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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.
141

SBR-technology - use and potential applications for treatment of cold wastewater

Morling, Stig January 2009 (has links)
Biological nutrient removal is used as an indicator of SBR performance at nine different SBRplants operated for a long period at low water temperatures (5 – 10oC). Typically needed aeratedSRT (Solids Residence Time) for complete nitrification is found to be in the range of 6 – 10 days.Biological phosphorus removal has been found to take place at 5oC. The specific nitrification and denitrification rates (g N/kg VSS/h) have been found to besubstantially higher than those found in design recommendations. At temperatures < 10 oC thenitrification rates have been found up to 4 g Nox/kg VSS/h. It has also been possible to establish a relation between the COD/N ratio and the nitrificationrate, showing that the rate increases to high rates when the ratio decreases. Enhanced biological phosphorus removal has been demonstrated at two different plants even atlow water temperatures 5 – 7 oC. Efficient biological nitrogen removal and phosphorus removal has been demonstrated at bothlow water temperatures and in presence of very high Chromium concentrations in inlet water, upto 20 mg Cr/l. The plants operated with a short fill time in comparison with the total cycle time for the SBRprocess have all demonstrated good sludge settling properties, suggesting that the SBR processmay incorporate a good sludge selection performance. Once a flexible operation strategy has been installed (in most cases through PLC systems) it hasbeen possible to meet load variations to maintain good treatment results. This has been found tobe true for most of the plants included in the thesis. Finally, a modified way to assess the energy efficiency for the system is analysed and suggested.Instead of using the traditional ratio kWh/kg BODremoved the use of kWh/kg OCPremoved as a basisfor energy efficiency is used as a far more relevant efficiency measurement. / QC 20100803
142

Diagnosis of Intermittent Faults in Discrete Event Systems

Hong, Hu 20 November 2012 (has links)
Fault diagnosis in discrete event systems is studied using a state-based framework. Faults can be either intermittent or permanent. For intermittent faults, system may recover from faulty behaviour through reset. To diagnose such intermittent faults, fault counters are introduced. Fault counters record the number of intermittent faults which must have occurred according to the output observations. This provides the main diagnosis. They also record the number of possible intermittent faults which may have occurred but cannot be confirmed. This provides auxiliary diagnostic information. Fault diagnosability is then studied. Since faults may be intermittent, they may occur repeatedly. Three different notions are studied: 1-diagnosability, 1,k-diagnosability, and 1,infty-diagnosability, and criteria for each of these notions are obtained. The criteria are expressed in terms of fault counters and extend the diagnosability criteria for permanent faults. The concept of a resonant path is introduced, which plays an important role in studying diagnosability.
143

Diagnosis of Intermittent Faults in Discrete Event Systems

Hong, Hu 20 November 2012 (has links)
Fault diagnosis in discrete event systems is studied using a state-based framework. Faults can be either intermittent or permanent. For intermittent faults, system may recover from faulty behaviour through reset. To diagnose such intermittent faults, fault counters are introduced. Fault counters record the number of intermittent faults which must have occurred according to the output observations. This provides the main diagnosis. They also record the number of possible intermittent faults which may have occurred but cannot be confirmed. This provides auxiliary diagnostic information. Fault diagnosability is then studied. Since faults may be intermittent, they may occur repeatedly. Three different notions are studied: 1-diagnosability, 1,k-diagnosability, and 1,infty-diagnosability, and criteria for each of these notions are obtained. The criteria are expressed in terms of fault counters and extend the diagnosability criteria for permanent faults. The concept of a resonant path is introduced, which plays an important role in studying diagnosability.
144

Stress and Fatigue Analysis of Roller Chain under Varied Loading

Chen, Min-chiang 03 September 2008 (has links)
The stress and fatigue analysis of roller chain under varied loading is investigated in this study. With the dynamic responses of a gear-cam intermittent mechanism, boundary conditions are set up to the finite element model. The commercial MARC finite element method package is used in this work. Stress distribution is our concern. ASME elliptic equation and AGMA allowable contact stress criteria are employed in the fatigue analysis. Results indicate that the maximum of von Mises stress occurs on the contact surface between pins and plates. Besides, the initial failures on this loading are predicted to happen on the plates according to the fatigue analysis.
145

Configuration and Operation of Battery Power Modules

NG, Kong-Soon 23 July 2009 (has links)
A novel battery power system configured by the battery power modules (BPMs) is proposed. Each BPM consists of a single battery pack or a battery bank equipped with an associated DC/DC converter. The output ports of BPMs can be connected in series for the high voltage applications, or in parallel to cope with a higher power or energy. For a large scale battery power system, a number of BPMs can be arrayed with combination of series and parallel connections to meet the load requirements. These all configurations allow the BPMs be operated individually. Consequently, the discharging currents of the batteries can be independently controlled, but coordinated to provide a full amount of the load current. The performances of BPMs connected in both parallel and series at outputs are analyzed theoretically and discussed from the experimental results. Batteries operating independently do not suffer from charge imbalance, and thus can avoid being over-charged or over-discharged, so that the life cycle can be prolonged. Furthermore, sophisticated discharging profiles such as intermittent currents can be realized to equalize the charges and thus to efficiently utilize the available stored energy in batteries. During the operation period, some of the batteries may take rest or be isolated from the system for the open-circuit measurement, facilitating the estimation of the state-of-charge (SOC) and the evaluation of the state-of-health (SOH). With the benefit of independent operation, the BPMs can be discharged with a scheduled current profile, such as intermittent discharging. The investigation results show that the average current plays the most important role in current discharging. By detecting the battery voltage at the break time, an SOC estimation method based on the dynamically changed open-circuit voltage exhibits an acceptable accuracy in a shorter time with considerations of the previous charging/discharging currents and the depth-of- discharge (DOD). In addition, the coulomb counting method can be enhanced by evaluating the SOH at the exhausted and fully charged states, which can be intended on the independently operated BPMs. Through the experiments that emulate practical operations, the SOC estimation methods are verified on lead-acid batteries and lithium-ion batteries to demonstrate the effectiveness and accuracy.
146

Psychological factors associated with walking in patients with Peripheral Arterial Disease

Cunningham, Margaret January 2010 (has links)
Objectives This thesis aimed to explore psychological factors associated with walking behaviour in patients with Peripheral Arterial Disease, within the framework of Leventhal et al’s (1998) Common-sense Model of Self-regulation of Health and Illness. The objective was to identify psychological factors which could be modified to increase walking behaviour in these patients. Method A series of three studies were conducted to achieve these aims. The first study was an exploratory qualitative study, to explore the illness and treatment beliefs and walking behaviour of patients with intermittent claudication. The second study was a cross-sectional postal questionnaire to a cohort of patients with intermittent claudication, which tested the influence of the psychological factors identified in the qualitative study, in a larger sample. The final study was a randomised controlled trial of a brief psychological intervention designed to modify the illness and walking beliefs of patients with intermittent claudication, in order to increase walking behaviour. Results Beliefs about intermittent claudication, and beliefs about walking were both found to be associated with walking behaviour in the qualitative study. The results from the cross-sectional postal questionnaire confirmed this relationship – taken as a set, illness and walking beliefs accurately predicted adherence to minimum walking levels for 93.4% of the sample. The brief psychological intervention successfully modified illness and treatment beliefs and increased walking behaviour in patients newly diagnosed with intermittent claudication. Conclusion This thesis highlights the importance of illness and walking beliefs to the walking behaviour of patients with intermittent claudication. The thesis has added to the body of knowledge about intermittent claudication, and the findings of this thesis have implications for the treatment of patients with intermittent claudication within the health service. Theoretical and clinical implications of this research are discussed.
147

Epidemiological, clinical anf pathogenetic studies of acute intermittent porphyria

Bylesjö, Ingemar January 2008 (has links)
Porphyrias are inherited metabolic disorders characterised by an impairment of heme biosynthesis. Acute intermittent porphyria (AIP) is the most common of the acute porphyrias in Sweden. Acute attacks of AIP are characterised by neuro-psychiatric symptoms, including epileptic seizures. Environmental and acquired factors are related to the induction of symptoms. Acute attacks of AIP are treated with high doses of glucose and/or hematin infusions. The pathogenesis of the neuro-psychiatric symptoms is not known. Reversible white-matter lesions, probably due to vasospasm, have been seen on brain MRI. Similarities between multiple sclerosis (MS) and AIP have previously been described, but to our knowledge no study has investigated whether AIP-gene carriers have white-matter lesions seen on brain MRI or oligoclonal bands (OB) in cerebrospinal fluid (CSF). The percentage of AIP-gene carriers who have experienced epileptic seizures has been calculated at 10-20%, but previous investigations are derived from highly selected clinic-based studies. Studies were therefore undertaken to investigate the prevalence of epileptic seizures, the relationship of seizures to AIP, the type of seizures and the relationship of seizures to other factors such as melatonin. A case report described the disappearance of porphyric attacks after the onset of diabetes mellitus (DM). In our study, we investigated the rate of attacks after the onset of DM. For many years, clinical issues relating to AIP have not been a focal area. We therefore carried out a study to update our knowledge of the clinical course of AIP in order to improve prevention, control and treatment. In our studies of AIP-gene carriers and epileptic seizures, we found that epileptic seizures are less common than has previously been described (3.7%) and they are not very different from what is expected in the general population, but the prevalence of 5.1% of seizures with manifest AIP is higher than in the general population. The seizures may be generalised or partial and the seizure frequency was generally low. The AIP-gene carriers who had had epileptic seizures had a lower melatonin excretion level in their urine compared with gender- and aged-matched AIP-gene carriers’ relatives without epileptic seizures, which may indicate that melatonin plays a possible anti-convulsive role. In our study of AIP and DM, no subject had an attack of AIP after the onset of DM. White-matter lesions on brain MRI were seen in 25% of the AIP-gene carriers examined outside attacks. One carrier had elevated protein levels in the CSF, but no carrier had cells or OB in the CSF. In our population-based study, 356 DNA-confirmed AIP-gene carriers from northern Sweden participated. Manifest AIP (MAIP) was identified in 42%, 65% of whom were women. Eight mutations were found. Women were more severely stricken by AIP attacks in terms of number and duration, hospital admission and early onset. Men (30%) reported most attacks > 40 years of age. The most commonly reported symptoms during attacks were severe abdominal pain (86%), fatigue (42%), constipation (41%), vomiting (36%), muscle pain (30%), psychiatric symptoms (29%), pareses (20%) and sensory impairment (10%). Chronic AIP symptoms were reported by 18%. Precipitating factors were often reported: menstruation (31%), psychological strain (30%), certain drugs and fasting (20%), infection and alcohol (14%), physical strain (12%) and pregnancy (5%). Smoking was more frequent in MAIP and was associated with the number of AIP attacks. Some 30% of MAIP carriers used drugs that were not considered safe (in 1999), mainly diuretics, calcium antagonists and ACE inhibitors. Twenty per cent of MAIP carriers reported that they were receiving a disability pension due to AIP. Elevated levels of ASAT, bile acids, creatinine, creatinine clearance, U-ALA and U-PBG were often found in MAIP-gene carriers. Hypertension, renal impairment and pain in the legs were associated with MAIP. Hepatoma was strikingly over-represented.To summarise; epileptic seizures are less common than has previously been described, melatonin may have an anti-convulsive effect and DM may have a beneficial effect on MAIP-gene carriers. White-matter lesions are seen on brain MRI. The lesions are unspecific but may relate to the patients’ porphyria. AIP is not a harmless disease. A large percentage of the AIP-gene carriers had frequent attacks, severe symptoms, long-lasting fatigue and chronic AIP and women were more severely stricken. Effects on the kidneys, blood pressure and the liver, including HCC, were evident. Measures should be taken to improve the quality of life and prognosis for AIP-gene carriers.
148

Visual control of human gait during locomotor pointing

Popescu, Adrian Unknown Date
No description available.
149

CONTROLLED RELEASE OF OSTEOTROPIC MOLECULES STIMULATES IN VITRO CELLULAR ACTIVITY AND IN VIVO LOCAL BONE REGENERATION

Jeon, Ju Hyeong 01 January 2007 (has links)
Bone defects treatment and reconstructive surgery continues to increase at a significant rate. Current bone defect treatments are autotransplantation, allograft, and xenografts create many problems such as, inflammation, infection and chronic pain. Moreover, allografts and xenografts arouse immune rejection. These problems have led to development of controlled release system for use as alternatives to autografts, allografts and xenografts in bone repair. There have been many approaches for sustained drug delivery in local bone regeneration using biodegradable polymers and osteotropic biomolecules. This dissertation presents new approaches that apply intermittent drug delivery for local bone regeneration. In the first, the osteotropic molecules simvastatin (Sim) or parathyroid hormone (PTH) were released with intermittent profiles. In the second, alternating delivery of Sim and PTH as well as alternating release of the antimicrobial agent cecropin B (CB) with Sim or PTH. An association polymer system of cellulose acetate phthalate (CAP) and Pluronic F-127 (PF-127) was used for the delivery vehicle. Each device showed discrete peaks in release profiles and lasted more than 10 days. Release profiles could be controlled by altering surface area exposed to aqueous environment, number of layers, loading, and blending ratios. Cells were cultured with sustained or intermittent exposure to Sim or PTH at various concentrations, and alternating exposure to CB and Sim or PTH and to Sim and PTH at different concentrations. Low dose Sim and PTH treatments stimulated higher osteoblastic activity than observed in control cultures. Furthermore, intermittent delivery was more effective than sustained exposure. In vivo, newly formed bone was found in animals implanted with both blank Sim-loaded devices. However, a greater anabolic effect was seen for Sim release devices. Further, intermittent release devices stimulated the greatest woven bone thickness, total bone area, and lamellar bone area. These results suggest that intermittent release devices containing a single molecule, Sim or PTH, and alternating release devices containing multiple molecules, CB with Sim or PTH, possess promising potential as a treatment for local bone regeneration.
150

Examination of aerobic and anaerobic contributions to Yo-Yo intermittent recovery level 1 test performance in female adolescent soccer players

Dickau, Leanne 27 April 2011 (has links)
The purpose of the study was to examine the physiological components related to the Yo-Yo intermittent recovery level 1 (YYIRL1) test in female adolescent soccer players. Eighteen female soccer players (age 16.3 ± .77 years) were tested for maximal oxygen uptake (VO2 max) and ventilatory threshold (VT) on a motorized treadmill. Anaerobic power and capacity were assessed by peak power (W) measured during a counter movement jump (CMJ) and performance on an anaerobic speed test (AST), respectively. As well, participants completed the Multistage 20m Shuttle run (Leger). YYIRL1 performance (meters) was significantly correlated to VO2 max (r = .59), VT (r = .42), Peak Power (r = .41), CMJ height (r = .41), AST (r = .52) and the Leger (r = .72, p < .05). Leger performance (m) was significantly correlated to VO2 max (r = .60) and AST (r = .47, p < .05). Multiple stepwise linear regression equations were run with YYIRL1 and Leger as the dependent variables. VO2 max was the only variable that contributed to prediction of YYIRL1 or Leger performance with R2 values of .35 and .36. The results of the study showed that YYIRL1 performance is related to both aerobic and anaerobic variables, although predominantly maximal aerobic power (VO2 max). It is recommended that the YYIRL1 be used when assessing female adolescent soccer players as the results provide evidence that the YYIRL1 is related to anaerobic variables associated with soccer match performance. As well, coaches can efficiently test their athletes in a shorter amount of time compared to the Leger. / Graduate

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