Wyniki wyszukiwania - Biblioteka Nauki

1

Impact of Shading of a Silvopastoral System on Microclimate and Botanical Composition of Polyphytic Pasture: A Preliminary Study in the Subtropics

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Vieira F. M. C. , Militão É. R. , Wagner Júnior A. , Herbut P. , Mayer L. R. R. , Vismara E. S. , Vieira A. M. C. , Paris W. , Hermes C. , Paśmionka I.

Journal of Ecological Engineering

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2021

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tom Vol. 22, nr 10

215--224

EN

The silvopasture system is an integrated system which has been widespread in tropical and sub-tropical climates. However, there is a lack of detailed studies regarding agroecological silvopasture systems. This study assessed whether the different levels of shading in an agroecological silvopastoral system influences the microclimate and botanical composition of polyphytic pasture. We used eight paddocks composed of a silvopastoral system in a subtropical climate, with different tree species arranged in simple lines with polyphytic pasture. In each paddock, we established three levels of visual shading (under the canopy, intermediate and full sun). The following microclimatic variables were recorded monthly during the daytime: illuminance, air temperature, air relative humidity, wind speed, and surface soil temperature. The samples of forages were separated into grasses, legumes and spontaneous, then fractionated into leaves, stems, and senescent material. We observed lower values of illuminance and surface soil temperature under the canopy, with differences between full sun and under the canopy at noon. Regarding the forage, the percentage of legumes was higher in full sun, and spontaneous species and leaves had high proportions under the canopy. Based on the results, the agroecological silvopastoral system changed the microclimatic characteristics and altered the plant composition of polyphytic pasture.

2

Zacienianie budynków. Wykorzystywanie diagramów drogi słońca przy określaniu zacienienia

100%

Chwieduk D.

Polska Energetyka Słoneczna

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2004

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tom nr 2-4

18-22

PL

W artykule przeanalizowano warunki powstawania zacienienia budynku spowodowanego znajdującymi się w jego sąsiedztwie naturalnymi i sztucznymi przeszkodami. Przedstawiono sposób tworzenia diagramów drogi Słońca oraz możliwość ich wykorzystania do określania zacieniania budynku.

3

Minimizing CPU usage in soft shadow volumes algorithm

100%

Lipowski J.

Machine Graphics and Vision

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2006

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tom Vol. 15, No. 3/4

493-503

EN

In this paper we present methods for reducing the CPU burden associated with the original implementation of the hardware-accelerated soft shadow volumes algorithm. We propose and implement two hardware-accelerated wedge construction methods: using the programmable vertex and fragment pipelines. New algorithms reducing the number of draw calls needed to render the shadow region (to three, two or even one) are also described. Tests performed using the current consumer level hardware show that our algorithms are no longer CPU-bound, and therefore can be over 2 times faster than the original algorithm.

4

The impact of shading on solar cell electrical parameters

100%

Swatowska B. , Panek P.

Optica Applicata

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2017

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tom Vol. 47, nr 2

319--323

EN

Availability of light to solar cells is crucial for the efficiency of photovoltaic systems. For this reason, even partial shading can result in significant reduction of generated electric power (loss of current). This paper examines the changes in the efficiency of multicrystalline silicon solar cells which are caused by different kinds of shading. Full and partial shading were simulated by the use of three types of shutter-foils printed in a gray and black scale. The measurements of current-voltage characteristics show that totally or partially shaded modules can drastically reduce the generated power. Short circuit current decreases from about 8100 to 100 mA that in the case of the series connection of cells in a module, lead to the shift of the point of the maximum power and finally to the considerable reduction of nominal system photovoltaic power.

5

Real-time wetting of porous media

88%

Hnat K. , Porquet D. , Merillou S. , Ghazanfarpour D.

Machine Graphics and Vision

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2006

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tom Vol. 15, No. 3/4

401-413

EN

Studying light reflection properties is a crucial factor in achieving a high degree of realism in image synthesis. Considered as a challenge in itself, it becomes even more complicated when dealing with specific changes in appearance due to external factors. Among these changes, one of the most common is wetting: surfaces appear darker and more specular as their wetting level increase. Such a phenomenon is of great visual importance in outdoor scenes under rain falls, for example. This change in appearance is mainly due to the porous nature of surfaces. In this paper, we propose to handle a porous surface BRDF post-process model in real-time and to extend it to account for wetting, with simple and intuitive parameters.

6

Application of a Control Algorithm for the Master Unit of a Distributed Photovoltaic System

75%

Świderski M. , Gąsiorek A.

International Journal of Electronics and Telecommunications

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2022

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tom Vol. 68. No. 4

863--866

EN

The presented distributed photovoltaic system is made of divided into individual modules photovoltaic panel, consisting of several photovoltaic cells properly connected and coupling them with low-power DC / DC converters. The essence of the research is to increase the reliability of the system and the resultant efficiency of the entire system, so that it is possible to convert solar radiation energy into electricity with the greatest efficiency. The article focuses on the presentation of the implementation and tests of the overriding control algorithm, the task of which is to provide full functionality for a distributed photovoltaic system. The control is designed to minimize the negative effects of shadows on the operation of the photovoltaic system and conduct self-diagnostics. The conclusion for the carried out work is the formulation of hardware and interface requirements for the further development of the project.

7

Investigating plant growth and physiological response to soil wetting with grey water under different shade regimes: a case of fluted pumpkin (Telfairia occidentalis)

75%

Ikhajiagbe B. , Anoliefo G. O. , Ohanmu E. O. , Omoregie G. O. , Uwagboe T.

Electronic Journal of Polish Agricultural Universities. Series Agronomy

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2017

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tom 20

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nr 4

8

Wpływ efektu zacienienia na pracę elektrowni solarnej z systemem rozproszonych paneli fotowoltaicznych

63%

Świderski M. , Gwóźdź M.

Przegląd Elektrotechniczny

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2020

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tom R. 96, nr 7

76--79

PL

Instalacje fotowoltaiczne coraz bardziej wpisują się w krajobraz Polski. Biorąc pod uwagę geograficzne uwarunkowania naszego kraju, jak również mając na uwadze niekorzystny wpływ zjawiska zacieniania na pracę systemu fotowoltaicznego należy zastanowić się, czy klasyczna struktura elektrowni solarnej jest tutaj najlepszym rozwiązaniem. W niniejszej pracy zaprezentowana została koncepcja elektrowni fotowoltaicznej o tzw. strukturze rozproszonej, polegającej na podziale panelu fotowoltaicznego na mniejsze części. Szczególna uwaga poświęcona została podstawowemu elementowi każdej elektrowni tego typu, czyli ogniwu fotowoltaicznemu, od którego w głównej mierze zależą parametry robocze całego systemu. W rozdziale opisującym dobór parametrów i struktury modułu fotowoltaicznego oraz wyniki jego badań laboratoryjnych pokazano, jak dużą stratę mocy generowanej przez moduł powoduje zacienienie o niewielkich wymiarach – stanowiące tutaj mniej niż 1% powierzchni całego modułu Wykazano również, że poza powierzchnią zacienienia, istotny wpływ na wartość straty mocy ma również położenie miejsca zacienienia.

EN

Photovoltaic installations have blend in the Polish landscape. Taking into account the geography of our country, as well as bearing in mind the negative impact of shading on the operation of photovoltaic systems, it should be considered whether the classic structure of a solar plant is the best solution. In this paper, the concept of power plant based on system of distributed photovoltaic panels is presented. Particular attention is paid to the photovoltaic cell, being a basic element of each power plant of this type, on which the operation parameters of the entire system depend. The chapter describing the selection of solar module parameters and its structure, as well as the results of laboratory tests, shows how much power loss, generated by the module, is caused by shading of a small area (less than 1% of the surface of entire module). It is also shown that, apart from the shaded surface, the location of the shaded space has a significant influence on the value of the power loss.

9

Do trees make a difference? An evaluation of the impact of riparian vegetation on the ecology of nutrient poor headwater streams

63%

O'Driscoll J. F. , Harrison S. S. C. , Giller P. S.

Polish Journal of Ecology

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2006

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tom Vol. 54, nr 4

695-700

EN

The presence of riparian vegetation is shown to affect both physical and biological properties of headwater streams. Riparian vegetation mediates food resource availability for macroinvertebrates and fish within streams through addition of allochthonous material such as leaves, woody debris and terrestrial invertebrates. Riparian shade can also reduce biomass and production of autochthonous algae. The potential role of riparian vegetation in enhancing biodiversity and productivity of headwater streams is discussed, with reference to improving salmonid fish stocks in the headwater streams of Ireland and Great Britain.

10

Poradnik dla początkującego witrażysty. Malowanie witraża klasycznego. Odcinek 18. Światłocień i cieniowanie

63%

Bochacz A. , Bochacz A.

Szkło i Ceramika

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2017

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tom R. 68, nr 1

46

11

New surface reflectance model with the combination of two cubic functions usage

63%

Romanyuk O. , Zavalniuk Y. , Pavlov S. , Chekhmestruk R. , Bondarenko Z. , Koval T. , Kalizhanova A. , Iskakova A.

Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska

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2023

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tom T. 13, nr 3

101--106

EN

In the article themodel of light reflection based on the combination of two cubicbidirectional reflectancedistribution functions is developed.The main components of color and the main requirements for reproducing the object`s glaresareanalyzed. The usage characteristicsof Cook-Torrance, Bagher, Oren-Nayar, coupled Shirley reflection models are described. The advantages and disadvantages of the highly productive Blinn-Phong modelare considered. The necessity of approximating the Blinn-Phong model by a function of low degree is justified. The characteristics of the cubic polynomial approximation of the Blinn-Phong model are determined. It was established that the main drawback of this approximation is a significant deviationof the function from the reference function in the glare’sattenuation zone. Thecombined function that combines two cubic functions is proposed. The first cubic function reproduces the glare’s epicenter, and the second replaces the specified function in the attenuation zone. A system of equationsfor calculating the coefficients of the second function was created. The formula for the connectionpointof two cubic functions is obtained. A graphof the developed combined model based on cubic functions is obtained. For the combined and original cubic functions a comparison of the maximum relative errors in the glare’sepicenterzone, the maximum absolute errors, and the relative errors at the inflection point was made. A three-dimensional plot of the absolute error of the combined cubic model from the Blinn-Phong modeldepending on the shininessand the angle value is built. Visualization results based on the combined and the original cubic functionsare compared. It is confirmed that the proposed reflection model increases the realismof glare formation in the attenuation zone. The resulting combined reflection model provides a highlyaccurate approximation of the Blinn-Phong model and is highly efficient because the third power function is used.

PL

W artykule opracowano model odbicia światła oparty na kombinacji dwóch sześciennych dwukierunkowych funkcji rozkładu odbicia.Przeanalizowano główne składniki koloru i główne wymagania dotyczące odtwarzania odblasków obiektu. Opisano charakterystykę użytkowania modeli odbicia Cooka-Torrance'a, Baghera, Orena-Nayara i Shirleya. Rozważono zalety i wady wysoce wydajnego modelu Blinn-Phong. Uzasadniono konieczność aproksymacji modelu Blinna-Phonga funkcją niskiego stopnia. Określono charakterystykę wielomianu sześciennego aproksymującego model Blinna-Phonga. Ustalono, że główną wadą tej aproksymacji jest znaczne odchylenie funkcji od funkcji odniesienia wstrefie tłumienia olśnienia. Zaproponowano funkcję kombinowaną, która łączy dwie funkcje sześcienne. Pierwsza funkcja sześcienna odtwarza epicentrum olśnienia, a druga zastępuje określoną funkcję w strefie tłumienia. Stworzono układ równań do obliczania współczynników drugiej funkcji. Uzyskano wzór na punkt połączenia dwóch funkcji sześciennych. Uzyskano wykres opracowanego połączonego modelu opartego na funkcjach sześciennych. Dla połączonychi oryginalnych funkcji sześciennych dokonano porównania maksymalnych błędów względnych w strefie epicentrum olśnienia, maksymalnych błędów bezwzględnych i błędów względnych w punkcie przegięcia. Zbudowano trójwymiarowy wykres błędu bezwzględnego połączonego modelusześciennegoz modelu Blinna-Phonga w zależności od połysku i wartości kąta. Porównano wyniki wizualizacji oparte na połączonych i oryginalnych funkcjach sześciennych. Potwierdzono, że proponowany model odbicia zwiększa realizm powstawania odblasków w strefie tłumienia. Wynikowypołączony model odbicia zapewnia bardzo dokładne przybliżenie modelu Blinna-Phonga i jest bardzo wydajny, ponieważ używana jest funkcja trzeciej potęgi.

12

Określenie zacienienia zabudowy jednorodzinnej na podstawie danych z lotniczego skaningu laserowego

63%

Witkowska A.

Roczniki Geomatyki

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2012

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tom T. 10, z. 4

157--164

PL

Promieniowanie słoneczne jest kluczowym składnikiem procesów: fizycznych i biologicznych, które mają miejsce na naszej planecie. Jednocześnie jest ono silnie związane zarówno z topografią terenu, jak również z samym otoczeniem: zabudową, drzewami czy roślinami znajdującymi się w bezpośrednim sąsiedztwie. Zacienie dowolnej powierzchni jest spowodowane przez osłabienie docierającego do niej strumienia promieniowania i może być całkowite lub częściowe. Gdy obiekt utrudniający dostęp promieniowania słonecznego nie jest przeźroczysty, na przykład sąsiednie budynki, mówimy o zacienieniu całkowitym. W przypadku gdy przeszkodę charakteryzuje określona przepuszczalność promieniowania, wówczas mówimy o zacienieniu częściowym. Przykładem obiektów, które cechują się określoną transmisyjnością są drzewa. W zależności od gatunku, wysokości i rozpiętości korony charakteryzują się one większą lub mniejszą zdolnością do przepuszczania promieniowania słonecznego. Literatura związana z energetyką słoneczną przy wyznaczaniu zacieniania opiera się na wykorzystaniu diagramów drogi słońca. Diagram drogi słońca w sposób graficzny prezentuje położenie słońca na nieboskłonie. Za jego pomocą jest zilustrowana pozycja słońca w funkcji czasu różnych dni roku. Po raz pierwszy diagramy drogi słońca zostały wprowadzone przez Olgayay A. i Olgyay V., zaś ich rozpowszechnienie spowodował Mazria. Diagramy słońca są powszechnie stosowaną metodą przy wyznaczaniu zacienienia promieniowania bezpośredniego dla dowolnej powierzchni zwróconej w kierunku południowym, co zostało osiągnięte przez połączenie geometrii ruchu słońca oraz natężenia promieniowania słonecznego. W artykule podjęto próbę opracowania modelu zacienienia przy wykorzystaniu narzędzi GIS oraz w oparciu o numeryczny model pokrycia terenu. Indywidualna analiza została przeprowadzona na przykładzie osiedla domów jednorodzinnych. Narzędzie, które wykorzystano w opracowaniu to moduł Spatial Analyst, który jest zarazem częścią środowiska ArcGIS. Narzędzie to ma zastosowanie przy obliczaniu nasłonecznienia [Wh/m2] ale w swoich kalkulacjach nie uwzględnia promieniowania odbitego. W badaniu nad zagadnieniem zacienienia wygenerowano przestrzenny rozkład nasłonecznienia dla promieniowania bezpośredniego i rozproszonego oraz ich sumę – nasłonecznienie całkowite. Na jej podstawie stworzono symulację zmian zacienienia zabudowy jednorodzinnej z uwzględnieniem występowania elementów tworzących otoczenie. Zmiany zacienienia prześledzono w funkcji czasu na przykładzie wybranego dnia oraz na przestrzeni roku kalendarzowego z interwałem trzech miesięcy. Publikacja ponadto skupia się na potencjalnych korzyściach wykorzystania technik GIS w opracowaniu modelu zacienienia.

EN

Solar radiation is the fundamental component of physical and biological processes taking place on our planet. It is strongly connected both with the topography of the terrain and with the surroundings: buildings, trees or plants in the direct neighborhood. Shading of any surface is caused by the weakness of stream radiation which can be total or partial. When the object obstructing solar radiation is not transparent, e.g. neighboring buildings, we talk about total shading. In the case when the obstruction is transparent, we talk about partial shading. Trees are an example of objects which are transparent. They are characterized by greater or smaller ability of letting through the solar radiation in dependence from species, height and the crown span. The literature connected with the solar radiation and determining of shading is based on utilization of diagrams of Sun position. The diagram of Sun position in a graphic way of presenting the position of Sun on the horizon. It illustrates the position of the Sun in the function of time in various days of the year. The first diagrams of the Sun position were introduced by Olgayay A. and Olgyay V. and Mazria caused their dissemination. The diagrams of the Sun position are a universal method of marking the shading of direct radiation for any surface turned in the southern direction, what was reached by the connection to the geometry of Sun position and the intensity of solar radiation. In the paper, I tried to model shading using GIS tools and the Digital Surface Model (DSM). The individual analysis was conducted for single family houses. The module Spatial Analyst was used which is also a part of ArcGIS environment. This tool can calculate the insolation [Wh/m2] but it does not take into account the reflected radiation. The spatial schedule of shadow was generated from the direct and diffused radiation and their sum – the total insolation. The simulation of changes in shading of single family buildings was created with the regard to the occurrence of elements of the surroundings. The changes of shading were traced in the function of time on the example of a selected day and on span of the calendar year with three month intervals. In addition, the publication concentrates on the potential advantages of using the GIS techniques in the study of the model of shading.

13

Analysis of changes in electrical parameters of photovoltaic roof tiles depending on the place of shading and connection configuration

63%

Kurz D. , Nawrowski R. , Kałuża S.

Przegląd Elektrotechniczny

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2022

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tom R. 98, nr 7

124--130

EN

The paper presents the research on the influence of the connection configuration and the location of the PV cells shading on the output parameters of photovoltaic roof tiles. The problem of shading occurs in all photovoltaic installations, but in the case of solar tiles it can cause much greater power losses than in the case of traditional panels. The series, parallel and series-parallel configurations of photovoltaic roof tiles with different shading locations were tested. The values of roof tiles output parameters, current-voltage and power characteristics of the analyzed systems were presented.

PL

W pracy przedstawiono badania wpływu konfiguracji połączeń oraz lokalizacji zacienienia ogniw PV na parametry wyjściowe dachówek fotowoltaicznych. Problem zacienienia występuje we wszystkich instalacjach z fotowoltaicznymi, jednak w przypadku dachówek solarnych może on powodować znacznie większe straty mocy niż w przypadku tradycyjnych paneli. Przebadano konfiguracje szeregową, równoległą oraz szeregowo-równoległą dachówek fotowoltaicznym z różnymi miejscami wystąpienia zacienień. Przedstawiono wartości parametrów wyjściowych dachówek, charakterystyki prądowo-napięciowe oraz mocowe analizowanych układów.

14

Cienie i cieniowanie w grafice komputerowej

63%

Helenowska-Peschke M.

Journal Biuletyn of Polish Society for Geometry and Engineering Graphics

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2003

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tom Vol. 13

19--23

PL

Współcześnie grafika komputerowa umożliwia tworzenie światłocieni z powodzeniem symulujących efekty oświetlenia obiektów występujące w świecie rzeczywistym. W artykule krótko przedstawiono podstawowe algorytmy wyznaczania cieni oraz możliwości kreowania cieni w 3D Studio – popularnym programie typu CAD.

EN

Contemporary computer graphics has an ability to create shade and shadows which successfully stimulate light effects in real world. In the paper basic algorithms for creating shade and shadows are shortly presented as well as shade and shadow options in 3D Studio – the popular CAD program.

15

The effect of vegetation character on abundance and structure of subpopulations of rare herb species Gentiana pneumonanthe L.

63%

Kostrakiewicz-Gieralt K.

Polish Journal of Ecology

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2013

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tom 61

|

nr 1

EN

During the 20th century in Central and Eastern Europe, traditional agricultural management was either heavily intensified or abandoned due to socio-economic reasons. The land abandonment led to subsequent secondary succession reverted many wet meadows into Phragmites swamps, Salix or Alnus thickets, as well as woodlands. Therefore, the understanding of changes in abundance and structure of populations in the process of succession has become very important especially for rare and endangered species. In Poland one of strictly protected plant is Gentiana pneumonanthe L. It is a nonclonal, long-lived, iteroparous plant consisted of numerous vegetative and generative stems, bearing 1–25 flowers per year. The investigations of abundance and structure of subpopulations of Gentiana pneumonanthe were conducted in the years 2009– 2011 in abandoned Molinietum caeruleae meadows dominated by low-stature species (Patch I), prevailed by tall grasses (Patch II), willows (Patch III), as well as partly overgrown by shrubs and trees (Patch IV). The average height of vegetation cover achieved from 65.3 cm (Patch I), via 85.8 cm (Patch II) and 94.0 cm (Patch III), to 142.7 cm (Patch IV). The gradually decline of abundance of Gentiana pneumonathe subpopulations and increased trend toward their senilization along the gradient of vegetation height might be due to successional closure of plant cover, preventing seedling recruitment. The total number of stems per individual and length of vegetative stems decreased with augmentation of neighbouring plants dimensions, whereas the height of generative stems, as well as flower and fruit production presented inversed trend. The greatest dimensions of capsules found in patch dominated by small meadow species might be due to greater availability of solar radiation. The conditions of studied subpopulations decrease gradually from patch dominated by small meadow species, via sites prevailed by grasses and willows, to place overgrown by shrubs and trees. Although obvious differences in abundance and structure of individuals, the prospects of all observed populations are poor, especially that patches are not subjected active protection.

16

Allometric partitioning theory versus optimal partitioning theory: the adjustment of biomass allocation and internal C-N balance to shading and nitrogen addition in Fritillaria unibracteata (Liliaceae)

63%

Guo H. , Xu B. , Wu Y. , Shi F. , Wu C. , Wu N.

Polish Journal of Ecology

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2016

|

tom 64

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nr 2

EN

Fritillaria unibracteata is a classic perennial alpine herb. In this study, we examined it's responses to shading (SH) and nitrogen addition (NA), as well as its correlation with internal C-N balance to detect how it adjusted to the changes of habitat conditions. Randomized block experiment was carried out in the field in Chuanbeimu Research Station in Songpan County, Sichuan Province, China (32°09′54″N, 103°38′36″E, altitude 3300 m a.s.l.). Two growing seasons after NA and SH, Fritillaria unibracteata's total plant biomass decreased significantly, with the proportion of biomass allocated to aboveground significantly increased. In addition, in this study, under both SH and NA treatments, Fritillaria unibracteata increased its biomass allocation to above-ground, which consisted with optimal partitioning theory. Moreover, Fritillaria unibracteata's biomass allocation was significantly correlated with its internal C-N status, regardless of nitrogen and light condition. We conclude that Fritillaria unibracteata optimizes its biomass allocation between root and shoot by adjusting its internal C-N balance, which would not be changed by the specialized resource storage organ-bulb.

17

Analysis of the influence of shading by horizon of PV cells on the operational parameters of a photovoltaic system

63%

Głuchy D. , Kurz D. , Trzmiel G.

Przegląd Elektrotechniczny

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2014

|

tom R. 90, nr 4

78--80

EN

The work presents the components of solar radiation that reaches the horizontal plane and a method of determining the energy value of the radiation that reaches the surface of a photovoltaic receiver inclined to the ground line at a certain angle. A shading assessment diagram and a methodology for determining the vertical angles and the influence of the horizon on the shading of a PV receiver were provided. A method of determining the direct radiation correction factor depending on the horizon line was presented. The influence of light shading on the current and voltage characteristics of a solar module was determined.

PL

W pracy przedstawiono składowe promieniowania słonecznego docierającego do powierzchni horyzontalnej oraz sposób wyznaczenia wartości energii promieniowania padającej na powierzchnię odbiornika fotowoltaicznego nachylonego pod pewnym kątem do ziemi. Zamieszczono diagram oceny cieniowania oraz metodykę wyznaczenia kątów pionowych i wpływu horyzontu na cieniowanie odbiornika PV. Przedstawiono sposób wyznaczania współczynnika korekcyjnego promieniowania bezpośredniego wywołanego linią horyzontu. Określono wpływ słabego cienia na charakterystykę prądowo-napięciową modułu solarnego.

18

Aspekty wizualizacji rzeźby terenu w czasie rzeczywistym

63%

Stateczny A. , Łagowski T.

Roczniki Geomatyki

|

2005

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tom T. 3, z. 1

155-161

EN

The paper presents works on creation of an optimal model of data for real time visualization of topographic surface. The model should fulfill three conditions: 1) minimization of the amount of stored data, 2) dynamic adjustment of the model to the scale of imaging, 3) guarantee of obtaining required accuracy of surface reconstruction. On the basis of literature and experiments conducted a data model based on sections was selected and an algorithm for dynamic real time visualization was elaborated. The model consists In creation of dense sections which are generalized in successive steps. Thus, the model with minimum sections arises ensuring the accuracy of reconstruction assumed in advance. Individual sections are assigned so called .priorities., which determine whether they are used in next stages of model construction or not. The higher the priority the lower distance at which the section stall be further processed. The distance is calculated from the observer to the centre of gravity of the section. The method of further creation of the model based on a network of triangles consists of the following stages: 1. Generalization is performed with the aim of decreasing the number of points, on the basis of which the network of triangles will be created. The generalization covers: m Determination of the distance between the observer and each of the sections to be analysed. The number and selection of proper sections shall depend upon the scale in which the model of topographic surface will be pictured. Based on the distance and priority sections for further analysis are selected. Designation of condensed points created a broken line of sections selected at the preceding stage. These points undergo the generalization process in order to decrease the number of triangles for the further process of creation of the topographic surface visualization. The Douglas-Peucker method was selected for generalization ensuring high level of generalization and small deformations. 2. Triangulation. The number of objects which shall be created in this step depends on the level of generalization. The increase in the level of generalization shall result in an increase of the area to be pictured and, at the same time, the accuracy of the model shall decline. In order to decrease calculations, the triangulation is conducted between neighbouring sections by the method of biggest angles. On the basis of the experiments conducted it was found that this method gives the best results providing the greatest number of triangles per unit of time. 3. Shading and illumination. It follows from the assumptions that colour shall define the height (depth). Therefore, the methods based on flat shading, which assign only one colour to each surface and bring about the lack of smooth change in colour, were not further used in the analysis. On the basis of experiments conducted, the Gouraud method was selected fulfilling the assumptions and featured with the shortest time of object shading. In the opinion of the authors, the proposed model very well fulfills the conditions presented at the beginning.

19

Effect of the stock plant shading on rooting of stem cuttings in Ficus benjamina 'Daniell' and 'Starlight'

63%

Pacholczak A. , Szydlo W.

Annals of Warsaw Agricultural University. Horticulture (Landscape Architecture)

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2004

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tom 25

20

The effect of etiolation and shading of stock plants on rhizogenesis in stem cuttings of Cotinus coggygria

63%

Pacholczak A. , Szydlo W. , Lukaszewska A.

Acta Physiologiae Plantarum

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2005

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tom 27

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nr 4A

EN

In order to improve vegetative propagation of a difficult to root Cotinus coggygria the stock plants were subjected to: etiolation, shading and spraying with IBA, combined with the application of two commercially available rooting powders. The IBA treatment was more suitable for rooting of C. coggygria cuttings than the NAA application and it enhanced rhizot genesis regardless of the form of auxin application (foliar application to a stock plant or a rooting powder used directly on cuttings) and the amount of light provided to stock plants. Etiolation did not improve rhizogenesis in stem cuttings, however, reduction of light intensity by 50 % and 96 % of the ambient prior to harvest of cuttings affected rooting positively. Positive effects of shading can be ascribed to changes in shoot anatomy, i.e. a weaker sclerenchyma development. Synergistic effect of shading and Miar auxin application can result from the increase in leaf blade area and/or thinner lower epiderm. Em hanced rooting in cuttings from shoots grown out under reduced light intensity was accompanied by decrease in the contents of total soluble sugars, soluble proteins and free ABA and by increase in total chlorophyll, free amino acids, polyphenolic acids and free IAA contents.