8,520 research outputs found
Multicommodity Flows in Planar Graphs with Demands on Faces
No full textWe consider the problem of multicommodity flows in planar graphs. Seymour [Seymour, 1981] showed that if the union of supply and demand graphs is planar, then the cut condition is also sufficient for routing demands. Okamura-Seymour [Okamura and Seymour, 1981] showed that if the supply graph is planar and all demands are incident on one face, then again the cut condition is sufficient for routing demands. We consider a common generalization of these settings where the end points of each demand are on the same face of the planar graph. We show that if the source sink pairs on each face of the graph are such that sources and sinks appear contiguously on the cycle bounding the face, then the flow cut gap is at most 3. We come up with a notion of approximating demands on a face by convex combination of laminar demands to prove this result
Dual Half-Integrality for Uncrossable Cut Cover and Its Application to Maximum Half-Integral Flow
No full textGiven an edge weighted graph and a forest F, the 2-edge connectivity augmentation problem is to pick a minimum weighted set of edges, E', such that every connected component of E' ∪ F is 2-edge connected. Williamson et al. gave a 2-approximation algorithm (WGMV) for this problem using the primal-dual schema. We show that when edge weights are integral, the WGMV procedure can be modified to obtain a half-integral dual. The 2-edge connectivity augmentation problem has an interesting connection to routing flow in graphs where the union of supply and demand is planar. The half-integrality of the dual leads to a tight 2-approximate max-half-integral-flow min-multicut theorem
Skeletons and Minimum Energy Scheduling
No full textConsider the problem where n jobs, each with a release time, a deadline and a required processing time are to be feasibly scheduled in a single- or multi-processor setting so as to minimize the total energy consumption of the schedule. A processor has two available states: a sleep state where no energy is consumed but also no processing can take place, and an active state which consumes energy at a rate of one, and in which jobs can be processed. Transitioning from the active to the sleep does not incur any further energy cost, but transitioning from the sleep to the active state requires q energy units. Jobs may be preempted and (in the multi-processor case) migrated.
The single-processor case of the problem is known to be solvable in polynomial time via an involved dynamic program, whereas the only known approximation algorithm for the multi-processor case attains an approximation factor of 3 and is based on rounding the solution to a linear programming relaxation of the problem. In this work, we present efficient and combinatorial approximation algorithms for both the single- and the multi-processor setting. Before, only an algorithm based on linear programming was known for the multi-processor case. Our algorithms build upon the concept of a skeleton, a basic (and not necessarily feasible) schedule that captures the fact that some processor(s) must be active at some time point during an interval. Finally, we further demonstrate the power of skeletons by providing a 2-approximation algorithm for the multiprocessor case, thus improving upon the recent breakthrough 3-approximation result. Our algorithm is based on a novel rounding scheme of a linear-programming relaxation of the problem which incorporates skeletons
sj-pdf-1-lup-10.1177_0961203320918011 - Supplemental material for Nuclear magnetic resonance–based targeted profiling of urinary acetate and citrate following cyclophosphamide therapy in patients with lupus nephritis
No full textSupplemental material, sj-pdf-1-lup-10.1177_0961203320918011 for Nuclear magnetic resonance–based targeted profiling of urinary acetate and citrate following cyclophosphamide therapy in patients with lupus nephritis by Sujata Ganguly, Umesh Kumar, Nikhil Gupta, Anupam Guleria, Sanjukta Majumdar, Sanat Phatak, Smriti Chaurasia, Sandeep Kumar, Amita Aggarwal, Dinesh Kumar and Ramnath Misra in Lupus</p
Bibliographics for the 983 eprints in the live archives of E-LIS : trends and status report up to 7th July 2004, based on author-self-archiving metadata
No full textThe priority for ideas and philosophy related to "Network Theory" have been traced back and documented by Braun(2004),and credit goes to Karinthy(1929).The IT has empowered to realise it, as the most practical phenomena and it is no more a humour. The OAI (Open Archives Initiatives)and ACIS (Academic Contributor Information System)are progressive in the direction ,which may lead to realise the "Collective Genius" at global level. Focus of present study is on Author-Self-Archiving (A-S-A)Metadata of the 983 Eprints in the Live Archives of the E-LIS (EPrints of Library and Information Science),which were approved till 7th July 2004.The A-S-A Metadata was used for librametric analysis. Self-explanatory bibliographics are illustrated.The highlights include: Conference papers (34%); highest approval, June 2004 (28%); published archives (76%);not refereed (52%); not in public domain (60%); highest self-archiving-author (De Robbio, Antonella).The Nos. of EPrints having single JITA domain specifications were: Theoretical and general aspects of libraries and information(27); Information use and sociology of information(80);Users,literacy and reading(13);Libraries as physical collections(30);Publishing and legal issues(57);Management(13);Industry, profession and education(36);Information sources, supports, channels(113) ; Information treatment for information services, Information functions and techniques (101); Technical services libraries, archives and museums(25); Housing technologies(1); Information technology and library technology(92); and Inter-domainery (395) i.e. having specifications of two or more than two JITA classes
A Unified Shell model for Buoyancy-Driven Turbulence
No full textWe construct a unified shell model for stably stratified and convective turbulence. Shell model simulation of stably stratified flow in turbulent regime exhibit Bolgiano-Obukhbov (BO) scaling in which the kinetic energy spectrum varies as . However, simulation of convective turbulence shows Kolmogorov's spectrum. These results are consistent with the direct numerical simulations of Kumar {\em et al.} [Phys. Rev. E {\bf 90}, 023016 (2014)]. We also observe a dual scaling ( and ) for a limited range of parameters in stably stratified flow
A Constant Factor Approximation for Capacitated Min-Max Tree Cover
No full textGiven a graph G = (V,E) with non-negative real edge lengths and an integer parameter k, the (uncapacitated) Min-Max Tree Cover problem seeks to find a set of at most k trees which together span V and each tree is a subgraph of G. The objective is to minimize the maximum length among all the trees. In this paper, we consider a capacitated generalization of the above and give the first constant factor approximation algorithm. In the capacitated version, there is a hard uniform capacity (λ) on the number of vertices a tree can cover. Our result extends to the rooted version of the problem, where we are given a set of k root vertices, R and each of the covering trees is required to include a distinct vertex in R as the root. Prior to our work, the only result known was a (2k-1)-approximation algorithm for the special case when the total number of vertices in the graph is kλ [Guttmann-Beck and Hassin, J. of Algorithms, 1997]. Our technique circumvents the difficulty of using the minimum spanning tree of the graph as a lower bound, which is standard for the uncapacitated version of the problem [Even et al.,OR Letters 2004] [Khani et al.,Algorithmica 2010]. Instead, we use Steiner trees that cover λ vertices along with an iterative refinement procedure that ensures that the output trees have low cost and the vertices are well distributed among the trees
sj-pdf-1-ajs-10.1177_03635465231180323 – Supplemental material for Efficacy and Safety of Stempeucel in Osteoarthritis of the Knee
No full textSupplemental material, sj-pdf-1-ajs-10.1177_03635465231180323 for Efficacy and Safety of Stempeucel in Osteoarthritis of the Knee by Pawan Kumar Gupta, Sunil Maheshwari, Joe Joseph Cherian, Vijay Goni, Arun Kumar Sharma, Sujith Kumar Tripathy, Keerthi Talari, Vivek Pandey, Parag Kantilal Sancheti, Saurabh Singh, Syamasis Bandyopadhyay, Naresh Shetty, Surendra Umesh Kamath, Purohit Sharad Prahaldbhai, Jijy Abraham, Suresh Kannan, Samatha Bhat, Shivashankar Parshuram, Vinayaka Shahavi, Akhilesh Sharma, Nikhil N. Verma and Uday Kumar in The American Journal of Sports Medicine</p
sj-docx-2-pie-10.1177_09544089221084802 - Supplemental material for Effect of electrode negativity ratio and heat input on bead and arc characteristics in submerged arc welding
No full textSupplemental material, sj-docx-2-pie-10.1177_09544089221084802 for Effect of electrode negativity ratio and heat input on bead and arc characteristics in submerged arc welding by Ajit Kumar Naik, Rakesh Roshan, Kanwer Singh Arora, Nikhil Shajan and Subash Chandra Mishra in Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering</p
sj-docx-1-pie-10.1177_09544089221084802 - Supplemental material for Effect of electrode negativity ratio and heat input on bead and arc characteristics in submerged arc welding
No full textSupplemental material, sj-docx-1-pie-10.1177_09544089221084802 for Effect of electrode negativity ratio and heat input on bead and arc characteristics in submerged arc welding by Ajit Kumar Naik, Rakesh Roshan, Kanwer Singh Arora, Nikhil Shajan and Subash Chandra Mishra in Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering</p
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