662 research outputs found
Adjusting to Really Big Changes: The Labor Market in China, 1989-2009
China’s emerging labor market was buffeted by changes in demand and supply and institutional changes in the last two decades. Using the Chinese Urban Household Survey data from 1989 to 2009, our study shows that the market responded with substantial changes in the structure of wages and in employment and types of jobs that workers obtained that mirrors the adjustments found in labor markets in advanced economies. However, the one place where the Chinese labor market appears to diverge from the labor markets in advanced countries is the rapid convergence in earnings and occupational positions of cohorts who entered the job market under more or less favorable conditions. On this dimension, China’s labor market seems more flexible than those in other countries. Three related factors may explain this pattern: (1) the rapid growth of China’s economy; (2) the high rate of employee turnover; (3) the relative weakness of internal labor markets in China. Bottom line, the Chinese labor market has responded about as well as one could expect to the changes in the demand and supply factors and institutional shocks in this critical period in Chinese economic history.
State estimation based on unscented Kalman filter for semi-active suspension systems
In this paper, a novel approach to estimate vehicle vibration state information in real time is proposed; it is based on unscented Kalman filter (UKF) theory. The UKF is based on the unscented transfer technique which considers high order terms during the measurement and update stage during the estimation. The proposed observer uses easily accessible measurements such as accelerations and suspension deflections to estimate the sprung and unspring mass vertical velocity for the suspension systems of full vehicle under unknown road disturbance. And it is with low sensitivity and robust to the unknown road surfaces. Matlab/Carsim co-simulation experiments are carried out to validate the performance of the estimator under two typical road excitations. The simulation results clearly indicate that the proposed UKF sate observer is precise
Neutral network-PID control algorithm for semi-active suspensions with magneto-rheological damper
In this paper, a semi-active suspension control system based on Magneto-Rheological (MR) damper is designed for a commercial vehicle to improve the ride comfort and driving stability. A mathematical model of MR damper based on the Bouc-Wen hysteresis model is built. The mathematical model could precisely describe the characteristics of MR damper compared with the bench test results. The neural network-PID controller is designed for the semi-active suspension systems. According to the numerical results, the proposed controller can constrain vehicle vibrations and roll angle significantly. A detailed multi-body dynamic model of the light vehicle with four semi-active suspensions are established, and an actual vehicle handling and stability tests are carried out to verify the control performances of the proposed controller. It can be concluded that MR semi-active suspension systems can play a key role in coordination between the ride comfort and handling stability for the commercial vehicle
Mixed strategy may outperform pure strategy: An initial study
In pure strategy meta-heuristics, only one search strategy is applied for all
time. In mixed strategy meta-heuristics, each time one search strategy is
chosen from a strategy pool with a probability and then is applied. An example
is classical genetic algorithms, where either a mutation or crossover operator
is chosen with a probability each time. The aim of this paper is to compare the
performance between mixed strategy and pure strategy meta-heuristic algorithms.
First an experimental study is implemented and results demonstrate that mixed
strategy evolutionary algorithms may outperform pure strategy evolutionary
algorithms on the 0-1 knapsack problem in up to 77.8% instances. Then
Complementary Strategy Theorem is rigorously proven for applying mixed strategy
at the population level. The theorem asserts that given two meta-heuristic
algorithms where one uses pure strategy 1 and another uses pure strategy 2, the
condition of pure strategy 2 being complementary to pure strategy 1 is
sufficient and necessary if there exists a mixed strategy meta-heuristics
derived from these two pure strategies and its expected number of generations
to find an optimal solution is no more than that of using pure strategy 1 for
any initial population, and less than that of using pure strategy 1 for some
initial population
Cognitive Mirage: A Review of Hallucinations in Large Language Models
As large language models continue to develop in the field of AI, text
generation systems are susceptible to a worrisome phenomenon known as
hallucination. In this study, we summarize recent compelling insights into
hallucinations in LLMs. We present a novel taxonomy of hallucinations from
various text generation tasks, thus provide theoretical insights, detection
methods and improvement approaches. Based on this, future research directions
are proposed. Our contribution are threefold: (1) We provide a detailed and
complete taxonomy for hallucinations appearing in text generation tasks; (2) We
provide theoretical analyses of hallucinations in LLMs and provide existing
detection and improvement methods; (3) We propose several research directions
that can be developed in the future. As hallucinations garner significant
attention from the community, we will maintain updates on relevant research
progress.Comment: work in progress; 21 page
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