Non-destructive Measurement Technique Research Articles

The impact of thickness heterogeneity on soft tissue biomechanics: a novel measurement technique and a demonstration on heart valve tissue.

The mechanical properties of soft tissues are driven by their complex, heterogeneous composition and structure. Interestingly, studies of soft tissue biomechanics often ignore spatial heterogeneity. In our work, we are therefore interested in exploring the impact of tissue heterogeneity on the mechanical properties of soft tissues. Therein, we specifically focus on soft tissue heterogeneity arising from spatially varying thickness. To this end, our first goal is to develop a non-destructive measurement technique that has a high spatial resolution, provides continuous thickness maps, and is fast. Our secondary goal is to demonstrate that including spatial variation in thickness is important to the accuracy of biomechanical analyses. To this end, we use mitral valve leaflet tissue as our model system. To attain our first goal, we identify a soft tissue-specific contrast protocol that enables thickness measurements using a Keyence profilometer. We also show that this protocol does not affect our tissues' mechanical properties. To attain our second goal, we conduct virtual biaxial, bending, and buckling tests on our model tissue both ignoring and considering spatial variation in thickness. Thereby, we show that the assumption of average, homogeneous thickness distributions significantly alters the results of biomechanical analyses when compared to including true, spatially varying thickness distributions. In conclusion, our work provides a novel measurement technique that can capture continuous thickness maps non-invasively, at high resolution, and in a short time. Our work also demonstrates the importance of including heterogeneous thickness in biomechanical analyses of soft tissues.

The calculation of light element impurity ([formula omitted], n) yield curves in a PuO[formula omitted] matrix and associated specific yield coefficients: Influence of the reaction cross sections

Most of the Pu separated from irradiated commercial nuclear fuel is stored as PuO 2. The primary quantitative nondestructive measurement technique used to verify the amount of Pu in storage containers is passive neutron correlation counting. An important physical property of the oxide material is the ratio, α, of the rate of (α, n) neutrons produced inside the item to the rate of neutrons produced by spontaneous fission. This ratio influences the precision of the correlated counting method and affects the interpretation of the data because of how it changes both the primary total neutron production rate and the rate of induced fission events taking place inside the item. In addition to the main O(α, n) contribution, additional contributions come from α-particle interactions with light element impurities that are inevitably present. In this work, we calculate specific (α, n) yield coefficients, expressed in units of neutrons per second per gram of α-emitting nuclide per part per million by mass of the specified impurity element distributed in a pure PuO 2 matrix, for some key α-emitting actinides commonly present in reprocessed Pu (238–242Pu+241Am). These coefficients are directly applicable to nuclear safeguards verification work in which the α ratio is often calculated from the Pu-isotopic composition and chemical information obtained by other means. They also provide a convenient up-to-date reference set against which values generated by other methods can be compared. Results are presented for impurities with atomic number from 3 to 17 inclusive, plus K and Fe. In most cases, these coefficients are not expected to change by more than 5%–10% at any time in the future. However, as new data become available, changes as large as 20% may be needed for some targets (e.g., F). The present yield calculations are limited by the general shortage of quality experimental total (α, n) reaction cross section data, which, together with unexplained variation between determinations, means that an objective and coherent evaluation is not possible. The situation is even less satisfactory for the partial differential cross section needed to calculate neutron spectra.

Evaluación de métodos de medición destructivos y no destructivos para determinar el espesor de un recubrimiento de titanio depositado por evaporación física

The purpose of this research is to develop reference Ti-coatings and analyze the thicknesses evaluated via destructive (DT) and non-destructive (NDT) measurement techniques. The Ti coating was deposited on a mirror finished AISI M2 steel by the magnetron process. The nominal value of the coating thickness was 1 μm. The NDT was the X-Ray Fluorescence (XRF) method, the thickness for the portable analyzer was 1.18 ± 0.19 μm and the thickness using the spectrometer XRF was 1.17 ± 0.24 μm. For DT, thickness measurements were carried out in the cross-sections of the Ti-coatings, using the Field Emission - Scanning Electron Microscopy equipped with Energy Dispersive Spectrometer (FE-SEM-EDS). The coating thickness measurements were performed with image analysis of secondary electrons (SE), backscattering electrons (BSC), mapping (MAP) and elemental profiles (LS) using ImageJ and Aztec software. The results of the thickness measurements are SE: 1.12 ± 0.15 μm, BSC: 1.14 ± 0.13 μm, LS: 1.25 ± 0.13 μm and MAP: 1.29 ± 0.6 μm. Variations in the results were identified and estimated in the uncertainty models proposed for each method.

In situ laser-ultrasonic monitoring of elastic parameters during natural aging in an Al-Zn-Mg-Cu alloy (AA7075) sheet

Solution heat treatment increases the formability of 7xxx series aluminum alloys by dissolution of nanoscale hardening phases. However, subsequent natural aging at room temperature partly reverses this process within a few hours, posing a logistical challenge to industrial operations as formability decreases and springback increases. Hence, non-destructive monitoring of mechanical properties may help facilitate forming of parts from 7xxx series alloys, but no suitable non-destructive direct measurement technique has been established so far. Here we demonstrate an in situ laser ultrasonic method based on the generation and detection of plate resonances to continuously monitor small changes (<1%) of Young’s modulus, shear modulus, and Poisson’s ratio during natural aging of an age-hardenable aluminum alloy (AA7075) sheet. Additionally, we followed plastic mechanical properties by tensile testing and we intermittently measured electrical conductivity and performed differential scanning calorimetry to assess precipitation during natural aging. We find qualitative correlation between Guinier-Preston zone formation and an increase in elastic moduli and material strength.

Evaluation of compactness as a method to quantitatively assess Chinese cabbage texture

Quality evaluation during growth and processing is quite important for the acceptability of Chinese cabbage. As destructive measurements of puncture firmness were not widely available on spherical leafy vegetables, the compactness index was utilized to determine the texture of Chinese cabbage using self-made apparatus, and the test parameters were optimized by L9(34) orthogonal design test. The experimental validation of novel compactness and conventional puncture approaches was conducted on 60 samples every 3 d for 16 d in storage. Mechanical vibration methods, artificial sensory evaluation, and discriminant analysis were employed for further comparative analysis of the adaptability of the compactness index. Results showed that the compactness measurement system could achieve superior performance when the width of the fiberglass belt, diameter change rate, and loading rate were 0.030 m, 15 %, and 10 mm min−1, respectively. Both compactness and firmness were independent of shape and mass, while compactness values correlated well with density and vibration parameters. Compactness also closely reflects the overall structure and texture. Results of repeatability, sensitivity, and sensory evaluation were consistent with these findings. The total discriminant accuracies of firmness and compactness were 53.3 % and 73.3 %, respectively. The proposed approach provided a non-destructive technique for the quantitative texture measurement of Chinese cabbage.

A Gaussian processes-based approach for damage detection of concrete structure using temperature-induced strain

Concrete structures in cold regions are highly susceptible to internal cracks due to the periodic variation of temperature and the alternation of drying and wetting in the long term. Conventional damage detecting techniques for concrete are often destructive and need tedious manual operation. Concrete strain monitoring is a non-destructive measurement technique, which provides continuously streaming strain data and has the potential of detecting damage automatically based on a data-driven approach. Temperature-induced strains are highly responsive to damage to concrete structures under the freeze-thaw (F-T) cycles. In this regard, we propose a novel damage detection approach based on temperature-induced strains. The proposed method separates the temperature-induced component from the measured data based on the independent component analysis, which improves the modeling accuracy of the Gaussian processes modeling (GPM) approach for detecting damage. The principle of damage detection is extracting the features related to the damage from the measured strain data. The model residuals of temperature-induced strains are extracted as features that are sensitive to concrete damage. A novel damage index is established to determine the presence of structural damage based on the Kolmogorov Smirnov (KS) test, which estimates the probability distribution of residuals. To increase the reliability of damage detection and decrease the pseudo fault alarm rate, the general extreme value (GEV) theory is considered to determine a reliable threshold limit. A moving window strategy is introduced to perform damage detection and identify the damage occurrence time effectively. Monitoring data of the F-T cycle experiment are utilized to validate the proposed method. The results of three different damage cases demonstrate the effectiveness of the proposed data-driven method in terms of detecting the damage and identifying the damage occurrence time. The variation rules of the concrete temperature characteristics are revealed through the damage detection results under F-T cycles.

Sensors and Instruments for Brix Measurement: A Review.

Quality assessment of fruits, vegetables, or beverages involves classifying the products according to the quality traits such as, appearance, texture, flavor, sugar content. The measurement of sugar content, or Brix, as it is commonly known, is an essential part of the quality analysis of the agricultural products and alcoholic beverages. The Brix monitoring of fruit and vegetables by destructive methods includes sensory assessment involving sensory panels, instruments such as refractometer, hydrometer, and liquid chromatography. However, these techniques are manual, time-consuming, and most importantly, the fruits or vegetables are damaged during testing. On the other hand, the traditional sample-based methods involve manual sample collection of the liquid from the tank in fruit/vegetable juice making and in wineries or breweries. Labour ineffectiveness can be a significant drawback of such methods. This review presents recent developments in different destructive and nondestructive Brix measurement techniques focused on fruits, vegetables, and beverages. It is concluded that while there exist a variety of methods and instruments for Brix measurement, traits such as promptness and low cost of analysis, minimal sample preparation, and environmental friendliness are still among the prime requirements of the industry.

A Low-Cost Metamaterial Sensor Based on DS-CSRR for Material Characterization Applications.

This paper presents a metamaterial sensor using a double slit complementary square ring resonator (DS-CSRR) that has been utilized for the measurement of dielectric materials, especially coal powder. The design is optimized for best performance of deep notch depth in transmission coefficient (Magnitude of S). Sensitivity analysis of transmission coefficient with respect to structure dimensions has been carried out. Metamaterial properties of double negative permitivity and permeability were extracted from the S–parameters of this sensor. The optimized structure is fabricated using low cost FR-4 PCB board. Measured result shows resonance frequency of 4.75 GHz with a deep notch up to −41 dB. Simulated and measured results show good agreement in desired frequency band. For material characterization, first, two known materials are characterized using this metamaterial sensor. Their respective resonances and dielectric constants are known, so the transcendental equation of the sensor is formulated. Afterwards, the proposed sensor is used for dielectric measurement of two types of coal powder, i.e., Anthracite and Bituminous. The measured value of dielectric constant of Anthracite coal is 3.5 and of Bituminous coal is 2.52. This is a simple and effective nondestructive measurement technique for material testing applications.

Performance Evaluation of a Long-Span Cable-Stayed Bridge Using Non-Destructive Field Loading Tests

As an important part of the transportation network, the reliability of bridge structures is of great significance to people’s personal safety, as well as to the national economy. In order to evaluate the performance of complex bridge structures, their mechanical behavior and fundamental characteristics need to be studied. Structural health monitoring (SHM) has been introduced into bridge engineering, and the structural response assessment, load effects monitoring, and reliability evaluation have been developed based on the collected SHM information. In this study, a performance evaluation method for complex bridge structures based on non-destructive field loading tests is proposed. The cable-stayed bridge in Guangxi with the largest span (Pingnan Xiangsizhou Bridge) was selected as the research object, and loading on the main girder was transferred to the piers and tower through the stay cables, whose structural responses are critical in the process of bridge operation. Therefore, the field loading tests—including deflection and strain testing of the main girder, as well as cable force tests—were also conducted for Pingnan Xiangsizhou Bridge by using non-destructive measurement techniques (multifunctional static strain test system, radar interferometric deformation measurement technology, etc.). Based on the numerically simulated results of a finite element model for Pingnan Xiangsizhou Bridge, reasonable field loading test conditions and loading arrangement were determined. Non-destructive field loading test results showed that the quality of the bridge’s construction is up to standard, due to a good agreement between the calculated and measured frequencies of the bridge. In addition, the calibration coefficients of displacement and strain were less than 1, indicating that Pingnan Xiangsizhou Bridge has satisfactory stiffness and strength.

Development of magnetic flux leakage device as a non-destructive method for structural reinforcement detection

Non-destructive measurement techniques are used to identify engineering construction components without causing any negative effects on their use as construction components in the future. Contrary to this, conventional techniques cause damage to the structure. The magnetic flux leakage (MFL) method is a non-destructive test technique commonly used to assess the physical status of construction materials. Within the framework of this study a magnetic flux leakage device was produced to detect the properties of reinforced concrete construction elements. The produced magnetic flux leakage device was used for measurements in 4 different test systems created in the laboratory environment and the results were interpreted. Thus, it was revealed that the detection of reinforcement in structures can be performed more rapidly and without damage with the MFL method.

Terahertz frequency domain sensing for fast porosity measurement of pharmaceutical tablets

Porosity is an important property of pharmaceutical tablets since it may affect tablet disintegration, dissolution, and bio-availability. It is, therefore, essential to establish non-destructive, fast, and compact techniques to assess porosity, in situ, during the manufacturing process. In this paper, the terahertz frequency-domain (THz-FD) technique was explored as a fast, non-destructive, and sensitive technique for porosity measurement of pharmaceutical tablets. We studied a sample set of 69 tablets with different design factors, such as particle size of the active pharmaceutical ingredient (API), Ibuprofen, particle size of the filler, Mannitol, API concentration, and compaction force. The signal transmitted through each tablet was measured across the frequency range 500–750 GHz using a vector network analyzer combined with a quasi-optical set-up consisting of four off-axis parabolic mirrors to guide and focus the beam. We first extracted the effective refractive index of each tablet from the measured complex transmission coefficients and then translated it to porosity, using an empirical linear relation between effective refractive index and tablet density. The results show that the THz-FD technique was highly sensitive to the variations of the design factors, showing that filler particle size and compaction force had a significant impact on the effective refractive index of the tablets and, consequently, porosity. Moreover, the fragmentation behaviour of particles was observed by THz porosity measurements and was verified with scanning electron microscopy of the cross-section of tablets. In conclusion, the THz-FD technique, based on electronic solutions, allows for fast, sensitive, and non-destructive porosity measurement that opens for compact instrument systems capable of in situ sensing in tablet manufacturing.

Dielectric properties assessment of honey by using non-destructive dielectric spectroscopy

&lt;p&gt;In this research the dielectric constant of three types of Malaysian honey has been investigated using a non-destructive measurement technique. The objective of this research is to assess the dielectric constant of the three types of honey in Malaysia using a non-destructive measurement technique known as an open-ended coaxial probe in the frequency range from 100 MHz to 10 GHz frequency. Analysis on the effect water concentration in honey on the dielectric constant and the effect of temperature on dielectric constant of honey has been conducted. The three types of honey that have been chosen to be investigated in this project are stingless bee honey, wild honey and commercial (organic) honey and together their water adulterated samples. For this research, the probe had been set up by setting a range of frequency from 100 MHz to 10 GHz and needs to be calibrated with three calibration methods namely open, short and reference water. From the result it was found that the higher the temperature of the honey and the higher percentage of water content in the honey, the dielectric constant is increased. The dielectric constants of all honeys decreased with increasing frequency in the measured frequency range and increased with increase percentage of water content and temperature.&lt;/p&gt;

Quantitative Effect of Aging Duration on Dielectric Parameters Based on Frequency Response

In this work, a non-edible natural ester oil (NEO) is considered for the study for its aging characteristics by the frequency-domain spectroscopy (FDS). The NEO considered is the Jatropha Curcas oil (JAT) because of its non-edible and biodegradable nature. The FDS method is a non-destructive measurement technique which is used to analyze the characteristics of the JAT oil by obtaining the relative permittivity and dielectric dissipation factor (DDF) over a wide range of frequencies. The NEO is subjected to thermal stress in an open beaker aging test setup at 115 °C for up to 500 h, and after every of 100 h of aging, the samples are taken out for testing. This technique is applied to understand the dielectric response of the oil at different aging durations. Fourier transform infrared spectroscopy and ultraviolet visible spectroscopy analyses are implemented before and after aging, to observe the alterations in the structure of the two oil samples. The FDS results show how the dielectric properties of JAT vary under aging and help understand the phenomenon behind the degradation at lower frequencies. The variation in the dielectric properties was analyzed by regression models for a quantitative outlook to aging in the oil samples and an associative relationship is established among the parameters.

Non-destructive measurement technique for water content in organic solvents based on a thermal approach.

The water content of organic solvents is one of the crucial properties that affect the quality of the products and the efficiency of the manufacturing processes. The established water determination methods such as Karl Fischer titration and gas chromatography require skilled operators, specific reagents, and prolonged measurement time. Thus, they are not suitable for both on-line and in-line applications. In this study, we aim to develop a real-time and low-cost device with reliable accuracy. The proposed device based on a newly developed thermal approach could non-destructively detect the water content in multiple organic solvents at low concentrations with high accuracy and without the use of any specific reagent. Experiments were performed for the determination of water content in organic solvents such as methanol, ethanol, and isopropanol. The results show that the proposed device is feasible for the water content determination in methanol, ethanol, and isopropanol at 0–1% w/w. A Bland–Altman plot to illustrate the differences in measurements between the proposed device and coulometric Karl Fischer titration shows that most of the measurements lie within the limits of agreement where 95% of the differences between the two methods are expected to fall in the range of −0.13% and 0.09%.

Nondestructive Quantitative Analysis of Water Potential of Tomato Leaves Using Online Hyperspectral Imaging System

HighlightsWe developed an online measurement system for water potential of tomato plants using hyperspectral imaging.We used Linear Discriminant Analysis to automatically and quickly extract the leaf images.We used SNV scattering correction to remove the spectral variations caused by collecting the defocused leaf images.We developed a prediction model of leaf water potential based on spectral image information.Abstract. Tomatoes have different water requirements in each growing period. Excessive water use or insufficient water supply will affect the growth and yield of tomato plants. Therefore, precise irrigation control is necessary during cultivation to increase crop productivity. Traditionally, the soil moisture content or leaf water potential has been used as an indicator of plant water status. These methods, however, have limited accuracy and are time-consuming, making it difficult to be put into practice in tomato production. This study developed an online hyperspectral imaging system to measure the leaf water potential of tomato nondestructively. Linear Discriminant Analysis was utilized to automatically and quickly extract the leaf images, with the recognition accuracy of 94.68% was achieved. The mathematical processing of Standard Normal Variate scattering correction was used to remove the spectral variations caused by the defocused leave images. The developed leaf water potential prediction model based on the spectral image information attained using the developed system achieved the standard error of calibration of 0.201, coefficient of determination in calibration set of 0.814 and standard error of cross-validation of 0.230, and one minus the variance ratio of 0.755. The obtained performance indicated the feasibility of applying the developed online hyperspectral imaging system as a real-time non-destructive measurement technique for the leaf water potential of tomato plants. Keywords: Hyperspectral imaging system, Machine learning, Tomato, Water potential.

Monitoring the apical growth characteristics of hairy roots using non-invasive laser speckle contrast imaging.

Hairy roots are used to produce plant agents and additives. Due to their heterogeneous structure and growth characteristics, it is difficult to determine growth‐related parameters continuously and in real time. Laser speckle contrast analysis is widely used as a non‐destructive measurement technique in material testing or in medical technology. This type of analysis is based on the principle that moving objects or particles cause fluctuations in stochastic interference patterns known as speckle patterns. They are formed by the random backscattering of coherent laser light on an optically rough surface. A Laser Speckle Imager, which is well established for speckle studies of hemodynamics, was used for the first time for non‐invasive speckle measurements on hairy roots to study dynamic behavior in plant tissue. Based on speckle contrast, a specific flux value was defined to map the dynamic changes in the investigated tissue. Using this method, we were able to predict the formation of lateral strands and to identify the growth zone in the apical root region, as well as dividing it into functional regions. This makes it possible to monitor physiological processes in the apical growth zone in vivo and in real time without labeling the target structures.

Probing peptide nanowire conductivity by THz nanoscopy

Significant efforts have recently been invested in assessing the physical and chemical properties of microbial nanowires for their promising role in developing alternative renewable sources of electricity, bioelectronic materials and implantable sensors. One of their outstanding properties, the ever-desirable conductivity has been the focus of numerous studies. However, the lack of a straightforward and reliable method for measuring it seems to be responsible for the broad variability of the reported data. Routinely employed methods tend to underestimate or overestimate conductivity by several orders of magnitude. In this work, synthetic peptide nanowires conductivity is interrogated employing a non-destructive measurement technique developed on a terahertz scanning near-field microscope to test if peptide aromaticity leads to higher electrical conductivity. Our novel peptide conductivity measurement technique, based on triple standards calibration method, shows that in the case of two biopolymer mimicking peptides, the sample incorporating aromatic residues (W6) is about six times more conductive than the negative control (L6). To the best of our knowledge, this is the first report of a quantitative nano-scale terahertz s-SNOM investigation of peptides. These results prove the suitability of the terahertz radiation-based non-destructive approach in tandem with the designer peptides choice as model test subjects. This approach requires only simple sample preparation, avoids many of the pitfalls of typical contact-based conductivity measurement techniques and could help understanding fundamental aspects of nature’s design of electron transfer in biopolymers.

Impact of curing time on UCS-electrical resistivity relation of cement grouted sands

As the curing process proceeds, both the strength and electrical resistivity (pmix) of cement-based (or cement-grouted) materials increase, leading to the nondestructive pmix measurement technique is very appealing in the assessment/monitoring of the quality of cement-grouted materials. However, the strength gain of cement-grouted sands with time differs from the increase in pmix with time. Thus, the relationship between unconfined compressive strength (UCS) and pmix can be affected by the curing time. This study evaluated the effect of curing time on the relationship between pmix and UCS of sands grouted with microcement. The ultimate goal of this study is to estimate UCS over time of cement-grouted sands based on pmix. Three silica sands with different median particle sizes were grouted with microcement at different water-to-cement ratios (wc) of 1.0, 1.5, and 2.0. Both unconfined compression test and electrical resistivity measurement test were conducted. Results demonstrate that curing time, particle size, and wc influenced both pmix and UCS of tested grouted sands in a similar manner; therefore, a direct relationship between pmix and UCS can be established. However, the complex impact of curing time on the relation between UCS and pmix and the nonlinear increase in UCS with time hinder the capture of adequate interplay between UCS, pmix, and curing time. Because a nonlinear increase in UCS with time can be represented by hyperbolic model, an estimation method for hyperbolic model parameters is newly suggested in this study based on pmix at early curing days.

Active Thermography for the Detection of Sub-Surface Defects on a Curved and Coated GFRP-Structure

Initial defects, for example, those occurring during the production of a rotor blade, encourage early damages such as rain erosion at the leading edge of wind turbine rotor blades. To investigate the potential that initial defects have for early damage, long-pulse thermography as a non-destructive and contactless measurement technique is applied to a strongly curved and coated test specimen for the first time. This specimen is similar in structural size and design to a rotor blade leading edge and introduced with sub-surface defects whose diameters range between 2mm and 3.5mm at depths between 1.5mm and 2.5mm below the surface. On the curved and coated test specimen, sub-surface defects with a depth-to-diameter ratio of up to 1.04 are successfully detected. In particular, defects are also detectable when being observed from a non-perpendicular viewing angle, where the intensity of the defects decreases with increasing viewing angle due to the strong surface curvature. In conclusion, long-pulse thermography is suitable for the detection of sub-surface defects on coated and curved components and is therefore a promising technique for the on-site application during inspection of rotor blade leading edges.

Firmness evaluation of postharvest pear fruit during storage based on a vibration experiment technique using a dielectric elastomer actuator

This study proposes a vibration technique based on the dielectric elastomer actuator (DEA) excitation to determine the resonance frequency of La France pear fruit. Postharvest pear fruit ripen during storage to improve their quality. A non-destructive measurement technique is necessary to predict maturity without damaging the fruit. The maturity of pear fruit is correlated with firmness, which can be assessed by a firmness index derived from the resonance frequency and the mass. Because DEAs exhibit characteristics that are conducive to vibration applications such as flexibility, lightweight, responsiveness, and deformability, they can be applied and effectively transfer excitation forces to fruit or vegetables with curved surfaces. In this study, the proposed technique is used to evaluate the variations in firmness indices of pear fruit during storage. Additionally, the firmness is measured using a penetrometer to verify the correlation with the firmness index. Using a vibration test system, the distinct frequency responses of pear fruit are obtained and the resonance peaks of the first elastic mode are observed around 700 Hz. The firmness indices of the target fruit are (21.6±2.5)×106 Hz2 g2/3 on day 0 and tend to decrease during storage. The tendency of each fruit is approximated based on a nonlinear least square method. Moreover, the firmness indices are well correlated with the results of the penetrometer test, demonstrating the effectiveness of the proposed technique to evaluate pear fruit quality.