How secure are computers in the U.S.A.? : An analysis of a series of attacks on Milnet computers

For 10 months, we monitored a systematic attack on 450 computers attached to the Defense Data Network. By analyzing the success of these attacks, we can estimate the vulnerability of nodes on the Milnet and (by extrapolation) civilian computers. We analyzed a particular type of attack: an outsider who attempts to log in by guessing at commonly used account name/password combinations.An outsider can expect some degree of access into about 13% of Milnet computers. Access to a programming environment is possible in at least 4%, and system manager privileges can be obtained by strangers in 2% of the sampled sites. Since this is only one of several methods used to enter these systems, these estimates are lower limits; other methods of entry can permit access to still more systems. These weaknesses are due to poor administration of computers, as well as systems distributed by vendors with security features disabled.     

Rectification of “restrained vs unrestrained”

For furnace testing of fire-resistant floor and roof assemblies in the United States, the ASTM E 119 standard (and similarly the UL 263 standard) permits two classifications for boundary conditions: “restrained” and “unrestrained.” When incorporating tested assemblies into an actual structural system, the designer, oftentimes a fire protection or structural engineer, must judge whether a “restrained” or “unrestrained” classification is appropriate for the application. It is critical that this assumption be carefully considered and understood, as many qualified listings permit a lesser thickness of applied fire protection for steel structures (or less concrete cover for concrete structures) to achieve a certain fire resistance rating if a “restrained” classification is confirmed, as compared with an “unrestrained” classification. The emerging standardization of structural fire engineering practice in the United States will disrupt century-long norms in the manner to which structural behavior in fire is addressed. For instance, the current edition of the ASCE/SEI 7 standard will greatly impact how designers consider restraint. Accordingly, this paper serves as an exposé of the “restrained vs unrestrained” paradigm in terms of its paradoxical nature and its controversial impact on the industry. More importantly, potential solutions toward industry rectification are provided for the first time in a contemporary study of this paradigm.     

Learning vector quantization and relevances in complex coefficient space

Neural Computing and Applications - In this contribution, we consider the classification of time series and similar functional data which can be represented in complex Fourier and wavelet...     

Polarisation independent liquid crystal lenses and contact lenses using embossed reactive mesogens

Liquid crystal lenses have promise in optical systems owing to their tunability combined with low electrical power, cost, and weight. A good example of such a system is switchable contact lenses for the correction of age‐related presbyopia. Sufficiently large phase modulation can be done using nematic liquid crystals in a meniscus lens configuration. However, the birefringent materials are inherently polarisation dependent, usually requiring orthogonal polarisations to be focussed separately. A novel method is presented for producing polarisation independent lenses based on reactive mesogens. Results are presented for a 2‐level and 3‐level diffractive Fresnel lenses, and the promise of the technique for use in refractive lenses such as contact lenses is discussed.     

Development and Psychometric Testing of the Rate and Accumulation Concept Inventory

Background

Because a fundamental understanding of rate and accumulation principles is important for engineering students across all subdisciplines, a method is needed to assess their understanding of these principles.

Purpose/Hypothesis

This article discusses the development of the Rate and Accumulation Concept Inventory (RACI) instrument and provides an analysis of its validity and reliability. The RACI is designed to test students’ (1) overall mastery of rate and accumulation concepts and (2) mastery of specific rate and accumulation concepts (e.g., mathematics, mass flow, and heat flow).

Design/Methods

Exploratory findings of students’ conceptual understanding prompted the development of a preliminary RACI instrument. Two pilot studies were conducted, with adjustments made to the instrument between each. Data from the second pilot were used to assess evidence of validity and reliability through classical test theory, item response theory, and structural equation modeling.

Results

Validity and reliability evidence indicates that the RACI can be used to measure students’ overall understanding of the concepts identified, though several items require revision or removal. Issues of potential construct underrepresentation were found in two of the conceptual categories.

Conclusions

The evidence of reliability and validity indicates the appropriateness of the RACI for assessing engineering students’ overall understanding of rate and accumulation principles. Additional research is needed to further enhance the validity and reliability of the RACI as a diagnostic tool, particularly in measuring students’ understanding of rate and accumulation concepts in particular physical contexts.     

DEVELOPMENT AND PRODUCTION OF FeAl BASED INTERMETALLIC ALLOYS

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Products from rapid heating of a brown coal in the temperature range 400–2300 °C

The devolatilisation behaviour of Yallourn brown coal was investigated under rapid heating conditions using two different flash pyrolysers: a fluid-bed reactor giving coal particle heating rates of 10⁴ °Cs^?1 with a gas residence time of about 0.5 s and a shock tube which generated heating rates of the order of 10⁷ °Cs^?1 and a 1 ms reaction time. Yields of products are reported covering pyrolysis temperatures in the range 400–2300 °C. Hydrocarbon gas yields reached maximum values which were remarkably similar for both reactors although occurring at different temperatures. Carbon oxide production was also similar for both reactors with CO yields reaching 30% wt/wt daf coal. These high yields of CO are very different from those reported for slow heating conditions. It appears that on flash heating, coal decomposition pathways change in a manner which increases CO yields at the expense of H₂0 and to a lesser extent C0₂, resulting in the volatilisation of additional carbon from the coal.     

Sulfur specificity in the bench‐scale biological desulfurization of crude oil by Rhodococcus IGTS8

Biological removal of organic sulfur from petroleum feedstocks may offer an attractive alternative to conventional thermochemical treatment due to the mild operating conditions and greater reaction specificity afforded by the nature of biocatalysis. Previous investigations have either reported the desulfurization of model sulfur compounds in organic solvents or gross desulfurization of crude oil without data on which sulfur species were being removed. This study reports initial sulfur speciation data for thiophenic sulfur compounds present in crude oil which may be used as a guide both as to which species are treated by the biocatalyst investigated as well as to where biocatalyst development is needed to improve the extent of biological desulfurization when applied to whole crudes. Biodesulfurization of two different crude oils in the 22–31 ° API specific gravity range with total sulfur contents between 1 and 2% is demonstrated in 1‐dm³ batch stirred reactors using wild type Rhodococcus sp IGTS8. While analysis of the crudes before and after biodesulfurization did not reveal a decrease in total sulfur, GC–MS did reveal significant (43–99%) desulfurization of dibenzothiophenes (DBT) and substituted DBTs. Fractionation of the whole crude, followed by analysis using gas chromatography–sulfur chemiluminescence detection (GC–SCD) of the aromatic fraction of the Van Texas crude oil, demonstrated a reduction of sulfur in this fraction from 3.8% to 3.2%. This research indicates that IGTS8 may be capable of biodesulfurization of refined products such as gasoline and diesel whose predominant sulfur species are dibenzothiophenes. Further biocatalyst development would be needed for effective treatment of the spectrum of sulfur‐bearing compounds present in whole crudes.