Comparison of Conventional and Cross-Layer Multimedia Transport Schemes for Wireless Networks

Three competing schemes have been proposed for multimedia transport over broadband wireless channels: (a) traditional UDP (Postel, The User Datagram Protocol, 1980 [1]), (b) semi-cross-layer UDP-Lite (The Lightweight User Datagram Protocol, 2004 [2]), and (c) cross-layer header estimation (Khayam et al., IEEE Transactions on Multimedia 9(2):377–385, 2007 [3]; Khayam and Radha, IEEE Transactions on Wireless Communications 6(11):3946–3954, 2007 [4]). In all these schemes, corrupted and lost packets are recovered using FEC at the application layer. In this paper, we analytically and experimentally compare the performances of these broadband wireless multimedia schemes. First, we derive lower bounds on the excepted FEC redundancy required by ideal cross-layer header estimation, UDP and UDP-Lite over an arbitrary-order Markov wireless channel. We show that under realistic wireless channel conditions, the cross-layer header estimation scheme always requires lesser redundancy than UDP and UDP-Lite. We then propose a practical minimum distance decoding (MDD) header estimation scheme, which is receiver-based, low complexity and highly accurate. Trace-driven multimedia experiments over wireless LANs demonstrate that MDD header estimation requires significantly lesser FEC redundancy and renders better video quality than existing schemes.     

A Functional Programming Framework for Latency Insensitive Protocol Validation

Latency insensitive protocols (LIPs) have been proposed as a viable means to connect synchronous IP blocks via long interconnects in a system-on-chip. The reason why one needs to implement LIPs on long interconnects stems from the fact that with increasing clock frequencies, the signal delay on some interconnects exceeds the clock period. Correctness of a system composed of synchronous blocks communicating via LIPs is established by showing latency equivalence between a completely synchronous composition of the blocks, and the LIP based composition. A design flow based on a synchronous composition specification, and stepwise refinement to LIP composition can be easily conceived, and a proof obligation to show latency equivalence between the synchronous specification and the refinement needs to be discharged. In this work, we propose a functional programming based framework for modeling and simulating LIP, and implement the semantics of various refinement steps in the programming model, so we can validate the LIP model against the original system within this functional programming framework. Such validation becomes easier due to the inherent denotational model of functional languages. We specifically use Standard ML to model the original system implementation as well as its latency insensitive version and compare the two by creating a model that contains both, giving them the same inputs and checking their outputs to be latency equivalent.     

Al₂O₃ and γAl₂O₃ Nanomaterials Based Nanofluid Models with Surface Diffusion: Applications for Thermal Performance in Multiple Engineering Systems and Industries

Thermal transport investigation in colloidal suspensions is taking a significant research direction. The applications of these fluids are found in various industries, engineering, aerodynamics, mechanical engineering and medical sciences etc. A huge amount of thermal transport is essential in the operation of various industrial production processes. It is a fact that conventional liquids have lower thermal transport characteristics as compared to colloidal suspensions. The colloidal suspensions have high thermal performance due to the thermophysical attributes of the nanoparticles and the host liquid. Therefore, researchers focused on the analysis of the heat transport in nanofluids under diverse circumstances. As such, the colloidal analysis of H₂O composed by γAl₂O₃ and Al₂O₃ is conducted over an elastic cylinder. The governing flow models of γAl₂O₃/H₂O and Al₂O₃/H₂O is reduced in the dimensionless form by adopting the described similarity transforms. The colloidal models are handled by implementing the suitable numerical technique and provided the results for the velocity, temperature and local thermal performance rate against the multiple flow parameters. From the presented results, it is shown that the velocity of Al₂O₃–H₂O increases promptly against a high Reynolds number and it decreases for high-volume fraction. The significant contribution of the volumetric fraction is examined for thermal enhancement of nanofluids. The temperature of Al₂O₃–H₂O and γAl₂O₃–H₂O significantly increases against a higher ϕ. Most importantly, the analysis shows that γAl₂O₃–H₂O has a high local thermal performance rate compared to Al₂O₃–H₂O. Therefore, it is concluded that γAl₂O₃–H₂O is a better heat transfer fluid and is suitable for industrial and technological uses.     

Facile Synthesis and Tensile Behavior of TiO<Subscript>2</Subscript> One-Dimensional Nanostructures

High-yield synthesis of TiO₂ one-dimensional (1D) nanostructures was realized by a simple annealing of Ni-coated Ti grids in an argon atmosphere at 950 °C and 760 torr. The as-synthesized 1D nanostructures were single crystalline rutile TiO₂ with the preferred growth direction close to [210]. The growth of these nanostructures was enhanced by using catalytic materials, higher reaction temperature, and longer reaction time. Nanoscale tensile testing performed on individual 1D nanostructures showed that the nanostructures appeared to fracture in a brittle manner. The measured Young’s modulus and fracture strength are ~56.3 and 1.4 GPa, respectively.     

Water absorbance and thermal properties of sulfated wheat gluten films

Wheat gluten films of various thicknesses formed at 30–70°C were treated with cold sulfuric acid to produce sulfated gluten films. Chemical, thermal, thermal stability, and water uptake properties were characterized for neat and sulfated films. The sulfated gluten films were able to absorb up to 30 times their weight in deionized water. However, this value dropped to 3.5 when the film was soaked in a 0.9% (w/w) NaCl solution. The films were also soaked 4 times in deionized water, and each soaking resulted in a reduced water uptake capacity. The temperature of film formation had no effect on the final water uptake properties. Also, thinner films had higher concentrations of sulfate groups than thicker films; this resulted in higher water uptake values. In addition, sulfated gluten films had comparable glass‐transition temperatures but lower thermal stabilities than the neat gluten films. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis of Bisindolylmethanes and Their Cytotoxicity Properties

Polymer supported dichlorophosphate (PEG-OPOCl₂) is an efficient green catalyst for the electrophilic substitution reaction of indole with aromatic aldehydes, in neat condition, to afford an excellent yield of bis(indolyl) methanes with short reaction time, at room temperature. The synthesized compounds and their anti-cancer activity are evaluated.     

Modification of wheat gluten with citric acid to produce superabsorbent materials

Wheat gluten was reacted with citric acid to produce natural superabsorbent materials able to absorb up to 78 times its weight in water. The properties of the modified gluten samples were characterized using Fourier Transform Infra‐red (FTIR) spectroscopy, thermogravimetric analysis, and water uptake. The reaction between gluten and citric acid was examined for gluten : citric acid ratios of 0.38 : 1 to 0.75 : 1 at temperatures from 100 to 130°C. More citric acid reacted for samples containing higher citric acid concentrations and at higher temperatures. FTIR analyses indicated the presence of carboxylate groups on the modified gluten samples, which resulted in modified samples having higher water uptake values than neat gluten. The sample with a gluten:citric acid ratio of 0.5 : 1 and reaction temperature of 120°C had the largest water uptake value. Also, all modified gluten samples had lower thermal stability than neat gluten. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Medicinal importance of grapefruit juice and its interaction with various drugs

Grapefruit juice is consumed widely in today's health conscious world as a protector against cardiovascular diseases and cancers. It has however, been found to be an inhibitor of the intestinal cytochrome P – 450 3A4 system, which is responsible for the first pass metabolism of many drugs. The P – glycoprotein pump, found in the brush border of the intestinal wall which transports many of these cytochrome P – 450 3A4 substrates, has also been implicated to be inhibited by grapefruit juice. By inhibiting these enzyme systems, grapefruit juice alters the pharmacokinetics of a variety of medications, leading to elevation of their serum concentrations. Most notable are its effects on the calcium channel antagonist and the statin group of drugs. In the case of many drugs, the increased serum concentration has been found to be associated with increased frequency of dose dependent adverse effects. In this review, we have discussed the phytochemistry of grapefruit juice, the various drugs involved in the drug – grapefruit juice eraction with their mechanisms of action and have presented the clinical implications of these interactions.