Experiment and computer simulation of particulate suspensions under shear flow

In this paper is described the role of molecular simulation as a useful quasi-‘experimental’ tool to help in understanding the interplay between molecular structure under shear flow and the manifested tribology/rheology. The development of non-equilibrium molecular simulation techniques are discussed, from the molecular dynamics approach through to the modelling of dispersions by brownian dynamics. Recent advances and extensions of the technique to weakly flocculated systems, such as electro-rheological fluids, are described.     

Continuous grinding in a small wet rod mill Part II. Breakage of some common ore minerals

A study has been made of the breakage of galena, marmatite, chalcopyrite and quartz, separately, in a calcite environment in a rod mill. The behaviour of all may be described by the same basic dynamic breakage model, which involves a breakage function, a rate function and a distribution of residence time function. The same breakage and distribution of residence time functions applied to all the minerals but the mean residence times decreased in the order galena > marmatite > chalcopyrite > quartz. Size for size, the values of the rate of breakage constants followed the same sequence.     

Photochemical Mechanism of an Atypical Algal Phytochrome

Phytochromes are bilin‐containing photoreceptors that are typically sensitive to the red/far‐red region of the visible spectrum. Recently, phytochromes from certain eukaryotic algae have become attractive targets for optogenetic applications because of their unique ability to respond to multiple wavelengths of light. Herein, a combination of time‐resolved spectroscopy and structural approaches across picosecond to second timescales have been used to map photochemical mechanisms and structural changes in this atypical group of phytochromes. The photochemistry of an orange/far‐red light‐sensitive algal phytochrome from Dolihomastix tenuilepis has been investigated by using a combination of visible, IR and X‐ray scattering probes. The entire photocycle, correlated with accompanying structural changes in the cofactor/protein, are reported. This study identifies a complex photocycle for this atypical phytochrome. It also highlights a need to combine outcomes from a range of biophysical approaches to unravel complex photochemical and macromolecular processes in multi‐domain photoreceptor proteins that are the basis of biological light‐mediated signalling.     

基于有限元的疲劳设计分析系统MSC/FATIGUE

简单描述了基于有限元分析结果进行疲劳寿命分析的思路,着重介绍了根据时域载荷输入计算构件内各点弹性应力应变响应的各种方法,以及从弹性应力应变结果近似计算弹塑性应力应变历史,并考虑多轴影响的各种途径;简单介绍了几种包含在ＭＳＣ／ＦＡＴＩＧＵＥ中的疲劳寿命计算方法及其各自的特点。总结了ＭＳＣ／ＦＡＴＩＧＵＥ系统的功能和特点,并给出了一个转向节疲劳分析例子。     

Developmental and Ripening-Related Effects on the Cell Wall of Pepino (Solanum muricatum) Fruit

Several cell wall components in ripening pepino fruit have been quantitatively and qualitatively characterised, with the aim of identifying their contributions to the loss of tissue firmness. Pepinos were graded into nine groups based on progressive, characteristic skin colour changes, previously shown to correspond with decreasing fruit firmness. While fruit softening began when the pepinos were still green but with newly acquired purple stripes, the first significant quantitative signs of cell wall modification (total pectin and hemicellulose content declining and CDTA-soluble pectin content increasing, on a fresh weight basis) were detectable later in ripening, when the fruit began to acquire yellow skin pigmentation. Gel fractionation studies demonstrated that there were increased levels of low-molecular-weight pectin and xyloglucan during pepino ripening. The change in molecular weight distribution of CDTA-soluble pectin occurred as fruit started to acquire yellow pigmentation, while xyloglucan polymers were modified at an earlier stage that coincided with the initial loss of firmness. © 1997 SCI.     

Lifts for evacuation—human behaviour considerations

To predict the time that a building will take to be evacuated in an emergency and to design lift systems capable of dealing with the demand, building designers need an understanding of the likely exiting behaviour of occupants. Because of the inherent difficulties of carrying out research in human behaviour, a number of approaches have been used in this investigation, including analysis of data from past fire events and a number of surveys. The results from this work suggest that the split of occupants using the stairs or lifts to evacuate is governed predominantly by floor level of the occupant and that it is unreasonable to expect that occupants will wait indefinitely for a lift to arrive in an emergency situation. The drop‐off in the percentage of occupants that will continue to wait for a lift with increasing waiting time is dependent on floor height. These results will allow building designers to make more realistic assumptions when designing evacuation strategies incorporating lifts. It is also hoped that a better understanding of the reservations that building users may have about using lifts for evacuation in emergency situations will allow better occupant training programmes to be developed. Copyright © 2011 John Wiley & Sons, Ltd.     

Granular Dynamics Simulations of Heap Formation: Effects of Feed Rate on Segregation Patterns in Binary Granular Heap

Granular dynamics simulations of a 2D heap formation have been carried out at low- and high-impact feed rates for a 3:1 diameter ratio binary mixture. The data have been analyzed using novel time series and filtering analysis to investigate key representative many-particle dynamic events of the assembly evolution. Spectral analysis of the time series has revealed quite different periodic behavior in the low- and high-impact cases. Segregation occurs in the low-impact case whereas more uniform mixing of the two types of particles arises at high impact, which is consistent with previous experimental observations. The low-impact feed regime is shown to be characterized by discrete surface avalanching manifesting kinetic sieving of the finer particles, in which the large particles move preferentially toward the free surface and segregate in the boundary layer on rolling toward the horizontal base. In contrast, the high-impact feed regime is marked by periodic lateral surging and vertical “pluming” of particles from below toward the free surface.     

General processes, rather than "goals," explain imitation errors.

The goal-directed theory of imitation (GOADI) states that copying of action outcomes (e.g., turning a light switch) takes priority over imitation of the means by which those outcomes are achieved (e.g., choice of effector or grip). The object