Classification Using Φ-Machines and Constructive Function Approximation

This article presents a new classification algorithm, called CLEF, which induces a -machine by constructing its own features based on the training data. The features can be viewed as defining subsets of the instance space, and they allow CLEF to create useful non-linear functions over the input variables. The algorithm is guaranteed to find a classifier that separates the training instances, if such a separation is possible. We compare CLEF empirically to several other classification algorithms, including a well-known decision tree inducer, an artificial neural network inducer, and a support vector machine inducer. Our results show that the CLEF-induced -machines and support vector machines have similar accuracy on the suite tested, and that both are significantly more accurate than the other classifiers produced. We argue that the classifiers produced by CLEF are easy to interpret, and hence may be preferred over support vector machines in certain circumstances.     

A tale of two cities: Price uniformity and price volatility in gasoline retailing

Retail gasoline markets have been found to exhibit either price volatility and price dispersion or price rigidity and uniformity across large metropolitan areas. The purpose of this paper is to identify a theoretical explanation for these patterns of pricing behavior, and to look for evidence consistent with the theory by examining market structure, conduct, and spatial pricing patterns in different retail gasoline markets in Canada. The study utilizes a novel source of price data: price observations reported to internet data collection sites. The firm and station specific price data are consistent with the presence of tacitly collusive behavior in one retail gasoline market and the presence of maverick retailers that prevent tacit collusion in the other retail market.The authors thank In-Touch Software Corporation for providing free of charge data collected through www.gastips.com, and Derek Tam and Glen Gower for providing free of charge data collected through www.ottawagasprices.com. The authors also wish to thank Roger Stough and anonymous referees for helpful advice, Don Schunk and participants at the 48th North American Meetings of the Regional Science Association International for their comments, and Ryan Reichl and Steven Yong for research assistance. Financial support provided by the Social Sciences and Humanities Research Council of Canada and the University of Alberta are gratefully acknowledged.     

Caste-dependent reactions to soldier defensive secretion and chiral alarm/recruitment pheromone inNasutitermes princeps

The soldier frontal gland secretion ofNasutitermes princeps induces strong short-range caste-specific alarm and attraction in both soldiers and workers. Soldiers are excited and patrol the surroundings of the source. The secretion per se does not induce ejection of additional secretion. Large workers of the second stage or older are massively attracted when tested in homogeneous groups. They focus their activities much more accurately than the soldiers around the source. The workers' reaction is less intense in the presence of soldiers. Large and small workers of stage 1 scarcely react at all to the secretion, whether tested in homogeneous or mixed groups. These results suggest the following complementary roles of soldiers and workers in defense. The first line of defense is provided by soldiers, which immobilize and incapacitate mobile enemies with their sticky secretion. Defense then is completed by older large workers as they eliminate the source of disturbance. The absence of reaction of young workers, small or large, confirms previous reports on age polyethism inNasutitermes observed in other contexts: young workers tend to stay in the nest. Alarm reactions are elicited by a source of (+)--pinene, the major monoterpene in the secretion, while its enantiomer, almost absent from the secretion, induces a much weaker reaction.     

Software project development cost estimation

This paper reports the results of an empirical investigation of the relationships between effort expended, time scales, and project size for software project development. The observed relationships were compared with those predicted by Lawrence Putnam's Rayleigh curve model and Barry Boehm's COCOMO model. The results suggested that although the form of the basic empirical relationships were consistent with the cost models, the COCOMO model was a poor estimator of cost for the current data set and the data did not follow the Rayleigh curve suggested by Putnam. However, the results did suggest that it was possible to develop cost models tailored to a particular environment and to improve the precision of the models as they are used during the development cycle by including additional information such as the known effort for the early development phases. The paper finishes by discussing some of the problems involved in developing useful cost models.     

Distillation column configurations in ammonia–water absorption refrigeration systems

In ammonia–water absorption refrigeration systems a purification process to reduce the water content in the vapour leaving the generator is required. During this process the water content in the vapour must be reduced to a minimum, otherwise it tends to accumulate in the evaporator and strongly deteriorates the efficiency of the system. The vapour purification can be carried out by partial condensation, by establishing a liquid–vapour counter flow or by combining both methods. In systems with partial condensation, the distillation column can be composed of one or more rectifiers using different cooling mediums, and the rectifying and stripping sections. In complete condensation systems only the rectifying and stripping sections can be used. Therefore different distillation column arrangements should be considered. This paper presents a study of several distillation column configurations for single stage ammonia–water absorption refrigeration systems with partial and complete condensation. In order to evaluate and compare the different configurations, a parameter that indicates the ratio of the ammonia vapour concentration increase in each part of the column to the total ammonia purification has been defined. The analysis has been based on the system COP. Finally the efficiency in each part of the column has been calculated to estimate its design requirements.     

Pietra Serena Mining in Fiesole. Part II: Geological Situation

The results are presented for the investigations into the geological estimate of Macigno formation representing an Oligocene-Miocene turbiditic sequence of the Northern Apennines, from the coarse-graded beds of which the Pietra Serena quarry stone was mined. It is shown that the sedimentological features, the physico-mechanical properties, and the mineralogical composition of rocks govern the distinctions in the operating performances.     

Dynamic Topography of Silver Azide Pre‐Explosion Luminescence

For the first time, it is experimentally shown that silver azide preexplosion luminescence emerging under weak laser excitation originates and develops locally. As the excitation intensity increases, the mean number of local luminous regions also increases, finally giving rise to homogeneous luminescence.     

Separation of W from Ta, Hf, Lu and Mo by BPHAC_5H_(11)OH/HCl extraction system (Model experiments for chemical study of seaborgium, the 106th element)

1 INTRODUCTIONIn the past years, the study of chemical property of transactinide elements gaineda broad interest from both experimental and theoretical chefests to determine theirpositions in the element periodic tabl.[1-4J. However, due to the "relativistic effect" oftransactinide elements, the deviation from regulaxity of the periodic table was not suitablefor .the transactinide elements compared with their lighter homologue elements. A fewOf modelling experiments aimed at studying the …     

SIMATIC S7-400H在膨胀机控制系统改造中的应用

文章介绍了SIMATIC S7-400H在膨胀机控制系统改造中的应用,总结了改造中的经验教训。减少设备故障,降低设备维护成本,消除了停产的风险(缺备件),对于正常生产缺少备件的用户来说,S5升级S7是一种切实可行的方法,值得借鉴。通过改造提高了生产的自动化程度,充分发挥了S7-400H系统的优势。