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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

PARENTING INFLUENCING CHILD AND ADOLESCENT CU TRAITS : The Role of Parental Harshness and Parental Warmth in the Development of CallousUnemotional Traits in Children and Adolescents <18: A Systematic Review.

Sandberg, Åsa Therese January 2014 (has links)
The present review sought to clarify and synthesise the existing research of the role parental harshness and parental warmth have on children and adolescents with callous unemotional traits by comparing research across different study designs and study samples in a systematic review. The systematic review search rendered in 16 publications which revealed that callous unemotional traits moderate the relationship between parental harshness as well as parental warmth and behaviour problems in children and adolescents. The moderation effect was directed by the level of callous unemotional trait in the child or adolescent where those with low levels exhibited the most negative effects when exposed to parental harshness. Conversely, children or adolescents with elevated levels exhibited the most positive effects when being exposed to parental warmth. Furthermore, the review revealed that both forms of parenting predict changes in callous unemotional traits over time, where parental harshness increased traits and parental warmth decreased traits. These results are further discussed in relation to the contextual theories of Lykken’s parental competence and socialisation model as well as Kochanska’s conceptual model of conscience development.
2

Effortful Control Development In The Face Of Harshness and Unpredictability

Warren, Shannon M., Warren, Shannon M. January 2017 (has links)
Through the life history theory perspective, this paper seeks to demonstrate how early adversity shapes the development of effortful control in ways that aim to best match the individual to the proximal environment toward ultimate goals despite trade-offs related to social, academic, and later health outcomes. Investigation linking early life harshness (i.e., cues of extrinsic morbidity-mortality; Ellis et al., 2009) and unpredictability (i.e., stochastic changes in environmental conditions; Ellis et al., 2009) to the development of self-regulation could facilitate a more nuanced understanding of early environmental effects on development. The current study investigates early environmental harshness and unpredictability as unique predictors for a self-regulation construct, effortful control. It was hypothesized that early life harshness and unpredictability would uniquely and negatively predict effortful control among preschoolers. While there was no evidence that cues of unpredictability predicted effortful control, cues of harshness, specifically neighborhood harshness, did statistically significantly predict effortful control in the direction expected. This appears to be the first study to explicitly investigate effortful control development in early childhood within the harshness and unpredictability framework.
3

Design Considerations for High Surface-Speed and High-Load Switched Reluctance Machines

Fairall, Earl January 2017 (has links)
This thesis investigates and determines the design considerations to be addressed when designing switched reluctance machines (SRMs) operating at high surface-speeds and high-loads. A new method is introduced to the traditional machine design procedure that captures all of the mechanical, thermal and electro-magnetic considerations for such electric machines. This method is applicable to any motor design; however, is most suitable for machines with rotors that sustain mechanical stresses near the rotor core material limits. The method begins by using common application specifications to identify the maximum diameter and length of a rotor through a series of structural analyses. Maximizing rotor diameter and axial length enables designers to evaluate a machine's theoretical mechanical and electro-magnetic performance limits. The design method is structured such that the designer must use theoretical limits as a constraint for assessing future design decisions which ultimately influence machine cost and performance. The proposed design method is applied to a case study example typical of a large electric vehicle traction machine, a 22,000rpm, 150 kW switched reluctance machine, while attempting to adhere with design practices commensurate with automotive mass manufacturing. To achieve this, a parallel connected 12/8 pole topology was finally developed. The thesis research suggest that a 440 MPa yield strength, 0.27mm thickness lamination with 30 turn stator coils is sufficient to meet the specification requirements within a prescribed power electronic converter voltage and current constraints, while satisfying material mechanical and thermal considerations. Detailed analysis of AC effects, performance characteristics, thermodynamics, noise and vibration is presented to simultaneously demonstrate and validate the proposed machine design and design method. / Thesis / Doctor of Philosophy (PhD)
4

Architecture, Control and NVH Development of Digital Hydraulics for Off-Highway Vehicle Applications

Yuan, QingHui, Jogada, Aaron 27 April 2016 (has links) (PDF)
Digital hydraulics is one of promising technologies having a huge potential to significantly improve energy efficiency in the fluid power industry. In this paper, we present a digital hydraulics solution for mobile market with a large ammount of energy usage by hydraulic components and systems. Specifically, a novel hydraulic architecture, Multiplex Digital Valve (MDV) system that employs digital valves to meet multiple service pressure/flow requirement in off highway vehicles, is introduced. With MDV being integrated in an execavator, signficant hydraulic power saving have been validated compared to the baseline machine with the negative flow control (NFC) architecture. In addition, considering noise is still a critical hurdle for digital hydraulics to be adoped, we develop several noise reduction methods that have been evaluated in simulation environment and implemented in the above MDV. The sound pressure measured from the retrofitted MDV solution with the NVH treatment in the excavator has been improved signficantly over the untreated system such that it is nearly comparable to the baseline machine. The paper also briefly presents the sound quality study for better understanding of human perception and acceptance to nonconventional sound.
5

Finite element modelling of ventilated brake disc hot spotting

Tang, Jinghan January 2017 (has links)
Hot spotting of automotive disc brakes is an undesired thermal localisation phenomenon, which is a challenge for numerical modelling in terms of both accuracy and efficiency especially for complex disc geometry. In this research, the aim was to develop a computationally efficient finite element (FE) approach for 2-piece pin-mounted ventilated disc hot spot prediction with acceptable accuracy enabling parametric studies to contribute to the knowledge of the complex mechanisms. A time reduction strategy for the simulations was established by incorporating an axisymmetric brake pad assumption with material scaling factor and the friction characteristics were defined by a user-subroutine. The computing accuracy and efficiency of this method were then verified by comparing with traditional FE models. 2D in-plane, 2D out-of-plane, and 3D models were performed to investigate the effects of ventilated disc hot spotting, radial hot spot/band migration, and hot spotting of realistic complex disc geometry respectively. Both 2D and 3D results were validated using experimental results based on a laboratory dynamometer and showed good correlation. The results suggested that adequate modelling of friction pair contact pressure distribution and the subsequent non-uniform heat generation is essential for hot spot simulation; speed was identified as the determinant for the number of hot spots, whereas hot spot temperature was determined by energy level. Furthermore, recommendations for vent design, pins, disc run-out, cooling, material selection, wear rate, pad length and loading distribution were given. Finally, hot spotting and hot band migration cause-effect chains were established based on the results and discussion.
6

Dämpning av ljud i Shift-by-Wire växelväljare : Noise damping in a Shift-by-Wire gear shifter

Karlsson, Sebastian, Boberg, André January 1900 (has links)
Constantly growing demands from the costumers in the Automotive industry forces the subcontractors to seek alternative ways to compete. One parameter of quality is the components tolerance against NVH(Noise, Vibraion & Harshness) aspects. Kongsbergs Automotive has developed a new gear shifter platform (Shift-by-Wire) that is sold to Alfa Romeo and used in of their car models. However, the company is not pleased with the components sound quality, therefore the main purpose of this thesis is to develope a number of concepts that is supposed to enhance these NVH-aspects. To get an understanding of the problem an analysis of the causes of the emitted sound has been done parallell to a product decomposition, function decomposition and a Ishikawa-diagram. Together with these methods has a litterature study been performed to get familiar with the physics of an impact and especially the emittment of noise. The concepts has been generated through a combined brainstorming and brainwriting session. A number of concepts has been developed that should reduce emitted noise. To evaluate the concepts generated has well proven methods for screening been used, such as: analysis of pros and cons, feasibility analyis and Go/No-Go. The definite concept uses a method that absorbs the kinetic energy induced by the user through a built-on component and an energy absorbing foam. The idéa is that the built-on component and the foam should transform more of the kinetic energy to heat energy. The consequenses of this study is that the company now has a fully applicable concept to evaluate the idés effectiveness regarding reduction of noise. Next step is to make a prototype and evaluate the idéa. Since the making of a prototype has not been done, the biggest restriction in the thesis  is that the developed concept is not evaluated regarding its effectiveness of reduction of noise.
7

Exploring Factors Affecting the Aging Prison Population in Japan

Ishihara, Junichi 01 December 2009 (has links)
In Japan, the prison population has been aging at a pace far exceeding the general population. This rapid aging has increased the costs in all aspects of prison administration, which has become a great burden on the Japanese prison system. However, little has been clear about the causes of the current explosion of elderly prisoners. This study explores factors affecting the aging prison population, and examines the extent to which three main possible causes affect the aging prison population: the elderly population growth in general society, increased criminal behavior of elderly people, and legal harshness by the criminal justice organizations, such as kinds of sentences and lengths of imprisonment. This study adopts a longitudinal design, using three kinds of cross-sectional annual data sources aggregated for the whole country of Japan during 20 years from 1988 to 2007. The findings indicate that while the the non-elderly prison population growth has been caused by harsher legal attitudes, the main reason for the elderly prison population growth is increased criminal behavior itself.
8

Vibration Modeling and Experimental Analysis of a Locomotive Cab

Venezia, James J. Jr. 01 May 1997 (has links)
This study evaluates noise and vibrations in a heavy freight locomotive cab, and provides several measures for providing more comfort to the crew. A full-scale production cab and sill structure is used to provide the results. The cab is setup in a controlled laboratory environment in a manner similar to the installation on a locomotive. Field measurements are used to emulate actual vibration input to the cab structure. A 16-channel data acquisition system is used to collect both noise and vibration data on various parts of the cab structure and inside the cab. Upon establishing the baseline for laboratory vibration measurements and correlating them with field data, a design of experiment was conducted to evaluate the vibration contribution of various parts of the cab. This showed that the cab floor and cab roof had the largest vibrations. A series of solutions including stiffening the cab floor and damping the cab roof were investigated. The results showed that although such solutions reduce localized vibrations, the overall effect on reducing cab interior noise is minimal. As a more global solution, the cab was isolated from the sill structure through six elastomeric elements mounted at the base of the cab and at the crash post. The mounts at the base were selected such that they support the static weight of the cab, provide a resonance frequency that is below the excitation range, and offer good lateral and longitudinal stability. Two tube-form elastomeric mounts were placed between the cab structure and the crash posts which attach to the front of the sill structure. The test results showed that the soft-mounted cab had significantly lower noise and vibration than the original cab. The vibration levels were reduced 10 to 100 times at certain locations and frequency ranges. The overall noise level was reduced by approximately 6 dBA. In an attempt to provide an estimate of effectiveness of the mounts with different stiffness values, a simulation model was prepared in Matlab. Although the model did not yield accurate results, it resulted in several recommendations for future research work. / Master of Science
9

Finite Element Modelling of Ventilated Brake Disc Hot Spotting

Tang, Jinghan January 2017 (has links)
Hot spotting of automotive disc brakes is an undesired thermal localisation phenomenon, which is a challenge for numerical modelling in terms of both accuracy and efficiency especially for complex disc geometry. In this research, the aim was to develop a computationally efficient finite element (FE) approach for 2-piece pin-mounted ventilated disc hot spot prediction with acceptable accuracy enabling parametric studies to contribute to the knowledge of the complex mechanisms. A time reduction strategy for the simulations was established by incorporating an axisymmetric brake pad assumption with material scaling factor and the friction characteristics were defined by a user-subroutine. The computing accuracy and efficiency of this method were then verified by comparing with traditional FE models. 2D in-plane, 2D out-of-plane, and 3D models were performed to investigate the effects of ventilated disc hot spotting, radial hot spot/band migration, and hot spotting of realistic complex disc geometry respectively. Both 2D and 3D results were validated using experimental results based on a laboratory dynamometer and showed good correlation. The results suggested that adequate modelling of friction pair contact pressure distribution and the subsequent non-uniform heat generation is essential for hot spot simulation; speed was identified as the determinant for the number of hot spots, whereas hot spot temperature was determined by energy level. Furthermore, recommendations for vent design, pins, disc run-out, cooling, material selection, wear rate, pad length and loading distribution were given. Finally, hot spotting and hot band migration cause-effect chains were established based on the results and discussion. / Appendix 1 and Appendix 2 are unavailable online due to copyright restrictions.
10

Är turjämlikheten hjärtlös?

Lindberg, Sharon January 2016 (has links)
No description available.

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