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Jambi, Safa Abdulsalam A. "Investigations into orthodontic anchorage." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/investigations-into-orthodontic-anchorage(b3769a47-e782-4b85-b8b4-21cb186e0fdd).html.
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Background and objectives: The control of anchorage is integral to successful orthodontic treatment. The objective of this research was to undertake three related projects to evaluate methods of increasing anchorage with the aim of adding to orthodontic knowledge and improve methods of treatment delivery. Methods: Two Cochrane systematic reviews were undertaken according to the methods published in the Cochrane Handbook for Systematic Reviews of Interventions, version 5.1.0. The influence of functional appliances on tooth position and the extraction decision was performed as a retrospective study using participants from a completed multicentre randomized trial. Results: 1- Statistically and clinically significant differences were found between the mean values of distal molar movement when surgical anchorage and conventional anchorage were compared. 2- Statistically significant differences were found between the mean values of distal molar movement and mesial upper incisor movement when intraoral distalising appliances and cervical headgear were compared.3- Fixed and removable functional appliances are equally effective in anchorage preparation. The type of functional appliance and time spent in Phase I treatment influenced the amount of lower incisor proclination. Conclusions: 1- Surgical anchorage is more effective than headgear without the inherent risks and compliance issues. However, intraoral appliances used in adolescence for distalisation of upper molars do not appear to have any advantages over cervical headgear. 2- Functional appliances reduce the anchorage requirements of a case primarily by reduction of the overjet, both fixed and removable functional appliances are equally effective in obtaining this. However, fixed functional appliances result in greater lower incisor proclination than removable functional appliances. 3- The type of functional appliance (removable or fixed) does not influence the extraction decision, however, this is influenced by overall space requirements.
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Theil, Ian. "Anchorage-dependent mammalian cell culture." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=56768.
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Genetically engineered anchorage-dependent human embryonic kidney (293) cells were cultured at 37$ sp circ$C on 1 mm thick sheets of a fibrous polymeric matrix having an average fibre diameter of 10.2 $ mu$m and a void fraction of 0.81 using Dulbecco's Modified Eagle's Medium (DMEM) supplemented with 10% fetal bovine serum (FBS) and 2.5 mM glutamine. Immobilization efficiencies above 70% were observed when cells were added to 100 mL spinner flasks (operating at 60 rpm) containing 70 mL of medium and two 1 x 1 cm squares of matrix (total gross area of 2 cm$ sp2$) fastened to the base of the stirrer shaft. Loadings in excess of 2.4 $ times 10 sp7$ cells per cm$ sp2$ of matrix were measured after 2 h.The state of the cultures was followed by measuring the consumption of glucose and glutamine and the production of lactate and ammonium.
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Camli, Umit Serdar. "Anchorage Strength Of Fiber Reinforced Polymers." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606752/index.pdf.
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Fiber reinforced polymers (FRPs) have gained popularity in upgrade projects for reinforced concrete structural elements within the last decade because of its ease of application and high strength-to-weight ratio. In the design of an effective retrofitting solution by means of an FRP system, the anchorage capacity has an important role. This study presents the results of an experimental program conducted to determine the strength of carbon fiber reinforced polymers (CFRPs) bonded to concrete prisms or hollow clay tiles that are finished with or without plaster. In the experimental program, different types of anchorage methods were tested in a double shear push-out test setup. A simple and effective strength model is proposed for strip type anchorages based on the existing analytical models and experimental observations from this study. This new model is suitable for determining the design capacity of CFRP-to-concrete and CFRP-to- hollow clay tile joints with or without plaster and accounts for the presence of embedment and concrete strength. Obtained results by using this model were found to closely match with the experimental observations.
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Tsui, Wai-kin, and 徐偉堅. "Bone anchorage for orthodontic tooth movement." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B44661605.
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Littlejohn, G. S. "Studies relating to ground anchorage systems." Thesis, University of Edinburgh, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.653958.
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This thesis comprises 28 papers which illustrate the nature and direction of development work and associated research undertaken between 1965 and 1993 on soil and rock anchorage systems. The research was performed in order to obtain a basic understanding of the behaviour of newly developed anchorage systems in a variety of ground types and conditions, in order to improve anchorage designs, construction methods and testing procedures, and thereby encourage the safe and economic application of ground anchorages worldwide. Field development of anchorage construction methods in gravels, sand, clays, marls and chalk using cement grout injection techniques is described together with equations evolved to estimate the ultimate resistance to withdrawal for each ground type, based on systematic testing of full scale anchorages. A new design method for single and multi tied stiff retaining walls installed in any soil is detailed and validated by large scale tests and closely monitored case histories. The interactions between wall, anchorage and soil are illustrated, coupled with the refinement of overall stability analyses in cohesionless soils using wedge and log spiral based mechanics of failure. For the rapid installation of anchorages in granular soils, vibratory driving is investigated in the laboratory and two distinct types of motion are found to exist. Theoretical equations of motion are developed to define the penetration processes and facilitate the design of vibrodrivers and vibrohammers. World practice in relation to the design, construction, testing and behaviour of rock anchorages is appraised, and field studies permit an improved understanding of uplift capacity by general shear failure, load transfer mechanisms, bond at rock/grout and grout/tendon interfaces, debonding, service performance and post-failure behaviour.
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Ivanović, Ana. "The dynamic response of ground anchorage systems." Thesis, University of Aberdeen, 2001. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=165281.
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This thesis describes the development of the lumped parameter model and the results obtained from it. In order to fully utilise the response signatures obtained from GRANIT, it is essential to understand the effect of the various components of the 'complete ground anchorage system' such as protruding free and fixed length of the anchorage, anchorage head assembly, affected and non-affected rock mass. In order to monitor each subsystem and its dynamic response to potential changes/failures, the anchorage system, in its simplest form, is represented by the model which comprises seven masses and a number of spring/damper systems replicating the components described earlier. Ordinary differential equations for mass/spring/dash-pot elements were then configured and the model was implemented in software form and then solved for both time and frequency domain. The acceleration response was examined at a number of points in the anchorage system i.e. at the protruding length as well as at the anchorage head, along the free length, along the fixed length and even within the rock mass itself. Several laboratory and field anchorage applications were simulated using the lumped parameter model and the results obtained from the model. A parametric study was then undertaken with regard to addressing mechanisms which are generally present in anchorage applications such as changes of material properties of the resin and concrete, the introduction of defects, such as gaps along the fixed anchorage length or debonding at the proximal fixed anchorage length, and the influence of changes in post tension load on the dynamic response of the anchorages. Furthermore, an investigation of the impulse load was conducted with the aim of further development of the current impact device in order to be able to assess anchorages regarding the mechanisms mentioned earlier.
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Ibell, Timothy. "Behaviour of anchorage zones for prestressed concrete." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259477.
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Hao, Jinde. "Dynamic responses of soil anchorages using numerical and centrifuge modelling techniques." Thesis, Available from the University of Aberdeen Library and Historic Collections Digital Resources, 2008. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&pid=24846.
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Muhamad, Khairussaleh Nor A. "Fatigue of cable anchorage on cable stayed bridge." Thesis, University of Surrey, 2016. http://epubs.surrey.ac.uk/811083/.
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Studies have shown that the connection details used for cable anchorage blocks on cable-stayed bridges have the potential for fatigue damage due to fluctuating stresses generated by the cyclic traffic loads passing over the bridge. To investigate the fatigue damage and determine the remaining fatigue life of a cable anchorage block used on a cable-stayed bridge, finite element (FE) analyses were undertaken by using the Fatigue Load Model 4 (FLM 4) proposed by the Eurocodes to identify the most fatigue-critical locations within the details. One of the main objectives of this research was to identify the critical area prone to fatigue in the anchorage block due to the response in traffic loads. Therefore, two types of numerical models of a typical cable anchorage block were analysed as a three dimensional sub-model which was driven by global cable forces obtained from the global analysis of a three-span cable-stayed bridge. These models are of the cable anchorage block without the longitudinal girder modelled and the cable anchorage block with the longitudinal girder modelled. The cable anchorage blocks without the longitudinal girder model were classified into three categories of model types namely; model types 0, A and B. Similarly, the cable anchorage blocks with the longitudinal girder model were classified as model types A-G, B-G and C-G. These model classifications are based on several boundary conditions simulated in the analyses. In addition to this, the fatigue behaviour of the cable anchorage block was analysed by using three different approaches namely; by using the nodal stresses at the location of the stress concentration (node stress concentration), by using a stress averaged over an area in the vicinity of the stress concentration (average elements) and by using the hot-spot method, in order to identify the stress ranges that adversely affect the remaining fatigue life of cable anchorages. Each approach was analysed with three different mesh sizes; 5mm by 5mm, 10mm by 10mm and 20mm by 20mm in order to carry out a mesh sensitivity analysis of the resulting stresses and associated stress ranges. The 10mm by 10mm mesh size was found to be most appropriate for this fatigue appraisal. This finding is supported because the 10mm by 10mm mesh size is specified in several code of practices such as the International Institute of Welding (IIW) and BS 7608 as guidance for use when determining hot-spot stress when using the hot-spot method for the fatigue analyses of a welded detail. The critical stresses from model type C-G were used in the fatigue appraisal as the behaviour of this model represented more accurately the actual cable anchorage block on the cable-stayed bridge compared to the other types of models used. Model type C-G were selected for further fatigue appraisal as this model include the correct boundary conditions and applied load that represented the actual condition of the anchorage behaviour on the cable-stayed bridge. This included the movement of the top anchorage block due to the displacement of the cable and in addition the deck movement. Also, non-uniform pressure was applied on the bearing plate which was included to model possible construction tolerances which was one of the important properties of the model type C-G. In evaluating the possible fatigue damage in the cable anchorage block, the cumulative model for fatigue failure expressed in terms of Miner’s rule was used. In addition to this, the condition of the structural detail due to fatigue with increasing traffic loading was determined by projecting traffic volume increases of up to 20%. Based on the results calculated, if the long distance traffic characteristic was used in fatigue appraisal, the cable anchorage block was justified to be not ‘safe’ as the damage accumulation for fatigue, Dd at the top gusset was recorded as 1.270, which exceeded the limiting value of 1.0 corresponding to a 120 year design life. However, if medium distance traffic characteristic was used in the fatigue appraisal, the cable anchorage block will remain ‘safe’ except when a 20% increase in traffic volume was included in the analysis, which resulted in Dd value of 1.016. Also, if a more conservative value of Dd = 0.5 as suggested by IIW (2008) was used, the cable anchorage block appraised by using both the long distance and medium distance traffics was found not safe from fatigue damage and would not survive its design working life without structural repair. For future fatigue appraisals of anchorage blocks (and other important structural details), it is strongly recommended that the numerical model of anchorage block is analysed together with the longitudinal girder using the hot-spot method. A 10mm by 10mm finite element mesh size is suggested and it is also necessary to specify the displacement at the top of the anchorage block to simulate the cable movement together with the girder movement both of which are obtained from the global analysis of the whole bridge structure.
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Hui, Macarious Kin Fung. "Anchorage of stirrups in prestressed concrete I-girders." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/57783.
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The current research investigates the performance of commonly-used non-code-compliant stirrup detailing in concrete I-girder bridges, specifically when the lower hooks on the stirrups are oriented parallel to the longitudinal prestressing strands and are not bent around any longitudinal bars. Such detailing does not meet the specifications in the Canadian Highway Bridge Design Code CSA S6-06. An experimental investigation was conducted on full-scale partial sections of a concrete I-girder to evaluate the performance of such non-code-compliant stirrup anchorages by comparing their performance to the performance of code-compliant stirrup anchorages. An analysis of an example concrete I-girder bridge was conducted to determine the demands on the stirrup anchorage during the tests. In the tests, the flexural tension force was applied to the prestressing strand while a diagonal force was applied to the web of the test specimens at approximately 30° to the longitudinal axis of the specimen. Two pairs of stirrups were fixed to a support as the diagonal force was applied. The ratio of the slip of the stirrup to the strain along the exposed length of the stirrup, which equals to the debonded length, was monitored in order to observe the performance of the stirrup anchorage. After applying many cycles of the diagonal force, including about 100 cycles after yielding of the stirrups, the non-code-compliant hooks were found to perform adequately.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
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Boizard, Sophie Marie Dominique Sandrine Valerie. "The ecology and anchorage mechanics of kelp holdfasts." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/31258.
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The intertidal zone on wave-swept shores is among the most stressful environments on earth. The ability of organisms to survive and thrive in such environments depends on their ability to withstand breakage and wave dislodgement. The research presented in this thesis investigated two aspects of the biology of kelp holdfasts. I first examined whether the recruitment of the kelp Hedophyllum sessile was facilitated by the presence of holdfasts of adult conspecifics and how canopy cover and wave-exposure mediated this interaction. Field experiments indicated that adult holdfasts and substrata of high structural complexity, such as articulated coralline algae, enhanced recruitment. However, the ability of structurally complex substrata to facilitate recruitment depends largely on the extent of canopy cover and to a lesser extent on wave-exposure. Mechanisms by which canopy cover mediates substratum-specific recruitment processes may hold significant implications for population persistence and successful recruitment, especially following periods of high disturbance. Secondly, I investigated the functional morphology of the holdfast of the kelp Laminaria setchellii in relation to its role in providing attachment to the substratum and resistance against wave dislodgment. Results of field investigations indicated that the thallus of L. setchellii responds to increased wave exposure by decreasing blade size and increasing holdfast size; a concomitant increase in holdfast attachment force was not observed. At high wave exposure sites, the integrity and attachment of L. setchellii holdfasts is jeopardized by the presence of barnacles and burrowing crabs. Field investigations further showed that L. setchellii exhibits asymmetry with respect to the prevailing wave direction. The blade and upper part of the stipe are oriented with their longer axis perpendicular to the flow so that reconfiguration and bending is facilitated. The lower part of the stipe and holdfast are oriented with their longer axis parallel to the flow, resisting bending. By exhibiting such pattern of asymmetry along it thallus, L. setchellii avoid large hydrodynamic forces while still avoiding large swaying and remaining off the substratum in water of higher light intensities and velocities.Science, Faculty of
Botany, Department of
Graduate
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Gad, Annica. "Cell cycle control by components of cell anchorage /." Stockholm : Division of Pathology, Karolinska institutet, 2005. http://diss.kib.ki.se/2005/91-7140-359-0/.
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French, David Joseph. "Investigations of a novel pile and anchorage concept." Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/46305.
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Cremona, C. A. "The role of anchorage in cell cycle control." Thesis, University College London (University of London), 2009. http://discovery.ucl.ac.uk/16663/.
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Mammalian cells generally require both mitogens and anchorage signals in order to proliferate. Failure to receive these signals results in either cell-cycle arrest or cell death, known as anoikis, due to activation of anchorage-dependent checkpoint mechanisms. Transformed cells alleviate these checkpoints, via activation of oncogenes and/or inactivation of tumour suppressors. In contrast, detachment of normal cells halts cell-cycle progression in G1, because of insufficient cyclin D1 induction to overcome the Rb/E2F checkpoint, accumulation of cyclin-dependent kinase inhibitors, and lack of cyclin A production. Because of the complexity of anchorage-dependent mechanisms involved, several changes are required for cells to become anchorage independent: impairment of both Rb and p53 pathways, plus activation of Ras. These specific defects are found in many human cancers, and anchorage independence correlates strongly with tumourigenic potential. Here I have used cells expressing SV40 LT, with and without oncogenic Ras, to model the changes leading to anchorage independent proliferation. Importantly, cells expressing SV40 LT alone retain their anchorage dependence, despite Rb and p53 inactivation. However, the mechanism responsible for this cell-cycle arrest in suspension is not known. Using immunoprecipitation and kinase assays, I demonstrated that the cyclin-dependent kinase inhibitor p27 curbs cell-cycle progression in these cells. FACS analysis showed that surprisingly, these cells do not undergo a robust checkpoint arrest, but instead stall throughout the cell cycle, showing abnormal DNA replication. Further investigation by metaphase spread showed the accumulation of aneuploid nuclei, indicating the development of genomic instability. This resulted in a higher rate of transformation among cells cultured without anchorage for a limited time. This work demonstrates that anchorage signals enable proper activation as well as assembly of cyclin-dependent kinase complexes, and that adhesion is particularly important for maintaining orderly cell-cycle progression and preventing genomic instability in checkpoint-deficient cells.
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Amin, Rizgar. "End anchorage at simple supports in reinforced concrete." Thesis, London South Bank University, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.685978.
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Chen, Qing-Li. "Effect of surface topography on hip prosthesis anchorage." Thesis, Queensland University of Technology, 1997.
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Ngan, Caroline Lai Yung. "Experimental investigations of anchorage capacity of precast concrete bridge barrier for Performance Level 2." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/1518.
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In the last twenty years, the design requirements of bridge barriers have changed with the aim of improving the safety of commuters on the bridge. A majority of precast concrete bridge barriers (PCBB) on highway bridges in British Columbia were designed and installed in accordance with the 1988 Canadian Highway Bridge Design Code (CHBDC). To ensure that these barriers comply with the current code requirements, research and testing were deemed obligatory. In particular, the anchorage capacity of the parapet under the CHBDC design load warrants verification. A finite element model of the barrier was developed in ANSYS to study its structural response. Static testing of a set of barriers was carried out at the University of British Columbia to better understand the behaviour of the barrier. The experimental results were used to calibrate and verify the finite element model. Through the finite element model and experimental results, a simpler model has been developed in a formatted spreadsheet environment to allow better estimates of the anchorage capacity of different barrier designs. The model was scaled to a wider use for practicing engineers so to ease and improve the design of anchorages of precast concrete bridge barrier under Performance Level 2 loading in accordance with the Canadian Highway Bridge Design Code.
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Sandler, Jonathan. "A comparison of the effectiveness of three methods of anchorage reinforcement in the treatment of maximum anchorage patients : a randomised clinical trial." Thesis, University of Sheffield, 2014. http://etheses.whiterose.ac.uk/5262/.
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The primary intention of this study was to add to the body of scientific evidence by determining whether a recently introduced method of anchorage reinforcement, namely Temporary Anchorage Devices (TADs), is effective. It is clear that there are several commonly used methods for anchorage support but some of these are totally dependent for success upon good patient compliance. Orthodontic clinicians would enthusiastically welcome as an alternative, an effective and efficient method that is less dependent upon patient co-operation. The introduction of new orthodontic techniques is rarely supported by high quality evidence on efficiency or effectiveness, in advance of them being promoted for widespread clinical use. New appliances and techniques are often promoted based upon very low levels of clinical evidence. Temporary Anchorage Devices were first introduced in 1983. Since then many papers have referred to Temporary Anchorage Devices as a source of stationary anchorage yet to date, few Randomised Clinical Trials (RCTs) have been carried out into this treatment method. AIMS To evaluate the effectiveness of Temporary Anchorage Devices for orthodontic anchorage when compared with the Nance button palatal arch and to Headgear. METHOD The TADs assessment trial is a prospective, dual-centre RCT involving 78 ‘maximum anchorage’ patients between 12 and 18 years of age with 39 males and 39 females. The three treatment arms of the study were Headgear, a Nance button palatal arch and TADs. Outcomes recorded included: anchorage loss measured both on lateral cephalometric radiographs and 3D model scanning, length of treatment, number of visits, quality of the outcome and the patients’ perception of the various treatment methods. RESULTS Sample summary showed the groups to be matched in terms of age, start PAR score and SNA. There was a statistically significant (p=0.002) overall effect of treatment when the right molar position was assessed on cephalograms. The Nance group lost 2.03mm (0.81-3.25) more anchorage than the Headgear group. No other statistically and clinically significant results were recorded between the groups on the cephalograms or on the superimposed digital models. Mean treatment times in months varied from 26.83 (SD 9.35) to 28.01(SD 5.38) and the total number of visits from 18.38 (SD 5.95) to 21.77 (SD 4.41). Casual visits and DNAs were almost identical between the groups but PAR scores were nearly 4 points better with TADs than Headgear and Nance. This result was statistically and clinically significant. From the patient questionnaires, the comfort levels both on placement and removal were similar with TADs and the Nance, and both techniques were highly recommended by the patients. Headgear was more troublesome and much less popular with the patients. CONCLUSIONS 1) There is no difference in the effectiveness of temporary anchorage devices, Nance button palatal arches and headgear in reinforcing anchorage in orthodontic treatment. 2) Patients’ perceptions suggest that there were greater problems with headgear and Nance buttons, than with temporary anchorage devices. 3) The quality of treatment as measured by PAR scores was significantly better with TADs than with headgear 4) Temporary anchorage devices may be the preferred method of choice for reinforcing orthodontic anchorage.
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Weckert, Steven Mining Engineering Faculty of Engineering UNSW. "Anchorage and encapsulation failure mechanisms of rockbolts ??? stage 2." Awarded by:University of New South Wales. School of Mining Engineering, 2003. http://handle.unsw.edu.au/1959.4/19219.
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The Fully Encapsulated Resin Bolt (FERB) is widely utilised for strata control and ground support in civil and mining applications worldwide, with approximately 6 million installed per annum by the Australian coal mining industry. Independent studies have concluded that 30-35% of these rockbolts, which represents an annual expenditure of $40 million, are ineffective. The anchorage and failure mechanisms of FERB are yet to be quantified, and support systems are designed primarily from empirical rather than scientific methods. There are no standardised methods of assessing FERB components, installation techniques and support behaviour. The majority of research into FERB support systems remains commercial intellectual property, with little information released into the public domain. This thesis investigated several variables of FERB support systems, and also examined differences between field and laboratory pull-out test load distributions. This research was conducted in two phases, with Phase 1 seeking standardised methodology and repeatability in results, while Phase 2 further refined Phase 1 methods and extended the range of tests. The results in both phases were encouraging, with reasonable repeatability attained in all testing series. The findings included: ??? Annulus Thickness: There was little change in load capacity with small annulus thickness, however the maximum peak load (MPL) significantly reduced once annulus thickness exceeded 4mm ??? Resin Installation Spin Time: Underspinning of cartridge resin was found to have an insignificant effect on rockbolt load/deformation characteristics. Overspinning, however, led to a dramatic reduction in anchorage performance with a lessening in both MPL and stiffness ??? Rockbolt Load Transfer: The magnitude of an applied load reduced to zero along the length of the rockbolt, being greatest nearest the rock free surface (the point of load application). An exponential reduction was found when tested in the manner of laboratory tests, with the loading jack reacting against the free surface. This reduction was linear when the load was applied as in the field, with no load placed on the free surface This basic investigation into FERB support systems has validated many empirical understandings of rockbolts, while highlighting the need for further testing into several key areas.
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Ahmad, BouSaleh. "Effects of anchorage details on response of deep beams." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=98946.
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As part of a research program at McGill University, involving the testing of eight full-scale deep beams, this research studies the response of four full-scale deep beams that were designed in accordance with the strut-and-tie model provisions of the CSA Standard A23.3 (2004). All of the deep beams had a centre-to-centre spacing of 2000 mm between the two supports, 1000 mm in height, and 350 mm in thickness. They were simply supported with an application of a single point load at midspan. The total length of the four beams varies depending on the type of anchorage being used. The four anchorage details that were considered in this study include a straight development length, a standard 90 degree hook, friction-welded 1.5 in. (38 mm) diameter circular headed bars and friction-welded 2 in. (50 mm) diameter headed bars. The dimensions of the loading pad and the bearing pads were 200 mm (and 300 mm) and 100 mm, respectively. All beams were reinforced with two layers of five 15M bars forming the tension tie reinforcement. El-Jorf (2006) carried out the testing and analysis of the other four full-scale deep beams in this overall research program.This research project demonstrated that providing friction-welded circular headed bars capable of developing the full yield strength at the head results in shorter beams and improved response compared to straight bar embedment details. Providing a lead-in length as well as friction-welded circular headed bars, with reduced head size, provides improved ductility compared to the straight bar embedment and compared to the hooked anchorage. This research also shows that benefits of confinement pressures at the supports can increase the bar stress although the provided development length is below code requirements.
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Baldwin, Marc Lllya. "The assessment of inadequate anchorage in reinforced concrete structures." Thesis, University of Birmingham, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.490768.
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Bennitz, Anders. "Mechanical anchorage of prestressed CFRP tendons : theory and tests /." Luleå : Division of Structural engineering, Department of Civil, Mining and Environmental Engineering, Luleå University of Technology, 2008. http://epubl.ltu.se/1402-1757/2008/32/.
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Applegate, Steven M. "The design of column base anchorages for shear and tension." Master's thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-01202010-020157/.
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Dua, Rupak. "Enhanced Anchorage of Tissue-Engineered Cartilage Using an Osteoinductive Approach." FIU Digital Commons, 2014. http://digitalcommons.fiu.edu/context/etd/article/2559/type/native/viewcontent.
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Articular cartilage injuries occur frequently in the knee joint. Several methods have been implemented clinically, to treat osteochondral defects but none have been able to produce a long term, durable solution. Photopolymerizable cartilage tissue engineering approaches appear promising; however, fundamentally, forming a stable interface between the tissue engineered cartilage and native tissue, mainly subchondral bone and native cartilage, remains a major challenge. The overall objective of this research is to find a solution for the current problem of dislodgment of tissue engineered cartilage at the defect site for the treatment of degraded cartilage that has been caused due to knee injuries or because of mild to moderate level of osteoarthritis. For this, an in-vitro model was created to analyze the integration of tissue engineered cartilage with the bone, healthy and diseased cartilage over time. We investigated the utility of hydroxyapatite (HA) nanoparticles to promote controlled bone-growth across the bone-cartilage interface in an in vitro engineered tissue model system using bone marrow derived stem cells. We also investigated the application of HA nanoparticles to promote enhance integration between tissue engineered cartilage and native cartilage both in healthy and diseased states. Samples incorporated with HA demonstrated significantly higher interfacial shear strength (at the junction between engineered cartilage and engineered bone and also with diseased cartilage) compared to the constructs without HA (p < 0.05), after 28 days of culture. These findings indicate that the incorporation of HA nanoparticles permits more stable anchorage of the injectable hydrogel-based engineered cartilage construct via augmented integration between bone and cartilage.
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Gale, Luke. "Behaviour of multiple anchorage systems for FRP-prestressed concrete structures." Thesis, University of Bath, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.425631.
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McDermott, Ruth Helen. "The adaptation of anchorage-dependent cells to glutamine-free medium." Thesis, Manchester Metropolitan University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294056.
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Cavalancia, James. "EFFECTS OF A LINGUAL ARCH AS MAXIMUM ANCHORAGE IN ORTHODONTICS." Master's thesis, Temple University Libraries, 2017. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/456182.
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Oral BiologyM.S.
Lingual arches are frequently used in orthodontic extraction treatment, with the intended purpose of achieving maximum anchorage in the mandibular arch; however, little evidence exists in the literature that supports this anchorage approach. The lingual arch is widely supported in the literature for space maintenance and sagittal correction. It has been proven effective at minimizing any decreases in arch depth and perimeter when there is early loss of primary teeth. Theoretically, the lingual arch as a passive maintenance appliance should exert no forces on the teeth, yet studies have shown both the molars and incisors to move. To examine its anchorage efficiency further, we compared incisor and molar position in extraction treatment with and without the use of a lingual arch. Pre and post-treatment cephalograms that included lower premolar extractions were recruited from a depository of images. Canine retraction with power chain or NiTi closing coils with or without the use of a lingual arch for maximum anchorage were compared for incisor and molar position. Angular and millimetric measurements for IMPA, L1-NB, L1-APog and molar mesialization were measured and compared using a t-test. The greatest difference between pre and post-treatment was the IMPA with 5.19° more uprighting of the incisors in the group with no lingual arch, followed by 4.38° more uprighting in the L1-APog measurement. However, none of the differences between the groups were significant: IMPA (p=0.129), L1-NB (angular p=0.161, millimetric p=0.205), L1-APog (angular p=0.197, millimetric p=0.196) and mesialization of the molar (p=0.308). The change in incisor and molar position does not significantly differ with or without the use of a lingual arch in extraction treatment. Clinically, this suggests that the lingual arch does not provide maximum anchorage. Another modality, such as TADs, may provide a better source of anchorage for space closure.
Temple University--Theses
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Fabris, Nicola. "Bond and anchorage of prestressing tendons in prestressed-concrete members." Doctoral thesis, Università degli studi di Padova, 2019. http://hdl.handle.net/11577/3422843.
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Over the last few decades, pretensioned Prestressed-Concrete (PC) has become very common in structural applications. Its extensive use, however, requires adequate knowledge of bond development between prestressing tendons and surrounding concrete. Bond is of paramount importance both for prestress transfer at release and anchorage capacity under flexural loading. Current design codes for concrete structures provide simplified formulations to describe the force transfer mechanisms from steel to concrete, and seem to be not always conservative when compared to experimental evidences. More refined models are actually needed to reasonably consider the effect of the main parameters affecting bond properties, thus resulting in a sound design of PC members.
The first part of this contribution presents a broad review of the literature on various aspects of pre-tensioning anchorage. The bond mechanisms governing the transmission of the prestressing-force to the concrete and the subsequent behaviour of PC members are illustrated. The common experimental methods to investigate both transmission length and anchorage capacity of prestressing tendons are described and discussed. Then, the existing provisions from the main design codes are analysed and compared.
The second part of the work is focused on the general assessment of the principal design formulations on pre-tensioning reinforcement. Big differences in the evaluation of the transmission length and anchorage length are highlighted when the different provisions are applied to the same structural configuration, due to discrepancies in the considered influencing factors. Thus, the accuracy of the suggested relationships is assessed in detail by applying them to a comprehensive experimental database of transmission length and anchorage length values, collected from the literature. It is shown that the performances of the various design concepts are not always acceptable, since the theoretical predictions do not always fit well the experimental results. Lastly, the role of some key variables affecting bond, such as strand diameter, strand surface condition and concrete strength, is studied based on the analysis of the collected dataset.
In the third part of the contribution, the analytical modelling of the transmission length in PC members is carried out. For practical purpose, simplified bond stress distributions along the beam are assumed by all the common design codes, even though they do not reflect the real properties at the interface steel-concrete. A more accurate representation of the internal behaviour of PC members can be achieved by means of physically-based models, rationally incorporating the effect of several influencing parameters. A first bond model is presented based on the radial expansion of the tendon at the release operation, considering anisotropic characteristics of the concrete around the tendon. Then, a second theoretical investigation is developed by appropriately describing the bond stress-slip relationship. In both cases, the bond stresses between the materials after release appear to describe a non-linear distribution along the transmission zone. The global results show the capability of the developed analytical models to simulate the bond behaviour during transmission of the prestressing-force to the concrete.Negli ultimi decenni il calcestruzzo armato precompresso a cavi pre-tesi ha assunto una crescente rilevanza nelle applicazioni strutturali. Il suo ampio utilizzo richiede comunque un’adeguata conoscenza in merito allo sviluppo dell’aderenza tra i trefoli e il calcestruzzo circostante. L’aderenza è un fenomeno di importanza fondamentale, sia per il trasferimento della forza di precompressione al rilascio dei trefoli che per la capacità di ancoraggio del cavo in seguito a carichi flessionali. Gli attuali codici normativi per strutture in calcestruzzo forniscono formulazioni semplificate per descrivere i meccanismi di trasferimento delle forze da acciaio a calcestruzzo, e sembrano essere talvolta non conservativi quando comparati a evidenze sperimentali. Per considerare in maniera ragionevole l’effetto dei principali parametri che influenzano le proprietà di aderenza sono in realtà necessari modelli più raffinati, in grado di indirizzare verso una più corretta progettazione degli elementi precompressi. La prima parte di questo contributo presenta un’ampia revisione della letteratura riguardo vari aspetti delle armature da precompressione. Vengono illustrati in particolare i meccanismi di aderenza che governano la trasmissione della forza di precompressione al calcestruzzo e il successivo comportamento della membratura. Vengono inoltre descritti e commentati i comuni metodi sperimentali che permettono di indagare la lunghezza di trasmissione e la capacità di ancoraggio di trefoli da precompressione. Infine, vengono presentate e comparate le principali disposizioni normative in vigore. La seconda parte del lavoro di tesi è focalizzata sulla valutazione generale delle principali formulazioni normative in merito alle armature di precompressione. Si riscontrano grandi differenze nella valutazione delle lunghezze di trasmissione e di ancoraggio quando le diverse prescrizioni vengono applicate alla medesima configurazione strutturale, in seguito a discrepanze sulle variabili di influenza considerate. Viene pertanto studiata nel dettaglio l’accuratezza delle formule proposte, andandole ad applicare ad un ampio database di prove sperimentali sulle lunghezze di trasmissione e di ancoraggio, raccolto dalla letteratura disponibile. Si vedrà che le performance dei vari codici normativi non sono sempre accettabili, poiché le predizioni teoriche non si adattano sempre bene ai risultati sperimentali. Infine, viene studiato il ruolo di alcuni parametri fondamentali (per es. il diametro del trefolo, le condizioni superficiali dello stesso e la resistenza del calcestruzzo) nei confronti dell’aderenza, sulla base dell’analisi dello stesso database. Nella terza parte del contributo si affronta la modellazione analitica della lunghezza di trasmissione in travi precompresse. Per questioni di praticità, tutte le principali normative assumono una distribuzione semplificata delle tensioni di aderenza lungo la trave, anche se tale situazione non riflette le reali proprietà all’interfaccia trefolo-calcestruzzo. Una rappresentazione più accurata del comportamento interno di membrature precompresse può essere ottenuta tramite modelli fisicamente basati, in grado di incorporare in maniera razionale l’effetto di molti parametri di influenza. A tale scopo, un primo modello di aderenza viene presentato sulla base dell’espansione radiale del trefolo che si verifica al rilascio dei cavi, considerando le caratteristiche anelastiche del calcestruzzo attorno al trefolo. In seguito, un secondo approccio teorico viene sviluppato andando a descrivere in maniera appropriata la relazione aderenza-scorrimento. In entrambi i casi, le tensioni di aderenza tra i due materiali al rilascio dei trefoli sembrano descrivere distribuzioni non lineari lungo la zona di trasmissione. I risultati globali mostrano l’effettiva capacità dei modelli analitici sviluppati di simulare il comportamento dell’aderenza durante la trasmissione della forza di precompressione al calcestruzzo.
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Selkregg, Sheila Ann. "The Decision and Rationale which Led to Construction on High-risk Land after the 1964 Alaska Earthquake: Analysis of Risk-based Cultural Dissociation." PDXScholar, 1994. https://pdxscholar.library.pdx.edu/open_access_etds/1302.
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Many lives and much property are lost in disasters when individuals and communities choose to ignore information which could mitigate the potential disaster. This case study examines community and individual decision processes and rationale which led to construction of a high-occupancy high-rise courthouse on land designated as high risk after the 1964 Alaska earthquake. The study reviews policy and decision making, psychology, and risk management literature to explore the psychological mechanisms and processes of hazard mitigation decisions.
It questions why individuals and communities choose not to mitigate when they have the information which makes risk mitigation possible. The hypothesis theorizes risk-based cultural dissociation and submits that individuals and society process risk-related information in a manner that allows for interpretation and acknowledgement of information so that it is compatible with individual and social agendas and constructs. Society and individuals can and do completely deny or dissociate from risk-related information.
This exploratory research uses macro, meso, and micro levels of analysis to examine the environmental setting, land ownership and power, and professional and public seismic information. This examination is placed in the context of Anchorage's post-earthquake reconstruction momentum.
Indepth interviews with elected officials, a bank president, insurance executives, investors, builders, appointed officials, private and public professionals, court representatives, a judge, a juror, and citizens provide insight into risk perception and individual and community agendas. The interviews revealed each level of analysis had different perceptions of risk and different agendas.
Professional warnings not to reconstruct on high-risk land were ignored. Downtown economic interests and powerful individuals significantly impacted the community decision process. One charismatic leader played a major role in the community reconstruction and courthouse decisions.
Research findings support the hypothesis. Individuals consistently chose to deny earthquake potential in their daily lives. Selective interpretation of information allowed individuals to support their own agendas. Community decision processes allowed deletion of important information and a transference of responsibility, resulting in no decision body or individual feeling responsible for the decision. Risk-based cultural dissociation is defined and presented in this research as a direction for future study.
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Garrett, Scott J. "Implementation of Canon 1112 [section] 1 to the Archdiocese of Anchorage." Theological Research Exchange Network (TREN), 2006. http://www.tren.com/search.cfm?p029-0679.
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Schreiber, Alex C. "Success rates of temporary anchorage devices placed in an orthodontic clinic." Thesis, Birmingham, Ala. : University of Alabama at Birmingham, 2008. https://www.mhsl.uab.edu/dt/2008m/schreiber.pdf.
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Indridason, Birgir. "Earthquake Induced Behavior of Submerged Floating Tunnels with Tension Leg Anchorage." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for konstruksjonsteknikk, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-23538.
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SUMMARY:The purpose of this study is to examine the behavior of a submerged floating tunnel (SFT) anchored by tension legs and subjected to seismic excitation. A proposal of a tunnel crossing the Høgsfjord in Norway is used as a case for the finite element model. The tunnel was proposed as 1345m long with a cross section diameter of 11.3 m. Furthermore, the tunnel should lie 25m under the sea surface to enable regular sea traffic. A seismic analysis of the SFT is performed using a pseudo-excitation method (PEM), which is based within the framework of random vibration methods. The coherency between different supports is studied, in particular the incoherence and wave passage effects. A simple constant incoherence model is introduced, for coherency between inter-components of motion. Three cases of the incoherence are then examined: (i) fully coherent, (ii) incoherent and, (iii) non-coherent. The seismic analysis is carried out for different velocities and angles of the propagating earthquake waves. The structure is modeled in Abaqus, by using beam elements for both the tunnel and the tension legs. The fluid/structure interaction is modeled and its effects on the structure are discussed. The SFT is modeled with both vertical and inclined tension legs and the behavior of the models are investigated, with regard to seismic events. The seismic analysis is performed in Matlab, by developing m-scripts based on the system matrices generated in Abaqus. The results from the analysis confirm the importance of accounting for the stochastic nature of seismic waves. Furthermore, the results suggest that submerged floating tunnels with tension leg anchoring are reliable when subjected to earthquake excitation. It is unlikely that earthquake action will be taken as the design load case for Norwegian conditions.
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Shave, Jonathan David. "Shear assessment of concrete bridges : anchorage effects and use of plasticity." Thesis, University of Bath, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.415398.
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Crispino, Eric Daniel. "Anchorage Zone Design for Pretensioned Bulb-Tee Bridge Girders in Virginia." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/31454.
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Precast/Prestressed concrete girders are commonly used in bridge construction in the United States. The application and diffusion of the prestress force in a pretensioned girder causes a vertical tension force to develop near the end of the beam. Field surveys of the beam ends of pretensioned bridge girders indicate that many of the PCBT beams used in the Commonwealth of Virginia develop cracks within the anchorage zone region. The lengths and widths of these cracks range from acceptable to poor and in need of repair. Field observations also indicate deeper cross sections, very heavily prestressed sections, and girders with lightweight concrete tend to be most susceptible to crack formation.
This research examined a new strut-and-tie based design approach to the anchorage zone design of the PCBT bridge girders used in Virginia. Case study girders surveyed during site visits are discussed and used to illustrate the nature of the problem and support the calibration of the strut-and-tie based model. A parametric study was conducted using this proposed design model and the results of this study were consolidated into anchorage zone design tables. The results of the parametric study were compared to the results obtained using existing anchorage zone design models, international bridge codes, and standard anchorage zone details used by other states. A set of new standard details was developed for the PCBT girders which incorporates elements of the new design approach and is compatible with the anchorage zone design aids.
A 65 ft PCBT-53 girder was fabricated to verify the new strut-and-tie based design model. This girder contained anchorage zone details designed with the new model. The new anchorage zone details were successful at controlling the development of anchorage zone cracks. The new design approach is recommended for implementation by the Virginia Department of Transportation.Master of Science
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Heymann, Gavin Christopher Tulloch J. F. Camilla. "Temporary anchorage devices for maxillary protraction 3D analysis of treatment outcomes /." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2008. http://dc.lib.unc.edu/u?/etd,1796.
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Thesis (M.S.)--University of North Carolina at Chapel Hill, 2008.Title from electronic title page (viewed Sep. 16, 2008). "... in partial fulfillment of the requirements for the degree of Master of Science in the Department of Orthodontics." Discipline: Orthodontics; Department/School: Dentistry.
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Takaaki, Tsunoyama. "Super-long single-molecule tracking reveals dynamic-anchorage-induced integrin function." Kyoto University, 2018. http://hdl.handle.net/2433/235968.
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McManus, Michelle Marie. "Effect of mini-screw maximum insertion torque on skeletal orthodontic anchorage." Thesis, University of Iowa, 2010. https://ir.uiowa.edu/etd/552.
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Objective: The primary objective of this study was to examine the effect that maximum insertion torque has on force resistance and stability of titanium screws in cadaver maxillae and mandibles.
Materials and Methods: Forty-eight cadaver maxillary and mandibular jaw quadrants were obtained Two titanium mini-screws were placed in each jaw quadrant and maximum insertion torque was measured. Each mini-screw was subjected to tangential force application oriented perpendicular to placement of the mini-screw and parallel to the occlusal plane. The force applied at each deflection was measured up to 1.5mm, but only the first 0.60mm of movement was investigated. This amount of displacement was selected to represent the amount of movement that would result in a clinically mobile mini-screw and potential failure.
Results: The post-hoc Tukey-Kramer's test showed that mean anchorage resistance for screws placed with maximum insertion torque of less than 5Ncm was significantly lower than those observed for 5-10Ncm and greater than 10Ncm. No significant difference was found between 5-10Ncm and greater than 10Ncm.
Conclusions: In vitro, mean anchorage resistance for screws placed with maximum insertion torque of less than 5Ncm was significantly lower than those placed with maximum insertion torque between 5Ncm and 10Ncm at deflections ranging from 0.12mm to 0.60mm. In terms of maximizing anchorage resistance, we recommend placement of orthodontic mini-screws with maximum insertion torque of greater than 5Ncm.
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Tarraf, Nour Eldin. "The application of skeletal anchorage in the management of maxillary deficiency in growing children." Thesis, The University of Sydney, 2021. https://hdl.handle.net/2123/25912.
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Chapter one discusses oropharyngeal swallowing impairment due to head and neck cancer (HNC). Its complexity and severity arise from the dual physiological and structural changes to swallowing musculature. Expectations of recovery are difficult to predict due to the variety of treatment modalities, demographic and clinical characteristics, the risk of recurrence, implications of malnutrition, and the progressive nature of radiation fibrosis.
The second chapter reported on a systematic review and meta-analysis describing the relationship between radiation dose to critical swallowing structures. The third chapter explores this relationship in the definitive and post-operative setting. Chapter four evaluated swallowing impairment following transoral robotic surgery (TORS) for HNC using fibreoptic endocscopic evaluation of swallowing. A significant deterioration in swallow function, characterised by a heavy secretion load, pharyngeal residue, laryngeal penetration and aspiration was identified in most participants. The fourth chapter evaluated intensity modulated radiation therapy (IMRT) and TORS at 12 months post-treatment for oropharyngeal cancer. A statistically significant advantage for TORS was identified, when adjuvant radiotherapy which involved the primary site could be avoided. This finding correlates with one of the primary purposes for TORS, which was to achieve a deintensification of radiation, known to impair swallowing function as demonstrated in earlier chapters.
This thesis describes how technological advances in head and neck cancer treatment have changed the expectations for functional recovery. Both IMRT and TORS represent approaches which are intended to preserve critical swallowing structures in an effort to preserve swallowing function after treatment. While encouraging, results presented here demonstrate significant challenges which impact quality of life. Utilisation of instrumental assessment in this population remains imperative to characterise swallow physiology, particularly in light of high rates of silent aspiration and pharyngeal residue. This information will guide rehabilitation programs.
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Black, Martin. "Automated lithological mapping using airborne hyperspectral thermal infrared data, Anchorage Island, Antarctica." Thesis, University of Hull, 2016. http://hydra.hull.ac.uk/resources/hull:13994.
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The thermal infrared portion of the electromagnetic spectrum has considerable potential for mineral and lithological mapping of the most abundant rock-forming silicates that do not display diagnostic features at visible and shortwave infrared wavelengths. Lithological mapping using visible and shortwave infrared hyperspectral data is well developed and established processing chains are available; however, there is a paucity of such methodologies for hyperspectral thermal infrared data. Here, a new fully automated processing chain for deriving lithological maps from hyperspectral thermal infrared data is presented; the processing chain is developed through testing of existing algorithms on synthetic hyperspectral data. The processing chain is then applied to the first ever airborne hyperspectral thermal data collected in the Antarctic. A combined airborne hyperspectral survey, targeted geological field mapping campaign and detailed mineralogical and geochemical datasets are applied to a small test site in West Antarctica where the geological relationships are typical of continental margin arcs. The challenging environmental conditions and cold temperatures in the Antarctic meant that the data have a significantly lower signal to noise ratio than is usually attained from airborne hyperspectral sensors. Preprocessing techniques were applied to improve the signal to noise ratio and convert the radiance images to ground leaving emissivity. Following preprocessing, the fully automated processing chain was applied to the hyperspectral imagery to generate a lithological map. The results show that the image processing chain was successful, despite the low signal to noise ratio of the imagery; the results are encouraging with the thermal imagery allowing clear distinction between granitoid types.
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Haldankar, Raj. "A kinetic study of the growth of anchorage-dependent mouse L cells." Ohio : Ohio University, 1994. http://www.ohiolink.edu/etd/view.cgi?ohiou1177097944.
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Kelly, David. "The effect of anchorage of geosynthetics upon the performance of unpaved roads." Thesis, Edinburgh Napier University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260996.
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OLIVEIRA, WALTER EDGLEY DE. "EXPERIMENTAL STUDY ON THE TENSILE STRENGTH OF ANCHORAGE PLATES EMBEDDED IN CONCRETE." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2003. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=4239@1.
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CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOELETROBRAS TERMONUCLEAR S.A - ELETRONUCLEAR
Placas de ancoragem embutidas em concreto são empregadas, geralmente, com a finalidade de permitir a fixação de elementos para a introdução de cargas concentradas nas estruturas de concreto, bem como viabilizar as ligações estruturais entre componentes pré-fabricados. As placas são ancoradas no concreto através de pinos soldados a elas. Estas placas são bastante empregadas em estruturas de usinas nucleares onde um grande número de equipamentos e tubulações são apoiados na estrutura de concreto. A pesquisa é de natureza experimental e tem como objetivo investigar a redução da resistência à tração de placas de ancoragem com grupo de chumbadores, placas instaladas com pequena distância dos bordos do elemento de concreto, e também de duas placas adjacentes, devido a interferência de seus cones de ruptura. A eficiência de uma armadura de suspensão (que transmite a carga além do cone de ruptura), também é verificada. Os resultados experimentais sugerem uma notável redução da resistência à tração para placas com grupo de chumbadores, e que o uso da armadura de suspensão para placa instalada nas proximidades do bordo do elemento de concreto não é muito eficiente. A armadura de suspensão apresentou um bom rendimento quando foi empregada em placas com grupo de chumbadores. Os resultados teóricos obtidos através de equações desenvolvidas para estimativa da carga de ruptura, apresentaram, de maneira geral, uma boa aproximação quando comparados com os resultados experimentais.
Anchorage plates embedded in concrete are used with the purpose of allowing the fixation of elements for the introduction of concentrated loads into concrete structures, as well as to make possible the structural connections between prefabricated components. The plates are anchored in the concrete through studs welded to them. These plates are used in structures of nuclear power stations where a great number of equipments and pipings are fixed in the concrete structure. The research is of experimental nature and its objective is to investigate the reduction of the tensile strength of multiple studs group, anchorage plates located close to a free edge, and also of two adjacent plates, due to interference of failure concrete cones. The efficiency of an additional reinforcement (that transfers the load beyond the concrete cone), is also addressed. The experimental results suggest a significant reduction of the tensile strength for plates with studs group, and that the use of the additional reinforcement for anchorage plates located close to a free edge is not too efficient. The additional reinforcement presented a good efficiency when it was used in plates with studs group. The theoretical results obtained from equations developed to estimate the concrete failure load show, in a general way, a good agreement with the experimental results.
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Kalupahana, W. K. Kalpana G. "Anchorage and bond behaviour of near surface mounted fibre reinforced polymer bars." Thesis, University of Bath, 2009. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.518298.
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The Near Surface Mounted (NSM) strengthening is an emerging retrofitting technique, which involves bonding Fibre Reinforced Polymer (FRP) reinforcement into grooves cut along the surface of a concrete member to be strengthened. This technique offers many advantages over external bonding of FRP reinforcement, for example, an increased bond capacity, protection from external damage and the possibility of anchoring into adjacent concrete members. To date, significant research has been conducted into the NSM FRP strengthening technique. However, there are still some areas which need further research in order to fully characterise bond and anchorage of NSM FRP bars. Lack of experimental data, design tools and analytical models addressing these areas create obstacles for the efficient use of these advanced polymer materials. The particular objectives of the research are; to investigate bond behaviour between NSM FRP bars and concrete, to understand the critical failure modes involved and their mechanics, and to develop a rational analytical model to predict bond strength and anchorage length requirements for NSM FRP bars. Several significant variables affecting bond, such as bond length, size, shape and type of bar, resin type, groove dimensions and concrete strength, have been considered. In particular, attention has been focussed on the effect of bar shape on bond behaviour. A comprehensive set of laboratory testing and their results, including the effect of the investigated parameters are presented. Various modes of anchorage failure of NSM FRP bars are identified and the underlying mechanics are investigated. Analytical models are developed to predict bond capacity and anchorage length requirements of NSM FRP bars, and are verified with experimental results.
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Lin, Ying-Chieh, and 林英傑. "Anchorage Behavior of the Inclined-Multiple-Anchorage Anchors in Silty Sand." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/70230997631159965039.
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碩士朝陽科技大學
營建工程系碩士班
95
A continuous strain hardening-softening and volumetric dilatancy model named SHASOVOD, and FLAC3D software were adopted to study the anchorage behavior of inclined-multiple-anchorage anchors in silty sand. To enhance the applicability of numerical analyses, the results of field tests are compared with those from numerical analyses. After the calibration, parametric studies were then carried out by numerical analyses. It was found that the numerical results are in a good agreement with those by field tests. The friction force dominates the anchorage capacity of a shaft multiple anchorage anchor. It can be inferred, the optimum position of the upper anchorage body is 6m form the bottom for a double-anchorage anchor. Moreover, for a triple-anchorage anchor, a distance of 12m is the best location for upper anchorage body from the middle one. Even though anchorage bodies were installed in the condition of optimum location, the anchorage capacity could not be the summation of the ultimate load of each anchorage body, this phenomenon is caused by carried load of each anchorage body do not reach peak values at same anchor displacement. Whether embedded depth, overburden depth or fixed length of an anchor increased, the anchorage capacity of an anchor also increased. For a multiple-anchorage anchor, increasing fixed length should be the best choice to increase the anchorage capacity, ultimate load per unit fixed length was around 60kN/m. However, as the fixed length of a double-anchorage anchor is greater than 30m, the anchorage capacity per unit fixed length was decreased due to progressive yield of friction stress along fixed end. Instead, a triple anchorage methodology could be applied to conquer the progressive yield of above situation. A tension force was generated beneath the anchorage body, Hence the grouted body was cracked and led to an erosive steel strand. No utilization to a multiple-anchorage anchor is really complete without applying a double protection on fixed length.
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Yeh, Chun-Chieh, and 葉俊杰. "Design of Orthodontic Anchorage Screw." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/w83764.
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碩士國立臺北科技大學
製造科技研究所
96
The primary purpose of this research work is to design new type of orthodontic anchorage screws. It is usually difficult to screw in the commercialized ones and hard to localized the anchorage screw without pre-drilling during orthodontic surgical operation. There are three types of anchorage screws which are A type with 3 cutting edges, B type with 3 flutes of self-tapping function, and combination both functions of C type were designed and manufactured in the CNC machine center once for all. All of the machined screws were tested with rigid polyurethane foam (base on ASTM F1839) and pig bones. The experimental results indicated that types A, B, and C did not meet the pursuit targets for design purposes. Therefore, a D type based on the advantages of both original type and C type was designed. The experimental data revealed that the maximum twist force was decreased from 0.181 to 0.092 kgf-cm. And the necessary anchoring revolutions for screw were also decreased from 5 to 1, simultaneously. Our conclusion is that it is not necessary to pre-drilling any more by take D type for orthodontic operation.
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Kouvroukogloa, Stylianos. "Migration of anchorage-dependent mammalian cells." Thesis, 1998. http://hdl.handle.net/1911/19278.
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Cell migration affects many physiologic and pathologic processes in mammalian organisms. Thus, our ability to modulate these processes depends on understanding how cell migration is controlled by soluble factors, cell-substrate interactions and metabolic pathways. To accurately quantify the effects of external stimuli, cell migration was studied using a computer-automated technique that combined video microscopy, digital time-lapse and image analysis. This approach enabled us to monitor large cell populations and characterize the migration behavior of individual cells.
The effect of receptor/ligand interactions on the migration of endothelial cells was studied first. Bioactive glass surfaces were prepared by covalently binding on them short adhesive peptides and the spatial distribution of the bound peptides was characterized with fluorescence studies. Locomotion analysis showed that endothelial cells migrated on the bioactive surfaces with significantly increased persistence and random motility coefficients. Since migration is a major factor in determining proliferation rates of anchorage-dependent cells, this type of surface modification can be used to accelerate the endothelization of synthetic vascular grafts and increase their implantation success rates.
The role of metabolism on cell motility was investigated by testing the hypothesis that glycolysis is required for cancer cell migration. Our measurements demonstrated that rat prostate cancer cells grown in conditioned media did not require glucose to maintain migration. Conditioned media helped these cells adapt to inhibition of glycolysis or mitochondrial respiration by increasing activity of the uninhibited pathway.
To test the ability of soluble factors to protect the endothelium and improve its wound healing response, we studied the morphology and migration of endothelial cells exposed to ionizing irradiation. Soluble growth factors had no effect on the migration speed of endothelial cells and did not reverse the hyperplasia observed after exposing these cells to radiation. However, heparin significantly reduced irradiated cell size especially when used together with basic fibroblast growth factor.
Finally, a computer model was developed to describe the dynamics of large populations of migrating, interacting and proliferating cells. Simulation results agreed well with experimental data. This model has predictive capabilities that make it particularly useful for tissue engineering applications.
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Syu, Liang-Wai, and 許諒瑋. "Optimization and Analysis of Prestressing Anchorage." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/51004821492755162411.
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碩士國立雲林科技大學
營建工程系碩士班
97
Prestressed concrete has been widely used in bridge construction. Prestressing system consists of anchor head, bearing plate, spiral reinforcement, duct, wedge, and tendons. Among them, bearing plate is the major part to transfer the prestressing force from the tendons to the concrete. The load transfer test is required to verify the design of prestressing systems by the CEB/FIP code. In this research, the load transfer test and finite element simulation have been carried out to examine the load transfer and stress distribution of the whole prestressing system. With the numerical models constructed using Abaqus software, the factors such as the size of bearing plate and the position of rings that influence the load transfer have been studied extensively. Some improvements have been made for the design of anchorage. Parametric study of this research shows that to include rings in the design of end anchorage is capable of improving the load transfer and stress distribution. If rings are located at optimal positions, the maximum lateral tensile stress of concrete can be lowered effectively. A smaller cross section of concrete can then be used if the area of bearing plate is decreased appropriately. Up to now, the optimization of prestressing anchorage is only verified by finite element simulation in this study. The improved design of anchorage is planned to be manufactured and verified by the load transfer test in the near future.
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Tsai, Chu-Chen, and 蔡竺真. "Experimental Anchorage Performance of T-Headed Bars." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/w6km75.
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碩士國立臺北科技大學
土木與防災研究所
101
Reinforced concrete, generally adopted by its durability, low cost and the easiness for installation and maintenance, is the most popular material of choice for construction in Taiwan. Traditionally, the standard hook used for reinforcement''s anchorage results in steel congestion in the beam-column joint region, and makes the difficulty to the concrete pouring. Moreover, the poor concrete placement due to congestion sometimes degrades the quality of structures and provokes the safety-relation problem. In the last decades, T-headed bar is proposed to replace conventional standard hook to ease fabrication and construction, to improve concrete placement quality and thus reduce structural failure. Consequently, the use of mechanical anchorage to offer a potential solution for these problems, and even provide a better seismic performance is the main subject of this study. A total of 36 specimens were designed to test under pullout condition by varying the rebar size, bonded depth, and the compressive strength of concrete. Experiment results indicate that the the T-headed bar had a better pullout strenth compared to the rebar embedded alone. The T-headed bar specimens were tested the concrete cone with the height of bonded depth while the rebar specimens tested the debonding with 20mm – 40mm concrete cone combination. The experiment also indicates a positive correlation between reinforced concrete strength and pullout strength. Finally, it is our humble that the results from this study, together with other investigation will provide some help to improve, here in Taiwan, the reinforced concrete engineering in practice.
49
Liu, Te-Chun, and 劉得均. "Biomechanical investigation of miniscrews for orthodontic anchorage." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/09661690857240445198.
Full textAbstract:
碩士國立成功大學
口腔醫學研究所
94
Anchorage control plays an important and determinant role in successful orthodontic treatment. Recently, orthodontic miniscrews, used as temporary implants, have been widely used for anchorage control in clinical practice. Compared to the traditional dental implant anchorage systems, the advantages of miniscrew are simple to insert and to remove, less trauma surgery, less limitation in implant position, immediate loading and less cost. However, the failure of miniscrews in clinic is still bothering the orthodontists. It was hypothesized that bone quality, miniscrew dimensions, implanted depth, exposed length and force conditions would contribute to the failure of miniscrew. The aim of the present study was to investigate the biomechanical influences of these factors in miniscrews for orthodontic anchorage by finite element method and clinical data analysis. Eleven patients were included with total 20 miniscrews applied for orthodontic anchorage for clinical analysis. In finite element simulations, the three-dimensional model of bone block integrated with miniscrew was built. The evaluated parameters included cortex thickness, cancellous bone property, miniscrew diameter, miniscrew length, implanted depth, exposed length, force magnitude and force direction. The maximum von Mises stress of cortex and displacement of miniscrew were investigated and compared. The results showed that the maximum von Mises stress of cortex concentrated in the compressed surface adjacent to the miniscrew and the maximum displacement of miniscrew located at the top of screw head in all models. The tendency of changes of the stress and displacement related to these parameters were similar. In general, both stress and displacement increased with the decreasing of cortex thickness, decreasing of miniscrew diameter, increasing of exposed length, and were linearly proportioned to the force magnitude and had the largest values in 90° force direction. For various lengths of miniscrew, these two indices were almost unchanged when the exposed lengths were equal with the implanted depths larger than 2 mm. For the same miniscrew, both stress and displacement varied insignificantly under various cancellous bone properties with cortex thickness greater than 0.5 mm. This study concluded that to increase the clinical success rate of miniscrew anchorage, the cortex should be thicker than 0.5 mm; the miniscrew diameter should be greater than 1.2 mm; the implanted depth should be longer than 2 mm; the exposed length should be as short as possible; the force magnitude should not exceed the clinical indications; and the force direction should prevent perpendicular to the miniscrew axis.
50
Hung, Chin-tzung, and 洪進宗. "Anchorage Behavior of Removable Anchorsin Silty Sand." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/10326471692198987896.
Full textAbstract:
碩士國立成功大學
土木工程學系碩博士班
97
Tie-back anchors are selected to use for underground excavation in the metropolis to increase construction efficiency. It is also used as retaining struts which are limited to be used in the basement construction. The purpose of this study is to estimate the ultimate anchorage capacity and to analyze the deformation for the removable and extractable anchors used in silty sand deposits. The results of this study can be used as a reference for the anchor design and construction in underground engineering. This study based on the results of full scale anchors proving test and suitability test in field around Kaohsiung-Zouing area. The tensile loading, duration and deformation during testing are measured to determine the relationship between the ultimate anchorage capacity and elastic-plastic deformation. The results show that the failure mode of the removable and extractable anchors embedded in sility sand is the pull-out failure along the interface of anchorage and soil. The unit ultimate anchorage capacity is about 1 kg/cm2, and the ultimate loading is smaller while the anchorage segment length is longer than critical length. From the plastic deformation curve, the plastic deformation will be smaller while the fix length of grout is shorter. The anchorage capacity is mainly from the frictional force between grout and soil. The frictional force is increased with the plastic deformation.