Techn. Hochsch., Diss.--Aachen, 2006.

Σκοπός της διπλωματική αυτής εργασίας είναι η παραμετρική διερεύνηση ενός αυτόνομου φωτοβολταϊκού συστήματος. Η διερεύνηση αυτή γίνεται για έξι πόλης της Βορείου Ελλάδος με στόχο την εξαγωγή γενικών συμπερασμάτων σχετικά με τον σχεδιασμό αυτόνομων φωτοβολταϊκών συστημάτων. Πριν προχωρήσουμε στην παραμετρική διερεύνηση, θεωρήθηκε σκόπιμο να μελετήσουμε θεωρητικά τα κυριότερα μέρη ενός φωτοβολταϊκού συστήματος. Αρχικά, παρατίθεται μια σύντομη Εισαγωγή στην οποία παρουσιάζεται το ενεργειακό, ενώ τονίζεται η σημασία της ανάπτυξης και βελτίωσης ηλεκτροπαραγωγικών μεθόδων βασιζόμενες στις Ανανεώσιμες Πηγές Ενέργειας (Α.Π.Ε.). Στο κεφάλαιο 1, αναλύεται η αρχή λειτουργίας των ηλιακών κυττάρων. Επιπλέον, γίνεται αναφορά στην εξίσωση, την I-V χαρακτηριστική και την απόδοση των Φ/Β κυττάρων, ενώ αναφέρονται και τα κυριότερα είδη αυτών. Στο κεφάλαιο 2, αναφερόμαστε στα κύρια δομικά χαρακτηριστικά μιας Φ/Β συστοιχίας, καθώς και στα προβλήματα που αυτή αντιμετωπίζει και την επίλυση αυτών. Στο κεφάλαιο 3 παρατίθεται η αρχή λειτουργίας καθώς και η δομή των δευτερευόντων συσσωρευτών. Επίσης, ειδική αναφορά γίνεται στους συσσωρευτές Νικελίου-Καδμίου. Στο κεφάλαιο 4, αναπτύσσεται το μοντέλο το οποίο χρησιμοποιούμε για να μετατρέψουμε τιμές της προσπίπτουσας ηλιακής ακτινοβολίας σε οριζόντια επιφάνεια σε αντίστοιχες τιμές σε κεκλιμένη επιφάνεια. Στο κεφάλαιο 5, χρησιμοποιούμε το μοντέλο που αναπτύχθηκε στο κεφάλαιο 4 για τον υπολογισμό τιμών της ηλιακής ακτινοβολίας σε κεκλιμένη επιφάνεια, για τις έξι υπό μελέτη πόλεις, χρησιμοποιώντας ως τιμές εισόδου τις τιμές που παρατίθενται στον πίνακα Α.1 (Παράρτημα). Οι τιμές που υπολογίζουμε στο κεφάλαιο αυτό μπορούν να χρησιμοποιηθούν στο σχεδιασμό Φ/Β συστημάτων συνδεδεμένων με το δίκτυο. Στο κεφάλαιο 6, αναπτύσσεται μια μεθοδολογία υπολογισμού αυτόνομων Φ/Β συστημάτων. Στα κεφάλαια 7 και 8, χρησιμοποιούμε την μεθοδολογία που αναπτύχθηκε στο προηγούμενο κεφάλαιο για να προσομοιώσουμε την λειτουργία ενός αυτόνομου Φ/Β συστήματος για ετήσια και καλοκαιρινή λειτουργία αντίστοιχα. Μάλιστα, στο κεφάλαιο 8 χρησιμοποιούμε και μια παραλλαγή της βασικής μεθόδου για τη μελέτη της καλοκαιρινής περιόδου λειτουργίας του Φ/Β συστήματος. Τέλος, στον επίλογο γίνεται μια συνολική αποτίμηση όσων έγιναν στην διπλωματική αυτή εργασία και παρατίθενται κάποια γενικά συμπεράσματα. / This thesis deals with the parametric study of a Stand Alone Photovoltaic System. This study is being conducted in six cities of Northern Greece, for the purpose of extracting general guidelines regarding the design of stand-alone PV systems. Before we proceed with the study, it is considered useful to study theoretically the main parts of a stand-alone PV system. We start off with a short introduction in which the global energy problem is being described. Emphasis is also given to the importance of developing energy production methods based on Renewable Energy Sources. Chapter 1 deals with the working principle of solar cells. Furthermore, we also investigate the equivalent circuit model, the I-V curve and the efficiency of solar cells. Finally, the primary types of solar cells are being demonstrated. In chapter 2 we study the main parts of a PV array. We also refer to the problems that a PV array faces during its operation, as well as the possible solutions of these problems. In chapter 3 we refer to the working principles and to the structure of batteries. In particular, we study Nickel-Cadmium batteries. In chapter 4, the model that is used in order to convert solar radiation values, taken in horizontal surface, to corresponding values taken in inclined surface, is being described. In chapter 5, we use the model described in chapter 4 in order to calculate values of solar radiation in inclined surface, for the six cities in which this study takes place. The data based on which we calculate the above values are being demonstrated in table A.1 (appendix A). The values calculated in this chapter can be used in the design of a grid connected PV system. In chapter 6, a methodology used in designing a stand-alone PV system is being described. In chapters 7 and 8, we use the above methodology in order to simulate the operation of a stand-alone PV system during annual and summer working periods correspondingly. In chapter 8 we also use a slight alteration of the above methodology in order to study the operation of a stand-alone PV system, during a summer working period even further. Finally, an overall valuation of this thesis is made in the epilogue. Furthermore, some overall conclusions are being presented.

Relevance of the problem. Forest compartment under the conditions of intensive forestry is the main unit of management and inventory (Antanaitis, 1961; Franklin, 2001). Regular, every 10 years, standwise forest inventory requires great expenditures on compartment delineation and their depicting in cartographic material. Different executives, guided by the same standards, but without objective forest compartment delineation methodics, may divide one and the same object into compartments in different ways (Rutkauskas, Kenstavičius, 1978). Therefore, the variability of forest compartment boundaries is artificially increased. Under the absence of clear boundaries between compartments in the forest and considering that the whole forest is homogeneous, compartment characteristics are usually ascertained ignoring their peculiarities at the edges. This comprises preconditions for the appearance of systemic forest inventory deviations (Антанайтис и др., 1975; Kuliešis, Kasperavičius, 2000; Brassel, Lichke, 2001). The accuracy of cartographic material and the influence of deviations on estimation reliability of forest resources are not evaluated (Gemmell et al., 1991; Fish, 2000; Franklin, 2001). Compartment edges, occupying in the forests of the country almost one third of the whole area of stands, are important not only from inventory, but also from forest stand growing viewpoint. What are wood increment losses, or what additional increment may be obtained due to differing growth... [to full text]

The theme of Master project of Energetics engineering is actual because in nowadays it is important not only design and functionality of bicycle, but also safety and technological tests of bycicle frame, fork and other part corresponding to international standarts. In Master project was created system for dynamic changing force applying on dynamic pedal and wheel strenght tests. Results of practical pedal pushing research and computations of modelated pedaling system were similar. Analysis of pneumatic cylinder and proportional pressure regulator (using Centaurus Plus modeling program) showed that it is necessary to reduce cylinder working cell volume to enable system to repeat 3 Hz set signals. Using algorithms models was created program for data input, processing and visualizing of testing stand. This program was kindly evaluated by specialists of Technological Test center of Faculty of Technology.

Magistro darbe tiriama brandžių medynų inventorizacijos miškotvarkos metu patikimumas. Darbo objektas – Kazlų Rūdos mokomosios miškų urėdijos valstybinės reikšmės miškų II-IV miškų grupės brandūs medynai. Darbo tikslas – išanalizuoti brandžių medynų inventorizacijos miškotvarkos metu tikslumą ir įvertinti atrankinės miškų inventorizacijos efektyvumą. Darbo metodai – Palyginamoji analizė, atrankos metodas. Darbo rezultatai - Brandžių medynų visuma inventorizuota atrankos metodu. Pagrindinis šio metodo pranašumas – jo objektyvumas, leidžiantis patikimai su žinoma atrankos paklaida įvertinti inventorizuotų medynų vidutinius rodiklius, pirmoje eilėje vidutinį tūrį. Tokiu būdu nustatytas brandžių medynų tūris yra 12 % didesnis už sklypinės inventorizacijos metu nustatytą tūrį, panaudojant taip pat atrankos metodą kiekviename sklype. Brandžių medynų visumos atrankinės inventorizacijos metu nustatytas medžių tūrio kintamumas, leisiantis geriau planuoti tokias inventorizacijas. Didžiausiu vidutinio medžių tūrio kintamumu Kazlų Rūdos miškų urėdijoje pasižymi brandūs pušynai (variacijos koeficientas – 48%). Beržynų ir eglynų tūrio variacijos koeficientas 40-41%, juodalksnynų - 37%. / The work object is Kazlų Rūda forest enterprises, II-IV group mature stands. The main goal of the work was to estimate the reliability of inventory mature stands during standwise inventory. Methods. Comparative analysis and sampling methods were used. The main results Mature stands were inventoried by sampling method. The main advantage of this method - its objectivity, which allow to estimate growing stock volume of mature stands with known error. Estimated mature stands volume of growing stock is 12 % higher than volume inventoried using angle count inventory method for each individual compartment. Estimated variation of growing stock of volume mature stands will allow to calculate other inventories. The highest variation of growing stock volume of mature stands Kazlų Rūda forest enterprise is in pine stands– 48 % medium, in birch and spruce stands 40-41 %, and the least in black alder stands– 37 %.

Objective: Lifting-seat devices are designed to raise the seat height to reduce biomechanical and neuromuscular demands of a sit-to-stand (STS). The goal of this thesis was to understand how seat height and lifting-seat devices with different mechanisms affect trunk, hip, and knee biomechanics and neuromuscular activity of surrounding muscles, and determine whether the effects are altered by age. Four conditions were tested; 1) no device normal seat height (ND-normal), 2) Seat Assist™ (SA), 3) Power Seat™ (PS), 4) no device raised height (ND-raised). Using a cross-sectional design, two objectives were completed. Objective one compared ND-normal and ND-raised to determine the effects of seat height. Objective two compared ND-raised, PS, SA to determine the effects of lifting-seats. Design: 10 healthy older and 10 healthy younger adults performed five trials of each STS condition. Bilateral lower limb and trunk three-dimensional motion, ground reaction forces and electromyography (EMG) from five muscles were collected.

Spausdinimo įrenginys „CITIZEN MD-910“ naudojamas kasos aparatuose, kaip kliento ir kontrolinės juostų spausdintuvas. Šis spausdintuvas plačiai naudojamas šiuose kasos aparatuose: ELCOM EURO-2000M, CASIO FE-800, DATECS MP-500, KONIC SR508F. Šiuos spausdintuvus remontuojant kasos aparatuose, iškyla pavojus, panaikinti kasos aparato atmintį, kurioje saugomi programiniai ir apyvartų duomenys. Spausdinimo įrenginio „CITIZEN MD-910“ patikros stendas kuriamas, tam, kad palengvinti kasos aparatų remonto darbus, taip sumažinant tikimybę panaikinti remontuojamo kasos aparato atmintį. Darbo tikslas – išnagrinėti spausdinimo įrenginio „CITIZEN MD-910“ veikimo principą, elektrines bei mechanines charakteristikas. Taip pat, išsiaiškinti spausdintuvo dvigubos galvos adatų išsidėstymą, sukurti spausdinimo algoritmą, simbolių biblioteką ir valdymo programą. Spausdintuvas „CITIZEN MD-910“ bus dedamas į stendą ir pasiuntus į jį iš valdymo programos tekstą, tikrinamas jo veikimas. Stendas atitiks spausdintuvo realų darbinį režimą. Iš to, kaip vyks spausdinimas, ir iš atspausdinto teksto ant popieriaus juostos, bus sprendžiama apie spausdintuvo mechaninius ir elektronikos gedimus, adatų veikimą ir jų mušimo jėgą į popierių, bei tinkamumą tolesnei eksploatacijai. Spausdinimo įrenginio „CITIZEN MD-910“ patikros stendo pagrindinė kūrimo priežastis yra ta, jog nėra sukurtų panašių analogų, kurie palengvintų šių kasos aparatų spausdinimo įrenginių remonto darbus. / Dot impact printer mechanism “CITIZEN MD-910” is used in cash registers as a printer for customer receipts and journal paper ribbons. This printer is widely used in the cash registers such as ELCOM EURO-2000M, CASIO FE-800, DATECS MP-500, KONIC SR508F. Repairing these printers inside the cash registers there is a risk to delete the cash register’s memory in which programs and data of a turnover is stored. The dot impact printer mechanism “CITIZEN MD-910” test stand is being worked out to make the cash registers repairing easier and in this way to reduce the risk of deleting cash registers memory. The printer “CITIZEN MD-910” will be placed in the test stand and its work will be tested by sending text from the operating program into it. The stand will simulate real working conditions of the printer. Analyzing the printing process and the printed text on the paper ribbon it will be possible to decide on printer’s mechanical and electrical damage, work of wires and force they dot the paper, also, further usability. There are no similar analogues which could make the repairing of the cash registers dot impact printer mechanism “CITIZEN MD-910” easier and this is the main reason to work out the dot impact printer mechanism “CITIZEN MD-910” test stand.

No description available.

No description available.

Seed-placed phosphorus (P) and sulphur (S) fertilizers can reduce canola plant stands. Field studies were conducted to determine the effect of various sources and rates of seed-placed P and S fertilizers on canola plant stand, early season biomass accumulation and seed yield. Conventional granular P and S blends increased the risk of seedling damage, but increased the frequency of yield response. Liquid fertilizers were similar in seedling damage but generally less effective in increasing seed yield compared to granular fertilizers. Novel fertilizers were more seed-safe but less reliable than conventional sources in increasing seed yield. A growth room experiment was conducted to determine the effect of soils from different landscape positions on the toxicity of seed-placed ammonium sulphate (AS) and monoammonium phosphate (MAP). Canola emergence was reduced and delayed by seed-placed MAP and AS. Ammonium sulphate in particular has a high risk of NH3 toxicity on calcareous hilltop soils