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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.
21

Leveraging Overtime Hours to Fit an Additional Arthroplasty Surgery Per Day: A Feasibility Study

Khalaf, Georges 30 June 2023 (has links)
The COVID-19 pandemic resulted in the cancellation of many hip and knee replacements, creating a backlog of patients on top of an existing long waiting list. To reduce wait lists with no financial burden, we aim to evaluate the possibility of leveraging our previous efficiency-improving work to add an additional case to a typical 4-joint day with no extra cost. To do this, 761 total operation days were analyzed from 2012 to 2019, capturing variables such as case number, success (completion of 4 cases before 3:45pm), and patient out of room time. Linear regression was used on 301 successful days to predict 5th cases, while overtime hours saved were calculated from the remaining unsuccessful days. Different cost distributions were then analyzed for a 77% 4-joint day success rate (our baseline), and a 100% 4-joint day success rate. Our predictions show that increasing performance to a 77% success rate can lead to approximately 35 extra cases per year at our institution, while a 100% success rate can produce 56 extra cases per year. Overall, this shows the extent of resources wasted by overtime costs, and the potential for their use in reducing wait times. Future work can explore optimal staffing procedures to account for these extra cases.
22

Design of a Cyclic Sliding, Dynamically Loaded Wear Testing Device for the Evaluation of Total Knee Replacement Materials

Thompson, Matthew Thomas 08 August 2001 (has links)
During normal walking, the relative motion of the human knee involves flexion/extension, anterior/posterior sliding, and medial/lateral rotation. As well, the knee experiences a complex, dynamic loading curve with a peak of up to seven times body weight. However, most wear testing machines that have been used to evaluate total knee replacement materials are unidirectional and/or apply only static force. This thesis presents an alternate wear testing device capable of simulating the most prevalent motions of the knee, and applying physiologically-correct loading to the material interface. By incorporating a CoCr disc, an UHMWPE block, stepping motors, pneumatic components, computer control, and linear tables in an x-y configuration, the device is capable of quickly screening new and alternative materials to UHMWPE before evaluating them on a much more expensive knee simulator. In addition, flexibility of the device allows programming of many different motion and loading configurations permitting materials testing under only certain circumstances, or evaluating the effects on wear of specific motions. Design rationale, development, validation, and future recommendations are presented. / Master of Science
23

Performance and safety of centrifugal chillers using hydrocarbons.

Tadros, Amir, The University of New South Wales. School of Mechanical & Manufacturing Engineering, UNSW January 2008 (has links)
The high ozone depletion and global warming potentials of fluorocarbon refrigerants have resulted in prohibitions and restrictions in many markets. Hydrocarbon refrigerants have low environmental impacts and are successfully used in domestic refrigerators and car air conditioners but replacing fluorocarbons in centrifugal chillers for air conditioning applications is unknown. Hydrocarbon replacements need a heat transfer correlation for refrigerant in flooded evaporators and predictions for operating conditions, capacity and performance. Safety precautions for large quantities of hydrocarbon refrigerants are needed and control of overpressure in plantrooms requires accurate prediction. Reliable correlations exist for forced convection in a single phase flow, condensation outside tubes and evaporation off sprayed tubes. For flooded evaporators this thesis proposes a new correlation for forced convection boiling of any refrigerant. An enhancement factor is combined with a modified Chen coefficient using recent pool boiling and forced convection correlations outside tubes. This correlates within typically a factor of two to known boiling literature measurements for CFC-113, CFC-11, HCFC-123, HFC-134a and HC-601. The operating conditions, capacity and performance of replacement hydrocarbons in centrifugal chillers were predicted using fluorocarbon performance as a model. With the new heat transfer correlation hydrocarbon predictions for flooded evaporators were made. For any fluorocarbon refrigerant there exists a replacement mixture of hydrocarbons which with a rotor speed increase about 40% gives the same cooling capacity in the same centrifugal chiller under the same operating conditions. For example replacing HCFC-123 in a flooded evaporator with HC-601/602 [90.4/9.6] and increasing the rotor speed by 43% will increase the coefficient of performance by 4.5% at the same cooling capacity. The maximum plantroom overpressure considered was from leakage and ignition of a uniform air/refrigerant mixture with maximum laminar burning velocity. Flow was modelled using a turbulence viscosity due to Launder and Spalding and turbulent deflagration using a reaction progress variable after Zimont. These partial differential equations were solved approximately for two and three dimensional geometries using finite volume methods from the Fluent program suite. Simple overpressure predictions from maximum flame area approximations agreed with Fluent results within 13.7% promising safe plantroom design without months of computer calculation.
24

Performance and safety of centrifugal chillers using hydrocarbons.

Tadros, Amir, The University of New South Wales. School of Mechanical & Manufacturing Engineering, UNSW January 2008 (has links)
The high ozone depletion and global warming potentials of fluorocarbon refrigerants have resulted in prohibitions and restrictions in many markets. Hydrocarbon refrigerants have low environmental impacts and are successfully used in domestic refrigerators and car air conditioners but replacing fluorocarbons in centrifugal chillers for air conditioning applications is unknown. Hydrocarbon replacements need a heat transfer correlation for refrigerant in flooded evaporators and predictions for operating conditions, capacity and performance. Safety precautions for large quantities of hydrocarbon refrigerants are needed and control of overpressure in plantrooms requires accurate prediction. Reliable correlations exist for forced convection in a single phase flow, condensation outside tubes and evaporation off sprayed tubes. For flooded evaporators this thesis proposes a new correlation for forced convection boiling of any refrigerant. An enhancement factor is combined with a modified Chen coefficient using recent pool boiling and forced convection correlations outside tubes. This correlates within typically a factor of two to known boiling literature measurements for CFC-113, CFC-11, HCFC-123, HFC-134a and HC-601. The operating conditions, capacity and performance of replacement hydrocarbons in centrifugal chillers were predicted using fluorocarbon performance as a model. With the new heat transfer correlation hydrocarbon predictions for flooded evaporators were made. For any fluorocarbon refrigerant there exists a replacement mixture of hydrocarbons which with a rotor speed increase about 40% gives the same cooling capacity in the same centrifugal chiller under the same operating conditions. For example replacing HCFC-123 in a flooded evaporator with HC-601/602 [90.4/9.6] and increasing the rotor speed by 43% will increase the coefficient of performance by 4.5% at the same cooling capacity. The maximum plantroom overpressure considered was from leakage and ignition of a uniform air/refrigerant mixture with maximum laminar burning velocity. Flow was modelled using a turbulence viscosity due to Launder and Spalding and turbulent deflagration using a reaction progress variable after Zimont. These partial differential equations were solved approximately for two and three dimensional geometries using finite volume methods from the Fluent program suite. Simple overpressure predictions from maximum flame area approximations agreed with Fluent results within 13.7% promising safe plantroom design without months of computer calculation.
25

Biomass production and changes in soil water with cover crop species and mixtures following no-till winter wheat

Kuykendall, Matti Beth January 1900 (has links)
Master of Science / Department of Agronomy / P. V. Vara Prasad, / Kraig L. Roozeboom / Replacing fallow with cover crops can provide many benefits, including improved soil quality and reduced nitrogen fertilizer requirements. The addition of cover crops into no-till systems has become popular in recent years as a means of increasing cropping system intensity and diversity. A primary concern of producers in the Great Plains is the possibility that cover crops may reduce the amount of soil water stored in the profile for the next grain crop, potentially reducing yields. Multi-species cover crop mixtures that enhance the ecological stability and resilience of cover crop communities may produce greater and more consistent biomass than single species. Field experiments were established in 2013 and 2014 near Belleville and Manhattan, KS following winter wheat (Triticum aestivum L.) harvest to evaluate the effect of cover crop species and species complexity on changes in soil profile water content and water use efficiency. Along with a chemical fallow control, ten cover crop treatments were tested: six single species, two-three component mixes, a mix of six species, and a mix of nine species. Volumetric water content was measured using a neutron probe and a Field Scout TDR 300. Similar data were collected in 2014 from an experiment established in 2007 comparing fallow, double-cropped soybean, and four cover crop types (summer and winter legumes and non-legumes) in a no-till winter wheat-grain sorghum-soybean cropping system near Manhattan, KS. Results from both studies showed that grasses produced the most dry matter with the highest water use efficiency (up to 618 kg cm-1). Fallow lost up to 7.9 cm less water than all cover crop treatments throughout cover crop growth and in the fall, but captured up to 3.4 cm less moisture in the spring than the cover crops that added residue to the soil surface. Brassica species extracted water from deeper in the soil profile than the other cover crop species. Species complexity affected water use only relative to the proportions and productivity of their individual components, with no advantage in water use efficiency for the more complex mixtures.
26

Hodnocení kvality pooperační analgetické péče / Assesment of quality of postoperative analgesic care

Rákosová, Andrea January 2016 (has links)
Introduction: The acute postoperative pain management is recently a concern of many expert committees and professional associations. The evidence of an increased interest in this issue is the Practice Guidelines for Acute Pain Management released by American Pain Society. According to these recommendations, the pain should be monitored as a fifth vital function. As a logical consequence of modern trends of pain management, Czech Society of Anaesthesiology and Intensive Care Medicine issued guidelines for acute pain management in postoperative setting. This paper is an attempt to describe and evaluate the quality of postoperative analgetic care after total knee and hip replacements in a selected institution's department.………………………………..…………………………………… Methods: The aim of our empirical survey was to assess the level of quality of postoperative care and analgesia in the selected department. We focused mainly on the question of pain trivializing from the nurses side, their approach towards patients suffering from acute pain and, finally, the level of patient's awareness of pain intensity assessment systems and treatment options. Using the quantitative research methods, we evaluated the differences in perceiving of postoperative pain treatment quality from patient's and nurse's point of view. The survey...
27

The production and properties of zinc-nickel and zinc-nickel-manganese electroplate

Kimpton, Harriet J. January 2002 (has links)
The aim of this research proj ect was to produce compositionally modulated zincnickel and zinc-nickel-manganese coatings usi ng a single bath process by variation of the applied electroplating current density. These could then be considered as possible replacements for electroplated cadmium. Zinc-nickel electrodeposits from both a simple bath and one containing the complexant tris(hydroxymethyl)methylamine (TRIS) were produced using either bath or by selective electroplating onto mild steel, 2014-T6 aluminium and 2000 series aluminium alloy connector shells. Zinc-nickelmanganese coatings were electroplated onto mild steel, using both DC and pulse electroplating from sulphate based baths containing either the complexant TRIS or sodium citrate. The coatings and the various electrodeposition processes were evaluated by thickness measurements, cun'ent efficiency calculations, composition detennination using energy dispersive X-ray anal ys is and SEM to examine the morphology. Corrosion characteristics were investigated by neutral salt fog exposure, alternate immersion, atmospheric trials, and electrochemical immersion tests including potential monitoring, galvanic and polarisation measurements. Other properties such as microhardness and surface electrical conductivity were also investigated. Compositionally modulated zinc-nickel and ziJlc-nickel-manganese were successfully deposited from single baths with nickel contents ranging from 5-20% Ni and manganese contents varying from 0-12% Mn. Current efficiency measurements showed the efficiency to be low especially for the zinc-nickel-manganese coatings, which exhibited a distinct morphology when electroplated from the citrate bath. Corrosion testing indicated that both coatings had a lower corrosion resistance than cadmium especially in accelerated tests, with a reduction in corrosion resistance being seen as the nickel content was increased; due to a decrease in density of the electroplate. This, and increasing through-thickness porosity promoted ennoblement of zinc-nickel and zinc-nickel-manganese leading to the coatings becoming nonsacri ficial to the substrate in accelerated tests. Zinc-nickel-manganese showed less white rust than zinc-nickel and exhibited lligher micro-hardness than zinc, cadmium and zinc-nickel. Electrical measurements indicated that both coatings were sufficiently conductive to meet the surface conductivity requirements for use on electrical connector shells.
28

Otěrové částice polyethylenu v okolí kloubních náhrad - jejich vlastnosti, distribuce a možný mechanizmus jejich nežádoucího biologického působení / Polyethylene wear particles around joint replacements - their properties, distribution and possible mechanism of their adverse biological effects

Zolotarevová, Eva January 2010 (has links)
CHARLES UNIVERSITY IN PRAGUE FACULTY OF SCIENCE DEPARTMENT OF BIOCHEMISTRY PRAGUE 2010 Supervisor: Doc. MUDr. Jiří Gallo, PhD. Supervisor-consultant: Prof. RNDr. Gustav Entlicher, CSc. Eva Zolotarevová Summary of PhD Thesis POLYETHYLENE WEAR PARTICLES AROUND TOTAL JOINT REPLACEMENTS - THEIR PROPERTIES, DISTRIBUTION AND POSSIBLE MECHANISM OF THEIR ADVERSE BIOLOGICAL EFFECTS PRAGUE 2010 The research project was supported by the Grant project of National research program II. (no. 2B06096) of the Czech Ministry of Education, Youth and Sports named "Observation and minimization of UHMWPE wear in joint replacements". Front-page picture: Polyethylene wear particle isolated from granuloma tissue surrounding total hip replacement; Electron microscope microphotograph; particle size app. 90 x 80 µm; retouched Eva Zolotarevová Introduction Introduction For many people all over the world a replacement with an implant of irreversibly damaged joint is often the only way how to come back to normal life without pain and mobility limitation. Nowadays, greater and greater requirements are asked of quality of all replacement components, especially in terms of quality of used materials. Biomechanical properties of hip and knee replacements have been already solved. The most often used materials for manufacturing joint...
29

Propuesta de mejora para incrementar el nivel de pedidos perfectos en el almacén de repuestos aplicando Lean Logistics en una empresa de alimentos de consumo masivo / Improvement proposal to increase the level of perfect orders in the spare parts warehouse applying Lean Logistics in a mass consumption food company

Caira Bravo, Karen, Corzo Glandel, Raquel Sharon 20 July 2021 (has links)
En el presente trabajo, se analizarán los principales beneficios de la aplicación de la metodología Lean Logistics en el área de almacén de repuestos en la empresa de consumo masivo. La aplicación de esta metodología está enfocada desde un punto de vista sistémico, con gran alcance de coordinación entre todas las funciones logísticas. Cabe resaltar que la empresa se dedica a la elaboración de alimentos de consumo masivo para su distribución a nivel nacional y en el extranjero. El objetivo principal es incrementar el nivel de pedidos perfectos en el almacén de repuestos aplicando Lean Logistics. Con respecto a la estructura del trabajo, este se divide en cinco capítulos; en el primero, se definen conceptos necesarios para la comprensión del proyecto, en el segundo, se describe la situación del diagnóstico actual, en el tercer capítulo se evaluarán propuestas de solución al problema existente, en el cuarto capítulo se validará la metodología propuesta. Por último, en el capítulo 5, se proporcionarán conclusiones y recomendaciones a partir de todos los argumentos presentados en el proyecto de investigación. Esta conclusión demuestra que el nivel de pedidos perfectos en el almacén de repuestos mejorará con la aplicación de esta metodología. / In this paper, the main benefits of the application of the Lean Logistics methodology in the spare parts warehouse area in the mass consumption company will be analyzed. The application of this methodology is focused from a systemic point of view, with a great scope of coordination between all logistics functions. It should be noted that the company is dedicated to the production of foods for mass consumption for distribution nationally and abroad. The main objective is to increase the level of perfect orders in the spare parts warehouse by applying Lean Logistics. Regarding the structure of the work, this is divided into five chapters; In the first, concepts necessary for understanding the project are defined, in the second, the current diagnosis situation is described, in the third chapter, proposals for solutions to the existing problem will be evaluated, in the fourth chapter the proposed methodology will be validated. Finally, in Chapter 5, conclusions and recommendations will be provided based on all the arguments presented in the research project. This conclusion shows that the level of perfect orders in the spare parts warehouse will improve with the application of this methodology. / Trabajo de Suficiencia Profesional
30

Perceptions of surgical nurses regarding the post-operative pain management of patients after total hip or knee replacement surgery

Kolobe, Litaba Efraim 11 1900 (has links)
The purpose of this study was to explore and describe the surgical nurses’ perceptions about the management of post-operative pain and strategies employed in management of pain in patients who have undergone total hip or knee replacement surgery in King Abdulaziz Medical City, Riyadh, Kingdom of Saudi Arabia. Qualitative, exploratory-descriptive research design was applied. Purposive nonprobability sampling was used and data collected by means of audio-recorded semistructured individual interviews. Data saturation was reached after interviewing twenty surgical nurses. Themes and categories emerged from adopting Creswell’s (2013) “data analysis spiral”. One of the key findings was that patients reportedly experience moderate to severe pain during the first three days after surgery, before it is controlled on mild to moderate levels or before the patient is pain free. Conclusions were drawn, and one of the major ones was that multimodal strategies are employed by the surgical to manage post-operative pain. Recommendations were also made from findings of this study, and one key recommendation was that expatriate nurses to have access to Arabic speakers to overcome language barriers. / Health Studies

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