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Development of current imbalance measurement technique among ships in IGBT module
Get PDF電子デバイス/半導体電力変換合同研究会, 10月30日-31日, 2014年, 産業技術総合研究所 TIAナノ連携棟, 茨城県IGBT modules need to have higher reliability since their demand is expanding. To realize highly reliable modules, an ultra-small PCB current probe was developed, which enables to measure current imbalance among chips without changing inside structure of the module. This technique can be applied to wiring design and built-in current sensing for highly reliable module
Interaction between compressible fluid and sound in a flue instrument
Get PDFIn order to study the generation of (aerodynamic) sound in flue instruments, we numerically apply Howe’s energy corollary for a 2D model of flue instrument. Howe’s energy corollary enables us to estimate the energy transfer between fluid flow and acoustic field. To implement it, separating the acoustic field from the fluid flow is needed. However the complete method to numerically achieve it has not been established yet. In this work, we develop an approximate method, which has been recently proposed in their experimental studies by Yoshikawa et al (2012 J. Sound Vib. 331 2558-2577) and others, and we apply it to the simulation of the model instrument. We first calculate fluid flow and acoustic oscillation simultaneously by a compressible fluid solver. Next referring to the information on the acoustic oscillation obtained we set up a pressure source on an acoustic solver and reproduce almost the same acoustic oscillation with it. Combining those results, we are able to calculate Howe’s energy corollary. The numerical result shows that the aerodynamic sound is generated from the oscillating jet rather than the vortices shed by the collision of it with the edge of the mouth opening, namely vortex shedding
A comparative study of spin coated and floating film transfer method coated poly (3-hexylthiophene)/poly (3-hexylthiophene)-nanofibers based field effect transistors
Get PDFA comparative study on electrical performance, optical properties, and surface morphology of poly(3-hexylthiophene) (P3HT) and P3HT-nanofibers based “normally on” type p-channel field effect transistors (FETs), fabricated by two different coating techniques has been reported here. Nanofibers are prepared in the laboratory with the approach of self-assembly of P3HT molecules into nanofibers in an appropriate solvent. P3HT (0.3 wt. %) and P3HT-nanofibers (∼0.25 wt. %) are used as semiconductor transport materials for deposition over FETs channel through spin coating as well as through our recently developed floating film transfer method (FTM). FETs fabricated using FTM show superior performance compared to spin coated devices; however, the mobility of FTM films based FETs is comparable to the mobility of spin coated one. The devices based on P3HT-nanofibers (using both the techniques) show much better performance in comparison to P3HT FETs. The best performance among all the fabricated organic field effect transistors are observed for FTM coated P3HT-nanofibers FETs. This improved performance of nanofiber-FETs is due to ordering of fibers and also due to the fact that fibers offer excellent charge transport facility because of point to point transmission. The optical properties and structural morphologies (P3HT and P3HT-nanofibers) are studied using UV-visible absorption spectrophotometer and atomic force microscopy , respectively. Coating techniques and effect of fiber formation for organic conductors give information for fabrication of organic devices with improved performance
P3HT-fiber-based field-effect transistor: Effects of nanostructure and annealing temperature
Get PDFPoly(3-hexylthiophene) nanofibers were prepared under ambient conditions and applied in organic field-effect transistors (FETs). Top-contact FETs with spin-coated and nanofiber-based layers were fabricated to compare their transport performance. It was found that the nanofiber FET shows a higher performance than the spin-coated one. The effects of annealing on the device performance of the nanofiber FET were also investigated from room temperature to 120 °C. The key performance characteristics of the nanofiber FET, such as carrier mobility and ON/OFF ratio, were improved by low-temperature annealing up to 80 °C. However, they were degraded by high-temperature annealing at 120 °C. The modulation of the surface morphology observed by atomic force microscopy is consistent with the change in device performance. The results of the correlation analysis of the mobility, hysteresis, and OFF current indicate that the change in FET performance is due to the disappearance of nanofiber interspaces and the removal of adsorbed molecules by temperature-controlled annealing
Detection of Underwater Objects Based on Machine Learning
No full textSide-scan and forward looking sonars are some of the most widely used imaging systems for obtaining large scale images of a seafloor, and their use continues to expand rapidly with their increasing deployment on Autonomous Underwater Vehicles. However,it is difficult to extract quantitative information from the images generated from these processes, in particular, for the detection and extraction of information on the objects within these images. We propose in this paper an algorithm for automatic detection of underwater objects in side-scan images based on machine learning employing adaptive boosting. Experimental results show that the method produces consistent maps of a seafloor
Molecular Structure and Crystal Packing of n-Type Semiconducting Material 3',3'-(1,4-Phenylene) bis {2'-(4"-trifluoromethyl) phenyl} acrylonitrile
Get PDFThe exact molecular structure and the crystal packing of the n-type semiconducting material 3′,3′-(1,4-phenylene)bis{2′-(4"-trifluoromethyl)phenyl}acrylonitrile was determined by a single crystal X-ray diffraction with twin treatment technique. The air-stable product was crystallized from dichloromethane-hexane mixed solution. The solid-state structure is the example of a typical π-π stacking with side intermolecular CN–H short contact networks
デジタル補正を用いたアナログ回路特性向上に関する研究
Get PDF九州工業大学博士学位論文 学位記番号:情工博甲第292号 学位授与年月日:平成26年3月25日第1章 序論||第2章 製造後に出力電圧を調整可能な3端子レギュレータ||第3章 クローズド・ループ・オフセット増幅器と析り返し-交互スイッチングDACを用いたオペアンプのオフセット校正||第4章 結
Score Allotment Optimization Method with Application to Comparison of Ability Evaluation in Testing between Classical Test Theory and Item Response Theory
Get PDFMany researchers know the superiority of the item response theory (IRT) over the classical test theory (CTT) from a detailed test-evaluation viewpoint. However, teachers are still reluctant to use the IRT as a daily testing tool. The primary objective of this paper is to nd the difference between the CTT and the IRT.
In particular, we focus on the difference in ability evaluation. We compared the CTT and IRT evaluated abilities by using the hypothetically assumed abilities that are mimicked to a real case. By using a simulation study, we found that the IRT is superior to the CTT to some extent. The CTT uses pre-assigned allotments contrary to the IRT which has no allotment concept. However, if we regard the ability evaluation by the IRT as the standard, we can nd the most appropriate allotments in the CTT so that the total scores of the CTT are adjusted as close as possible to the abilities obtained by the IRT. This is a kind of allotment optimization problem. We show the methodology in this paper. By applying our methodology to some simulation cases that mimic the real data case, we found an intriguing feature with respect to the pre-assigned allotments. If teachers want to raise the examination pass rate, we guess that they give higher scores than the actual scores achieved by students; we call this jacking-up. Using the allotment optimization, we have found that jacking-up causes higher allotments to easier problems in the CTT