排序方式: 共有19条查询结果,搜索用时 15 毫秒
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Alvarez Carrillo Pavel Anselmo Roselli Lucia Reis Peixoto Frej Eduarda Asfora de Almeida Adiel Teixeira 《Annals of Operations Research》2022,314(2):377-392
Annals of Operations Research - The aim of this paper is to solve an agricultural technology packages selection problem by considering multiple dimensions which influence a maize producer’s... 相似文献
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In this work, biaxially stretched polymer foams with well‐defined cellular structures were prepared from polyethylene via blown‐film extrusion and subjected to corona charging to produce a piezoelectric response. The charging parameters were first optimized in terms of charging voltage and needle distance, as well as the gas type and pressure to investigate their effect on the piezoelectric coefficient (d33). The results show that samples charged under nitrogen (N2) at 100 kPa had better d33 coefficient than those charged under ambient air or N2 at 20 kPa. Moreover, 2 different thermal pressure treatments were imposed to obtain an optimized eye‐like cellular structure with different cell aspect ratios (AR). The results showed that when the cells were elongated in both the longitudinal and transverse directions (higher AR), higher d33 coefficients were achieved. From all the samples produced, the best results were obtained for a longitudinal aspect ratio (AR‐L) of 7.1, a transversal aspect ratio (AR‐T) of 4.6, and a relative foam density of 0.52 leading to a d33 coefficient of 935 pC/N. This coefficient was further increased using reverse charging and multilayered films, reaching a maximum of 2550 pC/N. This value is much higher than typical ones reported so far for any polyethylene and polypropylene ferroelectrets. These results could increase the use of polyethylene in piezoelectric applications as these materials are very attractive for the large‐scale production of electret‐based sensors and transducers due to their low cost and easy processing. 相似文献
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Menel Ben Frej Fanny d'Orlyé Gerson F. Duarte-Junior Wendell K. T. Coltro Anne Varenne 《Electrophoresis》2022,43(20):2044-2048
A low-cost and straightforward hybrid NOA (Norland optical adhesive) 81-glass microchip electrophoresis device was designed and developed for protein separation using indirect fluorescence detection. This new microchip was first characterized in terms of surface charge density via electroosmotic mobility measurement and stability over time. A systematic determination of the electroosmotic mobility (μeo) over a wide pH range (2–10) and at various ionic strengths (20–50 mM) was developed for the first time via the neutral marker approach in an original simple frontal methodology. The evolution of μeo was proved consistent with the silanol and thiol functions arising from the glass and the NOA materials, respectively. The repeatability and reproducibility of the measurements on different microchips (RSD < 14%) and within 15 days (less than 5% decrease) were successfully demonstrated. The microchip was then applied for the efficient electrophoretic separation of proteins in a zonal mode coupled with indirect fluorescence detection, which is, to our knowledge, the first proof of concept of capillary zone electrophoresis in this hybrid microsystem. 相似文献
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Bin Lin Frej Mighri Michel A. Huneault Uttandaraman Sundararaj 《Macromolecular rapid communications》2003,24(13):783-788
The deformation and breakup of a single polycarbonate drop in a polyethylene matrix is studied at high temperatures under simple shear flow using a transparent Couette device. We observed “parallel breakup” where the drop breaks after being stretched into a thin sheet parallel to the flow. The breakup occurs at a viscosity ratio greater than 3.5. Deborah number and a stress ratio incorporating elastic moduli can characterize the “parallel breakup”.
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The experimental data of the temperature and concentration dependence of viscosity of concentrated aqueous ammonium oxalate solutions are analysed using the hole theory of liquids and Einstein's model of viscosity. Analysis of the data revealed that the dimensions of the species participating in the growth of ammonium oxalate monohydrate crystals are 3‐5 times larger than the dimensions of individual NH4+ and C2O42‐ ions composing them. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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Summary: This study aims at developing a highly electronic conductive microporous structure from thermoplastic polymers filled with carbon black (CB) and graphite (GR). The matrix was a low viscosity poly(propylene) (PP) and the conductive additives were composed of high specific surface area CB and synthetic flake GR. Conductive blends were first developed using a corotating twin‐screw extruder. Rheological properties and conductivities of these blends were then characterized as a function of blend composition. Blends that show the best compromise between electronic conductivity and processability were subsequently extruded through a sheet die to obtain films of around 500 µm in thickness. These films were then stretched in two successive steps under controlled temperature and stretching rate to generate a film of controlled microporous structure.
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Jayesh Patel Frej Mighri Abdellah Ajji Devendra Tiwari Tapas K. Chaudhuri 《Applied Physics A: Materials Science & Processing》2014,117(4):1791-1799
In this work, we describe a simple spin-coating deposition technique for lead sulphide (PbS) and cadmium sulphide (CdS) films from a methanolic metal–thiourea complex. The characterization of the films by X-ray diffraction and X-ray photoelectron spectroscopy techniques revealed that pure cubic phase PbS and CdS layers were formed via this method. As shown by atomic force microscopy and scanning electron microscopy results, both films were homogeneous and presented a smooth surface. Optical properties showed that the energy band gap of PbS and CdS films were around 1.65 and 2.5 eV, respectively. The PbS film is p-type in nature with an electrical conductivity of around 0.8 S/cm. The hole concentration and mobility were 2.35 × 1018 cm?3 and 2.16 × 10?3 cm2/V/s, respectively, as determined from Hall measurement. Both films were used to develop a thin film solar cell device of graphite/PbS/CdS/ITO/glass. Device characterization showed the power conversion efficiency of around 0.24 %. The corresponding open circuit voltage, short circuit current and fill factor were 0.570 V, 1.32 mA/cm2 and 0.32, respectively. 相似文献
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We show that the heat equation for the Jacobi–Dunkl operator, has a solution in terms of a semigroup of Markovian operators with strictly positive kernel. This result is used to solve the Poisson equation and to introduce a new class of Markov processes on the real line. To cite this article: F. Chouchene et al., C. R. Acad. Sci. Paris, Ser. I 341 (2005). 相似文献
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This paper is devoted to the heat equation associated with the Jacobi–Dunkl operator on the real line. In particular we show that the heat semigroup has a strictly positive kernel and a finite Green operator. As a direct application, we solve the Poisson equation and we introduce a new family of one-dimensional Markov processes. 相似文献