228,417 research outputs found
Towards Grower-friendly Apple Crop Thinning by Tree Shading
Light management with shading nets, which reduce sunlight by 74%, might be an
alternative to chemicals commonly used for thinning on apple trees. To study the effect of
shading on crop load and fruit quality, trials were conducted in field experiments with the
cultivars Golden Delicious and Elstar in 2006. Trees were either covered 25 days after full
bloom (DAFB) with a net during three days, or until the peak of fruit fall, observed after
seven days shading. Ideal time length for optimal crop yield was seven days shading for
Elstar and three days shading for Golden Delicious. Alternate bearing could be decreased
as flower initiation counts the following year showed. In both experiments, inner quality of
fruit such as sugar and firmness showed good values at optimal shading duration
compared with chemical + hand thinning. In 2007, a second field trial was conducted with
cultivars Golden Delicious and Topaz to study the time period for shading in further detail.
Shading was done for three days at 19, 26 and 33 DAFB using two net types (three- and
two-meter-net width, covering the trees entirely or only down to 50 cm above ground). For
Golden Delicious, shading after 19 and 26 days reduced fruits per 100 flower cluster to the
same extent as with chemical + hand thinning. There was no difference between the two
net types. For Topaz, shading after 19 days showed the best results. Regarding inner
quality of both cultivars, only sugar content for Golden Delicious could be significantly
improved after 19 and 26 days shading. Further analyses are still under way (e.g. for
acidity).
This study is part of an effort for increasing European consumption with fruit from
sustainable production systems, the ISAFRUIT-EU-project
The shading sign: is it exclusive of endometriomas?
To investigate if the shading sign is an exclusive MRI feature of endometriomas or endometrioid tumors, and to analyze its different patterns. Three hundred and fourty six women with adnexal masses who underwent 1.5/3-T MRI were included in this retrospective, board-approved study. The shading sign was found in 56 patients, but five cases were excluded due to lack of imaging follow-up or histological correlation. The final sample included 51 women. The type of tumor and the pattern of shading were recorded for each case. Thirty endometriomas and five endometrioid carcinomas were found. The remaining 16 cases corresponded to other benign and malignant tumors. The overall sensitivity, specificity, positive predictive value, and negative predictive value were 73%, 93%, 59%, and 96%, respectively. Restricting the analysis to cystic lesions without solid or fat component, sensitivity, specificity, positive predictive value, and negative predictive value were 73%, 96%, 94%, and 80%. Five shading patterns were identified: layering (15.7%), liquid-liquid level (11.8%), homogenous (45.1%), heterogeneous (11.8%), and focal/multifocal shading within a complex mass (19.6%). No significant correlation was found between these patterns and the type of tumor. The shading sign is not exclusive of endometriomas or endometrioid tumors. Homogenous shading was the most prevalent pattern in endometriomas and half of the cases with focal/multifocal shading within a complex mass were endometrioid carcinomas.info:eu-repo/semantics/publishedVersio
Design a photovoltaic system based on maximum power point tracking under partial shading
Photovoltaic systems have been given special attention given their long-term potential advantages. Solar panels can produce maximum power at specific operating points called maximum power points (MPP). Solar panels must work at this particular stage in order to ensure that solar panels produce maximum power and maximize efficiency. The performance of the solar photovoltaic unit is strongly affected by the level of radiation, heat and partial shading condition. The partial shedding condition is one of vectors that can affect the PV cell performance. To overcome on this problem, this project proposes photovoltaic system based on maximum power point tracking of partial shading condition. The MPPT algorithm has many methods like P&O and PSO. P&O it had limitation that is not capable to cover the multi-peaks curves. Beside that the PSO method is more effective in partial shading condition. The voltage and current of MSX60 PV module are subjected to various insolation conditions. The Particle Swarm Optimization (PSO) algorithm based MPPT has been implemented to track maximum power partial shading condition. So, in normal condition the power reach 245 W which is higher than the power under partial shading condition that reach 100 W. The PV module is designed using MATLAB/SIMULINK. The accurateness of this simulator is verified with PV module, the result is practiced during normal condition and under partial shading condition meanwhile, multiple curves of I-V and P-V will produce during normal condition and partial shading condition
A low cost shading analyzer and site evaluator design to determine solar power system installation area
Shading analyzer systems are necessary for selecting the most suitable installation site to sustain enough solar power. Afterwards, changes in solar data throughout the year must be evaluated along with the identification of obstructions surrounding the installation site in order to analyze shading effects on productivity of the solar power system. In this study, the shading analysis tools are introduced briefly, and a new and different device is developed and explained to analyze shading effect of the environmental obstruction on the site on which the solar power system will be established. Thus, exposure duration of the PV panels to the sunlight can be measured effectively. The device is explained with an application on the installation area selected as a pilot site, Denizli, in Turkey. © 2015 Selami Kesler et al
Impact of solar shading geometry on building energy use in hot humid climates with special reference to Malaysia
External solar shading devices can substantially reduce the cooling load of buildings and large energy savings can be achieved. Hence, intercepting the radiant heat wave before penetrating to the internal environment through envelope openings is the main criterion in designing solar shading. In hot and humid climate, one draw back of using shading devices is the risk to reduce daylight level thus increases in use of artificial lighting. Therefore it is important to understand the magnitude of energy consumption for cooling and lighting when shading devices are adapted in order to analyze optimum shading as energy conservation option in high-rise office buildings. In other words, little is known about the relationship between energy use and external horizontal shading device geometry. In an attempt to elucidate these complex relationships, a simple experiment of an office room is carried out using dynamic computer simulation program eQUEST- 3 (DOE 2.2). The study indicated depth of the external horizontal overhang can be manipulated to obtain an optimum energy use in high-rise buildings. The results showed that correlation between overhang depth and energy is an important aspect compared to correlation between overhang depth with building cooling loads and daylight level, especially in tropical climate conditions
3D simulation of complex shading affecting PV systems taking benefit from the power of graphics cards developed for the video game industry
Shading reduces the power output of a photovoltaic (PV) system. The design
engineering of PV systems requires modeling and evaluating shading losses. Some
PV systems are affected by complex shading scenes whose resulting PV energy
losses are very difficult to evaluate with current modeling tools. Several
specialized PV design and simulation software include the possibility to
evaluate shading losses. They generally possess a Graphical User Interface
(GUI) through which the user can draw a 3D shading scene, and then evaluate its
corresponding PV energy losses. The complexity of the objects that these tools
can handle is relatively limited. We have created a software solution, 3DPV,
which allows evaluating the energy losses induced by complex 3D scenes on PV
generators. The 3D objects can be imported from specialized 3D modeling
software or from a 3D object library. The shadows cast by this 3D scene on the
PV generator are then directly evaluated from the Graphics Processing Unit
(GPU). Thanks to the recent development of GPUs for the video game industry,
the shadows can be evaluated with a very high spatial resolution that reaches
well beyond the PV cell level, in very short calculation times. A PV simulation
model then translates the geometrical shading into PV energy output losses.
3DPV has been implemented using WebGL, which allows it to run directly from a
Web browser, without requiring any local installation from the user. This also
allows taken full benefits from the information already available from
Internet, such as the 3D object libraries. This contribution describes, step by
step, the method that allows 3DPV to evaluate the PV energy losses caused by
complex shading. We then illustrate the results of this methodology to several
application cases that are encountered in the world of PV systems design.Comment: 5 page, 9 figures, conference proceedings, 29th European Photovoltaic
Solar Energy Conference and Exhibition, Amsterdam, 201
Sun shield
A shading device which is capable of compactly storing a flexible shade on a biased, window shade type spring roller is disclosed. It is controlled to deliver the shade selectively to either its operative shading or compact storage orientation
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