过筛煤粉在铸铁件湿型砂铸造生产中的作用

正确选择煤粉,其性能要求同时具有低灰分、高挥发分和高膨胀指数,以及具有合适的筛分粒度这一关键因素,以确保所生产的铸件没有机械粘砂缺陷和表面质量问题.通过仔细选择、安全操作和加工处理,煤粉仍然是一个优良的、简易的、经济的有效解决方案.煤粉在储存、加工和运输过程中易于调节,然后经过进一步的安全处理,最终被铸造厂使用.尽管煤粉有诸多不足之处,对于最终用户来说,它仍然是经济合算的.而且现代加工和筛分方法确保它在最佳条件下使用.     

Thanks, but I'm used to better: A relative rank model of gratitude.

We argue that more help does not necessarily lead to more gratitude. Rather, gratitude depends on how a given instance of help compares with the help that a person is used to receiving. Participants read vignettes detailing an event in which 11 different friends either lent them varying amounts of money or spent varying amounts of time providing help. The amount of gratitude elicited by a given amount of help (e.g., a loan of ￡36 [about $56] or 49 min help) differed substantially depending on how this amount ranked among the help they were getting from their other friends. Comparison across four experimental conditions suggested that these judgments operated via the same general cognitive mechanisms used to judge other social events and psychophysical stimuli (as outlined by range frequency theory). Although more help does lead to more gratitude, people appear to be sensitive to how that help compares with what others are providing, and experienced gratitude depends on these relative judgments. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

An estimate of the incidence of dark cutting beef in the United Kingdom

Eight slaughterplants with throughputs ranging from 20 to 300 animals per day were examined to estimate the incidence of dark cutting beef in the United Kingdom. Four thousand, eight hundred and sixteen animals were surveyed and information concerning animal category, source, season and preslaughter handling conditions recorded. Muscle samples were removed to estimate glycogen concentration and after incubation, ultimate pH. The overall incidence of dark cutting (pHu ≥ 6·0) was 4·1%. Increased incidence was associated with short (≤ 20 miles) and long (≥ 150 miles) transport distances. Slaughter on the day of arrival rather than overnight lairage also increased the incidence. Plants were classified into small (killing ≤ 50 animals per day) or large (killing ≥ 100 per day). Eighty per cent of the animals slaughtered passed through the large plants, and a higher incidence was also associated with these plants. Bulls had the highest incidence and heifers the lowest. A seasonal effect was recorded with the highest incidence found between July and October. The results, however, indicate that factors in addition to those examined are also important.     

Mapping ICT use at home and telecommuting practices: A perspective from work/family border theory

This study draws on the work/family border theory to investigate the role of information communication technology (ICT) use at home in shaping the characteristics of work/family borders (i.e. flexibility and permeability) and consequently influencing individuals’ perceived work-family conflict, technostress, and level of telecommuting. Data were collected from a probability sample of 509 information workers in Hong Kong who were not self-employed. The results showed that the more that people used ICT to do their work at home, the greater they perceived their work/family borders flexible and permeable. Interestingly, low flexibility and high permeability, rather than the use of ICT at home, had much stronger influences on increasing, in particular, family-to-work conflict. As expected, work-to-family conflict was significantly and positively associated with technostress. Results also showed that the telecommuters tended to be older, had lower family incomes, used ICT frequently at home, and had a permeable boundary that allowed work to penetrate their home domain. The theoretical and practical implications are discussed.     

时空连续统中的颜色和显示

一种在空间域和时间域进行混色处理的合成显示颜色的新方法，能提高图像质量，改善彩色显示器的性能。     

N-order direct form digital filters with integer arithmetic

For direct form digital filters with integer arithmetic, a characterization of the initial condition vector and state vectorX(), for a fixed, > 1, is established without the intermediate state vectors. This is used to determine initial conditions for stability and initial conditions for convergence to a limit cycle. Also, several properties of limit cycles are proven.     

Beamed microwave power transmission and its application to space

The general principles and special components of beamed microwave power transmission systems are outlined, and their application to the space program is discussed. For a beamed system starting with a DC source of power, converting it to a microwave beam for transmission through space, and ending with DC power output at the receiving end, an experimentally measured and certified DC-to-DC efficiency of 54% has been achieved. The application that is discussed in detail is a low-earth-orbit-to-geostationary-orbit (LEO to GEO) transportation system that depends on vehicles propelled by electric thrusters whose power is supplied by a microwave beam originating at the earth's surface. A scenario for such a system is chosen, and the performance results are presented. The advantages of the all electronic system over a chemically propelled system are enumerated. The principles of space propulsion, particularly as they relate to electric propulsion, are outlined. Key components at the terminals of the system are discussed. Environmental considerations are discussed