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Evaluation of the reliability of solar micro-grids in emerging markets – Issues and solutions
摘要： One of the most important technical features of a power system is its ability to deliver electricity reliably to the customers. Based on interviews with 12 energy service companies (ESCO) currently operating solar micro-grids in northern rural India, this study identified important factors related to technical design, customer behaviour and operations and management (O&M) that may result in contingencies in service. In addition, the study presents companies' innovative solutions to overcome these problems. Initially, the interview method allowed only a rough qualitative comparison of different reliability levels as the availability of comparable data was limited. We found that a more descriptive method for reliability assessment would create equally valuable information on renewable off-grid energy projects. We propose a simple framework for assessing reliability that highlights the particular features of off-grid areas in developing countries.
关键词： Reliability,Micro-grid,Energy systems in developing countries,India,Technical sustainability,Reliability assessment
更新于2025-09-23 15:21:21
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AIP Conference Proceedings [Author(s) SolarPACES 2017: International Conference on Concentrating Solar Power and Chemical Energy Systems - Santiago, Chile (26–29 September 2017)] - Experimental evaluation of volumetric solar absorbers – Ceramic foam vs. an innovative rotary disc absorber concept
摘要： This paper presents the experimental evaluation of two volumetric solar absorber concepts. It compares the thermal performance of conventional foam absorbers with that of an innovative rotary disc absorber design. The moving absorber showed advantages regarding air temperature stability at the outlet and better operability compared to the foam absorber. Unfortunately, it is shown that the innovative rotary disc design in its present form is not competitive, neither in terms of thermal performance, nor regarding mechanical reliability and robustness. The future task is therefore to optimize the mechanical design regarding thermal fatigue, in order to obtain a robust and durable rotary absorber that can be thoroughly evaluated experimentally.
关键词： volumetric solar absorbers,ceramic foam,thermal performance,rotary disc absorber,mechanical reliability
更新于2025-09-23 15:21:21
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[IEEE 2018 5th IEEE International Workshop on Metrology for AeroSpace (MetroAeroSpace) - Rome, Italy (2018.6.20-2018.6.22)] 2018 5th IEEE International Workshop on Metrology for AeroSpace (MetroAeroSpace) - Active Fault Tolerant Gyromoment Control of Information Satellites and Free-flying Robots
摘要： The methods for modeling and detection of anomalous in the automatic control systems, and also practical methods for active analysis of anomalous situations, are presented. We develop algorithms for consecutive classification of onboard equipment failures and for reconfiguration of control loop. The simulation results are presented for the control systems of the information satellites and free-flying robots.
关键词： free-flying robots,gyromoment control,automatic control systems,fault detection and isolation (FDI),dynamic reliability,fault-tolerance,information satellites
更新于2025-09-23 15:21:21
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[ASME ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems - San Francisco, California, USA (Monday 27 August 2018)] ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems - The Effects of Temperature, Strain Rate, and Aging on the Poisson’s Ratio of SAC Lead Free Solders
摘要： In this study, we have conducted a combined numerical and experimental study on the Poisson’s ratio of SAC lead free solders. The Poisson’s ratio (PR) is one of the basic mechanical properties used in many material constitutive models. Although often not measured, it is important property in many finite element method (FEM) calculations. The value of the Poisson’s ratio of SAC lead free solders is relatively unexplored compared to other material properties, and for FEA simulations it is typically assumed to be ? = 0.3. In the current work, we have shown the effects of the chosen value of the solder joint Poisson’s ratio on the finite element results for BGA components subjected to thermal cycling. In the finite element models, the reliability predictions were based on the Morrow-Darveaux energy-based fatigue model. Several sizes (5, 10, 15 mm) of PBGA components with SAC305 solder joints with 0.4 and 0.8 mm spacing were modeled. The packages were subjected to a time dependent cyclic temperature distribution from -40 to 125 oC. The package assemblies were assumed to be in a stress-free state at 25 oC (room temperature), with no residual stresses induced in the manufacturing process. The simulation results have demonstrated that for specified range of Poisson’s ratio values of 0.15 < ??< 0.40, the solder Plastic Work varied over 20% and the Predicted Reliability Varied over 50%. To determine the actual Poisson’s ratio experimentally, uniaxial tensile stress-strain tests were carried out on SAC305 (96.5Sn3.0Ag0.5Cu) specimens using a micro tension/torsion testing machine with two strain rates (0.0001, and 0.00001 (sec-1)), four testing temperatures (T = 25, 50, 75, 100 oC), and several durations of prior aging at T = 125 oC. Deformations and strains in axial and transverse directions were measured using strain gages with automatic data acquisition from LabVIEW software. The recorded transverse strain vs. axial strain data were then fit with a linear regression analysis to determine the Poisson’s ratio values. A test matrix of experiments was developed to study the effects of temperature, strain rate, alloy composition, and solidification cooling profile on the value of solder Poisson’s ratio. The Poisson’s ratio was found to increase with increasing temperature, and decrease with increasing strain rate. Using a slower solidification cooling profile led to an increase in the solder Poisson’s ratio value. Finally, the microstructural coarsening that occurs during isothermal aging lead to an increase in the Poisson’s ratio.
关键词： FEA,Lead Free Solder,Reliability,DAQ,PBGA Packaging
更新于2025-09-23 15:21:21
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Reliability and validity of the iSense optical scanner for measuring volume of transtibial residual limb models
摘要： Background: Residual limb volume is often measured as part of routine care for people with amputations. These measurements assist in the timing of prosthetic fitting or replacement. In order to make well informed decisions, clinicians need access to measurement tools that are valid and reliable. Objectives: To assess the reliability and criterion validity of the iSense optical scanner in measuring volume of transtibial residual limb models. Study Design: Three assessors performed two measurements each on 13 residual limb models with an iSense optical scanner (3D systems, USA). Intra-rater and inter-rater reliability were calculated using intraclass correlation coefficients. Bland Altman plots were inspected for agreement. Criterion validity was assessed using a steel rod of known dimensions. Ten repeated measurements were performed by one assessor. A t-test was used to determine differences between measured and true rod volume. Results: Intra-rater reliability was excellent (range of intraclass correlation coefficients: 0.991–0.997, all with narrow 95% confidence intervals). While the intraclass correlation coefficients suggest excellent inter-rater reliability between all three assessors (range of intraclass correlation coefficients: 0.952–0.986), the 95% confidence intervals were wide between assessor 3 and the other two assessors. Poor agreement with assessor 3 was also seen in the Bland-Altman plots. Criterion validity was very poor with a significant difference between the mean iSense measurement and the true rod volume (difference: 221.18 mL; p < 0.001). Conclusions: Although intra-rater reliability was excellent for the iSense scanner, we did not find similar results for inter- rater reliability and validity. These results suggest that further testing of the iSense scanner is required prior to use in clinical practice.
关键词： validity,residual limb,Reliability,volume
更新于2025-09-23 15:21:21
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - The Impact of Cold Temperature Exposure in Mechanical Durability Testing of PV Modules
摘要： Existing mechanical durability testing sequences typically perform mechanical loading prior to environmental exposures such as thermal cycling or humidity freeze. Recent work has shown that the fracture strength of silicon solar cells can reduce after exposure to temperatures below -20°C. In an effort to better evaluate modules with respect to cell crack durability, we explore the use of a single thermal cycle prior to mechanical loading. Modules were exposed to a static front-side load before and after exposure to a single thermal cycle and were characterized with current-voltage measurements and electroluminescence imaging. The results show a significant increase in the number of cell cracks that are generated at a given load after a single cold exposure. We explore how this can be used to further optimize the qualification test sequence for mechanical durability.
关键词： cell fracture,photovoltaic modules,mechanical durability,reliability,silicon
更新于2025-09-23 15:21:01
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Selection of optimal wavelengths for optical soiling modelling and detection in photovoltaic modules
摘要： Soiling impacts the photovoltaic (PV) module performance by reducing the amount of light reaching the photovoltaic cells and by changing their external spectral response. Currently, the soiling monitoring market is moving toward optical sensors that measure transmittance or reflectance, rather than directly measuring the impact of soiling on the performance of photovoltaic modules. These sensors, which use a single optical measurement, are not able to correct the soiling losses that depend on the solar irradiance spectra and on the spectral response of the monitored PV material. This work investigates methods that can improve the optical detection of soiling by extracting the full soiling spectrum profiles using only two or three monochromatic measurements. Spectral transmittance data, measured with a spectrophotometer and collected during a 46-week experimental soiling study carried out in Ja?en, Spain, was analysed in this work. The use of a spectral profile for the hemispherical transmittance of soiled PV glass is found to significantly improve the soiling detection, returning the lowest errors independently of the PV materials and irradiance conditions. In addition, this work shows that it is also possible to select the measurement wavelengths to minimize the soiling loss detection error depending on the monitored PV semiconductor material (silicon, CdTe, a-Si, CIGS and a representative perovskite). The approaches discussed in this work are also found to be more robust to potential measurement errors compared to single wavelength measurement techniques.
关键词： Soiling,Dust,Optical modelling,Photovoltaic,Spectral losses,Reliability
更新于2025-09-23 15:21:01
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[IEEE 2020 International Conference on Computing, Networking and Communications (ICNC) - Big Island, HI, USA (2020.2.17-2020.2.20)] 2020 International Conference on Computing, Networking and Communications (ICNC) - On Performance of Multiuser Underwater Wireless Optical Communication Systems
摘要： This paper presents an apparatus and methodology for an advanced accelerated power cycling test of insulated-gate bipolar transistor (IGBT) modules. In this test, the accelerated power cycling test can be performed under more realistic electrical operating conditions with online wear-out monitoring of tested power IGBT module. The various realistic electrical operating conditions close to real three-phase converter applications can be achieved by the simple control method. Further, by the proposed concept of applying the temperature stress, it is possible to apply various magnitudes of temperature swing in a short cycle period and to change the temperature cycle period easily. Thanks to a short temperature cycle period, test results can be obtained in a reasonable test time. A detailed explanation of apparatus such as configuration and control methods for the different functions of accelerated power cycling test setup is given. Then, an improved in situ junction temperature estimation method using on-state collector–emitter voltage VC E O N and load current is proposed. In addition, a procedure of advanced accelerated power cycling test and test results with 600 V, 30 A transfer molded IGBT modules are presented in order to verify the validity and effectiveness of the proposed apparatus and methodology. Finally, physics-of-failure analysis of tested IGBT modules is provided.
关键词： power cycling test,physics-of-failure,Failure mechanism,lifetime model,insulated-gate bipolar transistor module,reliability
更新于2025-09-23 15:21:01
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In vitro reliability testing and in vivo lifespan estimation of wireless Pixium Vision PRIMA photovoltaic subretinal prostheses suggest prolonged durability and functionality in clinical practice
摘要： Objective. Retinal implants have the potential to restore some sight in patients with retinal degeneration. The PRIMA implant’s novel design features simpler insertion and no transscleral cabling or extraocular components. This in vitro study investigated PRIMA’s durability under real time and accelerated conditions and estimated the device’s lifespan in vivo. Approach. Two potential failure modes were examined: corrosion and overstimulation. Real-time aging was tested using implants immersed in balanced saline solution (BSS) at 37°C, mimicking the intraocular environment. Accelerated aging was examined at 77°C (Arrhenius theory). Confirmatory testing of acceleration factor was performed using different temperatures (37°C-87°C) and weakened implant coatings. The effect of repeated maximum stimulation was tested using a pulsed infrared laser (6x acceleration factor). Data were used to estimate device lifespan. Main results. 175 implants were tested for up to 33 months. No corrosion or water ingress was observed after approximately 20 accelerated years. A pixel failure rate of 0.15% was recorded after 10 accelerated years’ stimulation. The derived lifespan estimation for the PRIMA implant was 27.0 years with a reliability of 90% (95% confidence interval). Significance. The PRIMA implant was found to be robust, with in vitro reliability of at least ten years. The PRIMA implant shows durability and functionality for clinically relevant timespans under similar environmental conditions to the human eye. These results require in vivo confirmation.
关键词： implant corrosion,reliability,retinal prosthesis,lifespan,subretinal
更新于2025-09-23 15:21:01
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[IEEE 2019 14th International Microsystems, Packaging, Assembly and Circuits Technology Conference (IMPACT) - Taipei, Taiwan (2019.10.23-2019.10.25)] 2019 14th International Microsystems, Packaging, Assembly and Circuits Technology Conference (IMPACT) - Innovative System in Package Design by Laser Ablation Technology
摘要： The 5G revolution brings a lot innovative impact in various applications and business opportunities in mobility, automotive, insdustrial automation and healthcare globally. Therefore, the muti-function integration, form factor miniaturization and time to market of IC package design become the necessary trend in electronic assembly technology. Obviously, system in package (SiP) is the capable solution to meet these requirments and widely applied in the IOT, automotive and sensor module currently. However, the conventional singulation process by blade sawing technology exists the burr residual, inflexible package shape forming and inaccuracy tolerance controlling challenges that brings about low yield and limited package shape design. In this research, the sigulation and metal lid by laser ablation technology in various system in package applications are demonstrated, the metal lid discoloration and burr residual defeat are successfully eliminated by pico second pulses laser technology which shorten the energy absorption time from laser light to electrons and improve the heat-affected zone (HAZ) damage on sawing edge during the ablation process. Therefore, the design of experiment (DOE) shows that the metal lid discoloration rate have been greatly improved from 25% to 0% and without the burr residual issue by utilizing UV laser ablation process. In addition, the package shape forming by UV laser is also studied in this paper, the various geometrical shape that including circle, hexagon and qctagon package appearance are fabricated within 30 um cutting tolerance while without any chipping residual on cutting edge, thus, this formnig technology have been widely applied in various fingerprint sensor and particular module applications in smartphone and automotive industry. The typical reliability testing (Temperature Cycle Test, Hight Temperature Storage Test and unbias HAST) results as a verification. By employing this advanced UV laser ablation technology, the package forming quality and sawing accuracy control can be improved obviously compare to the topically blade sawing process. Undoubtedly, the UV laser ablation with pico pluse technology is absolutely the innovative and powerful weapon to accomplish the high quality SiP design in 5G generation.
关键词： 5G,pico second pulses laser,laser ablation technology,UV laser,package forming,reliability testing,system in package (SiP)
更新于2025-09-23 15:21:01