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Forecasting photovoltaic and wind energy capital costs in Japan: A Bayesian approach
摘要： This study used a Bayesian approach to estimate the future capital costs of photovoltaics and wind energy in Japan. In the proposed approach, the future cost estimated by different cost estimation methods is compounded by observing actual costs during specific periods. This study used capital costs estimated in previous studies conducted after 2011 and data on the actual costs between 2015 and 2017 in Japan as input data. This study discussed the validity of this approach by comparing the compounded value with the actual cost in 2017. The result of the comparison indicates that the cost estimates obtained using the Bayesian approach are especially valid in the case wherein actual costs lie within the estimated cost range. Capital costs in 2030 are also estimated using the Bayesian approach. The probability density distribution of the capital cost in 2030 is updated to the upper side of the estimated cost range by observing the actual costs. The result obtained by this reductive approach indicates that the capital costs in 2030 are expected to lie in the upper side of the estimated cost range in Japan.
关键词： Bayesian approach,Energy policy,Renewable energy,On-shore wind,Photovoltaics,Off-shore wind
更新于2025-09-12 10:27:22
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Ultrasensitive Fiber-based ZnO Nanowire Network Ultraviolet Photodetector Enabled by the Synergism of Interface and Surface Gating Effects
摘要： Flexible UV photodetector with high on/off ratio is extremely important for environmental sensing, optical communication and flexible optoelectronic devices. In this work, a flexible fiber-based UV photodetector with ultrahigh on/off ratio is developed by utilizing the synergism between interface and surface gating effects on ZnO nanowire network structure. The synergism of two gating effects is realized by the interplay of surface band bending and the Fermi level through nanowire-network structure, which is proved through the control experiments between ZnO micro/nanowire photodetector and micro/nanowire-junction photodetector, and the corresponding KPFM measurements. The on/off ratio of fiber-based ZnO nanowire-network UV photodetector reaches 1.98×108 when illuminated by 1.0 mW cm?2 UV light, which is 20 times larger than the largest reported result under the same UV illumination. This new UV sensor also has the high resolution to UV light intensity change in nW cm?2 range. Furthermore, when the fiber-based photodetector is curved, it still shows the excellent performance as above. This work gives a new effective route for the development of high-performance UV photodetector or other optoelectronic detection devices.
关键词： ZnO,synergetic gating effects,flexible electronics,UV photodetectors,on/off ratio
更新于2025-09-12 10:27:22
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Investigation on Thermally Induced Efficiency Roll-Off: Toward Efficient and Ultrabright Quantum-Dot Light-Emitting Diodes
摘要： Quantum-dot light-emitting diodes (QLEDs) with high brightness have potential application in lighting and display. The high brightness is realized at high current density (J). However, at high J, the efficiency drops significantly, thereby limiting the achievable brightness. This notorious phenomenon has been known as efficiency roll-off, which is likely caused by the Auger- and/or thermal-induced emission quenching. In this work, we show that the Joule heat generated during device operation significantly affects the roll-off characteristics of QLEDs. To realize ultra-bright and efficient QLEDs, the thermal stability of QDs is improved by replacing the conventional oleic acid ligands with 1-dodecanethiol. By further using a substrate with high thermal conductivity, the Joule heat generated at high J is effectively dissipated. Because of the effective thermal management, thermal-induced emission quenching is significantly suppressed, and consequently, the QLEDs exhibit a high external quantum efficiency (EQE) of 16.6%, which is virtually droop-free over a wide range of brightness (e.g., EQE=16.1% @ 105 cd/m2 and 140 mA/cm2). Moreover, due to the reduced efficiency roll-off and enhanced heat dissipation, the demonstrated QLEDs can be operated at a very high J up to 3885 mA/cm2, thus enabling the devices to exhibit a record-high brightness of 1.6×106 cd/m2 and a lumen density of 500 lm/cm2. Our work demonstrates the significance of thermal management for the development of droop-free and ultra-bright QLED devices for a wide variety of applications including lighting, transparent display, projection display, outdoor digital signage, phototherapy and etc.
关键词： high brightness,light-emitting diodes,quantum dot,thermal energy,efficiency roll-off
更新于2025-09-12 10:27:22
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[IEEE 2018 Asia Communications and Photonics Conference (ACP) - Hangzhou (2018.10.26-2018.10.29)] 2018 Asia Communications and Photonics Conference (ACP) - Energy Optimization with Passive WDM Based Fronthaul in Heterogeneous Cellular Networking
摘要： We propose a passive wavelength division multiplexing based fronthaul architecture for heterogeneous cellular networking, and a threshold based on/off algorithm for micro cells. Simulation results show that our algorithm significantly saves energy than traditional solutions.
关键词： fronthaul bandwidth,energy consumption,wavelength division multiplexing (WDM),switch on/off
更新于2025-09-12 10:27:22
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Performance evaluation for polarization shift keying modulation in atmospheric turbulence channel
摘要： The exponentiated Weibull (EW) distribution is adopted for all turbulence strengths when aperture averaging technology is applied. Firstly, the closed expression of the average bit error rate (BER) of a free space optical (FSO) system using polarization shift keying (POLSK) modulation under EW atmosphere turbulence model is derived. Then the effects of aperture averaging under different turbulence conditions described by the EW distribution are numerically studied with computer simulation, and the average BER of POLSK modulated system is compared with that of an on-off-keying (OOK) system. Numerical results show the effects of aperture averaging on the average BER under different turbulence strengths. The POLSK modulated FSO systems can offer better BER performance compared to OOK scheme.
关键词： average bit error rate,exponentiated Weibull distribution(EW),Polarization shift keying modulation(POLSK),aperture averaging,on-off-keying (OOK)
更新于2025-09-12 10:27:22
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[IEEE 2019 21st International Conference on Transparent Optical Networks (ICTON) - Angers, France (2019.7.9-2019.7.13)] 2019 21st International Conference on Transparent Optical Networks (ICTON) - Assessment of the Combined Effect of Laser Phase Noise and Intercore Crosstalk on the Outage Probability of DD OOK Systems
摘要： We study the influence of the combined effect of laser phase noise and intercore crosstalk on the outage probability of direct-detection 10 Gbit/s on-off keying optical communication systems. We show that the laser phase noise can affect significantly the outage probability, for lasers with linewidths in the MHz range, for low and high skew-bit rate products. We also show that the laser phase noise effect on the received eye-pattern is qualitatively similar to the one found for high skew-bit rate product in the absence of laser phase noise.
关键词： intercore crosstalk,on-off keying,multicore fiber,laser phase noise,outage probability
更新于2025-09-12 10:27:22
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[IEEE 2019 IEEE 17th World Symposium on Applied Machine Intelligence and Informatics (SAMI) - Herlany, Slovakia (2019.1.24-2019.1.26)] 2019 IEEE 17th World Symposium on Applied Machine Intelligence and Informatics (SAMI) - Computer Based Model for an Off-Grid Photovoltaic System with no DC – DC Adapter
摘要： This article describes a solar energy system, operating off-grid, having either a single photovoltaic panel - PV, or a group of multiple PVs, grouped in a simple solar battery-SB, directly supplying an electric battery-EB, or a group of EBs, having no DC-DC adapter (a buck, a boost or a combination of them, a classic solution available on the market). That SB must be adjusted to the voltage of the EB, in order to supply the same amount of electric energy as when the system functions at its mathematically detected maximum power operating point, on a MPP command strategy. This newly discussed technical solution could be less expensive, compared to the actual one which involves a SB, a DC-DC converter and the EB. It is a cost reduction because that DC-DC converter is no longer used at all. It requires a computer aided model for implementing the current-voltage characteristics. The results of this model will be compared with the classic DC-DC converter solution results, in order to prove validity.
关键词： Photovoltaic System,Direct Supply,Off-Grid,MPP
更新于2025-09-12 10:27:22
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A Methodology to Develop Design Support Tools for Stand-alone Photovoltaic Systems in Developing Countries
摘要： As pointed out in several analyses, Stand-Alone Photovoltaic systems may be a relevant option for rural electrification in Developing Countries. In this context, Micro and Small Enterprises which supply customized Stand-Alone Photovoltaic systems play a pivotal role in the last-mile-distribution of this technology. Nevertheless, a number of issues limit the development of these enterprises curbing also potential spinoff benefits. A common business bottleneck is the lack of technical skills since usually few people have the expertise to design and formulate estimates for customers. The long-term solution to tackle this issue implies the implementation of a capacity building process, but this solution rarely matches with time-to-market urgency of local enterprises. Therefore, we propose in this study a simple, but general methodology which can be used to set up Design Support Tools for Micro and Small Enterprises that supply Stand-Alone Photovoltaic systems in rural areas of Developing Countries. After a brief review of the techniques and commercial software available to design the targeted technology, we describe the methodology highlighting the structure, the sizing equations and the main features that should be considered in developing a Design Support Tool. Then, we apply the methodology to set up a tool for use in Uganda and we compare the results with two commercial codes (NSolVx and HOMER). The results show that the implemented Design Support Tool develops correct system designs and presents some advantages for being disseminated in rural areas. Indeed it supports the user in providing the input data, selecting the main system components and delivering estimates to customers.
关键词： rural electrification,off-grid systems,Uganda,solar photovoltaic,micro and small enterprises,Design techniques
更新于2025-09-12 10:27:22
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[IEEE 2019 6th International Conference on Space Science and Communication (IconSpace) - Johor Bahru, Malaysia (2019.7.28-2019.7.30)] 2019 6th International Conference on Space Science and Communication (IconSpace) - Koch Fractal Loop Circular Polarization (CP) Antenna Integrated with Solar Cells
摘要： Minimal profile antennas for wireless devices which characteristics consisted of being low cost, highly reliable, and lightweight, it bears a new challenge for the design of the antenna in wireless communications. In this paper, we propose a design of circularly polarized microstrip patch antenna integration with solar cells for green wireless applications. Two techniques have been proposed to form the prototype between the communication system (design of antenna) and solar panel (solar cell). Both methods will face two issues generally; the solar system needs to get 100% sunlight and the magnetic field produced by radio communication systems as well as the electric field produced by solar cells should not affect the efficiency. The antenna is composed of a Koch fractal loop patch and the substrate is employed using a transparent material. This enables the light to pass through with high efficiency to illuminate the solar panel cells while the RF performance is maintained with minimal degradation. The communication frequency measures 2.6, 3.5 and 4.4 GHz. CST MWS simulation is also studied and compared among the different substrates which show different results based on the same parameters, which is implemented with a lattice of 2×2 square solar cells. With this arrangement, the solar cells will be able to obtain 100% of sunlight exposure. The characteristics of the broadband are achieved by combining resonances and the minimum axial ratio points created by the driven patch and solar cell surface.
关键词： Trade-off RF transparency,Wireless communication,transparent substrate,Microstrip patch antenna,Compact Meshed patch antenna,integration antenna and solar panel,CST MWS,performances and Frequency,Gain
更新于2025-09-12 10:27:22
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Picosecond laser lift-off method for fracture and debonding of copper oxide layer grown on copper substrate
摘要： The objective of this work is to investigate the ablative removal behavior of copper oxide under the picosecond laser ( pulse duration 12 ps and wavelength 1064 nm) irradiation. For this purpose, a thin CuO layer with a thickness of about 750 nm is synthesized on a pure copper substrate by the dipping method to serve as the target samples for experimental tests. It is shown that, unlike the pure ablation behavior, the removal process of the CuO layer is mainly based on the nonthermal lift-o? e?ect, by which the stripping of the whole piece of oxide ?lms from the substrate can be achieved with a single pulse shot. A minimum ?uence required for peeling o? the layer is determined to be about 0.11 J/cm2. Further analyses demonstrate that the entire pop-o? of the CuO layer caused by the con?ned ablation at the interface occurs only if the laser ?uences are applied below 0.62 J/cm2. However, when it comes to the cases at higher ?uences, a thin residual layer can be observed remaining on the substrate. To explain this phenomenon, a plausible interpretation with respect to the ablation induced by nonlinear absorption and impact ionization is proposed, which declares that it is the combination of direct ablation and the interface lift-o? that ultimately causes such special removal features. In addition, the in?uence of the oxide ?lm thickness on the debonding threshold and the removal behavior are additionally assessed.
关键词： lift-off effect,damage threshold,thin oxide ?lms,laser selective removal
更新于2025-09-12 10:27:22