A clustering performance measure based on fuzzy set decomposition

Clustering is primarily used to uncover the true underlying structure of a given data set and, for this purpose, it is desirable to subject the same data to several different clustering algorithms. This paper attempts to put an order on the various partitions of a data set obtained from different clustering algorithms. The goodness of each partition is expressed by means of a performance measure based on a fuzzy set decomposition of the data set under consideration. Several experiments reported in here show that the proposed performance measure puts an order on different partitions of the same data which is consistent with the error rate of a classifier designed on the basis of the obtained cluster labelings.     

Keyboard design through physiological strain measurements

The physiologically tolerable range of positions for the joints of the upper extremities have been investigated for typing tasks by recording the myoelectric activities of the involved muscles. For long-term typing tasks a split keyboard is recommended allocating a key field to each hand. The fields should be rotated against each other in the horizontal plane and inclined laterally.     

Odour emission ability (OEA) and its application in assessing odour removal efficiency

Odourous emissions from sewer networks and wastewater treatment plants (WWTPs) can significantly impact a local population. Sampling techniques such as wind tunnels and flux hood chambers are traditionally used to collect area source samples for subsequent quantification of odour emission rates using dilution olfactometry, however these methods are unsuitable for assessing liquid samples from point sources due to the large liquid volumes required. To overcome this limitation, a gas phase sample preparation method was developed for assessing the total Odour Emission Ability (OEA) from a liquid sample. The method was validated using two volatile organic sulphur compounds (VOSCs), dimethyl-trisulphide (DMTS) and bismethylthiomethane (BMTM) that are frequently detected from sewers and WWTPs and are relatively stable compared with common VOSCs like mercaptan or methyl mercaptan. The recovery rates of DMTS and BMTM were quantified by injecting a known volume of a standard liquid sample into Tedlar bags using a static injection and a dynamic injection methodology. It was confirmed that both dynamic and static injection methods at ambient condition achieved high recovery rates with no need to consider increasing evaporation by elevating the temperature. This method can also be used to assess odour removal effectiveness of liquids by comparing the OEA before and after the treatment tests. Two application examples were presented.     

Tenderising in M. longissimus dorsi of beef, veal, rabbit, lamb and pork

The decrease in toughness of M. longissimus dorsi with storage time at 1°C was effectively described by an exponential decay equation. The average rate constant for beef, veal and rabbit was 0·17 whilst that for lamb was 0·21 and that for pork, 0·40 days(-1). However, the rate constants were not significantly different due to variations both within muscles and between animals. On average, 50% of the tenderising occurred in 2 days for pork and in 4·2 days for beef, veal and rabbit, and 80% in 4·9 and 9·5 days, respectively. At the completion of tenderising, beef and rabbit were the toughest and pork the most tender, whilst the greatest tenderising occurred in beef and lamb.     

精馏塔中回流比与板数的关系

对于二元溶液的蒸馏中最小理论板数、最小回流比、相对挥发度、q(由进料转化为饱和蒸汽所需热量/潜热)及在任意回流比之下的板数之间的精确关系,本文提供了代数方程的形式以及便于使用的算图。该法优于许多已有的近似经验关系,尤其是对于蒸馏过程中主要的板数是在提馏段的情况。特别适用于多组份蒸馏中,比经验的简捷方法要优越。文中并有例题。     

纯真童年

童年的往事,就像流过心里的一粒细砂,有无奈酸涩,也有快乐温馨……小时候家里很穷,每年冬季的早晨上学时,总是吃着含有冰碴儿的玉米面或者红薯面窝窝头,每次看到队长家和我一样大的女孩吃着粘有麻油和辣椒油的杂面窝头时,总羡慕得不得了,想像那是世界上最美最香的食品了!记忆中家里喝的汤也常是有少许白面的萝卜汤,能照得见人影儿。小时候最喜欢对着一碗汤,当镜子照来照去的。那时候用红线绳扎着羊角辫,头上别着从地里采来的各色小花,用筷子搅一搅汤水,满碗的缤纷色彩,一颗小小的心便盛在了汤碗里!长到十岁时,便开始随大人到田里劳作,繁重的…     

Use of synchrotron radiation for the measurement of fluorescence lifetimes with subpicosecond resolution

A method for the measurement of fluorescence lifetimes with subpicosecond resolution is described. The temporal resolution is achieved by using the high harmonic content of the synchrotron radiation produced by an electron storage ring.