Advanced Materials Research Vol. 629

Abstract: In ultrasonic flow metering, the inner pipe wall will be distorted by transducer’s installation, and the velocity profile of the meter will be different from that in a long straight pipe located in front of or behind the meter section. Changes in profile will finally influence the flow measurement accuracy. This paper shows a multi-path ultrasonic flow meter with its transducers installed at different positions. Our purpose is to find the best transducer installation position and to study the influence of path numbers and pipe diameters on the flow measurement accuracy at the best installation position. With a computational fluid dynamics (CFD) analysis, velocity profiles are calculated. Negative bias errors are obtained at all the three of the common installation positions. Similar phenomenon has also been observed in a real field experiment. The reasons for the negative bias error have also been analyzed.

Abstract: The performances of ultrasonic testing systems are greatly affected by the impedance characteristics of ultrasonic transducers. Conventional methods for designing matching networks consider only the characteristics of matching elements and transducer, while ignoring the effects of other elements of emission circuit. As a consequence, such method cannot give out satisfactory results. In this paper, a modeling method for ultrasonic driving circuits is proposed, which takes into account the power supply, the transformer, the matching networks, as well as the ultrasonic transducer. This method focuses on the performances both in time domain and in frequency domain. A computer simulation and experiments show that this method can provide better attenuation characteristics and energy transmission, and can be widely used for analyzing and designing matching network for ultrasonic testing systems.

Abstract: A new multi-furcated structure of tree-shaped mini-channel was proposed in this paper. Numerical simulation was conducted to analyze the flow boiling and bubble growth characteristics of water in the mini-channel. By using the constant wall temperature heating method, the model was divided into different sub-regions according to different wall temperatures. Typical bubbly flow and slug flow patterns were obtained through the monitoring of the boiling process. The simulation results showed that when the convective heat transfer dominated, the pressure drop maintained minor and stable; while the nucleate boiling dominated, the pressure drop increased significantly and fluctuated within a certain range. Moreover, with the increase of vapor quality, the heat transfer coefficient increased first and then decreased. It is also found that the geometric structure of the multi-furcated tree-shaped mini-channel had a great impact on the heat transfer characteristics, and simulation results agreed well with the theoretical values.

Abstract: The entransy loss minimization approach for the heat exchanger optimization design was established by Guo Z Y; the study based Guo Z Y’s works, found relationship between the entransy loss uniformity and the heat exchanger performance and the expression of the local entransy loss rate for heat convection was derived, numerical results of the heat transfer in a chevron plate heat exchanger and helix baffle heat exchanger show that the larger entransy loss uniformity factor appear in about Re=2000 and the entransy loss uniformity factor of chevron plate heat exchanges higher than helix baffle one.

Abstract: Analyzing problems represented by partial differential equations numerically with modern high performance computers has become an important approach in research of earth science. In the work, a Sea Ice numerical Model under JASMIN (J parallel Adaptive Structured Mesh applications INfrastructure) (SIMJ for brevity) including thermodynamic and dynamic processes is implemented and an numerical experiment of 20-year integration with SIMJ has been performed. It’s found that the model can reproduce seasonal variation of Arctic sea ice well and implementation of parallel computing is flexible and easy. The ratio of time consumption is 1:1.16:1.48:2.45 with 8, 4, 2, and 1 core(s) respectively for one year integration on mobile workstation (Thinkpad W510) with Red Hat Enterprise Linux 5.4 and Portland group’s pgf90 9.0-1.

Abstract: This paper focuses on the influence of the conjugative heat transfer in a regenerative cooling structure. With proper numerical modelling by both finite element method and computational fluid dynamic method, the distribution of the temperature in the solid and coolant, the interfacial heat flux, and the stress state and the deformation of this cooling structure are obtained. These results show that the thermal equilibrium of the cooling structure can be achieved in a given flow condition. The present numerical method has significant benefits to solve the heat transfer between engine coolant and solid components.

Abstract: Many artificial neural networks are the simple simulation of brain neural network’s architecture and function. However, how to rebuild new artificial neural network which architecture is similar to biological neural networks is worth studying. In this study, a new multilayer feedforward small-world neural network is presented using the results form research on complex network. Firstly, a new multilayer feedforward small-world neural network which relies on the rewiring probability heavily is built up on the basis of the construction ideology of Watts-Strogatz networks model and community structure. Secondly, fault tolerance is employed in investigating the performances of new small-world neural network. When the network with connection fault or neuron damage is used to test the fault tolerance performance under different rewiring probability, simulation results show that the fault tolerance capability of small-world neural network outmatches that of the same scale regular network when the fault probability is more than 40%, while random network has the best fault tolerance capability.

Abstract: This paper introduces the design of a DSP-based acquisition system with high parallelism of the beam. The system uses fiber arrays connected to spatial filters as the detection devices. A TMS320LF2407A DSP is adopted as the primary embedded processor, which connects Analog to Digital (A/D) converters via I/O ports. Simultaneously, the processor realizes the parallel processing of data storage, transmission and calculation. The design of the main processor control module, the signal processing module and its corresponding software, are discussed in detail.

Abstract: Job shop scheduling problem (JSP) is the most typical scheduling problem, In the process of JSP based on genetic algorithm (GA), large amounts of data will be produced. Mining them to find the useful information is necessary. In this paper dividing, hashing and array (DHA) association rule mining algorithm is used to find the frequent itemsets which contained in the process, and extract the corresponding association rules. Concept hierarchy is used to interpret the rules, and lots of useful rules appeared. It provides a new way for JSP study.

Abstract: Based on standard minority game, an Irrationality Agent Minority Game (IAMG) model is proposed, in which agents are less rational to make use of its strategy properly at each step. The control parameter of irrationality, p_I, represents the probability of an agent acting irrationally, which could be explained with the personal defect. Like the incomplete (strategy) minority game (IMG) model introduced in our previous paper, this IAMG model also has three failsafe mode including (R0) random action, (R1) random strategy and (R4)”Back- to-Best”. The IAMG model can be explain with analytic equations similar with the IMG, and simulation results match the trend of the conclusion. Irrationality shows a great effect on system efficiency, and system efficiency reaches its top value at a smaller p_Ic than p_Ic in IMG. The IAMG and IMG model can be used to explain the deviation of some game theory simulations, and to understand the system performance with abundant agents of various characters.