Heavily doped silicon:A potential replacement of conventional plasmonic metals

The plasmonic property of heavily doped p-type silicon is studied here.Although most of the plasmonic devices use metal-insulator-metal(MIM)waveguide in order to support the propagation of surface plasmon polaritons(SPPs),metals that possess a number of challenges in loss management,polarization response,nanofabrication etc.On the other hand,heavily doped p-type silicon shows similar plasmonic properties like metals and also enables us to overcome the challenges pos-sessed by metals.For numerical simulation,heavily doped p-silicon is mathematically modeled and the theoretically obtained re-lative permittivity is compared with the experimental value.A waveguide is formed with the p-silicon-air interface instead of the metal-air interface.Formation and propagation of SPPs similar to MIM waveguides are observed.     

Effects of Various Preparation and Polymerization Procedures on the Isospecific Nature of TiCl3-Based Polypropylene Catalysts

Summary As one of a series approaches in using two-component and three-component donor-free Ziegler–Natta catalysts, in this preliminary work, the effects of various preparation and polymerization conditions including catalyst preparation by wet- or dry- grinding, the type of cocatalyst, with or without pretreatment of catalyst by cocatalyst before polymerization, Al/Ti molar ratio and polymerization temperature, etc., on the isospecific nature of active sites of the TiCl₃ catalyst were studied through a systematic characterization of the PPs by a combination of GPC, ¹³C-NMR with TREF method. It was demonstrated that the types of Al-alkyl cocatalysts play the most dominant role in determination of isospecificity of activate sites and its distribution. A plausible mechanism (Scheme 1) regarding the formation of isospecific active sites with different stability in terms of Ti–Al bimetallic complexing depending on the type of cocatalyst had been proposed. Except the catalyst grinding method, other factors eg., pretreatment, temperature, and Al/Ti molar ratio, etc. did not show obvious effects on the isospecific nature of active sites.     

Calculation of Limestone Burning in a Coke-Fired Kiln

A mathematical model of the steady-state process of limestone burning in a kiln is proposed in the one-dimensional approximation. The model is developed on the basis of the laws of conservation of mass and energy with regard for the kinetics of physicochemical transformations and is a set of ordinary differential equations. If the geometric parameters of the kiln are known, then by setting the conditions at the inlet and outlet, i.e., the boundary conditions, and solving the boundary-value problem, one can determine the thermochemical and hydrodynamic situation in the kiln. In particular, the model allows one to find the kiln length distributions of the compositions and temperatures of the solid and gas phases, the mass flow rates, and the volume contents at various feed rates and initial temperatures of air, raw material, and fuel and different coke and limestone particle sizes.     

A research into thermal field in fluid-saturated porous media

Until now, the theory, methodology of investigations, and interpretation of thermometry data have been most completely developed for single-phase (oil, water, or gas) flows in formations. However, multiphase (oil+gas, oil+water, and oil+water+gas) flows in formations are more common in practice. This is primarily typical for fields featuring a high value of gas factor and saturation pressure, as well as for cases of formation tests at low values of bottom-hole pressure. Analysis of actual thermograms under these conditions has shown that the earlier-developed techniques for the cases of single-phase flows in the formation and the well cannot be applied here.This paper presents research data on the influence of the adiabatic and Joule-Thomson effects and the heat of fluid degassing on temperature field in porous medium.     

深埋地下洞室群动力时程分析中人工边界的设置

针对深埋地下洞室群动力时程分析中建模范围和人工边界设置问题,基于地下洞室群地震波动场的分布特征,提出一种动力时程分析中洞室群模型人工边界的设置方法。该方法允许模型不建至地表,而采用解析法求解地表反射波动场,并通过人工边界入射至模型。基于波场分离原理,使模型四周边界仅透射外行散射波,保障模型四周边界的计算精度。理论试验和实际工程计算表明,该方法计算精度较高,能满足地下洞室群动力时程计算对人工边界的精度要求,同时有效减少模型单元量,缩短动力时程的求解耗时。     

Ceramogranite made from natural minerals found in Uzbekistan

A technology has been developed for manufacturing ceramogranite from natural materials found in Uzbekistan. The processes occurring during heat treatment of porcelain stone from the Boinaksaiskoe deposits have been investigated. The optimal calcination temperature, the composition of the ceramic paste, and the effect of individual components of the batch on the properties of ceramogranite have been determined. The kinetics of sintering of experimental pastes has been studied. It is shown that combining different types of mineral raw materials makes it possible to obtain ceramogranite with high thermomechanical characteristics.     

Characteristics of brick used as aggregate in historic brick-lime mortars and plasters

Mortars and plasters composed of a mixture of brick powder and lime have been used since ancient times due to their hydraulic properties. In this study, raw material compositions, basic physical, mineralogical, microstructural and hydraulic properties of some historic Ottoman Bath brick-lime mortars and plasters were determined by XRD, SEM-EDS, AFM, TGA and chemical analyses. The mineralogical and chemical compositions, microstructures, morphologies and pozzolanicities of the brick powders and fragments used as aggregates in the mortars and plasters were examined to find out the relationship between hydraulic properties of the mortars and the bricks. The characteristics of bricks used in the bath domes were also determined to investigate whether the brick aggregates used in mortar and plasters were prepared from these bricks. The results indicated that the mortars and plasters were hydraulic owing to the presence of crushed brick powders that have good pozzolanicity. The brick powders had high pozzolanicity because they contained high amounts of calcium-poor clay minerals in their raw materials that were fired at low temperatures. On the other hand, bricks used in the domes had poor pozzolanicity with different mineralogical and chemical compositions from bricks used in mortars and plasters. Based on the results of the analysis, it was thought that the bricks manufactured with high amounts of clays were consciously chosen in the preparation of hydraulic mortars and plasters.     

掌纹识别的一种新的特征提取方法*

通过分析已有的掌纹识别方法和特征提取所面临的问题,提出了一种新的掌纹识别算法——直接监督保局投影(DSLPP)。该算法在传统的保局投影（LPP）算法中加入类别信息,同时对角化XLX T和XDX T,可以直接达到保局投影算法的最优准则,并且无须在原始高维数据(如原始图像)上先进行任何特征提取或降维处理。在PolyU 掌纹库中进行实验,与Eigenpalm、Fisherpalm和LPP算法相比具有较高的识别速度和识别率;当掌纹库中图像总数为600张,共100人,每人用5张掌纹图像作为训练样本,1张掌纹图像作为     

特高压直流输电换流阀控制系统应用

换流阀作为换流站中的关键设备,能实现交流电与直流电之间相互转换。换流阀控制系统主要功能是触发、监视和保护换流阀。以±800 kV特高压沂南换流站极Ⅱ的PCS-8600换流阀为背景,介绍换流阀控制系统的原理及配置方式,对阀控单元及晶闸管控制单元的重点功能进行详细分析。针对实际运行中需要重点关注的阀控接口信息,给出归纳与总结,为今后换流阀系统的运行维护及消缺处理提供参考。