1,522 research outputs found
Facility Location Planning Under Disruption
Facility Location Problems (FLPs) such as the Uncapacitated Facility Location (UFL) and the Capacitated Facility Location (CFL) along with the k-Shortest Path Problem (k-SPP) are
important research problems in managing supply chain networks (SCNs) and related operations. In UFL, there is no limit on the facility serving capacity while in CFL such limit is
imposed. FLPs aim to find the best facility locations to meet the customer demands within the available capacity with minimized facility establishment and transportation costs. The objective of the (k-SPP) is to find the k minimal length and partial overlapping paths between two nodes in a transport network graph. In the literature, many approaches are proposed to solve these problems. However, most of these approaches assume totally reliable facilities and do not consider the failure probability of the facilities, which can lead to notably higher cost. In this thesis, we investigate the reliable uncapacitated facility location (RUFL)and the reliable
capacitated facility location (RCFL) problems, and the k-SPP where potential facilities are exposed to disruption then propose corresponding solution approaches to efficiently
handle these problems. An evolutionary learning technique is elaborated to solve RUFL. Then, a non-linear integer programming model is introduced for the RCFL along with a
solution approach involving the linearization of the model and its use as part of an iterative procedure leveraging CPLEX for facility establishment and customer assignment along with a knapsack implementation aiming at deriving the best facility fortification. In RUFL and RCFL, we assume heterogeneous disruption with respect to the facilities, each customer is assigned to primary and backup facilities and a fixed fortification budget allows to make a subset of the facilities totally reliable. Finally, we propose a hybrid approach based on graph partitioning and modified Dijkstra algorithm to find k partial overlapping shortest paths between two nodes on a transport network that is exposed to heterogeneous connected node failures. The approaches are illustrated via individual case studies along with corresponding key insights. The performance of each approach is assessed using benchmark results. For the k-SPP, the effect of preferred establishment locations is analyzed with respect to disruption scenarios, failure probability, computation time, transport costs, network size
and partitioning parameters
Flexural bending test of topology optimization additively manufactured parts
The aim of this work is to model, manufacture, and test an optimized Messerschmitt-BölkowBlohm beam using additive manufacturing. The implemented method is the Solid Isotropic Material with Penalization of a minimum compliance design. The Taubin smoothing technique was used to attenuate geometric noise and minimize the formation of overhanging angles and residual stresses due to the thermal activity of the selective laser melting process. The optimized model required examination and repair of local errors such as surface gaps, non-manifold vertices, and intersecting facets. A comparison between experimental and numerical results of the linear elastic regimes showed that the additively manufactured structure was less stiff than predicted. Potential contributors are discussed, including the formation of an anisotropic microstructure throughout the layer-by-layer melting process. In addition, the effect of selective laser melting process on the mechanical properties of stainless steel 316l-0407 and its influence on structural performance was described
Navigating the Cairene Table: Food and Family between What Is Ideal and What Is Real
Our daily encounters with food, especially during our childhood, play a crucial role in shaping and informing our identity and our habitus. In this research, by using multimodal and auto ethnography, I argue that due to the guiding path that our senses carve for us, we make sense and contextualise our surroundings through our senses, and not only the five senses of vision, smell, taste, hearing, and touch, but also through our inner senses of time and temporality, and how time and memory play an important role in the registration of our surroundings through our bodies and senses. I am dealing with the senses as a guide for us, starting from childhood and planting the seeds of sensorial ideologies and contextualisation through our exposure to different sensorial elements via food. The first time of smelling a breakfast item that later on became a favourite; tasting tea for the first time in a family gathering and having the memory stamped in mind by the strong earthy flavour of the beverage; the sound of food sizzling in a pan, signalling the preparation of a feast; the first touch of a bread loaf brushing against one’s palm, tethering its warmth and its texture into one’s hands, are all examples of first encounters of a life-long sensuous and ideological affair with food. How do the passing interactions with food during our childhood shape our future understandings of our surrounding world(s)? The senses not only played an important role in understanding the self as part of my autoethnography, but the senses also helped in understanding the other aspects of this research being gender, kinship, social representation, and class dynamics.
When discussing food and family, discussing gender and kinship is inevitable. How does food and family intertwine under the guises of gender and kinship? And why can food and family never be confined within the limitations offered by binaries? Although the Egyptian society is considered by Egyptians and non-Egyptians alike as patriarchal, I describe that this is not the case when it comes to what is being seen on the façade of a household vis-à -vis what actually takes place within the confinements of the domestic sphere. The ideal image of a family might be known as a patriarch/breadwinner being the man of the house, but from fieldwork, I argue that this is not always the case, but far from it. The factuality of the matter is far more complex and multi-layered than to be deemed either purely patriarchal or radically matriarchal. There are aspects and details that go into each and every household that give it its own context and constitute how the household is run and maintained. Overlooking the influence of capitalism and how it goes hand in hand with patriarchy will also misbalance the scales of my argument; thus, rendering it essential to be pointed out.
Finally, how can the supermarket be looked at as a social simulacrum of class and class identity? What are the sensorial differences between the confined supermarket and the open souq? I showcase that the places that sell food (i.e., supermarkets and souqs) not only sell the product, but also sell a class identity informed by the brand bought by the consumer. The supermarket is not only a place of shopping, but it is also a systematic place of identity distribution. I argue that, unlike the haphazardness of the souq, the supermarket is hyper-organised to the point of sensorial sterility and is deprived of the social dramatisation of daily interactions
Application of Reference - Based Lossless Genome Compression
Genomic data technology has advanced by using many algorithms that not only facilitate a meaningful analysis of these data but also aid in efficient compression, storage, retrieval, updating, and transmission of huge volumes of the generated data. This has necessitated the development of novel bioinformatics approaches and generic compression tools. In recent years, many efforts have been madeto use a reference genome for storage that based on encode the differences between sequence and the reference genome. We used the difference compression to update the compressed set of similar sequences.In addition, we found that there is similarity degree between different organisms, so we used difference compression to compress data set from two different species. It used to determine which species can compress related to another species, and which reference is appropriate for data set.Results show that the entropy, which is an indicator of the compression efficiency, and a measure of relatedness, is much lower with variable reference that based on minimum entropy than that with the single fixed Cambridge reference sequence. It noted that execution time for encoding huge data set by using Cambridge reference less rather execution time for data set by using entropy to select reference
Evaluation of the Efficacy of Dexamethasone Versus Magnesium Sulfate in Prevention of Postspinal Shivering: A Prospective, Randomized, Double-Blind Study
Background: Postspinal shivering represents one of the distressing complications of regional anesthesia. This study evaluated the efficacy of dexamethasone and magnesium sulfate to prevent postspinal shivering (PSAS) in lower abdominal and lower limb surgeries. Materials and Methods: Hundred forty-seven patients undergoing elective abdominal and lower limb surgery under spinal anesthesia received either 100 mL isotonic saline (group C), 8 mg in 100 mL isotonic saline (group D), or magnesium sulfate 30 mg/kg in 100 mL isotonic saline (Group M). Results: The incidence of clinically significant shivering was highly significantly less in group D and group M compared to group C (p=0.001), however, there was no statistically significant difference between group D and group M (p=0.052). The onset of shivering was significantly lower in the C group compared to the D and M groups with statistically significant differences between the D and M groups (p=0.001). Conclusion: Dexamethasone and magnesium sulfate were effective in the prevention of PSAS in patients undergoing lower abdominal and lower limb surgeries under spinal anesthesia. However, magnesium sulfate is better than dexamethasone as it is accompanied by less incidence of shivering, and its sedative effect decreases the stress of the surgery
Privatization : problems of implementation in Egypt
This study aims to investigate to what extent the views of the managers of the enterprises to be privatized are a barrier to smooth implementation of privatization as opposed to other problems. Accordingly, the research tackles two main issues: Identification and analysis of the major problems encountered in the implementation of the Egyptian privatization programme and at which level these problems exist while proposing different approaches to tackle them; and views of public sector top and middle-level managers regarding the main issues of privatization. The study relies upon a literature survey, interviews with stakeholders, a survey of managers' attitudes and several illustrative case studies. A model of "good practice" for the smooth and effective implementation of privatization has been designed. Practice in Egypt has then been studied and compared with the "good practice" model. Lack of strictness and firmness in implementing the announced privatization programme has been found to be a characteristic of Egyptian practice. This is partly attributable to the inadequacy of the programme and partly to the different obstacles to implementation. The main obstacles are doubtful desirability of privatization on the part of the managers at different implementation levels, resistance of stakeholders, in adequately of the legal framework governing privatization, redundant labour, lack of an efficient monitoring system allowing for accountability, inefficient marketing of privatization, ineffective communication, insufficient information at different levels and problems related to valuation and selling procedures. A large part of the thesis is concerned with SOE (State Owned Enterprise) managers' attitudes on and understanding of the privatization (appraised through surveys). Although most managers have stated their acceptance of privatization, many of their responses show that they do not accept selling SOEs. They understand privatization to include enterprise reform and restructuring, changing procedures and giving more authority to company executives, but not necessarily as selling SOEs. The majority of managers still see many issues that have to be addressed for smooth implementation of privatization e.g. insufficiency of information, incompleteness of legal framework, restructuring and labour problems. The main contribution to knowledge of this thesis is the study of problems of implementing privatization in developing countries especially managers' resistance to privatization as a major change, partly because of the threat it poses and partly because of the lack of understanding of privatization and implications of operating private businesses. A programme of persuading managers and offsetting the unfavourable effects is recommended as an outcome of the study. Five different phrases and words for the national Index to theses are: Egypt, privatization, implementation of privatization, problems of implementing privatization and managers' attitudes towards privatization
Solvent-mediated modification of thermodynamics and kinetics of monoethanolamine regeneration reaction in amine-stripping carbon capture: computational chemistry study
A major limitation of amine-based post-combustion carbon capture technology is the necessity to regenerate amines at high temperatures, which dramatically increases the operating costs. This paper concludes the effect of solvent choice as a possible route to modify the thermodynamics and kinetics characterizing the involved amine 6 regeneration reactions, and discusses whether these modifications can be economically beneficial. We report experimentally-benchmarked computational chemistry calculations of monoethanolamine (MEA) regeneration reactions employing aqueous and non-aqueous solvents with a wide range of dielectric constants. Unlike previous studies, our improved computational chemistry framework could accurately reproduce the right experimental activation energy of zwitterion formation. From the predicted reactions thermodynamics and kinetics, the use of non-aqueous solvents with small dielectric constants led to reductions in regeneration Gibbs free energies, activation barriers and enthalpy changes. This can reduce energy consumption, and gives an opportunity to run desorption columns at relatively lower temperatures, thus offering the possibility of relying on low-grade waste heat as an energy input
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