The Diploma thesis is focused on reballing of BGA packages with the device PACE TF 2700. It describes the general types of BGA packages, their defects, importance of thermal management to the solder techniques, where it is also talked about the meaning of solders and fluxes for the joint. The work informs about the most common methods of reballing, the proper handling of components and the current situation with BGA stencils on the market. It briefly describes the device operation of PACE TF 2700, that is working on the convection and IR principle of heating components. It deals with the manufacturing of the template, dummy BGA packages, the test plates, creation of the thermo profile, comparing and examining the defects and their causes, which had the most significant impact on the results. The achievements would serve for comparing them with the results of the future laboratory exercises or as a subject for further works.

Magister Chirurgiae Dentium (MChD) / Occupational hazards are common among many professions and dentistry is no exception. Occupational hazards include percutaneous injuries, inhalation of noxious chemicals, noise and musculoskeletal disorders (MSD). Despite the fact that MSD have been documented to be very prevalent among dentists in various countries, there is a paucity of literature from South Africa. Aim The aim of the present study was to determine the prevalence of musculoskeletal disorders among the dentists in KwaZulu-Natal (KZN), South Africa and to identify risk factors associated with it. The study was a cross-sectional, descriptive one and questionnaires were used to elicit information regarding socio-demographic details, medical history, work history and work-related posture information from dentists based in KwaZulu-Natal. A convenience sample of all qualified dentists in this region who were registered members of the South African Dental Association (SADA) was used. Results One hundred and nine dentists responded to the questionnaire. The response rate was 31%. The majority were male; a third aged between 30 - 39 years and the ratio of females to males was 1:3. Almost all the dentists reported pain in the neck, lower back and shoulder. Less than a quarter of the dentists in KZN reported hand pain, numbness in the hands and a tingling sensation in the hands. More than three quarters reported that they had no negative effects when performing restorative work and scaling and polishing, but 3.1% reported having extreme levels of pain. The most common working position reported was the 2 0' clock position. Nearly three quarters rotated their necks while performing clinical dentistry and a third tilted their shoulders towards their dominant hand. There was no relationship between Body Mass Index (BMI) and whether respondents treated patients while seated or standing and neither was there a relationship between pain in the lower back and BMI. There was a strong association between pain in the neck while performing clinical work and the number of years in practice confounded by age. When compared to other countries the prevalence of MSD is very high. The highest occurrence was for neck, back and shoulder pain. Avoiding these injuries is critical and self-recognition is important in either preventing further injuries or in increasing severity of the condition. The findings of this study suggests that it may be valuable to include ergonomic work practice in the training of dentists and dentists should be involved in a proper exercise routine which should include stretching and weight training to prevent injuries. Regular breaks should be taken to perform stretching exercises in-between the management of patients in order to reduce the risk of MSD.

The methods of MSD are applied to the design of functionally graded materials. Analysis models are presented to allow the design of compliant derailleur for a case study and constraints are placed on the design. Several methods are presented for relating elements of the microstructure to the properties of the material, including Taylor yield theory, Hill elastic bounds, and precipitation hardening. Applying n-point statistics to the MSD framework is also discussed. Some results are presented for the information content of the 2-point correlation statistics that follow from the methods used to integrate functionally graded materials into MSD. For the compliant beam case study, the best design (98%Al-2%Li) was a 97% improvement over the worst (100%Al). The improvements were primarily due to the precipitation hardening, although anisotropy also significantly impacted the design. Under the constraints for the design, allowing the beam to be functionally graded had little effect on the overall design, unless there was significant stiffening occurring along with particulate formation.

No description available.

Submitted by Kelson Anthony de Menezes (kelson@ucb.br) on 2016-10-28T18:48:01Z No. of bitstreams: 1 JeffersonJoseCeruttiGauerDissertacao2016.pdf: 1448138 bytes, checksum: 7c0985d46840a27fe872a0de79761029 (MD5) / Made available in DSpace on 2016-10-28T18:48:01Z (GMT). No. of bitstreams: 1 JeffersonJoseCeruttiGauerDissertacao2016.pdf: 1448138 bytes, checksum: 7c0985d46840a27fe872a0de79761029 (MD5) Previous issue date: 2016-03-10 / Similarities of products and services, market stagnation, the portability of operations among institutions, competition and competitiveness in banking sector have motivated more attention to customer loyalty. It is essential to win new clients as well as to retain them in order to avoid churn. So management tools that concern relations with customers require an increasing amount of variables. Present study covers the best clients in a big-size Brazilian financial institution. It proposes a model for churn predicting, based on the evolution of their loans and investments. Operations from ca. 291 thousands clients were the input data for software QlikView (a user-oriented Business Intelligence platform). The model transformed the Daily Balance Average into a logarithm scale in order to assess the value oscillation according to periods. The achieved index seems to be a possible churn predictor, which indicates that relations management should regard carefully customers susceptible to churn. Nevertheless this index alone does not explain the churn rate. It is recommended to apply it as a complement and a refinement of other indexes that are already deployed in customer loyalty management. / As semelhan??as de produtos e servi??os, a estagna????o do mercado, a portabilidade de opera????es entre institui????es e a concorr??ncia e competitividade no setor banc??rio t??m motivado mais aten????o ?? fideliza????o do cliente. A considera????o de tais fatores ?? essencial para a conquista de novos clientes, bem como para a sua reten????o, a fim de evitar o churn. Assim, ferramentas de gest??o de relacionamento com o cliente exigem uma quantidade crescente de vari??veis. O presente estudo abrange os melhores clientes de uma institui????o financeira brasileira de grande porte. Prop??e um modelo para a predi????o de churn, com base na evolu????o dos seus empr??stimos e investimentos. Opera????es de 291.761 clientes foram os dados de entrada para a ferramenta QlikView (uma plataforma de BI ??? Business Intelligence ??? orientada ao usu??rio). O modelo transformou a M??dia de Saldos Di??rio (MSD) em uma escala logar??tmica, a fim de avaliar a oscila????o de acordo com os per??odos. O indicador alcan??ado parece ser um poss??vel preditor de churn, o que indica que a gest??o de relacionamento deve considerar cuidadosamente os clientes suscet??veis ?? evas??o. No entanto, s?? este indicador n??o explica a taxa de churn. Recomenda-se aplic??-lo como um complemento e um refinamento de outros indicadores que j?? est??o implantados na gest??o da fideliza????o com o cliente.

We employ the empirical potential function Airebo to computationally model free-standing Carbon-12 graphene in a classical setting. Our objective is to measure the mean square displacement (MSD) of atoms in the system for different average temperatures and Carbon-13 isotope concentrations. From results of the MSD we aim to develop a technique that employs Transmission Electron Microscopy (TEM), using high-angle annular dark filed (HAADF) detection, to obtain atomic-resolution images. From the thermally diffusive images, produced by the vibrations of atoms, we intent to resolve isotopes types in graphene. For this, we establish a relationship between the full width half maximum (FWHM) of real-space intensity images and MSD for temperature and isotope concentration changes. For the case of changes in the temperature of the system, simulation results show a linear relationship between the MSD as a function of increased temperature in the system, with a slope of 7.858×10-6 Å2/K. We also note a power dependency for the MSD in units of [Å2] with respect to the FWHM in units of [Å] given by FWHM(MSD)=0.20MSD0.53+0.67. For the case of increasing isotope concentration, no statistically significant changes to the MSD of 12C and 13C are noted for graphene systems with 2,000 atoms or more. We note that for the experimental replication of results, noticeable differences in the MSD for systems with approximately 320,000 atoms must be observable. For this, we conclude that isotopes in free-standing graphene cannot be distinguished using TEM.

QC 20101220

The Internet of Things (IoT) is an umbrella term for smart things connected to the Internet. Connected sensors may be used to the benefit of smart building management systems. This thesis describes the development of a sensor based building management system prototype, lightweight enough to run on a single network camera. The focus of the research was investigating if the system prototype was scalable, and capable of storing and analyzing data gathered from a large amount of sensors relevant to the field of building management. The prototype was developed through a five-stage systems development process, and evaluated using simulations and case studies. The finished prototype was able to gather and store data from a few hundred real-time sensors using limited hardware. Tests showed that the network camera should be capable of managing at least 100 sensors. The system itself is scalable with the use of more powerful hardware. However, using a distributed architecture would be preferable if more sensors are required. This could be achieved by creating a distributed network of cameras, where each camera manages its own set of sensors. This could both increase scalability and make the system more robust and reliable.

Opportunistic selection algorithms have grown in importance as next generation wireless systems strive towards higher data rates and spectral efficiencies. For example, in orthogonal frequency division multiple access(OFDMA), the system bandwidth is divided into many sub channels. For each sub channel, the user with the highest channel gain is opportunistically assigned to it. .Likewise, in a multi-source, multi-destination (MSD) cooperative relay system, a relay node must be assigned for every source-destination (SD) pair. The assignment decisions are based on local channel knowledge and must be fast so as to maximize the time available for data transmission. We develop novel multiple access based splitting-based selection algorithms for OFDMA and MSD systems. These systems are unique in that the same user and relay can be the most suitable one for multiple sub channels and multiple SD pairs, respectively. For OFDMA systems, we propose an algorithm called Split Select that assigns for every sub channel the user with the highest channel gain over it. For MSD systems, we propose a contention-based en masse assignment (CBEA) algorithm that assigns to each SD pair a relay that is capable of aiding it. Both Split Select and CBEA are fast and scale well with the number of nodes. For example, Split Select requires just 2.2 slots, on average, to assign a sub channel to its best user even when there are an asymptotically large number of contending users. Likewise, CBEA often takes far less than one slot, on average, to assign a relay to each SD pair.