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Monitoring Methods (monitoring + methods)
Selected AbstractsEnhanced process monitoring for wastewater treatment systemsENVIRONMETRICS, Issue 6 2008Chang Kyoo Yoo Abstract Wastewater treatment plants (WWTPs) remain notorious for poor data quality and sensor reliability problems due to the hostile environment, missing data problems and more. Many sensors in WWTP are prone to malfunctions in harsh environments. If a WWTP contains any redundancy between sensors, monitoring methods with sensor reconstruction such as the proposed one can yield a better monitoring efficiency than without a reconstruction scheme. An enhanced robust process monitoring method combined with a sensor reconstruction scheme to tackle the sensor failure problems is proposed for biological wastewater treatment systems. The proposed method is applied to a single reactor for high activity ammonia removal over nitrite (SHARON) process. It shows robust monitoring performance in the presence of sensor faults and produces few false alarms. Moreover, it enables us to keep the monitoring system running in the case of sensor failures. This guaranteed continuity of the monitoring scheme is a necessary development in view of real-time applications in full-scale WWTPs. Copyright © 2007 John Wiley & Sons, Ltd. [source] Use of turbidometry to characterize suspended sediment and phosphorus fluxes in the Lake Tahoe basin, California, USAHYDROLOGICAL PROCESSES, Issue 3 2007Andrew P. Stubblefield Abstract The efficacy of in-stream nephelometric turbidometry as a surrogate for total suspended solids (TSS) and total phosphorus (TP) concentrations was evaluated for use in low turbidity (<50 NTU) subalpine watersheds at Lake Tahoe, California,Nevada, USA. Continuous turbidity records for the 1999, 2000 and 2001 snowmelt seasons and data from water quality samples (1982,2000) were examined to determine watershed sediment delivery dynamics. Strong correlations were found between turbidity and both TSS and TP concentration. The strong correlation indicates that turbidity can serve as a good surrogate for direct measurement in these watersheds. The watersheds displayed clockwise hysteresis: sediment flushing and depletion, on daily, seasonal and decadal time-scales. The hysteresis curves had strong concave shapes, indicating a sensitive response to peak flow. A pronounced seasonal trend was observed for the ratio of suspended sediment concentration (SSC)/discharge over time, indicating early season flushing of available sediment. Significant linear relationships (p < 0·05) were found for 12 of 17 years. Comparison of annual sediment rating curve coefficients indicated smaller coefficients during high sediment loading years and in the years following. The smaller coefficients are evidence of sediment depletion during high flow years. The effect of hysteresis on monitoring methods was illustrated by comparing turbidity estimates of TSS load with sediment rating curve estimates of SSC. After accounting for differences in SSC/TSS methods of analysis, daily loads calculated with turbidity methods were 58,98% of rating curve estimates for the spring snowmelt seasons of 1999,2001. Copyright © 2006 John Wiley & Sons, Ltd. [source] Investigations into Salmonella contamination in poultry feedmills in the United KingdomJOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2010R.H. Davies Abstract Aims:, To investigate and compare commercial and farm-level milling operations in respect of the monitoring and control of Salmonella contamination. Methods and Results:, Four commercial feedmills and four on-farm poultry feed mixers were intensively sampled. Samples included dust and spillages and were cultured for Salmonella. Serovars in ingredients on farms were associated with wildlife and/or livestock, whereas those in commercial mill ingredients were associated with domestically produced cereals and imported vegetable protein. Endemic contamination of two commercial feedmills was reflected in isolates obtained from finished products and destination flocks. Renovation of equipment and chemical treatment of equipment and feed had not removed endemic strains, and previous routine monitoring in the commercial mills had not revealed the degree of contamination found in the present investigations. Conclusions:, Ingredient contamination was diverse and reflected the sources and storage environments used by mills and farms, respectively. The use of dust and spillage samples showed a clear sensitivity advantage over the previously used monitoring methods in the feedmills. Significance and Impact of the Study:, Monitoring for Salmonella contamination of commercial feedmills requires sensitive methods, such as those employed in this study. This is particularly important for endemic contamination. [source] Process monitoring for continuous process with periodic characteristicsJOURNAL OF CHEMOMETRICS, Issue 2 2004Yangdong Pan Abstract Application of conventional statistical monitoring methods to periodic processes can result in frequent false alarms and/or missed faults due to the non-stationary behavior seen over a period. To address this problem, we propose to identify and use a stochastic state space model that describes the statistical behavior of changes occurring from period to period. This model, when retooled as a periodically time-varying model, can be used for on-line monitoring and estimation with the aid of a Kalman filter. The same model can also be used for inferential estimation of the variables that are difficult or slow to measure on-line. The proposed approach is applied to a simulation benchmark of a waste water treatment process, which exhibits strong diurnal changes in the feed stream, and is compared against the principal component analysis (PCA) and partial least squares (PLS) methods. Copyright © 2004 John Wiley & Sons, Ltd. [source] Factors affecting black rhino monitoring in Masai Mara National Reserve, KenyaAFRICAN JOURNAL OF ECOLOGY, Issue 1 2002Matthew J. Walpole Abstract The black rhino in Africa is slowly recovering from poaching. This has been achieved in part by maintaining ongoing monitoring as part of intensive protection and biological management. However, the efficacy of population monitoring methods has not been assessed. Rhino surveillance records and rainfall data were used to determine which ecological and operational factors affected monthly rhino sightings by vehicle patrols in Masai Mara, Kenya. Comparisons of sightings capture rates using different ground-based and aerial methods were also conducted. Stepwise multiple regression revealed a model (adjusted R2 = 0.66) predicting monthly rhino sightings with four significant factors; number of patrols, rhino population size, rainfall over the previous 2 months and a dummy variable for the month of August. The latter two variables represent the negative effects of long grass growth and the annual wildebeest migration on rhino sightings, and result in seasonal deficiencies in monitoring. During vehicle patrols, 51% of sightings were made whilst moving, and 49% were made whilst stationary and scanning with binoculars, although sightings capture rate was an order of magnitude higher when stationary. Equally, sightings capture rate from hot air balloons was twice that during vehicle-based patrols, although with less accuracy of identification. The introduction of foot patrols would increase patrol cost-effectiveness and fill seasonal troughs, thereby providing better all-round surveillance. Résumé Le rhino noir d'Afrique récupère peu à peu des méfaits du braconnage. Ceci est le résultat, en partie, de la poursuite des contrôles constants visant une protection intensive et une gestion biologique. Pourtant, on n'a pas évalué l'efficacité des méthodes de surveillance de la population. On a utilisé les rapports de surveillance des rhinos et les données sur les chutes de pluie pour déterminer quels facteurs écologiques et opérationnels influençaient le nombre de fois que les véhicules des patrouilles apercevaient des rhinos chaque mois dans le Masai Mara, au Kenya. On a aussi fait des comparaisons des taux de captures visuelles selon différentes méthodes, au sol et aériennes. La méthode de régression multiple a fait apparaître un modèle (R2 ajusté= 0,66) pour prédire les observations mensuelles de rhinos avec quatre facteurs significatifs; le nombre de patrouilles, la taille de la population de rhinos, les chutes de pluie au cours des deux mois précédents et une variable factice pour le mois d'août. Les deux dernières variables représentent les effets négatifs de la croissance de longues herbes et de la migration annuelle des gnous sur l'observation des rhinos et leurs résultats sur les faiblesses saisonnières des contrôles. Pendant les patrouilles motorisées, 51% des observations se sont faites en mouvement et 41% à l'arrêt, en observant aux jumelles, mais le taux de captures visuelles était un ordre de grandeur supérieur à l'arrêt. De même, le taux de captures visuelles obtenu à partir d'une mongolfière était le double de celui obtenu lors des patrouilles motorisées, mais la précision des identifications était plus faible. L'introduction de patrouilles à pied augmenterait la rentabilité des patrouilles et permettrait de combler les lacunes saisonnières et d'assurer une meilleure continuité de la surveillance. [source] Experimental investigation of the hydrodynamics in a liquid,solid riserAICHE JOURNAL, Issue 3 2005Shantanu Roy Abstract Liquid,solid fluid dynamics has been investigated in a 6-in. (0.15 m) "cold-flow" circulating fluidized bed riser using non-invasive flow monitoring methods. Gamma-ray computed tomography (CT) was used to measure the time-averaged cross-sectional solids volume fraction distributions at several elevations. The time-averaged mean and "fluctuating" solids velocity fields were quantified using the computer-automated radioactive particle tracking (CARPT) technique. The experimental equipment, protocol of implementation, and data analysis have been discussed briefly, with particular emphasis on the specific features in the use of these techniques for studying high-density turbulent flows as in a liquid,solid riser. The experimental study examines nine operating conditions, that is, three liquid superficial velocities and three solids flow rates. The solids holdup profile is found to be relatively uniform across the cross section of the riser, with marginal segregation near the walls. The time-averaged solids velocity profiles are found to have a negative component at the walls, indicating significant solids backmixing. Detailed characterization of the solids velocity fields in terms of RMS velocities, kinetic energies, Hurst exponents, residence time distributions, trajectory length distributions, dispersion coefficients, and so forth are presented. Comparative and symbiotic analyses of the results were used to develop a coherent picture of the solids flow field. In addition, the work also serves to demonstrate the power and versatility of these flow-imaging techniques in studying highly turbulent and opaque multiphase systems. © 2005 American Institute of Chemical Engineers AIChE J, 51: 802,835, 2005 [source] Monitoring of batch processes through state-space modelsAICHE JOURNAL, Issue 6 2004Jay H. Lee Abstract The development of a state-space framework for monitoring batch processes that can complement the existing multivariate monitoring methods is presented. A subspace identification method will be used to extract the dynamic and batch-to-batch trends of the process and quality variables from historical operation data in the form of a "lifted" state-space stochastic model. A simple monitoring procedure can be formed around the state and residuals of the model using appropriate scalar statistical metrics. The proposed state-space monitoring framework complements the existing multivariate methods like the multi-way PCA method, in that it allows us to build a more complete statistical representation of batch operations and use it with incoming measurements for early detection of not only large, abrupt changes but also subtle changes. In particular, it is shown to be effective for detecting changes in the batch-to-batch correlation structure, slow drifts, and mean shifts. Such information can be useful in adapting the prediction model for batch-to-batch control. The framework allows for the use of on-line process measurements and/or off-line quality measurements. When both types of measurements are used in model building, one can also use the model to predict the quality variables based on incoming on-line measurements and quality measurements of previous batches. © 2004 American Institute of Chemical Engineers AIChE J, 50: 1198,1210, 2004 [source] Resistance monitoring of aluminum plates to microbiologically influenced corrosion using FFT impedance spectroscopy methodsMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 7 2006P. Norouzi Abstract It is well know that formation of a passive oxide film on aluminum can enhance its corrosion resistance. However, microbiologically species are able to damage this film. Microbial adhesion is widely accepted as important stage prior to the induction or initiation of biocorrosion. Pseudomonas aeruginosa and Cladosprioum sp. have been commonly associated with the microbiologically influenced corrosion (MIC) of aluminum and its alloys. In this study, the effect of an organic dye (Quinizarin), on the resistance of aluminum plates to MIC has been investigated by some corrosion monitoring methods such as FFT impedance spectroscopy, cyclic voltammetry and SEM (scanning electron microscopy). In this work, the surface of aluminum plates were changed after exposing them (five types: only polished, anodized, anodized and colored, anodized and colored and sealed) to Pseudomonas aeuroginosa in ASW (artificial sea water) as a microbial culture. The results showed that, the mentioned color caused a decrease in the growth of bacteria, because the color acts a protected layer on the surface of aluminum. This characteristic can reduce intensity of biocorrosion on aluminum plates, so the anodized and colored and sealed plates have the most resistance to MIC, and it can be shown and proven by these techniques which are mentioned above. [source] Supermarket Sales Data: Feasibility and Applicability in Population Food and Nutrition MonitoringNUTRITION REVIEWS, Issue 1 2007Sandar Tin Tin MBBS Population food and nutrition monitoring plays a critical role in understanding suboptimal nutrition at the population level, yet current monitoring methods such as national surveys are not practical to undertake on a continuous basis. Supermarket sales data potentially address this gap by providing detailed, timely, and inexpensive monitoring data for informing policies and anticipating trends. This paper reviews 22 studies that used supermarket sales data to examine food purchasing patterns. Despite some methodological limitations, feasibility studies showed promising results. The potential and limitations of using supermarket sales data to supplement food and nutrition monitoring methods are discussed [source] A study of time-between-events control chart for the monitoring of regularly maintained systemsQUALITY AND RELIABILITY ENGINEERING INTERNATIONAL, Issue 7 2009Michael B. C. Khoo Abstract Owing to usage, environment and aging, the condition of a system deteriorates over time. Regular maintenance is often conducted to restore its condition and to prevent failures from occurring. In this kind of a situation, the process is considered to be stable, thus statistical process control charts can be used to monitor the process. The monitoring can help in making a decision on whether further maintenance is worthwhile or whether the system has deteriorated to a state where regular maintenance is no longer effective. When modeling a deteriorating system, lifetime distributions with increasing failure rate are more appropriate. However, for a regularly maintained system, the failure time distribution can be approximated by the exponential distribution with an average failure rate that depends on the maintenance interval. In this paper, we adopt a modification for a time-between-events control chart, i.e. the exponential chart for monitoring the failure process of a maintained Weibull distributed system. We study the effect of changes on the scale parameter of the Weibull distribution while the shape parameter remains at the same level on the sensitivity of the exponential chart. This paper illustrates an approach of integrating maintenance decision with statistical process monitoring methods. Copyright © 2008 John Wiley & Sons, Ltd. [source] A one-sided MEWMA chart for health surveillanceQUALITY AND RELIABILITY ENGINEERING INTERNATIONAL, Issue 5 2008Michael D. Joner Jr Abstract It is often important to rapidly detect an increase in the incidence rate of a given disease or other medical condition. It has been shown that when disease counts are sequentially available from a single region, a univariate control chart designed to detect rate increases, such as a one-sided cumulative sum chart, is very effective. When disease counts are available from several regions at corresponding times, the most efficient monitoring method is not readily apparent. Multivariate monitoring methods have been suggested for dealing with this detection problem. Some of these approaches have shortcomings that have been recently demonstrated in the quality control literature. We discuss these limitations and suggest an alternative multivariate exponentially weighted moving average chart. We compare the average run-length performance of this chart with that of competing methods. We also evaluate the statistical performance of these charts when the actual increase in the disease count rate is different from the one that the chart was optimized to detect quickly. Copyright © 2008 John Wiley & Sons, Ltd. [source] Monitoring population productivity in the saiga antelopeANIMAL CONSERVATION, Issue 4 2009A. Kühl Abstract Effective conservation requires a good understanding of factors causing variation in population growth rate. We here analyse the relationship between female age and fecundity in the saiga antelope Saiga tatarica tatarica, a critically endangered ungulate of the Eurasian steppes and semideserts, at both individual and population levels. Annual variation in age structure and twinning rates was investigated using long-term datasets, sampling a total of 3308 females in four populations over more than 40 years. Further, a new non-invasive method is presented, estimating twinning rates from both calves and placentas encountered during calving aggregation transects. At an individual level, the most parsimonious model for twinning rates included three age classes (1, 2 and ,3 years); however, the model with only two classes (1 and ,2 years) was competitive and particularly useful for monitoring because these two age classes can reliably be determined by direct observation in the field. Among yearlings, 77.4% were fecund and 11.7% twinned, whereas among older females 94.6% were fecund and 72.6% twinned. At a population level, annual variation in age structure (proportion ,2 years) correlated well with annual variation in twinning rate except in the north-west Pre-Caspian population. Our results suggest that the recent poaching-driven collapse in saiga numbers has potentially resulted in reductions in fecundity, which will have an impact on population growth rate. Our results highlight the potential for monitoring of twinning rate using non-invasive calving aggregation transects as a cost-effective additional tool to population counts for monitoring the status of this critically endangered species. These monitoring methods are also potentially transferable to other ungulate species. [source] Ostracoda (Crustacea) from the Turkish Ramsar site of Lake Ku, (Manyas Gölü)AQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 3 2001Selçuk Alt, nsaçl Abstract 1.,Lake Ku, (Manyas Gölü), an important bird conservation area, was sampled in the summer, autumn, winter and spring of 1997, and the seasonal and spatial distributions of ostracods were investigated. Many of the taxa collected are useful indicator species for monitoring conditions within lake basins. 2.,The findings suggest that the L. Ku, ecosystem is already substantially degraded. Pollution, coupled with extensive water abstraction for irrigation, have damaged the value of the lake, both commercially (as an inland waters fishery), and as an important site for wetland bird conservation. 3.,This work shows that ostracod faunal analysis has value in the study of such sites, particularly where more formal physical, chemical and biological monitoring methods are inappropriate or unavailable. Copyright © 2001 John Wiley & Sons, Ltd. [source] Statistical Issues Arising in the Women's Health InitiativeBIOMETRICS, Issue 4 2005Ross L. Prentice Summary A brief overview of the design of the Women's Health Initiative (WHI) clinical trial and observational study is provided along with a summary of results from the postmenopausal hormone therapy clinical trial components. Since its inception in 1992, the WHI has encountered a number of statistical issues where further methodology developments are needed. These include measurement error modeling and analysis procedures for dietary and physical activity assessment; clinical trial monitoring methods when treatments may affect multiple clinical outcomes, either beneficially or adversely; study design and analysis procedures for high-dimensional genomic and proteomic data; and failure time data analysis procedures when treatment group hazard ratios are time dependent. This final topic seems important in resolving the discrepancy between WHI clinical trial and observational study results on postmenopausal hormone therapy and cardiovascular disease. [source] Assessment of physiological conditions in E. coli fermentations by epifluorescent microscopy and image analysisBIOTECHNOLOGY PROGRESS, Issue 3 2009Sónia Carneiro Abstract The development of monitoring methods for assessing the physiological state of microorganisms during recombinant fermentation processes has been encouraged by the need to evaluate the influence of processing conditions in recombinant protein production. In this work, a technique based on microscopy and image analysis was developed that allows the simultaneous quantification of parameters associated with viability and fluorescent protein production in recombinant Escherichia coli fermentations. Images obtained from light microscopy with phase contrast are used to assess the total number of cells in a given sample and, from epifluorescence microscopy, both protein producing and injured cells are evaluated using two different fluorochromes: propidium iodide and enhanced yellow fluorescent protein. This technique revealed the existence of different cell populations in the recombinant E. coli fermentation broth that were evaluated along four batch fermentations, complementing information obtained with standard techniques to study the effects of the temperature and induction time in recombinant protein production processes. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source] | |||||||||||||||||||