Industrial Quantitative Control of the Pressing Behavior of Spray-Dried MnZn-Ferrite Granules

In the first stage of a broad factory stabilization program, the compaction properties of spray-dried granulated powders are investigated. Certain compaction process parameters are identified and include (i) the slide coefficient between powder material and die wall during compaction, which mainly affects the pressing tool life time, (ii) the ratio of the pressure drop over the compact to the axial mechanical strength of the compact, basically related to the chance of chipping and crack occurrence upon ejection, and (iii) the homogeneity of the density profile along the compact, basically related to the chance of crack development and product deformation during sintering. The effect of important factors, such as binder and lubricant content, granulate storage humidity, and compaction temperature, on those parameters is investigated. Based on factory data, specification values for the previously mentioned parameters are derived and used to control the compaction quality of the industrially spray-dried powders with satisfactory results.     

Parallel evolutionary training algorithms for “hardware-friendly” neural networks

In this paper, Parallel Evolutionary Algorithms for integer weightneural network training are presented. To this end, each processoris assigned a subpopulation of potential solutions. Thesubpopulations are independently evolved in parallel andoccasional migration is employed to allow cooperation betweenthem. The proposed algorithms are applied to train neural networksusing threshold activation functions and weight values confined toa narrow band of integers. We constrain the weights and biases inthe range [–3, 3], thus they can be represented by just 3 bits.Such neural networks are better suited for hardware implementationthan the real weight ones. These algorithms have been designedkeeping in mind that the resulting integer weights require lessbits to be stored and the digital arithmetic operations betweenthem are easier to be implemented in hardware. Another advantageof the proposed evolutionary strategies is that they are capableof continuing the training process ``on-chip', if needed. Ourintention is to present results of parallel evolutionaryalgorithms on this difficult task. Based on the application of theproposed class of methods on classical neural network problems,our experience is that these methods are effective and reliable.     

Coupled and constrained sylvester equations in system design

Several design problems, including reduced observer and compensator design, output feedback, and finite transmission zero assignment, are examined using the vehicle of the coupled Sylvester equations. The coupling is generally provided through a third equation involving the solutions of the two linear Sylvester equations, thus serving as a constraint on the allowed solutions. The Sylvester approach allows the unification of algebraic and geometric approaches, and provides numerical design algorithms through the tool of the Hessenberg form. This research was supported by the National Science Foundation under Grant No. NCR-9210408 and by the University of Hawaii Research Council under Contract No. 93868F728B425.     

Information systems evaluation as an organizational institution – experience from a case study

Abstract.  Information systems evaluation has strong social and organizational dimensions while existing research focuses primarily on the formal and positivistic characteristics. We investigate the organizational roles of the key stakeholders within the particular evaluation context (orientation). We focus on four evaluation orientations: control, sense-making, learning and exploratory. Experience from a case study is used to analyse these concepts and relations. The case organization attempted to move from a state of an ad-hoc evaluation practice to a more business-driven one. New tools, processes, roles and responsibilities were developed during the attempt. We examine the behavioural and organizational integration aspects of evaluation during that journey.     

Neural network-based colonoscopic diagnosis using on-line learning and differential evolution

In this paper, on-line training of neural networks is investigated in the context of computer-assisted colonoscopic diagnosis. A memory-based adaptation of the learning rate for the on-line back-propagation (BP) is proposed and used to seed an on-line evolution process that applies a differential evolution (DE) strategy to (re-) adapt the neural network to modified environmental conditions. Our approach looks at on-line training from the perspective of tracking the changing location of an approximate solution of a pattern-based, and thus, dynamically changing, error function. The proposed hybrid strategy is compared with other standard training methods that have traditionally been used for training neural networks off-line. Results in interpreting colonoscopy images and frames of video sequences are promising and suggest that networks trained with this strategy detect malignant regions of interest with accuracy.     

Characterisation and management of ash produced in the hospital waste incinerator of Athens, Greece

Bottom and fly ash samples (BASH and FASH) from the APOTEFROTIRAS S.A. medical waste incinerator (Athens, Greece) were investigated. Powder-XRD data and geochemical diagrams showed BASH to be an amorphous material, analogous to basaltic glass, and FASH consisting of crystalline compounds (mainly CaClOH). Bulk analyses by ICP-MS and point analyses by SEM-EDS indicated a high content of heavy metals, such as Fe, Cu and Cr, in both samples. However, BASH was highly enriched in Ni while FASH was additionally enriched in Zn and Pb. Gamma-ray measurements showed that the radioactivity of both ash samples, due to natural and artificial radionuclides ((137)Cs, (57)Co), was within the permissible levels recommended by IAEA. According to EN-type leaching tests, BASH was practically inert with regard to the mobility of the hazardous elements in aqueous media. FASH, however, showed a relatively high EN (and TCLP) leachability with regard to Pb and Zn. Finally, the stabilisation method, suggested for the treatment of FASH, included compression of the powder into briquettes using an appropriate machine and embedding the briquettes into pozzolanic cement blocks. After this treatment, TCLP and EN-type tests showed minimal release of Pb and Zn, thereby demonstrating a reliable management of ash waste.     

Comparison of radiosity and ray-tracing techniques with a practical design procedure for the prediction of daylight levels in atria

Designers are often facing prescribed requirements concerning daylight in atria. For the accurate prediction of the illuminances the designers should employ either computer simulations or apply empirical equations. This study compares results obtained by a practical design procedure and simulated results using Radiance and Lightscape 3.2.     

Factors affecting quality and postharvest properties of vegetables: integration of water relations and metabolism

Growing of vegetables in the field, harvesting, handling in the packing house and storage are events in the lifetime of vegetables that are analysed from the point of view of the complex series of physiological transitions taking place in each of these events. Water is the major factor limiting plant metabolism and plants have developed fascinating mechanisms to cope with this limiting factor. Therefore, water relations (water, pressure and osmotic potential) are used as criteria for discussing plant stress physiology aspects such as osmotic, elastic adjustment and cold acclimation, as well as mechanical stress when the vegetable is harvested and during handling in the packing house. Consequences for the storage potential and quality of the vegetable are discussed. After harvesting, the postharvest cell has the ability to complete a complex series of physiological transitions that will influence vegetable quality andfurther processing operations. Metabolic changes in the cytosol, cell membrane and cell wall are described.     

Multi-farm economic analysis of perennial energy crops in Central Greece, taking into account the CAP reform

This study analyses farm level economic impacts of biomass production from perennial crops including Arundo donax L. (arundo), Miscanthus x giganteus (miscanthus), Panicum virgatum L. (switchgrass) and Cynara cardunculus L. (cardoon). Regional biomass supply curves are estimated with a dynamic, multi-farm, mathematical programming model. Micro-economic data for the model are generated from farm surveys covering 52 farms containing a total of 400 parcels, in Central Greece. The study also examines the potential effects of the Common Agricultural Policy reform in 2003 on regional biomass supply. Simulations show that the policy reform toward decoupled subsidies lowers the cost of biomass between 15 and 25 euro per tonne. Switchgrass appears to be the most attractive option, followed by cardoon and miscanthus. Due to high specific machinery cost, arundo is never preferred. Relative to the agricultural policy setting of Agenda 2000, the biomass potential increases more for farms of small economic size and farms with a higher share of cotton.     

An adaptive fuzzy logic system for the compensation of nonlinear distortion in wireless power amplifiers

Neural Computing and Applications - Computational intelligent systems are becoming an increasingly attractive solution for power amplifier (PA) behavioural modelling, due to their excellent...