隧道掘进节能环保水压爆破施工工法

隧道施工用普通钻爆法掘进,炸药利用率偏低、循环进尺较短、施工环境污染较严重。节能环保水压爆破,采用在炮孔中填塞水袋等措施,提高了炸药的利用率,文章介绍该工法施作程序和注意事项。     

某轻钢结构厂房的设计分析

通过工程实例,详细介绍一般轻钢结构厂房的结构分析、节点设计、支撑体系、刚架柱脚及檩条设计方法,表明轻钢结构在工业厂房中的应用有其优越性。     

依托城乡公交的"客运+物流"实践研究 ——以浙江省永康市为例

日益紧密的城乡联系增加了生产和生活性物品的流通需求,但传统的乡村物流难以令人满意.浙江省永康市依托城乡公交的"客运+物流"服务,以低成本、高时效性和高可靠性满足了运输需求.为使后续推广更成熟、更高效,有必要选取典型案例深入研究.以最早开通"客运+物流"服务的浙江省永康市K303路城乡公交为例,从居民、城市管理者、运营企业三个视角分析"客运+物流"的积极效益.综合运用实地踏勘、问卷调查、访谈、大数据分析等方法,从市区、乡镇物流网点布局和物流全过程服务品质两个维度进行量化分析,发现存在网点数量少、寄取件不便、物品包装简陋、物流信息不透明、服务体验不佳等问题.基于客运与物流品质同步提升的理念,提出网点增设、布局优化、运营模式调整、融入智慧物流的全过程服务提质等方面的具体方法和优化方案,并建议依托通村公交、社区公交实现"市区—乡镇—村庄"客运与物流一体化的远期发展目标.     

Evaluating impacts of coastal flooding on the transportation system using an activity-based travel demand model: a case study in Miami-Dade County,FL

Transportation - Recent climatic disasters have shown the vulnerability of transportation infrastructures against natural hazards. To understand the risk of coastal hazards on urban travel...     

框架结构钢筋混凝土面板裂缝分析与防治

对重庆果园港区码头现浇钢筋混凝土面板裂缝进行理论分析，找出产生裂缝的原因，并针对性地采取措施。这些措施包括：提高混凝土本身抗拉强度；采用混凝土后浇带方式在施工期间解除束缚面板混凝土的约束；通过对混凝土原材料、配合比的优化和采取施工措施来减少混凝土的自生收缩、塑性收缩、干缩及温度变化和内外温差引起的收缩，从而大大降低混凝土的收缩应力。     

散货船价格跌无可跌

散货船是全球船队保有量最大的船型,新船成交量在2006～2010年,年均超过1亿载重吨,尤其是2007年市场巅峰期订单量达到了1.7亿载重吨。金融危机后,新船需求骤降,2011年散货船新船订单不足4000万载重吨,2012年前三季度仅成交1310万载重吨,尽管成交量仍位居各船型之首,但与往日行情已不可同日而语。     

Vehicle distance estimation using a mono-camera for FCW/AEB systems

For robust vision-based forward collision warning (FCW) and autonomous emergency braking (AEB) systems, not only reliable detection performance including high detection rate and low false positives but also accurate measurement output of a target vehicle is required. Especially, in order to reduce false alarm or activation of FCW/AEB systems, the systems require the precise measurement output of a target object, such as position, velocity, acceleration, and time-to-collision (TTC). In this study, we developed a measurement estimation algorithm of a target vehicle using a monocular camera. This method estimates two cases of vehicle widths for a target vehicle by using the detected lane information and a pin-hole camera model. After that, the position, velocity, acceleration, and TTC of a target vehicle are estimated by using a Kalman filter for the each estimated vehicle width. To improve robustness, the both estimation results using the detected lane information and the pinhole camera model are fused. This estimation algorithm was evaluated and compared with the state-of-the-art technology. As a result, the proposed measurement output estimation method can improve the performance of the FCW/AEB systems.     

Effects of Injection Timing on Transient Performance of A Regulated Two-Stage Turbocharged Diesel Engine with Turbine Bypass Valve

The object of this paper is to reduce soot emissions under typical 5s transient conditions of constant speed and increasing torque. And effects of fuel injection timing on combustion and emissions parameters were experimentally and numerically studied in a regulated two-stage turbocharged diesel engine with a turbine bypass valve (TBV). The test results indicated that: the smaller TBV opening could improve deterioration of smoke emissions and BSFC at medium and heavy loads. Afterward, the full-stage injection timing (FSIT) strategies (delaying injection timing during the entire transient process) could reduce soot and NO_X emissions simultaneously. However, when TBV opening became larger, smoke emissions and BSFC were deteriorated gradually. Moreover, the sectional-stage injection timing (SSIT) strategies (advancing injection timing from 10 % load to a preset load and delaying injection timing from the preset load to 100 % load) could markedly reduce soot emissions by 75.8 % with TBV opening 20 %; the degradation of fuel consumption could be effectively suppressed. Finally, coupling the SSIT strategies with the TBV control strategies could significantly improve the transient performance.     

Iterative Learning Control Algorithm for Feedforward Controller of EGR and VGT Systems in a CRDI Diesel Engine

The modern diesel engines equip the exhaust gas recirculation (EGR) system to suppress the NOx emissions. In addition, the variable geometric turbocharger (VGT) system is installed to improve the drivability and fuel efficiency. These EGR and VGT systems have cross-coupled behavior because they interact with the intake and the exhaust manifolds. Furthermore, the turbocharger time delay, gas flow dynamics through EGR pipe cause the nonlinearity characteristics. These nonlinear multi-input-multi-output characteristics cause the degradation of control accuracy, especially during the transient condition. In order to improve the control accuracy, this study proposes an iterative learning control (ILC) algorithm for feedforward controller of EGR and VGT systems. The feedforward controller obtains the values about EGR and VGT actuators using the previous control results in predefined transient states. The ILC algorithm consists of a PD-type learning function and a low-pass filter. The control gains of learning function are determined to guarantee the convergence of learning results. In addition, the low-pass filter is designed for robustness against plant disturbance. The proposed control algorithm was validated by engine experiment which repeated predefined transient states. The error was reduced by 15 % according to the gain. As a result, the proposed algorithm is affordable for improving the transient control performance.