| 1. |
- Abshirini, Ehsan, et al.
(författare)
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Flood hazard and its impact on the resilience of cities : An accessibility-based approach to amenities in the city of Gothenburg, Sweden
- 2017
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Ingår i: Proceedings - 11th International Space Syntax Symposium, SSS 2017. - : Instituto Superior Tecnico, Departamento de Engenharia Civil, Arquitetura e Georrecursos. - 9789729899447 ; , s. 36.1-36.15
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Konferensbidrag (refereegranskat)abstract
- In the wake of climate change and its impact on increasing the number and intensity of floods, adaptability of cities to and resistance against the flood hazard is critical to retain functionality of the cities. Vulnerability of urban infrastructure and its resilience to flooding from different points of view have been important and worth investigating for experts in different fields of science. Flood hazards as physical phenomena are influenced by form of the cities and thus the magnitude of their impacts can be intensified by urban infrastructures such as street networks and buildings (Bacchin et. al, 2011). In this paper, we aim to develop a method to assess the resilience of a river city (the city of Gothenburg in Sweden), which is prone to flood events, against such disturbances and find out how the city reacts to river floods and to what extent the city retains its accessibility to essential amenities after a flood occurs. To do so, collecting required data; we, firstly, simulate flood inundation with two different return periods (50 and 1000 years) and then the impact areas overlay on the street networks. Evaluating the resilience of the city, syntactic properties of the street networks before and after flooding are measured at different scales. Additionally, accessibility and the minimum distance of the street networks to essential amenities such as healthcare centers, schools and commercial centers, at a medium distance (3 Km) is examined. The results show that flooding influences the city configuration at global scale more than the local scale based on comparison of syntactic properties before and after flooding. However, the results of accessibility and the minimum distance show that the impact of flooding on the functionality of the city is more limited to the riparian areas and the city is not affected globally.
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| 2. |
- Abshirini, Ehsan, 1979-, et al.
(författare)
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Flood Resilient Cities : A Syntactic and Metric Novel on Measuring the Resilience of Cities against Flooding, Gothenburg, Sweden
- 2017
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Ingår i: Journal of Geographic Information System. - : Scientific Research Publishing, Inc.. - 2151-1950 .- 2151-1969. ; 9, s. 505-534
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Tidskriftsartikel (refereegranskat)abstract
- Flooding is one of the most destructive natural disasters which have rapidly been growing in frequency and intensity all over the world. In this view, assessment of the resilience of the city against such disturbances is of high necessity in order to significantly mitigate the disaster effects of flooding on the city structures and the human lives. The aim of this paper is to develop a method to assess the resilience of a river city (the city of Gothenburg in Sweden), which is prone to flood Hazard, against such disturbances. By simulating flood inundation with different return periods, in the first step, the areas of impact are determined. To assess the resilience, two different methods are followed. One is a syntactic method grounded in the foreground network in space syntax theory and the other is based on measuring accessibility to the essential amenities in the city. In the first method, similarity and sameness parameters are defined to quantitatively measure the syntactic resilience in the city. In the next step, accessibility to amenities and the minimum distance to amenities before and after each disturbance is measured. The results, in general, show that such disturbances affect the city structure and the resilience of the city differently. For instance, the city is more resilient after flooding ac- cording to accessibility measures. This clearly means that the answer to the question of resilience is mainly dependent on “resilience of what and for what.”
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| 3. |
- Abshirini, Ehsan, 1979-
(författare)
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Interaction between rivers and morphology of cities in Sweden
- 2014
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Ingår i: Our common future in urban morphology. - Porto : FEUP edições (Faculdade de Engenharia da Universidade do Porto Edicoes). - 9789729910159
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Konferensbidrag (refereegranskat)abstract
- Rivers as one of the most important topographic factor have played a strategic role not only on the appearance of cities but they also affect the structure and morphology of cities. In this paper I intend to find out the influence of rivers on the morphology of a cities and discuss that how a city in its physical network interacts with a river flowing inside. My study area is river-cities in Sweden in which they have not received much attention in this issue. To this purpose I use space syntax method integrating with geospatial analysis and extract the properties of physical form of cities in terms of global and local integration value, choice value and so on. Comparing the states of presence and absence of rivers in these cities as well as evaluating the effect of rivers on the morphology of areas located in different banks of rivers are also part of interest in this paper. The primary result shows that although a river is not comparable to a city based on size and the area occupied by, it has a significant effect on the form of a city in both global and local properties. In addition, tracking the pattern of river-cities and their interaction to rivers may lead us to interoperate the physical form of these cities in terms of structured and distributed cities.
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| 4. |
- Abshirini, Ehsan, 1979-, et al.
(författare)
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Resilience, space syntax and spatialinterfaces: The case of river cities
- 2017
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Ingår i: A|Z ITU Journal of the Faculty of Architecture. - : ITU Press, Press of the Istanbul Techncial University. - 1303-7005 .- 1302-8324. ; 14:1, s. 25-41
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Tidskriftsartikel (refereegranskat)abstract
- Resilience defined as the capacity of a system to manage impacts, keep its efficiency and continue its development has been scrutinized by researchers from different points of view over the past decades. Due to the prominence of resilience in urban planning, this paper intends to find out how the spatial structure of cities deals with disturbances, and if geographical phenomena such as rivers affect the resilience in cities. Using the space syntax methods syntactically analyze the resilience in cities, we innovatively introduce two measures; similarity and sameness. These measures are in relation with the syntactical properties of cities and compare the degree of resilience between different groups. Similarity measures the degree to which each city retains the relative magnitude of its foreground network after a disturbance and sameness is the degree to which each city retains the same segments as its foreground network after a disturbance. Likewise to network resilience studies, we apply different disturbances on cities and explore the reaction of cities to disturbances in terms of size of the foreground network and which segments are parts thereof. We then compare different groups based on these measurements as a method to analyze sameness and similarity. The results show that the resilience, in the way we define it, is different in different cities depending on in which view and based on which parameters we are discussing the resilience. Additionally morphological phenomena such as rivers have a great impact on the structure of cities and in turn on their resilience.
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| 5. |
- Abshirini, Ehsan, et al.
(författare)
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Rivers as integration devices in cities
- 2016
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Ingår i: City, Territory and Architecture. - : Springer. - 2195-2701. ; 3:1, s. 1-21
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Tidskriftsartikel (refereegranskat)abstract
- Background: As dynamic systems rivers and cities have been in interaction under changing relations over time, and the morphology of many cities has risen through a long and steady struggle between the city functions and the river system flowing inside. This makes river cities an interesting case to study how the presence of geographical features interacts with spatial morphology in the formation of cities.Methods: The basis of this research is enabled by utilizing a novel model for cross-city comparison presented by Hillier in his Santiago keynote in 2012 called a “star model”. This is done on large samples of cities investigating concurrent configurations, as well as how the properties in this star model react to specific forms of disturbance.Results: Results illustrate that the foreground network as identified through maximum choice values in cities are more vital to the structure of cities than the bridges. The overall syntactic structure tends to retain its character (degree of distributedness) and the location of its foreground network (which street segments constitute the foreground network) even when bridges are targeted. Furthermore, counter to the initial hypothesis, river cities tend to change less than non-river cities after targeted disturbance of the systems. Finally, the results show that while there is a statistical morphological difference between river cities and non-river cities, this difference is not directly explained through the bridges.Conclusion: Integrating space syntax with statistical and geospatial analysis can throw light on the way in which the properties of city networks and urban structure reflect the relative effect of rivers on the morphology of river cities. The paper, finally, contributes through offering one piece of a better perception of the structure of river-cities that can support strategies of river-cities interaction as well as enhance our knowledge on the constraints and limits to that interaction.
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| 6. |
- Abshirini, Ehsan, 1979-, et al.
(författare)
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Visibility Analysis, Similarity and Dissimilarity in General Trends of Building Layouts and their Functions
- 2013
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Ingår i: Proceedings of Ninth International Space Syntax Symposium. - Seoul : Sejong University Press. - 9788986177213 ; , s. 11:1-11:15
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Konferensbidrag (refereegranskat)abstract
- Visibility analysis is one of the key methods in space syntax theory that discusses visual information conveyed to observers from any location in space that is potentially directly visible for the observer without any obstruction. Visibility – simply defined as what we can see – not only affects the spatial function of buildings, but also has visual relation to the perception of buildings by inhabitants and visitors. In this paper we intend to present the result of visibility analysis applied on a sample of building layouts of different sizes and functions from a variety of places of periods. The main aim of this paper is to statistically explore the general trends of building layouts and show if and how visibility properties such as connectivity, clustering coefficient, mean depth, entropy, and integration values can make distinctions among different functions of buildings. Our findings reveal that there are significant correlation coefficients among global properties of visibility in which we consider the mean value of properties, a similarity suggesting that they are not intensively manipulated by architecture. On the other hand, there are correlations although less so than the previous, still significant among local properties of visibility in which we consider the (max-min) value of properties, suggesting that social, cultural or other physical parameters distinguish buildings individually. We also show that functions such as ‘museum’ and ‘veterinary’ are relatively well-clustered, while functions such as ‘ancient’ and ‘shopping’ show high diversity. In addition, using a decision tree model we show that, in our sample, functions such as ‘museum’ and ‘library’ are more predictable rather than functions such as ‘hospital’ and ‘shopping.’ All of these mean that – at least in our sample – the usability and applicability of well-clustered and well-predicted functions have been predominant in shaping their interior spaces; vice versa, in well-diverse and unpredicted functions, the pragmatic solutions of people’s daily life developed in material culture affect the visual properties of their interior spaces.
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| 7. |
- Afzal, Zeeshan, 1991-, et al.
(författare)
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Using Features of Encrypted Network Traffic to Detect Malware
- 2021
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Ingår i: 25th Nordic Conference on Secure IT Systems, NordSec 2020. - Cham : Springer Science and Business Media Deutschland GmbH. ; , s. 37-53
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Konferensbidrag (refereegranskat)abstract
- Encryption on the Internet is as pervasive as ever. This has protected communications and enhanced the privacy of users. Unfortunately, at the same time malware is also increasingly using encryption to hide its operation. The detection of such encrypted malware is crucial, but the traditional detection solutions assume access to payload data. To overcome this limitation, such solutions employ traffic decryption strategies that have severe drawbacks. This paper studies the usage of encryption for malicious and benign purposes using large datasets and proposes a machine learning based solution to detect malware using connection and TLS metadata without any decryption. The classification is shown to be highly accurate with high precision and recall rates by using a small number of features. Furthermore, we consider the deployment aspects of the solution and discuss different strategies to reduce the false positive rate.
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| 8. |
- An, Wei, et al.
(författare)
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Mechanistic Study of CO Titration on CuxO/Cu(111) (x <= 2) Surfaces
- 2014
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Ingår i: ChemCatChem. - : Wiley-VCH Verlagsgesellschaft. - 1867-3880 .- 1867-3899. ; 6:8, s. 2364-2372
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Tidskriftsartikel (refereegranskat)abstract
- The reducibility of metal oxides is of great importance to their catalytic behavior. Herein, we combined ambient-pressure scanning tunneling microscopy (AP-STM), X-ray photoemission spectroscopy (AP-XPS), and DFT calculations to study the CO titration of CuxO thin films supported on Cu(111) (CuxO/Cu(111)) aiming to gain a better understanding of the roles that the Cu(111) support and surface defects play in tuning catalytic performances. Different conformations have been observed during the reduction, namely, the 44 structure and a recently identified (5-7-7-5) Stone-Wales defects (5-7 structure). The DFT calculations revealed that the Cu(111) support is important to the reducibility of supported CuxO thin films. Compared with the case for the Cu2O(111) bulk surface, at the initial stage CO titration is less favorable on both the 44 and 5-7 structures. The strong CuxO <-> Cu interaction accompanied with the charge transfer from Cu to CuxO is able to stabilize the oxide film and hinder the removal of O. However, with the formation of more oxygen vacancies, the binding between CuxO and Cu(111) is weakened and the oxide film is destabilized, and Cu2O(111) is likely to become the most stable system under the reaction conditions. In addition, the surface defects also play an essential role. With the proceeding of the CO titration reaction, the 5-7 structure displays the highest activity among all three systems. Stone-Wales defects on the surface of the 5-7 structure exhibit a large difference from the 44 structure and Cu2O(111) in CO binding energy, stability of lattice oxygen, and, therefore, the reduction activity. The DFT results agree well with the experimental measurements, demonstrating that by adopting the unique conformation, the 5-7 structure is the active phase of CuxO, which is able to facilitate the redox reaction and the Cu2O/Cu(111)<-> Cu transition.
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| 9. |
- Anukam, Anthony, et al.
(författare)
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A review of the mechanism of bonding in densified biomass pellets
- 2021
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Ingår i: Renewable & sustainable energy reviews. - : Elsevier. - 1364-0321 .- 1879-0690. ; 148
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Tidskriftsartikel (refereegranskat)abstract
- The production of durable biomass pellets have always been challenged by several factors including the lack of understanding of the mechanism involved in how particles combine to form pellets under standard conditions of the pellet press. This is because contributing factors span several molecular, microscopic, and even nanoscopic levels as biomass undergoes pelleting. The characteristics of the bonds formed between the combining particles and their relevance to the quality of pellets remains vague, no matter how quality is defined. However, even though few researchers have attempted to explain the mechanism of bonding in densified biomass pellets using different theories, none of their hypotheses supports particle bonding from a structural chemistry perspective. There are still no clear explanations which consider the role of molecular structure and the interactions of substances as milled biomass undergo pelleting. In view of these arguments therefore, this review presents an in-depth analysis of a structural chemistry perspective of the mechanism of bonding and the use of additives in densified biomass pellets and helps identify research areas needed to facilitate better understanding of bonding in densified biomass pellets. The status of current research in biomass pelleting, types of materials suitable as additives and their structural characteristics, as well as the current technical specifications of using additives are also discussed.
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| 10. |
- Anund Vogel, Jonas, 1981-, et al.
(författare)
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Incentivising innovation in the construction sector : the role of consulting contracts
- 2019
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Ingår i: Australasian Journal of Construction Economics and Building. - : UNIV TECHNOLOGY, SYDNEY-UTS EPRESS. - 1835-6354 .- 1837-9133. ; 19:2, s. 181-196
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Tidskriftsartikel (refereegranskat)abstract
- The issue of whether contracts promote innovation and sustainability is an important but overlooked aspect for achieving energy and environmental targets, as well as for creating smart and sustainable cities. In this article, based on the principle/agent problem and Holmstrom and Milgrom's work on optimal contracts it is argued that the current general conditions of architectural and engineering consulting agreements in Sweden (ABK 09)-a standard type of contract often used in developer/consultant relations-may not incentivize choices that support the long-term goals of society. Furthermore, although this exploratory study specifically analyses a Swedish standard contract, the question of how contractual incentive structures can optimize real-world performance is a general one, and thus the article's findings have general applicability. This exploratory study also points to further research into how contractual structures impact climate-neutral buildings. In this way, Swedish consultants who use ABK 09 are incentivized to include low-risk, well-proven, and widely used technologies in order to minimize risks for themselves. This study contributes to resolving this dilemma by suggesting how ABK 09 could be restructured to change the balance between incentives and risk and incentivize innovation and sustainability. As mentioned above, the current study operates at a theoretical level. It discusses six possible changes that would better align the contract with the societal goals of innovation and sustainability.
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