Single-pulse measurement of wind velocities using an Er:Yb:glass coherent laser radar

Many wind-field mapping applications require range-resolved atmospheric velocity measurements at long range and/or with a temporal resolution sufficient to investigate turbulence. We argue that this capability can be achieved only by coherent laser radar systems that transmit energetic (>1 mJ) pulses. We describe such a system and describe single-pulse measurement of the range-resolved line-of-sight velocities, and show that the instrument-limited reproducibility of the measurements is 0.4 ms(-1).     

Characterization of Model Uncertainty in the Static Pile Design Formula

Level 1 reliability methods have been internationally accepted as the basis for development of the new generation of geotechnical design codes. A key requirement of this design approach is the identification and quantification of uncertainties associated with the geotechnical design under consideration. This paper presents four load test databases from South Africa for driven piles in noncohesive soils (29 tests), bored piles in noncohesive soils (33 tests), driven piles in cohesive soils (59 tests), and bored piles in cohesive soils (53 tests). The capacity model factor is defined as the ratio of the interpreted capacity (Chin-Davisson approach) and the predicted capacity (static pile design formula). The uncertainty in the capacity model factor is modeled as a lognormal random variable. The model factor statistics reported in this study are required for reliability-based ultimate limit state design. The uncertainty in the load-settlement behavior is characterized by fitting measured load-settlement data to a hyperbolic equation and then normalizing the hyperbolic curve with the interpreted capacity. The resulting exercise reduces uncertainties in a set of nonlinear continuous curves to uncertainties in two hyperbolic curve-fitting parameters. This approach is practical and grounded realistically on the load test database with minimal assumptions. The hyperbolic parameter statistics reported in this study are required for reliability-based serviceability limit state design.     

Model-based scale-up of vacuum contact drying of pharmaceutical compounds

An integrated methodology for the scale-up of vacuum contact drying with intermittent agitation is described in this work. The methodology combines a mathematical model of vacuum contact drying, based on differential transient heat and energy balances, and a small-scale experimental apparatus for model validation and parameter estimation. The validated model was used for the estimation of drying times of six different pharmaceutical compounds at the pilot and manufacturing scale over a range of drying conditions – pressure 15–200 mbar, temperature 45–70 °C, solvents: acetone, water, methanol, n-propanol, and isopropyl acetate. The mean difference between predicted and actual drying times for the six compounds was less than 9%, which is considered a significant improvement over current semi-empirical approaches to vacuum contact drying scale-up.     

An Energy-Based Approach for Contact Force Computation

A new approach for computing resting contact forces between solids is presented, which handles both static and sliding friction, while avoiding the problems arising from previous approaches. Each iteration provides values for all unknowns and needs a constant computation time. The first iteration is a global dynamic solution involving inertia and external forces. The subsequent iterations consist of global redistributions of energy through the solids in order to restrict the values within correct bounds, leading to a progressive refinement of the solution. This allows the termination of the computation when a user-defined level of precision is reached. Convergence is proven in the frictionless case. The method is concise and is easily usable in a motion control system. It was implemented and tested on some examples involving simultaneously static and sliding friction along with motion control.     

Low-swing current mode logic (LSCML): A new logic style for secure and robust smart cards against power analysis attacks

A new logic style called low-swing current mode logic (LSCML) is presented. It features a dynamic and differential structure and a low-swing current mode operation. The LSCML logic style may be used for hardware implementation of secure smart cards against differential power analysis (DPA) attacks but also for implementation of self-timed circuits thanks to its self-timed operation. Electrical simulations of the Khazad S-box have been carried out in 0.13 μm PD (partially depleted) SOI CMOS technology. For comparison purpose, the Khazad S-box was implemented with the LSCML logic and two other dynamic differential logic styles previously reported. Simulation results have shown an improved reduction of the data-dependent power signature when using LSCML circuits. Indeed the LSCML based Khazad S-box has shown a power consumption standard deviation more than two times smaller than the one in DyCML and almost two times smaller than the one in DDCVSL.     

Acetylcholinesterase engineering for detection of insecticide residues

To detect traces of insecticides in the environment using biosensors,we engineered Drosophila acetylcholinesterase (AChE) to increaseits sensitivity and its rate of phosphorylation or carbamoylationby organophosphates or carbamates. The mutants made by site-directedmutagenesis were expressed in baculovirus. Different strategieswere used to obtain these mutants: (i) substitution of aminoacids at positions found mutated in AChE from insects resistantto insecticide, (ii) mutations of amino acids at positions suggestedby 3-D structural analysis of the active site, (iii) Ala-scananalysis of amino acids lining the active site gorge, (iv) mutagenesisat positions detected as important for sensitivity in the Ala-scananalysis and (v) combination of mutations which independentlyenhance sensitivity. The results highlighted the difficultyof predicting the effect of mutations; this may be due to thestructure of the site, a deep gorge with the active serine atthe bottom and to allosteric effects between the top and thebottom of the gorge. Nevertheless, the use of these differentstrategies allowed us to obtain sensitive enzymes. The greatestimprovement was for the sensitivity to dichlorvos for whicha mutant was 300-fold more sensitive than the Drosophila wild-typeenzyme and 288 000-fold more sensitive than the electric eelenzyme, the enzyme commonly used to detect organophosphate andcarbamate.     

Transformation of arachidonic acid into monohydroxy-eicosatetraenoic acids by mouse peritoneal macrophages

Mouse peritoneal macrophages synthesize 6 monohydroxylated eicosatetraenoic acids when incubated with exogenous arachidonic acid. These compounds were identified by chromatographic techniques (high pressure liquid chromatography and high efficiency glass capillary column gas chromatography and mass spectrometry. The chromatographic and spectrometric data are presented. These results show that peritoneal macrophages constitute one of the best systems to study in evaluating the metabolism of oxygenated products of arachidonic acid. Presented in part at the 22nd International Conference on the Biochemistry of Lipids, Milan, May 26–28, 1980.     

Fiber-Matrix Bond-Strength Characterization of Silicon Carbide-Silicon Carbide Materials

The fiber-matrix interface bond strength of a ceramicmatrix composite is quantitatively evaluated using an indentation technique at room temperature and after creep tests under vacuum. The observed decrease in frictional stress with increasing temperature is discussed in connection with such other data as rupture stress, importance of pullout, and geometric characteristics of the fibers.