Non-contact Measurement System Research Articles

Impact of coating and microstructure on wear resistance of tool steels for wood cutting: a novel approach to quantification and analysis of wear-related damages

Squaring, a wood transformation process, is an operation which consists of introducing the logs into a squaring machine which then uses sharp tools to cut the wood into pieces with high surface quality. Tool steels used in this process experience significant wear, damaging the wood surface and hence leading to substantial scrape rate. This study investigates the wear resistance of three tool steels specifically designed for wood cutting applications: modified AISI A8, modified steels with 0% and 1% tungsten, and powder metallurgy prepared W360 steel. Furthermore, the influence of a PVD coating on the wear resistance of the three alloys was investigated. ASTM G65 abrasive wear tests were conducted using the dry sand/rubber wheel abrasion test. A methodology using a non-contact 3D measurement system and specialized software was developed, allowing for a thorough quantitative assessment of the wear of these steels. The results revealed that the coated A8mod + 1%W steel exhibits the best resistance among the coated steels. Despite the excellent intrinsic resistance of W360 steel, the coating did not provide a significant improvement for this steel, showing only a 10% reduction in wear. Microstructural analysis revealed that the predominant wear mechanisms were abrasion and impact. The relative performance of each steel was quantified and is reported. Field trials conducted under actual cutting conditions, indicate the superiority of W360 steel in terms of resilience to wear and impacts compared to other tested alloys, while confirming the effectiveness of surface treatments in mitigating material wear. However, A8 steel modified with 1% tungsten exhibits increased wear under coating.

Noncontact optical device for measuring blood glucose in aqueous humor: a pilot clinical study investigating correlation with blood glucose levels.

Monitoring blood glucose levels is crucial for individuals with diabetes. Noninvasive methods for measuring serum glucose levels have been explored to aid in blood glucose control for diabetes management. We introduced a noncontact optical glucometer (NCGM) for measuring glucose levels in the aqueous humor of the human eye. We also investigated the correlation between glucose levels in the NCGM and the aqueous humor, blood samples, and self-monitoring blood glucose devices. The optical system used in this study measured both the near-infrared absorption and polarized rotatory distribution of glucose molecules in the human aqueous humor. This prospective study's outcomes were eye aqueous glucose level, preoperative blood glucose level, intraoperative blood glucose level, and NCGM reading of patients in a single center in Taiwan. The NCGM's measurements showed a strong correlation with blood glucose levels (intra-class correlation [ICC]: 0.95 to 0.98) and aqueous humor glucose levels (ICC: 0.76), indicating its ability to noninvasively measure blood glucose levels in human subjects. This NCGM may offer a convenient, pain-free, and rapid tool for measuring blood glucose levels in diabetic patients. The device could represent a significant advancement in noncontact hybrid optical glucose measurement systems.

Elevated-temperature mechanical property and constitutive model of galvanized parallel wire strands

High-temperature conditions lead to severe degradation of the mechanical properties of steel cables. This study conducted uniaxial tensile tests on 19-wire galvanized parallel wire strands (GPWSs) at elevated temperatures. Using a non-contact measurement system, the failure modes under high-temperature conditions were observed, and stress-strain curves were obtained for 12 temperature levels ranging from 20 °C to 700 °C. The yield strength corresponding to a strain level of 1.5% was determined as the nominal yield strength, which ensures both material strength and sufficient safety. By analyzing the stress-strain curves, reduction factors for the proportional limit, elastic modulus, nominal yield strength, and ultimate strength at various temperatures were obtained for the GPWS. Additionally, a Boltzmann curve was used to fit the reduction factors of the mechanical properties of the GPWS. A constitutive model for the entire process of the GPWSs was established through the segmented fitting of the elastic, plastic hardening, and necking stages. High temperatures severely affect the tensile strength of the GPWS. When the temperature reaches 400 °C, the ultimate tensile strength of the GPWS is only about 50% of that at room temperature. At 700 °C, the ultimate tensile strength of the GPWS is reduced to only 2.5%.

Analysis of the Effect of an Open Hole on the Buckling of a Compressed Composite Plate.

This paper investigates the effect of an open hole on the stability of a compressed laminated composite plate. The study was carried out in two ways: using experimental tests and numerical analysis. As a result of the experiment, the buckling form and path of the plate were recorded. The form of buckling was determined using the ARAMIS non-contact measurement system. The critical load value was determined from the working path using the approximation method. The experimental results were verified by numerical analysis based on the finite element method. FEM investigations were carried out in terms of a linear eigenproblem analysis. This allowed the bifurcation load and the corresponding buckling form of the numerical model of the plate to be determined. Investigating the effect of the hole in the compressed plate at a critical state showed high agreement between the proposed test methods. No clear effect of the hole size on the buckling of the plate was observed. In contrast, a clear effect of the hole on the critical load value was determined. The maximum decrease in the critical load value was 14%. The same decrease was observed for the stiffness of the post-critical characteristics. It was shown that the [45|-45|90|0]s composite plate had more than three times lower strength compared to [0|-45|45|90]s and [0|90|0|90]s. The novelty of this article is the development of a research methodology based on new interdisciplinary research methods for describing the influence of the central hole on the stability of compressed composite plates. The ABAQUS system was used for the numerical analysis.

Automatic Detection of Faults in Simulated Race Walking from a Fixed Smartphone Camera

Abstract Automatic fault detection is a major challenge in many sports. In race walking, judges visually detect faults according to the rules. Hence, automatic fault detection systems will help a training of race walking without experts’ visual judgement. Some studies have attempted to use sensors and machine learning to automatically detect faults. However, there are problems associated with sensor attachments and equipment such as a high-speed camera, which conflict with the visual judgement of judges, and the interpretability of the fault detection models. In this study, we proposed an automatic fault detection system for non-contact measurement. We used pose estimation and machine learning models trained based on the judgements of multiple qualified judges to realize fair fault judgement. We verified them using smartphone videos of normal race walking and walking with intentional faults in several athletes including the medalist of the Tokyo Olympics. The results show that the proposed system detected faults with an average accuracy of over 90%. We also revealed that the machine learning model detects faults according to the rules. In addition, the intentional faulty walking movement of the medalist was different from that of other walkers. This finding informs realization of a more general fault detection model.

Optical measurement instrument for detection of powdery mildew and grey mould in protected crops

This study presents an initiative aimed at developing a real-time optical measurement system for non-contact measurement of airborne fungal spores in protected crops such as strawberries, tomatoes, and cucumbers. The system is based on a customized microscope and an automatic system for trapping fungal spores. It has been tested in the field under real conditions, and image processing algorithms have been developed to identify fungal spores in high-resolution microscope images.

A ground reaction force model of speed skating based on non-contact measurement system

Accurate collection and analysis of ground reaction force (GRF) data are crucial for optimizing the technical movements of speed skaters; however, it has been a challenge for the limitations of experimental equipment and application scenarios. Therefore, we proposed a novel approach for estimating GRF based on kinematics obtained from markerless video tracking systems and achieved low errors compared with the experimental data. Our method allows for further biomechanical analysis, including muscle force and power, during speed skating competitions.

Machine learning driven prediction of mechanical properties of rolled aluminum and development of an in-situ quality control method based on electrical resistivity measurement

As a result of the increasing digitization in the context of the fourth industrial revolution in the metal processing industry, the application of the associated possibilities has also entered the field of optimized in-situ material quality testing. In-line monitoring in the production of semi-finished products such as sheet metal in particular will be implemented and optimized to an increasing extent. This study introduces a novel approach that establishes a correlation between the resultant mechanical properties, characterized by stress-strain values and related parameters such as the n-value, with the electrical resistance of aluminum sheets for a rolling process. This correlation is examined under varying rolling schedules and lubrication conditions, utilizing a non-contact measurement system for data acquisition. The four-point method, which was implemented for material testing on a tensile testing machine, can be further transferred to a rolling aggregate for an in-situ quality control step between the passes. Thus, using a black box machine learning approach, conclusions can be drawn about the prevailing mechanical properties as well as the anisotropic behavior by measuring the electrical resistance. Furthermore, a graphical user interface was developed, which generates an optimized rolling schedule for desired mechanical properties. By integrating such a measurement equipment into the rolling process, predictions can be made about the resulting properties and labor-intensive subsequent quality checks as well as scrap can be significantly reduced. In addition, there is the possibility to specify desired mechanical properties for further sheet forming processes, whereupon the optimal rolling process route to achieve them is displayed.

Mechanical properties evaluation of metacarpophalangeal joint prosthesis with new titanium-nickel memory alloy: a cadaver study

ObjectiveNi-Ti memory alloys are unusual materials for hard-tissue replacement because of their unique superelasticity, good biocompatibility, high strength, low specific gravity, low magnetism, wear resistance, corrosion resistance and fatigue resistance. The current study aims to evaluate its mechanical properties and provide biomechanical basis for the clinical application of the prosthesis.MethodsTen adult metacarpophalangeal joint specimens were randomly divided into a prosthesis group (n = 5, underwent metacarpophalangeal joint prosthesis) and a control group (n = 5, underwent sham operation). Firstly, the axial compression strength was tested with BOSE material testing machine to evaluate its biomechanical strength. Secondly, these specimens were tested for strain changes using BOSE material testing machine and GOM non-contact optical strain measurement system to evaluate the stress changes. Thirdly, fatigue test was performed between groups. Lastly, the mechanical wear of the metacarpophalangeal joint prosthesis was tested with ETK5510 material testing machine to study its mechanical properties.ResultsAxial compression stiffness in the prosthesis group was greater than that in the control group in terms of 30 ° and 60 ° flexion positions (P < 0.05). There was no statistically significant difference between two groups with regards to axial compression stiffness and stress change test (P > 0.05). In the fatigue wear test, the mean mass loss in the prosthesis group’s prosthesis was 17.2 mg and 17.619 mm3, respectively. The mean volume wear rate was 0.12%. There was no statistically significant difference in the maximum pull-out force of the metacarpal, phalangeal, and polymer polyethylene pads between the prosthesis group and the control group specimens.ConclusionsNi-Ti memory alloy metacarpophalangeal joint prosthesis conforms to the biomechanical characteristics of metacarpophalangeal joints without implants, and the fatigue strength can fully meet the needs of metacarpophalangeal joint activities after joint replacement.

Effect of rolling on crack behavior of FeCrAl alloys in ultra-long life

PurposeThe purpose of this paper is to determine (1) the relationship between microstructure and fatigue cracking behavior and (2) effect of rolling on the process of crack initiation and propagation in FeCrAl alloys.Design/methodology/approachThe qualitative and quantitative fracture studies were performed using scanning electron microscopy and the non-contact optical measurement system (IFMG5).FindingsThe results show that the formation of facets, rough facets and parallel stripes in the crack initiation and early crack propagation zones are closely related to the sensitivity of crack behavior to the microstructure of the material. Besides, the rolling process has a significant influence on the small crack initiation and propagation behavior. Quantitative analysis demonstrates that the size of the stress intensity factor and plastic zone size in the rough zone is associated with the rolling process.Originality/valueThe findings of this study have the potential to enhance the understanding of the microstructural crack formation mechanisms in FeCrAl alloys and shed light on the impact of rolling on the long-term and ultra-long fatigue behavior of these alloys. This new knowledge is vital for improving manufacturing processes and ensuring the safety and reliability of FeCrAl alloys used in nuclear industry applications.

Experimental Study on the Mechanical Properties and Influencing Factors of Glass Fiber-Reinforced Permeable Concrete.

In order to improve the mechanical properties and deformation characteristics of permeable concrete, glass fiber was added to this type of concrete. Based on an unconfined compressive strength test, non-contact full-field strain measurement system, and scanning electron microscopy test, the effects of aggregate particle composition, shaking time, fly ash content, fiber length, and fiber content on the strength and permeability of permeable concrete were studied. The results show that the strength and water permeability of permeable concrete are negatively correlated with an increase in shaking time. When the aggregate particle size is 5-10 mm, the permeable concrete has both good strength and permeability. Proper incorporation of fly ash improves the compactness inside the structure. The influence of different lengths of glass fiber on the strength of permeable concrete first increases and then decreases, and the permeable property decreases. With the same fiber length, the strength increases first and then decreases with an increase in the content, while the porosity and water permeability coefficient decrease. Under the test conditions, when the length of glass fiber is 6 mm, and the dosage is 2 kg/m3, the strength performance of permeable concrete is the best, and the permeability effect is good at the same time.

Noninvasive blood glucose sensing by secondary speckle pattern artificial intelligence analyses.

Diabetes is a prevalent disease worldwide that can cause severe health problems. Accurate blood glucose detection is crucial for diabetes management, and noninvasive methods can be more convenient and less painful than traditional finger-prick methods. We aim to report a noncontact speckle-based blood glucose measurement system that utilizes artificial intelligence (AI) data processing to improve glucose detection accuracy. The study also explores the influence of an alternating current (AC) induced magnetic field on the sensitivity and selectivity of blood glucose detection. The proposed blood glucose sensor consists of a digital camera, an AC-generated magnetic field source, a laser illuminating the subject's finger, and a computer. A magnetic field is applied to the finger, and a camera records the speckle patterns generated by the laser light reflected from the finger. The acquired video data are preprocessed for machine learning (ML) and deep neural networks (DNNs) to classify blood plasma glucose levels. The standard finger-prick method is used as a reference for blood glucose level classification. The study found that the noncontact speckle-based blood glucose measurement system with AI data processing allows for the detection of blood plasma glucose levels with high accuracy. The ML approach gives better results than the tested DNNs as the proposed data preprocessing is highly selective and efficient. The proposed noncontact blood glucose sensing mechanism utilizing AI data processing and a magnetic field can potentially improve glucose detection accuracy, making it more convenient and less painful for patients. The system also allows for inexpensive blood glucose sensing mechanisms and fast blood glucose screening. The results suggest that noninvasive methods can improve blood glucose detection accuracy, which can have significant implications for diabetes management. Investigations involving representative sampling data, including subjects of different ages, gender, race, and health status, could allow for further improvement.

Elevated-temperature mechanical property and constitutive model of Galfan-coated and full-locked steel cables

Steel cables are an essential stress-bearing member in pre-tensioned steel structures. Their exposure to fire may lead to prestress loss, which may cause structural failure or even overall collapse. This study used a non-contact strain measurement system to investigate the mechanical properties of 1670 MPa Galfan-coated steel cable and 1570 MPa full-locked steel cable at elevated temperatures. The test results showed that the mechanical properties of the two types of cable decayed significantly with the increase in temperature. At 700 °C, the ultimate strength of Galfan-coated steel cable was only 2.36% of that at room temperature, and that of full-locked steel cable was 3.56%. By analyzing the stress-strain relationships between the yielding and hardening stages at 9 test temperature levels, it was found that the high-temperature nominal yield strength could be taken as the stress at the strain level of 1.25% for both types of steel cables. Based on the full stress-strain curves at each temperature level, the calculation formulae for high-temperature reduction factors of elastic modulus, proportional limit, nominal yield strength, and ultimate strength of Galfan-coated and full-locked steel cables were proposed. Besides, the high-temperature constitutive models of the two cable types were also proposed based on the experimental data. The findings of this study can improve the fire safety of pre-tensioned steel structures.

Remote Bio Vision: Perfusion Imaging Based Non-Contact Autonomic Biosignal Measurement Algorithm

Due to the outbreak of new viruses in recent years, the need for contactless medical systems has significantly increased for monitoring, treating, managing, and preventing diseases. Systems are constantly being developed to replace conventional biosignal measuring methods with contactless medical systems. Several systems that substitute attachable sensors in conventional systems have been developed to measure diverse biosignals using images captured with visible cameras. Most non-contact biometric systems have certain limitations, for example, they can only measure a single biosignal, such as the heart rate, oxygen saturation, or blood pressure. They are also easily affected by external factors such as lighting conditions and noises. Furthermore, a blood pressure measuring system based on the pulse transit time requires physical contact and accuracy depends on the measurement location. This study examined a system that provides highly accurate biosignals to overcome these limitations of conventional biosignal measurement systems. This study proposes a biosignal measurement system that uses an infra-red camera to reduce visible light noise. The proposed system uses light sources outside the visible range and measures the amplified reflected light using a near infra-red camera to calculate the heart rate and oxygen saturation. The blood flow value is calculated by the measured heart rate and oxygen saturation. Based on measured data, blood pressure is estimated without contact with the body. We compared the proposed system with an existing non-contact blood pressure measurement system. The proposed system showed an average error rate of 2.07% in blood pressure measurement, which increased by 3.86% compared to the conventional system. Also, this study enabled the early detection of pressure ulcers, which is difficult to measure quantitatively.

A differential miniaturized thickness measurement calibration system based on laser triangulation sensors

Steel plate thickness inspection is important in high-precision steel processing and manufacturing. Traditional inspection methods use manual contact measurement, which has low inspection efficiency and large human error, so we proposed a differential non-contact thickness measurement system based on laser triangulation sensors. Firstly, we designed a differential measurement structure by placing the laser triangulation sensors on the top and bottom of the steel plate to be measured, so that the data from the top and bottom sensors can be sampled and the steel plate thickness can be calculated simultaneously. Secondly, based on the principle of error averaging effect, we proposed a multi-point measurement averaging method to take multiple points on the surface of the steel plate and calculate the average value as the thickness of the steel plate. Further, to improve the measurement system’s long-term stability, the temperature drift is corrected by the polynomial fitting method. Finally, the experiment proves that the repeatability accuracy of our proposed measurement system can reach ±0.5um and the measurement drift is better than ±0.1% of the steel plate thickness.

Noncontact Structural Displacement Measurements Using a Low-Cost Motion Tracking System

Structural health monitoring (SHM) depends on precise displacement measurements to evaluate a structure’s condition. Current measurement systems face challenges such as contact-type restrictions, high costs, uniaxial limitations, and significant computational power requirements. A novel low-cost, non-contact displacement measurement system, called the HTC-VTS (Vive Tracking System), developed by Hongda International Electronics Co., Ltd. (New Taipei City, Taiwan), is proposed. The system setup and data acquisition of the HTC-VTS for SHM involve coordinate transformations to convert six degrees of freedom (DOFs) from raw motion data into 3-DOF structural displacement measurements. The HTC-VTS was experimentally validated using laboratory-scale free vibration tests on a cantilever beam and shaking table tests with actual bridge displacement measurements, demonstrating satisfactory performance in both scenarios. The proposed system expands the potential for cost-effective motion capture systems in both experimental and real-world structural applications.

Spatial-Time Inhomogeneity Due to the Portevin-Le Chatelier Effect Depending on Stiffness

This work is devoted to the study of the influence of the rigidity of the loading system on the kinetics of the initiation and propagation of the Portevin-Le Chatelier (PLC) strain bands due to the jerky flow in Al-Mg alloy. To estimate the influence of the loading system, the original loading attachment, which allows reducing the stiffness in a given range, was used. Registration of displacement and strain fields on the specimen surface was carried out with the Vic-3D non-contacting deformation measurement system based on the Digital Image Correlation (DIC) technique. The mechanical uniaxial tension tests were carried out using samples of Al-Mg alloy at the biaxial servo-hydraulic testing system Instron 8850. As a result of tensile tests, deformation diagrams were obtained for Al-Mg alloy samples tested at different values of stiffness of the loading system: 120 MN/m (nominal value), 50 MN/m, 18 MN/m, and 5 MN/m. All diagrams show discontinuous plastic deformations (the Portevin-Le Chatelier effect). It is noted that a decrease in the rigidity of the loading system leads to a change in the type of jerky flow. At constant parameters of the loading rate, temperature, and chemical composition of the material, the PLC effects of types A, B, and C are recorded in tests.

Fowler-Nordheim tunneling mechanism Graphene/GaN ultraviolet position-sensitive detector with high precision for optoelectronic demodulation applications

As an important component of optical sensors, position-sensitive detector (PSD) plays an important role in non-contact measurement systems and is widely used in many important fields. However, the preparation and application of ultraviolet (UV) PSD are still to be studied. Herein, we propose a high precision UV PSD constructed by graphene (Gr)/GaN heterojunction (active area is 5 ×5 mm2) for the first time, and Fowler-Nordheim tunneling mechanism has been used to improve device performance. Benefiting from the FNT, under a weak light power of 0.06 mW/cm2, the PSD is able to determine the position of the UV light spot through the output photocurrent difference, displays high precision (0.16 μA/mm), excellent weak light detection capability，and good linearity without power supply. Besides, the Gr/GaN show an ultralow threshold voltage (0.132 V) of FNT. When the bias is higher than 0.132 V, photogenerated carriers will tunneling the thin insulation layer by the FNT, resulting in a multiplication of the photocurrent. Therefore, under the same power densities light irradiation (0.06 mW/cm2), the device exhibits an ultrahigh responsivity of 1.88 A/W, a remarkable detectivity of 2.71 × 1013 Jones, and a high LDR of over 99.58 at 0 V bias. More importantly, as an optoelectronic demodulator the device realizes the decoding of optical signals into electrical signals, showing great potential for application in non-contact measurement systems.

Position sensitive detector based non-contact vibration measurement with laser triangulation method utilizing Gabor Transform for noise reduction

Measurement of vibration without having contact with the target is crucial for many applications. However, real time vibration signals are frequently mixed with various levels of dynamic noises. In this research, a non-contact type vibration measurement system based on laser triangulation method is proposed by using a PSD (Position sensitive detector) and here a single axis Brüel and Kjaer piezoelectric accelerometer is used to validate the experimental results. The primary goal of this measurement system is to develop a Gabor Transform based signal denoising technique, in order to eliminate noise from the real-time vibration data. Furthermore, PSD platform vibration, which might cause unanticipated inaccuracies in the detected vibration data, has also been eliminated by utilizing a self-vibration compensation approach using an ADXL-345 three-axis accelerometer. The self-vibration compensated vibration measurement technique has been designed using an NI (national instruments) cRIO (CompactRIO) 9074 real-time FPGA (field programmable gate array) based embedded controller. Consequently, a Gabor Transform and Expansion-based Signal Processing Technique is designed using NI cRIO-9074 real time platform to reduce external noise from the self-vibration compensated vibration data. It has been observed that the implementation of Gabor Transform has improved the performance of the system in term of enhancing the SNR (Signal-to-noise ratio).

Dynamic response characteristics of moraine-soil slopes under the combined action of earthquakes and cryogenic freezing

Freeze-thaw and earthquake are significant factors for the stability and failure of moraine soil slopes in high-altitude cold and strong earthquake area. The cryogenic freezing (CF) and heat thawing (HT) of moraine soil slopes were completed by using a self-designed constant-temperature test chamber, and several shaking table tests under different seismic intensity were carried out. In these tests, the displacement and acceleration responses were recorded by the non-contact measurement system and accelerometers, and the slope dynamic responses were clarified by the displacement, acceleration and energy. The results showed that: (1) the seismic responses of the CF slope are larger than that of the HT slope. (2) The failure process of the CF slope under earthquakes could be summarized into three phases: elastic deformation phase with seismic magnitude <0.4 g, brittle failure phase with seismic magnitude from 0.4 g to 0.8 g, and failure slip phase with seismic magnitude >0.8 g. (3) The failure mode of the HT slope is characterized by the overall collapse of loose moraine soil, and the particle size of the collapsed moraine soil redistributes during the sliding process. The failure mode of CF slope is a frozen block landslide with the soil-ice interface as the sliding surface. (4) The peak acceleration of the input wave, slope surface and elevation have amplification effect on the slope dynamic response, and the top of slope surface is the main deformation and failure area. (5) Reinforcement measures such as soil improvement of slope surface, weight reduction at slope top and backpressure at slope toe, heat pipes are recommended for moraine soil slopes in cold and strong earthquake area. Such findings may provide scientific basis for the damage state identification and seismic reinforcement of moraine soil slopes in alpine and strong earthquake areas.