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Nonlinear and Negative Resistance in Loose Electrical Contacts Dark Bridge
Hiromichi Kubota,
Shunsuke Sasaki,
Hiroyuki Ishida,
Tasuku Takagi
Issue:
Volume 1, Issue 1, July 2013
Pages:
1-4
Received:
2 May 2013
Published:
10 June 2013
Abstract: The dark bridge in loose electrical contacts was investigated, which grew up when the contact gap was increased a little with micron by micron. The dark bridge was watched by microscopic camera along with measurement of voltage-current (V-I) relationship. At very small gap (less than 19μm for iron (Fe) contacts but different from materials), the V-I characteristics were linear, which is normal, but more than the 20~30μm, the non-linear relationship appeared and finally the negative resistance was observed. Experimental growth of dark bridge was shown in case of Pd. The nonlinear and negative resistance phenomena were tested for Fe. The resistance was analyzed and showed that it goes to negative one after crossing zero from positive region.
Abstract: The dark bridge in loose electrical contacts was investigated, which grew up when the contact gap was increased a little with micron by micron. The dark bridge was watched by microscopic camera along with measurement of voltage-current (V-I) relationship. At very small gap (less than 19μm for iron (Fe) contacts but different from materials), the V-...
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A plasma Formation in Pulsed Coaxial Gun at Continuously Filling Regime
A. M Zhukeshov,
A. U Amrenova,
A. T Gabdullina,
B. M Ibraev
Issue:
Volume 1, Issue 1, July 2013
Pages:
5-9
Received:
14 May 2013
Published:
10 June 2013
Abstract: In work presented the results of researches of plasma flow formation and propagate in the electrodynamics pulsed gun. Experimental researches carried out on the basis of pulse plasma accelerator CPU-30 with a coaxial symmetric geometry electrodes. It was shown, that structure of the flow significantly depends on initial operating pressure of working gas, and specify for “continuously filled” regime. The data on dynamics of plasma acceleration, obtained in previous studies was refined. The role of plasma internal electric field and acceleration peculiarities on differ pressure of initial gas are discuss.
Abstract: In work presented the results of researches of plasma flow formation and propagate in the electrodynamics pulsed gun. Experimental researches carried out on the basis of pulse plasma accelerator CPU-30 with a coaxial symmetric geometry electrodes. It was shown, that structure of the flow significantly depends on initial operating pressure of worki...
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Statistical tuning of walfisch-bertoni pathloss prediction model based on building and street geometry sensitivity parameters in built-up terrains
Isabona Joseph,
Babalola Michael
Issue:
Volume 1, Issue 1, July 2013
Pages:
10-17
Received:
25 May 2013
Published:
30 June 2013
Abstract: One of the underlying difficulties with the application of a prediction pathloss model for any environment is that no two areas are identical in the composition of the buildings and terrain. A pathloss model developed by Walfisch-Bertoni considers the impact of rooftops and building heights by using diffraction to predict average signal strength loss at street level. However, the error between the average path loss predicted by the model and that observed in practice will be smallest when the propagation environment conforms closely with the models assumptions (i.e. those urban environments exhibiting minimal variation in the height and separation of buildings). In particular, any building height variations can be expected to cause a significant error in the model predictions. Firstly, in this paper, we demonstrate the sensitivity impact of varying certain parameters on the performance W/B model in the study environments. The goal is to give the user an idea of the value associated with altering parameters that are in fact adjustable and showing the significance of the unchangeable parameters in the loss calculations. Secondly, a new statistical tuning method is proposed by extending the technique of Walfisch- Bertoni model which is now valid for generalized conditions in the CDMA2000 signal propagation environments. The results showed that tuned pathloss data agree strongly with measured data in the different study locations.
Abstract: One of the underlying difficulties with the application of a prediction pathloss model for any environment is that no two areas are identical in the composition of the buildings and terrain. A pathloss model developed by Walfisch-Bertoni considers the impact of rooftops and building heights by using diffraction to predict average signal strength lo...
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Experimental and Theoretical Study of Parasitic Effects in InAlAs/InGaAs/InP HEMT’s
S. Bouzgarrou,
M. M. Ben Salem,
A. Kalboussi,
A. Souifi
Issue:
Volume 1, Issue 1, July 2013
Pages:
18-24
Received:
21 May 2013
Published:
30 June 2013
Abstract: A detailed study of electrically active defects present in InAlAs/InP heterostructure and InAlAs/InGaAs/InP High Electron Mobility Transistors (HEMTs) grown by metal organic chemical vapor deposition (MOCVD) is presented. Current and capacitance Deep Level Transient Spectroscopy (I-DLTS and C-DLTS) techniques are used for the identification of active electrical defects. A notable correlation between deep levels observed by I -DLTS and C-DLTS results and the contribution of parasitic effects (Kink and Hysteresis effects) on output characteristics was evidenced. A new model for Kink effect is presented on InAlAs / InGaAs / InP HEMT’s. This model uses a new polynomial dependence of sheet carrier concentration, on bias and temperature of device structure to calculate Ids – Vds characteristics. The simulation model enables us to confirm that the Kink parasitic effect in Ids – Vds characteristics is strongly correlated by trapping and detrapping mechanisms. Experimental and theoretical results obtained by the new model are in good agreement.
Abstract: A detailed study of electrically active defects present in InAlAs/InP heterostructure and InAlAs/InGaAs/InP High Electron Mobility Transistors (HEMTs) grown by metal organic chemical vapor deposition (MOCVD) is presented. Current and capacitance Deep Level Transient Spectroscopy (I-DLTS and C-DLTS) techniques are used for the identification of acti...
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Study of Radiation in Spherical Media Using Moment Method
Issue:
Volume 1, Issue 1, July 2013
Pages:
25-32
Received:
3 June 2013
Published:
10 July 2013
Abstract: A moment technique is presented to improve the performance of the discrete ordinates method when solving the radiation problems in spherical media. In this approach the angular derivative term of the discretized 1-D radiative transfer equation is derived from an expansion of the radiative intensity on the basis of angular moments. The set of resulting differential equations, obtained by the application of the SN method associated to moment method, is numerically solved using the boundary value problem with the finite difference algorithm. Results are presented for the different independent parameters. Numerical results obtained using the moment approximation compare well with the benchmark approximate solutions. Moreover, the new technique can easily be applied to higher-order SN calculations.
Abstract: A moment technique is presented to improve the performance of the discrete ordinates method when solving the radiation problems in spherical media. In this approach the angular derivative term of the discretized 1-D radiative transfer equation is derived from an expansion of the radiative intensity on the basis of angular moments. The set of result...
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