PLCs are extensively used for the discrete and continuous control of non-intelligent shop-floor devices. The debugging phase of ladder logic development for PLCs is very cumbersome and difficult. Most often on-line debugging which is expensive and time consuming is used for debugging. Computer simulation techniques applied to this problem, leaves much to be desired. The best technique developed for ladder logic debugging is the use of ladder-based triggers. A ladder-based trigger is a function which suspends simulation execution whenever a vector of ladder variables equates to a vector of predefined states. System-based debugging facilities are those which aid a programmer in error detection at the system level. System based triggers will identify system faults and set traps within a simulation model to detect their occurrence. This approach will provide information necessary for a faster correction of the ladder logic once a trigger is activated. The system based debugging tool developed is capable of scanning a boolean representation of a PLC program with input coils, counters, timers, "and" conditions, "or conditions and output coils. The program provides the following facilities: 1. Graphics programs can be attached to the simulation program for better visualization. 2. The simulation program allows interactive control over the test bed developed. In a non-interactive simulation it can be executed in a timed sequential mode or random mode. 3. Triggers can be set by the user depending on the conditions that are to be monitored. 4. The program stops execution whenever a trigger is activated. 5. The program provides a trace of the output that caused the trigger and also of the inputs to this output, along with their state values at the time of activation. The use of system based techniques and graphics in the debugging of PLC ladder logic is demonstrated. Further the use of an object oriented frame work in the development of the debugging software is also demonstrated. / Master of Science

A simulation model is developed for use in programmable controller ladder diagram testing. The developed model represent a physical flexible manufacturing system that can be controlled by different ladder logic diagrams. The model is capable of detecting initial ladder errors, displaying state changes in the ladder, and logging an operations history. As a result of the simulation development, insight into a generalized system descriptive language is obtained. This includes the language structure, specific data requirements, and an interface control method. The model also allows the user to locate optimal ladder solutions by comparing the results produced by different ladder diagrams. This thesis contains a literature review that establishes a history of programmable controller ladder testing and simulation modeling. The literature review provides impetus to the research by conveying the need for alternative methods of ladder diagram development, debugging, and testing. / M.S.

This thesis presents methodologies for the operation of a programming/documentation system for a Texas Instruments Model 530 programmable controller. The methodologies include: 1) a means to store information about the structure of a ladder diagram and display the ladder diagram on a CRT screen, 2) a means to convert the ladder diagram information into its equivalent Boolean code, and 3) a means to convert Boolean code into its equivalent ladder diagram information. / Master of Science

One of the main and crucial activities of an insurance company is to determine amount of technical reserves to be generated. If the insurance company performs in the non-life insurance branch, it focuses first of all on loss reserve which is generated to settle debts coming from insurance claims. To set the proper amount of this reserve, especially of the reserve on incurred but not reported losses (IBNR), mathematical and statistical methods are used. This thesis introduces one of the most used methods which is the chain ladder method. It presents the first chain ladder deterministic model then moves to its stochastic extension in a form of Mack's model and finally gets to the Munich chain ladder model, which takes into calculations not only data on losses paid but also losses incurred. In the theoretical part both these models (standard Mack's chain ladder and Munich chain ladder) are presented both separately and in a common context so that later in the analytical section they could be demonstrated on real data.

published_or_final_version / Architecture / Master / Master of Architecture

Dans la première partie de la thèse, nous nous intéressons à la convergence faible du processus empirique pondéré des copules. Nous fournissons la condition suffisante pour que cette convergence ait lieu vers un processus Gaussien limite. Nos résultats sont obtenus dans un espace de Banach L^p. Nous donnons des applications statistiques de ces résultats aux tests d'adéquation (tests of goodness of fit) pour les copules. Une attention spéciale est portée aux tests basées sur des statistiques de type Cramér-von Mises.Dans un second temps, nous étudions le problème de provisionnement stochastique pour une compagnie d'assurance non-vie. Les méthodes stochastiques sont utilisées afin d'évaluer la variabilité des réserves. Le point de départ pour cette thèse est une incohérence entre les méthodes utilisées en pratique et celles publiées dans la littérature. Pour remédier à cela, nous présentons un outil général de provisionnement stochastique à horizon ultime (Chapitre 3) et à un an (Chapitre 4), basé sur la méthode Chain Ladder. / The aim of this thesis is twofold. First, we concentrate on the study of weak convergence of weighted empirical copula processes. We provide sufficient conditions for this convergence to hold to a limiting Gaussian process. Our results are obtained in the framework of convergence in the Banach space $L^{p}$ ($1\leq p <\infty $). Statistical applications to goodness of fit (GOF) tests for copulas are given to illustrate these results. We pay special attention to GOF tests based on Cramér-von Mises type statistics. Second, we discuss the problem of stochastic claims reserving in general non-life insurance. Stochastic models are needed in order to assess the variability of the claims reserve. The starting point of this thesis is an observed inconsistency between the approaches used in practice and that suggested in the literature. To fill this gap, we present a general tool for measuring the uncertainty of reserves in the framework of ultimate (Chapter 3) and one-year time horizon (Chapter 4), based on the Chain-Ladder method.

[pt] A reserva IBNR é uma reserva de suma importância para as seguradoras. Seu cálculo tem sido realizado por métodos, em sua grande maioria, determinísticos, tradicionalmente aplicados a informações de sinistros agrupadas num formato particular intitulado triangulo de run-off. Esta forma de cálculo foi muito usada por décadas por sua simplicidade e pela limitação da capacidade de processamento computacional existente. Hoje, com o grande avanço dessa capacidade, não haveria necessidade de deixar de investigar informações relevantes que podem ser perdidas com agrupamento dos dados. Muitas são as deficiências dos métodos tradicionais apontadas na literatura e o uso de informação detalhada tem sido apontado por alguns artigos como a fonte para superação dessas deficiências. Outra busca constante nas metodologias propostas para cálculo da IBNR é pela obtenção de boas medidas de precisão das estimativas obtidas por eles. Neste ponto, sobre o uso de dados detalhados, há a expectativa de obtenção de medidas de precisão mais justas, já que se tem mais dados. Inspirada em alguns artigos já divulgados com propostas para modelagem desses dados não agrupados esta dissertação propõe um novo modelo, avaliando sua capacidade de predição e ganho de conhecimento a respeito do processo de ocorrência e aviso de sinistros frente ao que se pode obter a partir dos métodos tradicionais aplicados à dados de quantidade para obtenção da quantidade de sinistros IBNR e sua distribuição. / [en] The IBNR reserve is a reserve of paramount importance for insurers. Its calculation has been accomplished by methods, mostly, deterministic, traditionally applied to claims grouped information in a particular format called run-off triangle . This method of calculation was very adequate for decades because of its simplicity and the limited computational processing capacity existing in the past. Today, with the breakthrough of this capacity, no waiver to investigating relevant information that may be lost with grouping data would be need. Many flaws of the traditional methods has been mentioned in the literature and the use of detailed information has been pointed as a form of overcoming these deficiencies. Another frequent aim in methodologies proposed for the calculation of IBNR is get a good measure of the accuracy of the estimates obtained by them and that is another expectation about the use of detailed data, since if you got more data you could get better measures. Inspired by some articles already published with proposals for modeling such not grouped data, this dissertation proposes a new model and evaluate its predictive ability and gain of knowledge about the process of occurrence and notice of the claim against that one can get from the traditional methods applied to data of amount of claims for obtain the amount of IBNR claims and their distribution.

Loss reserving in P&amp;amp;C insurance, is the common practice of estimating the insurer’s liability from future claims it will have to pay out on. In the recent years, it has been popular to explore the options of forecasting this loss with the help of machine learning methods. This is mainly attributed to the increase in computational power, opening up opportunities for handling more complex computations with large datasets. The main focus of this paper is to implement and evaluate a recurrent neural network called the deeptriangle by Kuo for modelling payments of individual reported but not settled claims. The results are compared with the traditional Chain Ladder method and a baseline model on a simulated dataset provided by Wüthrich’s simulation machine.  The models were implemented in Python using Tensorflow’s functional API. The results show that the recurrent neural network does not outperform the Chain Ladder method on the given data. The recurrent neural network is weak towards the sparse and chaotic nature of individual claim payments and is unable to detect a stable sequential pattern. Results also show that the neural network is prone to overfitting, which can theoretically be compensated with larger dataset but comes at a cost in terms of feasibility. / Reservsättning inom skadeförsäkring handlar om att beräkna framtida kostnader av en försäkringsgivare. Under de senaste åren har det blivit allt populärare att undersöka tillämpningen av olika statistiska inlärningsmetoder inom reservsättning. Den här uppsatsen syftar till att implementera och utvärdera ett återkommande neuraltnätverk som kallas för ”deeptriangle by Kuo” för att modellera utbetalningar av individuella rapporterade men icke­ färdigbetalda försäkringsfordringar. Resultaten kommer att jämföras med den traditionella Chain Ladder metoden samt en grundmodell på ett simulerat dataset som tillhandahålls av ”Wüthrichs simulation machine”. Modellerna implementeras i Python med hjälp av Tensorflows Functional API. Resultatet är att det återkommande neurala nätverket inte överträffar Chain Ladder metoden med den givna datan. Det återkommande neurala nätverket har svårigheter för att känna igen mönster i datamängder som individuella skadebetalningar eftersom datamängden till sin natur är spridd och kaotisk. Resultaten visar också att det neurala nätverket är benäget att överanpassa, vilket teoretiskt kan kompenseras med en större datamängd men som i sin tur bidrar till en risk för ogenomförbarhet.

Text in English / A survey by means of mailed questionnaires was conducted to compile a career profile of persons who completed the B.Cur programme at Medunsa. The sample consisted of all the nurses who had completed the B.Cur. programme over a decade from 1985 to 1994. Forty-one percent of the questionnaires were returned and the findings indicated that the nurse graduates were committed to nursing and were contributing to the nursing services in south Africa. The public service was the largest employer of the graduate nurses. Their commitment to nursing is shown by their long service as well as post-registration qualifications sought in nursing. The B.Cur programme at Medunsa had adequately prepared them to practice nursing. There appears to be a need, however, to review the curriculum in some areas. It was concluded that Medunsa has contributed to the provision of well qualified nurses. / Health Studies / M.A. (Nursing Science)

No description available.