False-Path Removal Using Delay Fault Simulation

Some false paths are caused by redundant stuck-at faults. Removal of those stuck-at faults automatically eliminates such false paths from the circuit. However, there are other false paths that are not associated with any redundant stuck-at fault. All segments of such a false path are shared with other testable paths. We focus on the elimination of this type of false paths. We use a non-enumerative path delay fault simulator based on the path status graph (PSG) data-structure, which duplicates selected gates to separate the detected and undetected path delay faults. The expanded circuit may contain new redundant stuck-at faults, corresponding to those undetected paths that are false. This happens because the expanded circuit has some new interconnects with only false paths passing through them. Such links become the sites for redundant stuck-at faults. Removal of these redundant faults eliminates false paths. The reported results show that the quality of the result may depend on the coverage of testable paths by the vectors that are simulated. When non-enumerative path delay simulation and implication-based redundancy removal techniques are used, the present procedure of false-path elimination can be applied to very large circuits.     

A cooling change-point model of community-aggregate electrical load

Estimates of daily electrical cooling load for a city of 800,000 are developed based on the relationship between weather variables and daily-average electricity consumption over 1 year. The relationship is found to be nearly linear above a threshold temperature. Temperature and humidity were found to be the largest, at 59%, and second largest, at 21%, contributors to electrical cooling load. Direct normal irradiation intercepted by a vertical cylinder, DNI sin θ, was found to be a useful explanatory variable when modeling aggregates of buildings without a known or dominant orientation. The best study case model used DNI sin θ and diffuse horizontal irradiation (DHI) as distinct explanatory variables with annual electrical cooling load contributions of 9% and 11% respectively. Although the seasonal variation in electrical cooling load is large - on peak summer days more than 1.5 times the winter base load - the combined direct and diffuse solar contribution is essentially flat through the year, a condition at odds with the common assumption that solar cooling always provides a good match between supply and demand. The final model gives an electrical cooling load estimate for Abu Dhabi Island that corresponds to 40% of the total annual electrical load and 61% on the peak day.     

Mechanical properties of amorphous silicon carbonitride thin films at elevated temperatures

The mechanical properties of amorphous silicon carbonitride (a-SiC _x N _y ) films with various nitrogen content (y = 0–40 at.%) were investigated in situ at elevated temperatures up to 650 °C in inert atmosphere. A SiC film was measured also at 700 °C in air. The hardness and elastic modulus were evaluated using instrumented nanoindentation with thermally stable cubic boron nitride Berkovich indenter. Both the sample and the indenter were separately heated during the experiments to temperatures of 300, 500, and 650 °C. Short duration high temperature creep tests (1200 s) of the films were also carried out. The results revealed that the room temperature hardness and elastic modulus deteriorate with the increase of the nitrogen content. Furthermore, the hardness of both the a-SiC and the a-SiCN films with lower nitrogen content at 300 °C drops to approx. 77 % of the corresponding room temperature values, while it reduces to 69 % for the a-SiCN film with 40 at.% of nitrogen. Further increase of temperature is accompanied with minor reduction in hardness except for the a-SiCN film with highest nitrogen content, where the hardness decreases at a much faster rate. Upon heating up to 500 °C, the elastic modulus of the a-SiCN film decreases, while it increases at 650 °C due to the pronounced effect of short-range ordering. The steady-state creep rate increases at elevated temperatures and the a-SiC exhibits slower creep rates compared to the a-SiCN films. The value of the universal constant x = 7 relating the W _p/W _t and H/E ^* was established and its applicability was demonstrated. Analysis of the experimental indentation data suggests a theoretical limit of hardness to elastic modulus ratio of 0.143.     

Packet Recycling and Delayed ACK for Improving the Performance of TCP over MANETs

Most of the schemes that were proposed to improve the performance of transmission control protocol (TCP) over mobile ad hoc networks (MANETs) are based on a feedback from the network, which can be expensive (require extra bandwidth) and unreliable. Moreover, most of these schemes consider only one cause of packet loss. They also resume operation based on the same stand-by parameters that might vary in the new route. Therefore, we propose two techniques for improving the performance of TCP over MANETs. The first one, called TCP with packet recycling (TCP-PR), allows the nodes to recycle the packets instead of dropping them after reaching the retransmission limit at the MAC layer. In the second technique, which is called TCP with adaptive delay window (TCP-ADW), the receiver delays sending TCP ACK for a certain time that is dynamically changed according to the congestion window and the trip time of the received packet. TCP-PR and TCP-ADW are simple, easy to implement, do not require network feedback, compatible with the standard TCP, and do not require distinguishing between the causes of packet loss. Our thorough simulations show that the integration of our two techniques improves the performance of TCP over MANETs.     

Trace elements‐based Auroshell gold@hematite nanostructure: Green synthesis and their hyperthermia therapy

Hyperthermia is an additional treatment method to radiation therapy/chemotherapy, which increases the survival rate of patients without side effects. Nowadays, Auroshell nanoparticles have attracted much attention due to their precise control over heat use for medical purposes. In this research, iron/gold Auroshell nanoparticles were synthesised using green nanotechnology approach. Auroshell gold@hematite nanoparticles were synthesised and characterised with rosemary extract in one step and the green synthesised nanoparticles were characterised by X‐ray powder diffraction, SEM, high‐resolution transmission electron microscopy, and X‐ray photoelectron spectroscopy analysis. Cytotoxicity of Auroshell iron@gold nanoparticles against normal HUVEC cells and glioblastoma cancer cells was evaluated by 2,5‐diphenyl‐2H‐tetrazolium bromide method, water bath hyperthermia, and combined method of water bath hyperthermia and nano‐therapy. Auroshell gold@hematite nanoparticles with minimal toxicity are safe against normal cells. The gold shell around the magnetic core of magnetite caused the environmental and cellular biocompatibility of these Auroshell nanoparticles. These magnetic nanoparticles with targeted control and transfer to the tumour tissue led to uniform heating of malignant tumours as the most efficient therapeutic agent.     

Symbolic analysis of large-scale networks using a hierarchical signal flowgraph approach

This paper presents an approach suitable for the symbolic analysis of large-scale active networks. The method depends on the partitioning of the network into smaller networks which are then symbolically analyzed noniteratively using the Mason's signal flowgraph models of each partition. The resulting solutions, which are reduced signal flowgraphs (transfer functions) for the subnetworks are then hierarchically combined to produce the final solution or solutions (transfer functions) for the entire system. The advantage of such an approach is the reduction in the number of symbolic terms compared to the conventional approaches, and the ability to analyze hybrid systems consisting of electrical and nonelectrical parts. The result of the analysis is a series of equations that have an upward hierarchical dependency on each other.     

Adaptive cross-layer MAC design for improved energy-efficiency in multi-channel wireless sensor networks

We present a novel cross-layer design for improving energy efficiency in a wireless sensor network that utilizes a multi-channel non-persistent CSMA MAC protocol with adaptive MQAM modulation at the physical layer. Cross-layer interactions are achieved through joint, traffic-dependent adaptation of the backoff probability at the MAC layer and the modulation order at the physical layer. The joint optimization of the backoff probability and the modulation order is conducted subject to a constraint on the packet retransmission delay. Such an optimization is shown to produce a significant improvement in the per-bit energy requirement for successful packet delivery. Our analytical findings are verified through numerical results and computer simulations.     

Effect of the preparation method on the surface coverage of Mo/Al2O3 catalysts

Two series of Mo/Al₂O₃ catalysts were prepared by equilibrium adsorption and incipient wetness impregnation methods. The effect of preparation method on the surface coverages of the calcined catalysts was investigated by the combined use of CO₂ chemisorption, low temperature CO adsorption and ion scattering spectroscopy (ISS). For a given Mo loading, the CO₂ and CO adsorption results showed little difference between the two preparation methods. As previously noted, the CO₂ chemisorption method overestimated the Mo surface coverage. In contrast to the adsorption methods, the ISS technique gave different Mo surface coverage values for a given Mo content of the two series of catalysts. This apparent discrepancy was attributed to different repartition of the Mo phase between the internal and external surfaces which can only be detected by ISS. This interpretation is supported by the observed agreement between the coverage values measured from ISS and low temperature CO adsorption for presumably uniform catalysts obtained by the equilibrium adsorption method.