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An Improved Proposed Single Phase Transformerless Inverter with Leakage Current Elimination and Reactive Power Capability for PV Systems Application
摘要： Single-phase transformerless inverters are broadly studied in literature for residential-scale PV applications due to their great advantages in reducing system weight, cost and elevating system efficiency. The design of transformerless inverters is based on the galvanic isolation method to eliminate the generation of leakage current. Unfortunately, the use of the galvanic isolation method alone cannot achieve constant common mode voltage (CMV). Therefore, a complete elimination of leakage current cannot be achieved. In addition, modulation techniques of single-phase transformerless inverters are designed for the application of the unity power factor. Indeed, next-generation PV systems are required to support reactive power to enable connectivity to the utility grid. In this paper, a proposed single-phase transformerless inverter is modified with the clamping method to achieve constant CMV during all inverter operating modes. Furthermore, the modulation technique is modified by creating a new current path in the negative power region. As a result, a bidirectional current path is created in the negative power region to achieve reactive power generation. The simulation results show that the CMV is completely clamped at half the DC link voltage and the leakage current is almost completely eliminated. Furthermore, a reactive power generation is achieved with the modified modulation techniques. Additionally, the total harmonic distortion (THD) of the grid current with the conventional and a modified modulation technique is analyzed. The efficiency of the system is enhanced by using wide-bandgap (WBG) switching devices such as SiC MOSFET. It is observed that the efficiency of the system decreased with reactive power generation due to the bidirectional current path, which leads to increasing conduction losses.
关键词： leakage current,transformerless inverter,reactive power,wide-bandgap (WBG),silicon carbide (SiC),photovoltaic (PV) power system
更新于2025-09-23 15:23:52
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PEGylated doxorubicin cloaked nano-graphene oxide for dual-responsive photochemical therapy
摘要： Graphene oxide (GO) own huge surface area and high drug loading capacity for aromatic molecules, such as doxorubicin (DOX). However, its biocompatibility is poor and it might agglomerate in physiological condition. Chemical modification of GO with hydrophilic polymer, especially PEGylation, was a common method to improve its biocompatibility. But the chemical modification of GO was complicated, and its drug loading capacity might be reduced because of the occupation of its functional groups. In this study, DOX-PEG polymers with different PEG molecular weight were synthesized to modify nano graphene oxide (NGO) to simultaneously realize the solubilization of NGO and the high loading capacity of DOX. The result showed that the drug release of NGO@DOX-PEG was pH sensitive. NIR irradiation could augment the drug release, cellular uptake, cytotoxicity and nuclear translocation of nanodrugs. Among the three kinds of nanodrugs, NGO@DOX-PEG5K was superior to others. It suggested that after conjugating with PEG, the bond between DOX-PEG and NGO was weakened, which resulted in a better drug release and treatment effect. In summary, the NIR and pH dual-responsive NGO@DOX-PEG nanodrugs were developed by noncovalent modification, and it demonstrated excellent biocompatibility and photochemical therapeutic effect, presenting a promising candidate for antitumor therapy, especially NGO@DOX-PEG5K.
关键词： Nano-drug Delivery System,pH sensitive,Nano-Graphene Oxide,photochemical therapy,Doxorubicin
更新于2025-09-23 15:23:52
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Design and characterization of the non-uniform solar flux distribution measurement system
摘要： It is important to accurately measure the solar flux distribution on the heated surface for the utilization of solar energy. To this end, in this paper a new measurement system was proposed to measure the solar flux distribution of the absorber tube surface by taking advantage of the end loss effect. The new measurement system does not disturb the collected lights path and influence the operation of the solar collector. The solar flux distribution at different angles can be measured with a few number of heat flux gage by rotating the proposed solar flux measurement system. Compared with existing measurement techniques, the proposed solar flux measurement system has distinct advantages such as simple structure, flexible and reliable operation and easy application. An experimental platform was designed and constructed, and the solar flux distributions on the outer surface of the absorber under different conditions are measured. The feasibility and effectiveness of the proposed measurement method are validated by comparing the experiment results and the numerical simulation results.
关键词： solar flux distribution,solar flux measurement system,parabolic trough solar collector,experimental investigation
更新于2025-09-23 15:23:52
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A new solar hybrid clean fuel-fired distributed energy system with solar thermochemical conversion
摘要： This paper proposes a new solar hybrid clean fuel-fired distributed energy system to increase the system thermodynamic efficiency and save fossil fuel, in which solar energy is upgraded into high-level chemical energy of syngas (H2 and CO) by integrating the solar-driven methanol decomposition based thermochemical conversion. Solar energy, in the form of chemical energy of the generated syngas, is steadily stored and utilized to drive the distributed energy system to generate power, heat and cooling. The double-axis tracking parabolic trough solar collector is deployed to the proposed system to reduce the cosine loss of solar energy. The incorporation of the solar thermochemistry and double-axis solar concentrator technologies leads to a significant improvement in the solar energy utilization efficiency and the off-design performances under varying solar irradiations. With the integration of solar energy utilization and tri-generation, the proposed system achieves a high net solar-to-electric efficiency, 24.66%, and results in high primary energy ratio, 83.86%, exergy efficiency, 38.81%, and carbon emission saving rate, 51.43%. The proposed system is deployed to an office building to study the operation strategies and annual thermo-economy performances, and competitive off-design performances and economy performances are achieved. The research findings open up a new avenue towards the efficient utilization modes of clean fuel and solar energy.
关键词： Distributed energy system,Solar fuel,Solar thermochemistry,Methanol decomposition,Tracking strategy
更新于2025-09-23 15:23:52
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Phage-based assay for rapid detection of bacterial pathogens in blood by Raman spectroscopy
摘要： Sepsis is a systemic inflammatory response ensuing from presence and persistence of microorganisms in the bloodstream. The possibility to identify them at low concentrations may improve the problem of human health and therapeutic outcomes. So, sensitive and rapid diagnostic systems are essential to evaluate bacterial infections during the time, also reducing the cost. In this study, from random M13 phage display libraries, we selected phage clones that specifically bind surface of Staphyloccocus aureus, Pseudomonas aeruginosa and Escherichia coli. Then, commercial magnetic beads were functionalized with phage clones through covalent bond and used as capture and concentrating of pathogens from blood. We found that phage-magnetic beads complex represents a network which enables a cheap, high sensitive and specific detection of the bacteria involved in sepsis by micro-Raman spectroscopy. The enter process required 6 h and has the limit of detection of 10 Colony Forming Units on 7 ml of blood (CFU/7 ml).
关键词： Phage-capture system,Raman spectroscopy,M13 filamentous phage,Sepsis,Phage display
更新于2025-09-23 15:23:52
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A simple, low cost ink system for Drop-On-Demand printing high performance metal oxide dielectric film at low temperature
摘要： We have successfully developed an ink system containing cheap raw materials through a simple process and have printed ZrOx dielectric film at a relatively low annealing temperature of 250 °C. The ZrOx dielectric film afforded a leakage current density of 5.4×10-6 A/cm2 at 1 MV/cm and a dielectric constant of 10, which shows promising future for flexible electronics. The ink system shows a temperature-induced gelation behavior and gel network is formed when temperature rises. A high concentration of oxide precursors is obtained near the network area through the absorption function of polymer groups, and thus oxide structure can be formed at a relatively low temperature due to the shorter diffusion path of precursor polymerization. The microstructure of printed ZrOx film was investigated by High Resolution Transmission Electron Microscope (HRTEM), Fourier-transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS), and the effect of annealing temperature on film structure was studied.
关键词： dielectric film,low temperature,Low cost,ink system,Drop-On-Demand printing
更新于2025-09-23 15:23:52
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The first deaf-blind patient in Russia with Argus II retinal prosthesis system. What he sees and why
摘要： A 59-year-old man with retinitis pigmentosa and hearing loss (clinical Usher syndrome) underwent surgery to implant the Argus II retinal prosthesis system in the right eye. This is the first case of retinal implant surgery in the Russian Federation. In this study we propose a new method for evaluating the functional results after implantation of the Argus II, the statistical analysis was performed to find correlations between the sizes of phosphenes that the patient drew and then were digitalized, and the height of the subimplant interface, retinal thickness, impedance, and perceptual threshold, which showed interesting mixed results. Correlation analysis showed the weak dependency between the size of a phosphene and the perceptual threshold and we did not find significant correlations between a phosphene and the height of the interface, impedance and retinal thickness.
关键词： Argus II,Usher syndrome,retinitis pigmentosa,deaf-blind,blind,artificial vision,retinal prosthesis system,retinal implant,deafblind
更新于2025-09-23 15:23:52
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[IEEE 2018 19th International Conference of Young Specialists on Micro/Nanotechnologies and Electron Devices (EDM) - Erlagol (Altai Republic), Russia (2018.6.29-2018.7.3)] 2018 19th International Conference of Young Specialists on Micro/Nanotechnologies and Electron Devices (EDM) - The System of Frequency Matching of the Ultrasonic Generators with the Radiators in “Bulava” Apparatuses
摘要： The article is devoted to the problem concerned with the determination of resonance frequency of the ultrasonic vibrating systems (the radiators) intended for the operation as a part of the ultrasonic technological apparatuses of “Bulava” type.
关键词： frequency control system,generator,resonance matching,Ultrasound
更新于2025-09-23 15:23:52
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[IEEE 2018 7th International Conference on Renewable Energy Research and Applications (ICRERA) - Paris, France (2018.10.14-2018.10.17)] 2018 7th International Conference on Renewable Energy Research and Applications (ICRERA) - Biomass Free Piston Stirling Engine Generator with PV
摘要： Proposed hybrid electric power generation system is constituted from Free Piston Stirling engine generator and solar photovoltaic system. Free Piston Stirling engine electric generator uses biomass, such as wood pellets as the heat source. This system produces maximum output of 1.6kW and 45°C 200L hot water with linear generator. This paper studied the control of output voltage of Free Piston Stirling Engine. ILQ (Inverse Linear Quadratic) control theory is used to keep output active power between 400W and 500W. In long range time constant of burning system and in short range time constant of electrical circuit, experiment yields temperature of FPSEG head between upper limit and lower limit.
关键词： hybrid system,Free Piston Stirling Engine,biomass,solar power,ILQ control
更新于2025-09-23 15:23:52
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Battery lifetime enhancement via smart hybrid energy storage plug-in module in standalone photovoltaic power system
摘要： Standalone photovoltaic power system is one of the feasible solutions in rural electri?cation. However, due to the intermittent nature of solar energy and signi?cant demand variations due to small load size, energy storage devices are needed to ensure power quality and reliability. Lead-acid battery bank has been widely used in such systems to act as the intermediate bu?er to compensate the power mismatch between generation and demand, despite the poor lifetime characteristics and relatively short service life compared to other energy storage devices. Most charge controllers only provide basic battery charging functionality and prevent the battery bank from overcharging and deep-discharging. While other notable aging factors such as frequent charge-discharge transition, high C-rate and surge power are often neglected. This paper presents a smart hybrid energy storage plug-in module that aims to enhance the service life of Lead-acid battery in standalone photovoltaic-battery power systems by mitigating life-limiting factors such as current ?uctuations and surge current. This module is designed as a plug-in module that can be adopted directly in existing infrastructure in installed standalone PV-battery power system. The e?ectiveness of the proposed plug-in module in mitigating battery stresses is simulated in Matlab Simulink with actual solar irradiance data and estimated load pro?le for a rural community in Sarawak Malaysia. The simulation results are validated experimentally with the scaled-down photovoltaic-battery power system. The e?ectiveness in mitigating battery stress is quantitatively evaluated with battery health cost function, while the reduction in overall battery cost is analyzed and discussed.
关键词： Renewable energy,Hybrid energy storage system,Photovoltaic,Supercapacitor,Lead-acid battery,Li-ion battery
更新于2025-09-23 15:23:52