Enhanced Dynamic Hierarchical Replication and Weighted Scheduling Strategy in Data Grid

The Data Grid provides massive aggregated computing resources and distributed storage space to deal with data-intensive applications. Due to the limitation of available resources in the grid as well as production of large volumes of data, efficient use of the Grid resources becomes an important challenge. Data replication is a key optimization technique for reducing access latency and managing large data by storing data in a wise manner. Effective scheduling in the Grid can reduce the amount of data transferred among nodes by submitting a job to a node where most of the requested data files are available. In this paper two strategies are proposed, first a novel job scheduling strategy called Weighted Scheduling Strategy (WSS) that uses hierarchical scheduling to reduce the search time for an appropriate computing node. It considers the number of jobs waiting in a queue, the location of the required data for the job and the computing capacity of the sites Second, a dynamic data replication strategy, called Enhanced Dynamic Hierarchical Replication (EDHR) that improves file access time. This strategy is an enhanced version of the Dynamic Hierarchical Replication strategy. It uses an economic model for file deletion when there is not enough space for the replica. The economic model is based on the future value of a data file. Best replica placement plays an important role for obtaining maximum benefit from replication as well as reducing storage cost and mean job execution time. So, it is considered in this paper. The proposed strategies are implemented by OptorSim, the European Data Grid simulator. Experiment results show that the proposed strategies achieve better performance by minimizing the data access time and avoiding unnecessary replication.     

A simple analytical model for calculating the effective thermal conductivity of nanofluids

A simple mathematical model for calculating the effective thermal conductivity of nanofluids has been developed based on the thermal resistance approach. The model is developed by considering both effects of a solid‐like nanolayer and convective heat transfer caused by Brownian motion which have not been considered simultaneously by most available models in the literature. In addition the correlation of Prasher and Phelan for the convective heat transfer coefficient is modified to take into account the effect of the solid‐like nanolayer. In addition a general value for n (different from the one presented by Tillman and Hill) is introduced to modify the thickness of the solid‐like nanolayer. The latter is done by considering both conduction and convection heat transfer mechanisms. Comparisons with previously published experimental results and other mathematical models show that the presented model could well predict a nanofluids effective thermal conductivity as a function of the nanoparticles mean diameter, volume fraction, and temperature for different kinds of nanofluids. © 2010 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20290     

Accurate analysis of carbon nanotube interconnects using transmission line model

A new technique for analysing the time-domain response of carbon nanotube (CNT) interconnects, based on transmission line modelling, that takes the effects of both contact and fundamental (quantum) resistances into account is introduced. A new sixth-order linear parametric expression for the transfer function of these lines has been presented for the first time. For verification purposes, the step response of a driver-CNT bundle-load configuration for a 32 nm technology node, using the new technique and HSPICE simulation have been compared, with which the obtained results show an excellent match. Also the effect of contact resistance on the step response, especially the propagation delay, has been studied. The obtained results show that for the length of a CNT bundle equal to 50 mum with the diameter of each individual CNT 1 nm, the propagation delay changes from 0.138 to 5.58 ns for the contact resistance values from 1 to 50 k Omega, i.e. a variation range of 39.43 times the minimum value. The related delay variations for the length values 200 mum, 500 mum and 1000 mum, are 31.37, 22.61 and 15.42 times the minimum value, respectively.     

Electroactive polythiophene/polystyrene bottlebrushes as morphology compatibilizers in photovoltaic systems

Poly(3‐thiophene ethanol) (P3ThEt)‐graft‐polystyrene (PSt) bottlebrushes were synthesized and applied in active layers of poly(3‐hexylthiophene) (P3HT):phenyl‐C71‐butyric acid methyl ester (PC71BM) solar cells as morphology compatibilizers. In the presence of 15 wt% of P3ThEt‐graft‐PSt bottlebrush compatibilizers, the P3HT crystallite dimensions (D₍₁₀₀₎ = 45.67 nm and D₍₀₂₀₎ = 30.12 nm) and R_mean (38.96 nm) of PCBM clusters were the largest and the layer spacings were all the smallest (d₍₁₀₀₎ = 1.054 nm, d₍₀₂₀₎ = 0.301 nm and d_(PCBM) = 0.406 nm). These dimensional properties led to better hole (1.9 × 10^?3 cm² V^?1 s^?1) and electron (1.2 × 10^?2 cm² V^?1 s^?1) mobilities. The content of bottlebrushes was optimized at 15 wt%, and thereby the best photovoltaic results including the maximum cell efficiency of 5.37% were obtained for this turning point (12.75 mA cm^?2, 61%, 0.69 V). On exceeding the optimum weight percentage, all photovoltaic parameters decreased markedly and reached even less than that of pristine devices (1.92% versus 2.24%). After an optimum weight percentage of compatibilizers, further enhancement in bottlebrush content in active layers saturated and finally oversaturated the system and, consequently, the cell parameters significantly decreased. Accumulation of bottlebrushes in interfaces and donor/acceptor phases ruined the system function even with large and packed P3HT crystallites and PC71BM clusters. © 2019 Society of Chemical Industry     

Multipolar Graviton in the Hydrogen Atoms

We derive multipolar gravitational radiation in the framework of quantum field theory in which the atomic states are treated nonrelativistically, and the gravitational waves are quantized. By relaxing the constraint e^ik·x ≈ 1, the multipolar transition rate is calculated when one graviton is emitted. As a consistency check, we recover the semiclassical result in the dipole approximation regime. Besides, we show that the dynamical mechanism that gives rise to spontaneous graviton emission by an atom, has a profound consequence on the lifetime of the atomic electron.     

Biodegradable and conductive hyperbranched terpolymers based on aliphatic polyester,poly(D,L-lactide), and polyaniline used as scaffold in tissue engineering

Designing the novel conductive and biodegradable scaffolds based on star-like hyperbranched terpolymers of aliphatic polyester–poly(D,L-lactide)–polyaniline (S-HAP–PLA–PANI) was the purpose of this research. The electroactivity of tissue engineering scaffold, which in the current work was for the presence of PANI, is an essential factor in its performance because the electrical signals are the pivotal physiological stimuli that control the adhesion and differentiation of various cell types. Star-shaped polymers have attracted conspicuous attention, thanks to their low-cost, well-defined highly functionalized structures and low crystallinity, and they also could be an interesting alternative to the linear analogs for their interaction with surrounding tissue and faster degradation rate. In the present work, after 12 weeks, the mass loses for S-HAP–PLA–PANI sample were calculated to be 45%. Scaffolds based on S-HAP–PLA–PANI/PLA nanofibers having the average diameter of 70–200?nm and electrical conductivity of 0.05 S cm^?1 imitated the natural microenvironment of extra cellular matrix to regulate the cell attachment, proliferation, and differentiation.     

Predictive control of drying process using an adaptive neuro-fuzzy and partial least squares approach

In this paper, adaptive neuro-fuzzy inference system (ANFIS), artificial neural network (ANN), and partial least squares (PLS) approaches are applied to predictive control of a drying process. In the proposed approaches, the PLS analysis is used to pre-process actual data and to provide the necessary background to apply ANN and ANFIS approaches. A reasonable section of this study is assigned to the modeling with the aim at predicting the granule particle size and executing by ANFIS and ANN. ANN holds the promise of being capable of producing non-linear models, being able to work under noise conditions, and being fault tolerant to the loss of neurons or connections. Also, the ANFIS approach combines the advantages of fuzzy system and artificial neural network to design architecture and is capable of dealing with both limitation and complexity in the data set. The efficiencies of ANFIS and ANN approaches in prediction are compared and the superior approach is selected. Finally, by deploying the preferred approach, several scenarios are presented to be used in predictive control of spray drying as an accurate, fast running, and inexpensive tool. This is the first study that presents a flexible intelligent approach for predictive control of drying process by ANN, ANFIS, and PLS. The approach of this study may be easily applied to other production process.     

Conjugate heat transfer of laminar mixed convection of a nanofluid through an inclined tube with circumferentially non-uniform heating

Laminar mixed convection of a nanofluid consisting of water and Al₂O₃ in an inclined tube with heating at the top half surface of a copper tube has been studied numerically. The bottom half of the tube wall is assumed to be adiabatic (presenting a tube of a solar collector). Heat conduction mechanism through the tube wall is considered. Three-dimensional governing equations with using two-phase mixture model have been solved to investigate hydrodynamic and thermal behaviours of the nanofluid over wide range of nanoparticle volume fractions. For a given nanoparticle mean diameter the effects of nanoparticle volume fractions on the hydrodynamics and thermal parameters are presented and discussed at different Richardson numbers and different tube inclinations. Significant augmentation on the heat transfer coefficient as well as on the wall shear stress is seen.     

Inverse boundary design of square enclosures with natural convection

An optimization technique is applied to design of heat transfer systems in which the natural convection is important. The inverse methodology is employed to estimate the unknown strengths of heaters on the heater surface of a square cavity with free convection from the knowledge of the desired temperature and heat flux distributions over a given design surface. The direct and the sensitivity problems are solved by finite volume method. The conjugate gradient method is used for minimization of an objective function, which is expressed by the sum of square residuals between estimated and desired heat fluxes over the design surface. The performance and accuracy of the present method for solving inverse convection heat transfer problems is evaluated by comparing the results with a benchmark problem and a numerical experiment.