Geochemistry, mineral paragenesis and geothermal conditions of oreforming fluids from the Ain El Bey Cu–Fe deposit: potential occurrence of native gold and precious metal traces (North African orogenic belt, Northern Tunisia)

The Ain El Bey abandoned mine, in North-West Tunisia, fits into the geodynamic context of the European and African plate boundary. Ore deposit corresponds to veins and breccia of multiphase Cu–Fe-rich mineralization related to various hydrothermal fluid circulations. Petromineralogical studies indicate a rich mineral paragenesis with a minimum of seven mineralization phases and, at least, six pyrite generations. As is also the case for galena and native silver, native gold is observed for the first time as inclusion in quartz which opens up, thus, new perspectives for prospecting and evaluating the potential for noble metals associated with the mineralization. Scanning Electron Microscope--Energy Dispersive Spectroscopy and Transmission electron microscopy analyses show, in addition, a large incorporation of trace elements, including Ag and Au, in mineral structures such as fahlores(tetrahedrite-tennantite) and chalcopyrite ones. The mineral/mineral associations, used as geothermometers, gave estimated temperatures for the mineralizing fluids varying from 254 to 330 ℃ for phase Ⅲ, from 254 to 350 ℃ for phase Ⅳ, and from 200 to 300 ℃ for phases Ⅴ and Ⅵ. The seventh and last identified mineralization phase, marked by a deposit of native gold, reflects a drop in the mineralizing fluid’s temperature(< 200 ℃) compatible with boiling conditions. Such results open up perspectives for the development of precious metal research and the revaluation of the Cu–Fe ore deposit at the Ain El Bey abandoned mine, as well as at the surrounding areas fitting in the geodynamic framework of the Africa-Europe plate boundary.

Electroviscous effect on electromagnetohydrodynamic flows of Maxwell fluids in parallel plate microchannels

Considering the influence of the streaming potential and electroviscous effects, the analytical solutions for electromagnetohydrodynamic (EMHD) flows in parallel plate microchannels are obtained. The electrolyte solutions in the microchannels are taken as generalized Maxwell fluids, and slip boundary conditions are adopted. To accurately analyze the EMHD flow characteristics, the variation trends of the electroviscous effects with the corresponding parameters must be understood. The results show that the electroviscous effects increase with the increase in the relaxation time De, the slip coefficient , and the wall zeta potential 0. However, the increase in the inverse of the electrical double-layer (EDL) thickness K, the electrical oscillating Reynolds number Re, and the ionic P'eclet number Pe can decrease the electroviscous effects. We also demonstrate that the electroviscous effect on the EMHD flows of generalized Maxwell fluids is larger than that of Newtonian fluids. This work will be useful in designing EMHD flows in parallel plate microchannels.

Numerical Simulation of Slurry Diffusion in Fractured Rocks Considering a Time-Varying Viscosity

To analyze the effects of a time-varying viscosity on the penetration length of grouting,in this study cement slur-ries with varying water-cement ratios have been investigated using the Bingham’sfluidflow equation and a dis-crete element method.Afluid-solid coupling numerical model has been introduced accordingly,and its accuracy has been validated through comparison of theoretical and numerical solutions.For different fracture forms(a single fracture,a branch fracture,and a fracture network),the influence of the time-varying viscosity on the slurry length range has been investigated,considering the change in the fracture aperture.The results show that under different fracture forms and the same grouting process conditions,the influence of the time-varying viscosity on the seepage length is 0.350 m.

Nonlinear phenomena in vibrations of embedded carbon nanotubes conveying viscous fluid

Various nonlinear phenomena such as bifurcations and chaos in the responses of carbon nanotubes(CNTs)are recognized as being major contributors to the inaccuracy and instability of nanoscale mechanical systems.Therefore,the main purpose of this paper is to predict the nonlinear dynamic behavior of a CNT conveying viscousfluid and supported on a nonlinear elastic foundation.The proposed model is based on nonlocal Euler–Bernoulli beam theory.The Galerkin method and perturbation analysis are used to discretize the partial differential equation of motion and obtain the frequency-response equation,respectively.A detailed parametric study is reported into how the nonlocal parameter,foundation coefficients,fluid viscosity,and amplitude and frequency of the external force influence the nonlinear dynamics of the system.Subharmonic,quasi-periodic,and chaotic behaviors and hardening nonlinearity are revealed by means of the vibration time histories,frequency-response curves,bifurcation diagrams,phase portraits,power spectra,and Poincarémaps.Also,the results show that it is possible to eliminate irregular motion in the whole range of external force amplitude by selecting appropriate parameters.

Insight into the dynamics of non-Newtonian Carreau fluid when viscous dissipation,entropy generation,convective heating and diffusion are significant

The investigation endorsed the convective flow of Carreau nanofluid over a stretched surface in presence of entropy generation optimization.The novel dynamic of viscous dissipation is utilized to analyze the thermal mechanism of magnetized flow.The convective boundary assumptions are directed in order to examine the heat and mass transportation of nanofluid.The thermal concept of thermophoresis and Brownian movements has been re-called with the help of Buongiorno model.The problem formulated in dimensionless form is solved by NDSolve MATHEMATICA.The graphical analysis for parameters governed by the problem is performed with physical applications.The affiliation of entropy generation and Bejan number for different parameters is inspected in detail.The numerical data for illustrating skin friction,heat and mass transfer rate is also reported.The motion of the fluid is highest for the viscosity ratio parameter.The temperature of the fluid rises via thermal Biot number.Entropy generation rises for greater Brinkman number and diffusion parameter.

Simulation of Two-Phase Flowback Phenomena in Shale Gas Wells

The gas-water two-phaseflow occurring as a result of fracturingfluidflowback phenomena is known to impact significantly the productivity of shale gas well.In this work,this two-phaseflow has been simulated in the framework of a hybrid approach partially relying on the embedded discrete fracture model(EDFM).This model assumes the region outside the stimulated reservoir volume(SRV)as a single-medium while the SRV region itself is described using a double-medium strategy which can account for thefluid exchange between the matrix and the micro-fractures.The shale gas adsorption,desorption,diffusion,gas slippage effect,fracture stress sensitivity,and capillary imbibition have been considered.The shale gas production,pore pressure distribution and water saturation distribution in the reservoir have been simulated.The influences of hydraulic fracture geometry and nonorthogonal hydraulic fractures on gas production have been determined and discussed accordingly.The simulation results show that the daily gas production has an upward and downward trend due to the presence of a large amount of fracturingfluid in the reservoir around the hydraulic fracture.The smaller the angle between the hydraulic fracture and the wellbore,the faster the daily production of shale gas wells decreases,and the lower the cumulative production.Nonplanar fractures can increase the control volume of hydraulic fractures and improve the production of shale gas wells.

Chemically Radiative MHD Flow of a Micropolar Nanofluid over a Stretching/ Shrinking Sheet with a Heat Source or Sink

This study examines the behavior of a micropolar nanofluidflowing over a sheet in the presence of a transverse magneticfield and thermal effects.In addition,chemical(first-order homogeneous)reactions are taken into account.A similarity transformation is used to reduce the system of governing coupled non-linear partial differ-ential equations(PDEs),which account for the transport of mass,momentum,angular momentum,energy and species,to a set of non-linear ordinary differential equations(ODEs).The Runge-Kutta method along with shoot-ing method is used to solve them.The impact of several parameters is evaluated.It is shown that the micro-rota-tional velocity of thefluid rises with the micropolar factor.Moreover,the radiation parameter can have a remarkable influence on theflow and temperature profiles and on the angular momentum distribution.

GUIDS: A Graphical User Interface Development System in UniECAD

UniECAD is an integrated electronic CAD system, the user interfaCe develotwent system is the key of the integration of UniECAD. This paper presents the architecture of GUIDS, a graphical user interface development system in UniECAD, and then discusses a series of new techniques and methods in the design and the implementation of this system around the following aspects: the editing environment of interface elements, the implementation of dialogue control and the automatic generation of interface code. As an example, the generation of the main interfaces of UniECAD shows the procedure of the development of user interfaces with this development system.

A Modified Characteristics Finite Element Method for the Electroneutral Micro-Fluids

In this paper,a numerical method for the electroneutral micro-fluids based on thefinite element method will be given.In order to deal with the non-linearity of the equation,the modified characteristics method will be used to deal with the tempo-ral derivates term and the convective term.In this way,the non-linear equation can be linearlized.Then,we will give the unconditional stability and optimal error estima-tion.At last,some numerical results are given to show the effectiveness of our method.From the stability analysis we can see that the method is unconditionally stable.The numerical results show that our method is robust.

工业互联网标识解析体系安全技术研究

工业互联网是工业系统和互联网体系与新一代科学技术融合发展的产物,它通过机器、人、物、料的全面互联对工业数据进行快速计算处理和模型构建。本文从架构安全、身份安全、数据安全及运营安全等方面全方位分析了工业互联网标识解析体系安全风险,并提出了采用安全接入、访问控制等关键技术确保工业互联网标识解析体系网络、信息与数据安全。本研究结合5G、人工智能、云计算、大数据等技术可推动传统产业快速转型升级和工业智能化发展。

Combined static mixers for high viscous fluids mixing

A new static mixer Cross-over-Disc has been invented to strip off the boundary layer and to make strong radial mixing.The pressure drop of Cross-over-Disc is 12–26 times as large as that of empty pipe with equivalent diameter and length.The mixing performance of Cross-over-Disc with 14 elements has been investigated in the viscosity range of 190–250 Pa·s by decoloration method,and the gray analysis of images shows that mixing inhomogeneity is about 7.5%and 9.4%for the mixing ratio of 5∶1 and 10∶1,respectively.Furthermore,mixing inhomogeneity for a combination of static mixing elements(four from Cross-over-Disc and three pairs from Sulzer-type)can be decreased to 2.1%–3.1%within a reasonable range of pressure drop.

Android OS手机平台的安全机制分析和应用研究

作为现实生活中非常重要的通讯工具,手机的安全性的意义不言而喻。为研究Android OS是如何保障手机安全的,文中在深入了Android智能手机操作系统平台的结构和特点的基础上,结合手机使用过程中常出现的一些安全问题,细致地诠释了手机安全的涵义,研究了Android OS手机安全原则和安全机制。实验以最常见的媒体播放任务为例,具体分析Android的安全机制运行原理。实验结果表明,Android智能平台是以Linux安全机制为基础,借助其两个安全元素——UID和权限,很好地保障了手机中的数据安全和系统安全。

Impact of Copy Number on Transgene Expression In Tobacco

对农杆菌介导法获得的转 β_葡糖醛酸酶 (β_glucuronidase ,GUS)基因 (uidA)烟草 (NicotianatabacumL .)进行GUS表达分析 ,发现部分转基因植株无GUS活性。进一步Southern杂交结果发现 ,GUS基因失活植株的基因组中整合了多个uidA拷贝 ,而GUS活性高的转基因植株多为uidA单拷贝整合 ,表明uidA基因失活与基因多拷贝整合有关。Northern杂交结果显示 ,失活植株无特异uidARNA杂交带 ,而GUS活性高的植株可检测到明显的杂交信号 ,说明多拷贝引起的基因失活发生在RNA水平。

Gnutella网络中的异构延迟现象及其解决方案

在基于Gnutella协议的Peer to Peer网络中,异构延迟是普遍存在的一种现象并严重影响网络中的信息传递。具体地分析了该现象对Gnutella网络性能的影响,重新定义了两种消息控制机制,提出了一种能有效消除该现象影响的解决方案。

我国物联网发展思考

自从IBM提出了"智慧的地球"概念,得到奥巴马政府积极回应,并寄希望于大力发展物联网产业带动经济的复兴,物联网在全世界各国变得炙手可热起来,我国也不例外,制定了一系列的产业扶持政策,力争在第三次信息产业浪潮中抢占制高点。通过探讨国内外物联网发展的最新动态,对一些易混淆的概念进行辨析,深入研究制约我国物联网发展的关键因素,并提出一些解决之道,以作抛砖引玉,最后对物联网的发展前景进行了展望。

图书馆行业RFID-UID编码标准化方案问题探讨

通过对现行图书馆RFID-UID应用模式和商业物流RFID-UID标准的对比分析及与ISBN的关系,提出了书馆行业RFID-UID的编码方案。

一种超高频电子标签电路及应用

提出一种UHF频段的电子标签电路,内容包括芯片的结构,指令集,防冲突协议、存储器等,还给出一个典型应用方案。

基于RFID的二进制防碰撞算法的改进

本文从RFID(Radio Frequency Identification,无线射频识别技术)的关键技术之一射频标签序号防碰撞入手,先介绍了常用的二进制防碰撞算法,针对其在终端射频卡数量越多,UID(Ubiquitous Identifications,身份识别标签)位数越多,传送时间越长的缺点;提出了二进制防碰撞算法的改进算法,改进算法与传统算法相比,在标签位数逐渐增多的情况下,其查询次数增加速度明显减慢;最后通过仿真给以证实。

关于UIMS发展方向和开发原则的探讨

开发友好的人机界面已经成为计算机史上的又一次软件革命；对于整个软件工程学有着巨大的影响─—智能型计算机系统加上友好的人机界面，无疑是提高软件工程水平和软件产品质量的重要途径，ＵＩＭＳ就这样应运而生了。而设计一个成功ＵＩＭＳ的关键首先在于确定正确的发展方向，从战略上保证ＵＩＭＳ立于不败之地；同时确立良好的开发原则，在战术上保证ＵＩＡＩＳ的最优化设计。