Cooperative strategies of wireless access technologies: A game-theoretic analysis

The wireless Internet has to overcome the problem of spectrum scarcity as the number of mobile equipments could increase even by an order of magnitude in the next decade; the cooperation of mobile devices is foreseeable as a feasible solution to the problems. There exists a large body of literature on opportunistic ad hoc networking including Pelusi et al. (2006) [25], Chen et al. (2006) [26], Hui et al. (2005) [27]; however, the impact of the location of the devices on their access method selection is not yet appropriately dealt with. In this paper, we address this issue based on game-theoretic analyses. The key contribution of our work is threefold. First, we model the access method selection of mobile devices by extending the classical forwarding game with position, mobility, and availability of the devices. Second, we apply the model in game-theoretic analyses to better understand the optimal cooperation strategies in the presence of heterogeneous wireless technologies. We further extend our framework to include uncertainty. Finally, we present the applicability of the model in a cognitive radio scenario where complex structures of parameters are included.     

Buckling analysis of a cable-stayed circular frame

Large parabolic dish concentrators have been widely employed in solar thermal applications. The supporting structure of a solar dish concentrator consists of a circular frame, a central post, and front and rear cables connecting the frame to the post. The tensions in the cables cause compressive stresses in the circular frame and the central post, and this support structure must be designed for stability. In this paper, the nonlinear buckling behavior of the supporting structure of a cable-stayed circular frame is studied in detail. A three-dimensional finite element model of the supporting structure is developed to predict the critical cable tensions that would cause buckling of the circular frame and to determine the associated buckling mode shapes of the supporting structural system. The results show that the buckling load of a cable-stayed circular frame depends not only upon the cross-section of the frame, but also upon the number of cables and the inclinations of the cables. In all cases, in-plane buckling modes are predominant. The concentrated torques resulting from unbalanced cable tensions tend to induce the out-of-plane buckling modes.     

Influence of nitrogen plasma post-treatment on diamond-like carbon films synthesized by RF plasma enhanced chemical vapor deposition

DLC films were synthesized by RF plasma enhanced chemical vapor deposition and the effects of nitrogen plasma post-treatment at different pressures on the structure and properties of DLC films were investigated. Higher roughness was obtained after plasma post-treatment at higher pressures (0.3 and 0.9 torr) and plasma post-treatment at a lower pressure (0.15 torr) resulted in lower roughness than that of original films. The hardness of DLC films decreased with the decrease of post-treatment pressure, which is consistent with the Raman results of I_D/I_G ratio and G peak position. Compared to the original DLC film, the residual stress after plasma post-treatment decreased slightly due to the relatively thin region involved in the plasma post-treatment.     

New statistical method for detection and quantification ofrespiratory sinus arrhythmia

A statistical method with the advantages of 1) enabling graphical representation of within-respiratory cycle heart rate variations, 2) detecting the presence of respiratory sinus arrhythmia (RSA) in a moving window, and 3) providing breath-by-breath RSA amplitude and phase obtained from the fitting of a sinusoid to the instantaneous relative heart rate is presented.     

Controllability of one class of nonlinear singularly perturbed systems

Sufficient conditions of complete controllability are derived for quasilinear singularly perturbed systems.Translated from Kibernetika i Sistemnyi Analiz, No. 4, pp. 61–66, July–August, 1992.     

A hyperspectral imaging system for in vivo optical diagnostics

This paper details the basic principles and instrumental systems as well as applications of hyperspectral imaging system in the biomedical field. The development of an HSI system that combines recent advances in several photonic technologies, including an AOTF, a 2-D CCD detector, and imaging fiber optics. The integration of these technologies leads to a versatile and powerful imaging system that can rapidly record spectral images of samples. This imaging system could find useful applications in medical diagnostics applications where rapid in vivo detection of complex samples is required. The HSI technique has the potential for in site optical diagnosis on tissue and it can be use for guidance of surgical intervention and treatment. The optical diagnostic approaches may either be an imaging modality or a spectroscopic modality. The spectroscopic diagnostics may also provide real-time assessment of tissue response to therapy.     

基于TPS 复合结构毁伤的等效仿真方法

基于破片存速对某高空高速飞行器热防护结构的影响,提出一种用单一材料结构替代热防护系统(thermal protection system,TPS)复合结构毁伤的等效仿真方法.15 mmTPS热防护复合结构板经计算可等效为4.3 mm铝合金板,经试验验证误差仅为5.6％,吻合度较高,破片穿透板后,TPS复合材料层形成的破孔周围有明显扩孔现象.将试验与仿真结果对比发现:靶板正面与背面破孔直径误差分别为2.9％和2％,铝合金和TPS复合结构极限速度误差分别为2.3％和1.4％.结果表明,该方法对热防护复合结构的设计及优化具有一定参考价值.     

Synthesis of hyperbranched conjugated polymers based on 3-hexylthiophene,triphenylamine and benzo [c] [1,2,5] thiadiazole moieties: convenient synthesis through suzuki polymerization and impact of structures on optical properties

Novel 3-hexylthiophene-based hyperbranched conjugated polymers containing triphenylamine and benzo [c] [1, 2, 5] thiadiazole moieties were synthesized by Suzuki coupling polymerization of tris (4-bromophenyl) amine, 2,2′-(3-hexylthiophene-2,5-diyl) bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolane) and 4,7-dibromobenzo [c] [1, 2, 5] thiadiazole. Organic solvent-soluble polymers with number-average molecular weights of 24,000 and 42,000 g/mol were obtained in 54–57 % yields. Their structures, molecular weights and thermal properties were characterized via proton nuclear magnetic resonance (¹H NMR) and Fourier transform infrared (FT-IR) spectroscopies, gel permeation chromatography (GPC), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and wide-angle powder X-ray diffraction (XRD) measurements. Optical investigation by UV–vis and fluorescence spectroscopies revealed that the incorporation of the benzo [c] [1, 2, 5] thiadiazole moiety in the hyperbranched polymer structure resulted in a red-shift of the maximum absorption wavelength and an increase in the solution-photoluminescence quantum yield, indicating an extension of the conjugation length. The UV–vis, DSC and XRD results demonstrated that the aggregation of conjugated polymer chains could effectively be reduced by the hyperbranched structures and that conjugation length extension via the introduction of benzo [c] [1, 2, 5] thiadiazole units led to the coexistence of both crystalline and amorphous phases in the solid state and in solution upon addition of a non-solvent.