某含砷硫金精矿酸性氧化预处理机理及其反应动力学

针对国内某金精矿中金嵌布粒度细且大部分被黄铁矿、毒砂包裹,难以浸出的现状,采用HCl?H2O2体系对其进行酸性氧化预处理,分析了氧化预处理的机理和动力学. 结果表明,在盐酸浓度0.7 mol/L、矿浆浓度40 g/L、金精矿粒度小于48 μm占90%以上、搅拌速度400 r/min、温度60℃和H2O2浓度0.5 mol/L的条件下,金精矿中Fe和As的溶解率分别达45.9%和99.6%,利于包裹金释放和浸出. 酸性条件下,金精矿中的黄铁矿和毒砂可被H2O2氧化分解,符合产物层扩散为速率控制的固相反应收缩核模型.     

Tuning of the active phase structure and hydrofining performance of alumina-supported tri-metallic WMoNi catalysts via phosphorus incorporation

The effects of phosphorus on the structure and hydrofining performance of tri-metallic WMoNi/Al₂O₃ catalysts prepared with W/Mo-based hybrid precursor nanocrystals were investigated. The incorporation of phosphorus weakened the metal-support interactions (MSIs) and facilitated the formation of more synergetic NiWMoS phases with higher stacks. Catalytic tests using a fluid catalytic cracking diesel fuel showed that the changes in the MSIs and the morphology of the active phases had a more positive effect on the hydrodenitrogenation activity than on the hydrodesulfurization activity. In contrast, when phosphorus was incorporated into a tri-metallic WMoNiP/ Al₂O₃ catalyst prepared by a conventional incipient impregnation method, the MSIs decreased causing aggregation of the metal species which resulted in poorer hydrofining performance of the catalyst. These results show that incorporating phosphorus into a WMoNi/Al₂O₃ catalyst can finely tune the structure of the active phase to enhance the hydrogenation and hydrodenitrogenation activity of the resulting tri-metallic catalyst.

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踝关节章动式康复运动轨迹规划

作为一种常见的骨骼损伤方式,踝关节损伤的康复过程十分漫长。现有研究中规划的踝关节康复轨迹模式较单一、且容易造成踝关节的二次损伤。为避免踝关节的二次损伤,需要对其康复运动轨迹进行精心规划。有鉴于此,提出一种混联式踝关节康复装置,并提出一种基于章动原理的康复运动轨迹规划方法。结合踝关节康复运动的安全性要求,借助生物力学软件AnyBody分析了不同位姿下相关肌肉的活动度,进而确定了章动式踝关节康复运动轨迹的章动角。在此基础上,通过运动学推导,给出了混联式踝关节康复装置中各推杆的位移。最后,以所提混联式踝关节康复装置为对象搭建系统的运动控制平台,并通过激光跟踪仪对动平台上的运动参考点进行跟踪。理论和实测数据对比表明,所提章动式踝关节康复运动轨迹能实现跖屈/背屈、内翻/外翻的复合运动,并满足康复安全性要求。所设计的混联式踝关节康复装置及章动式康复运动轨迹可为踝关节患者的康复训练提供有效的解决方案。     

基于镁铝水滑石的Mo/Al2O3-MgO催化剂制备及其加氢脱硫性能

生产低硫或无硫柴油是当今世界范围内清洁燃料发展的趋势,加氢脱硫（HDS）是大规模生产清洁柴油最为有效的技术之一,而研制高活性的HDS催化剂成为该技术的关键。以镁铝水滑石与氧化铝的复合氧化物为载体,通过等体积浸渍法制备了一系列Mo/Al₂O₃-MgO催化剂,以二苯并噻吩（DBT）的正庚烷溶液为原料,在固定床反应器上评价所得催化剂的HDS活性,考察了不同镁铝比的水滑石、焙烧温度和添加量对催化剂物化性质和催化性能的影响。研究结果表明,镁铝比、焙烧温度和添加量均影响催化剂的酸性、金属还原性、硫化性能和MoS₂片晶的堆垛度等,当镁铝摩尔比为3、焙烧温度为800℃、成型时水滑石加入量为10%（质量分数）时,所制备催化剂的HDS活性最高,其脱硫率可达96.2%。这是由于该催化剂的酸性较适宜,活性组分与载体间的相互作用力适中,活性组分更易硫化,有助于提高MoS₂片晶的堆垛度进而改善催化剂的HDS性能。     

The effect of vent burst pressure on a vented hydrogen–air deflagration in a 1 m3 vessel

A series of experiments are conducted to investigate the effect of vent burst pressure on stoichiometric hydrogen–air premixed flame propagation and pressure history in a 1 m³ rectangular vessel in this paper. Pressure buildup and flame evolution are recorded using piezoelectric pressure transducers and a high-speed camera, respectively. The results show typical pressure peaks of three different mechanisms for all vent burst pressures in the experiments. The first pressure peak, generated by the rupture of the vent cover, increases with the vent failure pressure, with the subsequent outflow inertia of combustion products giving rise to a negative pressure. The second pressure peak results from the constant bulk motion of the flame bubble (the Helmholtz oscillation), and the third is produced by the interaction between the combustion waves and the acoustic waves. The time interval between the first pressure peak and the second pressure transient remained nearly constant. The Helmholtz oscillation always appears as the vent ruptures and its magnitude increases with the vent burst pressure. Furthermore, the lower the vent failure pressure, the longer the Helmholtz oscillation is sustained. The peak of the acoustically enhanced pressure always occurs within several milliseconds of the flame front touching the vessel. From a theoretical perspective, Rasbash's equation models the relationship between the maximum reduced explosion overpressure and the vent burst pressure precisely. Also, it is observed that the maximum lengths of the external flames were found to be nearly identical in all tests, but the average propagation rate of the flame front increases with the vent burst pressure. It is interesting that a phenomenon of intense oscillation of internal flame bubble was observed with the increase of vent burst pressure.     

柔性基、柔性关节空间机械臂的运动混合控制

为解决具有不确定性柔性基、柔性关节空间机械臂的控制问题,提出一种自适应鲁棒终端滑模控制与自适应最优控制相结合的混合控制方案。首先,利用奇异摄动法将系统降阶为慢变子系统及快变子系统;其次,针对慢变系统设计一种由等效控制、鲁棒控制及自适应调节算法组成的轨迹跟踪自适应鲁棒终端滑模控制方案;之后,针对快变系统设计一类基于自适应状态观测的振动最优控制策略。仿真结果表明所提方案在系统刚性、柔性运动控制上的有效性。     

高温环境下编织-嵌槽型金属橡胶的疲劳特性分析

采用拉-压式组合试验工装,以位移控制的加载方式对编织-嵌槽型金属橡胶进行了疲劳试验,研究了常温（25 ℃）及高温（300 ℃）环境下编织-嵌槽型金属橡胶在不同加载振幅下的疲劳特性,并通过平均刚度、等效黏性阻尼系数及其损伤因子对构件的损伤演化过程进行了表征。结果表明：编织-嵌槽型金属橡胶构件的疲劳损伤形式表现为磨损、断丝以及塑性变形;构件在各种试验条件下的疲劳过程均可分为刚度强化期和刚度衰减期,而构件力学性能的衰减主要发生在刚度衰减期;温度的升高或振幅的增大均会显著增大构件的积累损伤,进而缩短其使用寿命。     

振荡管内入射激波衰减及其对冷效应的影响

在膨胀比ε 2～6、振荡管长径比L/d 87～737、射流激励频率f 10～240 Hz范围内,探讨了振荡管内入射激波衰减规律及其对压力波制冷机内流动及性能的影响。结果表明：入射激波相对强度Δp_x/Δp₀随着管长相对位置x/L增大而不断减小,入射激波衰减与管内气体黏性力和摩擦力作用、激波对管内气体增压增温作用以及与反射激波发生透射和反射作用有关;振荡管越短,管内入射激波相对强度降低越少,封闭端所产生的反射激波也越强,制冷机的最大制冷效率η_max会逐渐降低;增大管长会降低压力波制冷机的制冷效率波动幅度,有利于改善压力波制冷机变工况性能。基于量纲分析和实验数据得到了入射激波相对强度衰减公式,计算结果与实验数据吻合较好,最大误差为5.70%。     

A hybrid multi-objective PSO algorithm with local search strategy for VLSI partitioning

Very large scale integration (VLSI) circuit partitioning is an important problem in design automation of VLSI chips and multichip systems; it is an NP-hard combinational optimization problem. In this paper, an effective hybrid multi-objective partitioning algorithm, based on discrete particle swarm optimzation (DPSO) with local search strategy, called MDPSO-LS, is presented to solve the VLSI twoway partitioning with simultaneous cutsize and circuit delay minimization. Inspired by the physics of genetic algorithm, uniform crossover and random two-point exchange operators are designed to avoid the case of generating infeasible solutions. Furthermore, the phenotype sharing function of the objective space is applied to circuit partitioning to obtain a better approximation of a true Pareto front, and the theorem of Markov chains is used to prove global convergence. To improve the ability of local exploration, Fiduccia-Matteyses (FM) strategy is also applied to further improve the cutsize of each particle, and a local search strategy for improving circuit delay objective is also designed. Experiments on ISCAS89 benchmark circuits show that the proposed algorithm is efficient.     

Strain Hardening Associated with Dislocation,Deformation Twinning,and Dynamic Strain Aging in Fe–20Mn–1.3C–(3Cu) TWIP Steels

The effects of Cu on stacking fault energy,dislocation slip,mechanical twinning,and strain hardening in Fe–20Mn–1.3C twinning-induced plasticity(TWIP) steels were systematically investigated.The stacking fault energy was raised with an average slope of 2 mJ/m2 per 1 wt% Cu.The Fe–20Mn–1.3C–3Cu steel exhibited superior tensile properties,with the ultimate tensile strength reached at 2.27 GPa and elongation up to 96.9% owing to the high strain hardening that occurred.To examine the mechanism of this high strain hardening,dislocation density determination by XRD was calculated.The dislocation density increased with the increasing strain,and the addition of Cu resulted in a decrease in the dislocation density.A comparison of the strain-hardening behavior of Fe–20Mn–1.3C and Fe–20Mn–1.3C–3Cu TWIP steels was made in terms of modified Crussard–Jaoul(C–J) analysis and microstructural observations.Especially at low strains,the contributions of all the relevant deformation mechanisms—slip,twinning,and dynamic strain aging—were quantitatively evaluated.The analysis revealed that the dislocation storage was the leading factor to the increase of the strain hardening,while dynamic strain aging was a minor contributor to strain hardening.Twinning,which interacted with the matrix,acted as an effective barrier to dislocation motion.