Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 78-82).

Homogeneous Charge Compression Ignition (HCCI) operation is desirable for its high thermal efficiency and low emissions of NOx and particulates. Difficulty with cold starting and maximum achievable speed/load highlight the desire for mode-switching to traditional spark ignition (SI) operation. Mode-switching between SI and HCCI is investigated using only actuation of throttle, CNG injector pulse width, and CNG injection timing on a single cylinder CFR engine. Open-loop control achieves a one cycle mode-switch between two adjustable IMEP levels. Sequences are repeatable as demonstrated by 10 mode-switches with the same inputs. Performance is evaluated using a developed mode-switch performance criterion (MSPC) by considering duration between steady-states of operation, smoothness of IMEP, and knock based on maximum rate of pressure rise. Comparing the results with subjective analysis (the current standard) reveals good correlation. Throughout development, mode-switching performance is shown to improve by a factor of 60.

The aims of this study were to describe the childbirth preferences of nulliparous women in early pregnancy and to develop a model of the predictors of those preferences. Participants were recruited with Facebook advertisements and data were collected from 344 women via online survey. Predictors were measured using the Utah Test for the Childbearing Year. Predictors of childbirth preferences (type of birth care provider, birth setting, mode of delivery, and use/avoidance of pain medication) were tested using structural equation modeling. Conventional content analysis was employed to analyze women’s reasons for selecting the type of provider and setting they expected for their delivery. Although the majority of respondents preferred physicians and hospital birth, the proportions of women who preferred midwifery care and planned home birth were higher than currently access those types of care in the U.S. More respondents preferred to use pain medication than to avoid it. Over 95% of respondents preferred vaginal delivery. Women who had an internal locus of control and perceived their childbearing role to be one of active participation were more likely than women who saw their role as a passive one to prefer midwifery care, home birth, vaginal delivery, and to avoid pain medication. Women who saw the provider’s role as dominant to their own were more likely to prefer physicians and hospital birth than those who viewed the provider’s role as a collaborative one. The more fearful/painful women expected birth to be, the more likely they were to prefer cesarean delivery.

We give a common frame for different estimates in survival models. For models with nuisance parameters we approximate the profile likelihood and find estimates especially for the proportional hazard model.

Expanding to foreign markets is increasingly popular for companies. The company has to decide which organisational structure, entry mode, to use in the new market. Factors affecting the change from one entry mode to another have obtained little attention. This thesis concerns Swedish companies’ changes of entry mode in Taiwan. The purpose is to investigate which factors that serve as triggers respectively barriers for the change of entry modes, to be able to examine which theories that can be used to explain and support mode changes. Different theories concerning choice and change of entry mode have been investigated. Based on the theories, a model including factors influencing entry mode changes was established. The model has contributed a foundation for the empirical findings as well as the analysis of the companies. As a method, a qualitative approach was conducted through interviews with five Swedish companies having a subsidiary in Taiwan. The criterion for the companies was that they should have a subsidiary in Taiwan, but entered the market with another entry mode. Considering the small number of companies and to obtain an understanding about the entry mode changes, a qualitative investigation was the most suitable. Conclusions that could be drawn were that the competitive Taiwanese market had triggered some of the companies to change their entry mode to a subsidiary in order to be present in the market. Increased sales volume did also have evident affect on why the companies changed their entry mode. The investigation also gives indications that barriers tend to be of internal and firm specific character. Concerning the theories explaining entry mode changes, no complete theory could explain the changes, but parts from different theoretical fields could be applied.

Solutions to physical problems described by Differential Equationson complex domains are in except for special cases almost impossibleto find. This turns our interest toward numerical approaches. Sincethe size of the numerical models tends to be very large when handlingcomplex problems, the area of model reduction is always a hot topic. Inthis report we look into a model reduction method called ComponentMode Synthesis. This can be described as dividing a large and complexdomain into smaller and more manageable ones. On each of thesesubdomains, we solve an eigenvalue problem and use the eigenvectorsas a reduced basis. Depending on the required accuracy we mightwant to use many or few modes in each subdomain, this opens for anadaptive selection of which subdomains that affects the solution most.We cover two numerical examples where we solve Helmholtz equationin a linear elastic problem. The first example is a truss and the othera gear wheel. In both examples we use an adaptive algorithm to refinethe reduced basis and compare the results with a uniform refinementand with a classic model reduction method called Modal Analysis. Wealso introduce a new approach when computing the coupling modesonly on the adjacent subdomains.

To understand students, their world and what makes them act in a certain way or how they form groups in school is a very important part of a teachers work. You get a better understanding for the students behavior by having knowledge about how they look upon themselves and other students, to prevent prejudice and tendenses to bullying and beeing an “outsider”. Clothes and fashion are often a big part of the students identity buliding and how they look upon themselves and get looked at by others. We have chosed to exeminate this phenomenon among girls since they are often more exposed by the media for example and with unreasonable beautyideals and other external factors that many girls try to live up to in todays society. We have made a survey regarding the usage of clothes and fashion in the making of an identety with totally fiftyeight girls in the ninth grade on two different public schools in Haninge and Tyresö municipality. / Att förstå elevers värld och vad som kan göra att de beter sig på ett visst sätt, eller hur de bildar grupperingar i skolan är som lärare en viktig del i arbetet. Eftersom att man får en bättre förståelse för elevernas beteende genom att ta reda på hur de faktiskt själva ser på saker och ting, kan man som lärare också arbeta med eleverna för att få bort eventuella fördomar och tendenser till utanförskap eller mobbning. Ofta spelar kläder och mode en stor roll i elevernas identitetsarbete och hur de ser på sig själva och hur de i sin tur blir sedda av andra. Vi har valt att undersöka detta fenomen bland tjejer då det ofta är de som är mest utsatta av bland annat media med orimliga skönhetsideal och andra yttre faktorer som många unga tjejer försöker leva upp till i dagens samhälle. Vi har gjort en enkätundersökning rörande användandet av kläder och mode i skapandet av en identitet med totalt femtioåtta tjejer i årskurs nio på två olika kommunala skolor i Haninge och Tyresö kommun.

Based on the Lyapunov stability theorem, an adaptive sliding mode control scheme is proposed in this thesis for a class of mismatched perturbed multi-input multi-output (MIMO) dynamic systems to solve regualtion problems. The sliding surface function is firstly designed by treating some state variables as a pseudo controllers through the usage of sliding function to stabilize the rest of state variables. In this thesis the number of these pseudo controllers is less than that of the state variables to be stabilized. The second step is to design the controllers so that the trajectories of the controlled systems are able to reach sliding surface in a finite time. Some adaptive mechanisms are embedded in the sliding surface function and sliding mode controllers, so that not only the mismatched perturbations can be suppressed during the sliding mode, but also the information of upper bounds of some perturbations are not required when designing the sliding surface function and controllers. Once the controlled system enters the sliding mode, the state trajectories can achieve asymptotical stability under certain conditions. A numerical example and a practical example are given to demonstrate the feasibility of the proposed design technique.

A quantized control means that the control force is restricted to takes only a finite number of prescribed levels. The well-known bang-bang control or relay control belongs to this category. This kind of control has the advantage of simple circuit realization using electronic switches or relays that feature low power consumption in their on-off operation. However, quantized control introduces noise and distortion, and even worse its high nonlinearity makes the stabilizing compensator design difficult. This thesis applies the concept of dynamic sliding mode to the synthesis of a multi-level quantized control, with the aim to stabilize the system, perform reference tracking and attenuate the switching noise. The applicability of the presented sliding-mode quantized control is demonstrated on a three-level buck converter. Compared with the conventional PWM (Pulse-Width Modulation) scheme, it eliminates the use of a complex three-level PWM generator and a current sensor. A 12V/8V three-level buck converter with sliding mode quantized control is designed and realized, which shows the output voltage with 0.4625% of average DC error, 2.8988% of the static output ripple and 2.3% of load regulation error in response to the load current steps from 0A/3A to 3A/0A, at a slew rate of 6.25A/£gsec.

This thesis is concerned with the speed control of a brushless DC (BLDC) fan motor by switching its coil currents. Because fans are the most common cooling devices for computers, the demand for a quit and efficient fan that is capable of automatically regulating its speed according to temperature grows with each passing day. A mixed linear and switching control scheme which consists of two loop of feedback compensation for a two-phase BLDC fan motor is presented. Roughly speaking, the linear outer loop is mainly for speed regulation, and the inner loop is to generate a switching control signal while doing plant compensation. This control structure is simple and effective, emphasizing on low power consumption, accurate velocity regulation and low switching noise. The performance and stability requirement can be easily met by tuning several positive coefficients in the controller. The experiment shows an average steady-state regulation error of 0.563% in the range of fan¡¦s speed from 1050 to 2231 r.p.m.