Mechanical property of cylindrical sandwich shell with gradient core of entangled wire mesh

To explore the wide-frequency damping and vibration-attenuation performances in the application of aerospace components,the cylindrical sandwich shell structure with a gradient core of entangled wire mesh was proposed in this paper.Firstly,the gradient cores of entangled wire mesh in the axial and radial directions were prepared by using an in-house Numerical Control weaving machine,and the metallurgical connection between skin sheets and the gradient core was performed using vacuum brazing.Secondly,to investigate the mechanical properties of cylindrical sandwich shells with axial or radial gradient cores,quasi-static and dynamic mechanical experiments were carried out.The primary evaluations of mechanical properties include secant stiffness,natural frequency,Specific Energy Absorption(SEA),vibration acceleration level,and so on.The results suggest that the vibration-attenuation performance of the sandwich shell is remarkable when the high-density core layer is at the end of the shell or abuts the inner skin.The axial gradient material has almost no influence on the vibration frequencies of the shell,whereas the vibration frequencies increase dramatically when the high-density core layer approaches the skin.Moreover,compared to the conventional sandwich shells,the proposed functional grading cylindrical sandwich shell exhibits more potential in mass reduction,stiffness designing,and energy dissipation.

Mass transfer enhancement and hydrodynamic performance with wire mesh coupling solid particles in bubble column reactor

It is of vital significance to investigate mass transfer enhancements for chemical engineering processes.This work focuses on investigating the coupling influence of embedding wire mesh and adding solid particles on bubble motion and gas-liquid mass transfer process in a bubble column.Particle image velocimetry(PIV)technology was employed to analyze the flow field and bubble motion behavior,and dynamic oxygen absorption technology was used to measure the gas-liquid volumetric mass transfer coefficient(kLa).The effect of embedding wire mesh,adding solid particles,and wire mesh coupling solid particles on the flow characteristic and kLa were analyzed and compared.The results show that the gas-liquid interface area increases by 33%-72%when using the wire mesh coupling solid particles strategy compared to the gas-liquid two-phase flow,which is superior to the other two strengthening methods.Compared with the system without reinforcement,kLa in the bubble column increased by 0.5-1.8 times with wire mesh coupling solid particles method,which is higher than the sum of kLa increases with inserting wire mesh and adding particles,and the coupling reinforcement mechanism for affecting gas-liquid mass transfer process was discussed to provide a new idea for enhancing gas-liquid mass transfer.

THE PARAMETER DESIGN AND THE MECHANICAL MODEL OF PIANOWIRE PROBABILITY SCREEN

Based on the analysis of the piano wire’s vibration characteristics, the authors estab lished the mechanical model of piano wire proba bility screen , obtained the analytic so lution of thestable forced vibration of screen wires , and developed the para meter designfor m ula of the piano wire screen . The para meter design form ula has been used in coalpreparation industry .

基于机器视觉的大面积触控屏Metal Mesh缺陷检测

由于在大面积触控屏Metal Mesh的生产过程中,曝光机在长时间运行时会出现运行轨迹偏离,造成金属网断线和毛刺等问题.对此,设计了一种用于检测金属网缺陷的机器视觉检测系统,该机器视觉系统能通过工业摄像机采集图像,然后进行图像增强算法祛除环境干扰,Canny边缘检测算法划定图像边界,能快速检测出缺陷和其坐标位置.

Effect of silicon carbide and wire-mesh reinforcements in dissimilar grade aluminium explosive clad composites

Aluminium composites are inevitable in the manufacture of aircraft structural elements owing to less weight,superior corrosion resistance and higher specific properties.These composites reduce the weight of the aircraft,improve the fuel efficiency and enhance the maintenance duration.This study proposes the development of dissimilar grade aluminium(aluminium 1100-aluminium 5052)composites with different reinforcement’s viz.,stainless steel wire-mesh,silicon carbide(SiC)powders and SiC powder interspersed wire-mesh,by explosive cladding technique.Wire-mesh enhances the friction and restricts the movement of flyer plate to craft a defect free clad,while SiC particles form a band on the interface.Highest strength is obtained when SiC powder interspersed wire mesh is employed as reinforcement.The dissimilar aluminium explosive clad with SiC particle reinforcement results in lower strength,which is higher than that of the weaker parent alloy and that of the conventional dissimilar aluminium explosive clads without any reinforcement.

Performance evaluation of the incorporation of different wire meshes in between perforated current collectors and membrane electrode assembly on the Passive Direct methanol fuel cell

Passive Direct methanol fuel cells(DMFC)are more suitable for charging small capacity electronic devices.In passive DMFC,the fuel and oxidant are supplied by diffusion and natural convection process on the anode and cathode sides respectively.Current collectors(CC)play a vital importance in fuel cell performance.This paper presents the combined impact of perforated and wire mesh current collectors(WMCC)on passive DMFC performance.Three types of open ratios of perforated current collectors(PCC),such as 45.40%,55.40%and 63.40%and two types of wire mesh current collectors with open ratios of 38.70%and 45.40%were chosen for the experimental work.A combination of TaguchiL9 rule is considered.A combination of three PCC and two WMCC on both anode and cathode was used.Methanol concentration was varied from 1 mol·L^(-1)-5 mol·L^(-1)for nine combinations of PCC and WMCC.From the experimental results,it is noticed that the combination of PCC and WMCC with an open ratio of 55.40%and 38.70%incorporated passive DMFC produced peak power density at 5 mol·L^(-1)of methanol concentration.The passive DMFC performance was evaluated in terms of maximum power density and maximum current density.The combined current collectors of PCC and WMCC open ratios of 55.40%+38.70%have more stable voltage than single PCC of open ratio 63.40%at 4 mol·L^(-1)of methanol concentration.

Anping County Shangchen Wiremesh Products CO.,LTD.

Anping County Shangchen Wiremesh Products CO.,LTD. is found in 2010, it is a modem enterprise which set research and development,foreign trade into a whole. The head office is located in “Hometon of Wire Mesh in China” Anping County is famous as hometown of wire mesh. Anping County Shangchen Wiremesh Products CO.,LTD. main products and sales: Gabion Mesh, Wire Mesh Fence, Perforated Metal, Welded Wire Mesh, Filter Mesh, Window Screen, Plastic Net, Filter Cartridge, Metal Basket, Barbecue Wire Mesh, Metal Cage, Fiberglass Mesh, Steel Grating, Metal Wire. Our products are widely used in industry, agriculture, cultivation, construction, transport and mining.By now we have already established friendly business relations with more than 80 countries from Southeast Asia, Europe, America, Middle East,Africa, and the sales amount and customers quadruple annually.

RESEARCH ON THE QGS2020 TYPE PIANO-WIRE PROBABILITY SCREEN

Integrating the probability screen with the piano-wire screen, the authors developed the QGS2020 type piano-wire probability screen (PWPS), a new screen which has a large capacity, high efficiency, and no blinding. The results of the indus trial tests show that this screen is suitable for dry sCreening the fine particles from high-moisture raw coal. This paper describes the operation principles, the structure features and the mechanical model of the QGS2020 type PWPS, and also includes data from industrial tests.

THE DEVELOPMENT OF PIANO——WIRE PROBABILITY SCREEN

The Probability Sizing Screen (PSS) developed by China University of Mining and Technology has been used since 1980 for the screening of moist fine raw coal. More than 600PSS's have been installed in Chinese coal mines, bringing about economic benefits to both coal producers and consumers in terms of reduced energy saving, transpertation cost reduction,and environmental protection. While the PSS treats some high-moisture fine raw coal, the mesh apertures may be blinded by the fine particles stuck on the mesh wire of the screen. Recently, the authors have developed the Piano-wire Probability Screen, a new screen which screens moist fine raw coal. This screen assimilates advantages of PSS, having large deck inclination, large aperture and multideck. In addition the new screen uses piano-wire decks which have a new structure, great open area, and no blinding. The results of sizing fine moist raw coal in Lugou Coal Mine, Henan Province,show that the Piano-wire Probability Screen has a large capacity and high efficiency and is an efficient screen for separating moist raw coal with diameter of 6mm. This paper describes the results of fundamental studies on the Piano-wire Probability Screen. and also includes data from pilot-plant studies.

混杂网格增强超高性能混凝土双向板的弯曲性能

网格增强超高性能混凝土(ultra-high performance concrete,UHPC)具有轻质、高强、耐久性好等特性,已应用于薄壁结构和工程加固领域,但单一网格很难实现高效的增强增韧效应.为研究混杂网格增强UHPC双向板的抗弯性能,对3个钢丝网格与玻璃纤维网格混杂增强UHPC板、3个钢丝网格与玄武岩纤维网格混杂增强UHPC板、6个单一网格增强UHPC板和1个无网格UHPC对照板进行弯曲试验,研究网格种类、总层数及铺层方式对其破坏形态、承载能力和弯曲韧性的影响.结果表明:与单一钢丝网格板和单一玻璃纤维网格板相比,钢-玻璃纤维网格混杂板开裂后表现更显著的硬化现象,在连续网格与混杂短纤维协同效应下,板呈现多裂缝破坏模式,延性较理想.铺设2层网格时,钢-玻璃纤维网格混杂板的承载能力较单一钢丝网格板提升23.7%,且其在20 mm挠度处的残余承载力较单一玻璃纤维网格板提升28.2%;钢-玄武岩纤维网格混杂板峰前阶段的能量吸收值和20 mm挠度处的残余承载力均优于单一玄武岩纤维网格板.网格总层数为3层时,与单一玄武岩纤维网格板相比,2层钢丝网格与1层玄武岩纤维网格混杂增强板在峰前挠度为2 mm时的能量吸收值提高了21.6%,20 mm挠度处的残余承载力提高了42.6%.钢-玻璃纤维网格混杂板的网格强度利用率最理想,其承载能力、能量吸收值及弯曲韧性指标均高于钢-玄武岩纤维网格混杂板.最后,考虑网格强度有效利用率建立了混杂网格增强UHPC双向板抗弯承载力理论公式,适用性良好.

新型粉煤灰泡沫混凝土墙体轴心受压性能试验研究

利用工业固废粉煤灰制备节能与承重一体的新型墙体,对无冷弯薄壁C型钢外包内置钢丝网片固废粉煤灰泡沫混凝土墙体FW、外包1mm厚冷弯薄壁C型钢内置钢丝网片固废粉煤灰泡沫混凝土墙体CW1、外包2mm厚冷弯薄壁C型钢内置钢丝网片固废粉煤灰泡沫混凝土墙体CW2分别在轴压作用下的破坏形态、荷载-位移曲线及墙体极限承载力进行试验研究。研究结果表明:从破坏形态度角度,FW、CW1及CW2在破坏时,冷拔钢丝、冷弯薄壁C型钢发生屈服,泡沫混凝土破裂;FW大面积泡沫混凝土挤压破碎剥落,破坏严重;CW2破坏时完整性优于FW、CW1。从变形角度,CW1、CW2外包的C型钢能够对墙体内部的泡沫混凝土起到约束作用,墙体的刚度得到提升。从承载力角度,CW2较CW1提升了17.4%,较FW提升了23.7%。对墙体的轴压承载力进行理论计算,与墙体轴心受压试验的实测值相比,二者误差在10%以内且小于实测值,满足国家现行规范、行业技术标准相关要求。

基于无线Mesh网络的智慧农业大棚监控系统

针对目前农业大棚生产的实际情况,提出一种基于无线Mesh网络智慧农业大棚控制系统。系统采用TI公司的CC2530芯片作为无线ZigBee节点,组成无线Mesh网络,该网络具有自组网、信息监听、等待、低功耗、多节点、数据透传、自找空闲透传路径等特点。系统使用多组低压继电器控制大棚的通风窗、遮光帘、保温帘、滴灌、补光器。控制系统可以进行算法设计,参数设计及手动和自动切换。系统通过人机界面设置的参数,算法及各种状态,主控器将其储存在自身的E2PROM中。主控制器通过数据比较与算法计算,通过无线网络透传给路由器,控制通风窗、遮光帘、保温帘、滴灌、补光器,实现农业大棚现代化的数字化管理功能。

基于改进Faster RCNN的金属丝网缺陷检测方法

作为一种传统的纺织产品,金属丝网在工业生产、日常生活、科研等领域起着举足轻重的作用,而金属丝网在编制过程中,表面会产生斑点、断线等缺陷,严重影响金属丝网的质量。为保障产品质量,研究了一种基于改进Faster RCNN算法的金属丝网表面缺陷检测方法。首先,为提高模型缺陷特征提取能力,特征提取网络选用深度残差网络(ResNet50)代替原视觉几何群网络(VGG16),并引入注意力模块;随后,训练过程中利用有预热的余弦退火学习率衰减机制,以提高网络检测精度;同时引入k-means算法和遗传算法,设计了更适合金属丝网数据集的锚框尺寸,以提高候选框的精度,解决缺陷定位不准的问题。经实验验证,利用改进Faster RCNN算法检测的平均精度均值(mean average precision,mAP)达86.95%,较原Faster RCNN算法提高18.81%,为金属丝网缺陷的检测提供了一个有效可行的方案。

用于探测液态金属-气体的DLC涂层式丝网探针数值模拟与结构优化

液态金属-气体两相流是铅冷快堆在蒸汽发生器传热管破裂(SGTR)事故下的物理现象之一,考虑到液态金属的不透明性、腐蚀性及高温性,本文提出一种类金刚石(DLC)涂层式丝网探针(WMS)对液态金属-气体两相流相态分布进行探测。基于COMSOL软件,建立了涂层式WMS的数值模型并进行了实验验证,通过电场模拟阐明了该新型探针应用于含液态金属气液两相流的可行性。进一步地,通过改变丝网电极的间距与直径、涂层的厚度,研究了结构参数对涂层式WMS测量精度的影响。结果表明,电极丝横向间距为2~3 mm、垂直间距为1.5~2 mm时,WMS测量精度较高,而涂层厚度和电极丝直径的影响较小。本研究可指导DLC涂层式WMS在液态金属-气体两相环境中的实际应用,并为分析SGTR事故后的多相分布提供技术基础。

Effect of wire mesh casing treatment on axial compressor performance and stability

In this paper,a kind of Wire Mesh Casing Treatment(WMCT)is proposed to improve the stable operating range of the compressor.In contrast to the traditional circumferential groove,as for WMCT,a layer of wire mesh is laid on the surface of the circumferential groove.Parametric studies were conducted on the low-speed axial flow compressor,including the groove width,axial location,and mesh count.The optimum axial location for WMCT is related to its groove width.A higher wire mesh count results in a smaller compressor stall margin improvement.Steady simulations were carried out to study the effect of WMCT on the flow structure of the compressor.The wire mesh in the WMCT has a certain flow resistance,which restricts the flow into and out of the groove.Due to the WMCT,the flow parameter in the tip region of the rotor is less sensitive to changes in the operating conditions of the compressor.The WMCT causes the rotor tip blade loading to shift backward,inhibiting the formation of spill forward of the leakage flow,and thus improving the stability of the compressor.The flow resistance on the groove surface is a new degree-of-freedom for the casing treatment designer.

基于无线Mesh接入服务技术的校园网设计与实现

无线Mesh网简称WMN,是一种新型的无线通信网络;这是一种高容量、高速率、多跳的分布式宽带无线网络.以某体育学院校园网工程为背景,对原有校园网进行分析,提出了全新的整体规划,包括各层交换机和路由器的配置、无线接入的配置等;设计中采用三层交换结构,即接入层、汇聚层和核心层,在各个层上采用相应的配置策略;新的设计提高了校园网数据交换速率和整体性能.

无线mesh网络中学习资源的最优复制策略

以移动学习中的课件点播为应用背景,提出了以连接代价最小的学习资源复制策略,将选择的最优资源预先复制到无线mesh网络(WMNs)中的骨干节点上,当学习者需要某一资源时,可通过Peer-to-Peer(P2P)方式,从最近的节点中获得所需学习资源,从而提高用户的连接速度和播放质量,同时缓解WMNs中网关节点的负载压力.针对所求问题是一个特殊的多维0-1背包问题,提出了一种改进的分布式遗传算法对问题进行了求解.仿真结果说明了改进算法的优越性.

结构参数对金属丝网夹芯板力学性能的影响

为了研究不锈钢编织金属丝网(SSWWM)芯构成的轻质夹芯板的性能,用真空钎焊技术制备不同结构参数(层数、金属网的堆叠顺序和中间层)的夹芯板。对金属丝网夹芯板进行拉伸试验和三点弯曲试验,评估其力学性能。并对抗弯刚度的理论解析值与试验值进行比较。结果表明:适当增加夹芯板的层数、合适的堆叠顺序、在金属丝网间加入层间板均可显著提升夹芯板的力学性能。在所有试样中,带层间板的三层混合堆叠夹芯板(Tw-mix)的抗弯刚度最佳,带层间板的双层45°(Dw-45°)夹芯板的抗拉强度和伸长率最高。