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A special session on sensors in outdoor environmental monitoring and site remediation was held as part of the NIST Workshop on Gas Sensors. This manuscript summarizes the main points of the workshop. Application areas, issues of concern,... more
A special session on sensors in outdoor environmental monitoring and site remediation was held as part of the NIST Workshop on Gas Sensors. This manuscript summarizes the main points of the workshop. Application areas, issues of concern, and potentially fruitful areas for further research and development were discussed. The main conclusion of the group was that the problems and potential solutions to problems in environmental monitoring were common to other application areas of sensing as well. Of particular concern to the group were the many barriers to final development and commercialization of sensors. Barriers included lack of information on potential markets lack of support of development, (as opposed to more basic research), and difficulties in developing the final packaging for a device. The characterization and development of chemically selective materials for sensor coatings was viewed by the group as a particularly important area for future research.
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Arrays of polymer-coated surface acoustic wave (SAW) vapor sensors have shown great promise for detecting a variety of organic vapors at relevant levels. Both modeling studies and experimental studies have shown that many toxic organic... more
Arrays of polymer-coated surface acoustic wave (SAW) vapor sensors have shown great promise for detecting a variety of organic vapors at relevant levels. Both modeling studies and experimental studies have shown that many toxic organic vapors can be detected at or below permissible exposure limits. However, single sensors are not adequately selective for many applications. Sensor arrays with chemometric data processing offer a means to greatly increase the selectivity of the analytical measurement. We have recently completed the collection of a large data set where twenty diverse polymers coated on SAW devices were tested against 18 organic vapors and water. With these data in hand, it is possible to examine a variety of issues associated with the development of SAW sensor arrays and selection of polymers for the arrays.
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As part of the West Valley Demonstration Project (WVDP) the alkaline PUREX supernatant stored in Tank 8D2 will be partially decontaminated by the removal of radiocesium. Four processes for removal of radiocesium from the alkaline... more
As part of the West Valley Demonstration Project (WVDP) the alkaline PUREX supernatant stored in Tank 8D2 will be partially decontaminated by the removal of radiocesium. Four processes for removal of radiocesium from the alkaline supernatant were studied through experimentation and engineering analysis to identify a reference approach for the WVDP. These processes included the use of a zeolite inorganic ion-exchanger (Linde Ionsiv IE-95), an organic ion exchange resin (Duolite CS-100), and two precipitation processes; one using sodium tetraphenylboron (NaTPB) and the other using phosphotungstic acid (PTA). Based upon process performance, safety and environmental considerations, process and equipment complexity and impacts to the waste vitrification system, the zeolite ion-exchange process has been selected by West Valley Nuclear Services, Inc., as the reference supernatant treatment process for the WVDP. This paper will summarize the technical basis for the selection of the zeolite ion-exchange process. 4 figures, 2 tables.
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Several instrumentation concepts are being developed at the Pacific Northwest Laboratory (PNL) for process control of high-level waste glass melters. These systems include an infrared imaging system, a glass level monitor, a feed crust... more
Several instrumentation concepts are being developed at the Pacific Northwest Laboratory (PNL) for process control of high-level waste glass melters. These systems include an infrared imaging system, a glass level monitor, a feed crust stability sensor, and in-melter thermocouple arrays. These instrumentation systems provide redundant indications of the melter operating status and can detect potential process upset conditions such as glass foam and high feed rates. The systems are designed to withstand the melter operating environment of high temperatures and radiation levels, and corrosive gases and slurry. 5 references, 9 figures.
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Several extensions are made to the theory of multivariate process monitoring via Principal Components Analysis (PCA). An important robustness issue is addressed: the continued use of the PCA model after detection of a sensor failure.... more
Several extensions are made to the theory of multivariate process monitoring via Principal Components Analysis (PCA). An important robustness issue is addressed: the continued use of the PCA model after detection of a sensor failure. Without some adjustment, a single failed sensor can obscure other failures, thus rendering the monitoring method useless. It is shown here that one can calculate an estimate of the output of the failed sensor that is most consistent with the PCA model of the process. This estimate allows continued use of the model. Under some circumstances, replacing the failed output with this estimate is equivalent to rebuilding the entire PCA model. Partial Least Squares (PLS) regression can be used in a manner similar to PCA for process monitoring. It is shown that PLS is fundamentally more sensitive to sensor failures than PCA. Unlike PCA, however, the PLS monitoring scheme maps state information into the model residuals. For this reason, changes in the process sta...
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La presente invention concerne un procede de prise en compte de donnees obtenues d'un ensemble de reponses produites par un instrument multivoies, et de determination des caracteristiques d'un agent chimique dans l'echantillon... more
La presente invention concerne un procede de prise en compte de donnees obtenues d'un ensemble de reponses produites par un instrument multivoies, et de determination des caracteristiques d'un agent chimique dans l'echantillon sans devoir calibrer ou entrainer l'instrument avec des echantillons connus contenant le meme agent chimique. Les caracteristiques determinees par ce procede sont ensuite utilisees pour classifier et identifier l'agent chimique dans l'echantillon. En outre, on peut egalement utiliser ce procede pour quantifier la concentration de l'agent chimique dans l'echantillon.
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Applied Spectroscopy News is a monthly feature in the journal. It includes information from the Society for Applied Spectroscopy, news from other societies and institutions, announcements of meetings, schools, or other activities, and... more
Applied Spectroscopy News is a monthly feature in the journal. It includes information from the Society for Applied Spectroscopy, news from other societies and institutions, announcements of meetings, schools, or other activities, and reports of symposia from recent conferences. If you have news items, a meeting announcement, or a report from a symposium that would be in interest to readers of Applied Spectroscopy, contact David J. Butcher, Applied Spectroscopy News Editor, 340C Stillwell Science Building, 246 Central Drive, Western Carolina University, Cullowhee, NC 28723, Ph: (828) 227-7646, email: david.butcher@analytchem.org.
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Page 1. Partial least-squares regression with unlabeled data Paman Gujral, Barry M. Wise, Michael Amrhein, and Dominique Bonvin Laboratoire d'Automatique Ecole Polytechnique Fédérale de Lausanne ÉCOLE POLYTECHNIQUE FÉDÉRALE DE... more
Page 1. Partial least-squares regression with unlabeled data Paman Gujral, Barry M. Wise, Michael Amrhein, and Dominique Bonvin Laboratoire d'Automatique Ecole Polytechnique Fédérale de Lausanne ÉCOLE POLYTECHNIQUE FÉDÉRALE DE LAUSANNE ...
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Many chemical processes have a very large number of measured variables that are recorded frequently. Often, many of these variables are highly correlated and thus provide some redundant information concerning the state of the process and... more
Many chemical processes have a very large number of measured variables that are recorded frequently. Often, many of these variables are highly correlated and thus provide some redundant information concerning the state of the process and its sensors. When this is the case, multivariate techniques such as Principal Components Analysis and Partial Least Squares calibration can be used in conjunction with Statistical Process Control methods to identify process upsets and sensor failures. We refer to this combination of technologies as Multivariate Statistical Process Control (MSPC). Examples are shown for two types of sensor failure. The first class is where sensors develop a bias. The second class is where sensors become corrupted by noise. We show how confidence limits can be put on PCA residuals for the purpose of detecting failed sensors of both types. This method is compared to a PLS based method where individual variables are calibrated against other system variables and the pred...
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This work considers the application of several related multivariate data analysis techniques to the monitoring and modeling of dynamic processes. Included are the method of Principal Components Analysis (PCA), and the regression technique... more
This work considers the application of several related multivariate data analysis techniques to the monitoring and modeling of dynamic processes. Included are the method of Principal Components Analysis (PCA), and the regression technique Continuum Regression (CR), which encompasses Principal Components Regression (PCR), Partial Least Squares (PLS) and Multiple Linear Regression (MLR), all of which are based on eigenvector decompositions. It is shown that proper application of PCA to the measurements from multivariate processes can facilitate the detection of failed sensors and process upsets. The relationship between PCA and the state-space process model form is shown, providing a theoretical basis for the use of PCA in dynamic systems. For processes with more measurements than sta...
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Monitoring and fault detection of batch chemical processes is complicated by stretching of the time axis, resulting in batches of different length. This paper offers an approach to the unequal time axis problem using the Parallel Factor... more
Monitoring and fault detection of batch chemical processes is complicated by stretching of the time axis, resulting in batches of different length. This paper offers an approach to the unequal time axis problem using the Parallel Factor Analysis 2 (PARAFAC2) model. In part I of this series an algorithm for PARAFAC2 was developed and extended to N-way arrays. Unlike PARAFAC, the PARAFAC2 model does not assume parallel proportional profiles, but only that the matrix of profiles preserve its 'inner product structure' from sample to sample. PARAFAC2 also allows each matrix in the multi-way array to have different numbers of rows. Part II of this series demonstrated how the PARAFAC2 model could be used to model chromatographic data with retention time shifts. Fault detection, and to a lesser extent diagnosis, in a semiconductor etch process is considered in this paper. It is demonstrated that PARAFAC2 can effectively model process data with unequal dimension in one of the orders ...
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Linear algebra is the language of chemometrics. One cannot expect to truly understand most chemometric techniques without a basic understanding of linear algebra. This article reviews the basics of linear algebra and provides the reader... more
Linear algebra is the language of chemometrics. One cannot expect to truly understand most chemometric techniques without a basic understanding of linear algebra. This article reviews the basics of linear algebra and provides the reader with the foundation required for understanding most chemometrics literature. It is presented in a rather dense fashion: no proofs are given and there is little discussion of the theoretical implications of the theorems and results presented. The goal has been to condense into as few pages as possible the aspects of linear algebra used in most chemometric methods. Readers who are somewhat familiar with linear algebra may find this article to be a good quick review. Those totally unfamiliar with linear algebra should consider spending some time with a linear algebra text. In particular, those by Gilbert Strang are particularly easy to read and understand. Several of the numerical examples in this section are adapted from Strang’s Linear Algebra and Its...
State-of-the-art plasma processes are often pushed to the limits of the current technology, resulting in processes that have little or no margin for error. Increasingly, there is a need for fast, accurate, and sensitive detection and... more
State-of-the-art plasma processes are often pushed to the limits of the current technology, resulting in processes that have little or no margin for error. Increasingly, there is a need for fast, accurate, and sensitive detection and identification of equipment and process faults to maintain high process yields in manufacturing. In this work, we present an approach that simultaneously combines fault detection and classification together. Our algorithm uses linear discriminant analysis [1] methods to train for specific kinds of faults, e.g. a leaky mass flow controller. We can then monitor a small number of fault detection control charts, which are expressly set up to determine whether a specific fault has occurred or not. It can be shown that this approach provides higher sensitivity to specific kinds of faults than other multivariate approaches such as T, while detecting and classifying them simultaneously. We will review an example set of data and describe the performance of the n...
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Jeremy M. Shaver and Barry M. Wise Eigenvector Research, Inc. Orthogonal PLS, introduced originally by Trygg and Wold in 2002 [1], is a patented algorithm that has received much attention for its perceived ability to simplify model... more
Jeremy M. Shaver and Barry M. Wise Eigenvector Research, Inc. Orthogonal PLS, introduced originally by Trygg and Wold in 2002 [1], is a patented algorithm that has received much attention for its perceived ability to simplify model interpretation. Since its introduction, it has been shown by Ergon [2] and Kemsley and Tapp [3] that results identical to the original O-PLS formulation can be obtained by post-processing conventional PLS models in a nonpatented way. This demonstrated, unequivocally, that O-PLS models have predictive properties identical to their non-rotated versions. The authors did not, however, consider the interpretability of the models at length. In this poster we explore the issue of interpretability of O-PLS models by applying the method to carefully constructed simple systems and well characterized data. Abstract
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Note: PCG-VarianceReduction, PCG-BiasCorrection Reference LA-POSTER-2009-003 Record created on 2009-04-01, modified on 2017-05-10
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A novel approach for quantification of chemical vapor effluents in stack plumes using infrared hyperspectral imaging are presented and examined. The algorithms use a novel application of the extended mixture model to provide estimates of... more
A novel approach for quantification of chemical vapor effluents in stack plumes using infrared hyperspectral imaging are presented and examined. The algorithms use a novel application of the extended mixture model to provide estimates of background clutter in the on-plume pixel. These estimates are then used iteratively to improve the quantification. The final step in the algorithm employs either an extended least-squares (ELS) or generalized least-squares (GLS) procedure. It was found that the GLS weighting procedure generally performed better than ELS, but they performed similarly when the analyte spectra had relatively narrow features. The algorithms require estimates of the atmospheric radiance and transmission from the target plume to the imaging spectrometer and an estimate of the plume temperature. However, estimates of the background temperature and emissivity are not required which is a distinct advantage. The algorithm effectively provides a local estimate of the clutter, and an error analysis shows that it can provide superior quantification over approaches that model the background clutter in a more global sense. It was also found that the estimation error depended strongly on the net analyte signal for each analyte, and this quantity is scenario-specific.
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Examines four hydrogen bond acidic polymers as sorbent layers on acoustic wave devices for the detection of basic vapors. AC9810011
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In presenting this dissertation in partial fulfillment of the requirements for the Doctoral degree at the University of Washington, I agree that the Library shall make its copies freely available for inspection. I further agree that... more
In presenting this dissertation in partial fulfillment of the requirements for the Doctoral degree at the University of Washington, I agree that the Library shall make its copies freely available for inspection. I further agree that extensive copying of this dissertation is allowable only ...
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Abstract: This paper discusses the effect of using the biased regression technique ContinuumRegression for the identification of Finite Impulse Response (FIR) and Auto-RecursiveeXtensive variable (ARX) models of dynamic processes.... more
Abstract: This paper discusses the effect of using the biased regression technique ContinuumRegression for the identification of Finite Impulse Response (FIR) and Auto-RecursiveeXtensive variable (ARX) models of dynamic processes. Continuum Regression (CR)encompasses the techniques of Principal Components Regression (PCR), Partial LeastSquares (PLS) and Multiple Linear Regression (MLR). The theory behind CR is discussedand its use for the identification of single
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Disclosed is a method for taking the data generated from an array of responses from a multichannel instrument, and determining the characteristics of a chemical in the sample without the necessity of calibrating or training the instrument... more
Disclosed is a method for taking the data generated from an array of responses from a multichannel instrument, and determining the characteristics of a chemical in the sample without the necessity of calibrating or training the instrument with known samples containing the same chemical. The characteristics determined by the method are then used to classify and identify the chemical in the sample. The method can also be used to quantify the concentration of the chemical in the sample.
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West Valley Nuclear Services Company, Inc., will construct and operate facilities to vitrify two tanks of liquid radioactive waste stored at West Valley, New York. Pacific Northwest Laboratory developed the borosilicate waste glass... more
West Valley Nuclear Services Company, Inc., will construct and operate facilities to vitrify two tanks of liquid radioactive waste stored at West Valley, New York. Pacific Northwest Laboratory developed the borosilicate waste glass composition and vitrification process flowsheet. The initial flowsheet work with West Valley waste uncovered several unique processing problems, including difficulties in mixing and pumping the feed slurry, formation of a stable foam glass layer in the melter, and separation of secondary phases during melting. The large quantities of inorganic ion exchange resin used to decontaminate the supernatant phase in one of the tanks added to the complexity of this waste. Selection of the reference flowsheet and glass took more than 3 years, involving five major pilot-scale vitrification system tests and numerous laboratory- and engineering-scale experiments to achieve acceptable product and processing characteristics for this waste. Investigation of slurry proces...