SENTIMENT ASSESSMENT OF TEXT BY ANALYZING LINGUISTIC FEATURES AND CONTEXTUAL VALENCE ASSIGNMENT

Text is not only an important medium to describe facts and events, but also to effectively communicate information about the writer's positive or negative sentiment underlying an opinion, or to express an affective or emotional state, such as happiness, fearfulness, surpriseness, and so on. We consider sentiment assessment and emotion sensing from text as two different problems, whereby sentiment assessment is the task that we want to solve first. Thus, this article presents an approach to sentiment assessment, i.e., the recognition of negative or positive valence of a sentence. For the purpose of sentiment recognition from text, we perform semantic dependency analysis on the semantic verb frames of each sentence, and then apply a set of rules to each dependency relation to calculate the contextual valence of the whole sentence. By employing a domain-independent, rule-based approach our system is able to automatically identify sentence-level sentiment. A linguistic tool called “SenseNet” has been developed to recognize sentiments in text, and to visualize the detected sentiments. We conducted several experiments with a variety of datasets containing data from different domains. The obtained results indicate significant performance gains over existing state-of-the-art approaches.     

Evaluation of the differencing pixel-by-pixel change detection method in mapping irrigated areas in dry zones

Geographic information system (GIS) and change detection techniques were used in this study to evaluate the efficiency of an automatic change detection method in detecting and mapping the changes that took place after the implementation of newly irrigated areas in dry zones. Two satellite images were used: Landsat Thematic Mapper (TM) 1983 and Landsat Enhanced Thematic Mapper Plus (ETM+) 2004. The newly implemented irrigated areas were identified using the differencing pixel-by-pixel change detection method. All of these areas were detected over the period 1983–2004. The accuracy of the results obtained from the change detection method applied was determined by spectral and spatial assessment (image interpretation and field surveying). It was shown that all the newly implemented irrigated areas were detected. The assessment of the areas of the new implemented parcels obtained by the current change detection method showed an error of less than 8%. This result is reasonably good if we consider the speed of the process and its low cost for large zones.     

Optimization of rotor speed based on stretching,efficiency, and viscous heating in nonintermeshing internal batch mixer: Simulation and experimental verification

Optimization of rotor speed based on stretching, efficiency, and viscous heating in nonintermeshing internal batch mixer has been investigated using polymer melt. A practical optimization technique was followed for optimization. Four different rotor speeds were used and characterized numerically with viscous dissipation and stretching. The heat distribution between rotor edge and mixer wall was calculated. Stretching experienced by the fluid was analyzed and the result was verified experimentally using particle tracking method. Exponential increase of energy dissipation between the rotor edge and the barrel at higher speed highlighted the importance of choosing the thermal properties of the polymer to avoid thermal degradation. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Stochastic model for living radical polymerisation of styrene initiated by epoxide radical ring opening

A stochastic model was developed to simulate the polymerisation kinetics and the detailed microstructure of the resulting polymers made by the living radical polymerisation of styrene initiated by epoxide radical ring opening. The model was used to predict monomer conversion, average molecular weight, polydispersity index, and molecular weight distribution as a function of polymerisation time. Simulations were used to explore the effects of rate constant values on chain microstructures and polymer properties and validated with experimental data published in the literature. It was found that some parameters, such as the exchange rate constant, have no significant effect on the polymerisation kinetics, whereas major effects were observed when other rate constants, such as the reduction rate constant, were changed.     

Influence of post-curing temperature on the structure,properties, and adhesion of vinyl ester adhesive

Vinyl ester (VE) resins are widely used as thermoset adhesives in structural joints and composites, but complete curing under environmental conditions is not produced. The existing literature dealing with the effect of post-curing on the structure, viscoelastic, mechanical, and adhesion properties of VE resin is scarce. Therefore, in this study, VE resin was subjected to different post-curing temperatures (50–140 °C) for one hour, and the changes in structure and properties were assessed. The degree of cross-linking of the VE resin depended on the post-curing temperature and cure started to be completed above 100 °C, a temperature close to the glass transition temperature (115 °C) of the completely cross-linked polymer. Furthermore, gel formation in VE resin was evidenced for post-curing temperature below 100 °C. In order to fully cross-link the VE resin, post-curing at 140 °C for one hour was necessary, and it was evidenced by an increase in the glass transition temperature and in the mechanical properties; an increase in adhesion to cold rolled steel was obtained although the shear strength was lower than in the joint produced with the non-post-cured VE resin.     

6D μ cooling using a solenoid-dipole ring cooler for a muon collider

Six dimensional cooling of large emittance μ⁺ and μ⁻ beams is required in order to obtain the desired luminosity for a muon collider. We propose to use a ring cooler that employs both dipoles and solenoids with the additional requirement that the arcs of the ring be achromatic. We describe the lattice and the beam dynamics of the proposed ring, and demonstrate that the lattice gives substantial cooling in all 6 phase space dimensions.     

Flame propagation in a tent camp

This paper presents an experimental study leading to the understanding and modelling of the effect of air speed and its direction on flame propagation in tent fabrics in addition to fire propagation in a tent camp. The study was conducted on burning fabrics of different densities subjected to wind speeds ranging between zero (stagnant) and 1.4 m s^?1. Moreover, several air directions with respect to the flame were considered in the study to cover the cases of vertically upward, downward, horizontally aiding and opposing, and inclined directions. These cases were used in simulating actual flame propagation in a tent. It is found that there is a logarithmic relation between the time of burning a tent and air speed and the density of tent fabrics. Two different types of fabric are considered; waterproof and non‐waterproof. It is also observed that the surface flame temperature is invariant with air speed or fabric density and it reaches about 650°C. The results show that denser fabrics require more time for burning. The maximum flame propagation speed is observed for vertically upward flame concurrent with air direction. On the other hand, minimum flame propagation is observed for vertically downward flames opposing the air direction. A model is derived for predicting the time required for flame propagation in a known camp area. Copyright © 2001 John Wiley & Sons, Ltd.     

Physical phenomena affecting performance and reliability of 4H-SiC bipolar junction transistors

The silicon carbide bipolar junction transistor (BJT) is attractive for use in high-voltage switching applications offering high-voltage blocking characteristics, low switching losses, and is capable of operating at current densities exceeding 300 A/cm². However, performance reliability issues such as degradation of current gain and on-resistance currently prohibit commercial production of 4H-SiC BJTs. This paper examines the physical mechanisms responsible for this degradation as well as the impact that these physical phenomena have on device performance. Results were obtained through the examination of several types of N-P-N BJT structures using various fabrication methodologies. Electron-beam induced current (EBIC) and potassium hydroxide (KOH) etching were used to characterize defect content in the material, before and after device current stress, when possible. It was found that Shockley stacking faults (stress-induced structures) associated with the forward voltage drift phenomenon in SiC bipolar diodes, also play a major role in the reduction of gain and an increase of on-resistance of the BJTs. However, results from some devices suggest that additional processes at the device periphery (edge of the emitter) may also contribute to degradation in electrical performance. Hence, it is essential that the sources of electrical degradation, identified in this paper, be eliminated for SiC BJTs to be viable for commercial scale production.     

Polyaniline matrix containing nickel ferromagnet

Metallic nickel (Ni) was successfully dispersed onto a polyaniline (PANI) matrix by a simple one‐step electrochemical method. Ni particles as deposited onto the polymer seemed to be much smaller compared to those deposited onto bare Pt. The size of the Ni deposits was found to be influenced by the electrolytic bath composition and potential sweep rate. The PANI matrix thus dispersed with Ni particles exhibited ferromagnetic behavior and a lower electrical conductance. The decrease in conductivity may be attributed to the partial blockage of the conductive path by the Ni particles thus embedded in the polymer matrix. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 321–327, 2006