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A 3D graphics system usually consists of two major subsystems: geometry subsystem and rendering subsystem. The geometry subsystem performs transformation, lighting, backface culling, and clipping. The clipping is to remove the part of a triangle that is outside of the view volume by calculating the intersections of the triangle edges with view planes. The clipping operation turns out to be a time-consuming procedure in the geometry subsystem. In this thesis, we present several clipping algorithms and their hardware implementations, and compare the performance in the geometry subsystem. Furthermore, a new pre-clipping algorithm is also proposed to reduce the number of triangles that need to go through the clipping operations in order to reduce the burden of clipping operations in the whole geometry subsystem. The whole geometry system including the pre-clipping and clipping hardware is verified in a complete 3G graphics system in the Versatile FPGA demonstration board.

"Pasture is the natural food of all domesticated herbivore, especially the ruminant, and the only single feed upon which it can be maintained in health indefinitely."

No description available.

Τα γραφικά στην σημερινή κοινωνία της «Πληροφορίας» παίζουν σημαντικό ρόλο και είναι από τους τομείς που δαπανούνται υπέρογκα ποσά για τη βελτίωση τους. Για να καταλάβουμε τη σημαντικότητα του ρόλου τους αρκεί να αναφέρουμε τους τομείς στους οποίους βρίσκουν εφαρμογή: -Αλληλεπίδραση με το χρήστη -Σχεδιασμός στις επιχειρήσεις, στην επιστήμη και στην τεχνολογία -Αυτοματισμοί γραφείου και ηλεκτρονικές εκδόσεις -Ο υπολογιστής σαν βοήθημα στη σχεδίαση -Εξομοίωση και “animation” για επιστημονικές απεικονίσεις και διασκέδαση -Τέχνη και εμπόριο -Διεξαγωγή ελέγχου -Βοήθημα για εκμάθηση -Χαρτογραφία -Διασκέδαση Ένα από τα στάδια λειτουργίας μιας μηχανής παραγωγής 3D γραφικών, το Rendering, που είναι ένα από τα πιο απαιτητικά σε ισχύ στάδια της, μπορεί και γεμίζει με χρώμα κάθε Pixel της οθόνης ανάλογα με τη 3D εικόνα που θέλουμε να παρουσιάσουμε στην οθόνη του υπολογιστή. Το στάδιο αυτό απαιτεί εκατοντάδες χιλιάδες υπολογισμούς και προσπελάσεις μνήμης το δευτερόλεπτο -για rendering πραγματικού χρόνου- συνεπώς απαιτεί σημαντική ποσότητα ισχύος. Η εφαρμογή της παραγωγής γραφικών 3D σε συσκευές που απαιτούν χαμηλή κατανάλωση ισχύος, όπως PDA, κινητά τηλέφωνα και άλλες φορητές συσκευές, έχει δημιουργήσει την ανάγκη για μείωση της κατανάλωσης ισχύος. Το Clipping αποτελεί ένα από τα πέντε στάδια του Geometry Stage για την παραγωγή γραφικών. Το στάδιο αυτό το εφαρμόζεται για να καθοριστεί το μέρος της εικόνας το οποίο θα είναι ορατό μέσα σε μια δεδομένη περιοχή -το ορατό παράθυρο- γνωστή και ως viewing frustum ή viewport και να αποκοπούν εκείνα τα αντικείμενα που βρίσκονται έξω από αυτή. Αυτό που επιτυγχάνεται επομένως είναι να γίνεται rasterization μόνο στην ορατή περιοχή και αυτό είναι το βασικό πλεονέκτημα της χρήσης του Clipping. Επιτυγχάνεται καλύτερη απόδοση καθώς το στάδιο του rasterization είναι ιδιαίτερα απαιτητικό και μέσω του clipping βοηθάμε στην μείωση των αντικειμένων που θα απεικονισθούν άρα και στους μελλοντικούς υπολογισμούς και στην κατανάλωση ενέργειας. Ο αλγόριθμος N-L-N είναι ένας από τους βασικούς αλγορίθμους που χρησιμοποιούνται ευρέως στον τομέα των 2D γραφικών καθώς αποφεύγει τις εξωτερικές τομές (τομές μεταξύ του ΑΒ και των προεκτάσεων των πλευρών του παραθύρου) διαιρώντας το χώρο σε περισσότερες από τον C-S (Cohen-Sutherland) περιοχές, έχει τις λιγότερες διαιρέσεις και τις λιγότερες συγκρίσεις (1/3 από τον C-S και 1/2 από τον L-B (Liang-Barsky) [2] ) άρα είναι ο πιο ταχύς και αποδοτικός και συνεπώς ο πιο επιθυμητός σε 2D περιβάλλοντα. Όμως πολύ μικρό ποσοστό των γραμμών υπόκεινται Clipping -μόλις το 6% κατά μέσο όρο [1]- έτσι για τη βελτίωση του αλγορίθμου επικεντρωθήκαμε στα προηγούμενα στάδια (μέχρι την απόφαση να κάνουμε Clip).Πιο συγκεκριμένα στο [1] υποστηρίζεται ότι τα 8/9 των γραμμών αυτών υπόκεινται “Reject” αφού είναι εξ’ολοκλήρου εκτός του ορατού παραθύρου και μόνο το 1/9 “Accept” ή “Clip”. Για το λόγο αυτό δημιουργήθηκε ο QuickClip, ένας αλγόριθμος που στοχεύει στο πολύ γρήγορο reject ενός μεγάλου αριθμού γραμμών, όχι όμως όλων όσων πρέπει να υποστούν reject. Σκοπός λοιπόν του προτεινόμενου αλγορίθμου είναι να επιτευχθεί “Full Reject” (δηλαδή απόρριψη όλων των γραμμών που δεν είναι εξ’ ολοκλήρου ορατές) με όσο το δυνατόν λιγότερες πράξεις. Ο Quick Clip στη χειρότερη περίπτωση, μπορεί να κάνει έως και 3 άσκοπα Clipping, πριν αποφασίσει να αποκλείσει τη γραμμή. Αυτές οι άσκοπες πράξεις είναι κάτι ανεπιθύμητο, που προσπαθήσαμε να ελαχιστοποιήσουμε στον αλγόριθμό μας. Η οπτική γωνία από την οποία ο N-L-N αλγόριθμος αντιμετωπίζει το Clipping και o μηχανισμός των κλίσεων που χρησιμοποιεί μας βοήθησε στην δική μας υλοποίηση. Αφού μελετήσαμε και κατανοήσαμε την οπτική γωνία και τον τρόπο σκέψης των αλγορίθμων των οποίων η χρήση έχει επικρατήσει στη διαδικασία του Polygon και Line Clipping, διαπιστώσαμε ότι οι περισσότεροι έχουν διαφορετικές φιλοσοφίες και παρουσιάζουν μειονεκτήματα και πλεονεκτήματα. Το αποτέλεσμα ήταν η προσπάθεια σχεδίασης ενός αλγορίθμου, που εκμεταλλεύεται τα θετικά στοιχεία, προσπαθώντας παράλληλα να λύσει τα αρνητικά. Σύμφωνα με τις μετρήσεις της υπολογιστικής πολυπλοκότητας παρατηρούμε ότι κάνει λιγότερες πράξεις κυρίως στις περιπτώσεις απόρριψης των γραμμών (¨Full Reject¨), αλλά και αποδοχής (¨Full Accept¨) από τους κυρίαρχους αλγορίθμους. Επίσης σε συνολικό επίπεδο, ακόμα και στην χειρότερη περίπτωση (¨Worst case¨) όπου απαιτούνται οι περισσότερες πράξεις είναι ανταγωνιστικός με τους αλγόριθμους N-L-N και Quickclip. Σε συνδυασμό με τις μετρήσεις που έχουν προηγηθεί μεταξύ των αλγορίθμων που έχουν επικρατήσει ως τώρα στο Clipping ([1],[2],[3],[4],[5],[7]) μπορούμε να ισχυριστούμε ότι ο προτεινόμενος είναι ένας αλγόριθμος που θα είναι αποδοτικός λόγω των λιγότερων πράξεων του σε Low Power κατασκευές. Συμπερασματικά λοιπόν αναφέρουμε ότι συγκριτικά με τους αλγορίθμους N-L-N και Quickclip μειώθηκαν οι απαραίτητοι υπολογισμοί και ειδικά στην περίπτωση των εξ’ολοκλήρου απορρίψεων (“Full Reject”) όπου δόθηκε ιδιαίτερη έμφαση. Αυτό προήλθε από την παρατήρηση ότι τα 8/9 των γραμμών υπόκεινται “Reject” αφού είναι εξ’ολοκλήρου εκτός του ορατού παραθύρου και μόνο το 1/9 “Accept” ή “Clip”. Έτσι η πολυπλοκότητα της διαδικασίας αυτής μειώνεται, κάτι χρήσιμο σε αυτό το πρώιμο στάδιο των γραφικών. Ο προτεινόμενος αλγόριθμός μπορεί να φανεί χρήσιμος σε συσκευές που έχουν ανάγκη από χαμηλή κατανάλωση ενέργειας και μικρή επιφάνεια. Ο σχεδιασμός του αλγορίθμου έχει γίνει για δισδιάστατο περιβάλλον (2D), χωρίς όμως να αποκλείεται και τρισδιάστατη (3D) επέκτασή του. Με την κατάλληλη Low power και Low area υλοποίηση σε VLSI θα δώσει ένα αποτέλεσμα χαμηλής κατανάλωσης ενέργειας αλλά και μικρής επιφάνειας, στοιχεία που είναι καίρια για mobile συσκευές. Οι αλγόριθμοι του point clipping υλοποιήθηκαν σε γλώσσα προγραμματισμού C με την προσθήκη μιας εφαρμογής που αναπαριστά γραφικά τις γραμμές πριν και μετά το στάδιο του clipping. Κατόπιν έγινε καταγραφή σε VHDL μιας ενδεικτικής αρχιτεκτονικής του προτεινόμενου αλγορίθμου ώστε να δειχθεί ότι είναι υλοποιήσιμος σε VLSI. / Graphics in the society of "Information" play an important role, as they are one of the sectors where great sums of money are consumed for their improvement. In order to understand the importance of their role it is enough to mention the sectors in which they are applied: - Interaction with the user - Planning in enterprises, science and technology - Office automations and electronic publications - The computer as an aid in designing - Simulation and "animation" for scientific representations and entertainment - Art and trade - Conduct of control - Aid in learning - Cartography - Entertainment One of the stages of a 3D graphics production machine, Rendering, which is one of the most demanding in power, fills with color each Pixel of the screen depending on the 3D picture that we want to present in the screen of the computer. This stage requires hundreds of thousands calculations and memory accesses per second - for real time rendering -, so it requires an important quantity of power. The implementation of 3D graphics production at devices that require low consumption of power, as PDAs, mobile phones and other portable devices, has created the need of reducing the power consumption. The Clipping stage is one of the five stages of Geometry Stage in the graphics production. This stage is applied in order to determine the part of the picture that will be visible in a given region - called the visible window -also known as viewing frustum or viewport and cut away those objects that are detected outside this region. Consequently what is achieved is applying rasterization only in the visible region which is the main advantage of using Clipping. Better performance is achieved as the rasterization stage is too demanding and clipping helps the reduction of objects that will be drawn, hence the reduction of the future calculations and the consumption of energy. Algorithm N-L-N is one of the basic algorithms that are used widely in the section of 2D graphics as it avoids the exterior traces (traces between the AB line segment and the extensions of the sides of the window) dividing the space in more regions than the C-S (Cohen-Sutherland), it has the less divisions and less comparisons (1/3 of C-S and 1/2 of the L-B (Liang-Barsky) [ 2 ]) hence is quicker and more efficient so consequently the most desirable in 2D environments. However a very small percentage of lines is being Clipped - just the 6% in average [ 1 ] - so for the improvement of the algorithm we are focused in the previous stages (up to the decision of making Clipping). Specifically in [ 1 ] is mentioned that the 8/9 of this lines are being "Rejected" as being wholly outside the visible window and only the 1/9 are being "Accepted" or "Clipped". For this reason the QuickClip algorithm was created, a algorithm that aims in the very fast rejection of a large amount of lines, no however all of which should go through rejection. Aim of the proposed algorithm is to achieve "Full Reject" (that is to say reject of all lines that is not entirely visible) with as less operations as possible. The QuickClip algorithm at the worst case, will make up to 3 unnecessary Clippings, before deciding to exclude the line. These pointless operations are undesirable, that we tried to minimize in the proposed algorithm. The way which the N-L-N algorithm faces Clipping and the mechanism of slopes that it uses helped us in our implementation. After we studied and comprehended the ideas and the ways of the algorithms of which the use has dominated in the process of Polygon and Line Clipping, we realized that most have different philosophies and have disadvantages and advantages. The result was the effort of designing an algorithm that takes advantage of the positive elements, trying at the same time to reduce the negatives. According to the measurements of calculating complexity we observe that it mainly makes less operations in the cases of rejecting lines (¨Full Reject¨), but also acceptance (¨Full Accept¨) from the dominant algorithms. Also in a overall level, even in the worst case (¨Worst case¨) where the most operations are required is competitive with the algorithms N-L-N and QuickClip. In combination with the measurements that have preceded between the algorithms that have dominated until now in Clipping ([1], [2], [3], [4], [5], [7 ]) we can claim that the proposed algorithm will be efficient in Low Power devices because of the less operations. Deductively therefore we report that comparatively with the algorithms N-L-N and QuickClip the necessary calculations were decreased and specifically in the case of wholly rejected lines ("Full Reject") where proper emphasis was given. This came from the observation that the 8/9 of lines that go through "Reject" while they are wholly outside the visible window and only the 1/9 go through "Accept" or "Clip". Thus the complexity of this process is decreased, something useful in this early stage of graphics' pipeline. The proposed algorithm can be useful in devices that have the need of low consumption of energy and small surface. The planning of the algorithm has become for two-dimensions environment (2D), without however excluding the three-dimensions (3D) extension. With the suitable Low power and Low area implementation in VLSI it will give a result of low consumption of energy but also small surface, elements that are vital for mobile devices. The algorithms of point clipping were written in C Code with the addition of an application that represent graphically the lines before and afterwards the stage of clipping. Then a suggestive architecture of the proposed algorithm was designed in VHDL so as to show that it can be implemented in VLSI.

This dissertation presents four technical contributions in the theory and practice of low-density parity-check (LDPC) codes and orthogonal frequency division multiplexing (OFDM) systems withtransmission non-linearity and with interference due to high mobility.We first explore the universality of LDPC codes for the binary erasure channel (BEC), the AWGN channel, and the flat Rayleigh fading channel. Using excess mutual information as a performance measure, we demonstrate that an LDPC code designed on a singlechannel can be universally good across the three channels. Thus, a channel for which LDPC code design is simple may be used as a surrogate for channels that are more challenging.Due to fast channel variations, OFDM systems suffer from inter-carrier interference (ICI) in frequency-selective fast fading channels. We propose a novel iterative receiver design that achieves near-optimal performance while maintaining a complexity that grows only linearly with the number of OFDM carriers. Weprove that the matched filter bound for such a channel is also the maximum-likelihood sequence detection (MLSD) bound.Because of the presence of high peaks at OFDM modulator output, amplitude clipping due to amplifier saturation causes performance degradation. We show that existing analyses underestimate the capacity of OFDM systems with clipping, and we analyze thecapacity of clipped OFDM systems with AWGN and frequency-selective Rayleigh fading. We prove that for frequency-selective Rayleigh fading channels, under certain conditions, there exists an SNR threshold, above which the capacity of a clipped system is higherthan that of an unclipped system. We provide upper and lower bounds on the channel capacity and closed-form approximations of discrete-input capacities with and without clipping.We also derive tight MLSD lower bounds and propose near-optimal receivers for OFDM systems with clipping. We show that over frequency-selective Rayleigh fading channels, under certain conditions, a clipped system with MLSD can achieve better performance than an unclipped system. We show that the MLSD boundscan be achieved or closely approached by the proposed low complexity receivers in various channel types.

Toe trimming within the turkey industry has been used for over four decades as a method for controlling carcass scratching, and by doing so, achieving better grades and lower condemnation rates. The industry has changed greatly since the 1970’s, when the majority of the research on the procedure was completed. The technology used for toe trimming has switched from a hot-blade to the use of microwave energy, which will effect healing and toe length trimmed. The birds are larger now, which will impact mobility both before and after trimming, and in a consumer-driven trend, the industry is re-examining its codes of practice to ensure the highest level of welfare possible. As there is little pertinent research regarding these changes, the toe trimming procedure was re-examined under modern conditions and with focus on both production and welfare effects to determine if the practice can still be recommended. Hybrid Converter toms were raised to 140 d of age, with half (153) being toe trimmed at the hatchery using a Microwave Claw Processor (MCP) and the other half (153) left with their toes intact. The birds had feed consumption, body weight, mortality, toe length, stance, behaviour, and gait scores monitored throughout the trial with carcass damage assessed at processing. Means were considered significantly different when P≤0.05. Toe trimming caused a reduction in both feed consumption and body weight in the later stages of the experiment. Final weights for non-toe trimmed and toe trimmed toms were 21.70 kgs and 21.15 kgs, respectively. Feed efficiency with and without being corrected for mortality was unaffected by the procedure. Overall mortality and mortality by age group were also unaffected; however it was found that toe trimmed toms experienced higher levels of rotated tibia at 3.27% versus 0.65% for untrimmed birds. Toe length measurements found that trimmed toes were, on average, 91.9% the length of an intact toe, and that variability in length increased with trimming. The procedure was not found to impact stance or gait score, although behaviour at all ages measured demonstrated reduced mobility with trimming. In particular, reduced activity in poults for 5 d post-treatment indicates that the MCP treatment caused pain or discomfort. The percentage of carcasses which exhibited scratching was 15.6% for the non-trimmed treatment and 13.3% for the trimmed, which were not significantly different. Also, no significant effect of trimming was found for any other carcass damage category. Based on the negative impacts of toe trimming on both bird production and welfare found in this research, MCP treatment should not be recommended to turkey producers when raising heavy toms.

Lantmäteriet is developing an application that can show a three-dimensional representation of Sweden based on the data that Lantmäteriet has. The purpose of this application is to be able to crowdsource improvements and changes to the map data that Lantmäteriet has, it will also be able to be used to improve a case's information for easier and faster turnaround at Lantmäteriet. In this Project, I examine how best to use this map data to generate nature such as vegetation in this application to improve usability, and make it easier for the user to know where they are in the application. During the process, I designed a nature generator that uses polygon triangulation to better generate nature.

This study was conducted to provide insight into the response of Achyranthes japonica to management tools in the form of complete shoot removal (clipping) and herbicide application at Cypress Creek National Wildlife Refuge (CCNWR) in southern Illinois. Field herbicide experiments indicate that A. japonica is susceptible to foliar applications of systemic, broad leaf herbicides. The removal of A. japonica by herbicide, however, did not allow for re-establishment of the surrounding plant community in years 2011 and 2012. Seedlings at node stage 3, 4 and 6 were able to regrow following complete shoot removal indicating that this species can sustain perennial growth when it develops three nodes and that the node stage at which plants were clipped did not affect their regrowth potential. In the greenhouse, A. japonica was able to regrow following complete shoot removal at the 3 node stage and the number of branches and apical nodes on a plant are the best predictors of the regrowth potential for this species. Achyranthes japonica's susceptibility to foliar applications of systemic herbicides in the greenhouse was high. Herbicide titration results indicate that of the six herbicides tested (2,4-D ester, triclopyr, glyphosate, aminopyralid, triclopyr+fluroxypyr, and aminopyralid+metsulfuron) triclopyr required the least amount of active ingredient to reduce the growth of A. japonica by 50% (GR-50). Results overall suggest that A. japonica reaches perennial growth by the time it has three nodes, making clipping as a management tool only successful if done before plants have developed three nodes. Achyranthes japonica perennial plants are highly susceptible to foliar applications of broad leaf systemic herbicides making them a good management tool in the field.

The purpose of the current study is to evaluate a procedure that can be used to introduce horses to clipping. Negative reinforcement was used in a shaping paradigm. Shaping steps were conducted by the handler, starting with touching the horse with the hand, then touching the horse with the clippers while they are off, culminating with touching the horse with the clippers while they are on. When a horse broke contact with either the hand or the clippers, the hand or the clippers were held at that point until the horse emitted an appropriate response. When the horse emitted an appropriate response, the clippers were removed, and the handler stepped away from the horse. For all eight horses, this shaping plan was effective in enabling the clipping of each horse with minimal inappropriate behavior and without additional restraint. The entire process took under an hour for each horse.