52 research outputs found

    Radicular cyst associated with a primary first molar: A case report

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    Radicular cysts arising from deciduous teeth are rare. This report presents a case of radicular cyst associated with a primary molar following pulp therapy and discusses the relationship between pulp therapy and the rapid growth of the cyst. The treatment consisted of enucleation of the cyst sac and extraction of the involved primary teeth and 20 months follow up of the patient. Early diagnosis of the lesion would have lead to a less aggressive treatment plan

    Supplier selection and order lot sizing using dynamic programming

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    In this paper, we consider a multi-period integrated supplier selection and order lot sizing problem where a single buyer plans to purchase a single product in multiple periods from several qualified suppliers who are able to provide the required product with the needed quality in a timely manner. Product price and order cost differs among different suppliers. Buyer’s demand for the product is deterministic and varies for different time periods. The problem is to determine how much product from which supplier must be ordered in each period such that buyer’s demand is satisfied without violating some side constraints. We have developed a mathematical programming model to deal with this problem, and proposed a forward dynamic programming approach to obtain optimal solutions in reasonable amount of time even for large scale problems. Finally, a numerical example is conducted in which solutions obtained from the proposed dynamic programming algorithm is compared with solutions from the branch-and-bound algorithm. Through the numerical example we have shown the efficiency of our algorithm

    Mobility Pattern Recognition in Mobile Ad-Hoc Networks

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    ABSTRACT A Mobile Ad hoc Network (MANET) is a collection of wireless mobile nodes forming a self-configuring network without using any existing infrastructure. Network nodes in a mobile Ad-hoc network move in some motion patterns called mobility models. The mobility models play a very important role in determining the protocol performance in MANET. Thus, it is essential to study and analyze various mobility models and their effect on MANET protocols. If we can recognize the mobility pattern of motion of mobile nodes in our environment we can customize our network protocols to deal with that existing mobility model. In this paper we introduce a new method for classification and pattern recognition of mobility traces into mobility models in mobile Adhoc networks. This method uses a simple learning based classification method to recognize the existing mobility model in raw mobility traces which was collected from real motion of mobile Ad-hoc nodes or mobility traces generated by mobility simulators. Our simulation results prove ability of our proposed method to accurately classify given unknown mobility traces into various mobility models

    VNToR: Network Virtualization at the Top-of-Rack Switch

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    Cloud providers typically implement abstractions for net- work virtualization on the server, within the operating sys- tem that hosts the tenant virtual machines or containers. Despite being flexible and convenient, this approach has funda- mental problems: incompatibility with bare-metal support, unnecessary performance overhead, and susceptibility to hypervisor breakouts. To solve these, we propose to offload the implementation of network-virtualization abstractions to the top-of-rack switch (ToR). To show that this is feasible and beneficial, we present VNToR, a ToR that takes over the implementation of the security-group abstraction. Our prototype combines commodity switching hardware with a custom software stack and is integrated in OpenStack Neutron. We show that VNToR can store tens of thousands of access rules, adapts to traffic-pattern changes in less than a millisecond, and significantly outperforms the state of the art

    Experimental and numerical investigations on the seismic behavior of bridge piers with vertical unbonded prestressing strands

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    In the performance-based seismic bridge design, piers are expected to undergo large inelastic deformations during severe earthquakes, which in turn can result in large residual drift and concrete crack in the bridge piers. In this paper, longitudinal unbonded prestressing strands are used to minimize residual drift and residual concrete crack width in reinforced concrete (RC) bridge piers. Seven pier specimens were designed and tested quasi-statically and the numerical simulations were carried out. The effectiveness of using vertical unbonded prestressing strands to mitigate the residual drift and concrete crack width of RC bridge piers are examined and discussed in detail. It is found that the residual drift and residual concrete crack width of the piers can be reduced significantly by using the prestressing strands. Moreover, the strands can increase the lateral strength of the piers while have little influence on the ductility capacity of the piers. The hysteretic curves, residual drifts and strand stress of the piers predicted by the numerical model agree well with the testing data and can be used to assess the cyclic behavior of the piers

    Simulation and optimization of electrical power generation by solar ponds

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    The principal objective of the present thesis has been to develop a methodology for the simulation and optimization of electric power generation by solar ponds.A mathematical model for the analysis of the economic performance of a solar pond electric power system using a heat engine is developed. A salient feature of this model is a simple method for the analysis of a Rankine cycle. Other features include a mathematical model of the solar pond, of the energy exchange properties of the heat exchangers, as well as of the power required by the circulating pumps. The net electric power is expressed in terms of the thermodynamic properties of the organic working fluid, the temperatures of various thermodynamic states, the flow rates, the temperature and geometry of the solar pond, and the local climatic conditions. The system sizing and operating conditions which minimize the cost per kilowatt hour of electric energy is then determined through an optimization routine.The optimal storage depth and heat extraction scheduling are obtained by a semi-analytical method as well as a discrete optimal control technique. The possibility of an ice storage to act as a cooling source for an SPPP has also been investigated, which showed considerable improvement in the system's efficiency and reduction of electric energy cost.The possibility of making the NCZ of a solar pond float over a layer of fresh water has been investigated. The economical feasibility study of the concept for electric power generation was achieved using the model developed earlier.The thesis finally examines the means of enhancing the thermal storage under a solar pond by circulating LCZ brine through a network of buried horizontal pipes in the warmer part of the year. This heat stored can be used for the operation of a heat engine during the winter time if the LCZ brine is then used as a heat sink rather than a heat source.The present thesis has shown that the commonly held belief that SPPP can only function at acceptable efficiencies under semi-tropical conditions of SPPP in northern climates resulted in electric energy costs of 8.5 (CENTS)/KWh which is comparable with that of estimated by Israelis for an SPPP in semi-tropical conditions

    Control and stability dynamic performance of power systems [Book Review]

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    Oscillatory Stability Limit Prediction Using Stochastic Subspace Identification

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