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- Andersson Granberg, Tobias, 1973-, et al.
(författare)
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Using Semi-professionals in Emergency Response
- 2016
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Ingår i: Proceedings of the 13th International Conference on Information Systems for Crisis Response and Management. - 9788460879848 ; , s. 1-6
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The term semi-professional can be used to denote occupational groups that do not have emergency response as their primary profession but who get additional responsibilities within rescue and response, e.g. by performing a first response or assisting the professional emergency services. In this study, four different groups of possible semi-professional resources are analyzed and compared. Similarities and differences between the four groups are discussed. Factors, important for the successful implementation of a cross-sector collaboration of this kind, are highlighted. The preliminary results show that all four groups have the potential to act as semi-professional resources within emergency response. Interestingly, the basic requirements are the same for all groups, despite different prerequisites.
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| 2. |
- Berghauser Pont, Meta, 1972, et al.
(författare)
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PST
- 2019
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Annan publikation (mjukvara/multimedium) (övrigt vetenskapligt/konstnärligt)abstract
- PST is a tool for performing space syntax and regular accessibility analyses. It currently consists of two main parts - a C++ and Python library called Pstalgo and a plugin for the desktop application QGIS.PST is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. The GNU General Public License is intended to guarantee your freedom to share and change all versions of a program--to make sure it remains free software for all its users.For latest download visit either the Chalmers publication page, or find "Releases" on the Github page.
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| 6. |
- Gasch, Tobias
(författare)
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Concrete as a multi-physical material with applications to hydro power facilities
- 2016
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- During its lifetime, a concrete structure is subjected to many different actions, ranging from mechanical loads to environmental actions. To accurately predict its integrity from casting and throughout its service life, a modelling strategy is required that considers mechanical loading but also implicitly accounts for physical effects such as temperature and moisture variations. This is especially true for large concrete structures found in many infrastructure applications such as bridges, nuclear power plants and dams. Modelling concrete as a multi-physical material is becoming an increasingly used approach for which large research efforts are being made, including the development of more refined mathematical and numerical methods as well as considering more physical and chemical variables in the coupled model.The research project, of which this licentiate thesis is the first phase, aims at investigating aging concrete structures at hydro power facilities, with focus on the internal structures of the power plants. This thesis presents a review of advanced mathematical methods and concepts for modelling aging concrete found in the literature which can later be applied to study such structures. The focus is on models that describe the deformational behaviour of concrete where aspects such as aging, cracking, creep and shrinkage are investigated. However, in order to accurately describe such phenomena, a multi-physical approach is adopted where moisture and temperature variations in the concrete are studied. Also, models that describe the chemical behaviour related to hydration and thus in extension aging, are also reviewed and introduced in the multi-physical framework. The use of such models are discussed in the context of the finite element method (FEM), in which coupled models are implemented, verified and applied in the appended papers using two different FE codes.Several verification examples are presented covering different aspects of the implemented models, both in isolation and coupled in a multi-physical setting. By comparing the numerical results with experimental data from the literature it can be shown that it is possible to predict most aspects of aging concrete that have been of interest here. While these examples are all on a laboratory scale, numerical examples and case studies are also provided that exemplify how the models can be applied on a structural scale. By using the developed analysis tools, valuable information and insights can be gained on aging concrete structures and these tools will in the next phase of the research project be applied to large concrete structures at hydro power facilities.
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| 7. |
- Gasch, Tobias
(författare)
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Multiphysical analysis methods to predict the ageing and durability of concrete
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- With the societal demand for sustainability and the increasing age of infrastructure, a crucial task for the civil engineering community is to improve the durability of concrete structures. This thesis aims to contribute to such development through theoretical studies using mathematical modelling and numerical simulations. During its service life, a concrete structure is subjected to many different actions, ranging from mechanical loads to chemical and physical processes. Hence, a sound modelling strategy requires multiphysics and the inclusion of coupled chemical and physical fields (e.g. temperature, moisture and cement hydration) in addition to methods that describe mechanical integrity of the material. Conditions and phenomena critical for concrete structures at hydropower facilities have been of particular interest to study.The thesis presents several mathematical models of various complexity to describe the multiphysical behaviour of concrete using a material point description. A significant focus is on models that describe the mechanical behaviour of concrete where aspects such as ageing, cracking, creep and shrinkage are investigated. For the creep behaviour, a state-of-the-art model based on the Microprestress–Solidification (MPS) theory is reviewed and further developed. The appended papers (III to IV) presents a mathematical framework for the modelling of durability aspects of concrete based on multiphase porous media theory. The governing equations are derived with the Thermodynamically Constrained Averaging Theory (TCAT) as a starting point. It is demonstrated how this framework can be applied to a broad variety of phenomena related to durability; from the casting and hardening of concrete to the long-term absorption of water into air-entrained concrete. The Finite Element Methods (FEM) is used to solve the proposed mathematical models, and their capabilities are verified using experimental data from the literature.The main research contribution is the development and evaluation of theoretical models that advance the understanding and improve knowledge of the ageing and durability of concrete and concrete structures. More precisely, it is shown how multiphysical models and the developed multiphase framework can be used to gain insights on the material behaviour of concrete at smaller scales while they are also applicable to structural-scale simulations. During all model development, the efficient solution of structural problems has been fundamental. Through case studies and several examples from the literature, it is exemplified how these models can be used to enhance the performance and thereby increase the durability of concrete structures.
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| 9. |
- Malm, Richard, et al.
(författare)
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Cracking in the concrete foundation for hydropower generators : Analyses of non-linear drying diffusion, thermal effects and mechanical loads
- 2013
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- An extensive program for improvement of the hydropower plants in Sweden is currently on-going. The aims are to secure future production and to maintain and further develop an already high dam safety.During inspection, cracks were discovered in the concrete foundation, near the stator and rotor spider supports, at some hydropower stations in Sweden. The cracks were believed to be related to the function of the stator supports and to new patterns of generator operation. In earlier times, the generators ran continuously, while nowadays there are many stops and starts, sometimes even several times during one day. The objective of this study is to understand the complex interaction between the power generating system (stator, rotor, turbine, etc.) and the supporting concrete structure. It is important from a dam safety perspective to determine the causes of the structural cracks that have been found in-situ.A three dimensional non-linear finite element model has been developed in order to analyse formation and propagation of the cracks. Several different load effects have been studied in this project in addition to the mechanical loads during operation. The new pattern of generator operation with several starts and stops lead for instance to variations in temperature which have been studied. Besides this, the uneven drying shrinkage of concrete has also been studied in this project. Thereby, the structural behaviour of a concrete foundation for the power generating system has been analysed taking into account the transient thermal and moisture gradients in combination with dead loads and some of the operational loads imposed to the foundation.The analyses shows that reinforced concrete structure that constitute a support to the generator is subjected to cracking due to the loads considered in this study, where the cracks near the supports are caused by a combination of mechanical loads, long-term drying shrinkage and temperature variations. The analyses showed that even after 20 years, the moisture content in the centre of the thicker part in the concrete foundation still had a high relative humidity. At the same time the concrete close to the free surfaces and the slender parts of the concrete foundation had reached the same relative humidity as the environment. Thereby, a large difference in drying shrinkage is obtained between different parts of the concrete foundation and thereby large forces due to restrain. The analyses showed that the drying shrinkage induced cracking inside the concrete foundation and especially close to the supports of the stator and the rotor spider which coincides with location of the cracks found in-situ.The results show that the cracks found in-situ can be simulated and explained with advanced numerical methods. The results also indicate that the dynamic effect from the loads caused by the power generating system have to be studied further, since a reduced structural stiffness due to cracking may result in larger loads imposed on the structure from the magnetic eccentricity and turbine imperfections or alternatively lead to a fatigue failure of for instance the reinforcement.
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| 10. |
- Nordström, Tobias
(författare)
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Predicting prostate cancer : on the use of biomarkers in prostate cancer diagnostics
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Aims: The aims of this thesis work were to answer the following questions. Paper I: How prevalent is testing and retesting with prostate-specific antigen (PSA)?; Paper II: Is a genetic score based on single-nucleotide polymorphisms (SNPs) informative regarding the risk of prostate cancer (PCa) in men with low PSA?; Paper III: Are the commercially available tests Prostate Health Index (PHI) and the four-kallikrein panel comparable in aiding biopsy decisions?; Paper IV: Do commonly used medications affect PSA and the risk of PCa? Methods: In Paper I and Paper IV, the population-based PSA cohort STHLM0 was used together with registry-based data. Paper I described limited-duration point prevalence of testing and survival analysis describing retesting with PSA. Paper IV determined differences in PCa risk and PSA level among men using aspirin, statin, metformin or no medication. Paper II included 172 men with PSA at 1‒3ng/ml. Participants were invited according to their genetic score and underwent prostate biopsy. Risk of prostate cancer was assessed using logistic regression. Paper III included 531 men who had undergone a first prostate biopsy. Predictive models were compared using receiver-operating characteristics (ROC/AUC) and calculation of biopsies that could be avoided. Results: Paper I. During a 9-year study period, 46%, 68%, and 77% of men without previous PCa and aged 50–59 years, 60–69 years, and 70–79 years, respectively, had a PSA test. The probability of retesting with PSA was PSA- and age-dependent, with a 26-month cumulative incidence of 0.34 if the first PSA value was < 1 ng/ml. Paper II. PCa was diagnosed in 47 of 172 men with PSA levels of 1‒3ng/ml (27%), with Gleason sum of ≥ 7 in 10 of them (5.8%). There was an increase in the odds ratio of 1.60 with increasing genetic risk score. The absolute difference in risk of positive biopsy was 19 percentage points, comparing the high and low genetic risk groups (37% vs. 18%). Paper III. The four-kallikrein panel showed AUCs of 69.0 when predicting PCa of any grade and 71.8 when predicting high-grade cancer (Gleason score ≥ 7). Similar values were found for PHI (70.4 and 71.1, respectively). Both models had higher AUCs than a base model with PSA value and age. Using a 10% predicted risk of high-grade PCa by the four-kallikrein panel or PHI = 39 as cutoff for biopsy saved 29% of the biopsies performed, at a cost of delayed diagnosis for 10% of the men with highgrade cancer. Paper IV. There were no significant associations between aspirin or any antidiabetic medication and the risk of PCa. Men using any statin had an increased risk of both high-grade PCa and PCa overall (OR = 1.25; OR = 1.16). Compared to men without the medication, the level of the first PSA was lower in men using aspirin, statin, metformin, or insulin. Conclusions: Although screening for PCa is not recommended in Sweden, PSA testing in Stockholm County was high in men aged over 50 years. A risk score based on SNPs predicts biopsy outcome in previously unbiopsied men with PSA levels of 1–3 ng/ml. Furthermore, we found that two blood tests, the PHI and the four-kallikrein panel, performed similarly in predicting prostate biopsy outcome. Introduction of such risk stratification tools could increase the proportion of men being classified in line with their true risk of PCa. We found no protective effect of aspirin, statins, or antidiabetics in terms of overall risk of prostate cancer or high-grade cancer.
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