Energy‐delay‐aware caching strategy in green CCN using markov approximation

One of the basic challenges in content‐centric networking (CCN) is how to optimize the overall energy consumption of content transmission and caching. Furthermore, designing an appropriate caching policy that considers both energy consumption and quality of service (QoS) is a major goal in green CCN. In this paper, the problem of minimizing the total CCN energy consumption while being aware of the end‐to‐end delay is formulated as an integer linear programming model. Since it is an Non‐deterministic Polynomial‐time (NP)‐hard problem, the Markov approximation method for an energy‐delay aware caching strategy (MAEDC) is proposed through a log‐sum‐exp function to find a near‐optimal solution in a distributed manner. The numerical results show that the MAEDC achieves near‐optimal energy consumption with better delay profile compared with the optimal solution. Moreover, due to the possibility of distributed and parallel processing, the proposed method is proper for the online situation where the delay is a crucial issue.     

Provably correct control flow graphs from Java bytecode programs with exceptions

We present an algorithm for extracting control flow graphs from Java bytecode that captures normal as well as exceptional control flow. We prove its correctness, in the sense that the behaviour of the extracted control flow graph is a sound over-approximation of the behaviour of the original program. This makes control flow graphs suitable for performing various static analyses, such as model checking of temporal safety properties. Analysing exceptional control flow for Java bytecode is difficult because of the stack-based nature of the language. We therefore develop the extraction in two stages. In the first, we abstract away from the complications arising from exceptional flows, and relativize the extraction on an oracle that is able to look into the stack and predict the exceptions that can be raised at each instruction. This idealized algorithm provides a specification for concrete extraction algorithms, which have to provide a suitable implementation for the oracle. We prove correctness of the idealized algorithm by means of behavioural simulation. In the second stage, we develop a concrete extraction algorithm that consists of two phases. In the first phase, the program is transformed into a BIR program, a stack-less intermediate representation of Java bytecode, from which the control flow graph is extracted in the second phase. We use this intermediate format because it provides the information needed to implement the oracle, and since it gives rise to more compact graphs. We show that the behaviour of the control flow graph extracted via the intermediate representation is a sound over-approximation of the behaviour of the graph extracted by the direct, idealized algorithm, and thus of the original program. The concrete extraction algorithm is implemented as the ConFlEx tool. A number of test cases are performed to evaluate the efficiency of the algorithm.     

Precise analytical evaluation of the ring shape anchored contour mode disk resonator for constructing a low noise UHF Pierce oscillator

This paper presents an analytical evaluation of the previously demonstrated Ring Shape Anchored Contour Mode Disk (RSACMD) resonator and extracts its equivalent electrical circuit. In the next step, a series resonant Pierce oscillator is designed and parameterized based on the calculated MEMS characteristics. Due to the inherent 180° of phase shift in the RSACMD resonator equivalent circuit, a modified version of a Pierce sustaining circuit is introduced with two inverters (instead of one inverter in conventional Pierce oscillators) to compensate that extra phase shift and satisfy Barkhausen criteria. The designed circuit presents excellent phase noise performance because of a special design which results in small frequency pulling and enable the circuit oscillate close to natural frequency of the high Q resonator. The overall circuit consumes less than 257 μW from a 1.8 V power supply.     

Predicting the flow stress behavior of Ni-42.5Ti-3Cu during hot deformation using constitutive equations

The hot deformation behavior of ternary Ni-42.5Ti-3Cu alloy was modeled. Hot compression tests were carried out at the temperatures from 800 °C to 1000°C and at the strain rates of 0.001 s^?1 to 1 s^?1. The experimental results were then used to determine the constants for developing constitutive equations. There was an unacceptable fitting between the predicted and experimental results using Zener-Hollomon parameter in a hyperbolic sinusoidal equation form. The mismatches among the experimental and predicted results were observed almost for all tested conditions. By modifying the Zener-Hollomon parameter for the compensation of strain rate, a very good agreement was achieved between the predicted values and experimental ones. Both predicted and experimental stress-strain curves illustrate the occurrence of dynamic recrystallization. Also, in both cases, the peak and steady state stresses raised with decrease of temperature and increase of strain rate. The very good agreement between the measured and predicted results indicates the high accuracy of developed model and constitutive equations which can be used for predicting and analyzing the hot deformation behavior of Ni-42.5Ti-3Cu.     

Investigation of the effect of presulphidation on coke deposition on 25Cr-35Ni alloy during ethane steam cracking

The process of hydrocarbons cracking is carried out in the presence of heat-resistant alloys Fe-Ni-Cr, which HP40 alloy (25Cr-35Ni) has the most applications among olefin plants. Since these alloys naturally tend to form coke, the industry has always tried to reduce the coke formation by reducing the catalytic properties of the coils. In this research, the effect of dimethyl disulphide (DMDS) concentration (200–900 ppm) on the HP40 alloy of industrial coils at the presulphidation stage is evaluated. In the presulphidation stage, the alloy surface is in contact with sulphur in the absence of hydrocarbons, and this affects the amount of coke formation in the cracking process. Also, the surface composition and morphology of coke are identified using EDX and SEM analysis. These results showed that at the 500 ppm concentration of DMDS, coke deposition is minimized. Additionally, our findings indicated that coke morphology has not changed under different presulphidation conditions, and coke is still a filament type, but the size of the filaments has changed. Moreover, the study of HP40 composition in both preoxidized and presulphide stages shows that presulphidation reduces the amount of Fe and Ni in the coke layer significantly.     

Investigation of inter‐relationship between tensile behavior and photocatalytic activity of an acrylic‐based composite upon UVA exposure

The aim of this work is to produce a photocatalytic pseudo‐paint for benzene removal from air and find the role of TiO₂ nanoparticles, TiO₂ pigment, and CaCO₃ extender on photocatalytic performance of this paint along with their role on stress–strain behavior after ultraviolet (UV) exposure. For this purpose, TiO₂ nanoparticles were dispersed into an indoor paint resin (i.e., copolymer acrylic–styrene). The impact of main components of the paint on photocatalytic oxidation (PCO) rate of benzene was studied. It was found that dispersion of nanoparticles had the most dramatic effect on photo activity of nanocomposite. TiO₂ pigment generally increased PCO rate and also made the paint more stable under tensile stress. CaCO₃ may increase and/or decrease PCO of benzene, whether there is pigment in the formulation or not. However, it does not generally contribute to making the formulation resistant to UV exposure. Nanoparticles bring PCO and mechanical strength into the paint, but fail to strengthen the composite against UV deterioration. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44447.     

Experimental investigation and mathematical modeling of oxygen permeation through dense Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF) perovskite-type ceramic membranes

Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3?δ (BSCF) perovskite powder was synthesized via EDTA/citrate complexation method. BSCF membranes were formed by pressing powder at 400 MPa and sintering at 1100 °C for 10 h. XRD patterns showed that a high pure powder with cubic structure was obtained. SEM micrographs revealed that the membranes are dense with large grains. Effects of temperature, feed and permeate side oxygen partial pressures, flow rates and membrane thickness on oxygen permeation flux were studied experimentally. A Nernst–Planck based mathematical model, including surface exchange kinetics and bulk diffusion, was developed to predict oxygen permeation flux. Considering non-elementary surface reactions and introducing system hydrodynamics into the model resulted in an excellent agreement (RMSD = 0.0617, AAD = 0.0487 and R² = 0.985) between predicted and measured fluxes. The results showed that oxygen permeation flux increases with temperature, feed side oxygen partial pressure and flow rates, however decreases with permeate side oxygen partial pressure and membrane thickness. Contribution of feed side surface exchange reactions, bulk diffusion and permeate side surface exchange reactions resistances in the total resistance are in the range of 8–32%, 10–81% and 11–59%, respectively. Permeation rate-limiting step was determined using the membrane dimensionless characteristic thickness.     

Hot Ductility of Severe Plastic Deformed AA6061 Aluminum Alloy

The hot ductility of 6061 aluminum alloy,which was subjected to two different severe plastic deformations(SPD),was studied at different temperatures and strain rates.The tensile tests were carried out at the temperature range of 300-500 ℃ and at the strain rates of 0.0005-0.01 s~(-1).The microstructure evolution was characterized using optical microscopy,transmission electron microscopy and X-ray diffraction technique.The influences of the microstructure after SPD,thermomechanical parameters(temperature and strain rate) and specimen size on the hot formability of this alloy were then analyzed.The results show that a decrease in grains/subgrains exhibited significant effect on the hot ductility of SPDed samples.The constitutive equations were then developed to model the hot formability of the studied alloy.The developed model can be represented by Zener-Hollomon parameter in a hyperbolic sinusoidal equation form.Both the changes of elongation to failure and Zener-Hollomon parameter indicate that the hot ductility of the alloy is more sensitive to the temperature rather than to the strain rate.The uniform elongation is independent of the specimen size,but the postnecking elongation increases dramatically as the ratio of l/A~(1/2) decreases.