Feasibility study of the transient electromagnetic method for chamber blasting misfire detection and recognition

In this paper, transient electromagnetic method was used to carry out the feasibility study on the de- tection and recognition of chamber blasting misfire. Firstly, an electromagnetic background field was estab- lished in the test; secondly, a benign conductor was preset in the chamber, and then the background field was eliminated after the electromagnetic field was measured; thirdly, the transient electromagnetic field was mea- sured again after blasting; at last, the chamber blasting misfire was detected and recognized by comparing the change of eddy current field of the preset benign conductor before and after blasting. The test results showed that： When the buried depth of aluminum box target was no more than 30 m, transient electromagnetic method can clearly identify the position of the aluminum box; when the buried depth of aluminum box was more than 30 m, the buried depth and position of the aluminum box was not sure due to the unknown level of secondary eddy current field generated by aluminum box     

An effective absorbing boundary algorithm for acoustical wave propagator

In this paper,Berenger's perfectly matched layer(PML)absorbing boundary condition for electromagnetic waves is introduced as the truncation area of the computational domain to absorb one-dimensional acoustic wave for the scheme of acoustical wave propagator(AWP).To guarantee the efficiency of the AWP algorithm,a regulated propagator matrix is derived in the PML medium.Numerical simulations of a Gaussian wave packet propagating in one-dimensional duct are carried out to illustrate the efficiency of the combination of PML and AWP.Compared with the traditional smoothing truncation windows technique of AWP,this scheme shows high computational accuracy in absorbing acoustic wave when the acoustical wave arrives at the computational edges.Optimal coefficients of the PML configurations are also discussed.     

An effective absorbing boundary algorithm for acoustical wave propagator

In this paper, Berenger’s perfectly matched layer (PML) absorbing boundary condition for electromagnetic waves is introduced as the truncation area of the computational domain to absorb one-dimensional acoustic wave for the scheme of acoustical wave propagator (AWP). To guarantee the efficiency of the AWP algorithm, a regulated propagator matrix is derived in the PML medium. Numerical simulations of a Gaussian wave packet propagating in one-dimensional duct are carried out to illustrate the efficiency of the combination of PML and AWP. Compared with the traditional smoothing truncation windows technique of AWP, this scheme shows high computational accuracy in absorbing acoustic wave when the acoustical wave arrives at the computational edges. Optimal coefficients of the PML configurations are also discussed.     

Design and Manufacture of a Wax Injection Tool for Investment Casting Using Rapid Tooling

A rapid wax injection tool of a gearbox shift fork was designed, simulated, and manufactured using rapid prototyping and rapid tooling technology to save time and cost of producing wax models used for the investment casting process. CAE simulation softwares, in particular, MoldFlow, are used to get wax injection moulding parameters such as filling parameters, temperature profiles, freeze time, speed, and pressure. The results of this research were compared with conventional wax model production methods. The criteria of such comparison were based upon parameters such as time, cost, and other related characteristics, which resulted in saving of 50% in time and 60% in cost. In this research, design, assembly, and wax injection operation of the wax tool took 10 days. Considering the fact that wax melting temperature is as low as 70℃ and injection pressure of 0.5 MPa, the tool suffers no damage due to the thermal and pressure stresses, leading to the mass production of wax models.     

塑性应变和成型温度对低碳钢磁性能的影响

Claw poles are a key component of automobile generators. The output power performance of the generator is very dependent on the magnetic properties of its claw poles. Plastic deformation is known to significantly change the magnetic behavior of ferromagnetic materials in claw poles. In this paper, changes in the magnetic properties of low-carbon steel, used for claw pole components due to their plastic deformation, were investigated for different strains and temperatures. Ring-shaped material samples were prepared by machining and their magnetic properties were measured. The surface roughness was first evaluated and a machining process with an arithmetic average of roughness Ra 1.6 μm was selected as enabling the lowest measurement error. Hysteresis loops at different applied magnetic fields of the material were obtained for different plastic strains and forming temperatures. The magnetic parameters of magnetic flux density, coercivity, and remanence were obtained and compared with magnetic flux density as the primary focus. Results showed that machining, cold forming, and hot forming all led to lower magnetic flux density, larger coercivity, and smaller remanence. Magnetic flux density showed a sharp decrease at the start of plastic deformation, but as the strain increased, the decreasing trend gradually reached a constant value. The decrease was much larger for cold forming than for hot forming. For example, at 500 A/m, the degradation of magnetic flux density with a reduction percentage of 5% at room temperature was about 50%, while that of hot forming at 1200°C was about 10%. Results of this research may provide a reference for the future process design of hot-forged claw poles.     

A Proposal for the International Cooperation of Mangrove Ecosystem Studies in Guangxi of China

In the present paper,the situations concerning mangroves in Guangxi,China werereviewed with focus on resources,scientific research and natural conservation.The urgentproblems,related to coastal mangroves,were given out as some research projects for theconsiderations of foreign scientists and managers.On this basis,a favourable local study site ofmangrove ecosystem was introduced in detail.     

Effect of plastic strain and forming temperature on magnetic properties of low-carbon steel

Claw poles are a key component of automobile generators. The output power performance of the generator is very dependent on the magnetic properties of its claw poles. Plastic deformation is known to significantly change the magnetic behavior of ferromagnetic materials in claw poles. In this paper, changes in the magnetic properties of low-carbon steel, used for claw pole components due to their plastic deformation,were investigated for different strains and temperatures. Ring-shaped material samples were prepared by machining and their magnetic properties were measured. The surface roughness was first evaluated and a machining process with an arithmetic average of roughness Ra 1.6 μm was selected as enabling the lowest measurement error. Hysteresis loops at different applied magnetic fields of the material were obtained for different plastic strains and forming temperatures. The magnetic parameters of magnetic flux density, coercivity, and remanence were obtained and compared with magnetic flux density as the primary focus. Results showed that machining, cold forming, and hot forming all led to lower magnetic flux density, larger coercivity, and smaller remanence. Magnetic flux density showed a sharp decrease at the start of plastic deformation, but as the strain increased, the decreasing trend gradually reached a constant value. The decrease was much larger for cold forming than for hot forming. For example, at 500 A/m, the degradation of magnetic flux density with a reduction percentage of 5% at room temperature was about 50%, while that of hot forming at 1200℃ was about 10%. Results of this research may provide a reference for the future process design of hot-forged claw poles.     

Accuracy Analysis of Assembly Success Rate with Monte Carlo Simulations

Monte Carlo simulation was applied to Assembly Success Bate (ASK) analyses. ASR of two peg-in-hole robot assemblies was used as an example by taking component parts' sizes, manufacturing tolerances and robot repeatability into account. A statistic arithmetic expression was proposed and deduced in this paper, which offers an alternative method of estimating the accuracy of ASR, without having to repeat the simulations. This statistic method also helps to choose a suitable sample size, if error reduction is desired. Monte Carlo simulation results demonstrated the feasibility of the method.     

Dynamic response of jetting and cementing bucket platform to wave and current loading

The jetting and cementing bucket platform （JCBP） is a new type offshore oil-drilling platform. This paper aims to establish an analysis method for calculating the dynamic response of this platform. Based on the theory of elastic half space, the dynamic stiffness and damping of the platform＇ s foundation were obtained and attached to the end of the platform＇ s main jackets as a boundary condition. Then using finite element method （FEM）, the dynamic response of the platform due to wave and current loading was calculated. Furthermore, the whole platform＇ s finite element model was established and the dynamic response of the platform was calculated. The numerical results demonstrate that the present method by the usage of elastic half space theory and FEM is simple and it is reliable and efficient to calculate dynamic behavior of the platform in response to wave and current loading.     

Classification and Assessment of Freeze-Thaw Erosion in Tibet, China

Based on the analysis of existing relevant research result, a theoretical basis for the defining freeze-thawerosion zones of Qinghai-Tibet Plateau was been put forward, and a equation for calculating the altitude of the lower bound of the freeze-thaw erosion zones of Qinghai-Tibet Plateau was been established in this paper. Moreover, the freeze-thaw erosion zones in Tibet was been identified by using Geographical Information System (GIS) software. Next, based on thecomprehensive analysis of impact factors of freeze-thaw erosion, this paper chooses annul temperature range, slop and vegetation as three indexes, works out the criteria for relative classification of freeze-thaw erosion, and realizes the relative classification of the freeze-thaw erosion in Tibet under the support of GIS software. Then, a synthetic assessment of freeze-thaw erosion in Tibet was been done according to the relative classification result.     

基于电磁场与电磁波的教学研究

电磁场与电磁波是电气、电子信息、通信等各类专业本科学生继“电路”之后必修的一门主干课程，基于该课程的特点，结合自身多年对本门课的教学研究，本文从教学大纲的制定，理论教学手段的改进，实践教学的开展等方面进行了系统的讨论，实践证明该方法教学效果好。     

电磁波与材料相互作用探讨

 探讨了电磁波与材料相互作用,强调在现代科学研究中以Maxwell方程组为基础的电磁场理论的中心作用.以微波加热、超材料特性及超材料传感器为例,简要综述了国内外的研究现状,并介绍了云南大学信息学院在这方面的工作.     

半波损失的本质

本文分别讨论了机械波、电磁波、物质波在两种介质的分界面正入射传播时产生半波损失的本质.     

用平面波法分析矩形波导场模式理论

用平面波法分析了矩形波导场模型理论及其似输特性,有物理图谱清晰,各参量物理意义明确等优点,分析了结果同分离变量法一致。     

半波损失的本质

本文分别讨论了机械波、电磁波、物质波在两种介质的分界面正入射传播时产生半波损失的本质。     

基于Matlab的电磁场图示化教学

针对电磁场的特点,详述利用Matlab图示空间电磁场与电磁波的实例,通过形象化的场图等辅助手段,使场的概念更加清晰、直观,帮助学生理解和掌握电磁场的规律。     

驻波光场中的三能级原子

原子与光场相互作用系统是很难求解的 ,文章对三能级原子与驻波光场相互作用系统进行了深入的探讨 ,得出了三能级原子与驻波光场相互作用系统的波函数所满足的方程 ,在光场较弱的情况下 ,可以进行求解 ,并可得出系统能量的可能取值。     

三频组合波频率测深法

三频组合波频率测深法是一种频率测深新方法，发送机同时发射３种频率的电磁波，接收机每一通道同时接收３种频率的电磁场分量，同时得到３种频率的波阻抗和２个相对相位差，且发射机和接收机之间不需相位参考系统，因而具有高效、高精度和接收设备轻便等特点．三频组合波的原理适合频域中的其它电法勘探，发射机具有多功能特性，接收机能设计成地球物理数据综合采集系统，故用途广泛。     

驻波光场中的二能级原子

原子与光场相互作用系统是很难求解的 ,通过对二能级原子与驻波光场相互作用系统进行求解 ,在光场强度较弱的情况下 ,得出了二能级原子与驻波光场相互作用系统的波函数、能量的可能取值、二能级原子质心动量的可能取量。     

基于电磁波衰减和相移特性的籽棉回潮率检测方法分析

根据电磁波在不同回潮率的籽棉中传播特点,提出了通过检测电磁波在籽棉传播过程中的衰减和相移变化来检测籽棉回潮率的方法,建立了籽棉回潮率与电磁波衰减和相移变化之间的数学模型。通过该模型实现了对籽棉回潮率的无损非接触式动态实时测量,克服了传统方法测试周期长、准确率低等缺陷,同时提高了籽棉收购过程中其回潮率检测效率。