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41.
Ivan Matin Miodrag Hadzistevic Janko Hodolic Djordje Vukelic Dejan Lukic 《The International Journal of Advanced Manufacturing Technology》2012,63(5-8):595-607
Mold design is a knowledge-intensive process. This paper describes a knowledge-based oriented, parametric, modular and feature-based integrated computer-aided design/computer-aided engineering (CAD/CAE) system for mold design. Development of CAx systems for numerical simulation of plastic injection molding and mold design has opened new possibilities of product analysis during the mold design. The proposed system integrates Pro/ENGINEER system with the specially developed module for the calculation of injection molding parameters, mold design, and selection of mold elements. The system interface uses parametric and CAD/CAE feature-based database to streamline the process of design, editing, and reviewing. Also presented are general structure and part of output results from the proposed CAD/CAE-integrated injection mold design system. 相似文献
42.
Biological and nutritional properties of blackcurrant berries (Ribes nigrum L.) under conditions of shading nets 下载免费PDF全文
43.
Marija V. Pergal Vesna V. Antić Milutin N. Govedarica Dejan Goäevac Sanja Ostojić Jasna Djonlagić 《应用聚合物科学杂志》2011,122(4):2715-2730
Novel polyurethane copolymers derived from 4,4′‐methylenediphenyl diisocyanate (MDI), 1,4‐butanediol (BD) and α,ω‐dihydroxy‐[poly(caprolactone)‐poly (dimethylsiloxane)‐poly(caprolactone)] (α,ω‐dihydroxy‐(PCL‐PDMS‐PCL); = 6100 g mol?1) were synthesized by a two‐step polyaddition reaction in solution. In the synthesis of the polyurethanes, the PCL blocks served as a compatibilizer between the nonpolar PDMS blocks and the polar comonomers, MDI and BD. The synthesis of thermoplastic polyurethanes (TPU) with high soft segment contents was optimized in terms of the concentrations of the reactants, the molar ratio of the NCO/OH groups, and the time and temperature of the polyaddition reaction. The structure, composition, and hard MDI/BD segment length of the synthesized polyurethane copolymers were determined by 1H, 13C‐NMR, and two‐dimensional correlation (COSY, HSQC, and HMBC) spectroscopy, while the hydrogen bonding interactions in the copolymers were analyzed by FT‐IR spectroscopy. The influence of the reaction conditions on the structure, molecular weight, thermal, and some physical properties was studied at constant composition of the reaction mixture. A change in the molar ratio of the NCO/OH groups and the reaction conditions modified not only the molecular weight of the synthesized polyurethanes, but also the microstructure and therefore the thermal and physical properties of the copolymers. It was demonstrated that only PCL segments with high soft segment contents crystallize, thereby showing spherulitic morphology. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
44.
Vujisić LV Makarov SE Curčić BP Ilić BS Tešević VV Gođevac DM Vučković IM Curčić SB Mitić BM 《Journal of chemical ecology》2011,37(12):1358-1364
Three European julid species, Cylindroiulus boleti, Leptoiulus trilineatus, and Megaphyllum bosniense, secrete mixtures of up to 12 different quinones. The major components in these species are 2-methoxy-3-methyl-1,4-benzoquinone
and 2-methyl-1,4-benzoquinone. 2-Methoxy-5-methylhydroquinone is detected for the first time in the Class Diplopoda. 2-Hydroxy-3-methyl-1,4-benzoquinone,
2,3-dimethoxyhydroquinone, 2-methyl-3,4-methylendioxyphenol, and 2,3-dimethoxy-5-methylhydroquinone are registered for the
first time in representatives of the family Julidae. The similar chemical composition of defense secretions in all analyzed
European julids and Pacific spirobolids supports the idea of the chemical consistency of defensive compounds in juliform millipedes. 相似文献
45.
Milos Bandjur Nikola Sekulovic Mihajlo Stefanovic Aleksandra Golubovic Petar Spalevic Dejan Milic 《ETRI Journal》2013,35(4):722-725
In this letter, a wireless communication system with microdiversity and macrodiversity reception in gamma‐shadowed Rician fading channels is considered. Exact and rapidly converging infinite‐series expressions for the average level crossing rate and average fade duration at the output of the system are provided. Numerical results are presented graphically to illustrate the proposed mathematical analysis and to examine the effects of the system's parameters on the quantities considered. 相似文献
46.
Dejan Beslija ;Sead Delic ;Kyong-Hoe Kim ;Mirsad Kapetanovic ;Almir Ahmethodzic 《能源与动力工程:英文版》2014,(11):1964-1973
Special interest in current interruptions is dedicated to the processes close to the current zero instant, the so-called interaction region, which determines the circuit breakers' performance. The quantities of interest in this region are the distribution of temperature, density and pressure, velocity and gas mass flow along the electric arc axis, as well as the distribution of electric stress between contacts Calculation of steady SF_6 gas flow through the nozzle of a 420 kV circuit breaker at the current zero instant, for different arcing durations, was carried out using a commercial CFD (computational fluid dynamics) simulation tool. The calculation results were used to get insight into improvement possibilities of the SF_6 gas flow model used in the software for computer simulation of HV (high-voltage) circuit breakers. Electric field calculation results were performed for the same 420 kV circuit breaker, in order to estimate the breakdown voltage at the current zero instant. 相似文献
47.
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49.
Dejan Ivezić Marija Živković Toma Tanasković Nenad Đajić 《Applied Thermal Engineering》2009,29(8-9):1440-1446
Economic evaluation of different energy supply systems (district or local heating by natural gas) in Serbia is considered in this paper. According to variety of Serbian settlements (in density, size and layout of buildings) model which has ability to represent their different characteristics is formed. Model is based on identification of smaller urban areas with identical or similar characteristics and their representations with one of predefined nominal urban areas. For various nominal urban areas preferred type of energy supply system was selected. Obtained results formed matrix of preferred type of energy supply system (district or local heating) for different urban structures. This models’ matrix could be simple and useful tool for initial decision about energy supply system. 相似文献
50.
Dejan Slobodan Aleksić Dragan S. Janković Leonid V. Stoimenov 《The International Journal of Advanced Manufacturing Technology》2012,59(1-4):397-412
Traditional configuration-based product family modeling techniques do not yield favorable solutions for modeling the product families with the dominant product topology variations. This paper presents the case study for the modeling of variations of the product configuration, parameters, and topologies in mass production of custom windows and doors in a one-of-a-kind production (OKP) company. The case study is based on the object-oriented product family modeling framework we developed for OKP which is characterized by the dominant product variation by topology. The problem of variation in topology in our framework is solved by the manual model transformation in the computer-aided design module which creates a new metamodel of products with the desired topology and which is the basis for a further, automatic model transformation. Usage of our framework has a positive effect on the level of the product customizations and shortening of the leading time which helps OKP companies in obtaining a better position at the market. Our software solution for the designing and manufacturing of custom windows and doors based on our framework is implemented in more than 300 mostly small- and medium-sized enterprises. It proves our concept which can be used for the realization of the information systems for computer-aided one-of-a-kind production in the companies with a different production plan. 相似文献