A quality of service aware cross-layer approach for wireless ad hoc networks with smart antennas

Recent technological advances have led to a growing interest in multi-antenna wireless ad hoc networks in which each node has more than one antenna. This paper proposes a cross-layer approach called QoS-aware smart antenna protocol (QSAP) for such networks that assures quality of service (QoS) needs of applications with reduced energy consumption. The proposed scheme adaptively allocates the degrees of freedom present in the multi-antenna system at each node to reduce the transmit energy while meeting the QoS needs of the application. The effectiveness of the proposed approach is demonstrated through simulations. The simulations show that the cross-layer aspects of the proposed approach result in considerable energy savings compared to schemes which meet the QoS needs without the cross-layer interaction.     

Some aspects of unsaturated flow in jointed rock

The applicability of Darcy's Law to two-phase flow has been discussed. Specialised triaxial equipment has been employed to separately inject two pore fluid components (air and water) into fractured rock specimens, so that two-phase flow behaviour can be studied at high axial and confining stresses. Improvements to recently developed two-phase high-pressure triaxial apparatus have enabled the authors to continue their study of air–water (i.e. unsaturated) flow in intact and fractured rock specimens under a wide range of stress conditions, similar to those encountered in underground mining operations. In this paper, a simplified stratified two-phase flow model is also presented that satisfactorily predicts flow behaviour in an inclined rock fracture over a range of linear laminar flow for particular capillary pressure relationships. The mathematical model is based upon the principles of conservation of mass and momentum, and relates the fracture aperture (e_t) to phase permeability (k_i) using Poiseuille's law and the proposed ‘phase height’, h_i(t), for water and air phases. The experimental approach used to verify the model predictions is described and the predicted results compared with the measurements. The experimental data confirmed the relationship between relative permeability and flow rate, with respect to two-phase flow conditions.     

Temperature-adaptive voltage tuning for enhanced energy efficiency in ultra-low-voltage circuits

Circuits optimized for minimum energy consumption operate typically in the subthreshold regime with ultra-low power-supply voltages. Speed of a subthreshold logic circuit is enhanced with an increase in the die temperature. The excessive timing slack observed in the clock period of subthreshold logic circuits at elevated temperatures provides opportunities to lower the active-mode energy consumption. A temperature-adaptive dynamic-supply voltage-tuning technique is proposed in this paper to reduce the high-temperature energy consumption without degrading the clock frequency in ultra-low-voltage subthreshold logic circuits. Results indicate that the energy consumption can be lowered by up to 40% by dynamically scaling the supply voltage at elevated temperatures. An alternative technique based on temperature-adaptive reverse body bias to exponentially reduce the subthreshold leakage currents at elevated temperatures is also investigated. The active-mode energy consumption with two temperature-adaptive voltage-tuning techniques is compared. The impact of the process parameter and supply voltage variations on the proposed temperature-adaptive voltage scaling techniques is evaluated.     

Dual Functional Modification of Alkaline Amino Acids Induces the Self‐Assembly of Cylinder‐Like Tobacco Mosaic Virus Coat Proteins into Gear‐Like Architectures

Herein, the assembly of 3D uniform gear‐like architectures is demonstrated with a tobacco mosaic virus (TMV) disk as a building block. In this context, the intrinsic behavior of the TMV disk that promotes its assembly into nanotubes is altered by a synergistic effect of dual functional modifications at the 53rd arginine mutation and the introduction of lysine groups in the periphery at 1st and 158th positions of the TMV disk, which results in the formation of 3D gear‐like superstructures. Therein, the 53rd arginine moiety significantly strengthens the linkage between TMV disks in the alkaline environment through hydrogen bond interactions. The charge of lysine‐modified lateral surfaces is partially neutralized in the alkaline solution, which induces the TMV disk to form a gear‐like architecture to maintain its structural stability by exploiting the electrostatic repulsion between neighboring TMV disks. This study not only provides explicit evidence regarding the molecular‐level understanding of how the modification of site‐specific amino acid affects the assembly of resultant superstructures but also encourages the fabrication of functional protein‐based nanoarchitectures.     

Poly-L-ornithine/fucoidan-coated calcium carbonate microparticles by layer-by-layer self-assembly technique for cancer theranostics

Recently, the layer-by-layer (LbL) self-assembly technology has attracted the enormous interest of researchers in synthesizing various pharmaceutical dosage forms. Herewith, we designed a biocompatible drug delivery system containing the calcium carbonate microparticles (CaCO₃ MPs) that coated with the alternatively charged polyelectrolytes, i.e., poly-L-ornithine (PLO)/fucoidan by LbL self-assembly process (LbL MPs). Upon coating with the polyelectrolytes, the mean particle size of MPs obtained from SEM observations increased from 1.91 to 2.03?μm, and the surface of LbL MPs was smoothened compared to naked CaCO₃ MPs. In addition, the reversible zeta potential changes have confirmed the accomplishment of layer upon a layer assembly. To evaluate the efficiency of cancer therapeutics, we loaded doxorubicin (Dox) in the LbL MPs, which resulted in high (69.7%) drug encapsulation efficiency. The controlled release of Dox resulted in the significant antiproliferative efficiency in breast cancer cell line (MCF-7 cells), demonstrating the potential of applying this innovative drug delivery system in the biomedical field.     

Investigation of structural,mechanical and magnetic characterization of electroplated W deposited NiMo thin films

Journal of Materials Science: Materials in Electronics - In the current research work, NiMo thin films were successfully co-deposited with W on the copper substrate (NiMoW) by varying the plating...     

Watch to Edit: Video Retargeting using Gaze

We present a novel approach to optimally retarget videos for varied displays with differing aspect ratios by preserving salient scene content discovered via eye tracking. Our algorithm performs editing with cut, pan and zoom operations by optimizing the path of a cropping window within the original video while seeking to (i) preserve salient regions, and (ii) adhere to the principles of cinematography. Our approach is (a) content agnostic as the same methodology is employed to re‐edit a wide‐angle video recording or a close‐up movie sequence captured with a static or moving camera, and (b) independent of video length and can in principle re‐edit an entire movie in one shot. Our algorithm consists of two steps. The first step employs gaze transition cues to detect time stamps where new cuts are to be introduced in the original video via dynamic programming. A subsequent step optimizes the cropping window path (to create pan and zoom effects), while accounting for the original and new cuts. The cropping window path is designed to include maximum gaze information, and is composed of piecewise constant, linear and parabolic segments. It is obtained via L(1) regularized convex optimization which ensures a smooth viewing experience. We test our approach on a wide variety of videos and demonstrate significant improvement over the state‐of‐the‐art, both in terms of computational complexity and qualitative aspects. A study performed with 16 users confirms that our approach results in a superior viewing experience as compared to gaze driven re‐editing [ JSSH15 ] and letterboxing methods, especially for wide‐angle static camera recordings.     

An Investigation of Secret Key Generation for Physical Layer Security Using Wavelet Packets

Wireless Personal Communications - This work investigates the effectiveness of wavelet packets in dynamic secret key generation (DSKG) for physical layer security (PLS). Preprocessing channel...     

Symptotics: a framework for estimating the scalability of real-world wireless networks

We present a framework for non-asymptotic analysis of real-world multi-hop wireless networks that captures protocol overhead, congestion bottlenecks, traffic heterogeneity and other real-world concerns. The framework introduces the concept of symptotic scalability to determine the number of nodes to which a network scales, and a metric called change impact value for comparing the impact of underlying system parameters on network scalability. A key idea is to divide analysis into generic and specific parts connected via a signature—a set of governing parameters of a network scenario—such that analyzing a new network scenario reduces mainly to identifying its signature. Using this framework, we present the first closed-form symptotic scalability expressions for line, grid, clique, randomized grid and mobile topologies. We model both TDMA and 802.11, as well as unicast and broadcast traffic. We compare the analysis with discrete event simulations and show that the model provides sufficiently accurate estimates of scalability. We show how our impact analysis methodology can be used to progressively tune network features to meet a scaling requirement. We uncover several new insights, for instance, on the limited impact of reducing routing overhead, the differential nature of flooding traffic, and the effect real-world mobility on scalability. Our work is applicable to the design and deployment of real-world multi-hop wireless networks including community mesh networks, military networks, disaster relief networks and sensor networks.