运载火箭海上动平台起竖系统动力学建模与仿真

针对运载火箭海上发射平台箭体起竖问题,综合运用船舶耐波性和多体动力学理论,建立海上发射平台运动模型。将解析法求解得到的起竖载荷变化与0级海况下动力学仿真结果进行对比,验证了起竖力学模型的正确性。为了模拟复杂海况环境下的起竖问题,采用船舶耐波性理论分析得出的平台运动函数条件,开展发射平台垂荡、纵摇、横摇耦合运动的动力学仿真,获得不同海况和不同起竖方向下起竖装置所受载荷的变化规律。研究结果可以为起竖系统的抗风浪设计以及液压和控制系统的设计提供一定的参考。     

基于柔性打捞的波浪补偿系统设计与试验

为提高高海况下救助打捞成功率与起吊过程安全性,介绍一种基于高海况柔性网具救助打捞系统的方法,提出一种以变幅油缸为执行机构的主被动复合波浪补偿方案,采用模糊自适应PID算法控制器,控制变幅油缸伸缩位移,抑制船舶横摇对伸缩吊臂的影响。根据相似准则对打捞系统进行模型设计并建立波浪补偿系统缩比模型试验,通过液压摇摆台模拟船舶横摇角度,测试变幅油缸的响应时间、运动的平稳性及缩比模型的补偿精度,预测原型样机的波浪补偿效果。实验结果表明:模型试验系统运行稳定可靠,补偿效果良好,打捞吊机跟随模拟平台做-15°～+15°的正弦摇摆,吊臂的波浪补偿运动误差维持在±1°内。该方法原理和试验数据可为原型样机的设计提供参考。     

电液伺服稳定平台建模与实验

由于风浪的影响,海上作业的船舶会产生不规律的横摇、纵摇和升沉运动,这严重影响船载设备的安全。因此,在船舶上建立一个稳定平台显得尤为重要[1]。介绍了一种六自由度稳定平台的工作原理和实际用途,通过逆解算法得到每个液压缸的运动规律,最后通过实验平台对稳定平台及其反解算法进行验证。实验表明,稳定平台对船舶的横摇、纵摇和升沉的稳定效果明显,具有广泛的工程应用前景。     

主动补偿平台单通道控制系统研究

船舶在海上作业时,需要通过稳定平台对船舶的摇摆进行补偿。稳定平台工作过程中,需要采用控制算法对各个通道进行控制。由于液压缸和电液伺服阀等机械元件惯性的影响,采用常规PID算法时,系统响应具有滞后性,降低了稳定平台的补偿精度。为此,提出一种前馈PID控制算法,该算法既具有常规PID算法简单易操作的优点,又能解决系统响应的滞后性问题。以稳定平台单通道为研究对象,采用仿真与实验相结合的方式,证明前馈PID控制算法的有效性。     

基于AMESim的浮式钻井平台钻柱升沉补偿系统仿真研究

针对海浪升沉运动对钻柱和钻压的影响,设计基于电液比例阀控制非对称油缸的海洋浮式钻井平台钻柱升沉补偿系统。通过对系统中电液比例阀和液压缸进行分析,搭建了基于AMESim软件的主动补偿和半主动补偿系统仿真模型,运用PID控制算法进行仿真研究。仿真结果表明,设计的补偿系统具有较好的补偿效果。该模型可为升沉补偿系统研究提供参考。     

船舶起重机减摇装置液压回路的设计与试验

针对船舶起重机海上作业时存在的吊重摇摆问题,提出了一种新型机械式船舶起重机减摇装置,利用减摇索在减摇环处形成稳定的力三角形,并有效地减小吊重的摆幅,进而达到抑制吊重摇摆的目的。对减摇装置的原理进行叙述,根据起重机及减摇装置的动作要求设计了液压系统,利用AMESim软件对船舶横摇4°下减摇马达的响应进行仿真分析,结果表明:液压马达的响应良好,验证了液压系统的合理性。搭建试验平台进行试验分析,得到减摇马达响应适时,验证了液压系统的可行性。     

神经网络PID控制的液压驱动主动升沉补偿预测控制研究

为了提高船舶在海面上作业时补偿精度,采用BP神经网络PID控制方法,并对船舶升沉运动输出误差进行仿真。建立船舶主动升沉补偿系统简图,分析船舶升沉运动工作原理,给出液压缸驱动传递函数。引用BP神经网络算法,采用梯度下降法对BP神经网络加权值进行修正,通过学习速率来补偿控制系统输出误差,从而实现PID控制器参数在线调节。在受到不同负载影响状况下,采用MATLAB软件对船舶升沉运动补偿精度进行仿真,并且与PID控制补偿精度进行对比。结果表明:采用PID控制器,船舶升沉运动输出误差较大,控制系统反应速度较慢;而采用BP神经网络PID控制器,船舶升沉运动输出误差较小,控制系统反应速度较快,同时,随着负载质量的增加,输出误差就会增大。采用BP神经网络PID控制系统,响应速度快,补偿精度高,提高了船舶在海面上作业定位精度。     

最优控制理论在电液力矩伺服系统中的应用研究

船舶减摇水舱试验台架是研究和设计减摇水舱的重要试验设备，能否准确的模拟船舶在海浪中的运动是设计试验台架的关键，本文设计了用于驱动船舶减摇水舱试验台架的电液力矩伺服系统，针对这一系统设计了最优控制器，仿真结果表明系统具有很好的跟踪性能，系统符合设计要求。     

TSC型动态无功补偿半物理仿真系统设计

针对在研究冲击性负荷的无功补偿策略时面临的实验条件苛刻、成本高、危险性大等问题,提出了一种基于QuaRC平台和DSP控制器的TSC型动态无功补偿半物理仿真系统。根据典型冲击性负荷——点焊机的实际工况,在仿真环境中建立了实验对象,选取了一种无功补偿策略并在DSP控制器中实现。仿真结果符合实际情况,验证了本系统设计方案的合理性。     

基于摆动油缸的电液力矩伺服控制系统设计

船舶减摇水舱试验台架是研究和设计减摇水舱的重要试验设备，能否准确的模拟船舶在海浪中的运动是设计试验台架的关键，本文设计了用于驱动船舶减摇水舱试验台架的电液力矩伺服控制系统，在伺服系统中用摆动油缸代替液压马达，建立了摆动油缸的数学模型，仿真结果表明系统符合设计要求。     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

Effect of Short-Time Aging on the Pitting Corrosion Behavior of a Novel Lean Duplex Stainless Steel 2002

The effect of short-time aging in the temperature range between 400 and 1000 °C on the pitting corrosion behavior and mechanical property of a novel lean duplex stainless steel(LDSS) 2002 was investigated through the potentiostatic critical pitting temperature(CPT) tests and the Charpy impact tests. Both the pitting corrosion resistance and the toughness of aged specimens degraded due to the precipitation of detrimental secondary phases and the most significant reduction of CPT and impact energy emerged at 650 °C concurrently. The CPT of LDSS 2002 specimen aged at 650 °C decreased by 28 °C, and the impact energy dropped from 69 to 29 J/cm~2 compared with the solution-annealed sample. Transmission electron microscopy characterization showed that the main precipitates in LDSS 2002 were Cr_2N and M_(23)C_6 along the ferrite–austenite grain boundaries.     

INTRODUCTION TO PATENTS

The invention provides a method of making a mold which can reduce SOx generation rate while preventing decrease in hardening rate in the case of using sulfuric acid for a hardener composition. The method has a mixture step in which fire-resistant particles, a hardener composition and a binder composition are mixed to obtain a composition for a mold. The hardener composition contains sulfuric acid. In the mixture step, sodium carbonate is added. A molar ratio of the sulfuric acid to the sodium carbonate is 0.5 or more and 4.0 or less.     

China Foundry Week 2014

China Foundry Week, hosted by the Foundry Institution of Chinese Mechanical Engineering Society （FICMES） each year, is a large academic event in China. It is one of the ten high-impact activities sponsored by the Chinese Mechanical Engineering Society.     

17th Conference of Hydrodynamic and Electromechanical Control Engineering Call for papers

正1.Contents In order to promote the academic exchanges and technical communication of the research in the field of fluid power transmission and control,fluid control engineering specialized committee of the Chinese Society of Theoretical and Applied Mechanics will hold the 17th Conference of Hydrodynamic and Electromechanical Control Engineering on July 27-29,2014 in Tibet,Lhasa city.     

Information for Contributors

正The Transactions of Nonferrous Metals Society of China,founded in 1991 and sponsored by The Nonferrous Metals Society of China,is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology,including mineral processing,extraction metallurgy,metallic materials and heat treatments,metal working,physical metallurgy,powder metallurgy,with the emphasis     

Preface

<正>We are pleased to present this Special Issue of Transactions of Nonferrous Metals Society of China containing selected papers from the First Asian Conference on Aluminum Alloys(ACAA-2013),held in Beijing,China,13–17 October 2013.This conference has been initiated,with approval of     

Information for Contributors

The Transactions of Nonferrous Metals Society of China, founded in 1991 and sponsored by The Nonferrous Metals Society of China, is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology, including mineral processing, extraction metallurgy, metallic materials and heat treatments, metal working, physical metallurgy, powder metallurgy, with the emphasis on fundamental science. It is the unique preeminent publication in English for scientists, engineers, under/post-graduates on the field of nonferrous metals industry. This journal is covered by many famous abstract/index systems and databases such as SCI Expanded, Ei Compendex Plus, 1NSPEC, CA, METADEX, AJ and JICST.     

Rheology Feature of Simple Metal Melt

The rheology feature of Sb, Bi melt and alloys was studied using coaxial cylinder high-temperature viscometer. The results showed that the curve of torsion-rotational speed for Sb melt presents a linear relation in all measured temperature ranges, whereas for the Bi melt, the curve presents obvious non-Newtonian feature within the low temperature range and at relative high shear stress. The rheology feature of Sb80Bi20 and Sb20Bi80 alloy melts was well correlated with that of Sb and Bi, respectively. It is considered that the rheology behavior of Sb melt plays a crucial role in Sb80Bi20 alloy and that of Bi melt plays a crucial role in Sb20Bi80 alloy.