浅谈花岗岩碎石沥青混凝土的推广应用

以石灰岩碎石为主的沥青混合料成为路面建设的主要材料,在多年的应用实践中,人们对这种碎石拌和料有了较为丰富的认识,因而得到了最普遍的应用,石灰岩碎石以其存量大、分布广、易于破碎加工并与沥青有着较高的粘结性等优点成为沥青拌和料中的主要矿物集料。     

中型城市市域(郊)轨道交通建设的思考

根据某中型城市市域(郊)轨道交通建设经验,通过数据收集、理论计算、列举实例等方法,对中型城市市域(郊)轨道交通建设中关于客流预测、制式选择、设计速度、敷设方式、车辆编组、防灾救灾设计等重大问题进行研究,认为中型城市的市域(郊)轨道交通建设应根据各城市自身特点因地制宜,不能简单借鉴大型城市的建设经验,希望能给市域(郊)轨...     

广州地铁4号线高架桥防排水系统设计

根据广州地铁4号线高架桥的特点,分析桥梁排水设计的关键点,确定高架桥排水设计的原则,阐述地铁4号线高架桥防水及排水采用暗埋敷设的设计方案;通过对排水管材的分析比较,确定高架桥排水管材选型;分析高架桥排水管采用暗埋敷设的环境,对北方有冻胀灾害地区高架桥排水管的布置提出建议方案。     

纯电动汽车制动能量回收系统关键技术现状分析

文章以制动能量回收控制策略为核心,展开制动能量回收系统关键技术现状分析。首先重点阐述制动能量回收前后轴制动力与电-液制动力分配原则与技术要点。其后提出电机性能、储能装置性能状态、再生制动系统结构、行驶工况四类关键因素对制动能量回收的影响,并对其关键技术的研究现状进行综合分析。最后提出制动能量回收系统未来的研究方向。     

Application of dual reciprocity boundary element method to predict acoustic attenuation characteristics of marine engine exhaust silencers

In marine engine exhaust silencing systems, the presence of exhaust gas flow influences the sound propagation inside the systems and the acoustic attenuation performance of silencers. In order to investigate the effects of three-dimensional gas flow and acoustic damping on the acoustic attenuation characteristics of marine engine exhaust silencers, a dual reciprocity boundary element method （DRBEM） was developed. The acoustic governing equation in three-dimensional potential flow was derived first, and then the DRBEM numerical procedure is given. Compared to the conventional boundary element method （CBEM）, the DRBEM considers the second order terms of flow Mach number in the acoustic governing equation, so it is suitable for the cases with higher Mach number subsonic flow. For complex exhaust silencers, it is difficult to apply the single-domain boundary element method, so a substructure approach based on the dual reciprocity boundary element method is presented. The experiments for measuring transmission loss of silencers are conducted, and the experimental setup and measurements are explained. The transmission loss of a single expansion chamber silencer with extended inlet and outlet were predicted by DRBEM and compared with the measurements. The good agreements between predictions and measurements are observed, which demonstrated that the derived acoustic governing equation and the DRBEM numerical procedure in the present study are correct.     

Review of containership stowage plans for full routes

Containership stowage plans are a pivotal teaches in the system of container transportation. With the increasing containers shipping, planning containership stowage has become more and more complicated. So intelligent stowage planning for containerships is of great significance. An effective stowage plan may improve efficiency of transportation system. First, the progress of containership stowage plan at home and abroad is reviewed, including the latest developments, such as the application of various optimization methods and computer techniques to the problem. Then, the complexities of the problem are discussed and areas where investigations are still needed are pointed out. This will provide a reference for further research on the subject.     

中国乘用车轻量化水平发展趋势研究

采集了2010～2020年中国市场销售的约1.5万个燃油乘用车和电动乘用车样本,采用整车轻量化系数作为乘用车轻量化水平评价指标,对其不同类型、级别和车系的整车轻量化水平变化趋势和现状进行了研究。结果表明,近10年各类燃油乘用车的整车轻量化系数持续下降,降幅约30%,行业整体轻量化水平不断提高,但提高的幅度趋缓。自主品牌燃油乘用车的整车轻量化水平与其他车系仍有一定的差距。电动乘用车的整车轻量化系数呈下降趋势,轻量化水平不断提高,但其与燃油乘用车的轻量化特征存在较大差异。     

雾封层技术的研究

雾封层是一种有效的预防性养护措施,应用得当可延迟路面损坏,维持路面使用功能,延长道路使用寿命.然而若应用不当,将会导致路面抗滑能力下降,造成路面光滑,严重的情况下将会给行车安全带来不利影响.截至目前,国内对雾封层的应用技术尚无统一的标准和规定.主要对雾封层的适用条件、材料设计和施工技术等方面进行了归纳与总结,以利于促进...     

超声导波技术在燃气输配系统中的应用及缺陷评价

文中简述了超声导波检测原理及波谱分析方法,分析了该技术在城镇燃气输配系统中的应用结果,结果表明超声导波技术可有效检测出场站管道的缺陷;通过利用分级评价方法对检测出的腐蚀缺陷进行安全性评价,可进一步保证检测结果的科学性。     

大型无动力浮式储油船长江上海段拖航的可行性论证与实操

大型无动力浮式储油船长江上海段拖航属于超常规作业,特别是拖航编队须途经九段、圆圆沙、吴淞口等船舶密度高和交通流复杂的警戒区,具有一定的风险。笔者以"探险家"轮拖航编队为例,对大型无动力浮式储油船长江上海段拖航的可行性进行论证,并通过实际引航操纵验证其可靠性,为今后此类拖航提供理论保障和技术支持。