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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) - Comparative Study between CSP and CPV as Two Energy Systems
摘要： The need to cancel the total dependence of fossil fuels, several researches are established in order to meet this goal, mostly on solar systems. Today, global warming and green energy are important topics of discussion for every intellectual gathering all over the world. The only sustainable solution to these problems is the use of solar energy. The aim of this paper is the dynamic study of a PV system under the solar concentration based on lens multi-junction semiconductor materials and Fresnel associated with a passive heat recovery system, and a CSP technology based on Linear Fresnel Reflectors (LFR) with direct steam generation (DSG) in order to apply them in the region of Adrar where DNI is very important; the system LFR with DSG is dedicated to perform with high temperatures which is produce more power, but high temperatures causes a decrease in CPV system performance; the thermo – electric models and SAM software are used in order to describe and predict their behavior and compare their costs of construction.
关键词： Solar,CSP,PV,renewable energy
更新于2025-09-04 15:30:14
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Revealing molecular-level surface redox sites of controllably oxidized black phosphorus nanosheets
摘要： Bulk and two-dimensional black phosphorus are considered to be promising battery materials due to their high theoretical capacities of 2,600 mAh g?1. However, their rate and cycling capabilities are limited by the intrinsic (de-)alloying mechanism. Here, we demonstrate a unique surface redox molecular-level mechanism of P sites on oxidized black phosphorus nanosheets that are strongly coupled with graphene via strong interlayer bonding. These redox-active sites of the oxidized black phosphorus are confined at the amorphorized heterointerface, revealing truly reversible pseudocapacitance (99% of total stored charge at 2,000 mV s?1). Moreover, oxidized black-phosphorus-based electrodes exhibit a capacitance of 478 F g–1 (four times greater than black phosphorus) with a rate capability of ~72% (compared to 21.2% for black phosphorus) and retention of ~91% over 50,000 cycles. In situ spectroelectrochemical and theoretical analyses reveal a reversible change in the surface electronic structure and chemical environment of the surface-exposed P redox sites.
关键词： energy storage,pseudocapacitance,graphene,black phosphorus,redox-active sites
更新于2025-09-04 15:30:14
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Energy Level Engineering in Transition-Metal Doped Spinel-Structured Nanosheets for Efficient Overall Water Splitting
摘要： Unraveling the role of transition-metal doping on affecting the native spinel-structured nanosheets’ water splitting remains a grand challenge. In this work, a series of spinel-structured nanosheets wrapped hollow nitrogen-doped carbon polyhedrons was constructed, and doped transition-metal domains were deliberately introduced on the surface. Theoretical investigations show that their energy level can be finely tuned via direct transition-metal doping engineering. As a prototype, Fe-doped NiCo2O4 nanosheets wrapped hollow nitrogen-doped carbon polyhedron (Fe-NiCo2O4@HNCP) exhibits outstanding bifunctional electrocatalytic performances with low overpotentials (η = 270 mV for OER, η = 84 mV for HER), low Tafel slopes (b = 42 mV dec-1 for OER, b = 47 mV dec-1 for HER), and high durability. The enhanced performance is attributed to the synergistic effects of energy level matching for electron transfer, and partial charge delocalization-induced rich active sites for reactant adsorption via thermodynamic and kinetic acceleration. This work may open a new pathway to design highly active and stable transtion-metal doped electrocatalysts by manipulated energy levels for efficient overall water splitting.
关键词： energy level engineering,water splitting,electrocatalysts,spinel-structured nanosheets,transition-metal doping
更新于2025-09-04 15:30:14
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Facile synthesis, morphology and tunable photoluminescence properties of BaMgF <sub/>4</sub> :Ce <sup>3+</sup> /Tb <sup>3+</sup> /Eu <sup>3+</sup> phosphors
摘要： A series of BaMgF4:Ce3+/Tb3+/Eu3+ phosphors were successfully prepared via a facile hydrothermal process. X-ray diffraction (XRD), energy dispersive spectrometry (EDS), scanning electron microscopy (SEM), n-UV–UV-vis photoluminescence (PL) and fluorescence decays were employed to investigate the structure, composition, morphology, luminescence properties and energy transfer processes. The as-prepared BaMgF4 phosphors exhibit a rod-like morphology and the size of the product can be effectively regulated by changing the amount of NH4F in the original solution. Under n-UV–UV light excitation, the Ce3+, Tb3+ and Eu3+ singly-doped BaMgF4 phosphors all show good characteristic luminescence; the Ce3+–Tb3+ and Tb3+–Eu3+ co-doped BaMgF4 phosphors both show tunable emission colors from blue (green) to green (orange-red) because of the energy transfer of Ce3+ → Tb3+ and Tb3+ → Eu3+, respectively. Moreover, the efficient energy transfer from Ce3+ (Tb3+) to Tb3+ (Eu3+) ions in the co-doped samples was confirmed by investigating the excitation/emission spectra and decay lifetimes. The results indicate that the phosphors may be potentially used as single-component multi-color phosphors for white light-emitting diodes.
关键词： energy transfer,BaMgF4,white light-emitting diodes,phosphors,hydrothermal process
更新于2025-09-04 15:30:14
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Dew as a Detrimental Influencing Factor for Soiling of PV Modules
摘要： Soiling of photovoltaic (PV) modules can significantly reduce their energy yield by reflecting or absorbing the incident light and is of great importance for operation and maintenance of PV systems in dusty environments. In this paper, we examine the influence of dew—which is formed on PV modules during night and early morning hours—on soiling processes. Outdoor experiments were performed in desert conditions in Qatar using unheated and heated glass samples supplied with different heating powers, as well as outdoor microscopy studies. In addition, laboratory soiling experiments were performed using different dust types, controlled dust removal by centrifugal forces at different relative humidity levels, and defined dew cycles. Results from both the field tests and laboratory soiling experiments showed a significant impact of dew on particle adhesion, removal, and corresponding soiling rates, which was independent of the dust type. Microstructural investigations using electron microscopy were performed to determine the cause of increased particle adhesion. Heating of glass surfaces during the night can significantly reduce the processes of cementation, particle caking, and capillary aging and, thus, reduce soiling. This study indicates that the prevention of condensation can be a method to mitigate soiling.
关键词： Photovoltaic systems,surface contamination,solar panels,solar energy
更新于2025-09-04 15:30:14
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Measuring dark energy with the <i>E</i> <sub/>iso</sub> – <i>E</i> <sub/>p</sub> correlation of gamma-ray bursts using model-independent methods
摘要： We use two model-independent methods to standardize long gamma-ray bursts (GRBs) using the Eiso ? Ep correlation (log Eiso = a + b log Ep), where Eiso is the isotropic-equivalent gamma-ray energy and Ep is the spectral peak energy. We update 42 long GRBs and attempt to constrain the cosmological parameters. The full sample contains 151 long GRBs with redshifts from 0.0331 to 8.2. The first method is the simultaneous fitting method. We take the extrinsic scatter σext into account and assign it to the parameter Eiso. The best-fitting values are a = 49.15 ± 0.26, b = 1.42 ± 0.11, σext = 0.34 ± 0.03 and Ωm = 0.79 in the flat ΛCDM model. The constraint on Ωm is 0.55 < Ωm < 1 at the 1σ confidence level. If reduced χ2 method is used, the best-fit results are a = 48.96 ± 0.18, b = 1.52 ± 0.08, and Ωm = 0.50 ± 0.12. The second method uses type Ia supernovae (SNe Ia) to calibrate the Eiso ? Ep correlation. We calibrate 90 high-redshift GRBs in the redshift range from 1.44 to 8.1. The cosmological constraints from these 90 GRBs are Ωm = 0.23+0.06?0.04 for flat ΛCDM and Ωm = 0.18 ± 0.11 and ΩΛ = 0.46 ± 0.51 for non-flat ΛCDM. For the combination of GRB and SNe Ia sample, we obtain Ωm = 0.271 ± 0.019 and h = 0.701 ± 0.002 for the flat ΛCDM and the non-flat ΛCDM, and the results are Ωm = 0.225 ± 0.044, ΩΛ = 0.640 ± 0.082, and h = 0.698 ± 0.004. These results from calibrated GRBs are consistent with that of SNe Ia. Meanwhile, the combined data can improve cosmological constraints significantly, compared to SNe Ia alone. Our results show that the Eiso ? Ep correlation is promising to probe the high-redshift Universe.
关键词： cosmological parameters,dark energy,gamma rays: general
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE International Symposium on Technologies for Homeland Security (HST) - Woburn, MA, USA (2018.10.23-2018.10.24)] 2018 IEEE International Symposium on Technologies for Homeland Security (HST) - Development of Dual Energy Container Inspection System for Harbor Security in KAERI
摘要： The use of multiple energy X-rays can provide additional information as compared to a single energy X-ray for the security inspection of cargo such as containers. Using the 9/6 MeV dual energy X-ray and material discrimination algorithms, it is possible to distinguish between low-density (organic) and high-density (inorganic) materials through the intended color mapping. The material discrimination algorithm can obtain the material information of the image used for screening by exploiting the characteristic that the energy-dependent attenuation coefficient is different even though the same material is used. Based on these technologies, we have developed a security inspection system for container cargo that consists of a radiation source, a detector array, four- collimators, a moving stage, and an imaging system. The radiation source was developed based on a dual-energy radio- frequency (RF) electron linear-accelerator (LINAC) with a spot size of 0.9 mm, and a 5.5 MW S-band magnetron was used as a RF generator. The detector is composed of 43 modules in one array and 32 channels per module, and the moving stage is designed and manufactured to transport cargo of up to 70 tons in the horizontal direction of the radiation beam at an optimized speed of 300 mm per second. The imaging system controls the whole process of the security inspection system from the operation of equipment to the acquisition and discrimination of images. In this paper, we introduce the characteristics of the developed inspection system and explain the results obtained by ANSI N42.46, the international recommendation scanner performance test.
关键词： Material decomposition,Dual-energy LINAC,Cargo Security Inspection System
更新于2025-09-04 15:30:14
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Simultaneous Wireless Strain Sensing and Energy Harvesting from Multiple Piezo-Patches for Structural Health Monitoring Applications
摘要： This paper presents a novel approach called simultaneous wireless strain sensing and energy harvesting (SWSSEH) from multiple piezo-patches, which is intended for self-powered structural health monitoring (SHM) applications. The EH subsystem is mainly the self-powered extended synchronous electric charge extraction (eSECE) interface based on double cross-coupled rectifying structure and a single flyback transformer, which is able to harvest energy from multiple piezo-patches. And, the WSS subsystem is mainly the low-power multiplexing analog front end (MAFE), which is designed to process the multichannel strain signals. The innovation of the proposed approach is that energy harvesting and strain sensing can actually work simultaneously without interfering with each other. The prototype is implemented based on discrete components and tested with an emulated SHM system. Experimental results show the EH subsystem can produce 5.45 mJ energy in 100 s under 108 με and 30.4 Hz dynamic strain. The average current consumption of the WSS subsystem is 7.53 μA, and the required energy in a 100 s is 2.49 mJ, which means the system is able to self-start even if the battery is exhausted. Additionally, the self-powered capacity can be further improved in a practical SHM system since more piezo-patches can be employed.
关键词： Simultaneous energy harvesting and sensing,multiple piezo-patches,self-powered
更新于2025-09-04 15:30:14
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Hybrid global maximum power point tracking algorithm under partial shading condition
摘要： This paper presents a hybrid global maximum power point tracking (MPPT) algorithm under partial shading conditions, which consists of five methods, including the global scanning method, the filtering method, the binary searching method, the three-point method, and the anti-restarting method. By making full use of the advantages of these methods, the proposed algorithm is able to improve tracking speed and efficiency, decrease oscillation, and avoid restarting. Among which, the global scanning method is used to find all the local intervals, the filtering method is used to reduce the search area, the binary searching method is used to reduce the search time, the three-point method is used to track the global maximum power point dynamically, and the anti-restarting method is used to prevent restarting the algorithm. To verify the proposed algorithm, experiments have been carried out in a standard environment, dynamic solar irradiation, and dynamic temperature, respectively. The performance of the proposed algorithm is verified by comparing it with a perturb and observe (P&O) based global scanning MPPT method and a modified P&O with checking MPPT method using computer simulations.
关键词： MPPT,global maximum power point tracking,photovoltaic systems,partial shading condition,hybrid algorithm,solar energy
更新于2025-09-04 15:30:14
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Direct comparison of pulsed spark discharges in air and water by synchronized electrical and optical diagnostics
摘要： In this study, a direct comparison was made between pulsed spark discharges in air and water in sub-mm gaps. The discharges were ignited at atmospheric pressure in the same discharge arrangement for air and water, using a solid-state microsecond pulse source with ≈1 μs voltage rise time (Umax up to 37 kV). Fast voltage and current measurements were synchronized with iCCD imaging with high spatial resolution on symmetrical half-sphere tungsten electrodes (electrode gaps of up to 0.7 mm for air and 0.3 mm for water). The breakdown voltage and electrical ?eld strength, maximal current, transferred charge, consumed electrical energy and discharge emission structure (e.g. discharge channel diameters) was obtained for all cases. Using the synchronization of the electrical data and the iCCD imaging, current and energy densities were estimated for the sparks in air and water. It was found that the breakdown voltage, the discharge current, the transferred charge, and the consumed electrical energy increase with the gap distance, and that this dependency is much stronger for discharges in water (compared to air). Due to the use of the same discharge arrangement and the same applied voltage, the di?erence in the discharge characteristics was directly quanti?ed.
关键词： energy density,spark discharges,water,optical diagnostics,breakdown voltage,electrical diagnostics,air,discharge current
更新于2025-09-04 15:30:14