On-line Diagnostics Research Articles

Derivation and Tuning of a Compact Differential-Algebraic Equations Model for LiFePO4-Graphite Li-Ion Batteries

This paper presents a procedure for deriving and tuning a compact and solvable differential-algebraic equations (DAE) model for the LiFePO4-graphite battery cell. Electrochemical models of the battery cell are typically represented by complex partial differential equations of state variables and parameters whose relationships can be highly nonlinear. Several software packages are available for numerically solving these equations for simulations. However, their long computing time due to the complexity of the model is a major bottleneck for control and monitoring applications. A reduced order model (ROM) can drastically decrease the simulation time with a minimal loss of the prediction accuracy. A ROM is constructed by simplifying or approximating parameters of the full-order model of the battery cell. For on-line diagnostics and real-time control purposes, a lower-order compact representation of complicated transport and diffusion phenomena of a lithium-ion battery is highly desirable. In this paper, the psedo-2D (P2D) electrochemical model of the battery cell is simplified based on polynomial representations of pore-wall flux and lithium concentrations in a similar manner to previous studies. However, instead of adopting the standard Galerkin method which tends to increase the number of equations, this paper adopts Subramanian et al.’s method which demonstrated a potential for producing a compact description of a lithium-ion battery cell. While a traditional Galerkin method requires selecting particular polynomial representations which satisfy the boundary conditions, Subramanian et al.’s method selects a simple polynomial which can be analytically integrated foregoing setting up separate polynomials for solid and electrolyte potentials. This technique, therefore, has a potential to drastically reduce the size of simplified system. However, since the boundary conditions should be satisfied by additional analytical equations, one requires judicious choice of Galerkin formulations for electrolyte concentration in order to build a solvable DAE system. This paper introduces a systematic way of assessing a Galerkin formulation for the electrolyte concentration based on the theorem of Weierstrass. It is shown that each different Galerkin formulation converts the governing equation and its boundary conditions for the electrolyte concentration into a different set of linear DAE’s. However, not all DAE systems are solvable and some may induce numerical instabilities. It is shown that a full rank of the matrix pencil can ensure that a certain Galerkin formulation produces a solvable DAE system. Usefulness of the proposed method is illustrated by comparing several different Galerkin formulations for the LiFePO4-graphite system. In addition, this paper improves the accuracy of the model by accounting for the hysteresis of open-circuit voltage in LiFePO4 using a differential equation model. When the order of the polynomials are chosen at fours, the P2D model of the cell is simplified into a system of 24 DAE’s. This size is significantly smaller than those of comparable ROMs in the literature. The developed DAE system is solved by using SUNDIAL’s IDA solver where a typical charge/discharge cycle can be simulated under 10 seconds on a regular personal computer. The parameters of the developed DAE model are tuned based on charge/discharge experimental data from a commercial LiFePO4-graphite battery. In this paper, a systematic tuning of the model parameters is investigated by exploiting the fast simulation capability of the developed model. Based on a sensitivity study, six model parameters are chosen for tuning. These tuning parameters, thus selected, include the solid phase diffusivity of the negative electrode, initial hysteresis parameters, reaction rate constants, and the contact resistance. The genetic algorithm is applied to simultaneously find the six model parameters that minimize the sum of squared errors in charge/discharge voltages. The tuned model shows a good agreement with the experimental data at rates upto 4C. Contributions of this paper can be summarized as follows. This paper proposes a new method to ensure a compact DAE system is solvable when it is driven from the original higher-order model of the Lithium-ion battery cell. Moreover, a systematic tuning of the model parameters using the global optimization method is demonstrated by exploiting the computational efficiency of the simplified model. When coupled with the model for describing the hysteresis of the battery cell, the tuned model shows a good agreement with the experimental data from a LiFePO4-graphite battery cell.

Computational study of the bubbling-to-slugging transition in a laboratory-scale fluidized bed

We report results from a computational study of the transition from bubbling to slugging in a laboratory-scale fluidized-bed reactor with Geldart Group B glass particles. For simulating the three-dimensional fluidized-bed hydrodynamics, we employ MFiX, a widely studied multi-phase flow simulation tool, that uses a two-fluid Eulerian-Eulerian approximation of the particle and gas dynamics over a range of gas flows. We also utilize a previously published algorithm to generate bubble statistics that can be correlated with pressure fluctuations to reveal previously unreported details about the stages through which the hydrodynamics progress during the bubbling-to-slugging transition. We expect this new information will lead to improved approaches for on-line reactor diagnostics, as well as new approaches for validating the results of computational fluidized-bed simulations with experimental measurements.

Implantable biomedical sensor array with biocompatible hermetic encapsulation

Abstract. The treatment of metabolic diseases, such as diabetes mellitus, requires sensitive measuring systems. These should be able to detect the different metabolism-related parameters (blood glucose level, pH, pCO2) simultaneously and continuously. A new approach is an implantable wireless sensor microarray consisting of several hydrogel-based piezoresistive sensors that can provide an on-line monitoring of physiological parameters in the human body fluid. The specifically customized stimuli-responsive hydrogels enable the development of reliable biosensors for different analytes. In this regard, the on-line medical diagnostics attracts the main interest. The developed sensor system and its encapsulation should correspond to high requirements on the biocompatibility of implants according to the medical standard DIN EN ISO 10993-5. A multi-layer sensor encapsulation consisting of parylene C and amphiphilic block copolymers was proposed for subcutaneous implants and characterized using contact angle measurements and X-ray photoelectron spectroscopy. In vitro studies with model cells showed no cytotoxicity of the polyethylene glycol-based block copolymers. In order to understand the behavior of implants under physiological conditions, the interaction of the implant surface with biological specimen like proteins is discussed, taking into account the possible protein adsorption on the implant surface due to tissue inflammation around the implant, which should be minimized. Finally, the biocompatibility of the developed sensor system was studied to prove the suitability of the approach.

Spectrally Efficient CSI Acquisition for Power Line Communications: A Bayesian Compressive Sensing Perspective

Power line communication (PLC) techniques present a no extra wire solution for the communication purpose in a smart grid due to the ubiquity and low cost. Moreover, the through-the-grid property of PLC has naturally extended its possible applications, including but not limited to the automatic meter reading, line quality monitoring, online diagnostics, and network tomography. To guarantee the performance of communications as well as other applications in PLC systems, accurate channel state information (CSI) acquisition should be performed regularly. However, the conventional pilot-based CSI acquisition approaches in PLC systems have not made full use of the channel characteristics and hence suffer from a low spectral efficiency. In this paper, by exploiting the parametric sparsity and discretizing the electrical length in the well-known PLC channel model, we formulate the non-sparse (either time domain or frequency domain) PLC channel into a compressive sensing (CS) applicable problem. Furthermore, we propose a spectrally efficient CSI acquisition scheme under the framework of Bayesian CS and extend it to the multiple-input multiple-output PLC by investigating the channel spatial correlation. Compared with the existing sparse CSI acquisition schemes for PLC, such as the annihilating filter-based and the estimating signal parameters via rotational invariance technique-based ones, the proposed scheme has better mean square error performance and noise robustness.

Development of laser noninvasive on-line diagnostics of oncological diseases based on the absorption method in the 4860–4880 cm−1 spectral range

A novel method for noninvasive on-line diagnostics of gastrointestinal oncological diseases using a diode laser in the 4860–4880 cm−1 frequency range is proposed. The method is based on measuring the concentration of 13С during expiration. The accuracy of the method allows performing early diagnostics of diseases.

The perceived quality of interprofessional teamwork in an intensive care unit: A single centre intervention study

ABSTRACTThis article describes a study that evaluated the quality of teamwork in a surgical intensive care unit and assessed whether teamwork could be improved significantly through a tailor-made intervention. The quality of teamwork prior to and after the intervention was assessed using the Interprofessional Practice and Education Quality Scales (IPEQS) using the PROSE online diagnostics and documenting system, which assesses three domains of teamwork: organisational factors, care processes, and team members’ attitudes and beliefs. Furthermore, team members evaluated strengths and weaknesses of the teamwork through open-ended questions. Information gathered by means of the open questions was used to design a tailor-made 12-week intervention consisting of (1) optimising the existing weekly interdisciplinary meetings with collaborative decision-making and clear communication of goal-oriented actions, including the psychosocial aspects of care; and (2) organising and supporting the effective exchange of information over time between all professions involved. It was found that the intervention had a significant impact on organisational factors and care processes related to interprofessional teamwork for the total group and within all subgroups, despite baseline differences between the subgroups in interprofessional teamwork. In conclusion, teamwork, and more particularly the organisational aspects of interprofessional collaboration and processes of care, can be improved by a tailor-made intervention that takes into account the professional needs of healthcare workers.

High Fuel Utilization in Solid Oxide Fuel Cells: Experimental Characterization and Data Analysis with Continuous Wavelet Transform

The on-line diagnostics of Solid Oxide Fuel Cells (SOFCs) is a critical tool to achieve optimal performance and extend the lifetime. The Continuous Wavelet Transform (CWT) methodology was applied to the SOFC voltage signal to detect signatures that reveal the presence of a fault in the cell/stack. The selected fault was anode re-oxidation caused by high Fuel Utilization (FU) (higher then nominal). To experimentally emulate the high FU faults, a standard test procedure was developed, which was used to characterize a μ-CHP system at high FU operation. To complete the analysis, data collected on Single Cells were exploited too. The CWT was applied to the voltage signal for each FU level to verify the qualitative difference (signature) between the signals at different FU's within the same tests as well as the correspondence between the same conditions over different tests. A statistical study was performed to quantify the observed differences and to determine the correspondence between CWT coefficients and operating conditions. The approach proves to be suitable to diagnose high FU in SOFC, showing a successful detection rate above 76%. The results show the good potential of using the CWT methodology as diagnostic tools for SOFCs from cell to stack level.

Enhancement of resonant absorption through excitation of SPR

In this experiment the absorption of the laser radiation impinging on polymeric films with Au nanoparticles implanted in surface was studied. By varying the polarization and the incidence angle of the laser radiation on target, the role in the laser absorption of both excitation of surface plasmons and excitation of electronic plasma waves at critical density through resonant absorption was highlighted. In conditions of p-polarized laser irradiations at 1015W/cm2 intensity, resonant absorption can be induced in films enhancing proton and ion acceleration. Plasma on-line diagnostics is based on SiC detectors. Measurements of kinetic energy of accelerated ions indicate a significant increment using p-polarized laser light with respect to no-polarized light irradiation.

On line diagnostics and self-tuning method for the fluidized bed temperature controller

Abstract The paper presents the method of on-line diagnostics of the bed temperature controller for the fluidized bed boiler. Proposed solution is based on the methods of statistical process control. Detected decrease of the bed temperature control quality is used to activate the controller self-tuning procedure. The algorithm that provides optimal tuning of the bed temperature controller is also proposed. The results of experimental verification of the presented method is attached. Experimental studies were carried out using the 2 MW bubbling fluidized bed boiler.

Study of oxygen effect on the melting pool temperature during selective laser melting

The on-line optical diagnostics studies of selective laser melting are difficult to accomplish due to the need of closed chamber of inert gas protective atmosphere. In this term, this study was initiated to make evidence of oxygen influence on the signal from the melt pool. The results make clear the temperature growth with presence of oxygen and its effect on the metallurgical contact of the single-track to the substrate. It was shown that for both used materials, the oxidation leads to an overheating but the metallographic quality differs. The experiments highlighted that the optical diagnostic means such as IR thermography camera is suitable but not sufficient solution for process control and it needs adequate evaluation. Using the track width as an approximation of the melt pool width at melting point, it was possible with some assumptions to restore the true temperature of the studied zone.

Effect of superimposed impulses on AC partial discharge characteristics of oil-impregnated paper

The effect of HV impulses on surface and cavity partial discharges (PD) of oil-impregnated paper (OIP) is investigated in this work, by subjecting specimens to impulse voltages superimposed on a continuous AC voltage. The superposition of transient and AC voltage is relevant to insulation systems in power-system equipment, which is exposed to transients such as lightning and switching impulses during its operation. For several different PD-generating defects in oil-impregnated paper, the PD behaviors before and after the impulse are compared. The influence of moisture content is studied by using OIP with moisture content <0.5%, 3.0% and 5.5%. The results show a distinctive behavior of PD due to the impulse for each defect and insulation condition, either by change in the PD rate and magnitude or by causing PD inception or extinction. Recordings of the voltage signals and associated PD measurements during and after the incidence of a high voltage transient are of potential use for condition assessment of the insulation of power transformers and their bushings, as a form of online diagnostics.

A Method for Online Diagnostics of Electromagnetic Relays Against Contact Welding for Safety Critical Applications

In a nuclear power plant, electromagnetic (EM) relays are often used to communicate TRIP signal configured in fail-safe mode. Online diagnostics is an important part of fault tolerant design. Relay contact welding is a failure mode of concern. Current methods do not allow for reliable online diagnostics of this failure mode without actually opening/closing the relays or without making measurements at contact side. In this paper, a technique for online diagnostics of EM relay without affecting the contact status is proposed. The method uses the differences in characteristic decay of coil current during deenergization process between a healthy and a relay whose contacts got welded. A test circuit is designed to verify the concept of deenergizing, followed by quick reenergization of relay coil. Diagnostic information is extracted, and the method is amenable for online automated execution. Results are satisfactory, and a welded contact is successfully detected and indicated by the circuitry. Reliability improvement achieved by deploying the proposed method is highlighted.

Ambient intelligence for optimal manufacturing and energy efficiency

Purpose – This paper aims to describe the creation of innovative and intelligent systems to optimise energy efficiency in manufacturing. The systems monitor energy consumption using ambient intelligence (AmI) and knowledge management (KM) technologies. Together they create a decision support system as an innovative add-on to currently used energy management systems. Design/methodology/approach – Energy consumption data (ECD) are processed within a service-oriented architecture-based platform. The platform provides condition-based energy consumption warning, online diagnostics of energy-related problems, support to manufacturing process lines installation and ramp-up phase and continuous improvement/optimisation of energy efficiency. The systems monitor energy consumption using AmI and KM technologies. Together they create a decision support system as an innovative add-on to currently used energy management systems. Findings – The systems produce an improvement in energy efficiency in manufacturing small- and medium-sized enterprises (SMEs). The systems provide more comprehensive information about energy use and some knowledge-based support. Research limitations/implications – Prototype systems were trialled in a manufacturing company that produces mooring chains for the offshore oil and gas industry, an energy intensive manufacturing operation. The paper describes a case study involving energy-intensive processes that addressed different manufacturing concepts and involved the manufacture of mooring chains for offshore platforms. The system was developed to support online detection of energy efficiency problems. Practical implications – Energy efficiency can be optimised in assembly and manufacturing processes. The systems produce an improvement in energy efficiency in manufacturing SMEs. The systems provide more comprehensive information about energy use and some knowledge-based support. Social implications – This research addresses two of the most critical problems in energy management in industrial production technologies: how to efficiently and promptly acquire and provide information online for optimising energy consumption and how to effectively use such knowledge to support decision making. Originality/value – This research was inspired by the need for industry to have effective tools for energy efficiency, and that opportunities for industry to take up energy efficiency measures are mostly not carried out. The research combined AmI and KM technologies and involved new uses of sensors, including wireless intelligent sensor networks, to measure environment parameters and conditions as well as to process performance and behaviour aspects, such as material flow using smart tags in highly flexible manufacturing or temperature distribution over machines. The information obtained could be correlated with standard ECD to monitor energy efficiency and identify problems. The new approach can provide effective ways to collect more information to give a new insight into energy consumption within a manufacturing system.

A Linear Identification of Diode Models from Single $I$– $V$ Characteristics of PV Panels

This paper presents a novel approach on diode model parameter identification from the I- V characteristics of photovoltaic panels. Other than the prevailing methodology of solving a group of nonlinear equations from a few points on the I-V curve, the proposed methodology views the diode model as the equivalent output of a dynamic system. From this new viewpoint, diode model parameters are linked to the transfer function (after Laplace transform) of the same dynamic system whose parameters are then identified by a simple integral-based linear square. The indoor flash test shows the accuracy and effectiveness of the proposed method, and outdoor module testing shows its ability of online monitoring and diagnostics. Comparisons to the methods of Lambert W function and evolution algorithms are also included.

Ion acceleration from intense laser-generated plasma: methods, diagnostics and possible applications

Abstract Many parameters of non-equilibrium plasma generated by high intensity and fast lasers depend on the pulse intensity and the laser wavelength. In conditions favourable for the target normal sheath acceleration (TNSA) regime the ion acceleration from the rear side of the target can be enhanced by increasing the thin foil absorbance through the use of nanoparticles and nanostructures promoting the surface plasmon resonance effect. In conditions favourable for the backward plasma acceleration (BPA) regime, when thick targets are used, a special role is played by the laser focal position with respect to the target surface, a proper choice of which may result in induced self-focusing effects and non-linear acceleration enhancement. SiC detectors employed in the time-of-flight (TOF) configuration and a Thomson parabola spectrometer permit on-line diagnostics of the ion streams emitted at high kinetic energies. The target composition and geometry, apart from the laser parameters and to the irradiation conditions, allow further control of the plasma characteristics and can be varied by using advanced targets to reach the maximum ion acceleration. Measurements using advanced targets with enhanced the laser absorption effect in thin films are presented. Applications of accelerated ions in the field of ion source, hadrontherapy and nuclear physics are discussed.

On-line fault diagnostics in operating three-phase induction motors by the active and reactive currents

Motor current stator analysis (MCSA) are usually used to detect the broken bars. In several industrial applications, like cement industry, the motor is subjected to load torque variations of low frequencies, which have effects similar to rotor faults in the current spectrum and result of diagnostic procedure may be ambigues. In this paper, we present a study based on the application of the instantaneous active and reactive courant signature analyses for discriminating broken rotor bars from mechanical load oscillation effects in operating three-phase squirrel cage induction motors. This method is attractive because it does not need to interrupt the operating system in its application and allows the user to “see” the diagnosis information in the same way as in the well-known MCSA, i.e., as sidebands next to the fundamental current component. This technique has been first tested through the simulation of induction motors using a mathematical model based on the modified winding-function approach (MWFA). Then, experimental results are presented in order to demonstrate the capability of the proposed tool for discriminating between a motor with broken rotor bars from a motor driven by an oscillating load.

Proton Recoil Telescope Based on Diamond Detectors for the Measurement of Fusion Neutrons

Diamonds are very promising candidates for the neutron diagnostics in harsh environments such as fusion reactor. In the first place this is because of their radiation hardness, exceeding that of Silicon by an order of magnitude. Also, in comparison to the standard on-line neutron diagnostics (fission chambers, silicon based detectors, scintillators), diamonds are less sensitive to $\gamma$ rays, which represent a huge background in fusion devices. Finally, their low leakage current at high temperature suppresses the detector intrinsic noise. In this talk a CVD diamond based detector has been proposed for the measurement of the 14 MeV neutrons from D-T fusion reaction. The detector was arranged in a proton recoil telescope configuration, featuring a plastic converter in front of the sensitive volume in order to induce the (n,p) reaction. The segmentation of the sensitive volume, achieved by using two crystals, allowed to perform measurements in coincidence, which suppressed the neutron elastic scattering background. A preliminary prototype was assembled and tested at FNG (Frascati Neutron Generator, ENEA), showing promising results regarding efficiency and energy resolution.

A system of online diagnostics of the technical condition of wind power plants

The main issues of monitoring the technical condition of the electromechanical part of wind power plants in accordance with the concept of SMART GRID local networks are discussed. The creation of an integrated system of online diagnostics of the technical condition of wind power plants for autonomous energy sources is proposed. A mathematical approach to diagnostics of the technical condition of the electromechanical part permitting one to combine monitoring capability and control in a single facility is developed.

A model of impeller whirl for baffled mixing vessels

A model of impeller whirl that provides stability limits and mean square radial deflections for industrial mixing vessels is introduced. The model has a linear form and includes contributions to the mass, damping, and stiffness that arise from fluid forces acting on the impeller. The fluid forces were derived from Large Eddy Simulation (LES) of a mixer with a pitched blade impeller rotating at speed N, and undergoing prescribed circular orbits of frequency Ω. Simulations were performed for Reynolds numbers, 10≤Re≤10000, and subsynchronous whirl frequency ratios, −1≤Ω/2πN≤1. Model predictions of impeller whirl instability and mean square vibration amplitude were compared to experimental data from a laboratory scale mixer. The simplicity and economy of the new model allows its use in on-line diagnostics and operational planning.

Laser irradiations of advanced targets promoting absorption resonance for ion acceleration in TNSA regime

Advanced targets based on Au nanoparticles embedded in polymers films show high absorption coefficient in the UV–visible and infrared region. They can be employed to enhance the proton and ion acceleration from the laser-generated plasma in TNSA regime. In conditions of “p” polarized laser irradiations at 1015W/cm2 intensity, in these films can be induced resonant absorption due to plasma wave excitation. Plasma on-line diagnostics is based on SiC detectors, Thomson spectrometry and X-ray streak camera imaging. Measurements of kinetic energy of accelerated ions indicate a significant increment using polymer targets containing gold nanoparticles and “p” polarized laser light with respect to pure polymers and unpolarized light irradiation.