The evolution of a collaborative authoring system for non-linear hypertext: A design-based research study

Learning in complex and ill-structured knowledge domains requires accommodation of multiple perspectives embedded in authentic activities and the reconciliation of those perspectives with personal beliefs resulting in conceptual change. Cognitive flexibility hypertext systems support that process by enabling learners to explore authentic cases from multiple thematic perspective. Study 1 showed that knowledge exploration alone is insufficient to engage those conceptual change processes. So we reasoned that providing learners with environments that engage more constructive, personal knowledge representation activities would better support conceptual change. However, these environments rarely support learners in structuring, integrating, and representing their personal beliefs with other perspectives. That became the goal of our iterative research process.     

Optimal transfer,ordering and payment policies for joint supplier–buyer inventory model with price-sensitive trapezoidal demand and net credit

This study aims at formulating an integrated supplier–buyer inventory model when market demand is variable price-sensitive trapezoidal and the supplier offers a choice between discount in unit price and permissible delay period for settling the accounts due against the purchases made. This type of trade credit is termed as ‘net credit’. In this policy, if the buyer pays within offered time M₁, then the buyer is entitled for a cash discount; otherwise the full account must be settled by the time M₂; where M₂ > M₁ ? 0. The goal is to determine the optimal selling price, procurement quantity, number of transfers from the supplier to the buyer and payment time to maximise the joint profit per unit time. An algorithm is worked out to obtain the optimal solution. A numerical example is given to validate the proposed model. The managerial insights based on sensitivity analysis are deduced.     

Single-mode junction-up TJS lasers with estimated lifetime of 106hours

Accelerated life test for single-mode junction-up TJS lasers have been carried out at ambient temperatures of 50, 60, 70, 80, and 90°C. The laser chips are passivated with Si3N4films and die bonded on Si submounts. Estimated mean time to failure is 10⁶h at 25°C.     

Biological activity of fluidized bed ethanol extracts from several edible mushrooms

In vitro antioxidant and anti-inflammatory activities of fluidized bed ethanol extracts of Pleurotus ostreatus PQMZ91109, PBS281009, M2191 (obtained from a laboratory greenhouse), Agaricus bisporus, Marasmius oreades, Craterellus cornucopioides, and Tuber melanosporum were investigated using free radical scavenging activities, metal chelating effects, inhibition of lipid peroxidation (inhibition of peroxyl radicals), xanthine oxidase, and lipoxygenase, and identification of antioxidant compounds. Levels of different compounds with antioxidant properties demonstrated the presence of more tocopherols than polyphenol carboxylic acids and flavones. HPLC showed that T. melanosporum extracts had high correlation values between levels of different active compounds and antioxidant assay results. Tocopherol levels were highly correlated (R ²=0.867) with anti-inflammatory activities and inhibition of lipid peroxidation. Fluidized bed ethanol extracts from dried mushroom fruit bodies can be a source of products rich in tocopherols, and can constitute an important ingredient in food supplements.     

Finite Elements on Generalized Elastic Foundation in Timoshenko Beam Theory

Using the Vlasov foundation model, a modified approach of the continuous beam on elastic supports, leading to both a mechanical model and the proper foundation parameters of the generalized foundation is shown. Two formulations of the beam finite-element with shear deformation effect, resting on a two-parameter elastic foundation, characterized by distinct contributions of normal and rotary reactions are presented. The behavior of the second foundation parameter in the two formulations is governed by the bending cross section rotation of a beam. The first formulation, yielding a free-of-meshing stiffness matrix and equivalent nodal load vector, is based on the transcendental or “exact” solution of the governing differential equation of the beam resting on the elastic layer of constant thickness. Considering a linear variation of the layer thickness along the beam, the second formulation is based on the assumed polynomial displacement field. Numerical comparisons with the exact approach show that the cubic formulation leads to better results when the foundation parameters are variables. The practical utility of the analogy between a tensile axial force and the second foundation parameter is exemplified, too.     

New chlorine‐resistant polyamide reverse osmosis membrane with hollow fiber configuration

New asymmetric hollow fiber reverse osmosis (RO) membrane was developed from a new chlorine‐resistant copolyamide [4T‐PIP(30)] with a piperazine moiety by a conventional phase‐separation method. The new 4T‐PIP(30) hollow fiber membrane has the same low‐pressure RO performance as cellulose triacetate hollow fiber membrane (FR = 205 L/m² day, Rj = 99.6%) and superior chlorine resistance as well as pH resistance to conventional aramid RO membranes. Structural analysis and viscoelastic study revealed that the new hollow fiber consisted of a top skin, dense layer, and microporous layer, and that it began to decrease its elasticity at 80°C in water, which is possibly related to its good and stable RO performance around room temperature. Several kinds of RO modules were made from the new hollow fiber membranes, for which RO performances were stable for 2 years in chlorinated feed water desalination (the free residual chlorine ranged from 0.l to 1.1 mg/L). © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 517–527, 2001     

A batch scheduling model for m heterogeneous batch processor

This research addresses a batch scheduling problem for single item parts with multi due date on m heterogeneous batch processors. The objective is to minimise total actual flowtime of parts through the shop. The total actual flowtime of parts in a batch is the multiplication of the interval between batch arrival time and the due date by the number of parts in the batch. Using the actual flowtime as the objective means it is oriented to satisfy the due date as a commitment to customers, and simultaneously to minimise the length of time of the parts spending in the shop. An algorithm to solve this problem is proposed.