Persuasiveness of expert systems

Expert system advice is not always evaluated by examining its contents. Users can be persuaded by expert system advice because they have certain beliefs about advice given by a computer. The experiment in this paper shows that subjects (n = 84) thought that, given the same argumentation, expert systems are more objective and rational than human advisers. Furthermore, subjects thought a problem was easier when advice on it was said to be given by an expert system while the advice was shown in production rule style. Such beliefs can influence expert system use.     

Cross-validation of bimodal health-related stress assessment

This study explores the feasibility of objective and ubiquitous stress assessment. 25 post-traumatic stress disorder patients participated in a controlled storytelling (ST) study and an ecologically valid reliving (RL) study. The two studies were meant to represent an early and a late therapy session, and each consisted of a "happy" and a "stress triggering" part. Two instruments were chosen to assess the stress level of the patients at various point in time during therapy: (i) speech, used as an objective and ubiquitous stress indicator and (ii) the subjective unit of distress (SUD), a clinically validated Likert scale. In total, 13 statistical parameters were derived from each of five speech features: amplitude, zero-crossings, power, high-frequency power, and pitch. To model the emotional state of the patients, 28 parameters were selected from this set by means of a linear regression model and, subsequently, compressed into 11 principal components. The SUD and speech model were cross-validated, using 3 machine learning algorithms. Between 90% (2 SUD levels) and 39% (10 SUD levels) correct classification was achieved. The two sessions could be discriminated in 89% (for ST) and 77% (for RL) of the cases. This report fills a gap between laboratory and clinical studies, and its results emphasize the usefulness of Computer Aided Diagnostics (CAD) for mental health care.     

Comparison of the efficiency of immobilized and suspended systems in photocatalytic degradation

The photocatalytic degradation of formic acid in suspended and immobilized systems, with and without oxygen addition, are compared. In the immobilized system, oxygen addition to the reactor appeared to increase the efficiency, not only because oxygen acts as an efficient electron scavenger, but also due to increased mass transfer in this two-phase reactor. This immobilized system had an efficiency comparable to that of the suspended system. The addition of oxygen to the immobilized system appeared to increase the quantum yield with a factor 4, whereas the addition of oxygen to the suspended system hardly had any effect.     

Calcium methoxide initiated ring-opening polymerization of ε-caprolactone and L-lactide

Summary A commercial calcium dimethoxide and an in-situ generated calcium methoxide prepared from bis(tetrahydrofuran)calcium bis[bis(trimethylsilyl)amide] and methanol, were investigated as initiators for the ring-opening polymerization of ε-caprolactone and L-lactide. Commercial calcium dimethoxide initiated rapid ε-caprolactone polymerization at 120°C in bulk to give quantitatively a polymer with a polydispersity index around 1.3. Significant racemization was observed for L-lactide polymerization. The In-situ formed calcium methoxide promoted the solution polymerization of both ε-caprolactone and L-lactide to high conversion at room temperature over a short time period, yielding the corresponding polyesters with narrow molecular weight distribution. NMR spectra showed that the poly(L-lactide) isolated had a purely isotactic microstructure. The initiator efficiency could be tuned by varying the molar ratio of methanol and bis(tetrahydrofuran)calcium bis[bis(trimethylsilyl)amide]. Received: 11 August 2000/Revised version: 21 December 2000/Accepted: 3 January 2001     

Experimental and computational study of the “end of the vortex” phenomenon in reverse‐flow centrifugal separators

The “end of the vortex” (EoV) phenomenon, a flow instability that plays a crucial role in cyclone design and operation is studied in this article. In the experimental part of the study, tests were carried out to understand the origin and nature of the EoV and to study the effects of the flowrate through, and the length of, the cylindrical cyclone on the EoV. In the theoretical part, computational fluid dynamics (CFD) models, in agreement with the geometrical configurations and operating conditions used in the present and earlier experimental studies, were constructed and investigated. Three‐dimensional simulations were carried out using the large eddy turbulence model with the commercial CFD package Star‐CD. Bending of the vortex core to the wall of the vessel and its precessional motion, constituting the phenomenon of the EoV, was observed in the simulations in most geometries. The results are in a good agreement not only with the present experimental results but also with previous experimental observations. © 2011 American Institute of Chemical Engineers AIChE J, 2012     

Symposium review: Uncertainties in enteric methane inventories,measurement techniques,and prediction models

Ruminant production systems are important contributors to anthropogenic methane (CH₄) emissions, but there are large uncertainties in national and global livestock CH₄ inventories. Sources of uncertainty in enteric CH₄ emissions include animal inventories, feed dry matter intake (DMI), ingredient and chemical composition of the diets, and CH₄ emission factors. There is also significant uncertainty associated with enteric CH₄ measurements. The most widely used techniques are respiration chambers, the sulfur hexafluoride (SF₆) tracer technique, and the automated head-chamber system (GreenFeed; C-Lock Inc., Rapid City, SD). All 3 methods have been successfully used in a large number of experiments with dairy or beef cattle in various environmental conditions, although studies that compare techniques have reported inconsistent results. Although different types of models have been developed to predict enteric CH₄ emissions, relatively simple empirical (statistical) models have been commonly used for inventory purposes because of their broad applicability and ease of use compared with more detailed empirical and process-based mechanistic models. However, extant empirical models used to predict enteric CH₄ emissions suffer from narrow spatial focus, limited observations, and limitations of the statistical technique used. Therefore, prediction models must be developed from robust data sets that can only be generated through collaboration of scientists across the world. To achieve high prediction accuracy, these data sets should encompass a wide range of diets and production systems within regions and globally. Overall, enteric CH₄ prediction models are based on various animal or feed characteristic inputs but are dominated by DMI in one form or another. As a result, accurate prediction of DMI is essential for accurate prediction of livestock CH₄ emissions. Analysis of a large data set of individual dairy cattle data showed that simplified enteric CH₄ prediction models based on DMI alone or DMI and limited feed- or animal-related inputs can predict average CH₄ emission with a similar accuracy to more complex empirical models. These simplified models can be reliably used for emission inventory purposes.