Radon and 'King Solomon's Miners': Faynan Orefield, Jordanian Desert

Concentrations of 222Rn were measured in ancient copper mines which exploited the Faynan Orefield in the South-Western Jordanian Desert. The concentrations of radon gas detected indicate that the ancient metal workers would have been exposed to a significant health risk and indicate that any future attempt to exploit the copper ores must deal with the hazard identified. Seasonal variations in radon concentrations are noted and these are linked to the ventilation of the mines. These modern data are used to explore the differential exposure to radon and the health of ancient mining communities.     

The impact of preoxidation of SAS on biosorption efficiency on activated carbon

We have studied the process of a prolonged dynamic filtration on activated carbon in two biosorption systems — without preoxidation treatment of the initial matter and after ozonization. It has been shown that given the uniform load on activated carbon terms of the organic matter the efficiency of the biosorption process after preozonization is 2.3 times as small compared with that that without pretreatment, which correlates with the change of adsorption free energy.     

一种航空深弹安定器的CFD优化设计

静稳定性是航空深弹稳定飞行的先决条件,某对称配置的航空深弹静稳设计主要通过调整安定器的外形和相对位置实现。利用CFD方法研究某航空深弹在各种安定器外形参数条件下的流体动力参数,优化在总体接口条件限制下最可能实现的安定器外形设计。通过使用Fluent软件计算结果与试验结果的比较,认为此计算结果可信。     

Exif数据格式浅析及其读取应用

照片中镶嵌着丰富的Exif信息,从中可提取出拍摄位置与时间等实用数据服务于我们的工作与生活。本文分析了Exif数据格式,介绍了其读取方法,总结了Exif信息提取算法。结合具体实例,进行测试验证,对日常手机定位精度情况进行了评估。最后,通过生产实践,验证Exif信息对于提高测绘与地理信息单位的作业效率与质量控制的促进作用,同时对应用前景进行了展望。     

Analysis of Methods for Parallel Operation of Frequency Converters

Consideration is given to methods for the parallel operation of frequency converters by applying the active load division. The simulation model of the converter is presented. It consists of three parallel independent modules. A new principle of constructing individual modules of a frequency converter and the principle of their communication interface exhibiting resistance to destabilizing effects and allowing safe operation under nominal conditions even with a 5- to 10% range in time and amplitude values of pilot signals are developed.     

The Effect of Energy-Supply and Performance Indicators on the Performance of Traction-Resource Management Centers

Russian Electrical Engineering - This paper presents the results of a study of the effect of the characteristics of the traction power-supply system on the indicator of the energy supply of...     

Diagnostics of Multioperation Processes Using Basic Cells of Digital Homogeneous Structures

Russian Electrical Engineering - The cells of homogeneous digital structures designed for multioperation process diagnostics are considered in the form of graphic models. Digital circuits and...     

Ultrafast terahertz responses in monolayer graphene

ABSTRACT

We theoretically investigate the ultrafast terahertz (THz) properties of monolayer graphene. The analytical formulations of the photon carrier, electric polarization and optical current are obtained by solving the Bloch-equations in present of the ultrafast THz Gaussian pulse. Graphene shows a large nonlinear and ultrafast optical response at THz frequencies due to the gapless and relativistic Dirac particles with nearly linear energy dispersion. It is found that the photon carrier density, electric polarization and optical current density increase with increasing the frequency of the THz pulse. These theoretical results are in agreement with recent experimental findings. This study confirms further that graphene exhibits important features and is relevant to the applications in the ultrafast THz fields.     

Mathematical simulations of the electromagnetic system of a subminiature magnetoelectric engine

This paper is devoted to simulations of a valve electric engine with excitation from high-energy permanent rare-earth magnets. A feature of the design of the engine under consideration is that a stator is manufactured using the polycapillary glass-fiber technique. The conductors of the distributed stator winding are placed in holes pm the tube wall. The cylindrical bipolar rotor is made of iron–neodymium–boron. The assumption accepted in the work during the solving the Laplace equation has made it possible to obtain analytical solutions for the magnetic flux, emf, current, electromagnetic torque, and electromagnetic power.