大学生奥运志愿者服务动机及动机过程化的研究——以北师大奥运志愿者为例

本文以北京师范大学16个院系的奥运会志愿者为研究对象,结合问卷调查和访谈两种研究方法探究大学生奥运志愿者参与志愿服务的动机以及其动机过程化。以此研究为基础,作者对志愿者工作提出了建议。

大学生志愿者服务动机调查和思考

以福建省高校的大学生志愿者为研究对象,采取问卷调查与个别访谈相结合的方法,探析大学生初始志愿动机与持续志愿动机的特点,并通过数据对比分析,探究大学生志愿者参与志愿服务的动机化过程。结果表明:初始志愿动机为发展型与责任型的志愿者会出现更多的志愿服务行为;志愿服务过程对持续服务动机具有转化作用。进而依此调查结果,思考如何有针对性地改进目前高校大学生志愿者工作。

A Vector-based Cellular Automata Model for Simulating Urban Land Use Change

Cellular Automata(CA) is widely used for the simulation of land use changes. This study applied a vector-based CA model to simulate land use change in order to minimize or eliminate the scale sensitivity in traditional raster-based CA model. The cells of vector-based CA model are presented according to the shapes and attributes of geographic entities, and the transition rules of vector-based CA model are improved by taking spatial variables of the study area into consideration. The vector-based CA model is applied to simulate land use changes in downtown of Qidong City, Jiangsu Province, China and its validation is confirmed by the methods of visual assessment and spatial accuracy. The simulation result of vector-based CA model reveals that nearly 75% of newly increased urban cells are located in the northwest and southwest parts of the study area from 2002 to 2007, which is in consistent with real land use map. In addition, the simulation results of the vector-based and raster-based CA models are compared to real land use data and their spatial accuracies are found to be 84.0% and 81.9%, respectively. In conclusion, results from this study indicate that the vector-based CA model is a practical and applicable method for the simulation of urbanization processes.

An Expert System Based on Multi-reasoning Mechanism for Port Machine Diagnosis

Expert system plays an important role in port machine diagnosis, which aims at automatic equipment test for higher availability and efficiency of port operations. In this study, a port machine diagnosis expert system is proposed based on multi-reasoning mechanism. Relying on the knowledge acquired from the experienced experts in the port machine engineering, the system builds a library of relative experience and a set of rules of reasoning and estimating. Multi-reasoning mechanism that simulates the decision-making process of domain experts is employed to achieve reliable diagnosis results. The reasoning machine integrates artificial neural network, uncertain decision making and decision tree, which complements each other by sustainable growing voting mechanism. The effect of this multi-reasoning mechanism is evaluated and validated by means of Matthew＇s Correlation Coefficient （MCC）. The system incorporating the mechanism is successfully designed, implemented and applied in Shanghai Port.

Probabilistic model for remain passenger queues at subway station platform

The remain passenger problem at subway station platform was defined initially,and the period variation of remain passenger queues at platform was investigated through arriving and boarding analyses.Taking remain passenger queues at platform as dynamic stochastic process,a new probabilistic queuing method was developed based on probabilistic theory and discrete time Markov chain theory.This model can calculate remain passenger queues while considering different directions.Considering the stable or variable train arriving period and different platform crossing types,a series of model deformation research was carried out.The probabilistic approach allows to capture the cyclic behavior of queues,measures the uncertainty of a queue state prediction by computing the evolution of its probability in time,and gives any temporal distribution of the arrivals.Compared with the actual data,the deviation of experimental results is less than 20%,which shows the efficiency of probabilistic approach clearly.

What Life Is and How It Originated

This paper refutes the mechanistic interpretation of cellular dynamics and contends that the life-giving principle is sustained growth a biological system and is uninterrupted growth balanced in a dynamic state by synthesis and dissolution. The process began by an oxidation/reduction reaction on the surface of pyrite energized photovoltaically by sunlight. Hydrogen sulfide was oxidized, carbon dioxide was reduced, and phosphate on the surface of the pyrite was a reactant. The first organic compounds were sulfides and phosphoglycerates. These organophosphates were at the center of the energy cycle of all life where the dehydration of a relatively unreactive ＂low-energy＂ two-phosphoglycerate transforms it into the ＂high-energy＂ phosphoenolpyruvate. Life began as a growth process and continues to grow ceaselessly out of necessity. It cannot discontinue the life-giving energy flow without irreparable loss of the process. All forms of life past and present were and are stabilized systems in which the growth process is contained in metabolic turnover.

Analyses of surrogate models for calculating thermophysical properties of aviation kerosene RP-3 at supercritical pressures

Aviation kerosene is commonly used in combustion and regenerative engine cooling processes in propulsion and power-generation systems,including rocket,scramjet,and advanced gas turbine engines.In this paper,many surrogate models proposed in the open literature are examined for their applicability and accuracy in calculating thermodynamic and transport properties of the China aviation kerosene RP-3 at supercritical pressures,based on the extended corresponding-states methods.The enthalpy change from endothermic decomposition and low heating value from combustion of the jet fuel are also evaluated.Results from a number of simple and representative surrogate models,which contain species components ranging from 1 to10,are analyzed in detail.Data analyses indicate that a surrogate model with four species is the best choice for thermophysical property calculations under the tested conditions,with fluid temperature up to 650 K at various supercritical pressures.The surrogate model is particularly accurate in predicting the pseudo-critical temperature of aviation kerosene RP-3 at a supercritical pressure.A simple surrogate model containing the n-decane species and a surrogate model containing 10 species are the other two acceptable options.The work conducted herein is of practical importance for theoretical analyses and numerical simulations of various physicochemical processes at engine operating conditions.

Numerical simulation of turbulent combustion: Scientific challenges

Predictive simulation of engine combustion is key to understanding the underlying complicated physicochemical processes,improving engine performance,and reducing pollutant emissions.Critical issues as turbulence modeling,turbulence-chemistry interaction,and accommodation of detailed chemical kinetics in complex flows remain challenging and essential for highfidelity combustion simulation.This paper reviews the current status of the state-of-the-art large eddy simulation(LES)/probability density function(PDF)/detailed chemistry approach that can address the three challenging modelling issues.PDF as a subgrid model for LES is formulated and the hybrid mesh-particle method for LES/PDF simulations is described.Then the development need in micro-mixing models for the PDF simulations of turbulent premixed combustion is identified.Finally the different acceleration methods for detailed chemistry are reviewed and a combined strategy is proposed for further development.