Uncertainty of digital image correlation under video compression and DSP optimization.

The storage and transmission of videos at high spatial resolution remain a great challenge in image-based optical techniques. The uncertainty of digital image correlation (DIC) was assessed following speckle video compression under High Efficiency Video Coding (HEVC/H.265). First, the evaluation criterion for the DIC accuracy affected by compression was provided. The stability of H.265 video compression in DIC was studied considering different compressed frames under different target quantization parameters (QPs) and compression ratios (CRs). The deformation uncertainty of the DIC itself as affected by H.265 video compression was further investigated through uniform translation and non-uniform sinusoidal deformation performance. Moreover, the optimized digital speckle pattern (DSP) was re-evaluated considering video compression-induced uncertainty. DSPs with parameters of different diameters and randomness were compressed using various QPs and CRs. In addition, DSP evaluation was performed under both translation and non-homogeneous deformation conditions. The feasibility of the re-optimized DSP under H.265 video compression was validated using a defective bending beam, and DSP videos with a speckle size of 8 pixels reached a high CR within an acceptable margin of error.

Three-Dimensional Shape and Deformation Measurements Based on Fringe Projection Profilometry and Fluorescent Digital Image Correlation via a 3 Charge Coupled Device Camera.

We propose a novel hybrid FPP-DIC technique to measure an object's shape and deformation in 3D simultaneously by using a single 3CCD color camera, which captures the blue fringe patterns and red fluorescent speckles within the same image. Firstly, red fluorescent speckles were painted on the surface of the specimen. Subsequently, 12 computer-generated blue fringe patterns with a black background were projected onto the surface of the specimen using a DLP projector. Finally, both the reference and deformed images with three different frequencies and four shifted phases were captured using a 3CCD camera. This technique employed a three-chip configuration in which red-green-blue chips were discretely integrated in the 3CCD color camera sensor, rendering independent capture of RGB information possible. Measurement of out-of-plane displacement was carried out through the implementation of Fringe Projection Profilometry (FPP), whereas the in-plane displacement was evaluated using a 2D Digital Image Correlation (DIC) method by leveraging a telecentric-lens-based optical system. In comparison to the traditional FPP-DIC hybrid methodology, the present approach showed a lower incidence of crosstalk between the fringe patterns and speckle patterns while also offering a corrective for the coupling of the in-plane displacement and out-of-plane displacement. Experimental results for the in-plane cantilever beam and out-of-plane disk comparisons with the traditional 3D-DIC method indicated that the maximum discrepancy obtained between FPP-DIC and 3D-DIC was 0.7 µm and 0.034 mm with different magnifications, respectively, validating the effectiveness and precision of the novel proposed FPP-DIC method.

Flavonoid synthesis in Lamiophlomis rotata from Qinghai-Tibet Plateau is influenced by soil properties, microbial community, and gene expression.

Lamiophlomis rotata is a medicinal plant in Qinghai-Tibet Plateau, in which flavonoid compounds are the major medicinal components. However, it remains unclear how flavonoid metabolism of L. rotata is influenced by soil properties and microbial community. In this study, we collected L. rotata seedlings and rhizosphere soils from five habitats ranging from 3750 to 4270 m of altitude and analyzed the effects of habitat conditions on flavonoid metabolism. The activities of peroxidase, cellulase, and urease were increased with altitude, while those of alkaline phosphatase, alkaline protease, and sucrase were decreased with altitude. Analysis of OTUs showed that the total number of bacterial genera was higher than that of fungal genera. The highest number of fungal genera was 132, and that of bacterial genera was 33 in Batang (BT) town in Yushu County at an altitude of 3880 m, suggesting that the fungal communities may play a critical role in L. rotata rhizosphere soils. Flavonoids in leaves and roots of L. rotata shared a similar pattern, with a trend of increasing levels with altitude. The highest flavonoid content measured, 12.94 mg/g in leaves and 11.43 mg/g in roots, was from Zaduo (ZD) County at an altitude of 4208 m. Soil peroxidases affected quercetin content in leaves of L. rotata, while the fungus Sebacina affected flavonoid content in leaves and roots of L. rotata. The expression of PAL, F3'H, FLS, and FNS genes showed a declining trend in leaves with altitude, while F3H showed an increasing trend in both leaves and roots. Overall, soil physicochemical properties and microbial community affect flavonoid metabolism in L. rotata in Qinghai-Tibet Plateau. The variations in flavonoid content and gene expression as well as their associations with soil factors revealed the complexity of the growth conditions and genetic makeup in L. rotata habitats of Qinghai-Tibet Plateau.

Study on the Compressive Properties of an Elastomeric Porous Cylinder Using 360° Three-Dimensional Digital Image Correlation System.

To study the compressive properties of an elastomeric porous cylinder, a 360° 3D digital image correlation (DIC) system is proposed. This compact vibration isolation table system captures different segments of the object from four different angles and fields of view, enabling a comprehensive measurement of the full surface of the object. To increase the stitching quality, a coarse-fine coordinate matching method is presented. First, a three-dimensional rigid body calibration auxiliary block is employed to track motion trajectory, which enables preliminary matching of four 3D DIC sub-systems. Subsequently, scattered speckle information characteristics guide fine matching. The accuracy of the 360° 3D DIC system is verified through a three-dimensional shape measurement conducted on a cylindrical shell, and the maximum relative error of the shell's diameter is 0.52%. A thorough investigation of the 3D compressive displacements and strains exerted on the full surface of an elastomeric porous cylinder are investigated. The results demonstrate the robustness of the proposed 360° measuring system on calculating images with voids and indicate a negative Poisson's ratio of periodically cylindrical porous structures.

Analysis of flavonoid metabolism during fruit development of Lycium chinense.

Lycium chinense is an important medicinal plant in the northwest of China. Flavonoids are the major pharmacological components of L. chinense fruits. However, flavonoid metabolism during fruit development of L. chinense remains to be studied. Here, we analyzed the change of flavonoid contents, enzyme activity, and gene expression during fruit development of L. chinense. We found that flavonoids, anthocyanins, and catechins are the most important components of L. chinense fruits. Flavonoid content was increased with fruit development and was high at the late developmental stage. PAL, CHS, and F3H enzymes played a significant role in flavonoid accumulation in fruits. Transcriptomic analysis showed that anthocyanin pathway, flavonol pathway, flavonoid biosynthesis, and phenylpropanoid synthesis pathway were the major pathways involved in flavonoid metabolism in L. chinense. Gene expression analysis indicated that PAL1 and CHS2 genes were critical for flavonoid metabolism in L. chinense fruits. These discoveries help us understand the dynamic changes in flavonoids during fruit development and enhance the use of L. chinense fruits.

Internal displacement measurements based on color fluorescent speckle pattern by multispectral stereo-DIC and refractive index correction.

Fluorescent digital image correlation (DIC) is becoming popular for measuring 3D profiles and deformations in external surfaces. However, the simultaneous monitoring of interior layers is highly challenging due to the penetrability and refraction of light using monochromatic fluorescence. We propose a color fluorescent speckle pattern (CFSP) method for measuring the internal displacement of transparent objects based on multispectral stereo-DIC and refractive index correction. During sample fabrication, fluorescent speckle patterns exciting different colors are fabricated on both the surface and interior layers of objects. A virtual color stereo-DIC system is utilized to capture the CFSP on the surface and interior layers simultaneously from two different perspectives. Different color channels are practically equivalent to synchronized monochrome vision systems, having separate CFSP in external and internal measurements. In multispectral stereo-DIC calculation, the external surface is initially reconstructed through one channel of the system even if the surface is non-planar. Based on Snell's law and the CFSP method, the internal layer is then reconstructed and corrected by establishing the geometry of the refractive stereo-DIC through another channel. The relative error of the thickness between two planar layers was proved to decrease from 33.4% to 0.7% after refractive index correction. Further experimental results validate the efficacy of this method for correcting the profile of the non-planar arc profile and determining the internal deformations of disc materials.

A new species of the idiocerine leafhopper genus Chinaocerus Zhang amp; Li (Hemiptera: Cicadellidae) from northwest China, with a checklist and key to species.

A new leafhopper species, Chinaocerus dentatus Zhang sp. nov., is described and illustrated from Qinghai and Gansu Provinces, China. Specimens were collected from willow (Salix sp.). A checklist and key to species of the genus are provided.

The first mitochondrial genome of Creophilus Leach and Platydracus Thomson (Coleoptera: Staphylinidae: Staphylinini) and phylogenetic implications.

Creophilus Leach and Platydracus Thomson are two genera whose members were formerly included in a poorly defined Staphylinus. Both include large-sized rove beetles that can be frequently found in carrion, faeces, and other such rotting materials worldwide. But there are not yet mitochondrial genomes in public databases, which deters scientists from further studies that involve species of these two genera. Here we present the first complete mitochondrial genomes of two typical Palaearctic species, Creophilus maxillosus and Platydracus impotens, which are also the first for the two genera. Additionally, we included the new mitogenomic data in a phylogenetic context using maximum likelihood phylogenetic analyses. Our results confirm the results of previous studies but show that the position of Creophilus, and therefore the monophyly of Staphylinina, could be affected by dataset constitution and model selection.

Dual stereo-digital image correlation system for simultaneous measurement of overlapped wings with a polarization RGB camera and fluorescent speckle patterns.

Simultaneous monitoring of overlapped multi-wing structure by stereo-digital image correlation (stereo-DIC) may be used to quantify insect motion and deformation. We propose a dual stereo-DIC system based on multispectral imaging with a polarization RGB camera. Different fluorescent speckle patterns were fabricated on wings, which emit red and blue spectra under ultraviolet light that were imaged and separated using a polarization RGB camera and auxiliary optical splitting components. The resulting dual stereo-DIC system was validated through translation experiments with transparent sheets and reconstructed overlapped insect wings (cicadas). Dynamic measurements of the Ruban artificial flier indicate the efficacy of this approach to determining real insect flight behavior.

Rediscovery of Perlodinella microlobata Wu, 1938, with notes on Tibetisoperla sclerotica Yan, Chen, Bozdogan & Li, 2022 (Plecoptera: Perlodidae).

Perlodinella microlobata Wu, 1938 is rediscovered in Qinghai and Sichuan provinces with a supplementary description in this paper. Another species collected from Qinghai at the same time, Tibetisoperla sclerotica Yan, Chen, Bozdogan & Li, 2022, is partially revised because the adult female belongs to the chloroperlid genus Sweltsa Ricker, 1943.

Optimization of multiscale digital speckle patterns for multiscale deformation measurement using stereo-digital image correlation.

Simultaneous monitoring of multiple fields of view (FOVs) by multiscale stereo-digital image correlation (stereo-DIC) can quantify the deformation of a material when localized phenomena occur within a larger FOV or moving object. In multiscale deformation measurement via stereo-DIC, optimization of the digital speckle patterns (DSPs) is essential to achieve high accuracy and efficiency. This work optimizes and fabricates multispectral DSPs used for multiple scales. First, an optimization of the DSP for two FOVs is achieved using both spatial modulation and specified spectra. A spatially modulated DSP is compared with two spectral DSPs achieved by visible and ultraviolet-excited blue light. Then, a spatially modulated visible DSP fabricated by an ultraviolet printer overlaid with an ultraviolet-excited blue DSP fabricated by a photosensitive seal is designed for multiscale stereo-DIC measurements of three FOVs. Experiments were performed to illustrate the functionality and utility of this multiscale DSP. Such experimental analyses can supply adequate full-field data to validate localized or kinetic mechanical behavior.

New records and a confirmation of three perlodid species in China, with additional notes and images of Rauserodes epiproctalis (Zwick, 1997)(Plecoptera: Perlodidae).

Three species of the family Perlodidae are newly reported or confirmed for China, Isoperla asiatica Rauser from Arxan, Inner Mongolia Autonomous Region, Isoperla eximia Zapekina-Dulkeit from Changbai Mountain, Jilin Province, and Mesoperlina capnoptera (McLachlan, 1886) from Xinjiang Uygur Autonomous Region. Based on new material, additional taxonomic notes and images of another perlodid stonefly, Rauserodes epiproctalis (Zwick, 1997) is provided.

Digital image correlation with improved efficiency by pixel selection.

With the increase in digital image correlation (DIC) applications, the computational efficiency of DIC is becoming increasingly important. In previous studies, real-time DIC was realized with a relatively small subset. However, a small subset does not always include sufficient gray gradient information. In this paper, a pixel selection strategy is proposed to improve the computational efficiency of DIC further, allowing a real-time deformation measurement with a large subset. Within the subset, zero weight is assigned to unreliable pixels as a way of pursuing maximum efficiency. The modulus of the local intensity gradient vector of each pixel in the reference image is used as the criterion for reliability. Numerical and real experiments conducted to validate the feasibility and effectiveness of the strategy showed that the computational speed of DIC could be improved about 2 times.

A new species of the genus Hilethera Uvarov, 1923 (Orthoptera: Acrididae: Oedipodinae) from China and its complete mitochondrial genome.

The new species, Hilethera xinjiangensis sp. nov. (Orthoptera: Acrididae: Oedipodinae) is described based on specimens collected from Xinjiang, northern China. The new species is similar to H. brevipennis Zheng Lu, 2002 and H. turanica Uvarov, 1925, but differs from: (1) dark brown in general coloration, (2) darker coloration in forewings, (3) forewings longer than H. brevipennis but shorter than H. turanica, (4) cubital area of forewings boarder than H. brevipennis and H. turanica, (5) hind tibiae dark brown with two light yellow pre-basal rings, while dark with one fade pre-basal ring in H. brevipennis and light yellow with three dark rings in H. turanica.In addition, the complete mitogenome of holotype was sequenced using next-generation sequencing technology. The total length of the assembled mitogenome is 16,145 bp, representing 13 protein-coding genes, 22 transfer RNA genes, two ribosomal RNA genes and one noncoding region (D-loop region). The new mitogenome sequence is compared with published Oedipodinae mitogenomes and the phylogenetic relationships within the subfamily are reconstructed. The results infer that the gene cox1 could be a useful marker for higher phylogenetic level, while the genes nd5 and rrnL could be potentially useful markers between closely related species.

Free Water Loss-induced Heterogeneous Residual Strain and Reduced Fatigue Resistance in Root Dentin: A 3-dimensional Digital Image Correlation Analysis.

INTRODUCTION: This study evaluated free water loss-induced residual strain with and without axial compressive loading and assessed the mechanical effect of cyclic loading in fully hydrated and partially dehydrated root dentin. METHODS: Root dentin sections prepared from freshly extracted human premolars were used. Customized 3-dimensional digital image correlation was used to qualitatively and quantitatively analyze the residual strain induced by 2 hours of free water loss in different regions of root dentin. Residual strain in partially dehydrated root dentin during axial compressive loading was also analyzed using 3-dimensional digital image correlation. The effect of cyclic loading on load to fracture in fully hydrated and partially dehydrated dentin and their fractography were analyzed using micro-computed tomographic imaging. RESULTS: Free water loss resulted in a heterogeneous distribution of residual strain and an overall formation of residual compressive strain with areas of tensile strain localized to the root canal and outer dentin. More residual compressive strain was observed in the apical dentin compared with the cervical dentin (P < .05), and more residual shear strain was observed in outer dentin compared with inner dentin (P < .05). Axial loading resulted in an increase in the load-induced compressive strain in the direction perpendicular to dentinal tubules (P < .05). Fully hydrated roots displayed a higher mean (P < .05) and median (P < .05) number of cycles to fracture with microcracks characteristic of toughness. CONCLUSIONS: After free water loss, root dentin displayed an increased formation of heterogenous residual strain, which resulted in increased axial compressive load-induced strain and a decreased resistance to fatigue failure. The effect of free water loss in the loss of mechanical integrity of root-filled teeth needs further investigation.

Camera array-based digital image correlation for high-resolution strain measurement.

Digital image correlation (DIC) is a well-known technique for non-contact, non-destructive, full-field deformation measurement in experimental solid mechanics. Although DIC has been widely used in science and engineering, the resolution of strain measurement with DIC is limited by imaging resolution and is much lower than that obtained with a strain gauge. To achieve a breakthrough in strain measurement using DIC, a camera array-based DIC method is proposed herein for high-resolution strain measurement. Twenty-five industrial cameras were assembled into a plane array, with each camera capturing a part of the specimen. A novel calibration-based image stitching method is proposed and was applied to these images and their corresponding displacement fields. The strain field was then calculated based on the stitched displacement fields. The use of the camera array greatly improved the measurement spatial resolution of DIC and made high-resolution strain measurement possible. Both static error analysis and four point-bending experiments were performed to demonstrate the feasibility and effectiveness of the proposed method, and a full-field strain resolution of 10 µ ε was achieved.

Whole-field macro- and micro-deformation characteristic of unbound water-loss in dentin hard tissue.

High-resolution deformation measurements in a functionally graded hard tissue such as human dentin are essential to understand the unbound water-loss mediated changes and their role in its mechanical integrity. Yet a whole-field, 3-dimensional (3D) measurement and characterization of fully hydrated dentin in both macro- and micro-scales remain to be a challenge. This study was conducted in 2 stages. In stage-1, a stereo-digital image correlation approach was utilized to determine the water-loss and load-induced 3D deformations of teeth in a sagittal section over consecutively acquired frames, from a fully hydrated state to nonhydrated conditions for a period up to 2 hours. The macroscale analysis revealed concentrated residual deformations at the dentin-enamel-junction and the apical regions of root in the direction perpendicular to the dentinal tubules. Significant difference in the localized deformation characteristics was observed between the inner and outer aspects of the root dentin. During quasi-static loadings, further increase in the residual deformation was observed in the dentin. In stage-2, dentin microstructural variations induced by dynamic water-loss were assessed with environmental scanning electron microscopy and atomic force microscopy (AFM), showing that the dynamic water-loss induced distention of dentinal tubules with concave tubular edges, and concurrent contraction of intertubular dentin with convex profile. The findings from the current macro- and micro-scale analysis provided insight on the free-water-loss induced regional deformations and ultrastructural changes in human dentin.

Optimized digital speckle patterns for digital image correlation by consideration of both accuracy and efficiency.

The technique of digital image correlation (DIC), which has been widely used for noncontact deformation measurements in both the scientific and engineering fields, is greatly affected by the quality of speckle patterns in terms of its performance. This study was concerned with the optimization of the digital speckle pattern (DSP) for DIC in consideration of both the accuracy and efficiency. The root-mean-square error of the inverse compositional Gauss-Newton algorithm and the average number of iterations were used as quality metrics. Moreover, the influence of subset sizes and the noise level of images, which are the basic parameters in the quality assessment formulations, were also considered. The simulated binary speckle patterns were first compared with the Gaussian speckle patterns and captured DSPs. Both the single-radius and multi-radius DSPs were optimized. Experimental tests and analyses were conducted to obtain the optimized and recommended DSP. The vector diagram of the optimized speckle pattern was also uploaded as reference.

Noninvasive, three-dimensional full-field body sensor for surface deformation monitoring of human body in vivo.

Noninvasive, three-dimensional (3-D), full-field surface deformation measurements of the human body are important for biomedical investigations. We proposed a 3-D noninvasive, full-field body sensor based on stereo digital image correlation (stereo-DIC) for surface deformation monitoring of the human body in vivo. First, by applying an improved water-transfer printing (WTP) technique to transfer optimized speckle patterns onto the skin, the body sensor was conveniently and harmlessly fabricated directly onto the human body. Then, stereo-DIC was used to achieve 3-D noncontact and noninvasive surface deformation measurements. The accuracy and efficiency of the proposed body sensor were verified and discussed by considering different complexions. Moreover, the fabrication of speckle patterns on human skin, which has always been considered a challenging problem, was shown to be feasible, effective, and harmless as a result of the improved WTP technique. An application of the proposed stereo-DIC-based body sensor was demonstrated by measuring the pulse wave velocity of human carotid artery.

Resolving the taxonomic conundrum in Graphoderus of the east Palearctic with a key to all species (Coleoptera, Dytiscidae).

The Holarctic diving beetle genus Graphoderus (Dytiscinae, Aciliini) contains relatively few and well-known species but these may still be difficult to identify based on external characters. A taxonomic problem in the eastern Palearctic was discovered that relates to the Palearctic Graphoderus zonatus (Hoppe, 1795) and the Nearctic Graphoderus perplexus Sharp, 1882. Based on qualitative and quantitative characters, especially on male genitalia which have been poorly studied in the past, it is shown that eastern Palearctic specimens identified by previous authors as either of the two species in fact belongs to a third species. The synonymized name Graphoderus elatus Sharp, 1882, is reinstated as a valid species (stat. n.) and a lectotype is designated from the mixed syntype series. The male genitalia of all known Graphoderus species have been examined and an illustrated identification key to the genus is provided. The three species in the complex of focus, Graphoderus elatus, Graphoderus zonatus and Graphoderus perplexus are found to have allopatric distributions; Graphoderus perplexus in the Nearctic region, Graphoderus zonatus in the west Palearctic region and eastwards to the Yenisei-Angara river and Graphoderus elatus east of the Yenisei-Angara river. All previous records of either Graphoderus zonatus or Graphoderus perplexus in the east Palearctic, east of the Yenisei-Angara river turned out to be misidentified Graphoderus elatus. This conclusion also brings with it that dimorphic females, thought only to be present in the single subspecies Graphoderus zonatus verrucifer (CR Sahlberg, 1824), proved to be present also in a second species, Graphoderus elatus. The dimorphic female forms is either with dorsally smooth elytra and pronotum or conspicuously granulated elytra and wrinkly pronotum. As has been shown in Graphoderus zonatus verrucifer there is a correlation between the occurrence of granulate female forms in a population and an increase in the number of adhesive discs on pro- and mesotarsus in males within Graphoderus elatus.