Continuous Measurement System Research Articles

A low-cost versatile system for continuous real-time respiratory activity measurement as a tool in environmental research

Low-cost sensors available on the market allow reliable and straightforward research of model organism responses to changes in environmental conditions caused by xenobiotics or natural ecological processes. The purpose of this work was to develop a low-cost Arduino-based respiratory activity measuring system employing CO2 sensors (ResTox) applicable for various research and risk assessment purposes, providing a stable platform and support for further development and extension of current capabilities. The presented system comprises hardware and accompanying software solutions. The instrument employs multiple digital CO2 measuring sensors based on non-dispersive infrared (NDIR) technology, a waterproof temperature sensor, and a phototransistor light sensor. The cross-platform ResTox software support enables simple control of the measuring device and sensor output data storage during the experiments. Due to its uncomplicated and compact design, the developed system represents a versatile solution for experiments in both field and laboratory conditions and with animal and plant organisms.

A low-cost automated growth chamber system for continuous measurements of gas exchange at canopy scale in dynamic conditions

BackgroundObtaining instantaneous gas exchanges data is fundamental to gain information on photosynthesis. Leaf level data are reliable, but their scaling up to canopy scale is difficult as they are acquired in standard and/or controlled conditions, while natural environments are extremely dynamic. Responses to dynamic environmental conditions need to be considered, as measurements at steady state and their related models may overestimate total carbon (C) plant uptake.ResultsIn this paper, we describe an automatic, low-cost measuring system composed of 12 open chambers (60 × 60 × 150 cm; around 400 euros per chamber) able to measure instantaneous CO2 and H2O gas exchanges, as well as environmental parameters, at canopy level. We tested the system’s performance by simulating different CO2 uptake and respiration levels using a tube filled with soda lime or pure CO2, respectively, and quantified its response time and measurement accuracy. We have been also able to evaluate the delayed response due to the dimension of the chambers, proposing a method to correct the data by taking into account the response time ({t}_{0}) and the residence time (τ). Finally, we tested the system by growing a commercial soybean variety in fluctuating and non-fluctuating light, showing the system to be fast enough to capture fast dynamic conditions. At the end of the experiment, we compared cumulative fluxes with total plant dry biomass.ConclusionsThe system slightly over-estimated (+ 7.6%) the total C uptake, even though not significantly, confirming its ability in measuring the overall CO2 fluxes at canopy scale. Furthermore, the system resulted to be accurate and stable, allowing to estimate the response time and to determine steady state fluxes from unsteady state measured values. Thanks to the flexibility in the software and to the dimensions of the chambers, even if only tested in dynamic light conditions, the system is thought to be used for several applications and with different plant canopies by mimicking different environmental conditions.

An AI(Artificial Intelligence) based Device for Covid-19 Fever Detection

Coronavirus disease (covid-19) is a global pandemic, and every country is actively fighting against the virus. It is an effective way to prevent the spread of the virus in finding the person with abnormal temperature promptly to perform the further medical observation. However, the traditional method of temperature measurement has low efficiency and accuracy. Body temperature acting as important role in medicine, several diseases is characterized by a change in human body temperature. Monitoring body temperature also allows the doctor to track the effectiveness of treatments. But current continuous body temperature measurement system is mainly limited by reaction time, movement noise, and labour requirement. In addition, the traditional contact body temperature measurement has the problem of wasting consumables and causing discomfort. To address the above issues, we present a non contact, automatic system using a single thermal non-contact sensor. The Proposed Covid prevention method scans body temperature through MLX9014 Contactless Temperature Sensor and sends the data to Raspberry pi model 3+ architecture. Our application takes data from MLX9014 and analyzes it to see whether the temperature is greater than 370 Celsius , which then captures the image through pi camera.

The role of gas dispersion in the oxygen delignification process

Oxygen delignification is an essential part of the pulp production process. Delignification occurs with the aid of alkali and dissolved oxygen. Dissolved oxygen is obtained by dispersing oxygen gas into the pulp suspension by using efficient mixers. Little is known about the state of oxygen gas dispersion and its effect on oxy-gen delignification kinetics and efficiency. This paper will present the results for the effect of gas bubble size on the performance of oxygen delignification. The results are mainly based on detailed studies made in a Finnish hardwood mill where the oxygen bubble size distribution could be altered at the feed of the reactor. An essential aspect of these studies was the use of a new continuous inline gas bubble size measurement system to simultaneously determine the bubble size distribution at the feed and top of the reactor. Information about oxygen consumption in the reactor could also be obtained through the bubble size measurements. Accordingly, these studies quantify the effect of oxygen bubble size on the kappa reduction of the pulp. The effect of different chemical factors on the oxygen bubble size is also studied. Finally, the relationship between the gas bubble size and the liquid phase oxygen mass transfer coefficient (kLa) is presented. This connects the bubble size to the kappa reduction rate. Based on the presented modeling approach and the evaluation of practical factors that are not taken into account in the modeling, it was concluded that the volumetric average oxygen bubble size should preferably be smaller than 0.2 mm in practice. The information obtained with the new gas bubble size measurement system and the presented modeling approach give a very new basis for understanding, monitoring, adjusting, and designing oxygen delignification processes.

Intelligent system for measuring the level and mass of liquid in fuel tanks and tanks during pitching and tilting

An overview of the existing methods for measuring the liquid level and their disadvantages in the case of surface vibrations is presented. A system for continuous measurement of the mass of liquids in fuel tanks and tanks during rolling and tilting of vehicles and ships, implemented in a level gauge based on intelligent sensors, is proposed. The sensors include a microcontroller with an individual calibration characteristic of the volume-level dependence, taking into account the shape of the tank or fuel tank, and nanosensors built into the intelligent sensor (ID) for measuring density, permittivity and ambient temperature. It is established that the actual metrological characteristics of the ID are significantly higher than the characteristics of traditional sensors. The number and dimensions of the plates of flat capacitors are justified and the scheme of their arrangement on the roof of the tanks is presented. The exclusion of movable elements increased the reliability of operation, simplified maintenance and design requirements of the measuring object. Analytical expressions for calculating the level and mass of the liquid, implemented by the microcontroller, are given. The use of the proposed measurement system with complex computational processing and taking into account corrections for temperature, density, humidity and permittivity of the liquid made it possible to increase the accuracy and stability of the level meter readings. Analytical expressions are derived that relate the liquid level and the output frequency of the generator from the composition of the level gauge.

Continuous Chemiluminescence Measurements of Dissolved Nitric Oxide (NO) and Nitrogen Dioxide (NO2) in the Ocean Surface Layer of the East China Sea

Nitric oxide (NO) is a short-lived intermediate of the oceanic nitrogen cycle, and it is produced by biological and photochemical processes in the ocean. Nitrogen dioxide (NO2) is a reactive atmospheric compound which has not been determined in the ocean so far. Here, we present the setup and validation of a novel continuous underway measurement system to measure dissolved NO and NO2 in the surface ocean. The system consists of a seawater/gas equilibration component coupled to a chemiluminescence detector. It was successfully deployed during a 12 day cruise to the East China Sea in May 2018. Dissolved NO and NO2 surface concentrations ranged from <limit of detection (LOD) to 98 × 10-12 mol L-1 and <LOD to 83 × 10-12 mol L-1, respectively. The ECS was supersaturated with NO but significantly undersaturated with NO2, indicating that the surface waters were a source for atmospheric NO but a sink for atmospheric NO2 at the time of our measurements.

Development of an electrode system for continuous measurement of the volume of an AHV

Mechanical circulatory assistance devices are vital for the patients with end-stage heart failure, who require heart transplantation but are in a waiting list due to the shortage of donor organs. This makes the development of the advanced MCS devices and artificial heart ventricles a crucial task. The systems for the dynamic and adaptive control of circulation parameters are required. AHV liquid volume measurement units must be developed to create such systems. Objective – Determination of the optimal electrode system for the AHV liquid volume measurement unit based on the electrical impedance measurements. The most significant geometrical parameters of the electrode systems for the impedance based AHV liquid volume measurement are determined. The optimal values of the geometrical parameters were found for the system of dynamic AHV liquid volume measurement. Results were confirmed by the numerical and experimental studies. The obtained values of the optimal geometrical parameters of electrode systems will be used in development of biotechnical system of adaptive AHV control.

Low-cost continuous measurement system to learn the relationship between electrical conductivity and temperature in brackish waters

Low-cost continuous measurement system to learn the relationship between electrical conductivity and temperature in brackish waters

Assessment of Hypertension Using Clinical Electrocardiogram Features: A First-Ever Review

Hypertension affects an estimated 1.4 billion people and is a major cause of morbidity and mortality worldwide. Early diagnosis and intervention can potentially decrease cardiovascular events later in life. However, blood pressure (BP) measurements take time and require training for health care professionals. The measurements are also inconvenient for patients to access, numerous daily variables affect BP values, and only a few BP readings can be collected per session. This leads to an unmet need for an accurate, 24-h continuous, and portable BP measurement system. Electrocardiograms (ECGs) have been considered as an alternative way to measure BP and may meet this need. This review summarizes the literature published from January 1, 2010, to January 1, 2020, on the use of only ECG wave morphology to monitor BP or identify hypertension. From 35 articles analyzed (9 of those with no listed comorbidities and confounders), the P wave, QTc intervals and TpTe intervals may be promising for this purpose. Unfortunately, with the limited number of articles and the variety of participant populations, we are unable to make conclusions about the effectiveness of ECG-only BP monitoring. We provide 13 recommendations for future ECG-only BP monitoring studies and highlight the limited findings in pregnant and pediatric populations. With the advent of convenient and portable ECG signal recording in smart devices and wearables such as watches, understanding how to apply ECG-only findings to identify hypertension early is crucial to improving health outcomes worldwide.

Single-Channel Bioimpedance Measurement for Wearable Continuous Blood Pressure Monitoring

Pulse transit time (PTT) sensing technology is rapidly evolving for cuffless continuous blood pressure (BP) monitoring. However, PTT-based BP methods must implement multidevices that could impede wearable applications. This work presents the study and development of a single-channel wrist-worn impedance plethysmography (IPG) system for wearable continuous BP measurement. IPG-based BP mathematical model with two-step calibration was derived for single physiological signal acquisition. The high-resolution IPG measurement was performed by optimized injection current frequency and electrode arrangement in response to obvious impedance difference between systolic BP (SBP) and diastolic BP (DBP) feature points in the IPG waveform, resulting in an impedance difference of 594 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{m}\Omega $ </tex-math></inline-formula> . The BP accuracy results within 30 subjects indicated that SBP estimation error was 2.01 ± 1.40 mmHg and 1.83 ± 1.29% in terms of mean absolute error (MAE) and mean absolute percentage error (MAPE), and 2.26 ± 1.43 mmHg and 4.96 ± 3.02% for DBP estimation. The novel system could potentially be implemented as a wearable cardiovascular monitoring device with two-in-one functions (continuous BP and heart rate monitoring) using a single physiological sensor in the future.

Design of Tracking, Telemetry, Command (TT&amp;C) and Data Transmission Integrated Signal in TDD Mode

For satellite or aircraft networks, tracking, telemetry, and control (TT&amp;C) and data transmission between different nodes are necessary. Traditional measurement mostly adopts the frequency division duplex (FDD) mode and uses a continuous measurement system to achieve high-precision measurement. However, as the number of network nodes increases, the mode suffers from complex frequency domain allocation, and high-cost measurement and data transmission equipment is required. This paper proposes the integrated signal in time division duplex (TDD) mode to improve frequency utilization to address these circumstances. The proposed signal can transmit the TT&amp;C and data at the same frequency. In addition, the high-precision time-frequency synchronization and relative measurement technology in the TDD mode for distributed spacecraft or aircraft networks are studied. The simulation results show that the signal can work normally when the Doppler extrapolation error is less than a quarter of the integration frequency. The distance extrapolation error should be less than a quarter of the length of a chip. The integrated signal reduces the frequency band occupation and realizes the integration of TT&amp;C and data transmission. In addition, the measurement performance is reduced by only 2~3 dB compared with that of the traditional pure TT&amp;C signal.

Assessment of Cornfield LAI Retrieved from Multi-Source Satellite Data Using Continuous Field LAI Measurements Based on a Wireless Sensor Network

Accurate and continuous monitoring of leaf area index (LAI), a widely-used vegetation structural parameter, is crucial to characterize crop growth conditions and forecast crop yield. Meanwhile, advancements in collecting field LAI measurements have provided strong support for validating remote-sensing-derived LAI. This paper evaluates the performance of LAI retrieval from multi-source, remotely sensed data through comparisons with continuous field LAI measurements. Firstly, field LAI was measured continuously over periods of time in 2018 and 2019 using LAINet, a continuous LAI measurement system deployed using wireless sensor network (WSN) technology, over an agricultural region located at the Heihe watershed at northwestern China. Then, cloud-free images from optical satellite sensors, including Landsat 7 the Enhanced Thematic Mapper Plus (ETM+), Landsat 8 the Operational Land Imager (OLI), and Sentinel-2A/B Multispectral Instrument (MSI), were collected to derive LAI through inversion of the PROSAIL radiation transfer model using a look-up-table (LUT) approach. Finally, field LAI data were used to validate the multi-temporal LAI retrieved from remote-sensing data acquired by different satellite sensors. The results indicate that good accuracy was obtained using different inversion strategies for each sensor, while Green Chlorophyll Index (CIgreen) and a combination of three red-edge bands perform better for Landsat 7/8 and Sentinel-2 LAI inversion, respectively. Furthermore, the estimated LAI has good consistency with in situ measurements at vegetative stage (coefficient of determination R2 = 0.74, and root mean square error RMSE = 0.53 m2 m−2). At the reproductive stage, a significant underestimation was found (R2 = 0.41, and 0.89 m2 m−2 in terms of RMSE). This study suggests that time-series LAI can be retrieved from multi-source satellite data through model inversion, and the LAINet instrument could be used as a low-cost tool to provide continuous field LAI measurements to support LAI retrieval.

Spatiotemporal variations and controlling factors of the surface pCO2 in the northern South China Sea

The focal area of this study was the northern South China Sea (NSCS; 18.5°-22.5°N, 1.0°-8.0°E), located on the northwestern shelf of the SCS. The surface pCO2 (pCO2w), sea surface temperature (SST) and sea surface salinity (SSS) was measured by continuous measurement system during four field surveys to show their spatiotemporal variations in the NSCS. Low pCO2w in the southwestern region of PRE were observed in four seasons, particularly in spring and summer. The Pearl River diluted water (PRDW) discharged a large amount of nutrients into nearshore waters, which promoted phytoplankton propagation and CO2 uptake in spring and summer. On the contrary, primary productivity was low in winter and late autumn, runoff input of dissolved inorganic carbon (DIC) played important role in increasing the pCO2 in nearshore waters, so the PRDW controlled the spatiotemporal variations of pCO2w in the coastal and inner shelf. The pCO2w in the outer shelf and slope were relatively high in four seasons, and SST was the critical controlling factor of pCO2w, sea-air CO2 exchange also played role in the seasonal scales of pCO2w, the impact of weather and climate events on the variations of pCO2w and sea-air CO2 flux in the short term also were remarkable. Generally, the NSCS acted as sink of atmospheric CO2 in spring, late autumn and winter, particularly in latter two seasons, in contrast, it was weak CO21 source in summer.

Temperature-time monitoring of concrete hardening of a wind farm foundation

The foundations of wind farms are massive structures that require temperature control of concrete hardening during their construction. This is due to the need to ensure crack resistance and specific operating conditions of engineering networks located in the body of the structure. The work describes a comprehensive study of the foundations construction on the Zaporizhzhya wind farm. The study included calorimetric analysis using adiabatic calorimetry and on-site temperature monitoring of the object using a continuous temperature measurement system. Laboratory studies allowed verify the composition of concrete proposed by the concrete manufacturer and develop recommendations for concreting. The data obtained showed that the hardening conditions approach adiabatic ones with a foundation slab thickness of more than 2.5 m. This leads to a temperature gradient of more than 25 ° C between the internal and external parts of the structure. The adopted recipe and technological solutions have ensured the achievement of acceptable conditions for the foundation slab construction in the winter.

Monoterpene Chemical Speciation with High Time Resolution Using a FastGC/PTR-MS: Results from the COV3ER Experiment on Quercus ilex

Monoterpenes (MTs) represent an important family of biogenic volatile organic compounds (BVOCs) in terms of amount and chemical diversity. This family has been extensively studied using gas chromatography (GC) and proton transfer reaction-mass spectrometry (PTR-MS). Upon recent advances with Fast Gas Chromatography (FastGC), it was also commercialized with proton transfer reaction-time of flight-mass spectrometry (PTR-ToF-MS) instruments. The combination of both techniques showed promising results in the near real-time separation of isomers, with the need of further improvements. In this study, a FastGC prototype was coupled to a conventional PTR-MS (PTR-QuadMS). Extensive laboratory experiments were performed, in order to test the system’s performance and to optimize its operational parameters for MT separation. The detection limit was determined to be around 0.8–1.7 ppbv, depending on the MT. The system was afterwards deployed during a three-week field campaign in a mixed holm oak (Quercus ilex) forest known for its important MT emissions. MTs were measured in the incoming and the outgoing air of dynamic enclosures installed on the branches of four different trees. Three chemotypes of holm oak trees could be distinguished showing consistently different proportions of the emitted MTs throughout the measurement campaign: pinene-type, myrcene-type and limonene-type. Measurements showed a systematic diel variation in emissions typical of light and temperature-dependent, de novo-synthesized VOCs. The results demonstrated the feasibility of the FastGC/PTR-MS system for continuous measurements from dynamic chambers in the field, whereas further improvements would be necessary to lower the detection limit for ambient air measurements.

Fluid Mud Measurement and Siltation Analysis in A Trial Excavated Channel in the Approach Channel of the Xiangshan Port

In order to clarify the distribution and variation of silt and fluid mud in the Waiganmen shallow section of the 50000-ton intake channel of the Xiangshan Port, and to understand the influence of the channel excavation on the surrounding flow conditions and the strength of the backsilting, especially the impact of typhoon on the sudden silting of the channel, so as to demonstrate the feasibility and stability of the channel excavation. The fluid mud, hydraulic, sediment and topographic measurements were carried out in the study area, and the thickness of the fluid mud layers, tidal current, sediment and topographic data were obtained. Dual-frequency sounder, gamma-ray densitometer and SILAS navigational fluid mud measurement system were used to monitor the fluid mud, and the results were compared and verified. The adaptability and accuracy of the three methods were analyzed. The SILAS navigational continuous density measurement system and gamma-ray fixed-point fluid mud measurement are used to detect the density, thickness and variation of the fluid mud accurately. Based on the hydrological observation data, the process of erosion and deposition in excavation channel and its influence mechanism are analyzed, and the distribution characteristics and evolution law of siltation in engineering area are given in the form of empirical formula. The research shows that the super typhoon can produce large siltation, which results in sudden siltation of the channel. The tidal current is the main dynamic factor of the change of erosion and siltation of the excavation trench. Under the influence of reciprocating tidal current and excavation topography, the trial excavation trench is silted on the whole. There is fluid mud in the monitoring area of the trench, and the distribution of fluid mud is different in space. The thickness of the fluid mud at the bottom of the trench is generally larger than that outside the trench and the slope of the trench, and the siltation of the trench tends to be slow. The research results can provide scientific evaluation for channel excavation and maintenance, and support for the implementation of the project.

Estimating Blood Pressure from the Photoplethysmogram Signal and Demographic Features Using Machine Learning Techniques

Hypertension is a potentially unsafe health ailment, which can be indicated directly from the blood pressure (BP). Hypertension always leads to other health complications. Continuous monitoring of BP is very important; however, cuff-based BP measurements are discrete and uncomfortable to the user. To address this need, a cuff-less, continuous, and noninvasive BP measurement system is proposed using the photoplethysmograph (PPG) signal and demographic features using machine learning (ML) algorithms. PPG signals were acquired from 219 subjects, which undergo preprocessing and feature extraction steps. Time, frequency, and time-frequency domain features were extracted from the PPG and their derivative signals. Feature selection techniques were used to reduce the computational complexity and to decrease the chance of over-fitting the ML algorithms. The features were then used to train and evaluate ML algorithms. The best regression models were selected for systolic BP (SBP) and diastolic BP (DBP) estimation individually. Gaussian process regression (GPR) along with the ReliefF feature selection algorithm outperforms other algorithms in estimating SBP and DBP with a root mean square error (RMSE) of 6.74 and 3.59, respectively. This ML model can be implemented in hardware systems to continuously monitor BP and avoid any critical health conditions due to sudden changes.

In-Sewer Field-Evaluation of an Optical Fibre-Based Condition Monitoring System

A Fiber Bragg Grating (FBG) based monitoring system for continuous humidity and temperature measurement has been designed and evaluated experimentally in a sewer environment with high corrosion rates, humidity and the presence of gaseous hydrogen sulfide. The monitoring system has been designed specifically for field use, including packaging prepared for the harsh environment and the challenges of the operation. The system is battery powered and has hardware for controlling the interrogation equipment, power management, data logging and 4G connectivity. Results obtained show the long-term performance, over a 6-month period of non-stop monitoring of real-time data using the same probe. The data acquired was compared to the environmental data of temperature and precipitation for this period from the same location, which showed a good correlation between the expected and the measured data values. The data obtained point to the success of the optical fibre-based sensor system for monitoring in these harsh environments over long periods.

A self-control and visual grouting model test system and measurement method

The invisibility of grouting has been one of the most challenging problems that still remain unsolved related to studies in grouting theory. This paper presents a self-control and visual grouting model test system to realize the visualization of grouting process in sand. This system consists of (1) visual simulation material of rock masses, (2) high-strength transparent device, (3) parameter-controlled grout pumping equipment and (4) continuous physical field measurement system. A kind of visual material is used to simulate sand. A transparent device, measuring 200 mm long, 100 mm wide, and 150 mm high, is the place where visual material filling and grout injection are conducted. This parameter-controlled grout pumping equipment can realize grouting with a constant injection rate within the range of 0–2 mm/s. In addition, the continuous physical field measurement system, comprised of laser, CCD camera, data analysis software and computer, can be used to obtain continuous physical field changes caused by grouting in sand. To verify the suitability of this test system, grouting simulation test in sand was conducted. Test results present that the grout diffusion pattern shows ellipsoid-shape, which matches well with previous studies. This test system is therefore capable of conducting visual grouting experiments.

A wearable continuous core temperature measurement system based on the Zero-Heat-Flux method

A wearable continuous core temperature measurement system based on the Zero-Heat-Flux method