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Shading, Dusting and Incorrect Positioning of Photovoltaic Modules as Important Factors in Performance Reduction
摘要： The amount of solar radiation reaching the front cover of a photovoltaic module is crucial for its performance. A number of factors must be taken into account at the design stage of the solar installation, which will ensure maximum utilization of the potential arising from the location. During the operation of a photovoltaic installation, it is necessary to limit the shading of the modules caused by both dust and shadowing by trees or other objects. The article presents an analysis of the impact of the radiation reaching the surface of the radiation module on the e?ciency obtained. Each of the analyzed aspects is important for obtaining the greatest amount of energy in speci?c geographical conditions. Modules contaminated by settling dust will be less e?cient than those without deposits. The results of experimental studies of this e?ect are presented, depending on the amount of impurities, including their origins and morphologies. In practice, it is impossible to completely eliminate shadowing caused by trees, uneven terrain, other buildings, chimneys, or satellite dishes, and so on, which limits the energy of solar radiation reaching the modules. An analysis of partial shading for the generated power was also carried out. An important way for maximizing the incoming radiation is the correct positioning of the modules relative to the sun. It is considered optimal to position the modules relative to the light source, that is, the sun, so that the rays fall perpendicular to the surfaces of the modules. Any deviation in the direction of the rays results in a loss in the form of a decrease in the available power of the module. The most bene?cial option would be to use sun-tracking systems, but they represent an additional investment cost, and their installations require additional space and maintenance. Therefore, the principle was adopted that stationary systems should be oriented to the south, using the optimal angle of inclination of the module surface appropriate for the location. This article presents the dependence of the decrease in obtained power on the angle of deviation from the optimal one.
关键词： energy losses,photovoltaic module,shading,maximum power generation,dusting,optimal orientation
更新于2025-09-23 15:21:01
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Optimal settings for the Holmium: YAG laser in pediatric endourology: tips and tricks
摘要： To the best of our knowledge, no pediatric paper has been published regarding specifically how to set the Holmium:YAG laser for multiple urologic applications. Objective: To provide insight into the laser parameters for pediatric applications Study design: We describe the principle and the settings of the laser Results: The Holmium:YAG laser can produce four different biological effects: (1) fragmentation of stones in small fragments that can be retrieved with grasping instruments, thereby increasing the immediate stone-free outcome. For fragmentation lithotripsy, the laser has to be set with a high energy, low frequency and short pulse duration; (2) dusting which produces fine dust that can spontaneously evacuate, avoiding the use of basket retrieval. The dusting setting requires low energy, high frequency and long pulse duration; (3) incision of posterior urethral valves or ureterocele when all settings are maximized: high energy, high frequency and long pulse duration; (4) coagulation of urothelial tumors using high frequency, long pulse duration and slightly lower energy than required for incision. Discussion: Both dusting by painting and fragmentation with retrieval for ureteroscopic laser lithotripsy are effective. Although dusting tends to be associated with shorter operative times and a lower risk of ureteral trauma, this approach has a potential risk of recurrent stone formation from dust failing to pass. In contrast, fragmentation with extraction may provide for a more immediate postoperative stone-free result. Altering the pulse energy, frequency, width and modulation can help to optimize lithotripsy efficiency. Lower pulse energy settings result in smaller fragments, less retropulsion and reduce fiber tip degradation. A shallow depth of penetration in water and tissue allows precise energy application and provides a margin of safety. Conclusion: An understanding of Ho-YAG laser settings will permit the pediatric surgeon to make a better use of the device for different urological applications.
关键词： children,dusting,fragmentation,section,laser Holmium-YAG
更新于2025-09-23 15:19:57
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Are we cutting ourselves short? Laser lithotripsy performance based on differences in fiber-tip preparation
摘要： Objectives: To better understand the impact of laser fiber-tip configuration on lithotripsy performance, we undertook an in vitro study comparing three fiber-tip configurations: 1) new (single-use), 2) cleaved (re-usable) and 3) coated (cut with scissors). Methods: Lithotripsy was performed using a Ho:YAG laser utilizing fragmentation (1Jx10Hz) and dusting (0.5Jx20Hz) settings. BegoStones were fragmented with a laser fiber advancing at a speed of 1 mm/s (220 seconds of activation). Three fiber-tip configurations were tested: new single-use standard (242 ?m core) and cleaved (272 ?m core), compared to the same fiber-tip coated/cut flush with scissors, respectively. Study outcome was difference in stone mass before and after each experiment. Power output was measured using a power meter. Results: Fragmentation for new or cleaved fibers was greater than the coated/cut flush fiber-tip (p<0.05). For 1Jx10Hz and 0.5Jx20Hz settings, fragmentation was 59% and 75% higher with new fiber-tip compared to the coated/cut flush fiber-tip, respectively. For 1Jx10Hz and 0.5Jx20Hz settings, fragmentation was 51% and 45% higher with cleaved fiber-tip compared to the coated/cut flush fiber-tip, respectively. Power output at the end of laser activation was higher for new and cleaved fiber-tips. Conclusion: New and cleaved laser fibers demonstrated superior lithotripsy performance compared to fibers that were coated/cut flush with scissors. Cutting single-use laser fibers risks damaging the fiber-tip which can disperse the energy and reduce lithotripsy efficiency.
关键词： Lithotripsy,Equipment,Holmium Laser,Dusting,Laser Fiber
更新于2025-09-16 10:30:52