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81.
Ma?gorzata Igalson Pawe? Zabierowski Aleksander Urbaniak William N. Shafarman 《Solar Energy Materials & Solar Cells》2009,93(8):1290-1295
Many electrical characteristics of Cu(In,Ga)Se2-based solar cells, including current-voltage characteristics, are affected by specific properties of negative-U defects in the absorber. We present these characteristics and discuss them in the framework of a VSe-VCu defect model proposed by Lany and Zunger. We show how these defects influence photocarrier transport and the dominant recombination mechanism, and hence also the photovoltaic parameters of the cells. Numerical simulations validating our approach will also be presented. 相似文献
82.
Robert Rusinek Aleksander Siger Marzena Gawrysiak-Witulska Ewa Rokosik Urszula Malaga-Toboła Marek Gancarz 《International Journal of Food Science & Technology》2020,55(5):2161-2170
The article presents an attempt to use an electronic nose together with a new three-parameter method for generation of a digital smellprint in order to specify the mode of processing of rapeseed based on the analysis of volatile compounds contained in cold-pressed rapeseed oil. Prior to the pressing process, the seeds were roasted or improperly stored to obtain oil samples with varied technological quality. The quality of pressed oils was evaluated by determination of the acid value. Furthermore, changes in oil colour were assessed with the use of an imaging colorimeter. Volatile compounds were determined with the use of gas chromatography and an electronic nose with a metal oxide semiconductor (MOS) sensor matrix. It was found that the mode of seed pre-treatment before pressing did not change the colour of the oil significantly. However, it influenced the profile of volatile organic compounds and changed their proportions. Ketones represented the largest proportion of volatile compounds determined for roasted samples and those pressed from seeds moistened up to 25% (w.b.). Alcohols dominated in samples moistened up to 10 and 12%, terpenes were the dominant volatile compounds in samples roasted at 140 °C, and other volatile compounds dominated in samples moistened up to 10 and 20% (w.b.). In turn, esters and aromatic compounds accounted for the lowest proportion in the analysed samples. The results shown by the electronic nose were correlated with the presence of particular groups of volatile compounds in rapeseed oil. 相似文献
83.
Mariusz Chalecki Wojciech Czaplejewicz Aleksander Pawłuszewicz 《Welding International》2013,27(3):165-169
The aim of this research was to develop a process for welding BORON 27 type quenched steel, manufactured in Finland. The composition of a shielding gas mixture was selected by means of trials: 90% Ar, 5% CO2, and 5% O2. Joints were reproduced by this method, i.e. welded, quenched joints as well as unquenched welded joints, and were tested for quality. Tests included X-ray radiography, macroscopic testing, hardness tests, and tearing and bending resistance tests. The results of these tests were presented in the article. 相似文献
84.
Rapeseed oil‐based polyurethane foams modified with glycerol and cellulose micro/nanocrystals
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Mirna A. Mosiewicki Piotr Rojek Sławomir Michałowski Mirta I. Aranguren Aleksander Prociak 《应用聚合物科学杂志》2015,132(10)
A rapeseed oil‐based polyol (ROPO) was synthesized using chemical modification of the rapeseed oil (RO) by epoxidation reaction followed by oxirane ring‐opening with diethylene glycol. The ROPO was used in the formulation of low‐density green polyurethane (PU) foams. The use of glycerol as hydroxyl component, water as a reactive blowing agent and micro/nanocellulose (MNC) as a reinforcement increases the content of natural components in the formulations with important effects on the final foam properties. The ROPO and their intermediate products are characterized by analytical techniques and FTIR spectroscopy, while the final PU foams are characterized by morphological and mechanical analysis. The results show that the addition of glycerol increases the modulus and yield stress. The incorporation of MNC in small amounts is enough to increase the modulus at low temperatures. Both modifiers cause an increase in water absorption and the fragility of the cell walls, reflected in the micrographs of the foams. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41602. 相似文献
85.
Effect of different concentration of rapeseed‐oil‐based polyol and water on structure and mechanical properties of flexible polyurethane foams
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Flexible polyurethane foams (FPURFs) with varied concentration of water from 3.2 to 4.2% and rapeseed oil based polyol (ROP) in the range of 13–22% in polyol premix were obtained. Effects of changes in polyurethane (PUR) formulation on the foaming process and mechanical properties of FPURFs were analyzed. It was found that the change of water content in PUR formulation influences its foaming process. Higher water content in the PUR formulation increases the growth velocity and the temperature of reaction mixture. In the case of foams modified with ROP, an opposite effect can be observed, where higher content of that component resulted in overall downturn of the foaming process and decreases of registered temperature inside the foams core. An addition of ROP beneficially influences on foams cellular structure favoring creation of finer cells. Such modification of PUR formulation with ROP increased apparent density, reduced hardness, and resilience of flexible foams. What is more the support factor of FPURFs with ROP was higher in comparison to the reference foam. Along with higher water content in the PUR formulation, apparent density and hardness has decreased and foams ability to absorb energy has been increased. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42372. 相似文献
86.
Richard T. Fox Robert A. Newman Aleksander J. Pyzik Chan Han 《International Journal of Applied Ceramic Technology》2010,7(6):837-845
Modification of the Al2O3–Al system's chemistry via the addition of B4C is described and is shown to result in fully dense structures via wetting techniques at high temperatures, without the need for pressure-assisted infiltration. The relationships between the surface area of boron carbide and alumina powders, the effectiveness of infiltration, the material chemistry following infiltration, and the resulting mechanical properties of Al2O3–B4C–Al composites are evaluated. Additional approaches, including the incorporation of aluminum metal powder as an additional wetting agent before infiltration, are described in conjunction with a variation of both the surface areas and the volumetric ratios of inert Al2O3 to reactive B4C phases. These methods can provide the means to achieve low-cost metal matrix composites in both vacuum and argon infiltration environments, and represent an approach that enables the generation of articles with complex geometries, requiring minimal secondary finishing treatment. 相似文献
87.
P. K?dzioraA. Muc 《Composite Structures》2012,94(3):1224-1235
In this paper, dynamics, electromechanical couplings, and control of piezoelectric laminated cylindrical shells and rectangular plates are investigated. It is assumed that the piezoelectric layers are distributed on the top and bottom surfaces of the structures. First of all the governing equations and boundary conditions including elastic and piezoelectric couplings are formulated and solutions are derived. Then control of the plate/shells deflections and natural frequencies using high control voltages are studied in order to optimize the structural response. The present formulation of optimal design introduces boundaries of piezoelectric patches as new class of design variables. In addition, classical design variables in the form of ply orientation angles of orthotropic layers are also taken into account. For the actuator/actuator configuration, it was shown that the piezoelectric actuators can significantly reduce deformations/eigenfrequencies of the composite plate. Those effects were dependent on the value of the applied voltage. It was demonstrated that the proper choice of the actuator area is more efficient in reducing deflections/eigenfrequencies. The accuracy of optimal design are verified both with the aid of the FE package ABAQUS and using the standard Rayleigh-Ritz method. The results concerning active vibration control for axisymmetric cylindrical shells are also discussed. 相似文献
88.
An auction platform is a dynamic environment where a rich variety of social effects can be observed. Most of those effects remain unnoticed or even hidden to ordinary users. The in-depth studies of such effects should allow us to identify and understand the key factors influencing users’ behaviour. The material collected from the biggest Polish auction house has been analyzed. NLP algorithms were applied to extract sentiment-related content from collected comments and to measure informativity. Emotional distance between negative, neutral and positive comments has been calculated. The obtained results confirm the existence of the spiral-of-hatred effect but also indicate that much more complex patterns of mutual relations between sellers and buyers exist. The last section contains a several suggestions which can prove useful to improve trustworthiness of users’ reports and security of an auction platform in general. 相似文献
89.
Aleksander Rebane Mikhail Drobizhev Mikalai Kruk Aliaksandr Karotki Imbi Tehver Marlan Scully 《Journal of Modern Optics》2013,60(9):1243-1253
We study the coherent excitation profile (CEP) of resonance enhanced femtosecond CARS in a model system zinc phthalocyanine in a polymer film host as a prospective technique for detection and identification of molecular species in ambient environments. A new method of suppressing the non-resonant FWM background is demonstrated. Transform theory is applied to calculate CEP based on the absorption spectrum, and good agreement between theory and experiment is obtained. 相似文献
90.
Environmental sustainability indicators are studied with a particular emphasis on the relation with measures of happiness in nations. Environmental sustainability indicators measure success in transition toward a sustainable economic system where development must also improve quality of environment and quality of life. Traditional indicators of sustainable development are focused on economic, environmental and social measures of development. A link between sustainable development indicators and quality of life is often difficult to see for the individual. Here a new strategy is presented, which aims to explore relation between sustainability and happiness in order to promote sustainable development. An important question whether sustainable development in the interest of future generations requires a happiness sacrifice from the part of the current generation is being addressed, and apparently no sacrifices in happiness are required, as it is possible to design strategies, which improve happiness and sustainability simultaneously. 相似文献