A numerical approach to trajectory planning for yoyo movement

Based on nonlinear trajectory generation (NTG) software package, a general approach (i.e. numerical solution) to trajectory planning for yoyo motion is presented. For the real-time control of such periodical dynamic system, a critical problem is how to implement fast solving the optimal trajectory, so as to meet the real-time demand. However, traditional numerical solution methods are very time-consuming. In this paper, the optimization problem is solved by mapping the problem to a lower-dimension space. And combined with multithread programming technology, the computation time for solving the optimal trajectory is greatly reduced. Simulation results show that the numerical solution is identical to the analytic one, which demonstrates the correctness of the proposed method. The computation time of one cycle of yoyo simulation is about 10 ms, which shows that the proposed numerical method can be applied to the real-time control of yoyo playing.     

A low-cost testbed of underwater mobile sensing network

Comprised by a swarm of acoustically linked and cooperative autonomous underwater vehicles (AUVs) with onboard sensors, an underwater mobile sensing network (UMSN) will be a complementary means to fixed observatory networks, e.g. seafloor observatory networks and moored buoy arrays. It has obvious advantages over a single large AUV in higher efficiency due to parallel observation, stronger robustness to vehicle failures and lower cost. Although an UMSN can be viewed as a counterpart of wireless mobile sensing networks for air and terrestrial applications, it is much more challenging due to poor performance of underwater acoustic communication, poor performance of underwater positioning and high degree of uncertainty in vehicle dynamics and underwater environment. In order to verify key technologies involved in an UMSN, e.g. cooperation of multi-AUVs based on acoustic communication, a low cost testbed has been developed for experimental study. The design of both hardware and software is introduced. Also the results of a functional test for verification of the effectiveness of the testbed are presented.     

对弹性理论法计算单桩桩顶沉降的修正

针对弹性理论法计算模型中,桩并非真正嵌入土体中而与实际桩土模型不符的问题,对不同桩径比的单桩桩顶沉降进行了计算。通过弹性理论法与有限元法计算结果的对比分析,得出了弹性理论法计算单桩桩顶沉降的修正系数。     

Determining the hydrodynamic forces on a planing hull in steady motion

A combination of methods was developed that can determine hydrodynamic forces on a planing hull in steady motion. Firstly, a potential-based boundary-element method was used to calculate the hydrodynamic pressure, induced resistance and lift. Then the frictional resistance component was determined by the viscous boundary layer theory. Finally, a particular empirical technique was applied, to determine the region of upwash geometry and determine spray resistance. Case studies involving four models of Series 62 planing craft were run. These showed that the suggested method is efficient and capable, with results that are in good agreement with experimental measurements over a wide range of volumetric Froude numbers.     

基于新架构的汽车远程诊断系统的应用

基于SOA(Service Oriented Architecture)新架构的汽车远程诊断系统,具有车云之间通讯的优势,使车辆具有灵活的功能选择性。本文旨在提出可以满足客户的多样化需求的、缩减整车厂车辆研发周期的汽车远程诊断系统,其具备车辆功能配置服务、体检服务以及快捷服务等功能,在提高用户满意度和体验感的同时,也可以简化整车厂同一车型子车型结构,降低相关工作量,提升整车厂工作效率。     

IIoT在提升转向机产品质量方面的应用

工业物联网(IIoT)的泛在感知特性可以提高生产线过程检测、实时参数采集、材料消耗监测的能力和水平,通过对数据的分析处理可以实现智能诊断和决策,对生产过程进行工艺优化,提高产品合格率。通过工业物联网(IIoT)数据采集分析模型对转向机生产过程中的质量影响因子进行识别,得出壳体拧紧扭矩合格率低为当前影响产品质量的最大因素,同时根据操作工位在线监控系统的数据,研究拧紧不合格过程中的多个输入因子,并对5个可疑关键因子进行了改善。改善之后的数据结果表明,通过改善拧紧工装定位方式、机床拧紧对中、拧紧头重量和止规进入角度,可以使得螺盖锁紧工序一次不合格率由7.20%降低至1.55%,达到了预期2%的目标。     

现代激光测试技术在燃气轮机燃烧室测试中的应用

系统地概述了近年来燃气轮机燃烧室测试技术的应用及进展,介绍了激光多谱勒技术,粒子图象速度技术、激光荧光法和剌曼光谱测温技术的原理和特点,以及目前有关湍流火焰火焰前峰厚度及温度梯度的定量测试分析的报道。     

城市道路工程建设项目的优先排序——以编制天津中心城区2000年～2010年干道路网建设计划为例

进入二十一世纪 ,天津将为完善规划干线路网继续做出坚持不懈的努力。为了使项目建设计划更加科学化 ,本文特对影响道路工程建设项目排序的诸因素进行了分析 ,做到了定性与定量相结合 ,在此基础上 ,提出了 2 0 0 0年～ 2 0 0 5年 ,2 0 0 6年～ 2 0 1 0年道路建设项目的实施计划的建议     

岩溶隧道富水区段衬砌渗漏水治理技术

根据某岩溶隧道富水区段地质状况和衬砌渗漏水的情况，分析了渗漏水的原因，提出了衬砌渗漏水治理的总体思路，介绍了如何有针对性地选择渗漏水治理材料，并对治理工艺进行了阐述。     

二冲程发动机夹气喷射系统方案分析

通过对IAPAC、SCIP、AFI及ASDI 4种系统进行分析,可以确认采用先进的电子控制技术和纯空气的扫气来实现缸内夹气喷射,可使二冲程汽油机在保持传统二冲程机突出优点的同时又解决了其存在的油耗高、排气污染严重的问题。