Design space exploration of SW beamformer on GPU

Ultrasound imaging has become one of the most widely used modalities in medical diagnosis today. However, real‐time ultrasound imaging requires large amount of data transfer and massive computation and therefore mainly relies on a complex dedicated hardware system. A recent trend of a graphics processing unit (GPU) based software‐based approach offers the advantages of flexibility and quick implementation. The GPUs have been reported as excellent accelerators across a wide range of applications. For best exploiting outstanding computational power and high memory bandwidth of a GPU, the paper explores the design space of implementing an ultrasound beamformer on a GPU platform. The design spaces are expanded by applying different optimization strategies to the beamformer on a GPU platform, and we also discuss the performance evaluation results on the various GPUs whose architectural characteristics are different to each others. The performance analysis shows that by optimizing CUDA code, our real‐time‐GPU‐based beamformer can be successfully implemented with 181 frames per second (fps) and speedup of 230.6X compared with the single‐threaded implementation on a high‐performance CPU platform. Copyright © 2014 John Wiley & Sons, Ltd.     

Alginate-based coatings charged with hydroxyapatite and quercetin for fresh-cut papaya shelf life

In this study, the effect of alginate-based coatings charged with quercetin glycoside compounds and hydroxyapatite/quercetin glycoside compounds (HA/QUE) on the microbiological quality, and on bioactive compounds of fresh-cut papaya, was evaluated for 14 days at 6 °C. Alginate coatings with hydroxyapatite/quercetin showed a high capability to slow down the growth of all microbiological parameters investigated. At the end of cold storage, the total bacteria count in papaya samples covered with HA/QUE alginate coating was 4.8 log CFU g⁻¹ which is significantly lower (P < 0.05) than 8.3 log CFU g⁻¹ for uncoated samples. Total carotenoids’ percentage decrease, at the end of storage, was about 20% in papaya with active coatings, with respect to the losses of 39 and 35%, registered in uncoated and alginate-coated samples respectively. Vitamin C content and the antioxidant activity measured in papaya coated with HA/QUE alginate showed significantly higher values (P < 0.05) for each storage day than those detected for control- and alginate-coated samples. Based on the sensory evaluation, active-coated fresh-cut papaya reached, at the end of the storage period, suitable values for commercial purposes.     

Robust Energy Efficiency Power Allocation for Uplink OFDM–Based Cognitive Radio Networks

This paper studies the energy efficiency power allocation for cognitive radio networks based on uplink orthogonal frequency‐division multiplexing. The power allocation problem is intended to minimize the maximum energy efficiency measured by “Joule per bit” metric, under total power constraint and robust aggregate mutual interference power constraint. However, the above problem is non‐convex. To make it solvable, an equivalent convex optimization problem is derived that can be solved by general fractional programming. Then, a robust energy efficiency power allocation scheme is presented. Simulation results corroborate the effectiveness of the proposed methods.     

Heat release and flame propagation in prefabricated modular unit with GFRP composite facades

Prefabrication of modular residential and office units involves rapid manufacturing various building components off-site from different choices of materials, and transportation to construction site for the complete assembly. While this prefabrication manufacturing process could reduce construction costs, time and waste by using lightweight composite modules (LCM), significant challenge is associated with fire performance of an office modular unit using the modular units. This work aims at investigating the fire performance of a modular office unit using the LCM in terms of heat release rate and temperature history and compared with the traditional office unit model using glazing facade. The heat release and flame propagations in a selected prefabricated modular office unit are simulated with computational fluid dynamic (CFD) taking into account the complexity of the materials systems and the influences of the facade. The numerical procedure combining pyrolysis analysis of the composite sandwiches and the fire dynamic simulation of the combustion process is developed. The computational model is validated with thermal responses obtained from the cone calorimetry experiments. Kinetic parameters obtained from the TGA tests and pyrolysis analysis are used as inputs for the models measuring the fire growth index and total heat release. A multilayer sandwich composite material model is proposed to simulate the thermal responses and combustion processes of the prefabricated unit envelop. Temperatures at critical locations of the units are captured and compared with the standard fire curve to reveal the significant improvement in the fire performance of the office modular unit utilising GFRP composite.     

Field of application of high strength steel circular tubes for steel and composite columns from an economic point of view

This paper presents the results of a global comparison between high strength steel and normal steel circular tube used to build steel and composite columns submitted to static loading, as regards the economic aspects. The comparison is based on an optimum design taking into account the strength, stability and stiffness conditions of Eurocode 3 and 4. The automatic implementation of the algorithms allows achieving a high amount of case studies, covering the realistic possibilities of building columns. The investigations are realized on simple columns, columns included in braced or un-braced frames and whole frames. The field of application of high strength steel (vs normal steel), regarding the total cost of the member, is provided in a chart clearly indicating where the use of high strength steel becomes economic.     

Origin of a Tetragonal BiFeO3 Phase with a Giant c/a Ratio on SrTiO3 Substrates

A tetragonal BiFeO₃ phase with giant c/a of approximately 1.25 has been of great interest recently as it potentially possesses a giant polarization and much enhanced electromechanical response. This super‐tetragonal phase is known to be a stable phase only under high compressive strains of above approximately 4.5%, according to first principle calculations. However, in previous work, this super‐tetragonal BiFeO₃ phase was obtained in films deposited at high growth rate on SrTiO₃ substrates with compressive strain of only around 1.5%. By detailed structure analysis using high resolution synchrotron X‐ray diffraction, atomic force microscopy, and transmission electron microscopy, the parasitic β‐Bi₂O₃ phase is identified as the origin inducing the formation of super‐tetragonal BiFeO₃ phase on SrTiO₃ substrates. In addition, ab initio calculations also confirm that this super‐tetragonal phase is more stable than monoclinic phase when Bi₂O₃ is present. Using Bi₂O₃ as a buffer layer, an alternative route, not involving strain engineering, is proposed to stabilize this promising super‐tetragonal BiFeO₃ phase at low growth rates.     

Photoluminescence and electroluminescence properties of poly(9-vinylcarbarzole) doped with anthracence derivatives containing bis(ethynylphenyl oxadiazole) or bis(vinylphenyl oxadiazole) substituents

The photoluminescence (PL) and electroluminescence (EL) properties of two novel light-emitting anthracence derivatives containing bis(ethynylphenyl oxadiazole) or bis(vinylphenyl oxadiazole) substituents (ANOs) blended with poly(9-vinylcarbazole) (PVK) are characterized. The energy transfer process in the blends is discussed. By employing 2,5-bis(5-tert-butyl-2-benzoxazolyl) thiophene (BBOT) and tris(8-hydroxyquinoline) aluminum (Alq3) as electron transporting layers (ETLs) in the EL devices, remarkable improvements in EL efficiency were observed. The effect of the transporting layer on the EL intensity of the devices is also discussed.     

Experiment and simulation of micro‐part dynamics with roughness effect

In this study, we perform an experiment and develop a dynamic model that describes the planar motion modes of a micro‐part, including two linear motions and one rotational motion, on a saw‐tooth surface. In the experiment, the planar motion of the micro‐part is obtained by a particle‐tracking method. The rotation angle is measured from the principal axis of the micro‐part image. In a simulation, the contact between the micro‐part and the saw‐tooth surface is assumed to be the contact between a number of hemispheres on the micro‐part and the surface, which results in either a point contact or a slope contact. The effect of the saw‐tooth surface's roughness on the contact force at each contact point is modeled as a field of normal vectors. In addition, the roughness of the saw‐tooth surface is approximated by superposing white noise on an ideal saw‐tooth profile and is used to evaluate the adhesion force. The results show that the model can describe the motion modes of a micro‐part. Furthermore, the simulated results of the two linear motions are in good agreement with our experimental results from a previous study. The proposed model can be used to improve the design of surfaces for micro‐part transport. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Preparation and characterization of silicone resin nanocomposite containing CdSe/ZnS quantum dots

We report the preparation of the core/shell cadmium selenide/Zinc sulfide quantum dots (CdSe/ZnS QDs)‐silicone resin nanocomposite through the solution‐mixing method, followed by thermal hydrosilylation. After dispersing QDs into Dow Corning two‐component silicone resins (OE6630A and OE6630B at 1:4 mixing ratio by weight), the resins were cured at 150°C for 1.5 h to produce QD‐silicone resin nanocomposites. The curing behavior of the silicone resins resulting from the thermal hydrosilylation was studied using differential scanning calorimetry (DSC). The properties of the QD‐silicone resin nanocomposites were investigated by ultraviolet–visible (UV–vis), fluorescence, confocal laser scanning microscopy (CLSM), atomic force microscopy (AFM), and thermogravimetric analysis (TGA) measurements. The QDs that contain trioctylamine (TOA) as the original ligand can poison the Pt catalyst in the resins and inhibit the curing process by increasing the exothermic peak temperature, at which a lower heat of hydrosilylation is observed. Incorporating a small amount of CdSe/ZnS QDs (0.1 wt%) can greatly improve the thermal stability of the silicone resins. Moreover, CdSe/ZnS QDs tend to form clusters that are relatively homogeneously distributed in a cured silicone resin, offering good optical properties of 11.2 lm W⁻¹ luminous efficiency and 14.6% photoluminescence conversion efficiency (PCE) in light emitting device (LED) test. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Investigation of tearing mechanisms of woven textile

Tearing resistance is an important parameter for evaluating the reliability of textile structures, especially in the case of protective materials. In order to better understand the individual contribution of the different mechanisms involved in the tearing process, a study of the relation between the fabric and yarn properties characterizing these mechanisms and the tearing energy has been carried out. For that purpose, polyester fabrics with two types of weave patterns and various values of filling yarn density and linear density were characterized in terms of tongue tear energy, yarn and fabric modulus, breaking force and elongation at break, yarn slippage, and yarn jamming. Data for all tested fabrics relied on a unique master curve when the tearing energy was expressed as a function of the transverse yarn slippage force. This demonstrates the strong contribution of transverse yarn slippage to the tearing process, a mechanism which has generally been overlooked in previous works on tearing. Relationships between the tearing energy and the other properties characteristics of the mechanisms involved in tearing of woven textiles were also observed. These results build the path toward the development of models for the tearing energy of textile structures. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers