Knowledge-based automation of a design method for concurrentsystems

This paper describes a knowledge-based approach to automate a software design method for concurrent systems. The approach uses multiple paradigms to represent knowledge embedded in the design method. Semantic data modeling provides the means to represent concepts from a behavioral modeling technique, called Concurrent Object-Based Real-time Analysis (COBRA), which defines system behavior using data/control flow diagrams. Entity-relationship modeling is used to represent a design metamodel based on a design method, called COncurrent Design Approach for Real-Time Systems (CODARTS), which represents concurrent designs as software architecture diagrams, task behavior specifications and module specifications. Production rules provide the mechanism for codifying a set of CODARTS heuristics that can generate concurrent designs based on semantic concepts included in COBRA behavioral models and on entities and relationships included in CODARTS design metamodels. Together, the semantic data model, the entity-relationship model, and the production rules, when encoded using an expert system shell, compose CODA, an automated designer's assistant. CODA is applied to generate 10 concurrent designs for four real-time problems. The paper reports the degree of automation achieved by CODA. The paper also evaluates the quality of generated designs by comparing the similarity between designs produced by CODA and human designs reported in the literature for the same problems. In addition, it compares CODA with four other approaches used to automate software design methods     

Proposed Approaches for Cooperative Cognitive Radio

This paper in this topic concentrates on an important part is spectrum sensing (SS). It can detect the idle hole in spectrum by detection methods. This paper uses the sensing technique is called energy detector(ED). The ED depends on only the energy of the signal without other needs such as the modulation of signal or pre-knowledge about the signal and this is considered as advantage. This research proposed new two techniques are the additive wavelet transform (AWT) with Homomorphic Way (HW) and Haar Discrete Wavelet Transform (HDWT) approach. We apply these techniques are applied in wide band wireless signal by using the Cognitive Radio (CR) network. Each technique reduces the noise of signal before enter to the detection method ED. The HW is considered new technique in the wireless communication. This study will have these techniques as hybrid with the ED to increase the throughput for the cognitive user with a sufficient protection to the PU transmission. Also, it improves the probability of detection and reduces the probability of false alarm and the probability of error. The cooperative CR is used in this work which more than the non-cooperative cognitive user to detect the holes. The final decision for detection built on four fusion rules are the logic OR, logic AND, MAJORITY and K-Out-Of-M fusion rule. The two proposed are applied techniques on four fusion rule at constant sensing time. Then; study the four metric detection performances for each fusion rule by using the Additive White Gaussian Noise (AWGN) channel. At the end, comparison between two these proposed techniques with each fusion rule. Simulation results prove that the proposed scenario increases the probability of detection in the range of SNR of the PU from ?20 to ?5 dB using the theses proposed approaches.

     

Hybrid Detection for Cooperative Cognitive Radio Using AWT and HDWT

Wireless Personal Communications - A lot of research shows that spectrum is not effectively used in wireless communications. There are several gaps in spectrum that are unused. Cognitive radio (CR)...     

Axial mixing in a novel pilot scale gas–liquid reciprocating plate column

Axial mixing in a novel pilot scale landau reciprocating plate column (LRPC) has been investigated for counter-current gas–liquid contacting over a wide range of operating conditions. The experimental results obtained using the dynamic response method were analysed using both the dispersion and compartment models under different boundary conditions and using both the method of moments and the direct time domain parameter estimation techniques. Based on the results, it was identified that axial mixing in this column can be best described using the back flow and the dispersion models solved with “closed–closed” boundary conditions. A general correlation describing the effect of operating parameters on the extent of axial mixing was developed with a mean absolute relative residuals of 6.8%. Similar to other RPC designs, axial mixing in LRPC increases with increasing both phase flows and plates oscillatory velocity. Values of axial dispersion coefficient in this work ranged from 10⁻⁴ to over 3 × 10⁻³ m²/s, which are comparable or less than those in other RPC designs under similar phase velocities and oscillatory conditions, but an almost order of magnitude lower than those measured in bubble columns under similar operating flow rates.     

Modification of Nylon 6,6 with Trioctylphosphine Oxide for Uranium Removal from Aqueous Solution

Radiochemistry - The study deals with the uranium removal from a raffinate solution (nitric acid waste solution from the production of uranium yellowcake) using an extractant-impregnated material....     

Free-volume properties of epoxy composites and its relation to macrostructure properties

Some characteristics of epoxy composites are discussed based on the results of positron annihilation lifetime spectroscopy (PALS), electrical and mechanical measurements. The effect of different types and wt% of fillers such as aluminium oxide (Al₂O₃), titanium oxide (TiO₂) and silicon carbide (SiC) on the epoxy structure and hence free volume, physical, electrical, and mechanical properties is presented. The results showed that the electrical properties are improved at high wt% of filler, while mechanical properties are improved at low wt% of filler. Furthermore, a similar trend is observed for all fillers but with a systematic shift to high influence when Sic added to cured epoxy. On the other hand, adding SiC as a filler on epoxy improved the resistance to water absorption.The role of PALS as a sensitive probe for changes in microstructure of epoxy composites is confirmed during the correlation between the free-volume parameters and the other measurements.     

Dilute magnetic semiconductor of ZnCoSe thin films: Structural,optical, and magnetic characteristics

A series of Zn_1−xCo_xSe (x = 0, 0.025, 0.050, 0.075, and 0.100) films using were evaporated (thickness of 1 μm) using electron beam gun. The effect of Co doping on the structural, optical, and magnetic properties has been investigated. X-ray diffraction studies confirm formation of zinc blend structure for all Zn_1−xCo_xSe films. The crystallite size increases and the lattice strain decreases with the increase in Co content. The elemental constituents were characterized by energy dispersive X-ray. Optical studies showed an increase in refractive index and a decrease in energy gap with the increase in the cobalt doping. The dispersion of the refractive index has been analyzed in terms of the Wemple-DiDomenico single oscillator model. The oscillator parameters including the single oscillator energy (E_o), the dispersion energy (E_d), and the static refractive index (n₀) were estimated. Magnetization measurements via vibrating sample magnetometer showed a hysteresis loop and confirmed room-temperature ferromagnetism in Co-doped ZnSe films.     

Positron annihilation lifetime studies of gas sorption and desorption in polyethylene and poly[1‐(trimethylsilyl)‐1‐propyne]

The variation of free‐volume parameters (lifetime, intensity, and distribution) after sorption and desorption of CO₂ and CH₄ gases in the glassy polymer poly[1‐(trimethylsilyl)‐1‐propyne] (PTMSP) and in the rubbery high‐density polyethylene (HDPE) and low‐density polyethylene (LDPE) were determined by the PAL technique. Size distributions deduced from PAL measurements reveal the presence of large free‐volume holes in PTMSP with an average size of 0.725 nm³ and intensity of 22% in addition to a free‐volume hole size of 0.197 nm³ with an intensity of 11%. In polyethylene free‐volume hole sizes of 0.107 and 0.153 nm³ with intensities of 21% and 25% could be deduced for HDPE and LDPE, respectively. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 970–974, 2001     

Effect of adding feldspar on free volume properties of crosslinked polyester studied by positron annihilation lifetime spectroscopy

Positron annihilation lifetime spectroscopy (PAL) was applied to study the feldspar effect on the free volume properties of crosslinked polyester based on neopentyl glycol, succinic acid, phthalic anhydride, and maleic anhydride. The measurements have been carried on the polyester resin samples cured with three crosslinking agents namely styrene (SS) or styrene/methyl methacrylate (SM) or styrene/acrylonitrile (SA) comonomers mixtures in the ratios of 2 : 1 and loaded with different concentrations of feldspar in the range from 0 to 80 wt %. The free volume parameters (size and fractions of holes) depend on type of the crosslinking agent as well as the feldspar content added to the polyester. The results are supported by a significant variation in the nanoscale free volume hole size distributions. Moreover, the correlation between positron annihilation parameters and electrical parameters was discussed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Kinetics and formation mechanism of amorphous Fe52Nb48 alloy powder fabricated by mechanical alloying

A single phase amorphous Fe₅₂Nb₄₈ alloy has been synthesized through a solid state interdiffusion of pure polycrystalline Fe and Nb powders at room temperature, using a high-energy ball-milling technique. The mechanisms of metallic glass formation and competing crystallization processes in the mechanically deformed composite powders have been investigated by means of X-ray diffraction, Mössbauer spectroscopy, differential thermal analysis, scanning electron microscopy and transmission electron microscopy. The numerous intimate layered composite particles of the diffusion couples that formed during the first and intermediate stages of milling time (0–56 ks), are intermixed to form amorphous phase(s) upon heating to about 625 K by so-called thermally assisted solid state amorphization, TASSA. The amorphization heat of formation for binary system via the TASSA, ΔH_a, was measured directly as a function of the milling time. Comparable with the TASSA, homogeneous amorphous alloys were fabricated directly without heating the composite multilayered particles upon milling these particles for longer milling time (86 ks–144 ks). The amorphization reaction here is attributed to the mechanical driven solid state amorphization. This single amorphous phase transforms into an order phase (μ phase) upon heating at 1088 K (crystallization temperature, T_x) with enthalpy change of crystallization, ΔH_x, of −8.3 kJ mol⁻¹.