弹引系统传递函数系统辨识

在对弹引系统动态特性详细研究的基础上,通过分析弹丸过载和引信过载的差异,建立弹引系统传递函数的数学模型.搭建弹引系统锤击试验平台,根据系统可辨识性要求,采用有限元法对试验平台中力锤进行模态分析,确定力锤的选型.利用该试验平台,在弹丸、引信不同拧紧力矩条件下,测取单位脉冲激励时弹引系统的输出响应.基于系统辨识理论的输出误差模型,提出弹引系统传递函数算法,并编制相应的计算程序.最后以某弹引系统锤击试验的数据为例,计算出该弹引系统的频域传递函数,并在相同的激励环境下对理论计算的输出响应与实测试验结果进行比对,结果表明所提出的弹引系统传递函数系统辨识算法及输出误差模型符合实际情况,达到了研究目的.     

基于软件同步的机床主轴回转精度测试

机床主轴回转精度反映了主轴回转时轴心线在空间所产生的运动误差,该误差是机床加工误差的主要来源之一。传统测试方法的理论非常成熟,但是测试时的安装非常不方便。本文分析了软件同步技术的原理和适用场合之后,并将该原理运用到车床回转精度测试系统的数据前处理过程中,替代了传统的角度测试装置——编码器。该技术的运用降低了车床主轴测试安装要求,使测试系统更适用于现场测试;同时也降低了测试系统的成本,提高了其适应性。     

用深层搅拌法加固吹填土地基工程

港口在建设过程中经常遇到软土处理问题，特别是对吹填造陆部分必须进行处理，一般对软土地基处理的方法有：强夯法、堆载予压法、深层搅拌法。深层搅拌法对在吹填造陆上建筑物地基处理非常有效且经济。     

FDP FPGA芯片的设计实现

研究了新型的FDP FPGA电路结构及其设计实现.新颖的基于3输入查找表的可编程单元结构,与传统的基于4输入查找表相比,可以提高约11%的逻辑利用率;独特的层次化的分段可编程互联结构以及高效的开关盒设计,使得不同的互联资源可以快速直接相连,大大提高了可编程布线资源效率.FDP芯片包括1600个可编程逻辑单元、160个可用IO、内嵌16k双开块RAM,采用SMIC 0.18μm CMOS工艺全定制方法设计并流片,其裸芯片面积为6.104mm×6.620mm.最终芯片软硬件测试结果表明:芯片各种可编程资源可以高效地配合其软件正确实现用户电路功能.     

Simulation study of the dynamic characteristics of the electromagnetic flame-proof mechanism

Since the overloads of the electromagnetic flame-proof mechanism under different working conditions are complex and hard to be verified, a numerical simulation method of this mechanism working process is proposed with the combination of Adams and Simulink. First, a simulation model of electromagnetic flame-proof mechanism was established, which includes the safety pin, the spring, and the exciting coils and so on. Then, the model was imported to Adams taking constraints into consideration, which include the contacts, kinematic pairs and the spring. The co-simulation model was established through the union of Adams and Simulink. The model was tested via simulations, and the obtained results were analyzed finally. The results show that the method can simulate the dynamic process of the electromagnetic flame-proof mechanism during the service process and under the normal power supply condition, and therefore the motion displacements of the electromagnetic pin under different working conditions can be obtained through simulations. It can verify the mechanism''s designing rationality, thus laying the foundation for the physical prototype testing and reducing the repetition of the product''s design process.     

Numerical simulation of the delay arming process of initiating explosive brakes

The delay arming process of initiating explosive( IE) brakes for fuse is complex and hard to be verified.A numerical simulation model of IE brakes was established based on the arbitrary Lagrange-Euler method.The model included the structure,the air filed,etc. The simulation boundary conditions were defined,including the contacts,blasting parameters of the explosive and the fluid-solid coupling interface. The simulation results show that the shear pin of the chosen IE can be cut off. When the piston needs to move 0. 8 cm,the time set to the delay arming of the IE brakes model is about 40 μs. The maximum displacement of the piston is 1. 17 cm. The model provides basis for parameters design and further improvement of IE brakes.     

基于树状条件随机场模型的语义角色标注

针对线性条件随机场模型不能清楚表达语义角色内部结构关系的问题,提出一种基于树状条件随机场模型的语义角色标注方法。对句法依存树上的层次依赖关系和兄弟依赖关系进行标注,处理状态变量之间的长距离依赖,利用CRFs模型能添加任意特征的优点,在系统中添加新的组合特征和介词短语角色。在CoNNL 2008 Shared Task语料库上进行实验,结果证明该方法能有效提高系统的准确率和召回率。     

浅谈监理单位进行造价控制的必要性及控制要点

建设监理作为一种社会化、科学化、专业化程度较高的管理方式，在工程建设中所起的作用已逐渐被社会认可。《建设监理规范》中已明确：“监理单位必须与建设单位签订书面建设工程委托监理合同。合同中应包括监理单位对建设工程质量、造价、进度进行全面控制和管理的条款。”但就现状来看，业主委托监理单位的大多是施工阶段的质量控制，而投资控制却很少涉及。很多监理人员只是“质量检查员”。那么，我们应如何看待当前形势，又如何做好项目的造价控制？谨作简要分析。