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91.
Cadmium telluride nanoparticles with sizes between 8 and 13 nm have been synthesized via a sonochemical route using cadmium sulfate hydrate (CdSO4·8/3H2O), cadmium chloride (CdCl2) and elemental Te as precursors and aqueous solutions of NaOH and EDTA as solvents. The qualitative characterization and estimation of nanoparticle size were carried out by using X-ray powder diffraction (XRD). The morphology of nanoparticles was analyzed by transmission electron microscopy (TEM). Changes of physical and chemical properties of the prepared CdTe nanoparticles at increased temperature were studied by thermal analysis (TGA, SDTA). A probable mechanism for the sonochemical formation of CdTe is proposed. 相似文献
92.
Oleic-acid-coated CoFe2O4 nanoparticles were synthesized by co-precipitation and hydrothermal synthesis. The coprecipitation of the nanoparticles was achieved by the rapid addition of a strong base to an aqueous solution of cations in the presence of the oleic acid surfactant, or without this additive. The nanoparticles were also synthesized by a hydrothermal treatment of suspensions of the precipitates, coprecipitated at room temperature in the presence of the oleic acid, or without it. The influence of the synthesis conditions, such as the valence state of the iron cation in the starting aqueous solution, the temperature of the treatment and the presence of oleic acid, on the particles size was systematically studied. X-ray powder diffractometry (XRD) and transmission electron microscopy (TEM) coupled with energy-dispersive X-ray spectroscopy (EDS) revealed that, although spinel forms at room temperature, a substantial amount of Co was incorporated within the secondary, feroxyhyte-like phase when the iron cation was in the 2+ state. In contrast, when iron was in the 3+ state, the spinel forms at elevated temperatures of approximately 60 °C. The presence of the oleic acid further increased the formation temperature for the stoichiometric spinel. Moreover, the oleic acid impeded the particles’ growth and enabled the preparation of colloidal suspensions of the nanoparticles in non-polar organic solvents. The nanoparticles’ size was successfully controlled by the temperature of the synthesis in the region where superparamagnetism dominates to the region where mono-domain ferrimagnetism dominates the magnetic properties. 相似文献
93.
We have investigated the formation of barium hexaferrite via the coprecipitation method. Various reagent salts and solvents
were tested, and the coprecipitates were calcined at 300–800 °C for 1–50 h. The samples were characterized with X-ray powder
diffraction, electron microscopy and magnetometry. The coprecipitation conditions had a significant influence on the formation
time of the barium hexaferrite, which started to form at as low as 500 °C. The optimum coprecipitation conditions were: ethanol
as a solvent and chlorides as reagent salts. Powders with optimum magnetic properties, saturation magnetization 60–63 emu/g
and coercivity 4–5 kOe, were obtained by calcining at 600–700 °C. 相似文献
94.
The purpose of this article is to make a contribution to a more effective management for supply chains and networks, which we are subsuming under the title supply systems. We conceive of supply systems management as the design, control, and development of logistics along the value chain or in value networks. In this article, we concentrate on control, i.e., the regulation and steering of supply systems from production to customer and vice versa, with the help of system dynamics modeling and simulation. Traditionally, supply chain management has been heavily supported by discrete event simulation and optimization models on very detailed levels. Established tools, e.g., Manufacturing Resources Planning, Enterprise Resources Planning, and Production Planning Systems, have emphasized highly specialized functions, such as the planning for optimal capacity use and achievement of delivery goals, via the sequencing, scheduling, and dispatching of individual orders, or the global allocation of resources but without the possibility to evaluate different outcomes of the allocation process. In the quest for efficiency and effectiveness, new approaches to control, which lead beyond these functions of disposition, are needed. We present a model that combines two systemic methodologies that operate on higher levels of aggregation and complement each other: system dynamics to model and simulate the supply chain and cybernetic control to apply control-theoretical concepts, namely proportional, derivative, and integral control, in a combined mode as well as according to a recursive logic of distributed control. This way, substantial improvements in both efficiency and effectiveness can be achieved, and ultimately organizational viability can be enhanced. 相似文献
95.
Miha Mo?ina Dejan Toma?evi? Franjo Pernu? Bo?tjan Likar 《Machine Vision and Applications》2011,22(1):145-156
Visual appearance is an important quality factor of pharmaceutical tablets. Due to the vast quantities of produced tablets
and high-quality requirements, pharmaceutical companies are interested in employing automated systems for real-time visual
tablet inspection with the speeds of up to 100 tablets per second. Such systems require reliable tablet manipulation, illumination,
image acquisition, tablet image analysis, classification, and sorting system. Tablet image segmentation, in which each tablet
image is partitioned into the tablet region and background, is the first and very important step in tablet image analysis.
It this paper, we propose a novel real-time segmentation method for grey-level images that is based on border tracking. The
proposed method was designed to be accurate, robust, and computationally undemanding. The performances of the method were
objectively assessed on a large number of simulated and real tablet images. The obtained results indicated high reliability,
accuracy, and speed. The 100% reliability was obtained for segmentation of real images of pharmaceutical tablets, while the
segmentation times were no more than 1.5 ms or 15% of the whole time available for tablet image analysis. As such, the proposed
method proved feasible for real-time visual quality inspection of pharmaceutical tablets. Based on just a few assumptions
that are usually fulfilled, the method may be a valuable segmentation tool for many other visual quality inspection applications. 相似文献
96.
Miha Polajnar Franc Kosel Radovan Drazumeric 《Structural and Multidisciplinary Optimization》2017,55(1):91-104
The paper deals with minimum stress design using a novel stress-related objective function based on the global stress-deviation measure. The shape derivative, representing the shape sensitivity analysis of the structure domain, is determined for the generalized form of the global stress-related objective function. The optimization procedure is based on the domain boundary evolution via the level-set method. The elasticity equations are, instead of using the usual ersatz material approach, solved by the extended finite element method. The Hamilton-Jacobi equation is solved using the streamline diffusion finite element method. The use of finite element based methods allows a unified numerical approach with only one numerical framework for the mechanical problem as also for the boundary evolution stage. The numerical examples for the L-beam benchmark and the notched beam are given. The results of the structural optimization problem, in terms of maximum von Mises stress corresponding to the obtained optimal shapes, are compared for the commonly used global stress measure and the novel global stress-deviation measure, used as the stress-related objective functions. 相似文献
97.
Viktor Kraevec Miha Drofenik Drago Kolar 《Journal of the American Ceramic Society》1990,73(4):856-860
On the basis of the topotaxy between BaTiO3 and Ba6 Ti17 O40 found recently, a model of a nonconservative (111) twin in TiO2 -rich BaTiO3 was constructed. The model consists of several (001) layers of Ba6 Ti17 O40 intergrown between (111) layers of BaTiO3 , the core of the twin being a slightly modified double layer of Ba6 Ti17 O40 containing face-sharing octahedra. Using this model, anomalous grain growth below the eutectic temperature and preferential growth of (111) twins in a reducing atmosphere were explained, as well a nucleation of butterfly twins. 相似文献
98.
Darja Lisjak Andrej
nidari
Anna Sztanislav Miha Drofenik 《Journal of the European Ceramic Society》2008,28(10):2057-2062
We have investigated the formation of single-phase NiZn–W hexaferrites using two different approaches to the synthesis: a direct synthesis from an initial reagent mixture and a two-step synthesis from intermediates. As calculated, the probability of forming single-phase powders with a direct synthesis was lower than for the two-step synthesis. Powders were synthesized with both approaches via coprecipitation followed by a calcination at 1200–1300 °C. The synthesis was monitored with X-ray powder diffraction, thermogravimetric and thermomagnetic analyses. Single-phase NiZn–W hexaferrite powders were only obtained with the two-step synthesis. The electromagnetic properties of the NiZn–W powders and ceramics were measured. 相似文献
99.
Darko Makovec Zoran Samardija Miha Drofenik 《Journal of the American Ceramic Society》2006,89(10):3281-3284
The solid solubility of Ho3+ in BaTiO3 fired under the reducing conditions of a nitrogen atmosphere containing 10% of hydrogen was studied by quantitative electron-probe microanalysis using wavelength-dispersive spectroscopy. The solubility was found to depend mainly on the starting composition. In the TiO2 -rich samples, the solubility of the Ho3+ donors at the Ba lattice sites was measured to be ∼4 mol% HoBa (Ba0.96 Ho0.04 TiO3−δ at 1400°C), which is much higher than after sintering in air. In the BaO-rich compositions, the solubility of the Ho3+ acceptors at the Ti sites (solubility limit at 1500°C) decreased compared with that in air. Like with sintering in air, under reducing conditions, the highest solubility of holmium in BaTiO3 was determined when it was incorporated at both lattice sites (solubility limit ). 相似文献
100.
Miha Desman 《Architectural Design》2006,76(3):90-97
During the Soviet era, Slovenia was renowned as an architectural oasis for experimentation on the western borders of eastern European greyness. Miha Desman describes how this small but significant nation has maintained its taste for design innovation, despite the shifting economic and political conditions of the past two decades. He outlines what present-day Slovenia has to offer a greater Europe and the special qualities of its contemporary architecture. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献