深孔注浆技术在地铁暗挖隧道施工中的应用

城市地铁暗挖隧道施工中所面临的难题之一就是水的治理问题,水不仅危及掌子面开挖作业的安全,同样也威胁到地面建(构)筑物的安全。面对富水砂层及软弱破碎层,如何进行掌子面加固及止水是施工的关键。深圳地铁2号线东延线2222标安-侨区间隧道工程中采用TGRM深孔注浆技术成功地完成了富水砂层段的施工以及近距离多次穿越重要管线及建(构)筑物的施工,充分表明在不良地质地段采用深孔超前预注浆加固掌子面及固结止水技术是行之有效的。文章针对此工程实例,阐述了深孔注浆技术的机理和工艺特点,以及在城市暗挖地铁隧道施工中的应用效果。     

Strong key-insulated signature in the standard model

The only known construction of key-insulated signature (KIS) that can be proven secure in the standard model is based on the approach of using double signing. That is, the scheme requires two signatures: a signature with a master key and a signature with the signer’s secret key. This folklore construction method leads to an inefficient scheme. Therefore it is desirable to devise an efficient KIS scheme. We present the first scheme with such a construction. Our construction derives from some variations of the Waters’ signature scheme. It is computationally efficient and the signatures are short. The scheme is provably secure based on the difficulty of computational Diffie-Hellman (CDH) problem in the standard model.     

Research on the electro-hydraulic variable valve actuation system based on a three-way proportional reducing valve

As the internal combustion engine moves into the 21st century, fully flexible valve actuation systems are being proposed as an enabling technology for advanced internal combustion engine concepts. Electro-hydraulic valve actuator systems are being considered as a potential variable valve technology. Compared to the servo control system, the system using a proportional valve has the advantages of low price, high anti-pollution ability and high reliability. Our research focuses on exploring the dynamic characteristic of the electro-hydraulic variable valve system, which is based on three-way proportional reducing valve. In this paper, the structure and working principles of the system are described. The dynamic mathematical model of the system is derived. From the analysis of a linearized model and dynamic simulation, it is demonstrated that the system will be stable only if the proportional reducing valve has a positive opening. Some structural factors that affect the system’s dynamic characteristics, such as input signal, the stiffness of the return spring and the pre-tightening force of the return spring, are studied using AMESim. The experimental results coincide with the theoretical and simulated analyses. Further study shows that the dynamic response can be improved effectively by adopting closed-loop control of valve lift.     

基于模糊RBF神经网络的柴油机电液调速控制方法

介绍了电液调速执行器的动态特性,设计了电液调速控制回路,实现了模糊RBF神经网络对柴油机油门执行器位置的控制。将一种基于模糊RBF神经网络的PID控制器应用于柴油机调速控制中,详细说明了模糊RBF神经网络控制器的设计过程,它结合了传统PID以及神经网络和模糊控制的优点,可以在线调整得到一组最优的PID控制参数。仿真结果表明该系统比传统模糊控制的响应速度快、超调小,且适应性强,具有推广价值。     

典型港口夏秋季节大气颗粒物污染特征与来源解析

本文选取秦皇岛港区为监测点,分别于夏、秋两季的代表月进行PM_(10)样品的采集与化学组分分析。结果表明,夏、秋两季采样期间秦皇岛港大气PM_(10)质量浓度平均值分别为93.5±44.6μg/m~3、131.5±69.1μg/m~3。夏、秋两季二次无机离子浓度分别为27.9μg/m~3与30.5μg/m~3,分别占总PM_(10)的29.8%与23.2%;夏季SO42-最高,浓度为11.7μg/m~3,占比为12.5%,秋季NO3-明显高于夏季,浓度为12.4μg/m~3。夏、秋季碳质组分浓度分别为26.3μg/m~3与33.5μg/m~3,占比分别为28.1%与25.5%;两季EC浓度相差不大,分别为4.1μg/m~3与4.4μg/m~3;一次排放是有机气溶胶的主要贡献源,两季POA占比分别为75.0%与73.5%。一次组分来源解析结果显示,土壤尘与冶金、机动车、燃煤、海盐与船舶是秦皇岛港大气PM_(10)的主要贡献源,平均贡献率分别为44.0%、16.5%、15.9%、10.8%与8.9%,港区空气污染治理应注重对船舶排放的控制。     

Incorporating work zone configuration factors into speed‐flow and capacity models

This study aims to develop work zone speed‐flow and capacity models, which incorporate work zone configuration factors including the number of work zones, geometrical alignment, work zone speed limit, and work zone length. On the basis of the traffic data from six work zone sites with various work zone configurations, two nonlinear traffic speed and flow models including work zone configuration factors are developed for the uncongested and congested traffic conditions, respectively. A work zone capacity model is proposed on the basis of the two models. The three models can further be used to examine the effects of work zone configuration factors on the speed‐flow relationship and capacity at work zones. Results show that traffic speed, traffic flow, and work zone capacity increase with the posted speed limit. Traffic speed under uncongested conditions decreases with the geometric alignment, the number of work zones, work zone length, and heavy vehicle percentage. Under congested conditions, the increase of the number of work zones is found to exhibit a larger negative impact on the traffic flow than the increase of geometric alignment. The number of work zones is also found to have the largest negative impacts on work zone capacity, followed by the geometric alignment. Short work zone length exhibits a relatively minor contribution to increasing work zone capacity. Copyright © 2014 John Wiley & Sons, Ltd.     

LNG船齿轮箱基座预装工艺的优化

针对LNG船齿轮箱基座在船坞阶段安装产生的涂层破坏和对生产进度的影响,提出预总组的工艺阶段进行基座预装,并制定相应工艺,既满足了基座安装精度要求,又保证了涂装质量,确保质量的同时提高了产品建造效率。     

PSC检查中GMDSS通信出现的问题及应对措施

针对我国远洋船舶因港口国监督(PSC)检查造成船船舶滞留的问题,分析了PSC检查中全球海上遇险与安全系统(GMDSS)通信导致船舶滞留的3大主要原因:证书、设备、船员问题;然后重点阐述了GMDSS设备方面存在的问题;最后提出了应对PSC检查的准备工作和具体措施,即只要保证设备证书和相关资料齐全,加强GMDSS人员的培训...     

基于无源雷达模拟器的幅度算法研究

以无源雷达模拟器为基础,讨论了在不同工作模式下,目标信号幅度的计算方法,并对两种工作模式下信号幅度的取值进行了仿真。针对微波器件频率特性引起的差异,介绍了一种信号幅度调整的方法,对于“真实”的模拟目标信号,具有一定的实践和指导意义。     

不明原因不孕妇女月经周期中血清微量元素的研究

对19例不明原因不孕和14例已育健康妇女共33个月经周期中血清锌、铜、铁、锰、镍含量进行分析。结果表明：对照组排卵日血清锌、铜明显低于印泡中期和黄体中期，印泡中期铁、镍含量最高，在周期中呈递减趋势（P均＜0．05）；与对照组比较，不孕组除印泡中期镍减低外，各期血清钢及黄体中期锌、镍、铁均显著增高（P＜0．001，P＜0．05，P＜0．01），而各期血清锌／铜、铁／铜比率明显降低（P＜0．05）。研究提示：正常妇女月经周期中微量元素水平具有规律的周期变化，且相互存在恒定的比值，微量元素的代谢紊乱可能是不明原因不孕的重要因素之一。