Values Of Mechanical Parameters Research Articles

Study on visualization of impact damage characteristics of honey peaches based on finite element method.

The study of visualization of impact damage of fruit under different thicknesses of buffer materials can provide more efficient transportation and packaging solutions, and thus the economic losses caused by fruit damage can be reduced. Pearl cotton (EPE) is commonly used as a buffer material in the market, and the impact damage behavior of honey peaches under different thicknesses of EPE buffer material was studied by using the finite element method. Firstly, the damage area, maximum contact force and damage volume during the collision of honey peaches with EPE materials of different thicknesses (2, 4, and 6mm) were obtained by the single pendulum device, and then the Modulus of elasticity and Poisson's ratio of peach flesh were obtained by compression test. Finally, the finite element model of honey peach was built and the collision simulations were performed. The results of the study showed that the values of mechanical parameters of honey peach decreased with the increase of the thickness of the buffer material. When the collision angle was below 60°, the honey peaches were not damaged in the collision with the EPE material with a thickness of 4mm or more. By comparing the tested values with the simulated values, it was found that the errors of the damage area, damage volume and maximum contact force were less than 19.71%, 26.82%, and 25.88%, respectively. The study not only proves the possibility of the finite element method in the quantitative prediction of honey peaches damage but also provides rational support for the packaging design of honey peaches.

Integrating the Finite Element Method with Python Scripting to Assess Mining Impacts on Surface Deformations

Mining operations disrupt the structure of rock layers, leading to surface deformations and potential mining damage. This issue has been extensively studied since the 19th century using various analytical, geometric-integral, and stochastic methods. Since the 1990s, numerical methods have been increasingly applied to determine changes in the stress and strain states of rock masses due to mining activities. These methods account for numerous additional factors influencing surface deformation, offering significant advantages over classical approaches. However, modelling rock masses presents challenges, particularly in calibrating the mechanical parameters of rock layers, an area extensively researched with numerous publications. In this study, we determined the mechanical parameter values of rock layers at the advancing mining front using a custom Python script and Finite Element Method (FEM) numerical models. We also introduced a modification to evaluate the error of the estimated parameter values. Numerical analyses were conducted for the Piast–Ziemowit mine region in Poland, utilizing mining, geological, and surveying data. Our results demonstrate that accurate calibration of mechanical parameters is crucial for reliable predictions of surface deformations. The proposed methodology enhances the precision of numerical models, providing a more robust framework for assessing the impact of mining activities on rock layers.

Experimental and numerical study on the mechanical behavior of layered rock anchored by CRLD anchor cable

The study of the mechanical behavior of layered anchored rock is essential for addressing the stability control challenges of surrounding rock of the roadway in layered rock masses. This paper focuses on a novel constant resistance large deformation (CRLD) anchor cable and conducts a comparative study on the uniaxial compressive mechanical behavior of unanchored rock, conventional high-strength (HS) anchor cable, and CRLD anchor cable anchored rock under different bedding dip angles α (30°, 45°, 60°, 75°, and 90°). The strength characteristics, failure characteristics, and acoustic emission characteristics of various specimen types were analyzed with emphasis. The results indicate that with the increase of bedding dip angle, the elastic modulus, peak strength, and residual strength of all specimen types exhibit a trend of decreasing first and then increasing. Compared to unanchored and HS anchored rock, the values of various mechanical parameters for CRLD anchored rock show varying degrees of improvement. The failure modes of various specimen types under different bedding dip angles can be classified into five categories based on the characteristics of the crack distribution. Through comparison, it was found that the CRLD anchor cable can effectively restrict the occurrence of bedding shear failure within the anchored zone in layered rocks with smaller dip angles (30°, 45°). It also transforms the failure mode of layered rocks with larger dip angles (60°, 75°) from a single mode of bedding shear failure to a mixed mode of bedding-bedrock failure. However, under a bedding dip angle of 90°, the two types of anchored rocks exhibit similar failure forms. Comparing the acoustic emission characteristics of the two types of anchored rocks, it is observed that under different bedding dip angles, CRLD anchored rocks exhibit a more uniform distribution of acoustic emission counts, a smoother energy release process, and significantly lower peak count and cumulative energy values. Finally, a numerical model for layered CRLD anchored rocks was constructed based on the discrete element method. The reliability of the experimental results from the physical model in this study was verified by statistically analyzing the quantity evolution process and orientation distribution of microcracks in the numerical model.

Molecular dynamic simulation on comprehensive performance of ferrocene-based burning rate catalysts in a solid propellent

To determine the compatibility and interaction between ferrocene (Fc) and other components in AP/HTPB/Fc-based BRCs propellant, molecular dynamics simulation (MD simulation) method was used to study the binding energy, cohesive energy density (CED), mean square displacement (MSD) and mechanical properties of mononuclear ferrocenyl compounds (ethyl ferrocene, butyl ferrocene and octyl ferrocene), dinuclear ferrocenyl compounds (2,2′-(ethylferrocene)propane, 2,2′-(butylferrocene)propane) propane and hydroxymethyl bis-ferrocenyl propane), ionic ferrocenyl compounds (three ionic ferrocenes with ferrocene methyl dimethyl ammonium as cation, perchlorate, nitrate and picrate as anions respectively) and cyclic ferrocenyl compounds (1-ferrocenylmethyl-2-ferrocenyl-3-methylbenzimidazolium, binuclear ferrocene bridged by bridged biphenylferrocene and dihydropyrazole).The binding energy results show that alkyl groups, polar groups (such as hydroxyl groups) and cyclic substituents can improve the interaction between Fc and AP/HTPB. Moreover, the electrostatic interaction between ionic ferrocene and AP is strong, but the van der Waals interaction between ionic ferrocene and HTPB is weak. The CED data show that the mixed models based on alkyl mononuclear ferrocene, catocene, cyclic ferrocene and ionic ferrocene all have high cohesive energy with good safety performance. The MSD results show that the order of anti-migration ability is cyclic ferrocene > binuclear alkyl ferrocene > mononuclear alkyl ferrocene > binuclear hydroxyl ferrocene > ionic ferrocene. Regarding to the value of mechanical parameters (K, G, E and K/G), the mixed model of AP/HTPB/ dihydropyrazole bridged binuclear ferrocene possess the best mechanical properties among the 12 models. Based on the comprehensive data, we conclude that dihydropyrazole bridged binuclear ferrocene is the most ideal ferrocene-based burning rate catalyst among 12 ferrocenes.

Thermophysical and adhesive properties of functional polymer materials based on epoxy resin and silicon-containing component

The work was aimed at developing an adhesive formulation with increased adhesive strength for metals. It contains an epoxy resin of the bisphenol type СHS-TROXY 520 (an analogue of ED-20), an amine hardener triethanolamine (TEA) and a silicon-containing component (3-isocyanatopropyl)triethoxysilane, designated as NCO-Si, with an optimal ratio of components. The content of NCO-Si in the formulations was 0.5, 1.0, 3.0 and 5.0 wt. %, respectively. The gradual transformation of the epoxy system into a three-dimensional network with the formation of ester and urethane groups was shown by IR spectroscopy method. Tensile and shear strength were determined using the tearing machine R-50 in accordance with current standards. It was found that the maximum values of physical and mechanical parameters were obtained when the amount of NCO-Si was 3 wt. %. The maximum values of adhesion strength to steel substrates δst. = 58.5 MPa significantly exceed those for neat epoxy formulations. The shear strength values for steel plates τst. = 21 MPa increase by 60 %, for aluminium plates they are δAl =14.5 MPa and increase by 48 %. The morphology of the samples has been studied by means of optical microscopy. It is shown that the modified NCO-Si samples are characterised by a phase-separated structure. At a minimum amount of NCO-Si (0.5 wt. %), structurally disordered spherical domains with a size of ~1÷3 μm are observed, an increase in the content of the organosilicon component leads to the formation of interconnected regular structures, which are less pronounced at 1.0 wt. % of NCO-Si and clear at 3.0 and 5.0 wt. % of NCO-Si. Thermogravimetric analysis (TGA) was performed as well. It is shown that the modification of epoxy resin by a silicon-containing component with NCO-Si groups leads to an improvement in thermophysical parameters, a decrease in internal stresses and the formation of a material with a structure close to equilibrium.

Study on the Printability of Starch-Based Films Using Ink-Jet Printing.

Starch-based films are a valuable alternative to plastic materials that are based on fossil and petrochemical raw resources. In this study, corn and potato starch films with 50% glycerol as a plasticizer were developed, and the properties of films were confirmed by mechanical properties, surface free energy, surface roughness, and, finally, color and gloss analyses. Next, the films were overprinted using ink-jet printing with quick response (QR) codes, text, and pictograms. Finally, the print quality of the obtained prints was determined by optical density, color parameters, and the visual evaluation of prints. In general, corn films exhibit lower values of mechanical parameters (tensile strength, elongation at break, and Young Modulus) and water transition rate (11.1 mg·cm-2·h-1) than potato starch film (12.2 mg·cm-2·h-1), and water solubility is 18.7 ± 1.4 and 20.3 ± 1.2% for corn and potato film, respectively. The results obtained for print quality on starch-based films were very promising. The overprinted QR codes were quickly readable by a smartphone. The sharpness and the quality of the lettering are worse on potato film. At the same time, higher optical densities were measured on potato starch films. The results of this study show the strong potential of using starch films as a modern printing substrate.

Structure, Phase Composition, and Mechanical Properties of ZK51A Alloy with AlN Nanoparticles after Heat Treatment

The paper studies the influence of the content of aluminum nitride nanoparticles on the structure and mechanical properties of the ZK51A magnesium alloy. The microstructure investigations with optical and electron microscopy show that 1 wt.% AlN promotes the best grain refinement and size distribution. According to tensile strength testing of the ZK51A alloy, grain refinement is not a dominating mechanism in the property improvement of the alloy after heat treatment. The maximum values of mechanical parameters are achieved at the lowest (0.1 wt.%) content of aluminum nitride. The main mechanism of mechanical characteristics increase with the addition of AlN nanoparticles is dispersion hardening.

Synthesis and Structural Characterization of Four Different Concentrations of Ant Nest (Myrmecodia pendens) Collagen Membranes with Potential for Medical Applications.

The purpose of this study was to synthesize and structurally characterize four ant nest membranes in four different concentrations and determine the best concentration that could potentially be used as an alternative material for the production of new collagen barrier membranes. Membranes were created by mixing ant nest extracts at various concentrations of 0.5%, 1%, 1.5%, and 2%, as well as collagen, chitosan, and Polyvinyl Alcohol (PVA) using a film casting. A Universal Testing Machine (UTM) was used to evaluate mechanical properties including elastic modulus, tensile strength, maximum elongation, elongation at break, and maximum force. Water absorption was performed, FTIR was used for functional group identification, and morphology was examined using SEM. Additionally, EDS was used to identify the composition and distribution of elements in membranes. Statistical analysis was conducted using ANOVA (analysis of variance) and post hoc testing with a significance level of p <0.01 for quantitative data. The results showed that the mechanical properties produced the following mean (standard deviation): elastic modulus 0.87 Mpa (0.11), tensile strength 16.32 N/mm2 (2.46), maximum elongation 4.96% (1.72), elongation at break 5.23% (1.87), and maximum force 22.50 N (5.06). The average water absorption capacity of all four membranes had a p-value <0.01. FTIR spectrum showed various peaks corresponding to functional groups, while SEM results indicated a homogeneous mixture. EDS analysis confirmed that the addition of ant plant extract at 0.5%, 1%, and 1.5% resulted in the presence of elements C, O, and Ca. Meanwhile, membranes prepared with 2% concentration had a different composition, namely C, O, Ca, and Na. Increasing the concentration of ant nest affects the values of the membrane's mechanical properties parameters, including the elastic modulus (0.87 Mpa), tensile strength (16.32 N/mm2), maximum elongation (4.96%), elongation at break (5.23%), and maximum force (22.50 N). The average membrane absorption of water (p value <0.01) was also affected. SEM images showed homogeneous mixing, and membrane EDS results consisted of C, O, and Ca composition. However, there was no effect on FTIR functional groups. The anthill membrane with a 1% concentration has the potential to serve as an alternative membrane in guided tissue regeneration.

Comparison of Dental Zirconium Oxide Ceramics Produced Using Additive and Removal Technology for Prosthodontics and Restorative Dentistry-Strength and Surface Tests: An In Vitro Study.

The aim of this in vitro study was to determine the mechanical and functional properties of zirconium oxide ceramics made using 3D printing technology and ceramics produced using conventional dental milling machines. Forty zirconia samples were prepared for this study: the control group consisted of 20 samples made using milling technology, and the test group consisted of 20 samples made using 3D printing technology. Their surface parameters were measured, and then their mechanical parameters were checked and compared. Density, hardness, flexural strength and compressive strength were tested by performing appropriate in vitro tests. After the strength tests, a comparative analysis of the geometric structure of the surfaces of both materials was performed again. Student's t-test was used to evaluate the results (p < 0.01). Both ceramics show comparable values of mechanical parameters, and the differences are not statistically significant. The geometric structure of the sample surfaces looks very similar. Only minor changes in the structure near the crack were observed in the AM group. Ceramics made using additive technology have similar mechanical and surface parameters to milled zirconium oxide, which is one of the arguments for the introduction of this material into clinical practice. This in vitro study has shown that this ceramic can compete with zirconium made using CAD/CAM (Computer-Aided Design and Computer-Aided Manufacturing) methods.

Biomechanical analysis of the door-shaped titanium plate in single-level anterior cervical discectomy and fusion

BackgroundAnalyse and discuss the immediate stability of the cervical spine after anterior cervical discectomy and fusion using a door-shaped titanium plate and compare it with the traditional titanium plate, to provide biomechanical evidence for the rationality and effectiveness of the door-shaped titanium plate in clinical applications.MethodsTen adult goat C4/5 vertebral bodies were obtained, and models were prepared using denture base resin. Biomechanical experiments were performed on the specimens before internal fixation. MTS was used to conduct non-destructive biomechanical loading tests in six directions, including flexion, extension, left–right bending, and left–right torsion, recording the range of motion (ROM) and neutral zone (NZ) of each specimen. The specimens were then randomly divided into two groups: the study group was fixed with a door-shaped titanium plate, and the control group was fixed with a traditional titanium plate. ROM and NZ in each direction were measured again. After measurements, both groups were subjected to 0.5 Hz torsion loading with a torque of 2 N m for a total of 3000 cycles, followed by measuring ROM and NZ in six directions once more.ResultsCompared to before fixation, ROM and NZ in both groups significantly decreased in all six directions after fixation, with statistical significance (P < 0.05); after fixation, the study group showed slightly lower values for various mechanical reference parameters compared to the control group, with no statistical significance (P > 0.05); after 3000 torsional loads, both internal fixation groups showed increased ROM and NZ compared to after fixation but to a lower extent, and no screw or titanium plate loosening was observed. Compared to before fixation, the differences were still statistically significant (P < 0.05), with the study group having slightly lower ROM and NZ values in all directions compared to the control group, with no statistical significance (P > 0.05).ConclusionThe door-shaped titanium plate exhibits mechanical properties similar to the traditional titanium plate in all directions, and its smaller size and simpler surgical operation can be used for anterior cervical endoscopic surgery, reducing surgical trauma. It is clinically feasible and deserves further research and promotion.

Goaf risk prediction based on IAOA–SVM and numerical simulation: A case study

In regard to goaf risk prediction, due to the low accuracy and single prediction method, this study proposes a method that combines the improved arithmetic optimization algorithm (IAOA) – support vector machines (SVM) with GoCAD–FLAC3D numerical simulation. Thus, goaf risk is comprehensively predicted. From the perspectives of geological and engineering conditions, eight factors that affect goaf stability and 176 sets of sample data were determined. We utilized eight influencing factors such as rock mass structure, geological structure, and goaf burial depth as inputs, and the goaf risk level as the output. Moreover, an IAOA–SVM goaf risk prediction model was established. The 30 goaf areas of Yangla Copper Mine in Yunnan Province were selected as the research subject. First, the rationality of mechanical parameter values in the numerical model was verified using the parameter inversion method. Second, based on the GoCAD–FLAC3D numerical simulation method, the goaf risk analysis in Yangla Copper Mine was performed. Subsequently, using numerical simulation verification, the goaf filling effect was analyzed. Finally, the prediction results of the IAOA–SVM model were compared with that of other intelligent algorithms. The results indicate that the numerical simulation results of the GoCAD–FLAC3D model are consistent with those of IAOA–SVM and the actual results, which further verifies the effectiveness and superiority of the IAOA–SVM prediction model. Therefore, an innovative approach for goaf risk prediction is developed.

Assessment of Saturation Effect on Hydraulic Fracturing in Sandstone and Thermally Treated Granite

In this study, a set of laboratory experiments was carried out to study the parameters of hydraulic fractures induced in the dry and mineral-oil-saturated rocks and compare them with the geomechanical characteristics of tested samples. We chose sandstone and thermally treated granite as the materials for research. There are very few known studies related to the mechanical and acoustic properties of oil-saturated rocks, and even fewer studies describing, in detail, the parameters of hydraulic fractures generated in oil-saturated rocks. The hydraulic fracture parameters were determined using a set of independent sensors installed to measure the axial deformation of the sample (which is directly related to the aperture of created hydraulic fracture), fluid pressure, fluid volume injected into hydraulic fracture, and localization of acoustic emission (AE) events, generated during the propagation of hydraulic fractures. Our study focuses on the investigation of the influence of rock properties, altered by mineral oil saturation and thermal treatment, on such parameters of hydraulic fracturing as breakdown pressure (BP), fracture aperture, and the resulting roughness of the hydraulic fracture surface. In addition, we studied the influence of injected fluid viscosity on the parameters of created hydraulic fractures. It was revealed that the saturation state caused a reduction in the values of mechanical parameters such as Young’s modulus, compressive strength, and cohesion, and had a similar reducing influence on the breakdown pressure. The values of HF parameters, such as fracture width and the volume of fracturing agent injected into the HF, are higher in the tests for both saturated sandstone and saturated TT granite. However, we found out that thermal treatment of granite samples led to a much more significant reduction in the values of mechanical and acoustic parameters than the mineral-oil saturation procedure because it created a dense network of thermally induced cracks. The results obtained in our laboratory studies can be taken into account in the modeling of hydraulic fracturing in the field.

Assimilation of electronic, elastic, mechanical, optical, and thermal profiles in metal halide perovskite CsPbCl3, for optoelectronic applications

Potential applications for organic free Cs-based perovskite materials include optoelectronics and electronics. To examine the suitability of this material for optoelectronic devices, a thorough investigation of the mechanical, electrical, optical, and thermodynamic properties of CsPbCl3 was carried out using density functional theory with Generalized Gradient Approximation (GGA). For appropriate device applications, we estimated structural and elastic parameters to identify a better agreement of damage tolerance and electrical and optical responses. The values of Young's modulus (E), Bulk modulus (B), and Shear modulus (G) at 0–15 GPa range were found. Similarly, the values of basic mechanical parameters, Poisson's ratio (σ), Cauchy pressure (CP), and Pugh's ratio (B/G) for 0–15 GPa were also calculated. In all cases, the ductile nature of the material was found. Applied stress caused the thermodynamic properties to change. While the Debye temperature decreased as the temperature rose, the values for enthalpy and heat capacity were found to be at their highest for 15 GPa. The free energy, and entropy exhibit slightly erratic behavior. The results promise a real-world tool to tune the optical and elastic properties with applied stress in similar materials.

Comparative Analysis of Waste, Steel, and Polypropylene Microfibers as an Additive for Cement Mortar

This study presents the results of laboratory experiments conducted to determine the mechanical parameters for cement mortar with various quantities of waste fibers, polypropylene microfibers, and steel microfibers. Waste fibers were used as samples and obtained using an end-of-life car tire recycling process. For comparison, samples with the addition of steel and polypropylene microfibers were tested. The same degrees of fiber reinforcement were used for all types of fibers. Ultimately, 22 mixtures of cement mortar were prepared. The aim of this study is therefore to present and compare basic mechanical parameter values. Compressive strength, flexural strength, fracture toughness, and flexural toughness were of particular interest. A three-point bending test was performed on three types of samples, without a notch and with a notch of 4 and 8 mm. The results show that the use of steel microfibers in the cement mortar produces a product with better properties compared to a mixture with steel cord or polypropylene fibers. However, the cement mortar with the steel cord provides better flexural strength and greater flexural toughness factors compared to the cement mortar with polypropylene fibers. This means that the steel cord is a full-value ecological replacement for different fibers.

Comparative Characteristics of Hemp Nanocellulose Extracted by Different Methods

Abstract: The study describes the extraction of nanocellulose from organosolv hemp pulp (OHP) by different methods: acid hydrolysis, oxidation in the medium of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) and in deep eutectic solvent (DES). OHP was obtained from renewable plant material - hemp fibers by extraction with NaOH solution and cooking using a mixture of acetic acid and hydrogen peroxide. SEM and FTIR data confirmed the reduction of cellulosic fibers and the removal of non-cellulosic components from hemp samples during their sequential thermochemical treatment. The data of X-ray structural and thermogravimetric analyzes confirmed that with increasing crystallinity index and resistance of cellulose-containing hemp samples to the influence of temperature, the obtained nanocelluloses are arranged in the following order: OHP – NCD – NCT – NCH. The values of physical and mechanical parameters of hemp nanocelluloses obtained by different methods are compared. It was established that with approximately the same values of the transverse size of hemp nanoparticles, nanocellulose obtained in the process of acid hydrolysis (NСH) has higher values of physical and mechanical parameters than nanocellulose obtained in TEMPO-medium (NCT) and in the DES (NCD).

Physical properties and electronic structure of chalcogenide perovskite BaZrS3 under pressure

A theoretical comprehensive implementing of the structural, elastic, and electronic properties of chalcogenide perovskite BaZrS3 under pressures 0 and 20 GPa is performed by ab-initio calculations included within the density functional theory (DFT). The lattice constants of the BaZrS3 structure are well reproduced from our first-principles calculations, and in excellent agreement with experimental measurements. The electronic parameters indicate that the chalcogenide perovskite BaZrS3 compound has a direct band gap of 1.75 eV. Moreover, the values of mechanical parameters, such as the elastic constant, increased under applied pressure. From the quotient of bulk to shear modulus of B/G, it is found that ductility becomes stronger with the increasing pressure, indicating pressure can effectively improve the ductility of the orthorhombic BaZrS3

Sedimentological and engineering geological features of the Sarmatian limestones along the Black Sea Coast between the capes of Kaliakra and Shabla

This article aims to present the results of geotechnical studies of the main rock complexes that compose the periphery of the Dobrudzha Plateau in the area from Cape Kaliakra to Cape Shabla (Bulgarian Black Sea Coast), directly related to the development of hazardous geological processes. Sediments of the Sarmatian age were studied: carbonate tempestites, Mactra limestones (Karvuna Formation), nubecular (foraminiferal), reef and bioclastic limestones (Odartsi Formation). The corresponding microscopic and petrographic analyses of the studied sediments are also presented. Studies of collapses in caves near Cape Kaliakra show that they occur in friable peloidal limestones, with disturbances following stratification. This is confirmed by laboratory tests of samples showing lower strength indicators, namely in the direction to the layering. The results of laboratory tests of specimens from the sections between the village of Tyulenovo and Cape Shabla, including foraminiferal, reef and bioclastic limestones, show higher values of physical and mechanical parameters compared to limestones at Cape Kaliakra. In the case of the bioclastic limestones, higher strengths are found crosswise to the layering, and in the case of compressive strength, the ratio is double. The obtained data provide valuable information about the engineering geological parameters of the main varieties in which the rock deformations are developed, which can be used in the analysis of slope stability.

PPV Criterion of a Defect Rock Slope under Blasting SV-Waves

In order to estimate the stability of slopes with geological defects during blasting excavations, the dynamic responses of a rock slope with a fault subjected to blasting seismic waves are studied. The SV-component of blasting seismic waves is considered and the fault is simplified as a semi-infinite crack in an unbounded space. In the background of an iron mine in central China, the relation between the stress field and the PPV of the incident wave is analyzed and the function of PPV threshold is deduced using both deterministic and probabilistic methods to evaluate the slope stability. Results show that the PPV threshold increases monotonically with the increasing frequency and reaches the lowest point at around γ1 = 14°, which should be proposed as the PPV threshold. The PPV threshold is with an about 50% failure probability when the mean values of mechanical parameters are taken. On the safe side, a more rigorous PPV threshold with only 5% failure probability is determined as 2.25 cm/s for f ≤ 10 Hz, as 2.25 cm/s-5.02 cm/s for 10 Hz &lt; f ≤ 50 Hz, and as 5.02 cm/s-10.05 cm/s for f &gt; 50 Hz. A through structural surface is likely to occur inside the northern slope once the PPV exceeds the proposed threshold.

Ab initio calculation of mechanical, electronic and optical characteristics of chalcogenide perovskite BaZrS3 at high pressures.

A theoretical examination of the structural, elastic, electronic and optical properties of the chalcogenide perovskite BaZrS3 under pressures of 0 and 20 GPa was performed using density functional theory ab initio calculations. The lattice constants of the BaZrS3 structure are well reproduced from our first-principles calculations and are in excellent agreement with experimental measurements. Moreover, the values of mechanical parameters, such as the elastic constant, increased under applied pressure. The electronic parameters indicate that the chalcogenide perovskite BaZrS3 has a direct band gap of 1.75 eV. To understand the optical response, the real and imaginary parts of the dielectric function of BaZrS3 have been studied, as well as the absorption coefficient, reflectivity and extinction coefficient. The induced pressure is found to enhance the optical parameters in the different energy regions. Our calculations predict that the studied chalcogenide perovskite BaZrS3 could be a candidate in photovoltaic, optoelectronic and mechanical applications.

Quantitative study on impact damage of yellow peach based on hyperspectral image information combined with spectral information

Yellow peaches are graded based on their degree of impact damage to reduce economic losses, and the values of mechanical parameters can be used to characterize the degree of impact damage of them. In this paper, the combined hyperspectral image features and spectral features method was proposed to predict the values of mechanical parameters of yellow peaches. A collision device based on the pendulum principle was built to acquire the mechanical parameters which were maximum force, absorbed energy and average pressure. A hyperspectral imaging system was used to acquire the images of the bruised yellow peaches and the spectral information and color characteristics of images were extracted, respectively. The damage areas of yellow peaches were obtained based on the combined principal component analysis (PCA) and threshold segmentation method. Texture features of the characteristic wavelength images were extracted based on the grey-level co-generation matrix (GLCM). The PLSR models of mechanical parameters were built based on spectral information, image information, and spectral information combined with image information, respectively. The results show that the PLSR models based on spectral information combined with image information are best in prediction the values of damage area and maximum force. However, the PLSR models have not achieved satisfactory performance in prediction the values of absorbed energy and average pressure. To improve the performance of PLSR models of absorbed energy and average pressure, the feature wavelengths were selected by CARS, and the correlation analysis was used between image information and mechanical parameters. The PLSR models were built based on feature spectral information, image feature information, and feature spectral information combined with image feature information, respectively. The results show that the accuracy of all mechanical parameters is significantly improved by the PLSR models based on the feature spectral information combined with the image feature information. The prediction set correlation coefficient (RP) and the root mean square error (RMSEP) of the damaged area, absorbed energy, maximum force and average pressure are 0.928 and 86.632 mm2, 0.826 and 1.469 J, 0.924 and 61.765 N, 0.815 and 0.050 MPa, respectively. The results of the study not only provide a theoretical basis for postharvest grading of fruit, but also provide a reference for analyzing the mechanical properties of fruit.