Blends of ethylene methyl acrylate (EMA) and poly(dimethylsiloxane) rubber (PDMS) are demonstrated to be miscible. The miscibility results in a single and composition-dependent glass transition temperature. IR spectra of the blends provide direct evidence of chemical reaction between EMA and PDMS rubber. 相似文献
Prediction of stock index remains a challenging task of the financial time series prediction process. Random fluctuations in the stock index make it difficult to predict. Usually the time series prediction is based on the observations of past trend over a period of time. In general, the curve the time series data follows has a linear part and a non-linear part. Prediction of the linear part with past history is not a difficult task, but the prediction of non linear segments is difficult. Though different non-linear prediction models are in use, but their prediction accuracy does not improve beyond a certain level. It is observed that close enough data positions are more informative where as far away data positions mislead prediction of such non linear segments. Apart from the existing data positions, exploration of few more close enough data positions enhance the prediction accuracy of the non-linear segments significantly. In this study, an evolutionary virtual data position (EVDP) exploration method for financial time series is proposed. It uses multilayer perceptron and genetic algorithm to build this model. Performance of the proposed model is compared with three deterministic methods such as linear, Lagrange and Taylor interpolation as well as two stochastic methods such as Uniform and Gaussian method. Ten different stock indices from across the globe are used for this experiment and it is observed that in majority of the cases performance of the proposed EVDP exploration method is better. Some stylized facts exhibited by the financial time series are also documented.
An information security policy is a most vital and therefore essential part of any organisation’s set of controls. Yet most organisations have poorly written policies. This paper examines the possible shortfalls of policy writings. Starting from the meaning and etymological roots of the word, the theory behind particular structures is discussed. The case is made for a single policy, many standards hierarchy. Structural and linguistic considerations including a sample statement hierarchy provide 2 practical suggestions on how to build such a hierarchy. Authorship considerations and some fine details on how to convey the will and purpose of the signatories complete the paper. 相似文献
Multimedia Tools and Applications - This paper discusses the development of an efficient and automated system for the recognition of facial expressions, which is essentially an application... 相似文献
Guayule natural rubber (GNR) is an alternative resource of Hevea natural rubber (HNR) with 99.9% cis content in its 1,4-polyisoprene chemical backbone. In this study, compounds were formulated independently with four different reinforcing fillers such as carbon black (HAF), precipitated silica (VN3), fume silica (FUM) and nanofly ash (NFA) for the advancement of GNR based products. The cure characteristic, dynamic-mechanical performance and mechanical properties of GNR composite were studied with the reinforcing effect of different fillers on GNR. The cure characteristic results demonstrated that HAF and FUM silica filled compounds had more processing safety than VN3 and NFA filled compounds. Viscoelastic parameters of the vulcanizates were studied by dynamic mechanical analysis to estimate the glass transition characteristics and dynamic behavior. The higher storage modulus of FUM silica vulcanizate was an indication of superior filler reinforcing nature and improved rolling resistance than other filled systems. Additionally, HRTEM analysis also proved the better filler dispersion ability of FUM silica in GNR matrix. The mechanical properties were studied with a variation of each filler loading of 8, 16, and 32 phr in GNR vulcanizates. The tensile strength of each filled system increased with an increase of filler content from 8 to 32 phr. In comparison, FUM silica GNR vulcanizates exhibited better mechanical properties, therefore, it was considered as a better structure-performance composite than those of HAF, VN3 and NFA filled composites.
Toughness of rigid thermoplastic is an important mechanical property in polymer technology. In the present study, toughening of waste polypropylene (WPP) with ethylene–propylene–diene monomer (EPDM) rubber at different loading levels was carried out by melt blending at 180 °C. The EPDM-toughened WPP samples were characterized for its thermo-mechanical properties. The effect of carbon black (5 wt%) as a functional filler in WPP/EPDM to impart UV protection was also studied. The test sheets were subjected to natural weathering in variable climatic conditions for a 4-month period of time and were taken out at regular intervals for characterization. The waste PP underwent excessive degradation as the mechanical strength properties such as tensile, flexural and impact strengths were reduced drastically. On the other hand, WPP containing varying proportions of EPDM and carbon black showed better retention of strength properties. The percentage degree of crystallinity has been unusually increased after the environmental degradation due to chemi-crystallization. The impact-modified WPP which contains carbon black retained the processability even after the environmental aging. After aging, the non-stabilized systems were shown extensive change, whereas the structural integrity has been well retained of the toughened WPP containing carbon black as was evident from SEM and optical photomicroscopy. 相似文献
The differences in the bioavailability of different drug products are most frequently caused by differences in the dissolution rates of the active ingredient. In case of magnesium oxide the drug release can be directly determined by reaction kinetics method based on acid neutralization.
For a more precise study of the factors influencing the kinetical characteristics of the neutralization rates it is advisable to use homogeneous granule fractions. Before the granulation the substance was pretreated with silicone oil. The granulation of the obtained grains having hydrophobe surface was carried out in an AEROMATIC STREA-I type laboratory fluidization equipment with Eudragit polymer solved in isopropyl alcohol.
For determining the acid neutralization kinetics of the granules the “constant pH” method and the Rossett-Rice test were used.
As a result of the granulation the neutralization rate decreased. The granules can be considered as an Eudragit matrix which contains the pretreated magnesium oxide in embedded form. During the chemical reaction the resulted salt (magnesium chloride) leaves the surface of the unreacted magnesium oxide unless having a chemical reaction with the polymer. Meanwhile the residual matrix forms a mesh which increases the viscosity of the solution and the thickness of the diffusion layer. The dissolution rate decreases in both cases.
Under the same conditions the kinetic values of the neutralization change by several magnitudes depending on the utilized methods. In this way different systems of medicine, which alter their reaction capacity according to the expected physiological purposes, can be created. 相似文献