| 1. |
- Ademuyiwa, Adesoji O., et al.
(författare)
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Determinants of morbidity and mortality following emergency abdominal surgery in children in low-income and middle-income countries
- 2016
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Ingår i: BMJ Global Health. - : BMJ Publishing Group Ltd. - 2059-7908. ; 1:4
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Tidskriftsartikel (refereegranskat)abstract
- Background: Child health is a key priority on the global health agenda, yet the provision of essential and emergency surgery in children is patchy in resource-poor regions. This study was aimed to determine the mortality risk for emergency abdominal paediatric surgery in low-income countries globally.Methods: Multicentre, international, prospective, cohort study. Self-selected surgical units performing emergency abdominal surgery submitted prespecified data for consecutive children aged <16 years during a 2-week period between July and December 2014. The United Nation's Human Development Index (HDI) was used to stratify countries. The main outcome measure was 30-day postoperative mortality, analysed by multilevel logistic regression.Results: This study included 1409 patients from 253 centres in 43 countries; 282 children were under 2 years of age. Among them, 265 (18.8%) were from low-HDI, 450 (31.9%) from middle-HDI and 694 (49.3%) from high-HDI countries. The most common operations performed were appendectomy, small bowel resection, pyloromyotomy and correction of intussusception. After adjustment for patient and hospital risk factors, child mortality at 30 days was significantly higher in low-HDI (adjusted OR 7.14 (95% CI 2.52 to 20.23), p<0.001) and middle-HDI (4.42 (1.44 to 13.56), p=0.009) countries compared with high-HDI countries, translating to 40 excess deaths per 1000 procedures performed.Conclusions: Adjusted mortality in children following emergency abdominal surgery may be as high as 7 times greater in low-HDI and middle-HDI countries compared with high-HDI countries. Effective provision of emergency essential surgery should be a key priority for global child health agendas.
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| 2. |
- Abbafati, Cristiana, et al.
(författare)
-
- 2020
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Tidskriftsartikel (refereegranskat)
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| 3. |
- Affognon, Hippolyte, et al.
(författare)
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Ethnic groups' knowledge, attitude and practices and Rift Valley fever exposure in Isiolo County of Kenya
- 2017
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Ingår i: PLoS Neglected Tropical Diseases. - : Public Library of Science (PLoS). - 1935-2727 .- 1935-2735. ; 11:3
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Tidskriftsartikel (refereegranskat)abstract
- Rift Valley fever (RVF) is an emerging mosquito-borne viral hemorrhagic fever in Africa and the Arabian Peninsula, affecting humans and livestock. For spread of infectious diseases, including RVF, knowledge, attitude and practices play an important role, and the understanding of the influence of behavior is crucial to improve prevention and control efforts. The objective of the study was to assess RVF exposure, in a multiethnic region in Kenya known to experience RVF outbreaks, from the behavior perspective. We investigated how communities in Isiolo County, Kenya were affected, in relation to their knowledge, attitude and practices, by the RVF outbreak of 2006/2007. A cross-sectional study was conducted involving 698 households selected randomly from three different ethnic communities. Data were collected using a structured questionnaire regarding knowledge, attitudes and practices that could affect the spread of RVF. In addition, information was collected from the communities regarding the number of humans and livestock affected during the RVF outbreak. This study found that better knowledge about a specific disease does not always translate to better practices to avoid exposure to the disease. However, the high knowledge, attitude and practice score measured as a single index of the Maasai community may explain why they were less affected, compared to other investigated communities (Borana and Turkana), by RVF during the 2006/2007 outbreak. We conclude that RVF exposure in Isiolo County, Kenya during the outbreak was likely determined by the behavioral differences of different resident community groups. We then recommend that strategies to combat RVF should take into consideration behavioral differences among communities.
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| 4. |
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| 5. |
- Ahmed Hassan Ahmed, Osama, 1972-
(författare)
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Rift Valley fever : challenges and new insights for prevention and control using the “One Health” approach
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Rift Valley fever (RVF) is an emerging viral zoonosis that causes frequent outbreaks in east Africa and on the Arabian Peninsula. The likelihood of RVF global expansion due to climate change and human anthropogenic factors is an important issue. The causative agent, RVF virus, is an arbovirus that is transmitted by several mosquito species and is able to infect a wide range of livestock as well as people. The infection leads to mass abortions and death in livestock and a potentially deadly hemorrhagic fever in humans. RVF has severe socio-economic consequences such as animal trade bans between countries, disruption of food security, and economic disaster for farmers and pastoralists as well as for countries. Human behavior such as direct contact with infected animals or their fluids and exposure to mosquito bites increases the risk for contracting the disease.To better understand the challenges associated with RVF outbreaks and to explore prevention and control strategies, we used the One Health approach. The local community had to be involved to understand the interaction between the environment, animals, and humans. We focused on Sudan, Saudi Arabia, and Kenya. First, we systematically reviewed the literature and then we performed cross sectional community-based studies using a special One Health questionnaire. Climatic and remote sensing data were used in combination with statistics to develop a sub-region predictive model for RVF.For both Saudi Arabia and Sudan, the ecology and environment of the affected areas were similar. These areas included irrigation canals and excessive rains that provide an attractive habitat for mosquito vectors to multiply. The surveillance systems were unable to detect the virus in livestock before it spread to humans. Ideally, livestock should serve as sentinels to prevent loss of human lives, but the situation here was reversed. Differences between countries regarding further spread of RVF was mainly determined by better economic and infrastructure resources.In Sudan, there was a lack of knowledge and appropriate practices at the studied community regarding RVF disease symptoms and risk factors for both animals and humans. The community was hesitant in notifying the authorities about RVF suspicion in livestock due to the lack of a compensation system. The perceived role of the community in controlling RVF was fragmented, increasing the probability of RVF transmission and disease.In Kenya, our study found that better knowledge about RVF does not always translate to more appropriate practices that avoid exposure to the disease. However, the combination of good knowledge, attitudes, and practices may explain why certain communities were less affected. Strategies to combat RVF should consider socio-cultural and behavioral differences among communities. We also noticed that RVF outbreaks in Kenya occurred in regions with high livestock density exposed to heavy rains and wet soil fluxes, which could be measured by evapotranspiration and vegetation seasonality variables. We developed a RVF risk map on a sub-regional scale. Future outbreaks could be better managed if such relevant RVF variables are integrated into early warning systems.To confront RVF outbreaks, a policy is needed that better incorporates ecological factors and human interactions with livestock and environment that help the RVF pathogen spread. Early detection and notification of RVF is essential because a delay will threaten the core of International Health Regulations (IHR), which emphasizes the share of information during a transboundary disease outbreak to avoid unnecessary geographical expansion.
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| 6. |
- Allard, Ingrid
(författare)
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Achieving building energy performance : requirements and evaluation methods for residential buildings in Sweden, Norway, and Finland
- 2015
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Building energy performance has always been important in the cold climate of Sweden, Norway and Finland. To meet the goal that all new buildings should be nearly zero-energy buildings by 2020, set in the EU directive 2010/31/EU [1] on the energy performance of buildings (EPBD recast), the building sector in Europe now faces a transition towards buildings with improved energy performance. In such a transition, a discussion is needed about the objective of the improvement – why, or to what end, the building energy performance should be improved. The objective of improving building energy performance is often a political decision, but scientific research can contribute with knowledge on how the objectives can be achieved.This thesis addresses how the indicators used in the requirements used to achieve building energy performance in Sweden, Norway, and Finland, and the methods used to evaluate these requirements, reflect building energy performance. It also addresses difficulties in achieving comparable and verifiable indicators in evaluations of building energy performance. The research objective has two parts: to review, compare, and discuss (i) requirements and (ii) evaluation methods used to achieve energy performance of residential buildings in Sweden, Norway and Finland. The work in this thesis includes reviews of the requirements used in national building codes and passive house criteria to achieve building energy performance, of methods used to evaluate compliance with such requirements, and of methods used specifically to evaluate the indicator Envelope Air Tightness. The results show that different sets of indicators are used to achieve building energy performance in the studied building codes and passive house criteria. The methods used to evaluate compliance with requirements used to achieve building energy performance are also different, but calculation methods are generally more often used than measurement methods. The calculation- and measurement methods used are often simple. A methodology to analyze the deviation between predictions- and measurements of building energy performance (the performance gap) was developed, to investigate the effects of different evaluation methods on different indicators used to achieve building energy performance. The methodology was tested in a case-study. This study indicated that the choice of method affects which parts of the performance gap reflected in the indicators Supplied Energy (see Terminology), Net Energy (see Terminology), and Overall U-value. Among the reviewed methods to evaluate air tightness, the Fan/Blower Door Pressurization is well known and preferred by professionals in the field. The results in this thesis may be useful when choosing indicators and evaluation methods to achieve different objectives of improving building energy performance and in the quest towards comparable and verifiable indicators used to achieve building energy performance.
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| 7. |
- Allard, Ingrid, 1986-, et al.
(författare)
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Energy evaluation methods for residential buildings in Nordic countries
- 2012
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Ingår i: Proceeding of the Technoport Conference. - : Elsevier.
-
Konferensbidrag (refereegranskat)abstract
- To meet the goals of the directive 2010/31/EU on the energy performance of buildings, the building sector in Europe now faces a transition towards more energy efficient buildings. Research and development of new energy solutions and technology will be necessary for the transition and the importance of measuring and evaluating building energy performance increases. This paper attempts to review and evaluate different methods that are commonly used to analyze energy performance in residential buildings in Nordic countries, primarily in Sweden, Norway and Finland. A short international review of regulations is also included. Some advantages and disadvantages of each method are discussed, as well as commonly used methods in the three countries. Although the three Nordic countries have similar climate conditions and building traditions, the study shows that there exist relatively large variations in defining parameters related to energy performance in residential buildings, such as energy use, heated area, and climate zones. The outcome of the regulations could be investigated by adapting the codes on a selected set of buildings. Common analyzing methods, or parts of methods, are found to be used in several countries. These aspects may be considered in further work to develop more accurate and easily comparable methods to evaluate energy performance for residential buildings in cold climate.
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| 8. |
- Allard, Ingrid, 1986-, et al.
(författare)
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Methods for air tightness analysis for residential buildings in Nordic countries
- 2012
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Ingår i: Methods for air tightness analysis forresidential buildings in Nordic countries. - Southampton : WIT Press. - 9781845646141 ; , s. 311-322
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Konferensbidrag (refereegranskat)abstract
- Envelope air tightness is one factor that has impact on the energy performance ofbuildings. The goals of the directive 2010/31/EU, on energy performance ofbuildings, raise the importance of building energy performance analysis in theprocess. Measurements of air tightness can be useful both when evaluatingbuilding energy performance and developing new building techniques. The aimof this paper is to review and evaluate methods to measure air tightness in bothnew and existing residential buildings in Sweden, Norway and Finland, based onan international literature study and a survey. The methods are categorized basedon a number of criteria to determine their suitability in different situations.Advantages and disadvantages of the methods are discussed, as well ascommonly used methods in the three countries. The review shows that thestandard ISO 9972 is used for verification in all three countries, but alternativesexist that might be more suitable in certain situations. Simpler methods are usedin the building process to increase air tightness. To achieve a comparablemeasurement, both common methods and commonly defined units are needed.
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| 9. |
- Allard, Ingrid, et al.
(författare)
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Methods for energy analysis of residential buildings in Nordic countries
- 2013
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Ingår i: Renewable & sustainable energy reviews. - : Pergamon-Elsevier Science. - 1364-0321 .- 1879-0690. ; 22, s. 306-318
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Forskningsöversikt (refereegranskat)abstract
- To meet the goals of the directive 2010/31/EU on the energy performance of buildings, the building sector in Europe now faces a transition towards more energy efficient buildings. Research and development of new energy solutions and technology will be necessary for the transition and the importance of analyzing building energy performance increases. This paper aims to review and evaluate different methods that are commonly used to analyze energy performance in residential buildings in Nordic countries, primarily in Sweden, Norway and Finland. A short international review of regulations is also included. The goal is to find commonly used methods and possibilities for the future. The introduced methods are summarized, categorized and compared based on their advantages and disadvantages. Although the three Nordic countries have similar climate conditions and building traditions, the review shows relatively large variations in the definitions of energy performance for residential buildings, as well as variations in how measurements and calculations are used in the methods for energy performance analysis. In the conducted review, methods, or parts of methods, are also found to be used. The methods used to analyze energy performance are found to be more similar than the concepts of energy performance itself in the three countries. These aspects may be considered in further work to develop an international policy practice for energy performance of residential buildings in cold climate.
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| 10. |
- Bashir, Rania Salah Eldien, et al.
(författare)
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A One Health perspective to identify environmental factors that affect Rift Valley fever transmission in Gezira state, Central Sudan
- 2019
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Ingår i: Tropical Medicine and Health. - : BioMed Central. - 1348-8945 .- 1349-4147. ; 47:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Rift Valley fever (RVF) is a zoonotic viral vector-borne disease that affects both animals and humans and leads to severe economic consequences. RVF outbreaks are triggered by a favorable environment and flooding, which enable mosquitoes to proliferate and spread the virus further. RVF is endemic to Africa and has spread to Saudi Arabia and Yemen. There is great concern that RVF may spread to previously unaffected geographic regions due to climate change. We aimed to better understand the spatiotemporal pattern of the 2007 RVF outbreak at the human-animal-environment interface and to determine environmental factors that may have effects on RVF occurrence in Gezira state, Sudan.Materials and methods: We compiled epidemiological, environmental, and spatiotemporal data across time and space using remote sensing and a geographical information system (GIS). The epidemiological data included 430 RVF human cases as well as human and animal population demographic data for each locality. The cases were collected from 41 locations in Gezira state. The environmental data represent classified land cover during 2007, the year of the RVF outbreak, and the average of the Normalized Difference Vegetation Index (NDVI) for 6 months of 2007 is compared with those of 2010 and 2014, when there was no RVF outbreak. To determine the effect of the environmental factors such as NDVI, soil type, and RVF case's location on the Blue Nile riverbank on RVF incidence in Gezira state, a multilevel logistic regression model was carried out.Results: We found that the outbreak in Gezira state occurred as a result of interaction among animals, humans, and the environment. The multilevel logistic regression model (F = 43,858, df = 3, p = 0.000) explained 23% of the variance in RVF incidence due to the explanatory variables. Notably, soil type (beta = 0.613, t = 11.284, p = 0.000) and NDVI (beta = - 0.165, t = - 3.254, p = 0.001) were the explanatory environmental factors that had significant effects on RVF incidence in 2007 in Gezira state, Sudan.Conclusions: Precise remote sensing and the GIS technique, which rely on environmental indices such as NDVI and soil type that are satellite-derived, can contribute to establishing an early warning system for RVF in Sudan. Future preparedness and strengthening the capacity of regional laboratories are necessary for early notification of outbreaks in animals and humans.
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| 11. |
- Gestrin, Magnus, et al.
(författare)
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Taket som terrass
- 2011
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Ingår i: Byggfakta projektnytt. - : Byggfakta. - 1101-8437. ; 23:6, s. 68-70
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Forskningsöversikt (populärvet., debatt m.m.)
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| 12. |
- Grundberg, Staffan, et al.
(författare)
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Dynamics of axially loaded and partially interacting composite beams
- 2012
-
Ingår i: Proceedings of the 15th European Conference on Composite Materials, Venice, 24-28 June 2012. - Venice. - 9788888785332
-
Konferensbidrag (refereegranskat)abstract
- The aim of this paper is to study the dynamics of partially interacting composite beams subjected to axial loads. The eigenfrequencies are derived for the simply supported composite beam subjected to an axial force. Measurements of the fundamental frequencies of a simply supported composite beam consisting of three layers connected by shear connectors are carried out considering different values of the applied axial force. The agreement between the theoretical and experimental results is discussed. It is also shown that the application of the axial force introduces frictional moments at the boundaries, which make the experimental boundary conditions deviate somewhat from those of an ideal simply supported beam.
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| 13. |
- Grundberg, Staffan, 1961-, et al.
(författare)
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Dynamics of axially loaded and partially Interacting composite beams
- 2012
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Ingår i: ECCM15. - : ECCM15. - 9788888785332
-
Konferensbidrag (refereegranskat)abstract
- The aim of this paper is to study the dynamics of partially interacting composite beams subjectedto axial loads, a situation occurring in e.g. beam-columns. The eigenfrequencies arederived for the simply supported composite beam subjected to an axial force. Measurements ofthe fundamental frequencies of a simply supported composite beam consisting of three layersare carried out considering different values of the applied axial force. The agreement betweenthe theoretical and experimental results is discussed. It is also shown that the application ofthe axial force introduces frictional moments at the boundaries, which make the experimentalboundary conditions deviate somewhat from those of an ideal simply supported beam.
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| 14. |
- Grundberg, Staffan, et al.
(författare)
-
Vibration of axially loaded and partially interacting composite beams
- 2014
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Ingår i: International Journal of Structural Stability and Dynamics. - Singapore : World Scientific. - 0219-4554 .- 1793-6764. ; 14:1, s. 1350047-
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Tidskriftsartikel (refereegranskat)abstract
- The vibrations of axially loaded composite beams with partial interaction are considered. The equations of motion and the pertaining boundary conditions are derived from Hamilton's principle. Mainly free — but also forced — vibrations are considered. The natural frequencies are calculated as a function of the axial force and the stiffness of the interaction between the layers. The analytical result obtained for the eigenfrequencies of the simply supported beam is taken as a starting point for an approximation of the eigenfrequencies of beams subject to other boundary conditions. The proposed approximation — which has no numerical fitting parameters — is shown to be in good agreement with the exact solutions, especially for the case of a beam clamped at both ends.
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| 15. |
- Hassan, Osama Ahmed, et al.
(författare)
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A need for One Health approach : lessons learned from outbreaks of Rift Valley fever in Saudi Arabia and Sudan
- 2014
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Ingår i: Infection Ecology & Epidemiology. - : CoAction Publishing. - 2000-8686. ; 4
-
Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: Rift Valley fever (RVF) is an emerging viral zoonosis that impacts human and animal health. It is transmitted from animals to humans directly through exposure to blood, body fluids, or tissues of infected animals or via mosquito bites. The disease is endemic to Africa but has recently spread to Saudi Arabia and Yemen. Our aim was to compare two major outbreaks of RVF in Saudi Arabia (2000) and Sudan (2007) from a One Health perspective.METHODS: Using the terms 'Saudi Arabia', 'Sudan', and 'RVF', articles were identified by searching PubMed, Google Scholar, and web pages of international organizations as well as local sources in Saudi Arabia and Sudan.RESULTS: The outbreak in Saudi Arabia caused 883 human cases, with a case fatality rate of 14% and more than 40,000 dead sheep and goats. In Sudan, 698 human cases of RVF were recognized (case fatality, 31.5%), but no records of affected animals were available. The ecology and environment of the affected areas were similar with irrigation canals and excessive rains providing an attractive habitat for mosquito vectors to multiply. The outbreaks resulted in livestock trade bans leading to a vast economic impact on the animal market in the two countries. The surveillance system in Sudan showed a lack of data management and communication between the regional and federal health authorities, while in Saudi Arabia which is the stronger economy, better capacity and contingency plans resulted in efficient countermeasures. Studies of the epidemiology and vectors were also performed in Saudi Arabia, while in Sudan these issues were only partly studied.CONCLUSION: We conclude that a One Health approach is the best option to mitigate outbreaks of RVF. Collaboration between veterinary, health, and environmental authorities both on national and regional levels is needed.
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| 16. |
- Hassan, Osama AB
(författare)
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An alternative method for evaluating the air tightness of building components
- 2013
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Ingår i: Building and Environment. - : Elsevier BV. - 0360-1323 .- 1873-684X. ; 67, s. 82-86
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Tidskriftsartikel (refereegranskat)abstract
- In this study, an alternative and general approach is advanced to evaluate the air leakage area and air infiltration rate in building envelope components such as exterior/internal walls and floors. In this method, the leakage area is determined with the help of acoustical and physical methods by measuring the sound reduction index of the building. The air flow rate through air leaks is determined with the help of leakage area and pressure difference over the floor/wall. The heat losses and convective moisture rate through leaks in the building are subsequently evaluated with the help of the calculated air infiltration rate.(C) 2013 Elsevier Ltd. All rights reserved.
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| 17. |
- Hassan, Osama A. B.
(författare)
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Application of value - focused thinking on the environmental selection of wall structures
- 2004
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Ingår i: Journal of Environmental Management. - : Elsevier BV. - 0301-4797 .- 1095-8630. ; 70:2, s. 181-187
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Tidskriftsartikel (refereegranskat)abstract
- The decision of selecting building structures with respect to the environmental demand is an issue commonly addressed in environmental management. In this paper, the importance of considering the decision analysis technique value-focused thinking in the environmental selection of wall structures is investigated. In this context, a qualitative value model is developed in which the external and internal environmental factors are considered. The model is applied on a case study in which a decision should be made on three categories of exterior wall structures: wood, masonry and concrete. It is found that the wall structure made of wood is the most compatible option with respect to the external and internal environmental requirements of building structures.
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| 18. |
- Hassan, Osama A.B., et al.
(författare)
-
Dynamics of partially interacting composite beams
- 2012
-
Ingår i: Proceedings of the 15th European Conference on Composite Materials, Venice, 24-28 June 2012. - Venice. - 9788888785332
-
Konferensbidrag (refereegranskat)abstract
- The dynamic behaviour of layered composite beams with partial interaction is analysed using variational calculus. The theoretical results are compared with those from dynamic tests on simply supported beams with varying shear connection stiffness between the layers. The influence of the shear connection stiffness on the flexural natural frequencies, flexural deflection and damping is investigated. A good agreement between the analytical and experimental results is obtained
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| 19. |
- Hassan, Osama. A.B. 1969-
(författare)
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Dyslexia and learning in view of the socio-cultural theory and development psychology
- 2023
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Ingår i: Social Science & Humanities Open. - Amsterdam : Elsevier. - 2590-2911. ; 8:1, s. 100718-100718
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Tidskriftsartikel (refereegranskat)abstract
- This study attempts to apply the socio-cultural learning theory together with the developmental psychology theory to create a better insight into how learning and teaching methods can be made more efficient for university students who have reading and writing difficulties/dyslexia. Pedagogical and didactic methods are derived, based on the sociocultural perspective, Bronfenbrenner's ecological system theory and the author's observations as a teacher in the classroom to help minimize the problem of learning for students with dyslexia. Learning and the learning environment as dictated by these theories can enable the production of pedagogical and didactic methods to streamline the learning of students with dyslexia within the framework of university education.
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| 20. |
- Hassan, Osama A.B. 1969-
(författare)
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Effect of foundation designs of passive house on the thermal bridges at the ground
- 2016
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Ingår i: Journal of Engineering, Design and Technology. - : Emerald Group Publishing Limited. - 1726-0531 .- 1758-8901. ; 14:4, s. 602-613
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Tidskriftsartikel (refereegranskat)abstract
- In this paper it is attempted to study the effect of different foundation designs of passive house on the resultant thermal bridges, at the junction between a wall and a slab on grade. The linear thermal transmittances of some newly developed foundations of passive house are determined. The compared foundation designs are L-element, U-element and foundation with foam glass technique. It is found that the special design of passive house foundation can considerably influence the heat flow through thermal bridges. The calculated linear thermaltransmittances of L-element, U- element and foundation with foam glass are 0.085 W/mK, 0.074 W/mK and 0.031 W/mK, respectively. In this context, it is proposed a new foundation design of passive house, which has relatively low heat loss through thermal bridges, calculated as 0.031 W/mK. The results are compared with the “default” ISO values used to evaluate the effect of thermal bridges in typical buildings. It is found that there is large difference between the calculated linear thermal transmittances at the investigated foundationsof passive house as compared to typical buildings.
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| 21. |
- Hassan, Osama A. B.
(författare)
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Isolation of buildings from ground-borne noise using a sand stratum
- 2004
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Ingår i: Building Acoustics. - : SAGE Publications. - 1351-010X .- 2059-8025. ; 11:2, s. 97-114
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Tidskriftsartikel (refereegranskat)abstract
- The effect of an elastic stratum in reducing ground-borne sound transmission in buildings to be built above railway tunnels is investigated, by considering a sand layer between the bedrock and load bearing elements of the building. It is assumed that the initial vibrational energy that propagates from the foundation is in the form of quasi-longitudinal waves. The complete model as presented by the author in a previous paper is considered. Calculated results are compared with previous results for a typical building and it is shown that a sand layer can considerably reduce upward sound transmission in the building. The results of a parametric study to investigate the influence of the type of load-bearing elements and the thickness of the layer, on transmission of structure-borne sound in the building, are presented.
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| 22. |
- Hassan, Osama A B
(författare)
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Learning theories and assessmant methodologies : an engineering educational perspective
- 2011
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Ingår i: European Journal of Engineering Education. - : Taylor & Francis Group. - 0304-3797 .- 1469-5898. ; 36:4, s. 327-339
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Tidskriftsartikel (refereegranskat)abstract
- This paper attempts to critically review theories of learning from the perspective of engineering education in order to align relevant assessment methods with each respective learning theory, considering theoretical aspects and practical observations and reflections. The role of formative assessment, taxonomies, peer learning and educational policy as regards promoting the learning of engineering is discussed. It is suggested that an integrated learning method in which cognitive levels, social factors and teamwork and behaviouristic elements are integrated will optimise the learning process on an engineering course. Moreover, assessment of learning should not be isolated from views of teaching and the learning methods employed by the university teacher.
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| 23. |
- Hassan, Osama A. B., 1969-
(författare)
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New Methods for Reducing Ground-Borne Noise in Buildings above Railway Tunnels
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The rapid expansion of major cities in the west Europeancountries has accentuated the need to exploit every potentialsite for new establishments, e.g. areas over train tunnels andnear railway tracks in general. A significant impediment toexploit such areas is the structure-borne noise generated bythe train traffic, which is transmitted into buildings via theground. Reliable prediction methods and cost-effective noisecontrol measures are therefore needed and are also the objectof the present work. In this thesis, the studied buildings areconsidered as wave-guides for the sound transmitted from theground. The work is restricted to the case of hard ground suchas granite. The chosen technique permits comparison betweendifferent potential measures to reduce the transmission ofstructure-borne sound upward in buildings. It is shown that thedesign of the load-bearing structures is important in thiscontext, and a design with relocated columns has givenpromising results. It is also shown that the stiffness of theground plays an important role in the transmission process.This leads to the idea that a sand layer between the foundationof the building and the bedrock may reduce the transmission.New methods have thus been developed in the course of this workto evaluate the stiffness of the layer using approximate andexact techniques. Results are presented and a comparison ismade with previous results for a "normal" building and it isshown that the insertion of sand layer has a potential toconsiderably reduce the sound level in the building.Keywords:Ground-borne noise, railway noise, in-planewaves, wave-guides, scattering, propagation constant, inputmobility, elastic stratum, dual integral equations.
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| 24. |
- Hassan, Osama, 1969-, et al.
(författare)
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A comparative study between glulam and concrete columns in view of design, economy and environment
- 2022
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Ingår i: Case Studies in Construction Materials. - Amsterdam, Netherlands : Elsevier. - 2214-5095. ; 16
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, it is attempted to study possible sustainability solutions for building structures. In this context, comparisons are made between two load-bearing columns with different building materials – glued laminated timber and concrete – with regard to structural design, economic consequences and the emission of greenhouse gases. In terms of structural design, the results show that with small axial forces, glulam columns will result in smaller cross-sectional areas compared to concrete columns. However, at larger axial forces, concrete columns will result in smaller cross-sectional areas than glulam columns. An increased column length also means larger dimensions for glulam columns, but this does not always apply to concrete columns. With respect to environmental impact, it is shown that using glulam columns is the more environmentally friendly option. From an economic point of view, the cost estimates for glulam and concrete columns may vary depending on the country and the abundance of the construction material. In Sweden, a forest-rich country, it is shown that the costs for both column types are quite similar considering small axial loads. At higher axial loading, concrete is generally the cheaper alternative.
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| 25. |
- Hassan, Osama Ahmed, et al.
(författare)
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One Health early warning and response system for zoonotic diseases outbreaks : Emphasis on the involvement of grassroots actors
- 2023
-
Ingår i: Veterinary medicine and science. - : John Wiley & Sons. - 2053-1095. ; 9:4, s. 1881-1889
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Emerging and reemerging zoonotic diseases have become a global concern due to their frequent occurrence. Large delays between onset of emerging zoonotic disease outbreaks and their reporting and control are indicative of weak animal and human health systems.Objectives: The objective of this paper is to tackle the time delay by suggesting a One Health Early Warning and Response System (OH-EWRS) aiming at improving the surveillance and notification of zoonotic diseases by strengthening ‘bottom-up’ approaches and systems for early detection, especially in hot spot areas where they emerge.Methods: In this conceptual paper, we searched online database including PubMed, Google and Google Scholar to explore the scientific landscape for zoonotic diseases and One Health Early Warning and Response Systems published in English up to December, 2020. In addition, the authors made use of their own expertise and critically reviewed the retrieved papers that were found to be of relevance as the three authors are experts in their own fields, coming from different backgrounds, but are all working to improve the prevention and control of zoonotic disease outbreak.Results: The OH-EWRS advocates for collaboration between relevant stakeholders including nongovernmental organisations, country offices of international and intergovernmental technical organisations, governmental bodies, research institutes, the private sector and local communities with the aim of an integrated One Health prevention and control system. The OH-EWRS considers various priorities and objectives of the different stakeholders, taking into account possible conflict of interests and considering the need for trust, transparency and mutual benefits.Conclusions: Although the operationalisation, governance and institutionalisation of the OH-EWRS should be the responsibility of government bodies, inputs from and feedback to relevant stakeholders through a bottom-up and top-down approach are essential elements for the application of the successful operationalisation of a OH-EWRS.
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| 26. |
- Hassan, Osama, 1969-
(författare)
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A Simplified Procedure to Determine the Deflection of Statically Indeterminate Structures
- 2014
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Ingår i: International Journal of Aerospace and Lightweight Structures. - Singapore : Research publishing. - 2010-4286 .- 2010-4294. ; 4:4, s. 241-253
-
Tidskriftsartikel (refereegranskat)abstract
- In the study presented here, the problem of calculating deflection of stati-cally indeterminate continuous beams and structural frames is addressed. Theelastic line equation, taught in many standard courses in structural mechan-ics is used to determine the structure deflections.In the investigated method,the structure is divided into a simply supported members in which the elas-tic line equation is applied to calculate the deflection shape of the structure.The results are compared with the finite element method (FEM) and goodagreement is obtained. Moreover, the advantage of this method is that it issimplified, general, not time-consuming, and it can be standardised to thistype of structures.
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| 27. |
- Hassan, Osama, 1969-
(författare)
-
A simplified structural analysis of statically indeterminate continuous thick beams
- 2016
-
Ingår i: International Journal of Mechanical Engineering Education. - : Sage Publications. - 0306-4190 .- 2050-4586. ; 44:4, s. 257-271
-
Tidskriftsartikel (refereegranskat)abstract
- In the study presented here, a simplified exact analytical solution of the problem of indeterminate continuous beams is derived and compared with the numerical solution, finite element. For the analytical method, the structure is divided into a simply supported element with internal support moments. The moments are first calculated with the help of boundary rotation conditions by taking into account both the shear andbending deformations. Second, the deflection functions of the beam members are derived. The results of a two-span continuous beam show that both methods yield an excellent agreement. The advantage of the presented method is that it is simplified, general, not time-consuming, and it can be standardized to this type of structures. Solution methods discussed in this paper can be of interest within the framework of mechanical and civil engineering education in which bending and shear of thick beamsare taught.
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| 28. |
- Hassan, Osama Ahmed, et al.
(författare)
-
The 2007 rift valley Fever outbreak in Sudan
- 2011
-
Ingår i: PLoS Neglected Tropical Diseases. - San Francisco, CA : Public Library of Science. - 1935-2727 .- 1935-2735. ; 5:9
-
Forskningsöversikt (refereegranskat)abstract
- Rift Valley fever (RVF) is a neglected, emerging, mosquito-borne disease with severe negative impact on human and animal health and economy. RVF is caused by RVF virus (RVFV) affecting humans and a wide range of animals. The virus is transmitted through bites from mosquitoes and exposure to viremic blood, body fluids, or tissues of infected animals. During 2007 a large RVF outbreak occurred in Sudan with a total of 747 confirmed human cases including 230 deaths (case fatality 30.8%); although it has been estimated 75,000 were infected. It was most severe in White Nile, El Gezira, and Sennar states near to the White Nile and the Blue Nile Rivers. Notably, RVF was not demonstrated in livestock until after the human cases appeared and unfortunately, there are no records or reports of the number of affected animals or deaths. Ideally, animals should serve as sentinels to prevent loss of human life, but the situation here was reversed. Animal contact seemed to be the most dominant risk factor followed by animal products and mosquito bites. The Sudan outbreak followed an unusually heavy rainfall in the country with severe flooding and previous studies on RVF in Sudan suggest that RVFV is endemic in parts of Sudan. An RVF outbreak results in human disease, but also large economic loss with an impact beyond the immediate influence on the directly affected agricultural producers. The outbreak emphasizes the need for collaboration between veterinary and health authorities, entomologists, environmental specialists, and biologists, as the best strategy towards the prevention and control of RVF.
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| 29. |
- Hassan, Osama Ahmed, 1972-, et al.
(författare)
-
The One Health approach to identify knowledge, attitudes and practices that affect community involvement in the control of Rift Valley fever outbreaks
- 2017
-
Ingår i: PLoS Neglected Tropical Diseases. - : Public Library of Science (PLoS). - 1935-2727 .- 1935-2735. ; 11:2
-
Tidskriftsartikel (refereegranskat)abstract
- Rift Valley fever (RVF) is a viral mosquito-borne disease with the potential for global expansion, causes hemorrhagic fever, and has a high case fatality rate in young animals and in humans. Using a cross-sectional community-based study design, we investigated the knowledge, attitudes and practices of people living in small village in Sudan with respect to RVF outbreaks. A special One Health questionnaire was developed to compile data from 235 heads of household concerning their knowledge, attitudes, and practices with regard to controlling RVF. Although the 2007 RVF outbreak in Sudan had negatively affected the participants' food availability and livestock income, the participants did not fully understand how to identify RVF symptoms and risk factors for both humans and livestock. For example, the participants mistakenly believed that avoiding livestock that had suffered spontaneous abortions was the least important risk factor for RVF. Although the majority noticed an increase in mosquito population during the 2007 RVF outbreak, few used impregnated bed nets as preventive measures. The community was reluctant to notify the authorities about RVF suspicion in livestock, a sentinel for human RVF infection. Almost all the respondents stressed that they would not receive any compensation for their dead livestock if they notified the authorities. In addition, the participants believed that controlling RVF outbreaks was mainly the responsibility of human health authorities rather than veterinary authorities. The majority of the participants were aware that RVF could spread from one region to another within the country. Participants received most their information about RVF from social networks and the mass media, rather than the health system or veterinarians. Because the perceived role of the community in controlling RVF was fragmented, the probability of RVF spread increased.
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| 30. |
- Hassan, Osama, 1969-
(författare)
-
An integrated approach to assessing the sustainability of buildings
- 2016
-
Ingår i: Journal of Engineering, Design and Technology. - London : Emerald Group Publishing Limited. - 1726-0531 .- 1758-8901. ; 14:3, s. 835-850
-
Tidskriftsartikel (refereegranskat)abstract
- The sustainability of the built environment is increasingly becoming an urgent issue for modern society. In this context, assessing the sustainable development of buildings will be an effective tool in managing and monitoring the progress of the sustainability performance on a local and/or global scale. In this paper, there is an attempt to integrate two methods of assessing the sustainability of buildings. The first method applies the concept of composite indicators. The other method applies the weighted utility function, using the value-focused thinking approach of mathematically modelling and constructing composite indicators. A tentative index to evaluate the sustainability of buildings is proposed, based on this integrated approach. The suggested method can give the assessor the opportunity to analyse the potential improvement that can be carried out in order to improve the sustainable development of buildings in the long and short term. Finally, the role of benchmarking in improving the sustainability performance of buildings is discussed in relation to the suggested method.
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| 31. |
- Hassan, Osama, 1969-, et al.
(författare)
-
Assessment of human-induced vibrations in composite timbre floors
- 2012
-
Ingår i: Proceedings of the 15th European Conference on Composite Materials. - Italien. - 9788888785332
-
Konferensbidrag (refereegranskat)abstract
- The authors investigate the human induced vibrations in typical composite timber floors inresidential buildings. Assessment methods given in different design codes and guidelines,such as the Eurocode, are discussed. A case study analysis based on the differentmethodologies is carried out to assess the acceptability of a specific timber floor. Twoextreme cases are considered: full and non-composite action. It is shown that compositeaction improves the floor acceptability for general residential applications. The limitations ofthe different criteria given in the codes and guidelines for assessing floor vibrations in timberfloor structures are discussed and, also, the possible improvement of these criteria.
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| 32. |
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| 33. |
- Hassan, Osama, 1969-, et al.
(författare)
-
Cross-laminated timber flooring and concrete slab flooring : A comparativestudy of structural design, economic and environmental consequences
- 2019
-
Ingår i: Journal of Building Engineering. - : Elsevier. - 2352-7102. ; 26, s. 1-16
-
Forskningsöversikt (refereegranskat)abstract
- This paper compares cross-laminated timber (CLT) flooring and concrete slab flooring with respect to structural design, cost analysis, and greenhouse gas emissions. The effect of floor span on design values, costs, and carbondioxide emissions is analysed in terms of structural design, economy, and environmental impact. Different crosssections are chosen for this purpose. The study shows that CLT flooring has significantly lower emissions ofclimate-impact greenhouse gases, and its ability to store carbon is significantly greater than the capacity of concrete storage. From an economic point of view, the CLT material is more expensive than concrete. However, the estimated “ready-to-assemble” cost of both floor types is quite similar. The study shows that CLT flooring can compete with a concrete slab floor when it comes to a span as wide as 7m without violating the structural requirements. However, with an increase in span, it is more difficult to meet the requirements for vibration for aCLT floor than for a concrete slab. At shorter spans, the moment capacity is often a decisive factor for concrete slabs while deformation is the decisive factor for a CLT floor. For larger spans, resonance frequency and deformation are crucial for the CLT floor, while the long-term deformation of the concrete is the decisive factor in structural design.
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| 34. |
- Hassan, Osama, 1969-, et al.
(författare)
-
Dynamics of partially interacting composite beams
- 2012
-
Ingår i: Proceedings of the 15th European Conference on Composite Materials. - 9788888785332
-
Konferensbidrag (refereegranskat)abstract
- In this work, a combined variational calculus and experimental approach are used to characterize the structural vibration behaviour of layered composite beams. Experimental dynamic tests are carried out on a composite simply supported beam with varied interaction strength between the layers. From the results, the influence of connections on the flexural natural frequencies, flexural deformation and damping is investigated. A good agreement between the derived theoretical equations and experimental results is obtained.
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| 35. |
- Hassan, Osama, 1969-
(författare)
-
Dyslexi och lärande utifrån det sociokulturella perspektivet och utvecklingspsykologin
- 2023
-
Ingår i: Konferens i pedagogiskt arbete, 2023 -Book of abstracts. - Norrköping : Linköpings universitet. - 9789180752831 - 9789180752848
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Högt ställda kunskapskrav på universitet och kunskapsmässig spridning i klasserna bidrar till att studenter med dyslexi får svårt att hinna med den ordinarie undervisningen varför en undervisning anpassad efter studenters olika behov och förutsättningar tycks vara av stor betydelse. Många högskolestudenter med dyslexi behöver därför mer och bättre pedagogiskt stöd under sina studier. Det finns gedigen forskning som handlar om hur att stimulerar lärande hos barn, och ungdomar med dyslexiproblem. Se till exempel Ekelund (2021), Cederquist (2021), Lithari (2019). Med hänsyn till universitetsstudenter, se t ex Donato m fl. (2022). Denna artikel syftar till att tillämpa dock lärandet utifrån utvecklingspsykologiteorin och den sociokulturella lärandeteorin för att skapa bättre insyn i hur lärandet kan effektiviseras hos högskolestudenter med läs- och skrivsvårigheter/dyslexi, baserad på författarens observationer som lärare i klassen. Varför väljas specifikt dessa två teorier, beror på området av intresse för dessa två teorier behandlar. Båda teorier fokuserar om samspelet mellan individ och miljö och detta tycks vara av stor betydelse för lärandeutveckling hos studenter som lider av dyslexi. Vidare är det praktiskt att tillämpa pedagogiska och didaktiska principer som dikterade av dessa teorier inom ramen för högskoleutbildning.
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| 36. |
- Hassan, Osama, 1969-
(författare)
-
Dyslexi och lärande utifrån det sociokulturella perspektivet och utvecklingspsykologin
- 2023
-
Ingår i: Den 9:e utvecklingskonferensen för Sveriges ingenjörsutbildningar. - Västerås : Mälardalens universitet. - 9789174856200 ; , s. 65-77
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Syftet med denna artikel är att tillämpa den sociokulturella lärandeteorin tillsammans med utvecklingspsykologiteorin för att skapa bättre insyn i hur lärandet kan effektiviseras hos universitetsstudenter med läs- och skrivsvårigheter/dyslexi. Med detta som bakgrund föreslås några pedagogiska och didaktiska strategier, baserade på författarens observationer som lärare i klassen samt studenters feedback.
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| 37. |
- Hassan, Osama, 1969-
(författare)
-
Effect of wooden floorboards on the vibration of timber floor
- 2024
-
Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 14:1
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- This study is aimed at investigating those parameters related to timber fooring that can afect the acceptability of vibration behaviour of a timber foor in a residential building in view of the criteria stated in Eurocode EC5. The timber foor investigated is made of OSB/3 foorboards and timber joists. The parameters that are investigated in this study are thickness of fooring, foor joist span, joist spacing and connection of foorboards to the joists. In this context, two cases are considered. First: the fooring is nailed or screwed to the joists and no composite action or interaction is obtained between joists and foorboards. Second: the fooring is glued sufciently to the joists and full interaction is obtained. The result suggests that glued foorboards perform much better with respect to natural frequency, static defection and peak foor velocity than nailed or screwed foorboards. In almost all cases of glued foorboards, the result complies fully with the Eurocode 5 design vibration requirements. However, as foor lengths increase, the static defection will increase beyond the allowable limit, especially for relatively thin foor panels and relatively widely spread joists. For both cases, increasing foorboards thickness and decreasing the joist span by adding more beams can yield even better results to satisfy the requirement of vibration comfort.
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| 38. |
- Hassan, Osama, 1969-, et al.
(författare)
-
Estimation of drying time of fresh concrete slabs: acomparative study
- 2017
-
Ingår i: Journal of Engineering, Design and Technology. - : Emerald Group Publishing Limited. - 1726-0531 .- 1758-8901. ; 15:2, s. 134-148
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose – The purpose of this study is to attempt to compare experimental results for a number of modelsfor the prediction of the drying time of new concrete floors. The investigated methods are the table method, the Swedish Concrete Association (SCA) method and the free computer programme TorkaS 3.2.Design/methodology/approach – The comparison is based on moisture measurements of four differentfloor specimens. The specimens have different ratios (w/c 0.38, 0.6 and 0.7).Findings – The results show that there is a good agreement between the table method and the measured values on the specimens with high water-cement ratio (w/c 0.6 and 0.7). However, the deviation becomes greater at lower water-cement ratio (w/c 0.38). TorkaS also resulted in a good agreement with the measurements. However, it is noted that as the drying time increases, the programme exhibits a slowdehydration trend at higher w/c ratios. The SCA method shows various results within the permissible deviation. Moreover, the moisture distribution in concrete with high w/c ratios is found to be mainly influencedby moisture diffusion and little by self-desiccation.Research limitations/implications – This study is limited to concrete slabs that are drying from oneside in an enclosed building with an heating, ventilation and air conditioning (HVAC) system operating normally. Moreover, this study concerns concrete without special additives (e.g. silica fumes), which can beused in some specific cases to accelerate or retard the hydration (cure) process.Practical implications – These compared methods are used widely in Sweden; therefore, it will be interesting to understand their applicability range. Another focus in this paper is to investigate how the effect of self-desiccation of concrete is related to the w/c ratios, taking into consideration the result of these predictionmodels.Social implications – The paper can suit academic researchers, as well as the commercial industries, in asense that the comparative study will pave a way to the best method to be used for drying time estimation.Originality/value – The paper contains new information and could be useful to researchers and commercial industries.
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| 39. |
- Hassan, Osama, 1969-, et al.
(författare)
-
Experimental Analysis of Composite Timbre-Concrete Wall Element
- 2012
-
Ingår i: Proceedings of the 15th European conference on composite materials. - Venice. - 9788888785332
-
Konferensbidrag (refereegranskat)abstract
- The authors present an experimental and theoretical study on a composite or hybrid element used in residential and agricultural buildings. The composite wall element consists of timber studs connected to a concrete plate by means of nail plate shear connectors. Experimental results are presented and compared with an analytical model for partial composite action. A good agreement is obtained between the analytical and experimental results. Also, some suggestions to improve the design of the composite element are discussed.
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| 40. |
- Hassan, Osama
(författare)
-
Experimental investigations on the force mobility of an elastic stratum on a rigid base
- 2007
-
Ingår i: Acta Acoustica united with Acustica. - 1610-1928 .- 1861-9959. ; 93:1, s. 164-166
-
Tidskriftsartikel (refereegranskat)abstract
- This paper attempts to investigate experimentally the influence of base conditions on the mobility of a stratum on a rigid base. The results are compared with the theoretical results as presented by the author in a previous publication. It is shown that the obtained measurement results reasonably agree with the theory and that the base conditions of stratum on a rigid base do have a significant influence on the force mobility, particularly at resonance.
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| 41. |
- Hassan, Osama
(författare)
-
Experimental study on utilizing iron slag to stabilize Cr(VI)-contaminated soil
- 2010
-
Ingår i: WIT Transaction on Ecology and the Environment. - : WIT press. - 9781845644604 ; , s. 337-347
-
Konferensbidrag (refereegranskat)abstract
- A laboratory study is conducted to test the capacity of two types of iron slag to stabilize Cr(VI)-contaminated soils. The slag samples are incorporated with soils in different proportions and the resulting leachate is tested using batch experiments. The feasibility of using iron is demonstrated as concentrations up to 1000 mg Cr(VI)/kg in the leachate of an alkaline soil are reduced to 0,7 mg Cr(VI)/kg mix after 12 days, but to less than 5 mg Cr(VI)/kg mix after 7 days. Small particles size and L/S-ratio are, in most cases, favoured by the reducing agents to stabilize the contaminated soil. The study demonstrated that the iron slag can effectively stabilize Cr(VI)-contaminated soils.
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| 42. |
- Hassan, Osama, 1969-, et al.
(författare)
-
Experimental verification of static buckling of partially composite beams and beam-columns
- 2015
-
Ingår i: <em>Proceeding Advanced Materials World Congress</em>.
-
Konferensbidrag (refereegranskat)abstract
- The authors present an experimental study on static buckling of partially composite beams and beam-columns. In this context, a composite wall segment is tested consisting of timber studs connected to specially designed plywood board by means of shear connectors. The critical loads that characterise the buckling of timbre beams/columns with partial composite action are calculated both experimentally and theoretically. A good agreement is obtained between the analytical and experimental results. Further, it is discussed from the practical point of view that factors, which affect the deviation between the theoretical and experimental results.
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| 43. |
- Hassan, Osama
(författare)
-
Force mobility of an elastic stratum over a rigid base : Part I. Approximate solution
- 2006
-
Ingår i: Acta Acoustica united with Acustica. - 1610-1928 .- 1861-9959. ; 92:3, s. 378-389
-
Tidskriftsartikel (refereegranskat)abstract
- An approximate approach to derive the input mobility of an infinite elastic stratum on a rigid base is investigated. The excitation is due to a vertical force, which is applied via a small massless indenter with a circular base, fixed to the stratum. Two cases are investigated: a stratum with a fixed base and a stratum with a frictionless base. General expressions for the mobilities are derived from the equations of motion of an isotropic elastic medium. Using a numerical approach, the analytical results are evaluated up to a Helmholtz number k(L)d = 10, where k(L) is the wave number of the P- wave and d is the stratum depth. For small Helmholtz numbers, asymptotic expressions are derived analytically; the two evaluations agree well up to a Helmholtz number of 0.2 for the frictionless base and to 0.5 for the fixed base. It is shown that the mobilities for the two cases differ significantly at small Helmholtz numbers. This is mainly due to the influence of a propagating wave, which can exist only in the case of a frictionless base. It is also shown that the local deformations in the vicinity of the indenter are built up by low-frequency, non-propagating Lamb modes. Finally, the dispersion relations are evaluated up to a Helmholtz number k(L)d = 16.
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| 44. |
- Hassan, Osama
(författare)
-
Force mobility of an elastic stratum over a rigid base : Part II. Exact solution
- 2006
-
Ingår i: Acta Acoustica united with Acustica. - 1610-1928 .- 1861-9959. ; 92:3, s. 390-397
-
Tidskriftsartikel (refereegranskat)abstract
- The second part of this paper deals with the exact solution for the force mobility of an infinite elastic stratum with respect to a vertical force. The stratum rests on a rigid and frictionless foundation. The upper surface of the stratum is excited by a circular weightless indenter with a prescribed velocity; otherwise this surface is stress-free. The mixed boundary conditions result in dual integral equations, which are solved using analytical and numerical techniques. An exact analytical solution for the force mobility of the stratum is determined by using the method of resolvent kernel together with the residue theorem. The results are validated by comparisons with the results from a numerical solution using the quadrature method. It is shown that the results from an approximate solution as presented in the first part, where the prescribed velocity is exchanged for a presumed stress distribution, agrees well with the present results for low frequencies up to approximately the first thickness resonance, but not for higher frequencies.
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| 45. |
- Hassan, Osama, 1969-, et al.
(författare)
-
Glued laminated timber and steel beams : A comparative study of structural design, economic and environmental consequences
- 2018
-
Ingår i: Journal of Engineering, Design and Technology. - England : Emerald Group Publishing Limited. - 1726-0531 .- 1758-8901. ; 16:3, s. 398-417
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose – This paper compares glued laminated timber and steel beams with respect to structural design, manufacturing and assembly costs, and the amount of greenhouse gas emissions.Design/methodology/approach – This paper presents structural design requirements in conformance with EN 1993: Eurocode 5 and Eurocode 3. With the help of these standards, expressions are derived to evaluate the design criteria of the beams. Based on the results of life-cycle analysis, the economic properties and environmental impact of the two types of beam are investigated. In this paper, the effect of beam span on the design values, costs and carbon dioxide emissions is analyzed when investigating aspects of the structural design, economy and environmental impact. Different cross-sections are chosen for this purpose.Findings – The study shows that the glued laminated (abbreviated as glulam”) beams have a smaller tendency to lateral torsional buckling than the steel beams, and that they can be cheaper. From an environmental point of view, glulam beams are the more environmentally friendly option of the two beam materials. Furthermore, glulam beams may have a direct positive effect on the environment, considering the carbon-storage capacity of the wood. The disadvantage of glued wood is that larger dimensions are sometimes required.Research limitations/implications – Wind load and the effect of second-order effects have not been considered when analysing the static design. Only straight beams have been studied. Furthermore, the dynamic design of the beams has not been investigated, and the bearing pressure capacity of the supports has not been analyzed. We have investigated timber beams with a rectangular cross-section, and steel beams of rolled I-sections, known as “HEA profiles”. The cost analysis is based mainly on the manufacturing and assembly costs prevalent on the Swedish market. The only environmental impact investigated has been the emission of greenhouse gases. The design calculations are based on the European standards Eurocode 5 and Eurocode 3.Practical implications – To achieve sustainability in construction engineering, it is important to study the environmental and economic consequences of the building elements. By combining these two effects with the technical design of buildings made of steel and/or timber, the concept of sustainable development can be achieved in the long run. Social implications – The study concerns sustainability of building structures, which is an important of the sustainable development of the society. Originality/value – The paper contains new information, and will be useful to researchers and civil engineers.
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| 46. |
- Hassan, Osama, 1969-, et al.
(författare)
-
Lecablock, an Alternative Construction Material for the Exterior Walls of Passive House
- 2014
-
Ingår i: Journal of Building Construction and Planning Research. - : Scientific Research Publishing. - 2328-4889 .- 2328-4897. ; 2:2, s. 96-108
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper it is attempted to investigate the Leca blocks as sustainable construction material forthe exterior walls of passive house. The building physical properties of Leca design wall structureare studied along with the environmental impact and load-bearing capacity. To compare the results,a similar analysis is carried out considering the traditional wooden wall construction of passivehouses. The results showed that Leca design wall structure can be an alternative sustainablesolution to the traditional wooden wall structure of passive house, mainly due to its low U-value,its ability to handle moisture, and comparable structural load-bearing capacity. However, thewooden wall structure is more environmentally friendly than the Leca blocks due to its loweremissions to the environment and reduced energy use, especially during the manufacturing process.
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| 47. |
|
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| 48. |
- Hassan, Osama
(författare)
-
Monte Carlo simulations for the risk management of environmental pollution
- 2010
-
Ingår i: Journal of Environmental Assessment Policy and Management. - : World Scientific. - 1464-3332 .- 1757-5605. ; 12:1, s. 87-101
-
Tidskriftsartikel (refereegranskat)abstract
- This article attempts to adapt the Monte Carlo method to the quantitative risk management of environmental pollution. In this context, the feasibility of stochastic models to quantitatively evaluate the risk of chemical pollution is first discussed and then linked to a case study in which Monte Carlo simulations are applied. The objective of the case study is to develop a Monte Carlo scheme for evaluating the pollution in a lake environment. It is shown that the results can be of interest as they define the risk margins that are important to the sustainability of the ecosystem in general, and human health in particular. Moreover, assessing the environmental pollution with the help of the Monte Carlo method can be feasible and serve the purpose of investigating and controlling the environmental pollution, in the long and short terms.
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| 49. |
- Hassan, Osama, 1969-
(författare)
-
On the structural stability of timber members to Eurocode
- 2024
-
Ingår i: Mechanics based design of structures and machines. - : Taylor & Francis. - 1539-7734 .- 1539-7742.
-
Tidskriftsartikel (refereegranskat)abstract
- This study investigates the load-bearing behaviour of timber members subjected to combined compression and bending based on the guidelines of the standard Eurocode 5. In this context, two design approaches are stated to account for flexural buckling: the effective length method and the second-order analysis. Although Eurocode 5 states that second-order analysis can be carried out to check the stability of beam-columns, it does not mention how to formulate this analysis. This study investigates this case in order to develop alternative interaction formulae to check the stability of timber members subjected to simultaneously acting axial compression and bending moments with risk of buckling failure. Firstly, expressions are derived to formulate the interaction formulae based on second-order analysis. Secondly, the derivedinteraction formulae are compared with Eurocode 5 formulation. A parametric study is carried out to compare the two methods and the differences between results are discussed. The second-order analysis advanced in this paper can be an alternative tool to be used by the structural engineer to assess the stability of axially loaded members subjected to the risk of flexural buckling failure.
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| 50. |
- Hassan, Osama
(författare)
-
On the structural stability of timber members to Eurocode
- 2019
-
Ingår i: Mechanics based design of structures and machines. - : TAYLOR & FRANCIS INC. - 1539-7734 .- 1539-7742. ; 47:5, s. 647-657
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates the load-bearing behavior of timber members subjected to combined compression and bending based on the guidelines of the standard Eurocode 5. In this context, two design approaches are stated to account for flexural buckling: the effective length method and the second-order analysis. Although Eurocode 5 states that second-order analysis can be carried out to check the stability of beam-columns, it does not mention how to formulate this analysis. This study investigates this case in order to develop alternative interaction formulae to check the stability of timber members subjected to simultaneously acting axial compression and bending moments with risk of buckling failure. The second-order analysis advanced in this article can be an alternative tool to be used by the structural engineer to assess the stability of axially loaded members subjected to the risk of flexural buckling failure. Communicated by Francisco Javier Gonzalez Varela.
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