ABSTRACT FLEXIBLE ASSEMBLY LINE DESIGN PROBLEM WITH FIXED NUMBER OF WORKSTATIONS Barut&ccedil / uoglu, Sirin M.S. Department of Industrial Engineering Supervisor: Prof. Dr. Meral Azizoglu July 2009, 70 pages In this thesis, we study a Flexible Assembly Line Design problem. We assume the task times and equipment costs are correlated in the sense that for all tasks the cheaper equipment gives no smaller task time. Given the cycle time and number of workstations we aim to find the assignment of tasks and equipments to the workstations that minimizes the total equipment cost. We study a special case of the problem with identical task times. For the general case, we develop a branch and bound algorithm that uses powerful lower bounds and reduction mechanisms. We test the performance of our branch and bound algorithm on randomly generated test problems. The results of our experiments have revealed that we are able to solve large-sized problem instances in reasonable times.

In this thesis, we consider a Disassembly Line Balancing Problem (DLBP) with fixed number of workstations. We aim to maximize the total value of the recovered parts. We assume that there is a limited supply for the products to be disassembled. Different components can be obtained by disassembling different units of the product. Our aim is to assign the tasks to the workstations of the disassembly line so as to maximize the total value of the recovered parts. We present several upper and one lower bounding procedure. The results of our computational study have revealed the satisfactory behavior of our bounding mechanisms.

Thesis (M. Sc.)--University of Hong Kong, 1978. / Typescript.

The impact of stress on the health of postpartum mothers is poorly understood. Although the postpartum period increases risk for stress related diseases such as depression and autoimmune disorders, little qualitative research has focused on women’s perceptions of postpartum stressors. A constant comparative content analysis using Atlas.Ti was done on data collected by Groer (NIH R01 NR05000“Influence of Lactation on Postpartum Stress & Immunity) from 2001 to 2005. Women (n=127) answered the prompt, “Think of any one incident, thought, or feeling that stands out as very stressful to you and describe in as much detail as you choose.” Researcher triangulation was provided by independent coding of data by two qualitative researchers. The women were predominantly white (91%), married (72%), and not yet working following the baby’s birth (70%). Only 28% had family incomes greater than $40,000 per year. Vaginal births were experienced by 66%, 83% without complications. Forty-seven percent were breastfeeding exclusively with 43% bottle feeding. Slightly less than half (48%) were first time mothers. Eighty-nine percent claimed no recent major life event, such as a death in the family. Twenty-seven postpartum stressors were identified that were grouped into five themes: 1) environmental stressors, 2) symptoms of depression, 3) infant health and safety issues, 4) maternal role strain, and 5) lack of support. Seventeen women identified fatigue or lack of sleep as stressful and each questioned her ability to parent a newborn. Though these women would seem low risk for stress (having had an uncomplicated birth, being married and not yet back at work postpartum), 27 different postpartum stressors were identified. Stressors such as lack of sleep may be known by maternal-child nurses, but women are unprepared for them. Interventions need to be designed to provide anticipatory guidance for new mothers regarding postpartum stressors. Tools should be developed for use by clinicians to assess maternal stress in the postpartum period. Prenatal preparation anticipating stressors and postpartum vigilance in assessing stressors could ease the transition into motherhood.

Network Processors are multicore processors capable of processing network packets at wire speeds of multi-Gbps. Due to their high performance and programmability, these processors have become the main computing elements in many demanding network processing equipments like enterprise, edge and core routers. With the ever increasing use of the internet, the processing demands of these routers have also increased. As a result, the number and complexity of the cores in network processors have also increased. Hence, efficiently managing these cores has become very challenging. This dissertation discusses two main issues related to efficient usage of large number of parallel cores in network processors: (1) How to allocate work to the processing cores to optimize performance? (2) How to meet the desired performance requirement power efficiently? This dissertation presents the design of a hash based scheduler to distribute packets to cores. The scheduler exploits multiple dimensions of locality to improve performance while minimizing out of order delivery of packets. This scheduler is designed to work seamlessly when the number of cores allocated to a service is changed. The design of a resource allocator is also presented which allocates different number of cores to services with changing traffic behavior. To improve the power efficiency, a traffic aware power management scheme is presented which exploits variations in traffic rates to save power. The results of simulation studies are presented to evaluate the proposals using real and synthetic network traces. These experiments show that the proposed packet scheduler can improve performance by as much as 40% by improving locality. It is also observed that traffic variations can be exploited to save significant power by turning off the unused cores or by running them at lower frequencies. Improving performance of the individual cores by careful scheduling also helps to reduce the power consumption because the same amount of work can now be done with fewer cores with improved performance. The proposals made in this dissertation show promising improvements over the previous work. Hashing based schedulers have very low overhead and are very suitable for data rates of 100 Gbps and even beyond. / text

Server farms are popular architectures for computing infrastructures such as supercomputing centers, data centers and web server farms. As server farms become larger and their workloads more complex, designing efficient policies for managing the resources in server farms via trial-and error becomes intractable. In this thesis, we employ stochastic modeling and analysis techniques to understand the performance of such complex systems and to guide design of policies to optimize the performance. There is a rich literature on applying stochastic modeling to diverse application areas such as telecommunication networks, inventory management, production systems, and call centers, but there are numerous disconnects between the workloads and architectures of these traditional applications of stochastic modeling and how compute server farms operate, necessitating new analytical tools. To cite a few: (i) Unlike call durations, supercomputing jobs and file sizes have high variance in service requirements and this critically affects the optimality and performance of scheduling policies. (ii) Most existing analysis of server farms focuses on the First-Come- First-Served (FCFS) scheduling discipline, while time sharing servers (e.g., web and database servers) are better modeled by the Processor- Sharing (PS) scheduling discipline. (in) Time sharing systems typically exhibit thrashing (resource contention) which limits the achievable concurrency level, but traditional models of time sharing systems ignore this fundamental phenomenon. (iv) Recently, minimizing energy consumption has become an important metric in managing server farms. State-of-the-art servers come with multiple knobs to control energy consumption, but traditional queueing models don’t take the metric of energy consumption into account. In this thesis we attempt to bridge some of these disconnects by bringing the stochastic modeling and analysis literature closer to the realities of today’s compute server farms. We introduce new queueing models for computing server farms, develop new stochastic analysis techniques to evaluate and understand these queueing models, and use the analysis to propose resource management algorithms to optimize their performance.

This study analyzes the changes in disability-specific curriculum that took place in one specialized school for the blind driven by academic priorities from 1995 to 2005. The framework used in this case study approach analyzed the school's past and present (1) Artifacts - visible organizational structures and materials, (2) Expressed Values- explicitly written or stated beliefs and policies, and (3) Underlying Assumptions- unspoken attitudes and beliefs. Variables for change among the areas of teacher training, team teaching, evaluation systems, IEP's, state standards, the school improvement plan, short term and summer programming, as well as the residential program were all targeted to balance academics with an Expanded Core curriculum. The results indicate a balanced curriculum for some of the variables while other areas continue to reflect the struggle of mandates.

This work focuses on scheduling of MPI jobs when executing in shared-memory multiprocessors (SMPs). The objective was to obtain the best performance in response time in multiprogrammed multiprocessors systems using batch systems, assuming all the jobs have the same priority. To achieve that purpose, the benefits of supporting malleability on MPI jobs to reduce fragmentation and consequently improve the performance of the system were studied. The contributions made in this work can be summarized as follows:· Virtual malleability: A mechanism where a job is assigned a dynamic processor partition, where the number of processes is greater than the number of processors. The partition size is modified at runtime, according to external requirements such as the load of the system, by varying the multiprogramming level, making the job contend for resources with itself. In addition to this, a mechanism which decides at runtime if applying local or global process queues to an application depending on the load balancing between processes of it. · A job scheduling policy, that takes decisions such as how many processes to start with and the maximum multiprogramming degree based on the type and number of applications running and queued. Moreover, as soon as a job finishes execution and where there are queued jobs, this algorithm analyzes whether it is better to start execution of another job immediately or just wait until there are more resources available. · A new alternative to backfilling strategies for the problema of window execution time expiring. Virtual malleability is applied to the backfilled job, reducing its partition size but without aborting or suspending it as in traditional backfilling. The evaluation of this thesis has been done using a practical approach. All the proposals were implemented, modifying the three scheduling levels: queuing system, processor scheduler and runtime library. The impact of the contributions were studied under several types of workloads, varying machine utilization, communication and, balance degree of the applications, multiprogramming level, and job size. Results showed that it is possible to offer malleability over MPI jobs. An application obtained better performance when contending for the resources with itself than with other applications, especially in workloads with high machine utilization. Load imbalance was taken into account obtaining better performance if applying the right queue type to each application independently.The job scheduling policy proposed exploited virtual malleability by choosing at the beginning of execution some parameters like the number of processes and maximum multiprogramming level. It performed well under bursty workloads with low to medium machine utilizations. However as the load increases, virtual malleability was not enough. That is because, when the machine is heavily loaded, the jobs, once shrunk are not able to expand, so they must be executed all the time with a partition smaller than the job size, thus degrading performance. Thus, at this point the job scheduling policy concentrated just in moldability.Fragmentation was alleviated also by applying backfilling techniques to the job scheduling algorithm. Virtual malleability showed to be an interesting improvement in the window expiring problem. Backfilled jobs even on a smaller partition, can continue execution reducing memory swapping generated by aborts/suspensions In this way the queueing system is prevented from reinserting the backfilled job in the queue and re-executing it in the future.

Darbe nagrinėjama visuomeninio pastato vėsinimo sistema. Pastatas, kurio naudingas plotas 7900 m2, yra Vilniaus mieste, jo vėsinimo sistemoje yra 268 ventiliatoriniai konvektoriai. Pasirinkti trys šių įrenginių hidraulinio aprišimo variantai: pastoviojo srauto sistema, kintamojo srauto sistema su rankiniais balansavimo ventiliais ir kintamojo srauto sistema su automatiniais balansavimo ir valdymo ventiliais. Lyginamos pradinės sistemų investicijos ir montavimo bei eksploatacijos išlaidos. / An issue is a cooling systems analysis in a public building. Public building is situated in Vilnius city, area of 7900 m2, installed 268 fan coils. The comparison is made modelling between constant flow, variable flow with manual balancing, and variable flow systems with automatic balancing control valves. Analysis is done for initial investment (installation costs) and operating costs.

Constitution of the Republic of Lithuania sets the principal democratic values of society. Human rights assume special role in the system of constitutional values. Article 25 of the Constitution of the Republic of Lithuania establishes the right of a human being to have his own convictions and freely express them. Article 25 of the Constitution of the Republic of Lithuania establishes the right to everyone to have freedom to express his opinion and convictions and to freely impart them. This is an essential clause for the creation and protection of democracy. Constitutional freedom of expression is realised in ordinary laws. Article 25 of the Constitution of the Republic of Lithuania establishes the principle of freedom of expression that is realised in the Civil Code of the Republic of Lithuania, Law on Provision of Information to the Public and other ordinary laws. Freedom of expression, just like other constitutional human rights and freedoms, is not absolute. Employment of the freedom of expression faces such requirements that are required in the democratic society to protect the rights and freedoms of other human beings, as well as the constitutional arrangement. Ordinary courts (general jurisdiction and specialised), which examine cases for determining balance of freedom of expression and other constitutional values, must construe the content of constitutional rights of human beings. Decisions by ordinary courts in the cases of determining the balance of freedom of... [to full text] / LR Konstitucijoje įtvirtintos svarbiausios demokratinės visuomenės vertybės. Žmogaus teisėms konstitucinių vertybių sistemoje tenka ypatinga vieta. LR Konstitucijos 25 str. įtvirtinta žmogaus teisė turėti savo įsitikinimus ir juos laisvai reikšti. LR Konstitucijos 25 str. kiekvienam žmogui suteikia galimybę laisvai formuoti savo nuomonę ir pažiūras bei laisvai jas skleisti. Tai būtina sąlyga demokratijai kurti ir saugoti. Konstitucinė saviraiškos laisvė įgyvendinama ordinariniuose įstatymuose. LR Konstitucijos 25 str. įtvirtintas saviraiškos laisvės principas įgyvendintas LR Civiliniame kodekse, LR Visuomenės informavimo įstatyme bei kituose ordinariniuose įstatymuose. Saviraiškos laisvė, kaip ir kitos konstitucinės žmogaus teisės ir laisvės, nėra absoliuti. Naudojantis saviraiškos laisve susiduriama su tokiais reikalavimais, kurie būtini demokratinėje visuomenėje siekiant apsaugoti kitų žmonių teises ir laisves, konstitucinę santvarką. Ordinariniai (bendros kompetencijos ir specializuoti) teismai, spręsdami žodžio laisvės ir kitų konstitucinių vertybių pusiausvyros nustatymo bylas, turi interpretuoti konstitucinių žmogaus teisių turinį. Priimdami sprendimus žodžio laisvės ir kitų konstitucinių vertybių pusiausvyros nustatymo bylose ordinariniai teismai turi remtis žodžio laisvės ir kitų konstitucinių vertybių konstitucine dimensija.