428 research outputs found
Improved Approximation Algorithm for <em class="EmphasisTypeItalic">k</em>-level Uncapacitated Facility Location Problem (with Penalties)
No full textWe study the k-level uncapacitated facility location problem (k-level UFL) in which clients need to be connected with paths crossing open facilities of k types (levels). In this paper we first propose an approximation algorithm that for any constant k, in polynomial time, delivers solutions of cost at most αk times OPT, where αk is an increasing function of k, with limk→∞αk=3. Our algorithm rounds a fractional solution to an extended LP formulation of the problem. The rounding builds upon the technique of iteratively rounding fractional solutions on trees (Garg, Konjevod, and Ravi SODA’98) originally used for the group Steiner tree problem. We improve the approximation ratio for k-level UFL for all k ≥ 3, in particular we obtain the ratio equal 2.02, 2.14, and 2.24 for k = 3,4, and 5. Second, we give a simple interpretation of the randomization process (Li ICALP’2011) for 1-level UFL in terms of solving an auxiliary (factor revealing) LP. Armed with this simple view point, we exercise the randomization on our algorithm for the k-level UFL. We further improve the approximation ratio for all k ≥ 3, obtaining 1.97, 2.09, and 2.19 for k = 3,4, and 5. Third, we extend our algorithm to the k-level UFL with penalties (k-level UFLWP), in which the setting is the same as k-level UFL except that the planner has the option to pay a penalty instead of connecting chosen clients.</p
Heterogeneity, distribution, and cooperation in common property resource management
No full textThe report considers the role of group heterogeneity in the success or failure of common property resource management. The author argues that cooperative agreements are less likely to come about when agents are highly heterogeneous along relevant dimensions - and existing agreements are more likely to break down as a group becomes more heterogeneous. The author crystallizes his argument in simple numerical examples and illustrates by reference to case studies on common property resource management, in particular, cases involving fisheries and irrigation systems. More work is needed to substantiate the author's argument, but his analysis so far supports the argument that equity and efficiency complement rather than oppose each other.Agricultural Research,Agricultural Knowledge&Information Systems,Poverty Assessment,Common Property Resource Development,Environmental Economics&Policies
The value of intra-household survey data for age-based nutritional targeting
No full textThe object of this paper has been, first to develop a framework for upper-limit indicator targeting, and to illustrate it for age based targeting of nutrition interventions using data from the Philippines. Second, the authors provide quantitative estimates of the value of individual level information and of knowledge of the intra-household allocation of calories. For the sample, age proved to be a good indicator of undernutrition. However, this was not the case with household level calorie adequacy which rendered age less useful as a targeting instrument, at an often considerable calorie cost. Food sharing, on the other hand, truly rendered age less helpful as a targeting instrument because of within-household leakage. The authors conclude that the design of nutrition interventions can be very susceptible to the level of aggregation of available information. This is consistent with findings that while poverty or undernutrition rankings of groups defined on household level characteristics were not sensitive to the level of aggregation, the rankings of groups defined on individual characteristics were very sensitive. Perhaps the costs of collection of these intra-household data outweigh the benefits, but the experiments in this paper begin to answer questions about the costs of not collecting them.Poverty Lines,Youth and Governance,Science Education,Scientific Research&Science Parks,Health Monitoring&Evaluation
Children and intra-household inequality : a theoretical analysis
No full textArguing that resources within the household are not allocated according to need, several researchers have tried to model intra-household allocative behavior. One group (1990) argued that as households become better off, intra-household inequality first increases then decreases. The behavior of intra-household inequality as household welfare improves is clearly important for policy, as interventions are often restricted to the household level - although the objective is to improve the welfare of the least-well-off individual. The author shows here that many of the tractable derivations of intra-household resource allocation are available in what might be called the"linear expenditure systems"framework. He analyzes the relationship between intra-household inequality and total household resources for models of intra-household allocation that lead to a linear expenditure reduced form. He then investigates three structural models : household welfare maximization; cooperative bargaining; and a noncooperative game with children as public goods. The author indicates how these models should be modified to produce reduced forms that are better represented in the evidence.Urban Housing,Poverty Lines,Environmental Economics&Policies,Inequality,Housing&Human Habitats
Quality of Evaluation Extruded Snacks.
No full textThis Dissertation / Report is the outcome of investigation carried out by the creator(s) / author(s) at the department/division of Central Food Technological Research Institute (CFTRI), Mysore mentioned below in this page
Experience report: Scala collections
No full textWe report on our experiences in redesigning Scala's collection libraries, focussing on the role that type systems play in keeping software architectures coherent over time. Type systems can make software architecture more explicit but, if they are too weak, can also cause code duplication. We show that code duplication can be
avoided using two of Scala's type constructions: higher-kinded types and implicit parameters and conversions.sponsorship: The second author (Adriaan Moors) is supported by a grant from the Flemish IWT.status: Publishe
Indian summer monsoon simulations in successive generations of the NCAR Community Atmosphere Model
No full textFour generations of the NCAR Community Atmosphere Model (CAM3, 4, 5, and 6) are used to assess model upgrades to the Indian summer monsoon rainfall (ISMR) simulations. The total precipitation simulation in CAM3 is significantly overestimated over the western equatorial Indian Ocean, Arabian Sea, and southwest Bay of Bengal (BoB), and underestimated over the northern BoB due to overestimated convective and underestimated large-scale precipitation, respectively. In the subsequent CAM versions, the simulation of total precipitation has improved, except for the wet bias over the Western Ghats and Himalayan foothills, which has deteriorated due to increased convective and large-scale precipitation, respectively. The improvement in total precipitation simulation over the northern BoB is found in successive CAM versions from the increased heating and drying of the troposphere. CAM3 overestimates the frequency of low precipitation rates and underestimates the frequency of high precipitation rates, which is improved in CAM4, but deteriorated further in subsequent CAM versions. The model development cycle from CAM3 to CAM6 also led to a substantial improvement in most ISMR-associated circulation features, except for the successive overestimation in the low-level monsoon jet due to a strengthened easterly shear of zonal wind. The simulation of subtropical westerly and tropical easterly jets has become more reliable in subsequent CAM versions. In addition, we find successive improvements in the monsoon intra-seasonal oscillation (MISO), associated internal dynamics, and the east-west and north-south heat source. However, some important biases (e.g., the eastward component of MISO, monsoon low-level jet, excessive precipitation over Himalayan foothills, early monsoon onset) need to be alleviated for more realistic ISM simulations by improving further the cloud microphysical and moist processes in the future CAM versions.This work is partly supported by the DST Centre of Excellence in Climate Modeling at IIT Delhi and through a DST Science and Engineering Research Board (SERB) project (ECR/2015/000229). Ravi Kumar acknowledges the MTech fellowship from MHRD. The authors wish to acknowledge NCAR’s climate modeling section (http://www.cgd.ucar.edu/) for developing CAM3, CAM4, CAM5, and CAM6 models. We are thankful to TRMM (https://pmm.nasa.gov/trmm) and ECMWF (https://www.ecmwf.int/en/forecasts/datasets/) for providing the necessary observational and reanalysis datasets publicly. The IITD supercomputing facility is used for computations. NCAR-NCL is used for data analysis, and the climate data operator is used for data processing
CONCEPTUAL CHALLENGES IN POVERTY AND INEQUALITY:ONE DEVELOPMENT ECONOMIST'S PERSPECTIVE
No full textThe last thirty years in the analysis of inequality and poverty, especially in developing countries, has seen two phases-a phase of conceptual advancement, followed by a phase of application and policy debate. Both phases were exciting and useful in their own way, but the applied phase has significantly exhausted the potential of the conceptual advances of two decades ago, and new advances have been few and far between. However, there is now a need, and an opening, for a new phase of conceptual advances, advances that will make use of shifting methodological terrain in mainstream economics, and that will answer emerging policy questions that would otherwise have no easy answers (or, perhaps, too easy answers).Food Security and Poverty,
Determining Carrier Mobilities in GaAs and Natural Pyrite Using Geometrical Magnetoresistance Measurement
No full textabstract: Measurements of the geometrical magnetoresistance of a conventional semiconductor, gallium arsenide (GaAs), and a more recently developed semiconductor, iron pyrite (FeS2) were measured in the Corbino disc geometry as a function of magnetic field to determine the carrier mobility (μm). These results were compared with measurements of the Hall mobility (μH) made in the Van der Pauw configuration. The scattering coefficient (ξ), defined as the ratio between magnetoresistance and Hall mobility (μm/μH), was determined experimentally for GaAs and natural pyrite from 300 K to 4.2 K. The effect of contact resistance and heating on the measurement accuracy is discussed.Dissertation/ThesisMasters Thesis Materials Science and Engineering 201
The use of dynamic networks in scheduling flexible manufacturing systems
No full textFlexible Manufacturing Systems have developed recently to allow companies to compete in a global market. One problem arising from such systems is the optimal scheduling of the jobs through the system. There is much discussion as to what this problem should be, but it is agreed that it is a hard problem.This thesis deals with the scheduling problem as defined by Stecke as problems concerning the running of an FMS once it has been set up during a planning phase. Numerous techniques have been proposed to solve this problem.If the problem is static, various queueing models may be used. However, in a dynamic environment these models fail. Mathematical programming models allow for the dynamic environment, but rapidly increase in calculation requirements due to the need for integer answers. Simulation, hierarchical, and expert systems try to address this problem, but don't allow for optimal solutions.The use of a dynamic network model had been considered in the past, but rejected for various reasons. The thrust of this thesis is that these networks can be used and are a computationally feasible technique for finding optimal solutions to the FMS scheduling problem. In order to develop this concept, the basic dynamic network models originally proposed by Maxwell & Wilson needed to be expanded and modified.By incorporating the concepts of limited entry queues and micromodels of resources, a dynamic network model of an FMS can be developed and solved by efficient network flow techniques.Made available in DSpace on 2011-05-07T13:24:13Z (GMT). No. of bitstreams: 2
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