The Side Detection Efficiency of the Channel Multiplier

The ability of a channel multiplier to record radiation incident through its side walls has been studied, using mono-energetic MeV-electrons and protons and cosmic ray muons. The results indicate that about 25% of the total length of the detector is sensitive ta this radiation with a detection efficiency depending on particle type and energy.     

Trust dynamics in a large system implementation: six theoretical propositions

A large information systems implementation (such as Enterprise Resource Planning systems) relies on the trust of its stakeholders to succeed. Such projects impact diverse groups of stakeholders, each with their legitimate interests and expectations. Levels of stakeholder trust can be expected to vary in large-scale implementations (which can take several years), and cannot be taken for granted. Previous studies have largely focused on the taxonomic deconstruction of the trust construct, through point-in-time variance studies. They have identified the relationship between trust and project outcomes, but largely ignored the dynamics of trust relations. Giddens, as part of his study of modernity, theorises trust dynamics in relation to abstract social systems, though without focusing on information systems. We use Giddens’ concepts to investigate evolving trust relationships in a longitudinal case analysis of a large Integrated Hospital System implementation for the Faroe Islands. Trust relationships suffered a serious breakdown, but the project was able to recover and meet its goals. We develop six theoretical propositions theorising the relationship between trust and project outcomes, the maintenance, breakdown and restoration of trust, the role of the information system in restoring trust, and the emergent and reciprocal nature of trust and project outcomes.     

Recent Progress in Synthesis of Fine and Specialty Chemicals from Wood and Other Biomass by Heterogeneous Catalytic Processes

Synthesis of fine and specialty chemicals involving heterogeneous catalysts is discussed according to the type of reactions (e.g., hydrogenation, oxidation, isomerization, etc.) for various biomass derived feedstocks (carbohydrates, lignans, phenols, flavonoids, tannins, and stilbenes, tall oil, and fatty acids).     

Bücherschau

Ohne Zusammenfassung VDI     

A comparison of dimension reduction methods with application to multi-spectral images of sand used in concrete

This paper presents a comparison of dimension reduction methods based on a novel machine vision application for estimating moisture content in sand used to make concrete. For the application in question it is very important to know the moisture content of the sand so as to ensure good-quality concrete. In order to achieve a continuous in-line approach for the concrete mixing, digital image analysis is used. Multi-spectral images, consisting of nine spectral bands in the visible and near infrared (NIR) range, were acquired. Each image consists of approximately 9 million pixels. Five different sand types were examined with 20–60 images for each type. To reduce the amount of data, features were extracted from the multi-spectral images; the features were summary statistics on single bands and pairs of bands as well as morphological summaries. The number of features (2,016) is high in relation to the number of observations and, therefore, dimension reductive methods are needed. Furthermore, speed, which is an important consideration, is aided by the use of a small number of variables. On top of that, fewer dimensions tend to give more robust results. Two traditional statistical methods for dimension reduction (forward selection and principal components) combined with ordinary least squares and one sophisticated chemometrics algorithm (genetic algorithm-partial least squares) are compared to the recently proposed least angle regression-elastic net (LARS-EN) model selection method.     

Hemicellulose Hydrolysis in the Presence of Heterogeneous Catalysts

A prominent autocatalytic effect in the hydrolysis of hemicelluloses was observed in the presence of heterogeneous cation-exchange catalysts, Amberlyst 15 and Smopex 101. The kinetic models proposed were based on the reactivities of the non-hydrolysed sugar monomer units and the increase of the rate constant as the reaction progresses and the degree of polymerization decreases. General kinetic models were derived and the kinetic parameters, describing the autocatalytic effect, were determined by non-linear regression analysis. The kinetic model explained very well the overall kinetics, as well as the product distribution in the hydrolysis of hemicelluloses.

     

Chemical forms of ash-forming elements in woody biomass fuels

Advanced fuel characterization helps to predict ash fouling and slagging. Chemical fractionation analysis, i.e. sequential leaching in H₂O, NH₄Ac(aq), and HCl(aq), was applied to the biomass of spruce, pine, birch, and aspen. All of the Cl in the samples and most of the K, Na, and P were water-soluble; most of the Mg and Mn, and some of the Ca were leached in NH₄Ac; most of the Ca was leached in HCl; and most of the Si and S remained insoluble in the biomass. Ion Chromatography found the water-soluble Cl, P, and S present as Cl⁻, , and , respectively, and equimolar concentrations of as leached Ca in the acid fraction. The biomass solids were determined for anionic groups by methylene blue sorption. The contents were lowest in the wood samples (22-118 mmol/kg_D.S.) and highest in the bark samples (130-453 mmol/kg_D.S.). The closing of the ion charge balance led to a quantitative model for the ash-forming matter: water-soluble salts (KCl, K₂HPO₄, and K₂SO₄), acid-soluble minerals (CaC₂O₄), non-soluble minerals (SiO₂), and organically associated ash-forming elements (ionically bonded Ca²⁺, Mg²⁺, Mn²⁺, and K⁺, and covalently bonded P and S).     

Comparison of PIV and PDA droplet velocity measurement techniques on two high-pressure water mist nozzles

The need for reliable measurement of droplet velocities and droplet size has increased with the more widespread use of water mist systems. Two optical measuring techniques have been investigated, Particle Image Velocimetry (PIV) and phase Doppler anemometry (PDA). Measurements have been performed on two high-pressure nozzles, a hollow cone nozzle and a full cone nozzle. Both methods performed well close to the nozzle and further away from the nozzle. In the intermediate region the results obtained with PIV are biased against the larger droplets. The two methods complement each other, PIV giving the instantaneous velocity field and PDA giving both the droplet velocity and droplet size at a point. The measurement indicates that higher throw length can be archived with a full cone nozzle compared to the hollow cone nozzle, if both nozzles have the same cone angle and flow rate.     

Analysis and characterization of complex reactor behaviour: A case study

This paper analyzes the steady state and dynamic behaviour of a reactor for production of silicon metal, a submerged arc furnace. The furnace behaviour has been analyzed through simulation studies using a detailed, industrially proven, mechanistic simulation model. The analysis reveals that the silicon furnace has changing and complex dynamic behaviour, including inverse responses and slow modes, especially close to optimality. The paper analyzes the causes of the changing dynamic behaviour. It also shows how the margins to optimality can be deduced from the dynamic response to changes in the carbon coverage input.