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Impact of Subsystems on the Overall System Availability for the Large Scale Grid-connected Photovoltaic Systems
摘要： This paper demonstrates the impact of subsystem availability on a large scale grid-connected photovoltaic (PV) systems’ performance. Subsystem denotes to the installation of some subassemblies, which can be very small or gigantic in size, that serve this subsystem and the overall system. The analysis is largely based on a huge worldwide dataset of failures and repairs of various subassemblies, derived from different large scale grid-connected solar-PV systems. Major subsystems, such as a photovoltaic inverters (PVI), are also included, which are shown to have a signi?cant impact for improving on the overall system availability. An improved reliability block diagram (RBD) with an exponential probability distribution function is presented for estimating the reliability and availability performance of seven practical grid-connected solar-PV systems. In addition, availability importance measures are employed to rank various subsystems with regards to their impact on the overall system availability. Accordingly, it will be helping in identifying the subsystems that the planned maintenance should focus on in order to achieve the desired level of the availability. The secure operation of the system will be achieved by this approach. The implementation demonstrates the efficiency and the effectiveness of the proposed approach which may significantly contribute to enhancing the system availability.
关键词： reliability block diagram,failure rates,availability importance measures,repair rates,reliability,Photovoltaic systems,availability
更新于2025-09-12 10:27:22
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Overall efficiency enhancement and cost optimization of semitransparent photovoltaic thermal air collector
摘要： A semitransparent photovoltaic‐thermal (PV/T) air collector can produce electricity and heat simultaneously. To maximize the thermal and overall efficiency of the semitransparent PV/T air collector, its availability should be maximum; this can be determined through a Markov analysis. In this paper, a Markov model is developed to select an optimized number of semitransparent PV modules in service with five states and two states by considering two parameters, namely failure rate (λ) and repair rate (μ). Three artificial neural network (ANN) models are developed to obtain the minimum cost, minimum temperature, and maximum thermal efficiency of the semitransparent PV/T air collector by setting its type appropriately and optimizing the number of photovoltaic modules and cost. An attempt is also made to achieve maximum thermal and overall efficiency for the semitransparent PV/T air collector by using ANN after obtaining its minimum temperature and available solar radiation.
关键词： availability,semitransparent,ANN,photovoltaic‐thermal (PV/T) air collector
更新于2025-09-12 10:27:22
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Estimating below‐canopy light regimes using airborne laser scanning: An application to plant community analysis
摘要： Light is a key driver of forest biodiversity and functioning. Light regimes beneath tree canopies are mainly driven by the solar angle, topography, and vegetation structure, whose three‐dimensional complexity creates heterogeneous light conditions that are challenging to quantify, especially across large areas. Remotely sensed canopy structure data from airborne laser scanning (ALS) provide outstanding opportunities for advancement in this respect. We used ALS point clouds and a digital terrain model to produce hemispherical photographs from which we derived indices of nondirectional diffuse skylight and direct sunlight reaching the understory. We validated our approach by comparing the performance of these indices, as well as canopy closure (CCl) and canopy cover (CCo), for explaining the light conditions experienced by forest plant communities, as indicated by the Landolt indicator values for light (Llight) from 43 vegetation surveys along an elevational gradient. We applied variation partitioning to analyze how the independent and joint statistical effects of light, macro‐climate, and soil on the spatial variation in plant species composition (i.e., turnover, Simpson dissimilarity, βSIM) depend on light approximation methodology. Diffuse light explained Llight best, followed by direct light, CCl and CCo (R2 = .31, .23, .22, and .22, respectively). The combination of diffuse and direct light improved the model performance for βSIM compared with CCl and CCo (R2 = .30, .27 and .24, respectively). The independent effect of macroclimate on βSIM dropped from an R2 of .15 to .10 when diffuse light and direct light were included. The ALS methods presented here outperform conventional approximations of below‐canopy light conditions, which can now efficiently be quantified along entire horizontal and vertical forest gradients, even in topographically complex environments such as mountains. The effect of macroclimate on forest plant communities is prone to be overestimated if local light regimes and associated microclimates are not accurately accounted for.
关键词： canopy structure,forest biodiversity,remote sensing,light availability,microclimate,Ellenberg indicator value,beta diversity,hemispherical photography,biodiversity,airborne light detection and ranging LiDAR
更新于2025-09-11 14:15:04
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AIP Conference Proceedings [AIP Publishing ADVANCES IN BASIC SCIENCE (ICABS 2019) - Bahal, India (7–9 February 2019)] ADVANCES IN BASIC SCIENCE (ICABS 2019) - Profit analysis of a uni-directional and non revertible 1+1 protection switching scheme in optical communication process
摘要： The present paper examines availability and profit analysis of a system comprising four optical lines out of which two are operative (working paths) and the other two are hot-standby (protection paths). Each working line has its own hot standby. On the failure of the working path, signal is received from its own protection path and the failed unit is gone under repair immediately by a repairman. If a working path and its corresponding protection path both get failed then system is said to be failed. The system is analyzed by making use of regenerative point technique. Various measures of system effectiveness as well as expression for finding the profit have been obtained.
关键词： 1+1 Protection Scheme,availability,reliability,profit analysis
更新于2025-09-11 14:15:04
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[IEEE 2018 20th International Conference on Transparent Optical Networks (ICTON) - Bucharest (2018.7.1-2018.7.5)] 2018 20th International Conference on Transparent Optical Networks (ICTON) - A Proactive Restoration Strategy for Optical Cloud Networks Based on Failure Predictions
摘要： Failure prediction based on the anomaly detection/forecasting is becoming a reality thanks to the introduction of machine learning techniques. The orchestration layer can leverage on this new feature to proactively reconfigure cloud services that might find themselves traversing an element that is about to fail. As a result, the number of cloud service interruptions can be reduced with beneficial effects in terms of cloud service availability. Based on the above intuition, this paper presents an orchestration strategy for optical cloud networks able to reconfigure vulnerable cloud services (i.e., the ones that would be disrupted if a predicted failure happens) before an actual failure takes place. Simulation results demonstrate that, with a single link failure scenario, proactive restoration can lead to up to 97% less cloud services having to be relocated. This result brings considerable benefits in terms of cloud service availability, especially in low load conditions. It is also shown that these improvements come with almost no increase in the cloud service blocking probability performance, i.e., resource efficiency is not impacted.
关键词： Cloud services,Software defined networking (SDN),Availability,Failure prediction,Orchestration,Cloud service relocation,Resiliency,Proactive recovery,Restoration
更新于2025-09-10 09:29:36
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[IEEE 2018 Systems of Signals Generating and Processing in the Field of on Board Communications - Moscow (2018.3.14-2018.3.15)] 2018 Systems of Signals Generating and Processing in the Field of on Board Communications - An assessment of the availability factor of fiber-optic communication lines with consideration of external actions and diagnosis errors
摘要： A method of the determination of the fiber-optic communication lines reliability taking into account the effect of the optical fiber tension, the temperature influence and the built-in diagnostic equipment errors is discussed in this article. The reliability is assessed using the theory of Markov chains and probabilistic mathematical modeling. The reliability is assessed in terms of the availability factor. According to the permissible value of the availability factor, it is possible to determine the fiber-optic limiting communication lines. The work was performed with the financial support of the Ministry of Education and Science of the Russian Federation (Project No. 8.9334.2017/8.9)
关键词： diagnostic errors,fiber-optic communication line,availability factor,tension,mathematical model,optical fiber
更新于2025-09-09 09:28:46
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Model-based Pileup Events Correction Via Kalman-Filter Tunnels
摘要： A Kalman-?lter-based method is proposed to address challenges in nuclear signal processing, including pileup events and noise cancellation. The state-transition equation is established on the basis of suitable pulse-shape models. By regarding the output signal of particle detectors as a measurable variable, the measurement equation is also introduced to correct dynamic processes of the state transition. A linear Kalman ?lter with n tunnels is constructed to separate pileup events and maintain the original waveforms of pulses. In addition, two terms are de?ned and addressed for separation operations, namely, Availability, which is used to prepare for upcoming events, and Clearance Mechanism, which is given to remove thumbnail information from previous events and make occupied tunnels available to subsequent nuclear events. Simulation and ?eld experiments demonstrate that the proposed method can handle critical situations of pulse pileup and minimize count loss and dead time in the X-ray energy spectrum while maintaining original pulse shapes.
关键词： Noise Cancellation,Tunnel,Kalman Filter,Availability,Energy Spectrum,Pulse Pileup
更新于2025-09-09 09:28:46