Significant enhancement of electrical conductivity by incorporating carbon fiber into CoSb3 thermoelectric skutterudite fabricated by spark plasma sintering method

Journal of Materials Science - The effects of carbon fiber additions on the electrical and thermoelectric performance in p-type CoSb3-based skutterudite are reported. A threefold enhancement in...     

Book reviews

Various researchers have carried out forest fire analysis using NOAA satellite images. There are several methods of doing this, and most can detect a fire. However, many false fires were also detected, and, in some cases, actual fires were missed. We analysed four satellite‐based fire detection methods using data from AVHRR of NOAA‐16 over a period of three to six months for the Sakhalin region and the Japan region. Considering the fundamental differences, problems, and effectiveness of these methods, we have constructed an improved fire detection method with statistical analysis. Our method has reduced false fire detection significantly, as well as detected actual fire with accuracy.     

A highly efficient polymer‐anchored palladium(II) complex catalyst for hydrogenation,Heck cross‐coupling and cyanation reactions

BACKGROUND: Precise architectures of steric and electronic properties of palladium species play a crucial role in designing highly functionalized catalyst systems responsible for target organic transformations. Pd catalysts supported on polymer materials have been employed extensively as catalysts not only for hydrogenation but also for coupling reactions in the production of fine chemicals. RESULTS: A new polymer‐anchored Pd(II) complex has been synthesized and characterized. The catalyst shows high catalytic activity in the hydrogenation of styrene oxide, Heck cross‐coupling and cyanation reactions of aryl halides. The effect of various reaction parameters were investigated to optimize reaction conditions. The catalytic system shows good activity in the hydrogenation of styrene oxide (conversion 98%) with a selectivity to 2‐phenylethanol (93%) which is higher than its homogeneous analogues. The catalyst also exhibits excellent catalytic activity for the Heck cross‐coupling and cyanation reactions of various substituted and non‐substituted aryl halides. CONCLUSIONS: Results demonstrate that the catalyst is robust and stable and can be recovered quantitatively by simple filtration and reused several times without loss of activity. Copyright © 2010 Society of Chemical Industry     

On thermodynamics of methane + carbonaceous materials adsorption

This study presents the theoretical frameworks for the thermodynamic quantities namely the heat of adsorption, specific heat capacity, entropy, and enthalpy for the adsorption of methane onto various carbonaceous materials. The proposed theoretical frameworks are developed from the rigor of thermodynamic property surfaces of a single component adsorbate–adsorbent system and by incorporating the micropore filling theory approach, where the effect of adsorbed phase volume is considered. The abovementioned thermodynamic properties are quantitatively evaluated from the experimental uptake data for methane adsorption onto activated carbons such as Maxsorb III at temperatures ranging from 120 to 350 K and pressures up to 25 bar. Employing the proposed thermodynamic approaches, this paper shows the thermodynamic maps of the charge and discharge processes of adsorbed natural gas (ANG) storage system for understanding the behaviors of natural gas in ANG vessel.     

Australian research on ochratoxigenic fungi and ochratoxin A

The presence of the mycotoxin, ochratoxin A (OTA), has been reported in Australian grape products. Comprehensive surveys of Australian wines have determined that the frequency and level of OTA contamination are low. Aspergillus carbonarius is the primary OTA-producing species associated with grapes in Australia, and all isolates tested to date produce OTA. Aspergillus niger is isolated more frequently from vineyards, however, few strains produce OTA. A. carbonarius and A. niger exist as saprophytes in the top layer of soil beneath vines, from where they are thought to be blown onto bunches. The level of A. carbonarius in soil may be reduced by temperatures above or below the optimum temperature for survival (25 degrees C), by high soil moisture content, and by modifications to tillage and mulching practices. A. carbonarius is an opportunistic pathogen of damaged berries. In the absence of damage, spores may exist on berry surfaces without causing visible rots. Aspergillus rots are associated with black Aspergillus species, primarily A. niger, A. carbonarius and A. aculeatus. The potential for such rots is increased with berry damage, inoculum coverage and berry maturity. Susceptibility to berry splitting is related, in part, to bunch structure, and may be variety-dependent or influenced by rainfall, irrigation and canopy management. Black Aspergillus spp. are closely associated with berries near the main stem of the bunch. During winemaking, around 80% of the OTA initially present in grapes is removed, primarily with the skins and pulp during pressing. Additional reductions occur with the removal of precipitated grape and yeast solids. Bentonite in white wine and yeast hulls in red wine were the most effective non-carbonaceous fining agents for the removal of OTA.     

Thiophene-based molecular and polymeric semiconductors for organic field effect transistors and organic thin film transistors

Organic electronics has been a popular field for the last two decades, due to its potential to commercialize cheap-price and large-area flexible electronics. The devices based on organic compounds heavily rely on organic semiconductors (OSs). Primary challenge for materials chemist is the new OSs construction that has ameliorated attainment in organic thin film transistors (OTFTs) and organic field effect transistors (OFETs). The construction of air-stable (stable in air) n-channel OSs (electron-conducting materials) is particularly needed with capability comparable to that of p-channel materials (hole-conducting materials). In the last 10 years, there have been significant advancements in thiophene-based OSs. Thiophene-mediated molecules have a prominent role in the advancement of OSs. The main significance in thiophene-based molecules is their cheap-price (in comparison to silicon), processability at low temperature, structural flexibility, ability to be applied on flexible substrates, and high charge transport characteristics. In this paper, we review the progress in the performance of thiophene-based OSs that has been reported in the last 18 years, with a major emphasis on the last 10 years. This approach provides a crisp introduction to organic devices and catalogs progress toward the fabrication of thiophene containing p, n and ambipolar channel OSs, and discusses their characteristics. Finally, review discusses current challenges and future research directions for thiophene based OSs. This review would be beneficial for further developments in the technological performance. Moreover, this review will serve to accelerate knowledge and lays the foundation for improved applications. Hopefully, this struggle pushes the reader’s mind to consider new perspectives, think differently and forge new connections.     

An efficient workload-based data layout scheme for multidimensional data

Physical data layout is a crucial factor in the performance of queries and updates in large data warehouses. Data layout enhances and complements other performance features such as materialized views and dynamic caching of aggregated results. Prior work has identified that the multidimensional nature of large data warehouses imposes natural restrictions on the query workload. A method based on a “uniform” query class approach has been proposed for data clustering and shown to be optimal. However, we believe that realistic query workloads will exhibit data access skew. For instance, if time is a dimension in the data model, then more queries are likely to focus on the most recent time interval. The query class approach does not adequately model the possibility of multidimensional data access skew. We propose the affinity graph model for capturing workload characteristics in the presence of access skew and describe an efficient algorithm for physical data layout. Our proposed algorithm considers declustering and load balancing issues which are inherent to the multidisk data layout problem. We demonstrate the validity of this approach experimentally.     

Intracycle RPM control for vertical axis wind turbines

The wind energy market is currently dominated by horizontal axis wind turbines (HAWTs); however, vertical axis wind turbines (VAWTs) are emerging as a design alternative, especially for deep-water offshore siting due to their low center of gravity, ease of access to drivetrain components, and overall simplicity. Due to the absence of a pitch mechanism in large-scale Darrieus VAWTs, stall control has often been used to manage power and loads. Introducing a pitching mechanism in H-type VAWTs has been studied, but this diminishes the mechanical simplicity advantage, and the use of a pitching mechanism in a large-scale Darrieus-type VAWT is not practical. This work examines an innovative, alternative method to control the rotor dynamics of a large-scale 5 MW VAWT to maximize power while constraining loads without introducing any new or complex mechanical elements. This control strategy is termed intracycle revolution per minute (RPM) control, where the rotational speed of the turbine is allowed to vary in an optimal fashion with the azimuthal location of blades as opposed to typical constant RPM operation. An optimization framework is formulated for an open-loop optimal control problem and solved to maximize power subject to constraints on aerodynamic design loads. Results are presented to demonstrate the benefits and the performance limits of intracycle RPM control for large-scale 5 MW Darrieus VAWTs, namely, (1) power production (quantified in terms of AEP) that can be increased subject to baseline load limits and (2) opportunities to significantly increase AEP or decrease loads via intracycle RPM control that are examined for both two-bladed and three-bladed VAWTs.     

A real-coding jumping gene genetic algorithm (RJGGA) for multiobjective optimization

This paper presents a real jumping gene genetic algorithm (RJGGA) as an enhancement of the jumping gene genetic algorithm (JGGA) [T.M. Chan, K.F. Man, K.S. Tang, S. Kwong, A jumping gene algorithm for multiobjective resource management in wideband CDMA systems, The Computer Journal 48 (6) (2005) 749-768; T.M. Chan, K.F. Man, K.S. Tang, S. Kwong, Multiobjective optimization of radio-to-fiber repeater placement using a jumping gene algorithm, in: Proceedings of the IEEE International Conference on Industrial Technology (ICIT 2005), Hong Kong, 2005, pp. 291-296; K.F. Man, T.M. Chan, K.S. Tang, S. Kwong, Jumping-genes in evolutionary computing, in: Proceedings of the IEEE IECON’2004, Busan, 2004, pp. 1268-1272]. JGGA is a relatively new multiobjective evolutionary algorithm (MOEA) that imitates a jumping gene phenomenon discovered by Nobel Laureate McClintock during her work on the corn plants. The main feature of JGGA is that it only has a simple operation in which a transposition of gene(s) is induced within the same or another chromosome in the genetic algorithm (GA) framework. In its initial formulation, the search space solutions are binary-coded and it inherits the customary problems of conventional binary-coded GA (BCGA). This issue motivated us to remodel the JGGA into RJGGA. The performance of RJGGA has been compared to other MOEAs using some carefully chosen benchmark test functions. It has been observed that RJGGA is able to generate non-dominated solutions with a wider spread along the Pareto-optimal front and better address the issues regarding convergence and diversity in multiobjective optimization.