刘勰"文"体观的文化诠释

刘勰文体论是一个逻辑严密的文化叙事系统。以“文”观念为基础,刘勰讨论了诗歌以下等十六种具体文体。总体上看,刘勰文体论既重文体的自然起源,又重文体的义理关系,体现了事实描写、逻辑描写与知识寓意、审美寓意相统一的文化精神。     

路基工程最优化计算数学模型研究

提出了以路基变坡点为变量，路基工程费用为目标函数的路基工程最优化设计数学模型，并给出了解析形式的目标函数和约束矩阵。为河道，公路及铁路路基最优化设计奠定了理论基础。     

Policy innovations of the US intermodal surface transportation efficiency act and clean air act amendments

In combination, the Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA) and the Clean Air Act Amendments of 1990 (CAAA) are innovative and aggressive efforts to move US cities toward integrated transportation and air quality planning. Under these complementary laws, air quality has become a major national transportation goal. In areas with serious air pollution, air quality will be a major consideration in determining the future shape of urban transportation.This paper considers how the CAAA and ISTEA combine to provide an innovative national policy approach of interest to countries seeking to encourage sustainable development in urban centers. The CAAA mandates measurable and enforceable air quality targets. Nation-wide standards are set for acceptable levels of carbon monoxide, ground level ozone, and small particulates. ISTEA includes directions for transportation planners and decision-makers to follow to reach air quality and other goals — transportation planning must emphasize system efficiency, and for cities with severe air pollution, transportation projects are expected to contribute to cleaner air. Each urban area has flexibility in how it applies this framework to reflect its priorities and solve its problems. Strict federal sanctions provide incentives for compliance with both laws.Enactment of these laws has produced a period of transition and uncertainty as well as of challenge and opportunity for planners and elected officials. The next several years, the US will provide one national laboratory and over 100 different urban laboratories for innovative approaches to integrate transportation and environmental policies to resolve major urban problems.Abbreviations CAAA Clean Air Act Amendments of 1990 - CO Carbon monoxide - ECO Employee Commute Option - EPA US Environmental Protection Agency - HC Transportation hydrocarbons - I/M Inspections and maintenance program - ISTEA Intermodal Surface Transportation Efficiency Act of 1991 - MPO Metropolitan planning organizations - NO_x Nitrogen oxides - PPM Parts per million - PM₁₀ Small particulate matter - SIP State Implementation Plan - TIP Transportation Improvement Program - TCM Transportation control measures - VMT Vehicle miles traveled     

船用控制装置的结构电磁兼容设计

本文通过对船用控制装置中电磁干扰传播途径、各类屏蔽机理的分析,提出了船用控制装置结构设计中解决电磁兼容问题的几种有效方法.     

舰船能量管理系统技术研究

随着全电力舰船的发展,能量管理系统的应用逐渐为人所重视.本文介绍了舰船能量管理系统(PMS)的功能模块、信息流、网络结构.并着重介绍了PMS对推进系统的管理.     

船用高速柴油机多台增压器相继增压计算分析

介绍了多台增压器相继增压系统的工作原理及系统组成,并建立了某船用V型高速柴油机采用四台增压器相继增压的计算模型.计算结果表明,采用多台增压器进行相继增压可以明显地改善柴油机低工况性能,有效地扩大柴油机作为船用主机的低工况运行范围.     

丘陵及山地城市建设用地竖向规划方法研究

该文针对丘陵及山地城市的特点,重点从地形地貌评价、防洪排涝规划及竖向管理措施等三个方面对山地城市竖向规划方法及一般技术路线进行了论证及总结,并简要介绍了ArcGIS技术在竖向规划中的应用。     

中新天津生态城市政配套工程中创新理念的应用

该文阐述了在中新天津生态城市政道路及排水工程设计中,所采用的生态、节能、环保的设计理念和思路,对其他市政工程的建设具有借鉴意义。     

长纤维增强热塑性复合材料在汽车前端模块中的应用

世界汽车材料技术发展的主要方向是轻量化和环保化。汽车塑料相对密度低,以塑代钢制作外装件可减轻汽车自重,达到节能减排目的。文章介绍了长纤维增强热塑性复合材料(简称LFT)在国内外汽车行业的应用情况以及在汽车前端模块的应用状态。对LFT的力学性能等方面也做了比较详细的介绍,并就传统钣金焊接和LFT制作的前端模块进行了各个方面的对比分析,从中得出了LFT材料在该零件开发中的应用前景是令人期盼的。最后对前端模块应用复合材料的设计开发提供了一些建议。     

Effective assessment of tyre–road friction coefficient using a hybrid estimator

Vehicle stability and active safety control depend heavily on tyre forces available on each wheel of a vehicle. Since tyre forces are strongly affected by the tyre–road friction coefficient, it is crucial to optimise the use of the adhesion limits of the tyres. This study presents a hybrid method to identify the road friction limitation; it contributes significantly to active vehicle safety. A hybrid estimator is developed based on the three degrees-of-freedom vehicle model, which considers longitudinal, lateral and yaw motions. The proposed hybrid estimator includes two sub-estimators: one is the vehicle state information estimator using the unscented Kalman filter and another is the integrated road friction estimator. By connecting two sub-estimators simultaneously, the proposed algorithm can effectively estimate the road friction coefficient. The performance of the proposed estimation algorithm is validated in CarSim/Matlab co-simulation environment under three different road conditions (high-μ, low-μ and mixed-μ). Simulation results show that the proposed estimator can assess vehicle states and road friction coefficient with good accuracy.