scholarly journals Quasi-Boundary Method for Design Consideration of Resonant DC-DC Converters

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6153
Author(s):  
Nikolay Hinov

The paper presents a new unified method for designing the two basic types of serial resonant DC-DC converters (series and with a parallel-loaded capacitor). The method is based on the use of a simplified generalized approach for the analysis of this type of power electronic devices. It is characterized by the fact that regardless of the specific operating mode, with a control frequency below or above the resonant of the series resonant circuit to determine the relationship between input and output voltage or current, it is assumed that the converter operates in resonance. In this sense, it is called a quasi-boundary method for analysis and design. The use of the quasi-boundary method significantly accelerates and facilitates the design of the considered power circuits, which is very useful for the purposes of engineering practice, as well as in the training of power electronics. The applicability of this approach is proven by the methods of mathematical modeling and computer simulations.

Author(s):  
A. Nakajima ◽  
K. Oku ◽  
J. Nishidai ◽  
T. Shiraishi ◽  
Y. Ogihara ◽  
...  

2016 ◽  
Vol 78 (5-5) ◽  
Author(s):  
J. D. Nyuin ◽  
M. J. Md Noor ◽  
Y. Ashaari ◽  
C. Petrus ◽  
A. Albar

Conventional analysis and design of shallow foundation are based on the assumption that the soil is under fully saturated condition. However, shallow foundations are typically constructed near the ground surface where the soil is under partially saturated condition. Therefore, more research to investigate the behaviour of shallow foundation in unsaturated soil is very essential in order to aid engineers in making good analysis and design. This paper presents a series of laboratory footing tests conducted on unsaturated sandy soil. A specially designed test tank was fabricated for the test. Square footings of two different sizes (100 mm x 100 mm and 150 mm x150 mm) were used and loaded on Rawang sand which has residual suction value of 10 kPa. The measured values of matric suction of the soil in the test tank were in the range of 0 to 30 kPa. Based on the results, it was observed that bearing capacities of shallow foundation under fully saturated condition were the lowest compared to soil under unsaturated conditions. The highest values were measured at matric suction equals to residual suction (i.e 10 kPa). Furthermore, the relationship between the bearing capacities of shallow foundation with the matric suction was observed to be non-linear.    


2012 ◽  
Vol 229-231 ◽  
pp. 495-498
Author(s):  
Hui Xin Liu ◽  
Xian Min Yang ◽  
Cheng Tao Li ◽  
Xiang Cheng

There is a common problem during kill a well, which is how to quickly and accurately control the surface casing pressure according to the requirements for killing a well. A step-by-step exploration process is employed on operation sites. Continuously adjusting throttle valve to acquire surface casing pressure may lead to failure of kill operation because of its long time and low control accuracy. Obviously, if the calculation problems of throttling drawdown can be resolved,the relationship between drawdown and throttle valve opening can be found and the course of explorating can be converted into a straight course.Then the success rate of killing well can be improved. More importantly, this can make automatic controll of surface casing pressure possible. The paper built the calculation method of throttling pressure drop by theoretical analysis and verified the calculation method by adopting it into field test. The result has showed that the calculation method of throttling pressure drop coincides with experimental results and it can be used in engineering practice.


2010 ◽  
Vol 25 (8) ◽  
pp. 2142-2149 ◽  
Author(s):  
Sang-Hoon Park ◽  
So-Ri Park ◽  
Jae-Sung Yu ◽  
Yong-Chae Jung ◽  
Chung-Yuen Won

2001 ◽  
Author(s):  
B. M. Fichera ◽  
R. L. Mahajan ◽  
T. W. Horst

Abstract Accurate air temperature measurements made by surface meteorological stations are demanded by climate research programs for various uses. Heating of the temperature sensor due to inadequate coupling with the environment can lead to significant errors. Therefore, accurate in-situ temperature measurements require shielding the sensor from exposure to direct and reflected solar radiation, while also allowing the sensor to be brought into contact with atmospheric air at the ambient temperature. The difficulty in designing a radiation shield for such a temperature sensor lies in satisfying these two conditions simultaneously. In this paper, we perform a computational fluid dynamics analysis of mechanically aspirated radiation shields (MARS) to study the effect of geometry, wind speed, and interplay of multiple heat transfer processes. Finally, an artificial neural network model is developed to learn the relationship between the temperature error and specified input variables. The model is then used to perform a sensitivity analysis and design optimization.


Author(s):  
Carmel Majidi ◽  
Mikko Haataja ◽  
David J. Srolovitz

The development of self-powered electronic devices is essential for emerging technologies such as wireless sensor networks, wearable electronics, and microrobotics. Of particular interest is the rapidly growing field of piezoelectric energy harvesting (PEH), in which mechanical strains are converted to electricity. Recently, PEH has been demonstrated by brushing an array of piezoelectric nanowires against a nanostructured surface. The piezoelectric nanobrush generator can be limited to sub-micron dimensions and thus allows for a vast reduction in the size of self-powered devices. Moreover, energy harvesting is controlled through contact between the nanowire tips and nanostructured surface, which broadens the design space to a wealth of innovations in tribology. Here we propose design criteria based on principles of contact mechanics, elastic rod theory, and continuum piezoelasticity.


Author(s):  
Dušan Krokavec ◽  
Anna Filasová

The generalized interval observer design conditions for continuous-time Metzlerian Takagi-Sugeno systems are presented in the paper. Attention is focused on the analysis and design guaranteeing the asymptotic convergence of the interval observer error and positivity of interval observer state. The relationship between the nonnegativity of the observer gains and the corresponding positive observer state attractiveness is also shown. The method presented extends and generalizes the results that recently appeared in the literature.


1989 ◽  
Vol 109 (2) ◽  
pp. 130-130
Author(s):  
Toshihiko Tanaka ◽  
Hiroharu Fugou ◽  
Hirofumi Akagi ◽  
Akira Nabae

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