Дисертації з теми "Strength and directionality of influence"
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1
Sell, Andrea J. "The influence of movement on the directionality of space-time representation mappings." Tallahassee, Florida : Florida State University, 2009. http://etd.lib.fsu.edu/theses/available/etd-10302009-134713/.
Повний текст джерелаАнотація:
Thesis (M.S.)--Florida State University, 2009.Advisor: Michael Kaschak, Florida State University, College of Arts and Sciences, Dept. of Psychology. Title and description from dissertation home page (viewed on May 14, 2010). Document formatted into pages; contains vii, 25 pages. Includes bibliographical references.
2
Erry, Gavin Robert Geoffrey. "The influence of sensor directionality in array and single-aperture imaging applications." Thesis, Loughborough University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285917.
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3
Stone, Michael H., Margaret E. Stone, and Kimitake Sato. "Endurance: Influence of Strength Training." Digital Commons @ East Tennessee State University, 2017. https://dc.etsu.edu/etsu-works/4572.
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4
Eriksson, Malin. "The Influence of Molecular Adhesion on Paper Strength." Doctoral thesis, Stockholm, Department of Fibre and Polymer Technology, School of Chemical Science and Engineering, KTH, Royal Institute of Technlology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4101.
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5
Zhang, Xiaobo. "Influence of drying pressure on interfibre bond strength." Thesis, KTH, Hållfasthetslära (Inst.), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-103891.
Повний текст джерелаАнотація:
In this thesis the influence of the drying pressure on interfibre bond strength was investigated. Five different drying pressures, 0.7, 2.9, 4.5, 6.7, and 15 kPa, were applied during the preparation of fiber-fiber cross test pieces. The nominal overlap area of each fibre-fibre cross was measured in a transmission light microscope. A tensile tester was used to record the loaddeformation behavior of each fiber-fiber cross. The final results of the interfibre bond strength were defined by both the overlap area and the maximum force of each bond. The results showed that the influence of drying pressure to the average strength were very weak, although a maximum could be seen at 2.9 kPa of drying pressure. Moreover, the results suggested the overall trend of decreasing strengths at very high drying pressures. Finally, a statistical significance study of the results was presented. In addition, the influences of fiber type (spring wood vs. summer wood) and press type (steel vs. steel or steel vs. rubber) on interfibre bond strength were also discussed.
6
Li, Kevin Ka Lun. "Influence of size on punching shear strength of concrete slabs." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0033/MQ64235.pdf.
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Li, Kevin Ka Lun 1975. "Influence of size on punching shear strength of concrete slabs." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=30259.
Повний текст джерелаАнотація:
The punching shear behaviour of interior slab-column connections in flat plates is investigated. The response of six two-way slab specimens, which were designed such that they would fail in punching shear, are presented. The parameter introduced in the experimental program is member depth. The effects of this parameter on the punching shear capacity of slab elements are investigated. The results show a strong "size effect", with deeper members having a smaller shear stresses at failure than shallow ones.Test results obtained from this experimental program are compared with the punching shear predictions of the Canadian CSA A23.3-94 Standard, the American ACI 318-95 Code, the British BS 8110-85 Standard and the European CEB-FIP 1990 Model Code. Predictions were also made using computer program "Response 2000", assuming an equivalent beam analogy to represent the slab. It is concluded that the shear design of slabs, according to the current Canadian and American codes, can be unconservative under certain conditions, particularity for thick slabs. It is recommended that the punching shear expressions of the CSA Standard and the ACI Code be modified to take into account the "size effect" on the punching shear strength of slabs.
8
Costello, Robert P. "The influence of distance and direction on ground combat strength." Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/28285.
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9
Kelly, Robert. "The influence of member orientation on hollow section joint strength." Thesis, University of Nottingham, 1998. http://eprints.nottingham.ac.uk/13287/.
Повний текст джерелаАнотація:
The influence of the member orientation on the strength of joints formed with square hollow sections is examined. The bird beak joint system is a relatively new truss arrangement for square hollow sections, where the chord and the brace have each been rotated by 45° about their own centreline axes. Based on previous experimental testing it has been suggested that this joint system leads to a stronger joint arrangement. Finite element analysis has been used to study the strength and behaviour of such bird beak joints and to compare them to similar joints in CHS and the traditional RHS configuration to test this claim. A comprehensive study has been undertaken for bird beak X -joints and T -joints and comparisons are made with similar traditional joints in RHS and CHS as the parameters of the width ratio ß, the chord slenderness ratio 2y and the chord length ratio a are varied. Displaced shape and contoured stress plots are included to aid understanding of the failure mechanisms. The finite element work on K -joints allows comparisons of the strength and stiffness of bird beak K -joints with those formed in the traditional RHS configuration as the boundary conditions (at the ends of the members), the brace angle and loading conditions are varied. A limited amount of experimental work has been carried out in the laboratories at Nottingham University, with some assistance from the author, involving the physical testing of bird beak joints so that the finite element models can be validated. This work is reported and examined critically. The conclusions focus on the claims that the bird beak joints are stronger and how they differ from the traditional form of joints. Equations are presented to extend the design information available for a practical parameter range.
10
Lombard, Le Riche. "Influence of surface seal variables on bitumen bond strength properties." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/95882.
Повний текст джерелаАнотація:
Thesis (MScEng)--Stellenbosch University, 2014.ENGLISH ABSTRACT: Surface seals are widely used in South Africa. There are a number of reasons which include affordability, versatility and durability. There are, however, in some cases problems with stone loss that can lead to a shortened lifespan of the pavement. The loss of aggregate chippings in surface seals poses a major problem in the seal pavement industry. This study aims to identify the influencing factors that lead to these adhesive failures as well as to find optimum combinations of binders and aggregates at various conditions. Various binders commonly used in South African surface seal construction will be tested using the Bitumen Bond Strength (BBS) test method. The binders used in the study include 80/100 penetration grade bitumen, elastomer modified bitumen, bitumen rubber, elastomer modified emulsion and cationic rapid setting emulsion. Aggregates used in the study include dolerite, granite and quartzite. The test samples were cured and tested at two temperatures, 15 °C and 35 °C. The samples were also cured for 2, 6 and 24 hours respectively. The study tackles a wide range of variables in order to obtain a good understanding of adhesion properties of surface seals used in South Africa. Tests were repeated at least once to ensure repeatability and in some cases up to four repeats were performed. The loading rate at which the tests were performed had a significant influence on the BBS results. This rate varied which complicated the process of comparing the results. It was therefore decided to unify the loading rates. The BBS results exposed the difference between hot applied binders and emulsions. The former having significant stronger adhesion properties. It was also confirmed by the results that temperature plays a key role in the BBS results due to the visco-elastic properties of bitumen. These influences will be discussed along with others such as aggregate types and curing times. The type of failure is also discussed. Failure can either be adhesive or cohesive, the former being a failure between the aggregate and the binder while the later refers to a failure in the binder itself. The results of other students will also be discussed and compared to the results of this study. These include results of predecessors that tested emulsions as well as results from tests done on fractured aggregate surfaces and precoated aggregates. This study showed very similar results as these from other students, except for tests done with emulsions. It was discovered that the method of curing of the emulsions must be adapted to ensure proper curing of the emulsions. It was found that aggregates did not influence the BBS properties to the same extent as temperature and binder application type. The BBS results of hot applied binders also did not significantly increase as the curing time increased, but the results of emulsions showed some increase. However, the emulsions needed more time to cure properly.
AFRIKAANSE OPSOMMING: Oppervlak seëls word algemeen gebruik in Suid-Afrika. Daar is verskeie redes hiervoor waaronder bekostigbaarheid,veelsydigheid en duursaamheid. Daar is egter in sommige gevalle probleme met klipverlies wat kan lei tot n verkorte leeftyd. Hierdie klipverlies ontstaan as gevolg van verskeie redes of kombinasies daarvan. Die studie beoog om hierdie faktore wat die adhesie eienskappe beïnvloed te identifiseer sowel as om optimum kobinasies van bindmiddels en klipsoorte te bewerkstellig by verkeie kondisies. ‘n Verskeidenheid van bindmiddels wat algemeen in Suid-Afrika gebruik word, word in die studie getoets met die Bitumen Bond Sterkte (BBS) toets metode. Die bindmiddels wat in die studie gebruik word sluit 80/100 penetrasie graad bitumen, elastomeer gemodifiseerde bitumen, bitumen rubber, elastomeer gemodifiseerde emulsie en kationiese snel settende emulsie. Die klipsoorte wat vir die studie gebruikword is doleriet, graniet en kwartsiet. Hierdie gesteentes word algemeen in die praktyk gebruik. Die toets monsters word ook by twee temperature gekuur en getoets. Hierdie temperature is 15 °C en 35 °C. Die toets monsters word ook onderskeidelik vir 2, 6 en 24 uur gekuur. Die studie ondersoek 'n wye verskeidenheid van veranderlikes om sodoende 'n goeie begrip van adhesie eienskappe van die oppervlak seëls wat in Suid-Afrika gebruik word te verkry. Elke toets was ten minste een maal herhaal om herhaalbaarheid te verseker. Sommige toetse was tot 4 keer herhaal. Die belasting tempo van die toetse het ‘n beduidende uitwerking op die BBS resultate as gevolg van die visko-elastiese eienskappe van bitumen. Hierdie tempo het gewissel en dit moeilik gemaak om die resultate te vergelyk. Daarom was daar besluit om die tempo van die toetse te verander na ‘n gelykvormige tempo. Daar was ‘n duidelike verskil in BBS resultate van die warm toegepaste bindmiddels en die emulsies. Die warm bindmiddels het baie hoër BBS resultate gelwer. Dit was ook bevestig in die resultate dat temperatuur ‘n beduidende rol speel in die BBS. Hierdie invloede sal bespreek word tesame met ander, soos klipsoorte en kuring tye. Die tipe versaking word ook bespreek. Versaking kan plaasvind as gevolg van adhesie of cohesie, waar adhesie versaking 'n versaking is tussen die klip en die bindmiddel terwyl cohesie versaking verwys na 'n versaking in die bindmiddel self. Die uitslae van die ander studente sal ook bespreek word en vergelyking word met die resultate van hierdie studie. Dit sluit die resultate van voorgangers in wat emulsies getoets het sowel as die resultate van toetse wat gedoen is op gebreekte klipoppervlaktes en bitumen behandelde klippe. Hierdie studie het baie soortgelyke resultate getoon as dié van ander studente, behalwe vir die toetse wat gedoen was met emulsies. Daar is vasgestel dat die metode van kuring van die emulsies moet aangepas word om behoorlike kuring van die emulsies te verseker. Daar is ook gevind dat klipsoorte nie die BBS eienskappe in dieselfde mate as temperatuur en bindmiddel toepassingstipe beïnvloed het nie. Die BBS resultate van warm aangewende bindmiddels het ook nie aansienlik verhoog soos die kuringstyd toegeneem het nie, maar die resultate van emulsies het wel 'n toename getoon. Die emulsies het wel meer tyd nodig gehad om behoorlik te kuur.
11
Talotti, Marco. "Influence of substrate moisture preparation on concrete overlay bond strength." Master's thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/9080.
Повний текст джерелаАнотація:
Includes bibliographical references.A considerable amount of progress has been made over the years in understanding the fundamentals of concrete composition and performance in both safe and harsh environments. Nevertheless, premature concrete deterioration remains a concern and is often experienced either due to poor workmanship or design. The bonded concrete overlay technique has become a popular method in repairing these deteriorated concrete structures, as it has a simplistic application procedure and can be applied to a number of different scenarios. This technique involves the removal of the distressed layer of concrete (substrate), followed by the application of a fresh, new layer of concrete (overlay). One of the fundamentals behind bonded concrete overlays is the bond between the existing and new concrete layer. Sufficient bond strength is a prerequisite for the durability and serviceability of a repaired concrete structure. Factors which have been considered most important for achieving a good bond between the substrate and overlay are cleanliness and preparation of the substrate, together with overlay compaction and composition. However, the impact of substrate moisture condition on the bond strength of a repaired member has not been fully investigated and still raises many debates amongst engineers. Current best practice suggests that a concrete substrate which is preconditioned to a saturated surface dry state prior to overlay application will achieve higher bond strengths. This investigation provides insight into the aforementioned through both literature research and practical experiments performed. In this investigation the effects of moisture preparation on bond strength were tested on three different substrate concretes, together with the application of four overlays. The substrates varied according to strength grade (50, 30 and 25 MPa), whereas the overlays varied in both strength (40 and 25 MPa) and workability (30 and 120 mm slump). The accompanied bond strength was established through interface shear testing. All substrates of the repaired specimens were subjected to a constant surface roughness and equally aged to prevent any differential shrinkage which may falsify bond strength readings. The bond strength results were plotted, statistically evaluated and compared with existing literature.
12
Söderlund, Anders. "Influence of surface flatness on bolted flanges : Fatigue strength limit." Thesis, Karlstads universitet, Materialvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-62661.
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13
Roko, Raoul Olatounbossoun. "Roughness influence on strength and deformation behavior of rock discontinuities." Diss., The University of Arizona, 1990. http://hdl.handle.net/10150/185322.
Повний текст джерелаАнотація:
The influence of discontinuity roughness on the shear strength and deformation behavior of rock joint is analyzed. The study is divided into three parts: laboratory direct shear test on rock samples having different roughness characteristics, characterization of roughness profiles using variogram and probability density distribution and the application of dynamical systems theory to analyze the stability condition of the sliding motion. The relative motion along the rough joint is erratic particularly at a low normal load. A steady motion develops as the normal load increases. The kinematics of translational motion has two distinct characteristics: the translation occurs as a result of a gross and uniform motion (sliding) and/or through localized inhomogeneous motion (slipping). Three modes of volumetric changes are observed during the tangential motion: a dilatant-contractant behavior with the overall volumetric change being strictly dilatant, a dilatant-contractant behavior with the overall volumetric change varying from dilatant to contractant and the strictly contractant behavior. The size of the sheared zones is a function of the distribution of the asperities and of the interface strength. The coefficient of friction decreases as the normal load increases. It may or may not increase when the normal load is decreased. The probability density distribution of the height of the interface asperities is not always Gaussian. The variation of the experimental distribution (histogram) indicates that the asperities are not necessarily sheared off in order of decreasing height but rather on the basis of the condition underlying the existence of contact. The slope of the initial portion of the variogram and the sill, when it exists, are used to characterize the surface morphology of the discontinuity. The lower the slope, the smoother the surface. Two types of anisotropy are observed: geometic anisotropy (elliptic shape) and zonal anisotropy. The rate of collapse of the boundary of the loop describing the roughness of the interface describes the deformation of the discontinuity. The location of the orbit with respect to the stagnation line depends on the normalized stiffness. As the normalized shear stiffness increases, the orbit tends to collapse towards the stagnation axis.
14
Al-Sabbagh, Muhanad Nazar. "Influence of contact strength between particles on constitutive law for powder compaction and the strength of powder compacts." Thesis, University of Leicester, 2018. http://hdl.handle.net/2381/42788.
Повний текст джерелаАнотація:
Powder compaction is used in a wide range of industrial applications ranging from powder metallurgy, food, pharmaceuticals, consumer goods, catalysts, fuels briquettes, etc. Powder compaction can be defined in terms of 1) compactibility, which represents the ability to form strong compacts, which is quantified by compact strength and 2) compressibility, which represents the ability of the powder mass to form dense compacts and is described by the constitutive law. The aim of this work is to establish relationships between particle properties, (including mechanical properties of particles and interactions between particles, which are included in the contact law), and bulk powder properties (including compactibility and compressibility). Excipients used in pharmaceutical tablet formulations, such as microcrystalline cellulose, calcium phosphate and mannitol (a sugar) and their mixtures were characterised. Compacts of different densities were manufactured and their compressive and tensile strength was measured. The break force of curved faced tablet made of these materials and mixtures was also measured under an extensive range of conditions. A predictive model was developed and validated to estimate the break force of curved faced tablets using diametrical and uniaxial compression tests only; this has a significant practical importance in the pharmaceutical industry. The mechanical properties of individual particles were characterised using nano-indentation. The data for pharmaceutical excipient were augmented with results for a model powder material consisting of spherical aluminium particles. The now classic micromechanical model of Fleck was used as a theoretical framework to relate particle properties and constitutive laws for compaction. A parameter describing the strength of contact between particles was estimated using the strength of compacts. The contact strength parameter was then related to adhesive contact laws between particles. This work represents the first complete framework for relating contact law (which includes the elastic and plastic properties that determine the deformation of particles in contact and the friction and adhesion between particles) to compact strength.
15
Halleros, Solya, and Mikael Nordqvist. "The strength of digital narratives : Expolring value creation and customer influence." Thesis, Umeå universitet, Institutionen för informatik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-147924.
Повний текст джерелаАнотація:
Social media has become one of the main platforms for telling stories, not only for individualsbut also for corporations of all sizes. The published content on these platforms can be assimple as a picture or lines of text as long as they captures the attentions of other users theywill qualify as a digital story or narrative. This opens up for effortless interaction betweencustomers and corporation, but also for value creation alongside the two parties. Otherresearchers has contributed with different takes of how this value creation can be conductedand defined. Our contribution aims to closer examine how consumer interaction and valuecreation can strengthen digital narratives. We will not aim to standardise how a digital storyshould be told, but provide guidelines for designing narratives that include the public as astory contributor by seeing if there is a correlation between the choice of social mediaplatforms used and the type of stories the organizations narrate.
16
MacLeod, Gavin Drew. "Influence of concrete strength on the behaviour of bridge pier caps." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ29612.pdf.
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Yi, Sŏk-wŏn. "Influence of surface topography on interface strength and counterface soil structure." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/19559.
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MacLeod, Gavin 1972. "Influence of concrete strength on the behaviour of bridge pier caps." Thesis, McGill University, 1997. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=27239.
Повний текст джерелаАнотація:
Two full-scale reinforced concrete bridge pier caps were constructed and tested to investigate the influence of concrete strength on their behaviour. The amount of uniformly distributed reinforcement required for crack control at service load levels was also varied in order to investigate the suitability of current design approaches for these disturbed regions. In addition, strut-and-tie models, refined strut-and-tie models and non-linear finite element analyses are used to predict the complete behaviour of the test specimens.
19
Betamar, Naeima Mohamed. "Influence of specimen designs on the microtensile bond strength to dentine." Thesis, University of Sheffield, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.489353.
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Pappas, Maria. "Influence of a 3-step disinfection procedure on dentin bond strength." VCU Scholars Compass, 2004. http://scholarscompass.vcu.edu/etd/850.
Повний текст джерелаАнотація:
Statement of problem. Clinicians have used disinfection materials to remove surface contaminants during cavity preparation. It has been postulated that disinfection materials may negatively affect shear bond strength of restorative materials. If so, large numbers of restorations may be predestined for early failure with the use of a disinfection protocol.Purpose. To determine whether there is a difference in the bond strength between dentin and composite resin with a 3-step disinfection technique compared to a conventional bonding technique without the additional disinfection protocol.Material and Methods. Sixty human molar teeth were sectioned parallel to the occlusal surface to expose mid-coronal dentin and mounted parallel to a bond shearing device on a universal testing machine (Instron) and randomly divided into 2 groups. In Group I (n=30), specimens were treated with chlorhexidine, tubulicid red, and sodium hypochlorite before dentin bonding, following the manufacturer's instructions for All Bond 2. In Group II (n=30), specimens were treated only with the bonding protocol of All Bond 2. To ensure a uniform bond surface area, core paste was syringed into a cylindrical mold (diameter 2.38mm, height 2.00mm) that was in contact with the dentin bonding surface of each specimen, and allowed to set under constant force. All specimens were subjected to fracture by shear loading in a universal testing machine (Instron) at a uniform crosshead speed of 0.02 inch per minute and expressed as MPa. Statistical analysis, using nonpaired student's t-test, was performed. Results. A statistically-significant higher shear bond strength was found for the 3-step disinfection group (mean shear bond strength, 25.3; STD, 4.6) compared to the conventional bonding group (mean shear bond strength, 20.5, STD, 3.4) (PConclusions. The 3-step disinfection technique group showed a significantly stronger dentin shear bond strength compared to the conventional bonding technique without disinfection.
21
Hall, Emily. "Modelling the influence of porosity on fatigue strength of sintered steels." Thesis, Uppsala universitet, Strukturkemi, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-398977.
Повний текст джерелаАнотація:
The pores in pressed and sintered components constitute weak points in the material since the stress concentration is larger than the nominal stress there. Therefore, fatigue cracks initiate at the pores. Specifically, it can be assumed that the fatigue cracks initiate at the largest pore in the stressed volume. Studies have previously looked at finding ways to model the fatigue strength of the material based on the largest pore. This thesis looks at a model previously derived for hardened pressed and sintered materials that is based on linear elastic fracture mechanics and investigates if said model can be modified to include non-hardened pressed and sintered materials that do not necessarily behave linear elastically. A model describing the influence of the size of the largest pore on the fatigue limit using empirical coefficients is suggested. Furthermore, the area of the largest pore is modelled using extreme value statistics. The model proved successful in modelling the density effect of the porosity on the fatigue strength for two materials with different microstructures: one with a homogeneous microstructure and one with a heterogeneous microstructure. For the material with the homogenoeous microstructure the model also accounted well for the notch effect when tested on samples with a different geometry. However, for the heterogeneous material the model did not account for the notch effect. Deformation hardening due to local plastic deformation in the softer phases was suggested as a possible explanation and was supported by tensile tests.
22
Halilovic, Armin. "A micromechanical study of the combined influence of refining and strength additives on stiffness and strength in a paper." Thesis, KTH, Hållfasthetslära (Inst.), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-175701.
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23
Kaaki, Ahmad Abdullah. "The influence of faults on the engineering behavior of rock masses." Thesis, University of Newcastle Upon Tyne, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308836.
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24
Kairouz, Kays Clement. "The influence of stacking sequence on the strength of bonded CFRP joints." Thesis, Imperial College London, 1991. http://hdl.handle.net/10044/1/46855.
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25
Tang, Denglei, and Denglei Tang@gmail com. "Influence of Chloride-induced corrosion cracks on the strength of reinforced concrete." RMIT University. Civil, Environmental and Chemical Engineering, 2008. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080530.091350.
Повний текст джерелаАнотація:
In marine environments and where de-icing salts are applied, the degradation of reinforced concrete structures due to chloride induced corrosion of the reinforcement is a major problem. The expansive nature of the corrosion process results in cracking of the concrete and eventually spalling. In order to select suitable remedial measures it is necessary to make an assessment of the residual strength and the residual life. In order to investigate the effect of corrosion on bond strength of the reinforcement, specimens comprising square prismatic sections containing steel reinforcement in the four corners have been subjected to a wet-dry cycle and corrosion has been accelerated by polarising the bars. The research has studied the change of bond strength with level of corrosion for 12 mm and 16 mm bars with concrete cover of 1 and 3 times the bar size. The bond strength is assessed by means of pull out tests and the corresponding extent of corrosion has been assessed in terms of the mass loss. Observations and measurements of the form of the corrosion (pit dimensions and loss of bar diameter) are also presented. The relationship between bond strength and surface crack width has been investigated. Results show that the surface crack width may be a good indicator of residual bond strength. In addition, the influence on bond strength of concrete compressive strength, reinforcement cover, bar position and bar size on the change of bond strength has been explored. It should be noted that all conclusions drawn in this project are based on tests on specimens without shear reinforcement (unconfined) and that accelerated corrosion (by impressed current) has been adopted. Consequently, care should be exercised in applying these results directly to structures in the field. Additional research is needed to assess the influence of impressed current on crack patterns and the effect of shear reinforcement.
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Bobyliov, Konstantin. "Casting voids influence on spheroid graphite cast iron high-cycle fatigue strength." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2008. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2008~D_20081128_120950-42235.
Повний текст джерелаАнотація:
The influence of casting voids on spheroid cast iron cracking threshold is investigated. The experimental results and their analytical and numerical analysis basing on linear fracture mechanics is presented.Nagrinėjamas liejimo tuštumų poveikis stipriojo ketaus pleišėjimo slenksčiui. Pateikiami eksperimentiniai rezultatai ir jų analitinė bei skaitinė analizė, remiantis tiesine irimo mechanika.
Исследуется влияние литейных пустот на порог трещиностойкости чугуна с шаровидным графитом. Представлены результаты экспериментального исследования и их аналитический и численный анализ, опираясь на линейную механику разрушения.
27
Ohu, John Olutunde. "Peatmoss influence on strength, hydraulic characteristics and crop production of compacted soils." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=71960.
Повний текст джерелаАнотація:
The quantitative effects of increasing the organic matter contents of three soils upon their susceptibility to compaction, the recovery of tilth after compaction and the fertility of the soils were investigated. These effects were further studied on the production of bush bean (Phaseolus vulgaris).Soil consistency limits, soil water status, applied pressure and organic matter contents were used to predict shear strength, penetration resistance and water retention characteristics of compacted soils, with the aim of meeting the widespread demand for possible techniques of soil compaction prediction.
Soil compaction increased the ability of the soils to retain moisture, increased penetration resistance, shear strength and decreased the available water capacity of soils. On the other hand, organic matter increased the ability of the soils to retain moisture, expanded the available water capacity and decreased the penetration resistance and shear strength of compacted soils.
Although soil compaction increased the stem diameter of bush bean; the height, yields and root dry matter of the crop decreased with higher compaction levels. On the contrary, higher organic matter levels increased the plant and yield parameters of the crop.
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Ebuk, Ebuk John. "The influence of fabric on the shear strength characteristics of weathered granites." Thesis, University of Leeds, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303426.
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Bogahawatta, Vedananda Tilakasiri Loku. "The influence of fabrication effects on the strength of fired clay products." Thesis, Queen Mary, University of London, 1990. http://qmro.qmul.ac.uk/xmlui/handle/123456789/25783.
Повний текст джерелаАнотація:
A study has been made of the enhancement of the mechanical strength of bricks fabricated from five Sri Lankan Quaternary and post-Quaternary brick clays with the objective of identifying and optimising those factors which control the quality and performance characteristics of fired clay products of this type. Mineralogical investigations have shown that the clays are predominantly kaolinitic. Of the accessory minerals, feldspars and gibbsite are the chief constituents. The experimental programme involved the development of feasible processing techniques for clay bodies, the establishment of optimum heat treatments for their firing, and the testing and evaluation of material properties of the fired products. The microstructures of fired materials have been characterized using optical and electron microscopical techniques, as well as X-ray diffraction, electron probe microanalysis and chemical analysis. A limited study was also made of the durability of laboratory fired specimens. Methods of strength enhancement included use of the reactions of phosphates with natural clays, use of mineralizers to induce mullitization and surface coating by an efflorescence process. A kinetic analysis based on the first order kinetics is proposed for the estimation of optimum firing conditions for kaolinitic clays. The study has shown that surface coating of bricks increases the load at the elastic limit by up to 30% and the ultimate failing load by 19% in the clays examined. The measured increases in modulus of rupture and modulus of elasticity are over 33% and 40% respectively. A fabrication technique which requires the incorporation of phosphates has been developed. This provides the possibility of lowering the peak temperature of firing to 500°C. Flexural strength increase of up to 60% over the normally fired unbonded specimens can be achieved using this technique. Relevant compatibility relations in the ternary system Si02- P205-AI203 at 500'C are proposed. The presence of an optimum amount of mineralizer in a clay body may alter its sintering characteristics resulting in an increase in modulus of rupture up to 55%. However, uncontrolled additions exceeding 4 wt% cause deleterious effects. Microstructural analysis provides evidence that liquid phase sintering, development of mullite, development of pores and bloating are the dominant strength determining features in these clays. An empirical equation correlating the functional relation between modulus of rupture, mullite content and porosity is proposed. Mechanisms of strength development are discussed in the light of these findings.
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RODRIGUES, SUELEN. "INFLUENCE OF LOADING RATE ON THE BOND STRENGTH BETWEEN CFC AND CONCRETE." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2009. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=15133@1.
Повний текст джерелаАнотація:
PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
Neste trabalho é realizada uma investigação experimental sobre os efeitos de cargas de impacto sobre a resistência de aderência entre o compósito de fibras de carbono e o concreto. O objetivo foi verificar a influência da taxa de carregamento sobre a resistência de aderência. O programa experimental consistiu em ensaios de quarenta e cinco corpos-de-prova, constituídos de blocos de concreto e tiras de fibras de carbono coladas nas laterais opostas dos blocos. As variáveis de estudo foram a resistência à compressão do concreto (25 MPa, 45 MPa e 65 MPa) e a taxa de carregamento que variou de um mínimo de 1,92 MPa/s (estático) para um máximo de 438685 MPa/s (dinâmico). Os resultados dos ensaios mostraram que a resistência de aderência foi afetada pela taxa de carregamento.
An experimental investigation on the effects of impact loading on the bond strength between carbon fiber composite and concrete is described in this work. The objective was to verify the influence of loading rate on the bond strength. The experimental program consisted on testing of forty five specimens made of concrete blocks and carbon fiber strips glued on opposite sides of the block. The variables studied were the concrete compressive strength (25 MPa, 45 MPa and 65 MPa) and loading rate which varied from a minimum of 1,92 MPa/s (static) to a maximum of 438685 MPa/s (dynamic). Test results showed that the bond strength was affected by loading rate.
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Karam, Jeffrey Ramzi. "Influence of constituents' properties on the fracture properties of high strength concrete." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/44478.
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Light, Thaddeus. "The Influence of Strength in Load-Velocity Relationships in the Back Squat." Digital Commons @ East Tennessee State University, 2019. https://dc.etsu.edu/etd/3611.
Повний текст джерелаАнотація:
Load-velocity relationships may vary between people of different strength levels and across different loads. The purpose of this dissertation was to investigate how external loads influence the velocity characteristics of the back squat exercise, and the influence of strength on these variables. Healthy male students with a history of resistance training completed repetitions at specified intensities of their estimated one-repetition maximum (1RM) until they reached 1RM. Back squat 3D motion analysis was captured using four Vicon T010 cameras (Vicon Motion Systems Ltd.; Oxford, UK) and Vicon Nexus 1.8.5 software. Data were transported into R custom coding statistical analysis software (version 3.5.2; The R Foundation) to calculate velocity analyses which determined mean and peak concentric (MCV, PCV) and eccentric (MEV, PEV) values. Participants were grouped by their relative strength (body mass/1RM) in the back squat, as well as their ability to move often prescribed loads with greater speed (63-70%1RM, 83-87%1RM). Between-groups comparisons were made for MCV at all loading conditions, and correlational relationships between all velocity measures (MEV, PEV, MCV, PCV) were examined for each group. For all subjects, there was a significant effect for relative intensity (%1RM) on MCV, but only for the groups organized by MCV at 63-70%1RM and 83-87%1RM was there a between-subjects effect for group. Correlational analyses between velocity measurements during concentric and eccentric phase of the back squat showed a tendency for high relationships (r = 0.5-0.69) between all phases that weakened as the relative intensity increased. These differences were illustrated uniquely between subject grouping conditions. These results indicate that load-velocity characteristics of the back squat cannot necessarily be positively related to strength level in the movement, and that profiling athletes by their velocities at specific relative intensities could be an effective means of organization.
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Whittington, J. M., E. J. Shoen, L. L. Labounty, Jeremy A. Gentles, Jenna M. Kraska, Ann Marie Swisher, J. E. Keller, et al. "Bone Mineral Density and Content of Collegiate Throwers: Influence of Maximum Strength." Digital Commons @ East Tennessee State University, 2008. https://dc.etsu.edu/etsu-works/4094.
Повний текст джерелаАнотація:
Bone is a plastic tissue, changing in density and size with different levels of stress. Furthermore, it appears that BMD is altered in a site specific manner. However, BMD has not been studied extensively in all types of athletes, particularly well trained strengthpower athletes, such as throwers. The pwpose of this study was to examine the BMD of USA Division I collegiate throwers (shot put, discus, etc.). BMD was compared to normative data and to different athletes. Measures of whole body maximum strength and throwing performance were correlated with BMDs. Potential right/left side and sex differences were examined. Athletes were 4 males, 3 females age 19.9 ± 0.9 years. BMD was measured with a DEXA Maximum isometric strength was measured using a midthigh pull standing on a force plate. Force time-curves were generated during the strength tests. Peale force (PF) and normalized pealc force (PFa) were correlated with BMDs. Comparison indicates throwers have denser bones compared to normative data and compared to other types of athletes. Male throwers tend to have greater total body BMD than female throwers (p < 0.05). Dominant arm showed slightly greater BMD compared to non-dominant (p < 0.05). Furthermore, BMD is related to PF (r = 0.68) and PFa (r = 0.56). Throwers have greater BMD's than non-athletes or most other types of athletes. However, throwers showed only a small indication of sidedness. These observations likely stem from their training program (whole body heavy loading).
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Whittington, J. M., E. J. Schoen, L. L. Labounty, R. Hamdy, Michael W. Ramsey, Margaret E. Stone, William A. Sands, G. Gregory Haff, and Michael H. Stone. "Bone Mineral Density and Contet of Collegiate Throwers: Influence of Maximum Strength." Digital Commons @ East Tennessee State University, 2009. https://dc.etsu.edu/etsu-works/4128.
Повний текст джерелаАнотація:
AIM: Bone changes in size and density in response to different levels of stress. Alterations to bone mineral density (BMD) appear to occur in a site specific manner. Even though BMD has been examined in many populations there is a paucity of data looking at strength-power athletes, such as throwers. Therefore, the purpose of this study was to examine the BMD of a group of USA Division I collegiate throwers (e.g. shot put, discus, etc.). METHODS: Seven throwers (4 males; 3 females) who were 19.0 ± 0.9 years had their BMD compared to an age matched control group (n=14; 8 women and 6 men) and normative data. BMD was measured with dual X-ray absorptometry. Potential right/left side and sex difference in BMD were also examined. Maximal isometric strength was assessed using a mid-thigh pull while standing on a forceplate which generated force-time curves. Peak force (PF) and normalized peak force (PFa) were then correlated with BMDs. RESULTS: Generally, throwers had denser bones with male throwers tending to have a greater total BMD (P≤0.05). The dominant arm BMD was slightly greater when compared to non-dominant arm (P≤0.05). Furthermore, total body BMD was related to PF (r=0.68, r2 =0.46) and PFa (r=0.56, r2=0.31). CONCLUSIONS: Throwers have greater BMDs than non-athletes and most other athletes. However, throwers only showed a small indication of sidedness. It is likely that the BMDs observed in this study stem from the training intervention (e.g. whole body heavy lifting) undertaken by this population.
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Miyazaki, Natsumi. "Influence of Porosity and Pore-Distributions on Strength Properties of Porous Ceramics." Kyoto University, 2019. http://hdl.handle.net/2433/244569.
Повний текст джерела
36
Coyne, Joseph. "Influence of anthropometric and upper body strength qualities on surfboard paddling kinematics." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2015. https://ro.ecu.edu.au/theses/1664.
Повний текст джерелаАнотація:
Competitive surfing is an international professional water sport of which a key factor in performance appears to be surfboard paddling ability. Research on surfing performance is relatively novel and there is very limited data as to how anthropometric and upper extremity strength variables influence not just surfboard paddling but also surfing ability.
PURPOSE: The purpose of this research was threefold. The first purpose was to evaluate the reliability of Pull Up and Dip 1RM strength assessments, the ratio between the two exercises, and a surfboard endurance paddle assessment. The second purpose was to establish if there were discriminative factors between competitive and recreational surfers on these measures, and correlations between anthropometric, strength and paddling variables. The final purpose was to determine if upper extremity maximal strength training would improve surfboard paddling performance. METHODS: Thirty-six male surfers (29.7 ± 7.7 years, 177.4 ± 7.4cm, 76.7 ± 9.9kg) participated in this research. Subjects performed a tempo and range of motion controlled 1RM Pull and Dip assessment followed by a timed 400m endurance paddle on 2 days with 7 days separating testing sessions. Reliability was assessed by Intra-Class Correlation (ICC), Percent Coefficient of Variation (%CV) and Typical Error (TE). These tests along with a 15m sprint paddle test and additional anthropometric assessments were evaluated to determine if correlations between tests existed and if there were any differences between competitive and recreational surfers. Subjects were then placed into either intervention or control groups with the intervention group training the Pull Up and Dip exercises three times per week for 5 weeks.
RESULTS: All performance measures were considered reliable (ICC 0.96, 0.97 and 0.99; %CV 2.22, 2.41 and 2.01 for Relative 1RM Pull Up, Dip and 400m paddle respectively). A relative 1RM dip : pull up ratio of 1.11 was established. Fat mass and relative arm span were both correlated with paddling speed across sprint (p=0.02 to 0.04 and 0.01 respectively) and with even greater statistical power for endurance (p=0.01 andd=0.62-1.05).
CONCLUSIONS: Performance measures of 1RM Pull Up and Dip strength and endurance paddling are reliable when assessing upper extremity strength qualities in male surfers. Relative strength in the Pull Up and Dip are both correlated with sprint paddling ability. Significant differences in relative arm span and endurance paddling ability between competitive and recreational surfers appear to exist. Further, upper extremity maximal strength training can improve paddling ability in surfers; and especially so in weaker surfers.
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McGillivray, Catherine Black. "Lubrication mechanisms and their influence on interface strength during installation of subsurface pipes." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31851.
Повний текст джерелаАнотація:
Thesis (Ph.D)--Geosystems, Georgia Institute of Technology, 2010.Committee Chair: Frost, J. David; Committee Member: Burns, Susan E.; Committee Member: Gokhale, Arun; Committee Member: Mayne, Paul W.; Committee Member: Rix, Glenn J. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Hanno, Mithaq Elias. "Influence of Ferrite Content on Fatigue Strength of Quenched and Tempered 42CrMoS4 Steel." Thesis, KTH, Materialvetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-102023.
Повний текст джерелаАнотація:
Specimens of steel 42CrMoS4 were quenched from the austenite (γ) and the ferrite (α) + austenite + cementite phase fields to produce fully martensitic matrices with 0 – 14 % ferrite dispersed in the matrix. After tempering at 300°C or 600°C mechanical and fatigue properties were determined. As expected yield strength, tensile strength and hardness decreased with increased tempering temperature and ferrite content. Quite unexpected, the fatigue properties were mildly affected. A small amount of ferrite, approximately 3% even appears to improve the fatigue strength. Then, at even higher ferrite amounts, slightly below 20% the fatigue strength appears to decrease again.
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Hellqvist, Anna. "The Process Influence on Strength Properties of an Austenitic Stainless Steel (254 SMO)." Thesis, Örebro universitet, Institutionen för naturvetenskap och teknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-35545.
Повний текст джерелаАнотація:
This work has been performed at Outokumpu Stainless AB, QPE, in Degerfors where focus is on production of hot rolled tailor-made quarto plate in special stainless steel grades such as highly alloyed austenitics and duplex steel grades. After a period with low values in strength and a lot of deviations in tensile tests for the highly alloyed austenitic stainless steel, 254 SMO, there was a need to investigate what influence some parameters during process has on strength values. Process parameters during hot rolling and levelling have been examined to see if there is a connection between these and the strength. A statistical data base has been created to investigate the connection with strength. There has been experimental work involving two test plates in different dimensions to see how a double/extended heat treatment influence the sigma phase values and grain size, and if these can be connected to the strength values. The test plates have also been used to investigate how the position of the test coupon is affecting the tensile test result. Moreover, there have been tests performed in the cold plate leveller. The strength is a complex problem since there are many parameters that contribute to a variation in strength value. It is possible to see an influence from the investigated parameters, but their individual impact on strength varies. There are several indications in the results that the flatness seems to be a factor affecting the variation in strength. However, there is a need for more thorough investigations where the flatness can be measured to completely verify thisDet här arbetet har utförts på Outokumpu Stainless AB, QPE, i Degerfors där man inriktar sig på produktion av varmvalsad, skräddarsydd kvartoplåt i olika specialstål som höglegerade austeniter och duplexa stålsorter. Efter en period med låga värden i hållfasthet och många avvikelser i provning för ett höglegerat austenitiskt stål, 254 SMO, så fanns ett behov av att undersöka vissa parametrars inverkan på hållfastheten. Processparametrar vid valsning och riktning har undersökts för att se om det går att se ett samband mellan dessa och hållfastheten. Statistisk data har tagits fram för att undersöka sambandet med hållfastheten. Även experimentella försök har gjorts, främst på två testplåtar i olika dimensioner, för att se hur en dubbel/förlängd värmebehandling påverkar sigmafas och kornstorlek men även om dessa värden, genom försöken, kan kopplas till hållfasthetsvärden. Plåtarna har också använts till att se hur testresultatet påverkas av var i plåten som testkupongen tas ut. Dessutom har det gjorts försök i riktverket med olika parametrar. Hållfastheten är ett komplext problem att utreda eftersom det finns så många parametrar som ger en variation i resultaten. Det är möjligt att se en påverkan från flera av de undersökta parametrarna men deras individuella påverkan på hållfastheten varierar. Det finns många indikationer i resultaten som pekar på att planheten verkar vara en faktor som påverkar den variation som finns i resultat. Dock behövs det grundligare undersökningar där planheten kan mätas för att helt verifiera detta.
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Sagaseta, Albajar Juan. "The influence of aggregate fracture on the shear strength of reinforced concrete beams." Thesis, Imperial College London, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.686179.
Повний текст джерела
41
Green, Brandeis H. "The Moderating Influence of Strength on Depression and Suicide in African American Women." Digital Archive @ GSU, 2012. http://digitalarchive.gsu.edu/psych_diss/98.
Повний текст джерелаАнотація:
Strength for African American women and its psychological ramifications are being newly conceptualized and explored empirically in psychological research. The Strong Black Woman Attitudes Scale, (Thompson, 2003) was created to empirically test a three factor theoretical model: self reliance, affect regulation, and caretaking as a reliable culturally relevant coping mechanism for African American women. The primary aim of this study is to explore if cultural coping (SBW) moderates the relationship between depression and suicide in African American women. Other aims include, replicating the factor structure of the SBWAS with a community sample, and examining relationships between the SBW, racial identity, traditional coping, and depression. The Strong Black Woman Attitude Scale (SBWAS) was used to measure cultural coping, and the Ways of Coping Questionnaire (WOCQ) was used to measure traditional coping. Racial regard and centrality subscales from the Multidimensional Inventory of Black Identity (MIBI) measured racial identity and the Beck Depression Inventory (BDI) and Beck Suicide Scale (BSS) measured depression and suicide respectively. Results showed significant moderations for the total SBW score and the affect regulation subscale. Additionally, racial identity was positively associated with cultural coping, and cultural coping was negatively associated with traditional coping. Depression was positively related to the SBW and suicide. The three factor model was also upheld. The results of this study support the notion that strength for African American women can have detrimental psychological effects on women utilizing this coping style.
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Green, Brandeis H. "The Moderating Influence of Strength on Depression and Suicide in African American Women." Digital Archive @ GSU, 2011. http://digitalarchive.gsu.edu/psych_diss/107.
Повний текст джерелаАнотація:
Strength for African American women and its psychological ramifications are being newly conceptualized and explored empirically in psychological research. The Strong Black Woman Attitudes Scale, (Thompson, 2003) was created to empirically test a three factor theoretical model: self reliance, affect regulation, and caretaking as a reliable culturally relevant coping mechanism for African American women. The primary aim of this study is to explore if cultural coping (SBW) moderates the relationship between depression and suicide in African American women. Other aims include, replicating the factor structure of the SBWAS with a community sample, and examining relationships between the SBW, racial identity, traditional coping, and depression. The Strong Black Woman Attitude Scale (SBWAS) was used to measure cultural coping, and the Ways of Coping Questionnaire (WOCQ) was used to measure traditional coping. Racial regard and centrality subscales from the Multidimensional Inventory of Black Identity (MIBI) measured racial identity and the Beck Depression Inventory (BDI) and Beck Suicide Scale (BSS) measured depression and suicide respectively. Results showed significant moderations for the total SBW score and the affect regulation subscale. Additionally, racial identity was positively associated with cultural coping, and cultural coping was negatively associated with traditional coping. Depression was positively related to the SBW and suicide. The three factor model was also upheld. The results of this study support the notion that strength for African American women can have detrimental psychological effects on women utilizing this coping style.
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Šalna, Remigijus. "Influence of steel fibers on punching shear strength of beamless reinforced concrete slabs." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2008. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2008~D_20081119_134617-00531.
Повний текст джерелаАнотація:
The dissertation examines the influence of steel fibers on the punching shear strength of reinforced concrete slabs. The analysis of punching shear models and strength-deformation models of composite materials was used for research. Also, punching shear experimental tests of real dimensions were made. The aim of dissertation is to propose the punching shear strength model, estimating type, strength, different anchoring and geometrical characteristics of steel fibers, as well as plastic strains of steel fiber reinforced concrete. To implement the aim of the paper, the following tasks were solved: stress and strain state of existing punching shear strength models were analyzed, strength-deformation models of composite materials were explored, experiments to confirm the suggested model were conducted.
The dissertation consists of six chapters including the final chapter of conclusions.
First chapter is dedicated to the introduction of the problem and its topicality. Also, purposes and tasks of the paper are formulated, the methods employed and the novelty of solutions is described, the author‘s publications and dissertation structure is presented.
Second chapter covers the analysis of existing punching shear strength methods and models. The aim and tasks of the work are formulated in the end of the chapter.
The third chapter describes theoretical investigation of steel fiber reinforced concrete strength-deformation characteristics. Based on the accomplished analysis, theoretical... [to full text]Disertacijoje nagrinėjama dispersinio armavimo įtaka gelžbetoninių besijinių perdangos plokščių praspaudimo stipriui. Tyrimams buvo naudota literatūroje pateikiamų praspaudimo bei kompozitinių medžiagų stiprio bei deformacijų skaičiavimo modelių analizė. Taip pat atlikti realių matmenų eksperimentiniai plokščių praspaudimo tyrimai. Disertacijos darbo tikslas – pasiūlyti praspaudimo stiprio skaičiavimo modelį, leidžiantį įvertinti dispersinės armatūros tipą, jos stiprį, skirtingas inkaravimosi ir geometrines savybes bei dispersiškai armuotame betone pasireiškiančias plastines deformacijas. Siekiant šio tikslo buvo sprendžiami tokie uždaviniai: atlikta praspaudimo skaičiavimo metodų bei esamų praspaudimo modelių įtempių ir deformacijų būvio analizė, dispersiškai armuoto betono stiprio bei deformacijų esamų modelių ir metodų analizė, atlikti eksperimentiniai tyrimai modeliui patikrinti. Disertaciją sudaro šeši skyriai. Paskutinysis iš jų – rezultatų apibendrinimas. Pirmajame (įvadiniame) skyriuje nagrinėjamas problemos aktualumas, formuluojamas darbo tikslas ir uždaviniai, aprašomas mokslinis darbo naujumas, pristatomi autoriaus pranešimai bei publikacijos, disertacijos struktūra. Antrasis skyrius skirtas praspaudimo skaičiavimo metodų ir modelių analizei. Jo pabaigoje formuluojami disertacijos uždaviniai. Trečiajame skyriuje teoriškai nagrinėjamos dispersiškai armuoto betono stiprio ir deformacinės savybės. Atliktus analizę pasiūlytas dispersiškai armuoto betono stiprio ir... [toliau žr. visą tekstą]
44
Stephensen, David. "Influence of muscle morphology on muscle strength and gait in children with haemophilia." Thesis, University of East London, 2010. http://roar.uel.ac.uk/2630/.
Повний текст джерелаАнотація:
Improvements in medical treatment mean that although joint haemorrhages still occur and radiological signs of joint damage continue to be found in young boys with haemophilia, they present with no apparent clinical signs of joint damage. Evaluating muscle strength with an isokinetic device, muscle morphology with ultrasound imaging and gait patterns with 3-D motion capture, the primary aim of this study was to investigate whether muscle strength, morphology and gait characteristics of children with haemophilia differed from those of typically developing children. No joint or muscle impairment was detected with the Colorado Physical Examination in twenty-six boys with haemophilia, aged 6-12 years and a history of ankle joint haemarthrosis. But compared to a group of twenty-six age and size-matched typically developing boys, those with haemophilia showed deficits in isokinetic muscle strength of the knee extensors, ankle dorsi and plantarflexors (p<0.05), together with reduced size of vastus lateralis and lateral gastrocnemius muscles (p<0.05). Adaptations in walking were also found (p<0.05); greater knee flexion and ankle dorsiflexion angles, vertical ground reaction forces, knee flexion moments, ankle external rotation moments and EMG activity of lateral gastrocnemius. Regression analysis identified key relationships linking reduced lower limb muscle strength, altered muscle morphology and biomechamcal adaptations of walking patterns in boys with haemophilia (p<0.05). Implications from this study suggest that lower limb joint and muscle function in young boys with haemophilia and a history of ankle joint bleeding differed from that of their typically developing peers and were more impaired than current clinical evaluations imply.
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Johns, Eyioma Izuwah. "Influence of weldiing modes to strength and residual of low carbon steel joints." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2014. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2014~D_20140617_122036-53782.
Повний текст джерелаАнотація:
In this study, microstructural, micro hardness evaluation and residual stress distribution, of low carbon steel after single pass gas metal arc welding technique (GMAW) were investigated. The goal of this investigation were to reveal the microstructures, micro hardness, residual stress distribution and tensile strength of welded joints by using welding current as varying parameter. In order to realize this objective, welded plate of low carbon steel with thickness of 2.5mm and 250mm long by 200mm wide were welded together with different welding current of 70A, 100A through MIG process. Four different parts of samples were tried. The first part of samples was annealed in a furnace to a temperature of 750 and allowed to cool in air before welding. While the second was not heated, third and fourth trials were heated to a temperature of 200˚C and 580˚C respectively after the welding and allowed cooling in air. Nikon optic microscope and CSM micro hardness testing instrument were used to determine the microstructure of the weld bead and HAZ of the samples, and hardness tests were carried out at different zones of welded joint.
Micro hardness behavior was observed by using CSM instrument using 20N load for indentation, which reveals the correlation between hardness, elasticity and plasticity on the heat affected zone (HAZ) and weld bead of the welded plates. The samples were subjected to tensile strength and the distribution of residual stress of the weld. Tensile strength test... [to full text]Šiame darbe aprašomi mikrostruktūros, mikrokietumo nustatymo bei liekamųjų įtempimų pasiskirstymo tyrimai mažo anglingumo plienuose po lankinio suvirinimo. Tyrimo tiksla - nustatyti suvirintos jungties mikrostuktūros ir mikrokietųmo priklausomybę nuo suvirinimo srovės, kaip kintamo dydžio. Remiantis užduotimi buvo suvirintos 2.5 mm storio, 250 mm ilgio ir 200 mm pločio mažaanglio plieno plokštės, naudojant skirting dydžio (70A ir 100A) suvirininant apsauginių dujų aplinkoje (MIG) srovę. Buvo paruoštos keturios partijos bandinių. Pirmoji partija, proies suvirinant, buvo atkaitinta 750°C temperatųroje, ir ataušintas ore. Tuo tarpu antroji partija nebuvo apdorojama, o trečioji ir ketvirtoji atleista 200 C° ir 580°C temperatūroje ir atvėsinta ore. Suvirinimo vonelės ir erminio poveikio zonos mikrostruktūrai tirti bei mikrokietumui nustatyti buvo naudotas Nicon optinis mikroskopas bei CSM mikrokietumo bandymų įrenginys. Matuojant CSM įrenginiu, 20N įspaudimo apkrova, buvo pastebėtas įdomus kietuvo būvis, kuris atskleidė ryšį tarp kietumo, elastingumo ir plastiškumo esantį suvirintų plokštelių terminio poveikio zonoje bei suvirinimo vonelėje. Buvo matuojamas suvirintų bandinių stiprumas tempiant ir liekamųjų įtempimų pasiskirstymas. Tempimo stiprumo bandymų duomenys parodė ducharakteringus suirimo atvejus – plastiio-elastinio bei trapaus tipo. Liekamųjų įtempimų bandymų rezultati neparodė rėikšmingos liekamųjų įtempimų įtakos pasirinktomis sąlygomis suvirintuose bandiniuose.
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MACHADO, RENATO REIS. "INFLUENCE OF MICRO-WELD DOTS ON THE FATIGUE STRENGTH OF LOW CARBON STEELS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1997. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=24816@1.
Повний текст джерелаАнотація:
As dificuldades para a instalação e proteção de Extensômetros de Resistência Elétrica (EREs) em ambientes inóspitos pelos processos normais de colagem, limitam bastante o uso. A utilização de extensômetros soldáveis (ESs) pode reduzir sensivelmente os problemas de instalação e proteção, oferecendo uma ampliação na faixa de utilização e abaixando seu custo.
Os ESs são instalados nos componentes estruturais metálicos a partir de micro-pontos de soldas, gerados por instrumentos soldadores que trabalham através de descargas capacitivas.
Estes micro-pontos geram dois efeitos. Um deles afeta a distribuição das macro tensões atuantes na região. O outro efeito está relacionado com a mudança na estrutura do material, nas suas propriedades mecânicas, e tem implicações na geometria da superfície.
No presente trabalho, procurou-se estudar a influência da instalação de EREs soldáveis na resistência à fadiga de aços de baixo carbono, através da soldagem de pequenas chapas finas de aço inoxidável com espessura de 0,1 mm em espécimes de aço-carbono. Os espécimes utilizados foram retirados de chapas de aço estrutural, utilizados em plataformas marítimas (ASTM A-36 e o USIMINAS SAR-60).
Os testes de fadiga feitos em uma máquina de flexão rotativa UBM e em um máquina INSTRON 8501 servo-hidráulica, em tração-tração, ambos em controle de carga.
A partir dos resultados obtidos, das análises efetuadas e considerando espécimes com bases de medidas longas, ensaiados sob flexão rotativa e tração-tração, pôde-se concluir que estes micro-pontos de solda não influenciaram de maneira significativa a resistência à fadiga dos materiais testados.
A ausência de influência destes micro-pontos na resistência à fadiga foi também detectada a partir de avaliações feitas nas regiões de fratura dos corpos de prova, onde a grande maioria aconteceu nas regiões próximas aos ombros dos espécimes. Isto pode ter acontecido devido a: defeitos de usinagem na região do ombro, formação de tensões residuais compreensivas ao redor dos micro-pontos de solda e fortalecimento da região dos micro-pontos pela transformação microestrutural de ferrita em ferrita com carboneto em estrutura acicular.Bonding and protecting electric resistance gauges (ERSG) through the normal bonding procedures, is a difficult exercise in aggressive atmosphere. The use of welded strain gages (WSG) may significantly reduce the installation and protection problems. This welding technique permits the installation of a larger number of strain gages within a given period, and reduces operating costs. The WSG are affixed to metallic structural components using a micro-spotting technique, generated by a capacitive discharge equipment. Two effects are observed as a consequence of the micro-spots. The first is related to the distribution of the macroscopic stresses acting in the vicinity of the spots. The second is related to the alteration of the material microstructure and changes in mechanical properties and the surface geometry. In the present work, the influence of the WSG bondage on the fatigue strength of low carbon steels is studied. The bondage was simulated by micro-welding small stainless steel strips, 0,1 mm thick, along the gage length of the low carbon fatigue test piece. The specimens were machined out of structural steel sheets, used on off-shore platforms (grades: ASTM A -36 and USIMINAS SAR-60). Fatigue testing was performed under load control. Two equipments were used: a rotational-bending UBM machine, and an INSTRON 8501 of servhydraulic control. The results show that, considering long-dimension specimens, tested under rotational-bending and axial repeated (tensile)loading, the micro-spots have no significant effect on the material fatigue strength. The insignificant effect of the micro-spots was also confirmed through observations of the fracture surface. Most of the cracks initiated near the end of the gage length. This result may be attributed to: localization of machining surface defects around the shoulder region, generation of compressive residual stresses in the vicinity of the micro-spots, and strengthening of the microstructure around the spots due to a localized transformation of ferrite to acicular ferrite with carbide.
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ZHEMCHUZHNIKOV, ALEXANDER. "INFLUENCE OF CLAY CONTENT AND SUCTION ON THE STRENGTH OF COMPRESSED EARTH BLOCKS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2015. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=27018@1.
Повний текст джерелаАнотація:
PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
PROGRAMA DE EXCELENCIA ACADEMICA
Solo é um material de construção sustentável que tem sido utilizado por milhares de anos. As normas técnicas e recomendações existentes referente à construção de terra são baseadas em número limitado de estudos e dependem de materiais, condições climáticas e tradições locais. A compreensão dos parâmetros que influenciam o comportamento do solo compactado quando o mesmo utilizado em paredes e colunaas é essencial para a interpretação dos dados experimentais. Diversos estudos recentes analizaram taipa de pilão do ponto de vista da mecanica de solos nçao saturados, observando o decrescimo da resistência com a diminuição da sucção, causada por exemplo pelo aumento da humidade do ar. Porém, não hã uma pesquisa semelhante pertinente aos blocos de solo compactado. O objetivo do presente trabalho foi verificar a influência do teor de argila, dencidade e sucção na resistência dos blocos de solo compactado. Foram utiliazdas quatro dosagens de solo artificial que consistiu de areia, pó de quartzo e argila caulitinitca. Para cada dosagem, amostras estaticamente compactadas na umidade ótima e no ramo seco foram ensaiadas variando-se a sucção. Ao contrário dos resultados encontrados comunmente na literatura, a resistência das amostras diminuiu com o aumento da sucção, enquanto a influência das condições climáticas como umidade e temperatura foram mínimas. As conclusões feitas no presente trabalho podem ser utilizadas nos projetos de construção sustentável com emprego de blocos de solo compactado.
Soil is a sustainable construction material that has been used traditionally for thousands of years. In general, earth construction specifications are based on common knowledge. Existing recommendations tend to be supported by a limited number of studies and depend on local materials, climatic conditions and historical background. The lack of understanding of compacted soil behavior, in particularly its strength, may have prevented a wider application of earthen construction materials in housing. Understanding of the soil properties and parameters that influence its performance when used in walls and columns is essential for interpretation of experimental data. Recently a number of studies have analyzed rammed earth considering unsaturated soil mechanics, which suggest loss of strength following decrease in suction values, for example provoked by the increase in relative humidity. However, there is a lack of such research pertaining to compressed earth blocks (CEBs). The objective of this study was to verify the influence of clay content, density and suction on the strength of CEBs. Four soil mixes consisting of sand, quartz powder and kaolinitic clay were used. For each soil mix statically compacted samples with densities corresponding to optimum and dry of optimum moisture contents were tested for a range of suctions. Unlike reported in the literature, the results showed loss of strength following increase in suction values, while only small variations were registered for suctions corresponding to a wide range of RH and temperature conditions. The findings can be of use for specifications relating to construction of sustainable housing using CEBs.
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Shaw, I., BS Shaw, and GA Brown. "Influence of strength training on cardiac risk prevention in individuals without cardiovascular disease." African Journal for Physical, Health Education, Recreation and Dance, 2009. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1001650.
Повний текст джерелаАнотація:
Abstract
It has widely been shown that exercise, particularly aerobic exercise, has extensive cardioprotective
benefits and is an important tool in the prevention of coronary heart disease (CHD). The present
investigation aimed to determine the multivariate impact of strength training, designed to prevent the
development of CHD, on the Framingham Risk Assessment (FRA) score. Twenty-eight healthy
untrained men with low CHD risk (mean age 28 years and 7 months) participated in an eight-week (3-
d/wk) strength training programme. Self-administered smoking records, resting blood pressures, total
cholesterol (TC), high-density lipoprotein cholesterol (HDLC), FRA scores and absolute 10-year risks
for CHD were determined at the pre-test and post-test. After the eight-week period, no significant (p >
0.05) differences were found in number of cigarettes smoked daily, systolic blood pressure, TC, HDLC,
FRA scores and absolute 10-year risks for CHD in both the strength-trained (n = 13) and non-exercising
control (n = 15) groups. The data indicate that strength training did not reduce the risk of developing
CHD and absolute 10-year risk for CHD as assessed by the FRA score.
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Kay, Sean. "Concrete surface coatings and the influence of substrate moisture condition on bond strength." Master's thesis, University of Cape Town, 2016. http://hdl.handle.net/11427/20924.
Повний текст джерелаАнотація:
Concrete structures, in particular reinforced concrete structures, have been designed and built for many years. Many previously built structures are now being compromised with regard to their condition and structural integrity. There has developed a need to maintain these structures and protect them in order to protect the users and minimise the expenses associated with repair and maintenance. Instead of resorting to demolishing and rebuilding, engineers are becoming increasingly capable of restoring and enhancing existing structures in order to maximise the original structures lifespan. One of the ways in which this is achieved is through the implementation of various repair and maintenance strategies. These strategies can range from cathodic protection of the steel reinforcement to increasing concrete cover of the section. The easiest and often most commonly used method, although often not effective when used on its own, is to coat the concrete surface with a decorative or protective coating. There are many coatings available, ranging from simple to complex formulations of inorganic and/or organic materials. These coatings each perform a unique function and will often be designed to combat a specific problem which the structure is exposed to. The formulation of the coatings are almost always designed correctly when they are manufactured, however, premature bond failure due to poor substrate surface preparation and various substrate moisture conditions still seem to occur after coating application. This investigation will give insight into the effects a sound, clean and profiled concrete substrate that is subjected to different moisture conditions will have on the bond strength achieved when using cementitious based coatings. The reason for differing the moisture conditions of the substrate is that often on site the moisture condition of an existing substrate is not known prior to application of the coating. Through this investigation, epoxy modified cementitious coatings have been shown to provide an acceptable bond strength. In some cases, failure within the coating instead of the acceptable failure within the substrate has resulted, due only to the level of dryness of the substrate. A thorough investigation on the theory behind surface coatings, their properties and performance requirements was done and subsequently followed by a detailed experimental programme that was performed and analysed to provide insight to the said coating behaviour.
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Voortman, Landström Eric Johan Klas. "Influence of liquid shim on the bearing strength of a composite bolted joint." Thesis, KTH, Hållfasthetslära (Avd.), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-258826.
Повний текст джерелаАнотація:
The objective of this thesis has been to investigate the effect a liquid shim has on the bearing strength of a composite bolted joint. The shim is necessary to close gaps that occur during the assembly of the joints, preventing the structural parts from being fastened correctly. The shim however increases the load eccentricity of the joint and will have a negative effect on the joint strength, but the significance of this weakening is not well understood.This thesis primarily focuses on a parametric finite element study on the effect the liquid shim has on the bearing of both a homogenised carbon fibre/epoxy model and a fully detailed laminate model based upon the same material. Parameters studied were the plate and shim thicknesses, lateral support, number of fasteners, bolt pre-tension and bolt diameter and the relative strength decreases were documented.A literature study was also conducted to consider previous results concering the strength change due to the inclusion of a shim. It was found that the results show a large spread dependent on material system, geometry and assumptions regarding numerical behaviour. The finite element simulation was compared with the results from these studies, showing fairly good agreement.The analysis conducted has shown that there is a major increase in stress and strain on the bearing surface because of the shim. Moreover, it is shown that this strength reduction is dependent on both model and parameters studied, which necessitates experimental testing in order to verify which is the more applicable for future methodology.