Managing a Y2K project-starting now

As the year 2000 draws near, solutions to the Year 2000 (Y2K) problem seem both abundant and elusive. At this late date, Y2K problems require fast, flawless solutions. This article sets forth a practical work plan for assessing and correcting problems in existing application programs     

Windows 2000 security: A postmortem analysis

Introduction

After initially releasing Windows 2000 (W2K) in February 2000, Microsoft touted it as a secure operating system, one that was far improved over its predecessor, Windows NT(WNT). Yet even before Microsoft released W2K the software giant announced that it would release Service Pack 1 (SP1) for this operating system. The information security community immediately wondered whether the claims about the much improved security in W2K were true; many events and findings since then have reinforced this doubt. After a reign of three years as Microsoft's flagship operating system, last year Microsoft rolled out its newest server operating system, Windows Server 2003 (WS2003), signaling the end of an era for the W2K operating system. Windows XP (WXP) had already supplanted W2K Professional as the newest workstation operating system several years before. This is not to say that nobody uses W2K any more—to the contrary. But as W2K continues to increasingly take a proverbial back seat to newer Microsoft operating systems, now is a good time to take a retroactive look at W2K from a security viewpoint. Was it a success from a security perspective? What were its major failings and why? This paper addresses these issues.     

Minimizing L max for large-scale,job-shop scheduling problems

The academic literature in 2000 presented a procedure for solving the job-shop-scheduling problem of minimizing L _max. The iterative-adaptive simulation-based procedure is shown here to perform well on large-scale problems. However, there is potential for improvement in closing the gap between best-known solutions and the lower bound. In the present paper, a simulated annealing post-processing procedure is presented and evaluated on large-scale problems. A new neighbourhood structure for local searches in the job-shop scheduling problem is developed. The procedure is also evaluated using benchmark problems and new upper bounds are established.     

Impact of Brownian motion on the particle settling in molten metals

Understanding the settling behavior of nanoparticles in molten metals/alloys is important as it will aid in achieving uniform dispersions of reinforcement particles in metal matrix nanocomposites. Uniform dispersions are necessary to activate the Orowan strengthening mechanism, which can increase yield strength without significant diminishment of ductility. In this work, an analytical model of particle size effects on settling is described that takes into account both deterministic Stokes’ law and stochastic Brownian motion. The model shows a clear transitional behavior where settling velocity follows Stokes’ law for large particles and then drops to zero for small particles implying that Brownian motion predominates. It indicated that, in the Brownian motion regime, where the discrete nature of the liquid must be considered, the random motion imparted by unbalanced collisions can overwhelm the motions normally imposed by forces such as gravity, viscous drag, and thermal/concentration gradients.     

A Multiplexed Four Channel On-Line Iodine Monitor

Abstract

A robust autonomous system is described for the spectrophotometric determination of aqueous elemental iodine in multiple flowing process streams. The quantitative methodology uses characteristic absorbance at 460 nm, corrected for baseline drift using absorbance at 600 nm. Linear dynamic ranges of 0.2 - 25 mg/L, 0.4 - 45 mg/L, and 2 - 250 mg/L have been attained using path lengths of 1 cm, 5 cm, and 10 cm respectively. The multiplexed iodine monitor has proven capable of continuous operation for periods of up to eighteen months.     

Multilevel surrogate modeling of an amine scrubbing process for CO2capture

Surrogate models provide a powerful method for simplifying calculations within complex simulations. While surrogate models are broadly applied within chemical engineering, little research exists investigating the level of surrogacy's impact on a simplified process model. In this work, artificial neural networks (ANN) and Kriging models are used as surrogate models at the process, process unit, and thermodynamic levels for a CO₂ amine scrubbing process. The surrogated models are evaluated against an Aspen Plus simulation for accuracy, convergence behavior, computational cost, and ability to extrapolate. The thermodynamic and process unit models can better handle discontinuous, non-smooth behavior, and convergence issues in the surrogated truth model, but poor conditioning in the final system of equations results in a lower accuracy and convergence rate than the process level surrogate. Beyond model accuracy, availability of diverse data, intended re-usability, and the desired outputs must be considered when selecting a level of abstraction.     

Quantitative determination of fluorotelomer sulfonates in groundwater by LC MS/MS

Aqueous film-forming foams (AFFF) are complex mixtures containing fluorocarbon- and hydrocarbon-based surfactants that are used to fight hydrocarbon-fueled fires. The military is the largest consumer of AFFF in the United States, and fire-training activities conducted at military bases have led to groundwater contamination by unspent fuels and AFFF chemicals. A direct-injection, liquid-chromatography tandem mass spectrometry (LC MS/MS) method was developed to quantify a suite of fluorotelomer sulfonate surfactants in groundwater collected from military bases where fire-training activities were conducted. The 4:2, 6:2, and 8:2 fluorotelomer sulfonates were detected and quantified in groundwater from two of the three military bases. The total fluorotelomer sulfonate concentrations observed at Wurtsmith AFB, MI, and Tyndall AFB, FL, ranged respectively from below quantitation (< or = 0.60) to 182 microg/L and from 1100 to 14,600 microg/L. Analyses of a fluorotelomer-based AFFF concentrate by negative ion fast atom bombardment/mass spectrometry and LC MS/MS analyses indicate that the AFFF concentrate contains only a small amount of fluorotelomer sulfonates and that fluoroalkylthioamido sulfonates are the main anionic fluorosurfactant in the mixtures. More research is needed to determine the fate of fluoroalkylthioamido sulfonates in the environment.     

Hydrodesulfurization of Diesel Feeds by Association of a Catalytic Process and a Separation Process Using Charge-Transfer Complexes

While deep hydrodesulfurization of gas oil is more and more important, elimination of sulfur compounds such as 4,6-dialkyldibenzothio-phenes still attracts considerable attention. A new process based on the association of a separation process by charge-transfer complex (CTC) formation and classical catalytic hydrotreating (HDT) was evaluated. The results indicated that a CTC pretreatment allows the rate of hydrodesulfurization (HDS) to increase and the final sulfur level to decrease. This process is even more efficient for feeds difficult to desulfurize.     

Dietary Fatty‐Acid Compositions Are more Strongly Reflected in Fatty than Lean Dorsal Fillets of Common Carp (Cyprinus carpio L.)

In this fish‐feeding study, we tested similarity patterns between fatty acids (FA) in diets and common carp (Cyprinus carpio) of fish ponds used for semi‐intensive aquaculture, containing naturally occurring pond zooplankton and different feeds (marine or terrestrial feeds) until carp reached market size. We evaluated if and how total lipid contents in dorsal fillets can reflect dietary FA compositions in farm‐raised common carp and hypothesized that increasing total lipid contents in dorsal fillets significantly increase the similarity between dietary and dorsal fillets’ FA compositions. Results of this study showed that carps had higher total lipids when supplied with marine feeds and dietary FA compositions were indeed more strongly reflected in fatty (i.e. high total lipid contents) than in leaner dorsal fillets (low total lipid contents). Increasing total lipid contents in dorsal fillets significantly increased the similarity between the dietary and dorsal fillets’ FA compositions. In contrast, leaner dorsal fillets had FA patterns that were more distinct from dietary FA. Total lipid contents higher than ~60 mg/g dry weight in dorsal fillets had only limited effects on increasing the similarity between FA compositions of diets and dorsal fillets, and were independent of feed sources. It is thus suggested that higher total lipid contents in dorsal fillets can be used as a proxy to predict dietary FA profiles in common carps, or perhaps even in farm‐raised fish in general.     

Rotary actuators with multipole ring magnets

Rotary actuators are electromagnetic devices developing mechanical torque with limited rotary motion. Because of their simplicity and low cost they are finding more and more applications, especially in the automotive field. This paper describes a novel homopolar rotary actuator with a ring-type radially magnetized multipolar permanent magnet featuring a high force density “transverse flux” configuration which performs a spring action by developing electromagnetic torques with limited angular movement. Because of the magnetically complicated and nonsymmetrical rotary actuator configuration, the analysis of this actuator is based on 3-D finite element software. The analysis, which is well supported by test results, shows that symmetrical magnetic forces in both directions of rotation were achieved with a stable equilibrium position, satisfying all design requirements to enhance the basic hydraulic power steering system of passenger vehicles