基于虚拟仿真技术的计算机网络实验室的构建

分析了高校计算机网络实验教学的现状,结合我校实际情况,构建了基于虚拟仿真技术的计算机网络实验室。详细探讨了实验室软硬件条件和教学内容的建设,进一步完善了实验教学体系。     

免振捣高性能混凝土的研究

从免振捣高性能混凝土的配比设计方法、原材料选择、流变学特征和工作性能测试方法、硬化免振捣混凝土的物理力学性能、体积变形性能、耐久性能，以及免振捣混凝土的工程应用、存在的问题和发展前景等方面进行了探讨和论述。认为配制免振捣高性能混凝土宜采用体积法或改进后的体积法。     

Stochastic optimization in cooperative relay networks for revenue maximization

In cellular networks, cooperative relaying is an economic and promising way to enlarge the network capacity and coverage. In the case that multiple users and multiple relays are taken into account, efficient resource allocation is important in such networks. In this paper, we consider the joint relay power control with amplify- and-forward （AF） strategy and dynamic pricing for uplink cellular networks in order to maximize the network administrator＇s system revenue. The system revenue is associated with pricing strategies and mobile users＇ random data request, which is supported by the relay assisted transmission. To deal with the problem of the coupling in pricing and relay resource allocation, we utilize Lyapunov optimization techniques to design online pricing and relay power control without any statistic information of random events in networks. Theoretical analysis shows that the proposed algorithm can achieve a near-optimal performance and simulation results also validate its effectiveness and robustness.     

Evaluating noise annoyance cost recovery at Düsseldorf International Airport

This study estimates airport noise annoyance cost around Düsseldorf, Germany by examining rental apartment market data. Using data on regional apartment offers we estimate rent discounts of 1.04% per additional decibel of airport noise. Other sources of traffic noise induce significantly lower price effects. As a result, airport noise annoyance costs amount to about €7.5 million a year. While the noise protection fund recovers annoyance costs, the charging regime of the airport fails to fully internalize them.     

Simulation of multiregional wave-structure impact on damping elements on offshore structures

Hydrodynamic impacts of free surface waves are a widely known issue in coastal and ship engineering. They can result in severe damage to important industry facilities (e.g. offshore wind turbines) or means of transport (e.g. oil tankers). This kinds of damage give rise to different difficulties due to economic losses and environmental pollution. On that account, the present paper deals with a special feature of a protective mechanism for offshore structures. We develop a numerical multiregional wave-structure impact model of a damping element prototype. The investigated prototype consists essentially of an elastic cover that is attached to the cylindrical mono-pile foundation at wave level. The chamber between the flexible structure and the mono-pile is filled with a liquid. A prototype of the damping element has been constructed as a mono-pile structure test object. In order to measure the hydrodynamic loads on the test object, we placed piezoelectric sensors on the stagnation points of the mono-pile. The multiregional simulation model created is able to imitate the wave impact and its consequences. These implications include the deformation and oscillation of the elastic shell, the resultant force affecting the pile and the dissipation power of the damping fluid. The dissipation power can be understood as the crucial factor preventing the shell from oscillating over long periods of time. It enables us to state the mechanical energy that is transfered due to the wave’s impact on the damping fluid region.     

舰船电子设备远程维修系统架构研究

该文提出了基于军用互联网构建舰船电子设备远程维修系统的总体设计方案,并讨论了系统中关键模块的实现方法。该系统以信息的流动代替维修专家的流动,能够实现舰船电子设备远程故障诊断和维修,缩短维修时间、节约维修开支。     

Design and Combustion Characteristic Analysis of Free Piston Stirling Engine External Combustion System

The free piston Stirling engine external combustion system was simulated to investigate the diesel-air combustion characteristics in order to demonstrate its feasibility by computational fluid dynamics (CFD). The different effects on combustion were distinguished by analyzing the combustion burner, the injection position of diesel oil, the front tube arrangement of Stirling heater head and the back fin. The results show that the tilted front tube arrangement of the heater head with the back fin is the best practicable technology while the distance between the diesel nozzle position and the swirler top is 0. Its total heat flux is 15.6 kW, and the average heat transfer coefficients of the front and back tubes are 127W/(m² · K) and 192W/(m² · K), respectively. The heat transfer is mainly through convection, and the proportion of radiative heat transfer is only 16.9%. The best combustion efficiency of the free piston Stirling engine external combustion system is 86%.     

Immobility in travel diary surveys

The share of immobile persons, i.e. persons not leaving their homes on a given reporting day, is both a central result and a prime quality indicator of a travel diary survey. The wide range of values for the share of immobiles reported in travel diary and time budget survey literature has motivated this in-depth analysis of the reasons for these disparities. This paper collates available evidence on the share of immobiles in travel diary surveys. The share of these non-travellers (UK), or no-trippers (US), varies greatly between otherwise similar surveys. After analysing both disaggregate and aggregate information, this paper concludes that the share of immobiles should be in the range of 8%–12% for the standard one-day, weekday-only travel diary. The analysis suggests that a substantial share of respondents refuse to participate in a soft way, i.e. by claiming not to have left the house. In its conclusions, the paper sketches new ways to reduce the share of such soft refusers during the interview and to identify them during the analysis.      

Validation of railway vehicle dynamic models in training simulators

Training simulators play an important role for sustaining safety, efficiency and cost effective railway transportation. Dynamic modelling of train systems is one of the main modules of training simulators. Validation of the dynamic models with collected real data ensures the fidelity of the simulator utilising the respective models. In this study, a validation process (Dynamic Modelling Validation Process (DyMVaP)) which is developed to support the validation of railway dynamic models is introduced. However, the proposed process can also be used in validating other dynamic models as well. The developed process is based on five steps including the preparation of validation scenarios, sensor deployment, real data collection, data preparation, and comparison of simulated and measured data. Note that the proposed DyMVaP was used for the validation of a full-mission training simulator so called TRENSIM, which was developed for Turkish State Railways. During the study it is realised that the current speed, travelled distance, acceleration (in x, y, z directions), rotation angles (around x, y, z axes), air pressure, in-train pressure/tension forces, traction motor currents, catenary voltage, positions of controllers must be collected synchronously by using proper sensors in order to ensure simulation validation. The required data was collected from locomotive body, bogies, wheel sets and connection of railway cars. The data (～200?GB) collected from the field by applying 27 different scenarios and transformed into appropriate data for utilising the generated dynamic models within the simulator. The measured and simulated data were also compared visually using graphical representation of the parameters as well as performing computations regarding the magnitude, phase and comprehensive error factors.