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Assessments of structures with postulated or existing defects are generally carried out using standards and engineering assessment procedures. Assessments of this type involve comparing an applied force, in this case the crack driving force, with a material property, which in this case is the material's resistance to fracture, its fracture toughness. The crack driving force J can be calculated directly or implicitly by using a failure assessment diagram. Assessments can be based on either the initiation of the growth of a crack or, when dealing with ductile fracture, on an amount, e.g. 2 mm, of ductile tearing. Material fracture toughness values are obtained by testing high constraint specimens such as deeply cracked compact tension specimens and single edge notched bend specimens under uniaxial loading conditions. The high constraint of the test specimens provides conservative measurements of the fracture toughness for most applications. However, this assumption of conservatism is not necessarily applicable where there are biaxial loading conditions. The literature concerning assessments of such components mainly discusses whether uniaxial loading conditions provide conservative estimates of fracture toughness. Crack driving forces under biaxial loading can be overestimated, leading to a loss of conservatism. Conversely, biaxial loading could be beneficial and thus an approach that is consistently conservative has implications for the cost and time involved in the consequences of prematurely assessing or predicting the failure of a structure or component. This research considers the effects of biaxial loading on all the parameters involved in the integrity assessment of structures, components and specimens with defects. These parameters include the crack driving force, material fracture toughness, internal stresses and limit loads. It will address their relative effects on the determination of failure when compared with the assumption of uniaxial loading. The methods used will be analytical, using the equations and theories of standard solid mechanics, fracture mechanics and existing advice in R6 and the literature, and numerical using finite element analyses. Experimental, analytical and numerical work in the literature will be assessed and discussed and their outcomes compared with the findings of this research. The overall aim is to provide more explicit advice on the assessment of defects in components under biaxial loading in the R6 procedure.

The thesis deals with various aspects of running a web application written in PHP (programming language). It considers capabilities of different interpreters and it also compares some cloud-based services. In the practical part the thesis describes the design and implementation of a test application which was stepwise deployed to various environments where it was subjected to benchmark test. The description of deployment also depicts all the problems encountered on each platform. Finally various performance-affecting resources are discussed for the purpose of improving the application efficiency.

Microbial load can be controlled using either synthetic or natural preservatives. Particular interest has been focused on the potential application of plant essential oils as safer additives for meat. However, there is no published research on the use of essential oils during the meat drying process. This study was focused on enhancing the meat drying process. At first a value-added dried meat product by using oregano essential oil (OEO) to inhibit the growth of bacteria, and the sensorial response from assessors is presented. It was found that the application of the OEO in meat is effective in inhibiting Salmonella enteritidis and Escherichia coli. After 6 hours of drying at 55°C, 2 ml (0.038 ml l-1 air) and 1.5 ml (0.028 ml l-1 air) of OEO were considered the minimal inhibitory concentrations (MICs) against S. enteritidis and E. coli, respectively. Samples treated with 0.75 ml of OEO were more attractive for consumption compared with the control; at a higher concentration of OEO, the sensory quality of the food was affected. Next, the effect of modified blanching treatments on the drying behaviour of beef meat was evaluated by determining moisture ratio versus time curves and the influence on sensory quality of the resulted product. The 3 treatments under investigation were (1) oil treatment (2) steam blanching and (3) hot air blanching with 3 doses of oregano essential oil (1) 1.5 ml (2) 3 ml and (3) 6 ml. Each treatment had an effect on the drying time of the beef samples, however, the dose of oregano essential oil applied did not affect the drying process. The results showed that steam blanching was very effective reducing the drying time. Meanwhile, 1.5 ml and 3 ml hot air blanching samples and 1.5 ml oil treatment samples were judged as better from sensory point of view and the respondents considered that adding oregano essential oil enriched the pleasantness of the smell. In conclusion, a value-added dried meat product obtained by using oregano essential oil to enhance food safety received an acceptable sensorial response from consumers. Additionally, each modified blanching treatment tested influences the drying kinetics process, but the dose of oregano applied did not affect the drying process. In this sense, hot air blanching and oil treatment with the lowest dose had an acceptable sensorial response from consumers.

Current specifications of the American Association of State Highway and Transportation Officials (AASHTO) include restrictions on the live load deflections of highway bridge girders. Conventional practice, which utilizes hand calculations to estimate girder deflections, assumes that all girders of a highway bridge deflect to the same degree. In addition, the conventional equations do not account for AASHTO specifications requiring the evaluation of extreme force effects. As such, the accuracy of the conventional approach for calculating girder deflections is under question. The purpose of this study is, therefore, to check the accuracy of the conventional approach by testing the two aforementioned assumptions made by the equations. A composite steel girder bridge example has been selected from Design of Highway Bridges: An LRFD Approach, Third Edition by Richard M. Barker and Jay A. Puckett. The design example specifies the dimensions for all structural elements, as well as the girder type and spacing. The design example does not include specifications for the bridge bearings, and so bearing pads are designed according to the Illinois Department of Transportation (IDOT) Bridge Manual (2012). This study consists of two steps. First, a hand-calculated live load deflection for the bridge example is derived from the conventional approach (assuming all girders deflect to the same degree and without consideration for extreme force effects). Next, the finite element analysis software, NISA/Display IV, is utilized to model and analyze the real-world deflections of the bridge model. Three live loading conditions are applied to the finite element model, in accordance with AASHTO specifications. For first live load condition, the live loads are positioned at the center of each traffic lane. The second and third conditions apply extreme force effects to an interior girder and exterior girder, respectively. The results for each finite element analysis are then compared with the conventional, hand-calculated deflection. The results of this study contradict the two aforementioned assumptions made by the conventional equations for calculating girder deflections. Firstly, this study demonstrates that interior girders experience a significantly greater live load deflection than interior girders. More importantly, the results indicate that the conventional equations underestimate the live load deflection of an interior girder subjected to extreme force effects. None of the results, however, suggest that the bridge example is at risk of excessive deformation, and so the extent to which these drawbacks present a concern can be left to the discretion of the engineer.

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Made available in DSpace on 2014-06-11T19:31:29Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-07-04Bitstream added on 2014-06-13T20:02:02Z : No. of bitstreams: 1 correa_apfl_dr_botfm.pdf: 975637 bytes, checksum: fd75b8cd1d1053ad74ff487f91f0329a (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Universidade Estadual Paulista (UNESP) / O objetivo do estudo foi avaliar a resposta humoral, a carga parasitária e os aspectos histopatológicos presentes no fígado em camundongos BALB/c experimentalmente infectados por L. (L.) chagasi e imunossuprimidos. 96 camundongos foram subdivididos em quatro grupos: controle (I) – sem tratamento; imunossuprimidos (II) – tratamento com dexametasona (DXM) e pentoxifilina (PTX); infectado (III) – infecção por L (L.) chagasi e infectados e imunossuprimidos (IV) - infecção por L (L.) chagasi e tratados com DXM e PTX. O dia de infecção foi considerado como o dia zero e a imunossupressão ocorreu 60 dias pós-infecção. As amostras foram obtidas de cada grupo, em momentos distintos 15, 30, 60, 75 e 90 dias pós-infecção, em que se coletou sangue total, para detecção de IgG1 e IgG2a pelo ensaio imunoenzimático (ELISA), fragmentos de baço e fígado, para detecção da carga parasitária pela técnica de microtitulação em cultura e fragmentos de fígado para o exame histopatológico. Houve diferença significativa na produção das imunoglobulinas e IgG1 foi à subclasse de imunoglobulina mais produzida pelos grupos (P < 0,0001). Quando comparadas a subclasses de imunoglobulinas dentro do mesmo grupo, IgG1 também apresentou médias maiores de produção nos grupos III e IV (P = 0,014 e P = 0,009). E quando se considera o momento, não houve diferenças significativas entre IgG1 e IgG2a. Aos 90 dias pós-infecção foram encontradas diferenças significativas entre as médias de produção de IgG1 e IgG2a, entre os grupos III e IV e o grupo III produziu mais as duas subclasses (P = 0,02). Nos momentos 75 e 90 dias pós-infecção houve produção maior de IgG1 e IgG2a. O Grupo IV apresentou maior carga parasitária (P < 0,005). A carga parasitária no fígado foi mais elevada 15 e 30 dias pós-infecção... / This study aimed to evaluate the humoral response, the parasite load and liver histopathological features in BALB/c experimentally infected by L. (L.) chagasi and immunosuppressed Ninety-six mice divided into four groups: control (I) - no treatment; immunosuppressed (II) - Treatment with dexamethasone (DXM) and pentoxifylline (PTX), infected (III) - infection by L. (L.) chagasi and infected and immunosuppressed (IV) - infection by L (L.) chagasi and treated with PTX and DXM. The days of infection was considered as day zero and immunosuppression occurred 60 days post-infection. Samples were obtained from each group at different times 15, 30, 60, 75 and 90 days post-infection, which collected whole blood for detection of IgG1 and IgG2a by test immunoassay (ELISA), fragments of spleen and liver, to detect the parasite load in the technique microtiter culture and fragments of liver for histopathology. Significant differences in production of immunoglobulins, IgG1 was the subclass immunoglobulin produced by most groups (P<0.0001). When comparing the immunoglobulin subclasses within the same group, IgG1 also showed higher average production in groups III and IV (P=0.014 and P=0.009). When one considers the time, there were no significant differences between IgG1 and IgG2a. At 90 days post-infection were significant differences between the means of production of IgG1 and IgG2a between group III and IV and group III produced over the two subclasses (P=0.02). In periods of 75 and 90 days post-infection there was increased production of IgG1 and IgG2a. Group IV showed a higher parasite load (P <0.005). The parasite load in the liver was higher 15 and 30 days post-infection and 60 post-infection in spleen (P = 0.0001, P = 0.004, P=0.01), regardless of group. Considering the group IV, 15 days post-infection... (Complete abstract click electronic access below)

Master of Science / Civil Engineering / Hayder Rasheed / Reverse diagonal shear cracking at the supports of many reinforced concrete girders is a phenomenon affecting a number of KDOT’s low-volume bridges built in the early-to-mid 1900’s. This phenomenon is not addressed in the AASHTO Bridge Design Manual (2002) or ACI specifications. This study investigates the causes of this cracking and creates BRIDGE (Bridge Rating of Inclined Damage at Girder Ends), an Excel-based software to determine the load rating of a user specified bridge exhibiting reverse diagonal shear cracking at the girder supports. A user-interface is created which allows a user to create a grillage model of an existing bridge and to place various rating trucks on the bridge. Equivalent flexibility analysis is used to distribute the truck live loads from within the deck panels to the surrounding girders and diaphragms. Stiffness matrices are utilized to find the nodal displacements then the reactions at the girder supports caused by the truck live loads and bridge dead load. These reactions are checked against RISA software models to test the accuracy of the stiffness matrix application. ABAQUS FE models and Mohr’s circle stress distribution is used to find the driving and clamping forces on the crack. These forces are caused by resolving the dead and live load reactions and the friction force generated between the concrete girder and the rusty steel bearing pad along the shear crack orientation. These clamping and driving forces are used, along with the simplified modified compression field theory to determine the shear capacity of each girder at the reverse cracks. A modified version of Equation 6B.4.1 from the Manual for Bridge Evaluation (2011) is used to find the operating and inventory rating factors for the bridge.

There are a huge number of customers using Ericsson’s prepaid telecom charging system. This means that even the smallest optimization done in its management of load results in a big win when considering time and CPU usage. Ericsson wishes therefore to learn about how the load management can be improved considering speed, i.e. faster response to load changes. In this thesis work two subsystems of the prepaid telecom system are modeled. The first subsystem treats and prepares the telecom activity before it enters the second subsystem which checks if there is coverage for the action that the telecom activity asks for to be performed. A model which is an emulation of the subsystems is built using c++. It captures the timing of the real system not the logic or function. The c++ approach is compared to a Matlab approach which runs much slower in simulation. In addition, the model enables full view of the queue sizes and the rejects made by the regulator. Verification has been performed with self generated data based on synthetic test cases. Verification and analysis show that the model captures the intended behavior of load management. Information about different software parameters and its influence on the output is obtained. Different scenarios are tested and the outcome discussed.

Should Eskom and municipalities be held liable for loss resulting from load shedding? In essence, this is the question this dissertation answers or at least sheds some light on. This dissertation looks at the possibility of holding Eskom and municipalities delictually or contractually liable for loss resulting from load shedding. It does this by first discussing the delictual elements and thereafter determining whether these elements are present in the current circumstances in which Eskom and municipalities find themselves. It also looks at the relevant forms of breach of contract which may be present under the circumstances. It discusses their applicability to Eskom’s Standard Conditions of Supply for Small Supplies with Conventional Metering. It also discusses the applicability of these forms of breach to the relevant electricity supply by-laws which, in essence, provide the terms and conditions relating to the agreement for the supply of electricity between municipalities and consumers. The nature of electricity supply contracts are discussed throughout the dissertation in brief. It is found that electricity in itself is a very unique thing where the supply and sale thereof cannot be separated. The dissertation also deals with some interesting legislation which has the effect of municipalities and Eskom having to prove that they were not negligent in causing loss to consumers. Furthermore, the dissertation looks at related topics, briefly discussing class actions, pure economic loss, the “once and for all” rule, mitigation of loss, prescription, concurrent actions and possible infringement of constitutional rights. It considers the types of loss which might be claimed for as well as alternatives to instituting claims for damages. In the end, the conclusion is reached that all claims must be assessed with due regard to the circumstances surrounding each claim. It also comes to the conclusion that, in general, Eskom can be held delictually and contractually liable for load shedding. The assessed contract contains provisions which are contrary to national legislation and thus inoperative. It is, however, doubtful if such liability would succeed since courts would in all probability deny such claims for fear of opening the flood gates. It might be harder and even impossible to hold municipalities delictually liable. However, municipalities might be contractually liable as it is clear that by-laws, which regulate the supply of electricity to the consumer by the municipality, are often inoperative since these are in conflict with national legislation. This dissertation does not proclaim to provide all the answers relating to claims resulting from load shedding. It is, however, hoped that it will provide some insight into the considerations that need to be taken into account whilst raising some thought provoking questions. / Dissertation (LLM)--University of Pretoria, 2011. / Private Law / unrestricted