DETERMINANTS OF TURNOVER INTENTIONS AMONG CHINESE OFF FARM MIGRANTS

This study examines the determinants of turnover intentions of off farm migrant workers, using data collected from China's Jiangsu Province. Turnover intention is posited to be a function of demographic/human capital characteristics, job characteristics and job satisfaction. We find that higher levels of education have a positive effect on reported turnover intentions, while higher income and job satisfaction have a negative effect on turnover intentions. As turnover intentions represent a good proxy for actual turnover, the results can be viewed as providing reliable predictors of job mobility among off farm migrant workers at a time when there is a growing shortage of such workers in China's coastal provinces.

Wavelength-division-multiplexed Transmission Using Semiconductor Optical Amplifiers And Electronic Impairment Compensation

Over the last decade, rapid growth of broadband services necessitated research aimed at increasing transmission capacity in fiber-optic communication systems. Wavelength division multiplexing (WDM) technology has been widely used in fiber-optic systems to fully utilize fiber transmission bandwidth. Among optical amplifiers for WDM transmission, semiconductor optical amplifier (SOA) is a promising candidate, thanks to its broad bandwidth, compact size, and low cost. In transmission systems using SOAs, due to their large noise figures, high signal launching powers are required to ensure reasonable optical signal-to-noise ratio of the received signals. Hence the SOAs are operated in the saturation region and the signals will suffer from SOA impairments including self-gain modulation, self-phase modulation, and inter channel crosstalk effects such as cross-gain modulation, cross-phase modulation, and four-wave mixing in WDM. One possibility to circumvent these nonlinear impairments is to use constant-intensity modulation format in the 1310 nm window where dispersion is also negligible. In this dissertation, differential phase-shift keying (DPSK) WDM transmission in the 1310 nm window using SOAs was first considered to increase the capacity of existing telecommunication network. A WDM transmission of 4 x 10 Gbit/s DPSK signals over 540 km standard single mode fiber (SSMF) using cascaded SOAs was demonstrated in a recirculating loop. In order to increase the transmission reach of such WDM systems, those SOA impairments must be compensated. To do so, an accurate model for quantum-dot (QD) SOA must be established. In this dissertation, the QD-SOA was modeled with the assumption of overall charge neutrality. Static gain was calculated. Optical modulation response and nonlinear phase noise were studied semi-analytically based on small-signal analysis. The quantitative studies show that an ultrafast gain recovery time of ~0.1 ps can be achieved when QD-SOAs are under high current injection, which leads to high saturation output power. However more nonlinear phase noise is induced when the QD-SOAs are used in the transmission systems operating at 10 Gbit/s or 40 Gbit/s. Electronic post-compensation for SOA impairments using coherent detection and digital signal processing (DSP) was investigated next in this dissertation. An on-off keying transmission over 100 km SSMF using three SOAs at 1.3 [micrometer] were demonstrated experimentally with direct detection and SOA impairment compensation. The data pattern effect of the signal was compensated effectively. Both optimum launching power and Q-factor were improved by 8 dB. For advanced modulation formats involving phase modulation or in transmission windows with large dispersion, coherent detection must be used and fiber impairments in WDM systems need to be compensated as well. The proposed fiber impairment compensation is based on digital backward propagation. The corresponding DSP implementation was described and the required calculations as well as system latency were derived. Finally joint SOA and fiber impairment compensations were experimentally demonstrated for an amplitude-phase-shift keying transmission

A Simulation and Experimental Study of Active Disturbance Rejection for Industrial Pressure Control

The quality of control loop is very important in hydraulic machineries, where pressure must be accurately regulated in the presence of various disturbances. Proportional-Integral-Derivative (PID) control has dominated the industry for a long time and it is by far the most popular general purpose controller for pressure control. The purpose of this study is to conduct a simulation and experimental study comparing PID with an emerging new technology, namely active disturbance rejection control (ADRC). For the purpose of this study, an experimental testbed similar to those used in industry settings is used; its mathematic model is derived and used in the simulation study. A linearized model is also derived for the purpose of PID tuning, where various methods such as the standard Ziegler-Nichols method, the pole-placement and the trial-and-error method are tested. As for the tuning of ADRC, a method is proposed to determine the critical gain parameter, which is the only plant parameter needed. All the simulation and experimental tests are designed based on the practical scenarios, so that the controller tuning, the tracking performance, the disturbance rejection capability and the energy consumption can be studied meaningfully for future industrial applications. Initial results indicate that, with the same bandwidth, ADRC can be used in a wider range of set point tracking than PID. Furthermore, ADRC is easy to tune and has clear advantages over PID in terms of disturbance rejection and energy saving in all simulation and experiment results. In summary, results of this study indicates that ADRC, as a general purpose controller, is a viable solution for pressure control applications, and an alternative to PID

Joint Fiber and SOA Impairment Compensation Using Digital Backward Propagation

An electronic scheme for joint postcompensation of fiber and semiconductor optical amplifier (SOA) impairments based on coherent detection and digital backward propagation is proposed and demonstrated. A 10-GBd amplitude-phase-modulated transmission system was demonstrated experimentally using semiconductor optical amplification. The Q-factor of the received signal was improved by 5 dB with simultaneous fiber and SOA impairment compensation in the electrical domain

Electronic Compensation of Nonlinear Effects ofSemiconductor Optical Amplifiers

An electrical post-compensation scheme for semiconductor optical amplifier (SOA) impairments has been proposed. An on-off keying (OOK) transmission over 100 km standard single mode fiber (SSMF) and three SOAs was demonstrated experimentally with SOA impairment compensation. An 8dB improvement in Q-factor has been achieved

Unified analysis of finite-size error for periodic Hartree-Fock and second order M{\o}ller-Plesset perturbation theory

Despite decades of practice, finite-size errors in many widely used electronic structure theories for periodic systems remain poorly understood. For periodic systems using a general Monkhorst-Pack grid, there has been no comprehensive and rigorous analysis of the finite-size error in the Hartree-Fock theory (HF) and the second order M{\o}ller-Plesset perturbation theory (MP2), which are the simplest wavefunction based method, and the simplest post-Hartree-Fock method, respectively. Such calculations can be viewed as a multi-dimensional integral discretized with certain trapezoidal rules. Due to the Coulomb singularity, the integrand has many points of discontinuity in general, and standard error analysis based on the Euler-Maclaurin formula gives overly pessimistic results. The lack of analytic understanding of finite-size errors also impedes the development of effective finite-size correction schemes. We propose a unified analysis to obtain sharp convergence rates of finite-size errors for the periodic HF and MP2 theories. Our main technical advancement is a generalization of the result of [Lyness, 1976] for obtaining sharp convergence rates of the trapezoidal rule for a class of non-smooth integrands. Our result is applicable to three-dimensional bulk systems as well as low dimensional systems (such as nanowires and 2D materials). Our unified analysis also allows us to prove the effectiveness of the Madelung-constant correction to the Fock exchange energy, and the effectiveness of a recently proposed staggered mesh method for periodic MP2 calculations [Xing, Li, Lin, J. Chem. Theory Comput. 2021]. Our analysis connects the effectiveness of the staggered mesh method with integrands with removable singularities, and suggests a new staggered mesh method for reducing finite-size errors of periodic HF calculations

The Application of Augmented Reality Technology for the Anesthesiology Major

Anesthesiology is an important subject for in-depth research in the fields of clinical anesthesia, critical care medicine, first-aid and resuscitation, and pain treatment. As an important branch of clinical medicine, it has strong practicality and applicability. It has the commonality of clinical medicine and the specialty of anesthesiology. Carrying out anesthesiology practice teaching using augmented reality (AR) to simulate the experimental environment and scene simulation is of great significance to promoting the development of anesthesia practice teaching. This article mainly introduces the augmented reality technology. It not only analyzes the main forms of augmented reality technology in anesthesiology, but also explores the application of augmented reality technology for anesthesiology in the new era