Showing papers in "Journal of Testing and Evaluation in 2023"
TL;DR: In this article , various cellulosic materials, such as CTF, micro-crystalline cellulosics, and nanocrystalline CTF fibers, were extracted from coffee waste to make them into valuable products.
Abstract: Because of the environmental footprint of oil-based materials, the demand for bio-based renewable materials is hiked. The usage of agricultural waste to extract cellulose, minimized the dependent of hydrocarbon products which is an added value besides due to overpopulation the productivity is increased, which leads to an increase in agricultural waste that causes environmental pollution. In this work, various cellulosic materials, such as cellulosic textile fibers (CTF), microcrystalline cellulosic fibers, and nanocrystalline cellulosic fibers, were extracted from coffee waste to make them into valuable products. The morphological analysis of extracted cellulose is performed by scanning electron microscopy, and the Fourier transform infrared spectroscopy was performed to investigate the structure of extracted cellulose, which indicates the crystalline cellulosic components from the extraction process; X-ray diffractometer analysis shows the extracted cellulose was cellulose I and cellulose II. The cellulose that is extracted by ultrasonication with dimethyl sulfoxide has 88 % of cellulose with a crystallinity index of 74.5 %, and the thermal properties of raw coffee husk and extracted cellulose were compared by thermogravimetric analysis. Additionally, the dye uptake of the CTF shows its potential as a bio-adsorbent in the dye removal domain.
3 citations
TL;DR: In this paper , the authors studied the spatial distribution of the corrosion products in concrete based on a series of experimental investigations of a marine construction and found that the migration of corrosion products was particularly affected by the location and geometry of the defects.
Abstract: This paper studies the spatial distribution of the corrosion products in concrete based on a series of experimental investigations of a marine construction. The distributions of defects and corrosion products in the concrete cover were identified in a mesoscale based on the computed tomography test, and the fractal dimension of cracks was analyzed. Some cracks and defects were filled by corrosion products in various degrees. The results showed that the defects were significantly influenced by the shape and relative location of the deformed steel reinforcement, which would then lead to the variation of the corrosion layer. The migration of corrosion products was particularly affected by the location and geometry of the defects, which could provide a suitable channel for the migration of corrosion products. The research can be helpful for the prediction of concrete cracking performance induced by the chloride-induced corrosion of the steel reinforcement.
3 citations
TL;DR: In this article , the effect of waste polyethylene (PE) on the modified asphalt binders' rheological behavior from a statistical point of view was investigated, and the interlaboratory testing results from the RILEM Technical Committee Valorization of Waste and Secondary Materials for Roads Task Group 1 were used for this purpose.
Abstract: This article investigated the effect of waste polyethylene (PE) on the modified asphalt binders’ rheological behavior from a statistical point of view. The interlaboratory testing results from the RILEM Technical Committee 279 Valorization of Waste and Secondary Materials for Roads Task Group 1 were used for this purpose. First, an unaged 70/100 penetration graded neat binder was selected as the reference material. Next, a single 5 % content of waste PE additives (PE-pellets and PE-shreds) was mixed with a 95 % neat binder to prepare two PE modified binders. Then, dynamic shear rheometer–based temperature-frequency sweep tests were performed over a wide range of temperatures and frequencies to evaluate the rheological properties of these three binders. Different rheological behaviors were observed in the isochronal plots at high temperatures. Based on a reproducibility precision requirement proposed for phase angle, 28°C was set as the transition temperature across the rheological behaviors. Next, according to the three rheological behaviors defined in a previous study by the authors, statistical analysis was introduced to identify sensitive rheological parameters and determine the thresholds. Results indicate that the phase angle measured above 28°C and 1.59 Hz can be used as a sensitive parameter to discriminate the three rheological behaviors of PE modified binders. The thresholds among different behaviors were also calculated as an example for phase angle measured at the highest common testing temperature of 70°C. Additional experimental evaluations on more types of PE modified binders, especially at intermediate and high temperatures, are recommended to better understand their influence on the rheological behavior of PE modified binders.
2 citations
TL;DR: In this paper , the characteristics of liquid metal embrittlement (LME) cracks combined with the location, amount, and length of the resistance spot-welded joint of galvanized advanced high-strength steel were comprehensively investigated.
Abstract: The characteristics of liquid metal embrittlement (LME) cracks combined with the location, amount, and length of the resistance spot-welded joint of galvanized advanced high-strength steel were comprehensively investigated in this study. To better illustrate the features of LME cracks, a multilayer grinding and polishing technique was employed to more comprehensively reflect the existence of LME cracks compared with that of a single-layer technique. Based on the crack observation results of the cross section of the center weld, the longest type-I and type-II cracks were approximately 322.2 and 106.7 μm, respectively. On the contrary, the longest type-I and type-II cracks were approximately 1,062.9 and 194.7 μm, respectively, for the multilayer grinding and polishing technique. The existence of liquid zinc for more time and the resultant tensile stress at the center of the weld can trigger crack propagation, eventually resulting in type-I cracks that are longer than type-II cracks. Similarly, severe LME cracks mainly exist in the central position of the welded joint, implying that temperature and stress can have a crucial effect on the formation and propagation of LME cracks.
1 citations
TL;DR: Based on the Seeger fatigue life theory and the improved Lemaitre damage evolution theory, the fatigue behavior of four Ti2AlNb alloys was investigated in this article , and the average errors of the predicted fatigue lives of the four structural parts are 20.1, 19.8, 20.9, and 19.5 %, respectively.
Abstract: In aerospace engineering, many titanium alloy structures are subjected to fatigue loads and thus fail. Based on the Seeger fatigue life theory and the improved Lemaitre damage evolution theory, the fatigue behavior of four Ti2AlNb alloys is investigated. First, finite element models of four structural parts are established by ABAQUS software. Meanwhile, the fatigue life of four Ti2AlNb alloys is predicted by referring to the damage model parameters determined by previous work. Under the same initial conditions, the average errors of the predicted fatigue lives of the four structural parts are 20.1, 19.8, 20.9, and 19.5 %, respectively. The effects of load amplitude, temperature, and structural characteristics on the fatigue properties of Ti2AlNb alloy structural parts are studied. The stability of the two fatigue life simulation methods is analyzed. By comparing fatigue data of Ti2AlNb structural parts from various literature, the rationality of the simulated data is confirmed. Finally, the application of the Ti2AlNb structural fatigue database to machine learning is illustrated. These results provide a numerical simulation method for evaluating the fatigue life of various Ti2AlNb alloy aviation structural parts.
1 citations
TL;DR: In this article , a thermo-mechanical model dedicated to fatigue cracking in bituminous material is presented, where the parameters of the Paris law are determined using the notched specimens (a0 being assimilated to the notch depth) except for Nini, which is deduced from the difference in lifetime duration between the tests carried out on notched and unnotched specimens.
Abstract: This article aims at presenting a thermo-mechanical model dedicated to fatigue cracking in bituminous material. The model calibration based on two-point bending (2PB) fatigue tests performed on specimens of bitumen-bound sand is also detailed. In the model, crack growth is handled by the Paris law considering the initialization term Nini. This parameter represents the number of loading cycles required to initiate a short macrocrack of length a0 from which the Paris law can be applied. The tests utilized for calibration and comparison with the numerical simulations are performed on notched and unnotched trapezoidal samples, for different levels of imposed displacement amplitude. The parameters of the Paris law are determined using the notched specimens (a0 being assimilated to the notch depth) except for Nini, which is deduced from the difference in lifetime duration between the tests carried out on notched and unnotched specimens. The full calibration procedure described thereafter has the advantage to not depend on the choice of a0. It is shown that the simulations run for the calibrated model are globally in good agreement with the test results obtained for both types of samples and for all the imposed displacement amplitudes. Finally, the model is used to predict the response of four-point bending tests carried out on the same bitumen-bound sand, considering the input parameters determined from the 2PB tests. The intrinsic nature of the model is evaluated through its ability to simulate both types of tests using the same set of material parameters.
TL;DR: In this paper , the authors carried out an experimental study on two solar stills with a single slope, one was provided by a new absorber designed with multilayer composite materials and the other still was taken as a reference or control.
Abstract: The supply of drinking water has become a major challenge, despite large but relatively polluted quantities of groundwater, especially in southeastern Algeria. The use of solar energy for water desalination has become the subject of many local and global researchers. To solve this problem, we carried out an experimental study on two solar stills with a single slope. One was provided by a new absorber designed with multilayer composite materials and the other still was taken as a reference or control. The dimensions of the solar still was 0.5 × 0.5 m and the thickness of the layer of water used was 0.01 m. The results obtained show that the quantity of fresh water produced from the modified solar still was 4,312 l/m2 per day, while that of the reference solar still was 4,488 l/m2 per day, showing a difference in productivity of 3 %.
TL;DR: In this paper , the effects of the SESO bio-emulsion demonstrated a rejuvenating activity on the properties of the aged asphalt binder, with mechanical and rheological improvements for both analyzed rates.
Abstract: An increase in the use of biomaterials has been noted in recent years because of several impacts caused by human activities, especially for engineering and paving industry benefits. Several renewable resources, such as a nonfood source of soybean oil, have been successfully tested on modification of asphalt binders. However, their impact on the pavement life cycle is still unknown. Thereby, the objective of this research was to investigate soybean oil as a new, green supply for the maintenance of flexible pavements. The experimental plan consisted of the construction of field test sections through the application of sub-epoxidized soybean oil (SESO) over a flexible pavement surface. Rates of 0.1 and 0.3 L/m2 were chosen, and the main tests intended for study were functional procedures including the British pendulum and sand patch tests on the pavement surface, which were complemented with the indirect tensile strength test for mechanical analysis. The change in the chemical composition of the recovered binder was analyzed by thin layer chromatography and Fourier-transform infrared spectroscopy. The rheological properties were analyzed by frequency sweep, linear amplitude sweep, and multiple stress creep and recovery, and the tests were carried out with a dynamic shear rheometer. The effects of the SESO bio-emulsion demonstrated a rejuvenating activity on the properties of the aged binder, with mechanical and rheological improvements for both analyzed rates. A further investigation is indicated to evaluate the influence of time on the modification studied in this work. Such testing could ensure the use of SESO bio-emulsion as an environmentally friendly alternative for the maintenance of flexible pavements.
TL;DR: In this paper , the authors investigated the mechanical properties of light-transmitting concrete with different optical fiber arrangements with three optical fiber ratios, respectively, 1, 1.6, and 2.4 %.
Abstract: Although concrete has been used extensively as a structural material for buildings since ancient times, light-transmitting concrete (LTC), also referred to as translucent concrete, is an innovative and attractive building material for the construction industry to enhance aesthetic and energy-saving properties. This research paper aims to investigate the mechanical properties of LTC with different optical fiber arrangements with three optical fiber ratios, respectively, 1, 1.6, and 2.4 %. The durability performance of LTC under the effects of accelerated aging is also investigated. Polymethyl methacrylate (PMMA) optical fibers with two arrangements were used in the concrete specimens. One of the LTC groups that had a linear optical fiber arrangement was labeled as ARlin. The other LTC group with bundle optical fiber arrangements was labeled as ARbun. The prepared concrete consisted of cement, fine aggregate, water, mineral additive, acrylic polymer, and superplasticizer. The flexural strengths of LTC with PMMA optical fibers placed longitudinally or laterally were determined. The compressive strengths of LTC specimens with different arrangements were compared. Accelerated aging effects under wetting-drying, freezing-thawing, and high temperature were applied to the ARlin group to investigate these effects on the mechanical properties of LTC. The results of the experiments indicate that the optical fiber arrangements affect the flexural strength, compressive strength, and light transmittance of LTC. The light transmittance increases with the optical fiber content. It is also seen that the flexural strengths and light transmittance of LTC specimens decrease significantly after the high-temperature effect. According to the test results, it is also concluded that LTC with 0.5-mm-diameter optical fibers in a linear arrangement can be used as a construction material under external conditions.
TL;DR: In this paper , graphite flakes are used as nanofiller in polystyrene (PS) membrane to improve hydrophobicity, moisture blocking capacity, thermal stability, tensile strength, and gas separation ability.
Abstract: The use of polymer composite membranes has been widely increased to improve the mechanical and material properties. In this research, graphite flakes are used as nanofiller in polystyrene (PS) membrane to improve hydrophobicity, moisture blocking capacity, thermal stability, tensile strength, and gas separation ability. The membranes are prepared by a solution casting technique and are characterized by fourier transformation infrared spectroscopy, X-ray diffractometry, scanning electron microscope, thermal gravimetric analysis, water contact angle (WCA), moisture transmission rate (MTR), and mechanical testing. The prepared membranes are also tested to determine the O2 and N2 permeability and O2/N2 selectivity. The quantity of graphite flakes is varied from 0–1.0 wt% of PS. 0.7 wt% graphite-filled PS has shown the best results among all the prepared samples. The WCA of the PS membrane is increased from 97.3 to 114.803°, which shows that graphite flakes are well-suited to increase the hydrophobicity of the PS membrane. The MTR of 0.7 wt% graphite-filled PS shows that the membrane is well-suited for moisture blocking and also showed better thermal stability. Graphite flakes are also found suitable for increasing the tensile strength of the membrane. Also, the highest O2/N2 selectivity is achieved for 0.7 wt% graphite-filled membranes, which makes them suitable for gas separation operation. Furthermore, the potential application of graphite-filled PS membranes is also presented.
TL;DR: In this paper , an automatic impacting device was devised, a system was set up to measure impact force signal, and a program was developed to analyze the obtained signal and estimate the compressive strength.
Abstract: This study examined the potential of the impact force response signal induced by impacting an object to estimate the compressive strength of concrete nondestructively. For this study, an automatic impacting device was devised, a system was set up to measure impact force signal, and a program was developed to analyze the obtained signal and estimate the compressive strength. Concrete test specimens were manufactured and tested. Impacts were carried out on the specimens, and the impact force signals were obtained. The signals were analyzed to obtain the total impact force signal energy, and a uniaxial compressive strength test was carried out on each specimen to measure the compressive strength directly. A good relationship was formed between the total impact force signal energy and the uniaxial compressive strength. The strength was estimated from the obtained relationship for new test specimens and compared with the directly measured strength. The comparison indicated that the estimated strength and the measured strength had a close relationship. In addition, a Schmidt hammer test was carried out on the new specimens before the uniaxial compressive test, and the test results were compared with those from the impact force signal energy. The strength estimation using the impact force signal energy had a better result. The study results show that the compressive strength of concrete materials could be estimated nondestructively using the proposed method.
TL;DR: In this paper , the optimized process parameters for low hot cracking susceptibility and the enhanced microhardness of ultrasonic-assisted tungsten inert gas (UA-TIG) welded AA7075 joints were investigated.
Abstract: The current study investigates the optimized process parameters for low hot cracking susceptibility and the enhanced microhardness of ultrasonic-assisted tungsten inert gas (UA-TIG) welded AA7075 joints. The optimization trials were made using response surface methodology (RSM) and RSM coupled with genetic algorithm (RSM-GA) approaches. Welding process parameters, such as welding current, gas flow rate, presence and absence of ultrasonic vibration (UT), and filler metal were varied to study the hot crack sensitivity and microhardness of the AA7075 welded joints. RSM was used to develop the empirical relationships with a higher coefficient of determination (R2 = .9892 for hot cracking sensitivity and R2 = .9919 for microhardness). Welding current (120A), gas flow rate (13L/min) with UT and filler material with hot cracking sensitivity (0 %), and microhardness (117.76HV) are the optimized process parameters. The experimental results and predicted RSM model at optimal conditions were compared to the predicted RSM-GA model for minimal hot cracking sensitivity and maximum microhardness. A good agreement between the experimental results and the predicted RSM model confirms the soundness of the developed RSM-GA model.
TL;DR: In this paper , the influence of Si3N4 nano reinforcement content on hardness, strength, and wear resistance of AA357-Si3N 4 nanocomposites was investigated.
Abstract: The engineering sector researchers are always searching for new materials for their challenging applications. The aluminum alloy (AA) 357 plays a critical role in applications like automotive and aerospace because of its exceptional characteristics such as toughness, fatigue resistance, and more importantly strength-to-weight ratio, but it suffers from poor wear resistance. However, the research community is looking for enhancement in wear resistance at various loads. This research deals with AA357-Si3N4 nanocomposites fabricated through the induction stir casting method and evaluation of properties in comparison with AA357 matrix. The Si3N4 nanoparticulates were selected as reinforcement and added 0.5 to 3.0 wt.% in the steps of 0.5 wt.%. The influence of Si3N4 nano reinforcement content on hardness, strength, and wear resistance of AA357-Si3N4 nanocomposites investigative work was conducted as per ASTM standards. The studies of microstructures of AA357-Si3N4 nanocomposites were performed using an optical microscope to analyze grain structure and a scanning electron microscope (SEM) to examine particle distribution. The density, hardness, and ultimate tensile strength (UTS), in addition to morphological studies of fractured surfaces and energy dispersive spectroscopy for nanocomposites elemental study. As per ASTM G99, Standard Test Method for Wear Testing with a Pin-on-Disk Apparatus, standards, pin-on-disc equipment was used to examine tribological properties of AA357-Si3N4 nanocomposites and SEM pictures of worn nanocomposites surfaces analyzed extensively. By going through the experimental outcomes, it is realized that with increase in nano reinforcement in matrix AA357, the properties such as density, resistance to indentation/hardness, and UTS increased at the expense of percentage elongation. The pin-on-disc tribometer experimental results indicate that the fabricated AA357-Si3N4 nanocomposites have higher wear resistance.
TL;DR: In this article , an improved principal component analysis-support vector machine (PCA-SVM) intelligent algorithm based on grid search (GS) is proposed to detect the fatigue crack at different depths of rail bottom.
Abstract: Ultrasonic guided wave is widely used to detect cracks in rail because of its long propagation distance and small attenuation. To effectively detect the fatigue crack in rail bottom through ultrasonic guided wave, an improved principal component analysis-support vector machine (PCA-SVM) intelligent algorithm based on grid search (GS) is proposed to detect the fatigue crack at different depths of rail bottom. The finite element method is used to establish the model of ultrasonic guided wave at different depths of the rail bottom, and the simulation model is compared with the experimental data to determine the effectiveness of the simulation model. Five main component features of the fatigue cracks at different depths are extracted by PCA. The GS method is used to optimize the penalty factor c and kernel function parameter g in the SVM, and the optimized SVM model is selected to identify the rail fatigue crack at different depths. The combination of theoretical simulation and experimental results shows that the accuracy of the training set and the test set of the improved PCA-SVM intelligent algorithm based on the GS method can reach 99.79 % and 99.73 %, respectively, which provides a basis and method for the detection of the fatigue crack depth of the rail bottom.
TL;DR: In this article , the authors studied the limit of linear viscoelastic behavior on a common straight-run bituminous binder at different temperatures and frequencies by performing strain amplitude sweep tests.
Abstract: The objective of this research is to study the limit of linear viscoelastic behavior on a common straight-run bituminous binder at different temperatures and frequencies by performing strain amplitude sweep tests. A dynamic shear rheometer was used for the experimental campaign. An increase of complex modulus due to physical hardening was observed during strain amplitude sweep tests at low temperatures and frequencies. A correction method is proposed to consider the effect of physical hardening on complex modulus when evaluating the linear viscoelastic limit.
TL;DR: In this article , the authors investigated the effect of the design of a striker on the absorbed energy of low-energy reference materials and proposed a method of correcting this absorbed energy by subtracting the striker energy.
Abstract: Attempts to optimize the design of instrumented strikers for accurate dynamic force measurement were successful for a Toni MFL 300J Charpy impact tester (C-type hammer). However, the instrumented strikers for a Tinius Olsen IT406 machine (U-type hammer) failed to meet the indirect verification requirements at the low-energy level specified in ASTM E23-18, Standard Test Method for Notched Bar Impact Testing of Metallic Materials. To investigate whether the design of the striker contributes to the absorbed energy of low-energy reference specimens, the Charpy impact test was simulated for different striker designs by using finite element analysis. This exercise confirmed a contribution to the absorbed energy, attributed to the elastic energy stored in the striker at the point of brittle fracture (striker energy). The striker energy is proportional to the striker compliance, which is much larger for strikers for U-type machines than for C-type machines. Consequently, the absorbed energy of low-energy reference materials tested on C-hammer machines will be lower than when tested on U-hammer machines. The possibility of correcting the absorbed energy by subtracting the striker energy was investigated. For this purpose, historical records of instrumented tests on low-energy reference materials performed on pendulum impact testers with different strikers were analyzed. Correcting the absorbed energy shifts the striker bias. With no correction, more than half of the indirect verifications at the low-energy level failed, whereas nearly all passed after correction. Although a bias remained for individual strikers, the averaged corrected bias of all strikers was close to zero, indicating that the proposed method of correcting the absorbed energy of low-energy reference materials for the striker energy can potentially cancel out the striker influence, thereby yielding a striker/machine-independent value for low-energy reference materials.
TL;DR: In this article , the authors highlighted the unique areas of human-centered artificial intelligence with healthcare applications and various innovations in multidiscipline areas and also presented some technical evidence and its countermeasure.
Abstract: This Journal of Testing and Evaluation special issue integrates computer science/information technology with health science and services, embracing information science research coupled with topics related to the modeling, design, development, integration, and management of health information systems. This special issue highlights the unique areas of human-centered artificial intelligence with healthcare applications and various innovations in multidiscipline areas and also presents some technical evidence and its countermeasure. This special issue aims to identify the emerging technology in various domains with healthcare in all related areas. It consists of up-to-date, state-of-the-art research contributions with novel design and developments of intelligent application, perception, and security methods in healthcare artificial intelligence in order to enhance the reliability and feasibility of healthcare in real-world applications. The first three papers by Wei Qin, Peihua Liu, and Juan Chen deal with the development of the healthcare and leisure industries, health of badminton player performance based on machine learning, and development of online preschool education resources and background. Pingli Ren’s article proposes a local path planning method based on model predictive control to address the obstacle voidance problem of driverless vehicles in the hospital environment. Weiwei Liu reviews problems and countermeasures of sharing ideas of the effectiveness of ideological and political course teaching in the health perspective of colleges and universities. Xiaozhou Zhou’s article provides a possible cognitive clue on materials. The experimental results provide reference for medical product design. Xin Zhou, Jianjun Li, and Yuanyuan Kang concentrate on the response of bio-characteristics of subway vibration load based on finite element methods, medical graphic-aided visual elements active communication algorithm in print advertising, and comprehensive discrimination method of fluid phase behavior in low-permeability reservoir for blood flow modeling. Xiaocui Lu focuses on the identification method of conductance fluctuation signal of fiber Bragg grating biosensor. Shilong Zhang proposes a data collection strategy of a distributed network based on linear regression analysis, constructs a perceptual unconventional mutation data model by applying linear regression analysis method, and maintains the characteristics of perceptual data to realize data collection. Xi Yang’s article deals with an analysis method based on fuzzy integral that was proposed to analyze the features of digital broadcast bio-signals. Jun Tian’s paper concentrates on the stochastic limit equilibration-material point method, which is used to study the dynamic evolution process of different failure modes of slope under the condition that the slope parameters are not uniformly distributed in the space of a hospital environment. Bo Wang addresses the energy-saving configuration of embedded sensor transfer nodes in the Internet of Things (IoT) for dust movement monitoring in atmospheric environment from the heath perspective. Hyung-Hyo Lee, Zhu Mei, and Zhijun Ma concentrate on privacy protection schemes in medical electronic health records based on blockchain and asymmetric encryption, three-dimensional image analysis of sports technical features and sports training methods based on artificial intelligence, and overseas surgical warehouse location of a cross-border medical supply chain network based on parallel big data mining. Xiuying Yang, Ning Jia, and Yang Lv deal with the design of an IoT information interactive perception system based on fifth-generation (5G) mobile communication technology in a hospital network, medical data cloud information storage encryption based on fuzzy-particle swarm optimization, and design of an automatic monitoring model for real-time data flow in a network based on fuzzy-clustering analysis for health analysis. Yingying Mao’s article focuses on the hybrid particle-size algorithm for classification of hygienic fruit and vegetable images based on the convolution neural network from a health perspective. Haiying Zhang proposes pressure sensors to assess the force exerted by each foot during walking. A fuzzy algorithm is implemented on a smartphone and used to detect each of the gait phases based on the sensor signals. Additionally, to provide a solution that is insensitive to perturbations caused by non-walking activities, a probabilistic classifier is employed to discriminate walking forward from other low-level activities such as turning, walking backwards, lateral walking, etc. The papers by Chunqing Xuan, Fei Yin, Xiaorui Liu, and Heru Xue address the design of wireless sensor network data-acquisition systems via health sensors based on symmetric encryption algorithm, anti-malicious attacks of wireless sensor hospital networks based on an improved particle swarm optimization algorithm, intelligent visual path selections for health industry robots based on data mining, and predictions of milk protein content in milk for health hygiene based on hyperspectral and convolutional neural network. Chao Deng, Ying Chen, and Guangbin Wang concentrate on technical repair methods of Poyang bodiless lacquerware based on the scale-invariant feature transform algorithm for healthcare vision, long-term evolution-5G data transmission based on gray fuzzy Bayesian networks to monitor health parameters, and layered defogging for a remote-sensing image based on meteorological load factors. Jing Cheng’s article focuses on data aggregation algorithms of sensor network nodes for health monitoring based on fuzzy clustering, and Nannan Zhao proposes an improved method of cloud-computing data-protection technology based on a symmetric encryption algorithm. According to the characteristics of cloud computing, a trusted communication channel for virtual machine monitoring is established on users and servers.
TL;DR: In this article , an improved transfer function method is investigated and a new mounting structure is designed for high hydrostatic pressure, which can significantly improve the measurement efficiency of the underwater acoustic properties of materials and structure.
Abstract: Water-filled impedance tubes are widely used to measure the acoustic properties of underwater sound absorption materials. Traditional transfer function has been applied for sound absorption measurement in air. Because this method needs to switch between two microphones during the test, it is not suitable for a water-filled impedance tube, especially at high hydrostatic pressure. The mounting of the hydrophone is also a challenging problem for water-filled impedance at high hydrostatic pressure. In this study, an improved transfer function method is investigated and a new mounting structure is designed for high hydrostatic pressure. Measurements of the sound absorption coefficient of the polydimethylsiloxane material and a water/air interface are used to verify the improved transfer function method, and an underwater sound absorption material is tested under different hydrostatic pressures. Results show that the developed water-filled impedance has a stable and repeatable performance at the working frequency range from 1,500 to 7,000 Hz, and the testing pressure can increase up to 1.5 MPa with suitable reliability. This can significantly improve the measurement efficiency of the underwater acoustic properties of materials and structure at high hydrostatic pressure.
TL;DR: Bullet velocity measurement uncertainty supports the rigorous application of these functions by providing a means for accurate comparison between different laboratories, manufacturers, and users; tracking and assessing the performance history of a product; accurately assessing external effects (such as environmental) on performance; ensuring performance is within acceptable tolerances; and comparing the performance of products as mentioned in this paper .
Abstract: Bullet velocity measurements are critical to the understanding of the performance of firearms and their ammunition, as well as the ballistic protection of armor materials and systems. This information is essential to the improvement and advancement of firearms, ammunition, and armor. The bullet velocity measurement uncertainty supports the rigorous application of these functions by providing a means for accurate comparison between different laboratories, manufacturers, and users; tracking and assessing the performance history of a product; accurately assessing external effects (such as environmental) on performance; ensuring performance is within acceptable tolerances; and comparing the performance of products.
TL;DR: In this paper , a methodology applied to the radiation factor in the Costa Rican territory was designed, which is called the solar irradiance coefficient (SIC), which corresponds to a regional weighting of the annual direct solar radiation with respect to the total national direct sun radiation.
Abstract: The current asphalt aging tests that incorporate climatic factors at scale such as ultraviolet (UV) radiation, rainfall, evaporation, and condensation phenomena, as well as temperature, present general scaling conditions because of the great climatic variability that is intended to simulate. Because of this, in the present article, a methodology applied to the radiation factor in the Costa Rican territory was designed, which is called the solar irradiance coefficient (SIC). This corresponds to a regional weighting of the annual direct solar radiation with respect to the total national direct solar radiation. Using the SIC, regions of low, medium, and high irradiance were determined and, consequently, test values to be scaled through the UV light source. Based on the studies carried out, the regional classification of solar radiation concluded by the SIC provides values more accurate to the service conditions of the asphalts in Costa Rica, which improves the information collected on the performance of the material in the tests of accelerated aging by weathering.
TL;DR: In this article , the authors used the Belgian Nuclear Research Centre (SCK CEN) database for fracture toughness testing and verified that the methodology is sufficiently robust to provide an average loading rate within the suggested range of 0.5 and 2 MPa√m/s.
Abstract: ASTM E1921-21, Standard Test Method for Determination of Reference Temperature, T0, for Ferritic Steels in the Transition Range, contains a limitation on the stress intensity factor loading rate (K˙) for the quasistatic loading. The specimens should be loaded at a rate such that K˙ during the initial elastic portion is between 0.1 and 2 MPa√m/s. However, based on recent improvements in the test technique, it should be possible to narrow the loading rate range in order to reduce variability and have more comparable results between laboratories. For all users to be able to achieve the reduced range, clear guidelines are needed, which are not yet available. The Belgian Nuclear Research Centre (SCK CEN) has extensive experience in fracture toughness testing and has constructed a large database on which statistical studies were performed. This paper illustrates, using the SCK CEN database, that Wallin’s theoretical displacement formulas can only be used in the case in which the compliance of the testing setup is taken into account. An improved equation is proposed, guidelines for implementing the equation are drawn up, and these are verified using the database. It is clear that the methodology is sufficiently robust to provide an average loading rate within the suggested range of 0.5 and 2 MPa√m/s. This methodology could thus be integrated into the testing standard ASTM E1921-21.
TL;DR: In this article , a mathematical model based on Weibull distribution was proposed to describe the competition among different failure modes for defect-fine granular area (FGA)-fisheye induced failure exhibiting long fatigue life.
Abstract: As a metal material with superior mechanical properties, high-strength carburized steel is of great value for the production and manufacture of components in various fields. In this work, based on axial loading tests at stress ratios of −1, 0, and 0.3, the fatigue behaviors of high-strength carburized steels from high cycle to very high cycle are systematically investigated. For defect-fine granular area (FGA)-fisheye induced failure exhibiting long fatigue life, it is verified that the transition sizes between small and long cracks can be approximately equivalent to FGA size. Combined with extreme value estimation, a new mathematical model based on Weibull distribution was proposed to describe the competition among different failure modes. The results show that the probability of interior failure will decrease significantly with the increase of the maximum surface defect size under the condition that the maximum stress exceeds about 900 MPa. Additionally, larger surface defects are more beneficial to the occurrence of surface failure. Finally, combined with the stress correction factor proposed for optimizing the data with large dispersion, the fatigue life is predicted based on the crack initiation and propagation behavior, and the prediction results are in good agreement with the experimental results.
TL;DR: In this paper , an underground engineering model test system is used to simulate tunnel blasting excavation with a nonexplosive electric spark initiation device, and the acceleration and strain of the surrounding rock during excavation are collected in real time.
Abstract: Studying the propagation characteristics of blasting seismic waves in surrounding rock under different in situ stresses forms the basic framework for discussing the damage and failure laws of tunnel surrounding rock caused by deep engineering blasting vibration. To study the propagation law of blasting seismic waves under different in situ stresses, an underground engineering model test system is used to simulate tunnel blasting excavation with a nonexplosive electric spark initiation device. The vibration acceleration and strain of the surrounding rock during excavation are collected in real time. Based on the test data system, the blasting vibration response characteristics of tunnel surrounding rock under different in situ stresses are discussed. According to the results of experimental studies, the peak values of radial and axial acceleration show nonlinear attenuation with an increase in distance under different in situ stresses. With an increase in in situ stress, the attenuation rate of the peak value of radial acceleration decreases, while that of axial acceleration increases. Moreover, the peak values of acceleration and strain measured at the same point near the seismic source under different in situ stresses remain unchanged, whereas those measured at the same point far away from the seismic source gradually decrease. Moreover, the attenuation rate at the stage of low in situ stress is greater than that at the stage of high in situ stress. The farther away from the seismic source, the greater the influence of in situ stress on peak acceleration and peak strain. The research results play an important guiding role in the development of deep tunnel blasting theory and safe construction.
TL;DR: In this paper , a temperature stress test machine was used to investigate the early-age cracking potential of FA-HPC with internal curing by super absorbent polymers (SAPs).
Abstract: Early-age cracking is problematic for high performance concrete (HPC) made with a low water/binder ratio. The application of fly ash (FA) as a cement replacement can contribute to reduced CO2 emission and clinker factor, as well as improved durability of HPC. Super absorbent polymers (SAPs) were also applied for better curing and a higher rate of hydration to optimize the FA HPC. The current study utilized a temperature stress test machine to investigate the early-age cracking potential of FA HPC with internal curing by SAPs. Test results and the related analyses suggested that the introduction of internal curing alleviated the autogenous shrinkage, restrained stress, as well as tensile creep for HPC with 0 % and 20 % FA replacement level. The application of SAPs reduced the cracking potential of HPC with a low FA replacement level, whereas it aggravated the cracking when the FA replacement level was high.
TL;DR: In this article , a cube hydration model suitable for the CSS-cement system was established, which considered the spatial distribution and the evolution of cement and CSS particles in the hydration unit.
Abstract: Calcium silicate slag (CSS) is a secondary solid waste produced during the extraction of aluminum oxide (Al2O3) from fly ash. Pulverized CSS can replace part of portland cement as a supplementary cementitious material. This study investigates the content of chemically bound water and the hydration degree of a CSS-cement system while varying the CSS content, water–binder ratio, and hydration age. Results show that adding CSS can appropriately reduce the content of chemically bound water and the hydration degree. A cube hydration model suitable for the CSS-cement system was established, which considered the spatial distribution and the evolution of cement and CSS particles in the hydration unit. Based on the cubic hydration model, the growth process of hydration products of CSS and cement particles was analyzed, the expression for the volume of CSS and cement particles at different hydration stages was deduced, and the hydration degree of the CSS-cement system was calculated. The calculated value of the hydration degree was compared with the test value to verify the correctness of the former. Overall, the results provide a practical experimental and theoretical framework to understand the application of the CSS-cement system.