Broadcasting in multi-radio multi-channel wireless networks using simplicial complexes

We consider the broadcasting problem in multi-radio multi-channel ad hoc networks. The objective is to minimize the total cost of the network-wide broadcast, where the cost can be of any form that is summable over all the transmissions (e.g., the transmission and reception energy, the price for accessing a specific channel). Our technical approach is based on a simplicial complex model that allows us to capture the broadcast nature of the wireless medium and the heterogeneity across radios and channels. Specifically, we show that broadcasting in multi-radio multi-channel ad hoc networks can be formulated as a minimum spanning problem in simplicial complexes. We establish the NP-completeness of the minimum spanning problem and propose two approximation algorithms with order-optimal performance guarantee. The first approximation algorithm converts the minimum spanning problem in simplical complexes to a minimum connected set cover (MCSC) problem. The second algorithm converts it to a node-weighted Steiner tree problem under the classic graph model. These two algorithms offer tradeoffs between performance and time-complexity. In a broader context, this work appears to be the first that studies the minimum spanning problem in simplicial complexes and weighted MCSC problem.     

Radial Sub-band Allocation with Downlink Interference Mitigation in Macro–Femto Environment

Wireless Personal Communications - Femtocell deployment is an important strategy when it comes to improvement of QoS metrics in areas of poor cell coverage like indoors in an LTE environment. This,...     

Mobile web for under-privileged in developing countries

In developing nations, Internet infrastructure in scarce; however, majority of people in developing countries also need access to information that matter for their daily life and livelihood. As cost of computers are higher than mobile phones and infrastructure for running computers by stable electricity is not widely available at many places of under developed and developing (hence, referred as developing) countries. One of the major options for under-privileged people in developing countries to access information is through mobile phone. A mobile device with GPRS for access to Internet services is still expensive for a common man to afford in developing countries. Therefore, to offer mobile web for the developing countries, we need to look at SMS (Short Message Service) as transport bearer, which is cheaper and can support most of the actionable services (many important services which needs a few bytes to exchange the information). SMS as transport bearer has one constraints – it does not interoperate (i.e., a user belong to one service provider is not able to access services by SMS-data of another service provider). In this paper, we propose a routing algorithm that makes SMS-data interoperable. We also propose architecture for mobile web over SMS as transport bearer for seamless application access in roaming, number portability, and vehicular condition. Substantial researches have been done on performance of TCP/IP for wireless web that mainly focused on three applications viz., file transfer, Electronic mail, and World Wide Web. This paper presents performance of actionable information through online transaction over TCP/IP and SMS under similar conditions; it shows SMS is not at a disadvantage compared to TCP/IP.     

Design and performance of a planar star mixer

This paper describes the realization of a hybrid star mixer as a planar circuit. The mixer has a minimum conversion loss of 5 dB and, for a conversion loss of less than 9 dB, spans over 2.2 GHz in IF bandwidth and 8 GHz in RF/LO bandwidth. The mixer employs a novel, planar balun structure, similar to conductor-backed CPW, that is suitable for realization as a monolithic circuit     

Chemotactic migration of leucocytes through corneal layers: an in vitro study

The ability of polymorphonuclear leucocytes (PMNs) to migrate into the different corneal layers in the presence or absence of a chemotactic stimulus was investigated in rabbits. The epithelial and/or endothelial surfaces were damaged in some corneas and in others they were intact. One side of the cornea was kept in contact with a viable population of rabbit PMNs and the other side with a chemotactic agent (zymosan activated human serum). The migration of PMNs into the cornea was traced histologically. The PMNs could not penetrate intact epithelium and Descemet's membrane even under the influence of a chemotactic stimulus. The stroma allowed PMN migration only when the chemotactic agent was present. The endothelium offered no resistance to PMN invasion whether the chemotactic stimulus was present or not.     

Development of Apparels from Silk Waste and Pineapple Leaf Fiber

The degummed mulberry silk waste and eri silk waste were blended with degummed and bleached pineapple leaf fibers (PALF) at fiber stage in different proportions, and spun into yarn in a jute spinning system. The 90-tex blended yarn thus developed was analyzed for different physico-mechanical properties. Properties of fabric developed in a traditional handloom using 2/40-s cotton as warp and blended yarn as weft were also analyzed. The quality parameters, viz., tensile property, crease recovery, fabric cover, stiffness, drape, and thickness of the developed fabric, met essential apparel requirements. A comparative subjective evaluation of the fabric quality, viz., aesthetic appearance, luster, and texture, was made with the help of a group of people from different age, educational, and occupational background to examine its marketability; all respondents felt that appearance of PALF with silk waste was excellent. Texture and luster were found to be from medium to moderate. About 95% of respondents felt that fabric was crispy.     

Potentiality of Indian pineapple leaf fiber for apparels

The use of textile-grade fiber extracted from the Indian pineapple leaf is an unexplored area. Pineapple leaf fiber (PALF) is fine, soft, and moderately strong and is much acceptable for fashion garment. An attempt has been made to extract and soften Indian PALF from the pineapple leaves by decortication and subsequent water retting. Decorticated cum retted fiber has shown better physicomechanical and surface appearance properties than decorticated fiber. Fine yarn (38 tex) was spun in a suitable spinning system, and the property performance was found to be suitable to make eco-sustainable novelty fabric. Fabric was developed by using cotton as warp yarn and PALF-based yarn as weft in a handloom. The developed fabric shows very good physical and mechanical properties, desired for apparels. This inferred that Indian PALF may be successfully used to make eco-niche apparel quality fabric as well as novelty textiles.     

Rheological, textural and spectral characteristics of sorbitol substituted mango jam

Full replacement of sucrose with sorbitol is feasible in mango jam manufacturing. Dynamic rheological tests characterized mango jam manufactured with sucrose/sorbitol as a weak gel. Mango jam did not follow Cox-Merz or modified Cox-Merz rule. The storage- and loss- moduli increased with sucrose concentration up to 60%, but decreased at higher sucrose concentrations. Gel strength decreased with increasing sorbitol concentration because of weaker junction zones in pectin gel network. FTIR spectra revealed that C-O and C-C stretching vibrations are indicators of the gel strength because pectin polymeric chain network formation in fruit jam is due to hydrogen bonding and hydrophobic interactions.     

Studies on the effect of thiuram disulfide on NR vulcanization accelerated by thiazole-based accelerator systems

Thiuram disulfides form synergistic combinations with thiazole and thiazole-based accelerators, namely, N-cyclohexy-2-benzothiazole sulfenamide (CBS), 2-mercaptobenzothiazole(MBT), and 2-mercaptobenzothiazyl disulfide (MBTS). Unfortunately, widely used thiuram disulfides (TD) generate carcinogenic N-nitrosoamine. It is reported that the nitrosamines from N-methylpiperazine and dibenzylamine are free from this menace. So, some investigations were carried out with the binary combinations of each of bis(N-methylpiperazino)thiuram disulfide (MPTD), tetrabenzylthiuram disulnde (TBzTD), and tetramethyl-thiuram disulfide (TMTD) separately with CBS, MBT, and MBTS. It was observed that all the TD are activated by the CBS, MBT, or MBTS in the combinations studied. The intensity of activation is manifested in the enhancement of torque, modulus, tensile strength, cure rate, hardness, and decrease of elongation at break values and is very much dependent upon the ratio of the accelerators used. Considering the torque, modulus, tensile strength, and the elongation at break values, it apears that MPTD and TBzTD are capable of competing with the hitherto unbeaten TMTD as suitable accelerators for the vulcanization of rubber. Some investigations in respect to heat- and age-resistance behavior have also been carried out and the observed differences in the activities of various binary combinations have been explained through a mechanism. The results obtained with filled vulcanizates indicate that the binary systems comprising TD and MBTS provide fruitful results of which the TBzTD–MBTS combination seems to give the best cure and physical data for practical vulcanizates. © 1996 John Wiley & Sons, Inc.