Design of 5.9 ghz dsrc-based vehicular safety communication

The automotive industry is moving aggressively in the direction of advanced active safety. Dedicated short-range communication (DSRC) is a key enabling technology for the next generation of communication-based safety applications. One aspect of vehicular safety communication is the routine broadcast of messages among all equipped vehicles. Therefore, channel congestion control and broadcast performance improvement are of particular concern and need to be addressed in the overall protocol design. Furthermore, the explicit multichannel nature of DSRC necessitates a concurrent multichannel operational scheme for safety and non-safety applications. This article provides an overview of DSRC based vehicular safety communications and proposes a coherent set of protocols to address these requirements     

On trading wavelengths with fibers: a cost-performance based study

We consider the effect of multiple fibers on wavelength division multiplexing networks without wavelength conversion. We study networks with dynamic wavelength routing and develop accurate analytical models to compare various possible options using single- and multiple-fiber networks. We use results of an analytical model and simulation-based studies to evaluate the blocking performance and cost of multifiber networks. The number of fibers required providing high performance in multifiber networks and their costs are compared. A case is made for using multiple fibers in each link with fewer wavelengths instead of using a single fiber with many wavelengths. In particular, we show that a network with four fibers per link and with four wavelengths on each fiber without any wavelength conversion on any node yields similar same performance as the networks with one fiber per link and 16 wavelengths per fiber on each link and with full wavelength conversion capability on all nodes. In addition, the multifiber network may also offer the cost advantage depending on the relative cost of components. We develop a parametric cost model to show that multiple fibers in each link are an attractive option. Finally, such multifiber networks also has fault tolerance, with respect to a single fiber failure, already built into the system.     

A Monte Carlo simulation study of the mechanical and conformational properties of networks of helical polymers. I. General concepts

We study the mechanical and conformational properties of networks of helical polymers with a combination of Monte Carlo simulations based on the Wang-Landau algorithm and the three-chain model. We find that the stress-strain behavior of these networks has novel features not observed in typical networks made of synthetic polymers. In particular, we find that as these networks are stretched they first strengthen, then soften and finally strengthen again. This non-monotonic behavior of the stress correlates with the one of the helical content and is rationalized by the elongation-induced formation and melting of the helical structure of the polymer. We complement these results with a study of other conformational properties of the polymer strands that clarify the molecular mechanisms behind the mechanical behavior of these networks. Finally, we present a qualitative comparison of some of our results with the theoretical ones recently reported by Kutter and Terentjev.     

DISCREPANCIES IN THE REGRESSION MODELLING OF RECRYSTALLIZATION RATE AS USING THE DATA FROM PHYSICAL SIMULATION TESTS

The analysis of numerous experimental equations published in the literature reveals a wide scatter in the predictions for the static recrystallization kinetics of steels. The powers of the deformation variables, strain and strain rate, similarly as the power of the grain size vary in these equations. These differences are highlighted and the typical values are compared between torsion and compression tests. Potential errors in physical .simulation testing are discussed.     

Speed Control of DC Motor with MRPID Controller in the Presence of Noise

Speed control of a DC motor has always been a challenge because of its variable torque. But it becomes more challenging when noise enters the system at its input. Therefore, there is a need of more advanced controllers. In this paper, a multi-resolution proportional integral derivative (MRPID) controller has been proposed to be utilized to control the speed of a DC motor. It works well even in the presence of noise as compared to the conventional PID controller. Also, performance of a PID controller deteriorates when nonlinearity or uncertainty arises in the system. This degraded performance can be improved by utilizing the multi-resolution property of wavelets, which decomposes the error signal into various frequency components. Further, wavelet coefficients of these decompositions are used to generate the control signal for controlling speed of a DC motor. In this paper, performances of a MRPID, a fractional order PID (FOPID) and a conventional PID controllers are compared in the presence of noise for speed control of a DC motor. The results obtained using a MRPID controller are observed to be better in terms of improved transient characteristics and disturbance rejection for a DC motor as compared to those obtained with PID and FOPID controllers.

     

Enhanced photoluminescence from CdS nanocrystals encapsulated by PVP and SHMP

The effects of the stabilizing agent on the structural and luminescence properties of cadmium sulfide (CdS) nanocrystals have been investigated. Samples were prepared by chemical precipitation method using sodium hexametaphosphate (SHMP) and polyvinyl pyrrolidone (PVP). The structural and optical properties have been studied by X-ray diffraction (XRD), ultraviolet-visible (UV-Vis) absorption, photoluminescence (PL) and Fourier transform infrared (FTIR) spectroscopy. XRD patterns confirm the presence of cubic zinc blend crystal structure with space group F-43m. The results show the variation in crystallite size with change in surfactant. Blue shift in absorption edge as compared to bulk CdS is found. PL results represent broad and very intense red emission with smaller particle size due to modification of surface emitting states with surfactant.     

Antineoplastic and antioxidant potential of phycofabricated silver nanoparticles using microalgae Chlorella minutissima

This study for the first time reports on fresh water microalgae Chlorella minutissima aqueous extract (CmAe) which was utilized for the biogenic synthesis of silver nanoparticles and tested their antineoplastic potential against Liver Hepatocellular Carcinoma (HepG2) cell line. The characteristic colour change of the reaction mixture from greenish yellow to yellowish brown confirmed the synthesis of Chlorella minutissima silver nanoparticles (CmAgNPs). Microscopic analysis revealed CmAgNPs to be spherical‐shaped with particle size ranging from 10 to 30 nm. The carbohydrates and proteins distinctive peaks were observed in Fourier transform infrared spectroscopy (FTIR) spectra which suggested these biomolecules acted as reducing and capping agents. Further, the crystalline nature of CmAgNPs was confirmed by X‐ray diffraction (XRD) analysis. CmAgNPs showed maximum free radical scavenging proving it to be more potent antioxidant agent as compared to CmAe. The mortality rate of HepG2 cells treated with CmAgNPs was found to be 91.8 % at 120 μg/ml with IC₅₀ value 12.42 ± 1.096 μg/ml after 48 h whereas no effect was observed on normal Human Embryonic Kidney (HEK 293) cells. Fluorescent images of the treated HepG2 cells revealed the formation of apoptotic bodies, condensed nuclei and cell shrinkage indicating their effectiveness against the cancer cells.Inspec keywords: silver, nanoparticles, nanomedicine, microorganisms, cellular biophysics, nanofabrication, scanning electron microscopy, transmission electron microscopy, atomic force microscopy, proteins, Fourier transform infrared spectra, molecular biophysics, X‐ray chemical analysis, X‐ray diffraction, kidney, cancer, biomedical materialsOther keywords: antineoplastic potential, antioxidant potential, phycofabricated silver nanoparticle, Chlorella minutissima, freshwater microalgae, aqueous extract, liver hepatocellular carcinoma cell line, CmAgNP synthesis, field emission scanning electron microscopy, high‐resolution transmission electron microscopy, atomic force microscopy, dynamic light scattering, carbohydrate, protein, Fourier transform infrared spectroscopy, biomolecule, energy‐dispersive X‐ray spectroscopy, elemental silver signal, CmAgNP crystalline, X‐ray diffraction analysis, antioxidant agent, HepG2 cell mortality rate, human embryonic kidney, HEK 293 cell, fluorescent image, apoptotic body formation, condensed nuclei, cell shrinkage, cancer cell, antineoplastic agent, Ag     

Reliability evaluation and optimal design in heterogeneous multi-state series-parallel systems

This paper addresses the heterogeneous redundancy allocation problem in multi-state series-parallel reliability structures with the objective to minimize the total cost of system design satisfying the given reliability constraint and the consumer load demand. The demand distribution is presented as a piecewise cumulative load curve and each subsystem is allowed to consist of parallel redundant components of not more than three types. The system uses binary capacitated components chosen from a list of available products to provide redundancy so as to increase system performance and reliability. The components are characterized by their feeding capacity, reliability and cost. A system that consists of elements with different reliability and productivity parameters has the capacity strongly dependent upon the selection of constituent components. A binomial probability based method to compute exact system reliability index is suggested. To analyze the problem and suggest an optimal/near-optimal system structure, an ant colony optimization algorithm has been presented. The solution approach consists of a series of simple steps as used in early ant colony optimization algorithms dealing with other optimization problems and offers straightforward analysis. Four multi-state system design problems have been solved for illustration. Two problems are taken from the literature and solved to compare the algorithm with the other existing methods. The other two problems are based upon randomly generated data. The results show that the method can be appealing to many researchers with regard to the time efficiency and yet without compromising over the solution quality.     

Nanoclays for polymer nanocomposites, paints, inks, greases and cosmetics formulations, drug delivery vehicle and waste water treatment

An overview of nanoclays or organically modified layered silicates (organoclays) is presented with emphasis placed on the use of nanoclays as the reinforcement phase in polymer matrices for preparation of polymer/layered silicates nanocomposites, rheological modifier for paints, inks and greases, drug delivery vehicle for controlled release of therapeutic agents, and nanoclays for industrial waste water as well as potable water treatment to make further step into green environment. A little amount of nanoclay can alter the entire properties of polymers, paints, inks and greases to a great extent by dispersing 1nm thick layered silicate throughout the matrices. The flexibility of interlayer spacing of layered silicates accommodates therapeutic agents which can later on be released to damaged cell. Because the release of drugs in drug-intercalated layered materials is controllable, these new materials have a great potential as a delivery host in the pharmaceutical field. The problem of clean water can be solved by treating industrial and municipal waste water with organoclays in combination with other sorbents like activated carbon and alum. Organoclays have proven to be superior to any other water treatment technology in applications where the water to be treated contains substantial amounts of oil and grease or humic acid.