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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

Bulleråtgärder vid kapsåg / Noise reduction at crosscut saw

Axén, Evelina, Jonasson, Ida January 2006 (has links)
<p>Uppsatsen behandlar bullerdämpning vid kap på ProfilGruppen Extrusions AB i Åseda. Problemen med ljudnivån beror bland annat på stomljudet som alstras av kapen i de långa profilerna. För att sänka ljudnivån har fastklampningskonstruktioner tagits fram som dämpar stomljudet och förslag på vidare åtgärder rapporterats.</p><p>Försök och jämförande mätningar av ljudnivån har utförts för att få ett bra underlag att utvärdera. Resultaten av försöken med viskoelastisk plast som dämpelement visar en viss dämpning. Dämpningen kan med all sannolikhet bli större med användning av tjockare dämpelement.</p> / <p>This project is about noise reduction of a cross cut saw at ProfilGruppen Extrusions AB, Åseda. The problems with the sound level depend on the structure-borne sound that generates in the long profiles. To lower the sound level have press clamp constructions been developed which reduce and further attends have been suggested.</p><p>Attempts and comperative measurings of the sound level have been evaluated. The results of the comperative measurings with viscoelastic plastic as damping element display certain damping. The damping can in all probability become larger using a thicker damping element.</p>
142

MODEL ANALYSIS AND PREDICTIVE CONTROL OF DOUBLE ELECTRODE SUBMERGED ARC WELDING PROCESS FOR FILLET JOINTS WITH ROOT OPENING

Lu, Yi 01 January 2014 (has links)
Submerged Arc Welding (SAW) for fillet joints is one of the major applications in the shipbuilding industry. Due to the requirement for the weld size, a sufficient amount of metal must be deposited. In conventional SAW process, the heat input is proportional to the amount of metal melted and is thus determined by the required weld size. To meet this requirement, an excessive amount of heat is applied causing large distortions on the welded structures whose follow-up straightening is highly costly. In order to reduce the needed heat input, Double-Electrode (DE) technology has been practiced creating the Double-Electrode SAW (DE-SAW) method for fillet joints. The reduction in the heat input, however, also reduces the penetration capability of the process, and the ability to produce required weld beads has to be compromised. To eliminate the unwanted side effect after using DE-SAW, a root opening between the panel and the tee has been proposed in this dissertation to form a modified fillet joint design. Experimental results verified that the use of root opening improves the ability of DE-SAW to produce the required weld beads at reduced heat input and penetration capability. Unfortunately, the use of root opening decreases the stability of the process significantly. To control the heat input at a minimally necessary level that guarantees the weld size and meanwhile the process stability, a feedback is needed to control the currents at their desired levels. To this end, the fillet DE-SAW process is modeled and a multivariable predictive control algorithm is developed based on the process model. Major parameters including the root opening size, travel speed and heat input level have been selected/optimized/minimized to produce required fillet weld beads with a minimized heat input based on qualitative and quantitative analyses. At the end of this dissertation, a series of experiments validated the feasibility and repeatability of the predictive control based DE-SAW process for fillet joints with root opening.
143

Acoustic wave and bond rupture based biosensor-- principle and development : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Massey University, Palmerston North, New Zealand

Hirst, Evan January 2009 (has links)
Bond rupture is an experimental methodology that is used to augment a conventional mass balance biosensor. A good point-of-care biosensor is fast, reliable, simple, cost-effective, and detects low concentrations of the target analyte. Biosensor development is a multidisciplinary field and bond rupture testing is of technical interest to many groups. The Bond rupture methodology endows a mass probe with the ability to discern bond strength. The recognition of specific bonds by mass loading is separated from erroneous non-specific binding by a probe of the force between the analyte and the transducer. Bond rupture is achieved by acoustic excitation of the point of attachment. The force is incremented gradually until rupture occurs. The advancement of bond rupture biosensors beyond the lab requires improved understanding of the mechanisms of bond rupture by base excitation, the transducers, and the supporting hardware. Bond rupture has traditionally been used in conjunction with the Quartz Crystal Microbalance (QCM). There exists, however, a variety of sensors and transducers to which the bond rupture methodology could be applied. The time, cost and experience required for comprehensive investigation of all avenues is prohibitive. To further the development of bond rupture characteristic experiments are designed and carried out on the QCM platform. Numerical simulations are constructed which model the current bond rupture approach. This work is limited to the simulation of bond rupture by base excitation. From the results of the experimental investigation a number of improvements to the bond rupture technique are proposed. Improvements are tested by simulation and the Surface Acoustic Wave (SAW) device is selected to advance the bond rupture craft. A prototype SAW bond rupture device is designed. The prototype device is manufactured and tested, confirming the principle of SAW bond rupture. Future work is required to progress the SAW bond rupture methodology before possible integration with other sensor systems. Because of this work, and the evaluation of the SAW bond rupture prototype, much is learned about the advancement of SAW device bond rupture.
144

Effect of 5[alpha]-reductase inhibitors on LNCaP cells, Syrian hamster flank organs, and TRAMP mice prostate cancer

Opoku-Acheampong, Alexander Boadu January 1900 (has links)
Doctor of Philosophy / Department of Human Nutrition / Brian L. Lindshield / The growth-inhibitory effect of saw palmetto supplements (SPS) with high long-chain fatty acids (FA)-low phytosterols (HLLP), high long-chain FA-high phytosterols (HLHP), and high medium-chain FA-low phytosterols (HMLP) was determined using androgen-sensitive LNCaP prostate cancer (PCa) cells and Syrian hamster flank organs. In vitro, all three SPS at high concentrations significantly decreased dihydrotestosterone-stimulated LNCaP cell number. HMLP and HLLP at high concentrations significantly decreased, but HLHP which significantly increased testosterone-stimulated LNCaP cell number. In Syrian hamsters, all three SPS treatments caused notable, but nonsignificant reduction in the difference between the left and right flank organ growth in the testosterone-, but not dihydrotestosterone-treated SPS groups. Results suggest SPS might be a mild 5-alpha-reductase (5-alpha-R) inhibitor. The pharmaceuticals finasteride inhibits 5-alpha-R2, and dutasteride inhibits 5-alpha-R1 and 5-alpha-R2 isoenzymes. Because finasteride inhibits only 5-alpha-R2, we hypothesized that it would not be as efficacious in preventing PCa development and/or progression in TRAMP mice as dutasteride. Six-week-old C57BL/6 TRAMP x FVB male mice were randomized to control, pre- and post- finasteride and dutasteride diet groups that began at 6 and 12 weeks of age, respectively, and terminated at 20 weeks of age. Pre and post groups received drugs before and after mice were expected to develop PCa, respectively. Post-Dutasteride treatment was significantly more effective than Pre-Dutasteride; and dutasteride treatments significantly more effective than finasteride treatments in decreasing prostatic intraepithelial neoplasia progression and PCa development. The finasteride groups and the Pre-Dutasteride group had significantly increased incidence of poorly differentiated PCa versus control. Androgen receptor and Ki-67 protein, DNA fragmentation from apoptosis, 5-alpha-R1 and 5-alpha-R2 mRNA levels were determined in mice with genitourinary weight less than 1 gram and greater than 1 gram to elucidate the discordant response in Pre-Dutasteride and finasteride groups, and Post-Dutasteride’s efficacy. Results suggest the difference in genitourinary weights is influenced more by proliferation, rather than androgen receptor and apoptosis in tumor. Mice age may not be significantly important in regulating proliferation, androgen receptor and apoptosis to promote tumor growth. In conclusion, the results with 5-alpha-reductase inhibitors may support the therapeutic use of dutasteride, but not finasteride, or saw palmetto supplements.
145

Reconstruindo-se a Função de Densidade Óssea Utilizando-se Triângulos de Bézier em Dados Desestruturados para Aprimorar o Processo de Diagnóstico da Osteoporose

CASTRO, Pedro Machado Manhães de January 2007 (has links)
Made available in DSpace on 2014-06-12T16:00:19Z (GMT). No. of bitstreams: 2 arquivo6372_1.pdf: 2413746 bytes, checksum: f2dce473f73c4dff94e0ee8f8ad4fec9 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2007 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Osteoporosis is a disease characterized by a reduction in bone mineral density and disruption of bone microarchitecture. It is the most common of the metabolic bone diseases, affecting more than 10,000,000 Brazilians. Despite being of paediatric origin, its symptoms are rarely manifested in childhood. However, the illness becomes increasingly problematic as the individual grows older, causing serious geriatric symptoms. As life expectancy increases, geriatric illnesses become a predominant factor in health care. An accurate diagnosis is therefore extremely important. Currently, the methods of diagnosis of osteoporosis are relatively efficient, albeit substantially inaccurate. For example, people with similar characteristics may have different diagnoses. By using a database of bone mineral density samples, this work presents a mathematical modeling able to produce a more accurate and less ambiguous diagnosis of osteoporosis. Several techniques of mathematical modeling were grouped around this objective. With the model in hand, this work raises new questions for the researcher concerned with the relationship between medicine and computer science. This work may be extended to solve similar problems in the medical domain, as well as in oceanography, meteorology, and others
146

PERLA Ústí nad Orlicí / PEARL Ústí nad Orlicí

Tomková, Iva January 2016 (has links)
The object of the study is urban planning - architectural design strategy of conversion and revitalization of the factory PEARL 01 in Usti nad Orlici. The area of the site is about 3 hectares, an area eight times larger than the actual main square in the town. Most of the land is owned by the city. Current status of the area does not match the aesthetic or functional demands placed on this space, which is intended for expansion of the city center, whose current capacity does not match the needs of even the size of the city. Textile industry and Perla itself played an important role in the history of the region and influenced the lives of most local citizens. Therefore, the proposal seeks to retain as much of the original structure as possivle and with them the charm and spirit of the original factory and its buildings. The area is cleaned up, breathes and becomes in the first time in history a part of the urban space, and not a big barrier in its center.
147

Optimalizace technologie laserového dělení trubek se čtvercovým průřezem / Optimization of the laser cutting technology of tubes with a square cross section

Podaný, Petr January 2018 (has links)
The master thesis deals with the design and manufacture of tabbed joint in the profile with a square cross section using laser cutting. They examine their suitability and impact on the following MAG welding operation in terms of efficiency and accuracy. The theoretical part provides basic information about lasers used in industry and laser cutting methods. There is also a section dedicated to laser apparatus for tube cutting along with problematic about the laser cutting profiles. The experimental part describes the procedure of designing tabbed joint, making samples and measuring them. In the end, the individual samples are compared in terms of angular deflection after welding. The thesis also contains a technical-economic evaluation, where the costs of individual operations are quantified.
148

Predikce řezných sil a výkonů při řezání kotoučovou pilou / Prediction of cutting forces and powers when sawing with a circular saw

Skryja, Jan January 2019 (has links)
This thesis deals with the cutting of steel thin-walled parts by slitting saw. Its subject is to study and test of cutting edges of slitting saws with a goal to reduce cutting forces to a minimum. The thesis is divided into the theoretical and practical part. In the theoretical part, existing knowledge about slitting saws and general cutting technology is analyzed. In the practical part testing of four slitting saws with different geometries of cutting edges during machining of chosen thin-walled part is performed. The performed measurements show that by the proper choice of the geometry of cutting edge, the cutting force can be reduced approximately by 30 %.
149

Correlation between saw blade width and kerf width

Menschel, Melissa 16 July 2020 (has links)
Previous studies of saw marks have primarily focused on morphological characteristics and their utility in identifying saws suspected to have been utilized in cases of criminal dismemberment. The present study examined the extent to which metric analysis may be used to correlate saw blades measurements of kerf width. A sample of 56 partially defleshed white-tailed deer (Odocoileus virginianus) limbs were utilized as a proxy for human remains. The partial limbs were cut using a variety of commercially available saws, including 11 manual-powered saws and 5 mechanical-powered saws. A total of 500 false start kerfs (FSKs) were measured using digital calipers. Two experiments were performed, with the first test examining the kerf widths of false starts produced on specimens that were restrained using clamps, while the second test analyzed the kerf widths of false starts produced on minimally restrained specimens. Statistical analysis using Hierarchical Linear Modeling indicated a positive relationship between saw blade width (mm) and minimum kerf width (MKW), with the model estimating that MKWs would increase by 1.61 mm for every millimeter increase in blade width. Results from the models indicated that blade width (p<0.001) and the difference between mechanical- and manual-powered saws (p=0.029) were considered statistically significant. A comparison of MKWs produced using manual-powered saws on unrestrained and restrained bones suggests that restraint condition (p=0.009) is statistically significant. In comparisons of MKWs to blade widths, the average ratio for used saws was 2.7% greater than the average ratio for new saws. The mode of the ratios was approximately 1.4, supporting the general rule that MKW does not exceed 1.5 times saw blade width.
150

A Novel Nonlinear Mason Model And Nonlinear Distortion Characterization For Surface Acoustic Wave Duplexers

Chen, Li 01 January 2013 (has links)
Surface acoustic wave (SAW) technology has been in use for well over one century. In the last few decades, due to its low cost and high performance, this technology has been widely adopted in modern wireless communication systems, to build filtering devices at radio frequency (RF). SAW filters and duplexers can be virtually found inside every mobile handset. SAW devices are traditionally recognized as passive devices with high linear signal processing behavior. However, recent deployments of third generation (3G) and fourth generation (4G) mobile networks require the handsets to handle an increasing number of frequency bands with more complex modulation /demodulation schemes and higher data rate for more subscribers. These requirements directly demand more stringent linearity specifications on the front end devices, including the SAW duplexers. In the past, SAW duplexer design was based on empirically obtained design rules to meet the linearity specifications. Lack of predictability and an understanding of the root cause of the nonlinearity have limited the potential applications of SAW duplexers. Therefore, research on the nonlinearity characterization and an accurate modeling of SAW nonlinearity for mobile device applications are very much needed. The Ph.D. work presented here primarily focuses on developing a general nonlinear model for SAW resonators/duplexers. Their nonlinear characteristics were investigated by measuring the harmonic and intermodulation distortions of resonators. A nonlinear Mason model is developed and the characterization results are integrated into SAW duplexer design flows to help to simulate the nonlinear effects accurately and improve the linearity performance of the products. iv In this dissertation, first, a novel nonlinear Mason equivalent circuit model including a third order nonlinear coefficient in the wave propagation is presented. Next, the nonlinear distortions of SAW resonators are analyzed by measuring large-signal harmonic and intermodulation spurious emission on resonators using a wafer probe station. The influence of the setups on the measurement reliability and reproducibility is discussed. Further, the nonlinear Mason model is validated by comparing its simulation results with harmonic and intermodulation measurements on SAW resonators and a WCDMA Band 5 duplexer. The Mason model developed and presented here is the first and only nonlinear physical model for SAW devices based on the equivalent circuit approach. By using this new model, good simulation measurement agreements are obtained on both harmonic and intermodulation distortions for SAW resonators and duplexers. These outcomes demonstrate the validity of the research on both the characterization and modeling of SAW devices. The result obtained confirms that the assumption of the representation of the 3 rd order nonlinearity in the propagation by a single coefficient is valid

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