Boundary Galerkin's method for three-dimensional finite element electromagnetic field computation

Electromagnetic field problems are often formulated as boundary value problems in unbounded regions. For this reason, the application of conventional numerical methods, such as the finite element method, is difficult. The paper describes a new technique to circumvent this difficulty. The technique is based on the reduction of the field equations in unbounded space to equivalent boundary Galerkin's criterion. Such criterion can be combined with the volume Galerkin's criterion for regions occupied by conductors. A new quasi-finite-element discretization based on the coupled boundary/volume Galerkin's criterion is presented.     

Bayesian estimation of motion vector fields

A stochastic approach to the estimation of 2D motion vector fields from time-varying images is presented. The formulation involves the specification of a deterministic structural model along with stochastic observation and motion field models. Two motion models are proposed: a globally smooth model based on vector Markov random fields and a piecewise smooth model derived from coupled vector-binary Markov random fields. Two estimation criteria are studied. In the maximum a posteriori probability (MAP) estimation, the a posteriori probability of motion given data is maximized, whereas in the minimum expected cost (MEC) estimation, the expectation of a certain cost function is minimized. Both algorithms generate sample fields by means of stochastic relaxation implemented via the Gibbs sampler. Two versions are developed: one for a discrete state space and the other for a continuous state space. The MAP estimation is incorporated into a hierarchical environment to deal efficiently with large displacements     

Start-up phase of the HELOKA-LP low pressure helium test facility for IFMIF irradiation modules

As part of the Engineering Validation and Engineering Design Activities (EVEDA) for the International Fusion Materials Irradiation Facility (IFMIF) [1], it is foreseen to design and test a 1:1 scale prototype of the IFMIF High Flux Test Module (HFTM) [2]. The module has been designed to be cooled by a low pressure helium gas flowing through minichannels to remove the nuclear heat.The Helium Loop Karlsruhe-Low Pressure (HELOKA-LP) has been designed to provide coolant at 1:1 HFTM operational conditions: massflow 12–120 g/s, inlet pressure 0.3–0.6 MPa, inlet temperature RT – 250 °C. A secondary objective is to use the experience gained with HELOKA-LP for the planning of the IFMIF helium cooling system.The facility has been put into operation in 2009, and has since then been in a test and optimization phase. It was proven, that the above mentioned requirements for the facility are achieved. The paper describes the process layout and components of the facility. The performance is characterized by the results of several steady state and transient benchmark tests. Typical start-up and transition times relevant for the operation mode in the IFMIF irradiation campaigns are obtained. Additionally first results on the impurity ingress and the cooling gas chemistry are described.     

Yielding of Microstructured Geomaterial by Distinct Element Method Analysis

The purpose of this paper is to present macro- and micro-study on the yielding of microstructured geomaterials by numerical experiments. This target is achieved by carrying out 63 one-dimensional and biaxial compressions tests on an idealized bonded geomaterial with an extension of distinct element method, into which bond contact models proposed were implemented. Numerical results indicate that: (a) preconsolidated pressure appears to attribute to bond and looseness in the geomaterials, and an increase in void ratio leads to a decrease in yielding stress in one-dimensional tests; (b) an increase in bonding strength at interparticle contacts results in an increase in yielding stress and cohesion, and an internal friction angle that is smaller than the critical state value; (c) the observed first-yielding (initiation of bond breakage) is stress path dependent, and gross-yield (defined with respect to volumetric strain) of microstructured geomaterials is evidently related to bond breakage.     

Real-time automated risk assessment in protected core networking

Protected Core Networking (PCN) is an approach to creating a secure and flexible network and communications infrastructure that supports network enabled capability (NEC) operations. The real-time automated risk assessment (R-TARA) provides a theoretically and practically sound method for risk assessment in the Protected Core. The purpose of the R-TARA is multifold. On the one hand it provides a global metric, which could be used by the network operator to assess the overall security level of the network and its evolution over time. On the other hand, the results of R-TARA can be used in order to achieve dynamic accreditation. Finally, R-TARA local risk metrics, e.g. susceptibility to DoS attacks, can be used for dynamic routing decisions. We propose use of Bayesian networks, known from operational risk assessment, for PCN risk assessment and we provide analytical and simulative evaluation of R-TARA mechanisms.     

Three-dimensional finite element computation of laser cavity eigenmodes [corrected

A new method for computing eigenmodes of a laser resonator by the use of finite element analysis is presented. For this purpose, the scalar wave equation (delta + k2)E(x, y, z) = 0 is transformed into a solvable three-dimensional eigenvalue problem by the separation of the propagation factor exp(-ikz) from the phasor amplitude E(x, y, z) of the time-harmonic electrical field. For standing wave resonators, the beam inside the cavity is represented by a two-wave ansatz. For cavities with parabolic optical elements, the new approach has successfully been verified by the use of the Gaussian mode algorithm. For a diode-pumped solid-state laser with a thermally lensing crystal inside the cavity, the expected deviation between Gaussian approximation and numerical solution could be demonstrated clearly.     

集成了网络连接的低成本控制器

按照当前的技术水准，如果设计一个不与网络或互联网连接的控制、调节或数据通信系统显然是落伍了。文中将介绍如何采用Maxim／Dalias创新的八位网络微控制器DS80C400实现低成本的具有WEB连接的工业应用。     

Über die Kinetik der Oxydation und Reduktion von Wüstit innerhalb seines Existenzgebietes

Abhängigkeit der Sauerstoffaktivität des Wüstits von seiner Zusammensetzung. Gravimetrische Messungen zur Abhängigkeit der Oxydations- und der Reduktionsgeschwindigkeit des Wüstits von seiner Sauerstoffaktivität in H₂O/H₂- und CO₂/CO-Gemischen.     

Numerical Determination of Secondary Dendrite Arm Spacing for IN738LC Investment Castings

A numerical model was developed to estimate the solidification conditions and the secondary dendrite arm spacing of equiaxed solidified IN738LC investment castings. The model, composed of geometric data, thermophysical properties, and boundary conditions, was verified by a comparison of calculated and measured process temperatures obtained from casting experiments. The computation of the secondary dendrite arm spacing was carried out from temperature gradient G, solidification rate v, and an alloy-specific parameter M, determined by means of an inverse approach. The calculated secondary dendrite arm spacing was found to be in very good agreement with metallographic measurements.