Cognitive amplify‐and‐forward relay networks with beamforming under primary user power constraint over Nakagami‐m fading channels

In this paper, we analyze the performance of cognitive amplify‐and‐forward (AF) relay networks with beamforming under the peak interference power constraint of the primary user (PU). We focus on the scenario that beamforming is applied at the multi‐antenna secondary transmitter and receiver. Also, the secondary relay network operates in channel state information‐assisted AF mode, and the signals undergo independent Nakagami‐m fading. In particular, closed‐form expressions for the outage probability and symbol error rate (SER) of the considered network over Nakagami‐m fading are presented. More importantly, asymptotic closed‐form expressions for the outage probability and SER are derived. These tractable closed‐form expressions for the network performance readily enable us to evaluate and examine the impact of network parameters on the system performance. Specifically, the impact of the number of antennas, the fading severity parameters, the channel mean powers, and the peak interference power is addressed. The asymptotic analysis manifests that the peak interference power constraint imposed on the secondary relay network has no effect on the diversity gain. However, the coding gain is affected by the fading parameters of the links from the primary receiver to the secondary relay network. Copyright © 2012 John Wiley & Sons, Ltd.     

Adaptive blind receivers for MC‐CDMA communication systems

In this paper, we propose three adaptive blind algorithms for multiuser multicarrier code division multiple‐access systems in multipath fading channels. The proposed adaptive blind receivers are based on the property of the discreteness of the input data symbol and are updated in every symbol interval. We also use the concept that the variance of the output signal approaches to the variance of the desired signal to get the cost function. The three proposed receiver structures are the traditional finite impulse response (FIR) structure, the despreading (DES) filter structure and the generalized sidelobe canceller (GSC) structure. The advantage of the FIR filter is that the length of the filter weights does not have to be the same length as the spreading code. For the DES filter, the combination of the adaptive weight and the despreading code has the simplest structure than the other two proposed receiver structures. The constrained GSC filter is superior to the other two proposed receiver structures in the environments dominated by multiple‐access interference. By this constraint, the blind GSC filter can guarantee to converge to the desired solution. Simulation results are given to show the effectiveness and comparison of the proposed adaptive blind receivers. Copyright © 2012 John Wiley & Sons, Ltd.     

Batch adsorption of organic pollutants from oxidation pond effluents using fly ashes

The batch shaking adsorption study was conducted to determine the potential of fly and volcanic ashes in removing organic pollutants from oxidation pond effluents. Factors affecting organic pollutant removals, such as concentrations and sizes of fly and volcanic ashes, initial pond effluent organic concentrations, washed and unwashed conditions of fly and volcanic ashes, were investigated. The TOC (total organic carbon) removal efficiency varied from 30 to 58 percent. The organic removal efficiency increased with increasing ash concentrations, with decreasing initial pond effluent organic concentrations and with decreasing sizes of ashes.     

Adjustment behaviour of capital structure over the business cycles: evidence from the construction industry of Taiwan

Prior studies have found that firms may deviate from the target capital structure in the short run and adjust towards the target in the long run. However, little attention has been given to the adjustment behaviour of capital structure in the construction industry over the business cycles, in particular within the context of emerging markets. The partial adjustment model with the GMM (i.e. generalized method of moments) estimation is used to examine the adjustment behaviour of capital structure in the construction industry within the context of Taiwan during the period 1982 to 2007. The results suggest that, first, the average rate of adjustment is 26.3% of the adjustment gap between the target debt ratios and the previous debt ratios for firms in the construction industry of Taiwan. However, the average rate of adjustment towards the target debt ratios has slowed down after the Asian financial crisis of 1997. Secondly, firms with the financial constraint of over‐leverage relative to the target debt ratios have lower debt ratios than those firms with the financial constraint of under‐leverage. In addition, the difference in debt ratios between firms with the financial constraint of over‐leverage and under‐leverage has become narrower after the Asian financial crisis. Lastly, the findings suggest that macroeconomic conditions do not have a significant, negative effect on debt ratios.     

台湾的木建筑:迈向永续之路

"认识自然,依循自然法则,寻找出恰当的对应."是永续设计的基本原则.思考"永续"的议题时,必须超越建筑物本身,以更宽广的视野来思考整体环境与人及建筑的关系. 台湾有其独特的气候、地形、风貌与植物,不同于日本也不同于欧洲.在台湾极其珍贵但有限的资源中,如何使建筑与生态体系共存,是我们长期努力的目标.在建筑设计中,有几个关键议题是我们特别重视的—1)再生建材(renewable materials)的使用;2)与地形(topography)之对应;3)与当地气候(local climate)之对应;4)以隐喻(metaphor)的手法呼应当地的人文特质.第4项似乎与永续无关,但却是一种以诗意的方式来表达建筑的作法.我观看上帝常以他所造的自然万象隐喻他的意念,也常以诗意的手法表达他的思想,这也影响了我们创作表达的方式.     

Highly sensitive electrochemical sensor based on zirconium oxide-decorated gold nanoflakes nanocomposite 2,4-dichlorophenol detection

Journal of Applied Electrochemistry - In this study, a sensitive and selective electrochemical sensor based on a zirconia oxide-decorated gold nanoflake nanocomposite-modified glassy carbon...     

CuInSe2 Formation from CuSe/In2Se3 and Cu2Se/In2Se3 Powders: Reaction Kinetics and Mechanisms

CuInSe₂ (CIS) powders were synthesized using CuSe, Cu₂Se, and In₂Se₃ as the raw materials. The formation mechanisms and reaction kinetics from CuSe/In₂Se₃ and Cu₂Se/In₂Se₃ powders in a selenium atmosphere were investigated. It was observed that the formation temperature of α‐CIS powders synthesized using Cu₂Se/In₂Se₃ as the raw materials was higher than that using CuSe/In₂Se₃. Both reactions for Cu₂Se/In₂Se₃ and CuSe/In₂Se₃ mixtures follow one‐dimensional diffusion‐controlled reactions with apparent activation energies of 124.3 and 73.2 kJ/mol, respectively. For both mixtures the indium‐rich β‐CIS phase resulting from Cu⁺ ion diffusion toward the In₂Se₃ phase was observed. The particle size and morphology of the newly formed CIS was similar to In₂Se₃, which indicated that the CIS formation kinetics may be dominated by the diffusion of Cu⁺ ions. The Cu–Se liquid phase resulting from the peritectic decomposition of CuSe₂ and CuSe at a relatively low temperature may promote Cu⁺ diffusion into the In₂Se₃ surface, assisting CIS formation.     

Enhanced Piezoelectric and Dielectric Responses in 92.5%(Bi0.5Na0.5) TiO3 ‐7.5%BaTiO3 Ceramics

Structure and piezoelectric coefficient (d₃₃) of lead‐free 7.5% mole BaTiO₃‐doped (Bi_0.5Na_0.5) TiO₃ (BNT‐7.5%BT) polycrystalline piezoceramics have been characterized systematically as a function of poling electric (E) field. Dielectric permittivity and loss were also measured as functions of frequency and temperature. The piezoelectric coefficient d₃₃ after poling at E = 35 kV/cm can reach d₃₃~186 pC/N, which is the highest value reported among (1?x) BNT–xBT compositions. A prior poling E field can reduce rhomobherdal lattice distortion, and enhance tetragonal phase and polarization ordering, that contribute significantly to the rapid raise of d₃₃ and lower depolarizing temperature (T_d). The reduced dielectric permittivity for the poled sample is attributed to ordered state and the pinning of field‐induced nanodomain walls by the presence of oxygen vacancies.     

Density modeling of polyurethane box foam

A model based on about a dozen fundamental differential equations is used to evaluate and simulate the urethane reactions and physical processes of urethane box foaming. This work focuses on quantitative modeling of foam density for foams using water and physical blowing agents. The final densities of foams range from 30 to 90% of the density as projected with full utilization of the blowing agent. The primary sources of inefficient use of blowing agent are loss of the physical blowing during open‐air mixing and degassing—basically, physical blowing agents with boiling points between 25 and 80°C will evaporate and experience cell rupture in box foams. This loss of blowing agent would not apply to in‐line mixers used for commercial production and should be taken into account with scaling up box or cup foams commercial processes. POLYM. ENG. SCI., 54:1503–1511, 2014. © 2013 Society of Plastics Engineers