Continuous On-line Monitoring Research Articles

Non-contact resistance and capacitance on-line measurement of lubrication oil film in rolling element bearing employing an electric field coupling method

Abstract The lubrication condition of a radially loaded rolling element bearing mainly depends on the continuity of the oil film between friction pairs, which is critical for highly reliable electromechanical systems. To achieve the continuous online monitoring of the lubricating condition of the bearing oil film, a non-contact measuring method for both the oil film capacitance and resistance, which can be used to detect oil deterioration and film damage, is proposed. The method is implemented by measuring the complex impedance of the oil film using two electric field coupling paths instead of slip rings, thus avoiding mechanical contact with the rotating parts directly. This paper provides the equivalent circuit of the lubrication structure in the bearing and the operational principle, algorithm, and circuit implementation of the non-contact measurement. Verification experiments were carried out for a practical rotary mechanical system, obtaining the capacitance in the range of 50–300 pF and the resistance in the range of 50 kΩ–2 MΩ with error less than 15%, which is sufficient for practical on-line lubrication monitoring. The proposed method has a wide range of applications in high-reliability, high-speed, and precise suspension systems.

Online analysis of protein inclusion bodies produced in E. coli by monitoring alterations in scattered and reflected light.

The online monitoring of recombinant protein aggregate inclusion bodies during microbial cultivation is an immense challenge. Measurement of scattered and reflected light offers a versatile and non-invasive measurement technique. Therefore, we investigated two methods to detect the formation of inclusion bodies and monitor their production: (1) online 180° scattered light measurement (λ=625nm) using a sensor platform during cultivation in shake flask and (2) online measurement of the light reflective interference using a porous Si-based optical biosensor (SiPA). It could be shown that 180° scattered light measurement allows monitoring of alterations in the optical properties of Escherichia coli BL21 cells, associated with the formation of inclusion bodies during cultivation. A reproducible linear correlation between the inclusion body concentration of the non-fluorescent protein human leukemia inhibitory factor (hLIF) carrying a thioredoxin tag and the shift ("Δamp") in scattered light signal intensity was observed. This was also observed for the glutathione-S-transferase-tagged green fluorescent protein (GFP-GST). Continuous online monitoring of reflective interference spectra reveals a significant increase in the bacterium refractive index during hLIF production in comparison to a non-induced reference that coincide with the formation of inclusion bodies. These online monitoring techniques could be applied for fast and cost-effective screening of different protein expression systems.

A Measurement Device for Online Monitoring of Total Tar in Gasification Systems

Tars produced during the thermal conversion of coal or especially biomass is one of the major obstacles for the application of gasification systems. They limit the use of the producer gas in engines or turbines or, in further processes like in methanization or conversion to other secondary fuels or chemicals, without further gas cleaning. The determination of the tar content with conventional methods is very time consuming and does not allow continuous online monitoring of the gas quality. One approach to avoid these drawbacks is an automatic system developed at the University of Stuttgart that monitors the tar concentration in the producer gas online and semicontinuous during the gasification process. The technique is based on a flame ionization detector (FID) difference measurement of the hydrocarbons in the producer gas, where the condensable hydrocarbons—the tars—are condensed on a suitable filter material. This work shows the further development of the measurement technique, the choice of a suitable tar filter material for the underlying difference measurement, and a first verification of the system with real producer gas at a 20 kWth bench scale gasifier.

Combining On-Line Characterization Tools with Modern Software Environments for Optimal Operation of Polymerization Processes

This paper discusses the initial steps towards the formulation and implementation of a generic and flexible model centric framework for integrated simulation, estimation, optimization and feedback control of polymerization processes. For the first time it combines the powerful capabilities of the automatic continuous on-line monitoring of polymerization system (ACOMP), with a modern simulation, estimation and optimization software environment towards an integrated scheme for the optimal operation of polymeric processes. An initial validation of the framework was performed for modelling and optimization using literature data, illustrating the flexibility of the method to apply under different systems and conditions. Subsequently, off-line capabilities of the system were fully tested experimentally for model validations, parameter estimation and process optimization using ACOMP data. Experimental results are provided for free radical solution polymerization of methyl methacrylate.

基于Salvo操作系统的远程水位在线监测终端设计

介绍了一种融合GPRS/SMS与以太网混合组网技术的地下水位远程在线监测终端，用于远程双向数据通信；通过引入Salvo操作系统，方便系统功能扩展和裁剪，使终端具有多任务、实时性的特点。对山区地下水位一年的监测数据应用表明，采用Salvo嵌入式操作系统、混合组网和太阳能市电互补供电方式，保证了远程在线监测终端具有可靠性、稳定性的同时，具备了实时性、在线连续监测等特点。 The online water level monitoring terminal used the GPRS/SMS and Ethernet mixed network technology. It can realize bi-directional data communication. By using Salvo operating system, it made it easy for the system to realize the function extension and cutting. It has also improved multi-tasking and real-time ability of the terminal. According to one year data of the mountain area water level, it proved that by adopting the Salvo operating system, mixed network technology and the complementary power supply method of the mains supply and solar power, it made the remote online monitoring terminal more reliable and stable. At the same time, it also improved the real-time ability and the ability of continuous online monitoring of the terminal.

Reporter Gene Assays in Ecotoxicology.

The need for simple and rapid means for evaluating the potential toxic effects of environmental samples has prompted the development of reporter gene assays, based on tester cells (bioreporters) genetically engineered to report on sample toxicity by producing a readily quantifiable signal. Bacteria are especially suitable to serve as bioreporters owing to their fast responses, low cost, convenient preservation, ease of handling, and amenability to genetic manipulations. Various bacterial bioreporters have been introduced for general toxicity and genotoxicity assessment, and the monitoring of endocrine disrupting and dioxin-like compounds has been mostly covered by similarly engineered eukaryotic cells. Some reporter gene assays have been validated, standardized, and accredited, and many others are under constant development. Efforts are aimed at broadening detection spectra, lowering detection thresholds, and combining toxicity identification capabilities with characterization of the toxic effects. Taking advantage of bacterial robustness, attempts are also being made to incorporate bacterial bioreporters into field instrumentation for online continuous monitoring or on-site spot checks. However, key hurdles concerning test validation, cell preservation, and regulatory issues related to the use of genetically modified organisms still remain to be overcome.

Roller bearing acoustic signature extraction by wavelet packet transform, applications in fault detection and size estimation

Continuous online monitoring of rotating machines is necessary to assess real-time health conditions so as to enable early detection of operation problems and thus reduce the possibility of downtime. Rolling element bearings are crucial parts of many machines and there has been an increasing demand to find effective and reliable health monitoring technique and advanced signal processing to detect and diagnose the size and location of incipient defects. Condition monitoring of rolling element bearings, comprises four main stages which are, statistical analysis, fault diagnostics, defect size calculation, and prognostics. In this paper the effect of defect size, operating speed, and loading conditions on statistical parameters of acoustic emission (AE) signals, using design of experiment method (DOE), have been investigated to select the most sensitive parameters for diagnosing incipient faults and defect growth on rolling element bearings. A modified and effective signal processing algorithm is designed to diagnose localized defects on rolling element bearings components under different operating speeds, loadings, and defect sizes. The algorithm is based on optimizing the ratio of Kurtosis and Shannon entropy to obtain the optimal band pass filter utilizing wavelet packet transform (WPT) and envelope detection. Results show the superiority of the developed algorithm and its effectiveness in extracting bearing characteristic frequencies from the raw acoustic emission signals masked by background noise under different operating conditions. To experimentally measure the defect size on rolling element bearings using acoustic emission technique, the proposed method along with spectrum of squared Hilbert transform are performed under different rotating speeds, loading conditions, and defect sizes to measure the time difference between the double AE impulses. Measurement results show the power of the proposed method for experimentally measuring size of different fault shapes using acoustic emission signals.

Preparation of Grignard reagents from magnesium metal under continuous flow conditions and on-line monitoring by NMR spectroscopy

A convenient method for the classical preparation of Grignard reagents from aryl halides and magnesium using a fluidized bed reactor under continuous flow conditions was developed. The process was combined with quenching of the Grignard reagent by CO2 as a model reaction performed using a second flow reactor. The formation and quenching of the reagent was monitored by on-line 1H NMR spectroscopy. The combination of continuous flow operation for Grignard reagents with reaction monitoring by on-line NMR spectroscopy allows one to quickly optimize the working conditions.

Study on surface termination of boron-doped diamond electrodes under anodic polarization in H2SO4 by means of dynamic impedance technique

Anodic oxidation is a popular way to modify termination bonds at boron doped diamond electrodes altering their electrochemical and physicochemical properties. Our studies, performed with dynamic electrochemical impedance spectroscopy technique, supported with X-ray photoelectron spectroscopy and ellipsometry analysis prove its utility in continuous on-line monitoring of impedance changes on the electrode surface under polarization conditions, which may be of great use for the optimization of working conditions of the process. Based on our results, it can be observed that oxidation of termination bonds is a multistep process, each stage initiated at different anodic polarization potential. The factors influencing oxidation of termination bonds are presented and discussed. It was also possible to draw a conclusion about the removal of sp2 carbon impurities from the electrode surface as a precondition to activate the oxidation process. The depth and time of polarization, boron uptake at the grain boundaries, as well as crystallographic orientation of individual grains influence the heterogeneity of the oxidation process. Its partial reversibility was observed as a result of cathodic polarization in the range of hydrogen evolution, however due to irreversible corrosion of sp2 impurities, hydrogenation is not complete. This form of hydrogenation additionally contaminates the electrode surface with sulphur.

Condensed Phase Membrane Introduction Mass Spectrometry with Direct Electron Ionization: On-line Measurement of PAHs in Complex Aqueous Samples.

Polycyclic aromatic hydrocarbons (PAHs) are USEPA regulated priority pollutants. Their low aqueous solubility requires very sensitive analytical methods for their detection, typically involving preconcentration steps. Presented is the first demonstrated ‘proof of concept’ use of condensed phase membrane introduction mass spectrometry (CP-MIMS) coupled with direct liquid electron ionization (DEI) for the direct, on-line measurement of PAHs in aqueous samples. DEI is very well suited for the ionization of PAHs and other nonpolar compounds, and is not significantly influenced by the co-elution of matrix components. Linear calibration data for low ppb levels of aqueous naphthalene, anthracene, and pyrene is demonstrated, with measured detection limits of 4 ppb. Analytical response times (t10%–90% signal rise) ranged from 2.8 min for naphthalene to 4.7 min for pyrene. Both intra- and interday reproducibility has been assessed (<3% and 5% RSD, respectively). Direct measurements of ppb level PAHs spiked in a variety of real, complex environmental sample matrices is examined, including natural waters, sea waters, and a hydrocarbon extraction production waste water sample. For these spiked, complex samples, direct PAH measurement by CP-MIMS-DEI yielded minimal signal suppression from sample matrix effects (81%–104%). We demonstrate the use of this analytical approach to directly monitor real-time changes in aqueous PAH concentrations with potential applications for continuous on-line monitoring strategies and binding/adsorption studies in heterogeneous samples.

Machine learning can classify vital sign alerts as real or artifact in online continuous monitoring data

Alarm hazards continue to be the top patient safety concern of 2015. Machine learning (ML) can be used to classify patterns in monitoring data to differentiate real alerts from artifact.

On the damages detection in aluminium beam using Hilbert-Huang transformation

Purpose– Continuous on-line monitoring of structural integrity are in priority in many engineering fields such as aerospace, automotive, civilian structures, and industrial applications. Of all these possible applications, the aerospace industry has one of the highest payoffs. Possible damage can lead to catastrophic failures and costly inspections. On the other hand, processing a signal consists of important feature from sensors measurements to reach the considered target. Typically, the sensors translate a physical phenomenon from one or many sources in temporal variations or in spatial variations. The purpose of this paper is to investigate damages, in terms of suddenly screw removal or in a small cut, detection in vibrating (clamped-free) aluminum beam structures using the empirical mode decomposition (EMD) method along with the Hilbert-Huang transformation (HHT). The perspective is to identify very small defects in real aircraft structures.Design/methodology/approach– The proposed method deals with a new time-frequency signal processing analysis tool, for damages detection in a vibrating plate. An experimental test ring is used in order to excite a clamped-free aluminum plate. Two types of excitations are used. The first one is a harmonic excitation and the second one is a random excitation provided by an impact hammer. A hole and its filled by a screw with mass of 0.2 g, and a small cut is created, simulating a cut creation, are produced afterword, and the HHT is used in order to arise the developed oscillations, and to reveal hidden reflections in the data and to provide a high-resolution energy-time frequency spectrum.Findings– The major finding was the clear amplitude increment either for screw removal or for cut creation, using the EMD process with the HHT, giving the possibility to detect them.Originality/value– The use of the HHT to detect, using an experimental procedure, two different defects: a suddenly screw removal and a cut creation, in a clamped-free beam, excited by non-stationary and non-linear signals.

Real-Time Prognosis of Crack Growth Evolution Using Sequential Monte Carlo Methods and Statistical Model Parameters

A probabilistic method to monitor and predict fatigue crack propagation is presented in this work. The technique makes use of sequential Monte Carlo sampling combined with the probability density functions of the model parameters. The technique leads to an adaptive dynamic state-space model for crack evolution able to identify the most probable parameters, enhancing the estimation of the residual life of the system. The lifetime predictor presented here could be implemented in advanced maintenance strategies for critical structures employed in civil, industrial, and aerospace fields. The algorithm is first applied to a simulated crack growth, and then to some experimental crack propagations from laboratory tests on helicopter panels. The applicability within on-line continuous monitoring systems is discussed at the end of the paper.

Management of chlorine dosing rates in urban water distribution networks using online continuous monitoring and modeling

The aim of this study is to present the results of a research which was undertaken to manage chlorine dosing rates in a real water distribution network using online continuous monitoring and modeling. The study area was divided into 18 district metered areas (DMAs) where the water pressure and flow rate measurements to each DMA were online and continuous. Besides, online water quality sensors were installed at eight different locations and a bimonthly water quality measurement and sampling program was carried out. The data sets required to set, calibrate and verify the hydraulic and chlorine models were derived from the online continuous monitoring and sampling program. Eight chlorine management scenarios that take into consideration the extreme conditions found out during the online monitoring and sampling were utilized. The study revealed that online monitoring provides excellent data sets for chlorine modeling and management that enables automatic application of chlorine dosing.

Ppb-level QEPAS NO2 sensor by use of electrical modulation cancellation method with a high power blue LED

A novel electrical modulation cancellation method (E-MOCAM) is proposed to suppress the background noise in the case of the excitation light source with a poor beam quality. For its practical implementation, an E-MOCAM based on-beam QEPAS NO2 sensor by use of a commercial high-power wide-stripe LED is developed. The E-MOCAM ultimately suppressed the background noise caused by the stray light by three orders of magnitude. A 1σ detection limit of 1.3ppb (part per billion by volume) was achieved at 1s integration time in this experiment, which corresponds to a normalized noise equivalent absorption coefficient (NNEA) 4.2×10−9Wcm−1Hz−1/2. A 9h continuous on-line monitoring of ambient atmospheric NO2 was carried out on the campus of Shanxi University.

Review of Wetland Ecosystem Services Valuation in China

The wetland ecosystem not only supplies human with the production of ecosystem goods, such as pharmaceuticals, food, but also is one of the foundations of civilization and life support systems. With the in-depth understanding of the wetland ecosystem functions, the research of wetland ecosystem services evaluation has attracted much attention. This study summarizes connotation, classification and assessment methods of wetland ecosystem services. The several commonly used the methods of wetland ecosystem services valuation were chose, including market value, forestation cost, carbon tax, shadow project costs and travel cost. On this basis, the existing problem and the future development of wetland ecosystem service evaluation in China were discussed. Some suggestions were proposed in the future wetland ecosystem valuation and management in China. More attention should be paid to the systematic, integrity evaluation system establishment of wetland ecosystem service. Automatic continuous online monitoring system of wetland should be established, in order to provide more detailed and reliable dynamic data for the evaluation of wetland ecosystem service.

Using copper ions to amplify ROS-mediated fluorescence for continuous online monitoring of extracellular glucose in living rat brain

In this study we developed a facile and sensitive method for continuous monitoring of extracellular glucose concentration in living rat brain through microdialysis (MD) sampling in conjunction with (i) online sample derivatization using glucose oxidase to generate H2O2, which converted a reactive oxygen species-responsive fluorescent dye, 2′,7′-dichlorodihydrofluorescein (DCFH), into fluorescent species, and (ii) a novel non-immobilized enzyme-based fluorescence assay strategy, featuring copper ion (Cu2+)-facilitated amplification of the fluorescence intensity. After evaluating the experimental conditions for glucose oxidation and fluorescence generation, the introduction of Cu2+ ions to this system resulted in an additional 51-fold amplification of the net fluorescence intensity. By sequentially loading brain microdialysate into the dual sample collection loops, the sampling frequency was 7.5h−1. Based on a 40-μL sample volume, the system's detection limit reached as low as 0.18mM, sufficiently accurate to determine the extracellular glucose concentrations in living rat brains. To demonstrate the proposed system's practical performance and applicability, we conducted (i) spike analyses of biomolecule-rich fetal bovine serum sample, confirming that the analytical reliability was similar to that of a commercial glucose kit, and (ii) in vivo dynamic monitoring of the extracellular glucose concentrations in living rat brains after inducing neural depolarization by perfusing a high-K+ medium from the MD probe.

A miniature porous aluminum oxide-based flow-cell for online water quality monitoring using bacterial sensor cells

The use of live bacterial reporters as sensing entities in whole-cell biosensors allows the investigation of the biological effects of a tested sample, as well as the bioavailability of its components. Here we present a proof of concept for a new design for online continuous water monitoring flow-cell biosensor, incorporating recombinant reporter bacteria, engineered to generate an optical signal (fluorescent or bioluminescent) in the presence of the target compound(s). At the heart of the flow-cell is a disposable chip made of porous aluminum oxide (PAO), which retains the sensor microorganisms on its rigid planar surface, while its high porosity allows an undisturbed access both to the sample and to essential nutrients. The ability of the bacterial reporters to detect model toxic chemicals was first demonstrated using a “naked” PAO chip placed on solid agar, and later in a chip encased in a specially designed flow-through configuration which enables continuous on-line monitoring. The applicability of the PAO chip to simultaneous online detection of diverse groups of chemicals was demonstrated by the incorporation of a 6-member sensor array into the flow-through chip. The selective response of the array was also confirmed in spiked municipal wastewater effluents. Sensing activity was retained by the bacteria after 12-weeks storage of freeze-dried biochips, demonstrating the biochip potential as a simple minimal maintenance “plug-in” cartridge. This low-cost and easy to handle PAO-based flow-cell biosensor may serve as a basis for a future platform for water quality monitoring.

Online, continuous monitoring of the sensitivity of the LCST of NIPAM-Am copolymers to discrete and broad composition distributions

The lower critical solution temperature (LCST) of NIPAM/Acrylamide copolymers was monitored during synthesis using second generation ACOMP (automatic continuous online monitoring of polymerization reactions) for a series of discrete starting compositions. A full sweep of NIPAM/Am compositions was subsequently obtained in a semi-batch feed of NIPAM into Am, allowing LCST behavior to be assessed over all compositions of the two copolymers. A separate Simultaneous Multiple Sample Light Scattering (SMSLS) instrument was used to assess compositional polydispersity via the broadening of the LCST temperature transition as compositional heterogeneity of samples increases. This was achieved by combining LCST data as a function of composition and added salt into a master equation. Extended period SMSLS monitoring of the aggregates formed when the LCST is reached showed they are reversible on the short time scale of hours, but are irreversible for homopolymer NIPAM with salt and for copolymers on the scale of days.

Transformer winding deformation diagnostic system using online high frequency signal injection by capacitive coupling

Transformer winding deformation is common among all sorts of transformer failures. Cumulative deformation can eventually burgeon into catastrophic faults and result in entire network outage. It is possible to detect the early signs of faults with continuous online monitoring transformer. However, frequency response analysis (FRA) is considered to be a useful and accurate tool for sufficient detection. This paper aims at proposing a novel diagnostic system for online monitoring power transformer winding deformation based on FRA. In order to realize online monitoring transformer winding, the system uses the capacitive coupling method to inject controllable nanosecond pulses, which function as the excitation signal of winding, and to obtain the response signal. This proposed method may extend frequency range for analysis and perhaps could early detect minor winding movement and looseness. Transformer experiments show great prospect in the application of the system.