Simple and accurate scheme for fluid velocity interpolation for Eulerian-Lagrangian computation of dispersed flows in 3D curvilinear grids

Particle tracking in turbulent flows in complex domains requires accurate interpolation of the fluid velocity field. If grids are non-orthogonal and curvilinear, the most accurate available interpolation methods fail. We propose an accurate interpolation scheme based on Taylor series expansion of the local fluid velocity about the grid point nearest to the desired location. The scheme is best suited for curvilinear grids with non-orthogonal computational cells. We present the scheme with second-order accuracy, yet the order of accuracy of the method can be adapted to that of the Navier-Stokes solver.An application to particle dispersion in a turbulent wavy channel is presented, for which the scheme is tested against standard linear interpolation. Results show that significant discrepancies can arise in the particle displacement produced by the two schemes, particularly in the near-wall region which is often discretized with highly-distorted computational cells.     

Does prolonged sitting with limited legroom affect the flexibility of a healthy subject and their perception of discomfort?

This study examined for differences in subjective ratings of discomfort and comfort (Numerical Rating Scale) and objective measures of hamstring (Sit-Reach test), lumbar (Schöber’s test) and neck (Cervical Range of Motion) flexibility in healthy young subjects (n = 24) following 4 h of sitting on stacking chairs with or without limited legroom.When comparing the limited and unlimited legroom groups for differences in subjective and objective measures over 4 h, no significant findings were seen at the 5% level of confidence. However, differences in buttock, neck, shoulder and average discomfort were significantly negatively correlated to differences between post-warm up Sit-Reach scores (Correlation Co-efficients: −.763, −.434, −.408, and −.445; p values of .004, .034, .048, and .029, respectively). The difference in buttock discomfort was significantly negatively correlated to the difference between pre-warm up Sit-Reach scores (Correlation Coefficient: −.750; p = 0.005), post-sitting/pre-warm up and pre-sitting/post-warm up Sit-Reach scores (Correlation Coefficient: −.756; p = 0.004), and Schöber’s tests (Correlation Coefficient: −.578; p = 0.049).Although the above results suggest a relationship between a loss in flexibility and an increase in discomfort, the mechanism influencing this relationship is not clear from this study. What does appear clear is that the limiting of legroom to the parameters used in this study does not seem to exacerbate change in flexibility and discomfort which are a consequence of prolonged sitting.

Relevance to industry

Many forms of public transport provide limited legroom for their passengers, which may have an adverse affect on the user’s flexibility or experience of discomfort. Determining which objectively measurable parameters are associated with the subjective level of discomfort during sitting should allow for a greater appreciation of the changes that underpin such subjective perceptions.     

可持续理念下的风景园林评价体系研究

随着可持续理念在20多年的发展中被广泛接受和认可,城市风景园林的可持续性也受到广泛关注,各国都在探索可持续理念下的城市景观的建设与发展。对不同国家和中国台湾地区现阶段已经建立的可持续风景园林的评价体系,按照定性、定量及综合评价方法的方式进行分类,分别进行阐述与比较,并提出了中国建立可持续风景园林评价体系的建议。     

Assessment of grape skin hardness by a puncture test

BACKGROUND: The release of grape components during wine making might be related to the mechanical properties of the skin, in particular its hardness. Samples from three varieties collected during the 2005 vintage season in Piedmont, Italy, were tested for their skin hardness using a texture analyser. The goal was to understand the statistical interactions between three factors—variety, cluster position and puncture point—and their influence on the grape skin hardness. A discussion on the relationship between the size of the sample used and the confidence level is also provided. RESULTS: Results of the ANOVA test showed that there is an interaction between the variety and the puncture point when measuring the skin hardness with the break energy. The position of the berry on the cluster does not affect the berry skin break energy. We also show that a sample size depend on the variety tested. CONCLUSION: The break energy is more useful in understanding the effect of the three factors on the skin hardness. Other factors that might affect the puncture test applied to grapes need to be studied in the future and the usefulness of the test in winemaking will need to be further developed. Copyright © 2008 Society of Chemical Industry     

A study of heat distribution and dissipation in a micromachined chemoresistive gas sensor

A micromachined chemoresistive gas sensor was studied from the point of view of heat distribution and thermal dissipation: this innovative device for environmental pollutant gas monitoring, is based on a sensitive film of semiconductor metal oxides, kept in temperature by a platinum resistor. In order to avoid electrical interactions between the film heater and the contacts for the film reading, the heater is driven by a square wave, and the film is read when no voltage is provided. Since the working temperature of the film is extremely important for its operation, it is crucial to maintain the temperature fluctuations within few degrees; to this end, in this work we study the heat distribution and dissipation of such a device, aiming to set a proper heating frequency, which will assure a right stability of the working temperature.     

A method based on Graph Theory and Three Way Decisions to evaluate critical regions in epidemic diffusion:

Applied Intelligence - The paper reports the results of an analysis of COVID-19 diffusion in Italy. The analysis was carried out with a new method based on the combined use of a 3 Way Decisions...     

Designing and Rightsizing the Information System Architecture

Information system design and sizing constitute a complex, top-down process that tailors the technology architecture to application requirements. Practitioners usually tackle this top-down process by focusing on individual design aspects, such as data or specific applications, and by relying on their previous experiences to compare alternative architectural solutions. Acquisition costs are usually accounted for, but related operating and maintenance costs are often neglected or underestimated. The complexity of optimizing individual design problems leads researchers to avoid a global optimization perspective and, thus, the IS architecture is usually a result of the juxtaposition of multiple local optima.This paper takes an overall perspective on the cost minimization problem of information system design to achieve a better trade-off between cost and performance over the whole expected life of the technology architecture. A comprehensive design methodology is discussed as an integrating framework that accounts for all categories of costs, including design, implementation, maintenance, and operation, to achieve a globally cost-minimizing solution.     

Hyperazeotropic ethanol salted-out by extractive distillation. Theoretical evaluation and experimental check

A distillation process for the production of hyperazeotropic ethanol from a dilute wine obtained from the fermentation of biomass has been studied. This process utilizes the coupling of a soft preconcentration stage and of a dehydration stage based on the salting-out effect produced by calcium chloride on the ethanol in an aqueous solution, with the disappearance of the azeotrope. The salt is employed in a close cycle, due to the presence of a regeneration stage, therefore no consumption of calcium chloride is noticed.

The distillation process utilizes one column consisting of two sections operating at different pressures in order to reach an efficient heat recovery.

In this paper, a simplified flow-sheet of the process and the principal operating conditions of the distillation column are illustrated. When compared with other processes, conventional or under development, this one is characterized by the promising reduction of the specific energy requirement.

The operating conditions chosen for the distillation with salt have been experimentally checked using a laboratory column running continuously with calcium chloride as salting-out agent. Moreover, the experiments confirmed the reliability of the mathematical model of the process. Further experiments are in progress with the aim of utilizing a mixture of salts which can be fed from the bottom of the dehydration section back to the fermentor, so that the salt regeneration stage can be reduced.     

Comparison of thin epitaxial film silicon photovoltaics fabricated on monocrystalline and polycrystalline seed layers on glass

We fabricate thin epitaxial crystal silicon solar cells on display glass and fused silica substrates overcoated with a silicon seed layer. To confirm the quality of hot‐wire chemical vapor deposition epitaxy, we grow a 2‐µm‐thick absorber on a (100) monocrystalline Si layer transfer seed on display glass and achieve 6.5% efficiency with an open circuit voltage (V_OC) of 586 mV without light‐trapping features. This device enables the evaluation of seed layers on display glass. Using polycrystalline seeds formed from amorphous silicon by laser‐induced mixed phase solidification (MPS) and electron beam crystallization, we demonstrate 2.9%, 476 mV (MPS) and 4.1%, 551 mV (electron beam crystallization) solar cells. Grain boundaries likely limit the solar cell grown on the MPS seed layer, and we establish an upper bound for the grain boundary recombination velocity (S_GB) of 1.6x10⁴ cm/s. Copyright © 2014 John Wiley & Sons, Ltd.