Self-Tuning Microprocessor Universal Controller

Recent advances in microprocessor technology make it possible to implement on-line modern control algorithms at reasonable cost. Self-tuning regulators can, in general, be used to regulate any industrial process and this paper describes one such implementation on a microprocessor in three different software formats, i. e., 8-bits, 32-bit floating-point, and a modified version of the 32-bit floating-point. Studies of the process control specifications and the corresponding modifications required are described.     

The adsorption of water vapour on a microporous carbon black

The adsorption of water vapour on a microporous carbon black has been studied by measurement at 25° C of (a) the adsorption isotherm, (b) the heat of immersion in water of samples charged with different amounts of water vapour. The two sets of measurements were carried out on the carbon black both before and after the micropores had been filled with n-nonane vapour. It was thus possible, in effect, to isolate the adsorptive behaviour of the micropores. As expected, the heat of adsorption in the micropores was greater than on an open surface, but the isotherm of adsorption in the micropores remained convex to the pressure axis in the low pressure region; the carbon black remained “hydrophobic” despite the enhancement of the adsorption field within the micropores.     

A study of strengthening mechanisms in tempered martensite from a medium carbon steel

Previous studies of strengthening mechanisms in quenched and tempered steels have been based almost entirely on microscopy. The density and distribution of residual dislocations in these materials have generally been poorly characterized and there is doubt as to the contribution of substructure to strength. In the present work, a 0.42 pct C steel has been hardened and tempered for 1 hr at seven temperatures in the range 250° to 550°C. The structures have been studied by X-ray diffraction line profile analysis as well as by electron microscopy. The measured 0.2 pct offset yield strength, over the whole tempering temperature range, could be represented by $$\sigma _{0.2{\text{ = }}} \sigma _0 {\text{ + }}\frac{{k_{\text{1}} }}{D}{\text{ ln }}\frac{D}{{2b}}{\text{ + }}k_{\text{2}} {\text{ }}\rho ^{1/2} $$ whereD is the mean planar spacing of carbide particles,ρ is the density of residual dislocations in the as-tempered structure, and b is the Burger’s vector of a dislocation in iron. The stress ct0 was found to be about 35 kgm mm^-2 for the steel used and probably includes an appreciable contribution from incremental interstitial solid solution strengthening. The constantsk ₁ andk ₂ have values which are consistent with both theory and previous experimental work with the Orowan mechanism and strain-hardening, respectively. The dislocation substructure contribution accounted for more than 35 pct of the yield strength of the steel tempered at temperatures up to 400°C.     

Comparison of the hydrophobic grid-membrane filter DNA probe method and the Health Protection Branch standard method for the detection of Listeria monocytogenes in foods

The standard Health Protection Branch (HPB) method for the detection of L. monocytogenes in foods involves lengthy enrichment, selection and biochemical testing, requiring up to 8 days to complete. A hydrophobic grid-membrane filter (HGMF) method employing a digoxigenin-labelled listeriolysin O probe required 5 days to complete, and included an image-analysis system for electronic data acquisition. A total of 200 food samples encompassing 8 high-risk food groups (soft and semi-soft cheeses, packaged raw vegetables, frozen cooked shrimp, ground poultry, ground pork, ground beef, jellied meats, and pâté) were screened for the presence of L. monocytogenes by the two methods. Overall, 32 (16%) and 30 (15%) of the naturally-contaminated food samples tested positive for L. monocytogenes by the HPB and DNA methods, respectively. The DNA probe method was highly specific in discriminating L. monocytogenes from other Listeria spp. present in 50 of the samples tested. Results showed 94% sensitivity and 100% specificity between the two methods. The HGMF DNA probe method is an efficient and reliable alternative to the HPB standard method for detecting L. monocytogenes in foods.     

Tests with a microcomputer based adaptive synchronous machinestabilizer on a 400 MW thermal unit

Field tests have been conducted on a microcomputer-based self-tuning adaptive synchronous machine stabilizer. The adaptive control algorithm tracks the system operating conditions using a least squares identification technique with variable forgetting factor and the control is calculated by a self-searching pole-shift method. An outline of the control algorithm and the results of field tests on a 400 MW thermal generating unit are described     

Twist Based Acquisition and Tracking of Animal and Human Kinematics

This paper demonstrates a new visual motion estimation technique that is able to recover high degree-of-freedom articulated human body configurations in complex video sequences. We introduce the use and integration of a mathematical technique, the product of exponential maps and twist motions, into a differential motion estimation. This results in solving simple linear systems, and enables us to recover robustly the kinematic degrees-of-freedom in noise and complex self occluded configurations. A new factorization technique lets us also recover the kinematic chain model itself. We are able to track several human walk cycles, several wallaby hop cycles, and two walk cycels of the famous movements of Eadweard Muybridge's motion studies from the last century. To the best of our knowledge, this is the first computer vision based system that is able to process such challenging footage.     

An analog of the normal current density effect in barrier discharge

We have experimentally studied the regimes of homogeneous barrier discharge operation in air at reduced pressure and observed behavior analogous to the normal current density effect in a dc discharge.     

Wide temperature (-20°C-95°C) operation of an uncooled2.5-Gb/s 1300-nm DFB laser

This letter describes a 2.5-Gb/s 1300-nm distributed feedback laser that can operate in a wide temperature range of -20°C to 95°C. We present RF and DC characteristics of the device and the statistical distribution of threshold current and slope efficiency at high temperature. Finally, we demonstrate the device performance in a 2.5-Gb/s small-form-factor module up to 85°C