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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.
31

Study of Standard Voltage Setting of a Primary Substation

Kao, Tzu-yu 04 July 2009 (has links)
Stability of the power quality is one of the objectives that power companies always try to assure. With energy shortage and the increases of fuel cost over years, reduction of expenses in all areas is another effort of the power company. Dealing with the above problems, Taiwan Power Company sets up a standard voltage for secondary side of each primary substation. Standard voltage is a commitment of expected 69kV primary substation bus voltage. A proper setting of the standard voltage can reduce voltage variation, in the secondary substation, and reduce the operation frequencies of the on load tap changer. Besides, it can prolong the service life and the maintenance cycle, and it can also reduce maintenance cost of each main transformer. This study proposes a method to calculate the standard voltage to improve the shortcomings that the voltage used to be set up with experience rule. The load and voltage data were used to build a neural network model. Improved particle swarm optimizer was used to find the parameters of the radial basis function neural network in order to build an efficient network. This network uses improved particle swarm optimizer again to the standard voltage. The proposed approach has been verified by the comparison of winter and summer standard voltages on the Tainan primary substation of taipower with accurate results.
32

Vem för de törstigas talan? : En studie av debatten kring vattensektorn

Stenholm, Moa January 2008 (has links)
<p>1.1 billion people are today living without sustainable access to improved water. The debate over the water sector has been dominated by the discussion over whether public or private actors are the most competent to manage it. In this paper the arguments pro and contra the two positions are presented to try to overview the debate and to try to find new ways to approach the question of the people living without clean water. By examining possible alternatives towards the discussion of public and private actors, it might result in some new approaches on how to move closer towards a solution. One alternative is local, small- scale projects which focus on the situation of the targetgroup in most need. I have in this paper tried to find signs of that the debate is changing in a way that would bring positive outcomes for the people living without access to improved water. The debate is changing, both the private as well as the public sector is changing their ways of working and the alternative approach is increasing its influence. Hopefully the debate can move away from the discussion of ideology and acknowledge the strengths of each other to result in possible solutions of the water problems. With the increasing interest and concern for the question of water there is thus an opportunity for a change in the debate that would benefit the ones living without sustainable access to improved water.</p>
33

Association of Glucosamine and/or Chondroitin Use with Reports of Improved Health and Joint Pain among Individuals with Arthritis, National Health Interview Survey (NHIS) 2012

Woodard, Kedra 11 August 2015 (has links)
ABSTRACT BACKGROUND: Arthritis is increasingly becoming a public health concern as it is the leading cause of disability. Glucosamine and chondroitin, which are alternative dietary supplements, are commonly marketed for persons with joint pain. The purpose of this study is to examine if self-reported 12-month and past 30-day use of glucosamine and/or chondroitin among persons with any arthritis, unspecified arthritis, and rheumatoid arthritis is associated with reports of past 12-month improved health and reports of past 30-day joint pain, aching, and stiffness, respectively. METHODS: The 2012 National Health Interview Survey (NHIS), a nationally representative cross-sectional household interview survey, was used for this study. The adult sample consisted of 34,525. Subgroup analyses were conducted on 7,654 respondents with any arthritis, 6,016 with unspecified arthritis, and 898 with rheumatoid arthritis. The independent variables were defined as the use of glucosamine only, chondroitin only, or glucosamine and chondroitin one or more times in the past 12 months and past 30 days. The dependent variables were defined as self-reported past 12 month improved health and past 30 day joint pain, aching, and stiffness. Descriptive, bivariate, and multivariate analyses were conducted using SAS 9.4 accounting for the complex survey design, computing missing values as missing completely at random for variance estimation. All multivariate logistic regression models included sociodemographics, use of other observed alternative therapies, and other chronic conditions. RESULTS: Approximately 21.8% of U.S adults had any arthritis, 17.0% had unspecified arthritis and 2.5% had rheumatoid arthritis. Among persons with any arthritis, approximately 3.7% used glucosamine, 0.4% used chondroitin, and 3.4% used both glucosamine and chondroitin within the past 12 months while approximately 5.1% used glucosamine, 0.6% used chondroitin, and 0.4% used both glucosamine and chondroitin within the past 30 days. Among persons with unspecified arthritis, approximately 3.7% used glucosamine, 0.5% used chondroitin, and 3.8% used both glucosamine and chondroitin within the past 12 months while 5.5% used glucosamine, 0.5% used chondroitin, and 0.4% used both glucosamine and chondroitin within the past 30 days. Among persons with rheumatoid arthritis, approximately 2.4% used glucosamine, 0.3% used chondroitin, and 2.1% used both glucosamine and chondroitin within the past 12 months while approximately 2.9% used glucosamine, 0.7% used chondroitin, and 0.5% used both glucosamine and chondroitin within the past 30 days. Women used more of all supplements (past 12 months and past 30 days) except past 12 month use of chondroitin among persons with any arthritis. Persons 56 to 70 years old had the highest proportion of past 12 month and 30 day supplement use among persons with unspecified arthritis. After adjusting for sex, age, race, BMI, poverty level, other health conditions, and other CAM therapies (acupuncture, energy, mind-body, and chiropractic/osteopathic therapies), the use of chondroitin only (adjusted OR= 0.6; p= <0.01) and the use of both glucosamine and chondroitin (adjusted OR= 5.7; p= <0.01) during the past 30 days was associated with self-reported past 30 day joint pain, aching, and stiffness among persons with any arthritis. After adjusting for age, BMI, poverty level, region, other health conditions, and other CAM therapies (acupuncture, energy, mind-body, and chiropractic/osteopathic therapies), the use of chondroitin only was also associated with past 30 day joint pain, aching, and stiffness among persons with unspecified arthritis (adjusted OR= 0.5; p= 0.02). CONCLUSION: Chondroitin alone was associated reports of past 30 day joint pain, aching, and stiffness among persons with any arthritis and unspecified arthritis highlighting a potential effective role and use for this supplement. In addition, the use of both glucosamine and chondroitin were associated with reports of past 30 day joint pain, aching, and stiffness among persons with any arthritis. Marketing may play a role in these relationships and should be further examined.
34

Wettability alteration in high temperature and high salinity carbonate reservoirs

Sharma, Gaurav, M.S. in Engineering 02 November 2011 (has links)
The goal of this work is to change the wettability of a carbonate rock from oil wet-mixed-wet towards water-wet at high temperature and high salinity. Only simple surfactant systems (single surfactant, dual surfactants) in dilute concentration were tried for this purpose. It was thought that the change in wettability would help to recover more oil during secondary surfactant flood as compared to regular waterflood. Three types of surfactants, anionic, non-ionic and cationic surfactants in dilute concentrations (<0.2 wt%) were used. Initial surfactant screening was done on the basis of aqueous stability at these harsh conditions. Contact angle experiments on aged calcite plates were done to narrow down the list of surfactants and spontaneous imbibition experiments were conducted on field cores for promising surfactants. Secondary waterflooding was conducted in cores with and without the wettability altering surfactants. It was observed that barring a few surfactants, most were aqueous unstable by themselves at these harsh conditions. Dual surfactant systems, a mixture of a non-ionic and a cationic surfactant increased the aqueous stability of the non-ionic surfactants. One of the dual surfactant system, a mixture of Tergitol NP-10 and Dodecyl trimethyl ammonium bromide, proved very effective for wettability alteration and could recover 70-80% of OOIP during spontaneous imbibition. Secondary waterflooding with the wettability altering surfactant (without alkali or polymer) increased the oil recovery over the waterflooding without the surfactants (from 29% to 40% OOIP). Surfactant adsorption calculated during the coreflood showed an adsorption of 0.24 mg NP-10/gm of rock and 0.20 mg DTAB/gm of rock. A waterflood done after the surfactant flood revealed change in the relative permeability before and after the surfactant flood suggesting change in wettability towards water-wet. / text
35

Βελτιωμένα διαστήματα εμπιστοσύνης για την διασπορά κανονικού πληθυσμού

Ταφιάδη, Μαρία 25 May 2009 (has links)
Η παρούσα μεταπτυχιακή διατριβή ανήκει στο επιστημονικό πεδίο της Στατιστικής Θεωρίας Αποφάσεων και αποσκοπεί στην κατασκευή βελτιωμένων διαστημάτων εμπιστοσύνης για την διασπορά ενός πληθυσμού που προέρχεται από κανονική κατανομή. Η μελέτη του προβλήματος της κατασκευής ενός διαστήματος εμπιστοσύνης για την διασπορά μιας κανονικής κατανομής, παρουσιάστηκε στην εργασία του Shorrock (1990). Ειδικότερα, ο Shorrock σε αυτή του τη μελέτη κατασκεύασε διαστήματα εμπιστοσύνης που εξαρτώνταν από την δειγματική διασπορά και από τον δειγματικό μέσο. Συγκεκριμένα, τα νέα αυτά διαστήματα έχουν το ίδιο μήκος με το κλασικό διάστημα εμπιστοσύνης για την διασπορά, αλλά έχουν ομοιόμορφα μεγαλύτερη πιθανότητα κάλυψης. Αρχικά, εξετάζουμε λεπτομερώς τα γνωστά διαστήματα εμπιστοσύνης και πιο συγκεκριμένα, το διάστημα εμπιστοσύνης ίσων ουρών, ελαχίστου μήκους, λόγου πιθανοφανειών και το αμερόληπτο διάστημα εμπιστοσύνης για να γίνουν οι απαραίτητες συγκρίσεις με τα διαστήματα που θα παραχθούν στη συνέχεια. Το πρώτo διάστημα κατασκευάζεται ακολουθώντας μία διαδικασία που είναι αντίστοιχη με την μεθοδολογία εύρεσης του εκτιμητή τύπου Stein, γι' αυτό και το διάστημα που προκύπτει, ονομάζεται διάστημα εμπιστοσύνης τύπου Stein. Η κατασκευή του επόμενου διαστήματος βασίζεται στην μεθοδολογία εύρεσης του εκτιμητή Brown (1968) γι' αυτό και ονομάζεται διάστημα εμπιστοσύνης τύπου Brown. Κατ' όπιν και σε αναλογία με την μεθοδολογία εύρεσης των εκτιμητών Brewster and Zidek (1964) γενικεύεται το προηγούμενο διάστημα κατασκευάζοντας το διάστημα εμπιστσύνης Brewster and Zidek, το οποίο αποδεικνύεται με τη σειρά του ότι, είναι ένα γενικευμένο διάστημα Bayes. Έτσι, κάνοντας τη σύγκριση ως προς την πιθανότητα κάλυψης μεταξύ των νέων αυτών διαστημάτων και του κλασικού διαστήματος εμπιστοσύνης αποδεικνύεται πως αυτή είναι ομοιόμορφα μεγλύτερη για τα νέα διαστήματα. / This master thesis belongs to Statistic Decision Theory field and its purpose is the construction of improved confidence intervals for a normal variance. These intervals were studied by Shorrock (1990). Especially, the usual confidence interval for the variance of a normal distribution, is a function of the sample variance alone. However, in his work Shorrock constructs intervals for variance that also depend on the sample mean. The new intervals have the same length as the shortest interval, depending only on the sample variance and have uniformly higher probability of coverage. Initially, we study well known confidence intervals such as, confidence interval with equal tails, confidence interval of minimum length and then we construct the improved ones. More specifically, we construct a confidence interval analogue of the point estimator in Stein (1964), a confidence interval analogue of the point estimator in Brown (1968) and a Brewster and Zidek (1974) confidence interval, which is also a generalized Bayes interval. Thus, we understand that the intervals above, are improved because they have uniformly greater coverage probability than the shortest one.
36

Towards an Improved Baton Technique: The Application and Modification of Conducting Gestures Drawn from the Methods of Rudolf, Green and Saitō for Enhanced Performance of Orchestral Interpretations

Lee, Ki Sun January 2008 (has links)
Since the early nineteenth century, a conductor has led orchestras in concert, rather than the concertmaster or the composer from a keyboard instrument. There is no theory about the function of the conductor or technique for conducting an orchestra or choir in that early period. Early conductors probably imitated the bow motions of the concertmaster, who was the leader of the group of instrumental players. The increasing importance of conducting resulted in conductors who not only cued to indicate entrances and cut offs as the concertmaster did, but also helped the musicians to understand his musical interpretation and play as a unified musical body. The establishment of this new role soon required the training of future generations of conductors and eventually conducting textbooks, with guidelines and other educational material for the apprentice conductor. In this paper, the author explores the historical background of conducting technique and the development of conducting textbooks in the twentieth century. Three conducting textbooks were chosen representing different approaches: Max Rudolf's The Grammar of Conducting; Elizabeth A. H. Green The Modern Conductor; and Hideo Saitō The Saitō Conducting Method. The author analyzes the conducting theory presented in each textbook and pinpoints the strengths and weaknesses of the three schools. He then suggested integrates beat patterns, combining elements from them, proposes more effective conducting gestures for his interpretation of the music. The focus for these integrated beat patterns is on the physical gestures and patterns of the right hand, not left hand gestures or specific expressive gestures. Chapter 2 summarizes the characteristics of the three conducting theories. Chapter 3 analyzes the basic characteristic motions of each school. Chapters 4 through 6 propose adaptations of conducting gestures, drawing from the three schools to interpret challenging sections of the examples: Marche royale from Histoire du Soldat by Igor Stravinsky, Adagio for Strings by Samuel Barber, and the Ouverture: Die Hebriden by Felix Mendelssohn. For the most effective performance of the author s interpretations, proposed integrated beat patterns are suggested for the phrases shown in the musical examples. Some of the beat patterns are presented in diagrams to show the integrated beat pattern, derived from the author s synthesis of the basic five motions of the three schools adapted from the three schools.
37

Sequential Agroforestry systems for Improving Fuelwood Ssupply and Crop Yield in Semi-arid Tanzania

Kimaro, Anthony 03 March 2010 (has links)
Promotion of agroforestry practices in sub-Sahara Africa may help sustain subsistent food and wood production by integrating trees and crops on farmlands to replenish soil fertility and improve crop yield. Using rotational woodlot and pigeonpea intercropping systems in semi-arid Tanzania as case studies, my research screened suitable tree species to increase fuelwood supply and examined mechanisms for reducing tree-crop competition. By adopting nutrient use efficiency (the ratio of biomass yield to nutrient uptake) as a criterion, I found that selecting tree species of low wood nutrient concentrations would minimize nutrient exports by 42 – 60 %, thus reducing soil nutrient depletion while concurrently sustaining local fuelwood supply harvested from rotational woodlots. Currently smallholder farmers cannot afford to replenish soil fertility because of high fertilizer costs. However, 5-year tree fallowing raised soil N and P levels for maize culture as high as those from recommended fertilizer applications. Post-fallow maize yield was also increased significantly over natural fallow practices. Apparently there is a trade-off between yields of maize and fuelwood under rotational woodlot culture providing farmers the choice to proportion tree and crop composition based on priority demands. An alternative practice of intercropping pigeonpea with maize may also rapidly replenish soil fertility as well as enhance maize yield when competitive interactions between trees and crops are controlled. Vector analysis revealed that such interactions suppressed biomass yields of maize and pigeonpea by 30 % and 60 %, respectively, due to limited soil nutrients and/or moisture. Optimizing yields of both crops would require prescribed fertilizer addition when intercropped, but dose rates can be lowered by half under the improved fallow system due to alleviating interspecific competition. My findings form the basis of a plea for greater use of rotational woodlot and pigeonpea intercropping systems in semi-arid areas. I conclude that smallholder farm management of rotational agroforestry systems can be significantly improved by refining tree selection criteria and mitigating nutrient competition between trees and crops to maintain food and fuelwood production.
38

The acute effects of weight training on softball throwing velocity

Sheehy, Kevin M Unknown Date (has links)
The short-term enhancement of physical performance known as post-activation potentiation could be exploited in the design of sport-specific training sessions. The purpose of this study was to compare the potentiation of softball throwing velocity following two kinds of resistance-training session: a control session consisting of traditional heavy-load sets, and an experimental "Pmax" session consisting of sets of loads selected to maximise the mean power output during explosive bench presses. Both sessions included plyometric medicine ball chest passes. Eight male softball players of premier grade, with at least 2 yr experience of resistance training, performed the two sessions in a crossover fashion, with 30 min recovery between sessions. Softball throwing velocity was measured with a radar gun immediately before and at 2-min intervals 4-10 min after each session. Percent effects on throwing speed were analyzed via log transformation, and t statistics were used to make magnitude-based inferences with respect to the smallest important change of 2%. The average throwing velocity increased between pre and post tests for both treatments; the average increase was a substantial 2.3% (0.5 to 4.1%). Throwing velocity after Pmax training was a trivial 0.4% slower relative to that after heavy-load training (90% confidence limits -1.2 to 1.9%). There was a greater change in throwing velocity by 10 min post treatment than by 4 min post treatment; the change by 10 min was 5.0% (3.2 to 6.7%) for the Pmax training session and 5.3% (2.1 to 8.6%) for the heavy-load session. These effects were almost certainly beneficial for throwing speed, but the difference between them was unclear (-0.3%; -3.7 to 3.1%). The mean change between 4 and 10 min for both treatments combined was 5.1% (90% confidence limits 3.6 to 6.7%). The short-term enhancement of throwing performance following heavy-load and Pmax training sets has implications for the design of softball warm-up routines. There is also the potential for softball players to use such training to improve their throwing velocity during games.
39

Impregnation of Norway spruce (Picea abies L. Karst.) wood with hydrophobic oil /

Ulvcrona, Thomas, January 2006 (has links) (PDF)
Diss. (sammanfattning) Umeå : Sveriges lantbruksuniv., 2006. / Härtill 5 uppsatser.
40

Seeing Through the Smoke: Measuring Impacts of Improved Cookstove Interventions on Technology Adoption and Environmental and Health Outcomes

Lewis, Jessica January 2015 (has links)
<p>Traditional cooking using biomass is associated with adverse health consequences, local environmental degradation, and regional climate change. Improved stoves (ICS; liquefied petroleum gas (LPG), biogas, electric, efficient biomass) are heralded as a solution, but their adoption and use remains low. In the first chapter, I report on a series of pilot programs that utilized the marketing mix principles of promotion, product, price and place to increase stove sales in rural Inia. We found that when given a choice amongst products, households strongly preferred an electric stove over improved biomass-burning options. Households clearly identified price as a significant barrier to adoption, while provision of discounts (e.g., rebates given if households used the stove) or payments in installments were related to higher purchase. Collectively, these pilots point to the importance of continued and extensive testing of messages, pricing models, and responses to different stove types prior to scale-up. Thus, a one-size-fits-all approach will be unlikely to boost ICS adoption. </p><p>In the second and third chapters, I analyze the impact of mainly improved stove use on social, environmental, and health outcomes in rural India- first in a sample of biogas stove users in Odisha, India, and next with households in the Himalayan state of Uttarakhand. In both settings, ICS use was associated with reduced use of firewood, substantial time savings for primary cooks, and significant reduction in exposure to particulate matter and polycyclic aromatic hydrocarbons in household air. I find that ICS users in Odisha spend reduced time in the hospital with acute respiratory infection and reduced diastolic blood pressure, but no relationship with other health measurements. </p><p>In the third chapter, I also find significant reduction in exposure to personal air pollution. Using temperature sensors as objective stove use monitors for all stoves and heaters we find that households underreport use of improved and traditional stoves. </p><p>These papers provide encouraging evidence of potential for adoption of clean stove and a suite of benefits from clean stove use; however, in order to achieve recommended levels of air pollution additional policies may be needed.</p> / Dissertation

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