Measurement Bench Research Articles

Supercontinuum laser-based gonio-scatterometer for in and out-of-plane spectral BRDF measurements.

The hyperspectral component of bidirectional reflectance measurements, namely from several hundred wavelengths upwards, is attracting growing interest for numerous applications in both optics and computer graphics. In this paper, we present a motorized hyperspectral bidirectional reflectance measurement bench that performs in-plane and out-of-plane measurements for isotropic materials using a supercontinuum laser covering the visible and near infrared range, with a sub-nanometer spectral accuracy. We describe the complete data processing chain, including a method for assessing the alignment error of the measurement bench. From these measurements, we verify the principles of non-negativity, energy conservation and Helmholtz reciprocity. We introduce criteria also to evaluate the validity of the Lambertian hypothesis for the bidirectional reflectance and its deviation from reciprocity, obtained from the measurements directly. We show the need for spectral bidirectional reflectance measurements for certain materials, rejecting the separable function approximation.

Innovative Test Bench for RF and High-Voltage Component Characterization for MRI Applications: A Comprehensive Review

This scientific paper presents a detailed exploration of the electrical characterization of commercially available trimmers, conducted in collaboration with Siemens Medical. The study encompasses the establishment of a specialized measurement bench for impulse mode electrical tests, involving the adaptation of the signal generator with an adjustable supercapacitor and variable inductance. For precise measurements, a carefully designed filtering system prevents voltage overshoots. Given the critical sensitivity of voltage and frequency measurements for passive components in RF and high-voltage applications, the methodology is further refined to achieve optimal compromises across various parameters. The primary objective remains the determination of the voltage across the evaluated capacitor using the proportionality coefficient 𝛼, essential for accurate trimmer characterizations. In this paper, useful insights are provided into the electrical characterization of trimmers, as well as a refined methodology designed for RF and high-voltage applications. The findings presented herein enhance our understanding of trimmer behavior, offering potential implications for improved component selection and performance in a range of electrical systems.

An innovative and low-cost system for in situ and real-time cure monitoring using electrical impedancemetry for thermoset and CFRP laminate

This paper is divided into five sections. The first one introduces the context of our study dealing with the monitoring of the cure of structural composites made of carbon fibers and thermoset matrix (CFRPs). The second one presents a brief state of the art. The third one deals with the materials characterized in this study, and the design and the production of a new bench dedicated to electrical impedance (EI) and thermal measurements. The fourth one compares the results obtained on CFRP and unreinforced matrix samples using conventional differential scanning calorimetry and EI measurements. A conclusion and some prospectives close the paper. In a recent previous work, we studied phases transitions in CFRP during their curing by EI showing that changes in the electrical complex impedance Z can easily be related to those of conventional parameters such as the thermoset matrix degree of cure (DOC) α. This work was carried out using a commercial single-channel impedance analyzer: HIOKI. In addition to its high acquisition cost, this device presented certain limitations in terms of measurement channels (only one) and data acquisition rate (60 s for a frequency sweep). These facts led us to develop a new EI measurement bench for monitoring the impedance changes in CFRP part for aeronautical applications (airframe structures). The innovative new multi-channel (8) bench we designed and manufactured is based on the Digilent PmodIA module (never used previously for this purpose) and an analog-front-end developed for EI measurements. It costs only 15% of the HIOKI analyzer and has a data acquisition rate 48 times higher (1,23 s versus 60 s). All this while maintaining an equivalent impedance measurement range: 100 mΩ to 1 MΩ. The proposed approach makes it possible not only to monitor the DOC α, but also to detect potential cure cycle issues. This latter demonstration was carried out on a new composite material (vacuum-bag oven-cured), NC66/1808NA (supplied by CTMI), which, to our knowledge, had never been characterized in the literature. Compared with preliminary results, similar behavior is obtained on two different CFRPs using two different benches. This clearly underlines the value and quality of the study. Experimental validation of our approach will contribute to CFRP structural health monitoring.

ADC low-complexity modelling identification and mitigation of baseband intermodulation distortion with instantaneous frequency dependence

The linearization of active electronic components such as power amplifier or analog-to-digital-converter (ADC), is a vast subject. Many issues come into play, including behavioural modelling with the selection of a relevant model in terms of accuracy, complexity, identification, and compensation. In this paper we consider an ADC linearization problem, we propose an original low-complexity modelling identification and mitigation of baseband intermodulation distortion with instantaneous frequency dependence. Thus, we introduce a refinement of a power series model by adding a dependence on the variation of the instantaneous frequency of the signal. Based on this, we describe a method suitable for the model calibration using a two-tone signal. We finally present a measurement bench adapted to the calibration of the coefficients of the model, followed by some results of linearization. All the methods presented are intended to be operated in real time in embedded systems and are therefore studied to present very low computational complexities.

Contribution of the solar effect in LEDs and spectral responses

This experimental work describes our work on spectrometric measurements (spectral responses) and measurement of sensitivity of solar radiation by (simulating the solar to a powered lamp) on commercial light emitting diodes of different colors (LEDs). The first experiment was carried out at the electronics department in University of USTHB Bab Ezzouar (Laboratory of thin layers) which has a measurement bench allowing the relative spectral representation of the photo of the detector noted Vphot (λ).

Experimental measurement of thermal conductivity of stereolithography photopolymer resins

The rise in the use of additive manufacturing highlights the importance of knowing the properties of the materials employed in this technology. Therefore, for the commercialization of thermal applications with this technology, heat management is essential. Here, computational modelling is often utilised to simulate heat transfer in various components, and knowing precisely the values of thermal conductivity is one of the key parameters. In this line of research, this paper includes the experimental study of three different types of resin used in additive manufacturing by stereolithography. Based on a test bench designed by researchers from the Public University of Navarre, which measures thermal contact resistances and thermal conductivities, the thermal conductivity analysis of three kinds of resin is carried out. This measuring machine employs the temperature difference between the faces and the heat flux that crosses the studied sample to determine the mentioned parameters. The thermal conductivity results are successful considering the constitution of the material studied and are consistent with the conductivity values for thermal insulating materials. The ELEGOO standard resin stands out among the others due to its low thermal conductivity of 0.366 W/m K.Article HighlightsCalculating thermal conductivity of three resins used in additive manufacturing by stereolithography.Contributing to a knowledge-based design of heat sink in thermal conductivity measurement bench.Improvement of the thermal conductivity measurement bench by reducing the uncertainty for its application in low thermal conductivity materials testing.Graphical abstract

Characterization of surface defects using a phase retrieval technique in a high-power laser system.

In the framework of high-power lasers, surface defects on optics can generate strong light intensification and induce damage sites on downstream optics. To evaluate this intensification during high-energy laser shots, a three-step method is proposed. First, a dedicated measurement bench is designed to measure the intensification induced by defects on a wide variety of optics, including amplifier slabs, KDP crystals, mirrors, gratings, and vacuum windows, for propagation distances up to 2000 mm. A multi-resolution single-beam multiple-intensity reconstruction phase retrieval algorithm is then used to reconstruct a model of the defect, in both amplitude and phase, from a set of intensification measurements. Finally, the impact of the modeled defect on downstream optics is evaluated with a simulation of the high-power laser system. This method is experimentally validated through a case study of damage identified on one of the Laser Mégajoule (LMJ) beams, characterized with the method presented in this paper. The long-distance impact on the LMJ beam is estimated by simulation and compared to a direct near-field measurement.

In Vitro Modeling of Implantable Cardiac Pacemakers Submitted to Conducted Disturbance

The work presented describes the modeling of a measurement bench in the presence of an implantable single-chamber pacemaker in vitro subjected to a conducted disturbance. The source of disturbance is a sinusoidal electrical signal with amplitude of 10 V; the frequency ranges studied correspond to the frequencies of the electrical distribution network (50/60 Hz) and to the frequencies of domestic applications (10/25KHz). The numerical simulations were carried out according to two methods, the first based on the finite element method using the Comsol multiphysics software, the second is based on the impedance method. The results obtained by the two methods are in good agreement, and this will allow us to calculate the voltage induced between the ends of the stimulator. These results allowed us to validate the proposed model.

3D Inductive Frequency Selective Structures Using Additive Manufacturing and Low-Cost Metallization

The use of additive manufacturing and different metallization techniques for prototyping radio frequency components such as antennas and waveguides are rising owing to their high precision and low costs. Over time, additive manufacturing has improved so that its utilization is accepted in satellite payloads and military applications. However, there is no record of the frequency response in the millimeter-wave band for inductive 3D frequency selective structures implemented by different metallization techniques. For this reason, three different prototypes of dielectric 3D frequency selective structures working in the millimeter-wave band are designed, simulated, and manufactured using VAT photopolymerization. These prototypes are subsequently metallized using metallic paint atomization and electroplating. The manufactured prototypes have been carefully selected, considering their design complexity, starting with the simplest, the square aperture, the medium complexity, the woodpile structure, and the most complex, the torus structure. Then, each structure is measured before and after the metallization process using a measurement bench. The metallization used for the measurement is nickel spray flowed by the copper electroplating. For the electroplating, a detailed table showing the total area to be metallized and the current applied is also provided. Finally, the effectiveness of both metallization techniques is compared with the simulations performed using CST Microwave Studio. Results indicate that a shifted and reduced band-pass is obtained in some structures. On the other hand, for very complex structures, as in the torus case, band-pass with lower loss is obtained using copper electroplating, thus allowing the manufacturing of inductive 3D frequency selective structures in the millimeter-wave band at a low cost.

Dataset of Flow-Induced Vibrations on a Pipe Conveying Cold Water

Analysis of flow-induced pipe vibrations has been applied in a variety of applications, such as flowrate inference and leak detection. These applications are based on a functional relationship between the vibration features estimated in the pipe walls and the dynamics related to the flow of the substance. The dataset described in this document is comprised of signals acquired using an accelerometer attached to a pipe conveying cold water at specific flowrate values. Tests were carried out under numerals of the ISO 4064-1/2: 2016 standard and were performed in two measurement benches designed for flowmeter calibration, and a total of 80 flowrate values, from 25 L/h to 20,000 L/h, were considered. For each flowrate value, 3 to 6 samples were taken, so that the resulting dataset has a total of 382 signals that contain acceleration values in three axes and a timestamp in microseconds.

Status of Magnetic Measurement Benches for Insertion Device Characterization at MAX IV Laboratory

Status of Magnetic Measurement Benches for Insertion Device Characterization at MAX IV Laboratory

Boiling heat transfer properties of copper surface with different microstructures

The T-shaped groove surface with groove width of 0.3–1.2 mm and groove depth of 0.6–1.5 mm is prepared on the copper surface by using electric spark wire cutting technology, Set up a set of wall temperature measurement, bubble visualization and steady flow heating test bench. Experimental observations of boiling heat transfer of deionized water on different heat transfer surfaces are achieved. The boiling curves of T-shaped surface such as superheat, heat flux and heat transfer coefficient were plotted. The effect of heat transfer area on the heat transfer performance was investigated, and the bubble growth process was studied by using finite element simulation software. The effect of size on heat transfer performance is explained by experiment and simulation. It is found that the influence of groove width on heat transfer performance is greater than that of groove depth, under the reasonable width of the groove, the larger the depth of the groove, the easier it is to reach the required temperature for the vaporized core generation. The optimal size value of T-shaped grooves in this size range is selected, and the surface of T-grooves at different scales is constructed by laser marking technology. The boiling heat transfer performance of four kings of surfaces including smooth surface and laser scanning surface was studied. Studies have shown, heat transfer effect of multi-scale T surface is always the best,1.31 times of single scale surface,2.38 times of smooth surface and 2.83 times of laser scanning surface. The surface with micro structure can effectively promote boiling heat transfer by wire cutting and laser machining.

Generation of Mesoband Signals With Optoelectronic Technique and a Combiner for Intentional Electromagnetic Interference Conducted Tests

In this article, a source for generating conducted intentional electromagnetic interference with a mesoband spectrum is presented in order to perform electromagnetic susceptibility tests on electronic equipment. This high-voltage source is based on different optoelectronic generators, which integrate photoconductive semiconductor switches (PCSSs) operating in a linear switching mode and triggered by a laser pulse. These optoelectronic devices generate a damped sinusoidal signal with a center frequency between 20 and 200 MHz, a Q factor between 11 and 12.4, and a maximum peak-to-peak magnitude of 3.12 kV for a bias voltage of 4 kV. An optoelectronic generator model was designed using Advance Design System (ADS) software, and experimental tests were performed with a measurement bench to compare simulated and measured results. A study on a voltage increase of these generators has been performed and has established the experimental limits of generation in planar technology with low-cost PCSS available on the shelf. The highest peak-to-peak magnitude value obtained is 6.10 kV, it is possible, thanks to the design and manufacture of a power combiner, with ADS and CST Suite Studio software tools, to set up a multiway combination.

Development of a Cryogenic Test Bench for Spectral MTF Measurement on Midwave Infrared Focal Plane Arrays

The modulation transfer function (MTF) is one of the key figures of merit for the characterization of infrared focal plane arrays (FPA). Moreover, with both the trend of reduced pixel pitch and the variety of pixel structures observed in the industry, the study of the impact of wavelength on the MTF is also of great interest, and thus needs a spectro-spatial measurement. In this paper, we demonstrate such spectral MTF measurements in the mid-wavelength infrared (MWIR) band by the use of several spectral bandpass filters. We realize those measurements at 80 K on a specific n/p 320 × 256 HgCdTe MWIR FPA, divided into different areas. The pixel pitch is the same for all areas (30 μm), the only difference being the fill factor, which differs from one zone to another. The MTF measurement bench is based on a continuously self-imaging grating interferometer integrated in a specific cryogenic set-up.

Utilization of RADFET sensors for x-ray undulators: experiential considerations on magnetic field profile before commissioning

Concerning accelerator-based light sources, electrons are accelerated in conformity with specific time structures (i.e. continuous wave, ‘cw’, or bunched), which arise out of accelerating frequencies of employed radiofrequency cavities. Thus, the concept of transverse emittance of electron bunches comes into prominence, simply defining the area of an ellipse in phase space where the electrons are occupied. In nonideal cases (i.e. in real life), when some fraction of these electrons sneak out of a bunch, the concept of ‘energy spread’ automatically arises. Since the energy spread resulting from off-axis relativistic electrons in an insertion device induces considerable radiation damage on magnetic structures of x-ray undulators, radiation-sensitive field effect transistors (RADFETs) are utilized for quantification of radiation intensity. Hence, it is crucial to bring out their influence on magnetic field profiles before commisioning in tunnels. In this respect, two different types of RADFET sensors were investigated over the magnetic poles of an undulator with 40 mm period length (shortened as an U40 undulator). The effects of the sensors on magnetic field were measured using transverse and longitudinal scans through 6.5 m-long magnetic measurement benches (MMBs). The results of two RADFET standard systems are presented, wherein one contains the magnetic material nickel. Finally, novel magnetic measurement techniques for x-ray undulators via unique MMBs are thoroughly explained as well.

Electromagnetic Time Reversal in the Near Field: Characterization of Transient Disturbances in Power Electronics

In the article, the electromagnetic time reversal technique (EMTR) is studied in the electromagnetic compatibility context. The main issue addressed by this approach is to deal with electromagnetic (EM) radiating source identification. This article is intended to provide a time-domain (TD) study of EMTR in the near field (NF) and prove its efficiency in characterizing transient disturbances in power electronics. The reconstruction of EM emissions is based on two stages. First, the modeling process relies on the use of TD analytical expressions. Second, signal processing is referring to the time reversal technique, which defines an inverse problem resolution. The method proposes to identify a set of equivalent dipoles. The validation is carried out experimentally using a TD measurement bench. The main purposes of this method is to extract the dipoles locations, moments, and orientation. The magnetic field maps calculated at each time step using obtained equivalent sources are compared with measured distributions. Adequate agreement is achieved, which confirms the efficiency of the proposed method. In addition, for validation purposes, the equivalent model is compared with that obtained by a frequency-domain (FD) method based on the standard genetic algorithms. Unlike FD, TD investigations allow characterizing transient disturbances in power electronic systems that emit strong EM interferences, by finding a sufficient equivalent model valid on a wide frequency band at once.

Optoelectronic generation of transient waveforms for UWB radars with rejected frequencies

AbstractIn this paper, a new design of an optoelectronic system for transient waveforms shaping, with a selection of rejected frequencies, is presented. The generation of short pulses is performed with several optoelectronic generators using photoconductive semiconductor switches (PCSS) operating in linear switching mode and triggered via a laser pulse. With the appropriate number of generators, the system generates a spectrum ranging from 300 MHz to 3 GHz, with rejected frequencies at 900 MHz and 1.8 GHz. A PCSS characterization has been set up to determine the necessary parameters for the establishment of an optoelectronic generator model on Keysight Advanced Design System software (ADS). Experimental tests have been realized using measurement benches to compare the simulated and measured signals.

Novel Adaptive Controller for Effective Magnetic Measurement Under Arbitrary Magnetization

In the context of the ever-expanding application of soft magnetic materials, the fully controlled magnetic measurement has, therefore, become essential. It ensures not only the accurate modeling of materials but also the rigorous quality control throughout the manufacturing process, as well as the explicit communication of magnetic data in academic studies or between suppliers and customers. Due to the nonlinearity and hysteresis nature of electrical steels, automatic flux density controller is required for high standard measurements. In this article, we propose a novel steady-state digital control algorithm with two loops, one to regulate the amplitude and the other to correct the waveform of the flux density. Measurement results for various samples tested by Epstein frame and ring specimens under different waveforms, a wide range of frequency and high amplitudes of the flux density have proven the high adaptability, accuracy, and convergence speed of this controller. Its principle is discussed in detail, together with the employed measurement bench.

The use of U3Si2/Al dispersion fuel for high power research reactors

In order to investigate the irradiation performance of U3Si2/Al dispersion fuel at relatively aggressive reactor conditions, compared to how this fuel is typically used in a research or test reactor, post irradiation examination was performed on two fuel plates that were irradiated at ∼270 W/cm2 average surface heat flux and to a maximum local burnup greater than 8 × 1021 fissions/cm3 in the Advanced Test Reactor as part of the RERTR-8 experiment. As part of the non-destructive examinations that were performed on both fuel plates, detailed thickness measurements using a high-fidelity measurement bench were performed on one fuel plate and a segment of the second fuel plate. This paper provides the first reported results of such high-resolution thickness measurements for U3Si2/Al dispersion fuel plates, containing primarily the U3Si2 fuel phase, irradiated at such power levels to high burnup. For destructive examination using optical metallography, samples were generated from both irradiated plates. Localized regions of high swelling (characteristic of internal blistering) were observed on the surface of both fuel plates, suggesting that the performance limits had been reached for each plate. Destructive examinations showed that the fuel particles that are primarily U3Si2, which become amorphous during irradiation, in both plates contained relatively large fission gas bubbles with evidence of fission gas bubble interconnection.

Experimental research of oil pump for a compression-ignition aircraft engine

The paper presents an analysis of the constructions of oil pumps for an aircraft compression ignition engine. It is a two-stroke liquid-cooled engine with a power of 100 kW. The system has 3 cylinders and 6 opposed pistons. The paper estimates the required oil pump capacity to make the engine components well-lubricated. Next, automotive oil pumps for diesel engines are analyzed to select a correct pump for aircraft diesel engine applications. Three pump constructions of different constructions and dimensions of a rotor were selected. A measurement bench was designed and built to test these oil pumps in the range of pump shaft speeds from 0 to 4500 rpm and volumetric flow rate up to 150 l/min. The bench also enables stabilization of oil temperature at the required level within the range from 30 to 120oC. In addition, flow resistance through engine slide bearings was simulated by changing the position of a throttling valve at the pump output to regulate pressure in the range of 0–700 kPa. The obtained capacity characteristics of individual pumps versus on oil pressure and temperature allowed us to find an appropriate oil pump to make individual engine nodes well-lubricated.