This thesis presents the results of an investigation of factors which influence the geotechnical properties of frozen mine backfill (FMB). FMB has extensive application potential for mining in permafrost areas. The uniaxial compressive strength (UCS) of hardened backfill is often used to evaluate mine backfill stability. However, the deformation behaviour and stiffness of the FMB are also key design properties of interest. In this thesis, uniaxial compressive tests were conducted on FTB and FCPB samples. Information about the geotechnical properties of FMB is obtained. The effects of FMB mix components and vertical compression pressure on the geotechnical properties of FMB are discussed and summarized. An optimum total water content of 25%-35% is found in which the strength and the modulus of elasticity of the FTB are 1.4-3.2 MPa and 35-58 MPa, respectively. It is observed that a small amount (3-6%) of cement can significantly change the geotechnical properties of FTB.

This report describes the growth and characterization of thin amorphous samarium-cobalt alloy films. The samarium-cobalt alloy was grown by DC magnetron sputtering in the presence of an external magnetic field parallel to the thin film. The external magnetic field induces a uniaxial in-plane magnetic anisotropy in the samarium-cobalt alloy. The thin films were characterized with x-ray scattering, and the magnetic anisotropy was characterized with the magneto optic Kerr effect. The measurements showed a uniaxial in-plane magnetic anisotropy in the samarium-cobalt alloy films. It is not clear how amorphous the samples really are, but there are indications of crystalline and amorphous areas in the alloys.

This work investigates the effects of post-fabrication applied mechanical tensile strain on Silicon (Si) Bipolar Junction Transistor (BJT) and Silicon-Germanium (SiGe) Heterojunction Bipolar Transistor (HBT) devices. Applied strain effects on MOSFET transistors are being heavily explored, both in academia and industry, as a possible alternative to dimensional scaling. This thesis focuses on how strain affects Si BJT and SiGe HBTs, where tensile strain is applied after the Integrated Circuit (IC) fabrication has been completed, using a unique mechanical method. The consequence of both biaxial and uniaxial strain application has been examined in this work. Chapter I gives a short introduction to the scope of this work, the motivation for conducting this research and the contributions of this experiment. Chapter II entails a brief discussion on Si bipolar and SiGe heterojunction bipolar device physics, which are key to the understanding of strain induced effects. Chapter III provides a thorough summary of the current state of research regarding applied strain, also known as Strain Engineering. It covers different types, orientations, and application techniques of strain. Chapter IV, highlights the details of this experiment, and also presents the measured results. It is observed that for this particular method of biaxial tensile strain application, the collector current (IC) and current gain degrades for both Si BJT and SiGe HBT. Base current (IB) decreases in Si BJT, though it increases for SiGe HBT after strain. Little or no change is noticed in the dynamic or ac small-signal characteristics like unity-gain cutoff frequency (fT) and base resistance (rBB) after strain. Uniaxially strained SiGe HBT samples showed similar results as the biaxial strain. This chapter also attempts to explain the origin of these strain induced changes. Chapter V, summarizes the finding of this experiment, and concludes the thesis with some future directions for this research.

Metal-oxide-semiconductor field-effect transistors (MOSFETs) are major devices inintegrated circuit, extensively used in various electronic products. In order to improve the electrical characteristics, scaling channel width and length, using high-£e gate dielectric insulator, and strained silicon may be utilized to increase the driving current and circuit speed. Nevertheless, the scaling of the channel width and length must overcome the limitation of the photolithographytechnology and cost. Once the method is employed, the MOSFETs will face a serious short-channel effect and gate leakage current. In the aspect of high-£e gate dielectric insulator, there still have problems, containing the trap states, phonon scattering, dipole-induced threshold voltage variation, needed to be solved. This dissertation focuses on the properties of MOSFETs experienced an external-mechanical strain, where the channel will be strained. Hence, the mobility, driving current, and circuit speed will increase. Our research can be divided into three topics: fabricating process-induced strained Si, external mechanical stress-induced strained Si, and the properties of strained Si MOSFETs at different temperatures. Except the electrical measurement, we also used the ISE-TCAD to simulate the electrical characteristic of MOSFETs under stress. Firstly, we apply the stress on n-MOSFETs by utilizing the nitride-capping layer. Once the lattice is strained, the mobility will increase, hence resulting in the operating speed. Secondly, the electrical characteristics under external stress is explored by introduced the external mechanical stress along the channel length of nMOSFETs. In addition to the fabricating process-induced strain, the fabricating process condition will also influence the device characteristics. As a result, we propose a new strain technology for our following research. Thirdly, the device performance of strained Si under different temperatures is investigated. Finally, we discuss the gate leakage current in strained Si depending on the ultra-thin gate oxide layer.

This thesis presents the results of an investigation of factors which influence the geotechnical properties of frozen mine backfill (FMB). FMB has extensive application potential for mining in permafrost areas. The uniaxial compressive strength (UCS) of hardened backfill is often used to evaluate mine backfill stability. However, the deformation behaviour and stiffness of the FMB are also key design properties of interest. In this thesis, uniaxial compressive tests were conducted on FTB and FCPB samples. Information about the geotechnical properties of FMB is obtained. The effects of FMB mix components and vertical compression pressure on the geotechnical properties of FMB are discussed and summarized. An optimum total water content of 25%-35% is found in which the strength and the modulus of elasticity of the FTB are 1.4-3.2 MPa and 35-58 MPa, respectively. It is observed that a small amount (3-6%) of cement can significantly change the geotechnical properties of FTB.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-05-10T20:12:53Z No. of bitstreams: 1 LarissaBezerraDaSilva_DISSERT.pdf: 3671939 bytes, checksum: 0ded2fa22f6e277a6bf0acd3e16b0455 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-05-12T00:26:21Z (GMT) No. of bitstreams: 1 LarissaBezerraDaSilva_DISSERT.pdf: 3671939 bytes, checksum: 0ded2fa22f6e277a6bf0acd3e16b0455 (MD5) / Made available in DSpace on 2016-05-12T00:26:21Z (GMT). No. of bitstreams: 1 LarissaBezerraDaSilva_DISSERT.pdf: 3671939 bytes, checksum: 0ded2fa22f6e277a6bf0acd3e16b0455 (MD5) Previous issue date: 2014-08-22 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / A efetiva utiliza??o dos recursos naturais diante o acelerado crescimento econ?mico resulta no aumento cont?nuo de res?duos industriais, e para suprimir estes res?duos, um processo de reciclagem ? de prefer?ncia uma solu??o atraente. Durante a usinagem dos blocos de zirc?nia para diversos tipos de implantes odontol?gicos, grande parte do material ? desprendida na forma de p?, que posteriormente ? descartado. A zirc?nia tetragonal estabilizada com 3% em mol de ?tria (Y-TZP) possui uma variedade de aplica??es na ?rea de engenharia e biom?dica devido ? sua ?tima combina??o de resist?ncia, tenacidade ? fratura, condutividade i?nica e baixa condutividade t?rmica. Al?m do dano para o meio ambiente, o desperd?cio deste material resulta em preju?zo financeiro, refletindo em elevado custo final no tratamento para os pacientes. Os materiais de partida utilizados neste trabalho foram dois diferentes p?s do sistema cer?mico ZrO3-Y2O3: zirc?nia comercial nanoparticulada e res?duo de zirc?nia microparticulado. Os p?s foram conformados por prensagem uniaxial e isost?tica e em seguida sinterizadas a 1500, 1550 e 1600 ?C, durante 1 hora. As t?cnicas de granulometria a laser, difra??o de raios X (DRX), e dilatometria foram utilizadas para caracteriza??o do p?. Ap?s sinterizados, foram realizados ensaios de densidade e porosidade, difra??o de raios X (DRX), resist?ncia mec?nica ? flex?o, microdureza Vickers e an?lise de tenacidade ? fratura, e microscopia eletr?nica de varredura (MEV). As amostras compactadas via prensagem isost?tica apresentaram valores de porosidade inferiores a 0,78% e demostraram maior efetividade de compacta??o comparada ? via uniaxial. Foi observado nos difratogramas de raios X, com o aumento da temperatura, a intensidade dos picos da fase monocl?nica diminuiu. A temperatura de sinteriza??o influenciou de forma moderada a microdureza das amostras, demostrando pequenos acr?scimos da dureza at? a temperatura de 1600?C. A resist?ncia ? flex?o do res?duo de zirc?nia aumenta com o aumento da temperatura de sinteriza??o, para ambas as vias de compacta??o, apresentando melhores valores por via isost?tica. / The actual use of natural resources on accelerated economic growth, resulting in continuous increase of industrial waste, and to remove these residues, a recycling process is preferably na attractive solution. During the machining of blocks of zirconia to several types of dental implants, most of the material is loosened as a powder, which is subsequently discarded. The stabilized tetragonal zirconia with 3% yttria (Y-TZP) mol boasts a variety of applications in engineering, and biomedical, because of its great combination of strength, fracture toughness, ionic conductivity and low thermal conductivity. Besides the damage to the environment wasting of the material resulting in financial loss, reflecting the high final cost of medical treatment for patients. The starting materials used in this work were two different powders ZrO3-Y2O3ceramic system: commercial zirconia nanoparticulate and microparticulate zirc?nia residue. The powder was uniaxially and isostatically pressed and then sintered at 1500, 1550 and 1600 ? C for 1 hour. The techniques of laser granulometry, X-ray diffraction (XRD) and dilatometry were used for powder characterization. After sintering were performed density and porosity tests, X-ray diffraction (XRD), Flexural strength, microhardness and fracture toughness analysis, and scanning electron microscopy (SEM). Samples compacted via isostatic pressing showed values less than 0.78% porosity and demonstrated greater effectiveness compared to uniaxial compression. Was observed in X-ray diffra ction, that with increasing temperature, the intensity of the peaks of monoclinic phase is decreased. The sintering temperature moderately has influenced on the microhardness of samples, showing small increases in hardness to temperature of 1600 ? C. The flexural strength of zirconia residue increases with increasing sintering temperature for both routes of compression, showing the best values for isostatic compression.

The primary aim of this research was to develop a method for determining the true uniaxial tensile strength of concrete by conducting a series of cylinder splitting, modulus of rupture (MOR) and cylinder/cube compression tests. The main objectives were: • Critically reviewing previous published research in order to identify gaps in current knowledge and understanding, including theoretical and methodological contributions to the true uniaxial tensile strength of concrete. In order to maintain consistency and increase the reliability of the proposed methods, it is essential to review the literature to provide additional data points in order to add additional depth, breathe and rigor to Senussi's investigation (2004). • The design of self compacting concrete (SCC), normal strength concrete (NSC) and high strength concrete (HSC) mixes and undertaking lab-based experimental works for mixing, casting, curing and testing of specimens in order to establish new empirical evidence and data. • Analysing the data, presenting the results, and investigating the application of validity methods as stated by Lin and Raoof (1999) and Senussi (2004). • To draw conclusions including comparison with previous research and literature, including the proposal of new correction factors and recommendations for future research. 29 batches of NSC, 137 batches of HSC, 44 batches of fly ash SCC and 47 batches of GGBS SCC were cast and their hardened and fresh properties were measured. Hardened properties measured included: cylinder splitting strength, MOR, cylinder compressive strength and cube compressive strength. A variety of rheological tests were also applied to characterise the fresh properties of the SCC mixes, including: slump flow, T50, L-box, V-funnel, J-ring and sieve stability. Cylinders were also visually checked after splitting for segregation. The tensile strength of concrete has traditionally been expressed in terms of its compressive strength (e.g. ft = c x c f ). Based on this premise, extensive laboratory testing was conducted to evaluate the tensile strength of the concretes, including the direct tension test and the indirect cylinder splitting and MOR tests. These tests however, do not provide sufficiently accurate results for the true uniaxial tensile strength, due to the results being based upon different test methods. This shortcoming has been overcome by recently developed methods reported by Lin and Raoof (1999) and Senussi (2004) who proposed simple correction factors for the application to the cylinder splitting and MOR test results, with the final outcome providing practically reasonable estimates of the true uniaxial tensile strength of concrete, covering a wide range of concrete compressive strengths 12.57 ≤ fc ≤ 93.82 MPa, as well as a wide range of aggregate types. The current investigation has covered a wide range of ages at testing, from 3 to 91 days. Test data from other sources has also been applied for ages up to 365 days, with the test results reported relating to a variety of mix designs. NSC, SCC and HSC data from the current investigation has shown an encouraging correlation with the previously reported results, hence providing additional wider and deeper empirical evidence for the validity of the recommended correction factors. The results have also demonstrated that the type (size, texture and strength) of aggregate has a negligible effect on the recommended correction factors. The concrete age at testing was demonstrated to have a potentially significant effect on the recommended correction factors. Altering the cement type can also have a significant effect on the hardened properties measured and demonstrated practically noticeable variations on the recommended correction factors. The correction factors proved to be valid regarding the effects of incorporating various blended cements in the HSC and SCC. The NSC, HSC and SCC showed an encouraging correlation with previously reported results, providing additional support, depth, breadth and rigor for the validity of the correction factors recommended.

This master’s thesis deals with production of ferrite cores by the powder metallurgy technology in EPCOS s.r.o. Šumperk. Special importance is given to powder compaction process through uniaxial cold pressing in a rigid die. The production company is introduced in the first part and is followed by a study of pressure propagation in a powder bed during uniaxial pressing, then the analysis of critical phases of compaction process in terms of green cracks and compact’s defects follows. Main test methods of compact’s green strength are also presented. Significant part of the master’s thesis deals with an analysis of a powder technological properties’ testing method. For that purpose, an instrumented compaction device called Powder Testing Center (PTC, KZK Powder Tech Corp.) is used. A new pressing tool of smaller diameter was made and mounted to the experimental press; also the testing technique, procedure and certificate of powder’s properties was slightly changed. Technological property called advanced compactibility of powder is introduced. Decision about suitability of powder for uniaxial pressing process is made upon the value of newly introduced coefficient of advanced compactibility . Compact’s green strength is evaluated by a proposed contract bend test method, which uses cylindrical-shaped testing pieces with high height-to-diameter ratio. The results from both testing methods show the impact of additional granulate adjustment on green strength and heterogeneity of density distribution along axial direction. Implementation of gained knowledge to production process led to more than 40 % cost savings in term 2/2016 – 4/2016 in comparison with term 8/2015 – 11/2015, because of lowering the number of scrap parts from KLY material due to crack reduction.

No description available.

This thesis presents the results of an investigation of factors which influence the geotechnical properties of frozen mine backfill (FMB). FMB has extensive application potential for mining in permafrost areas. The uniaxial compressive strength (UCS) of hardened backfill is often used to evaluate mine backfill stability. However, the deformation behaviour and stiffness of the FMB are also key design properties of interest. In this thesis, uniaxial compressive tests were conducted on FTB and FCPB samples. Information about the geotechnical properties of FMB is obtained. The effects of FMB mix components and vertical compression pressure on the geotechnical properties of FMB are discussed and summarized. An optimum total water content of 25%-35% is found in which the strength and the modulus of elasticity of the FTB are 1.4-3.2 MPa and 35-58 MPa, respectively. It is observed that a small amount (3-6%) of cement can significantly change the geotechnical properties of FTB.