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Cutting planes in mixed integer programming: theory and algorithmsTyber, Steven Jay 19 February 2013 (has links)
Recent developments in mixed integer programming have highlighted the need for multi-row cuts. To this day, the performance of such cuts has typically fallen short of the single-row Gomory mixed integer cut. This disparity between the theoretical need and the practical shortcomings of multi-row cuts motivates the study of both the mixed integer cut and multi-row cuts. In this thesis, we build on the theoretical foundations of the mixed integer cut and develop techniques to derive multi-row cuts.
The first chapter introduces the mixed integer programming problem. In this chapter, we review the terminology and cover some basic results that find application throughout this thesis. Furthermore, we describe the practical solution of mixed integer programs, and in particular, we discuss the role of cutting planes and our contributions to this theory.
In Chapter 2, we investigate the Gomory mixed integer cut from the perspective of group polyhedra. In this setting, the mixed integer cut appears as a facet of the master cyclic group polyhedron. Our chief contribution is a characterization of the adjacent facets and the extreme points of the mixed integer cut. This provides insight into the families of cuts that may work well in conjunction with the mixed integer cut. We further provide extensions of these results under mappings between group polyhedra.
For the remainder of this thesis we explore a framework for deriving multi-row cuts. For this purpose, we favor the method of superadditive lifting. This technique is largely driven by our ability to construct superadditive under-approximations of a special value function known as the lifting function. We devote our effort to precisely this task.
Chapter 3 reviews the theory behind superadditive lifting and returns to the classical problem of lifted flow cover inequalities. For this specific example, the lifting function we wish to approximate is quite complicated. We overcome this difficulty by adopting an indirect method for proving the validity of a superadditive approximation. Finally, we adapt the idea to high-dimensional lifting problems, where evaluating the exact lifting function often poses an immense challenge. Thus we open entirely unexplored problems to the powerful technique of lifting.
Next, in Chapter 4, we consider the computational aspects of constructing strong superadditive approximations. Our primary contribution is a finite algorithm that constructs non-dominated superadditive approximations. This can be used to build superadditive approximations on-the-fly to strengthen cuts derived during computation. Alternately, it can be used offline to guide the search for strong superadditive approximations through numerical examples.
We follow up in Chapter 5 by applying the ideas of Chapters 3 and 4 to high-dimensional lifting problems. By working out explicit examples, we are able to identify non-dominated superadditive approximations for high-dimensional lifting functions. These approximations strengthen existing families of cuts obtained from single-row relaxations. Lastly, we show via the stable set problem how the derivation of the lifting function and its superadditive approximation can be entirely embedded in the computation of cuts.
Finally, we conclude by identifying future avenues of research that arise as natural extensions of the work in this thesis.
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Preliminary study of a frame for a two module turbine systemLundberg, Anders, Jansson, Tobias January 2011 (has links)
The development of steam turbines is continuously moving forward and the aim is oftento develop configurations with higher power output. Siemens Industrial Turbomachinery AB is currently in the beginning of a development project which replaces a single turbine with two interconnected turbines with higher pressure and temperature of the steam than before. To ensure reliable quality and hold down costs is it an advantage to do most of the assembly before delivery to site.This thesis work at Linköping University has been written in collaboration with Siemens Industrial Turbomachinery AB, Finspång. The objective of this work is to investigate the possibility to mount two turbines and a gearbox on a turbine frame. Theframe will be used both for transportation and during operation.The thesis considerate analyses of the turbine layout and critical parameters that may affect a turbine frame. In addition was a frame concept developed and evaluated with respect to solid mechanics and alignment of the shaft arrangement.Our conclusion is that there are good possibilities to install the equipment on a frame and achieve demands due to solid mechanics and alignment of the shaft arrangement.We recommend Siemens Industrial Turbomachinery AB to carry on with the project and do further investigations of the natural frequency of the frame concept, compare financial advantages and disadvantages together with possibilities for transportation.
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Manual handling workload and musculoskeletal discomfort in nursing personnel [electronic resource] / by Nancy Nivison Menzel.Menzel, Nancy Nivison. January 2001 (has links)
Title from PDF of title page. / Document formatted into pages; contains 69 pages. / Thesis (Ph.D.)--University of South Florida, 2001. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: Nursing staff members (registered nurses, licensed practical nurses, and nursing aides) have one of the highest incidence rates of work-related musculoskeletal disorders (WMSDs) of all occupations. Ergonomic research has identified patient handling and movement tasks that put the caregiver at high risk for a WMSD each time they are performed. The purpose of this study was to determine whether the frequency of performing the highest risk tasks, as well as certain other risk factors affecting physical workload, were related to the frequency of musculoskeletal discomfort. Also investigated was whether the manual handling workload varied by job category. The cross-sectional study was conducted at a Veterans' Administration hospital in Tampa, Florida in August 2001 on 11 in-patient units with 113 participants, who completed musculoskeletal discomfort and demographic surveys at the end of a week of observation of their workloads. / ABSTRACT: Multiple regression analysis indicated that the number of high risk patient handling and movement tasks performed per hour, the number of patients cared for who weighed 212 pounds or more, and the interaction of the two were associated with the frequency of knee and wrist pain, but not with low back pain. The following variables were not associated with the frequency of musculoskeletal discomfort in any body part: patient census/able bodied staff ratio, patient classification rating, or number or use of patient handling and movement equipment. Manual handling workload did differ significantly among job categories, with registered nurses performing the fewest at- risk patient handling tasks and nursing aides the most. The seven-day prevalence rate of at least moderate discomfort in at least one body part was 62%. / ABSTRACT: Recommendations include instituting recorded patient assessments to standardize the type of equipment and the number of staff members needed for specific handling and movement activities, as well as improved staff training. Further research is needed on the following: biomechanical forces on the wrist and knee during patient handling and movement tasks; the effect of patient weight on the risk of patient handling and movement tasks; and psychosocial stressors in addition to the physical workload of nursing staff. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.
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臺北市立國民中學教師輔導與管教學生現況與問題之研究朱賡忠 Unknown Date (has links)
本研究旨在探討臺北市立國民中學自訂「教師輔導與管教學生辦法」的過程,瞭解其實施的現況,學校處理學生問題時所遭遇的困境,實施「零體罰」及「解除髮禁」所造成的衝擊,並提出改善策略與建議,俾供教育主管機關、學校行政與教師參考。
研究內容包含文獻分析與深度訪談等兩種方法。其中文獻分析的部分,首先探究輔導與管教之法規與適用及其內涵與救濟,然後以英、美為例,探究其他國家之輔導與管教辦法,對照我國過去在相關議題部分之研究文獻。至於深度訪談部分,則以教育主管單位及臺北市各型學校抽樣,選出與本研究問題之業務有直接相關的教育工作者共39人進行深入訪談,將訪談內容加以分析並提出建議。
本研究主要發現如下:
一、 各校訂定本辦法時,均能夠遵循國民教育法、行政命令等相關法規,依法定程序與精神辦理。
二、 學校學生常發生之偏差行為可分為四類,包括:學習態度不佳、生活常規不良、違規行為、違法行為等四大類型。
三、 學校在實施本辦法時所面臨的困擾,主要來自:辦法本身的不週延、學生人格特質、家庭因素或學區環境影響、家長的態度、學校行政的效能、以及教師的專業知能等。
四、 「零體罰」政策部分,教育主管單位、校長、訓導人員、輔導人員、教師、家長等,角色職責不同,其看法分歧,亟待整合。
五、 「解除髮禁」政策部分,教師期待學生自律與自愛,能自我澄清髮禁的意義與價值,不要為追求外表的特色而迷失了自我。
六、 受訪者提出多項看法,針對不同困擾的因素,提供各種改進的意見與建議,以提供各相關業務人員參考使用。 / This research focuses on the process in which junior high schools in Taipei develop individual “regulations of student guidance and discipline by teachers,” in an attempt to understand the current execution of those regulations, the predicament that the school administrators might encounter when dealing with students’ problems, and the impact of implementing “zero corporal punishment” and “lifting of the ban on hairstyle,” at the same time proposing strategies and suggestions for improvement, which may serve the educational administration, school administrators, and teachers for future reference.
This study adopts two approaches—the review of literature and an in-depth interview. In terms of literature review, we first examine current regulations of guidance and discipline, also exploring their inherent compensatory mechanisms. Then, in the light of our studies on some cases of guidance and discipline methods in such western countries as Britain and the US, we re-examined research on relevant issues done by scholars in Taiwan in the past. And for the in-depth interview, we choose among education authorities and junior schools of all sizes in Taipei, and base our study on a sample of totally 39 educators directly related to our research question. An analysis of the result of the interviews is made, and suggestions offered accordingly.
The main findings of this research are as follows:
1. In making the aforementioned regulations, the school administrations are able to abide by the Statute of Civil Education and related governmental codes, executing such regulations within the confines of legality and justice.
2. Common deviant behaviors among junior high students can be categorized into 4 major types—bad learning attitudes, awful daily routines, behavior against regulations, and behavior against the law.
3. The problems schools face when executing such regulations are mainly due to: the inadequacy of the regulation per se, the students’ personalities, the influence of family or learning environment, parents’ attitude, effectiveness of school administrations, and the teachers’ professional knowledge and abilities.
4. In terms of “zero corporal punishment,” there are separate roles to play for education administrators, principals, school discipline staff, school guidance staff, teachers, and parents, and their ideas about this policy differ greatly and need to be integrated.
5. As for he policies on lifting the ban on hairstyle, the teachers expect their students not only to exhibit self-discipline and self-respect, but also to appreciate the meanings and values of the ban on hairstyle instead of blindly seeking beautiful appearances while losing their selves.
6. The interviewees offer various viewpoints on how different kinds of problematic situations can be improved, thus providing related educational administrators with future references.
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The effects on strength and performance of an amino acid supplement, Rebuild II [TM], following strength training in collegiate softball playersMcGovern, Bryan January 1999 (has links)
Fourteen Ball State University softball players participated in this study to examine the effects of an amino acid supplement, Rebuild II TM, on strength and performance. Rebuild II TM contains high levels of BCAAs and glutamine. Two groups strength trained for ten weeks with the treatment group consuming Rebuild II TM, and the control group consuming a placebo. Subjects were pre and post-tested on the bench press, squat and machine shoulder press for strength, and performed a 90-foot sprint and a vertical jump for performance measures. LBW was calculated from the subjects body weight and percent fat. Pre and post measures were analyzed using a two way Anova variance with repeated measures test with a significant level set at p< 0.05. Both groups showed significant increases in strength and vertical jump performance, but only the Rebuild II TM group had a significant increase in LBW and decrease in percent fat. It was concluded that with a controlled weight training program, softball players will increase strength and vertical jump performance, and by adding an amino acid supplement to an athletes diet, there may be larger increases in LBW and decreases in percent fat while strength training. / School of Physical Education
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Design, testing, and performance of a hybrid micro vehicle - the Hopping RotochuteBeyer, Eric W. 04 May 2009 (has links)
A new hybrid micro vehicle, called the Hopping Rotochute, was developed to robustly explore environments with rough terrain while minimizing energy consumption over extended periods of time. Unlike traditional robots, the Hopping Rotochute maneuvers through complex terrain by hopping over or through impeding obstacles. A small coaxial rotor system provides the necessary lift while a movable internal mass controls the direction of travel. In addition, the low mass center and egg-like shaped body creates a means to passively reorient the vehicle to an upright attitude when in ground contact while protecting the rotating components.
The design, fabrication, and testing of a radio-controlled Hopping Rotochute prototype as well as an analytical study of the flight performance are documented. The aerodynamic, mechanical, and electrical design of the prototype is outlined which were driven by the operational requirements assigned to the vehicle. The aerodynamic characteristics of the rotor system as well as the damping characteristics of the foam base are given based on experimental results using a rotor test stand and a drop test stand respectively. Experimental flight testing results using the prototype are outlined which demonstrate that all design and operational requirements are satisfied. A dynamic model associated with the Hopping Rotochute is then developed including a soft contact model which estimates the forces and moments on the vehicle during ground contact. A comparison between the vehicle's motion measured using a motion capture system and the simulation results are presented to determine the validity of the experimentally-tuned dynamic model. Using this validated simulation model, key parameters such as system weight, rotor speed profile, internal mass weight and location, as well as battery capacity are varied to explore the flight performance characteristics. The sensitivity of the hopping rotochute to atmospheric winds is also investigated as well as the ability of the device to perform trajectory shaping.
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The causes and prevention of airline baggage handler back injuries : safe designs required where behaviour and administrative solutions have had limited effectDell, Geoff January 2007 (has links)
"Back injuries have consistently been the most common types of injuries suffered by people at work. They have been a significant worker injury problem in most, if not all, industrialised countries for many years and manual handling has long been established as a significant task related back injury causal factor.[...] This research project established that the manufacturers of the jet airlines used by the airlines in this study had not previously been acquainted with the issue of baggage handler back injuries.[...] This study also canvassed the opinion of airline safety professionals and airline baggage handlers concerning baggage handling tasks and working environment related causal factors. [...] A major focus of this research project was also to measure the effect of ACE and Sliding Carpet, two commercially available retro-fit baggage systems, on the risk of back injuries to baggage handlers stacking baggage within Boeing B737 narrow-body aircraft." / Doctor of Philosophy
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The causes and prevention of airline baggage handler back injuries : safe designs required where behaviour and administrative solutions have had limited effectDell, Geoff . University of Ballarat. January 2007 (has links)
"Back injuries have consistently been the most common types of injuries suffered by people at work. They have been a significant worker injury problem in most, if not all, industrialised countries for many years and manual handling has long been established as a significant task related back injury causal factor.[...] This research project established that the manufacturers of the jet airlines used by the airlines in this study had not previously been acquainted with the issue of baggage handler back injuries.[...] This study also canvassed the opinion of airline safety professionals and airline baggage handlers concerning baggage handling tasks and working environment related causal factors. [...] A major focus of this research project was also to measure the effect of ACE and Sliding Carpet, two commercially available retro-fit baggage systems, on the risk of back injuries to baggage handlers stacking baggage within Boeing B737 narrow-body aircraft." / Doctor of Philosophy
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The effect of load and technique on biomechanical and psychophysical responses to level dynamic pushing and pullingBennett, Anthea Iona January 2009 (has links)
Pushing and pulling research has yet to fully elucidate the demands placed on manual workers despite established epidemiological links to musculoskeletal disorders. The current study therefore aimed to quantify biomechanical and perceptual responses of male operators to dynamic pushing and pulling tasks. Three common push/pull techniques (pushing, one handed and two handed pulling) were performed at loads of 250kg and 500kg using an industrial pallet jack in a laboratory environment. Thirty six healthy male subjects (age: 21 ±2 years, stature: 1791 ±43 mm and body mass: 77 ±10 kg) were required to perform six loaded experimental and two unloaded control conditions. Hand force exertion, muscle activity and gait pattern responses were collected during 10m push/pull trials on a coefficient controlled walkway; body discomfort was assessed on completion of the condition. Horizontal hand force responses were significantly (p<0.05) affected by load, with a linear relationship existing between the two. This relationship is determined by specific environmental and trolley factors and is context specific, depending on factors such as trolley maintenance and type of flooring. Hand force exertion responses were tenuously affected by technique at higher loads in the initial and sustained phases, with pushing inducing the greatest hand forces. Comparison of the motion phases revealed significant differences between all three phases, with the initial phase evidencing the greatest hand forces. Muscle activity responses demonstrated that unloaded backward walking evoked significantly higher muscle activation than did unloaded forward walking whilst increased muscular activity during load movement compared to unloaded walking was observed. However increasing load from 250kg to 500kg did not significantly impact the majority of muscle activity responses. When considering technique effects on muscle activity, of the significant differences found, all indicated that pushing imposed the least demand on the musculoskeletal system. Gait pattern responses were not significantly affected by load/technique combinations and were similar to those elicited during normal, unloaded walking. Perceptually, increased load led to increased perception of discomfort while pushing resulted in the least discomfort at both loads. From these psychophysical responses, the calves, shoulders and biceps were identified as areas of potential musculoskeletal injury, particularly during one and two handed pulling. Pushing elicited the highest hand forces and the lowest muscle activity responses in the majority of the conditions whilst psychophysical responses identified this technique as most satisfactory. Current results advocate the use of pushing when moving a load using a wheeled device. Suitability of one and two handed pulling remains contradictory, however results suggest that one handed pulling be employed at lower loads and two handed pulling at higher loads.
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Designing of A Pneumatic Cushion for Supporting Standing and Sitting ProcessYu, Mingyue, Lu, Yixuan January 2018 (has links)
As is known to all, the aging problem becomes more and more serious in recent years. The issues “get into and out of a chair”, from one of the self-care tasks of aging people named Functional mobility in ADLs (Activity of daily livings), need to be solved carefully in efficient ways to help seniors and patients who have physical problems dealing with their daily life. In this previous investigation, the existing products in the market are normally quite heavy and importable. After combined with the advantages of the existing products and some improvements in portability and comfort which is related to human engineering. A Pneumatic Cushion for Supporting Standing and Sitting Process, based on airbag and pneumatic system which has been designed in this thesis, can be used by user who has physical-trouble for standing up and sitting down. Meanwhile, after being assembled with some specific extra components, it can be used as a mobility aid device. For the whole designing process, many relevant article, video sources and websites are referred for the previous researches, including Google Scholar, BTH Digital Library and YouTube. The product was designed and analysed in Inventor 2018 and the fluid dynamic simulation has been done in Abaqus. Studies involved lifting function are selected after the survey about assist appliance and aid appliance market.
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