Lower critical solution temperature behavior of ethylene propylene copolymers in multicomponent solvents

The lower critical solution temperature (LCST) locus for ethylene-propylene copolymers has been determined as a function of pressure in a variety of single and multicomponent solvents. The lower critical end-point temperature (LCEP), which is the intersection of the LCST locus with the vapor-pressure curve, was found to be predictable from the solvent density as previously established for single-component solvents by Charlet and Delmas.¹ Dissolving a low-molecular hydrocarbon gas such as propylene in an alkane has a dramatic effect on lowering the LCEP, and can reduce phase-separation temperatures to levels at which this technique becomes attractive as a practical method for polymer recovery from diluents such as those used in solution polymerizations. Temperatures considerably above the LCEP are needed to minimize the residual polymer concentration in the solvent in the two-liquid-phase region. The solvent critical temperature must be approached for essentially complete elimination of the polymer from the solvent phase. The LCST locus was found to be a linear function of pressure for all of the systems investigated, and the slope of the line, d(LCST)/dP, could be well correlated as a function of solvent density and critical temperature. From the relationship between the LCEP and solvent density and the correlation for d(LCST)/dP, the location of the LCST locus can be readily predicted from a knowledge of solvent properties.     

Optimal production of intermediate for zero—first and first—first order reaction sequences in fluidised bed reactors1

An analysis of zero—first and first—first order reaction schemes has been carried out in a fluidised bed with a view to optimising the production of intermediate R for a given bubble diameter. For the zero—first order reaction sequence, the gas residence time at which the maximum concentration of R occurs is shown to be fixed and independent of bubble size in the bed. On the other hand, for a first—first order reaction scheme, an optimum gas residence time exists for the concentration maximum to occur at the bed exit. This interaction between bubble diameter, gas residence time and maximum concentration of intermediate is resolved by recourse to a three dimensional diagram which optimises the production of intermediate for any given value of bubble diameter or gas residence time.     

Are U.K. Citizens Satisfied With E-Government Services? Identifying and Testing Antecedents of Satisfaction

Citizens’ satisfaction is acknowledged as one of the most significant influences for e-government adoption and diffusion. This study examines the impact of information quality, system quality, trust, and cost on user satisfaction of e-government services. Using a survey, this study collected 1518 valid responses from e-government service adopters across the United Kingdom. Our empirical outcomes show the five factors identified in this study have a significant impact on U.K. citizens’ satisfaction with e-government services.     

Multi-frame estimation of planar motion

Traditional plane alignment techniques are typically performed between pairs of frames. We present a method for extending existing two-frame planar motion estimation techniques into a simultaneous multi-frame estimation, by exploiting multi-frame subspace constraints of planar surfaces. The paper has three main contributions: 1) we show that when the camera calibration does not change, the collection of all parametric image motions of a planar surface in the scene across multiple frames is embedded in a low dimensional linear subspace; 2) we show that the relative image motion of multiple planar surfaces across multiple frames is embedded in a yet lower dimensional linear subspace, even with varying camera calibration; and 3) we show how these multi-frame constraints can be incorporated into simultaneous multi-frame estimation of planar motion, without explicitly recovering any 3D information, or camera calibration. The resulting multi-frame estimation process is more constrained than the individual two-frame estimations, leading to more accurate alignment, even when applied to small image regions.     

Low temperature J-resistance curve determination of asphalt concrete using wavelet-Radon transform

A single specimen test using the three point single edge notched beam configuration at low temperatures for obtaining hot mix asphalt （HMA） resistance curves is developed.Resistance curves are obtained for mixtures at six temperature levels of＋5,0,-5,-10,-15,and-20 ℃ and three binder contents of 4％,4.5％,and 5％.Crack extension increments during the test are measured by means of an image processing technique using Radon transform and feature extraction.All the specimens exhibit a rising R-curve,indicating ductility and toughening mechanisms in the ductile-quasi brittle fracture of the mixture.It is observed that the reduction of temperature results in a further tendency of the mixture for unstable crack growth and less subcritical crack length.It is also shown that using the binarization process,an automatic index can be developed that can represent the extent of brittleness and extent of the low temperature in which the cracking has occurred.     

Scheduling with Conflicts on Bipartite and Interval Graphs

In this paper, we consider the on-line scheduling of jobs that may be competing for mutually exclusive resources. We model the conflicts between jobs with a conflict graph, so that the set of all concurrently running jobs must form an independent set in the graph. This model is natural and general enough to have applications in a variety of settings; however, we are motivated by the following two specific applications: traffic intersection control and session scheduling in high speed local area networks with spatial reuse. Our results focus on two special classes of graphs motivated by our applications: bipartite graphs and interval graphs. The cost function we use is maximum response time. In all of the upper bounds, we devise algorithms which maintain a set of invariants which bound the accumulation of jobs on cliques (in the case of bipartite graphs, edges) in the graph. The lower bounds show that the invariants maintained by the algorithms are tight to within a constant factor. For a specific graph which arises in the traffic intersection control problem, we show a simple algorithm which achieves the optimal competitive ratio.     

Corneal topography of photorefractive keratectomy versus laser in situ keratomileusis. Summit PRK-LASIK Study Group

OBJECTIVE: This study aimed to compare qualitative patterns of corneal topography early in the postoperative course after excimer laser photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) when used for the treatment of myopia of 6.0 to 15.0 diopters. DESIGN: The study design was a prospective, multicenter, randomized clinical trial. PARTICIPANTS: A total of 64 eyes were treated with PRK and 54 eyes were treated with LASIK. INTERVENTION: Using the Summit Apex excimer laser, patients received either PRK or LASIK using a single pass, multizone excimer laser ablation. Computer-assisted videokeratography was performed at designated postoperative examinations. MAIN OUTCOME MEASURES: Videokeratography maps at 1 and 3 months after surgery were classified using a standard classification scheme. The association of topography patterns to loss of spectacle-corrected visual acuity was tested. RESULTS: At 1 month, for the PRK (n = 60) and LASIK (n = 51) groups, respectively, 63.3% and 19.6% of eyes fell into one of the four optically irregular groups (central island, keyhole, semicircular, or irregularly irregular; P < 0.001). At 3 months, for the PRK (n = 49) and LASIK (n = 39) groups, respectively, 36.7% and 10.3% of eyes fell into one of the optically irregular groups (P = 0.004). Comparing the 1- and 3-month examination results in the PRK and LASIK groups, respectively, 19 (42%) of 45 eyes and 11 (31%) of 36 eyes had a change in topography, generally to an optically smoother pattern. The irregular groups, taken together, were associated with a greater tendency toward loss of spectacle-corrected visual acuity of two or more Snellen lines (P = 0.01). There also was greater tendency toward loss of spectacle-corrected visual acuity in the PRK group that diminished with time (P < 0.01 at 1 month, P = 0.05 at 3 months). CONCLUSIONS: After treatment for moderate-to-high myopia, LASIK topography patterns generally are more regular than are PRK patterns. This may be a result either of masking of underlying topography perturbations by the lamellar corneal flap, thus mitigating induced topography changes, or differences in surface wound healing. This study suggests that more rapid return of spectacle-corrected visual acuity found in patients treated with LASIK may be a result of more regular topography patterns early in the postoperative course.     

Thermal Buckling Analysis of Piezoelectric Functionally Graded Plates with Temperature-Dependent Properties

In this study, the thermal buckling analysis of hybrid laminated plates made of two-layered functionally graded materials (FGMs) that are integrated with surface-bonded piezoelectric actuators referred to as (P/FGM)_s are investigated. Material properties for both substrate FGM layers and piezoelectric layers are temperature-dependent. Uniform temperature rise as a thermal load and constant applied actuator voltage are considered for this analysis. By definition of four new analytic functions, the five coupled governing stability equations, which are derived based on the first-order shear deformation plate theory, are converted into fourth-order and second-order decoupled partial differential equations (PDEs). Considering a Levy-type solution, these two PDEs are reduced to two ordinary differential equations. One of these equations is solved using an accurate analytical solution, which is named as power series Frobenius method. The effects of parameters, such as the plate aspect ratio, ratio of piezoelectric layer thickness to thickness of FGM layer, gradient index, actuator voltage, and the temperature dependency on the critical buckling temperature difference, are illustrated and explained. The critical buckling temperatures of (P/FGM)_s with six various boundary conditions are reported for the first time and can be served as benchmark results for researchers to validate their numerical and analytical methods in the future.