Electrical Conductivity of Silver Vanadium Tellurite Glasses

We have investigated mixed electronic-ionic conduction in 0.5[ x Ag₂O·(1 − x )V₂O₅]–0.5TeO₂ glasses, where the Ag₂O amount varies over a range of 5–40 mol%. The glass samples have been prepared by quenching the melt. The ac conductivity has been measured at frequencies from 10 Hz to 100 kHz and temperatures of 300–425 K. The data indicate that the conduction mechanism changed from being predominantly electronic to ionic for Ag₂O contents of >27.5 mol%. This transition is due to the change in glass structure, which affects both electronic- and ionic-transport properties. The electronic dc conductivity results have been analyzed in terms of a small polaron-hopping model.     

La chaîne de conception analogique du système CASSIOPEE

Annals of Telecommunications - Cet article décrit un ensemble de logiciels destinés à la conception de circuits intégrésmosanalogiques. Ces programmes font partie du...     

Pulp and paper from corn stalks

The whole corn plant was successfully used for the production of pulp and paper by employing comparatively simple procedures of atmospheric pressure digestion followed by multi-stage bleaching. Water pre-treatment was found necessary to remove the dust particles. However, the use of boiling water was not recommended. The effects of the amount of active chlorine in the hypochlorite step on the optical and the physical-strength properties of paper were investigated. One-and two-stage pulping were compared and the effect of depithing after the first stage was studied.     

The emerging role of DSS: From passive to active

Existing decision support systems (DSS) are passive in their operation; their sole aim is to help maintain the current position of the firm. Conversely, Information Technology has recently adopted a more active role in the corporate strategy. This suggests that DSS could also undertake a far more active stance by identifying gaps in existing operations and suggesting ways to strengthen the standing of the firm. We renamed DSS containing this characteristics as Active Decision Support Systems (or ADSS) to emphasize their new orientation. Managers draw on their knowledge to suggest ways of alleviating problems or exploiting opportunities, and to evaluate each alternative in relation to the corporate objectives. Patterns and alternatives must be identified and incorporated into the ADSS. They should then be compared with the current position of the firm in order to determine whether any such problems/opportunities exist. This paper proposes an approach for designing ADSS; it introduces a knowledge-based component within the DSS framework and applies the concept of triggers to control the invocation of rule sets. A logical structure for ADSS is provided and the system use is illustrated through an example of strategic management. Issues for future research are highlighted.     

Business process redesign at CompuNet—standardizing top-quality service through IT

CompuNet, founded in 1984 in Cologne, Germany, has been regarded as the leader in reselling, networking, maintaining and supporting personal computers in Germany. As a multi-vendor system integrator and maintenance company, CompuNet has recently managed several business process reengineering (BPR) efforts to proactively prepare itself for the competitive environment in fast developing system service market. The case provides background information on the company and its strategic positioning. The study focuses on two successful IT-based BPR initiatives that stress CompuNet's shift from a sales to service orientation, concluding with an in-depth case discussion and a brief outlook.     

Path planning in construction sites: performance evaluation of the Dijkstra, A, and GA search algorithms

This paper presents the application of path planning in construction sites according to multiple objectives. It quantitatively evaluates the performance of three optimisation algorithms namely: Dijkstra, A^*, and Genetic algorithms that are used to find multi-criteria paths in construction sites based on transportation and safety-related cost. During a construction project, site planners need to select paths for site operatives and vehicles, which are characterised by short distance, low risks and high visibility. These path evaluation criteria are combined using a multi-objective approach. The criteria can be optimised to present site planners with the shortest path, the safest path, the most visible path or a path that reflects a combination of short distance, low risk and high visibility. The accuracy of the path solutions and the time complexities of the optimisation algorithms are compared and critically analysed.     

Avoiding and controlling double transformation artifacts

This article describes a set of standard control experiments for the authentication of new protein variants isolated through library selection and site-directed mutagenesis. These controls are specifically designed to rule out artifacts derived from 'double transformants' -- i.e. cells transformed with, or infected by, two different plasmids simultaneously. These seem to have been the source of past artifacts and, as demonstrated here, are far more common than generally recognized. By following standard protocols for cloning, plasmid isolation, subcloning, in combination with functional assays, the presence of such artifacts can be ruled out. This protocol needs to be applied for any new variant isolated from heterogeneous gene repertoires, and in particular for variants isolated by selection for either enzymatic activity, or binding.     

Corrosion of niobium in sulphuric and hydrochloric acid solutions at 75 and 95 °C

New Pourbaix diagrams were calculated at 25, 75 and 95 °C for the Nb-H₂O system. The species and were considered. Potentiodynamic polarization and mass loss experiments (14 days) were conducted in concentrated H₂SO₄ (20, 40 and 80 wt%) and HCl (20 and 38 wt%) solutions at 75 and 95 °C. Nb forms a metastable pentoxide (Nb₂O₅) in H₂SO₄ and HCl solutions which dissolves as . Corrosion rates decrease between the 40% and the 80% H₂SO₄ solutions. SEM micrographs show generalized pitting in the 20% and 40% H₂SO₄ solutions. Mass loss corrosion rates did not exceed 306 μm/yr. Corrosion rates estimated by Tafel extrapolation were within two orders of magnitude of those measured by mass loss and it is shown that this finding is consistent with the thickening of the oxide.     

Evaluation of Some Nonionic Surfactants Derived from Tannic Acid as Additives for Water‐Based Mud

Water‐based mud is the most‐used mud for oil and gas exploration and is generally considered to be more environmentally friendly than oil‐based or synthetic‐based mud. Therefore in this study we focused on water‐based mud and a series of nonionic surfactants derived from tannic acid was evaluated as additives for water‐based muds. The rheological properties for formulated water‐based muds contain nonionic additives at different temperatures were investigated including: apparent viscosity, plastic viscosity, yield point, gel strength, thixotropy and filtration properties. In addition to the relation between shear stress and shear rate were presented at different temperatures. The results of the studied nonionic surfactant showed improvements in the rheological properties when used as additives for water‐based mud formulation.