Today's Measurement Research Articles

Signatures and Methods for the Automated Nondestructive Assay of ${\rm UF}_{6}$ Cylinders at Uranium Enrichment Plants

International Atomic Energy Agency (IAEA) inspectors currently perform periodic inspections at uranium enrichment plants to verify UF6 cylinder enrichment declarations. Measurements are typically performed with handheld high-resolution sensors on a sampling of cylinders taken to be representative of the facility's entire cylinder inventory. These measurements are time-consuming, expensive, and assay only a small fraction of the total cylinder volume. An automated nondestructive assay system capable of providing enrichment measurements over the full volume of the cylinder could improve upon current verification practices in terms of manpower and assay accuracy. The 185-keV emission from U-235 is utilized in today's cylinder measurements, but augmenting this “traditional” signature with more-penetrating “non-traditional” signatures could help to achieve full-volume assay in an automated system. This paper describes the study of non-traditional signatures that include neutrons produced by F-19 (α, n) reactions (spawned primarily from U-234 alpha emission) and the high-energy gamma rays (extending up to 8 MeV) induced by those neutrons when they interact in the cylinder wall and nearby materials. The potential of these non-traditional signatures and assay methods for automated cylinder verification is explored using field measurements on a small population of cylinders ranging from 2.0% to 5% in U-235 enrichment. The standard deviation of the non-traditional high-energy gamma-ray assay approach was 4.7% relative to the declared cylinder enrichments; the standard deviation of the traditional enrichment meter approach using a well-collimated high-resolution spectrometer was 4.3%. The prospect of using the non-traditional high-energy gamma-ray signature in concert with the traditional 185-keV signature to reduce the uncertainty of automated cylinder assay is discussed.

Quality engineering tools used to design & optimize a mobile measurement station [Instrumentation Notes

During the design and construction of a distributed measurement system, design engineers face many basic questions. How does one properly choose a structure and actual solutions for the key elements of the system? Which elements are important? How does one guarantee a suitable level of operating quality and reliability? A broad knowledge base and technical experience are necessary to answer these questions. The consumer's expectations for the product need to be met. The designer's subjectivity should be minimized. In this column, we discuss the use of two tools, the Quality Function Deployment (QFD) method which comes from quality engineering rules and the Analytic Hierarchy Process (AHP) which comes from operations research. Implementing QFD during the design process can focus the attention of the designer on the most important elements of reliability and work quality. The AHP method helps the engineer make complex decisions in designing today's measurement systems that have many extreme optimization problems. Using these methods should decrease the cost of manufacturing and maintenance of measuring systems. We explain these methods and then show how they work in designing a distributed system for a mobile measurement station (MMS).

An Observer for Mass-action Chemical Reaction Networks

In biological research, experimental data analysis plays an important role since it enables quantitative understanding of biochemical processes. On the other hand, today's measurement techniques, in continuous development, generally allow measuring a subset of the major system's variables. Such major issue can be tackled by relying on a system's and mathematical approach. For instance, first principles modelling of metabolic or signal transduction networks typically leads to a set of nonlinear differential equations. In this paper, we devise a nonlinear observer specifically suited for models of biochemical reaction networks. We show that the observer is locally convergent under certain observability conditions which can be inferred by elementary network analysis. The applicability and performance of the outlined observer are shown considering the state estimation problem for a benchmark biochemical reaction network.

Improving solar ultraviolet irradiance measurements by applying a temperature correction method for Teflon diffusers

To establish trends in surface ultraviolet radiation levels, accurate and stable long-term measurements are required. The accuracy level of today's measurements has become high enough to notice even smaller effects that influence instrument sensitivity. Laboratory measurements of the sensitivity of the entrance optics have shown a decrease of as much as 0.07-0.1%/deg temperature increase. Since the entrance optics can heat to greater than 45 degrees C in Dutch summers, corrections are necessary. A method is developed to estimate the entrance optics temperatures from pyranometer measurements and meteorological data. The method enables us to correct historic data records for which temperature information is not available. The temperature retrieval method has an uncertainty of less than 2.5 degrees C, resulting in a 0.3% uncertainty in the correction to be performed. The temperature correction improves the agreement between modeled and measured doses and instrument intercomparison as performed within the Quality Assurance of Spectral Ultraviolet Measurements in Europe project. The retrieval method is easily transferable to other instruments.

P-29: Lowest Cost USB Display Measurement System for Displays and Monitors

Most of PC monitors have never been tested for ergonomic parameters at the workplace because today's measurement equipment is too expensive. An easy to use and lowest cost system for PCs was developed: USB interfacing overcomes the need of batteries and PC based software guides (inexperienced) users through the tests. Contrast ratio and grey scale can be measured with and without ambient illumination. The system is also capable to perform many optical display measurements with slightly modified software.

Advances in analytical technologies for environmental protection and public safety.

Due to the increased threats of chemical and biological agents of injury by terrorist organizations, a significant effort is underway to develop tools that can be used to detect and effectively combat chemical and biochemical toxins. In addition to the right mix of policies and training of medical personnel on how to recognize symptoms of biochemical warfare agents, the major success in combating terrorism still lies in the prevention, early detection and the efficient and timely response using reliable analytical technologies and powerful therapies for minimizing the effects in the event of an attack. The public and regulatory agencies expect reliable methodologies and devices for public security. Today's systems are too bulky or slow to meet the "detect-to-warn" needs for first responders such as soldiers and medical personnel. This paper presents the challenges in monitoring technologies for warfare agents and other toxins. It provides an overview of how advances in environmental analytical methodologies could be adapted to design reliable sensors for public safety and environmental surveillance. The paths to designing sensors that meet the needs of today's measurement challenges are analyzed using examples of novel sensors, autonomous cell-based toxicity monitoring, 'Lab-on-a-Chip' devices and conventional environmental analytical techniques. Finally, in order to ensure that the public and legal authorities are provided with quality data to make informed decisions, guidelines are provided for assessing data quality and quality assurance using the United States Environmental Protection Agency (US-EPA) methodologies.

Modeling and analysis of fault tolerant multistage interconnection networks

Performance and reliability are two of the most crucial issues in today's high-performance instrumentation and measurement systems. High speed and compact density multistage interconnection networks (MINs) are widely-used subsystems in different applications. New performance models are proposed to evaluate a novel fault tolerant MIN arrangement, thereby assuring performance and reliability with high confidence level. A concurrent fault detection and recovery scheme for MINs is considered by rerouting over redundant interconnection links under stringent real-time constraints for digital instrumentation such as sensor networks. A switch architecture for concurrent testing and diagnosis is proposed. New performance models are developed and used to evaluate the compound effect of fault tolerant operation (inclusive of testing, diagnosis, and recovery) on the overall throughput and delay. Results are shown for single transient and permanent stuck-at faults on links and storage units in the switching elements. It is shown that performance degradation due to fault tolerance is graceful while performance degradation without fault recovery is unacceptable.

Targeting Chemical and Biological Warfare Agents at the Molecular Level

AbstractAfter the September 11 tragedies of 2001, scientists and law‐enforcement agencies have shown increasing concern that terrorist organizations and their “rogue” foreign government‐backers may resort to the use of chemical and/or biological agents against U.S. military or civilian targets. In addition to the right mix of policies, including security measures, intelligence gathering and training for medical personnel on how to recognize symptoms of biochemical warfare agents, the major success in combating terrorism lies in how best to respond to an attack using reliable analytical sensors. The public and regulatory agencies expect sensing methodologies and devices for homeland security to be very reliable. Quality data can only be generated by using analytical sensors that are validated and proven to be under strict design criteria, development and manufacturing controls. Electrochemical devices are ideally suited for obtaining the desired analytical information in a faster, simpler, and cheaper manner compared to traditional (lab‐based) assays and hence for meeting the requirements of decentralized biodefense applications. This articler presents a review of the major trends in monitoring technologies for chemical and biological warfare (CBW) agents. It focuses on research and development of sensors (particularly electrochemical ones), discusses how advances in molecular recognition might be used to design new multimission networked sensors (MULNETS) for homeland security. Decision flow‐charts for choosing particular analytical techniques for CBW agents are presented. Finally, the paths to designing sensors to meet the needs of today's measurement criteria are analyzed.

The Magnesium–Velocity Dispersion Relation and the Genesis of Early‐Type Galaxies

Available data on the magnesium-velocity dispersion (Mg-σ) relation for ~2000 early-type galaxies is analyzed. As noted previously, the Mg residuals from a fitted line are roughly Gaussian near the median but have an asymmetric blue tail, probably from subpopulations of relatively young stars. We define statistics for scatter and asymmetry of scatter in the Mg dimension and find impressive uniformity among data sets. We construct models of galaxy formation built to be as unbiased as possible toward the question of the importance of mergers in the formation of early-type galaxies. The observational constraints (Mg-σ width, asymmetry, and mean Mg strength, plus mean age and width of abundance distribution) are severe enough to eliminate almost all models. Eliminated are models with merger rates proportional to (1 + z)n with n > 0, models that assume early formation followed by recent drizzling of new stars, merger-only models in which the number of mergers exceeds ≈80, merger-only models with less than ≈20 mergers, and models with a cold dark matter power spectrum (at least within our approximations). The most successful models were those with merger probability constant or mildly declining with time, with the number of mergers needed to form the galaxy around 50 and gas fractions of ~0.2-0.35. These models are characterized by mean light-weighted ages of 8-9 Gyr (consistent with spectroscopic studies), an abundance distribution that does not exceed local constraints, and a look-back time behavior nearly indistinguishable from passive evolution of old stellar populations. Our simulations suggest that the evolution of median Mg index strength is not a good discriminator between mergers and passive evolution and that better discriminators such as Mg-σ scatter and asymmetry require N > 1000 sample sizes with accuracies similar to today's local measurements.

David St. Aubin (1952-2002)

Imagine the scene, Dave, strong, youthful and sharp-eyed, poised to leap off the bow of a swift-turning zodiac, hurl himself into the frigid Arctic waters, and deftly place a hoop-net over the head of a thrashing beluga whale. Each evening we would sit quietly on the cliffs, sharing the satisfaction of a good day's work .... The spectacle of the hundreds of belugas just below the bluff, rubbing in the shallows of Cunningham Inlet, made this one of Dave's favourite places. He was, after all, the one who had found out why belugas were there. ... Dave was the first to document that a whale could actually moult, in a peculiar kind of mammalian way. Dave started his research career as an assistant at the Arctic Biological Station, Fisheries and Oceans Canada, in Ste. Anne de Bellevue, Quebec, .... Dave was clear in his vision and goals. In 1973, he decided on graduate training. Riding a wave of powerful recommendations, he arrived at the University of Guelph .... Dave earned his Master's degree and Ph.D., both with honours. ... From the moment Dave arrived at the university until the day he left 21 years later, ... three of us worked together from the Arctic to the tropics, from Maritime Canada to Florida, from Holman Island to South America to Hawaii- observing, studying, documenting, learning. ... In 1993, Dave went to Mystic Marine Life Aquarium as Director of Research and Veterinary Services. While south of the Canadian border, his interests and involvement in Arctic research grew stronger than ever. ... By today's measure, 50 years is a disappointingly short life, but Dave never wasted a moment and accomplished much. ...

A discussion of potential exposure metrics for use in epidemiological studies on human exposure to radiowaves from mobile phone base stations.

There is currently a high level of concern in many countries that exposure to radiowaves from mobile phone base stations may be hazardous to health. When investigating such suggested risks, epidemiologists need to define an exposure metric that can reliably discriminate between exposed and unexposed groups of people. We conducted a feasibility study to investigate if either short-term measurements of electric field strength, calculations of electric field strength, or distance from nearby mobile phone base stations could be used to develop a metric reflecting an individual's exposure to radiowaves. With electric field strengths in the range of 0.012-0.343 V/m, radiowaves from mobile phone base stations were found to give a material contribution to total exposure; however, stronger signals were frequently measured from other sources such as broadcast radio and television transmitters. Theoretical considerations and the measurements made during this work demonstrated that studies at the population level on suggested adverse effects of radiowaves from mobile phone base stations are not feasible since no valid metric for estimating historical exposures is currently available. The pace of radio infrastructure development is also such that today's measurements are unlikely to be good proxies for either past or future exposures. The complex propagation characteristics affecting the beams from base station antennas include shielding effects and multiple reflections from house walls and other buildings. These factors, combined with the presence of other environmental sources of radiowaves, cause distance from a base station to be a poor proxy for exposure to radiowaves indoors. It may be possible to adapt computer models developed by network providers to predict network coverage for epidemiological purposes; however, this has yet to be investigated. Furthermore, there is little evidence that presently justifies epidemiological studies being restricted to adverse effects of radiowaves from mobile phone base stations while neglecting radiowaves at other frequencies produced by different transmitters.

Behavior of resistors and shunts: with today's high-precision measurement capability and a century of materials experience, what can go wrong?

The characteristics of laboratory resistors and high-precision resistors in the principal range, 1 /spl Omega/ to 10 k/spl Omega/, are reviewed. Also reviewed is the history of the shunt and of shunt construction. A method is given for improving the uncertainty of shunts by a factor of five by measuring temperature and providing the resistance-temperature characteristic. Data for high-current shunts using this method are included showing the improvement even in cases where shunt behavior is less than expected. Data are also given for the uncertainty improvement achieved with a common meter type, high-current shunt. The results of efforts to identify the cause of the behavior that went wrong in high-precision shunts are also presented.

Error compensation of coordinate measurements in computer-integrated manufacturing using neural networks

Coordinate measurements on computer numerically-controlled (CNC) machine tools and coordinate measuring machines are widely used in modern manufacturing settings. Switching probes, also called touch trigger probes, are the most widely used probe type in these dimensional measurement tasks. However, probe error exists and becomes one of the major error sources in today's coordinate measurement processes due to advances in machine accuracy and tighter part tolerances. In this paper, a three-hidden layer backpropagation neural network is designed and implemented to characterize probe pretravel pattern. The trained neural network can be used to perform on-line probe error compensation in coordinate measurements. Experimental data from a CMM are used to train the neural network and to show the prediction effectiveness of the approach.

Seismic excitation of the polar motion, 1977?1993

The mass redistribution in the earth as a result of an earthquake faulting changes the earth's inertia tensor, and hence its rotation. Using the complete formulae developed by Chao and Gross (1987) based on the normal mode theory, we calculated the earthquake-induced polar motion excitation for the largest 11,015 earthquakes that occurred during 1977.0-1993.6. The seismic excitations in this period are found to be two orders of magnitude below the detection threshold even with today's high precision earth rotation measurements. However, it was calculated that an earthquake of only one tenth the size of the great 1960 Chile event, if happened today, could be comfortably detected in polar motion observations. Furthermore, collectively these seismic excitations have a strong statistical tendency to nudge the pole towards approx. 140 deg E, away from the actually observed polar drift direction. This non-random behavior, similarly found in other earthquake-induced changes in earth rotation and low-degree gravitational field by Chao and Gross (1987), manifests some geodynamic behavior yet to be explored.

Television audience research technology, today's systems and tomorrow's challenges

Television ratings information is a key element in the consumer entertainment business environment. The technology used in today's measurement systems, as well as future requirements, are discussed. Program identification codes and consumer interface issues are highlighted.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A refined method of recovering potential coefficients from surface gravity data

A new method for computing the potential coefficients of the Earth's external gravity field is presented. The gravimetric boundary-value problem with a free boundary is reduced to the problem with a fixed known telluroid. The main idea of the derivation consists in a continuation of the quantities from the physical surface to the telluroid by means of Taylor's series expansion in such a way that the terms whose magnitudes are comparable with the accuracy of today's gravity measurements are retained. Thus not only linear, but also non-linear terms are taken into account. Explicitly, the terms up to the order of the third power of the Earth's flattening are retained. The non-linear boundary-value problem on the telluroid is solved by an iteration procedure with successive approximations. In each iteration step the solution of the non-linear problem is estimated by the solutions of two linear problems utilizing the fact that the non-linear boundary condition may be split into two parts; the linear spherical approximation of the gravity anomaly whose magnitude is significantly greater than the others and the non-linear ellipsoidal corrections. Finally, in order to solve the problem in terms of spherical harmonics, the transform method composed of the fast Fourier transform and Gauss Legendre quadrature is theoretically outlined. Immediate data processing of gravity data measured on the physical Earth's surface without any continuation of gravity measurements to a reference level surface belongs to the main advantage of the presented method. This implies that no preliminary data handling is needed and that the error data propagation is, consequently, maximally suppressed.

Tele-Processing Systems

Data transmission's impact on information processing has started a new evolution, perhaps, a revolution, and the next few years will clearly show how it will enhance the scientific operation of abusiness. Data transmission is not new; in fact, it is quite old by today's measurements. In May of 1844, the first data was transmitted over public telegraph by Samuel Morse. In June of 1876, at the Philadelphia Centennial, the first words were transmitted by public telephone. Both mediums, telegraph and telephone, transmit and receive information - data - and are commonly accepted today as a way of life. Yet the full implications of communications in information processing are just beginning to be realized.

Density estimation by dual ascent of the log-likelihood

A methodology is developed to assign, from an observed sample, a joint-probability distribution to a set of continuous variables. The algorithm proposed performs this assignment by mapping the original variables onto a jointly-Gaussian set. The map is built iteratively, ascending the log-likelihood of the observations, through a series of steps that move the marginal distributions along a random set of orthogonal directions towards normality. AMS subject classifications. 34A50, 65C30, 65L20, 60H35. 1. Introduction and setting Extracting information from is a fundamental underlying many ap- plications. Medical doctors seek to diagnose a patient's health from clinical data, blood tests and genetic information. Pharmaceutical companies analyze the results of massive in vitro tests of different compounds to select the best candidate for new drug development. Insurance companies assess, based on financial data, the probabil- ity that a number of credit-lines go into default within the same time-window. Using commercial data, market analysts attempt to quantify the effect that advertising cam- paigns have on sales. Weather forecasters extract from present and past observations the likely state of the weather in the near future. Climate scientists estimate long-time trends from observations over the years of quantities such as sea-surface temperature and the atmospheric concentration of CO2. In many of these applications, the fundamental data problem consists of es- timating, from a sample of a set of interdependent variables, their joint probability distribution. Thus, the financial analyst dealing in credit derivatives seeks the proba- bility of joint default of many debts over a specified time window; the medical doctor, the likelihood that a patient's test results are associated with a certain disease; the weather forecaster, the likelihood that the pattern of today's measurements anticipate tomorrow's rain.