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关键词： Flow classification   Graphics Processing Unit (GPU)   GPU cluster   Mobile edge computing   Software Defined Networking   Software Defined Mobile Edge Computing (SDMEC)  

摘要： Mobile Edge Computing (MEC) provides different storage and computing capabilities within the access range of mobile devices. This moderates the burden of offloading compute/storage-intensive processes of the mobile devices to the centralized cloud data centers. As a result, the network latency is reduced and the quality of service provided for the mobile end users is improved. Different applications benefit from the large-scale deployments of MEC servers. However, the considerable complexity of managing large scale deployments of the sheer number of applications for the millions of mobile devices is a challenge. Recently, Software Defined Networking (SDN) is leveraged to resolve the problem by providing unified and programmable interfaces for managing network devices. Most of the current SDN packet processing services are tightly dependent on the packet classification service. This primary service classifies any incoming packet based on matching a set of specific fields of its header against a flow table. Acceleration of this basic process considerably increases the performance of the SDN-based MEC. In this paper, the hierarchical tree algorithm, which is a packet classification method, is parallelized using popular platforms on a cluster of Graphics Processing Units (GPUs), a cluster of Central Processing Units (CPUs), and a hybrid cluster. The best scenario for the parallel implementation of this algorithm on the CPU cluster is that which combines OpenMP and MPI. In this case, the throughput of the classifier is 4.2 million packets per second (MPPS). On the GPU cluster, two different scenarios have been used. In the first scenario, the global memory is used to store the rules and the Hierarchical-trie of the classifier while in the second scenario we break the filter set in a way that the resulting Hierarchical-trie of each subset could be stored in the shared memory of GPU. According to the results, although the first GPU cluster scenario achieves a throughput of

关键词： 松散体   润湿作用   固液接触角   表面张力   复合浆液   高温火区   注浆  

摘要： 为了解决黑岱沟煤矿南帮S01综放工作面因上覆近距离高温松散体存在的裂隙使得工作面在正常回采过程中易受地表渣台高温火区有害气体侵入威胁及引起采空区遗煤自燃问题,基于传统预防性注浆防灭火理论基础,提出改变固液接触角、表面张力等特性进而达到提高浆液的动力学特性及润湿性能,实验过程找出具有最佳起泡性、润湿性等防灭火效果的复合浆液。实践证明,改良型复合浆液对工作面上覆渣台重点区域的注浆治理效果突出,能够确保工作面安全生产。

关键词： 标准皮托管   激光多普勒测风仪   量值溯源   不确定度  

摘要： 计量检定规程《皮托管》JJG 518-1998中,只对工作级皮托管的计量检定方法进行了阐述,而高等级的标准皮托管的量值溯源一直没有明确规定。为保证高等级的标准皮托管测量数据的准确、可靠,对其测量结果的不确定度分析很有必要。选择激光多普勒测风仪作为标准器建立适应科技发展的量值溯源体系,对标准皮托管进行计量检定,并给出新体系下标准皮托管校准系数测量结果的不确定度评定分析。该方法对标准皮托管测量结果的可信度评定以及计量检定规程《皮托管》JJG 518-1998的修订具有较强的参考价值。

关键词： BOPP薄膜   表面张力   复合添加剂   衰减速度   薄膜厚度  

摘要： 通过采用复合添加剂与母料混合制备BOPP薄膜的方式,探究复合添加剂种类、含量对BOPP薄膜表面张力的影响,以试验手段研究了复合添加剂B对不同厚度薄膜表面张力的具体影响。研究结果表明,复合添加剂会影响BOPP薄膜表面张力的衰减速度,无添加剂的薄膜表面张力衰减最快,复合添加剂A次之,复合添加剂B的表面张力衰减最慢;复合添加剂B含量为0.2%~0.4%时,BOPP薄膜稳定的表面张力随着复合添加剂B的含量的增加而增大,含量为0.2%、0.3%、0.4%的薄膜表面张力稳定时分别为38.1 mN·m-1、39.1 mN·m-1、39.6 mNm-1;当复合添加剂B含量为0.4%时,薄膜表面张力下降速度随着厚度的增加而变慢;不同厚度薄膜表面张力稳定时,表面张力从小到大的顺序为:25μm<30μm<35μm。

关键词： 喷墨印花   染料墨水   黏度   表面张力   涤棉织物  

摘要： 采用行星式球磨机对分散染料进行研磨,分析了添加消泡剂和活性染料对研磨效率的影响。通过黏度调节剂、水溶性高分子化合物、表面张力调节剂和pH值调节剂等调控墨水各项物理性能,以使其符合喷墨打印墨水的要求。优化的墨水处方为:分散红色浆25%,活性红染料1.25%,乙二醇10%,丙三醇12%,聚乙烯吡咯烷酮-K30(PVP-K30)0.3%,脂肪醇聚氧乙烯醚(FAPE)0.2%,十二烷基硫酸钠(SDS)0.1%,三乙醇胺0.2%,消泡剂AFE-31680.01%,去离子水50.94%。将自制墨水应用到涤棉织物的直喷印花中,印花后织物的K/S值较高,经纬向的轮廓清晰度较好,色牢度均在4级以上。

关键词： 大坝   测压管   观测数据   分析研究   渗漏  

摘要： 测压管是观测大坝运行情况的重要设施。以测压管实测资料为基础,采用特征值统计法、作图法、比降法对观测资料进行分析。通过测压管水位相关分析、测压管过程线图绘制及计算正常蓄水位下各测压管断面的比降,结合除险加固情况、运行中大坝存在问题、地质勘察成果,根据土石坝渗流基本理论,得出大坝不存在坝基渗漏安全隐患,现状溢洪道南侧坝体存在的发展性集中渗漏,判断为防渗体破坏,且渗漏影响范围在坝体内有扩大。

关键词： Rolling circulating fluidized bed (RCFB)   Rolling amplitude Theta   Rolling period T   Improved cluster renewal model (ICRM)   Heat transfer coefficient  

摘要： This paper presents a novel method to predict the gas layer thickness delta' in an improved cluster renewal model (ICRM) to calculate the heat transfer coefficient h', for a rolling circulating fluidized bed (RCFB). Eulerian-Eulerian two-fluid model (TFM) with kinetic theory of granular flow is used to perform a numerical simulation. After comparing the pressure gradient -Delta p/Delta z' and the simulated heat transfer coefficient between multiphase and the wall h(gs) with previously published experiment data, the correctness and reliability of the simulation are able to be verified. In conclusion, firstly, the variation of h(c)s calculated from delta' in the ICRM is almost the same with hgs in the case that the RCFB undergoes the rolling motion. In order to quantitatively evaluate the proposed novel method, an error percentage a between h', calculated from delta' and h(gs) is 2.043% which is less than 5%. This certified that the novel method to predict delta' in the ICRM has higher accuracy to calculate h', Secondly, h', calculated from delta' is mainly influenced by rolling amplitude 0 rather than by rolling period T. Specifically, with the increase of 0, amplitudes of Ts are decreased, which is caused by the increased heat transfer and the decreased (5' between cluster and wall. The decreased amplitudes of T-s are able to increase heat transfer efficiency, which eventually increases h'c, Thirdly, in the case that normalized rolling period tIT is changed from 0 to 0.5, higher h', calculated from delta' in Region I results from the large local cross-sectional particle volume fraction go, 1 in Region I with a smaller delta', while lower h', calculated from (5' in Region III results from the smaller clo,1 in Region III with a larger delta'. Therefore, it is concluded that h'(c), calculated from delta' is able to well predict the bed-to-wall heat transfer coefficient of the RCFB even if the rolling motion is considered. (C) 2020 The Society of Powder Technology Japan

关键词： Fluidized beds  

摘要： In this paper, a 3D two-phase simulation involving the complex heat transfer characteristics within a vertical cylindrical fluidized bed was conducted numerically. The accuracy of mathematical modeling has been validated by comparing with the experimental results. The discrete ordinate model (DOM) was employed to investigate the radiation heat transfer in a fluidized bed. The user-defined function (UDF) was compiled by considering the effect of the particle flow emissivity on radiation heat transfer, and coupled the two-phase flow field by using the gray and non-gray model respectively. The results show that the non-gray model can better depict the selected absorption of radiation wavelength in two-phase flow heat transfer than gray model. Furthermore, under high heat flux density conditions, the proportion of radiation heat transfer increases gradually with the increase of heat flux, which can reach about 40% of the total heat transfer coefficient. Meanwhile, other factors about radiation heat transfer such as initial solid packing height, inlet gas velocity, and other conditions were studied and consistent with the thermal experimental regularity. The findings demonstrated that the radiation heat transfer and it's modeling play an important role in two-phase heat transfer of fluidized bed.

关键词： Rotors   Shock absorbers   Bars   Windings   Synchronous motors   Induction motors   Circuit faults   Air gap flux   damper bar   fault diagnostics   field winding   off-line testing   salient pole synchronous motor (SM)   search coil   spectral analysis   starting transient  

摘要： Recent cases of broken damper bars and shorted field winding turns in synchronous motors (SMs) have shown that rotor faults can degrade motor performance and lead to a forced outage of the motor and driven process. However, detection of SM rotor faults has not received much attention since SMs are not as common as induction motors. Detection of SM rotor faults is difficult, as the damper bar is active only under the starting or load transients, and shorted field winding turns result only in a slight increase in rotating asymmetry. SM rotor fault testing in the field mainly relies on visual inspection or off-line tests, and new test methods that can provide reliable detection of the faults without motor disassembly is highly desirable. In this article, new test methods for not only detecting, but also classifying the two types of SM rotor faults under motor standstill and starting are proposed. A finite element and experimental study on 1.1 MW and 30 kW salient pole SMs are provided to verify the proposed methods. It is shown that damper and field winding faults can be detected and classified with high sensitivity and reliability compared to conventional tests.

关键词： ECIME fluidized-bed   Copper removal   Electrodeposition   Enhanced mechanism   Reaction model  

摘要： For the purification of heavy metal wastewater, internal micro-electrolysis (IME) was considered as an effective method but some disadvantage greatly restricts its application. Electrocatalytic internal micro-electrolysis (ECIME) fluidized bed using iron-carbon particles was proposed to avoid disadvantaging of IME. The principal aim of this study was to investigate the enhanced removal characteristics, mechanism, and kinetic behavior of Cu(II) that none clear before. ECIME reactor shows a better copper removal performance and depends much on the polarization of the external electric field (EEF). Both the reaction rate and removal efficiency of copper electrodeposition improved obviously. Noteworthy is more than 88.0% of Cu(II) in aqueous solutions was removed by enhanced electrodeposition, and only about 10.0% of Cu(II) was absorbed and flocculated through the in situ formed iron hydroxyl compounds. Through scanning electron microscopy (SEM) and electrochemical analysis, copper can effectively electrodeposition on the surface of iron-carbon particles in ECIME reactor and accordingly the enhanced mechanisms were proposed. 1) Iron-carbon particles of ECIME formation of microelectrodes with high surface potential, larger specific area, and active sites through electrode collision and repolarization. 2) Copper electrodeposition on the formed microelectrodes exhibited greater reduction peak potential, reaction overpotential and exchange current density, which influenced by the polarization voltage significantly. 3) The electrocatalytic environment tend to in situ generate iron polymer hydroxyl compounds help to further remove residual Cu(II). ECIME fluidized-bed has promised potential for heavy metal containing wastewater purification and metal recovery. In addition, the proposed reaction models will be useful for field application. (C) 2020 Elsevier Ltd. All rights reserved.