Towards a compliance requirement management for SMSEs: a model and architecture

Information Systems and e-Business Management - Today’s business entities face an ever-growing number of laws and regulations due to recent high profile business scandals and failures. Small...     

Phase Behavior of Poly(butyl acrylate) Networks in Nematic Liquid Crystal Solvents

Summary: This paper reports the phase behavior of photochemically crosslinked poly(butyl acrylate) networks in nematic liquid crystal (LC) solvents. The swelling properties are studied as a function of temperature for two low molecular weight nematic LCs, 4‐cyano‐4′‐pentylbiphenyl (5CB) and the eutectic mixture of cyanoparaphenylenes (E7). Chemically crosslinked polymer networks were formed by the UV radiation of initial solutions of the reactive monomer, butyl acrylate, a crosslinker (hexanediol diacrylate), and a photoinitiator. To obtain different network densities, the ratio of butyl acrylate to hexanediol diacrylate was varied prior to polymerization/crosslinking reactions. Immersion in an excess of the LC solvent allowed for the measurement of size increase by polarized optical microscopy in terms of temperature. Length, width, and diagonal ratios were calculated considering swollen to dry network states of the samples. In general, swelling leads to an increase in the network size by increasing the temperature with a significant dependence on the degree of crosslinking. A large shift in the swelling ratio was found in the vicinity of the nematic to isotropic transition temperatures of the LCs.

     

Electrocardiogram Signal Denoising Using Discrete Wavelet Transform

The most common noises in ECG （electrocardiogram） signal processing are BW （baseline wandering） and the 50 or 60 Hz PLI （power line interferences）. In order to remove these two major source of noises, we have used the recent powerful DWT （discrete wavelet transform） signal processing in ECG signals which are obtained from MIT-BIH Arrhythmia Database. The results indicate that DWT is a good method for filtering noises without changing the morphology of ECG, and can be applied to all types of ECG signals, whether normal or presenting arrhythmias.     

Pilot contamination mitigation based on antenna subset transmission for mmWave massive MIMO

This paper tackles the problem of pilot contamination (PC) in mmWave Massive MIMO cellular systems. We propose an analog precoder based on antenna subset transmission technique to mitigate the PC. This technique ensures the interfering signal to become noise‐like signal thus helping a more efficient estimation of channel coefficients. Also, this strategy is low cost and introduces no complexity load. The result shows the effectiveness of the proposed precoder to mitigate PC issue.     

RF Testing on a Mixed Signal Tester

In this paper, testing of radio frequency (RF) devices with mixed-signal testers is discussed. General purpose automatic test equipment (ATE) will be used. In this paper, a more universal test structure utilizing RF building blocks is proposed. A global positioning system (GPS) device is used as an example to illustrate how to develop the RF test plan with this usage. The test plan developed includes fast, cost-effective and dedicated circuitry.

The Effect of γ‐Irradiation on the Structure and Properties of Poly(propylene)/Clay Nanocomposites

The oxidative degradation of PP/OMMT nanocomposites under γ‐irradiation was studied. Changes in structure and properties resulting from γ‐exposure in the range 0–100 kGy were investigated. The results were analyzed by comparing the influence of PP‐g‐MA and pristine OMMT on the oxidation kinetics of neat PP. γ‐Irradiation in the presence of air strongly degraded the properties of PP materials, particularly for radiation doses above 20 kGy. The rate of oxidative degradation of PP/OMMT/PP‐g‐MA nanocomposites was much faster than that of neat PP. This suggests that PP‐g‐MA and pristine OMMT components behave as oxidation catalysts, leading to the formation of free radicals in the polymer matrix.

     

Effect of Hydrothermic Ageing on Dielectric and Mechanical Properties of Rigid Poly(vinyl chloride)

An accelerated hydrothermic ageing (according to N.F.T. 54043 method) was performed on samples of rigid poly(vinyl chloride). The test consisted of sample immersion in boiling water at 100°C for different exposure periods up to 480 h. The samples were removed from the boiling water every two hours for mechanical and dielectric characterization and color test. The dielectric measurements carried out on aged samples, up to 40 h, showed that the permittivity remained almost constant and its value was found to be 2.3 in the range –100 to +62.8°C. However, as the temperature approaches the glass transition (T_g = 88.3°C), the permittivity was observed to increase rapidly. It was also found that the permittivity of aged samples was lower than that of the non‐aged samples. The dielectric loss factor (tan δ) measurements with respect to temperature have confirmed the presence of two relaxations: β at low temperature (around –35°C) and α near the T_g. The combined action of water and temperature reduced the intensity of the corresponding relaxation peaks. The sample color index was evaluated up to 480 h using the SYNMERO scale in order to estimate the degradation extent. Unexpectedly, elongation at break under uniaxial traction remained unaffected by the hydrothermic ageing, meaning that two competing processes were involved simultaneously (sample degradation via chain scission and sample plastification via water absorption).     

Cyclic polymers in good solvents

This paper deals with the effects of excluded volume interactions on the thermodynamic and structural properties of cyclic polymers in good solvents. Several thermodynamic properties are discussed with particular emphasis on excluded volume interactions and their effects on the radii of gyration and the form factors. An empirical model describing the mean square distance between two points along a cyclic polymer is proposed and its predictions compared with those of other models. Comparison between cyclic and linear chain properties highlights the effects of chain closure under good solvent conditions. © 2000 Society of Chemical Industry     

Electrical properties of polyaniline–polystyrene blends above the percolation threshold

Blends of conductive polymers with classical ones can exhibit good mechanical properties and good electrical conductivity and deserve great attention for application in electronic industrial technology. Conductive polyaniline solutions have been chemically prepared using bis(2-ethyl hexyl)hydrogen phosphate (DiOHP) as the dopant chemical species. The codissolution method leads to conductive polyaniline–polystyrene (PANI–PSt) composites with good mechanical properties. The dependence of electrical conductivity on the volume fraction of PANI in the blend is found to be characteristic of a percolation system. Electrical conductivity and thermoelectric power measurements are interpreted on the basis of hopping mechanisms between polaronic clusters. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1205–1208, 1998