QoS provisioning in micro-cellular networks supporting multiple classes of traffic

We introduce an adaptive call admission control mechanism for wireless/mobile networks supporting multiple classes of traffic, and discuss a number of resource sharing schemes which can be used to allocate wireless bandwidth to different classes of traffic. The adaptive call admission control reacts to changing new call arrival rates, and the resource sharing mechanism reacts to rapidly changing traffic conditions in every radio cell due to mobility of mobile users. In addition, we have provided an analytical methodology which shows that the combination of the call admission control and the resource sharing schemes guarantees a predefined quality-of-service to each class of traffic. One major advantage of our approach is that it can be performed in a distributed fashion removing any bottlenecks that might arise due to frequent invocation of network call control functions.     

Nonlinear interactive analysis of cooling tower–foundation–soil interaction under unsymmetrical wind load

This paper deals with physical and material modelling of a cooling tower–foundation–soil system. The physical modelling has been carried out using solid 20-noded isoparametric element to model the cooling tower, annular raft foundation and soil media. The cooling tower–foundation–soil system was analysed under vertical and lateral load generated due to self-weight and wind loads. The soil nonlinearity has been taken into consideration using hyperbolic nonlinear elastic constitutive law. The response of the structure has been investigated with respect to displacement and stresses. Moreover, an attempt has been made to study the effect of the linear and nonlinear interactive analyses compared with conventional analysis. It was seen that the interactive analysis of the cooling tower–foundation–soil media plays a major role in releasing the stresses in the cooling tower, particularly at the bottom ring beam.     

First-principles study of hydrogen storage on Si atoms decorated C60

Hydrogen storage capacity of Si_nC₆₀ is studied via first-principles theory based on DFT and Canonical Monte Carlo Simulation (CMCS). It is shown that Si atoms strongly prefer D-site rather than other sites and in these structures maximum number of hydrogen molecule onto any Si atom is one. Each Si atom adsorbs one hydrogen molecule in molecular form and with proper binding energies when Si atom is placed in any D-site of C₆₀. Si atoms enhance remarkably hydrogen storage capability in fullerene.     

Effect of Saturated/Unsaturated Fatty Acid Ratio on Physicochemical Properties of Palm Olein–Olive Oil Blend

Although blending polyunsaturated oil with more saturated or monounsaturated oils has been studied extensively, there is no similar information regarding the partial replacement of palm olein with olive oil (OO). Therefore the main objective of this study was to investigate the effects of OO partial replacement (0, 25, 50, 75, 90 and 100% w/w) on the chemical stability of palm olein oil (POO). The physicochemical properties of oil samples namely iodine value, peroxide value (PV), anisidine value, TOTOX value (total oxidation value, TV), free fatty acid (FFA), cloud point, color and viscosity were considered as response variables. Significant differences among the oil blend properties were determined at the significance level of P < 0.05. Apart from FFA, all the response variables were significantly influenced by type and concentration of oils. The oil blend containing 10% POO and 90% OO showed the highest TV (6.10); whereas the blend containing 90% POO and 10% OO exhibited the least TV (2.41). This study indicated that the chemical stability of oil blend significantly (P < 0.05) increased with increasing the proportion of polyunsaturated/monounsaturated fatty acid.     

A resource estimation and call admission algorithm for wirelessmultimedia networks using the shadow cluster concept

The shadow cluster concept can be used to estimate future resource requirements and to perform call admission decisions in wireless networks. Shadow clusters can be used to decide if a new call can be admitted to a wireless network based on its quality-of-service (QoS) requirements and local traffic conditions. The shadow cluster concept can especially be useful in future wireless networks with microcellular architectures where service will be provided to users with diverse QoS requirements. The framework of a shadow cluster system is completely distributed, and can be viewed as a message system where mobile terminals inform the base stations in their neighborhood about their requirements, position, and movement parameters. With this information, base stations predict future demands, reserve resources accordingly, and admit only those mobile terminals which can be supported adequately. The shadow cluster concept involves some processing and communication overheads. These overheads have no effect on wireless resources, but only on the base stations and the underlying wireline network. It is shown how base stations determine the probabilities that a mobile terminal will be active in other cells at future times, define and maintain shadow clusters by using probabilistic information on the future position of their mobile terminals with active calls, and predict resource demands based on shadow cluster information. In addition, a call admission algorithm is introduced, which uses current traffic and bandwidth utilization conditions, as well as the amount of resources and maximum allowable “dropping probability” being requested. Performance results showing the advantages of the shadow cluster concept are also included     

PARO: Supporting Dynamic Power Controlled Routing in Wireless Ad Hoc Networks

This paper introduces PARO, a dynamic power controlled routing scheme that helps to minimize the transmission power needed to forward packets between wireless devices in ad hoc networks. Using PARO, one or more intermediate nodes called redirectors elects to forward packets on behalf of source–destination pairs thus reducing the aggregate transmission power consumed by wireless devices. PARO is applicable to a number of networking environments including wireless sensor networks, home networks and mobile ad hoc networks. In this paper, we present the detailed design of PARO and evaluate the protocol using simulation and experimentation. We show through simulation that PARO is capable of outperforming traditional broadcast-based routing protocols (e.g., MANET routing protocols) due to its energy conserving point-to-point on-demand design. We discuss our experiences from an implementation of the protocol in an experimental wireless testbed using off-the-shelf radio technology. We also evaluate the impact of dynamic power controlled routing on traditional network performance metrics such as end-to-end delay and throughput.     

End to end QoS provisioning multimedia wireless/mobile networksusing an adaptive framework

This article presents a framework for multimedia networking in a wireless and mobile environment. We consider both multimedia application needs as well as networking requirements, and try to bridge these paradigms using an adaptive framework. Central to this framework is the concept of representing a multimedia connection in terms of multiple substreams each with their own specified QoS requirement and making network elements (switching and access points), services, and protocols (signaling, control, routing) aware of the QoS requirements of such substreams. As resource availability in the wireless and mobile network fluctuates, the network selects and schedules substreams in order to present the information content with an acceptable quality at a receiver (or each receiver in case of multicast connections). This is done while achieving a reasonable utilization efficiency of network resources and sharing them in a fair manner     

Distributed call admission control in mobile/wireless networks

The major focus of this paper is distributed call admission control in mobile/wireless networks, the purpose of which is to limit the call handoff dropping probability in loss systems or the cell overload probability in lossless systems. Handoff dropping or cell overload are consequences of congestion in wireless networks. Our call admission control algorithm takes into consideration the number of calls in adjacent cells, in addition to the number of calls in the cell where a new call request is made, in order to make a call admission decision. This is done by every base station in a distributed manner without the involvement of the network call processor. The admission condition is simple enough that the admission decision can be made in real time. Furthermore, we show that our distributed call admission control scheme limits the handoff dropping or the cell overload probability to a predefined level almost independent of load conditions. This is an important requirement of future wireless/mobile networks with quality-of-service (QoS) provisioning     

Sustainable production of pectin from lime peel by high hydrostatic pressure treatment

The application of high hydrostatic pressure technology for enzymatic extraction of pectin was evaluated. Cellulase and xylanase under five different combinations (cellulase/xylanase: 50/0, 50/25, 50/50, 25/50, and 0/50 U/g lime peel) at ambient pressure, 100 and 200 MPa were used to extract pectin from dried lime peel. Extraction yield, galacturonic acid (GalA) content, average molecular weight (M_w,ave), intrinsic viscosity [η]_w, and degree of esterification (DE) were compared to those parameters obtained for pectins extracted using acid and aqueous processes. Pressure level, type and concentration of enzyme significantly (p < 0.05) influenced yield and DE of pectin. Enzyme and high pressure extraction resulted in yields which were significantly (p < 0.05) higher than those using acid and aqueous extraction. Although pressure-induced enzymatic treatment improves pectin yield, it does not have any significant effect on M_w,ave and [η]_w of pectin extracts indicating the potential of high pressure treatment for enzymatic pectin production as a novel and sustainable process.