Development and prospects of initial alignment method for strap-down inertial navigation system北大核心CSCD

Initial alignment technology is directly related to the navigation accuracy and startup time of the strap-down inertial navigation system (SINS), and has always been regarded as a challenging focal point in the research field of inertial navigation. This paper makes a comprehensive survey of SINS initial alignment technology, briefly introduces the basic principles of initial alignment without latitude, coarse alignment with known latitude and precise alignment, and points out their advantages, disadvantages and applicable conditions. The research and effects of existing initial alignment error suppression techniques are then analyzed and discussed. Finally, according to the problems of existing initial alignment methods and the development requirements of the carrier, the future research direction of SINS initial alignment technology is predicted. © 2022 Journal of Clinical Hepatology. All rights reserved.     

《国际海运危险货物规则》40-20修正案主要修订内容介绍

在介绍《国际海运危险货物规则》(IMDG规则)40-20版修正案的修订脉络基础上,从危险货物分类、一览表及特殊规定等4个方面分析了修正案的主要修订内容,并根据修订情况提出相应的措施建议。     

气泡混合土抗冻融循环性能试验研究

为解决冻土地区普通路基由于保温性能差导致的路基病害问题，采用保温隔热性能好的气泡混合土作为路基填料，可起到保护冻土、减少病害的作用。为探讨气泡混合土的抗冻性能，选取了不同容重的气泡混合土试件进行冻融循环试验研究，研究气泡混合土质量及强度损失规律，从而获知气泡混合土的容重对其抗冻性能的影响；进而，向气泡混合土试件中掺入玻璃纤维，探讨其对气泡混合土抗冻性能的增强作用。结果表明：气泡混合土的抗冻性能随着容重的增大而提高，表现为容重越大，所能经受的冻融循环次数越多，抗压强度和质量损失率越低；容重为800kg/m3的气泡混合土试件经过15次冻融循环后抗压强度迅速降低，经过100次冻融循环后，试件的质量损失达到9.2%；而容重为1 200kg/m3的气泡混合土试件在经过50次冻融循环后，抗压强度才开始明显降低，经过100次冻融循环后，试件的质量损失只有4.5%。玻璃纤维能显著提高气泡混合土的抗冻性能，其抗压强度损失率和质量损失率明显较未掺纤维的普通气泡混合土要小，且抗压强度和质量损失的速率明显降低；不同容重的气泡混合土试件掺入纤维后，经过50次冻融循环后，试件的抗压强度损失减少50%以上，质量损失减少40%以上。     

深海变径声阵缆布放回收装置研究

本文提出了基于深海工作站运搭载的变径缆海底布放回收方式，介绍了变径缆海底布放回收装置的主要工作原理和结构组成，完成了布放回收装置主要部套件的设计计算以及和电液控制系统的设计及计算。     

《电加热道岔融雪系统设备》TB/T3539-2018解读

解读《电加热道岔融雪系统设备》与《客运专线铁路信号产品暂行技术条件汇编——电加热道岔融雪系统设备》标准的共性部分,并从编制背景、标准定位、技术要求、试验方法和检验规则等方面,分析两者之间的差异性.     

Bolster spring fault detection strategy for heavy haul wagons

An on-board health monitoring system is proposed for heavy haul wagons in this paper including a signal-based fault detection and isolation (FDI) method and an on-line fault diagnose strategy. Such a system, to be feasible on freight wagons, must be sufficiently cheap and robust, hence the design assumes the constraint of using only two accelerometers mounted on the front left and right rear part of each carbody in a heavy haul train. This paper focuses on the detection of bolster spring fault conditions. The problem is made more complex by the modes of failure which might be expected in bolster spring nests. Types of spring failure are firstly identified and discussed covering situations of broken (shortening springs) and softening (individual spring loss from a nest or cross-section loss through corrosion). The effects of these faults and their detectability were investigated using simulations on straight and curved track and using a fully detailed model of a typical 40?t axle-load heavy haul wagon. The simulation results were then examined and compared using cross-correlation analysis and an FDI system was proposed. The FDI system introduced five possible fault indicators. Initial results indicated that it was possible to detect changes in bolster stiffness of ±25%. An on-line fault diagnoses strategy is proposed for bolster spring faults which only requires data from wagon monitoring during travel around sharp curves to detect and the occurrence of confirm faults. The functionality envisaged needs only a ‘once per trip’ monitoring site, such as a sharper curve, and is aimed at condition monitoring rather than the provision of alarms or comprehensive monitoring of all events.     

Modeling the interactions between car and bicycle in heterogeneous traffic

In this paper, a new cellular automata model is proposed to simulate the car and bicycle heterogeneous traffic on urban road. To capture the complex interactions between these two types of vehicles, a novel occupancy rule is adopted in the proposed model to consider the variable lateral distances of mixed vehicular traffic. Based on massive simulations, microscopic fundamental diagrams under different bicycle densities are devised. With these, the bicycle's spilling behavior is then investigated and discussed. In order to reflect the interference of a bicycle on a car, the interference transformation from friction state to block state is modeled explicitly. Finally, different simulation results under different occupancy rules indicate that the constant and fixed occupancy rule adopted in the previous studies might lead to overestimation of car flux in the heterogeneous traffic flows with different bicycle densities. Copyright © 2013 John Wiley & Sons, Ltd.     

“工厂法”沉管隧道早期性能的足尺试验研究

由于沉管隧道管段体积大、结构形式复杂、施工工艺复杂,容易因温度、收缩以及约束等原因,造成管段结构在预制阶段出现危害性裂缝,进而影响结构的服役性能和耐久性能。文章依托在建港珠澳大桥沉管隧道工程实例,开展了足尺试验,对"工厂法"沉管管节关键部位的温度和应变发展实施了监测,分析对比了温度发展规律和应变发展规律。分析结果表明:在早期因混凝土水化热引起温度上升,整个管段结构膨胀受拉,温度到达峰值后逐渐下降,结构也收缩恢复;但由于混凝土自收缩等因素的存在,结构最终收缩受压。研究所提供的试验结果可作为深入进行数值分析的一个基础。