通信机房的建设及防雷击措施

作者长期在通信行业从事一线建设工作,总结工作中的经验得失,着重介绍无人机房的合理选择、规划及机房建设中应着重注意的防雷击措施。     

数字滤波检漏仪检测实用技术

通过对几种检测管道漏泄方法的优缺点比较,得出目前铁路供水管网检漏设备最为实用的设备是数字滤波检漏仪。根据多年的检漏实践,归纳出检测管道泄漏点综合操作程序。     

MSTP内嵌RPR技术在沈阳地铁中的应用与设计

介绍MSTP内嵌RPR技术在沈阳地铁传输系统的应用方案,对MSTP内嵌RPR的技术特点进行简要分析,并给出工程实施设计建议.     

浅谈高液限粉(粘)土的施工

从高液限粉(粘)土的试验报告、土的特性、压实原理、施工工艺的特性、冲击式压路机的补压和效果等方面论述了现场施工过程的要点。     

吹填沙法建防洪堤

本文介绍福建省若干个采用吹填沙的方法建造堤防工程的情况 ,其中详细介绍了桔园洲防洪堤工程用吹填法构筑反滤沙堤的施工工艺及特点。同时本文还总结了吹填沙施工方法的特性和优点     

Habitual travel behaviour: Evidence from a six-week travel diary

This paper introduces different methods to measure similarity of travel behaviour addressing the question of how repetitious travel behaviour actually is. It compares empirical results of the different methods based on the data from a six-week travel diary. In general, the results show that the day-to-day behaviour is more variable if measured with trip-based methods instead of methods based on time budgets. Furthermore, it is confirmed that the similarity declines if the method captures more of the complexity of the travel pattern. It is also shown that travel behaviour is neither totally repetitious nor totally variable. Even for the whole observation period, it is demonstrated that two days always have some common elements. Additionally, it is found that the different methods yield the same pattern of variability for different types of day. Travel behaviour is clearly more stable on work days. Similar results for all methods are also obtained concerning the question of how long the minimum period of observation should be. All measures show that the period should not be less than two weeks if one aims at measuring variability.     

Process Save Reduction by Macro Joint Approach: The Key to Real Time and Efficient Vehicle Simulation

Applying a non-linear model reduction method to the tire suspension system of road vehicles enables an automatic transfer of complex offline simulation vehicle models to a mathematical model, which fits the real time simulation requirements. The basic assumption, that high frequent inner suspension dynamics are not relevant to handling manoeuvres, converts the differential algebraic equation system (DAE) of suspensions with kinematical closed loops into pure elasto-kinematical linkage equations. The equations of motions can be represented as an ordinary differential equation system (ODE) and considerable simulation time reductions are obtained for the off-line simulation and real time simulation is enabled. This so-called macro joint approach is an alternative modelling method to the well-known look-up table representation of suspension kinematics but it keeps the parameterisation of the original suspension model and is suitable to parameterised real time MBS models. With a second step the dynamics, caused by compliance in the suspension bushings, are reduced to their quasi-static behaviour. The consideration of these quasi-elasticity has nearly no influence on the necessary simulation time. This contribution shows the theoretical background and demonstrates the advantage of the macro joint model reduction approach on a typical vehicle example.     

Correlation between automotive CO, HC, NO, and PM emission factors from on-road remote sensing: implications for inspection and maintenance programs

Carbon monoxide (CO), hydrocarbon (HC), and nitrogen oxide (NO) emission factors (EFs) are measured with a commercial vehicle emissions remote sensing system (VERSS) during a large-scale vehicle exhaust emissions study in Las Vegas. Particulate matter (PM) EFs are simultaneously measured for individual vehicles with a newly developed PM-VERSS based on ultraviolet backscatter light detection and ranging (Lidar). The effectiveness of CO and HC EFs as proxy for NO and PM EFs for spark-ignition vehicles is evaluated. Poor correlations were found between EFs for pollutants on an individual vehicle basis indicating that high EFs for one or more pollutants cannot be used as a predictor of high EFs for other pollutants. Stronger functional relationships became evident after averaging the EF data in bins based on rank-order of a single pollutant EF. Low overlap between the highest 10% emitters for CO, HC, NO, and PM was found. These results imply that for an effective reduction of the four pollutants, inspection and maintenance (I/M) programs, including clean screening, should measure all four pollutants individually. Fleet average CO and HC concentrations determined by gaseous VERSS were compared with fleet average CO and HC concentrations measured at low-idle and at high-idle during local I/M tests for spark-ignition vehicles. The fleet average CO concentrations measured by I/M tests at either idle were about half of those measured by remote sensing. The fleet average high-idle HC concentration measured by I/M tests was about half of that measured by VERSS while low-idle I/M and VERSS HC average concentrations were in better agreement. For a typical vehicle trip, most of the fuel is burned during non-idle conditions. I/M measurements collected during idling conditions may not be a good indicator of a vehicle’s potential to be a high emitter. VERSS measurements, when the vehicle is under a load, should more effectively identify high emitting vehicles that have a large contribution to the mobile emissions inventory.