Abstract¡G We measured time-resolved PL of Zn1-XCdXSe epilayer and ZnSe/Zn0.91Cd0.09Se MQW by Upconversion experiment. The Zn1-XCdXSe epilayer was growth with four kind of Cadmium compositions (X=0.08¡B0.32¡B0.60 and 0.84). The thickness of the Zn1-XCdXSe epilayer is around 0.5£gm. The ZnSe/Zn0.91Cd0.09Se MQW of well width thickness varies from 5nm¡B10nm¡B15nm to 20nm . From carrier recombination mechanism ,We get the two sample relative temperature dependence of radiative¡Bnonradiative recombination lifetime and quantum efficiency , From nonradiative recombination lifetime formula , we can get trap concentration and capture cross section. At low temperature the two samples recombination process is dominated by radiative recombination process. The two samples increase nonradiative recombination process and decrease quantum efficiency with increasing temperature. At high temperature the two samples recombination process is dominated by nonradiative recombination process.

BitTorrent is assumed and predicted to be the world's largest Peer to Peer (P2P) network. Previous studies of the protocol mainly focus on its file sharing algorithm, and many relevant aspects of the protocol remain untouched. In the thesis, we conduct a number of experiments to explore those untouched aspects. We implement a BitTorrent crawler to collect data from trackers and peers, and statistically analyze it to understand the characteristics and behaviors of the BitTorrent protocol better. We find that the expected lifetime of a peer in the BitTorrent is 56.6 minutes and the activity is diurnal. Peers show strong preference towards a limited number of torrents, and 10% of torrents are responsible for 67% of traffic. The US contributes maximum number of peers to the BitTorrent and µTorrent emerges as the favorite BitTorrent client. We measure the strength of Distributed Denial of Service (DDoS) attack using BitTorrent network and conclude that it is transient and weak. Finally we address and discuss the content locatability problem in BitTorrent and propose two solutions.

This thesis considers nonparametric predictive inference for lifetime data that include right-censored observations. The assumption A((_m)) proposed by Hill in 1968 provides a partially specified predictive distribution for a future observation given past observations. But it does not allow right-censored data among the observations. Although Berliner and Hill in 1988 presented a related nonparametric method for dealing with right-censored data based on A((_n)), they replaced 'exact censoring information' (ECI) by 'partial censoring information' (PCI), enabling inference on the basis of A((_n)). We address if ECI can be used via a generalization of A((_n)).We solve this problem by presenting a new assumption 'right-censoring A((_n))' (rc- A((_n)), which generalizes A((_n)). The assumption rc- A((_n)) presents a partially specified predictive distribution for a future observation, given the past observations including right-censored data, and allows the use of ECI. Based on rc-A((_n)), we derive nonparametric predictive inferences (NPI) for a future observation, which can also be applied to a variety of predictive problems formulated in terms of the future observation. As applications of NPI, we discuss grouped data and comparison of two groups of lifetime data, which are problems occurring frequently in reliability and survival analysis.

No description available.

Spontaneous atomic emission is not a process of the isolated atom but rather a cooperative effect of the atom and the vacuum field. It is now well established that spontaneous radiative decay rates can be enhanced or suppressed through the effect of cavities comprising various types of discrete, reflective-mirror type, boundaries. The cavity effect is generally understood in terms of a cavity-induced modification of the vacuum spectral energy density. Recently, interest has grown in the possibility that systems characterized by distributed periodic boundary conditions, such as a spatially varying index of refraction, might be effective in controlling radiative atomic processes. A semi-classical theory is given that enables an estimate of the size of the lifetime modification of a two-level radiator contained within a three-dimensionally incomplete photonic bandgap structure called a fiber-Bragg grating. Following this is an exploration of a specific system and its effect upon radiative spontaneous emission. It is found through fluorescence line narrowing and frequency hole burning measurements that the observation of lifetime modification of the specific system is complicated due to intra and inter Stark energy migration. A lifetime modification measurement then shows that no change in lifetime is observed beyond the error bars on the measurement results. The tuning and coherence properties of a short-external-cavity diode laser that may be useful for future time-dependent spectroscopic measurements are examined using a fiber-based, self-heterodyne technique. Coherence properties during active frequency scans are characterized through analysis of time-dependent heterodyne beat signals at the output of a fiber interferometer.

Polyimide is one of the most heat resistant polymers with high electric breakdown strength, good mechanical properties, and chemical resistance. Polyimide is used in severe environmental condition. Polyimide is commonly applied as electrical insulation in a fine gauge of invertered motor windings and in high voltage coils of encapsulated fly-back transformers. The wire insulation may be exposed to multi-stresses like ac, dc high voltages, temperatures etc. In this thesis, magnet wire insulation properties under multiple stresses are studied under ac, dc voltages and high temperatures. Accelerated degradation test is used to do study of Life -time characteristics of Magnetic wire MW 16-C, which has polyimide insulation. The results of accelerated aging test are evaluated with statistical tools Weibull and ALTA. The result shows that the time to failure can be represented by the inverse power law and the Arrhenius equation with respect to test voltage and temperature respectively.

No description available.

Thesis advisor: John B. Williamson / Today, against the backdrop of the demographic pressures to delay the retirement of older workers, sociologists of aging have begun exploring the impact of national labor market institutions on individual workers’ experiences of aging. Using semi-structured, life story interview data drawn from a sample of 52 male workers in the Tokyo area (born between 1940 and 1953), this dissertation research has contributed to uncovering the ways in which the institution of lifetime employment – the most foundational labor market institution of contemporary Japan – uses age to control individuals’ perceptions and behaviors over the course of their working lives. This dissertation research includes data from pre-mandatory retirement older workers (n=29, aged 55-59) and post-mandatory retirement older workers (n=23, aged 60-68). Based on a social constructionist perspective, this dissertation research has explored three areas of these workers’ experiences of aging over the course of their working lives: (1) perceived instances of being subjected to age discrimination; (2) changes to their attitudes toward these age discrimination experiences; and (3) changes to their self-concepts as workers. A series of thematic data analyses of the interview data, drawn with a life course approach and a grounded theory method, has generated two sets of findings. First, the pre-mandatory retirement experiences of aging of the interview participants (n=52) have contributed to uncovering and describing a social process through which ‘older workers’ are socially constructed within the institutional framework of lifetime employment. Second, the research has found that after mandatory retirement, the post-mandatory retirement workers (n=23) rejected the label of ‘older workers’ and critically viewed lifetime employment as a 'total institution' (Goffman 1961), essentially an institution of social control, harmful to workers in their later working lives. This dissertation research has contributed to the literature by demonstrating that the lifetime employment institution in Japan serves as an intensive age-based social control mechanism that has constructed and reproduced ‘older workers’ in the country’s labor force. Based on the findings of post-mandatory retirement experience of aging, this dissertation research also suggests that the Japanese government should find ways to mitigate the social exclusion, marginalization, and stigmatization that workers experience in their post-mandatory retirement working lives. / Thesis (PhD) — Boston College, 2010. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Sociology.

No description available.

The Hot Spot effect is an issue that reduces the network lifetime considerably. The network on the field forms a tree structure in which the sink represents the root and the furthest nodes in the perimeter represent the leaves. Each node collects information from the environment and transmits data packets to a "reachable" node towards the sink in a multi-hop fashion. The closest nodes to the sink not only transmit their own packets but also the packets that they receive from "lower" nodes and therefore exhaust their energy reserves and die faster than the rest of the network sensors. We propose a technique to allow the data sink to identify nodes severely suffering from the Hot Spot effect and to move beyond these nodes. We will explore the best trajectory that the data sink should follow. Performance results are presented to support our claim of superiority for our scheme.