Performance Evaluation of Different PV-Array Configurations under Weak Light Conditions and Partial Shadings

The paper analyses empirical performance data of five commercial PV-plants in Germany. The purpose was on one side to investigate the weak light performance of the different PV-modules used. On the other hand it was to quantify and compare the shading losses of different PV-array configurations. The importance of this study relies on the fact that even if the behavior under weak light conditions or the shading losses might seem to be a relatively small percentage of the total yearly output; in projects where a performance guarantee is given, these variation can make the difference between meeting or not the conditions.When analyzing the data, a high dispersion was found. To reduce the optical losses and spectral effects, a series of data filters were applied based on the angle of incidence and absolute Air Mass. To compensate for the temperature effects and translate the values to STC (25°C), five different methods were assessed. At the end, the Procedure 2 of IEC 60891 was selected due to its relative simplicity, usage of mostly standard parameters found in datasheets, good accuracy even with missing values, and its potential to improve the results when the complete set of inputs is available.After analyzing the data, the weak light performance of the modules did not show a clear superiority of a certain technology or technology group over the others. Moreover, the uncertainties in the measurements restrictive the conclusiveness of the results.In the partial shading analysis, the landscape mounting of mc-Si PV-modules in free-field showed a significantly better performance than the portrait one. The cross-table string using CIGS modules did not proved the benefits expected and performed actually poorer than a regular one-string-per-table layout. Parallel substrings with CdTe showed a proper functioning and relatively low losses. Among the two product generations of CdTe analyzed, none showed a significantly better performance under partial shadings.

Hand Gesture Detection & Recognition System

The project introduces an application using computer vision for Hand gesture recognition. A camera records a live video stream, from which a snapshot is taken with the help of interface. The system is trained for each type of count hand gestures (one, two, three, four, and five) at least once. After that a test gesture is given to it and the system tries to recognize it.A research was carried out on a number of algorithms that could best differentiate a hand gesture. It was found that the diagonal sum algorithm gave the highest accuracy rate. In the preprocessing phase, a self-developed algorithm removes the background of each training gesture. After that the image is converted into a binary image and the sums of all diagonal elements of the picture are taken. This sum helps us in differentiating and classifying different hand gestures.Previous systems have used data gloves or markers for input in the system. I have no such constraints for using the system. The user can give hand gestures in view of the camera naturally. A completely robust hand gesture recognition system is still under heavy research and development; the implemented system serves as an extendible foundation for future work.

Solar position diagram

Program SOLVEJ är ett användarvänligt program som visar solens vandring över himlavalvet vid upp till fem valfria datum och vid valfri ort. Programmet är utvecklat av två skäl. För det första, att demonstreras för en intresserad allmänhet som del av vandringsutställning om solenergi, vilken är initierad och utarbetad av SERC. För det andra, att användas av solenerglintressenter för att snabbt få en uppfattning om solinstrålningen på en ort vid olika tidpunkter på året.Indata till programmet ges från tangentbordet. Som svar på frågor skrivs för vilken ort diagrammet skall gälla, max fem datum, ortens latitud och longitud, som anges positiv i västlig riktning, samt tidszonen. Varje uppgift avslutas med tryck på tangenten ENTER. Programmet kommer nu att rita ett koordinatsystem på skärmen. Första axeln visar vädersträcken, norr, öster, söder, väster och norr, varje delstreck utgör 10 grader. För södra halvklotet byter norr och söder plats. Andra axeln visar höjden över horisonten i grader, 0 till 90 grader och 10 grader för varje delstreck. Efter några sekunder ritas diagrammet upp med solhöjden som funktion av väderstrecket och varje hel timme markerad. Se fig. 1-4. Slutligen frågas efter om diagrammet skall ritas ut på printer. SOLVEJ avbrytes med att trycka CTRL+BREAK.SOLVEJ är skrivet i Quick-BASIC (se App. 1) och leveras både som källkod och körklar version. Lämplig dator är IBM-kompatibel AT med EGA- eller VGA-skärmkort (ej Herkules Lämplig printer är IBM Proprinter eller liknande matrisskrivare, kopplad till LPT1 på kommunikationskortet.Till grund för beräkningarna har använts artikeln On Calculating the Position of the Sun, publicerad i nr. 1 1988 av The International Journal of Ambient Energy. Fem empiriska ekvationer beträffande beräkningar av solens position har studerats för att undersöka deras tillförlitlighet. Felaktigheter på fem grader eller mer kan uppträda om man använder sig av de enkla ekvationer som kan hittas solenergi-böcker och som inte kräver tillgång till dator. FORTRAN-rutinen SUNAE2 (se App. 2) beräknar solpositionen med noggrannast kända metod. Program SOLVEJ är en utveckling av SUNAE2.

Kuvad och jämlik på planeten Vinter : Le Guins feministiska science fiction-roman The Left Hand of Darkness ur Foucaults maktperspektiv

Studien är en applicering av Foucaults Övervakning och straff på science fiction-romanen The Left Hand of Darkness av Le Guin. Fokus låg på hur makten drabbar huvudkaraktärerna; syftet var att notera hur de gör motstånd mot maktutövningen och att ta fasta på alternativa maktrelationer som kan influera verkligt politiskt arbete mot en bättre, mer jämlik värld. Att använda Foucaults idéer på liknande sätt är vanligt. Analysen består av sex sekvenser som utspelar sig på planeten Vinter i The Left Hand of Darkness. Landsförvisningar för att återupprätta härskarens makt, både avsaknaden och upprättandet av framstegsmyt och en etik som förespråkar jämlikhet utmärkte monarkin Karhide; kuvade kroppar i disciplinens förtecken och en makt som är sammantvinnad med vetandet kännetecknade byråkratin Orgoreyn. Slutsats: Det är nödvändigt att uppoffra sig för att få till stånd förändringar. Den politiske visionären kan dessutom ha användning för en särskild etik, en mindre aggressiv framstegsmyt och horisontellt samarbete.

Vägar till en halverad energianvändning i Dalarnas småhusbebyggelse

Denna rapport är en svensk sammanfattning av licentiatavhandlingen med titeln "Simple Question, Complex Answer. Pathways towards a 50% Decrease in Building Energy Use", som publicerades vid Uppsala Universitet i februari 2014. I denna rapport har jag samman-ställt det som jag anser vara de viktigaste resultaten ur ett länsperspektiv och rapporten riktar sig därför i första hand mot aktörer inom byggnadssektorn i Dalarna. Mer omfattande bild-material, diagram, tabeller och hänvisningar till källmaterial återfinns för den intresserade i licentiatavhandlingen. Min förhoppning är att denna sammanfattning kan ligga till grund för diskussioner och beslut om framtiden för Dalarnas småhusbestånd.

COMPARISON OF PARTIAL SHADING LOSSES IN FREE FIELD PV-PLANTS WITH DIFFERENT ARRAY CONFIGURATIONS

A common problem when planning large free field PV-plants is optimizing the ground occupation ratio while maintaining low shading losses. Due to the complexity of this task, several PV-plants have been built using various configurations. In order to compare the shading losses of different PV technologies and array designs, empirical performance data of five free field PV-plants operating in Germany was analyzed. The data collected comprised 140 winter days from October 2011 until March 2012. The relative shading losses were estimated by comparing the energy output of selected arrays in the front rows (shading-free) against that of shaded arrays in the back rows of the same plant. The results showed that landscape mounting with mc-Si PV-modules yielded significantly better results than portrait one. With CIGS modules, making cross-table strings using the lower modules was not beneficial as expected and had more losses than a one-string-per-table layout. Parallel substrings with CdTe showed relatively low losses. Among the two CdTe products analyzed, none showed a significantly better performance.

Differences in muscle activity during hand dexterity tasks between women with arthritis and a healthy reference group

Background. Impaired hand function is common in patients with arthritis and it affects performance of daily activities; thus, hand exercises are recommended. There is little information on the extent to which the disease affects activation of the flexor and extensor muscles during these hand-dexterity tasks. The purpose of this study was to compare muscle activation during such tasks in subjects with arthritis and in a healthy reference group. Methods. Muscle activation was measured in m. extensor digitorium communis (EDC) and in m. flexor carpi radialis (FCR) with surface electromyography (EMG) in women with rheumatoid arthritis (RA, n = 20), hand osteoarthritis (HOA, n = 16) and in a healthy reference group (n = 20) during the performance of four daily activity tasks and four hand exercises. Maximal voluntary isometric contraction (MVIC) was measured to enable intermuscular comparisons, and muscle activation is presented as %MVIC. Results. The arthritis group used a higher %MVIC than the reference group in both FCR and EDC when cutting with a pair of scissors, pulling up a zipper and—for the EDC—also when writing with a pen and using a key (p < 0.02). The exercise “rolling dough with flat hands” required the lowest %MVIC and may be less effective in improving muscle strength. Conclusions. Women with arthritis tend to use higher levels of muscle activation in daily tasks than healthy women, and wrist extensors and flexors appear to be equally affected. It is important that hand training programs reflect real-life situations and focus also on extensor strength.

The hand of God is over their hands (Q. 48:10) : on the notion of covenant in al-Ṭabarī’s account of Karbalāʾ

This article is an analysis of the story of the killing of Ḥusayn b. ʿAlī at Karbalāʾ in 61/680, as it is presented by Abū Jaʿfar Muḥammad b. Jarīr al-Ṭabarī (d. 310/923). The main argument is that the notion of the divine covenant, which permeates the Qur’an, constitutes a framework through which al-Ṭabarī views this event. The Qur’anic idea of the covenant is read in structural/thematic continuity with the Hebrew Bible account of the covenant between Yahweh and the Hebrew people, which has, in turn, been traced back in its basic form to Late Bronze Era treaties between rulers and their vassals.   The present study focusses on four speeches ascribed to Ḥusayn during the encounter he and his group had with the vanguard of the Kūfan army led by al-Ḥurr. These are analysed in accordance with their use of Qur’anic covenant vocabulary. They are also categorised within the broader framework of the eight standard characteristics of Ancient West Asian and Biblical covenants, as presented by George Mendenhall and Gary Herion, which have recently been developed in a Qur’anic context by Rosalind Ward Gwynne. This article argues that al-Ṭabarī’s Karbalāʾ narrative presents the pact of loyalty to Ḥusayn as a clear extension of the divine covenant.