Continuous Measurement Systems Research Articles

Water vapor stable isotope memory effects of common tubing materials

Abstract. Water molecules in vapor can exchange with gaseous water molecules sticking to surfaces of sampling tubing, and exchange rates are unique for each water isotopologue and tubing material. Therefore, water molecules on tubing walls take some time to reach isotopic equilibrium with a new vapor isotopic signal. This creates a memory effect that is observed as attenuation time for signal propagation in continuous stable water vapor isotope measurement systems. Tubing memory effects in δD and δ18O measurements can limit the ability to observe fast changes, and because δD and δ18O memory are not identical, this introduces transient deuterium excess (D-excess, defined as δD-8×δ18O) artifacts in time-varying observations. To our knowledge, a comprehensive performance comparison of commonly used tubing material water exchange properties in laser-based measurement systems has not been published. We compared how a large isotopic step change propagated through five commonly used tubing materials for water isotopic studies – perfluoroalkoxy (PFA), fluorinated ethylene propylene (FEP), polytetrafluoroethylene (PTFE), high-density polyethylene (HDPE), and copper – at two different temperatures and an airflow rate of 0.635 L min−1 through approximately 100 ft (30.5 m) of 1/4 in. (6.4 mm) outer diameter (o.d.) tubing. All commonly used tubing materials performed similarly to each other in terms of attenuation times, reaching δ18O-location-adjusted δD and δ18O 95 % completion in less than 45 s, with slight variations based on temperature. PFA does appear to perform slightly better than the other materials, although memory metric differences are small. A tubing material commonly used in the early 2000s but reported to have memory effects on δD, Dekabon, was also tested at ambient temperature and changing humidities. The Dekabon isotopic equilibrium was not reached until nearly an hour after source transition, much later than H2O mixing ratios equilibrated. Bev-A-Line XX (used in some soil O2 and CO2 gas studies) was also tested at ambient temperature, but it did not approach isotopic equilibrium until after nearly 6 h of testing. Therefore, we cannot recommend the use of Bev-A-Line XX or Dekabon in water vapor isotope applications. Source transition from heavy to light or from light to heavy affected isotopic transition speed only in experiments where H2O ppmv was changing. While a shorter tubing lengths and smaller inner diameters shorten the delay of signal propagation through the tubing, they did not greatly change the attenuation curves under these conditions for the current commonly used tubing materials tested. However, in Dekabon, attenuation curves were greatly extended with increased tubing length. Our results show that the commonly used plastic tubing materials tested were not inferior to copper in terms of isotopic memory under these conditions, and they are easier to work with and are less expensive than copper.

Laboratuvar Teknolojisi Programı Öğrencilerinin Teknik Gezi ile Çevre Analizleri Hakkında Farkındalıklarının Arttırılmasına Yönelik Çalışmanın Değerlendirilmesi

A technical trip was planned within the course of environmental analysis in the second-class curriculum and sampling methods in the first class curriculum of the Laboratory Technology Program. In this study, it was aimed to determine the effect of technical trip about awareness of our students about the parameters analysed in the environment. Students attended this technical trip stated in the survey conducted after the trip that their awareness increased about environmental analyses. They are continuous emission measurement systems, outdoor air quality measurements, air quality modelling, water analysis, water analysis modelling, occupational health and safety in field studies, occupational hygiene in field studies, environmental noise level examinations, the relationship of soil analysis with production and health and leaf analysis. The questionnaire was evaluated using the SPSS program and Cronbach Alpha reliability coefficient was calculated as 0.927.

Continuous glucose monitoring Respective roles of healthcare professionals and quick interpretation guide

The use of continuous interstitial glucose measurement systems (CGM) has revolutionized the management of patients with diabetes for 15 years. This is true both for professional use (diagnostic CGM) and personal use for patients (therapeutic CGM). The role of health professionals - general practitioners, diabetologists, nurses, dieticians - is important to coordinate, with a specific role for each. The clinical situations are all different and the systematic analysis of the data has ideally to be carried out with the participation of the patient. These devices allow significant improvements in glycemic control, making this technology one of the most important advances in diabetes for many years.

Telemedizin in der Kinderdiabetologie

Der aktuelle Stand telemedizinischer Anwendungen und deren zu erwartendes Potenzial werden aus der Perspektive der pädiatrischen Diabetologie beleuchtet. Kontinuierliche Glukosemesssysteme (CGM [„continuous glucose measurement“]) und Insulinpumpen lassen sich zunehmend auch über interoperable oder herstellerbasierte Datenplattformen auslesen und teilen und ermöglichen es den Diabetesteams, eine Beratung auf Basis dieser Daten auch ohne physischen Kontakt in die kontinuierliche Versorgung einzubauen. Videosprechstunden können dabei zunächst ein ergänzendes Angebot darstellen, unterliegen oft längeren Implementierungsprozessen und sind u. a. abhängig von datenschutzkonformer Videochatsoftware, koordinierten Arbeitsabläufen sowie technischem Support. Telemedizin kann derzeit schon bestehende Beratungsstrukturen in Kliniken und Praxen ergänzen und helfen, das Potenzial digital dokumentierter Daten aus CGM- und automatisierten Insulinabgabesystemen voll auszuschöpfen, wobei telemedizinische Anwendungen bisher kein direktes Einsparungspotenzial bezüglich Zeit und Aufwand des medizinischen Personals und damit der Personalkosten bieten.

It-monitoring kvaliteta otpadne vode u realnom vremenu u prevenciji pandemije COVID-19

New measures are being taken in the EU member states for flexible and scalable solutions in monitoring wastewater quality. The latest scientific studies have further confirmed the presence of SARS-CoV2 virus in wastewater. This virus was also detected in stool samples of patients with COVID-19 symptoms, but also in asymptomatic cases of the disease, which confirms the possibility of faecal-oral transmission. The aim of this paper is to introduce automated real-time online monitoring in the wastewater treatment plant "Ekogramont" with the possibility of using this monitoring in the prevention of the COVID-19 pandemic. The plant is located at 1080 m above sea level and was built in the period from 1998 to 1999 for the needs of the company for bottling spring water "Vlasinska ROSA", which is now owned by the company "Coca Cola" HBC. The proposed SCADA system collects the data from the sensors located in the sewage water and delivers the obtained results to the computers in the central station. The suitability of such automated monitoring comes to the fore in extreme weather conditions which prevail in this high mountain area, when for the purposes of standard analysis, wastewater sampling is disabled. The system also contains the so-called "contamination" alarm which is activated by every parameter which exceeds the set critical limit. The standard RT-PCR protocols WHO and FDA are used to detect SARS-CoV2. The detection of the viral genome in sewage, prior to the exponential phase of the epidemic, is a valuable indicator of the imminent danger of an outbreak. In this filed, modification of legal regulations in Serbia would enable the formation of a network for automated real-time monitoring of water quality control, with continuous measurement systems that would deliver the measurement results via SCADA systems to the competent institutions.

Smart Assembly of Sulfide Heterojunction Photocatalysts with Well-Defined Interfaces for Direct Z-Scheme Water Splitting under Visible Light.

A Z-scheme photocatalytic water-splitting system is an effective approach to integrate the advantages both hydrogen- and oxygen-evolution photocatalysts. The interfacial properties of the heterojunctions have a great influence on the efficiency through the crystal orientation and the charge kinetics. In this study, a general chemical vapor deposition process and a gentle cation-exchange method were combined to assemble Z-scheme photocatalysts between CdS and MnS. As a result of the well-defined heterojunction interfaces and distinctive structural benefits, without cocatalysts, the 1 D CdS/MnS hybrid photocatalyst exhibited a significantly increased photocatalytic H2 evolution rate of 1595 μmol h-1 g-1 (apparent quantum efficiency of 22.6 % at λ=420 nm), which is over 10.5 times higher than that of CdS. Moreover, a better photocatalytic stability is demonstrated over particulate (42 h cycling measurement) and photoelectrochemical (3000 min continuous measurement) systems. Overall, this work provides a unique experimental insight into high-quality heterojunction interface design and new Z-scheme photocatalyst synthesis.

Sediment Transport in Sewage Pressure Pipes, Part I: Continuous Determination of Settling and Erosion Characteristics by In-Situ TSS Monitoring Inside a Pressure Pipe in Northern Germany

Continuous measurement systems are widely spread in sewers, especially in non-pressure systems. Due to its relatively low costs, turbidity sensors are often used as a surrogate for other indicators (solids, heavy metals, organic compounds). However, little effort is spent to turbidity sensors in pressurized systems so far. This work presents the results of one year in-situ turbidity/total suspended solids (TSS) monitoring inside a pressure pipe (600 mm diameter) in an urban region in northern Germany. The high-resolution sensor data (5 s interval) are used for the determination of solids sedimentation (within pump pauses) and erosion behavior (within pump sequences). In-situ results from sensor measurements are similar to laboratory results presented in previous studies. TSS is decreasing exponentially in pump pauses under dry weather inflow with an average of 0.23 mg/(L s). During pump sequences, solids eroded completely at a bed shear stress of 0.5 N/m². Sedimentation and erosion behavior changes with the inflow rate. Solids settle faster with increasing inflow: at storm water inflow with an average of 0.9 mg/(L s) and at diurnal inflow variation up to 0.6 mg/(L s) at 12:00 a.m. The results are used as calibration data for a sediment transport simulation in Part II.

Artificial Neural Network in the Measurement of Environmental Odours by E-Nose

Odour measurement plays a crucial role in environmental odour management. Continuous odour measurement systems are promoted to keep the situation always under control, such as being able to adopt the most suitable mitigation measures in real time to avoid odour complaints and impacts. Electronic Nose (eNose) represents currently the instrument of having the highest future developing potential to guarantee continuous odour measurements. To use an eNose, a training phase is however mandatory, which has the scope to create the Odour Monitoring Model (OMM) that is able to identify the presence of odour, the different odour classes and the quantification of the odorous stimuly. Statistical or biological inspired measurement techniques are applied to create the optimum OMM.The study presents and discusses the elaboration of an Artificial Neural Network (ANN) technique to recognize environmental odour with eNose. The proposed system was architected on a feed-forward neural network with Bayesian Regularization algorithm using Matlab R2017a software.The elaborated ANN was tested and validated using the seedOA eNose, realized by the Sanitary Environmental Engineering Division (SEED) of the Department of Civil Engineering of the University of Salerno (Italy). Tests were carried out analyzing odour samples collected at a large Wastewater Treatment Plant (WWTP). The comparison between the Odour Monitoring Model (OMM) elaborated through the proposed ANN system and the traditional statistical techniques, such as the Partial Least Square (PLS) and the Linear Discriminant Analysis (LDA), is also discussed.Results shown the efficiency of the elaborated ANN to identify the different odour classes and predict the odour concentration in terms of OUm-3. The artificial neural network shows smaller Root Mean Squared Errors (RMSE) and greater coefficient of determination (R2) as compared to the traditional statistical methods. The main advantages of neural networks are their adaptability in terms of learning, self-organization, training and noise-tolerance.

Explaining CO2 fluctuations observed in snowpacks

Abstract. Winter soil carbon dioxide (CO2) respiration is a significant and understudied component of the global carbon (C) cycle. Winter soil CO2 fluxes can be surprisingly variable, owing to physical factors such as snowpack properties and wind. This study aimed to quantify the effects of advective transport of CO2 in soil–snow systems on the subdiurnal to diurnal (hours to days) timescale, use an enhanced diffusion model to replicate the effects of CO2 concentration depletions from persistent winds, and use a model–measure pairing to effectively explore what is happening in the field. We took continuous measurements of CO2 concentration gradients and meteorological data at a site in the Cape Breton Highlands of Nova Scotia, Canada, to determine the relationship between wind speeds and CO2 levels in snowpacks. We adapted a soil CO2 diffusion model for the soil–snow system and simulated stepwise changes in transport rate over a broad range of plausible synthetic cases. The goal was to mimic the changes we observed in CO2 snowpack concentration to help elucidate the mechanisms (diffusion, advection) responsible for observed variations. On subdiurnal to diurnal timescales with varying winds and constant snow levels, a strong negative relationship between wind speed and CO2 concentration within the snowpack was often identified. Modelling clearly demonstrated that diffusion alone was unable to replicate the high-frequency CO2 fluctuations, but simulations using above-atmospheric snowpack diffusivities (simulating advective transport within the snowpack) reproduced snow CO2 changes of the observed magnitude and speed. This confirmed that wind-induced ventilation contributed to episodic pulsed emissions from the snow surface and to suppressed snowpack concentrations. This study improves our understanding of winter CO2 dynamics to aid in continued quantification of the annual global C cycle and demonstrates a preference for continuous wintertime CO2 flux measurement systems.

Numerical Modelling of the 1995 Dinar Earthquake Effects on Hydrodynamic Regime of Egirdir Lake

The effect of earthquakes on closed and semi-closed water systems is a research topic that has been studied for many years. The lack of continuous measurement systems in closed and semi-closed water systems is insufficient to examine and investigate what has happened during the earthquake. The morphological structures of the lakes indicate the characteristics of the events that occurred during an earthquake. Due to the developing technology and research request, some monitoring, measurement stations are installed in some lakes, gulfs, estuaries, etc. systems. Today, both higher quality measurement and field data can be obtained, and more complicated processes are being explored with the help of faster computers. Computational fluid dynamics is currently used because of the difficulty in calculating hydrodynamic responses of lakes due to earthquake. Investigations on the effects of the earthquake condition on the desired closed / semi-closed water system studies by using numerical modelling have been continuing increasingly in recent years. Both the quality of the bathymetric data gathered from the field, the continuous acquisition of both dynamic water level measurement systems, and the use of new technologies and systems in the search for base materials contribute to the fact that we have more knowledge of the formation, behavior and effects of the sorts. In this study, 1995 Dinar Earthquake effects on Egirdir Lake hydrodynamic regime was investigated by numerical modelling approach.

DARMA: Software for dual axis rating and media annotation.

Continuous measurement systems provide a means of measuring dynamic behavioral and experiential processes as they play out over time. DARMA is a modernized continuous measurement system that synchronizes media playback and the continuous recording of two-dimensional measurements. These measurements can be observational or self-reported and are provided in real-time through the manipulation of a computer joystick. DARMA also provides tools for reviewing and comparing collected measurements and for customizing various settings. DARMA is a domain-independent software tool that was designed to aid researchers who are interested in gaining a deeper understanding of behavior and experience. It is especially well-suited to the study of affective and interpersonal processes, such as the perception and expression of emotional states and the communication of social signals. DARMA is open-source using the GNU General Public License (GPL) and is available for free download from http://darma.jmgirard.com .

Comparative study of gas-analyzing systems designed for continuous monitoring of TPP emissions

Determining the composition of combustion products is important in terms of both control of emissions into the atmosphere from thermal power plants and optimization of fuel combustion processes in electric power plants. For this purpose, the concentration of oxygen, carbon monoxide, nitrogen, and sulfur oxides in flue gases is monitored; in case of solid fuel combustion, fly ash concentration is monitored as well. According to the new nature conservation law in Russia, all large TPPs shall be equipped with continuous emission monitoring and measurement systems (CEMMS) into the atmosphere. In order to ensure the continuous monitoring of pollutant emissions, direct round-the-clock measurements are conducted with the use of either domestically produced or imported gas analyzers and analysis systems, the operation of which is based on various physicochemical methods and which can be generally used when introducing CEMMS. Depending on the type and purposes of measurement, various kinds of instruments having different features may be used. This article represents a comparative study of gas-analysis systems for measuring the content of polluting substances in exhaust gases based on various physical and physicochemical analysis methods. It lists basic characteristics of the methods commonly applied in the area of gas analysis. It is proven that, considering the necessity of the long-term, continuous operation of gas analyzers for monitoring and measurement of pollutant emissions into the atmosphere, as well as the requirements for reliability and independence from aggressive components and temperature of the gas flow, it is preferable to use optical gas analyzers for the aforementioned purposes. In order to reduce the costs of equipment comprising a CEMMS at a TPP and optimize the combustion processes, electrochemical and thermomagnetic gas analyzers may also be used.

Investigation of the effects of using single-wall carbon nanotubes (SWCNTs) in ozone measurement with passive samplers

ABSTRACTPassive samplers are used in air quality monitoring for many years to compete in terms of being economical with continuous measurement systems. In this study, different amounts of single-wall carbon nanotubes (SWCNTs) were added in the impregnation solution of the filters of passive samplers and the effect on the absorption of ozone studied. The results of the measurement of ozone with varying amounts of SWCNTs added to the impregnation solution of the filters of the passive samplers were compared with the results of the continuous ozone measurement system (CS). Measurements were performed for 7 days and 14 days at two different exposure times. The increase of the amount of SWCNTs on the filters of the passive samplers, however, did not have an effect on the measurement of ozone. The measurement results of the passive samplers of the 14-day exposure periods, alternating with the 7-day exposure periods, were lower considerably than the results of the 7-day exposure.Implications: The accuracy and the use of passive samplers in SWCNTs are expected to provide high measurement results. Observing the effect of the change in the amount of diffusion of pollutants held in the SWCNT is also one of the expected implications.

Single source photoplethysmograph transducer for local pulse wave velocity measurement.

Cuffless evaluation of arterial blood pressure (BP) using pulse wave velocity (PWV) has received attraction over the years. Local PWV based techniques for cuffless BP measurement has more potential in accurate estimation of BP parameters. In this work, we present the design and experimental validation of a novel single-source Photoplethysmograph (PPG) transducer for arterial blood pulse detection and cycle-to-cycle local PWV measurement. The ability of the transducer to continuously measure local PWV was verified using arterial flow phantom as well as by conducting an in-vivo study on 17 volunteers. The single-source PPG transducer could reliably acquire dual blood pulse waveforms, along small artery sections of length less than 28 mm. The transducer was able to perform repeatable measurements of carotid local PWV on multiple subjects with maximum beat-to-beat variation less than 12%. The correlation between measured carotid local PWV and brachial BP parameters were also investigated during the in-vivo study. Study results prove the potential use of newly proposed single-source PPG transducers in continuous cuffless BP measurement systems.

Noninvasive Hemodynamic Monitoring Devices

Noninvasive Hemodynamic Monitoring Devices

Intraindividual differences between two simultaneous glucose measurement systems in type 2 diabetic patients

Continuous glucose measurement systems are an established tool to support diabetes therapy. Because of different technical solutions one can propose different potential limitations in daily practice. So we tried to identify the accuracy of two different devices head to head in daily routine to point out individual characteristics. We included 24 patients with type 2 diabetes mellitus to wear the GlucoDay and the MiniMed continuous glucose measurement system at the same time for 48h. We examined the mean differences in simultaneous glucose measurements, the confidence intervals were calculated by standard methods based on the t-distribution. Comparison of glucose levels of both continuous glucose measurement systems showed that there was a tendency for higher glucose levels measured by the GlucoDay device. These differences were dependent on the time of the day. The absolute difference between two consecutive glucose measurements was higher for the GlucoDay system what means a somehow higher fluctuation of the GlucoDay measurements. The differences in intraindividual comparison of the GlucoDay and the MiniMed continuous glucose measurement systems in type 2 diabetic patients may be taken into account when using different systems for detection of nocturnal hypoglycemia and the observation of trends used for therapeutic decisions.

Nitrous Oxide Emission by Agricultural Soils: A Review of Spatial and Temporal Variability for Mitigation

This short review deals with soils as an important source of the greenhouse gas N2O. The production and consumption of N2O in soils mainly involve biotic processes: the anaerobic process of denitrification and the aerobic process of nitrification. The factors that significantly influence agricultural N2O emissions mainly concern the agricultural practices (N application rate, crop type, fertilizer type) and soil conditions (soil moisture, soil organic C content, soil pH and texture). Large variability of N2O fluxes is known to occur both at different spatial and temporal scales. Currently new techniques could help to improve the capture of the spatial variability. Continuous measurement systems with automatic chambers could also help to capture temporal variability and consequently to improve quantification of N2O emissions by soils. Some attempts for mitigating soil N2O emissions, either by modifying agricultural practices or by managing soil microbial functioning taking into account the origin of the soil N2O emission variability, are reviewed.

Model-Based Design of Experiments in the Presence of Continuous Measurement Systems

Model-based design of experiments (MBDoE) techniques are a useful tool to maximize the information content of experimental trials when the purpose is identifying the set of parameters of a deterministic model in a statistically sound way. Traditionally, the problem of MBDoE has been addressed for discrete measurement systems. In this case, formulation of the optimal design problem is based on maximization of the expected information, usually calculated from discrete forms of the Fisher information matrix. However, current measurement technology allows measurements to be taken at a much higher frequency than in the past, to a point that measurements may be assumed to be obtained in a continuous way. A novel design criterion allowing for the continuous model-based design of the experiments (CMBDoE) is formulated in this paper by optimizing a continuous measurement function of the Fisher information matrix, with the purpose of reaching a statistically satisfactory estimation of model parameters in a computationally efficient way. The benefits of the proposed strategy are discussed by means of two simulated case studies, where the effectiveness of the design is assessed by comparison to a standard MBDoE approach.

Temperature and Time of Day Influence on Double‐Ring Infiltrometer Steady‐State Infiltration Rates

Steady‐state infiltration rates (IRs) correlate well with temperature. They have been observed, however, to have values 1.5 to 2.5 times higher than predicted by viscosity, known as the t‐effect Many field studies that have observed the t‐effect used continuous IR measurement systems. We measured 67 IRs using double‐ring infiltrometers (DRIs) during the 2007 and 2008 autumn seasons in sand and loamy sand soils across a temperature range of 5 to 35°C. We found above‐average to good correlation between temperature and IR. For loamy sand (n = 17), IR rate differences were accounted for by viscosity differences, but for sand (n = 30) the IR values were 2.0 to 2.9 times higher than the viscosity‐predicted rate. Additionally, we found a difference in the IR temperature regressions based on the time of day of the measurements in the sand. Morning measurements were two times the viscosity‐predicted IR, while afternoon measurements were nearly three times. This research corroborates other field studies that observed the t‐effect using DRIs.

Towards Using Photo-Plethysmogram Amplitude to Measure Blood Pressure During Sleep

There is considerable interest in non-intrusive and reliable continuous ambulatory blood pressure measurement systems. Pulse amplitude is the peak to trough amplitude of the photo-plethysmogram signal. We compared pulse amplitude with a currently popular parameter, the pulse arrival time (PAT), for estimating continuous systolic blood pressure (SBP). Overnight sleep data from 18 young, healthy subjects (14 M 4 F, age 24+/-5 years, BMI 23.8+/-4.0 kg/m2) was analyzed. We found that pulse amplitude was more effective than PAT for estimating SBP during sleep. Mean coherence between pulse amplitude and SBP was significantly stronger than that for PAT [p<0.001, 95% CI: 0.21-0.25 (finger), 0.11-0.14 (wrist)]. Correlation between pulse amplitude and SBP was significantly stronger than that for PAT [p<0.001, 95% CI: 0.46-0.53 (finger), 0.13-0.20 (wrist)]. SBP estimation errors were significantly lower using pulse amplitude [p<0.001, 95% CI: -1.55 to -1.29 mmHg (finger), -0.53 to -0.36 mmHg (wrist)]. We also found that while pulse amplitude was closely related to SBP, the relationship weakened during and around REM sleep (ANOVA of REM, transitional Wake-REM and transitional REM-Sleep versus other sleep states: F=24.7, p<0.001). These results suggest that pulse amplitude is potentially a more suitable measure than pulse arrival time for estimating continuous blood pressure.