A heuristic homotopic path simplification algorithm

, Article Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 20 June 2011 through 23 June 2011 ; Volume 6784 LNCS, Issue PART 3 , June , 2011 , Pages 132-140 ; 03029743 (ISSN) ; 9783642219306 (ISBN) Daneshpajouh, S ; Ghodsi, M ; Sharif University of Technology

2011

Abstract

We study the well-known problem of approximating a polygonal path P by a coarse one, whose vertices are a subset of the vertices of P. In this problem, for a given error, the goal is to find a path with the minimum number of vertices while preserving the homotopy in presence of a given set of extra points in the plane. We present a heuristic method for homotopy-preserving simplification under any desired measure for general paths. Our algorithm for finding homotopic shortcuts runs in O( mlog(n + m) + nlogn log(nm) + k) time, where k is the number of homotopic shortcuts. Using this method, we obtain an O(n 2 + mlog(n + m) + nlogn log(nm)) time algorithm for simplification under the Hausdorff...

A note on the minimum interval cost flow problem

, Article Applied Mathematics and Computation ; Volume 217, Issue 17 , 2011 , Pages 7051-7052 ; 00963003 (ISSN) Daneshpajouh, H ; Alimomeni, M ; Sharif University of Technology

2011

Abstract

We reduce the problem of minimum interval cost flow problem (MICFP) introduced by Hashemi et al. (2006) to the well-known minimum cost flow problem (MCFP)

Algorithms for Path Simplification

, Ph.D. Dissertation Sharif University of Technology Daneshpajouh, Shervin (Author) ; Ghodsi, Mohammad (Supervisor)

Abstract

In this thesis, we present different algorithms for path simplification. We first study this problem under area measures. We present an approximation algorithm for sum-area measure and an optimal algorithm for diff-area measure. Both of these algorithms can be applied on general paths. Moreover, we study the homotopic path simplification. We present a general framework for path simplification which work for desired error measure. We first present a strongly homotopic simplification algorithm for x-monotone paths. Also, we study the strongly homotopic simplification for general paths. We present a geometric tree data structure and present an algorithm based on this data structure....

Modeling of Dynamic Kill in Gas-Condensate Well

, M.Sc. Thesis Sharif University of Technology Daneshpajouh, Abouzar (Author) ; Shad, Saeed (Supervisor)

Abstract

By exploring huge gas-condensate reservoirs, three-phase transient flow modeling demonstrates its crucial role in designing dynamic kill, relief well parameters and kill procedure of such wells. Controlling gas-condensate well needs robust transient three phase models capable of capturing discontinuities in density, geometry and velocity of phases. In this paper, two phase Advection-Upstream-Splitting-Method hybrid scheme is extended to three-phase model capable of modeling blowout and dynamic kill in gas-condensate-water wells. Density and viscosity changes are calculated using Peng-Robinson equation of state and in according, flow model parameters are corrected.The capability of this model...

Computing polygonal path simplification under area measures

, Article Graphical Models ; Volume 74, Issue 5 , September , 2012 , Pages 283-289 ; 15240703 (ISSN) Daneshpajouh, S ; Ghodsi, M ; Zarei, A ; Sharif University of Technology

2012

Abstract

In this paper, we consider the restricted version of the well-known 2D line simplification problem under area measures and for restricted version. We first propose a unified definition for both of sum-area and difference-area measures that can be used on a general path of n vertices. The optimal simplification runs in O(n 3) under both of these measures. Under sum-area measure and for a realistic input path, we propose an approximation algorithm of O n2 time complexity to find a simplification of the input path, where is the absolute error of this algorithm compared to the optimal solution. Furthermore, for difference-area measure, we present an algorithm that finds the optimal...

Path simplification under difference area measure

, Article 2009 14th International CSI Computer Conference, CSICC 2009, 20 October 2009 through 21 October 2009, Tehran ; 2009 , Pages 276-279 ; 9781424442621 (ISBN) Daneshpajouh, S ; Zarei, A ; Ghodsi, M ; Sharif University of Technology

2009

Abstract

In this paper, we consider path simplification problem under difference area (diff-area) measure. Diff-area measure is defined as AA(Q) AB(Q) , where AA(Q) is the area under Q and above P and AB(Q) is the area above Q and under P (sec Figure 1). Bose et al. [1] presented an approximation algorithm for finding a simplificd path with at most k verticcs that minimizes the cliff-area measure which only works on i-monotone paths. The constraint of being i-monotone is restrictive in some applications like tracking bird migration paths or map boundary simplification. Here, we extend the method of Rosc et al. [1] and present algorithms with the same time complexities as theirs for gcneral paths....

A fast community based algorithm for generating web crawler seeds set

, Article WEBIST 2008 - 4th International Conference on Web Information Systems and Technologies, Funchal, Madeira, 4 May 2008 through 7 May 2008 ; Volume 2 , 2008 , Pages 98-105 ; 9789898111265 (ISBN) Daneshpajouh, S ; Nasiri, M. M ; Ghodsi, M ; Sharif University of Technology

2008

Abstract

In this paper, we present a new and fast algorithm for generating the seeds set for web crawlers. A typical crawler normally starts from a fixed set like DMOZ links, and then continues crawling from URLs found in these web pages. Crawlers are supposed to download more good pages in less iterations. Crawled pages are good if they have high PageRanks and are from different communities. In this paper, we present a new algorithm with O(n) running time for generating crawler's seeds set based on HITS algorithm. A crawler can download qualified web pages, from different communities, starting from generated seeds set using our algorithm in less iteration

Synthesis and Biological Evaluation of Superparamagnetic Iron Oxide Nanoparticles as Contrast Agents for Bioimaging Applications

, M.Sc. Thesis Sharif University of Technology Ali Abouzar, Mitra (Author) ; Maddah Hosseini, Hamid (Supervisor) ; Oghabian, Mohammad Ali (Supervisor)

Abstract

A biocompatible ferrofluid containing ?Fe?_3 O_4 nanoparticles was produced using co precipitation of ?FeCl?_2.?4H?_(2 )O and ?FeCl?_3 ?6H?_2 O under ultrasonic irradiation power with NaOH being the alkaline. Two variables studied in this research were concentration and molecular weight of PEG, as the coating agent. The impact of these variables were carefully monitored on shape, size distribution and magnetic behavior of nanoparticles through SEM, DLS, XRD and VSM characterization techniques. Moreover, MRI relaxation times,T_1and T_2, were calculated using synthesized nanoparticles as contrast agents. Accordingly these nanoparticles were biologically evaluated by MTT assay. Results...