Pramod Kumar Mishra

Force-induced desorption of a linear polymer chain adsorbed on an attractive surface

We consider a model of self-avoiding walk on a lattice with on-site repulsion and an attraction for every vertex of the walk visited on the surface to study force-induced desorption of a linear polymer chain adsorbed on an attractive surface and use the exact enumeration technique for analyzing how the critical force for desorption fc(T) depends on the temperature. The curve fc(T) gives the boundary separating the adsorbed phase from the desorbed phase. Our results show that in two dimensions, where surface is a line, the force fc(T) increases monotonically as temperature is lowered and becomes almost constant at very low temperatures. In case of three dimensions we, however, find re-entrance, i.e. fc(T) goes through a maximum as temperature is lowered. The behaviour of the polymer chain at different values of temperature and force is examined by calculating the probability distribution of the height from the surface of the vertex at which external force is applied.

A simple and exactly solvable model for a semiflexible polymer chain interacting with a surface

We use the lattice model of directed walks to investigate the conformational as well as the adsorption properties of a semiflexible homopolymer chain immersed in a good solvent in 2D and 3D. To account for the stiffness in the chain we have introduced energy barrier for each bend in the walk and have calculated the persistent length as a function of this energy. For the adsorption on an impenetrable surface perpendicular to the preferred direction of the walk we have solved the model exactly and have found the critical value of the surface attractions for the adsorption in both 2D and 3D. We have also enumerated all possible walks on square and cubic lattices for the number of steps N⩽30 for 2D and N⩽20 for 3D and have used ratio method for extrapolation. The transition located using this method is in excellent agreement with the results found from the analytical method. We have compared the results of surface adsorption for two different surface orientations. In one of the orientation, surface is considered parallel to the preferred direction and in another it is perpendicular to the preferred direction. Results found in both the cases indicate that for stiffer chains adsorption transition takes place at higher temperature compared to that of flexible chain

Does a surface attached globule phase exist

A long flexible neutral polymer chain immersed in a poor solvent and interacting with an impenetrable attractive surface exhibits a phase known as surface attached globule (SAG) in addition to other adsorbed and desorbed phases. In the thermodynamic limit, the SAG phase has the same free energy per monomer as the globular phase, and the transition between them is a surface transition. We have investigated the phase diagrams of such a chain in both two- and three-dimensions and calculated the distribution of monomers in different domains of the phase diagram.

Direction analysis algorithm using statistical approaches

Statistical approaches become very important tools that interfere and overlap in our daily life and become inevitable event that help us in every tiny details of our life, in this paper; we are going to present a new technique for analyzing the two principal component of any given object by calculating the direction over the occupied coordinates using mean, variance, and covariance statistical functions, and by finding some relationship between those statistical functions; we have extracted the angle degree of the processed object, for pattern recognition applications; this object can be adjusted accordingly to overcome the rotation perturbation shortcoming that hinders the extraction of a unified features especially for object recognition purposes in which we have to present many samples per single pose which makes the processing of this increasing size of the database is a noticeable burden, we have achieved a dramatically results with almost zero time of calculation since the statistical functions applied need little processing time to finish.

Collapsed and Adsorbed States of a Directed Polymer Chain in Two Dimensions

A phase diagram for a surface-interacting long flexible partially-directed polymer chain in a two-dimensional poor solvent, where the possibility of collapse in the bulk exists, is determined using exact enumeration methods. We used a model of self-attracting self-avoiding walks and evaluated 30 steps in series. An intermediate phase between the desorbed collapsed and adsorbed expanded phases, having the conformation of a surface-attached globule, is found. The four phases, viz ., (i) desorbed expanded (DE), (ii) desorbed collapsed (DC), (iii) adsorbed expanded (AE), (iv) surface-attached globule (SAG), are found to meet at a multicritical point. These features are in agreement with those of an isotropic (or non-directed) polymer chain.

A Randomized Scheduling Algorithm for Multiprocessor Environments Using Local Search

The LOCAL(A, B) randomized task scheduling algorithm is proposed for fully connected multiprocessors. It combines two given task scheduling algorithms (A, and B) using local neighborhood search to give a hybrid of the two given algorithms. Objective is to show that such type of hybridization can give much better performance results in terms of parallel execution times. Two task scheduling algorithms are selected: DSC (Dominant Sequence Clustering as algorithm A), and CPPS (Cluster Pair Priority Scheduling as algorithm B) and a hybrid is created (the LOCAL(DSC, CPPS) or simply the LOCAL task scheduling algorithm). The LOCAL task scheduling algorithm has time complexity O(|V||E|(|V |+|E|)), where V is the set of vertices, and E is the set of edges in the task graph. The LOCAL task scheduling algorithm is compared with six other algorithms: CPPS, DCCL (Dynamic Computation Communication Load), DSC, EZ (Edge Zeroing), LC (Linear Clustering), and RDCC (Randomized Dynamic Computation Communication). Performance evaluation of the LOCAL task scheduling algorithm shows that it gives up to 80.47 % improvement of NSL (Normalized Schedule Length) over other algorithms.

A RANDOMIZED SCHEDULING ALGORITHM FOR MULTIPROCESSOR ENVIRONMENTS

In this paper, we propose a randomized scheduling algorithm on a fully connected homogeneous multiprocessor environment. This is a randomized version of our earlier algorithm in which we used priority of modules that was dependent on the computation and the communication times associated with the modules. First we propose a generalization of our earlier scheduling algorithm with restricted number of clusters to reduce the time complexity. Then we apply randomization to the generalized algorithm and demonstrate its superiority over our previous work. We show the complexity of our proposed algorithm as O(ab |V| (|V|+|E|) log (|V|+|E|)). Here a is the number of randomization steps, and b is a limit on the number of clusters formed. If we use a and b as constants, then this gives a better complexity in comparison with the complexity of our previous algorithm that was O(|V|2(|V|+|E|) log (|V|+|E|)). In comparison with our previous work we get a performance improvement of up to 6.63% and a performance improvement of up to 12.56% when compared with Sarkars Edge Zeroing algorithm.

Equilibrium statistics of an infinitely long chain in the severe confined geometry: exact results

We analyse the equilibrium statistics of a long linear homopolymer chain confined in between two flat geometrical constraints under good solvent conditions. The chain is occupying two-dimensional space and geometrical constraints are two impenetrable lines for the two-dimensional space. A fully directed self-avoiding walk lattice model is used to derive analytical expression of the partition function for the given value of separation () in between the impenetrable lines. The exact values of the critical exponents ( and ) were obtained for given values of separations in between the impenetrable lines. The probability of polymerization of the confined polymer chain conformations (bridges and trains) with any or both the ends in contact with the impenetrable lines was obtained and the dominant contribution of the canonical partition function of an N-monomer-long chain is also analysed to discuss the effect of confinement on equilibrium statistics of the confined chain. An exact expression of the grand canonical partition function of the confined semi-flexible chain is also calculated using the generating function technique.

Performance Analysis of Floyd Warshall Algorithm vs Rectangular Algorithm

this paper, we have examined the comparative study of Floyd Warshall algorithm and the Rectangular algorithm. We have tested these two algorithms on random graphs generated by the Erdos - Renyi (ER) model. The evaluation of the algorithms for different probabilities show that the Floyd Warshall algorithm gives slightly better performance for dense graphs while the Rectangular algorithm works better for sparse graphs. Keywordsford algorithm, Dijkstras algorithm, Floyd warshall algorithm, all pair shortest path algorithm, the rectangular algorithm, comparison of algorithms.