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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.
91

Resolución de problemas de diseño de redes mediante Dual-Ascent para aplicaciones industriales

Rivas Sáenz, Sebastián Andrés January 2016 (has links)
Magíster en Gestión de Operaciones / todos desarrollados en estudios previos. Para este tipo de problemas, la formEn este trabajo se desarrolla un nuevo enfoque para resolver el problema de diseño de redes no capacitadas con fuente única en base a la combinación de méulación multicommodity que desagrega las demandas ha sido utilizada extensamente y se ha probado que se obtienen mejores resultados que con la formulación de flujo en redes clásica al comparar sus relajaciones lineales. En este trabajo se muestra que dicha formulación puede mejorar aún más al duplicar y dirigir arcos no-dirigidos. Con este concepto, se desarrolla un método de ascenso dual específico para el problema de diseño con fuente única que entrega cotas inferiores de buena calidad. Dentro de este método se propone un esquema de clasificación de commodities que permite una representación reducida del problema y que entrega mejores cotas inferiores en las instancias testeadas. Adicionalmente, este método también entrega una subred de tamaño reducido que se utiliza para encontrar soluciones primales factibles. Se muestra, que en este sentido, el método de ascenso dual es una excelente herramienta de selección de arcos en términos del potencial que tiene la subred de encontrar soluciones primales de buena calidad. Para obtener la solución primal, se utiliza la formulación multicommodity original o un esquema de generación de filas dependiendo del tamaño de la instancia. Se testean los distintos enfoques en instancias de distintos tamaños de redes en forma de grilla generadas aleatoriamente variando sus parámetros y su relación de costos fijos a costos de flujo, testeando instancias que en su equivalente de formulación multicommodity llegan a más de 16 millones de variables. / Este trabajo ha sido parcialmente financiado por Comisión Nacional de Investigación Científica y Tecnológica (CONICYT)
92

Dual-earning parents’ work-family balance and time with children: the moderating effects of gender and age

Xie, Shuting 18 August 2016 (has links)
Achieving work-family balance is a challenge for many families in Canada, especially for dual-earner families with children in the household. Prior research regarding the predictors of work-family balance has mainly focused on work characteristics; therefore, the current study aimed to assess the predictive effect of a key family characteristic -- quality time with children -- on work-family balance. The two objectives of this study were: (a) to describe the association between time with children and parents’ work-family balance among Canadian dual-earner parents, and (b) to understand the effects of age of the youngest child, parent’s gender, and parent’s age on the association between work-family balance and quality time with children. This study used cross-sectional national time-use data from the General Social Survey (GSS) 2010, Cycle 24. T-test and logistic regression analyses were used to address the two research objectives, and all analyses were weighted. Findings indicated that work-family balance was negatively associated with quality time with children. Age of the youngest child, parent’s gender, and parent’s age were found to moderate the effect of quality time with children on work-family balance: The negative effect of quality time with children on work-family balance was stronger for parents who had a youngest child of an older age than for those who had a youngest child of a younger age, for parents who were older than for those who were younger, and for mothers more than for fathers. Findings of this study can add strength to the understanding of work-family balance of Canadian parents and have implications for helping Canadians balance their paid work and family life demands. As well, the findings indicate a more nuanced exploration of how parents’ relationships with their children affect their experience of work-family balance is needed in future research. / October 2016
93

The influence of a family status of singular or dual parenthood on child behavior

Noel, Keiona A. 01 May 2016 (has links)
This study examined the relationship between family status and child behavior and the relationship between the primary caregiver groups and child behavior. In total, there were 40 non-randomly selected participants who took part in a cross-sectional design. The Final Survey consisted of a combined questionnaire of the Child Behavior Checklist and the Eyberg Child Behavior Inventory. This study found that there were no statistically significant differences between singular and dual households in regards to child behavior (p =.222) and no statistically significant differences between the primary caregiver groups in regards to child behavior (p= .312). The conclusions drawn from the findings suggest that living arrangements and the primary caregiver groups do not influence maladaptive child behavior.
94

Design and Application of Phased Array System

Ren, Han 08 1900 (has links)
Since its invention, phased array has been extensively applied in both military and civil areas. The applications include target detecting and tracking, space probe communication, broadcasting, human-machine interfaces, and remote sensing. Although the phased array applications show a broad range of potential market, there are some limitations of phased array's development: high cost, complex structure, narrow bandwidth, and high power consumption. Therefore, novel ideas are needed to reduce these constraints. In this thesis, several new approaches about the design and application of phased array are presents. First, the principle of phased array and fundamental design equations are introduced. Second, a new application of phased array antenna for radar respiration measurement is presented. By integrating a 4×4 Butler matrix with four-element antenna array, there will be four distinct main beams in radiation pattern. This new approach can improve the measurement accuracy and realize a high detecting rate. Third, a compact phased array antenna system based on dual-band operations is introduced. Dual-band function can make N-antenna system obtain 2N unique radiation beams (N is an integer) and achieve a significant size reduction compared to the conventional single-band system. To verify the design concept, a four-element phased array antenna working at 5GHz and 8GHz is designed and fabricated. The measurement results make a good agreement with the simulations. Finally, a novel architecture of steering phase feeding network by using bi-directional series-fed topology is presented. This bi-directional series-fed network needs less phase shifters and realizes steering phase function by applying control voltage.
95

Dual-band Microwave Device Design

Li Shen, Andres E. 05 1900 (has links)
This thesis presents a brief introduction to microwave components and technology. It also presents two novel dual-band designs, their analysis, topology, simulation and fabrication. In chapter 2, a novel dual-band bandpass filter using asymmetric stub-loaded stepped-impedance resonators (SLSIRs) operating at 1 and 2.6 GHz is shown. This type of design applies suitable arrangements to improve the filter’s performance. Then, in chapter 3, a novel dual-band balun (transforms unbalanced input signals to balanced output signals or vice versa) operating at 1.1 and 2 GHz with flexible frequency ratios is presented, which has more advantages in microwave applications. Then, conclusion and future works are discussed in chapter 4.
96

Theoretical and Experimental Development of an Array of Droopy Bowties with Integrated Baluns

Puzella, Angelo 20 June 2014 (has links)
"Theoretical modeling, design, assembly, and measurement of a novel integrated phased array radiator are presented. The droopy bowtie turnstile radiator with quad line feed meets challenging radar requirements and uses low cost manufacturing and assembly techniques. This thesis develops the complete theoretical model (antenna, balun, feeding network) of a broadband phased array radiator: the droopy bowtie turnstile radiator. A novel quad line balun feed is developed that provides a low loss, high isolation, and coincident phase-center feeding network for the droopy bowtie. The radiator and feed design combines broadband RF performance and high-isolation dual-linear polarization in a low profile, compact package that enables wide scan volume performance versus frequency. This thesis develops low-cost manufacturing and assembly techniques applied to the droopy bowtie radiator with the quad line feed. The new radiator design would utilize low cost fabrication techniques such as injection molding and 3-D printing, and also leverages automated assembly techniques. Measurement prototypes and array prototypes of droopy bowtie radiators with the quad line feed are developed for L- and X-bands. The measurements demonstrate broadband RF performance in a low profile compact package viable for wide-scale phased array applications."
97

Does a Fual-Task Promote Better Postural Control In Children Compared to a Single-Task?

Paitich, Graydon 07 May 2019 (has links)
Postural control is the skill developed allowing body equilibrium and orientation, allowing for an efficient interaction with the environment. This skill is developed from birth; the first major landmark is the maintenance of an upright stance of a child, followed by the skill to walk freely (Shumway-Cook & Woollacott, 1985). A second important development occurs between the ages of 7-10 years-old when children start to demonstrate adult-like postural control (Riach & Hayes, 1987). While adults and older adults have shown increased automaticity in postural control in a dual-task (DT) (Potvin-Desrochers, Richer, & Lajoie, 2017), children have not yet been studied. The purpose of this experiment was to determine if children aged 6-7, 8-9, and 10-11 years old would demonstrate better postural stability, and greater postural automaticity in a DT condition than in a postural task (PT). To verify this, children were asked to stand still on a force platform in a PT or in a DT condition (PT with concurrent cognitive task). Results showed that older children had better postural stability, as demonstrated by a smaller sway area (7.20 cm2), reduced sway variability (0.60 cm), and a slower MV of sway (4.70 cm/s) than younger children (12.37 cm2, 0.78 cm, 6.60 cm/s). Older children also had a higher MPF in the PT (0.24 Hz) than in the DT (0.16 Hz). A wavelet transformation revealed a greater contribution of the ultra-low frequency band in the PT (49.9%) than in the DT (46.8%) across all children. These results demonstrated that older children were more stable than younger children. The smaller contribution to the ultra-low band in the DT may be an indication that children rely less heavily on their visual system in the DT. This research shows that children do not demonstrate automaticity of postural control between the ages of 6-11 years.
98

The development of the Corporate School Programme in Thailand

Bhongsatiern, Jomhadhyasnidh January 2015 (has links)
This research investigates the Corporate Schools' programme in Thailand. It aims to examine its implementation and progress from inception, evaluate its current status, and propose ways to enhance its future effectiveness. The programme was initiated through collaboration between the Government and the private sector in the belief that business can play an important role in developing public sector ability to improve educational accessibility and learning quality. The programme is expected to provide young people - particularly school-leavers - with opportunities for education and training. It is also intended to equip them with the knowledge and skills to match labour market requirements. A qualitative approach was employed throughout - governing research design, data collection and data analysis. Three participating companies: CP All Public Company Limited, S&P Syndicate Public Company Limited and the V-ChEPC programme, were selected as case studies. Data were collected through documentary research, semi-structured interviews and observation. The findings, which are based on thematic analysis, show two of the three case study companies were satisfied with the programme's outcomes. These two cases have been focused on their needs and they were aware of the importance of basic skills which young people required. This tends to confirm that the recruitment process has been conducted with due attention. This process, which is aimed at recruiting prospective candidates who hold basic knowledge and skills, could be further developed into one where technical and transferable skills best fit companies' needs. This thesis identifies the current challenges and suggests potential opportunities for three cases. Its outcome should provide a systematic insight to help increase understanding of the Corporate Schools' programme in Thailand with a view to assessing whether or not it has sufficient impact to merit its continuation.
99

Investigating the nature of dual active galactic nuclei in Stripe 82

Gross, Arran Connor 01 May 2019 (has links)
During the close approach of two galaxies in a merger, tidally induced gas inflows can trigger simultaneous black hole accretion which are observed as dual active galactic nuclei (dAGNs). Merger simulations predict that the resulting increased nuclear gas reservoirs will obscure the X-ray emissions from the AGNs. We investigate whether dAGNs in mergers are observed to be more obscured than their isolated counterparts by combining the results of previous radio and optical spectroscopy studies with new Chandra X-ray observations for a sample of 4 dAGN systems in the Stripe 82 field. For the 6 detected components, we find the rest-frame X-ray luminosities range between 39.8 < log LX /erg s-1 < 42.0. The sources have redshifts between 0.04 < z < 0.22 and projected separations between 4.3 and 9.2 kpc, as well as multi-wavelength properties most closely resembling low-luminosity AGNs. However, we determine that the X-ray emissions for 2 of the sources likely has strong contributions from hot interstellar medium, and star-formation and X-ray binaries may contribute to the X-ray luminosities of several sources. We do not find evidence of enhanced obscuration through our analysis of X-ray hardness ratios, optical [O III] emission line luminosities, and mid-infrared luminosities. Therefore, we suggest that the unobscured low-level accretion observed for the AGNs in this sample is driven through stochastic processes rather than the massive gas inflows predicted for a merger-driven scenario.
100

A University Course to Facilitate the Transition Into, Through, and Beyond College Life

Crivello, Matthew A. 01 September 2010 (has links)
The purpose of this project was to review the literature associated with the social and psychological adjustments freshmen and transfer intercollegiate athletes face as they transition into college and create a mandatory course to assist them through their transition into California Polytechnic State University. This project led to the creation of an academic course that will be offered at California Polytechnic State University in the near future. This course could serve as an impetus for coaches, faculty, and administrators at other universities to develop similar courses, or reevaluate established course offerings, and to develop follow-up course training for intercollegiate athletes that will contribute to their positive growth throughout the course of their college careers.

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