1,721,062 research outputs found
Query optimization in mobile environments
No full textWe consider the issue of optimizing queries for distributed processing in mobile environment. An interesting characteristic of mobile machines is that they depend on battery as a source of energy which may not be substantial enough. Hence, the appropriate optimization criterion in a mobile environment considers both resource utilization and energy consum- ption at the mobile client.
In this scenario, the optimal plan for a query depends on the residual battery level of the mobile client and the load at the server. We approach this problem by compiling a query into a sequence of candidate plans, such that for any state of the client-server system, the optimal plan is one of the candidate plans.
A general solution is proposed by adapting the partial order dynamic programming search algorithm (p.o dp) such that the coverset of the query is the set of candidate plans. We propose two novel algorithms, namely, the linear combinations algorithm and the linearset algorithm (referred to as the linear algorithms) that compute the linearset of a query. The linear- set of a query is an approximation to the coverset returned by p.o. dp.
We show, by means of simulation, that (1) the linearset is an excellent approximation of the coverset, (2) query compilation using the linear algorithms outperform query compilation using p.o. dp by factors ranging from 2 to 9, (3) the time taken to compile queries using the linear algorithms for the general optimization criterion is at most twice the time taken by a System R* like standard query optimizer search algorithm, and (4) the run time overhead incurred by the linear algorithms technique is minimal.
The techniques presented in the paper are of general applicability to multi-criterion optimization problems in distributed databases, where each criterion is an additive metric.Technical report lcsr-tr-21
Optimizing queries for coarse grain parallelism
No full textWe consider the problem of optimizing select-project-join relational queries for minimum response time on parallel machines. The design of the optimizer is based on three ideas: (1) the concept and quantification of degree of coarse grain parallelism for an execution tree, (2) the design of a parallelizing scheduler for a tree of coarse grain operations which is provably near optimal, and (3) the analysis of the scheduling algorithm to obtain a cost formula for parallel execution time. The search algorithm of the optimizer is presented as a multi-dimensional dynamic programming algorithm. We present two three- dimensional search algorithms for the case when placement of relations in the parallel machine do not overlap. We propose the tree placement strategy and demonstrate, by means of examples, how the number of dimensions in the search can be significantly reduced, thereby increasing the efficiency of the search algorithm.Technical report lcsr-tr-21
Fast search methods for biological sequence databases
No full textBiology researchers have a pressing need for data management technologies which will make the storage and retrieval of DNA and protein sequence data accurate and efficient. The volume of data generated by DNA sequencing is already massive and will continue to grow rapidly. Even if the current sequence databases are adequate today, they most assuredly will become inadequate in the future when far more sequence data has been determined. The direction of future research in sequence databases needs to be in the organization of information. This is so that the volume of data needing to be searched does not grow linearly with the volume of sequence data being discovered.
We propose to develop an index structure and retrieval system called PROXIMAL for biological sequence databases which promises to be efficient and general. This organization of the databases will complement other current efforts at sequence comparison and analysis, by providing an infrastructure in which other methods can be used to efficiently locate desired sequences. Our method relies on the use of reference strings to partition the database of sequences. It is efficient since the use of multiple reference strings for any given distance measure greatly reduces the number of sequences that must be examined, allowing us to quickly locate sequences based on a precomputed metric. It is general since multiple distance measures can be used. These include at least differing gap and mismatch weights for the basic edit distance calculation, or entirely different models of mutation. The only requirement is that there is a metric structure - mainly, that the calculations satisfy the triangle inequality. This is a weak requirement that is satisfied by many interesting measures, including those currently in wide use for sequence comparison.Technical report LCSR-TR-21
India and the United Kingdom: Finding a New Equilibrium
No full textIndia’s relationship with the United Kingdom (UK) is an unusual one with the legacy of empire both pulling the two states closer and pushing them apart. In the immediate post-1947 period India saw itself in opposition to the larger aims of UK foreign policy. Yet bilateral relations between India and the UK were frequently constructive during the Cold War. The presence of a significant Indian diaspora in the UK adds depth to relations between the states. The UK is receptive to India’s soft power, and vice versa. Individual decision makers including Prime Ministers Nehru, Thatcher, Indira Gandhi and Cameron have tried to make a personal impression on bilateral relations. Longer term systemic changes, especially the end of the Cold War and the post-1991 reforms, facilitated renewed cooperation between India and the UK. Trade increased and the two states formed a strategic partnership
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Politics of utility privatization in India
Full text linktextIn this dissertation I offer an explanation for why Indian states are undertaking economic liberalization at different rates, focusing on reforms to the electricity sector. In the period between 1991 and 2003, India's states restructured their electricity systems to vastly different degrees. The dissertation evaluates three variables that feature prominently in the literature on economic policy change: ideological predilections of governing elites, external pressures like those coming from international financial institutions, and state-society interactions. I argue that it is the last explanation, focusing on the degree to which the potential "losers" from reform dominate state politics--that most compellingly accounts for the unevenness in state-level reforms. In my work, I lay greater analytic weight on the role of rural actors than much of the existing literature on the political economy of market reforms. The primary independent variable that explains this variation in reform outcomes is the organization and political strength of societal actors in each state, particularly rural and industrial constituencies, and middle class interests. In some parts of India, the advent of Green Revolution technologies in the late 1960s meant that farmers--chiefly larger landowners--became the primary beneficiaries of extensive development subsidies, including those for electricity. During India's period of economic liberalization in the 1990s, these beneficiaries constituted the main opponents of privatization, which today threatens to change the rules of the game by allocating resources according to market logics. Given these dynamics, where farm sectors are large or well-organized, reform has not proceeded. In the absence of rural political clout, state elites elected to privatize in order to satisfy industrial and urban constituents and signal the state's openness to private capital inflows. By comparing outcomes across states within the single country of India, the research design can control for some variables that are proposed as determinative of government policy, like electoral institutions and macroeconomic shock. I have selected cases to both capture variation of the dependent variable and control for other plausible explanations, such as ideology, financial crisis, and external pressure.Governmen
Shadow Boxing: How the Risk of Government Intervention Shapes Terrorist Organizational Structures
Full text linkThesis (Ph.D.) - Indiana University, Political Science, 2013For a non-state terrorist group, internal communication and coordination are necessary to maintain organizational control and implement the group's strategy; but this need for interpersonal contact also makes the group vulnerable to disruption by government authorities. How then might these competing demands shape a group's organizational structure? This dissertation will examine how the presence or absence of a safe haven can interact with a group's choice of organizational structure to determine its ability to survive, conduct attacks, and mobilize supporters. Furthermore, it will look at whether and how groups change their organizational structures to adapt to their political environments. To this end, process tracing, the congruence procedure type 2, and cross-case comparison will applied to the cases of four Western, Cold War-era groups (The Provisional Irish Republican Army, The Red Army Faction, The Red Brigades and The Weather Underground) to both identify the critical factors that impact group organizational structure and to explain how these factors exert their influence
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