Dynamical System of Three Magnetic Layers in the Presence of Porous Media

This paper concerns the linear stability of three viscous fluid layers in porous media. The system is composed of a middle fluid embedded between two semi-infinite fluids, in which the effect of the normal magnetic field is to introduce. The principle aim of this work is to investigate the influence of fluid viscosity and the porosity effect on the growth rate in the presence of normal magnetic field. The parameters governing the layers flow system, the magnetic properties and porosity effects strongly influence the wave forms and their amplitudes and hence the stability of the fluid. The stability criteria are discussed theoretically and numerically and stability diagrams are obtained, where regions of stability and instability are identified. It is found that the stabilizing role for the magnetic field is retarded when the flow is in porous media. Moreover, the increase in the values of permeability parameters plays a dual role, in stability behavior. It has been found that the phenomenon of the dual (to be either stabilizing or destabilizing) role is found for increasing the permeability parameter. It is established that both the viscosity coefficient and the magnetic permeability damps the growth rate, introducing stabilizing influence. The role of the magnetic field and Reynolds number is to increase the amplitude of the disturbance leading to the destabilization state of the flow system, promote the oscillatory behavior. Influence of the various parameters of the problem on the interface stability is thoroughly discussed.

Bending and vibration analyses of a rotating sandwich cylindrical shell considering nanocomposite core and piezoelectric layers subjected to thermal and magnetic fields

The bending and free vibration of a rotating sandwich cylindrical shell are analyzed with the consideration of the nanocomposite core and piezoelectric layers subjected to thermal and magnetic fields by use of the first-order shear deformation theory （FSDT） of shells. The governing equations of motion and the corresponding boundary conditions are established through the variational method and the Maxwell equation. The closed-form solutions of the rotating sandwich cylindrical shell are obtained. The effects of geometrical parameters, volume fractions of carbon nanotubes, applied voltages on the inner and outer piezoelectric layers, and magnetic and thermal fields on the natural frequency, critical angular velocity, and deflection of the sandwich cylindrical shell are investigated. The critical angular velocity of the nanocomposite sandwich cylindrical shell is obtained. The results show that the mechanical properties, e.g., Young＇s modulus and thermal expansion coefficient, for the carbon nanotube and matrix are functions of temperature, and the magnitude of the critical angular velocity can be adjusted by changing the applied voltage.

Effect of nano-oxide layers on the magnetoresistance of ultrathin permalloy films

Ta/NiFe/Ta ultrathin films with and without nano-oxide layers （NOLs） were prepared by magnetron sputtering followed by a vacuum annealing process. The influence of NOLs on the magnetoresistance （MR） ratio of ultrathin permalloy films was studied. The results show that the influence of grain size and textures on the MR ratio becomes weak when the thickness of the NiFe layer is below 15 nm. A higher MR ratio was observed for the thinner （〈 15 nm） NiFe film with NOLs. The MR ratio of a 10 nm NiFe film can be remarkably enhanced by NOLs. The enhanced MR ratio for these ultrathin films can be attributed to the enhanced specular reflection of conduction electrons.

基于模糊聚类和改进Densenet网络的小样本轴承故障诊断

针对实际中轴承的故障数据少难以满足深度学习数据大量训练模型的要求,利用卷积神经网络的微小特征提取优势和模糊聚类不需要训练即可完成分类的特点,提出了一种基于模糊聚类和改进Densenet网络的小样本轴承故障诊断方法。首先将预训练微调的Densenet网络去掉分类只保留特征提取层,设计一个维度自适应全局均值池化层(GAP)代替全连接层(FC),其次利用模糊聚类代替Densenet网络的softmax分类层,不需要训练即可完成分类。实验结果表明:该算法利用小样本数据训练网络中的GAP参数,模型需要的训练样本大大减少,诊断时将轴承时域图像输入到网络中,在GAP层输出1 920个特征数据,不同故障状态的特征数据构建特征向量矩阵,利用模糊聚类方法求得模糊相似矩阵和模糊等价矩阵,当置信因子从大到小变化时,由对应布尔矩阵得到动态聚类图,从而实现轴承故障分类。

Extension of e^N method to general three-dimensional boundary layers

In order to extend the eN method to general three-dimensional boundary layers, the conservation law of the imaginary parts for the wave parameters with a fixed wave vector is deduced. The compatibility relationship （CR） and the general theory of ray tracing （RT）, which have been extensively used in conservative systems, are applied to a general three-dimensional boundary layer belonging to non-conservative systems. Two kinds of eN methods, i.e., the eN-CR method and the eN-RT method, are established. Both the two kinds of methods can wavenumber and the amplitude of the be used to predict the evolutions of the spanwise disturbances in general three-dimensional boundary layers. The reliability of the proposed methods is verified and validated by performing a direct numerical simulation （DNS） in a hypersonic general three-dimensional boundary layer over an aircraft model. The results are also compared with those obtained by other eN methods, indicating that the proposed methods have great potential applications in improving the transition prediction accuracy in general three-dimensional boundary layers.

The impact of land use change on quality evolution of soil genetic layers on the coastal plain of south Hangzhou Bay

Land use change plays an important part in the studies of global environmental change and regional sustainable development. The change of soil quality can particularly reflect the impacts of human socio-economic activities on environment. Taking the coastal plain of south Hangzhou Bay as a study case, we analyzed the effects of land use changes on organic matter （OM）, total nitrogen （TN）, total phosphorus （TP）, available phosphorus （AP）, available potassium （AK）, total salinity （TS）, pH value in soil genetic layers, and assessed soil quality change related to different land use types from 1982 to 2003. The results show that： （1） The general change tendency of soil quality in the coastal plain of south Hangzhou Bay declined obviously in A layer and slightly rise in B （or P） layer and C （or W） layer. The contents of TP decreased generally in all soil genetic layers, but the variety difference of other soil quality indices was relatively great. （2） The change of soil quality in the areas where land use changed is far more remarkable than that with land use unchanged. The value of quality variety is A layer 〉B （or P） layer 〉C （or W） layer. （3） The changes of soil tillage, cultivation, fertilization, irrigation and drainage activities related to land use may make some soil-forming processes disappeared and bring in other new processes which will affect the soil quality and soil genetic layers directly.

An Internet Key Exchange Protocol Based on Public Key Infrastructure

Internet key exchange (IKE) is an automated key exchange mechanism that is used to facilitate the transfer of IPSec security associations (SAs). Public key infrastructure (PKI) is considered as a key element for providing security to new distributed communication networks and services. In this paper, we concentrate on the properties of the protocol of Phase 1 IKE. After investigating IKE protocol and PKI technology, we combine IKE protocol and PKI and present an implementation scheme of the IKE based on PKI. Then, we give a logic analysis of the proposed protocol with the BAN-logic and discuss the security of the protocol. The result indicates that the protocol is correct and satisfies the security requirements of Internet key exchange.

Exploring Soil Layers and Water Tables with Ground-Penetrating Radar

Ground-penetrating radar (GPR) has been used predominantly for environments with low electrical conductivity like freshwater aquifers, glaciers, or dry sandy soils. The objective of the present study was to explore its application for mapping in subsurface agricultural soils to a depth of several meters. For a loamy sand and a clayey site on the North China Plain, clay inclusions in the sand were detected; the thickness, inclination, and continuity of the confining clay and silt layers was assessed; and a local water table was mapped. Direct sampling (soil coring and profiling) in the top meter and independent measurement of the water table were utilized to confirm the findings. Also, effective estimates of the dielectric number for the site with the dielectric number of moist clayey soils depending strongly on frequency were obtained. Thus, important properties of soils, like the arrangement and type of layers and in particular their continuity and inclination, could be explored with moderate efforts for rather large areas to help find optimal locations for the time-consuming and expensive measurements which would be necessary to detail a model of the subsurface.

Modeling of Ad-hoc and Infrastructure Dual Mode Mobile Networks

This paper investigates a mobile telecommunications system that supports both ad hoc and infrastructure mode operations. Based on analytic and simulation models, our study investigates how base station (BS) and ad hoc channel capacity, and the mobility and locality of mobile stations affect the performance of a dual mode system. We show that a dual mode system can significantly outperform a single mode (infrastructure) system when the degree of locality is high. Furthermore, a dual mode system can support much faster mobile users with less BS channels in comparison to an infrastructure mode system. Our study quantitatively identifies the threshold value for the number of ad hoc channels such that beyond this threshold, increasing ad hoc channel capacity will not improve the performance of a dual mode system. Keywords Ad-hoc - infrastructure - dual mode system Yi-Hung Chen received B.S. degree in 2001 and M.S. degree in 2003 of Computer Science and Information Engineering from National Chiao Tung University, HsinChu, Taiwan. He is an engineer of QUALCOMM CDMA technologies Taiwan.His research interests include wireless communication and ad-hoc networking.Hui-Nien Hung received the B.S. degree in mathematics from the National Taiwan University, Taipei, Taiwan, in 1989, the M.S. in mathematics degree from National Tsin-Hua University, Hsinchu, Taiwan, in 1991, and the Ph.D. degree in statistics from the University of Chicago, Chicago, IL, in 1996. He is a Professor at the Institute of Statistics, National Chiao Tung University, Taiwan.His current research interests include applied probability, financial calculus, bioinformatics, statistical inference, statistical computing, and industrial statistics. Yi-Bing Lin (M’96-SM’96-F’04) is Chair Professor and Vice President of Research and Development, National Chiao Tung University.His current research interests include wireless communications and mobile computing Dr. Lin has published over 190 journal articles and more than 200 conference papers. His current research interests include wireless communications and mobile computing Dr. Lin has published over 190 journal articles and more than 200 conference papers. Lin is coauthor of the book Wireless and Mobile Network Architecture (with Imrich Chlamtac; published by John Wiley & Sons). Lin is an IEEE Fellow, an ACM Fellow, an AAAS Fellow, and an IEE Fellow.

A TCP Performance Enhancement Scheme in Infrastructure based Vehicular Networks

Transmission Control Protocol （TCP） in infrastructure based vehicular net- works is dedicated to support reliable Intemet services for mobile users. However, an end-to- end TCP flow not only experiences some com- mon challenges in wireless mobile networks, such as high packet loss rate, medium access competition, unstable wireless bandwidth, and dynamic topology, etc., but also suffers from performance degradation due to traffic congestion at the Road-Side Units （RSUs） that connect the wireline and wireless networks. In order to address the challenging issues related to reliable TCP transmissions in infrastruc- ture based vehicular networks, we propose an RSU based TCP （R-TCP） scheme. For wireline source nodes, R-TCP adopts a novel flow control mechanism to adjust transmission rates according to the status of bottleneck link. Specifically, during the short wireless connec- tion time in Infrastructure based vehicular net- works, R-TCP quickly chooses an ideal trans- mission rate for data transmissions instead of activating the slow start algorithm after the connection is established, and successfully avoids the oscillation of the transmission rate. Simulation results show that R-TCP achieves great advantages than some relate proposals in terms of throughput, end-to-end delay, and packet loss rate.

Virtual 5G Network Embedding in a Heterogeneous and Multi-Domain Network Infrastructure

The pursuit of the higher performance mobile communications forces the emergence of the fifth generation mobile communication(5G). 5G network, integrating wireless and wired domain, can be qualified for the complex virtual network work oriented to the cross-domain requirement. In this paper, we focus on the multi-domain virtual network embedding in a heterogeneous 5G network infrastructure, which facilitates the resource sharing for diverse-function demands from fixed/mobile end users. We proposed the mathematical ILP model for this problem.And based on the layered-substrate-resource auxiliary graph and an effective six-quadrant service-type-judgment method, 5G embedding demands can be classified accurately to match different user access densities. A collection of novel heuristic algorithms of virtual 5G network embedding are proposed. A great deal of numerical simulation results testified that our algorithm performed better in terms of average blocking rate, routing latency and wireless/wired resource utilization, compared with the benchmark.

A Survey on Event Mining for ICT Network Infrastructure Management

1 IntroductionNowadays in China, there are more than six hundred million netizens [1]. On April 11, 2015, the nmnbet of simultaneous online users of the Chinese instant message application QQ reached two hundred million [2]. The fast growth ol the lnternet pusnes me rapid development of information technology （IT） and communication technology （CT）. Many traditional IT service and CT equipment providers are facing the fusion of IT and CT in the age of digital transformation, and heading toward ICT enterprises. Large global ICT enterprises, such as Apple, Google, Microsoft, Amazon, Verizon, and AT＆T, have been contributing to the performance improvement of IT service and CT equipment.

Experimental Study on Magnetorheological Damper for Semi-Active Vibration Control of Civil Infrastructures

Magnetorheological (MR) fluid is a kind of smart material whose rheological properties can be rapidly varied in magnetic field. To make full use of the advantages of MR fluid to devices, a model of double ended, shear combined and valve typed MR damper is designed and manufactured, and the dynamic properties under sinusoidal excitations are experimentally studied. The experiment results show that the maximum damping force of the MR damper at the full magnetic intensity reaches about 20 kN while the maximum power required is less than 50 W, which predicts that the MR damper will be a powerful measurement for semi active vibration control of civil infrastructures.

Methylation profile of bovine Oct4 gene coding region in relation to three germ layers

Previous studies have shown that octamer-binding transcription factor 4（Oct4） plays a significant role in early embryonic development of mammalian animals, and different Oct4 expression levels induce multi-lineage differentiation which are regulated by DNA methylation. To explore the relationship between the methylation pattern of Oct4 gene exon 1 and embryonic development, in this work, five different tissues（heart, liver, lung, cerebrum and cerebellum） from three germ layers were chosen from low age（50–60 d） and advanced age（60–70 d） of fetal cattle and the differences between tissues or ages were analyzed, respectively. The result showed that the DNA methylation level of Oct4 gene exon 1 was significant different（P〈0.01） between any two of three germ layers in low age（〈60 d）, but kept steady of advanced age（P〉0.05）（〉60 d）, suggesting that 60-d post coital was an important boundary for embryonic development. In addition, in ectoderm（cerebrum and cerebellum）, there was no significant methylation difference of Oct4 gene exon 1 between low age and advanced age（P〉0.05）, but the result of endoderm（liver and lung） and mesoderm（heart） were on the contrary（P〈0.01）, which indicated the development of ectoderm was earlier than endoderm and mesoderm. The methylation differences from the 3rd, 5th and 9th Cp G-dinucleotide loci of Oct4 gene exon 1 were significantly different between each two of three germ layers（P〈0.05）, indicating that these three loci may have important influence on bovine embryonic development. This study showed that bovine germ layers differentiation was significantly related to the DNA methylation status of Oct4 gene exon 1. This work firstly identified the DNA methylation profile of bovine Oct4 gene exon 1 and its association with germ layers development in fetus and adult of cattle. Moreover, the work also provided epigenetic information for further studying bovine embryonic development and cellular reprogramming.

基于视觉注意VGGNet的中厚板低碳钢多层多道熔池分类模型

重大装备制造中厚板机器人多层多道焊(multi-layer and multi-pass welding,MLMPW)一直是热点和难点,而实现机器人MLMPW的核心是对其熔池的获取、监控并分类.为了提高MLMPW的自动化和智能化,有必要开发一个熔池图像在线分类系统.针对焊接过程中的熔池图像提出了一种新的MLMPW熔池分类方法——基于视觉注意的(SENet)VGGNet熔池分类方法.为了提高效率和精度,引入迁移学习中的预训练模型到网络训练过程中.因为针对中厚板多层多道熔池研究较少,导致熔池公开数据集较少,为了应对这一问题,需要对数据集进行增广.结果表明,提出的模型可快速有效的对七类MLMPW熔池进行准确分类,预测精度可达到98.39%.

Role of government subsidies in the new energy vehicle charging infrastructure industry:a three-party game perspective

With the new round of scientific and technological revolution and industrial transformation,China has posited the direction of“new infrastructure”in 2020.As one of the seven major industries of the“new infrastructure”,the charging infrastructure(CI)industry not only supports the upgrade of the new energy vehicle industry but also provides developing platforms for emerging industries,such as wireless charging,energy storage,smart microgrid,and new energy consumption.Therefore,the government’s supporting role is crucial for the CI industry.To effectively explore the effectiveness of government’s subsidy policy in the CI industry and promote its healthy development,we employed a game model and discussed the government's evolution process of different game strategies between CI and battery-swapping station(BSS)operators in this study.First,China's government subsidies for the electric vehicle(EV)industry were classified into CIs and BSSs.The subsidies obtained by the CI operators were operating subsidies,whereas those obtained by BSSs were investment subsidies.Second,a game model was constructed,involving the government,operators,and users.The model used backward induction to seek the refined Nash equilibrium solution for CIs and BSS operators.The Nash equilibrium solution indicated that the optimal investment amount and BSS quantity of the operator were positively correlated with the government subsidy intensity.When the profitability of the operators increased and the amount of the subsidies increased,consumers’willingness to use EVs increased and the policy effects were closely related to the benefits of government management.The decisions made by either the users or the operators were inversely related to the operators’management efficiency.Besides,the subsidy policy was affected by the government management.Therefore,in the implementation stage of the government’s future subsidy policies,the government needs to innovate and improve management effectiveness.The government could use subsidy policies as a driving force for developing the CI industry to build a comprehensive ecosystem of the industry,which is also the next key point for the government to promote the development of the CI industry in the future.

Electromagnetic Oscillations in a Spherical Conducting Cavity with Dielectric Layers. Application to Linear Accelerators

We present an analysis of electromagnetic oscillations in a spherical conducting cavity filled concentrically with either dielectric or vacuum layers. The fields are given analytically, and the resonant frequency is determined numerically. An important special case of a spherical conducting cavity with a smaller dielectric sphere at its center is treated in more detail. By numerically integrating the equations of motion we demonstrate that the transverse electric oscillations in such cavity can be used to accelerate strongly relativistic electrons. The electron’s trajectory is assumed to be nearly tangential to the dielectric sphere. We demonstrate that the interaction of such electrons with the oscillating magnetic field deflects their trajectory from a straight line only slightly. The Q factor of such a resonator only depends on losses in the dielectric. For existing ultra low loss dielectrics, Q can be three orders of magnitude better than obtained in existing cylindrical cavities.

一种交通场景下人车检测的VHA-CenterNet无锚方法研究

在真实的交通场景中,车辆和行人检测器容易受到复杂背景的干扰,导致严重的误检和漏检。此外,由于交通场景图像中存在各种不同尺度的目标,大多数检测方法对小物体的检测性能较差,且难以适应交通物体的多样性。为了解决这些问题,提出了一种基于注意力和前景注意模块的无锚方法VHA-CenterNet。在主干网络中加入一个卷积块注意模块(CBAM),以提高对小目标的关注能力。在前景注意模块(FAM)中引入前景信息,以减少复杂背景的干扰。结果表明:在中等难度下,所提出的VHA⁃CenterNet方法在KITTI数据集上的mAP达71.92%,在RTX 2080 Ti上的推理速度为10.68 FPS,可以显著提高人车识别的准确率和速度。在所有情况下,交通场景的人车检测准确率都高于传统模型。

End-to-End Rate Adaptation to Support Heterogeneous Services for Infrastructure-Based Vehicular Networks

Vehicle to Infrastructure （V2I） communications aim to provide mobile users on the road low-cost Internet and driver safety services. However, to meet Quality of Service （QoS） requirements of various applications and officiently utilize limited wireless channel resourc- es, the transport layer protocol has to perform effective rate control in low channel quality and frequent changing topology communica- tion environment. In this paper, we propose a novel rate-control scheme in infrastructure based vehicular networks that avoids conges- tion and starvation and promotes fairness in end-to-end V2I communications. In vehicular networks, a bottleneck roadside unit （RSU） keeps track of its buffer size, aggregate incoming rate, and link throughput, and appropriately allocates bandwidth to traversing flows. With feedback information from the RSU, source nodes dynamically adjust their sending rates to avoid buffer overflow or starvation at the bottleneck RSU. Simulation results show that the proposed scheme can reduce not only packet losses owing to buffer overflow but also buffer starvation time, which improves the utilization efficiency of wireless channel resource.

Magnetic and Structural Properties in Co/Cu/Co Sandwiches with Ni and Cr Buffer Layers

The magnetic and structural properties in Co/Cu/Co sandwiches with Ni and Cr buffer layers were investigated. It was found that the coercivity in Ni layer buffered samples decreases with increasing Ni layer thickness, while that in Cr layer buffered ones increases with increasing Cr layer thickness, leading to a large difference in field sensitivity of their giant magnetoresistance (GMR) properties. X-ray diffraction and high resolution transmission electron microscope images exhibited that there is a strong fcc (111) texture in the samples with Ni buffer layer. But there are only randomly oriented potycrystalline grains in Cr buffered sandwiches. According to atomic force microscope topography, the surface roughness of Cr buffered sandwiches is smaller than that of Ni buffered ones. It is demonstrated that buffer layer influences both magnetic and structural properties in Co/Cu/Co sandwiches as well as their GMR characteristics.