Verification Conditions are Code

This paper presents a new theoretical result concerning Hoare Logic. It is shown here that the verification conditions which support a Hoare Logic program derivation are themselves sufficient to construct a correct implementation of the given pre-, post- condition specification. This property is mainly of theoretical interest, though it is possible that it may have some practical use, for example if predicative programming methodology is adopted. The result is shown to hold for both the original, partial correctness, Hoare logic, and also a variant for total correctness derivations

TEMPERATURE CONTROL OF TRANSFORMERS USING SOFT COMPUTING TECHNIQUES

ABSTRACT The adaptability of a transformer enables it to have a wide range of applications. One of the most important parameter that has an influence on the transformer insulation is the 'TEMPERATURE'. In a non oil transformer, temperature has more significance because the entire cooling medium is air. Hence, the parameter to be controlled is the fan speed that varies invariantly with the load. The conventional control technique fails to achieve this task .So to have all the intermediate values, we go for the predicate control which is possible by the use of fuzzy logic (Soft computing technique). Several studies were made with two parameters i.e. load and temperature. But this paper includes a variable "MOISTURE" also

Freeze-Thawing of Polyester/E-Glass as an Evaluation of an ASTM International Test Standard Proposal

American Composites Manufacturers Association (ACMA) reported in 2009 that the four major sectors currently utilizing fiber reinforced polymers (FRP) are construction, corrosion, marine, and transportation in descending order of total FRP shipped. All of these sectors are known to be billion dollar industries and they are all involved with applications subjected to freezing and thawing. FRP encompass many characteristics that are beneficial to these sectors and also in resisting this exposure. ASTM International has yet not developed a standard to test FRP materials resistance to freeze-thaw (FT) cycling exposure. The D20.18.02 committee of the ASTM is in the process of creating a test standard for freeze-thawing of FRP and has developed a draft standard. This study was conducted to assist in the development of this standard. A pultruded mat and roving E-glass reinforced polyester with aluminum tri hydroxide (ATH) filler was used. Three sample batches were subjected to FT-cycling. Two sample batches were subjected to manual FT-cycling; one was exposed to 30 days of initial moisture exposure (30W-samples) and the other to 60 days (60W-samples). The third sample batch was exposed to 30 days of initial moisture exposure and automatic FT-cycling through the use of a programmable temperature chamber (30TC-samples). The samples were first conditioned in distilled water at 23°C (77°F) for 30 days. Secondly they were exposed to a total of 100 FT-cycles each 6 hours long consisting of 3 hour of thawing in distilled water at 23°C and 3 hours of dry freezing at ?20°C (?4°F). The ultimate tensile strength (UTS) of three sample batches was determined through ASTM D638 upon the completion of the 100 FT-cycles. The results from the three test environments shosimilar degradation. The percent reductions in the samples mean UTS of the 30W-, 60W-, and 30TC-samples was found to be 21.0%, 17.6%, and 19.1%, respectively. The test parameters were evaluated by implementing several sample batches and through the use of the preliminary research conducted. Contributions to the development of the draft from the D20.18.02 committee were made based on these findings and are presented in this study

Error and Predicativity

The article surveys ideas emerging within the predicative tradition in the foundations of mathematics, and attempts a reading of predicativity constraints as highlighting different levels of understanding in mathematics. A connection is made with two kinds of error which appear in mathematics: local and foundational errors. The suggestion is that ideas originating in the predicativity debate as a reply to foundational errors are now having profound influence to the way we try to address the issue of local errors. Here fundamental new interactions between computer science and mathematics emerge

Probabilistic Semantics for RoboChart A Weakest Completion Approach

We outline a probabilistic denotational semantics for the RoboChart language, a diagrammatic, domain-specific notation for de- scribing robotic controllers with their hardware platforms and operating environments. We do this using a powerful (but perhaps not so well known) semantic technique: He, Morgan, and McIver’s weakest completion semantics, which is based on Hoare and He’s Unifying Theories of Programming. In this approach, we do the following: (1) start with the standard semantics for a nondeterministic programming language; (2) propose a new probabilistic semantic domain; (3) propose a forgetful function from the probabilistic semantic domain to the standard semantic domain; (4) use the converse of the forgetful function to embed the standard semantic domain in the probabilistic semantic domain; (5) demonstrate that this embedding preserves program structure; (6) define the probabilistic choice operator. Weakest completion semantics guides the semantic definition of new languages by building on existing semantics and, in this case, tackling a notoriously thorny issue: the relationship between demonic and probabilistic choice. Consistency ensures that programming intuitions, development techniques, and proof methods can be carried over from the standard language to the probabilistic one. We largely follow He et al., our contribution being an explication of the technique with meticulous proofs suitable for mechanisation in Isabelle/UTP

A numerical approach to model and predict the energy absorption and crush mechanics within a long-fiber composite crush tube

Past research has conclusively shown that long fiber structural composites possess superior specific energy absorption characteristics as compared to steel and aluminum structures. However, destructive physical testing of composites is very costly and time consuming. As a result, numerical solutions are desirable as an alternative to experimental testing. Up until this point, very little numerical work has been successful in predicting the energy absorption of composite crush structures. This research investigates the ability to use commercially available numerical modeling tools to approximate the energy absorption capability of long-fiber composite crush tubes. This study is significant because it provides a preliminary analysis of the suitability of LS-DYNA to numerically characterize the crushing behavior of a dynamic axial impact crushing event;Composite crushing theory suggests that there are several crushing mechanisms occurring during a composite crush event. This research evaluates the capability and suitability of employing, LS-DYNA, to simulate the dynamic crush event of an E-glass/epoxy cylindrical tube. The model employed is the composite progressive failure model , a much more limited failure model when compared to the experimental failure events which naturally occur. This numerical model employs (1) matrix cracking, (2) compression, and (3) fiber breakage failure modes only. The motivation for the work comes from the need to reduce the significant cost associated with experimental trials. This research chronicles some preliminary efforts to better understand the mechanics essential in pursuit of this goal. The immediate goal is to begin to provide deeper understanding of a composite crush event and ultimately create a viable alternative to destructive testing of composite crush tubes

Granulometry, chemistry and physical interactions of non-colloidal particulate matter transported by urban storm water

Urban rainfall-runoff is a major source of anthropogenic pollutions to the natural water bodies. Particulate matter generated from anthropogenic environments and activities is a constituent of environmental concern as well as a carrier substrate for reactive contaminants such as metals. Partitioning, transport and transformation of particulate-bound contaminants are determined by the granulometry, physical and geochemical properties of the particulate carriers. Previous research emphasized in the transport of colloidal and suspended particles in rainfall-runoff. The settleable and sediment material were ignored though they are a major granulometric fraction which may contain most of the sorbed or transported constituents such as metals, organics or inorganics. In this research the entire flow section of rainfall-runoff was captured. Particulate matters in the catchment were analyzed for solid fractions, metal partitioning and distribution, fractal nature, morphology, chemical composition, and settling characteristics. Unsteady hydrodynamic conditions and short residence time determine coagulation and flocculation is still a dynamic mechanism in urban rainfall-runoff. Natural coagulation and flocculation (C/F) as well as coagulants/flocculants assisted C/F was studied for particles in urban rainfall-runoff. A C/F model incorporating fractal geometry and sedimentation mechanism was applied to simulate the particle size distribution in a 2-m settling column test. The overarching objective is to facilitate decision-making with respect to urban runoff management, regulations, treatment and potential disposal of runoff sediment residuals

Cities as hotspots for invasions: the case of the eThekwini Municipality.

Doctoral Degree. University of KwaZulu-Natal, Durban.Increased anthropogenic activities (trade and travel) have caused an increase in the introduction of biological organisms outside of their native range. Biological invasions result in serious negative ecological, economic and social impacts in their invaded range and are responsible for a decline in native biodiversity. These negative impacts become more prominent in highly transformed environments, such as those found in cities which are often the first points of introduction for alien species. Durban (eThekwini) is situated on the east coast of South Africa and is one of the largest port cities on the African continent, making it an important economic centre for the country. It is the third most populated city in South Africa and is a major contributor towards tourism. Additionally, Durban is located in the Maputaland-Pondoland Albany, one of thirty-four global hotspots of biodiversity. This study focuses on the patterns, processes and drivers of biological invasions in Durban. I investigated three important aspects of alien species responses in urban environments: 1) precaution through the prevention of alien species introduction; 2) prioritisation through using a combination of early warning systems and techniques to identify potentially high-risk alien species; and 3) preparedness and response for a potential incursion event of Solenopsis invicta in Durban. I investigated the importance of preventing alien species introductions by identifying the pathways which facilitate the highest number of introductions for prioritisation for prevention efforts. Furthermore, I identified vectors responsible for secondary spread of alien species in cities. The majority of alien species were either released into nature or escaped from captivity and spread within cities through unaided dispersal. It is difficult to control the natural spread of species, therefore preventing alien species introductions is paramount. However, preventing the introduction of all alien species to a new area is difficult to achieve. Therefore, prioritising alien species for prevention efforts is an essential component of responding to biological invasions which will allow decision makers to more carefully allocate limited resources and time to species with the potential to result in severely negative impacts. Incorporating a holistic prioritisation approach based not only on alien species with a high-risk of invading new areas, but also the pathways which facilitate their introduction and the areas which are most at risk of being invaded is beneficial for decision makers in targeting priority species for prevention efforts. I developed a methodology, integrating these three aspects (species, pathways and sites), to select priority species to target for prevention efforts and identified areas most at risk of being invaded by these species using climatic suitability modelling to select priority targets for prevention efforts. Additionally, I used climatic models and pathway information to identify potential points of first introduction and sites of first naturalisation to target for active and passive surveillance endeavours. Solenopsis invicta Buren (the red imported fire ant) was identified as a potentially high-risk species posing serious ecological and socio-economic threats for Durban. I then explored opportunities for strategic response planning for Solenopsis invicta for Durban, South Africa. In doing so, I identified key priorities to help decision makers initiate strategic response planning for a potential incursion of this species to Durban. The research presented in this study outlines approaches that can assist with the prevention, prioritisation, and preparedness in responding to alien species in urban environments.Publications on page v