scholarly journals Analysis of Memory Footprints of Sparse Matrices Partitioned Into Uniformly-Sized Blocks

2018 ◽  
Vol 19 (3) ◽  
pp. 275-292
Author(s):  
Daniel Langr ◽  
Ivan Šimeček
Keyword(s):  
Lower Bounds ◽  
Sparse Matrices ◽  
Worst Case ◽  
Wide Range ◽  
Block Sizes

The presented study analyses memory footprints of 563 representative benchmark sparse matrices with respect to their partitioning into uniformly-sized blocks. Different block sizes and different ways of storing blocks in memory are considered and statistically evaluated. Memory footprints of partitioned matrices are then compared with their lower bounds and CSR, index-compressed CSR, and EBF storage formats. The results show that blocking-based storage formats may significantly reduce memory footprints of sparse matrices arising from a wide range of application domains. Additionally, measured consistency of results is presented and discussed, benefits of individual formats for storing blocks are evaluated, and an analysis of best-case and worst-case matrices is provided for in-depth understanding of causes of memory savings of blocking-based formats.

scholarly journals Lower Bounds for Dynamic Algebraic Problems

1998 ◽  
Vol 5 (11) ◽  
Author(s):  
Gudmund Skovbjerg Frandsen ◽  
Johan P. Hansen ◽  
Peter Bro Miltersen
Keyword(s):  
Fourier Transform ◽  
Lower Bound ◽  
Lower Bounds ◽  
Communication Complexity ◽  
Symmetric Functions ◽  
Matrix Multiplication ◽  
Worst Case ◽  
Dynamic Matrix ◽  
Wide Range ◽  
On Line

We consider dynamic evaluation of algebraic functions (matrix multiplication, determinant, convolution, Fourier transform, etc.) in the model of Reif and Tate; i.e., if f(x1, . . . , xn) = (y1, . . . , ym) is an algebraic problem, we consider serving on-line requests of the form "change input xi to value v" or "what is the value of output yi?". We present techniques for showing lower bounds on the worst case time complexity per operation for such problems. The first gives lower bounds in a wide range of rather powerful models (for instance history dependent<br />algebraic computation trees over any infinite subset of a field, the integer RAM, and the generalized real RAM model of Ben-Amram and Galil). Using this technique, we show optimal  Omega(n) bounds for dynamic matrix-vector product, dynamic matrix multiplication and dynamic discriminant and an <br />Omega(sqrt(n)) lower bound for dynamic polynomial multiplication (convolution), providing a good match with Reif and<br />Tate's O(sqrt(n log n)) upper bound. We also show linear lower bounds for dynamic determinant, matrix adjoint and matrix inverse and an Omega(sqrt(n)) lower bound for the elementary symmetric functions. The second technique is the communication complexity technique of Miltersen, Nisan, Safra, and Wigderson which we apply to the setting<br />of dynamic algebraic problems, obtaining similar lower bounds in the word RAM model. The third technique gives lower bounds in the weaker straight line program model. Using this technique, we show an ((log n)2= log log n) lower bound for dynamic discrete Fourier transform. Technical ingredients of our techniques are the incompressibility technique of Ben-Amram and Galil and the lower bound for depth-two superconcentrators of Radhakrishnan and Ta-Shma. The incompressibility technique is extended to arithmetic computation in arbitrary fields.

A New Type of Gas Turbine Based-Hybrid Propulsion System: Part 1—Concept Development, Definition of Mission Parameters and Preliminary Sizing

2000 ◽  
Author(s):  
Emiliano Cioffarelli ◽  
Enrico Sciubba
Keyword(s):  
Gas Turbine ◽  
Combustion Engine ◽  
Development Program ◽  
Propulsion System ◽  
Medium Size ◽  
Passenger Cars ◽  
Worst Case ◽  
Hybrid Propulsion ◽  
Wide Range ◽  
Definition Of

Abstract A hybrid propulsion system of new conception for medium-size passenger cars is described and its preliminary design developed. The system consists of a turbogas set operating at fixed rpm, and a battery-operated electric motor that constitutes the actual “propulsor”. The battery pack is charged by the thermal engine which works in an electronically controlled on/off mode. Though the idea is not entirely new (there are some concept cars with similar characteristics), the present study has important new aspects, in that it bases the sizing of the thermal engine on the foreseen “worst case” vehicle mission (derived from available data on mileage and consumption derived from road tests and standard EEC driving mission cycles) that they can in fact be accomplished, and then proceeds to develop a control strategy that enables the vehicle to perform at its near–peak efficiency over a wide range of possible missions. To increase the driveability of the car, a variable-inlet vane system is provided for the gas turbine. After developing the mission concept, and showing via a thorough set of energy balances (integrated over various mission profiles), a preliminary sizing of the turbogas set is performed. The results of this first part of the development program show that the concept is indeed feasible, and that it has important advantages over both more traditional (Hybrid Vehicles powered by an Internal Combustion Engine) and novel (All-Electric Vehicle) propulsion systems.

South Africa at a Turning Point?

2015 ◽  
Vol 53 (3) ◽  
pp. 477-486 ◽  
Author(s):  
Elke Zuern
Keyword(s):  
South Africa ◽  
Turning Point ◽  
Case Scenario ◽  
State Collapse ◽  
Worst Case ◽  
South Africans ◽  
Nelson Mandela ◽  
Wide Range ◽  
Electricity Provision

South Africa is at a crossroads. The state has not adequately addressed dire human development needs, often failing to provide the services it constitutionally guarantees. As a result, citizens are expressing their frustrations in a variety of ways, at times including violence. These serious challenges are most readily apparent in poverty, inequality and unemployment statistics, but also in electricity provision, billing and affordability as well as a recent spate of racially motivated attacks which highlight the tension both among South Africans and between South Africans and darker skinned foreigners. The country has, however, been on the brink before and avoided the worst-case scenario of full-scale civil war and state collapse. Far too often South Africa's past successes have been attributed to the role of one man, Nelson Mandela. While Mandela was indeed an extraordinary human being who rightly deserved the international awards and accolades as well as the deep admiration of so many, South Africa's triumphs as a society and a state are the product of both cooperative and conflicting contributions by a wide range of actors. A central question at the present juncture is how well equipped domestic actors and institutions are to address the crisis. The following pages seek to provide some insights and through the perspectives of three authors to consider causes and possible responses.

Limit pressure for a spherical vessel with a circumferential slot at its junction with a radial cylindrical protruding branch

1987 ◽  
Vol 22 (4) ◽  
pp. 215-227 ◽  
Author(s):  
M Robinson ◽  
C S Lim ◽  
R Kitching
Keyword(s):  
Spherical Shell ◽  
Lower Bounds ◽  
Yield Criterion ◽  
Spherical Vessel ◽  
Non Linear Programming ◽  
Limit Pressure ◽  
Wide Range ◽  
Cylindrical Branch ◽  
Von Mises ◽  
Plastic Limit Pressure

One of the requirements of the two criteria method of safety assessment of a pressure vessel with a defect is an estimate of the plastic limit pressure. Here the defect is in a spherical shell close to its junction with a protruding radial cylindrical branch. The defect is assumed to be an axisymmetric circumferential slot of uniform depth on the outer surface of the shell. Lower bounds to the limit pressure are calculated for a wide range of geometries. The material is assumed to obey the von Mises yield criterion and a non-linear programming method is used to give optimum lower bounds. Data is supplied for spherical shell radius to thickness ratios from 25 to 100, nozzle radius to vessel radius ratios from 0 to 0.4, nozzle to vessel thickness ratios from 0.25 to 1.0 and ligament thickness to vessel thicknesses (ligament efficiencies) of 0 to 1. Slot widths vary from the significant to the infinitesimal, where it becomes a crack. Vessels of some proportions were shown to have their limit pressures reduced only a little by very low ligament efficiencies.

scholarly journals Lower Bounds for Dynamic Transitive Closure, Planar Point Location, and Parentheses Matching

1996 ◽  
Vol 3 (9) ◽  
Author(s):  
Thore Husfeldt ◽  
Theis Rauhe ◽  
Søren Skyum
Keyword(s):  
Lower Bound ◽  
Lower Bounds ◽  
Transitive Closure ◽  
Unit Cost ◽  
Random Access ◽  
Point Location ◽  
Worst Case ◽  
Planar Point ◽  
Planar Point Location ◽  
Prefix Sums

We give a number of new lower bounds in the cell probe model<br />with logarithmic cell size, which entails the same bounds on the random access computer with logarithmic word size and unit cost operations. We study the signed prefix sum problem: given a string of length n of zeroes and signed ones, compute the sum of its ith prefix during updates. We show a<br />lower bound of  Omega(log n/log log n) time per operations, even if the prefix sums are bounded by log n/log log n during all updates. We also show that if the update time is bounded by the product of the worst-case update time and the<br />answer to the query, then the update time must be Omega(sqrt(log n/ log log n)).<br /> These results allow us to prove lower bounds for a variety of seemingly unrelated<br />dynamic problems. We give a lower bound for the dynamic planar point location in monotone subdivisions of <br />Omega(log n/ log log n) per operation. We give<br />a lower bound for the dynamic transitive closure problem on upward planar graphs with one source and one sink of <br />Omega(log n/(log logn)^2) per operation. We give a lower bound of  Omega(sqrt(log n/log log n)) for the dynamic membership problem of any Dyck language with two or more letters. This implies the same<br />lower bound for the dynamic word problem for the free group with k generators. We also give lower bounds for the dynamic prefix majority and prefix equality problems.

scholarly journals Chronic Kidney Disease Prediction using Machine Learning Models

2019 ◽  
Vol 9 (1) ◽  
pp. 6364-6367
Keyword(s):  
Machine Learning ◽  
Chronic Kidney Disease ◽  
Kidney Disease ◽  
Kidney Failure ◽  
Bone Diseases ◽  
Machine Learning Algorithms ◽  
Knowledge Generation ◽  
Good Prediction ◽  
Worst Case ◽  
Wide Range

The field of biosciences have advanced to a larger extent and have generated large amounts of information from Electronic Health Records. This have given rise to the acute need of knowledge generation from this enormous amount of data. Data mining methods and machine learning play a major role in this aspect of biosciences. Chronic Kidney Disease(CKD) is a condition in which the kidneys are damaged and cannot filter blood as they always do. A family history of kidney diseases or failure, high blood pressure, type 2 diabetes may lead to CKD. This is a lasting damage to the kidney and chances of getting worser by time is high. The very common complications that results due to a kidney failure are heart diseases, anemia, bone diseases, high potasium and calcium. The worst case situation leads to complete kidney failure and necessitates kidney transplant to live. An early detection of CKD can improve the quality of life to a greater extent. This calls for good prediction algorithm to predict CKD at an earlier stage . Literature shows a wide range of machine learning algorithms employed for the prediction of CKD. This paper uses data preprocessing,data transformation and various classifiers to predict CKD and also proposes best Prediction framework for CKD. The results of the framework show promising results of better prediction at an early stage of CKD

scholarly journals Feature Recognition for Manufacturability Analysis

1994 ◽  
Author(s):  
William C. Regli ◽  
Satyandra K. Gupta ◽  
Dana S. Nau
Keyword(s):  
Time Complexity ◽  
Material Removal ◽  
Feature Recognition ◽  
Solid Modeling ◽  
Cad Model ◽  
Worst Case ◽  
Machining Features ◽  
Automated Recognition ◽  
Wide Range ◽  
Complete Set

Abstract While automated recognition of features has been attempted for a wide range of applications, no single existing approach possesses the functionality required to perform manufacturability analysis. In this paper, we present a methodology for taking a CAD model of a part and extracting a set of machinable features that contains the complete set of alternative interpretations of the part as collections of MRSEVs (Material Removal Shape Element Volumes, a STEP-based library of machining features). The approach handles a variety of features including those describing holes, pockets, slots, and chamfering and filleting operations. In addition, the approach considers accessibility constraints for these features, has an worst-case algorithmic time complexity quadratic in the number of solid modeling operations, and modifies features recognized to account for available tooling and produce more realistic volumes for manufacturability analysis.

Analysis of Service Compatibility

2010 ◽  
pp. 136-155
Author(s):  
Ken Q. Pu
Keyword(s):  
Relational Database ◽  
Type System ◽  
Large Family ◽  
Service Description ◽  
Worst Case ◽  
Database Queries ◽  
Unification Algorithm ◽  
Data Services ◽  
Wide Range ◽  
Unification Problem

In this chapter, the authors apply type-theoretic techniques to the service description and composition verification. A flexible type system is introduced for modeling instances and mappings of semi-structured data, and is demonstrated to be effective in modeling a wide range of data services, ranging from relational database queries to web services for XML. Type-theoretic analysis and verification are then reduced to the problem of type unification. Some (in)tractability results of the unification problem and the expressiveness of their proposed type system are presented in this chapter. Finally, the auhtors construct a complete unification algorithm which runs in EXP-TIME in the worst case, but runs in polynomial time for a large family of unification problems rising from practical type analysis of service compositions.

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