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Search Results: 1 - 10 of 224 matches for " Haruna Bakari Rann "
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Application of Iterative Approaches in Modeling the Efficiency of ARIMA-GARCH Processes in the Presence of Outliers  [PDF]
Emmanuel Alphonsus Akpan, K. E. Lasisi, Ali Adamu, Haruna Bakari Rann
Applied Mathematics (AM) , 2019, DOI: 10.4236/am.2019.103012
Abstract: The study explored both Box and Jenkins, and iterative outlier detection procedures in determining the efficiency of ARIMA-GARCH-type models in the presence of outliers using the daily closing share price returns series of four prominent banks in Nigeria (Skye (Polaris) bank, Sterling bank, Unity bank and Zenith bank) from January 3, 2006 to November 24, 2016. The series consists of 2690 observations for each bank. The data were obtained from the Nigerian Stock Exchange. Unconditional variance and kurtosis coefficient were used as criteria for measuring the efficiency of ARIMA-GARCH-type models and our findings revealed that kurtosis is a better criterion (as it is a true measure of outliers) than the unconditional variance (as it can be depleted or amplified by outliers). Specifically, the strength of this study is in showing the applicability and relevance of iterative methods in time series modeling.
Heat Transfer Optimization in Air Flat Plate Solar Collectors Integrated with Baffles  [PDF]
Ramadhani Bakari
Journal of Power and Energy Engineering (JPEE) , 2018, DOI: 10.4236/jpee.2018.61006
Abstract: This paper presents an experimental analysis for comparisons of conventional flat plate solar collectors and collectors integrated with different numbers of baffles. Heat transfer between absorber plate and drying fluid (air) has been one of the major challenges in the design and operations of the indirect solar dryer systems. In this experiment, efficiency of air flat plate solar collector integrated with 2, 3, 4 and 8 baffles was studied and compared with the ordinary collector. The results showed that integrating solar collector with baffles significantly increased the efficiency of the system. It was noted that collector with 2, 3, 4 and 8 baffles had a mean efficiency of 29.2%, 31.3%, 33.1% and 33.7% respectively while with no baffles was 28.9%. The analysis showed that when there were less than four baffles in the collector, heat transfer was dominant over pressure drop and hence high efficiency. However, when the number of baffles exceeded four, the effect associated with an increase in pressure drop highly observed compared to heat transfer coefficient, thus resulted to insignificant increase in efficiency. Therefore, the optimum number of four baffles was commended for the designed model for optimum efficiency.
Review: Building the Revolution: Soviet Art and Architecture 1915-1935
James Rann
Opticon1826 , 2012, DOI: 10.5334/opt.121209
Abstract:
Equilibrium and Potential in Coalitional Congestion Games
Sergey Kuniavsky,Rann Smorodinsky
Computer Science , 2011,
Abstract: The model of congestion games is widely used to analyze games related to traffic and communication. A central property of these games is that they are potential games and hence posses a pure Nash equilibrium. In reality it is often the case that some players cooperatively decide on their joint action in order to maximize the coalition's total utility. This is by modeled by Coalitional Congestion Games. Typical settings include truck drivers who work for the same shipping company, or routers that belong to the same ISP. The formation of coalitions will typically imply that the resulting coalitional congestion game will no longer posses a pure Nash equilibrium. In this paper we provide conditions under which such games are potential games and posses a pure Nash equilibrium.
Greediness and Equilibrium in Congestion Games
Sergey Kuniavsky,Rann Smorodinsky
Computer Science , 2011,
Abstract: Rosenthal (1973) introduced the class of congestion games and proved that they always possess a Nash equilibrium in pure strategies. Fotakis et al. (2005) introduce the notion of a greedy strategy tuple, where players sequentially and irrevocably choose a strategy that is a best response to the choice of strategies by former players. Whereas the former solution concept is driven by strong assumptions on the rationality of the players and the common knowledge thereof, the latter assumes very little rationality on the players' behavior. From Fotakis \cite{fotakis10} it follows that for Tree Representable congestion Games greedy behavior leads to a NE. In this paper we obtain necessary and sufficient conditions for the equivalence of these two solution concepts. Such equivalence enhances the viability of these concepts as realistic outcomes of the environment. The conditions for such equivalence to emerge for monotone symmetric games is that the strategy set has a tree-form, or equivalently is a `extension-parallel graph'.
Ex-Post Equilibrium and VCG Mechanisms
Rakefet Rozen,Rann Smorodinsky
Computer Science , 2012,
Abstract: Consider an abstract social choice setting with incomplete information, where the number of alternatives is large. Albeit natural, implementing VCG mechanisms may not be feasible due to the prohibitive communication constraints. However, if players restrict attention to a subset of the alternatives, feasibility may be recovered. This paper characterizes the class of subsets which induce an ex-post equilibrium in the original game. It turns out that a crucial condition for such subsets to exist is the existence of a type-independent optimal social alternative, for each player. We further analyze the welfare implications of these restrictions. This work follows work by Holzman, Kfir-Dahav, Monderer and Tennenholtz (2004) and Holzman and Monderer (2004) where similar analysis is done for combinatorial auctions.
Sequential Information Elicitation in Multi-Agent Systems
Rann Smorodinsky,Moshe Tennenholtz
Computer Science , 2012,
Abstract: We introduce the study of sequential information elicitation in strategic multi-agent systems. In an information elicitation setup a center attempts to compute the value of a function based on private information (a-k-a secrets) accessible to a set of agents. We consider the classical multi-party computation setup where each agent is interested in knowing the result of the function. However, in our setting each agent is strategic,and since acquiring information is costly, an agent may be tempted not spending the efforts of obtaining the information, free-riding on other agents' computations. A mechanism which elicits agents' secrets and performs the desired computation defines a game. A mechanism is 'appropriate' if there exists an equilibrium in which it is able to elicit (sufficiently many) agents' secrets and perform the computation, for all possible secret vectors.We characterize a general efficient procedure for determining an appropriate mechanism, if such mechanism exists. Moreover, we also address the existence problem, providing a polynomial algorithm for verifying the existence of an appropriate mechanism.
Subjective Perception Games and Privacy
Ronen Gradwohl,Rann Smorodinsky
Computer Science , 2014,
Abstract: We analyze a general framework for modeling agents whose utility is derived from both their actions and the perceptions of others about their type. We show that such perception games always have equilibria, and discuss two natural refinements. We demonstrate the applicability of our framework in a variety of contexts, with a particular emphasis on privacy-related issues.
Magnetic monopoles, nuclearites, Q-balls: a qualitative picture
D. Bakari
Physics , 2000,
Abstract: We present qualitative pictures of the structures of magnetic monopoles (MMs), nuclearites (nuggets of strange quark matter, strangelets, surrounded by electrons) and Q-balls (supersymmetric states of squarks, sleptons and Higgs fields). In particular we discuss the relation between their mass and size. MMs, nuclearites and Q-balls could be part of the cold Dark Matter (DM); we consider astrophysical limits on the flux of these particles in the cosmic radiation.
Effects of Feeding Onion (Allium cepa) and Garlic (Allium sativum) on Some Performance Characteristics of Broiler Chickens
Slyranda Baltini Aji,Kennedy Ignatius,Asha` Adatu Y. Ado,Joel Bakari Nuhu,Auwal Abdulkarim,Usman Aliyu,Muhammad Bello Gambo,Mohammed Adamu Ibrahim,Haruna Abubakar,Mohammed M. Bukar,Hama`Adama M. Imam,Patrick T. Numan
Research Journal of Poultry Sciences , 2012, DOI: 10.3923/rjpscience.2011.22.27
Abstract: In view of the current shift towards the use of growth promoters of natural origin, this study was carried out to determine the effects of feeding onion and garlic on some performance characteristics (body weight, feed intake, water intake, feed conversion ratio, feeding cost and carcass yield) of broiler chickens. A total of 104,4 weeks old broiler chickens were divided into 2 equal groups of 62 birds each at random (one for onion and the other for garlic) and used in the study. The result of the study revealed that garlic and onion significantly (p<0.05) increased the body weight of birds at 50 and 100 mg dose whereas only 100 mg of onion significantly (p<0.05) increased their feed and water intake. There was improvement in the feed conversion ratio of all the treated birds but those of the group that were given onion appeared better. The study also revealed that onion at 25 and 50 mg decreased the feeding cost of the treated group of birds at the end of the 21 days trial period but at 100 mg and garlic at all the doses regimens used increased their feeding cost. Both treatments did not affect the carcass yield of the birds. It was concluded that onion and garlic could be used to improve the productive performance of broiler chickens but more studies need be done to establish the appropriate amount, age and other favorable conditions under which the best result can be achieved with these plant materials.
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