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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.
181

Tjänster och lönsamhet med ett batterilager till en solcellspark : En fallstudie om att implementera ett batterilager till Vasakronans solcellspark i Uppsala / Profitability and services provided by a battery storage system connected to a solar park

Jonsson, Lisa, Valdemarsson, Joel January 2021 (has links)
The installed capacity of electricity produced from solar power has increased over the years and will do so even further. A lot of companies are investing in so-called solar parks to create large scale electricity production from solar power. With intermittent energy sources such as solar power comes challenges for the electricity net where storage systems can play an important role to handle these challenges. Storage systems connected to renewable energy can also be a way to increase the economic benefits of a system.  This study investigates whether a lithium-ion battery system connected to a solar park is economically profitable, and in that case under which circumstances. This is done by focusing on a solar park in Uppsala, Sweden, owned by Vasakronan AB. Different grid-connected services provided by the battery that could generate income were identified and chosen for the study which were arbitrage, a local flexibility market and frequency regulation. The usage of the battery for each and a combination of these services were modelled and simulated in Matlab (2020). Each individual case was created as its own model for three different battery capacities (2, 4 & 8 MWh). To investigate whether a case was profitable or not, the internal rate was calculated for each model. This was also done for a longer lifetime of the battery and for lower investment costs as a sensitivity analysis. The results show that a system of this kind is only profitable for one case which is if a 2 MWh battery is used for the frequency regulation services FFR and FCR-D. This results in an internal rate of 6% which is higher than the rate of return of 5% that Vasakronan requires. The conclusions of the study is that it is difficult to make an investment in a battery system that is only charged from a solar park profitable.
182

Is it time for a Social Media Detox? Understanding the journey of intermittent discontinuance of Instagram among Gen Y

Scheppe, Matiena Marie, Seiffen, Anna Luise January 2022 (has links)
Background: Even though the use of social media is one of the most popular activities of our time a decline in the number of active users can be observed at present. Users discontinue using social media platforms temporarily or stop the usage permanently. Thereby, the trend to do a social media detox has emerged, meaning users consciously take a break from social media platforms like Instagram, often for a set period of time. Instagram is one of the most widely used social media platforms of the younger generation, especially Generation Y, and is also noted for its addictive potential. Purpose: Previous studies and scholars have primarily concentrated on the permanent discontinuance of social media, whereby users permanently stop using social media platforms without actively planning to return. Thereby, the focus of the research was often on the social media network Facebook. By studying the journey of intermittent discontinuance of Instagram, the purpose of this research study is to explore Generation Y’s motivation before, experiences and feelings during and post-behavior after a 14-day detox by holistically representing the Instagram Detox Journey. Method: To fulfil the purpose of this thesis being of exploratory nature, a qualitative research design was applied. Empirical data were collected over 4 weeks, beginning with a focus group discussion before, followed by diary research during and 15 in-depth semi- structured interviews after the detox, and concluding with another focus group discussion at a later time. Using an inductive approach, the data was decoded, analysed, and interpreted using thematic analysis. Conclusion: The findings of the study show two main motivations before starting the detox: gaining back control and self-reformation. During the detox, five final themes were identified: mood & satisfaction, technological craving, mental well-being, physical well- being, and social relationships. Lastly, three different post-behaviors after completion were noted: the boomerang effect, conscious consumption, and an attitude change. The findings led to the development of the conceptual framework “Instagram Detox Journey”.
183

Study on Process Performance and Evaluation of Dala Vatten’s Two Municipal Wastewater Treatment Plants.

Amatya, Anjali January 2016 (has links)
Dala Vatten AB has been operating two municipal wastewater treatment plant namely Gagnef wastewater treatment plant and Tällberg wastewater treatment plant since 1970’s and 1950’s respectively in Dalarna, middle of Sweden. These both traditional treatment plants have been updated with continuous and intermittent aerated biological treatment facilities: Moving bed biofilm reactor (MBBR) in 2012 and 2007 respectively. Recently, more detailed process performance and evaluation of both plants is required focusing on energy consumption. The objective of this master thesis is thus to investigate the opportunities in reducing energy consumption from both plants to save operation cost, identify the opportunities for chemical saving, if possible reduce the excess sludge so produced from the plant and potential optimization of the process for its plant’s sustainability. The laboratory study was made in May and August, 2015 with grab sampling and flow proportional sampling method. The analysation was carried out with several wastewater parameters: BOD7, COD, TOC, TP, NH4-N and TN with Hach Lange analysing method. Results showed that both continue and intermittent aerated plants have higher process performance with lower effluent organic (BOD7, COD) and TP loading to the recipient. Gagnef WWTP with continuous aeration has demonstrated an excessive use of chemical, sludge production and high-energy consumption by the blower serving MBBR during the studied period. By contrast, Tällberg WWTP with intermittent aeration has proved to be successful in terms of lower energy consumption by the blower serving the MBBR but failed to show improved specific energy efficiency for each pollutant load during the studied period. The recommendation in improvising energy saving and saving operation cost at both treatment plants was put forward.
184

Improvement of Biological Processes of Inland Municipal Wastewater Treatment Plant.

Li, Wen January 2016 (has links)
This master thesis gives an account for various aeration schemes that are utilized in conventional activated sludge treatment process in a wastewater treatment plant. By altering between different aeration schemes, the project aimed at reducing energy consumption along with maintaining the treatment performance at the plant. A series of experiments on the treatment performance over several different aeration schemes thus has been conducted on site at Solviken in Mora, Sweden. The project is basically a case study where no parameters were manually controlled except for the aeration schemes at the plant. Energy consumption reduction is logically relative to the ratio between aeration and non-aeration intervals. Several criteria were tested in regards to the treatment performance, including pH value, organic matters, phosphorus substances and microorganisms. The study has come up with a superior aeration scheme for the plant, as well as indicated processes that can be improved at the plant.
185

Vagal Afferent Innervation and Remodeling in the Aortic Arch of Young-Adult Fischer 344 Rats Following Chronic Intermittent Hypoxia

Ai, J., Wurster, R. D., Harden, S. W., Cheng, Z. J. 01 December 2009 (has links)
Previously, we have shown that chronic intermittent hypoxia (CIH) impairs baroreflex control of heart rate and augments aortic baroreceptor afferent function. In the present study, we examined whether CIH induces structural changes of aortic afferent axons and terminals. Young-adult Fischer 344 (F344, 4 months old) rats were exposed to room air (RA) or CIH for 35-45 days. After 14-24 days of exposure, they received tracer DiI injection into the left nodose ganglion to anterogradely label vagal afferent nerves. After surgery, animals were returned to their cages to continue RA or CIH exposure. Twenty-one days after DiI injection, the animals were sacrificed and the aortic arch was examined using confocal microscopy. In both RA and CIH rats, we found that DiI-labeled vagal afferent axons entered the wall of the aortic arch, then fanned out and branched into large receptive fields with numerous terminals (flower-sprays, end-nets and free endings). Vagal afferent axons projected much more to the anterior wall than to the posterior wall. In general, the flower-sprays, end-nets and free endings were widely and similarly distributed in the aortic arch of both groups. However, several salient differences between RA and CIH rats were found. Compared to RA control, CIH rats appeared to have larger vagal afferent receptive fields. The CIH rats had many abnormal flower-sprays, end-nets, and free endings which were intermingled and diffused into "bush-like" structures. However, the total number of flower-sprays was comparable (P>0.05). Since there was a large variance of the size of flower-sprays, we only sampled the 10 largest flower-sprays from each animal. CIH substantially increased the size of large flower-sprays (P<0.01). Numerous free endings with enlarged varicosities were identified, resembling axonal sprouting structures. Taken together, our data indicate that CIH induces significant remodeling of afferent terminal structures in the aortic arch of F344 rats. We suggest that such an enlargement of vagal afferent terminals may contribute to altered aortic baroreceptor function following CIH.
186

Successful Stepdown Treatment of Pulmonary Histoplasmosis With Thrice-Weekly Liposomal Amphotericin B in a Hospital-Associated, Outpatient Infusion Centre: A Case Report

Lewis, P. O., Khan, I., Patel, P. 01 April 2018 (has links)
What is known and objective: Amphotericin is the preferred treatment for pulmonary histoplasmosis during pregnancy. The long half-life of amphotericin supports less than daily administration. Case summary: A 28-year-old pregnant woman diagnosed with recurrent pulmonary histoplasmosis was initiated on liposomal amphotericin 250 mg (4 mg/kg) intravenously daily. After 2 weeks, the patient was discharged and successfully received 250 mg thrice weekly at a hospital-associated outpatient infusion centre. After 6 weeks of outpatient treatment, a chest X-ray demonstrated no remaining disease and therapy was discontinued. What is new and conclusion: Administration of thrice-weekly liposomal amphotericin in a hospital-associated, outpatient infusion centre may be a promising option for stepdown treatment in patients unable to take itraconazole.
187

Propuesta de modelos de reposición de materiales en una empresa petrolera / Proposal of replenishment of materials models in an oil company

Vivas Chunga, Willie Roy 03 September 2020 (has links)
El presente trabajo de investigación desarrolla una propuesta para mejorar el desempeño de la gestión de inventarios en el almacén de una empresa petrolera, considerando la presencia de demandas no suaves que no se ajustan para ser tratadas como si tuvieran una distribución normal. Una demanda no suave presenta alta variabilidad en la cantidad solicitada y la posibilidad considerable de tener varios periodos sin demanda. El objetivo es mejorar el nivel de servicio al cliente interno sin tener que incrementar el valor de inventario promedio. Se inicia indicando la importancia de la gestión de inventarios en una empresa y explicando cada etapa en la gestión de la demanda, para luego revisar más a detalle los modelos de inventarios tradicionales y así como los que son recomendados para demandas no suaves. En la siguiente parte se examina la situación actual de la gestión de inventarios en el almacén en estudio, obteniendo un diagnóstico de la misma, y exponiendo los aspectos que pueden mejorarse. Por último, se presenta la propuesta que incluye los métodos de pronóstico y los modelos de control de inventarios elegidos según criterios adecuados que consideran la naturaleza y el patrón de la demanda. / This research develops a proposal to improve the performance of inventory management in the warehouse of an oil company, considering the presence of non-smooth demands that do not fit to treat them like if they would have a normal distribution. A non-smooth demand presents high variability on the required quantity and the chance to have several periods without a demand. The objective is to improve the service level for the internal customer without needing to increase the average inventory value. It is started indicating the importance of inventory management in a company and explaining each phase of demand management, then proceeds to review in detail traditional inventory models, as well as, those are recommended for non-smooth demand. The next part examines the current situation of inventory management in the warehouse that is under study, getting a diagnostic of it, and exposing the aspects that can be improved. Finally, is presented the proposal which to include the forecasting methods and the inventory control models, these are chosen according to suitable criteria which to consider the nature and pattern of demand. / Trabajo de investigación
188

Impact of Intermittent Hypoxia on Growth in Very- and Extremely-Preterm Infants

Horgan, Megan C. 30 December 2020 (has links)
Background. Premature infants are at risk for many complications. Among these, growth failure and intermittent hypoxia (IH) can independently impact the outcomes of other comorbidities. Recent data suggest that IH may directly affect postnatal growth. Our study aims to evaluate the impact of IH on growth velocity in preterm infants. Methods. This prospective cohort study utilized inpatient oximetry, nutrition, and growth data to evaluate the relationship between IH and growth velocity. Enrolled infants were dichotomized by high- versus low-exposure to IH. This relationship was explored in both unadjusted analyses and generalized linear models with repeated measures. Results. The study population included 19 preterm infants, with average birth gestational age of 29 weeks, each contributing one or more measures of weekly data. Infants in the high-exposure cohort had lower birth weight, higher rates of bronchopulmonary dysplasia, and longer duration of respiratory support and caffeine treatment. The unadjusted analysis revealed a marginally significant trend towards higher IH rates during weeks of slower growth. The logistic regression with repeated measures analysis also supported increased odds of slower growth associated with higher IH rates, but this relationship was also only marginally significant. Conclusion. Our study suggests a relationship between exposure to IH and slower growth velocity in preterm infants. The prospectively collected data allowed for accurate measures of IH, growth, and nutrition, but the small sample size likely contributed to the lack of significance of our results.
189

Upplevelsen av regelbunden behandling med Simdax hos personer med kronisk hjärtsvikt : intervjustudie

Friis, Susanne, Johansson, Erica January 2018 (has links)
SAMMANFATTNING  Bakgrund: Hjärtsvikt är en allvarlig och progressiv sjukdom som har invalidiserande symtom vilket påverkar patientens mående och livssituation negativt. Hjärtsvikt definieras som en otillräcklig hjärtminutvolym eller förhöjda fyllnadstryck med bevarad hjärtminutvolym. Vid försämrad hjärtfunktion ökar symtom, återinläggningar och lidandet för individen och är förenat med hög mortalitet. Vanliga symtom på hjärtsvikt är dyspné, ortopné, benödem och trötthet. Andra symtom som också förekommer dock inte lika omnämnda är nedsatt aptit och viktnedgång, förvirring, depression, dålig sömn, yrsel och koncentrationssvårigheter. Målen vid hjärtsvikt är att lindra de symtom som förekommer, förbättra personens livskvalitet, förhindra progress, minska behovet av vård på sjukhus samt öka livsförlängden. Simdax®. är ett läkemedel med den aktiva substansen levosimendan som ges intravenöst under 24 timmar och stärker hjärtats pumpförmåga. Simdax® har visats ge förbättrad hemodynamik och stärker hjärtats ejektionsfraktion samt minskar mortaliteten vid akut hjärtsvikt jämfört med annan inotrop behandling. Dock skiljer rutiner och rekommendationer av användandet av denna medicin sig åt på klinikerna i Sverige och enligt Socialstyrelsen behövs mer forskningsunderlag för vidare riktlinjer.  Syfte: Syftet var att beskriva hur personer med kronisk hjärtsvikt upplever att behandlas regelbundet med Simdax®.  Metod: Vald metod innebar en kvalitativ, induktiv ansats. Information inhämtades via semistrukturerade intervjuer. Sex intervjuer genomfördes på en klinik i södra Sverige.  Resultat: Alla forskningspersoner uttryckte en positiv effekt av att få regelbunden behandling med Simdax®. De beskrev lindring av symtom vilket gjorde att de mådde bättre både fysiskt och mentalt. Utöver symtomlindring upplevde forskningspersonerna att de inte längre hade behov av akuta återinläggningar i sjukvården till följd av försämring av sin hjärtsvikt vilket i sig var värdefullt för dem. De upplevda effekterna visade sig ha vidare positiv verkan att det ökade deras möjligheter att delta i aktiviteter som var betydelsefulla för dem. Forskningspersonerna upplevde även ett förbättrat humör som påverkade deras sociala situation positivt.  Slutsats: Regelbunden behandling med Simdax® upplevdes ge symtomlindring samt förbättring av fysisk och mental funktion. Således kunde detta vara en bra behandlingsregim för personer med hjärtsvikt i symtomlindrande syfte men även kunna minska risken för återinläggningar på grund av försämring.  Nyckelord: Simdax®, regelbunden, kronisk hjärtsvikt, upplevelse. / ABSTRACT  Background: Heart failure is a serious and progressive disease that has invalidating symptoms which adversely affects the patient's mood and life situation. Heart failure is defined as an insufficient cardiac output or elevated fill pressure with preserved cardiac output. In case of deterioration of cardiac function, symptoms, relapses and suffering to the individual increase and are associated with high mortality. Common symptoms of heart failure are dyspnea, orthopedics, oedema and fatigue. However, other symptoms that are not mentioned above are reduced appetite and weight loss, confusion, depression, poor sleep, dizziness and concentration difficulties. The goals of heart failure are to relieve the symptoms that occur, improve the quality of life, prevent progress, reduce the need for care in hospitals and prolong life. Simdax®. is a medicine with the active substance levosimendan given intravenously for 24 hours and strengthens the heart's pump capacity. Use of this has shown improved hemodynamics and strengthens the heart ejection fraction and reduces the mortality of acute heart failure compared with other inotropic treatment. However, routines and recommendations of the use of this medicine differ in the clinics in Sweden and, according to the National Board of Health, more research bases are needed for further guidelines.  Aim: The aim was to examine how patients with heart failure experience intermittent treatment with Simdax.  Method: Chosen method was qualitative, inductive approach through semi-structured interviews. Six interviews were conducted in southern part of Sweden.  Result: All interviewed expressed a positive effect of receiving regular treatment with Simdax®. They described relief of symptoms which made them feel better both physically and mentally. In addition to symptom relief, the participant felt that they no longer needed emergency reinstatement, which was valuable to them. The perceived effects also proved to have a positive effect that increased their ability to participate in activities that were important to them. They also experienced a better temper that had a positive effect om their social relations.  Conclusion: Regular treatment with Simdax® was found to provide symptom relief and improvements in physical and mental capacities. Thus, this could be a good treatment regimen for people with heart failure for symptomatic purposes but may also reduce the risk of rehospitalization due to deterioration.  Keywords: Simdax®, intermittent, chronic heart failure, experience.
190

Development of Electrochemical Sensors with Enhanced Specificity and Temporal Resolution for Biological Applications

Santos Cancel, Mirelis 11 June 2019 (has links)
No description available.

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