Removal of p-xylene from an air stream in a hybrid biofilter

Biofiltration of an air stream containing p-xylene has been studied in a laboratory hybrid biofilter packed with a mixture of mature pig compost, forest soil and the packing material which was made of polyethylene (PE) and used in the moving bed biological reactor (MBBR) in wastewater treatment. Three flow rates, 9.17, 19.87 and 40.66 m(3)m(-2)h(-1), were investigated for p-xylene inlet concentration ranging from 0.1 to 3.3 g m(-3). A high elimination capacity of 80 g m(-3)h(-1) corresponding to removal efficiency of 96% was obtained at a flow rate of 9.17 m(3)m(-2)h(-1) (empty bed residence time of 132 s). At a flow rate of 40.66 m(3)m(-2)h(-1) (empty bed residence time of 30s), the maximum elimination capacity for p-xylene was 40 g m(-3)h(-1) and removal efficiencies were in the range of 47-100%. The production of carbon dioxide (P(CO(2))) is proportional to elimination capacity (EC) and the linear relation was formulated as P(CO(2))=1.65EC+15.58. Stable pH values ranging from 6.3 to 7.6 and low pressure drop values less than 0.2 cm H(2)O (19.6 Pa) of packing media in compost-based biofilter of hybrid biofilter were observed, which avoided acidification and compaction of packing media and sustained the activity of microorganism populations.     

基于SolidWorks的机器人离线示教方法

工业机器人主要采用人工示教、运动再现的工作方式。为减轻人工示教的工作量,开发了一套机器人离线路径生成系统。通过SolidWorks二次开发,获取操作对象上的运动路径。通过位姿变换,将运动路径上的点转化为机器人末端执行器的位姿。经机器人专用仿真软件仿真表明,该离线示教方法能正确指导机器人实现指定运动。     

Experimental study of power consumption,local characteristics distributions and homogenization energy in gas–liquid stirred tank reactors

In this paper, the power consumption, the vertical local void fraction and the local gas–liquid interfacial area are investigated in the aerated stirred tank reactors(STRs) equipped with a rigid-flexible impeller. Meanwhile, the regressive correlation based on power consumption and interfacial area is proposed. Then a novel homogenization energy(HE = RSDPtm) expression based on power consumption and local interfacial area is redefined and used to indicate the mixing efficiency. The optimal operating mode is selected based on the change of the HE value. This paper can provide research ideas for structural optimization of stirred reactors.     

Predicting shear strength of slender beams without reinforcement using hybrid gradient boosting trees and optimization algorithms

Shear failure of slender reinforced concrete beams without stirrups has surely been a complicated occurrence that has proven challenging to adequately understand. The primary purpose of this work is to develop machine learning models capable of reliably predicting the shear strength of non-shear-reinforced slender beams (SB). A database encompassing 1118 experimental findings from the relevant literature was compiled, containing eight distinct factors. Gradient Boosting (GB) technique was developed and evaluated in combination with three different optimization algorithms, namely Particle Swarm Optimization (PSO), Random Annealing Optimization (RA), and Simulated Annealing Optimization (SA). The findings suggested that GB-SA could deliver strong prediction results and effectively generalizes the connection between the input and output variables. Shap values and two-dimensional PDP analysis were then carried out. Engineers may use the findings in this work to define beam's geometrical components and material used to achieve the desired shear strength of SB without reinforcement.     

Efficient promotion of methane hydrate formation and elimination of foam generation using fluorinated surfactants

Methane hydrate preparation is an effective method to store and transport methane. In promoters to facilitate methane hydrate formation, homogeneous surfactant solutions, sodium dodecyl sulfate (SDS) in particular, are more favorable than heterogeneous particles, thanks to their faster reaction rate, more storage capacity, and higher stability. Foaming, however, could not be avoided during hydrate dissociation with the presence of SDS. This paper investigated the ability of five fluorinated surfactants: potassium perfluorobutane sulfonate (PBS), potassium perfluorohexyl sulfonate (PHS), potassium perfluorooctane sulfonate (POS), ammonium perfluorooctane sulfonate (AOS), and tetraethylammonium perfluorooctyl sulfonate (TOS) to promote methane hydrate formation. It was found that both PBS and PHS achieve a storage capacity of 150 (V/V, the volume of methane that can be stored by one volume of water) within 30 min, more than that of SDS. Cationic ions and the carbon chain length were then discussed on their effects during the formation. It was concluded that PBS, PHS, and POS produced no foam during hydrate dissociation, making them promising promoters in large-scale application.     

Memristive Artificial Synapses for Neuromorphic Computing

Neuromorphic computing simulates the operation of biological brain function for information processing and can potentially solve the bottleneck of the von Neumann architecture.This computing is realized based on memristive hardware neural networks in which synaptic devices that mimic biological synapses of the brain are the primary units.Mimicking synaptic functions with these devices is critical in neuromorphic systems.In the last decade,electrical and optical signals have been incorporated into the synaptic devices and promoted the simulation of various synaptic functions.In this review,these devices are discussed by categorizing them into electrically stimulated,optically stimulated,and photoelectric synergetic synaptic devices based on stimulation of electrical and optical signals.The working mechanisms of the devices are analyzed in detail.This is followed by a discussion of the progress in mimicking synaptic functions.In addition,existing application scenarios of various synaptic devices are outlined.Furthermore,the performances and future development of the synaptic devices that could be significant for building efficient neuromorphic systems are prospected.     

ZGMn18Cr2Mo超高锰钢加工硬化机理研究

研究了ZGMn18Cr2Mo超高锰钢在压缩变形时的加工硬化机理。结果表明：在小压缩变形情况下，有高密度的位错、少量层错和大量的形变孪晶形成，并有一定数量的交叉孪晶和纳米尺寸的超微细碳化物TEM和XRD分析未发现形变诱发马氏体存在，说明超高锰钢加工硬化是位错强化、孪晶强化、层错强化及弥散析出的超微细碳化物颗粒强化综合作用的结果。     

双端RAM在SRM调速系统中的应用

根据开关磁阻电机（Switched Reluctance Motor--SRM）调速系统的特点，利用双端RAM（IDT7132）实现ATMEGA128芯片和89S51的双CPU的数据采集、通讯、PID运算和PWM波的产生，解决了SRM调速系统的实时控制问题，提高了开关磁阻电机的动、静态特性。     

RESEARCH ON THE PERFORMANCE OF NEW TYPE OF PROPORTIONAL PESSURE AND FLOW CONTROL VALVE

A new closed loop flow controlling principle through correcting the valve's opening area while load pressure is changing is carried out. Further more a principle using only one proportional valve to compound control pressure and flow is suggested. By using very simple proportional throttle valve in structure, the functions that five kinds of proportional valves or any two of them combined possess can be complimented. After analyzing, comparing, and testing the dynamic and static characteristics of valve with different controlling principles and main valve structure styles, the optimized structure styles and control methods are achieved.     

活性炭对铅酸电池负极活性物质结构与性能的影响

本工作研究了在铅酸电池负极活性物质中添加高比表面积活性炭对其微观结构与性能的影响。模拟电池实验结果发现,添加0. 5%的SPC04型活性炭可以使负极1C、5C、10C的放电容量分别提高18. 36%、42. 68%、44. 01%,2C 60 s的放电循环寿命提高1倍。6-FM-9F型实际电池测试结果表明,不仅在部分荷电态高倍率(HRPSo C)充放电条件下电池的循环寿命得到了显著提高,而且在完全充放电下电池的循环寿命也得到了显著提高。负极活性物质的微观结构测试结果表明,活性炭材料的加入可以明显改变其颗粒形貌和孔隙结构,活性炭可以使负极活性物质颗粒及孔隙分布较为均匀,粒径大小适中,增加了活性物质颗粒间有效孔径范围(0. 4～3μm)的占比。