Magneto-electric properties of magnetic field sensors fabricated using AlGaN/GaN heterostructures for harsh environments

豊橋技術科学大

High-performance near-infrared photodetector based on nano-layered MoSe2

In recent years, the integration of two-dimensional (2D) nanomaterials, especially transition metal chalcogendies (TMCs) and dichalcogendies (TMDCs), into electronic devices have been extensively studied owing to their exceptional physical properties such as high transparency, strong photoluminescence, and tunable bandgap depending on the number of layers. Herein, we report the optoelectronic properties of few-layered MoSe2-based backgated phototransistor used for photodetection. The photoresponsivity could be easily controlled to reach a maximum value of 238 AW–1 under near-infrared light excitation, achieving a high specific detectivity D∗ = 7.6×10** cmHz*/1W3* . Few-layered MoSe2 exhibited excellent optoelectronic properties as compared with those reported previously for multilayered 2D material-based photodetectors, indicating that our device is one of the best high-performance nanoscale near-infrared photodetector based multilayered two-dimensional materials

Imposed Switching Frequency Direct Torque Control of Induction Machine Using Five Level Flying Capacitors Inverter

The paper proposes a new control structure for sensorless induction motor drive based on a five-level voltage source inverter (VSI). The output voltages of the five-level VSI can be represented by nine groups. Then, the amplitude and the rotating velocity of the flux vector can be controlled freely. Both fast torque and optimal switching logic can be obtained. The selection is based on the value of the stator flux and the torque. This paper investigates a new control structure focused on controlling switching frequency and torque harmonics contents. These strategies, called ISFDTC, indeed combines harmoniously both these factors, without compromising the excellence of the dynamical performances typically conferred to standard DTC strategies. The validity of the proposed control technique is verified by Matlab/Simulink. Simulation results presented in this paper confirm the validity and feasibility of the proposed control approach and can be tested on experimental setup.Peer reviewe

Field behavior near the edge of a microstrip antenna by the method of matched asymptotic expansions

International audienceThe cavity model is a wide-spread powerful empirical approach for the numerical simulation of microstrip antennas. It is based on several hypotheses assumed a priori: a dimension reduction in the cavity, that is, the zone limited by a metallic patch and the ground plane in which is fed the antenna, supplied by the additional condition that the open sides of the cavity act as magnetic walls. An additional important assumption of this model consists in an adequate description of the singular field behavior in the proximity of the edge of the patch. A simplified two-dimensional problem incorporating the main features of the field behavior near the edge of the patch and inside the cavity is addressed. The method of matched asymptotic expansions is used to carry out a two-scale asymptotic analysis of the field relatively to the thickness of the cavity. All the empirical hypotheses at the basis of the derivation of the cavity model can thus be recovered. Proved error estimates are given in a simplified framework where the dielectric constants of the substrate are assumed to be 1 in order to avoid some unimportant technical difficulties

Enhancing of CH3NH3SnI3 based solar cell efficiency by ETL engineering

Solar cells based on organic-inorganic perovskites (PVK) are the subject of several researches in laboratories around the world. One of the most promising hybrid perovskite is the methylammonium lead tri-iodide MAPbI3 that is suitable for sun light harvesting. But the MAPbI3 is a toxic material, so in this paper is proposed another nature friendly candidate which is the methylammonium tin tri-iodide MASnI3. The proposed material is inserted into an n-i-p heterojunction solar cell which structure is electron transport layer (ETL)/PVK/hole transport layer (HTL). The used HTL is the PEDOT: PSS in combination with one of two ETLs which are the PCBM and the IGZO. Simulation efforts using 1D SCAPS was carried. It is found that IGZO ETL based solar cell yields a higher power conversion efficiency (PCE) compared with PCBM ETL based solar cell in the same thickness. 

Caractérisation hydrogéochimique des eaux souterraines du complexe aquifère Morsott-Laouinet (Région Nord de Tébessa, Sud-Est algérien)

L’analyse des eaux souterraines de l’aquifère superficiel Plio-Quaternaire, pose à nouveau la question de l’importance des faciès gypso-salifères dans la région de Morsott-Laouinet au Nord de Tébessa dans le Sud Est algérien. Ces faciès sont représentés par des affleurements triasiques en surface et par la présence d’un substratum marno-salifère en profondeur. Les analyses chimiques de la totalité des puits de la région le confirment.La salinité des eaux est très variable et généralement élevée. La  conductivité électrique de l’eau oscille entre 1154 μS cm-1 et 23800 μS cm-1 avec une concentration élevée d’amont en aval dans le sens de l’écoulement qui se fait du Sud vers le Nord. Les faciès chimiques extrêmes sont le bicarbonaté calcique et le chloruré sodique avec une prédominance de ce dernier. Les teneurs en chlorures et en sodium pouvant atteindre localement les valeurs respectives de 8145 mg l-1 et 3988 mg L-1. La comparaison de la teneur en chlorures avec le reste des éléments majeurs et le strontium, montre que la salinité des eaux souterraines de la plaine de Morsott-Laouinet possède deux origines possibles : la dissolution-précipitation de la roche aquifère et du substratum et l’échange de base entre le sodium et les éléments qui lui sont semblables.Mots-clés : Trias, aquifère, salinité, saturation, Morsott-Laouinet

Matching of Asymptotic Expansions for a 2-D eigenvalue problem with two cavities linked by a narrow hole

One question of interest in an industrial conception of air planes motors is the study of the deviation of the acoustic resonance frequencies of a cavity which is linked to another one through a narrow hole. These frequencies have a direct impact on the stability of the combustion in one of these two cavities. In this work, we aim is analyzing the eigenvalue problem for the Laplace operator with Dirichlet boundary conditions. Using the Matched Asymptotic Expansions technique, we derive the asymptotic expansion of this eigenmodes. Then, these results are validated through error estimates. Finally, we show how we can design a numerical method to compute the eigenvalues of this problem. The results are compared with direct computations

Rocking seismic excitations effect on inelastic response of reinforced concrete building with soft-story

Well-known problem with seismic design codes is that it does not take into account the rotational earthquake components. Only Eurocode 8, in Part 6, offers response spectra of rotational accelerations for the seismic design of slender and tall structures such as towers, masts, and chimneys. However other structures such as high-rise buildings or buildings with soft-story could be influenced by the rocking seismic components. Recording rotational ground motions can only be considered in its infancy. One approach to solve this problem involves the use of computed rotational accelerograms. The effect of rotational components on the structural response is still insufficiently explored. This paper investigate the influence of the rocking seismic components on the structural response of reinforced concrete structures with soft-story. Two types of rotational ground motions are used: recorded and computed accelerograms. Under combined translational and rotational accelerograms, the results are collected in terms of themaximum of inter-story drifts, story displacements, and internal forces. Nonlinear time history analysis shows clearly that the contribution of the rocking seismic components can be significant in structural response such as displacement (up to 60%), inter-story drift (up to 32%), and axial force (up to 8%). The existence of soft-story in the structure can amplify this contribution up to 25% compared to a structure without soft-story. Therefore, the effects of horizontal rotational components should not be ignored by the seismic codes and require further investigations

Rocking seismic excitations effect on inelastic response of reinforced concrete building with soft-story

Well-known problem with seismic design codes is that it does not take into account the rotational earthquake components. Only Eurocode 8, in Part 6, offers response spectra of rotational accelerations for the seismic design of slender and tall structures such as towers, masts, and chimneys. However other structures such as high-rise buildings or buildings with soft-story could be influenced by the rocking seismic components. Recording rotational ground motions can only be considered in its infancy. One approach to solve this problem involves the use of computed rotational accelerograms. The effect of rotational components on the structural response is still insufficiently explored. This paper investigate the influence of the rocking seismic components on the structural response of reinforced concrete structures with soft-story. Two types of rotational ground motions are used: recorded and computed accelerograms. Under combined translational and rotational accelerograms, the results are collected in terms of themaximum of inter-story drifts, story displacements, and internal forces. Nonlinear time history analysis shows clearly that the contribution of the rocking seismic components can be significant in structural response such as displacement (up to 60%), inter-story drift (up to 32%), and axial force (up to 8%). The existence of soft-story in the structure can amplify this contribution up to 25% compared to a structure without soft-story. Therefore, the effects of horizontal rotational components should not be ignored by the seismic codes and require further investigations