无线式与有线式电压互感器二次压降测试技术优势对比与检测分析

针对传统有线式电能计量互感器二次压降测试方法完成1次测试过程需要2 h,且存在测量回路较长、误差较大、对相困难,并易造成电压互感器二次短路的情况,通过引用以GPS、载波通信技术和比对测量算法为核心技术的无线式二次压降测试技术,测量1个回路只需20 min,方便、高效、安全。

有线式网位仪的试制

网位仪是一种重要的水声助渔仪器。根据使用要求不同，网位仪能够提供的信息差别也很大。结构比较复杂的网位仪，不仅能指示出网具在水中的位置，还能将渔网周围鱼群分布情况．网口张开的程度、网中渔获量的多少等信息指示出来。如上月挪威西姆莱特公司来我市进行技术交流时，

有线嵌入式以太网在遥测终端机中的应用研究

针对当前遥测终端机有线网络通信能力不足,为使遥测终端机具备有线嵌入式以太网网络通信功能,在分析目前常用的几种代表性的网络接口芯片应用特点的基础上,以集成全硬件TCP/IP协议栈的嵌入式以太网控制器W5500芯片为例,介绍在遥测终端机中集成W5500芯片的应用设计与技术思路,分析其结构特点、接入方式、软件驱动库和使用方法,阐述遥测终端机的几种常用网络通信业务应用方式。通过在遥测终端机内嵌W5500以太网控制芯片,移植驱动库,利用其提供的符合BSD Socket(伯克利套接字)的应用编程接口,开发人员不需要了解TCP/IP协议的细节,就可以与远端建立Socket连接进行通信,使得终端机可以接入以太网中,作为其中的一个节点,建立起丰富的网络应用。

矿山钻孔救援探测机器人设计

基于矿山钻孔救援探测需求,针对现有探测机器人信息探测范围窄、探测距离较短、功能单一、无越障能力等问题,设计了一种矿山钻孔救援探测机器人。该机器人能够通过Φ225mm救援钻孔到达煤矿井下,利用携带的传感器和摄像头获取灾变区域的环境信息和被困人员信息,并将信息实时传到地面;以NImyRIO作为控制核心,采用LabVIEW图形化编程构建控制系统,利用有线通信方式实现机器人在灾变区域内的数据远程控制。试验结果表明:该机器人运动性能良好,具有体积小、质量轻、越障能力强等特点,可顺利通过救援孔,能够对井下环境信息进行实时检测和传输,为地面救援指挥中心决策提供了第一手资料。

煤矿井下钻进钻孔随钻测量技术研究进展

在国内外随钻测量技术研究的基础上,分析和总结了煤矿井下随钻测量技术的工作原理及分类,根据信息传输介质的不同,将其分成有线式和无线式两类。基于技术发展和现场应用现状,对煤矿井下随钻测量技术的发展趋势进行了展望,认为无线随钻测量技术将是未来煤矿井下随钻测量技术的发展方向。

汽车诊断技术概述

CAN总线被广泛应用于汽车通信。随着汽车电控系统结构的日益复杂,电子系统出现故障的可能性也相对增加,同时对故障发生原因也变得越来越困难,从而极大影响了客户的用车体验。本文以汽车诊断仪为研究对象,分别介绍有线式诊断仪、无线式近距离诊断仪和无线远程式诊断仪技术路线所需要的硬件设备和优缺点,并进一步分析汽车诊断技术未来发展趋势。

INCREMENTAL AUGMENT ALGORITHM BASED ON REDUCED Q-MATRIX

Reduced Q-matrix （Qr matrix） plays an important role in the rule space model （RSM） and the attribute hierarchy method （AHM）. Based on the attribute hierarchy, a valid/invalid item is defined. The judgment method of the valid/invalid item is developed on the relation between reachability matrix and valid items. And valid items are explained from the perspective of graph theory. An incremental augment algorithm for constructing Qr matrix is proposed based on the idea of incremental forward regression, and its validity is theoretically considered. Results of empirical tests are given in order to compare the performance of the incremental augment algo-rithm and the Tatsuoka algorithm upon the running time. Empirical evidence shows that the algorithm outper-forms the Tatsuoka algorithm, and the analysis of the two algorithms also show linear growth with respect to the number of valid items. Mathematical models with 10 attributes are built for the two algorithms by the linear regression analysis.

Operator Matrix Forms of Positive Operators

If a 3-tuple (A:H_1→H_1,B:H_2→H_1,C:H_2→H_2) of operators on Hilbert spaces is given,we proved that the operator A:= on H=H_1⊕H_2 is≥0 if and only if A≥0,R(B) R(A1/2)and C≥B~* A^+ B, where A^+ is the generalized inverse of A. In general,A^+ is a closed operator,but since R(B) R(A1/2),B~* A^+ B is bounded yet.

Effects of Gully Erosion and Gully Filling on Soil Degradation in the Black Soil Region of Northeast China

Gully erosion has caused soil degradation and even reduced soil productivity. However, only few studies on the effects of gully erosion and artificial controlling measures on soil degradation in the Black Soil Region of Northeast China are available. Thus, this study explores the relationships between gully erosion, gully filling and soil parameters. Two sets of soil samples were collected in the field at： （1） 72 sample points in the gully erosion study area, 60 sample points in the ephemeral and classical gully erosion area （3,518 m2）, 12 sample points in the deposition zone （443 m2）, （2）1o reference points along a slope unaffected by gully erosion representing the original situation before the gully was formed. All soil samples were analyzed for gravel content （GC）, soil organic matter （SOM）, total nitrogen （TN）, available nitrogen （AN）, available phosphorus （AP）, and available potassium （AK）. The soil property values on unaffected slope were fitted by the polynomial curves as the reference values in no gully erosion area. The interpolated soil property values in gully eroded study area were compared with these polynomial curves, respectively, and then, changes of soil property values were analyzed. Gully erosion caused an increase in GC and a decrease in SOM, TN, AN, AP and AK. The change of GC, SOM, TN, AN, AP, AK was 8.8%, -9.04 g kg-1, -0.92 g kg-1, -62.28 mg kg-1, -29.61 mg kg% -79.68 mg kg-1. The soil property values in the study area were below optimal values. Thus, we concluded that gully erosion and gully filling caused both on-site and off-site soil degradation. Soil degradation area was 0.65 % of the cultivated land. In addition, it was proved that gully filling were an improper soil and water conservation measure, which seems to exacerbate the problem. Thus, it is suggested that soil where soil is deep is moved to fill the gully, and then the area around the filled gullies should be covered by grass for preventing the formation and development of the gully.

Case Study on Hybrid Business Model： KT＇s Olleh TV Skylife

This paper aims to analyze a case of a telecom operator, Korea Telecom （KT）＇s hybrid business model---Olleh TV Skylife （OTS）. This case is KT＇s new hybrid network and set-top-box （STB） which combines Internet Protocol TV （IPTV） with Direct-To-Home （DTH） satellite reception and business. It serves now as a guideline to better understanding hybrid consumer behavior and their needs. This paper shows how KT＇s OTS has been formulated as a new business model, how it has changed the market structure, and how it has experienced a successful market performance with new business idea and innovative technology. Before analyzing this case, it firstly discusses about the technological situation and the industrial organization （IO） theory. After this, it shows the previous service offerings of cable TV, satellite TV, and IPTV, before launching OTS and shows that the mixed service portfolio of satellite TV and IPTV is the perfect service combination to beat the cable TV in terms of hybrid consumer needs. After explanation about OTS, this paper verifies whether this hybrid business model really changes market and generates a good market performance and operating synergy with KT＇s other businesses of content, network, and marketing. In conclusion, this paper expects future growth potential of OTS and KT Skylife in terms of subscription fee, home shopping, and advertising sales based on the total subscriber base.

Pitfalls in Identity Based Encryption Using Extended Chebyshev Polynomial

Chebyshev polynomials are used as a reservoir for generating intricate classes of symmetrical and chaotic pattems, and have been used in a vast anaount of applications. Using extended Chebyshev polynomial over finite field Ze, Algehawi and Samsudin presented recently an Identity Based Encryption （IBE） scheme. In this paper, we showed their proposal is not as secure as they chimed. More specifically, we presented a concrete attack on the scheme of Algehawi and Samsudin, which indicated the scheme cannot be consolidated as a real altemative of IBE schemes since one can exploit the semi group property （bilinearity） of extended Chebyshev polynomials over Zp to implement the attack without any difficulty.

Analyzing Parabolic Profile Path for Underwater Towed-Cable

This article discusses the dynamic state analysis of underwater towed-cable when tow-ship changes its speed in a direction making parabolic profile path. A three-dimensional model of underwater towed system is studied. The established governing equations for the system have been solved using the central implicit finite-difference method. The obtained difference non-linear coupled equations are solved by Newton＇s method and satisfactory results were achieved. The solution of this problem has practical importance in the estimation of dynamic loading and motion, and hence it is directly applicable to the enhancement of safety and the effectiveness of the offshore activities.

Fault Attacks on Hyperelliptic Curve Discrete Logarithm Problem over Finite Fields

In this paper, we present two explicit invalid-curve attacks on the genus 2 hyperelliptic curve over a finite field. First, we propose two explicit attack models by injecting a one-bit fault in a given divisor. Then, we discuss the construction of an invalid curve based on the faulted divisor. Our attacks are based on the fact that the Hyperelliptic Curve Scalar Multiplication (HECSM) algorithm does not utilize the curve parameters and We consider three hyperelliptic curves as the attack targets. For curve with security level 186 (in bits), our attack method can get the weakest invalid curve with security level 42 (in bits); there are 93 invalid curves with security level less than 50. We also estimate the theoretical probability of getting a weak hyperelliptic curve whose cardinality is a smooth integer. Finally, we show that the complexity of the fault attack is subexponential if the attacker can freely inject a fault in the input divisor. Cryptosystems based on the genus 2 hyperelliptic curves cannot work against our attack algorithm in practice.

Low Distortion 1.31μm AlGaInAs/InP MQW DFB Laser Module for CATV Systems

A high power and low distortion 1.31 μm AlGaInAs/InP multiquantum well distributed feedback laser diode (MQW DFB LD) with RWG structure has been developed by MOCVD technique. The fiber output power of butterfly packaged module with optic isolator P f is more than 10 mW, threshold current is in the range of (13～20) mA, slope efficiency, E s>0.30 W/A and side mode suppression ratio, R S,M,S >35 dB. The composite second order, O C,S <-61 dBc and composite triple beat, B C,T <-65 dBc are obtained by test frequencies of (45～550) MHz with 60 PAL channels. In the test conditions the carrier to noise ratio, R C,N >51 dB.

Three-Step Difference Scheme for Solving Nonlinear Time-Evolution Partial Differential Equations

In this paper, a special three-step difference scheme is applied to the solution of nonlinear time-evolution equations, whose coefficients are determined according to accuracy constraints, necessary conditions of square conservation, and historical observation information under the linear supposition. As in the linear case, the schemes also have obvious superiority in overall performance in the nonlinear case compared with traditional finite difference schemes, e.g., the leapfrog(LF) scheme and the complete square conservation difference(CSCD) scheme that do not use historical observations in determining their coefficients, and the retrospective time integration(RTI) scheme that does not consider compatibility and square conservation. Ideal numerical experiments using the one-dimensional nonlinear advection equation with an exact solution show that this three-step scheme minimizes its root mean square error(RMSE) during the first 2500 integration steps when no shock waves occur in the exact solution, while the RTI scheme outperforms the LF scheme and CSCD scheme only in the first 1000 steps and then becomes the worst in terms of RMSE up to the 2500th step. It is concluded that reasonable consideration of accuracy, square conservation, and historical observations is also critical for good performance of a finite difference scheme for solving nonlinear equations.

IMPLICITIZATION USING UNIVARIATE RESULTANTS

Among several implicitization methods, the method based on resultant computation is a simple and direct one, but it often brings extraneous factors which are difficult to remove. This paper studies a class of rational space curves and rational surfaces by implicitization with univaxiate resultant computations. This method is more efficient than the other algorithms in finding implicit equations for this class of rational curves and surfaces.

Traveling Wave Solutions for Nonlinear Differential-Difference Equations of Rational Types

Differential-difference equations are considered to be hybrid systems because the spatial variable n is discrete while the time t is usually kept continuous.Although a considerable amount of research has been carried out in the field of nonlinear differential-difference equations,the majority of the results deal with polynomial types.Limited research has been reported regarding such equations of rational type.In this paper we present an adaptation of the(G /G)-expansion method to solve nonlinear rational differential-difference equations.The procedure is demonstrated using two distinct equations.Our approach allows one to construct three types of exact traveling wave solutions(hyperbolic,trigonometric,and rational) by means of the simplified form of the auxiliary equation method with reduced parameters.Our analysis leads to analytic solutions in terms of topological solitons and singular periodic functions as well.

Penetration of disk fragments following impact on thin plate

To investigate the ballistic resistance and failure pattern of aeroengine casing following the impact of disk fragments, and to determine the optimum case structure, the phenomena of a 1/3rd disk fragment impact on single and double-layered thin plate targets were simulated using nonlinear dynamical analysis software MSC.Dytran. Strain rate effect was introduced in a Johnson-Cook (JC) material model for the disk fragment and the plate. Impact modeling was based on the Arbitrary Lagrange-Eulerian method, and simulated using explicit finite element method (FEM). Simulation results showed that the major failure pattern of the plate is shearing and tensile fracture with large plastic deformation. It was also concluded that the ballistic limit velocity increases with the standoff distance when it is beyond a certain value, and that greater resistance is obtained when the front plate has either a proportionately low or high thickness. The impact resistance of a double-layered plate may exceed that of a single plate if the thicknesses and standoff distance of the two plates are set appropriately.

A large-scale wave-current coupled module with wave diffraction effect on unstructured meshes

Based on the extended mild-slope equation,a large-scale wave module is developed.By combining the eikonal equation and the modified wave action equation,the wave model can account for diffraction in most situations such as in the lee of islands and breakwaters,and using unstructured meshes provides great flexibility for modelling the wave in the complex geomorphology of barriers and islands,also allowing for refinement of the grid resolution within computationally important domains.The numerical implementation of the module is based on the explicit second-order upwind finite-volume schemes in geographic space,the Flux-Corrected Transport(FCT)algorithm in frequency space and the implicit Crank-Nicolson method in directional space.The three-dimensional hydrodynamic module is then modified to couple with the wave model,where the wave readily provides the depth-dependent radiation stress and the wave-induced turbulence coefficient for the current fields,and the wave propagation takes into account the current-induced advection,refraction and diffraction of wave energy and the effect of water level.The applicability of the proposed model to calculate Snell’s Law,wave transformation over the breakwaters and the elliptic shoal,wave propagation over the rip current field and the undertow on a sloping beach is evaluated.Numerical results show that the present model makes better predictions of the near-shore wave propagation and complex three-dimensional(3D)near-shore circulation driven by the waves,considering analytical solutions and experimental values.

Initial-boundary value problem of three phase flow in porous media

We study the mathematical model of three phase compressible flows through porous media. Under the condition that the rock, water and oil are incompressible, and the compressibility of gas is small, we present a finite element scheme to the initial-boundary value problem of the nonlinear system of equations, then by the convergence of the scheme we prove that the problem admits a weak solution.