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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
191

On Heat and Paper : From Hot Pressing to Impulse Technology

Lucisano, Marco Francesco Carlo January 2002 (has links)
Impulse technology is a process in which water is removedfrom a wet paper web by the combined action of mechanicalpressure and intense heat. This results in increased dewateringrates, increased smoothness on the roll side of the sheet, andincreased density. Although the potential benefits of impulsepressing have been debated over the past thirty years, itsindustrial acceptance has been prevented by web delamination,which is defined as a reduction in the z-directional strengthof paper. This thesis deals with the mechanism of heat transfer withphase change during impulse pressing of wet paper. The resultsof four complementary experimental studies suggest that littleor no steam is formed in an impulse nip prior to the point ofmaximum applied load. As the nip is unloaded and the hydraulicpressure decreases, hot liquid water flashes to steam. Weadvance the argument that the force expressed upon flashing canbe used to displace liquid water, in a mechanism similar tothat originally proposed by Wahren. Additionally, modelexperiments performed in a novel experimental facility suggestthat the strength of flashing-assisted displacement dewateringcan be maximized by controlling the direction of steam venting.If this solution could be exploited in a commercially viableimpulse press, delamination would cease to be an issue ofconcern. The thesis includes a study of the web structure ofdelaminated paper. Here, we characterized delaminated paper bythe changes in transverse permeability and cross-sectionalsolidity profiles measured as a function of pressingtemperature. We found no evidence that wet pressing and impulsepressing induced stratification in non-delaminated sheets andconcluded that the parabolic solidity profiles observed weredue to capillary forces present during drying. Further, thepermeability of mechanically compressed never-dried samples wasfound to be essentially constant for pressing temperatureslower than the atmospheric boiling point of water and toincrease significantly at higher pressing temperatures. Wepropose this to be a result of damage to the cell wall materialdue to flashing of hot liquid water in the fiber walls andlumina. Finally, we present a method and an apparatus formeasurement of the thermal properties of water-saturated paperwebs at temperatures and pressures of interest for commercialhigh-intensity processes. After validation, the method wassuccessfully applied to measure the thermal conductivity,thermal diffusivity and volumetric heat capacity ofwater-saturated blotter paper as functions of temperature andsolids content. Here, we found that the thermal conductivityincreased with solids content in the range from 30%\ to 55%,which is in conflict with the commonly stated assumptions of adecreasing trend. We propose that this discrepancy could be dueto the thermal conductivity of air-free fibers wetted byunpressable water only, being significantly different from thatof dry cellulose.
192

A Study on Information Transmission and Volume-price Relationship in Taiwan Stock Index and Industrial Stock Index

Chang, Chen-wei 20 August 2007 (has links)
The purpose of this study is to research the volume-price relationship and information transmission among Taiwan Stock Index, Electronic Industry Index, Financial Industry Index and Plastic Industry Index. This study uses the time series methods of ADF unit root test, variance decomposition, Granger causality and impulse response analysis to proceed empirical research. It covers the period June 2, 2003, through December 29, 2006 and uses the daily data for sample. The empirical results can be summarized as follows¡G (1) All the trading volume and stock return series are trend stationary at level, therefore, they are integrated of order 0 ~ I (0). (2) The variance decomposition shows that the major change of every variable comes from by itself. The explanatory power of trading volume is higher than stock returns. Among the stock returns of Taiwan Stock Index, Electronic Industry Index, Financial Industry Index and Plastic Industry Index, Taiwan Stock Index has the highest explanatory power. (3) According to the Granger causality test, it expresses that trading volume leads stock returns. Taiwan Stock Index is the leading indicator of the Electronic Industry Index and Financial Industry Index. (4) As to the impulse response functions, neither persistent nor overall. The effect of shocks on all variables is transitory.
193

Ultra Wideband Impulse Radio for Wireless Sensing and Identification

Baghaei Nejad, Majid January 2008 (has links)
Ubiquitous computing and Internet-of-Things (IoT) implies an untapped opportunity in the realm of information and communication technology, in which a large number of micro-devices with communication and/or computing capabilities, provides connectivity for anything, by anyone at anytime and anywhere. Especially, these devices can be equipped with sensors and actuators that interact with our living environment. Barcode, smart contactless card, Radio Frequency Identification (RFID) systems, wireless sensor network (WSN), and smart mobile phones are some examples which can be utilized in ubiquitous computing. RFIDs and WSN have been recognized as the two promising enablers for realization of ubiquitous computing. They have some great features such as low-cost and small- size implementation, non-line of sight operation, sensing possibilities, data storing ability, and positioning. However, there are several challenges which need to be addressed, such as limited life time for battery powered device, maintenance cost, longer operation range, higher data rate, and operation in dense multipath and multiuser environment. Ultra-Wideband Impulse Radio (UWB-IR) with its huge advantages has been recognized as a great solution for future WSN and RFID. UWB-IR technique has the possibility of achieving Gb/s data rate, hundreds of meter operation range, pJ energy per bit, centimeter accuracy of positioning, and low cost implementation. In this work utilization of UWB-IR in WSN and RFID is investigated. A wireless sensor network based on UWB-IR is proposed focusing on low-cost and low-power implementation. Our contribution is to imply two different architectures in base station and sensor nodes to satisfy power, complexity and cost constraints. For sensor nodes, an autonomous UWB-IR detection is proposed, which detects the UWB signal autonomously and no restrict synchronization is required. It reduces the circuit complexity significantly. The performance in term of bit-error-rate is compared with two other common detection techniques. It is shown that the new detection is more robustness to timing jitter and clock skew, which consequently reduces the clock and synchronization requirements considerably. A novel wireless sensing and identification system, based on remote-powered tag with asymmetric wireless link, is proposed. Our innovative contribution is to deploy two different UWB and UHF communication techniques in uplink and downlink respectively. In the proposed system, tags capture the required power supply from different environmental sources (e.g. electromagnetic wave transmitted by a reader) and transmit data through an ultra-low power impulse UWB link. A new communication protocol is devised based on slotted-aloha anti-collision algorithm. By introducing several improvements including of pipelined communication, adaptive frame size, and skipping idle slots, the system throughput of more than 2000 tags/s is achieved. To prove the system concept a single chip integrated tag is implemented in UMC 0.18μm CMOS process. The measurement results show the minimum sensitivity of -18.5 dB (14.1 μW) and adaptive data rate up to 10 Mb/s. It corresponds to 13.9 meters operation range, considering 4W EIRP, a matched antenna to the tag with 0dB gain, and free space path loss. This is a great improvement in operation range and data rate, compared with conventional passive RFID, which data rate is limited to a few hundreds of Kb/s. System integration in a Liquid-Crystal-polymer (LCP) substrate is investigated. The integration of a tunable UWB-IR transmitter and a power scavenging unit are studied. Our contribution includes embedding and modeling the RF components and antenna in substrate and co-optimizing the chip and package with on-chip versus off-chip passives trade-offs. Simulation results verify the potential of system-on-package solution for UWB integration. The effect of antenna miniaturization in a UWB system is studied. Our focus is to scale down a UWB antenna and optimize the performance through the chip-antenna co-design. A tunable impulse- UWB transmitter is designed in two cases - a conventional 50Ω design and a co-design methodology. The simulation results show that the standard 50Ω design technique can not reach the best condition in all cases, when a real antenna is placed into the system. The performance can be improved significantly when doing codesign. The antennas and UWB transmitter performances are evaluated in a given UWB systems. It is shown that the operation distance at a target performance is reduced with antenna scaling factor and it can be compensated by antenna-transceiver co-design. The result proves the importance of antenna-transceiver codesign, which needs to be addressed in the earliest phases of the design flow. / QC 20100701
194

Worldizing kontra IR-reverb

Israelsson, Viktor January 2011 (has links)
Detta examensarbete går ut på att jämföra två verktyg som ljuddesigners kan använda sig av för att placera ljud i önskade akustiska miljöer. Verktygen i fråga är båda två metoder för att applicera reverb på ljudfiler. Angreppsvinkel för jämförandet är främst frekvensanalys, men utöver rent tekniska detaljer finns även en rad andra inspelningsproblematiska detaljer att ta i beaktning. / The purpose of this degree work is to compare two sound design tools, which both are used to virtually place a sound in an acoustic environment. The tools in question are both methods to add reverb on sound files. The angle of the comparison is mainly frequency analysis. Above technicality, practical details are taken into consideration.
195

Do crude oil price changes affect economic growth of India, Pakistan and Bangladesh? : A multivariate time series analysis

Akram, Muhammad January 2012 (has links)
This paper analyzes empirically the effect of crude oil price change on the economic growth of Indian-Subcontinent (India, Pakistan and Bangladesh). We use a multivariate Vector Autoregressive analysis followed by Wald Granger causality test and Impulse Response Function (IRF). Wald Granger causality test results show that only India’s economic growth is significantly affected when crude oil price decreases. Impact of crude oil price increase is insignificantly negative for all three countries during first year. In second year, impact is negative but smaller than first year for India, negative but larger for Bangladesh and positive for Pakistan.
196

Macroeconomic Shocks and Monetary Policy : Analysis of Sweden and the United Kingdom

Gajic, Ruzica January 2012 (has links)
External economic shocks cause domestic macroeconomic aggregates to fluctuate. This may call for a macroeconomic policy intervention. Since the early 1990s an increasing number of countries have adopted an inflation targeting framework. In reality, inflation targeters do not have perfect information when determining the interest rate in order to maintain their goal of price stability and stable economic growth. Therefore it is relevant to understand how shocks affect the domestic macroeconomic aggregates theoretically and investigate whether the theoretical predictions hold empirically. I use the New Keynesian model by Clarida, Galí and Gertler from 1999 and investigate explicitly the theoretical effects of expected and unexpected supply and demand-side shocks on the monetary policy instrument and the two monetary policy target variables – the interest rate, output gap and inflation rate. By analysing the impulse-response functions of a structural VAR model applied to quarterly Swedish and British data from 1994 to 2011, I test empirically the theoretical predictions according to the New Keynesian model. I find that the empirical results are in line with the theoretical predictions.
197

Vardagslyx

Dickson, Caroline, Lindblad, Linnéa, Matschy, Alexandra January 2009 (has links)
Our purpose with this research has been to obtain a deeper insight and understanding for the phenomenon and term “weekday-luxury.” Through our research, we have found a link between value, service, brands and consumer behaviour into a relationship that we termed “weekday-luxury.” This link of values is particularly interesting to us and we are curious about the underlying motivation to “weekday-luxury” and the driving forces underlying the phenomenon. We have noticed in society that people need something extra in their daily lives and we attempt to speculate where their perceived value lies through the concept of “weekday-luxury." Our goal is to determine a deeper understanding and insight into this phenomenon and how it meets our needs through an identifiable pattern. We also analyze the nature of “weekday-luxury” and its meaning. This essay further focuses on peoples effort to “treat ourselves” from which we have chosen a market-oriented perspective, as well as a quantitative method, from which we have performed eight personal interviews and three mail interviews.
198

Oil And The Macroeconomy : Empirical evidence from 10 OECD countries

Al-Ameri, Leyth January 2012 (has links)
This paper examines the oil price-macro economy relationship by means of analyzing the impact ofoil price on Industrial production, real effective exchange rate, long term interest rate and inflation rate for a sample of ten OECD countries using quarterly data for the period 1970q1-2011q1.The impact of oil price shock on industrial production is negative and occurs with a lag of one year. However, the impact has weakened considerably compared to the 1970s. The impact on real effective exchange rate is negative/positive for a net importer/exporter, and the magnitude of the shock depends on the county´s share of net import/export of total world demand/supply. Interest rates are affected negatively, through increase in inflation rates following the oil price shock. The effect tends to die out after 5-8 quarters following the shock for most of the variables and countries. This paper also applies alternative methods to test for unit root and cointegration, which takes into account for structural breaks in the data. The weakness of Phillips-Peron test is clearly demonstrated in the case of inflation rates and interest rates, where the test falsely considered the series to be non-stationary when they in fact are stationary around a structural break. There is also strong evidence of cointegration between oil price and inflation rates and between oil price and interest rates, especially when taking account for structural breaks. / This study also highlights the relevance of oil scarcity and oil peak theory. It is shown that these two terms should receive more attention than they have received so far as more oilexporters have reached their production peaks and more are likely to be followed. According to the data, renewable source of energy are not likely to dominate OECD countries energy mix in the short term, instead, there is a trend of increasing natural gas consumption among most of OECD countries. Natural gas markets are likely to play an equal role in the future as oil markets do today. The dilemma that importing countries are facing today, particularly in Europe, is whether to expose their markets to Russia or to the Middle East.
199

Monetary transmission mechanism in Taiwan- Application of FAVECM model.

Lin, An-ni 06 July 2010 (has links)
This study discusses the monetary policy transmission mechanism in the different channels. The analysis is conducted using generalized impulse response functions derived from a factor-augmented vector error correction (FAVECM) model. The FAVECM methodology as developed by Lee (2009) extends the factoraugmented vector autoregression (FAVAR) model to analyze long-run and shortrun dynamics of non-stationary variables. This recenly derived FAVECM model combines the advantages of factor model and the VECM model. The estimations are conducted using 174 macroeconomic time series in monthly frequency for the period January 2000 to September 2009. Results indicate that interbank call loan rate, deposit rate and prime lending rate are conintegrated, which provides sufficient evidence of the existence of the credit channel in monetary transmission system. Other GIRF results are generally consistent of the expected monetary policy effectiveness.
200

Purchasing power parity and exchange rate transmission channel analysis - Application of FAVECM

Pan, Ying-ying 15 July 2010 (has links)
This study revists Purchasing Power Parity (PPP) and discusses the monetary policy transmission mechanism in exchange rate channels. The analysis is conducted using generalized impulse response functions derived from a Factor- Augmented Vector Error Correction (FAVECM) model. The FAVECM methodology as developed by Lee (2009) extends the Factor- Augmented Vector Autoregression (FAVAR) model to analyze long-run and shortrun dynamics of non-stationary variables. This recently derived FAVECM model combines the advantages of factor model and the VECM model. The estimations are conducted using 157 macroeconomic time series in monthly frequency for the period January 2000 to September 2009. Results indicate that PPP exists and expansionary devaluation effect in Taiwan. Other GIRF results are generally consistent of the expected exchange rate effectiveness.

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