Crashworthiness analysis and optimization of fourier varying section tubes

Thin-walled structures are widely used as energy absorption devices for their proven advantages on lightweight and crashworthiness. However, a majority of studies have being focus on exploring separately the crashworthiness of the thin-walled structure with a specific geometric section, such as circular, square, hexagon, octagon etc., and little research has investigated the relationship of crashworthiness among thin-walled structures with different sections systematically. This paper utilizes Fourier series expansion to generate a series of novel sectional configurations, namely Fourier varying sectional tubes (FVSTs), to look into their advantages of crashworthiness, thereby developing some FVSTs with highest possible energy absorption capacity. Based on the validated finite element (FE) models, parametric analysis is conducted to investigate the effects of cross-sectional configuration, perimeter and thickness of FVSTs on collapse mode and energy absorption. The results showed that the collapse modes of FVSTs are fairly sensitive to cross-sectional configuration, perimeter and wall thickness. Of these FVSTs generated, the highest specific energy absorption (SEA) increases 77.54% by increasing perimeter and 69.73% by decreasing wall thickness. Finally, a discrete optimization based on the orthogonal arrays is conducted to obtain the optimal FVST for maximizing SEA under the constraint of the initial peak crushing force (IPCF). The optimized FVSTs are of superior crashworthiness and great potential as an energy absorber.     

Detection of signals of unknown duration by multiple energy detectors

An extension of the classical energy detector is proposed to deal with the case of unknown signal duration. Multiple energy detectors are applied to partitions of the original observation interval; presence of signal is decided if at least one of the detectors is in favor of it. We have derived the corresponding probabilities of false alarm and detection for a particular strategy of successive segmentations of the original interval, thus obtaining a layered structure of energy detectors. One key problem is that individual decisions obtained from the multiple energy detectors are statistically dependent, thus complicating the derivation of the overall probabilities of detection and false alarm. ROC curves have been computed, showing significant improvements in detectability when there is a large mismatch between the duration of the observation interval and the actual duration of the signal. This can be especially interesting in the framework of novelty detection where specific parameters of the signal, like duration, are totally unknown.     

通信行业节能减排工作的思考

阐述了现阶段通信行业自身节能减排工作及措施包括的主要内容，以及通信运营商节能减排需要关注的几个问题，最后介绍了通信行业对全社会节能减排的意义。     

Effects of distance between wells on band structure and characteristics of InGaAs/InGaAsP strain-compensated multiple quantum well lasers

In terms of the multi-well energy representation technique, the effects of the distance between wells on the valence band structure and characteristics are analyzed for InGaAs/InGaAsP strain-compensated multiple quantum well lasers with zero net strain. The computed result shows that a coupling effect exists between the wells, causes an energy split, and affects the properties of the laser, such as the density of states, optical gain, differential gain, threshold wavelength, threshold carrier density and threshold current density. We find that when the distance between wells equals twice the thickness of the well, the effect of the distance between wells on the characteristics of the laser becomes weak. Therefore, for the practical design of lasers, it is reasonable to take the thickness of the barrier to be twice that of the well.     

Role of inter-particle collision on solids acceleration in riser

Collision among particles plays a significant role in governing the structure of gas-solids flow in a riser,especially in the dense and acceleration region.The inter-particle collision is the major cause not only for the kinetic energy dissipation(in terms of additional pressure drop beyond the solids hold-up) but also for the control of solids acceleration(in terms of a balancing force to prevent a free acceleration of solids).A neglect of the balancing force of inter-particle collision against the hydrody...     

Inverted Region in Intermolecular Electronic Energy Transfer

A critique of some recent publications (concerning the so-called inverted region in exchange-induced electronic energy transfer) is presented. It is first pointed out that the phenomena reported therein have in fact been known for nearly two decades; next, a derivation of the expression (used in the aforementioned communications) for k _EnT, the transfer rate constant, is presented; finally, it is stressed that this formula cannot provide reliable quantitative predictions.     

Field Interaction and Anomalies in Astrophysical and Cosmological Phenomena

The WKB expansion of bosonic and fermionic interacting fields in general curved spacetimes is computed. The explicit expression of the loss of energy in terms of macroscopic quantities like densities and velocities, according to the corresponding spinorial structure, is obtained. Analyzing experimental data of the PSR 1913+16 pulsar, we propose an interpretation of the rotational energy decay and estimate the possible bosonic-fermionic interaction strength capable of producing it. We use these results to discuss some cosmological anomalies related to red-shifts and energy decays giving alternative interpretations.     

Vehicle motion control with subsystem prioritization

This paper presents a new approach for integrated vehicle motion control, coordinating multiple vehicle subsystems of a passenger car including friction brake system, near-wheel drive electric motors, wheel steer actuators, camber angle actuators, dynamic tire pressure system and actuators generating additional normal forces. The proposed algorithms are based on restriction weights into the cost function of optimization-based control allocation. Hardware-in-the-loop investigation using a test rig with hardware components of friction brake system and dynamic tire pressure system showed that the proposed approach allows to achieve lower energy consumption and energy losses without significant impairment of motion stability and vehicle handling as compared to conventional control allocation.     

单原子催化剂的合成及其能源电催化应用的研究进展

基于电化学反应的能源储存与转化技术为全球能源结构的转型提供了一条绿色、 可持续的途径, 高效的电催化剂在其中扮演着重要的角色. 得益于在物理、 化学性质上的独特优势, 单原子催化剂在电催化能源转化方面展现出巨大的应用前景. 本文综合评述了单原子催化剂的合成及其能源电催化应用的研究进展, 介绍了单原子催化剂的常见表征手段, 总结了单原子催化剂的合成方法(湿化学法、 高温热解法、 原子沉积法、 电化学沉积法等), 并介绍了该类材料在氧还原、 二氧化碳电还原、 电解水及氮气电还原反应中的研究进展, 重点探讨了催化剂微观结构与其性能之间的关系, 最后, 对单原子能源电催化领域所面临的挑战进行了总结, 并对该领域未来的发展方向进行了展望.