Prediction of stress-strain behaviors in steels using an integrated constitutive, FEM and ANN model

Austenitic steels with a carbon content of 0.0037 to 0.79 wt% C are torsion tested and modeled using a physically based constitutive model and an Integrated Phenomenological and Artificial neural Network (IPANN) model. The prediction of both the constitutive and IPANN models on steel 0.017 wt% C is then evaluated using a finite element (FEM) code ABAQUS with different reduction in the thickness after rolling through one roll stand. It is found that during the rolling process, the prediction accuracy of the reaction force from FEM simulation for both constitutive and IPANN models depends on the strain achieved (average reduction in thickness). By integrating FEM into IPANN model and introducing the product of strain and stress as an input of the ANN model, the accuracy of this integrated FEM and IPANN model is higher than either the constitutive or IPANN model.

An experiment to assess the learning benefits of employing accounting software in the classroom

This paper reports on an experiment analysing the development of students' understanding of accounting concepts by comparing three different teaching strategies: a traditional tutorial (workshop), exposure to a commercial accounting package, and a control group. Findings indicate that integration of a commercially available accounting package into accounting curricula does not significantly enhance students' understanding of accounting concepts. As this experiment employed a randomised allocation of students to groups, a control group, and identical pre and posttests, these findings are robust to alternative explanations such as learning styles and motivation.

A scale-model room as a practical teaching experiment

A practical experiment is described which was used to help university students increase their understanding of the effect of construction methods and window design on passive solar heating and electrical heating. A number of one tenth scale model rooms were constructed by students and sited out-of-doors in the late autumn. The models were fabricated to mimic available commercial construction techniques with careful consideration being given to window size and placement for solar access. Each model had a thermostatically controlled electric heating element. The temperatures and electricity use of the models were recorded using data-loggers over a two week period. The performances of the models based on energy consumption and internal temperature were compared with each other and with predictions based upon thermal mass and R-values. Examples of questions used by students to facilitate this process are included. The effect of scaling on thermal properties was analysed using Buckingham’s p-theorem.

An experiment using ICT to investigate pure voting power

We present an experiment to evaluate the accuracy of power indices by measuring the political power embodied in blocks of votes per se. The experiment incorporates several players interacting in lCT chat rooms under supervision. The chat rooms and the selection process reduce or eliminate other political forces leaving logroIIing as the primary political force.

Contact pressure and wear in sheet metal forming - an FEM analysis

Wear is the principal cause of tool failure in most sheet metal forming processes. It is well known that the contact pressure between the blank and the tool has a large influence on the wear of the tool, and hence the tool life. This investigation utilises the finite element method to analyse the contact pressure distribution over the die radius for a particular deep drawing process. Furthermore, the evolution of the predicted contact pressure distribution throughout the entire stroke of the punch is also examined. It was found that the majority of the process shows a steady state pressure distribution, with two characteristic peaks over the die radius, at the beginning and end of the sheet contact area. Interestingly, the initial transient contact pressure response showed extremely high localised peak pressures; more than twice that of the steady state peaks. Results are compared to wear reported in the literature, during similar experimental deep drawing processes. Finally, the significance and effect of the results on wear and wear-testing techniques are discussed.

A controlled experiment on yarn hairiness and fabric pilling

This study focused on the hairiness of worsted wool yarns and how it affects the pilling propensity of knitted wool fabrics. Conventional worsted ring spun yarns were compared with comparable SolospunTM yarns and yarns modified with a hairiness reducing air nozzle in the winding process (JetWind). Measurements of yarn hairiness (S3) on the Zweigle G565 hairiness meter showed a reduction in the S3 value of approximately 46% was achieved using SolospunTM ring spinning attachment and a 33% reduction was achieved using the JetWind process. Interestingly, subsequent evaluation of the pilling performance of fabrics made from the SolospunTM spun yarn and JetWind modified yarn showed a half grade and full grade improvement, respectively over a similar fabric made from conventional ring spun yarns. This result suggested that a relatively large reduction in yarn hairiness was needed to achieve a moderate improvement in fabric pilling, and that the nature of yarn hairiness was also a key factor in influencing fabric pilling propensity. It is postulated that the wrapping of surface hairs by the air vortex in the JetWind process may limit the ability of those surface fibers to form fuzz and reach the critical height required for pill formation.

Pectinase production by solid fermentation from Aspergillus niger by a new prescription experiment

The Ordos Plateau in China is covered with up to 300,000 ha of peashrub (Caragana) which is the dominant natural vegetation and ideal for fodder production. To exploit peashrub fodder, it is crucially important to optimize the culture conditions, especially culture substrate to produce pectinase complex. In this study, a new prescription process was developed. The process, based on a uniform experimental design, first optimizes the solid substrate and second, after incubation, applies two different temperature treatments (30 °C for the first 30 h and 23°C for the second 42 h) in the fermentation process. A multivariate regression analysis is applied to a number of independent variables (water, wheat bran, rice dextrose, ammonium sulfate, and Tween 80) to develop a predictive model of pectinase activity. A second-degree polynomial model is developed which accounts for an excellent proportion of the explained variation (R² = 97:7%). Using unconstrained mathematical programming, an optimized substrate prescription for pectinase production is subsequently developed. The mathematical analysis revealed that the optimal formula for pectinase production from Aspergillus niger by solid fermentation under the conditions of natural aeration, natural substrate pH (about 6.5), and environmental humidity of 60% is rice dextrose 8%, wheat bran 24%, ammonium sulfate ((NH₄)₂SO₄) 6%, and water 61%. Tween 80 was found to have a negative effect on the production of pectinase in solid substrate. With this substrate prescription, pectinase produced by solid fermentation of A. niger reached 36.3 IU/(g DM). Goats fed on the pectinase complex obtain an incremental increase of 0:47 kg day^-1 during the initial 25 days of feeding, which is a very promising new feeding prospect for the local peashrub. It is concluded that the new formula may be very useful for the sustainable development of arid and semiarid pastures such as those of the Ordos Plateau.

Design of electrical infrastructure at container terminal and 'net metering'

Net metering is generally a consumer-based incentive for renewable sources such as wind or solar power systems also referred to as dasiacogenerationdasia. It is still a grey area for container terminals with large electric machines, such as quay cranes, automatic stacking cranes, that can operate in the regenerative mode and export electric energy to the grid. With actual measured electrical data presented for discussion, this paper provides information for the readers to provide a better understanding of their access to net metering, ultilizing their electrical equipment capabilities and be informed for their next negotiation with the power supply company.

Power demand and energy usage of container crane - comparison between AC and DC drives

The electrical data of two quay cranes, one has a DC drive system and the other has an AC drive system, in actual working conditions at a container terminal are measured and presented in this paper. Peak demand, energy usage, power factor and power quality are examined and compared.