182 research outputs found
A new balloon dissector for totally extraperitoeneal hernia repair
No full textBackground: Balloon dissectors (BD) find their use in totally extraperitoneal (TEP) and retroperitoneoscopic procedures. Commercial BD is prohibitively expensive. The author uses an indigenously assembled BD and describes the same. Material and Methods: The author assembles the BD by tying glove-fingers on an NG tube and then tying this assembly in the concavity of a Kelly′s clamp, premounted with peanut gauze (KC-BD). Results: The author has used it in the last 75 cases of TEP. A large working space is created, without any iatrogenic injuries or balloon rupture. This cheap indigenous BD can be assembled easily and in no time at all. Conclusions: KC-BD offers several advantages because of its unique design. It is effective, totally nontraumatic, inexpensive, and easy to assemble
Techniques for the performance analysis of queueing networks
No full textETDs are only available to UIUC Users without author permissionU of I OnlyAnalyzing the performance of queueing networks that do not admit a product form solution is a challenging problem. In this thesis we present some tools for doing so. Our attention is restricted to Markovian queueing networks.We first present a technique for bounding the performance of such networks. Assuming a steady state for functionals of the state, we obtain linear programs which bound the performance. This technique is illustrated using quadratic functionals to bound the performance of a class of Markovian queueing networks called reentrant lines. We also show how this technique may be applied to bound throughput and blocking probabilities in networks with buffer capacity constraints. In some cases bounds obtained using multimedial functional of the state are shown to approach the exact value when the degree of the multimedial increases.We also study another important technique for the analysis of queueing networks, namely, the fluid limit approach. This approach is used to establish the stability of a class of policies called Fluctuation Smoothing policies for open reentrant lines. We also show how the fluid limit approach can be used to obtain the asymptotic performance of closed queueing networks in heavy traffic. We then use fluid limits to establish the efficiency of Fluctuation Smoothing policies for closed reentrant lines, as well as the Harrison-Wein policy for two station closed reentrant lines.Made available in DSpace on 2011-05-07T14:22:46Z (GMT). No. of bitstreams: 2
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Efficient uniformly convergent numerical methods for singularly perturbed parabolic reaction–diffusion systems with discontinuous source term
No full textFinanciación de acceso abierto proporcionada por los Fondos Europeos FEDER y la Junta de Castilla y León en el marco de la Estrategia de Investigación e Innovación para la Especialización Inteligente (RIS3) de Castilla y León 2021-2027[EN] This article is concerned with the construction and analysis of efficient uniformly convergent methods for a class of parabolic systems of coupled singularly perturbed reaction–diffusion problems with discontinuous source term. Due to the discontinuity in the source term, the solution to this problem exhibits interior layers along with boundary layers, which are overlapping and interacting in nature. To achieve an efficient numerical solution for the coupled system under consideration, at interior points (excluding the interface point) we employ a special finite difference scheme in time (where the components of the approximate solution are decoupled at each time level) and the central difference scheme in space; for mesh points on the interface, a special finite difference scheme decoupling the components of the approximate solution is developed. A rigorous error analysis is provided, establishing the method’s uniform convergence. In terms of computational cost, our numerical methods are more efficient than existing approaches for solving this class of problems. Finally, we provide numerical results to substantiate the theory and showcase the efficiency of our methods.The first author expresses gratitude to the Indian Institute of Technology (BHU) for
the assistance provided during the work tenure. Sunil Kumar extends thanks to the Science and Engineering
Research Board (SERB) for awarding the research support grant CRG/2023/003228 for this work
Endoscopic diagnosis, management and outcome of gastroduodenal tuberculosis
No full textCurrent guidelines for gastroduodenal tuberculosis suggest that surgery in conjunction with anti-tubercular therapy (ATT) is the primary therapy. We determined the efficacy of endoscopic balloon dilatation along with ATT as the primary treatment for this condition. Patients with gastric outlet obstruction at endoscopy seen over a two-year period underwent multiple biopsies from the involved area. Those in whom mucosal biopsy revealed non-specific inflammation, underwent endoscopic mucosal resection (EMR). Patients showing granulomatous inflammation with/without acid-fast bacilli (AFB) underwent endoscopic balloon dilatation under fluoroscopic guidance along with ATT. End point of dilatation was taken as dilatation with 18 mm balloon. The time taken to resume normal diet post endotherapy was determined. Thirteen patients were diagnosed to have gastroduodenal tuberculosis. Granulomatous inflammation with or without demonstration of AFB was documented in 92 % of the patients by endoscopic biopsy and EMR. Endoscopic balloon dilatation of the strictures was successful in 11/12 patients (92 %); these patients could resume their normal diet at a median of 11 days (range 7-60) post-dilatation. Retroperitoneal perforation in 1 patient was managed conservatively. Endoscopic therapy in combination with ATT is recommended as the first line therapy for gastroduodenal tuberculosis. Surgical intervention is reserved for the minority in whom endoscopic therapy fails.Amarender Singh Puri, Sanjeev Sachdeva, Vibhu Vibhas Mittal, Nitin Gupta, Ameet Banka, Puja Sakhuja, Sunil Kumar Pur
Two approaches to the hierarchical solution of constraint satisfaction problems
No full textConstraint Satisfaction Problems (CSPs) involve assigning values to a finite set of variables from their finite domains such that a finite set of constraints is satisfied. Graph coloring, Scheduling and Time-table design are some of the commonly occurring CSPs. All general solution procedures for CSPs are based upon a combinatorial enumeration of variable bindings, with the addition of clever devices to reduce the number of nodes explored in the corresponding search tree. CSPs, however, are NP-hard, and general-purpose search algorithms are slow. This research explores the application of problem decomposition to construct faster CSP solvers
Previous applications of Problem Decomposition to CSPs have been based upon the representation of a CSP as a Constraint Graph, where nodes represent variables, and arcs represent constraints. A tree-shaped constraint graph, after some preprocessing on the nodes, can be solved without backtrack (Freuder, 82). Researchers have proposed different methods for reducing a constraint graph into a tree of node-clusters, with the cost of solution dependent on the size of the largest such cluster.
Tree-clustering based methods of decomposition fail on CSPs with global constraints, where any cluster including the global constraint has to include all the problem's variables. This thesis proposes reducing redundant constraint-checks as an alternative motivation for problem decomposition in CSPs. The decomposition algorithms developed here are applicable to CSPs unrestricted on constraint arity.
There are three major components to this research. The first is the development of a framework, named bottom-up solution, for solving a CSP through its decomposition. It is aimed at handling decompositions that do not completely partition a problem into independent components. The framework allows for the efficient handling of problem components dependent upon other subproblems. The bottom-up solution framework has been implemented on top of the basic Backtrack and Forward-Check search algorithms.
The thesis then introduces two problem decomposition algorithms aimed directly at reducing redundant constraint checks. The main insight here is that redundant constraint tests are caused by artificial dependencies of constraints on non-argument variables, set up by the serial nature of combinatorial enumeration used as the basis for search algorithms. The decomposition algorithms seek to reduce artificial dependencies in a problem, and the resulting decompositions can be solved in the bottom-up solution framework.
The third component of this thesis focuses on global and high-arity constraints. The complexity of a class of problems with a particular constraint topology is defined by the highest arity of its constraint set. This is reflected in the inability of search algorithms to take advantage of global constraints to reduce the size of the explored search space. This thesis proposes a procedure for the syntactic decomposition of a global constraint in a problem. This decomposition is used to define an abstract problem layer, and a new hierarchical problem which is equivalent to the original problem, and in which the global constraint is replaced with a set of smaller arity constraints.
The problem decomposition techniques are evaluated on random problems and on some sample application domains. In general the decomposition is shown to be more beneficial for problems which, when solved in their original form, exhibit high artificial serial dependencies and produce bushier search trees. Global constraint decomposition is demonstrated on some sample application domains, and shown to significantly reduce search effort.
Constraint satisfaction problems are difficult enough that there do not exist any reliable and effective general purpose problem solving heuristics and evaluation functions. It is therefore significant that the DOI decomposition algorithm proposed in this research is guaranteed never to make the problem harder to solve.
The primary contribution of this research is in the form of new problem solving methods for general constraint satisfaction problems which significantly improve performance, particularly for harder problems. It also extends the current understanding of what makes constraint satisfaction problems difficult to solve and where search algorithms spend their effort. On the more general side, this thesis promotes a deeper understanding of the application and benefits of problem decomposition as a problem solving strategy.Technical report LCSR-TR-25
Pattern of Cancer in Nepal from 2003 to 2011
No full textCorrection: On 15th January 2017, the authors Sunil Kumar Sah and Naval Kishor Yadav were added to the author list.Cancer is global burden of disease in developed and developing countries. It is one of the main causes of death. The environmental factor and life styles are major causes of cancer.This hospital based retrospective study was carried out using data retrieved from the register maintained at seven cancer centers. The most common basis of diagnosis were microscopic (histopathological and cytopathological examination). The diagnosis was also based on clinical examination, radiological examination, endoscopy, biochemical and immunological tests.Most of the cancer cases were diagnosed at BPKMCH (23908) followed by BPKIHS (9668) and BH (5959) and few cases from KCH (518) in 2003 to 2011. The total number of cancer cases were increasing from 2003 to 2011 and it become double in 2011. Out of 75 district of Nepal, more number of cancer cases was found in Kathmandu, Sunsari, Morang, Chitwan, Lalitpur, Jhapa, Kaski, Nawalparasi, Rupendehi and Kavrepalchowk in 2010. Similarly, in 2011 more number of cancer cases was found in Kathmandu, Morang, Jhapa, Sunsari, Chitwan, Lalitpur, Rupendehi, Kaski, Saptari, Bhaktapur. Lung cancer was the common cancer and similarly, other prevalent cancers were cervical, breast, stomach, ovarian and colo-rectum cancer in 2003 to 2011. The common cancers were lung, cervical, breast, stomach, ovarian and colo-rectum. The number of patients is increasing, which may be due to change in life style and lack of education
Plane Strain Deformation In Thermoelastic Microelongated Solid
No full textThe purpose of this paper is to study the two dimensional deformation in a thermoelastic microelongated solid. A mechanical force is applied along the interface of fluid half space and thermoelastic microelongated half space. The normal mode analysis has been applied to obtain the exact expressions for displacement component, force stress and temperature distribution. The effect of microelongation on the displacement component, force stress and temperature distribution has been depicted graphically for Green-Lindsay (GL) theory of thermoelasticity. Keywords: Thermoelasticity, Microelongation, Normal mode analysis
A new balloon dissector for totally extraperitoeneal hernia repair
No full textBackground: Balloon dissectors (BD) find their use in totally
extraperitoneal (TEP) and retroperitoneoscopic procedures. Commercial
BD is prohibitively expensive. The author uses an indigenously
assembled BD and describes the same. Material and Methods: The author
assembles the BD by tying glove-fingers on an NG tube and then tying
this assembly in the concavity of a Kelly′s clamp, premounted
with peanut gauze (KC-BD). Results: The author has used it in the last
75 cases of TEP. A large working space is created, without any
iatrogenic injuries or balloon rupture. This cheap indigenous BD can be
assembled easily and in no time at all. Conclusions: KC-BD offers
several advantages because of its unique design. It is effective,
totally nontraumatic, inexpensive, and easy to assemble
A two dimensional fibre reinforced micropolar thermoelastic problem for a half-space subjected to mechanical force
No full textThe purpose of this paper is to study the two dimensional deformation of
fibre reinforced micropolar thermoelastic medium in the context of
Green-Lindsay theory of thermoelasticity. A mechanical force is applied
along the interface of fluid half space and fibre reinforced micropolar
thermoelastic half space. The normal mode analysis has been applied to
obtain the exact expressions for displacement component, force stress,
temperature distribution and tangential couple stress. The effect of
anisotropy and micropolarity on the displacement component, force stress,
temperature distribution and tangential couple stress has been depicted
graphically
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