توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقاله‌های نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده می‌شوند.
۱Influence of different stacking methods and magnetization direction on the power loss in 3% silicon iron core material
نویسنده(ها):
اطلاعات انتشار: هجدهمین کنفرانس بین المللی برق، سال
تعداد صفحات: ۱۲
Reducing loss in laminated cores during ac magnetization is the aim of steel manufacturers as well as the wish of the users. A microprocessor controlled system for magnetizing and measuring the characteristics of magnetic materials was employed to calculate the losses and other magnetic properties of electrical steel material. The characteristics of 0.27 mm thick high permeability grain oriented 3% siliconiron, "Unisil – H" material, have been studied at large angles of magnetization to the rolling direction over the range during the magnetization process, was measured in different stacking units of Unisil–H materials. It has been established that the magnetization angle to the rolling direction is the main factor which controls the magnitude of normal flux density and resulting loss. The angle of 0o shows very low losses and also low normal flux density, because of the low reluctance magnetic path along this, the rolling direction. The effect of surface scratching on the normal flux density and power loss was investigated. Static domains were observed by using a Bitter Technique system. A decrease in the main domain wall spacing tended to reduce the power loss, whereas wall deviation from the rolling direction has a major effect on increasing the normal flux and eddy current loss. The comparative measurement of the localized power loss and normal flux density over an area showed a reasonable correlation with the observed static domain configuration in the Unisil – H material. The effects of different stacking methods and different magnetization direction on the power loss, due to the normal flux, were investigated by conducting a systematic comparison between five different stacking methods. The stacking method and number of strips per stacking unit has an important effect on controlling the normal flux and
power loss particularly at the T–joint and corners in 3–phase laminated cores. The low nominal loss and low magnitude of normal flux density materials are preferred in laminated transformer cores, because of low building factor. It was found that low magnetic reluctance along the magnetizing direction decreased normal flux density and eddy current loss, consequently improving the building factor.<\div>

۲Optimum design & operation of power transformers
نویسنده(ها):
اطلاعات انتشار: هفدهمین کنفرانس بین المللی برق، سال
تعداد صفحات: ۱۰
Reducing Building factor and loss in laminated cores during ac magnetization is the aim of steel manufacturers as well as the wish of the user. A microprocessor controlled system for magnetizing and measuring the characteristics of magnetic materials was employed to calculate the losses and the other magnetic properties of electrical steel materials. The power loss of the transformer cores is usually higher than nominal loss of the core materials, and measured in the Epstein square or the single strip tester. The ratio of the core loss to the nominal loss is termed the building factor, B.F. The B.F. ranges from 1.2 to 1.8 or more depending on the magnetic properties of the core material and the design of a magnetic circuit. The academic as well as economic importance of the B.F. has been highlighted as the nominal loss of the core material improved.
Laser scribing, surface scratching with a ball point pen, creating lines using spark ablation, creating scratches with special small cylinders, or stress relief each have a large impact on the better behaviour and the homogenisation of the passing flux and as a result decreasing of the loss
in the created core. In the design of the shape and the size of the core for instance choosing a suitable width to fit transformer windows and well sized angles for cutting sheets for T Joints and corners are worthy factors to be considered when reducing the B.F. and are also very important issues in increasing efficiency. Choosing a core with a suitable permeability for the middle limb in order to equal it's reluctance to that of the ending limb will homogenize the flux density in all parts of the core, minimizing the related loss and thus increasing efficiency. It must be considered that maximum efficiency usually occurs when iron loss equals the copper loss and the load has a suitable and standard value. The full load power loss can also be reduced by working on core creation designs. At last choosing a suitable usage for the transformer, considering the fact that the most efficiency can be reached through a particular percentage of the full load leads us to our aim of increasing efficiency. For example some transformers have their maximum efficiency under a mean of their full load, whereas power transformers show full efficiency in taking values near the whole full load.<\div>

۳Factors Affecting Normal Flux and Iron Loss in Laminated Cores
نویسنده(ها):
اطلاعات انتشار: چهارمین همایش کیفیت و بهره وری در صنعت برق، سال
تعداد صفحات: ۱۲
This paper presents experimental evidence that four types of magnetic laminated core materials of grain oriented 3% silicon–iron cut and magnetized at 0o to their rolling direction and one type of amorphous material (POWERCORE) ffects the magnitude of the normal flux density distribution transfer between them. Stacks of laminations were agnetized at 50Hz between 1.0 and 1.8 T and the normal flux was found to vary from about 0.5 to 1.2 mT. The flux transfer in any group of samples could vary by as much as 100% according to the different types of materials used with
.possible consequential differences in the power loss due to associated inplane eddy currents.<\div>

۴A New Correlation For Predicting Hydrate formation temperature Using Artificial neural network
اطلاعات انتشار: اولین همایش ملی توسعه تکنولوژی در صنایع نفت، گاز و پتروشیمی، سال
تعداد صفحات: ۴
Gas hydrates are a costly problem when they plug oil and gas pipelines. The best way to determine the Hydrate Formation Temperature (HFT) and pressure is to measure these conditions experimentally for every gas system. Since this is not practical in terms of time and money, correlations are the other alternative tools. There are a few numbers of correlations for specific gravity method to predict the hydrate formation. As the hydrate formation temperature is a function of pressure and gas gravity, an empirical correlation is presented based on the Hammerschmidt correlation for predicting the hydrate formation temperature. In order to obtain a new proposed correlation, 357 experimental data points have been collected from gas–gravity curves. This correlation is programmed and assessed with respect to its capabilities to match experimental data published in the literature under varying system conditions (i.e. temperature, pressure, and composition). The LINGO software has been employed for statistical analysis of the data. Accuracy of our correlation is more accurate than the Hammerschmidt correlation. In order to establish a method to predict the hydrate formation temperature, a new neural network has also been developed with the BP (back propagation) method. This neural network (IPS) model enables the user to accurately predict hydrate formation conditions for a given gas mixture, without having to do costly experimental measurements. It is found that the IPS neural network and the AUT correlation have the same results and are more accurate than the empirical correlation.<\div>

۵Toward Integration of Human Resource Management (HRM) and Systems Thinking (ST)
اطلاعات انتشار: نخستین کنفرانس ملی رویکرد سیستمی در ایران، سال
تعداد صفحات: ۱۳
Systems thinking have been applied to many aspects of organization, and this paper examines the potential for using these ideas in the area of human resource management (HRM).An overview of modern HRM ideas reveals that motivation and leadership are considered important factors for effective management. Learning –based motivation using reinforcement has ethical implications which may appear good for efficiency but not for individuals. Traditional motivation methods which involve personal goal fulfillment encourage defensiveness and cover up. Real learning and real problem solving come from openness, valid information, and confronting of viewpoints. Therefore the manager requires approaches which can challenge the prevailing ideology. This study finds that systems methodologies can help HRM to produce an efficient, effective, profitable and ethically fair organization. However, this requires using a variety of systems approaches based on different paradigmatic assumptions to help the different human interests. Critical awareness must be brought into group leadership, motivation and interactions. Challenging of ideas can avoid obstructing learning and can improve decision making. This research recommends that HRM would be improved by adopting a critical systemic perspective.<\div>

۶Toward Integration of Project management and systems engineering:A Comprehensive approach
نویسنده(ها): ،
اطلاعات انتشار: نخستین کنفرانس ملی رویکرد سیستمی در ایران، سال
تعداد صفحات: ۱۱
The main characteristics of complicated projects are uncertainty and complexity in technical tasks and interdependency of them which highlights the need of systems engineering. In the current paper, we tried to develop a framework that uses both systems engineering and project management advantages to improve the probability of project success. In this regard after investigating the detailed processes of project management lifecycle and systems engineering lifecycle a novel framework named PSLM (project system lifecycle management) tries to show the detailed interface between the two areas of knowledge<\div>

۷Investment model in knowledge management applying system dynamics approach
اطلاعات انتشار: هفتمین کنفرانس ملی و اولین کنفرانس بین المللی مدیریت دانش، سال
تعداد صفحات: ۱۳
Knowledge management (KM) as an important aspect of organizational success is a matter of interest for all organizations. KM is not a stand–alone process and instead of considering technical aspects, currently its relation with other issues has been realized. Thus, the purpose of this study is to present a dynamic and heuristicmode for creating KM, organizational learning and innovation, human capital and also considering amount of investment on KM which dynamic interactions arepresented through system dynamics. Research systemic model has been simulated using Vensim DSS software. The results truly show the methods of KM creation in organization, use of explicit and implicit knowledge for growing learning organization. It also analyzes how an organization should invest on KM and R&D. Managers, policy makers and investors can use and employ the results of this study.<\div>

۸The survey of effect of Kombucha tea on activity of hepatic UDPGT enzyme in mice
اطلاعات انتشار: Advanced Herbal Medicine، اول،شماره۲، ۲۰۱۵، سال
تعداد صفحات: ۱۴
Background and aims: Kombucha is an ancient food and healing source with Asian origin. Kombucha consists of a wide range of acids, including vitamin C, organic materials, enzymes, and B–group vitamins, which has provided it with immense value. This study was aimed to investigate the effects of Kombucha tea consumption on hepatic UDPGT enzyme in mice. Methods: In this experimental study, 21 small male albino mice and CD–1 genus were used. Albino mice species were purchased from serum Institute in Karaj Hisarak. Mice with a weight between 18 to 25 g were selected. Animals were kept in triplex group in polycarbonate cages. Animal rooms were equipped with air–conditioner. Ambient temperature was retained at about 22°C, and humidity 50%. A light cycle was set at 12 hours brightness and 12 hours darkness. The intensive diet was used that produced by animal Pars feeds for mice feeding. Finally, UDPGA enzyme was measured. Results: Consumption of kombucha tea for seven days of experiment caused a significant increase in enzyme activity in mice liver UDPGT compared to the negative control group, from the first day until the seventh day of experiment. Conclusion: Kombucha tea induced the UDPGT enzyme; thus, it accelerated the detoxification of the body and should be cautioned about simultaneous administration of this beverage with some drugs (such as steroids, acetaminophen, cardio– vascular medicine, etc.) that they metabolize through conjugation. Medical community in this case must be justified and their opinion must be considered when people are using this tea. Finally, kombucha tea consumption did not increase the liver weight. So, UDPGT induction was not the reason of liver weight increase.
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