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Challenges in the pre-normative characterization of bifacial photovoltaic modules
摘要： Bifacial photovoltaic (PV) technology is receiving growing interest on the market, with several companies commercializing bifacial modules alongside their conventional products, with various c-Si structures, such as PERC, PERT, HIT, IBC, etc. Current-voltage characterization of bifacial PV modules at Standard Test Conditions (STC) is challenging, as it requires an extension of the definition of STC that includes the spectral and total irradiance on the rear side of the module. Indoor characterization in principle allows the most accurate control of these quantities: the simplest procedure involves measurements of each side of the bifacial module at a time with a single light source, while carefully keeping the other side in the dark. This procedure requires attention to minimize unintended contributions to the module power from the non-illuminated side, which is associated to the reflected irradiance from surroundings, to the optical properties of the module, and to the geometrical disposition of the cells. This work revises the pre-normative activity that has led to the draft standard IEC 60904-1-2 (due for publication in 2018) and focuses on the new norm in what concerns indoor measurement with a single-source simulator. It illustrates the metrological challenges in the selection of the non-reflective material behind the non-illuminated side, and their impact to the electrical characterization of bifacial modules.
关键词： Electrical characterization,Standard Test Conditions,Solar simulators,Bifacial photovoltaic modules
更新于2025-09-12 10:27:22
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An Effective Method On Evaluating Photovoltaic Module Snail Trail
摘要： Although in recent years photovoltaic module snail trails have been extensively studied, when it comes to development of photovoltaic modules, it remains difficult to find the suitable method to evaluate what materials cause snail trails. The key is how to make the sample suitable for test so that it can generate snail trials. This paper intends to solve this problem and determine suitable test conditions to accelerate the occurrence of snail trails. An experimental comparison is also made to evaluate different test samples made with different combinations of materials.
关键词： snail trails,module reliability test,Snail trail,PV module defects
更新于2025-09-12 10:27:22
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Erbium:YAG laser treatment of female stress urinary incontinence: midterm data
摘要： Introduction and hypothesis Stress urinary incontinence (SUI) is treated using intravaginal laser therapy. We wanted to find out how incontinence severity at baseline and the number of laser interventions affect success rate, and whether the effect of laser therapy was obvious 6 months and 2 years after the last laser intervention. Methods Fifty-nine women, 32 with SUI I, 16 with SUI II, and 11 with SUI III were treated using an erbium-doped yttrium aluminium garnet (Er:YAG) laser following the IncontiLase? protocol. Therapy included five laser sessions with a 1-month interval between sessions. Objective (1-h pad test) and subjective data (International Consultation on Incontinence Questionnaire-Urinary Incontinence Short Form [ICIQ-UI SF], Pelvic Organ Prolapse/Urinary Incontinence Sexual Questionnaire [PISQ-12]) were assessed at baseline, after two and four laser sessions and 6 months and 2 years after the fifth laser session. Results Objective cure/improve rates for mild SUI I were 69%, 78%, 91%, and 78% after two, four, and five laser sessions at the 6-month and 2-year follow-ups. Subjective cure rates (ICIQ-UI SF) were 53%, 69%, 72%, and 66%, and sexual function (PISQ-12) also improved. For SUI II, objective cure/improve rates were 31%, 63%, 69%, and 50%. Subjective cure rate was 13% at the 2-year follow-up. For SUI III, only one patient had an objective improvement after two and four laser sessions. Conclusions Intravaginal laser therapy led to cure/improvement for SUI I and SUI II, but not for severe SUI III. Outcome was better after four to five laser sessions than after two laser sessions. Follow-up data 6 months and 2 years after laser intervention showed sustainability of the treatment.
关键词： ICIQ-UI SF,1-h pad test,Stress urinary incontinence,Intravaginal laser therapy,Erbium:YAG laser,Non-ablative SMOOTH mode
更新于2025-09-12 10:27:22
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Influence of surface topography on fatigue behavior of Ti6Al4V alloy by laser powder bed fusion
摘要： This article deals with the understanding of the influence of surface topography on fatigue behavior of Ti6Al4V alloy specimens produced by laser powder bed fusion (LPBF). The same laser parameters and scan strategy were used for all specimens, giving a sample density higher than 99.5 %. Two different surface topographies were obtained by using the top and side surfaces of the specimens. The surface topography and morphology were investigated by optical surface profilometry and focus variation microscopy. Four-point bending fatigue test was performed on specimens with top and side surfaces as the highest stressed surface respectively. Machined specimens were used as reference. The features of the fracture surface, such as crack initiation and propagation, were analyzed by focus variation and scanning electron microscopy (SEM). Both, fatigue results and fracture surface investigations, were correlated and discussed in relation to surface topography and microstructure, as well as manufacturing parameters.
关键词： laser powder bed fusion,surface topography,Ti6Al4V alloy,fatigue test,fracture mechanisms
更新于2025-09-12 10:27:22
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Differences in Optic Nerve Head Blood Flow Regulation in Normal Tension Glaucoma Patients and Healthy Controls as Assessed With Laser Speckle Flowgraphy During the Water Drinking Test
摘要： Précis: Optic nerve head (ONH) perfusion was not signi?cantly altered in subjects with normal tension glaucoma (NTG) nor in healthy individuals after performing the water drinking test (WDT), because of its limited effect on ocular perfusion pressure (OPP). Purpose: ONH blood ?ow can be maintained stable in healthy individuals because of a physiological phenomenon called autoregulation. Impairment of autoregulation has been shown especially under condition of NTG. The purpose of this study was to investigate the ONH blood ?ow autoregulation in patients with NTG by in?uencing the OPP with the WDT. Methods: The study included 9 eyes from 9 white patients with a diagnosis of NTG and 9 eyes from age-matched and sex-matched healthy individuals. In the glaucoma group, the antiglaucomatous therapy was paused 3 weeks before the investigations. Measurements of ONH blood ?ow were performed with laser speckle ?owgraphy. After baseline measurements, individuals ingested 800 mL of water in <5 minutes. Measurements were repeated after 15, 30, and 45 minutes. Results: The water ingestion led to a signi?cant rise in intraocular pressure (P < 0.001) but also mean arterial pressure (P < 0.001) in both groups. This resulted in stable OPP (P = 0.051) with no signi?cant difference between the groups (P = 0.43). ONH blood ?ow remained stable over time in both groups (P = 0.719). No signi?cant interaction of time and group was shown for all parameters. Conclusions: Our ?ndings show that the WDT does not signi?cantly in?uence the OPP and therefore has to be considered inferior to other methods used to assess blood ?ow autoregulation.
关键词： laser speckle ?owgraphy,normal tension glaucoma,water drinking test,blood ?ow regulation
更新于2025-09-12 10:27:22
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[IEEE 2019 IEEE 16th International Conference on Smart Cities: Improving Quality of Life Using ICT & IoT and AI (HONET-ICT) - Charlotte, NC, USA (2019.10.6-2019.10.9)] 2019 IEEE 16th International Conference on Smart Cities: Improving Quality of Life Using ICT & IoT and AI (HONET-ICT) - Ramp Characteristics of Photovoltaic and Wind Power in South Korea
摘要： In this paper, in order to analyze the characteristics of photovoltaic and wind power ramps in South Korea, we analyzed a ramp using 1 hour power generation data to form the basis of backup installed capacity and reserve calculation. In order to find the distribution characteristics of ramps in each region, we first performed basic statistical analysis on ramps, and tested the normality of the ramps in the nine regions of South Korea. For non-normal distributions, we identified the appropriate distribution among 14 distributions based on p-values and statistical values of Anderson-Darling test and likelihood ratio test (LRT).
关键词： photovoltaic,wind,probability distribution,ramp,normality test
更新于2025-09-12 10:27:22
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A Novel Method for Digitalisation of Test Fields by Laser Scanning
摘要： In this article, a novel, media undisruptive method for the measurement of photogrammetric test fields using a laser tracker is presented. The new approach is precise and versatile in its application. It relies on image processing on the quasi continuous measurements of a hand-held laser scanner and laser tracker combination. The field of useful applications is large. In this article, we show the benefit in the field of camera calibration. Essential for highly accurate photogrammetric measurements is a careful calibration, since all cameras have optical distortions due to manufacturing processes of the lens. The calibration can be done by e.g. using a test field. In some cases, 3D coordinates of the control points are necessary. These coordinates are often determined by photogrammetry itself and tacheometric angle measurements in advance. A scale, e.g. a subtense bar, usually needs to be included which increases the measuring efforts. The method bases on the measured 3D point cloud of a test field. With this technique, not only the centers of all control points are accessible. Other geometric features can be chosen too. Since the point cloud consist of many single point measurements, every control point determination has already a high statistical redundancy. The 3D coordinates of every single control point are extracted from the point cloud, making an additional scale obsolete. Presently, the position accuracy is ≤ 50 μm (MPE), which is mainly limited by the laser scanner used in this article. The here-presented technique can be applied to all kinds of shapes, dimensions, materials, numbers and arrangements of control points. Furthermore, it is a lot faster and easier to handle than the angle measurements of the tacheometer.
关键词： Laser scanning,Photogrammetric calibration,Test field,Geometric calibration,3D point cloud
更新于2025-09-12 10:27:22
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Integrated microsensor for precise, real-time measurement of junction temperature of surface-mounted light-emitting diode
摘要： Light-emitting diodes (LEDs) are widely used in many industrial applications owing to their high performance and efficiency compared with conventional lighting systems. However, a considerable amount of input power is inevitably dissipated into heat at the LED junction, which can degrade the performance and reliability of the LED; thus, it is important to monitor the change in the junction temperature of the LED. In this study, we present a micro-temperature sensor-integrated surface-mounted device (SMD) for accurate and real-time measurement of the junction temperature of an LED. The LED is mounted on a microfabricated Pt sensor in a similar way to the typical SMD assembly. The heat generated at the LED junction is conductively transferred to the microsensor, increasing the temperature and changing its electrical resistance. In contrast to the conventional techniques for thermal characterization of LEDs, the integrated microsensor provides real-time information on the junction temperature with high precision, reproducibility, and simplicity. Additionally, the temperature of the solder, which is not easily accessible but is closely related to the reliability of the LED, can be estimated by analyzing the thermal resistance of the LED package. Experimental and numerical results indicate a linear correlation (R2 = 0.988) between the junction and sensor temperatures, which is practically useful for the thermal management of the miniaturized SMD-LED.
关键词： Junction temperature,Light-emitting diode,Thermal transient test,Microsensor,Surface-mounted device,Thermal management
更新于2025-09-12 10:27:22
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Experimental Investigation of the Shading and Mismatch Effects on the Performance of Bifacial Photovoltaic Modules
摘要： Bifacial photovoltaic (PV) modules are drawing increasing attention because of their potential in gaining extra energy from the rear-side irradiance. However, the rear-side irradiance can cause the performance of bifacial PV modules to be different from the performance of monofacial PV modules under shading and mismatch conditions. For bifacial modules, two factors can lead to the irradiance mismatch: the front-side partial shading and the rear-side irradiance inhomogeneity. This experimental work aimed to study the impact of these two factors on the performance of bifacial PV modules. The effect of front-side partial shading was investigated by comparing the electrical and thermal behavior of bifacial and monofacial PV modules under different shading conditions. The influence of rear-side irradiance inhomogeneity was investigated by analyzing the operating voltages of the solar cells in a bifacial PV module under certain typical installation conditions. To further explain the origin of the mismatch effect, a diode model circuit was applied in the analysis. The results indicate that even when the bypass diode of the bifacial PV module was activated, the shaded bifacial cells still received extra irradiance and produced higher heat. Thus, in most cases, the mismatch caused by the front-side partial shading may result in a greater reliability risk for the bifacial PV modules compared with the monofacial PV modules. For the mismatch effect of bifacial PV modules caused by the rear-side irradiance inhomogeneity, the significant reliability issues (such as reverse bias of solar cells and hotspot problems) would rarely happen, mainly because of the limited inhomogeneity of the equivalent irradiance and logarithmical increasing relationship between the voltage deviation and irradiance deviation of each solar cell.
关键词： shading effect,mismatch,thermal characteristic,Bifacial,outdoor test,photovoltaic (PV) module
更新于2025-09-12 10:27:22
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[IEEE 2019 IEEE 69th Electronic Components and Technology Conference (ECTC) - Las Vegas, NV, USA (2019.5.28-2019.5.31)] 2019 IEEE 69th Electronic Components and Technology Conference (ECTC) - 7nm Chip-Package Interaction Study on a Fine Pitch Flip Chip Package with Laser Assisted Bonding and Mass Reflow Technology
摘要： Due to the rapid growth in new technological features in mobile applications, new packaging solutions smaller form factor package designs, lower power consumption and other efficiency enhancements are required for the 7nm node silicon devices. Flip chip technology such as fcCSP (flip chip Chip Scale Package) has been widely adopted as the primary (or preferred) solution for mobile devices to satisfy these challenging requirements. The flip chip CSP package offers a cost-effective solution through the combination of Sn/Ag bumped copper (Cu) pillars, the use embedded trace substrate (ETS) technology along with mass reflow chip attach and molded underfill (MUF) processes.. While mass reflow chip attach process provides a cost-effective solution for flip chip assembly, there is nonetheless a high risk of bump to trace shorting especially as the need increases for finer bump pitch designs, with reduced copper line width and line spacing (LW/LS) for the escaped traces. To reduce this risk, we are exploring the use of laser assisted bonding (LAB) methodology to study the 7nm chip-package interaction (CPI) of a fcCSP with a 60μm bump pitch and escaped trace designs in this paper. For the purpose of measuring the extremely low-k (ELK) performance in a 14x14mm fine pitch fcCSP with 7nm node silicon live die, the thunder test, two-times mass reflow followed by a quick temperature cycling (QTC), and the hammer test, a multi-reflow process with a peak temperature of 260°C have been utilized. The results show that although both chip attach methodologies can pass the normal requirements of the thunder and hammer tests, the utilization of LAB technology can further enhance the strength of ELK, resulting in better yield performance. From these results, we believe that LAB not only can guarantee assembly yield but also ensure less ELK damage risk in the evaluated 7nm node silicon fcCSP. Futhermore we have shown that LAB technology is suitable for the 7nm node silicon devices along with the bump pitch reduction using finer LW/LS substrate with escaped traces design.
关键词： 7nm silicon node,chip-package interaction,laser assisted bonding,quick temperature cycling test,mass reflow,embedded trace substrate,hammer test
更新于2025-09-11 14:15:04