Experimental Measurement System Research Articles

Lift Force Measurement in Landing Gears Dynamic Tests

Abstract As one of the key components of the aircraft in terms of both operation and safety landing gears are of special interest of the aviation regulations. During the touch down landing gears need to dissipate as much of the energy as possible maintaining the lowest volume and weight as required by the aviation design restrictions. According to the aviation regulations landing gears have to be tested in order to prove the dissipation of the calculated landing energy and to evaluate actual loads acting on the fuselage via the mounting nodes of the landing gears. The tests need to replicate the real landing conditions as closely as possible – including the lift force (or lift) acting on the aircraft during landing. The lift force during landing is not sufficient to maintain the aircraft in flight but acts as the relief force to the aircraft weight resulting in lowering loads applied to the fuselage and decreasing landing energy needed to be dissipated. The lift force or lift has to be taken into account during laboratory tests of landing gears. The lift force needs to be simulated in all of the landing gears dynamic tests: performance optimization, proof of the operation for the certification, and the fatigue evaluation. There are two main methods of applying the lift during the tests: equivalent/effective mass or direct lift application. The latter is used at the Landing Gear Laboratory of the Lukasiewicz Research Network – Institute of Aviation (where author works on daily basis). The lift is applied by the pneumatic cylinders built in the test stand. Until recently the control of the lift force value was performed indirectly by the measurement of the pressure inside the pneumatic system. Recently the experimental direct measurement system using force transducers was introduced in order to directly measure the lift force during every test. In the presented paper, the author gives an overview of the lift force measurement system including its design and the results of the preliminary use evaluation.

Statistical Feature Extraction Combined with Generalized Discriminant Component Analysis Driven SVM for Fault Diagnosis of HVDC GIS

Accurately identifying the types of insulation defects inside a gas-insulated switchgear (GIS) is of great significance for guiding maintenance work as well as ensuring the safe and stable operation of GIS. By building a set of 220 kV high-voltage direct current (HVDC) GIS experiment platforms and manufacturing four different types of insulation defects (including multiple sizes and positions), 180,828 pulse current signals under multiple voltage levels are successfully measured. Then, the apparent discharge quantity and the discharge time, two inherent physical quantities unaffected by the experimental platform and measurement system, are obtained after the pulse current signal is denoised, according to which 70 statistical features are extracted. In this paper, a pattern recognition method based on generalized discriminant component analysis driven support vector machine (SVM) is detailed and the corresponding selection criterion of involved parameters is established. The results show that the newly proposed pattern recognition method greatly improves the recognition accuracy of fault diagnosis in comparison with 36 kinds of state-of-the-art dimensionality reduction algorithms and 44 kinds of state-of-the-art classifiers. This newly proposed method not only solves the difficulty that phase-resolved partial discharge (PRPD) cannot be applied under DC condition but also immensely facilitates the fault diagnosis of HVDC GIS.

Enhanced precision inspection of free-form surface with an improved whale optimization algorithm.

For precision inspection of free-form surface parts using non-contact measurement methods, the registration between the actual measurement model and the ideal design model is necessary.The traditional iterative closure point (ICP) method requires good initial parameters to obtain the global optimal transformation matrix, which is difficult to guarantee in the actual detection process. In order to improve the accuracy and robustness of free-form surface precision inspection, an Improved Whale Optimization Algorithm (IWOA) is proposed in this study.This algorithm can solve the required registration parameters by constantly updating the population. A measurement experimental system is designed to test the accuracy of blade registration. The performance of IWOA is evaluated by the actual measurement experiment, and the results are verified by a comparative study with Whale Optimization Algorithm (WOA), Lévy flight trajectory-based Whale Optimization Algorithm (LWOA), and Adaptive Whale Optimization Algorithm (AWOA). The surface registration errors are 0.1711mm for IWOA, 2.0015 mm for WOA, 1.2656 mm for LWOA, 2.8132 mm for AWOA and 2.1537 mm for ICP. The results show that the accuracy of IWOA is more than 7 times higher than other four algorithms. In general, the experiments indicate that IWOA has a good registration ability and can meet the needs of industrial measurement.

A novel experimental system for the KDK measurement of the 40K decay scheme relevant for rare event searches

Potassium-40 (40K) is a long-lived, naturally occurring radioactive isotope. The decay products are prominent backgrounds for many rare event searches, including those involving NaI-based scintillators. 40K also plays a role in geochronological dating techniques. The branching ratio of the electron capture directly to the ground state of 40Ar has never been measured, which can cause difficulty in interpreting certain results or can lead to lack of precision depending on the field and analysis technique. The KDK (Potassium (K) Decay (DK)) collaboration is measuring this decay. A composite method has a silicon drift detector with an enriched, thermally deposited 40K source inside the Modular Total Absorption Spectrometer. This setup has been characterized in terms of energy calibration, gamma tagging efficiency, live time and false negatives and positives. A complementary, homogeneous, method is also discussed; it employs a KSr2I5:Eu scintillator as source and detector.

Research on Speed Measurement Signal Denoising Processing of Laser Doppler Vibrometer

Speed is an important parameter to reflect the quality of products and equipment, and it plays an important role to monitor and diagnose its operating status by measuring speed. The laser Doppler vibrometer measures the speed with the advantages of non-contact measurement, high sensitivity, small non-linear error and fast dynamic response, and can measure motor speed more accurately. However, the speed data during the measurement process contains a lot of noise, so the measurement data must be denoised. This paper introduces the principle of measuring motor speed with a surface laser Doppler vibrometer, and builts the speed measurement experimental system. The improved wavelet basis denoising threshold algorithm is designed, and the speed measurement data are processed by the improved wavelet basis denoising threshold algorithm and the Kalman filtering algorithm, and the measurement data noise is filtered out, the measurement accuracy is improved. The results show that the average square root value after Kalman filter is closer to the motor rated speed value, the variance is small, the relative error is small, and the denoising effect is better.

F-P interferometer vibration measurement experimental system based on ultra-small grin fiber probe

F-P interferometer vibration measurement experimental system based on ultra-small grin fiber probe

LANDSLIDE-GENERATED TSUNAMIS: A NUMERICAL ANALYSIS OF THE NEAR-FIELD

There are coastal areas which are particularly prone to landslide-generated tsunami risk. The destructive effects caused by the impulsive waves, generated by landslide sources, can be strongly magnified by the characteristics of the so-called "confined geometries" (e.g. bays, reservoirs, lakes, volcanic islands, fjords, etc.). Complicated physical phenomena (e.g. trapping mechanisms, edge waves, wave runup, etc.) take place as a consequence of the interaction between the generated waves and the local bathymetry and control the tsunami propagation and interaction with the coast, often causing devastating consequences. Many past events of landslide-generated tsunamis testify this reality (e.g. Lituya Bay, Alaska, Fritz et al., 2009; Stromboli Island, Italy, Tinti et al., 2005; Anak Krakatau, Indonesia, Grilli et al., 2019). To reduce and mitigate the tsunami risk a proper comprehension, and modelling, of such complicated phenomena is crucial. Landslide-generated tsunamis have been largely studied by exploiting experimental, analytical and numerical modelling. Experimental tests are often time and money consuming, especially if 3D models are considered. Large facilities, as well as complicated experimental configurations and sophisticated measurement systems (e.g. Romano et al. 2016), are often needed. Furthermore, not always it is possible to explore in detail the influence of all the involved parameters, in particular those related to the landslide triggering mechanisms and rheology, that have a considerable influence on the wave characteristics in the so-called "near-field". To this end, numerical modelling can provide a valuable assistance. The new tools offered by the Computational Fluid Dynamics (CFD) methods represent a valuable means for shedding light on the unresolved aspects. In particular, the 3D CFD modelling techniques appear to be crucial as far as the tsunami characteristics in the near-field, induced by landslide sources, are concerned. Indeed, the accurate reproduction of the energy transfer between the landslide and the water is essential to model the tsunami generation and propagation mechanisms, allowing to explore a large variety of landslide triggering mechanisms and rheology. In this paper we present a numerical study of the landslide-generated tsunamis in the near-field.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/liUdiV2qXPg

Three Dimensional Measurement System for the Dynamic Deformation of Aero-engine Blade Profile

In order to solve the technical problem of three-dimensional profile measurement of aero-engine blades with high speed rotation, an optical dynamic measurement system for aero-engine blades was developed. Firstly, the system is calibrated by the algorithm of spatial truncation phase calibration to establish the index between truncation phase and spatial coordinates. During the measurement, the deformation map of the rotating measured blade is obtained by synchronous projection and snapshot. By using the fast Fourier algorithm, the truncation phase is obtained, and then the profile information of blade can be obtained through the truncation phase and spatial coordinate index. Through the design and construction of the blade simulation platform and dynamic measurement experiment system, the three-dimensional profile data of the blade at different rotating speeds are obtained, compared and analyzed, and then the overall profile deformation law is discovered, which verifies the effectiveness and feasibility of the algorithm. The system can obtain the dynamic profile information of the whole blade completely, and provide innovative technical means for blade design verification and performance analysis.

Snow melting on photovoltaic module surface heated with transparent resistive wires embedded in polyvinyl butyral interlayer

This paper presents a novel surface heating system that has been developed to remove snow and icing accumulating on the photovoltaic (PV) module surfaces in snowy regions. The design was created by laminating the transparent resistive wires onto the module surface along with a second-module glass using an interlayer material called polyvinyl butyral (PVB). To minimize energy consumption, the heating wires were placed on the upper and lower halves of the module surface in discrete segments. The objective of this work is to examine the actual performance of the surface heating system and to assess its suitability for snow removal in terms of energy and economy in comparison to the mechanical stripping method. An experimental measurement and recording system has been established to test the snow melting performance at different inclination angles of the design and to investigate its effect on annual energy production. Heated PV modules were placed on the mounting system with inclination angles of 0°, 10°, 20°, 30°, 40°, and 50° together with two standard modules having equivalent properties. Each module in the test system was connected to the grid through a micro-inverter. The electrical energy required for the heating system was provided from the AC grid.The main electrical specifications of the design were measured by utilizing a commercial simulator device before and after lamination and they were used for validation of the efficiency loss. Test results show that the components used in the design led to a reduction of approximately 4.9% in the efficiency of the module. The experimental results obtained under the outdoor conditions show that annual performance loss varies between 5% and 10% depending on the angle of inclination and the differences between modules. In addition, it is observed that the heated module frame makes the fall of snow and the water drainage difficult in all tilt angles and under test conditions. However, when the heating system is used together with high inclined modules, it is demonstrated that energy savings could reach values up to 38% owing to the heating of the module surface piece by piece. Based on economic viability analysis results, it could be concluded that the surface heating method is cost-effective when it is compared to the mechanical stripping method as it only uses electricity that is already available. However, from the financial perspective, it is concluded that the design is inherently expensive in its current form in comparison with a standard module and not financially feasible because it increases the payback time.

Research program of superheavy elements and nuclides based on HIAF

Atomic nuclei are many-body quantum systems composed of protons and neutrons. The nuclides, whose existence is attributed to the nuclear shell effects, are referred to as superheavy nuclides. The exploration of the limit to the existence of nuclides with regard to the proton and mass numbers is at the frontier of nuclear physics research. So far, superheavy elements with an atomic number of up to 118 and hundreds of superheavy nuclides have been experimentally synthesized and identified in various laboratories, resulting in the completion of the seventh period of the periodic table of elements. The High Intensity heavy-ion Accelerator Facility (HIAF) is now under construction and is scheduled to be commissioned in 2025. The study on superheavy elements and nuclei is one of the main research goals of HIAF. Intense heavy-ion beams can be extracted from around the middle point of linac, and the beam energies can be finely adjusted around the Coulomb barriers of nuclear reactions. Therefore, HIAF will provide great opportunities for the synthesis of new superheavy elements and to explore the superheavy island of stability, which was theoretically predicted long ago via fusion and multi-nucleon transfer reactions, respectively. This paper presents the research program of superheavy elements and nuclides based on HIAF, provides an overview of the research on superheavy nuclei, and describes the electromagnetic spectrometers and experimental measurement systems associated with fusion and multi-nucleon transfer reactions. The HIAF physics goals, including the synthesis of new superheavy elements and nuclides, the study on the nuclear structure of superheavy nuclei, the reaction mechanism of producing superheavy nuclides, and the atomic structure and chemical properties of the heaviest elements, are illustrated in detail. Lastly, the future research plan for superheavy elements and nuclides is summarized.

An optimization and test method for ducted fans based on CFD

Some unmanned aircrafts with ducted fan systems are characterized by high efficiency, structural safety and good stability. As a major part of such aircrafts, the ducted fan plays an important role in performance. However, changes in the fan blade structure will influence the fan action. First, from a manufacturing point of view, materials and gate positions were selected. The injection molding process parameters were optimized based on an orthogonal testing analysis method, and this optimization process reduced the warpage by 36.4%. Then, the flow fields of the ducted fans in the theoretical and deformed models were compared and analyzed with SolidWorks computational fluid dynamics (CFD). Finally, the wind velocity values at different distances from the nozzle outlet of the ducted fan were obtained using a wind speed measurement experiment system. The results from the model comparisons showed that fan blade deformation reduced the wind speed by approximately 5%.

Thermodynamic effects of the generation of H*/OH*/CH2O* on flammable gas explosion

To establish the relationship between energy diffusion and intermediate generation during the gas explosion, a mathematical model of the maximum explosion pressure and the free radical concentration was built according to the explosive chain reaction mechanism and the laws of thermodynamics. A 20-L spherical closed explosion experimental system and spectral measurement system were used to collect the pressure and flame emission spectra characteristics during the explosion process of five typical gases (CH4, C2H6, C2H4, CO, and H2). The experimental results verified the reliability of the model by mathematical fitting. And the weight ratio of three free radicals (H*, OH* and CH2O*) to promote maximum explosion pressure was calculated. Results show that the explosion pressure can be linearly expressed by the sum of the concentration of all free radicals containing the same element. As the equivalent ratio increases, the peak of explosion pressure and radical emission intensity rise simultaneously; there is a piecewise linear relationship between them. When the equivalent ratio is less than 1, the promotion of the three free radicals to the maximum explosion pressure is equal; when the equivalent ratio is more than 1, the effect of the three free radicals on the maximum explosion pressure in descending order is H*, CH2O* and OH*. This is significant to the selection of chemical explosion suppression media, which provides a theoretical basis for the prevention and control of gas explosion.

A novel experimental system for measurement of coupled multi-physics-induced surface alteration processes in geomaterials

Despite significant advances in micro-scale measurement techniques for investigations in subsurface energy-bearing geomaterials, they have been unable to incorporate subsurface geomechanical conditions such as in-situ stresses in their applications. To overcome such lacking, we designed a novel high-pressure shear cell capable of measuring chemo-thermo-mechanical behaviour of actual (not synthetic) geomaterials by allowing application of critical stresses while simultaneously being exposed to different fluids.For assessment of the novel setup, a set of measurements for shale surface and micro-structural alteration due to ionic solution under different states of stress (isotropic/anisotropic) were performed. The system generated accurate results showing that surface swelling on shales is not uniform but rather localized and the cause of fluid-induced microstructural alteration is associated with reduction in rock’s shear strength. Such results highlight the importance of performing rock-related measurements under in-situ stresses which paves way for more application areas that can be potentially benefitted through this setup.

Custom vacuum load-lock for the sputtering vacuum chamber, loading/unloading and locking automatisation mechanisms

This paper presents the continuity of my work presented in previous articles regarding my activity as a PhD student at the University of Oradea, Doctoral School of Industrial Engineering. After installing, cleaning, vacuum testing and developing an experimental system for vacuum measurement, we decided that the next best step would be to develop the system with a load-lock further, as the time required for experiments would drastically improve and the need for refurbishing the old positioning mechanism would be eliminated. The paper describes the steps taken, starting with CAD representing the sputtering vacuum chamber for the manufacturer to start their production process, and finalising with automating the whole start/stop and reload sequence for the load-lock with an experimental setup made from readily available equipment in our laboratory, as the initial sequences were manually only and the risk of misusing for non-trained personnel would be high.

Effects of nonlinearity and technical noise on weak-value amplified phase measurement

An exact nonlinear model for pointer shift estimation in phase measurement with weak-value amplification is presented, and the necessary assumptions for the linear approximations are discussed. A realistic experimental weak measurement system with pure imaginary weak-value is demonstrated to verify the nonlinear model, and it is shown that our model is effective over a wide dynamic range. In addition, the influence of several common-type technical noise on the uncertainty of pointer shift estimation in momentum space is analyzed theoretically and verified experimentally, in connection with the relationship between the working condition and the signal-to-noise ratio of the system. This close examination of the impact and ramifications of nonlinearity and technical noise in a realistic experimental phase measurement setting employing weak value amplification provides helpful guidance for its invocation in optical interferometric sensor design.

Experimental and Automatic Measurement System Design of Flatness of Automatic Wallboard Cutting Surface

With the development of the industrialization of buildings, the demand for wallboard is increasing. The development of wallboard automatic production lines can solve the problems of low efficiency and low automation in the production process of wallboard. In the paper, the insufficient of the method that wall panel length detection in JGT169-2016 is considered, the automatic measurement system and cutting surface flatness analysis experiment is designed. Using MATLAB to filter and fit data. Optimize the cutting speed of wallboard based on LJQB-JX-600-QGJ.01 cutting machine. Through experimental analysis, better control parameters are selected for production control, and the quality of production wallboard is further improved, thereby improving the quality of the production line.

Development of a wayside measurement system for the evaluation of wheel-rail lateral contact force

Abstract Considering the safety against derailment, it is essentially that a vehicle respects the force limits imposed by standards. This paper presents an experimental wayside measurement system for the measurement of the wheel-rail lateral contact force. While there are several well-known solutions for the monitoring of the vertical force, the measurement of the lateral one by means wayside systems is rather uncommon because of overlapping effects that are always present with vertical loads. The system, thanks to its particular sensors configuration, is instead able to isolate the strain effects of the vertical force from those of the lateral one. The research is based on laboratory tests, finite element simulations and on field test directly on a railway line in service. Besides, combining the system with another one for monitoring of the vertical force, it has shown the possibility to evaluate the derailment ratio for each train passing over the measurement site.

Thermocapillary Convection Space Experiment on the SJ-10 Recoverable Satellite.

Thermocapillary convection is an important research subject in microgravity fluid physics. The experimental study on surface waves of thermocapillary convection in an annular liquid pool is one of the 19 scientific experimental projects on the SJ-10 recoverable satellite. Presented is a design for a payload for space experimental study on thermocapillary convection that includes the experimental model, measurement system, and control system. The specifics for the construction of an experimental model of an annular liquid pool with variable volume ratios is provided. The fluid temperatures are recorded by six thermocouples with a high sensitivity of 0.05 °C at different points. The temperature distributions on the liquid free surface are captured by means of an infrared thermal camera. The free surface deformation is detected by a displacement sensor with a high accuracy of 1 µm. The experimental process is fully automated. The research is focused on thermocapillary oscillation phenomena on the liquid-free surface and convective pattern transitions through analyses of experimental data and images. This research will be helpful to understand the mechanism of thermocapillary convection and will offer further insights into the nonlinear characteristics, flow instability, and bifurcation transitions of thermocapillary convection.

On the time coupling analysis of explosion pressure and intermediate generation for multiple flammable gases

In this paper, the key product (CH2O) from the explosive chain reaction of methane is selected as the research object, and a method for analysing the coupling mechanism between the explosion pressure and intermediate products is proposed; this method provides a theoretical basis for the construction of an explosion control system with chemical effects. A 20-L spherical closed explosion experimental system and spectral measurement system are used to investigate the pressure and flame emission spectra characteristics of the intermediate products during the mixed explosion process of five typical gases (CH4, C2H6, C2H4, CO, and H2). The time difference (ΔT) between the peak explosion pressure (Pmax) and the peak CH2O spectral intensity is proposed to analyse the coupling relationship between them. On the one hand, the results show that ΔT reflects the effect of the improvement in CH2O generation on explosion intensity; the smaller the ΔT value is, the greater the improvement is. On the other hand, ΔT reflects the main source of CH2O; when the sample concentration is smaller, CH2O is mainly formed during the explosive chain reaction. When the sample concentration is larger, CH2O mainly originates from the bond polymerization of alkylene compounds. The effects of the system conditions (sample concentration, sample composition and methane concentration) on the ΔT and CH2O formation rates are combined, and the correlation between Pmax and ΔT can reflect the coupling mechanism between the explosion pressure and intermediate products. When the oxygen is enriched, ΔT is negatively correlated with Pmax using the power function model, with R2 > 0.95.

The Evolution of Thermal Conductivity and Pore Structure for Coal under Liquid Nitrogen Soaking

An experimental system for liquid nitrogen soaking and real‐time temperature measurement was designed and implemented to investigate the characteristics of temperature field changes in coal under liquid nitrogen soaking. Then, the heat conduction law of the coal in the process of liquid nitrogen soaking and room temperature recovery for dry and water‐saturated coal were examined. The microstructure characteristics of the coal before and after liquid nitrogen soaking were analyzed with nuclear magnetic resonance (NMR) technology. The results showed that, during the liquid nitrogen cold soaking process, the heat transfer law of the dry and water‐saturated coal samples exhibited a notable three‐stage distribution. For the room temperature recovery process, the dry and water‐saturated coal samples exhibited rapid heating characteristics, and the cooling rate gradually decreased to zero. NMR test results indicated that the liquid nitrogen soaking increased the number of micro and small pores in the coal. Thermal stress analysis revealed that the thermal stress generated by the dry coal was larger than that produced by the saturated coal, and the damage was primarily caused by thermal stress. However, the permeability of the saturated coal was better than that of the dry coal. The damage on the saturated coal was caused by the volume expansion of pores and fissures caused by water‐ice phase transition.