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Optical quantum bit string comparator
摘要： Quantum computation has attracted much attention and several quantum algorithms have been proposed in the literature. However, the hardware able to implement such algorithms is still a challenge. In this work, we provide an optical setup for implementation of a quantum bit string comparator, QBSC, for polarization-based qubit, using the non-linear Kerr effect. The QBSC is an important structure for implementation of conditional statements in quantum algorithms.
关键词： Non-linear Kerr effect,Quantum bit string comparator,Quantum computation
更新于2025-09-23 15:22:29
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Global MPPT of photovoltaic system based on scanning method under partial shading condition
摘要： The partial shading (PS) of the photovoltaic (PV) array is a major problem for the PV systems. Therefore, it is necessary to extract the global maximum power point (GMPP) under partial shading. In this paper, we propose a simple method to find the GMPP. This method scans the P–V curve and memorizes all the peaks in order to get the global peak. Next, we control a boost DC–DC converter to extract the GMPP from the PV system. In addition, this Method allows following the dynamic GP under variant SPs with less oscillations around the stable state compared to the existing works.
关键词： Scanning method,Photovoltaic system,Global maximum power point,PV string
更新于2025-09-23 15:21:01
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Heating up holography for single-trace JT?ˉ$$ J\overline{T} $$ deformations
摘要： We study thermodynamic aspects of a tractable toy model of holography for extremal Kerr black holes proposed in [1]. On the gravity side, the theory can be described by the worldsheet action of string theory on a warped AdS3 background supported by NS-NS flux. Once we turn on temperature, the deformed background is described by a black string solution of type IIB supergravity that features a locally warped AdS3 factor. The dual field theory is conjectured to be a single-trace version of a J T -deformed CFT at finite temperature. As evidence for the correspondence we show that the spectrum of strings winding on the deformed background agrees with the spectrum of J T -deformed CFTs. Furthermore, we show that the gravitational charges of the black string match the averaged charges of a thermal ensemble in the dual field theory. Finally, we reproduce the Bekenstein-Hawking entropy of the black string from the microscopic density of states of J T -deformed CFTs.
关键词： Conformal Field Models in String Theory,Integrable Field Theories,AdS-CFT Correspondence
更新于2025-09-23 15:19:57
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[IEEE 2018 IEEE Energy Conversion Congress and Exposition (ECCE) - Portland, OR, USA (2018.9.23-2018.9.27)] 2018 IEEE Energy Conversion Congress and Exposition (ECCE) - A Novel Differential Power Processing Architecture for a Partially Shaded PV String Using Distributed Control
摘要： This paper proposes a differential power processing (DPP) architecture applied to a series PV string which enables each PV element to operate at its local maximum power point (MPP) while processing only a small portion of its total generated power through the module integrated converters (MICs). The current processed through each converter is the difference between the local PV element MPP current and the local PV string current. This feature allows for a reduced current stress on the MIC components relative to the most common DPP topology. Thus, a higher system efficiency is realized at a reduced cost. A state space model of the proposed system is derived, and a comparison analysis is carried out with respect to the conventional DPP architectures. Additionally, a modular and compact design is proposed for a large number of PV panels in a series PV string. A hardware prototype is designed and built for 3 PV panels connected in series to validate the proposed architectures effectiveness and experimentally demonstrate its robustness. The modularity of the system is also tested to ensure low current and voltage stress on the MICs.
关键词： Distributed Control,maximum power point tracking (MPPT),Differential Power Processing,DC-DC Converters,Photovoltaic (PV) String,Partial Shading
更新于2025-09-23 15:19:57
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Discovery of conical intersection mediated photochemistry with growing string methods
摘要： Conical intersections (CIs) are important features of photochemistry that determine yields and selectivity. Traditional CI optimizers require significant human effort and chemical intuition, which typically restricts searching to only a small region of the CI space. Herein, a systematic approach utilizing the growing string method is introduced to locate multiple CIs. Unintuitive MECI are found using driving coordinates that can be generated using a combinatorial search, and subsequent optimization allows reaction pathways, transition states, products, and seam-space pathways to be located. These capabilities are demonstrated by application to two prototypical photoisomerization reactions and the dimerization of butadiene. In total, many reaction pathways were uncovered, including the elusive stilbene hula-twist mechanism, and a previously unidentified product in butadiene dimerization. Overall, these results suggest that growing string methods provide a predictive strategy for exploring photochemistry.
关键词： reaction pathways,growing string method,conical intersections,photochemistry,MECI
更新于2025-09-19 17:15:36
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Minimal Magnetic Dipole Moment for the Solar Cell Array Using GaInP/GaAs/Ge Cells
摘要： The only ambient power source in space is solar energy, which is harvested by photovoltaic conversion with solar cells. Since about 20 years ago, silicon solar cells have been used extensively as the primary power devices in space. However, in recent years, GaInP/GaAs/Ge solar cells with triple junction technology, have been widely used as power-generation devices for space applications. Not only do the GaInP/GaAs/Ge solar cells have better conversion efficiency compared to Si solar cells, but it is also possible to supply the required electric power using a smaller number of solar cells. While there are advantages when using the GaInP/GaAs/Ge solar cells, methods for design of systems of strings should be established for minimizing their magnetic dipole moment. This is because the voltage and current are three times greater than with Si solar cells, and this must be considered. By electromagnetic theory, loop current of a string consisting of cells in series occurs when flowing through it. That magnetic dipole moment can affect attitude control when using magnetic torque bars in orbit, and spacecraft systems require no more than 0.25 Am2 of magnetic dipole moment for optimal attitude control. Therefore, we designed a single string of GaInP/GaAs/Ge solar cells and tested its current capacity to see and minimize the magnetic dipole moment. Finally, we proposed an optimal string design methodology by a test coupon solar cell array using GaInP/GaAs/Ge solar cells by simulation and implemented it on a substrate of carbon fiber reinforced plastic material to see how well the prototype worked or did not work. In future, the string design methodology could be extended to a larger solar cell array by using this coupon design methodology to minimize the magnetic dipole moment.
关键词： Carbon fiber reinforced plastics,GaInP/GaAs/Ge,Solar cell,String,Magnetic dipole moment
更新于2025-09-19 17:13:59
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Analysis of Photovoltaic String Failure and Health Monitoring with Module Fault Identification
摘要： In this paper, photovoltaic (PV) string failure analysis and health monitoring of PV modules based on a low-cost self-powered wireless sensor network (WSN) are presented. Simple and effective fault detection and diagnosis method based on the real-time operating voltage of PV modules is proposed. The proposed method is verified using the developed health monitoring system which is installed in a grid-connected PV system. Each of the PV modules is monitored via WSN to detect any individual faulty module. The analysis of PV string failure includes several electrical fault scenarios and their impact on the PV string characteristics. The results show that a degraded or faulty module exhibits low operating voltage as compared to the normal module. The developed health monitoring system also includes a graphical user interface (GUI) program which graphically displays the real-time operating voltage of each module with colors and thus helping users to identify the faulty modules easily. The faulty modules identification approach is further validated using the PV module electroluminescence (EL) imaging system.
关键词： photovoltaic module fault detection,health monitoring,Internet of Things,photovoltaic string,graphical user interface,self-powered wireless sensor network
更新于2025-09-16 10:30:52
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Technical and Economic Optimal Solutions for Utility-Scale Solar Photovoltaic Parks
摘要： Solar energy has shown to be a successful renewable source, wherefore large investments are planned in the upcoming decades. This work aims at developing technical and economical solutions to optimize a utility‐scale grid connected solar photovoltaic park with an installed capacity of 24 MWp. Several successive simulations were automatically performed with the PVSyst software, so that each influencing parameter is individually analyzed. Moreover, a comprehensive study touching relevant aspects, such as central versus string inverters, landscape versus portrait dispositions, the optimal tilt angle (for fixed tilt systems), backtracking strategy (for single axis tracking systems), shading limit angle, and pitch is performed with the objective of finding the configuration leading to the higher grid injected energy output. The levelized cost of energy (LCOE) was obtained for 12 different cases in which, for both fixed tilt and single‐axis tracking (SAT), central and string inverters and portrait/landscape disposition were considered. The lowest LCOE achieved was 32.23 €/MWh, which is a clear indication of the competitiveness of the solar Photovoltaic (PV) technology. The most economic viable solution is characterized by the employment of an SAT system with the backtracking strategy, together with string inverters and module portrait disposition.
关键词： string inverters,levelized cost of energy (LCOE),optimization,design parameters,economic analysis,utility‐scale solar PV park
更新于2025-09-16 10:30:52
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[Institution of Engineering and Technology 5th IET International Conference on Clean Energy and Technology (CEAT2018) - Kuala Lumpur, Malaysia (5-6 Sept. 2018)] 5th IET International Conference on Clean Energy and Technology (CEAT2018) - The Impact of Energy Yield of a Photovoltaic System Under Partial Shading
摘要： Photovoltaic module is very susceptible to partial shading problem. In a photovoltaic power system, large number of photovoltaic modules are connected in series to provide required voltage and power. Due to large number of photovoltaic modules, the chances of every photovoltaic module to receive uniform solar irradiance become lower. Therefore, a photovoltaic system consists of large number of photovoltaic modules is even more susceptible to partial shading problem. This paper presents the investigation of the energy yield of a photovoltaic system under partial shading conditions. The investigation results shows that the energy yield of a photovoltaic system decreases as the shading heaviness increases. However, the effect is not constant. The effect is especially significant when the photovoltaic system is under lightly partial shaded conditions. In worst case, the energy yield of the photovoltaic system can drops up to 17.65 % as the shading heaviness increases by 20 %. Therefore, the partial shading need to be address in order to minimize the losses of the photovoltaic system under partial shading conditions.
关键词： Photovoltaic module,photovoltaic string,solar energy,partial shading
更新于2025-09-12 10:27:22
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Buck-Boost-Buck Type Single-Switch Multi-String Resonant LED Driver with High Power Factor and Passive Current Balancing
摘要： An integrated buck-boost-buck type single-switch multi-string resonant LED driver is proposed and analyzed. It combines buck-boost and buck converters to achieve passive current balancing and power factor correction (PFC). With this circuit configuration, the proposed LED driver employs only one low-side connection active switch, resulting in a very simple control requirement involving one closed-loop controller for regulating one output current. Other output currents can be balanced automatically by resonant capacitor and storage capacitors, making the control strategy economical. In addition, high efficiency is achieved due to single-stage power conversion. Taking three-string LED driver as an example, the proposed buck-boost-buck type single-switch LED driver is studied in terms of operating principle, current balancing principle, power factor (PF) analysis, voltage gain and key circuit parameter design. Finally, an 84W high PF three-string LED driver prototype with 94.3% peak efficiency is built to verify the analytical results.
关键词： passive current balancing,multi-string,single switch,power factor correction (PFC),Buck-boost-buck,LED driver
更新于2025-09-11 14:15:04