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Optimal cascaded predictive control for photovoltaic systems: application based on predictive emulator
摘要： The present study sheds new light on advanced control methods of photovoltaic (PV) emulators using finite set model predictive control (FS-MPC). In the first part of the study, a predictive PV emulator (P-PVE) based on a Buck converter is proposed and tested under hard climatic conditions and load variations. The high performance of the P-PVE in terms of dynamic response, reference tracking, accuracy, simplicity, and efficiency is confirmed experimentally when compared with those of the commonly used one based PI controller. The second part of the study proposes an efficient cascaded predictive control (CPC) method applied on two topologies of PV systems, namely the stand-alone system and the grid-connected system. In each topology, the P-PVE is cascaded to a maximum power point tracking Boost converter in order to track efficiently the maximum power point. In addition to the high performance offered by the FS-MPC, the proposed control strategy allows to control all cascaded converters at the same time in one stage instead of controlling them separately, thus providing more flexibility and simple controllability. Extensive experimental results are done confirming the correctness and the effectiveness of the proposed CPC under hard climatic conditions, even in the presence of distorted grid voltage.
关键词： finite set model predictive control,stand-alone system,cascaded predictive control,grid-connected system,photovoltaic emulator
更新于2025-09-16 10:30:52
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Reconstruction method for DECT with one half-scan plus a second limited-angle scan using prior knowledge of complementary support set (Pri-CSS)
摘要： Dual-energy computed tomography (DECT) has capability to improve material differentiation, but most scanning schemes require two sets of full-scan measurements at different x-ray spectra, limiting its application to imaging system with incomplete scan. In this study, using one half-scan and a second limited-angle scan, we propose a DECT reconstruction method by exploiting the consistent information of gradient images at high- and low-energy spectra, which relaxes the requirement of data acquisition of DECT. Based on the theory of sampling condition analysis, the complementary support set of gradient images plays an important role in image reconstruction because it constitutes the sufficient and necessary condition for accurate CT reconstruction. For DECT, the gradient images of high- and low-energy CT images ideally share the same complementary support set for the same object. Inspired by this idea, we extract the prior knowledge of complementary support set (Pri-CSS) from the gradient image of the first half-scan CT image to promote the second limited-angle CT reconstruction. Pri-CSS will be incorporated into total variation regularization model in the form of constrains. Alternative direction method is applied to iteratively solve the modified optimization model, thereby deriving the proposed algorithm to recover low-energy CT image from limited-angle measurements. The qualitative and quantitative experiments on digital and real data are performed to validate the proposed method. The results show that the proposed method outperforms its counterparts and achieve high reconstruction quality for the designed scanning configuration.
关键词： complementary support set,total variation,image-domain method,dual-energy CT
更新于2025-09-12 10:27:22
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New Approach for Pulsed-Laser Testing That Mimics Heavy-Ion Charge Deposition Profiles
摘要： A novel approach for two-photon absorption (TPA) pulsed-laser testing produces extended charge deposition profiles that are analogous to those produced by heavy ions. In this approach, which utilizes an axicon rather than a spherical lens, the conventional Gaussian beam is replaced by a quasi-Bessel beam. The key feature of a quasi-Bessel beam, relevant to pulsed-laser single-event effects (PL-SEE) studies, is that its radial size (~1 μm) remains constant over the axial length of the beam (several 100s of μm) resulting in a charge-deposition profile that more closely mimics that produced by a heavy ion. This elongated charge distribution directly lends itself to a simple and intuitive description in terms of linear-energy transfer, or LET, facilitating laser/ion correlation studies. Experimental results comparing a conventional TPA PL-SEE focusing geometry and the axicon focusing geometry are presented for three different test vehicles: a 45-nm SOI nFET, a bulk silicon photodiode, and an LM 124 operational amplifier. Using the axicon approach, strong laser/ion correlation is observed in the silicon photodiode for single-event transients (SET) across a wide range of LETs. The correlation is achieved by “tuning” the laser to the desired LET rather than relying on pre-existing heavy-ion data and therefore this approach holds promise as a predictive tool.
关键词： single-event effect (SEE),silicon,Correlation methods,single-event transient (SET),heavy-ion testing,pulsed-laser,two-photon absorption,linear energy transfer (LET)
更新于2025-09-12 10:27:22
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Analyzing the interrelationships among barriers to green procurement in photovoltaic industry: An integrated method
摘要： Although the environmental issues behind solar energy and green procurement (GP) have received increasing attention, industries still struggle to identify key barriers hindering GP and analyze the interrelationships among them. Most of the previous studies ignored the cognition uncertainty in assessing the barriers to GP, and failed to consider the impact of barrier strength on the interrelationships among barriers. This paper proposes a rough weighted method that integrates the advantages of DEMATEL (Decision-Making and Trial Evaluation Laboratory) and ISM (Interpretive Structural Modeling). Variable rough precision theory is introduced to control the cognition uncertainty and vagueness in assessing the barriers. This novel approach is then applied to analyze the interrelationships among barriers to GP in China’s photovoltaic (PV) industry. The analysis results show that internal obstacles (e.g. company’s unawareness) are more important than external obstacles (e.g. lack of legislation). However, external obstacles (especially weak incentive policies) should be solved first by policy-makers because internal obstacles are found to be caused by external obstacles. Finally, comparative studies are employed to prove the effectiveness of the proposed method. Further studies are expected to apply the proposed method to different industries and promote the development of GP.
关键词： variable precision rough set,barrier interrelationship,rough numbers,Green procurement,photovoltaic industry
更新于2025-09-12 10:27:22
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Influence of laser post-processing on pore evolution of Ti–6Al–4V alloy by laser powder bed fusion
摘要： In laser powder bed fusion (LPBF) processes, critical defect issues such as porosity limit the quality of the fabricated part. This work investigates the mechanism of pore evolution during the laser post-processing of an LPBF part. A laser beam was utilized to scan the top surface of a Ti–6Al–4V alloy part. The morphologies of the internal layers as well as the distribution of the porosity inside the Ti–6Al–4V sample were experimentally measured and compared using micro-computed tomography (micro-CT). It was found that the void fraction was significantly decreased, from 2.51% to 0.77%, by laser post-processing. A multi-physics coupled finite element model based on the Level-set method was built to analyze the evolution mechanism of the pore. This model simulated the effects of the energy density, Marangoni flow and mass transfer on the pore evolution. Typical processes were studied in detail, and a table summarizing the pore evolution under different post-processing parameters is given.
关键词： Ti–6Al–4V alloy,Laser powder bed fusion,Pore evolution,Additive manufacturing,Level-set method
更新于2025-09-12 10:27:22
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Robust Profit Maximization in Multiperiod Energy Markets with Interval Prediction of Photovoltaics
摘要： In this paper, we formulate an optimal bidding problem in a multiperiod electricity market with the consideration of the uncertain PV output. Based on the proposed strategy, the aggregator of interest operates his dispatchable assets to pursue the largest pro?t by submitting one optimal prosumption curve to the day-ahead market. To deal with a non-convexity issue stemming from the robust optimization problem, we reformulate the problem as its Lagrange dual counterpart. Then, we describe the uncertain range of the PV output by one polyhedral set, with which a new decision variable is introduced. We implement a constraints-generation method to solve the newly formulated problem by splitting it into another two subproblems. Based on one iterative scheme, the two subproblems are solved in sequence, and the solution of the robust optimization problem is obtained when the optimal results of the two subproblems are equal. In the numerical simulation, the pro?ts under di?erent PV lower bounds are presented.
关键词： Smart grid,robust optimization,polyhedral set,optimal bidding,Lagrange duality
更新于2025-09-12 10:27:22
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Influence of Quantum Dot Characteristics on the Performance of Hybrid SET-FET Circuits
摘要： Quantum dots (QDs) can be used as conductive islands to build-up single-electron transistors (SETs). The characteristics of the QDs define the functional performance of the SETs. In consequence, analyzing the influence of the variations of QD dimensions on the performance of hybrid SET-FET circuits is of high relevance. We employ a self-developed SET compact model which is calibrated to 3-D quantum-mechanics-based simulations in order to obtain realistic model parameters. A method to improve the circuit behavior, i.e., to increase the output current, is proposed. It is concluded that the variation of the QD size presents the largest influence on the overall circuit behavior.
关键词： variability,single-electron transistor (SET),quantum dot (QD),Nanowires
更新于2025-09-11 14:15:04
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A simple jig for the anti-parallel alignment of linacs’ lasers
摘要： Background: Despite crossing at the isocentre, misaligned laser beams may cause significant positioning problems. Purpose: The jig proposed here is to be used in addition to the quality assurance procedures employed with linacs and deals with possible misalignments of transverse lasers. Materials and methods: It is an inverted T construction with a two-sided rectangular, slightly transparent mirror set vertical on a piece of glass serving as its base. The device is carried by a horizontally set spirit-level surface and placed on the couch-top so that the sagittal laser passes through the vertical mirror’s plane. Then the therapy couch is translated along the Y direction until a laser beam shines on the corresponding side of the semi-transparent mirror. This spot is marked and is normally the linac’s isocentre set through an independent procedure employing a rotating plate. If the laser had been set properly, then its beam should be reflecting back on its source. If not, the alignment can be corrected by rotating and/or translating the laser holder until it does that. At the same time, it should be ensured that the beam does not wander away from the isocentre spot on the mirror. When both are achieved, the beam ends up perpendicular to the linac’s axis of rotation, while passing through the isocentre. The procedure can be repeated for the opposite laser. Conclusion: The jig was simple to construct and has been found quite useful in practice. The accuracy of patient positioning will be restricted only by the size of the laser beam’s cross-section.
关键词： laser alignment,patient positioning,radiotherapy,laser beam set up
更新于2025-09-11 14:15:04
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[IEEE 2018 Tenth International Conference on Quality of Multimedia Experience (QoMEX) - Cagliari (2018.5.29-2018.6.1)] 2018 Tenth International Conference on Quality of Multimedia Experience (QoMEX) - A High-angular-resolution Turntable Data-set for Experiments on Light Field Visualization Quality
摘要： In this paper, we present a high-angular-resolution data-set created using a turntable arrangement. Seven distinct objects, positioned on an automated turntable, were captured from three camera positions for every half degree of rotation, generating 720 images for each camera position. For each object, the camera positions were registered to the coordinate system of the middle camera. Intrinsic parameters of the camera were also estimated. A data-set of this kind is instrumental for research in a variety of areas, such as light field visualization, manifold learning, visual quality assessment, evaluation of preferred object orientation etc. Due to the availability of three-view stereo, this data-set could be useful for studying view interpolation techniques.
关键词： quality assessment,turntable data-set,Light field,angular resolution
更新于2025-09-11 14:15:04
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Visible light photoredox catalysed amidation of carboxylic acids with amines
摘要： A visible-light promoted photoredox catalysed, green one-pot approach for the amidation of carboxylic acids with amines has been developed for the synthesis of diverse aliphatic and aromatic amides. The proposed strategy is extendable also to biologically active amides and could represent a low-cost alternative to the common synthetic pathways. The developed strategy may hold great potential for a comprehensive display of biologically interesting peptide synthesis and amino acid modification.
关键词： Visible light,Amidation,Eosin Y,SET,Photoredox
更新于2025-09-11 14:15:04