Algorithms for computing diffuse reflection paths in polygons

Let s be a point source of light inside a polygon P of n vertices. A polygonal path from s to some point t inside P is called a diffuse reflection path if the turning points of the path lie on edges of?P. A?diffuse reflection path is said to be optimal if it has the minimum number of reflections on the path. The problem of computing a diffuse reflection path from s to t inside P has not been considered explicitly in the past. We present three different algorithms for this problem which produce suboptimal paths. For constructing such a path, the first algorithm uses a greedy method, the second algorithm uses a transformation of a minimum link path, and the third algorithm uses the edge–edge visibility graph of?P. The first two algorithms are for polygons without holes, and they run in O(n+klogn) time, where k denotes the number of reflections in the constructed path. The third algorithm is for polygons with or without holes, and it runs in O(n ²) time. The number of reflections in the path produced by this third algorithm can be at most three times that of an optimal diffuse reflection path. Though the combinatorial approach used in the third algorithm gives a better bound on the number of reflections on the path, the first and the second algorithms stand on the merit of their elegant geometric approaches based on local geometric information.     

The Syntheses and Characterization of Interpenetrating Polymer Networks (IPNs) Derived from Cardanol-Based Dye and Linseed Oil-Based Polyurethanes

Interpenetrating Polymer Networks, from glycerol modified linseed oil polyurethanes and cardanol-based dyes, which are yet to be extensively studied were synthesized using benzoyl peroxide as initiator and ethylene glycol dimethacrylate as cross-linker. These polymers were characterized by Fourier transform infrared spectra, thermal analysis techniques such as thermogravimetric analysis, derivative thermogravimetry and differential thermal analysis. The kinetic parameters such as activation energy and orders of reaction were ascertained using Freeman-Carroll and Freeman-Anderson methods. The effects of changes in polyurethane to dye monomer weight ratio on the properties of such polymers were investigated at 1.2 and 1.6 NCO/OH ratios.     

Transport of cobalt(II) through a hollow fiber supported liquid membrane containing di-(2-ethylhexyl) phosphoric acid (D2EHPA) as the carrier

This work presents experimental, modeling and simulation studies for Co²⁺ ion extraction using hollow fiber supported liquid membrane (HFSLM) operated in a recycling mode. Extractant di-(2-ethylhexyl) phosphoric acid (D2EHPA) diluted with kerosene has been used as the membrane phase. The Co²⁺ ion concentration in the aqueous feed phase was varied in the range of 1–3 mM. Also, D2EHPA concentration was varied in the range of 10–30% (v/v). A mass transfer model has been developed considering the complexation and de-complexation reactions to be fast and at equilibrium. Equations for extractant mass balance and counter-ion (H⁺) transport have also been incorporated in the model. Extraction equilibrium constant (K_ex) for cobalt–D2EHPA system has been estimated from equilibration experiments and found to be 3.48 × 10⁻⁶. It was observed that the model results are in good agreement with the experimental data when diffusivity of metal-complex (D_m) through the membrane phase is 1.5 × 10⁻¹⁰ m²/s. Feed phase pH and strip phase acidity had negligible effect on the extraction profiles of Co²⁺ ions. An increase in D2EHPA concentration increased extraction rates of Co²⁺ ions. The membrane phase diffusion step was found to be the controlling resistance to mass transfer.     

Review of tools and algorithms for network motif discovery in biological networks

Network motifs are recurrent and over‐represented patterns having biological relevance. This is one of the important local properties of biological networks. Network motif discovery finds important applications in many areas such as functional analysis of biological components, the validity of network composition, classification of networks, disease discovery, identification of unique subunits etc. The discovery of network motifs is a computationally challenging task due to the large size of real networks, and the exponential increase of search space with respect to network size and motif size. This problem also includes the subgraph isomorphism check, which is Nondeterministic Polynomial (NP)‐complete. Several tools and algorithms have been designed in the last few years to address this problem with encouraging results. These tools and algorithms can be classified into various categories based on exact census, mapping, pattern growth, and so on. In this study, critical aspects of network motif discovery, design principles of background algorithms, and their functionality have been reviewed with their strengths and limitations. The performances of state‐of‐art algorithms are discussed in terms of runtime efficiency, scalability, and space requirement. The future scope, research direction, and challenges of the existing algorithms are presented at the end of the study.Inspec keywords: computational complexity, graph theory, biology, search problemsOther keywords: network size, motif size, network motif discovery, biological networks, network composition, recurrent patterns, over‐represented patterns, local properties, search space, subgraph isomorphism check, NP‐complete problem, NP‐complete problem, exact census, design principles, background algorithms, runtime efficiency, space requirement     

Optimization of Polishing Conditions for Long Grain <Emphasis Type="Italic">Basmati</Emphasis> Rice in a Laboratory Abrasive Mill

Rice milling operation is a very energy-intensive process. The major qualities of the rice which are taken into consideration while milling are the degree of milling and head rice yield. A laboratory abrasion polisher, modified by attaching a humidifying and cooling unit, was used to polish long-grain Pusa Basmati rice in order to optimize the polishing conditions. Polishing experiments were carried out using central composite design for a factorial with a central point, at different initial grain temperatures (5–25 °C) and milling chamber temperatures (11–25 °C) at a constant humidity level of 95 ± 2% for different time intervals. Models capable of predicting the quality of milled rice were developed using response surface methodology and used to determine optimum processing conditions. Responses such as degree of milling (DOM), broken content, and specific energy consumption were used to assess product quality. Optimum milling conditions of a minimum of 10% DOM, a broken content of 8%, and a specific energy consumption of 11 kJ/DOM were obtained at a milling chamber temperature of 11 °C, an initial grain temperature of 15 °C, and a milling period of 180 s.     

Electrochemical insertion of Sr ions onto nano δ-MnO2 particles

Manganese dioxide is known to be an important electroactive material for supercapacitors. Generally, δ-MnO₂ is subjected to electrochemical characterization studies in aqueous electrolytes of Na₂SO₄. It exhibits capacitance behaviour in the potential range between 0 and 1.0 V vs. SCE (saturated calomel electrode). In the present study, it is shown that δ-MnO₂ exhibits capacitance behaviour in Sr(NO₃)₂ electrolytes also. The suitable potential range in this electrolyte is also found to be 0-1.0 V. Specific capacitance measured in Sr(NO₃)₂ electrolyte is 192 F g^− 1. X-ray photoelectron spectroscopy data confirm that Sr²⁺ ions get inserted onto δ-MnO₂ nanoparticles.     

Selective transport of radio-cesium by supported liquid membranes containing calix[4]crown-6 ligands as the mobile carrier

Facilitated transport of Cs-137 across supported liquid membranes (SLM) containing a calix-crown ligand viz. caliz[4]arene-bis(crown-6) (CC), calix[4]arene-bis(o-benzocrown-6) (CBC) or calix[4]arene-bis(napthocrown-6) (CNC) was investigated. The feed consisted of dilute nitric acid solutions while the carrier solutions contained mainly CNC in several organic diluents inside the pores of polypropylene (PP) as well as PTFE flat sheet membranes. PTFE membranes containing CNC in a diluent mixture of 2-nitrophenyloctyl ether (NPOE) and n-dodecane were found to have high stability. Selectivity studies were carried out using simulated high level waste (SHLW) as well as fission products obtained from an irradiated natural uranium target.     

Algorithm for Accurate Three-Dimensional Scene Graph Updates in High-Speed Animations of Previously Simulated Construction Operations

Abstract:   Visualization of construction operations is an important technique to communicate the logic of simulation models in detail. Early efforts resulted in a scene graph and frame update algorithm that was capable of converting discrete information from simulation models into smooth and continuous 3D animations. That algorithm did not account for high speed or concurrent animation because the need to do so was not anticipated. Recent advances in computing power and an interest in using the technology for next generation applications now demand accurate high speed and concurrent animations. This article presents the design of the original algorithm at a previously undocumented level of detail and specificity, and that allows for the analysis of its shortcomings when used at high speeds or concurrently with simulation. Two subsequent but still inadequate designs of the algorithm are also presented and analyzed in detail so that they can serve as an illustration of the path toward the final design and place it in proper context. The article concludes with the final design and evaluation of the algorithm, which is accurate at very high animation speeds and supports concurrent animation of simulation models.