CHEOPS: A tool-integration platform for chemical process modelling and simulation

A large number of modelling tools exist for the construction and solution of mathematical models of chemical processes. Each (chemical) process modelling tool provides its own model representation and model definition functions as well as its own solution algorithms, which are used for performing computer-aided studies for the process under consideration. However, in order to support reusability of existing models and to allow for the combined use of different modelling tools for the study of complex processes, model integration is needed. This paper presents a concept for an integration platform that allows for the integration of modelling tools, combining their models to build up a process model and performing computer-aided studies based on this integrated process model. In order to illustrate the concept without getting into complicated algorithmic issues, we focus on steady-state simulation using models comprising only algebraic equations. The concept is realized in the component-based integration platform CHEOPS, which focuses on integrating and solving existing models rather than providing its own modelling capabilities.     

Some aspects of the biology of Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae), a pest of stored groundnuts in Nigeria

The biology of Plodia interpunctella (Hübner) was studied at various combinations of temperature and relative humidity. The incubation period of eggs ranged from 4 to 7 days. Development from laying of egg to adult lasted an average of 50.9 days at 25°C and 60% r.h. and 34.6 days at 30°C and 80% r.h. At 70 and 80% relative humidity, development was faster, more progeny were produced and the moths were heavier than at 60% r.h. Relative humidity had little effect on egg and pupal development.The larvae were negatively phototactic. However, the rate of development of the strain studied was similar in constant darkness, constant light or in a 12 hr-light: 12 hr-dark light system. The adult moths were immobile in diffused daylight. Locomotory activity was markedly high at dusk and was accompanied by an increase in the rate of pairing. Temperatures between 27 and 31°C did not appear to influence locomotory activity.Cracked groundnuts were more favourable for development than whole nuts which were in turn better than groundnut meal. The weight losses inflicted on infested groundnuts were directly correlated with the total weights of emerged moths and differed according to the treatment given to the medium. Losses in weight of about 8.7 and 8.6% were observed when 13 larvae completed development in 30 g of whole nuts and cracked nuts, respectively. Females consumed more food and were heavier than the males. Each larva ate an average of 140 mg of whole nuts and 190 mg of cracked groundnuts to complete development. The increases in free fatty acid values were not appreciably higher in infested media than in the control. Increases of 17.5 and 18.2 m-equiv of peroxides were observed in infested whole and cracked nuts, respectively.     

A data model for managing drug therapy within a patient data management system for intensive care units

The major intent of this article was to describe the design principles of the drug-therapy documentation module of the Patient Data Management System (PDMS) ICUData, in routine use at the intensive care unit (ICU) of the Department of Anesthesiology and Intensive Care Medicine at the University Hospital of Giessen, Germany, since February 1999. The new drug management system has been in routine use since March 2000. Until 8 January 2001, 1140 patients have been documented using this approach. It could be demonstrated that it was possible to transform the formerly unstructured text-based documentation into a detailed and structured model. The mediated benefit resulted in the automatic calculation of fluid balance. Further, detailed statistical analyses of therapeutic behavior in drug administration are now possible.     

Separation of plutonium and neptunium species by capillary electrophoresis-inductively coupled plasma-mass spectrometry and application to natural groundwater samples

Capillary electrophoresis (CE) was coupled to ICPMS in order to combine the good performance of this separation technique with the high sensitivity of the ICPMS for the analysis of plutonium and neptunium oxidation states. The combination of a fused-silica capillary with a MicroMist AR 30-I-FM02 nebulizer and a Cinnabar small-volume cyclonic spray chamber yielded the best separation results. With this setup, it was possible to separate a model element mixture containing neptunium (NpO2(+)), uranium (UO2(2+)), lanthanum (La3+), and thorium (Th4+) in 1 M acetic acid. The same conditions were also suitable for the separation of various oxidation states of plutonium and neptunium in different aqueous samples. All separations were obtained within less than 15 min. A detection limit of 50 ppb identical with 2 x 10(-7) M (3-fold standard deviation of a blank) was achieved. To prove the negligible disturbance of the plutonium and neptunium redox equilibria during the CE separations, plutonium and neptunium speciation by CE-ICPMS in acidic solutions was compared with the results of UV/visible absorption spectroscopy and was found to be in good agreement. The CE-ICPMS system was also applied to study the reduction of Pu(VI) in a humic acid-containing groundwater at different pH values.     

The Transformation of Computing: Riding the Wave

Abstract

In an IS world characterized by high stress and low unemployment, IS executives must not only secure scarce talent but also ensure that staffing patterns optimally meet corporate and IT goals. the staffing model presented here offers a new way of looking at IS culture, bringing IS in tandem with the strategic direction of the organization, and fostering ongoing, global assessment of overall IS performance.     

Von der Prozeßsimulation zur Lebenszyklusmodellierung

From Process Simulation to Lifecycle Modeling Process simulation is an established technology to support the design and operation of chemical processes. Since this technology has reached a mature state, an obvious question concerns emerging technologies which may succeed process simulation in the future. This contribution attempts to answer this question. The increasing capabilities of mathematical modeling and simulation on various levels of detail increasingly ask for the integration of available but independently developed and applied technologies across the process design lifecycle. Novel computer-based design support environments are required for this purpose. Such environments need to integrate existing modeling and simulation tools in a workflow oriented manner in order to provide context specific support during the whole design process.     

Imaging defects and junctions in single-walled carbon nanotubes by voltage-contrast scanning electron microscopy

Voltage-contrast scanning electron microscopy is demonstrated as a new technique to locate and characterize defects in single-walled carbon nanotubes. This method images the surface potential along and surrounding a nanotube in device configuration and it is used here to study the following: (a) structural point-defects formed during nanotube growth, (b) nano-scale gap formed by high-current electrical breakdown, (c) electronic defect such as electron-irradiation induced metal-insulator transition, and (d) charge injection into the substrate which causes hysteresis in nanotube devices. The in situ characterization of defect healing under high bias is also shown. The origin of voltage-contrast, the influence of the above defects on the contrast profiles and optimum imaging conditions are discussed.     

Vertically Aligned Hybrid Core/Shell Semiconductor Nanowires for Photonics Applications

A family of 1D organic/inorganic core/shell materials formed by an inner organic nanowire (ONW) conformally covered with an inorganic wide band gap semiconductor (ZnO or TiO₂) layer is presented. The developed procedure is a two‐steps vacuum methodology involving the formation of supported single crystal small‐molecule nanowires by physical vapor deposition and plasma enhance chemical vapor deposition (PECVD) of the inorganic shell. Critical characteristics of the last technique are the possibilities of low temperature and remote configuration deposition. Additionally, an initial step has to be included in order to create nucleation centers for the growth of the ONWs. The procedure and its general character in terms of the variability in organic core and inorganic shells composition and the applicability of the technique to different substrates are presented. The formation of the inorganic shell with no damage of the organic core single‐crystalline structure is demonstrated by high resolution transmission electron microscopy. The vertical alignment of the hybrid nanostructure is achieved thanks to the interaction of the 1D organic nanostructured surfaces and the glow discharge during the deposition of the inorganic shell by PECVD. The optical properties of these core/shell NWs are studied by fluorescence spectroscopy and microscopy, and their application as nanoscale waveguides in the 550–750 nm range addressed.     

The Case of a Broken Plank

A construction worker was seriously injured after falling from a roof to a concrete floor. He was working on a plank while placing insulation material when the accident occurred. The plank broke into three pieces. Visual observation of the plank indicated a relatively new plank. Further investigation of the plank revealed a grade of structural plank no. 2. A common practice is for a construction worker to use scaffold grade plank, which has twice the capacity of a structural grade plank. This represents the most probable procedural cause of the plank's failure. The most probable enabling cause (internal cause) of the failure is a local split at the midspan, whereas the most probable triggering cause (external cause) is the impact loads produced by the weight of the worker and the insulation material he carried while walking on the plank. The study also concluded a failure mechanism that was initiated by a longitudinal split at the midspan of the plank. The split weakened the plank and led to a transverse break at the midspan.     

Analysis of Causes of Falsework Failures in Concrete Structures

A study of 85 major falsework collapses of bridges and buildings in the past 23 yrs has documented the types of collapsed falseworks and failed permanent structures, the construction stages at the time of collapse, and the causes of failures. Three causes of failure were identified: triggering; enabling; and procedural causes. Most failures occurred because of the interaction of the triggering and enabling events that were, in many cases, produced by inadequacies in the procedural methods. Impact forces resulting from concreting operations have repeatedly triggered falsework failures that were enabled by deficiencies in the falsework bracings, components, connections, foundations, and design. Inadequate review of falsework design and monitoring procedures were frequent problems that facilitated the occurrernce of these events. The findings emphasize the importance of proper delineation of responsibility of each party in the building process in order to reduce falsework failures in the future.