[en] In order to improve the stiffness characteristics of orthopedic devices implants that mimic the mechanical behavior of bone need to be considered. With the capability of Additive layer manufacturing processes to produce orthopedic implants with tailored mechanical properties are needed. This paper discusses finite element (FE) analysis and mechanical characterization of porous medical grade cobalt chromium (CoCr) alloy in cubical structures with volume based porosity ranging between 60% to 80% produced using direct metal laser sintering (DMLS) process. ANSYS 14.0 FE modelling software was used to predict the effective elastic modulus of the samples and comparisons were made with the experimental data. The effective mechanical properties of porous samples that were determined by uniaxial compression testing show exponential decreasing trend with the increase in porosity. Finite element model shows good agreement with experimentally obtained stress-strain curve in the elastic regions. The models prove that numerical analysis of actual prosthesis implant can be computed particularly in load bearing condition (paper)

[en] A cryogenic advanced propellant loading system is currently being developed at NASA. A wide range of applications and variety of loading regimes call for the development of computer assisted design and optimization methods that will reduce time and cost and improve the reliability of the APL performance. A key aspect of development of such methods is modeling and optimization of non-equilibrium two-phase cryogenic flow in the transfer line. Here we report on the development of such optimization methods using commercial SINDA/FLUINT software. The model is based on the solution of two-phase flow conservation equations in one dimension and a full set of correlations for flow patterns, losses, and heat transfer in the pipes, valves, and other system components. We validate this model using experimental data obtained from chilldown and loading of a cryogenic testbed at NASA Kennedy Space Center. We analyze sensitivity of this model with respect to the variation of the key control parameters including pressure in the tanks, openings of the control and dump valves, and insulation. We discuss the formulation of multi-objective optimization problem and provide an example of the solution of such problem. (paper)

[en] In order to produce pulsed electron beam with the energy of 17.5 GeV, the European X-ray Free Electron Laser (XFEL) linear accelerator is under construction. The XFEL accelerator will contain the linear accelerator (linac) and the injector. The XFEL cryogenic distribution system supplies the linac and the injector with cooling helium. The cryogenic supply of the linac is separated in parallel cryogenic sections called ‘strings’.Operation of the XFEL cryogenic distribution system is under the process control system for Experimental Physics and Industrial Control System (EPICS). A complementary component of EPICS is the Open Source software suit CSS (Control System Studio) providing an integrated engineering, maintenance and operating tools for EPICS as well as human machine interface. Cryogenic instrumentation used for operation and diagnostic is connected to PROFIBUS. More than 300 PROFIBUS nodes control the XFEL cryogenic system. DESY introduced the monitoring system based on Field Device Tool (FDT). FDT framework contains Data Tool Management (DTM) applications to examine the correct installation and configuration of all PROFIBUS nodes in real time.This paper describes the control system for the XFEL cryogenic distribution system including all steps from engineering to the pre-service tests. (paper)

[en] This paper is intended to show that Petri nets can be also applicable in the chemical industry. It used linear programming, modeling underlying Petri nets, especially discrete event systems for isotopic separation, the purpose of considering and control events in real-time through graphical representations. In this paper it is simulate the control of "1"3C Isotope Separation column using Petri nets. The major problem with "1"3C comes from the difficulty of obtaining it and raising its natural fraction. Carbon isotopes can be obtained using many methods, one of them being the cryogenic distillation of carbon monoxide. Some few aspects regarding operating conditions and the construction of such cryogenic plants are known today, and even less information are available as far as the separation process modeling and control are concerned. In fact, the efficient control of the carbon monoxide distillation process represents a necessity for large-scale "1"3C production. Referring to a classic distillation process, some models for carbon isotope separation have been proposed, some based on mass, component and energy balance equations, some on the nonlinear wave theory or the Cohen equations. For modeling the system it was used Petri nets because in this case it is deal with discrete event systems. In use of the non-timed and with auxiliary times Petri model, the transport stream was divided into sections and these sections will be analyzed successively. Because of the complexity of the system and the large amount of calculations required it was not possible to analyze the system as a unitary whole. A first attempt to model the system as a unitary whole led to the blocking of the model during simulation, because of the large processing times. (paper)

[en] A study of geometry nozzle is particularly important in optimizing the quantity of coolant in terms to minimize that quantity or coolant can be used for lubrication of machines moving parts. Coolants can be from the simplest (water, air) as well as a mixture of liquid (emulsions) to achieve a good cooling in function of temperature that develops in the area concerned. The study from this paper proposes an analysis and a simulation of flow through the convergent-divergent nozzle type to optimize them and to use a minimum quantity of coolant or lubricant. This study is focus on the analysis of cooling systems for cutting processes on machine tools. (paper)

[en] The ultrasonic nondestructive evaluation of structural integrity of pipes in high risk industries such as chemical or nuclear, represents a domain of highest importance. The inspection of kilometers of piping in rough conditions is a difficult if not an impossible task. Guided ultrasonic waves can propagate however along tens of meters in pipes and bring by the reflected signal, important information concerning the presence of flaws. There are three classes of guided modes in a pipe: longitudinal, torsional and flexural. The longitudinal modes have an axial symmetry of the radial and axial displacements. These waves prove to be most sensitive to partly circumferential flaws. These waves are dispersive, the wave velocity strongly depending on the frequency. The torsional modes are less dispersive, especially the fundamental SH_0 mode. Moreover, the radial displacements are negligible, reducing the interaction with the surrounding fluids and thus reducing the attenuation. The interaction of these waves with axial flaws is more pronounced. The flexural modes are highly dispersive and attenuated. However, if the symmetry of the emitting transducer is not perfect, these modes can propagate in the pipe and their properties must be understood. The presence of fluid inside and in some cases outside the inspected pipe represents a challenging problem of computing the guided modes dispersion curves. The various guided modes velocities and attenuations are determined for several fluids which might be filling and surrounding the common size steel pipes. A dedicated software package developed by our team is used for this purpose. These dispersion curves are used for optimal numerical simulation, using the Finite Elements Method (FEM), in order to verify the attenuation mechanism. The obtained results allow a motivated selection of the least attenuated mode, from the three classes explained before, at a given inspection frequency and for a typical steel pipe, filled with various fluids. The numerical data can be used for comparison with laboratory experiments. The experimental setup is using common ultrasonic transducers in a special geometrical arrangement. The experiments allow the measurement of the numerically predicted modal attenuation. The maximum expected inspection range can be thus determined before the inspection on real industrial piping. (paper)

[en] The derivation of the equation for the calculation of the critical size of clusters and nanoparticles in the range of appearing of their unusual properties in comparison with the massive body as well as the equation for the calculation of the growth of spherical crystallites and aggregations is presented in the article. (paper)

[en] This article presents the results of numerical simulation of dynamic behaviour of welded metal beams in conveyor galleries. Investigations were carried out for the beams having symmetrical cross-sections and evenly-spaced transversal ribs with various spacing between the ribs in different beams. The regularities of changes in the vibration mode shapes depending on the beam geometric characteristics have been investigated. (paper)

[en] The current commercial use of electron accelerators grows in research, industry, medical diagnosis and treatment. Due to this fact, the creation of a model describing the electron beam profile and shape is an actual task. The model of the TPU microtron extracted electron beam created in the program “Computer Laboratory (PCLab)” is described and compared with experimental results in this article. The value of the internal electron beam divergence determination is illustrated. The experimental data of the electron beam profiles at the selected distances from the output window are analysed and compared with the simulation data. The simulation data of the electron beam profiles are shown. (paper)

[en] Aluminum nitride is widely-used material for semiconductor devices and ceramics production. Despite the large number of known ways to obtain AlN powder, the problem of synthesizing high-purity and nanosized product is still urgent. This paper shows results on plasma dynamic synthesis of aluminum nitride using system based coaxial magneto plasma accelerator. The influence of using gaseous or solid precursors on such characteristics of the final product as phase content and particle size distribution was investigated. According to X- Ray diffractometry AlN phase content is increased in the case of use of solid nitrogen- containing precursor (melamine) in comparison with the use of gaseous nitrogen. The particle sizes distribution histograms are built in accordance with the data of bright-field TEM-images and shown in this paper. The most of particles are less than 100 nm in both experiment but there are some differences, depended on the precursor type, that are also described. (paper)