Optical properties and g factors of GaAs quantum rods

The Hamiltonian of the zinc-blende quantum rods in the framework of eight-band effective-mass approximation in the presence of external homogeneous magnetic field is given. The electronic structure, optical properties and electron g factors of GaAs quantum rods are investigated. We found that the electron g factors are very sensitively dependent on the dimensions of the quantum rods. As some of the three dimensions increase, the electron g factors decrease. The more the dimensions increase, the more the electron g factors decrease. The dimensions perpendicular to the direction of the magnetic field affect the electron g factors more than the other dimension. (c) 2006 Elsevier B.V. All rights reserved.

Electron g factors and optical properties of InAs quantum ellipsoids

The electronic structure, electron g factors and optical properties of InAs quantum ellipsoids are investigated, in the framework of the eight-band effective-mass approximation. It is found that the light-hole states come down in comparison with the heavy-hole states when the spheres are elongated, and become the lowest states of the valence band. Circularly polarized emissions under circularly polarized excitations may have opposite polarization factors to the exciting light. For InAs ellipsoids the length, which is smaller than 35 nm, is still in a strongly quantum-confined regime. The electron g factors of InAs spheres decrease with increasing radius, and are nearly 2 when the radius is very small. The quantization of the electron states quenches the orbital angular momentum of the states. Actually, as some of the three dimensions increase, the electron g factors decrease. As more dimensions increase, the g factors decrease more. The dimensions perpendicular to the direction of the magnetic field affect the g factors more than the other dimension. The magnetic field along the z axis of the crystal structure causes linearly polarized emissions in the spheres, which emit unpolarized light in the absence of magnetic field.

Electronic structure and electron g factors of HgTe quantum dots

The electronic structure and electron g factors of HgTe quantum dots are investigated, in the framework of the eight-band effective-mass approximation. It is found that the electron states of quantum spheres have aspheric properties due to the interaction between the conduction band and valence band. The highest hole states are S (l = 0) states, when the radius is smaller than 9.4 nm. the same as the lowest electron states. Thus strong luminescence from H-Te quantum dots with radius smaller than 9.4 nm has been observed (Rogach et al 2001 Phys. Statits Solidi b 224 153). The bandgap of H-Te quantum spheres is calculated and compared with earlier experimental results (Harrison et al 2000 Pure Appl. Chem. 72 295). Due to the quantum confinement effect, the bandgap of the small HgTe quantum spheres is positive. The electron g factors of HgTe quantum spheres decrease with increasing radius and are nearly 2 when the radius is very small. The electron g factors of HgTe quantum ellipsoids are also investigated. We found that as some of the three dimensions increase, the electron g factors decrease. The more the dimensions increase, the more the g factors decrease. The dimensions perpendicular to the direction of the magnetic field affect the g factors more than the other dimension.

Characteristics of the conductive polyimide film surfaces induced by ultraviolet laser beam

A conducting layer with the conductivity of 1.2 Omega(-1)cm(-1) stripped in a solvent from KrF-laser-irradiated polyimide thin film is taken as a sample to determine the microstructure of the conducting layer. Fourier-transform infrared and X-ray photoelectron spectroscopies show the formation of the carbon-rich clusters after irradiation. The element analysis gives the atomic ratio of C:H:N:O for the carbon-rich cluster as 60:20:3:1. Wide-angle X-ray diffraction indicates that the conducting layer is mainly amorphous carbon with a small amount of the short-range ordered carbon-rich clusters. This study suggests a structural model with three-layer carbon sheets linked together in a random fashion for the short-range ordered carbon-rich clusters. The interplanar spacing is 3.87 Angstrom and the layer diameter 25 Angstrom. The transport model of variable-range hopping in three dimensions is used to explain the conducting behavior of the conducting layer. In our case, the short-range ordered carbon-rich clusters are assumed to be conducting islands dispersed in the amorphous carbon-rich cluster matrix.

Effective response of nonlinear composite under external AC and DC electric field

A perturbation method is used to study effective response of nonlinear Kerr composites, which are subject to the constitutive relation of electric displacement and electric field, D-alpha = epsilon(alpha)E + chi(alpha)vertical bar E vertical bar(2)E. Under the external AC and DC electric field E-app = E-a (1 + sinwt), the effective nonlinear responses and local potentials are induced by the cubic nonlinearity of Kerr materials at all harmonics. As an example in three dimensions, we have investigated this kind of nonlinear composites with spherical inclusions embedded in a host. At all harmonic frequencies, the potentials in inclusion and host regions are derived. Furthermore, the formulae of the effective linear and nonlinear responses are given in the dilute limit.

Effective AC and DC responses of nonlinear composites at higher concentration

For higher concentration of inclusions, an effective medium approximation (EMA) method is used to investigate the bulk effective response of weakly nonlinear composites, which are subject to the constitutive relation of electric displacement and electric field, D-alpha = epsilon E-alpha + chi(alpha)|E|(2) E. As an example of three dimensions, under the external AC and DC electric fields E-app = E-a (1 + sin omega t), we have derived the general effective nonlinear response of composites by the EMA method for higher concentration of spherical inclusions. Furthermore, the effective nonlinear responses at harmonics are predicted.

基于Vega Prime的多水下机器人视景仿真系统的设计与实现

介绍了一套多水下机器人三维视景仿真系统。该系统采用虚拟现实技术，利用虚拟仿真软件VegaPrime 与Visual C++.NET 2003 混合编程实现三维视景仿真。它主要用于海洋环境的模拟和多水下机器人运行时的位姿更新、碰撞检测、环境效果及各种特效的实时显示。此外，它还具有响应各种输入/输出设备的功能和通过人性化图形界面接口与用户进行交互的功能。

井间地震速度层析成像方法与软件系统

Crosshole Seismic tomography has been broadly studied and applied in the fields of resource exploration and engineering exploration because of its special observing manner and better resolution than normal seismic exploration. This thesis will state the theory and method of Crosshole Seismic tomography. Basing on the previous studies，the thesis studied the initial velocity model，ray-tracing method, and developed the three-dimension tomography software. All the cells that a ray passes through are of the same velocities if the paths from transmitters to receivers are straight. The cells that the each ray passes through are recorded, and rays that pass through each cell are calculated. The ray average velocity which passes through a cell is set as the cell velocity. Analogously we can make a initial node velocity model because the velocity sum is calculated on the all cells which own to a certain node, and the cell number is summed about each nodes，the ratio of the velocity sum to the all cells number is set as the node velocity. The inversion result from the initial node velocity model is better than that of the average velocity model. Ray-bending and Shortest Path for Rays (SPR) have shortcomings and limitations respectively. Using crooked rays obtained from SPR rather than straight lines as the starting point can not only avoid ray bending converging to the local minimum travel time path, but also settle the no smooth ray problem obtained by SPR. The hybrid method costs much computation time, which is roughly equal to the time that SPR expends. The Delphi development tool based on the Object Pascal language standard has an advantage of object-oriented. TDTOM (Three Dimensions Tomography) was developed by using Delphi from the DOS version. Improvement on the part of inversion was made, which bring faster convergence velocity. TDTOM can be used to do velocity tomography from the first arrival travel time of the seismic wave, and it has the good qualities of friendly user interface and convenient operation. TDTOM is used to reconstruct the velocity image for a set of crosshole data from Karamay Oil Field. The geological explanation is then given by comparing the inversion effects of different ray-tracing methods. High velocity zones mean the cover of oil reservoir, and low velocity zones correspond to the reservoir or the steam flooding layer.

武警工作倦怠及相关因素分析

Accumulating studies have been conducted on job burnout in the fields of organizational psychology and health psychology, but there are few studies investigating job burnout for people in the Chinese Armed Police Force(CAPF). This thesis explored the antecedents (social comparison, perceived control and perceived organizational support) and outcomes (incumbents’ level of task performance and psychological health) of job burnout, using data collected from 458 teachers (study 1) and 792 officers (470 lower level army cadres,150 commandos and 172 teachers, study 2) in CAPF. Two studies were carried out. The results are as follows: 1. There were significant differences among the three dimensions of job burnout for teachers: reduced accomplishment was rated significantly higher than cynicism and emotional exhaustion. 2. For the emotional exhaustion dimension, special technical soldiers gave the highest ratings and cadres provided the lowest ratings. Besides, special technical soldiers and teachers rated higher on cynicism than cadres did. 3. Perceived control significantly influenced job burnout: the higher the perceived control, the lower the three dimension of job burnout (emotional exhaustion, cynicism and reduced accomplishment). 4. Perceived control exerted impacts on psychological health directly and indirectly: the higher the perceived control, the better psychological health. Moreover, perceived control had significant effects on psychological health through emotional exhaustion: the higher the perceived control, the lower emotional exhaustion and the better psychological health. 5. The higher perceived organizational support, the lower the three dimensions of job burnout; perceived organizational support impacted psychological health through emotional exhaustion: the higher perceived organizational support, the lower emotional exhaustion and the better psychological health. 6. Job burnout exerted significant influence on task performance: the higher reduced accomplishment, the lower task performance rated by participants themselves. Drawing on the above results, measures would be taken in CAPF to enhance perceived control and perceived organizational support, to alleviate burnout and improve task performance and psychological health.

动漫行业创业者胜任特征研究

Venture has become an important force for the sustainable economic growth of China, However, research on entrepreneurs is far failed to meet the actual needs, Animation and Comic Industry is an important component of the state-led Cultural and Creative Industries. Entrepreneurship is the rapid growth of population, but the empirical research on the Animation and Comic Industry entrepreneurs’ Competent Characteristic Model is rarely heard. As a manager of a national incubator which major in Cultural and Creative Industry, study these entrepreneurs competent characteristics is my responsibility. As an exploration, the study uses Competent Characteristic Model of classical design methods and behavior events interview method, and selects entrepreneurs which of animation and comic industry business start-up period as the objects. Through coding analysis of 31 entrepreneurs’ interview information, completed the amendment to the dictionary coding, and ultimately construct the animation and comic industry entrepreneurs need to have the threshold competence model and differentiating competence model. Differentiating competence model includes six competencies: tolerance and optimism, cooperation, creative innovation, pool talents, vision, decision-making and tempo control. Threshold competence model includes twenty features, divided into three dimensions: personal characteristics, knowledge quality, capacity of the quality. Knowledge and capacity of the quality are closely related to the core work of entrepreneurs, Personal characteristics concern the deep-seated motivation of the entrepreneurs. The study also analyses and discusses the characteristics of the entrepreneurs on the demographic variables.

问题之间共性关系的意识水平对平面几何解题迁移的影响

Transfer of learning is one of the major concepts in educational psychology. As cognitive psychology develops, many researchers have found that transfer plays an important part in problem solving, and the awareness of the similarity of related problems is important in transfer. So they become more interested in researching the problem of transfer. But in the literature of transfer research, it has been found that many researchers do not hold identical conclusions about the influence of awareness of related problems during problem solving transfer. This dissertation is written on the basic of much of sub-research work, such as looking up literature concerning transfer of problem solving research, comparing the results of research work done recently and experimental researches. The author of this dissertation takes middle school students as subjects, geometry as materials, and adopts factorial design in his experiments. The influence of awareness of related problems on problem solving transfer is examined from three dimensions which are the degree of difficulty of transfer problems, the level of awareness of related problems and the characteristics of subjects themselves. Five conclusions have been made after the experimental research: (1) During the process of geometry problem solving, the level of awareness of related problems is one of the major factors that influence the effect of problem solving transfer. (2) Either more difficult or more easy of the transfer problems will hinder the influence of awareness of related problems during problem solving transfer, and the degree of difficulty of the transfer problems have interactions with the level of awareness of related problems in affecting transfer. (3) During geometry problems solving transfer, the level of awareness of related problems has interactions with the degree of student achievement. Compared with the students who have lower achievement, the influence of the level of the awareness is bigger in the students who have higher achievement. (4) There is positive correlation between geometry achievement and reasoning ability of the middle school students. The student who has higher reasoning ability has higher geometry achievement, while the level of awareness is raised, the transfer achievement of both can be raised significantly. (5) There is positive correlation between geometry achievement and cognitive style of the middle school students. The student who has independent field tendency of cognitive style has higher geometry achievement, while the level of awareness is raised, the transfer achievement of both can be raised significantly. At the end of the dissertation, the researcher offers two proposals concerning Geometry teaching on the basis of the research findings.

Utrata bezpieczeństwa żywnościowego jako źródło wewnętrznych konfliktów zbrojnych w Darfurze

Zgodnie z definicją wypracowaną w ramach ONZ, bezpieczeństwo żywnościowe istnieje gdy ludzie mają nieprzerwanie zapewniony „fizyczny i ekonomiczny dostęp do wystarczającej, bezpiecznej i bogatej w składniki odżywcze żywności”. Artykuł wyjaśnia kształtowanie się koncepcji bezpieczeństwa żywnościowego oraz wyodrębnienie jego trzech wymiarów – tj. międzynarodowego, narodowego i odnoszącego się do gospodarstwa domowego. Celem jest analiza międzyplemiennych konfliktów i wojny domowej w Darfurze w kontekście rywalizacji o zasoby zapewniające bezpieczeństwo żywnościowe mieszkańcom tej sudańskiej prowincji.

Avaliação da qualidade de serviço

Dissertação de Mestrado apresentada à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Gestão da Qualidade.

Síndrome de Burnout em farmacêuticos

Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Ciências Farmacêuticas

ACOUSTO-OPTIC IMAGING IN DIFFUSE MEDIA USING PULSED ULTRASOUND AND THE PHOTOREFRACTIVE EFFECT

Acousto-optic imaging (AOI) in optically diffuse media is a hybrid imaging modality in which a focused ultrasound beam is used to locally phase modulate light inside of turbid media. The modulated optical field carries with it information about the optical properties in the region where the light and sound interact. The motivation for the development of AOI systems is to measure optical properties at large depths within biological tissue with high spatial resolution. A photorefractive crystal (PRC) based interferometry system is developed for the detection of phase modulated light in AOI applications. Two-wave mixing in the PRC creates a reference beam that is wavefront matched to the modulated optical field collected from the specimen. The phase modulation is converted to an intensity modulation at the optical detector when these two fields interfere. The interferometer has a high optical etendue, making it well suited for AOI where the scattered light levels are typically low. A theoretical model for the detection of acoustically induced phase modulation in turbid media using PRC based interferometry is detailed. An AOI system, using a single element focused ultrasound transducer to pump the AO interaction and the PRC based detection system, is fabricated and tested on tissue mimicking phantoms. It is found that the system has sufficient sensitivity to detect broadband AO signals generated using pulsed ultrasound, allowing for AOI at low time averaged ultrasound output levels. The spatial resolution of the AO imaging system is studied as a function of the ultrasound pulse parameters. A theoretical model of light propagation in turbid media is used to explore the dependence of the AO response on the experimental geometry, light collection aperture, and target optical properties. Finally, a multimodal imaging system combining pulsed AOI and conventional B- mode ultrasound imaging is developed. B-mode ultrasound and AO images of targets embedded in both highly diffuse phantoms and biological tissue ex vivo are obtained, and millimeter resolution is demonstrated in three dimensions. The AO images are intrinsically co-registered with the B-mode ultrasound images. The results suggest that AOI can be used to supplement conventional B-mode ultrasound imaging with optical information.