Friction factor data are important for better prediction of leakage and rotordynamic coefficients of gas annular seals. A flat-plate test rig is used to determine friction factor of hole-pattern/honeycomb flat-plate surfaces representing annular seals. Three flat-plates, having a hole-pattern with hole diameter of 12.15 mm and hole depths of 0.9 mm, 1.9 mm, and 2.9 mm, are tested with air as the working medium. Air flow is produced between two surfaces, one having the hole-pattern roughness representing the hole-pattern seal and the other smooth, at the following three clearances of 0.254, 0.381, and 0.635 mm and three inlet pressures of 56, 70, and 84 bar with all possible pressure ratios at each configuration. The friction factor data are presented for all tested configurations, with description of the test rig and theory behind the calculations. The effect of hole diameter, hole depth, clearance, Reynolds number, and inlet pressure are analyzed, and friction factor models based on these parameters are calculated. Friction factor upset (an undesirable phenomenon making the test data non repeatable) is also explained. Dynamic pressure data are presented, measured from dynamic pressure probes located at both the hole-pattern plate and the smooth plates at different locations.

Abstract This study concludes the position feedback from discussing about the trend of the evolution of flat panel display ¡]FPD¡^technology by using the path dependence theory. Based on this theory, the research on the valuation curve of application forms the model of valuable development. Therefore, the position feedback of FPD technology is established according to the system dynamic theory. The key factors of position feedback are defined as below: ¡]1¡^The ages of digital TV, ¡]2¡^Light¡Bthin¡Bshort¡Bsmall¡Brapid ¡]3¡^ Good quality of CRT¡]4¡^Low cost¡]5¡^Market scale¡K etc.. It explains the character of every key factor of path dependence for FPD. In accordance with the application of valuation curve, FPD is classified into six types¡GLCD¡BPDP¡BLCOS¡BDLP¡BFED and OLED. The classification is also based on JPRI(Japan picture research institute) standard¡G ¡]1¡^the way of luminescence¡]2¡^ the size of screen¡]3¡^ the outward appearance¡]4¡^ weight¡]5¡^ Brightness¡]6¡^ Contrast Ratio¡]7¡^ View Angle¡]8¡^ Resolution¡]9¡^ response time¡]10¡^ consume power¡]11¡^ life time¡]12¡^ flexibility¡]13¡^ product application scope etc. Use the weighted index method to calculate the sum of valuation for six types of FPD technology. Drawing a valuation curve by weighted index¡]Y axis¡^ and time table(X axis). The conclusions of this study are as follows: 1. FPD technology has the obvious tendency of the path dependence. 2. By the path dependence theory, the technology of FED and OLED have potential for replacing the LCD-TFT technology. The conclusions above are significant to the management in the following prospects. 1.The mode of position feedback of high technology industry will have many references for the developmental path of industry. 2.Based on Taiwan¡¦s photo-electric industry, it is necessary to penetrate the tendency of Japan¡¦s research in order to promote the FPD industry in Taiwan. Key word¡Gpath dependence¡Bsystem dynamic theory¡Bflat panel display

There are various value-influencing factors that have various effects on the value of a cooperative flat for buyers. What generates value is individual and different from buyer to buyer, but also between buyers and real-estate agents. Consequently, the real-estate agents who perform valuations can make incorrect estimates of a residential value. Therefore, it is important to examine which factors are important for buyers to prevent incorrect valuations. To find out which these factors are and which of them that are the most important for potential buyers, previous research has been done in larger cities in both Sweden and other countries. However, no previous research on how much impact these factors have on a cooperative flats value in smaller towns in Sweden has been done. Smaller towns are important parts of the real estate market. Research based on smaller towns could be analyzed together with research performed in larger cities. This would, regardless of if there are differences between larger or smaller cities or not, lead to more correct valuations by real-estate agents. This paper examines which factors that are most important for buyers in the purchase of cooperative flats in smaller towns. This research can be seen as a complement to previous research about valuation and value-influencing factors. A quantitative method was used with certain qualitative elements. The qualitative element consisted of an interview with a real-estate agent and the quantitative part was then based on the results of that interview in the form of a survey. The survey was conducted in two smaller towns, Ludvika and Kristinehamn, where 75 respondents participated in each city. The result was determined by examination of the average value of every value-influencing factor. An analysis of the results was performed with help of the theory. The theory mainly consists of a description of the real-estate market and various value-influencing factors such as the number of square meters. The conclusions drawn by the study was that monthly fee (rent), the tenantowners´ association's finances, the purchase price, balcony/patio, parking spot and a well-planned layout were important factors among the respondents. When these factors are the ones buyers value the most, they also increase buyers’ willingness to pay. Consequently, when evaluating cooperative flats, a higher price could be estimated if the described factors were met. / Det finns olika värdepåverkande faktorer som har olika stor påverkan på en bostadsrätts värde för köpare. Vad som genererar värde är individuellt och kan skilja sig mellan olika köpare men också mellan köpare och fastighetsmäklare. Av den anledningen kan fastighetsmäklare som i sitt yrke utför värderingar göra felaktiga uppskattningar av en bostads värde. Därför är det viktigt att undersöka vilka faktorer som för köpare är de viktigaste för att undvika att felaktiga värderingar utförs. För att ta reda på vilka dessa är och vilka av dem som är viktigast har tidigare forskning genomförts i större städer i både Sverige och andra länder. Det saknas dock tidigare forskning om dessa faktorer och hur stor påverkan de har på en bostadsrätts värde i småstäder i Sverige. Småstäder utgör en viktig del av fastighetsmarknaden. Forskning som utförts i småstäder skulle kunna sammanläsas med övrig forskning från större städer. Detta skulle oavsett om det finns skillnader mellan större och mindre städer eller ej leda till att mer korrekta värderingar skulle kunna utföras av fastighetsmäklare. Den här uppsatsen undersöker vilka faktorer som är viktigast för köpare vid köp av bostadsrätter i småstäder. Forskningen kan ses som ett komplement till tidigare forskning inom fastighetsvärdering och värdepåverkande faktorer. En kvantitativ metod användes med visst kvalitativt inslag. Det kvalitativa inslaget bestod av en intervju med en fastighetsmäklare som den kvantitativa enkätundersökningen sedan baserades på. Undersökningen utfördes i småstäderna Ludvika och Kristinehamn där 75 respondenter deltog i vardera stad, totalt 150 stycken. Resultatet fastställdes genom att varje värdepåverkande faktors medelvärde granskades. En diskussion av resultatet utfördes med hjälp av teori. Teorin består främst av en beskrivning av fastighetsmarknaden och olika värdepåverkande faktorer som kan vara till exempel antal kvadratmeter, bostadens läge och dess skick. Slutsatser som kunde dras av resultatet var att månadsavgiften (hyran), bostadsrättsföreningens ekonomi, inköpspriset, balkong/uteplats, parkeringsplats och välplanerad planlösning var viktigast för respondenterna. Då dessa faktorer är de som köpare värderar högst ökar med största sannolikhet deras betalningsvilja om dessa faktorer finns. Därmed kan vid värdering av bostadsrätter ett högre pris uppskattas om de beskriva faktorerna är uppfyllda.

Although relativistic physics tend to omit nondynamical "absolute objects" such as a flat metric tensor or a preferred time foliation, there exist interesting questions related to such entities, such as worries about the "flow" of time in special relativity, and the apparent disappearance of time altogether in canonical general relativity. This latter problem is related to the lack of a fixed causal structure with repect to which one might posit "equal-time" commutation relations, for example. In view of these issues, we consider whether including a flat background metric, and perhaps a preferred foliation, is physically worthwhile. We show how a derivation of Einstein's equations from flat spacetime can be generalized to include a preferred foliation, the possible significance of which we discuss, though ultimately we suggest why such a foliation might be present in metaphysics and yet absent from physics. We also derive a new "slightly bimetric" class of theories using the flat spacetime approach. However, such derivations are only formally special relativistic, because they give no heed to the flat metric's causal structure, which the curved effective metric might well violate. After reviewing the history of this problem, we introduce new variables to give a kinematic description of the relation between the two null cones. Then we propose a method to enforce special relativistic causality by using the guage freedom to restrict the configuration space suitably. Consequences for exact solutions, such as the Schwarzschild solution and its 'singularity,' are discussed. Advantages and difficulties regarding adding a mass term to the theory are discussed briefly. / text

In sheet metal forming (SMF), the major failure reason is galling. Galling is a process of different wear stages that leads to destruction of both the forming tool and the sheet metal working piece and is, because of that, of big economic importance for the SMF industries. Therefore, investigations and researches about how tool steels microstructure affect the tool steels galling resistance is of high priority. In the present work, different carbide properties were studied to find out how their properties affected the tool materials galling resistance. The investigated carbide properties were: Shape and size of the carbides   Carbide volume fraction Carbide distribution in the microstructure The investigation included three tools, all made of the PM tool steel S390, that were heattreated differently in order to achieve different carbide properties but still maintain the same hardness. The tools were galling tested in a slider-on-flat-surface (SOFS) tribometer to determine their galling resistances. In a scanning surface electron microscope (SEM) the tools galling marks were analyzed to find explanations for the SOFS tribometer results and the connection to the tools different carbide properties.  The investigations most galling resistant tool was the tool that had the microstructure with largest carbides which were distributed at grain boundaries and the second highest carbide volume fraction among the investigated tools.

The current development of consumer electronics, driven by the effort to manufacture smaller products with increased performance, has amplified the chance for inducing higher thermal stresses to these systems. In an effort to devise more effective cooling methods for these systems, many scholars have studied the convective cooling of discrete heating elements. This report discusses a methodology for fabricating and testing a suitable flat plate design with discrete heating elements for both natural and forced convection cooling experiments. There were two plate design attempts: (i) an aluminum plate and (ii) a R3315 hydrostatic-resistance plastic foam plate. For the purpose of conducting experiments for the discrete heating elements, the foam plate design was found to be an appropriate design. After designing a proper foam plate, several experiments were conducted for the natural convection case. The combination of parameters such as the geometric location and power output ratio between heaters that resulted in the maximum thermal conductance were studied. / text

Η διπλωματική αυτή εργασία ξεκινά με μια σύντομη αναφορά, στο κεφάλαιο 1, στις εξελίξεις που αφορούν τους διάφορους τρόπους ανίχνευσης της ακτινοβολίας, μετά από την αλληλεπίδρασή τους με το σώμα, και στην τεχνολογία απόκτησης ακτινοδιαγνωστικών εικόνων μέχρι την εισαγωγή της ψηφιακής απεικόνισης. Αναφέρεται, επίσης, η μετάβαση από το σύστημα φθορίζουσας οθόνης-φιλμ στο σύστημα του ενισχυτή εικόνας-tv monitor, στο σύστημα CCDs-tv camera και από εκεί στα συστήματα των επίπεδων ανιχνευτών. Στη συνέχεια, παρουσιάζονται τα πλεονεκτήματα της ψηφιακής απεικόνισης και πώς αυτά οδήγησαν στα σύγχρονα ψηφιακά συστήματα ακτινοδιαγνωστικής. Μετά την περιγραφή των συστημάτων αυτών, ακολουθεί η κατηγοριοποίησή τους ανάλογα με την τεχνολογία ανίχνευσης και πιο συγκεκριμένα ανάλογα με το σχήμα του ανιχνευτή, τον τύπο του συστήματος ανίχνευσης και τον τρόπο ανίχνευσης. Το κεφάλαιο 2 αφορά κυρίως τους επίπεδους ανιχνευτές. Αφού παρουσιάζεται η διαδικασία ανάγνωσης σε πίνακα ενεργού μήτρας, αναλύονται οι αρχές άμεσης και έμμεσης ανίχνευσης και οι παράμετροι που χαρακτηρίζουν την απόδοση ενός επίπεδου ανιχνευτή. Ολοκληρώνοτας το κεφάλαιο αυτό, γίνεται σύγκριση μεταξύ των δύο προαναφερθέντων επίπεδων ανιχνευτών, σύγκριση μεταξύ των ανιχνευτών έμμεσης ανίχνευσης, που χρησιμοποιούνται σε κλινικές εφαρμογές, και του ενισχυτή εικόνας, που τείνει να αντικατασταθεί σχεδόν σε όλα τα σύγχρονα μηχανήματα, και, τέλος, αναφορά σε διάφορες εξελίξεις πάνω στην τεχνολογία των επίπεδων ανιχνευτών. Τα συστήματα των επίπεδων ανιχνευτών εφαρμόζονται ήδη σε μια μεγάλη γκάμα ακτινοδιαγνωστικών συστημάτων, στα οποία πραγματοποιούνται εξετάσεις, όχι μόνο διάγνωσης, αλλά και θεραπείας. Εξετάσεις όπως η αγγειογραφία, η ψηφιακή αφαιρετική αγγειογραφία (DSA), στεφανιογραφία και αγγειοπλαστική περιγράφονται στο κεφάλαιο 3. Εκτός, όμως, από τα οφέλη που προκύπτουν από τις παραπάνω διαδικασίες, είναι πιθανό να προκληθούν και βλαβερές συνέπειες από την έκθεση του ασθενούς στις ακτίνες Χ. Αφού περιγραφούν τα ντετερμινιστικά και στοχαστικά αποτελέσματα των ακτινοβολιών στον άνθρωπο, αναφέρονται κάποιες δοσιμετρικές έννοιες και κάποιες συναρτησιακές σχέσεις μεταξύ τους, που σχετίζονται με τα παραπάνω αποτελέσματα και την πρόληψή τους. Η παρούσα εργασία, συνεχίζεται με το ειδικό μέρος, στο οποίο γίνεται, αρχικά, στο κεφάλαιο 4, μία σύντομη περιγραφή του ψηφιακού συστήματος στεφανιογραφίας και μία εισαγωγή σε δοσιμετρικές και γεωμετρικές έννοιες που θα χρησιμοποιηθούν στο επόμενο κεφάλαιο. Το κεφάλαιο 5 αναφέρεται, εξ’ ολοκλήρου, στο σύστημα του ψηφιακού στεφανιογράφου. Μετά την αναφορά στην παλμική ακτινοσκόπηση, τα modes απεικόνισης fluoroscopy και cine, ακολουθεί περιγραφή της τοποθέτησης των δοσιμέτρων, της γεωμετρίας και των προγραμμάτων του συστήματος, που χρησιμοποιήθηκαν για την καταγραφή του ρυθμού δόσης στην είσοδο του ασθενούς. Παρουσιάζονται τ’ αποτελέσματα και οι γραφικές παραστάσεις αυτών, καθώς και τα σχόλια που σχετίζονται με τη δοσιμετρία. Με την ολοκλήρωση των σχολίων συτών, γίνεται μετάβαση στην ποιότητα εικόνας (διακριτική ικανότητα υψηλής και χαμηλής αντίθεσης) και τη συσχέτισή της με τη δοσιμετρία. Η διπλωματική εργασία ολοκληρώνεται, κεφάλαιο 6, με διάφορους μελλοντικούς στόχους που προέκυψαν κατά τη διάρκεια της εκπόνησής της. / -

The nonlinear transition regime of supersonic boundary layers at low to moderate supersonic Mach numbers (Mach 2-3:5) under wind-tunnel conditions is studied using linear stability theory (LST) and direct numerical simulations (DNS). Two main flow configurations are chosen, a flat-plate boundary layer and a cone boundary layer. Previous investigations of the early nonlinear transition regime have mainly focused on two nonlinear mechanisms, the so-called "oblique breakdown" mechanism and "asymmetric subharmonic resonance". The first mechanism has only been investigated numerically while the second mechanism was first observed in experiments. This dissertation discusses three open questions related to both mechanisms: (i) Can oblique breakdown be identified in old wind-tunnel experiments published in the literature, (ii) what is the most dominant breakdown mechanism for a supersonic boundary layer, oblique breakdown or asymmetric subharmonic resonance, and (iii) does oblique breakdown lead to a fully developed turbulent boundary layer? By adopting the flow conditions and the disturbance generation of a specific experiment from the literature, in which asymmetric subharmonic resonance in a wave train was studied, it was possible to show that oblique breakdown might also have been present in the experiment, although oblique breakdown was not reported by the experimentalists. Hence, this experiment might provide the first experimental evidence of oblique breakdown for a supersonic boundary layer. The second question was addressed by performing DNS of a wave packet. A wave packet is typically used as a model of a broadband disturbance environment. If a nonlinear mechanism is dominant, it should leave strong imprints in the disturbance spectrum of the wave packet. In the DNS of the wave packet, oblique breakdown was visible in the disturbance spectrum while subharmonic resonance played only a minor role. To study the last question, a set of DNS of the entire transition path from the linear regime to the turbulence stage was conducted. Some of these simulations demonstrated that the ow reached turbulence near the downstream end of the computational domain.

This dissertation explores the uses for data collected at broadband seismic stations to investigate upper mantle structures. In the Barents Sea region, we use seismic waveform modeling on data collected from arrays in Norway and Finland to investigate the nature of the Hales discontinuity in this area. We find that the unusually high velocities required by the move-out of the diffracted first arrival requires a discontinuity below the Moho, which we believe is probably caused by a phase transition from spinel to garnet peridotite. In Chile and Argentina, we use data collected during the Chile Argentina Geophysical Experiment to perform a regional travel time tomography in order to investigate the nature of the mantle above this unusual subduction zone. The northern half of the study area (between 30° and 33°S) is characterized by the central Chilean flat slab segment, where the descending Nazca slab dives to 100 km depth and then flattens, traveling horizontally for hundreds of kilometers before resuming its descent into the mantle. The Nazca plate in the southern half of the study area has a relatively constant dip of about 30°. The southern half exhibits normal arc volcanism roughly above the 100 - 125 km contours of the downgoing slab. The northern half has had no active volcanism in the past 2 Ma, and underwent an eastward displacement of arc volcanism beginning ~10 Ma. The northern half is also remarkable for the basement-cored uplifts of the Sierras Pampeanas. Our study of the upper mantle above the southern half indicates low P wave velocities, low S wave velocities, and high Vp/Vs ratios below the arc, consistent with partial melt. Above the flat slab segment we find low Vp, high Vs, and low Vp/Vs ratios. While the nature of the material responsible for these velocities cannot be uniquely determined, the velocities indicate it must be dry, cold, and depleted. In the transition from flat to normal subduction geometries, we find velocities consistent with frozen asthenosphere, which may have been displaced by the advancing flat slab during the Miocene.

Administration of flat blocks in Lithuania is a relevant issue. Recently on the initiative of the authorities’ flat block communities or their hired housekeeping companies started to take care of the management and upkeep of flat blocks. Management of flat blocks consists of many parts that must be performed by a company which maintains the building, so it has to administrate and store the data. Recently in Lithuania, especially in greater cities, more and more flat blocks are built, so the quantity of flat block communities increases automatically. The greater quantity of flat block communities has increased the demand to use that data effectively. Do flat block communities in Lithuania have and use special software for data administrating? Is this software available in the market? What kind of data is stored and administrated by flat block communities? In order to get an answer to these questions, the objectives of the project work were set as follows: * To investigate what kind of information is stored and administrated by the flat block communities; * To investigate what kind of software is currently used by the flat block communities; * To investigate which software products are available in the market and are they expedient in using them to administrate the data of flat block community; * To evaluate whether it is expedient to develop an information system which could help to administrate the data of flat block communities. After qualitative analysis it was concluded... [to full text]