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Academic literature on the topic 'Shading technique'

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Published: 26 July 2024
Last updated: 27 July 2024

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Journal articles on the topic "Shading technique"

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Hadiyani, Dhiyaa Julita. "PERBANDINGAN TEKNIK KOREKSI BENTUK WAJAH PERSEGI PADA RIAS WAJAH MALAM HARI." JURNAL PENDIDIKAN DAN KELUARGA 10, no. 2 (December 29, 2018): 186. http://dx.doi.org/10.24036/jpk/vol10-iss2/541.

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We compare two correction techniques namely deep shading and outer shading with only inner shading square face shape at night makeup. This research method uses quasi-experimental methods.The population in this study were women who had a square face shape with 3 people of samples. The results of the analysis show that there is no difference in the level of smoothness in the technique of using shading in the technique of using deep shading and outside shading (p=0,225). But the highest average value was found in the technique of using inner shading and outer shading (X2), which was equal to 3.33. There is a significant difference in the level of sharpness in the technique of using shading in the technique of using deep shading and outside shading (p=0,038). with the highest average value in the technique of using inner shading and outer shading (X2) which is equal to 3.07. There is a significant difference in the level of accuracy in the technique of using shading in with the technique of using shading inside and outside shading (p = 0.038) with the highest average value in the technique of using inner shading and outer shading (X2) which is equal to 3.27.
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Ge, Shibei, Yameng Wang, Keyin Shen, Qianying Wang, Golam Jalal Ahammed, Wenyan Han, Zhifeng Jin, Xin Li, and Yuanzhi Shi. "Effects of Differential Shading on Summer Tea Quality and Tea Garden Microenvironment." Plants 13, no. 2 (January 11, 2024): 202. http://dx.doi.org/10.3390/plants13020202.

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Shading is an effective agronomic technique to protect tea plants from intense sunlight. However, there are currently very few studies on more effective shading methods to improve the quality of summer tea. In this study, ‘Longjing43’ plants were grown under four different shading treatments for 14 days, with no shading as the control. Among the four shading treatments, double-layer-net shadings had the most positive impact on the tea quality, resulting in higher levels of amino acids but lower levels of tea polyphenols. Additionally, double-layer-net shadings provided more suitable microenvironments for tea plants. The tea leaves in T4 (double nets 50 cm above the plant canopy) contained 16.13 mg∙g−1 of umami and sweet amino acids, which was significantly higher than in other treatments. T4 had the lowest air temperature and the most suitable and stable soil water content. Interestingly, the ratio of red light to far-red light in T4 was only 1.65, much lower than other treatments, which warrants further study. In conclusion, the microenvironment induced by shading can greatly affect the tea quality, and double-layer-net shading is better for improving the quality of summer tea.
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Carbone, Rosario, and Cosimo Borrello. "Experimenting with a Battery-Based Mitigation Technique for Coping with Predictable Partial Shading." Energies 15, no. 11 (June 5, 2022): 4146. http://dx.doi.org/10.3390/en15114146.

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In this paper, the authors propose to use batteries to improve the performance of grid-connected photovoltaic plants when their photovoltaic fields are subject to partial shading phenomena. Particular attention is devoted to predictable and repetitive partial shadings, such as those that often appear in urban residential environments. Firstly, battery packs with proper nominal voltage and capacity are connected in parallel to partially shaded photovoltaic submodules. Then, the shaded photovoltaic submodules are properly disconnected and connected to the respective photovoltaic string by using a “battery control unit”, which is operated by taking into account characteristics of the specific partial shading phenomenon to cope with. To demonstrate the effectiveness of the proposed technique, an experimental study is performed to compare the performances of two identical prototypal grid-connected photovoltaic generators subject to identical artificial and repetitive partial shadings. Only one of the photovoltaic generators is equipped with batteries together with their respective battery control unit, while the second one is simply equipped with conventional bypass diodes. The main advantages of the proposed technique are a greatly improved whole power generation together with the elimination of hotspot phenomena.
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Mahmod Mohammad, Altwallbah Neda, Mohd Amran Mohd Radzi, Norhafiz Azis, Suhaidi Shafie, and Muhammad Ammirrul Atiqi Mohd Zainuri. "An Enhanced Adaptive Perturb and Observe Technique for Efficient Maximum Power Point Tracking Under Partial Shading Conditions." Applied Sciences 10, no. 11 (June 5, 2020): 3912. http://dx.doi.org/10.3390/app10113912.

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In this paper, we propose enhanced adaptive step size Perturb and Observe (P&O) maximum power point tracking (MPPT) with properly organized comparison sequences which lead to achieving the actual maximum power point (MPP) effectively in the presence of partial shading conditions, taking into account the optimization of all aspects of high-performance MPPT to be novel, simpler, fast, and accurate, with the best efficiency reaching up to almost 100%. In this study, the proposed algorithm, along with a boost converter, was designed and simulated in MATLAB/Simulink to validate the performance of the suggested technique. Four different levels of partial shading conditions were considered for system examination: weak, moderate, and two different levels of strong shading. Each case was applied separately first and then combined in a sequence arrangement to provide robust and comprehensive testing which can provide a guaranteed assessment of the proposed algorithm. The performance of the suggested technique is discussed and compared with that of conventional P&O and conventional incremental conductance (IC) MPPT techniques. The failure of the conventional techniques to work efficiently in the presence of partial shading conditions was observed from the simulation results. Meanwhile, the success of the proposed technique and its high performance were clearly confirmed under partial shading conditions with no increase in complexity or convergence time.
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Akki, Gangadhar Mahalingappa, and Srivani S G. "Maximum Power Point Tracking using modified Particle Swarm Optimization Technique." International Journal for Research in Applied Science and Engineering Technology 10, no. 5 (May 31, 2022): 2759–70. http://dx.doi.org/10.22214/ijraset.2022.42951.

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Abstract: Maximum power point tracking is an essential and vital technique generally applied in SPV technology under uniform and partial shading conditions. The existence of partially shaded conditions leads to the presence of several peaks on PV curves, which decrease the efficiency of conventional techniques. Hence, the proposed algorithm, which is based on the modified particle-swarm optimization (MPSO) technique, increases the output power of PV systems under such abnormal conditions and has a better performance compared to other methods. The proposed method is examined under several scenarios for partial shading condition and non-uniform irradiation levels using Matlab and to investigate its effectiveness adequately. The experimental results show that the proposed method can decrease the interference of the local maximum power-point to cause the PV system to operate at a global maximum power-point. The efficiency of the MPSO is achieved with the least number of steady-state oscillations under partial shading conditions as compared with the other methods. Keywords: Photovoltaic(PV), Particle Swarm Optimization(PSO), Modified Particle Swarm Optimization(MPSO), Partial shading condition(PSC), Velocity step function.
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Al-Kaoaz, Hiba Nadhim Ameen, and Omar Sharaf Al-deen Yehya Al-Yozbaky. "Influence of natural clouds on the performance of solar cell systems in Iraq." Bulletin of Electrical Engineering and Informatics 12, no. 4 (August 1, 2023): 1867–80. http://dx.doi.org/10.11591/beei.v12i4.4703.

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Solar energy generated by photovoltaic (PV) technology can be supplied to standalone systems, as it combines efficiency and cost-effectiveness. However, this combination is achieved only after considering the effects of shading, which can significantly influence electrical output. The primary factor that influences the use of solar energy in electricity generation is irradiation. PV cells are significantly impacted by shading, where the output of the PV cell reduces in the presence of a shadow. In this study, the researchers have presented an experimental analysis of how shading affects two PV cells, using the series and parallel configurations. The experimental work is installed at the University of Mosul, Department of Electrical Engineering, Renewable Lab (Iraq). MATLAB was used to simulate, evaluate, and compared the results to understand the effects of shading on PV cell output. This research offers an analytical technique to determine the probable effects of Partial shadowing conditions on PV power generation. The results provide the effects of partial shadowing in an annual performance loss of ≥10–30%. The orientation of the PV panels' tilt angle has an impact on their output power. When the tilt angle deviates from its ideal value, the PV panel's output drops off substantially.
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Al-Kaoaz, Hiba Nadhim Ameen, and Omar Sharaf Al-deen Yehya Al-Yozbaky. "Influence of natural clouds on the performance of solar cell systems in Iraq." Bulletin of Electrical Engineering and Informatics 12, no. 4 (August 1, 2023): 1867–80. http://dx.doi.org/10.11591/eei.v12i4.4703.

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Solar energy generated by photovoltaic (PV) technology can be supplied to standalone systems, as it combines efficiency and cost-effectiveness. However, this combination is achieved only after considering the effects of shading, which can significantly influence electrical output. The primary factor that influences the use of solar energy in electricity generation is irradiation. PV cells are significantly impacted by shading, where the output of the PV cell reduces in the presence of a shadow. In this study, the researchers have presented an experimental analysis of how shading affects two PV cells, using the series and parallel configurations. The experimental work is installed at the University of Mosul, Department of Electrical Engineering, Renewable Lab (Iraq). MATLAB was used to simulate, evaluate, and compared the results to understand the effects of shading on PV cell output. This research offers an analytical technique to determine the probable effects of Partial shadowing conditions on PV power generation. The results provide the effects of partial shadowing in an annual performance loss of ≥10–30%. The orientation of the PV panels' tilt angle has an impact on their output power. When the tilt angle deviates from its ideal value, the PV panel's output drops off substantially.
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Ulfah, Taqiyyah, and Dwi Budiwiwaramulja. "ANALISIS KARYA GAMBAR ILUSTRASI TEKNIK ARSIR SISWA KELAS VIII DI SMP SWASTA TUNAS KARYA BATANG KUIS." Gorga : Jurnal Seni Rupa 8, no. 1 (July 2, 2019): 279. http://dx.doi.org/10.24114/gr.v8i1.13642.

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AbstrakPenelitian ini bertujuan untuk mengetahui kemampuan menggambar ilustrasi teknik arsir yang digunakan untuk mendapatkan hasil karya gambar ilustrasi teknik arsir berdasarkan aspek penilaian ilustrasi yaitu penempatan, konsep, karakter, dan konsistensi menurut prinsip penilaian ilustrasi oleh Andrew Loomis. Waktu penelitian berlangsung selama 2 bulan, yang dilaksanakan dari bulan Oktober hingga Desember. Lokasi penelitian adalah jalan Batang Kuis Desa Tanjung Sari Kecamatan Batang Kuis. Penelitian ini menggunakan metode deskriptif kualitatif dengan menguraikan masing-masing subjek yang diteliti. Pada penelitian ini, peneliti menggunakan purposive sampling dengan sample 29 karya siswa. Hasil penelitian menjelaskan bahwa nilai rata-rata karya siswa secara keseluruhan dikaregorikan baik dengan rata-rata nilai 79,8 (baik). Hasil karya gambar ilustrasi dikategorikan baik yaitu 27 karya dengan nilai rata-rata 80,8. Hasil karya gambar ilustrasi teknik arsir dikategorikan cukup baik yaitu 1 karya dengan nilai 66,3. Hasil karya gambar ilustrasi tenik arsir dikategorikan kurang baik yaitu 1 karya dengan nilai 64,9. Maka dari 29 karya gambar ilustrasi teknik arsir yang mencapai nilai KKM sebanyak 28 karya dari karya gambar Ilustrasi Teknik Arsir yang dibuat oleh siswa kelas VIII SMP Swasta Tunas Karya Batang Kuis.Kata Kunci: analisis, gambar, ilustrasi, teknik, arsir.AbstractThe Study aims to determine the ability to illustrate shading techniques that are used to obtain the illustrations of shading techniques based on the assessment aspects of the technique, namely placement, concept, character, and consistency according to the illustration by Andrew Loomis. The time of the study lasted for two months, wich was held from October to Desember. The location of the research is at Batang Kuis St. Tanjung Sari village Batang Kuis sub-dictrict. This study uses a qualitative descriptive method by describing the subject studied. In this study,the researcher used purposive sampling with a sample of 29 student works. The result of the study explain that the average value of students as a whole can be categorized as good with an average calue of 79,8 (good). Illustration works are categorized as good, namely 27 works with an average value of 80,8. The drawing artwork of the shading technique is categorized quite well, namely 1 work with a value of 66,3. The results of the experimental work of the shading technique are categorized as poor, namely 1 work with a value 64,9. Then of the 29 images of shading drawing technique wich reached KKM values as many as 28 students’ work from the work of the drawing technique of the shading technique made by students of class VIII Private Junior High School Tunas Karya Batang Kuis. Keywords: analysis, images, illustration, technique, shading.
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Subhi, Mohammed Osamah, and Wafaa Saeed Majeed. "PERFORMANCE OF SCREW HORIZONTAL AND BRIDGE LINKAGE PHOTOVOLTAIC ARRAY CONFIGURATIONS." Journal of Engineering and Sustainable Development 28, no. 02 (March 1, 2024): 268–84. http://dx.doi.org/10.31272/jeasd.28.2.9.

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Due to partial shading effects on the productivity of solar panels which in turn negatively impacts the performance characteristics of photovoltaic systems, researchers work on different studies to overcome this phenomenon and improve solar system productivity. Therefore, this study aims to investigate different techniques to enhance the output power, fill factor, and efficiency of the PV system by reducing the number of local maximum power peaks, power losses, and mismatch losses. The configurations include a novel static reconfiguration technique, called a Screw Horizontal photovoltaic array, and a recently developed technique known as a Bridge Linkage array. Both of these are modeled using MATLAB/Simulink software and examined during six shading patterns. The novelty of this study is that we combined the above static reconfiguration technique with another modern technique called blocking and bypass diode technology to prevent the effect of reverse current and hotspot phenomena respectively. According to the results, the Bridge Linkage configuration performs the most efficiently under partial shading conditions compared to the Screw horizontal PV array configuration.
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Masry, Mohamed Zaghloul-El, Abdallah Mohammed, Fathy Amer, and Roaa Mubarak. "New Hybrid MPPT Technique Including Artificial Intelligence and Traditional Techniques for Extracting the Global Maximum Power from Partially Shaded PV Systems." Sustainability 15, no. 14 (July 11, 2023): 10884. http://dx.doi.org/10.3390/su151410884.

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This research aimed to increase the power captured from photovoltaic (PV) systems by continuously adjusting the PV systems to work at the maximum power point under climate changes such as solar irradiance change and temperature change and by tracking the global maximum power under partial shading conditions (PSCs). Under the effect of partial shading (PS), the PV curve has many local maximum peaks (LMPs) and one global maximum peak (GMP) which is dynamic because it changes with time when the shading pattern (SP) changes. The traditional maximum power point tracking (MPPT) methods are unable to track the Dynamic GMP and may fall into one of the LMPs. Many modern MPPT methods have been introduced that can track the Dynamic GMP, but their effectiveness can be improved. In this respect, this work introduces a new optimal MPPT technique to enhance the performance of the maximum power point tracking of solar cells under environmental changes and partial shading conditions. The proposed technique combines three well-known and important MPPT techniques, which are the Artificial Neural Network (ANN), Variable Step Perturb and Observe (VSP&O), and Fuzzy Logic Controller (FLC). Artificial Neural Network gives a voltage near the optimum voltage, Variable Step Perturb and Observe updates the voltage to get close to the optimum voltage, and Fuzzy Logic Controller updates the step size of the (P&O) technique. The proposed hybrid ANN-VSP&O-FLC technique showed its ability to track the Dynamic GMP accurately and quickly under the variation in the shading patterns with time and its ability to follow maximum power efficiently and quickly under climate changes. The proposed hybrid ANN-VSP&O-FLC technique also showed very low distortions in waveforms and very low oscillations around the steady state. The proposed hybrid ANN-VSP&O-FLC technique was compared to the most recent and effective MPPT techniques in terms of steady-state behavior, tracking speed, tracking efficiency, and distortions in waveforms, and the comparison showed that it is superior to them, with lower distortions in waveforms, a faster tracking speed (less than 0.1 s), higher tracking efficiency (greater than 99.65%), and lower oscillations around the steady state (less than 2 Watts).
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Dissertations / Theses on the topic "Shading technique"

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Mayol, Cotapos Carolina de los Ángeles. "Mitigation control against partial shading effects in large-scale photovoltaic power plants using an improved forecasting technique." Tesis, Universidad de Chile, 2017. http://repositorio.uchile.cl/handle/2250/144113.

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Magíster en Ciencias de la Ingeniería, Mención Eléctrica
En un trabajo previo se propuso un control de mitigación de efecto nube que permitía disminuir los efectos nocivos de la nubosidad parcial sobre parques fotovoltaicos en la frecuencia de sistemas eléctricos de potencia. Esto último sin la necesidad del uso de acumuladores de energía. La estrategia se basa en la operación sub-óptima de los parques (operación en deload) con tal de disponer de reservas de potencia. A pesar que la implementación del sistema nombrado mejoró la frecuencia del sistema de forma significativa en comparación al caso base (sin el sistema de control), la operación en deload de los parques implica una gran cantidad de energía que no se está aprovechando, lo que no se consideró en la metodología. Con tal de mejorar esto, el siguiente trabajo propone un control de mitigación de efecto nube en parques fotovoltaicos de gran escala basado en una herramienta de pronóstico de radiación. Esto último permite disminuir las pérdidas de energía junto con mitigar los efectos de la nubosidad parcial, mediante la determinación de un nivel de deload en los parques fotovoltaicos usando dicho pronóstico. En primer lugar, esta tesis presenta una revisión bibliográfica y discusión del estado del arte de las técnicas de pronóstico en parques fotovoltaicos. Se muestra que la selección de la técnica de pronóstico depende en la información disponible y la ventana de tiempo del pronóstico, es decir, dependerá del caso de estudio. Dicho esto, se propone el uso de una técnica de pronóstico basada en redes neuronales en el Sistema Interconectado del Norte Grande (SING) de Chile. El pronóstico sirve para determinar el nivel de deload en el parque fotovoltaico para los siguientes 10 minutos, en función de una rampa de radiación. Los resultados muestran que la implementación de la técnica de pronóstico no solo mejora la respuesta en frecuencia del sistema, sino que también disminuye las pérdidas energéticas de forma significativa.
Este trabajo fue parcialmente financiado por el Proyecto CONICYT/FONDAP/15110019 "Solar Energy Research Center" SERC-Chile y el Instituto de Sistemas Complejos de Ingeniería (ISCI)
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Milnthorpe, Graham E. "Computer generation of integral images using interpolative shading techniques." Thesis, De Montfort University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.422599.

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Pope, Glenn William. "Application of shape-from-shading to synthetic aperture radar." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/29755.

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This thesis investigates the viability of applying a shape-from-shading technique to SAR imagery. A shape-from-shading algorithm is derived and tested on a single site for which both a Seasat SAR image and Digitial Elevation Model (DEM) were available. The shape-from-shading technique used in this thesis follows an approach proposed by Frankot and Chellappa for processing slant range SAR imagery. The algorithm incorporates a one-step technique for projecting non-integrable surface orientation estimates onto an integrable set in the frequency domain along with the iterative convergent shape-from-shading algorithm of Brooks and Horn. The significant issues and choices made in implementing the shape-from-shading algorithm and in preparing the SAR data and DEM are discussed. The shape-from-shading algorithm was applied to both the test site SAR image and images synthesized from the DEM. Reflectance models were derived from the SAR image and DEM. By quantitatively comparing the shape-from-shading results with the initial conditions used for the experiments, it was found that the algorithm produced substantially better results when applied to the synthesized images; however, when applied to the SAR image, there was no significant improvement over the initial conditions.
Science, Faculty of
Computer Science, Department of
Graduate
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Panchetti, Minica. "Exploitation d'images numériques pour la simplification et la déformation de modèles polyédriques." Phd thesis, Paris, ENSAM, 2009. http://pastel.archives-ouvertes.fr/pastel-00005131.

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Les modèles polyédriques, très utilisés dans les processus d'ingénierie, constituent une représentation privilégiée au sein des maquettes numériques de produits. Les approches et méthodes de manipulation et d'exploitation de ces modèles, sont le plus souvent pilotées par un critère géométrique lié à la forme des objets (normale, courbure ...) mais très peu prennent en compte des informations de type perceptuelles. Parallèlement, les techniques de traitement d'images existantes extraient des données (contours, primitives géométriques, textures ...) relatives à la description des formes des objets qu'elles représentent. Ainsi, le but de cette thèse est de réaliser un couplage modèle polyédrique 3D / images numériques 2D pour manipuler les modèles 3D avec des critères extraits d'image(s). Une méthode de simplification et deux méthodes de déformation de polyèdres sont présentées. Dans la première méthode, la simplification est basée sur un processus itératif de suppression de sommets piloté par un critère de tolérance de simplification. Cette tolérance est liée au filtrage de contours d'image(s) qui sont projetés sur le modèle 3D afin d'identifier les zones plus ou moins proches de ces lignes de caractère. Les méthodes de déformation de polyèdres sont appliquées au cas du remplissage de trous. Une triangulation est insérée au modèle puis déformée par la résolution d'un problème d'optimisation numérique sous contraintes. La fonctionnelle à minimiser simule la variation de courbure entre le maillage inséré et le modèle initial. La solution est obtenue par un algorithme itératif basé sur un modèle mécanique de réseau de barres. Les contraintes imposent le respect de lignes de caractère 3D obtenues par triangulation stéréoscopique dans la première méthode, ou bien calculées en fonction de l'intensité lumineuse des pixels et qui imposent le déplacement des sommets correspondants suivant une certaine élévation (problème inverse du Shape From Shading). Les trois méthodes implémentées sont complètement modulaires.
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Zubiaga, Pena Carlos Jorge. "Real-time 2D manipulation of plausible 3D appearance using shading and geometry buffers." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0178/document.

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Les artistes traditionnels peignent directement sur une toile et créent des apparences plausibles de scènes qui ressemblent au monde réel. A l’opposé, les artistes en informatique graphique définissent des objets dans une scène virtuelle (maillages 3D, matériaux et sources de lumière), et utilisent des algorithmes complexes (rendu) pour reproduire leur apparence. D’un côté, les techniques de peinture permettent de librement définir l’apparence. D’un autre côté, les techniques de rendu permettent de modifier séparément et dynamiquement les différents éléments qui définissent l’apparence. Dans cette thèse, nous présentons une approche intermédiaire pour manipuler l’apparence, qui permettent certaines manipulations en 3D en travaillant dans l’espace 2D. Mous étudions d’abord l’impact sur l’ombrage des matériaux, tenant en compte des matériaux comme des filtres passe-bande d’éclairage. Nous présentons ensuite un petit ensemble de relations statistiques locales entre les matériaux / l’éclairage et l’ombrage. Ces relations sont utilisées pour imiter les modifications sur le matériaux ou l’éclairage d’une image d’une sphère créée par un artiste. Les techniques connues sons le nom de LitSpheres / MatCaps utilisent ce genre d’images pour transférer leur apparence `a des objets de forme quelconque. Notre technique prouve la possibilité d’imiter les modifications 3D de la lumière et de matériaux à partir d’une image en 2D. Nous présentons une technique différente pour modifier le troisième élément impliqué dans l’aspect visuel d’un objet, sa géométrie. Dans ce cas, on utilise des rendus comme images d’entrée avec des images auxiliaires qui contiennent des informations 3D de la scène. Nous récupérons un ombrage indépendant de la géométrie pour chaque surface, ce qui nous demande de supposer qu’il n’y a pas de variations spatiales d’éclairage pour chaque surface. L’ombrage récupéré peut être utilisé pour modifier arbitrairement la forme locale de l’objet de manière interactive sans la nécessité de rendre `a nouveau la scène
Traditional artists paint directly on a canvas and create plausible appearances of real-world scenes. In contrast, Computer Graphics artists define objects on a virtual scene (3D meshes, materials and light sources), and use complex algorithms (rendering) to reproduce their appearance. On the one hand, painting techniques permit to freely define appearance. On the other hand, rendering techniques permit to modify separately and dynamically the different elements that compose the scene. In this thesis we present a middle-ground approach to manipulate appearance. We offer 3D-like manipulation abilities while working on the 2D space. We first study the impact on shading of materials as band-pass filters of lighting. We present a small set of local statistical relationships between material/lighting and shading. These relationships are used to mimic modifications on material or lighting from an artist-created image of a sphere. Techniques known as LitSpheres/MatCaps use these kinds of images to transfer their appearance to arbitrary-shaped objects. Our technique proves the possibility to mimic 3D-like modifications of light and material from an input artwork in 2D. We present a different technique to modify the third element involved on the visual appearance of an object: its geometry. In this case we use as input rendered images alongside with 3D information of the scene output in so-called auxiliary buffers. We are able to recover geometry-independent shading for each object surface, assuming no spatial variations for each recovered surface. The recovered shading can be used to modify arbitrarily the local shape of the object interactively without the need to re-render the scene
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Greenwood, Shannon Thomas. "The incorporation of bubbles into a computer graphics fluid simulation." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969.1/2267.

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We present methods for incorporating bubbles into a photorealistc fluid simulation. Previous methods of fluid simulation in computer graphics do not include bubbles. Our system automatically creates bubbles, which are simulated on top of the fluid simulation. These bubbles are approximated by spheres and are rendered with the fluid to appear as one continuous surface. This enhances the overall realism of the appearance of a splashing fluid for computer graphics. Our methods leverage the particle level set representation of the fluid surface. We create bubbles from escaped marker particles from the outside to the inside. These marker particles might represent air that has been trapped within the fluid surface. Further, we detect when air is trapped in the fluid and create bubbles within this space. This gives the impression that the air pocket has become bubbles and is an inexpensive way to simulate the air trapped in air pockets. The results of the simulation are rendered with a raytracer that includes caustics. This allows the creation of photorealistic images. These images support our position that the simple addition of bubbles included in a fluid simulation creates results that are much more true to life.
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Courteille, Frédéric. "Vision monoculaire : contributions théoriques et application à la numérisation des documents." Toulouse 3, 2006. http://www.theses.fr/2006TOU30202.

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Un des problèmes classiques en vision par ordinateur est la reconstruction tridimensionnelle d'une scène à partir d'une seule image. Dans cette thèse, nous nous intéressons à ce problème par le biais de deux méthodes de reconstruction, à savoir le shape from shading et le shape from contour qui utilisent, respectivement, l'information photométrique et une partie de l'information géométrique contenues dans l'image. Dans un premier temps, nous remettons en question certaines des hypothèses nécessaires à ces deux méthodes, afin d'en obtenir des modélisations réalistes. Ceci nous permet, dans un deuxième temps, de généraliser les méthodes de résolution existantes et d'en proposer de nouvelles. Ces contributions théoriques nous amènent à nous intéresser, en guise d'application, à la numérisation des documents. Si le procédé classique, qui utilise un scanner à plat, est satisfaisant pour les situations courantes, il présente deux faiblesses: d'une part, lorsqu'il s'agit d'un livre, la manipulation répétitive consistant à tourner une page puis à plaquer le livre contre la vitre du scanner est relativement fastidieuse; d'autre part, l'image numérisée comporte des défauts (caractères flous ou déformés, effets de parallaxe, papier non encré de couleur non uniforme) si le document est «bombé», comme c'est le cas pour un livre épais. Pour pallier ces deux faiblesses, nous proposons de remplacer le scanner par un appareil photographique numérique, puis de corriger les défauts de la photographie en utilisant l'information tridimensionnelle de la scène. Nous obtenons des résultats très satisfaisants sur images réelles
A classical problem in computer vision is the 3D-reconstruction of a scene from a single image. In this thesis, we consider two 3D-reconstruction methods, namely shape from shading and shape from contour, which use, respectively, the photometric information and a part of the geometric information contained in the image. First, in order to obtain realistic modelings, we put some of the hypotheses necessary to both these methods into question. Second, this allows us to generalize the existing methods of resolution and to design new ones. These theoretical contributions lead us to take an interest in a specific application, namely document digitization. If the traditional process, which uses a flatbed scanner, produces satisfactory results for the current situations, it presents two weaknesses: on the one hand, when dealing with a book, the repetitive handling which consists in turning one page, and then forcing the book sticking to the scanner pane, is rather tedious; in addition, for a curved document, as for example a thick book, some defects will appear in the digital image (blurred or deformed characters, effects of parallax, noninked paper having a non-uniform color). To overcome these two weaknesses, we propose to replace the flatbed scanner by a digital camera, and then to correct the defects of the photograph by using the 3D-shape of the scene. We obtain very satisfactory results on real images
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8

Conceição, Sérgio Gil Pinheiro da. "Cel shading : história e aplicação do efeito 2D em animação digital." Master's thesis, 2013. http://hdl.handle.net/10400.14/16680.

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A presente dissertação tem como principais objetivos a compreensão e a análise da técnica visual Cel shading, quer na indústria digital de animação, quer na de videojogos. Cel shading é uma técnica visual de animação, que permite emular ilustrações, ou desenhos, em gráficos 3D, que devidamente animados, formam vários constituintes das indústrias de animação e de videojogos. Ao longo desta dissertação é realizada uma contextualização histórica da animação, analisando diversas técnicas e processos que levaram à sua evolução, desde o celuloide até à era digital. Aqui é dando especial ênfase a determinados filmes revolucionários de cada época, fundamentais para a evolução das técnicas de animação utilizadas desde então. Além dos filmes e séries televisivas, é também realizada uma síntese dos videojogos mais relevantes, que usam, ou usaram, esta técnica visual, pois permite emular o estilo visual de banda desenhada. Os exemplos mais marcantes de cada tipo são: (i) em séries televisivas: “The Simpsons” (1989 – presente), “Futurama” (1999 – 2003) e “Family Guy” (1999 – presente); (ii) em filmes de animação: “Animatrix” (2003), “Ghost in the Shell” (1989) e “The Iron Giant” (1999); (iii) e em videojogos: “Jet Set Radio”, “XIII”, “The Legend Of Zelda: Phantom Hourglass”, ”The Legend of Zelda: The Wind Waker”. Simultaneamente ao desenvolvimento da presente dissertação foi produzida uma curta-metragem de animação para a empresa de telecomunicações Optimus. Esta pretende descrever, através de metáforas e estilos visuais apelativos, a viagem de uma mensagem de texto e todos os processos inerentes ao seu envio e receção. Ao se optar por realizar esta curta-metragem, foram analisados vários estilos visuais muito próprios. De todos os estilos analisados, o escolhido para a curta-metragem realizada foi o Cel shading. A interação com um cliente real exige a constante transformação, segundo as suas decisões. Uma das modificações aplicadas a esta dissertação foi o estilo visual escolhido. Invés da técnica visual Cel shading, o estilo visual adotado para a curta-metragem de animação produzido foi um estilo mais realista, baseado em imagens de High-dynamic-range imaging (HDRi).
The present dissertation has as main objective the understanding and analysis of the visual technique Cel shading, either on the digital animation industry, or in the video games industry. Cel shading is a visual animation technique that can emulate illustrations, or drawings, in 3D graphics. Those illustrations, when fully animated, can form various elements of the animation industries and video games. Throughout this dissertation is held a historical context of animation, analysing different techniques and processes that led to its evolution, since the celluloid to the digital era, with emphasis on certain revolutionary films of each era, fundamental for the evolution of the techniques used since. Apart from films and television series, is also carried out a synthesis of the most important videogames that use, or have used, this visual technique, because it allows emulating the visual style of comics. The most remarkable examples of each type are: (i) in television series "The Simpsons" (1989 – present), "Futurama" (from 1999 to 2003) and "Family Guy" (1999 – present); (ii) in animation films "Animatrix" (2003), "Ghost in the Shell" (1989) and "The Iron Giant" (1999); (iii) and in videogames, "Jet Set Radio", "XIII", "The Legend Of Zelda: Phantom Hourglass" and "The Legend of Zelda: The Wind Waker". Simultaneously with the development of this dissertation, it was produced a short animated film for the Portuguese telecommunications company Optimus. This animation intended to describe, through metaphors and appealing visual styles, the journey of a short text message (SMS); and all the processes inherent on its sending and receiving. For the production of this short film, the authors analysed several visual styles. Of all the styles analysed, the chosen for the short film was the technique Cel shading. The interaction with a real client requires a constant change, based on its decisions. One of those modifications applied to this thesis was the visual style chosen. Instead of the visual technique Cel shading, the adopted visual style for the short animated film produced was a more realistic, based in images from High-dynamic-range imaging (HDRi).
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Wang, Jun-Ren, and 王俊仁. "A Two-Stage Maximum Power Point Tracking Technique for Photovoltaic Generation Systems Considering Partial Shading." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/3e9kjv.

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碩士
國立臺灣科技大學
電機工程系
107
Photovoltaic generation systems (PGSs) frequently experience partial shading conditions (PSCs). Because PSCs will result in multiple peak values on the power-to-voltage characteristic curve, developing an algorithm that facilitates tracking global maximum power point (GMPP) is crucial. Therefore, a two-stage GMPP tracking algorithm is proposed in this thesis. In the first stage, the vicinity of the maximum power point is obtained by performing extensive simulations, while during the second stage, alpha factor perturb and observe (P&O) method is utilized to improve the tracking accuracy and stably control the operating point at the maximum power point. To verify the correctness and feasibility of the proposed MPPT algorithm, a 600 W prototyping circuit is constructed. The simulation results compared with the deterministic cuckoo search (CS) method under partial shading conditions show that the rising time is shortened by 34.67%, the settling time is improved by 25.18%, the average tracking power loss is reduced by 35.68%, and the 99.99% steady-state tracking accuracy can be achieved. Experimental results also validate that the proposed method can obtain GMPP under different shading patterns, and above 99.00% steady-state tracking accuracy has been reached on the specific five PSC test cases.
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WU, CHIA-CHUN, and 伍家俊. "A Study on Shading Effect of Solar Cell and Electroluminescent Technique for Solar Cell Inspection." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/vghh44.

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碩士
國立勤益科技大學
電子工程系
106
The solar electrical power is more useful and important issue for green requirements today. In this study, we investigate the shaded effects for various kinds of solar modules. In addition, there are various types of solar cell defects in fabrication. Various defects of solar cell might lower the photoelectron transformation efficiency. Among these defects, micro cracks occurring in the interior of solar wafers are most crucial. In normal lighting intensity, micro cracks of solar cell is difficult to detect or visible. Currently, the most common method to detect invisible micro crack in solar cell is used by electroluminescence (EL) technique. In this study, based on crystalline silicon solar cells we investigate electro characteristics such as open voltage (Voc) and short-circuit current (Isc) after EL test of cell. In addition, we also develop an EL image inspection system for roughly evaluation in normal area of the solar cell under test. However, this is an experimental prototyping system, the accuracy of micro cracks detection for solar cell is still depended on the quality of EL image and test instruments settings.
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Books on the topic "Shading technique"

1

Roig, Gabriel Martín i. Line and shading in drawing. Hauppauge, NY: Barron's Educational Series, 2005.

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Edwards, Ginger. The ultimate highlighting & shading guide. Norcross, GA: Plaid Enterprises, 2004.

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Ken, Butcher, Chartered Institution of Building Services Engineers, and Great Britain. Department of Trade and Industry, eds. Design for improved solar shading control. London: CIBSE, 2006.

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Marc, Olano, ed. Real-time shading. Natick, Mass: AK Peters, 2002.

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Czarniawska-Joerges, Barbara. Shadowing: And other techniques for doing fieldwork in modern societies. Malmö, Sweden: Liber, 2007.

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Sparkes, W. E. Lessons on Shading. Dover Publications, Incorporated, 2012.

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Sparkes, W. E. Lessons on Shading. Dover Publications, 2007.

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Sparkes, W. E. Lessons on Shading. Dover Publications, Incorporated, 2012.

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Line and shading in drawing. Hauppauge, NY: Barron's Educational Series, 2005.

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Loomis, Andrew. Successful Drawing. Titan Books, 2012.

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Book chapters on the topic "Shading technique"

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Ulich, Gabriele. "A new variational technique for Shape from Shading." In ICAOS '96, 253–59. Berlin, Heidelberg: Springer Berlin Heidelberg, 1996. http://dx.doi.org/10.1007/3-540-76076-8_138.

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Sai, Boni Satya Varun, Sarang A. Khadtare, and Debashis Chatterjee. "A Sensor-Based Improved MPPT Technique Under Partial Shading Condition." In Lecture Notes in Mechanical Engineering, 635–44. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-3497-0_51.

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Jagadeesh, K., Ch Chengaiah, and Surender Reddy Salkuti. "A Novel FSD Reconfiguration Technique for Dynamic Shading in Photovoltaic Systems." In Energy and Environmental Aspects of Emerging Technologies for Smart Grid, 579–97. Cham: Springer International Publishing, 2024. http://dx.doi.org/10.1007/978-3-031-18389-8_25.

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Balogiannis, G., D. Yova, and K. Politopoulos. "3D Reconstruction of Skin Surface Using an Improved Shape-from-Shading Technique." In IFMBE Proceedings, 439–42. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-00846-2_109.

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Kumar, Rakesh, Naveenkumar Tadikonda, Jitendra Kumar, and R. N. Mahanty. "An ANN-Based MPPT Technique for Partial Shading Photo Voltaic Distribution Generation." In Lecture Notes in Electrical Engineering, 391–403. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-0193-5_32.

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Markin, L. V. "Technique to Calculate the Solar Cell Shading When Designing Solar Power Plants." In Proceedings of the 5th International Conference on Construction, Architecture and Technosphere Safety, 263–72. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-91145-4_26.

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Lu, Hesong, Zaijiang Tang, Qiang Liang, and Wei Shao. "Study on the Key Technique of the Hill Shading Virtual Roaming System Based on XNA." In Communications in Computer and Information Science, 230–38. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-662-45498-5_26.

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Bonthagorla, Praveen Kumar, Suresh Mikkili, and Kanjune Akshay Bapurao. "Optimal Sudoku Static Reconfiguration Technique for Power Enhancement of PV Array Under Partial Shading Conditions." In Smart Technologies for Power and Green Energy, 235–50. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-2764-5_20.

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Nagadurga, T., P. V. R. L. Narasimham, and V. S. Vakula. "Maximum Power Extraction from Solar Photovoltaic Strings Using Grey Wolf Optimization Technique Under Partial Shading Condition." In Algorithms for Intelligent Systems, 165–75. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-2109-3_15.

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Shankar, P. Mohana. "Diversity Techniques." In Fading and Shadowing in Wireless Systems, 313–416. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4614-0367-8_5.

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Conference papers on the topic "Shading technique"

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Mecca, Roberto. "Uniqueness for shape from shading via photometric stereo technique." In 2011 18th IEEE International Conference on Image Processing (ICIP 2011). IEEE, 2011. http://dx.doi.org/10.1109/icip.2011.6116274.

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Aliaslkhiabani, Mahdieh, Francisco Paz, Martin Ordonez, and Liwei Wang. "Partial Shading Mitigation in Photovoltaic Arrays using Shade Dispenser Technique." In 2019 IEEE 10th International Symposium on Power Electronics for Distributed Generation Systems (PEDG). IEEE, 2019. http://dx.doi.org/10.1109/pedg.2019.8807663.

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Dixit, Sudhir S. "An Adaptive Preprocessing Technique For Shading Correction, Contrast Enhancement, And Thresholding." In OE LASE'87 and EO Imaging Symp (January 1987, Los Angeles), edited by Julian Marshall. SPIE, 1987. http://dx.doi.org/10.1117/12.940049.

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Nagvekar, Purva, and R. A. Metri. "An Improved GMPPT Technique Under Partial Shading Conditions for PV Array." In 2019 International Conference on Computation of Power, Energy, Information and Communication (ICCPEIC). IEEE, 2019. http://dx.doi.org/10.1109/iccpeic45300.2019.9082383.

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Yang, Bei. "Genetic Algorithm Based PV Array Reconfiguration Technique under Partial Shading Condition." In 2023 IEEE International Conference on Power Science and Technology (ICPST). IEEE, 2023. http://dx.doi.org/10.1109/icpst56889.2023.10164934.

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Tayyab, Hafiz Muhammad, Yaqoob Javed, Irfan Ullah, Abid Ali Dogar, and Burhan Ahmed. "A Hybrid MPPT Technique for Solar Photovoltaic System under Partial Shading." In International Conference on Energy, Power and Environment. Basel Switzerland: MDPI, 2021. http://dx.doi.org/10.3390/engproc2021012028.

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Ojima, Shuichi. "A simple enhancement technique for shading in 2D images by retinex model." In TENCON 2011 - 2011 IEEE Region 10 Conference. IEEE, 2011. http://dx.doi.org/10.1109/tencon.2011.6129108.

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Young-Hyok Ji, Jun-Gu Kim, Sang-Hoon Park, Jae-Hyung Kim, and Chung-Yuen Won. "C-language based PV array simulation technique considering effects of partial shading." In 2009 IEEE International Conference on Industrial Technology - (ICIT). IEEE, 2009. http://dx.doi.org/10.1109/icit.2009.4939687.

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Dai, Gang, Zhong-Hua Shen, Jian Lu, and Xiao Wu Ni. "Measurement of target deformation under laser shock with optical beam shading technique." In Photonics Asia 2007, edited by Yongtian Wang, Theo T. Tschudi, Jannick P. Rolland, and Kimio Tatsuno. SPIE, 2007. http://dx.doi.org/10.1117/12.756695.

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AL-Emam, Mohamed, Mostafa I. Marei, and Walid El-khattam. "A Maximum Power Point Tracking Technique for PV Under Partial Shading Condition." In 2018 8th IEEE India International Conference on Power Electronics (IICPE). IEEE, 2018. http://dx.doi.org/10.1109/iicpe.2018.8709506.

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Reports on the topic "Shading technique"

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Tanny, Josef, Gabriel Katul, Shabtai Cohen, and Meir Teitel. Micrometeorological methods for inferring whole canopy evapotranspiration in large agricultural structures: measurements and modeling. United States Department of Agriculture, October 2015. http://dx.doi.org/10.32747/2015.7594402.bard.

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Original objectives and revisions The original objectives as stated in the approved proposal were: (1) To establish guidelines for the use of micrometeorological techniques as accurate, reliable and low-cost tools for continuous monitoring of whole canopy ET of common crops grown in large agricultural structures. (2) To adapt existing methods for protected cultivation environments. (3) To combine previously derived theoretical models of air flow and scalar fluxes in large agricultural structures (an outcome of our previous BARD project) with ET data derived from application of turbulent transport techniques for different crops and structure types. All the objectives have been successfully addressed. The study was focused on both screenhouses and naturally ventilated greenhouses, and all proposed methods were examined. Background to the topic Our previous BARD project established that the eddy covariance (EC) technique is suitable for whole canopy evapotranspiration measurements in large agricultural screenhouses. Nevertheless, the eddy covariance technique remains difficult to apply in the farm due to costs, operational complexity, and post-processing of data – thereby inviting alternative techniques to be developed. The subject of this project was: 1) the evaluation of four turbulent transport (TT) techniques, namely, Surface Renewal (SR), Flux-Variance (FV), Half-order Time Derivative (HTD) and Bowen Ratio (BR), whose instrumentation needs and operational demands are not as elaborate as the EC, to estimate evapotranspiration within large agricultural structures; and 2) the development of mathematical models able to predict water savings and account for the external environmental conditions, physiological properties of the plant, and structure properties as well as to evaluate the necessary micrometeorological conditions for utilizing the above turbulent transfer methods in such protected environments. Major conclusions and achievements The major conclusions are: (i) the SR and FV techniques were suitable for reliable estimates of ET in shading and insect-proof screenhouses; (ii) The BR technique was reliable in shading screenhouses; (iii) HTD provided reasonable results in the shading and insect proof screenhouses; (iv) Quality control analysis of the EC method showed that conditions in the shading and insect proof screenhouses were reasonable for flux measurements. However, in the plastic covered greenhouse energy balance closure was poor. Therefore, the alternative methods could not be analyzed in the greenhouse; (v) A multi-layered flux footprint model was developed for a ‘generic’ crop canopy situated within a protected environment such as a large screenhouse. The new model accounts for the vertically distributed sources and sinks within the canopy volume as well as for modifications introduced by the screen on the flow field and microenvironment. The effect of the screen on fetch as a function of its relative height above the canopy is then studied for the first time and compared to the case where the screen is absent. The model calculations agreed with field experiments based on EC measurements from two screenhouse experiments. Implications, both scientific and agricultural The study established for the first time, both experimentally and theoretically, the use of four simple TT techniques for ET estimates within large agricultural screenhouses. Such measurements, along with reliable theoretical models, will enable the future development of lowcost ET monitoring system which will be attainable for day-to-day use by growers in improving irrigation management.
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Heitman, Joshua L., Alon Ben-Gal, Thomas J. Sauer, Nurit Agam, and John Havlin. Separating Components of Evapotranspiration to Improve Efficiency in Vineyard Water Management. United States Department of Agriculture, March 2014. http://dx.doi.org/10.32747/2014.7594386.bard.

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Vineyards are found on six of seven continents, producing a crop of high economic value with much historic and cultural significance. Because of the wide range of conditions under which grapes are grown, management approaches are highly varied and must be adapted to local climatic constraints. Research has been conducted in the traditionally prominent grape growing regions of Europe, Australia, and the western USA, but far less information is available to guide production under more extreme growing conditions. The overarching goal of this project was to improve understanding of vineyard water management related to the critical inter-row zone. Experiments were conducted in moist temperate (North Carolina, USA) and arid (Negev, Israel) regions in order to address inter-row water use under high and low water availability conditions. Specific objectives were to: i) calibrate and verify a modeling technique to identify components of evapotranspiration (ET) in temperate and semiarid vineyard systems, ii) evaluate and refine strategies for excess water removal in vineyards for moist temperate regions of the Southeastern USA, and iii) evaluate and refine strategies for water conservation in vineyards for semi-arid regions of Israel. Several new measurement and modeling techniques were adapted and assessed in order to partition ET between favorable transpiration by the grapes and potentially detrimental water use within the vineyard inter-row. A micro Bowen ratio measurement system was developed to quantify ET from inter-rows. The approach was successful at the NC site, providing strong correlation with standard measurement approaches and adding capability for continuous, non-destructive measurement within a relatively small footprint. The environmental conditions in the Negev site were found to limit the applicability of the technique. Technical issues are yet to be solved to make this technique sufficiently robust. The HYDRUS 2D/3D modeling package was also adapted using data obtained in a series of intense field campaigns at the Negev site. The adapted model was able to account for spatial variation in surface boundary conditions, created by diurnal canopy shading, in order to accurately calculate the contribution of interrow evaporation (E) as a component of system ET. Experiments evaluated common practices in the southeastern USA: inter-row cover crops purported to reduce water availability and thereby favorably reduce grapevine vegetative growth; and southern Israel: drip irrigation applied to produce a high value crop with maximum water use efficiency. Results from the NC site indicated that water use by the cover crop contributed a significant portion of vineyard ET (up to 93% in May), but that with ample rainfall typical to the region, cover crop water use did little to limit water availability for the grape vines. A potential consequence, however, was elevated below canopy humidity owing to the increased inter-row evapotranspiration associated with the cover crops. This creates increased potential for fungal disease occurrence, which is a common problem in the region. Analysis from the Negev site reveals that, on average, E accounts for about10% of the total vineyard ET in an isolated dripirrigated vineyard. The proportion of ET contributed by E increased from May until just before harvest in July, which could be explained primarily by changes in weather conditions. While non-productive water loss as E is relatively small, experiments indicate that further improvements in irrigation efficiency may be possible by considering diurnal shading effects on below canopy potential ET. Overall, research provided both scientific and practical outcomes including new measurement and modeling techniques, and new insights for humid and arid vineyard systems. Research techniques developed through the project will be useful for other agricultural systems, and the successful synergistic cooperation amongst the research team offers opportunity for future collaboration.
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Tanny, Josef, Gabriel Katul, Shabtai Cohen, and Meir Teitel. Application of Turbulent Transport Techniques for Quantifying Whole Canopy Evapotranspiration in Large Agricultural Structures: Measurement and Theory. United States Department of Agriculture, January 2011. http://dx.doi.org/10.32747/2011.7592121.bard.

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Original objectives and revisions The original objectives of this research, as stated in the approved proposal were: 1. To establish guidelines for the use of turbulent transport techniques as accurate and reliable tool for continuous measurements of whole canopy ET and other scalar fluxes (e.g. heat and CO2) in large agricultural structures. 2. To conduct a detailed experimental study of flow patterns and turbulence characteristics in agricultural structures. 3. To derive theoretical models of air flow and scalar fluxes in agricultural structures that can guide the interpretation of TT measurements for a wide range of conditions. All the objectives have been successfully addressed within the project. The only modification was that the study focused on screenhouses only, while it was originally planned to study large greenhouses as well. This was decided due to the large amount of field and theoretical work required to meet the objectives within screenhouses. Background In agricultural structures such as screenhouses and greenhouses, evapotranspiration (ET) is currently measured using lysimeters or sap flow gauges. These measurements provide ET estimates at the single-plant scale that must then be extrapolated, often statistically or empirically, to the whole canopy for irrigation scheduling purposes. On the other hand, turbulent transport techniques, like the eddy covariance, have become the standard for measuring whole canopy evapotranspiration in the open, but their applicability to agricultural structures has not yet been established. The subject of this project is the application of turbulent transport techniques to estimate ET for irrigation scheduling within large agricultural structures. Major conclusions and achievements The major conclusions of this project are: (i) the eddy covariance technique is suitable for reliable measurements of scalar fluxes (e.g., evapotranspiration, sensible heat, CO2) in most types of large screenhouses under all climatic conditions tested. All studies resulted with fair energy balance closures; (ii) comparison between measurements and theory show that the model is capable in reliably predicting the turbulent flow characteristics and surface fluxes within screenhouses; (iii) flow characteristics within the screenhouse, like flux-variance similarity and turbulence intensity were valid for the application of the eddy covariance technique in screenhouses of relatively dilute screens used for moderate shading and wind breaking. In more dense screens, usually used for insect exclusions, development of turbulent conditions was marginal; (iv) installation of the sensors requires that the system’s footprint will be within the limits of the screenhouse under study, as is the case in the open. A footprint model available in the literature was found to be reliable in assessing the footprint under screenhouse conditions. Implications, both scientific and agricultural The study established for the first time, both experimentally and theoretically, the use of the eddy covariance technique for flux measurements within agricultural screenhouses. Such measurements, along with reliable theoretical models, will enable more accurate assessments of crop water use which may lead to improved crop water management and increased water use efficiency of screenhouse crops.
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