Continuous Low‐Bias Switching of Superconductivity in a MoS2 Transistor

Engineering the properties of quantum electron systems, e.g., tuning the superconducting phase using low driving bias within an easily accessible temperature range, is of great interest for exploring exotic physical phenomena as well as achieving real applications. Here, the realization of continuous field‐effect switching between superconducting and non‐superconducting states in a few‐layer MoS₂ transistor is reported. Ionic‐liquid gating induces the superconducting state close to the quantum critical point on the top surface of the MoS₂, and continuous switching between the super/non‐superconducting states is achieved by HfO₂ back gating. The superconducting transistor works effectively in the helium‐4 temperature range and requires a gate bias as low as ≈10 V. The dual‐gate device structure and strategy presented here can be easily generalized to other systems, opening new opportunities for designing high‐performance 2D superconducting transistors.     

Effect of Process Parameters on Work Index, Milling Efficiency and Some Technological Properties of Yam Flour Using Attrition Mill

The effect of process parameters on work index, efficiency of milling, bulk density, swelling capacity and water absorption capacity of yam flour using attrition mill was studied. Independent variables were: moisture content (8, 12, 16, 20 and 24 % w.b.), speed (288, 346, 432, 576 and 864 rpm) and inlet opening (1,300, 2,600, 3,900, 5,200 and 6,500 mm²). The responses were work index, milling efficiency, bulk density, water absorption and swelling capacities of the flour. Work indexes for milling yam flour, meal and grit were found to be 0.25?±?0.13, 0.49?±?0.14 and 1.8?±?0.56, respectively. Flour fraction, bulk density, water absorption capacity and swelling capacity ranged from 42.2 to 56.6 %, 0.54 to 0.66 g/m³, 200 to 400 % and 13 to 23 ml, respectively. The treatments were found to influence the responses significantly (p?<?0.05). Optimum process condition was achieved at 12 % moisture content of feed, 506 rpm shaft speed and 5,200 mm² feed opening giving 19.1 % grit, 23.6 % meal and 54.2 % flour. The desirability of the optimisation process was 0.78. Validation of predicted optimal moisture content, worm shaft speed and feed inlet opening gave errors of 19, 14.4 and 6.1 % for grit, meal and flour, respectively.     

A new algorithm for geometrical design of asymmetric tall buildings against seismic torsional behaviour

This paper presents a new algorithm developed to minimize the torsional effects in asymmetric tall buildings, through arriving at all possible orientations of rectangular columns that have different lateral stiffnesses and strength in two principal directions. The most suitable combination of different orientations of such columns are chosen for the design, which leads to minimum torsional effect. The developed algorithm is coded in MATLAB and the eccentricity of a given asymmetric tall building is minimized through the proposed algorithm. Three‐dimensional model of the building is constructed and its modal analysis is performed to obtain mode shapes using SAP2000 finite element program. Finite element model of the building is updated to eliminate the torsional moments by applying developed algorithm. Earthquake behaviour of the building is investigated using 1999 Kocaeli earthquake before and after this geometrical design. It is seen from the analysis results that the torsional moments are almost eliminated and the maximum principal stresses on shell elements are extremely reduced after system design depending on the proposed algorithm. In addition to this, it is realized that structural modal behaviour of the building is changed from torsional to translational. Copyright © 2010 John Wiley & Sons, Ltd.     

A review: Recent advances in sol-gel-derived hydroxyapatite nanocoatings for clinical applications

The prospect of modifying the surface properties of the substrate (or base) material to enhance its corrosion and wear resistance as well as its reliability, performance, and more importantly its bioactivity is made possible using nanocoatings. An effective technique of synthesizing high purity nanocoatings in addition to nanopowders and fibers is to utilize the sol-gel approach. It is an attractive and versatile method that can be carried out with relative ease. Ceramic coatings, such as hydroxyapatite (HAp), can be fabricated through chemical means from solutions and consequently complex shapes can be coated economically. Given the fact that mixing takes place on the atomic scale, one of the key advantages of the sol-gel technique is its capacity to produce homogeneous materials, and it has been shown that the mechanical properties of sol-gel coatings are enhanced due to the presence of nanocrystalline grain structures. This review covers a brief insight into the recent application of HAp nanocoatings derived from sol-gel technique.     

Complexity Model Based Proactive Dynamic Voltage Scaling for Video Decoding Systems

Significant power savings can be achieved on voltage/ frequency configurable platforms by dynamically adapting the frequency and voltage according to the workload (complexity). Video decoding is one of the most complex tasks performed on such systems due to its computationally demanding operations like inverse filtering, interpolation, motion compensation and entropy decoding. Dynamically adapting the frequency and voltage for video decoding is attractive due to the time-varying workload and because the utility of decoding a frame is dependent only on decoding the frame before the display deadline. Our contribution in this paper is twofold. First, we adopt a complexity model that explicitly considers the video compression and platform specifics to accurately predict execution times. Second, based on this complexity model, we propose a dynamic voltage scaling algorithm that changes effective deadlines of frame decoding jobs. We pose our problem as a buffer-constrained optimization and show that significant improvements can be achieved over the state-of-the-art dynamic voltage scaling techniques without any performance degradation. Index     

Performance comparison of ZnO photocatalyst in various reactor systems

BACKGROUND: Owing to difficulties in catalyst recovery from slurries the deposition of a catalyst on suitable supports has been investigated extensively in recent years. The support material and the method of coating influence the activity. Photocatalytic decolorization of methyl orange (MO) and Rem Red F3B (RRF3B) was conducted in various reactor systems including a slurry reactor, ZnO thin film coated tube reactor and fixed bed reactor filled with ZnO coated ceramic or glass supports of various geometries. RESULTS: ZnO coating was carried out by the ammonium zincate deposition method. ZnO thin films were quite stable in acidic and basic media and resistant to photocorrosion. Various methods including scanning electron microscopy (SEM) and X‐ray diffraction (XRD) were applied for the physical characterization of thin films. The XRD patterns of ZnO thin film exhibit a wurtzite (zincite) crystal structure. SEM analysis revealed the granular morphology of ZnO film with a particle size of 300–400 nm. CONCLUSION: Photocatalytic activities were determined kinetically by calculating first‐order rate constants, which were also related to process variables by regression analysis. From the viewpoint of decolorization efficiency, the coated tube reactor (6 mm i.d.) showed the highest activity, which was equal to that of a powder catalyst loading of 300 mg dm^?3 for MO and of 200 mg dm^?3 for RRF3B. Copyright © 2010 Society of Chemical Industry     

Lumped-parameter models for low-temperature geothermal fields and their application

The behavior of low-temperature geothermal reservoirs under exploitation is simulated using analytical lumped-parameter models. These models consider the effects of fluid production and reinjection, as well as natural recharge, on the pressures (or water levels) of low-temperature, liquid-dominated geothermal systems. The computed responses for constant production/injection flow rates are given in the form of analytical expressions. Variable flow rate cases are modeled, based on the Duhamel's principle. Reservoir parameters are obtained by applying a weighted nonlinear least-squares estimation technique in which measured field data are history matched to the corresponding model response. By using history-matched models, the future performance of the reservoir can be predicted for different production/injection scenarios in order to optimize the management of a given geothermal system.We demonstrate the applicability of the models by simulating measured data from the Laugarnes geothermal field in Iceland, and the Balcova–Narlidere field in Turkey.