Improving energy efficiency of incremental relay based cooperative communications in wireless body area networks

In this paper, we investigate the energy efficiency of an incremental relay based cooperative communication scheme in wireless body area networks (WBANs). We derive analytical expressions for the energy efficiency of direct and cooperative communication schemes taking into account the effect of packet error rate. The following communication scenarios specific to a WBAN are considered: (i) in‐body communication between an implant sensor node and the gateway, and (ii) on‐body communication between a body surface node and the gateway with line‐of‐sight (LOS) and non‐LOS channels. The results reveal a threshold behavior that separates regions where direct transmission is better from regions where incremental relay cooperation is more useful in terms of energy efficiency. It is observed that, compared with direct communication, incremental relay based cooperative communication schemes improves the energy efficiency significantly. Further, cooperation extends the source‐to‐destination hop length over, which energy efficient communication can be achieved as compared with direct communication. We also observe that, for both direct as well as cooperative transmission schemes in error prone channels, an optimal packet size exists that result in maximum energy efficiency. Copyright © 2013 John Wiley & Sons, Ltd.     

Variable Beam Width Selection for Improving the Throughput of IEEE 802.11ad Wireless LAN in the Contention Based Access Period

The hybrid MAC protocol specified by IEEE 802.11ad for millimeter wave wireless LANs consist of carrier sense multiple access/collision avoidance (CSMA/CA) during the contention based access periods (CBAPs) and TDMA during the service periods. To provide channel access during CBAP, the coverage area around the access point (AP) can be divided into several quasi omni (QO) beam levels. When uplink channel access during CBAP is considered, every directional multigigabit station residing within a QO level uses CSMA/CA protocol for getting the transmission opportunity. With equal beam width receive QO levels at the AP, we present an analytical model to compute the uplink throughput of the network in the CBAP, by closely following the 802.11ad MAC protocol specifications. We demonstrate that PHY layer MCS (modulation and coding scheme) dependent adaptive selection of QO levels can improve the throughput performance. In the second part of the paper, we consider that PCP/AP can have at most three radios, each tuned to operate in non-overlapping frequency bands as specified by 802.11ad PHY. We establish that such an arrangement can lead to concurrent transmissions in the network and improve the uplink throughput performance.     

Improved Merkle Hash Tree-Based One-Time Signature Scheme for Capability-Enhanced Security Enforcing Architecture for Named Data Networking

The concept of network caching is determined to be the potential requirement of named data networks (NDN) for enhancing the capabilities of the traditional IP networking. It is responsible for location independent data accesses and optimal bandwidth utilization in multi-path data dissemination. However, the network caching process in NDN introduces security challenges such as content cache poisoning, malicious injection or flooding of the packets and violation in accessing content packets. In this paper, an Improved Merkle Hash Tree-based one-time signature scheme for capability-enhanced security enforcing architecture (IMHT-OTSS-CSEA) is proposed for provisioning data authenticity in a distributed manner for leveraging the capabilities to inform the access privileges of the packets during the process of data dissemination. It is proposed for permitting the routers to verify the forwarded packets’ authenticity in NDN. It is capable in handling the issues that emerge from unsolicited packets during a flooding-based denial of service attacks by supporting the indispensable verification process in routers that confirms the timeliness of packets. The simulation experiments conducted using the open source CCNs platform and Planetlab confirmed a significant mean reduction in delay of 14.61%, superior to the benchmarked schemes. It is identified to minimize the delay incurred in generating bit vectors by a average margin of 13.06%, excellent to the baseline approaches. It also confirmed a mean increase in the true positive rate of 5.42%, a mean increase in the precision rate of 6.04%, decrease in false positive rate of 6.82% and increase in F-measure of 5.62% compared to the baseline approaches in the context of detecting content cache pollution attack respectively.

     

Improved Room Temperature Plasticity of Zr41.2Ti13.8Cu12.5Ni10Be22.5 Bulk Metallic Glass by Channel‐Die Compression

In this work, the effect of channel‐die compression (CDC) on the mechanical behavior of the Zr_41.2Ti_13.8Cu_12.5Ni₁₀Be_22.5 bulk metallic glass is analyzed. The results indicate that CDC can be successfully used as a pre‐deformation process to effectively enhance the room temperature plastic strain ability of metallic glasses. The origin of the improved mechanical properties is most likely due to the creation during CDC of a heterogenous microstructure consisting of hard and soft regions able to hinder the rapid propagation of shear bands.     

An investigation over the effect of the reducing agent on the properties of the ZnO-reinforced Ni–P coatings

Journal of Materials Science: Materials in Electronics - Electroless ZnO-reinforced Ni–P coatings are developed on mild steel substrates in the Electroless bath, which contains an optimum...     

Effect of modified starch from sweet potato as a fat replacer on the quality of reduced fat ice creams

In the present study, application of different levels (0, 1 and 2%) of citric acid treated sweet potato starch as a fat replacer (FR) in a high (11% fat), medium (6% fat) and low-fat (1%) ice creams were investigated. Results indicated that hardness value tends to improve with the addition of 1% FR in all reduced fat ice creams. During 60 days of storage, a decreasing trend was noticed in overrun, acidity and hardness values of ice cream samples. Overall score of sensory conveyed that the reduced fat ice creams with 1% FR (medium fat ice cream and low fat ice cream) were found to be very acceptable by sensory panels with a similar physicochemical characteristics and acceptance as high-fat ice cream (control) at the end of storage period. Citric acid treated sweet potato starch proved to be a promising alternative as a fat replacer in the ice cream production.     

Effect of modified atmosphere packaging on structural and physical changes in buffalo meat

The effect of modified atmosphere packaging of buffalo meat on the structural parameters viz., fibre diameter, sarcomere length and myofibrillar fragmentation index and physical parameters viz., pH, drip loss and colour scores were studied. The buffalo meat was packed under aerobic, vacuum and modified atmosphere (80% oxygen+20% carbon dioxide) and stored at 4±1°C upto 21 days. The results obtained revealed that vacuum-packed buffalo meat had the lowest fibre diameter and myofibrillar fragmentation index and the highest sarcomere length, vacuum thus appears to enhance ageing. Buffalo meat packed in modified atmosphere had a low drip loss and a desirable colour. The modified atmosphere packed and vacuum-packed buffalo meat was acceptable for upto 14 days at 4±1°C.     

Fat Mimicking Properties of Citric Acid Treated Sweet Potato Starch

Fat mimicking properties of citric acid treated sweet potato starch were investigated in this present study. Citric acid treated sweet potato starch was prepared by treating the native sweet potato starch with 3% citric acid for 6 h at a temperature of 45°C. Dextrose equivalent value of citric acid treated sweet potato starch was 2.05%. A significant increase in amylose content was noticed in citric acid treated sweet potato starch possibly due to the lyses of amylopectin fractions. The melting temperature of citric acid treated sweet potato starch was 51.44°C, which was close to the melting point of fat. Citric acid treated sweet potato starch exhibited superior water holding capacity and in vitro digestibility. Gel strength and enthalpy (?H) of citric acid treated sweet potato starch were comparatively lower than native sweet potato starch; correspondingly, citric acid treated sweet potato starch confirmed a low pasting profile. Native sweet potato starch and citric acid treated sweet potato starch exhibited a shear-thinning behavior. Acid treatment did not alter the granule size of native sweet potato starch (≈8 µm). Hence, this study concluded that citric acid treated sweet potato starch would be used as a potential fat replacer in food preparations due to its fat mimicking properties.