Submersible Sensors Research Articles

A multivariable submersible sensor for monitoring in real-time industrial flotation cells

This paper describes the development and validation of a submersible sensing technology for industrial flotation cells. The sensor provides simultaneous real-time measurements of gas and solid holdups, as well as the density and viscosity of the slurry in the pulp zone of flotation machines. The submersible device comprises a gas exclusion cell, which resembles an inverted truncated cone assembled to a single-straight tube Coriolis meter. When the sensor device is vertically immersed in the aerated slurry, a continuous bubble-free flow of slurry is induced through the device, which allows the Coriolis meter to provide measurements of the slurry flow, density, and viscosity. The magnitude of the induced flow is a primary function of the sensor’s geometry and gas holdup. Applying the Bernoulli equation reveals that gas holdup can be expressed as the square of the induced flow velocity. A discharge coefficient parameter is introduced to compensate for variations in the velocity profile and flow losses. This coefficient is a function of the fluid Reynolds number, calculated in real-time based on the Coriolis measurements. The sensing technology was assessed in a pilot column operated in a water–air system and industrial forced-air and self-aspirated large flotation cells. Results demonstrate the sensor’s capabilities to provide reliable, accurate, real-time, long-term continuous gas dispersion and solid suspension-related variables, which could be used for supervision, control, and optimization applications.

A low-cost IoT-based deep learning method of water gauge measurement for flood monitoring

Real-time and accurate measurement of the water level is a critical step in flood monitoring and management of water resources. In recent years, with the advent of the Internet of Things (IoTs) and cloud computing platforms and resources, the surveillance technology for water monitoring has been revolutionized due to the availability of high-resolution and portable cameras, robust image processing techniques, and cloud-enabled data fusion centers. However, despite the potential advantages of online water level monitoring of the rivers and lakes, some technical challenges need to be addressed before they can be fully utilized. Submersible sensor devices are frequently used for measuring water levels but are prone to damage from sediment deposition and many gauge detection techniques are inefficient at nighttime. In response, this paper presents a novel Internet of Things (IoT) based deep learning methodology that uses Mask-RCNN to accurately segment gauges from images even when there are distortions present. An automated and immediate water stage estimate is provided by this simple, low-cost method. The methodology’s applicability to water resource management systems and flood disaster prevention engineering opens up new possibilities for the deployment of intelligent IoT-based flood monitoring systems in the future.

Novel technique for the ultra-sensitive detection of hazardous contaminants using an innovative sensor integrated with a bioreactor

This study introduces an evaluation methodology tailored for bioreactors, with the aim of assessing the stress experienced by algae due to harmful contaminants released from antifouling (AF) paints. We present an online monitoring system equipped with an ultra-sensitive sensor that conducts non-invasive measurements of algal culture's optical density and physiological stage through chlorophyll fluorescence signals. By coupling the ultra-sensitive sensor with flash-induced chlorophyll fluorescence, we examined the dynamic fluorescence changes in the green microalga Chlamydomonas reinhardtii when exposed to biocides. Over a 24-h observation period, increasing concentrations of biocides led to a decrease in photosynthetic activity. Notably, a substantial reduction in the maximum quantum yield of primary photochemistry (FV/FM) was observed within the first hour of exposure. Subsequently, we detected a partial recovery in FV/FM; however, this recovery remained 50% lower than that of the controls. Integrating the advanced submersible sensor with fluorescence decay kinetics offered a comprehensive perspective on the dynamic alterations in algal cells under the exposure to biocides released from antifouling coatings. The analysis of fluorescence relaxation kinetics revealed a significant shortening of the fast and middle phases, along with an increase in the duration of the slow phase, for the coating with the highest levels of biocides. Combining automated culturing and measuring methods, this approach has demonstrated its effectiveness as an ultrasensitive and non-invasive tool for monitoring the physiology of photosynthetic cultures. This is particularly valuable in the context of studying microalgae and their early responses to various environmental conditions, as well as the potential to develop an AF system with minimal harm to the environment.

Estimating Groundwater Level in Peatlands by Using Submersible Sensor

Peatland fires pose a significant challenge in peatland management, with declining groundwater levels being a contributing factor. Real-time monitoring of groundwater levels (GWL) is essential to address this issue effectively. This study examines GWL data collected from submersible sensors and manual readings in peatlands of Tangkit Baru and Pematang Rahim villages, Jambi Province. Results reveal an increase in GWL in Tangkit Baru coinciding with rising precipitation, while Pematang Rahim experiences a contrasting decrease despite heavy rainfall. Statistical analysis, specifically t-tests, indicates no significant difference (p > 0.05) between the two measurement methods. However, slight discrepancies (0.1-1 cm) between submersible sensor and manual measurements underscore the importance of sensor maintenance for accurate GWL assessment. Keywords: Peatlands, sensors, groundwater level

The Impact of Flocculation on In Situ and Ex Situ Particle Size Measurements by Laser Diffraction

AbstractAccurate particle size distribution (PSD) measurements of suspended particulate matter (SPM) composed of flocs and aggregates are important to improve understanding of ecological and geomorphological processes, and for environmental engineering applications. PSDs can be measured in situ (in the field) using a submersible sensor, or ex situ (in the laboratory) using samples. The methodological choice is often guided by logistical factors, and the differences in PSDs acquired by in situ and ex situ measurements is of concern. In this study, a laser‐diffraction instrument (the LISST‐200X) was used to compare in situ and ex situ PSD measurements. Samples measured ex situ were stored for three consecutive weeks and measured each week in a laboratory using different stirrer speeds. We observed that ex situ measurements display a higher D50 (median particle size) than in situ measurements of the same sample (up to 613% larger, 112% on average). Our experiments show that the difference between in situ and ex situ measurements can be explained by flocculation of the riverine sediments during the first week of storage. During the subsequent ex situ measurements, the stirring results in a significantly lower D50. Ex situ measurements are therefore unsuitable for flocculated SPM. This study provides recommendations for optimizing PSD measurements by calculating the measurement times required to obtain robust PSD measurements (exceeding 3 min per sample), which are larger for field samples with coarser particles and wider PSDs.

In Situ Water Quality Monitoring Using an Optical Multiparameter Sensor Probe

Optical methods such as ultraviolet/visible (UV/Vis) and fluorescence spectroscopy are well-established analytical techniques for in situ water quality monitoring. A broad range of bio-logical and chemical contaminants in different concentration ranges can be detected using these methods. The availability of results in real time allows a quick response to water quality changes. The measuring devices are configured as portable multi-parameter probes. However, their specification and data processing typically cannot be changed by users, or only with difficulties. Therefore, we developed a submersible sensor probe, which combines UV/Vis and fluorescence spectroscopy together with a flexible data processing platform. Due to its modular design in the hardware and software, the sensing system can be modified to the specific application. The dimension of the waterproof enclosure with a diameter of 100 mm permits also its application in groundwater monitoring wells. As a light source for fluorescence spectroscopy, we constructed an LED array that can be equipped with four different LEDs. A miniaturized deuterium–tungsten light source (200–1100 nm) was used for UV/Vis spectroscopy. A miniaturized spectrometer with a spectral range between 225 and 1000 nm permits the detection of complete spectra for both methods.

Concentration and Fluorescence of Chlorophyl a in the Atlantic Sector of Antarctic

The studies were carried out in cruise 79 of the R/V Akademik Mstislav Keldysh. The variability of the chlorophyll a specific light absorption coefficient of phytoplankton and the coefficient of correlation between the fluorescence intensity and chlorophyll a concentration at various optical depths under basic lighting conditions and after dark adaptation was studied. It is shown that in the absence of water stratification, there is no vertical variability in the chlorophyll a specific light absorption coefficient of phytoplankton. It was found that when measuring the intensity of chlorophyll a fluorescence with a submersible sensor, without preliminary dark adaptation, a decrease in the fluorescence intensity signal in the upper layer of water is observed, which is associated with the effect of illumination on the fluorescence quantum yield.

Design Optimization of a Submersible Chemiluminescent Sensor (DISCO) for Improved Quantification of Reactive Oxygen Species (ROS) in Surface Waters.

Reactive oxygen species (ROS) are key drivers of biogeochemical cycling while also exhibiting both positive and negative effects on marine ecosystem health. However, quantification of the ROS superoxide (O2−) within environmental systems is hindered by its short half-life. Recently, the development of the diver-operated submersible chemiluminescent sensor (DISCO), a submersible, handheld instrument, enabled in situ superoxide measurements in real time within shallow coral reef ecosystems. Here, we present a redesigned and improved instrument, DISCO II. Similar to the previous DISCO, DISCO II is a self-contained, submersible sensor, deployable to 30 m depth and capable of measuring reactive intermediate species in real time. DISCO II is smaller, lighter, lower cost, and more robust than its predecessor. Laboratory validation of DISCO II demonstrated an average limit of detection in natural seawater of 133.1 pM and a percent variance of 0.7%, with stable photo multiplier tube (PMT) counts, internal temperature, and flow rates. DISCO II can also be optimized for diverse environmental conditions by adjustment of the PMT supply voltage and integration time. Field tests showed no drift in the data with a percent variance of 3.0%. Wand tip adaptations allow for in situ calibrations and decay rates of superoxide using a chemical source of superoxide (SOTS-1). Overall, DISCO II is a versatile, user-friendly sensor that enables measurements in diverse environments, thereby improving our understanding of the cycling of reactive intermediates, such as ROS, across various marine ecosystems.

Rancang Bangun Sistem Pendeteksi Tsunami (Studi Kasus Selat Sunda)

Tsunami is not only caused by the strength of tectonic earthquakes with the dislocation of the seafloor, but also by landslides /rocks in shallow waters, or the relatively large fall of meteors/ celestial bodies. Unlike other tsunamis caused by slab collisions, tsunamis in the Sunda Strait tsunami caused by high tides and underwater landslides due to the eruption of krakatoa. Tsunami due to the eruption of Mount Anak Krakatau threatens at any time so that technology is needed to be able to help the community and BMKG monitor activities in the Sunda Strait so as to provide security and comfort of the surrounding residents. Therefore, research was made to measure the height of waves to detect high waves causing tsunamis in the Sunda Strait. In this research, Tsunami detection system using electrical circuits in its testing with submersible sensors as a wave height reader. The result of the sensor height readings read by the sensor in the process uses a Resberry-Pi microcontroller. The height limit set on the sensor produces siren sounds and sends short messages sent to residents of coastal communities of the Sunda Strait. The results showed that the tsunami detection system managed to read the water level in real time accurately according to the calibration equation. The water level reading tool set by the limit is 2 meters with the length of the wave using a maximum time of 90 seconds. The device will send a short message and produce a siren sound when the wave reaches a height of 2 meters for 90 seconds in a row. Sending messages takes 2-5 seconds, if there is a tsunami due to the eruption of Mount Anak Krakatau the evacuation time to the safe zone for coastal communities of the Sunda Strait is still affordable and safe.

A new approach to measure gas holdup in industrial flotation Machines. Part III: Industrial prototype design and assessment

• An industrial gas holdup sensor prototype was validated in a 250 m 3 flotation cell at Los Pelambres. • A weakly dependence of sensoŕs discharge coefficient to Reynolds number was observed. • Gas holdup predictions were largely insensitive to errors in the anticipated pulp kinematic viscosity. • Submersible sensor provided robust accurate gas holdup measurement over long periods of time. An industrial gas holdup sensor was designed, constructed, and its performance assessed on a 250 m 3 self-aerated Wemco cell at Los Pelambres concentrator. The submersible sensor comprised a ceramic-liner IP68 magnetic flowmeter assembled to a stainless steel gas exclusion cell, which resembles an inverted truncated cone. The gas exclusion cell was designed to avoid low-velocity sections where particles could settle. When the sensor device is vertically immersed in an aerated pulp a continuous downward flow of pulp without bubbles is induced through it. A remotely installed processing unit converts the flow velocity signal, provided by the magnetic meter, into a gas holdup signal, by applying Bernoullís equation to the induced flow. The ideal velocity in the Bernoullís equation is obtained by multiplying the measured velocity and the discharge coefficient. The discharge coefficient was found to be fairly constant over a wide range of Reynolds numbers. Gas holdup measurements were compared against those obtained by sampling a fixed volume of aerated pulp using the JK Tech Air Holdup Probe. These tests were conducted on different days over nine months to allow for the pulp properties to change. Gas holdup changes in the flotation machine were achieved by restricting the air intake to the cell by placing a stainless steel cap on top of the air suction pipe. Short and long-term testing demonstrated the sensoŕs capability to provide reliable and accurate continuous-time gas holdup measurements for industrial flotation machines.

Sea-trial research on natural product-based antifouling paint applied to different underwater sensor housing materials

Biofouling is a common challenge for underwater sensors, especially for long-term in situ monitoring in marine environments. In this study, we assessed the antifouling efficacy of a paint containing a natural product camptothecin (CPT) on six materials (316 L stainless steel, TC4 titanium alloy, 7075 aluminum alloy, polyoxymethylene, polyvinyl chloride, and Teflon), which are frequently used in the construction of underwater sensor housings. Additionally, a buoy-based sea-trial was performed to test the antifouling performance of the CPT-based paint on housings of three in situ sensors used for practical seawater monitoring applications, namely a spectrophotometer for chemical oxygen demand (COD) measurements and two fluorimeters for biochemical oxygen demand (BOD) and chlorophyll a (Chl a) concentration measurements. The results showed significantly lower macrofouling coverage on the areas painted with the CPT-based paint compared to the unpainted areas for each tested material over 9 months of seawater immersion. The CPT-based paint exhibited different antifouling performance for the different materials; in particular, it exhibited better antifouling performance on the plastic materials compared to the metal materials. Furthermore, when applied on submersible sensor housings in the sea-trial test, the CPT-based paint kept the housings of the COD sensor and the Chl a sensor clean for over 4 months. In addition, the paint prevented fouling of the BOD sensor housing even after 6 months of seawater immersion. Thus, our results suggest that the CPT-based paint could be used as a potential solution to control the biofouling of sensor housings for long-term in situ applications in marine environments.

Underwater Energy Harvesting to Extend Operation Time of Submersible Sensors.

A linear electromagnetic energy harvesting device for underwater applications, fabricated with a simple manufacturing process, was developed to operate with movement frequencies from 0.1 to 0.4 Hz. The generator has two coils, and the effect of the combination of the two coils was investigated. The experimental study has shown that the energy capture system was able to supply energy to several ocean sensors, producing 7.77 mJ per second with wave movements at 0.4 Hz. This study shows that this energy is enough to restore the energy used by the battery or the capacitor and continue supplying energy to the sensors used in the experimental work. For an ocean wave frequency of 0.4 Hz, the generator can supply power to 8 sensors or 48 sensors, depending on the energy consumed and its optimization.

Increasing the efficiency of electric submersible pumps by using big data processing and machine learning technologies

The current coverage of oil wells with telemetry does not allow timely determination of deviations in the operation of about 40% of electric submersible pumps. To solve this problem, a model of virtual sensors has been developed that allows the prediction of temperature and pressure growth at the pump intake in the absence of submersible sensors based on modern big data processing and machine learning technologies. The developed models of virtual sensors are embedded directly into the process control system, which allows notifying the technologists and operators about a possible reduction in the planned average pump operating time and their possible failures for various reasons.

Asymmetric coplanar strip based stepped monopole sensor for liquid permittivity measurements

Investigation of dielectric properties of materials has significant applications in the current scenario. A high sensitive microwave submersible sensor for measuring complex permittivity of liquids over a broad range is presented in this paper. An asymmetric coplanar strip (ACS) fed stepped monopole is employed as the sensing element, and the impedance contrast in the stepped monopole maximizes the sensor’s sensitivity. The sensor is immersed in the liquid sample, and its resonant frequency is exploited to determine the real part of permittivity, and the reflection phase or the radiation efficiency is utilized for the imaginary part of permittivity. Analysis of the sensor, loaded with liquid samples of various dielectric constants and loss tangents, is presented in this paper. The proposed sensor operating at 5.3 GHz under unloaded condition has a maximum numerical sensitivity of 13.7%. The sensor is fabricated and experimentally validated with liquids with dielectric constant ranging from 2–78. The proposed sensor is utilized to measure the glucose concentration in an aqueous glucose solution and the concentration of ethanol blending in petrol.

Personality factors' influence (gender, age, death category) on indicators of biophysical objectification of intra-vital injuries of a putrefactive corpse

Determination of the personality factors influence (gender, age, death category) on the numerical indicators of electrical characteristics during biophysical objectification of soft tissue injuries in a putrefactive corpse. The study was carried out based on Bureau of Forensic Medicine of the Bashkortostan Republic. The instrumental method examined 177 putrefactive corpses; 78 are female and 99 are male. Measurement of electrical characteristics (electrical capacity, electrical resistance) was carried out by an invasive method using a submersible sensor. It was established a significant effect of a person's age, gender and death category on the results of instrumental measurements. These individual characteristics can be recognized as factors that determine the electrical resistance and electrical capacity of biological tissues.

Nutrient Dynamics Buoy (Ndb) Sensor Data and Calibration Report

The Nutrient Dynamics Buoy (NDB) is currently based on a multi-parameter sonde with 7 sensors and includes an integrated Nitrate Sensor and a Phosphate sensor. It also includes a reference PAR1 sensor mounted at the water surface as well as a submersible PAR1 sensor that is immersed at 2m below the water surface together with the mult-parameter sonde, Nitrate sensor and Phosphate sensor.

Experimental Hydration Temperature Increase in Borehole Heat Exchangers during Thermal Response Tests for Geothermal Heat Pump Design

The correct design of a system of borehole heat exchangers (BHEs) is the primary requirement for attaining high performance with geothermal heat pumps. The design procedure is based on a reliable estimate of ground thermal properties, which can be assessed by a Thermal Response Test (TRT). The TRT analysis is usually performed adopting the Infinite Line Source model and is based on a series of assumptions to which the experiment must comply, including stable initial ground temperatures and a constant heat transfer rate during the experiment. The present paper novelty is related to depth distributed temperature measurements in a series of TRT experiments. The approach is based on the use of special submersible sensors able to record their position inside the pipes. The focus is on the early period of BHE installation, when the grout cement filling the BHE is still chemically reacting, thus releasing extra heat. The comprehensive dataset presented here shows how grout hydration can affect the depth profile of the undisturbed ground temperature and how the temperature evolution in time and space can be used for assessing the correct recovery period for starting the TRT experiment and inferring information on grouting defects along the BHE depth.

Comparative Study of Buoy-Actuated Energy-Harvesting Devices for Submersible Sensors

AbstractContinuous electrical power supplies are crucial for the success of deep-sea missions given the need for power to energize sensors, actuators, or light sources to monitor activities in deep...

Adulteration detection in petroleum products using directly loaded coupled‐line‐based metamaterial‐inspired submersible microwave sensor

A modified design topology of planar submersible sensor, to realize the improved sensitivity, using the split ring resonator (SRR) loaded coupled microstrip line is presented. The designed sensor can easily be immersed in the liquid sample under test. The maximum numerical sensitivity of the designed sensor (11.58%) at the design frequency of 6.12 GHz is quite higher than the sensitivity of earlier reported submersible sensor (4.01%). The measured unloaded resonant frequency of the fabricated sensor shows a close match with the corresponding simulated data. The fabricated sensor prototype can distinguish between the test samples having nearly similar dielectric properties due to its improved sensitivity. Two significant aspects of petrochemical industries in the Indian continent, i.e. contamination/blending of petrol with kerosene/ethanol are mainly considered here. As the discrimination between petrol and kerosene using the commonly available microwave sensors is especially quite challenging due to the very similar dielectric behaviour of these two chemicals. The developed prototype can typically measure the minimum 2% level of kerosene adulteration in petrol corresponding to 7.5 MHz shift in the measured resonant frequency. The uncertainty in the measured frequency shift of the liquid samples using the proposed sensor is found to be ∼1 MHz.

Two-magnet energy harvesting device for charging submersable sensors

Monitoring subsea environment requires sophisticated tools such as Autonomous or Remote Underwater Vehicles, submersible sensors, and very skilled manpower. Power is vital to the success of subsea missions especially in deep-waters where visibility is poor and the travel time from the surface to the seabed and vice versa takes a relatively long time. Therefore, renewable energy sources have been tapped into as a solution to continuously provide power to underwater vehicles, actuators, and sensors used/located in deep waters, such as the Gulf of Mexico or the North Sea. Previously, we designed a one-magnet energy harvester installed at the bottom of the sea to generate electricity for small sensors. In order to increase the electrical power production to provide power for a variety of devices, two kinds of energy harvesters (single-magnet and two-magnet) actuated via a buoy are proposed here. The produced voltage is fed to a signal conditioning rectifier to prep it for usage by sensors/actuators. The performance of the two proposed harvesters using the Genetic Algorithms generated parameter is presented for comparison. The simulation results showed that the electrical power generated by the two-magnet energy harvester using periodic wave motion is double that of the single-magnet energy harvester.