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[IEEE 2018 International Conference on Smart Electric Drives and Power System (ICSEDPS) - Maharashtra State, India (2018.6.12-2018.6.13)] 2018 International Conference on Smart Electric Drives and Power System (ICSEDPS) - Cascaded H-Bridge Inverter based PV-STATCOM
摘要： The environmental effect and need of energy have been increasing rapidly, due to this demand for renewable resources increased. One of the renewable resources Solar Photovoltaic (PV) energy is presently most popular in the environment. An inverter is a necessary part of grid-connected PV systems. This paper presents a new approach of large-scale photovoltaic solar farm inverter as STATCOM, known as PV-STATCOM, for regulation of voltage at the point of common coupling which recovers the voltage stability of the transmission line. Over daytime, the solar PV farm generates active power, but stay in idleness at the night-time. In this paper, PV-STATCOM incorporating multilevel inverter is presented. The voltage at the PCC is regulated at different loading conditions using PV-STATCOM. The entire system modeling and study are performed using MATLAB/SIMULINK.
关键词： STATCOM,photovoltaic(PV),cascaded H-Bridge (CHB),flexible AC transmission system (FACTS),Pulse width modulation (PWM),neutral point clamped (NPC)
更新于2025-09-10 09:29:36
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Detection of Delaminations in Sunlight-Unexposed Concrete Elements of Bridges Using Infrared Thermography
摘要： Infrared thermography is a non-destructive test used in the inspection of structures. However, its use for bridge inspection is still under development and in many cases its application may be limited to bridge sections exposed to direct sunlight. This study aims to evaluate infrared thermography test for the detection of delaminations in different types of concrete not exposed directly to sunlight. The experimental methodology uses two concrete specimens with water/cement ratios (w/c) equal to 0.5 and 0.6, through the insertion of polystyrene plates of different thicknesses (3, 6 and 12 mm) and depths (25, 50 and 75 mm), in order to simulate defects within the concrete and evaluate the capacity of infrared thermography to detect them. The results show that detection is possible, but limited to short periods of time. In relation to the concrete quality, defects were more easily detected in the test specimen with lower w/c ratio. It can be said that the nearer to the surface and larger the delamination, the easier it is to detect. Also, the better the quality of the concrete, the more effective the technique becomes.
关键词： Concrete,Passive thermal imaging,Infrared thermography,Bridge inspection
更新于2025-09-10 09:29:36
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Decoupling the contributions to the enhancement of electrical conductivity in transparent silver nanowire/zinc oxide composite electrodes
摘要： Electrical properties of silver nanowire (AgNW)-based transparent electrodes have been improved without transmittance loss by forming a composite with zinc oxide (ZnO). Here, we identified the dominant effect responsible for the improvement of electrical conductivity of the transparent AgNW:ZnO composite electrodes by fabricating the AgNW:ZnO composite electrodes with different architectures and theoretically calculating the overall resistance of their equivalent circuits. Specifically, when we compared the overall resistances of the AgNW:ZnO electrodes with various architectures by experiment, the electrode with only the electrical bridge effect showed the lowest electrical resistance. In addition, while the theoretical overall resistances were comparable on changing the interconnect resistances between the silver nanowires in the equivalent circuits of all architectures, they decreased dramatically with the decreasing ZnO bridging resistance. Thus, it was concluded that the electrical bridge effect is more important than the capillary force effect which decreases the interconnect resistance between the silver nanowires for the enhancement of the electrical properties of AgNW:ZnO composite electrodes. It was also found that the AgNW:ZnO electrodes with only the electrical bridge effect showed better device performances when applied to optoelectronic devices such as organic photovoltaics.
关键词： electrical conductivity,silver nanowire,electrical bridge effect,zinc oxide,capillary force effect
更新于2025-09-09 09:28:46
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Modelling and Analysis of Characteristics of a Piezoelectric-Actuated Micro-/Nano Compliant Platform Using Bond Graph Approach
摘要： The piezoelectric-actuated ?exure-based compliant platform is commonly adopted in many ?elds of micro and nanotechnology. In this paper, bond graph modeling, and kinematic and dynamic characteristics of a piezoelectric-actuated micro-/nano compliant platform system are investigated. During modeling, the bond graph model of the piezoelectric actuator (PZT) is derived by considering both the electrical domain and the mechanical domain. Considering the compliances of ?exure hinges and elastic linkages, as well as the input ends, the bond graph model for the bridge-type displacement ampli?cation mechanism in the compliant platform is established by combining pseudo-rigid-body (PRB) model theory and elastic beam theory. Based on the interactions between the PZT subsystem and compliant platform subsystem, the kinematic performance of the proposed compliant platform system is evaluated through both computer simulations and experimental tests. Furthermore, the frequency responses, dynamic responses and load capacity of the compliant platform system are studied. This paper explores a new modeling method for a piezoelectric-actuated compliant platform system, which can provide an effective solution when analyzing the micro-/nano system.
关键词： piezoelectric actuator,micro-/nano compliant platform,bridge-type displacement ampli?cation mechanism,bond graph
更新于2025-09-09 09:28:46
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[IEEE 2018 International Power Electronics Conference (IPEC-Niigata 2018 –ECCE Asia) - Niigata, Japan (2018.5.20-2018.5.24)] 2018 International Power Electronics Conference (IPEC-Niigata 2018 -ECCE Asia) - Design of a High-Frequency Dual-Active Bridge Converter with GaN Devices for an Output Power of 3.7 kW
摘要： In the automotive industry weight and volume are important issues to design power electronics besides costs. With the upcoming of wide band-gap devices like Gallium Nitride (GaN) devices high switching frequencies become a potential for converters. Operating at high switching frequencies reduces the volume of passive components e.g., transformer significantly. Auxiliary supplies or on-board charging systems for electric vehicles are typical areas of application for a reduction of volume and weight. For this kind of application dc-dc converters like a Dual Active Bridge converter can be used. This paper describes a detailed electrical analysis of a compact single phase Dual Active Bridge converter operated at a high switching frequency of 500 kHz at a dc voltage of 400 V on both full bridges to achieve a power transfer of 3.7 kW. In this paper it is shown how a fast switching and compact dual active bridge converter is designed that operates with a high efficiency of about 96% at nominal power.
关键词： Gallium Nitride (GaN) devices,Dual Active Bridge converter,electric vehicles,power electronics,high switching frequencies
更新于2025-09-09 09:28:46
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Unraveling the Role of Π - Conjugation in Thiophene Oligomers for Optoelectronic Properties by DFT/TDDFT Approach
摘要： Thiophene oligomer has been investigated using DFT/TDDFT calculations with an aim to check its suitability for opto electronic applications and also to analyse the influence of π-bridge. Our results revealed that thiophene oligomers have excellent π-conjugation throughout. FMO analysis give an estimate of band gap of thiophene oligomer and further revealed HOMO are localized on π – bridge, donor group and LUMO are localized on π – bridge and acceptor group. A TDDFT calculation has been performed to understand the absorption properties of them in gas phase and solvent phase. PCM calculations convey that absorption maxima show positive solvatochromism. Among the designed candidates, the one with more π – bridge show higher wavelength of absorption maxima and would be a choice for better optoelectronic materials. NBO analysis provides support for complete delocalization in these systems. It is interesting to note that oligomer with more π–bridge display an enhanced optoelectronic properties than with less π – bridge.
关键词： Thiophene oligomer,TDDFT,π – bridge,PCM,NBO
更新于2025-09-09 09:28:46
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A Research on the Automatic Gain Control via the Relative Gain
摘要： The paper presents an auto gain control (AGC) method and/or technology developed by its author based on the Variable Electricity Bridge (VEB) principle. This new close-loop AGC method aims to control the change of the decibel value of the relative gain. Specifically, the proposed method does not control the changes of the gain by way of the reverse feedback, but it controls the regulated results of the decibel attenuation in a linear way by using the changes of the decibel values of the relative gain. The contributions of this paper include the founding and development of the VEB AGC theory and the related technology. We demonstrates the results via the radio frequency channels of the VEB AGC technology, in which changes in decibel value of the output power are equal to that of the input, and irrelevant to the perturbation of the total gain.
关键词： VEB AGC Transfer Function,VEB Gain-and-Error Bridge,AGC Transfer Voltage,VEB AGC Principle,Relative Gain,Limited Gain Precision
更新于2025-09-09 09:28:46
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Active Guarded Wheatstone Bridge for High Resistance Measurements Up to 100 TΩ at TüB?TAK UME
摘要： We present an active guarded Wheatstone bridge, developed at TüB?TAK UME, for high resistance measurements between 100 MΩ to 100 TΩ up to 1000 V. The guarded box connections and special low noise cables were used to reduce noise and leakage currents causing measurement errors. This has enabled us to perform stable measurements at higher resistor values.
关键词： guard resistor,measurement uncertainty,Wheatstone bridge,high value resistance,low current
更新于2025-09-09 09:28:46
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A study on the UAV image-based efficiency improvement of bridge maintenance and inspection
摘要： This study reviewed ef?cient bridge management using UAVs (Unmanned Arial Vehicles) that have much potential for facility maintenance such as the possibility of regular inspection on inaccessible parts of bridges, easy operation regardless of the operators’ specialty, and economic maintenance. For this study, images were obtained from a UAV and a 3D viewer was created with them for the work ef?ciency of bridge inspectors, so that the inspectors can see and check inaccessible areas regardless of inspector’s location. It compared various existing inspection methods for problems such as cracks, ef?orescence and leakage with the UAV inspection method to analyze the work ef?ciency as well as sustainable economic bene?t. The main purpose of this study was to ?gure out whether the proposed inspection using the images from the UAV and 3D viewer can replace the existing inspection methods that cannot be performed easily and analyze the economic bene?t of the new method. The study result showed that the UAV image-based bridge maintenance and inspection is possible even though it was found inef?cient when images of uneven quality were provided depending on operation of the UAV. Therefore, a UAV operation manual that can help generate images of even quality must be produced.
关键词： UAV photogrammetry,bridge maintenance and inspection,3D viewer,inspection ef?ciency
更新于2025-09-04 15:30:14
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Improving the rectifying performance of the pyrene-benzene system by optimizing its hydrocarbon bridge: A first-principles investigation
摘要： We report a computational study on enhancing the rectification ratio (RR) of the pyrene-benzene junction by modifying the structure of its acyclic aliphatic hydrocarbon bridge. The RR values for a series of pyrene-benzene systems with different types of bridges are determined. Notably, the maximum RR of the pyrene-(CH)3-(CH2)3-(CH)3-benzene system is 93.8, and the same hydrocarbon bridge increases the RR of the organic photovoltaic materials pyrene-DMA (N,N-dimethylaniline) and pyrene-DCNB (p-dicyanobenzene) by 10 times and limits reverse current during photo-induced electron transfer. These findings are particularly important for the design of molecular devices where both a high RR and conductivity are desirable. Moreover, they provide new insight into phenomena that indirectly affects the photo-electric conversion efficiency viz. enhancing the RR of the materials.
关键词： molecular electronics,hydrocarbon bridge,photovoltaic materials,pyrene-benzene system,rectification ratio
更新于2025-09-04 15:30:14