Applied Mechanics and Materials Vols. 764-765

Abstract: This paper presents an analysis of a new type of permanent magnet excited transverse flux linear synchronous motor (PMTFLSM). This linear motor achieves a high thrust from its novel design and fabric. Its translator consists of cross-shaped core sets. Considering parameters such as magnet dimension, pole pitch, and tooth width of the translator, the effected thrust is analyzed and simulated with a 2D model of our PMTFLSM using the finite element method. Extensive simulations were conducted to investigate how the motor performs under a variety of parameter settings. Accordingly, motor characteristics are identified whereby an optimal combination of parameter values can be found. The new findings are then fed back to our motor design to validate performance improvement.

Abstract: This study investigates numerically the NOx reduction by SNCR in a CO boiler. The combustion and fluid flow in the FPC CO boiler is examined with emphasis on the influence of the injection position of reducing agent on NOx reduction. Simulation results indicate that NOx is formed mainly in the high temperature region near the boiler inlet where the mixing caused by swirler is strong. Among the reducing agent injection positions investigated, the boiler inlet has the best NOx reduction efficiency, while 0.5m behind the boiler inlet is the worst. When reducing agent is injected from the boiler inlet, a NOx reduction efficiency of 51% is achieved if default amount of reducing agent is injected. When reducing agent is injected from 3.6m behind the boiler inlet, the NOx reduction efficiency is 14% for default amount of reducing agent. The injection position of reducing agent has a siginificant influence on the NOx reduction efficiency. Better injection positions for NOx reduction should be where reducing agent can pass through a region where temperature is suitable for the SNCR reaction or residence time of reducing agent in the SNCR reaction region can be longer, e.g., the boiler inlet or the downstream region of the oxidizer lower portion where recirculation exists.

Abstract: In recent decades environmental pollution and energy crisis have become a challenging task for the scientists and engineers who lead them to innovate new technology and solve this problem by reducing environmental pollution and by exploiting the new source of energy. In this regard wave energy is appeared to be a suitable outcome in order to resolve the current issues. This paper studies and summarizes that the linear generators are considered a device which is used to convert wave energy into electrical energy efficiently. It is the first time to calculate the electromagnetic force by considering the linear generator and at the same time simulated by Ansoft Maxwell software; by providing calculated value and simulated value, it is also verified that the calculated result is accurate with a small probability error as compared to software calculated value.

Abstract: The structural characteristics and the working principle of inertial rotary vibrating screen are introduced in this paper. The inertial rotary vibrating screen is a kind of high efficient equipment for the screening classification of dry and wet fine materials. It has the features of simple and compact structure, convenient installation and disassembly, stable work operation, no sieve pore blocking, high screening efficiency, and the whole machine closure without polluting environment. The nonlinear vibration equations of inertial rotary vibrating screen are established, considering the nonlinear forces of materials. An approximate solution and the material combination coefficient and drag coefficient for the vibration equations are solved by equivalent linearization method of nonlinear theory. A calculation example is also given in this paper.

Abstract: Real-time life prediction for rolling bearings contributes to maintenance decision-making and optimization based on the health state. Real-time life prediction based on Bayesian methods usually require that the priori distribution of the product be obtained; however, this task is extremely difficult to implement for new products or small sample sizes. To solve this problem, a nonparametric Bayesian updating method is proposed in this study. Kernel density estimation is employed to estimate the priori and posterior distribution of parameters by integrating real-time performance degradation information. Thus, bearing real-time life prediction based on nonparametric Bayesian updating is realized. In addition, this study investigates the calculation and normalization process of the working condition conversion factor. The effectiveness of the proposed method is verified by bearing run-to-failure experiments.

Abstract: This paper presents a compact dual-band MIMO antenna that is compatible to the IEEE 802.11n wireless LAN standards. The MIMO antenna contains two tree-type elements placed back to back with distance of one-sixth wavelength of 2.4GHz; the element in the MIMO antenna is structured with a two-branch tree-type planar inverted-L monopoles, the lengths in both branches are set to the electrical quarter-wavelength of the frequency bands of 5.2GHz and 2.4GHz respectively. The MIMO antenna characterized by small size, low mutual coupling effect and nearly omni-directional coverage in radiation pattern make it entirely applicable to the mobile wireless network applications. The measurement results of the fabricated MIMO antenna demonstrate the success of the suggested design topologies.

Abstract: In this paper, we propose a multiple objective fitness function for cognitive engines by using the genetic algorithm (GA). Specifically, we propose four single objective fitness functions, and finally, we propose a multiple objective fitness function based on the single objective fitness functions for transmission parameter optimization. Numerical results demonstrate that we can obtain transmission parameter sets optimized for given transmission scenarios with the GA-based cognitive engine incorporating the proposed objective fitness function.

Abstract: A novel algorithm for a single-phase active power filter (APF) is proposed in this paper. The proposed algorithm avoids the use of main voltage signal in the calculation of reference compensation current. Therefore, the mains current after compensation is still a pure sinusoidal waveform even when the mains voltage is distorted. A novel circuit for detecting the amplitude of the real part of the fundamental load current is not more than 1/4 cycle. Its transient response is superior to the other conventional techniques. In addition, the proposed algorithm can compensate for the power factor and suppress the harmonics of nonlinear loads. Finally, some experimental results are presented for verification.

Abstract: Cognitive radio is one of the promising techniques to solve the spectrum scarcity problem. In this paper, we propose a novel spectrum sensing scheme for cognitive radio in dynamic traffic circumstances. In the proposed scheme, a sensing period is partitioned and the final decision is obtained based on the energy detection results of each partitioned sensing period. From numerical results, it is confirmed that the proposed scheme has an improved detection performance compared with those of the conventional schemes.

Abstract: This paper presents a Radar Cross Section (RCS) reduction method for wind turbines. In the proposed method, a reshaping procedure is utilized to generate waves or bumps on the surface of the wind-turbine tower. As the tower is illuminated by electromagnetic waves, the reflected rays are perturbed by the convex structures and the RCS of the wind turbine is decreased. Test results conclude that our modeling method reduces the average RCS values. The scatterings in the directions of the convex structures are significantly declined.