Numerical study of the forming process of high frequency welded pipe

The roll forming process is applied to the manufacturing of high frequency welded (HFW) pipes,section steels,etc. In this paper,the roll forming process of the HFW pipe is simulated with the finite element method (FEM). A user-defined material routine of the commercial finite element code ABAQUS/Explicit is developed,and the mixed hardening constitution model is realized through the user-defined material routine. Based on the mixed hardening constitutive equation,the numerical simulation of roll forming pro...     

Performance research of a micro-CCHP system with adsorption chiller

This paper describes a new micro-combined cooling,heating and power(CCHP) system,which is especially suitable for domestic and light commercial applications. It mainly consists of a natural gas-fired internal combustion engine,a silica gel-water adsorption chiller and other heat recovery units. In order to study the energy effciency and economic feasibility,an experimental investigation has been carried out. The experimental system has a rated electricity power of 12 kW,a rated cooling capacity of 9 kW and a rated heating capacity of 28 kW. Evaluation and analysis of the system are discussed in detail. The testing results show that the energy effciency of the overall system depends on different modes. The overall thermal and electrical effciency is over 70%. Higher heat load supplied causes higher effciency of the system. Economic evaluation shows that the micro-CCHP system enjoys a small capital cost and short payback period,which is easily accepted by customers. At current natural gas price of 1.9 RMB/m3(nominal condition) and electric price of 0.754 RMB/(kW·h) ,the total capital cost is only 90 000 RMB with a payback period of 3.21 years.     

Effect of absorption layer on interior sound field of sonar dome

Using the finite element method (FEM) and boundary element method (BEM) and considering the sound absorption layer which is covered on the backing of the sonar dome, the interior field in the dome which is excited by the incident plane wave has been studied. This method is validated by comparing numerical results with that of classic elastic theory. Then the effect of parameters of the sound absorption layer on interior sound field has been analyzed. The numerical calculation results show that uniformity of interior sound pressure is improved when the backing is covered with a sound absorption layer. The thicker the layer is, or the higher the loss factor of layer is, the more uniform the sound field is.     

Analysis and enhancement of a watermarking protocol suitable for web context

AbstractA buyer-seller watermarking protocol is a combination of traditional watermarking and fingerprinting techniques. Recently, Frattolillo proposed such a watermarking protocol suitable for web context. Frattolillo’s scheme has two problems which would make it hard to implement practically. Several possible solutions to the two problems are presented in this paper.     

Opportunistic preventive maintenance optimization for multi-unit series systems with combing multi-preventive maintenance techniques

This paper proposes a dynamic opportunistic preventive maintenance (PM) optimization policy for multi-unit series systems by integrating multi PM techniques. Two PM techniques, periodic PM and sequential PM, are considered. Whenever one of the units reaches its reliability threshold, a PM action has to be performed on that unit. At that time the whole system has to be stopped and PM opportunities arise for the other units of the system. An optimal PM practice is determined by maximizing the short-term cumulative opportunistic maintenance (OM) cost savings for the whole system. Numerical examples are given to show how this approach works. Finally, a comparison between the proposed PM policy and the other policies is given.     

On the algorithms of adaptive neural network-based speed control of switched reluctance machines

AbstractA switched reluctance machine(SRM)drive is a time-varying,strongly nonlinear system.High performance control can no longer be achieved by using linear techniques.This paper describes the back-propagation (BP)neural network-based proportional-integral-derivative(PID)speed control of the SRM.It’s the interest of this paper to explore the utilization of the prior empirical knowledge as guidance in the initializing and training of the neural networks.The purpose is to make the networks less sensitive on the initial weights.Two modified algorithms are presented and simulation experiments show some interesting findings about their control effects and their corresponding sensitivity on the initial weights of the networks.     

3D Numerical simulation of non-isothermal resin transfer molding filling process using unstructured tetrahedron mesh

We present a numerical formulation for resin flow based on the concept of quasi-steady state situation at the flow front. To be fit for complicated product shapes, we use the four-node unstructured tetrahedron mesh based on which the numerical formulation of temperature and degree of cure is developed. The validity of our method is established in the case where flexible meshes are used. The results show that the numerical procedure, tested on known data, provides numerically valid and reasonably accurate predictions.     

Remaining Useful Life Prediction of Turbofan Engine Using Hybrid Model Based on Autoencoder and Bidirectional Long Short-Term Memory

High voltage electrostatics and corona discharge are utilized for various applications in pollution and environmental control. The traditional applications have many flaws due to improper construction of electrode design and assembly that cause system failure, in particular when electrically stimulated devices are exposed to high humidity. A new innovative-patented design by Hamade, electrically stimulated catalytic converter (ESCC), eliminates such flaws and shows the wide practical applications of the new design. The new design utilized previous patented designs and work of the same inventor but retrofitted for catalytic auto exhaust emission control. The current and previous patents include: employing electrically stimulated filtration (ESF) to replace high efficiency particulate air (HEPA) filters, treatment of biological and infectious diseases, electret fabrication, and, most notably, the invention of a new electrically stimulated catalytic converter (ESCC). The electrically stimulated catalytic converter invention includes an exhaust conduit fed from the engine exhaust port with a housed corona charger apparatus. The opposite end is opened to the atmosphere outside of the vehicle or connected to a reduced-size catalytic converter. The corona charger is intrusively or non-intrusively associated with a main flow path defined by the exhaust conduit. The corona charger includes at least one electrode, which may be recessed away from, the main flow path. A plurality of corona chargers may be used in various combinations, optimally a two dimensional grid. The electrically stimulated catalytic converter is adapted to treat and eliminate auto exhaust pollution emission to air.     

Intelligent Costume Recommendation System Based on Expert System

On the basis of expert system, we design a costume recommendation system which provides customers with clothing collocation solution and more experience. We set up a costume matching knowledge base collected from experts, and represent the knowledge with production rules. By analyzing the customers’ specific physical information got through man-machine interface, the proposed system provides customers an intelligent costume recommendation strategy in accordance with blackboard model reasoning. Moreover, index adding algorithm is integrated into the traditional serial blackboard model in the system. Finally, we present experiments which show the search rate is improved significantly.     

Impacts of CaO Solid Particles in Carbon Dioxide Absorption Process from Ship Emission with NaOH Solution

CO₂ emitted from ship exhaust is one of the major sources of atmospheric pollution. In order to reduce ship CO₂ emissions, this paper comes up with the idea of recovering CO₂ from ship exhaust by NaOH solution and improves the absorption rate by adding CaO solid particles. The effect mechanism of CaO solid particles on CO₂ absorption efficiency is analyzed in detail, and the mathematical model is deduced and the CaO enhancement factor is calculated through experiments. Experiment result demonstrates that the effect of CaO solid particles on the absorption of CO₂ in alkali solution is significant. The absorption rate of pure CO₂ gas, the simulated ship exhaust gas and 6135AZG marine diesel engine emission can be increased by 10%, 15.85% and 10.30%, respectively. So it can be seen that CaO solid particles play an important role in improving the absorption efficiency of ship CO₂ emission.