Where did we go wrong? An examination of students treatment of experimental error in engineering mechanics laboratories

The ability of engineers and applied scientists to undertake experimental measurements is a fundamental requirement of the profession. However, it is not simply good enough to be able to perform experiments if we are not able to interpret the results. In this study, reports prepared by mechanical engineering students were examined to determine how students dealt with the disparity between experimental measurements and theoretical results in their Engineering Mechanics laboratories. Analysis of the reports, and discussions with students in their laboratory classes, revealed a superficial understanding or regard for experimental error. This superficial treatment of experimental error is, most likely, due to a number of factors that are discussed. Some possible strategies for addressing the issue are also examined.

Adote o artista não deixe ele virar professor: reflexões em torno do híbrido professor performer

Pós-graduação em Artes - IA

Instantaneous complex power applied to three-phase machines

The theory presented in this paper was primarily developed to give a physical interpretation for the instantaneous power flow on a three-phase induction machine, without a neutral conductor, on any operational state and may be extended to any three-phase load. It is a vectorial interpretation of the instantaneous reactive power theory presented by Akagi et al. Which, believe the authors, isn't enough developed and its physical meaning not yet completely understood. This vectorial interpretation is based on the instantaneous complex power concept defined by Torrens for single-phase, ac, steady-state circuits, and leads to a better understanding of the power phenomenon, particularly of the distortion power. This concept has been extended by the authors to three-phase systems, through the utilization of the instantaneous space vectors. The results of measurements of instantaneous complex power on a self-excited induction generator's terminals, during an over-load application transient, are presented for illustration. The compensation of reactive power proposed by Akagi is discussed and a new horizon for the theory application is opened.

Light noble gases in 12 meteorites from the Omani desert, Australia, Mauritania, Canada, and Sweden

We measured the concentrations and isotopic compositions of He, Ne, and Ar in 14 fragments from 12 different meteorites: three carbonaceous chondrites, six L chondrites (three most likely paired), one H chondrite, one R chondrite, and one ungrouped chondrite. The data obtained for the CV3 chondrites Ramlat as Sahmah (RaS) 221 and RaS 251 support the hypothesis of exposure age peaks for CV chondrites at approximately 9 Ma and 27 Ma. The exposure age for Shişr 033 (CR chondrite) of 7.3 Ma is also indicative of a possible CR chondrite exposure age peak. The three L chondrites Jiddat al Harasis (JaH) 091, JaH 230, and JaH 296, which are most likely paired, fall together with Hallingeberg into the L chondrite exposure age peak of approximately 15 Ma. The two L chondrites Shelburne and Lake Torrens fall into the peaks at approximately 40 Ma and 5 Ma, respectively. The ages for Bassikounou (H chondrite) and RaS 201 (R chondrite) are approximately 3.5 Ma and 5.8 Ma, respectively. Six of the studied meteorites show clear evidence for 3He diffusive losses, the deficits range from approximately 17% for one Lake Torrens aliquot to approximately 45% for RaS 211. The three carbonaceous chondrites RaS 221, RaS 251, and Shişr 033 all have excess 4He, either of planetary or solar origin. However, very high 4He/20Ne ratios occur at relatively low 20Ne/22Ne ratios, which is unexpected and needs further study. The measured 40Ar ages fit well into established systematics. They are between 2.5 and 4.5 Ga for the carbonaceous chondrites, older than 3.6 Ga for the L and H chondrites, and about 2.4 Ga for the R chondrite as well as for the ungrouped chondrite. Interestingly, none of our studied L chondrites has been degassed in the 470 Ma break-up event. Using the amount of trapped 36Ar as a proxy for noble gas contamination due to terrestrial weathering we are able to demonstrate that the samples studied here are not or only very slightly affected by terrestrial weathering (at least in terms of their noble gas budget).

A Question of Title: Property Rights and Asset Values

This paper examines the impact of land title systems on property values. The predominant system in the U.S., the recording system, awards title to claimants over current possessors, whereas the Torrens registration system awards title to the current owner. In theory, the registration system maximizes property value, all else equal, but in practice, the systems differ depending on the risk of a claim and administrative costs. A natural experiment in Cook County, Illinois, where both systems have existed since 1897, allows a test of the theory. The results, based on commercial and industrial properties, reveal that parcels tend to self-select into the two systems based on the predictions of the theory.

Suplemento á las Memorias para ayudar á formar un diccionario crítico de los escritores catalanes y dar alguna idea de la antigua y moderna literatura de Cataluña,

Mode of access: Internet.

The life and times of the Right Honourable Sir James R. G. Graham, bart.

Mode of access: Internet.

The hops industry of the United Kingdom /

Mode of access: Internet.

An essay on the external corn trade,

Mode of access: Internet.

A letter to the Right Honorable Sir Robert Peel, bart. etc., on the condition of England, and on the means of removing the causes of distress.

Added title page: The budget. A series of letters on financial, commercial, and colonial policy. By a member of the Political Economy club. No. IX.

Memoirs of William Lamb, second viscount Melbourne /

Includes index.

The future of NATO's tactical air doctrine /

"August 1997."

Memoirs of the Right Honourable William, second viscount Melbourne.

Mode of access: Internet.

Madame de Malguet : a tale of 1820.

A novel.