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type:Journal Article, This paper presents a research work aimed to detect previously-undetected faults, either Write Disturb Faults (WDFs) or Deceptive Read Destructive Faults (DRDFs) or both in March Algorithm such as MATS++(6N), March C-(10N), March SR(14N), and March CL(12N). The main focus of this research is to improve fault coverage on Single Cell Faults as well as Static Double Cell Faults detection, using specified test algorithm. Transition Coupling Faults (CFtrs), Write Destructive Coupling Faults (CFwds) and Deceptive Read Destructive Faults (CFdrds) are types of faults mainly used in this research. The experiment result published in [1] shows BIST (Built-In-Self-Test) implementation with the new algorithm. It provides the same test length but with bigger area overhead, we therefore proposed a new 14N March Test Algorithm with fault coverage of more than 95% using solid 0s and 1s Data Background (DB). This paper reveals the design methodology to generate DB covers all memories function by applying non-transition data, transition data, and single read and double read data. The automation hardware was designed to give the flexibility to the user to generate other new March Algorithm prior to the selected algorithm and analyzed the performance in terms of fault detection and power consumption., source:http://www.jatit.org/volumes/Vol47No1/fourtyseventh_volume_1_2013.php

type:Journal Article, Bismuth‐based solar cells have been under intensive interest as an efficient non‐toxic absorber in photovoltaics. Within this new family of semiconductors, we herein report a new, long‐term stable copper bismuth iodide (CuBiI4). A solutionprocessed method under air atmosphere is used to prepare the material. The adopted HI‐assisted dimethylacetamide (DMA) co‐solvent can completely dissolve CuI and BiI3 powders with high concentration compared with other organic solvents. Moreover, the high vapor pressure of tributyl phosphate, selected for the solvent vapor annealing (SVA), enables complete low‐temperature (≤70°C) film preparation, resulting in a stable, uniform, dense CuBiI4 film. The average grain size increases with the precursor concentration, greatly improving the photoluminescence lifetime and hall mobility; a carrier lifetime of 3.03 ns as well as an appreciable hall mobility of 110 cm2V−1s−1 were obtained. XRD illustrates that the crystal structure is cubic (space group Fd3m) and favored in the [111] direction. Moreover, the photovoltaic performance of CuBiI4 was also investigated. A wide bandgap (2.67 eV) solar cell with 0.82% power conversion efficiency is presented, which exhibits excellent long‐term stability over 1008 h under ambient conditions. This air‐stable material may give an application in future tandem solar cells as a stable short‐wavelength light absorber., source:https://doi.org/10.1002/cssc.201800815

type:Journal Article, Lead-based perovskite solar cells have gained ground in recent years, showing efficiency as high as 20%, which is on par with that of silicon solar cells. However, the toxicity of lead makes it a nonideal candidate for use in solar cells. Alternatively, tin-based perovskites have been proposed because of their nontoxic nature and abundance. Unfortunately, these solar cells suffer from low efficiency and stability. Here, we propose a new type of perovskite material based on mixed tin and germanium. The material showed a band gap around 1.4–1.5 eV as measured from photoacoustic spectroscopy, which is ideal from the perspective of solar cells. In a solar cell device with inverted planar structure, pure tin perovskite solar cell showed a moderate efficiency of 3.31%. With 5% doping of germanium into the perovskite, the efficiency improved up to 4.48% (6.90% after 72 h) when measured in air without encapsulation.

type:Journal Article, Photoexcited electron injection dynamics from CsPbI3 quantum dots (QDs) to wide gap metal oxides are studied by transient absorption spectroscopy. Experimental results show under a low excitation intensity that ∼99% of the photoexcited electrons in CsPbI3 QDs can be injected into TiO2 with a size-dependent rate ranging from 1.30 × 1010 to 2.10 × 1010 s–1, which is also ∼2.5 times faster than that in the case of ZnO. A demonstration QD-sensitized solar cell based on a CsPbI3/TiO2 electrode is fabricated that delivers a power conversion efficiency of 5%.

type:Journal Article, Organic–inorganic hybrid perovskite solar cells have demonstrated unprecedented high power conversion efficiencies in the past few years. Now, the universal instability of the perovskites has become the main barrier for this kind of solar cells to realize commercialization. This situation can be even worse for those tin-based perovskites, especially for CsSnI3, because upon exposure to ambient atmosphere the desired black orthorhombic phase CsSnI3 would promptly lose single crystallinity and degrade to the inactive yellow phase, followed by irreversible oxidation into metallic Cs2SnI6. By alloying CsSnI3 with CsPbI3, we herein report the synthesis of alloyed perovskite quantum dot (QD), CsSn1–xPbxI3, which not only can be phase-stable for months in purified colloidal solution but also remains intact even directly exposed to ambient air, far superior to both of its parent CsSnI3 and CsPbI3 QDs. Ultrafast transient absorption spectroscopy studies reveal that the photoexcited electrons in the alloyed QDs can be injected into TiO2 nanocrystals at a fast rate of 1.12 × 1011 s–1, which enables a high photocurrent generation in solar cells.

type:Journal Article, Lead halide perovskites are attracting a great deal of interest for optoelectronic applications such as solar cells, LEDs, and lasers because of their unique properties. In solar cells, heat dissipation by hot carriers results in a major energy loss channel responsible for the Shockley–Queisser efficiency limit. Hot carrier solar cells offer the possibility to overcome this limit and achieve energy conversion efficiency as high as 66% by extracting hot carriers. Therefore, fundamental studies on hot carrier relaxation dynamics in lead halide perovskites are important. Here, we elucidated the hot carrier cooling dynamics in all-inorganic cesium lead iodide (CsPbI3) perovskite using transient absorption spectroscopy. We observe that the hot carrier cooling rate in CsPbI3 decreases as the fluence of the pump light increases and the cooling is as slow as a few 10 ps when the photoexcited carrier density is 7 × 1018 cm−3, which is attributed to phonon bottleneck for high photoexcited carrier densities. Our findings suggest that CsPbI3 has a potential for hot carrier solar cell applications., source:https://doi.org/10.1063/1.4991993

type:Journal Article, Perovskite quantum dots (QDs) as a new type of colloidal nanocrystals have gained significant attention for both fundamental research and commercial applications owing to their appealing optoelectronic properties and excellent chemical processability. For their wide range of potential applications, synthesizing colloidal QDs with high crystal quality is of crucial importance. However, like most common QD systems such as CdSe and PbS, those reported perovskite QDs still suffer from a certain density of trapping defects, giving rise to detrimental nonradiative recombination centers and thus quenching luminescence. In this paper, we show that a high room-temperature photoluminescence quantum yield of up to 100% can be obtained in CsPbI3 perovskite QDs, signifying the achievement of almost complete elimination of the trapping defects. This is realized with our improved synthetic protocol that involves introducing organolead compound trioctylphosphine–PbI2 (TOP–PbI2) as the reactive precursor, which also leads to a significantly improved stability for the resulting CsPbI3 QD solutions. Ultrafast kinetic analysis with time-resolved transient absorption spectroscopy evidence the negligible electron or hole-trapping pathways in our QDs, which explains such a high quantum efficiency. We expect the successful synthesis of the “ideal” perovskite QDs will exert profound influence on their applications to both QD-based light-harvesting and -emitting devices.

type:Journal Article, This research proposes a residential Photovoltaic-Power Conditioning Subsystem (PV-PCS) in a functional and stable power supply system with battery storage (Electric Vehicle [EV] storage etc.) to reduce PV output fluctuation. In PV power generation, PV power fluctuations caused by weather changes make it difficult to obtain stable power output. Further, it can then be expected that this adversely affects the power system. In this paper, functional power supply system model is constructed with power fluctuation suppression control system using bidirectional DC/DC converter and existing residential PCS and EV battery storage. Furthermore, simulation results of the electric battery power suppression element of the PV power fluctuation are also shown by using Simple Moving Average (SMA) control method to suppress PV power fluctuation. PV power suppression system using existing residential PCS has an advantage that can not only suppress the energy change during normal operation but can also construct the isolated power supply in an emergency case of power supply loss. In this emergency case, EV battery storage control provides the power to critical loads during utility outage. This feature is not available without storage. Also, effectiveness of PV-PCS interconnection stable power supply system with existing residential PCS in Japan was proposed. Moreover, a basic research of solar power generation amount of solar radiation estimation and the resulting simulation on information acquisition method of solar energy capacity using Geographic Information System (GIS) are presented.

type:Journal Article, Virtual inertia emulation could be regarded as an inevitable component of microgrids with renewable energy, enhancing microgrid inertia and damping properties. In applying this control technique, a phase-locked loop (PLL) is necessary to obtain the estimation of the system frequency data. However, the employment of PLL could cause larger frequency oscillation to the microgrid due to its dynamics. This issue would be exacerbated in a low-inertia microgrid driven by high renewable penetration, severely deteriorating the frequency stability. Thus, the effect of PLL with measurement delay is a critical issue in utilizing the virtual inertia control. To overcome such problem, this paper proposes a robust virtual inertia control for a low-inertia microgrid to minimize the undesirable frequency measurement effects, improving the microgrid frequency stability. The robust H ∞ control design using a linear fractional transformation (LFT) technique is used to develop the virtual inertia control loop, considering the dynamics of PLL with measurement delay and the uncertainties of system inertia and damping. The efficacy of the proposed H ∞ control method is compared to the conventional and optimum proportional-integral (PI)based inertia control. The results show that the H ∞ -based robust virtual inertia control is superior to both conventional virtual inertia control and optimum PI-based virtual inertia control against a wide range of microgrid operating conditions, disturbances, and parametric uncertainties.

type:Journal Article, The shoot-through phenomenon has not been fully discussed for high-power inverters with IGBTs. This is because a negative gate voltage is applied to IGBTs during off states. Recently, attention is paid to an improved gate driver with only a positive gate voltage in order to meet demands for simplification, integration, and reduction in power consumption as well as in cost of the gate driver. Moreover, the threshold voltage of the next-generation IGBT will decrease with microfabrication techniques of the gate structure. This will make the shoot-through phenomenon severer and degrade the inverter reliability with the next-generation IGBTs. The influence of the parasitic parameters in both the IGBT and circuit on the shoot-through mechanism has not been investigated so far.This paper clarifies the shoot-through mechanism and investigates the impact of the next generation IGBTs on the inverter reliability. The influence of the internal capacitance of IGBT including stray inductance on inverter reliability is experimentally confirmed., source:https://doi.org/10.1016/j.microrel.2017.06.087

type:Journal Article, Maintaining frequency stability of low inertia microgrids with high penetration of renewable energy sources (RESs) is a critical challenge. Solving this challenge, the inertia of microgrids would be enhanced by virtual inertia control-based energy storage systems. However, in such systems, the virtual inertia constant is fixed and selection of its value will significantly affect frequency stability of microgrids under different penetration levels of RESs. Higher frequency oscillations may occur due to the fixed virtual inertia constant or unsuitable selection of its value. To overcome such a problem and provide adaptive inertia control, this paper proposes a self-adaptive virtual inertia control system using fuzzy logic for ensuring stable frequency stabilization, which is required for successful microgrid operation in the presence of high RESs penetration. In this concept, the virtual inertia constant is automatically adjusted based on input signals of real power injection of RESs and system frequency deviations, avoiding unsuitable selection and delivering rapid inertia response. To verify the efficiency of the proposed control method, the contrastive simulation results are compared with the conventional method for serious load disturbances and various rates of RESs penetration. The proposed control method shows remarkable performance in transient response improvement and fast damping of oscillations, preserving robustness of operation.

type:Journal Article, Electrical transport properties of the nano-graphene oxide were investigated by measuring current-voltage characteristics in the wide temperature range of 15 K∼450 K. The n-GO is composed of nanometer-sized intact graphene-like sp2 domains embedded in the sp3 matrix which acts as a charge transport barrier between the highly conductive sp2 domains. The oxygen in the n-GO has the concentration of 4.43 at% in the form of oxygen functional groups. Below the conduction band, four discontinuous localized states with the activation energies of 1.92 meV, 3.27 meV, 5.54 meV, and 6.58 meV were observed. These activation energies decrease with decreasing oxygen concentration and increasing external electric field in the n-GO material. Moreover, we found that the direct tunneling of charge carrier through the sp3 barrier was a dominant transport mechanism for the n-GO material. Also, unlike the activation energy of charge carrier, the transport barrier was independent of both the concentration of the oxygen functional groups and external electric field. The transport barrier was mainly determined by insulation property of the sp3 structure., source:https://doi.org/10.1063/1.5116774

type:Journal Article, A highly flexible electrochemical supercapacitor electrode was developed with a novel metal oxide-reinforced nanofiber electrode by utilizing a solution-based electrospinning technique. The facile fabrication steps involved the introduction of metal precursors into a polymeric solution, which was subjected to an in situ electrospinning process. The electrospun polymeric web with metallic ingredients was then subjected to an oxidative stabilization process that induced the formation of metal oxide nanoparticles within the polymer structure. Finally, the metal oxide nanoparticles incorporated with nanofibers were obtained using a carbonization process, thus converting the polymer backbones into a carbon-rich conductive nanofiber structure. The fabricated nanofibers were decorated and implanted with metal oxide nanoparticles that had a surface-decorated structure morphology due to the solubility of the precursors in the reaction solution. The electrochemical performance of the fabricated metal oxide reinforced with nanofiber electrodes was investigated as an electrochemical system, and the novel morphology significantly improved the specific capacitance compared to a pristine carbon nanofiber membrane. As a result of the uniform dispersion of metal oxide nanoparticles throughout the surface of the nanofibers, the overall capacitive behavior of the membrane was enhanced. Furthermore, a fabricated free-standing flexible device that utilized the optimized nanofiber electrode demonstrated high stability even after it was subjected to various bending operations and curvatures. These promising results showed the potential applications of these lightweight, conductive nanofiber electrodes in flexible and versatile electronic devices.

type:Journal Article, We have succeeded in synthesizing filled skutterudite-type structure compounds GdRu4P12 and TbRu4P12 under high pressure. The magnetic properties of GdRu4P12 and TbRu4P12 have been studied by means of electrical resistivity, magnetic susceptibility, and magnetization measurements. Magnetic experiments suggest that the Gd and Tb ions in the compounds have trivalent state. The compound GdRu4P12 displays features that suggest the occurrence of antiferromagnetic ordering below TN=22 K. In TbRu4P12, thermal variation of magnetic susceptibility indicates the existence of two successive magnetic transitions (TN=20 K and T1=10 K). Magnetization up to 18 T exhibits two-step metamagnetic transitions below T1 for TbRu4P12., source:https://doi.org/10.1103/PhysRevB.62.11581, source:http://www.aps.org

type:Journal Article, By measuring the i−vi−v characteristics of Y3N@[C80]6− anionic solid at various temperatures and electric field strengths, four conducting phases with i∝vi∝v , i∝v2i∝v2 with low resistance, i∝v4i∝v4 and i∝v2i∝v2 with high resistance were observed. First, at temperatures below 100 K and field strengths below 30 Vcm−1Vcm−1 , the current passing through the sample was a linear function of the d.c. bias voltage due to free moving charges. Second, at the same field strengths, the trapped carrier was thermally activated with activation energies of 13.6 meV for temperature range of 100−250100−250 K and 88.7 meV for 250−450250−450 K. In this conducting phase, the carrier transport was governed by space charge limited conduction mechanism. Third, when the electric field increased from 30 to 120 Vcm−1Vcm−1 , the ii became a quartic function of the vv because the carrier mobility is a quadratic function of the field strength. A conducting phase with high resistance was observed at temperatures below 100 K. The trapped carrier was thermally activated with activation energies of 146.5 meV for temperature range of 100−250100−250 K and 288.5 meV for 250−450250−450 K. Finally, in the electric field strengths of 120−2000120−2000 Vcm−1Vcm−1 , a high resistance phase appeared in the anionic solid at temperatures below 100 K. The current was a quadratic function of the d.c. bias voltage, and the carrier mobility was independent of the field strength.

type:Journal Article, We have implemented a student note-sharing system, AirTransNote, that facilitates collaborative and interactive learning in conven- tional classrooms. With the AirTransNote system, a teacher can immediately share student notes with the class using a projection screen to enhance group learning. However, students tend to hesitate to share their notes, particularly when the notes contain embarrassing mistakes. Nevertheless, teachers want to focus on real mistakes students make while learning. We introduce an erase stroke detecting method for the student note-sharing system to reduce students’ discomfort regarding sharing mistakes, as well as to assist the teacher in finding mistakes. We collected and manually labeled free-style handwritten student notes. Based on the labeled notes, we extracted features for the erase symbols and deleted strokes. We have tested support vector machine techniques for classifying erase symbols and deleted strokes from typical handwritten notes., Knowledge-Based and Intelligent Information & Engineering Systems 19th Annual Conference, KES-2015, Singapore, September 2015 Proceedings, source:https://doi.org/10.1016/j.procs.2015.08.131

type:Conference Paper, The minimum trench edge termination length for various trench depth is theoretically determined to obtain universal curve for efficient design under considering trade-off relation with trench fabrication difficulty, cost and limitation specially for thin wafer IGBTs and diodes. This study unveils for the first time clear relationship between trench depth and termination length. We present practical design for each trench depth based on design curve considering trench filler material., 2012 24th International Symposium on Power Semiconductor Devices and ICs (ISPSD 2012), June 3-7, 2012, Bruges, Belgium

type:Journal Article, Electrical transport properties of the nanocrystalline Er3N@C80 with fcc crystal structure were characterized by measuring both temperature-dependent d.c. conductance and a.c. impedance. The results showed that the Er3N@C80 sample has characteristics of n-type semiconductor and an electron affinity larger than work function of gold metal. The Er3N@C80/Au interface has an ohmic contact behavior and the contact resistance was very small as compared with bulk resistance of the Er3N@C80 sample. The charge carriers in the sample were thermally excited from various trapped levels and both acoustic phonon and ionic scatterings become a dominant process in different temperature regions, respectively. At temperatures below 250 K, the activation energy of the trapped carrier was estimated to be 35.5 meV, and the ionic scattering was a dominant mechanism. On the other hand, at temperatures above 350 K, the activation energy was reduced to 15.9 meV, and the acoustic phonon scattering was a dominant mechanism. In addition, a polarization effect from the charge carrier was observed at low frequencies below 2.0 MHz, and the relative intrinsic permittivity of the Er3N@C80 nanocrystalline lattice was estimated to be 4.6 at frequency of 5.0 MHz.

Described are the design and characterisation of an ultra-low-power temperature level detector (TLD) and temperature sensor based on a silicon-on-insulator (SOI) CMOS integrated circuit (IC) for harsh environment applications. Since this IC is mainly for harsh environment applications (e.g. high temperatures and radiations), it has been designed and manufactured using the 1 µm high-temperature SOI-CMOS technology provided by X-FAB. The measured power dissipation of the TLD circuit is 9 µW at a supply voltage of 5 V and temperature of 27 °C, according to the measurement results of the manufactured design.

Experimental studies on the perpendicular magnetic anisotropy in amorphous TbCo prepared by rf sputtering have been carried out and the results obtained have been compared with those in other amorphous rare earth-transition metal films. it has been found that the perpendicular anisotropy of TbCo films greatly depends on a negative bias voltage applied to the substrate during sputtering. Because of their large magnetostriction, the anisotropy results from the planar stress due to the substrate constraint occupies considerably part in the whole perpendicular anisotropy in TbCo films. Annealing for one hour at 300℃ destroys the perpendicular anisotropy almost completely. Magnetostriction plays an important role in the magnetization process in amorphous films without crystalline anisotropy. However, few studies have been done on magnetostriction in amorphous films. Therefore, a cantilever capacitance apparatus has been set up for measuring the magnetostriction constant. It has been found that using a standard Fe0.40Ni0.60 film for calibration, this apparatus is accurate enough and very useful.

A mathematical approach for evaluating each sound power using sampled data of vehicle stream is described. By the Fourier transform theory, each frequency component of sampled sound power generated by moving n point sources can be expressed by a linear equation of n complex exponentials. Applying the Prony's method to above equation, both vehicle velocity and time when every vehicle passes at the front of the observation point can be determined numerically. And each sound power can be chosen in such a way that the sum of squared norm is minimized. The proposed method, based on the squared inversely proportional function as the intensity attenuating characteristic, has general applicability to problems where so-called inverse square law exists.

Recently ferromagnetic films with their magnetization perpendicular to the film plane have been investigated widely mainly due to their interest as a medium for the high density magnetic recording. The magnetization curve of these films is known to be changed from almost linear type without hysteresis to a large square hysteresis type by varying film thickness, temperature or film composition. In this paper, this change in the magnetization curve is shown to be explained by a modified Kooy-Enz theory, where the effect of the wall coercivity is taken into account. Our theory also interprets well the nucleation field at which the magnetization drops discontinuously from saturation.

The energy shifts of the parabolic conduction band-edge at 77 and 300K with doping the Te-donor in GaP were calculated in the nondegenerate system for the two cases ; unintentional and intentional compensations, using the two models proposed by Hwang abd by Mahan. The total parabolic shift △EM（△EH）, and the contributions of the exchangeinteraction △μex（△Ee） and of the Coulomb interaction △μed（△Ec） calculated by the Mahan's model (Hwang's model), increase with increasing donor concentration in the unintentional compensation system at 300K. △μex is smaller than △μed whereas △Ee is much larger than △Ec, and △μex < △Ee and △μed > △Ec. △EM agrees well the experimental parabolic shift △δ while △EH ＞ △δ. The energy gap narrowing △EG calculated by the Mahan's model is much larger than the experimental energy gap narrowing △EC. The results are interppretd as follows. △μex fairly estimate the exchange interaction since the Mahan's model takes account of the anisotropy and multivalley effects. △μed reasonably estimates the Coulomb interaction since the Mahan's model takes account of the self-consistent interaction energy of the elentron-screened donor system. The overestimation of the hole-electron correlathon energy may be a reason for △EG > △EO.

The method of simulation for the DLTS signal is described for the electron traps having a single sharp energy level and/or a broadened energy level in the p+n (or schottky) junction. From the result of the simulation for the sharp level, the effects of the parameters used for the simulation on the shapes of DLTS signals are demonstrated. The temperature and the half width of the DLTS peak depend systematically on all the parameters, while the height of the peak depends only on the ratio t1/t2 of the sampling times. The experimental DLTS signals are obtained for the GaP Schottky junctions before and after electron irradiation. There are two kinds of the experimental DLTS peaks in the irradiated GaP, one is the narrow peak which can be reproduced by the simulated curve for the sharp level, and the other is the broad peak which can be reproduced by the composed simulation curve for the broadened level. The level broadening is estimated by the simulation to be 0.134 eV for the defect introduced by the electron irradiation at 10MeV. It is suggested that the simple and very complex defects coexist in the irradiated GaP.

International audience, FDTD simulation of a Surface Acoustic Wave (SAW) RFID tag is presented. The simulated tag consists of a single-electrode Inter-digital Transducer (IDT) with ten electrodes and three single-electrode reflectors, printed on the surface of a 128°YX Lithium Niobate (LiNbO3) piezoelectric substrate. FDTD modeling is done considering the multyphisics nature of the problem, by combining the electromagnetic and the elastodynamics theory in order to obtain the piezoelectric governing equations. Simulation results allow determining the time-position and insertion loss of SAW echoes, which enables the determination of the ID code stored in the tag.