虹梯关特长隧道快速掘进施工技术研究

虹梯关特长隧道是目前国内第三长大公路隧道,施工过程中通过采用水压爆破、巷道式通风和优化施工组织计划等措施,有效提高了施工进度,创造了人工钻爆法施工单月独头掘进556 m的世界纪录。     

基于模型的电控发动机标定技术

阐述了基于模型标定的技术国内外发展概况.论述了包括试验设计技术、模型构建技术、参数优化技术和MAP生成技术在内的基于模型标定的关键技术.指出,基于模型标定技术在国内电控发动机开发过程中的应用还不够成熟和广泛,而瞬态工况下基于模型的电控发动机标定技术、基于模型的控制技术和基于耦合模型的整车标定技术,将成为电控发动机基于模型标定技术的发展趋势.     

为启动座椅坐垫倾角调节机构的汽车制动模式识别策略的研究

为准确地判定紧急制动状态,以便及时启动座椅坐垫倾角调节机构,对汽车制动模式判别策略进行研究.选取在汽车中低速行驶下的缓慢、点刹、紧急制动3种模式,采用正交试验设计方法,选用不同驾驶员以不同车速进行了制动实验.在对实验数据进行分析的基础上,采用了踏板力峰值法与踏板力变化率法两种判别算法.实验结果发现,两种算法都存在局限性.为此,又尝试了基于RBF神经网络模式识别算法.结果表明,这种算法能准确地判别制动模式.     

On the slack phenomena and snap force in tethers of submerged floating tunnels under wave conditions

Under severe sea wave conditions, the mooring tethers of submerged floating tunnel (SFT) might go slack. It may cause the structure failure during the service lifetime of SFT. The paper investigated SFT dynamics when going through tether slacking and the related snap force under wave conditions. Besides the nonlinearity of fluid drag and of structural geometry for a relative large structure displacement, the problem is characterized by the nonlinearity due to the discontinuity in axial stiffness of the tethers. To include these nonlinearities, the method of Lagrange energy is used to build the governing equations of SFT motion, and a bilinear oscillator is introduced to simulate the mooring tether operating in an alternating slack-taut state. The sensitivities of the occurrence of tether slacking to wave height and wave period are investigated. Results show that at a large wave height SFT tether will go slack and snap force occurs. SFT responses are categorized into three types of state according to the dynamic response characteristics of tether tension. Effects of two fundamental structure parameters, buoyancy-weight ratio (BWR) and inclined mooring angle (IMA), on the dynamic responses of SFT are analyzed. A slack-taut map of SFT tethers is built. It intuitively describes the occurrences of slack and snap force with different combinations of the two parameters. An analytical approach for slack prediction by deriving the slack criterion is provided to reveal the mechanism of the presented slack-taut map. By present research, the authors tried to make their effort to provide an alternative philosophy for SFT structural design on concerning preventing the occurrence of tether slacking and snap force.     

甚低频可控硅开关功率放大器的仿真研究

介绍了一种甚低频可控硅开关功率放大器,建立了其在临界换流状态时的等效电路模型和非线性数学模型,在OrCAD环境下仿真了等效电路模型,并采用拉氏变换法和微分方程数值分析法求解其非线性数学模型。三种方法都能计算出功放任意点的电流电压值,且结果相符。     

矩量法分析导体附近线天线的辐射特性

分析金属导体附近线天线的辐射特性具有重要的实用价值.运用矩量法处理多种形状金属导体附近的线天线辐射特性问题.先将线天线模拟为带状线,天线和金属导体表面均采用平面三角形面单元进行剖分,RWG基函数作电流展开函数.在此基础上,计算了在4种不同环境下的天线方向图,计算结果与软件(FEK0)仿真结果吻合良好.为分析工程中复杂的电大尺寸目标,提供了重要的参考依据.     

Research on network maintenance strategy selection based on analytic hierarchy process and technique for order preference by similarity to ideal solution algorithm

Network maintenance strategy selection is a multi-objective decision making topic. It mostly depends on the uncertainty and fuzziness of decision makers and conditions. In this paper, based on analytic hierarchy process (AHP) and technique for order preference by similarity to ideal solution (TOPSIS), TOPSIS partial order method is proposed to choose the optimal maintenance strategy. This method uses AHP to determine the weights of evaluation indexes. The optimal maintenance strategy choice is given as an example to demonstrate the effectiveness of the method.     

大跨高低墩连续刚构桥合龙顶推力计算分析

合龙顶推施工是建造连续刚构桥施工过程中的关键工序,以跨越一不对称狭长山谷的连续刚构桥(65m+120m+65m)为依托,分析了桥墩墩顶位移、控制截面内力和应力改善情况,提出了大跨高低墩连续刚构桥合龙顶推力的计算方法.计算方法考虑了恒荷载产生的有利影响,以及预应力效应、高温合龙、收缩徐变产生的不利影响.大跨高低墩连续刚构...     

潜艇水下碰撞特性数值研究

为分析碰撞中潜艇结构的损伤特性,选取2500t级双壳体潜艇作为研究对象,对潜艇结构进行等比例实体建模,并采取潜艇船艏与舷侧部位的撞击形式.利用大型非线性有限元软件Ls-Dyna,从能量、碰撞力和冲击环境3个角度研究碰撞的影响,得出以下结论：潜艇外壳及中间结构是吸能的主要结构,刚度较弱的潜艇艏部会产生大的塑性变形区,而刚度较强的舷侧结构的响应则以动能为主,且伴随着小范围的塑性变形区;撞击力在艏部临界速度附近,产生单峰值及双峰值现象,并确定临界速度值约为15～16kn;船长方向的冲击环境成对数函数分布,按中级损伤程度,对艇员的影响区域为距离船艏撞击区约0.11倍艇长范围.     

一种角位仪的研究设计

文章提出了一种用于模拟旋转变压器输出角度和位置信号的简便仪器的设计方法。介绍了以DSP为控制核心的设计原理以及具体的实现方式,重点介绍了硬件设计及应用对象,简要介绍了其调试、测试过程。通过实验说明了本仪器设计合理,性能指标能满足要求。