Poly(p-tert-butoxycarbonyloxystyrene): a convenient precursor to p-hydroxystyrene resins

An efficient synthetic route to pure, high molecular weight poly(p-hydroxystyrene) is reported. The route involves synthesis of a new monomer, p-tert-butoxycarbonyloxystyrene, polymerization by radical initiation or by cationic initiation in liquid SO₂, followed by thermolysis or acidolysis of the tert-butoxycarbonyl protecting group. Porous, crosslinked resin beads containing the nucleophilic, phenol pendant group have been prepared in a similar fashion from the precursor terpolymer of p-tert-butoxycarbonyloxystyrene, styrene and divinylbenzene. The utility of this resin for solid-phase synthesis has been demonstrated.     

Kinetic modelling of the catalytic conversion of synthesis gas

A kinetic study for the one-step conversion of synthesis gas to gasoline on a ZnO–Cr₂O₃–ZSM-5 catalyst is described. On this catalyst, three reactions are involved in the overall transformation of synthesis gas: the methanol synthesis, the conversion of methanol to hydrocarbons and the water–gas shift reaction. Under the operating conditions selected for the study, it was found that the water–gas shift was at equilibrium and the methanol was completely converted to hydrocarbons. Consequently, it was postulated that the kinetics of the limiting reaction step, the methanol synthesis on the ZnO–Cr₂O₃ component, was the one that controls the overall reaction rate. Three kinetic model equations describing the rate of synthesis gas conversion on the bifunctional catalyst, were considered to fit the data of the experimental runs performed in a Berty well-mixed reactor. Those equations were derived under very special conditions where the methanol decomposition term could be neglected. It was also observed that in the kinetic equations a term involving the fugacity of CO₂ was required to predict the rate properly. The catalyst deactivation was also taken into account in the analysis.     

Characterization of cationic water-soluble polyacrylamides

Copolymers of poly(acrylamide-co-acryloyloxyethyltrimethylammonium chloride or AM–CMA) and poly(acrylamide-co-methacryloyloxyethyltrimethylammonium chloride or AM–CMA) prepared by inverse emulsion polymerization were characterized by different analytical techniques. The chemical composition of the copolymers was estimated by elemental analysis and by nuclear magnetic resonance spectroscopy (NMR). NMR spectroscopy and computer simulation were further used for investigating the polymers' sequence distribution. The poly(AM–CMA) copolymers are chemically more homogeneous than are the poly(AM–CMA). The configurational propagation of dyads and triads for the homopolymers obeys Bernouilli's statistics. For the copolymers, the chemical sequences distribution is governed by Markov's first-order statistics.     

冠带层新平台技术

子午线轮胎出现不久，就采用钢丝带束层代替了纤维带束层，这对于实现子午线轮胎提高使用寿命和改善操纵性能的潜能是必要的。     

Marking student programs using graph similarity

We present a novel approach to the automated marking of student programming assignments. Our technique quantifies the structural similarity between unmarked student submissions and marked solutions, and is the basis by which we assign marks. This is accomplished through an efficient novel graph similarity measure (AssignSim). Our experiments show good correlation of assigned marks with that of a human marker.     

Optimization of quality and operational costs through improved scheduling of harvest operations

The agriculture sector still lacks the tools and models to enhance the utilization of different resources. This paper addresses the vineyard harvesting problem in developing countries, with the objective of optimizing the wine quality and minimizing the operational costs. Heuristics were introduced to better assign the harvesting days to the different grape blocks that exist in the vineyard's field. The quality of the grapes was a key target as it can transform production from a pinnacle wine to a bulk one. We solved several numerical examples for verification and demonstrative purposes and found that our proposed approach finds solutions that significantly reduce the harvesting costs in the vineyard and considerably outperform Branch and Bound algorithm especially for large problems.     

Generating systems from multiple sketched models

Diagrams are often used to model complex systems: in many cases several different types of diagrams are used to model different aspects of the system. These diagrams, perhaps from multiple stakeholders of different specialties, must be combined to achieve a full abstract representation of the system. Many CAD tools offer multi-diagram integration; however, sketch-based diagramming tools are yet to tackle this difficult integration problem. We extend the diagram sketching tool InkKit to combine software engineering sketches of different types. Our extensions support software design processes by providing a sketch-based approach that allows the iterative creation of multiple outputs interacting with one another from the inter-linked models. We demonstrate that InkKit can generate a functional system consisting of a user interface with processes to submit and retrieve data from a database from sketched user interfaces designs and sketched entity relationship diagrams.     

Airflow in a slot-ventilated enclosure partially filled with porous boxes: Part I - Measurements and simulations in the clear region

A reduced-scale model and CFD predictions were used to investigate experimentally and numerically the airflow patterns within a ceiling slot-ventilated enclosure partially loaded with vented boxes filled by spherical objects. The experiments were carried out using laser Doppler velocimetry. Airflows around and inside porous boxes were predicted taking into account their aerodynamic interactions. This work is divided into two parts. This paper presents part I and concerns the air velocity characteristics within the jet above the boxes, while Part II deals with the air velocity characteristics inside the boxes. The results highlight the confinement effect due to the enclosure and the influence of load porosity on jet penetration, its development and hence the heterogeneity of ventilation within the enclosure. The numerical predictions obtained with the computational fluid dynamics Fluent package using the RSM turbulence model show reasonable agreement with experimental data. Predicted velocity profiles were generally within an error of 3-30% of the measured velocities.     

Generic remeshing of 3D triangular meshes with metric-dependent discrete voronoi diagrams

In this paper, we propose a generic framework for 3D surface remeshing. Based on a metric-driven Discrete Voronoi Diagram construction, our output is an optimized 3D triangular mesh with a user defined vertex budget. Our approach can deal with a wide range of applications, from high quality mesh generation to shape approximation. By using appropriate metric constraints the method generates isotropic or anisotropic elements. Based on point-sampling, our algorithm combines the robustness and theoretical strength of Delaunay criteria with the efficiency of entirely discrete geometry processing . Besides the general described framework, we show experimental results using isotropic, quadric-enhanced isotropic and anisotropic metrics which prove the efficiency of our method on large meshes, for a low computational cost.