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Carbon-fiber-reinforced polymer (CFRP) composites are widely used in lightweight structures because of their high specific strength, specific modulus, and low coefficient of thermal expansion. Additionally, the unidirectionally arrayed chopped strand (UACS) laminates have excellent mechanical properties and flowability, making them suitable for fabricating structures with complex geometry. In this paper, the damage process of UACS quasi-isotropic laminates under tensile load was tested using acoustic emission detection technology. The mechanical properties and damage failure mechanism of UACS laminates were studied combined with finite element calculation. By comparing and analyzing the characteristic parameters of acoustic emission signals such as amplitude, relative energy, and impact event, it is found that acoustic emission behavior can accurately describe the damage evolution of specimens during loading. The results show that the high-amplitude signals representing fiber fracture in continuous fiber laminates are concentrated in the last 41%, while in UACS laminates they are concentrated in the last 30%. In UACS laminates, more of the damage is caused by matrix cracks and delamination with medium- and low-amplitude signals, which indicates that UACS laminates have a good suppression effect on damage propagation. The stress–strain curves obtained from finite element analysis agree well with the experiment results, showing the same damage sequence, which confirms that the model described in this research is reliable. [ABSTRACT FROM AUTHOR]

Herein, a twin-boom, inverted V-tailed unmanned aerial vehicle (UAV) featuring a foldable bi-wing configuration is proposed for logistics and transportation applications. We employed the Navier–Stokes solver to numerically simulate steady, incompressible flow conditions. By examining the effects of key design parameters on aerodynamic characteristics and bypass flow fields in a two-dimensional state, we were able to suggest a more optimized foldable wing design. Building on the two-dimensional analysis, we performed aerodynamic assessments of the three-dimensional aircraft geometry. Our results indicated that appropriate wing and gap parameters can significantly enhance lift characteristics, maintaining high lift even during large-angle flights. Specifically, when compared to a mono-wing, the lift coefficient of the bi-wing increased by 27.1% at a 14° angle of attack, demonstrating the effectiveness of our wing-and-gap design. Optimal aerodynamic performance was achieved when the gap distance equalled the chord length in both flow and vertical directions. Further, the right combination of airfoil configuration, wing axes angle, and wingspan can improve flow field aerodynamic characteristics, while also enhancing the wing's stall capacity. The lift coefficient reached its maximum value at an angle of attack of 15°, which has the potential to reduce takeoff and landing distances, thereby enhancing the UAV's overall safety. [ABSTRACT FROM AUTHOR]

Simple Summary: African swine fever (ASF) causes acute hemorrhagic disease in domestic pigs. This disease causes huge economic losses worldwide, and there are no safe and effective vaccines. The ASF virus (ASFV) has at least 68 structural proteins. One of these is CD2v, an outer envelope protein usually used as a target for ASF vaccine development. However, the effective immunological regions of this protein have not been fully characterized. Herein, we used monoclonal antibodies to identify a novel B cell epitope located in the intracellular region of CD2v. Importantly, the epitope can elicit both humoral and cellular immune responses in a mouse model. This study provides new insights into ASF epitope vaccine development. The African swine fever virus (ASFV) causes high mortality in domestic pigs. ASFV encodes an important protein target for subunit vaccine development, CD2v, but its most effective immunological regions are not known. Herein, we generated a monoclonal antibody (mAb) named IF3 by immunizing mice against the intracellular region of the CD2v protein (CD2v-IR). 1F3 specifically recognized CD2v, which is expressed transiently in transfected Sf9 cells and also in inactivated ASFV-infected porcine alveolar macrophage (PAM) cells. The epitope recognized by 1F3 is 264EPSPREP270, which is highly conserved in ASFV genotypes. Immunization of mice with this epitope elicited an increased IgG response, including IgG1 and IgG2a subtypes, and also increased CD8+ T cells and cytokine expression. Overall, these results indicate that this epitope induces both humoral and cellular immune responses that may be used for ASFV-related subunit vaccine design and development. [ABSTRACT FROM AUTHOR]

Herceptin (or trastuzumab) is an important therapeutic monoclonal antibody (mAb) used in the treatment of HER2‐positive breast cancer. Real‐time counting and characterization of Herceptin is a fundamental step in the field of disease‐related diagnosis and therapy. Solid‐state nanopore‐based biosensors have been proved to hold great potential in characterizing the properties of proteins at the single‐molecule level for in vitro diagnosis. Here, the label‐free detection and detailed translocation dynamics study of Herceptin using solid‐state nanopores are demonstrated. By constricting nanopore size close to the size of Herceptin, the detection sensitivity and temporal resolution have been significantly improved, allowing the delicate probing of the structural information of single‐molecule Herceptin. Therefore, three types of Herceptin translocation events are identified through nanopores, single‐level, multi‐level and spike‐like events, emerged at different voltages regimes, indicating the unfolding kinetics of Herceptin under electric field. The potential influence of a high electric field on complex biomolecules is highlighted and a novel prospective platform is provided for label‐free detection of single‐molecule therapeutic monoclonal antibodies via solid‐state nanopores as a miniaturized biomedical device. [ABSTRACT FROM AUTHOR]

The ball screw is a vital component in the feed drive systems of machine tools. It is susceptible to thermal errors that significantly impact its accuracy. Current thermal error modeling methods for ball screws face significant challenges in achieving full-time series prediction. Furthermore, these methods impose stringent requirements for a complex temperature data collection process, further constrained by the compact structure of machine tools. Additionally, valuable working condition data in thermal error prediction remains underutilized. This paper proposes a new hybrid-driven model that combines mechanism and data-driven approaches to achieve full-time series thermal error prediction of ball screws. The proposed model utilizes the operating rotational speed as a key input parameter, eliminating the need for temperature collection during the modeling stage and the compensation process. The temperature model is proposed as a mechanism-driven model based on heat transfer theory to calculate the temperature of the thermal sensitive points by utilizing operating rotational speed. The accuracy of the model is validated through thermal characteristic experiments of ball screws under four different working conditions. The data-driven models based on different traditional neural networks are established to predict thermal errors according to the time series temperature data from the temperature model. Moreover, hyperparameters of different neural networks are optimized by the Beetle Antennae Search (BAS). Comparative analysis among different neural network-based hybrid-driven models reveals that the convolutional neural network (CNN) model optimized by BAS consistently exhibits lower absolute errors predominantly below 10 μm, as well as lower root mean squared error (RMSE) and mean absolute error (MAE) values in each working condition. The BAS-CNN model, within the hybrid-driven model framework, is better suited for the full-time series prediction of thermal errors in ball screws. The BAS-CNN model is a foundation for thermal error compensation by utilizing working condition data. [ABSTRACT FROM AUTHOR]

A growing set of Chinese scholars view field philosophy as a new approach toward philosophical research. Field philosophy offers a meta-philosophy, and a methodology, but most importantly an institutional response to philosophical relevance. As the latter, field philosophy means implementing a philosophical practice at the organizational level. This is the essential characteristic of field philosophy that distinguishes itself from all other philosophies and philosophical practices. China does not have a tradition of field philosophy, but should embrace this approach as consistent with its Marxist orientation, while recognizing that the institutionalization of field philosophy will occur differently in the West and China. [ABSTRACT FROM AUTHOR]

Abstract Intelligent sampling can be used to influence the efficiency of surface geometry measurement. With no design model information provided, reconstruction from prior sample points with a surrogate model has to be carried out iteratively, thus the next best sample point(s) can be intelligently selected. But, a lack of accurate and fast reconstruction models hinders the development of intelligent sampling techniques. In this paper, a smart surrogate model based on free-knot B-splines is used for intelligent surface sampling design with the aid of uncertainty modelling. By implementing intelligent sampling in a Cartesian, parametric or specific error space, the proposed method can be flexibly applied to reverse engineering and geometrical tolerance inspection, especially for high-dynamic-range structured surfaces with sparse and sharply edged features. Extensive numerical experiments on simulated and real surface data are presented. The results show that this parametric model-based method can achieve the same or higher sampling efficiency as some recent non-parametric methods but with far less computing time cost. Highlights • A free-knot B-spline (FKBS) modelling-based adaptive sampling strategy was developed. • This strategy efficiently works for the measurement of smooth and sharply-edged surfaces. • This strategy shows comparable sample saving performance to the latest techniques. • With far less computing time, this strategy meets practical requirement in industry. [ABSTRACT FROM AUTHOR]

Abstract A novel architecture of graphene oxide wrapped copper spheres (Cu/GO) is proposed for fabricating high wear-resistant Cu-based composites. Tribological results indicate that GO shell layers present an exceptional strengthening efficiency surpassing conventional nanoparticle, fiber and nanosheet reinforcements for Cu-based materials reported to date. The friction torque of the composites shows a load-insensitive behavior stabilized at 0.26–0.41 Nm. Such good tribological performance is ascribed to integrated effects including strong metal/GO interfacial coupling, uniform distributed GO, and the GO-assisted tribofilm formed on ridges and asperities of wear tracks. The fabrication strategy is convenient, low cost, easily scalable, and can be expanded to the preparation of other metal/GO materials. Graphical abstract Image 1 Highlights • A composite is fabricated from novel architecture of GO wrapped Cu spheres. • GO shell layers present an exceptional tribological strengthening efficiency. • This is ascribed to the strong metal/GO interface and uniform GO distribution. • GO-assisted tribofilm formed on asperities also promotes tribological properties. • The fabrication strategy is convenient, low cost, and easily scalable. [ABSTRACT FROM AUTHOR]

Abstract This study reports on fretting friction and wear behaviors of steel/copper test pairs lubricated in the nanodiamond-dispersed oil with a flat-on-flat configuration at 106 N. After 4 × 104 fretting cycles, results show that an addition of 0.2 wt% nanodiamonds in oil reduces the friction torque from 0.12 Nm of pure oil to 0.08 Nm. Particularly, the wear volume is decreased by an order of magnitude compared to that tested in pure oil. Microstructural analyses reveal that the substantial friction and wear reduction is attributed to collective effects including the formation of robust nanodiamond-strengthened tribofilms, wear-induced twin boundaries, and good mechanical bonding interface between tribofilms and the substrate. Highlights • Dispersing nanodiamonds (NDs) in oil dramatically reduced friction for fretting. • Wear volume was decreased by an order of magnitude after dispersing NDs in oil. • This can be attributed to formation of a robust nanodiamond-strengthened tribofilm. • Wear-induced TBs in the substrate also promoted to the high wear resistance. [ABSTRACT FROM AUTHOR]

The low-speed shaft-bearing system has been used in many navigation equipment, and its rotation error can directly affect the navigation accuracy. Currently, due to the emergence of super precision bearings, bearing accuracy has exceeded the overall accuracy level of the shaft-bearing system, and the other parts' (such as shaft, housing) errors become the main factors to hinder the improvement of low-speed rotation accuracy. To solve this problem, this paper proposed a low-speed rotation error prediction method to determine the key tolerances, which can be used to improve the rotation accuracy of shaft-bearing system. Firstly, the formation mechanism of the low-speed rotation error is introduced. Secondly, the spatial pose kinematic model of the shaft-bearing system considering the assembly deviation is established in low-speed rotational movement. Thirdly, the coupled model of assembly deviation and static mechanics in shaft-bearing system is established. Fourthly, based on the above two models, the low-speed rotation error prediction method is proposed, and then verified with the measurement on a rigid shaft-bearing system. Finally, based on it, the effects of bearing installation errors (caused by the part's tolerances) on the rotation error can be quantitatively analyzed to determine the key tolerances, which can be largely useful for improving the rotation accuracy of the shaft-bearing system. • Spatial pose kinematic model of the shaft-bearing system is established. • Coupled model of assembly deviation and quasi-static mechanics is established. • Model-based low-speed rotation error prediction method is proposed. • Influences of the assembly deviation on the low-speed rotation error are analyzed. [ABSTRACT FROM AUTHOR]

In this paper, a tolerance representation model for generating tolerance specification schemes and corresponding tolerance zones is proposed to meet the requirement of the representation of tolerance information semantics. This model is hierarchically organized and consists of five layers. They are component, geometric feature, variational geometric constraint, tolerance specification scheme, and tolerance zone layers. The mating relations between components in the component layer, the mating relations between geometric features in the geometric feature layer, the variational geometric constraints between geometric features in the variational geometric constraint layer, the tolerance specification schemes of component in the tolerance specification scheme layer, and the tolerance zones of tolerance specification schemes in the tolerance zone layer are formally defined by one or more adjacency matrices, respectively. Based on the model, a method for generating tolerance specification schemes for component and their resultant tolerance zones is designed. This method shows how to adopt a top-down strategy to carry out tolerance specification for an arbitrary assembly designed in a CAD system. The paper also provides a practical example to illustrate how the method works. [ABSTRACT FROM AUTHOR]

Self-healing can protect materials from diverse damages, but is intrinsically difficult in metals. This paper demonstrates a potential method through a simultaneous decomposition and oxidation of Ti 3 SiC 2 to achieve healing of stress cracking on the surface of nickel aluminum bronze (NAB)/Ti 3 SiC 2 nanocrystalline composites during fretting wear. At the finest nanocrystalline materials, a crack recovery would be attained at 76.5%. The repetitive fretting wear leads to a modest amount of ‘flowability’ of Ti 3 SiC 2 toward the crack, facilitating crack recovery. Along with the wear-triggered self-healing, the NAB/Ti 3 SiC 2 shows an improved tribological performance with the stable decreased friction torque due to the formation of lubrication TiO 2 oxide. [ABSTRACT FROM AUTHOR]

Many wear failures are caused by a combination of fretting wear and sliding wear. In this study, the torsional fretting and torsional sliding wear properties of CuNiAl against 42CrMo4 were comparatively investigated under dry condition using a flat on flat contact tester. Experimental results showed that the sliding friction coefficients declined more dramatically than the fretting friction coefficients when the normal load increased. The fretting wear rate was lower than the sliding wear rate, which was partly due to the solid lubrication effect of the wear debris and strain hardening of the worn surfaces. The dominant wear mechanisms for the fretting tests were oxidation, cracks and delamination, while for the sliding tests were abrasion combined with plastic deformation. [ABSTRACT FROM AUTHOR]

The present research describes a study to explore the possibility to improve the wear resistance by healing microcracks that initiated under fretting wear. To this aim Ti 3 SiC 2 coatings prepared at different plasma powers (33 and 34 kW) were investigated comparatively under fretting. The results showed that the amount of Ti 3 SiC 2 phases was higher at the lower plasma power, leading to a major difference on fretting wear properties. Coatings with a higher content of Ti 3 SiC 2 phases exhibited a remarkable decrease in the friction coefficient and an enhancement in the wear resistance. The enhanced wear resistance was mainly attributed to the healed cracks by selective oxidation of Ti 3 SiC 2 . The reduced friction coefficient was strongly related to the formation of tribo-induced oxides. [ABSTRACT FROM AUTHOR]

In this paper, an ontology-supported case-based reasoning approach for computer-aided tolerance specification is proposed. This approach firstly considers the past tolerance specification problems and their schemes as previous cases and the new tolerance specification problems as target cases and uses an ontology to represent previous and target cases. Then certain ontology-based similarity measure is used to assess the similarity between the toleranced features of target and previous cases, the similarity between the part features of target and previous cases, and the similarity between the topological relations of target and previous cases. Based on these similarities, an ontology-based similarity measure for computing the similarity between target and previous cases is designed, and an algorithm for establishing such similarity measure with high accuracy and retrieving similar previous cases for a target case with this similarity measure is presented. This algorithm shows how to linearly combine the similarity of toleranced features, the similarity of part features, and the similarity of topological relations to assess the similarity between target and previous cases to implement retrieval of previous cases under the prerequisite of ensuring the highest accuracy of the similarity measure. The paper also reports a prototype implementation of the proposed approach, provides an example to illustrate how the approach works, and evaluates the approach via theoretical and experimental comparisons. [ABSTRACT FROM AUTHOR]

Torsional fretting and torsional sliding wear behaviors of CuNiAl against 42CrMo4 were comparatively investigated in oil, filtered water and artificial seawater. Most experiment parameters except the angular displacement amplitude were set the same for all the tests. Compared with sliding tests, the averaged fretting friction torque of fretting tests tended to be higher but the wear rate was much lower, resulting from the influence of wear trace roughness, lubricant penetration behavior, surface strain hardening and third body effect. The fretting and sliding wear traces were mainly characterized by abrasion. The fretting wear traces under the filtered water and artificial seawater lubrications were also scattered with cracks and delamination, resulting from the frequent shear stress and poorer lubrication condition. [ABSTRACT FROM AUTHOR]

Fretting wear of nickel-aluminum bronze (NAB) alloys and 15 wt% Ti 3 SiC 2 /NAB composites against the 42CrMo4 steel was studied through flat-on-flat testing at oil-lubrication conditions with varying free-water contents (0, 26.8, 52.3 and 76.7 wt%). Tribological test results revealed that the addition of Ti 3 SiC 2 substantially reduced the fretting wear and the friction coefficient of NAB alloys at all testing conditions, which could be attributed to high absorption of the fracture energy on the wear track by the deflection of fatigue cracks along Ti 3 SiC 2 /NAB interfaces. In addition, microstructural analyses and dissipative particle dynamics simulations revealed that high free-water contents facilitated the propagation of cracks and break of the oil film, which resulted in the transformation of wear mechanisms from abrasion and mild oxidation at the low free-water contents to abrasion, deformation and oxidation at the high contents. Accordingly, the steady-state friction coefficient of Ti 3 SiC 2 /NAB composites increased from 0.09 to 0.17 as the free-water content increased from 0 to 76.7 wt%. [ABSTRACT FROM AUTHOR]

This work investigated the effect of sintering temperatures (600–750 °C) on mechanical and tribological behaviors of nickel-aluminium bronze (NAB) alloys developed by gas atomization and spark plasma sintering. Results indicated an increase of the volume fraction of B2-type NiAl precipitates with increasing sintering temperature, leading to an improvement of the yield strength and the wear resistance. Specifically, detailed microstructural analyses of sintered NAB alloys at 750 °C showed the presence of ultrafine grains with an average size of 367 nm, nanoscale twins with a volume fraction of 11.7% and dislocations with a density of 1.3 ± 0.1 × 10 14 m −2 . A much higher yield strength of 620 MPa was obtained in NAB, if compared to that of conventional cast counterparts (280–440 MPa). Estimations of strengthening mechanisms suggested the predominant mechanism of grain boundary strengthening (335 MPa) for NAB alloys with contributions from precipitate strengthening (54 MPa), dislocation strengthening (75 MPa), twin boundary strengthening (89 MPa) and solid solution strengthening (50 MPa). Moreover, dislocations was blocked at twin boundaries to form complex dislocation barriers and networks, further contributing to the high strength. The high wear resistance of NAB could be ascribed to the reduction of the local stress around crack tips due to the high elastic modulus mismatch ( E NiAl / E Cu ), and to the crack extension toughening near the interface of the matrix and the precipitate caused by the high plastic mismatch ( σ NiAl / σ Cu ). [ABSTRACT FROM AUTHOR]

Torsional fretting exists in many engineering applications and the contact configurations have great effects on the fretting wear behavior. Influence of angular displacement amplitudes and normal loads on torsional fretting were investigated under flat on flat contact. Friction torque versus angular displacement amplitudes and friction torque versus number of cycle curves were used to analyze the fretting kinetics behavior. Evolution of accumulated dissipated energy ( E T ) and wear volume ( V W ) with the change of angular displacement amplitudes were analyzed. The wear mechanisms were studied base on examinations under optical microscope (OM), scanning electron microscope (SEM) and Energy Dispersive X-Ray Spectroscopy (EDX). It is found that E T and V W analysis helps to reveal the variation of failure mechanisms with the change of angular displacement amplitudes. Uneven spread of wear scar under mixed slip resulted from the effects of debris on stress-redistribution. Similar to ball on flat contact, the torsional fretting wear mechanism under flat on flat contact was a combination of deformation, cracks, delamination abrasive wear and oxidation wear. [ABSTRACT FROM AUTHOR]

Influence of surface topography on torsional fretting under flat-on-flat contact were investigated. Contact surfaces of the lower specimens were prepared by milling with different initial surface roughness while the upper specimens were polished. Results indicate that with the increase of surface roughness, friction torque and accumulated dissipated energy present a first increase and then decrease tendency and are higher when the texture is perpendicular to the relative movement direction. The wear volume and wear rate present increasing and decreasing tendencies separately for textures parallel and perpendicular to the relative movement direction, and they are higher when the texture is parallel to the relative movement direction. The results can provide guidance for the initial surface design to reduce fretting wear. [ABSTRACT FROM AUTHOR]

Representing the semantics of the interaction of two or more tolerances (i.e., composite tolerance) explicitly to make them computer-understandable is currently a challenging task in computer-aided tolerancing (CAT). We have proposed a description logic (DL) ontology-based approach to complete this task recently. In this paper, the representation of the semantics of the composite positional tolerance (CPT) for patterns of holes (POHs) is used as an example to illustrate the proposed approach. This representation mainly includes representing the structure knowledge of the CPT for POHs in DL terminological axioms; expressing the constraint knowledge with Horn rules; and describing the individual knowledge using DL assertional axioms. By implementing the representation with the web ontology language (OWL) and the semantic web rule language (SWRL), a CPT ontology is developed. This ontology has explicitly computer-understandable semantics due to the logic-based semantics of OWL and SWRL. As is illustrated by an engineering example, such semantics makes it possible to automatically check the consistency, reason out the new knowledge, and implement the semantic interoperability of CPT information. Benefiting from this, the ontology provides a semantic enrichment model for the CPT information extracted from CAD/CAM systems. [ABSTRACT FROM AUTHOR]

Semantic similarity measure technology based approach is one of the most popular approaches aiming at implementing semantic mapping between two different CAD model data ontologies. The most important problem in this approach is how to measure the semantic similarities of concepts between two different ontologies. A number of measure methods focusing on this problem have been presented in recent years. Each method can work well between its specific ontologies. But it is unclear how accurate the measured semantic similarities in these methods are. Moreover, there is yet no evidence that any of the methods presented how to select a measure with high similarity calculation accuracy. To compensate for such deficiencies, this paper proposes a method for selecting a semantic similarity measure with high similarity calculation accuracy for concepts in two different CAD model data ontologies. In this method, the similarity calculation accuracy of each candidate measure is quantified using Pearson correlation coefficient or residual sum of squares. The measure with high similarity calculation accuracy is selected through a comparison of the Pearson correlation coefficients or the residual sums of squares of all candidate measures. The paper also reports an implementation of the proposed method, provides an example to show how the method works, and evaluates the method by theoretical and experimental comparisons. The evaluation result suggests that the measure selected by the proposed method has good human correlation and high similarity calculation accuracy. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • JDBM micro-tubes were successfully fabricated by double extrusion. • The grains of JDBM micro-tubes are greatly refined after double extrusion. • The YS, UTS and elongation are all improved significantly after double extrusion. • The high elongation is attributed to the enhanced activation of non-basal slips. Abstract Double extrusion with a large plastic deformation was conducted to fabricate Mg-Nd-Zn-Zr (JDBM) micro-tubes (3.5 mm in outer diameter and 0.25 mm in thickness) with high plasticity for biodegradable vascular stents application. After double extrusion, the grain size was greatly decreased to one seventh of the original size and the basal texture intensity was enhanced slightly. The elongation increases from about 23% for the as-extruded JDBM alloy bar to about 48.8% for the as-extruded micro-tubes, which is a 112% increase by double extrusion. The high elongation is attributed to the enhanced activation of non-basal slips contributed by the significant grain refinement. [ABSTRACT FROM AUTHOR]

Inspired by track-before-detection technology in radar, a novel time-frequency transform, namely polynomial chirping Fourier transform (PCFT), is exploited to extract components from noisy multicomponent signal. The PCFT combines advantages of Fourier transform and polynomial chirplet transform to accumulate component energy along a polynomial chirping curve in the time-frequency plane. The particle swarm optimization algorithm is employed to search optimal polynomial parameters with which the PCFT will achieve a most concentrated energy ridge in the time-frequency plane for the target component. The component can be well separated in the polynomial chirping Fourier domain with a narrow-band filter and then reconstructed by inverse PCFT. Furthermore, an iterative procedure, involving parameter estimation, PCFT, filtering and recovery, is introduced to extract components from a noisy multicomponent signal successively. The Simulations and experiments show that the proposed method has better performance in component extraction from noisy multicomponent signal as well as provides more time-frequency details about the analyzed signal than conventional methods. [ABSTRACT FROM AUTHOR]

We present a novel method for simulating compressible flow on a multitude of Cartesian grids that can rotate and translate. Following previous work, we split the time integration into an explicit step for advection followed by an implicit solve for the pressure. A second order accurate flux based scheme is devised to handle advection on each moving Cartesian grid using an effective characteristic velocity that accounts for the grid motion. In order to avoid the stringent time step restriction imposed by very fine grids, we propose strategies that allow for a fluid velocity CFL number larger than 1. The stringent time step restriction related to the sound speed is alleviated by formulating an implicit linear system in order to find a pressure consistent with the equation of state. This implicit linear system crosses overlapping Cartesian grid boundaries by utilizing local Voronoi meshes to connect the various degrees of freedom obtaining a symmetric positive–definite system. Since a straightforward application of this technique contains an inherent central differencing which can result in spurious oscillations, we introduce a new high order diffusion term similar in spirit to ENO-LLF but solved for implicitly in order to avoid any associated time step restrictions. The method is conservative on each grid, as well as globally conservative on the background grid that contains all other grids. Moreover, a conservative interpolation operator is devised for conservatively remapping values in order to keep them consistent across different overlapping grids. Additionally, the method is extended to handle two-way solid fluid coupling in a monolithic fashion including cases (in the appendix) where solids in close proximity do not properly allow for grid based degrees of freedom in between them. [ABSTRACT FROM AUTHOR]

The application of biochar has been shown to increase crop yields on acidic and low activity soils in the tropics but fewer positive yield responses have been reported for soils of Northern China. In field conditions, the application of biochar can raise the crop yields in dark brown soil of Northern China. This study tested the influence of biochar on the moisture of dark brown soil and the yield of two consecutive maize crops. The readily available water (RAW) content (volumetric water available between -10 kPa and -100 kPa) has been re shown to be increased significantly. The bulk density (BD) has been decreased, but moisture uptake hasn't been affected consistently. Following very high stover application rates, the grain yield has been increased by 5% to 12% because of the application of biochar in 2013 and 2014, which was presumably because biochar mitigated adverse effects of allelochemicals released from the decomposing maize residue. These results indicate that biochar in combination with crop residue can improve the characteristics of soil moisture and the yield of maize. © 2015 Friends Science Publishers [ABSTRACT FROM AUTHOR]

Background: Shenzhen has made great efforts to address the tobacco epidemic in the past decade. This study aims to evaluate the current status of the tobacco epidemic among adolescent in Shenzhen, China. Methods: The multi-stage random cluster sampling method was used in the school-based cross-sectional study in 2019 and a total of 7,423 junior and high school (both senior and vocational) students were recruited. Information on cigarette use was collected by the electronic questionnaire. Logistic regression analysis was used to examine the associations between current cigarette use and associated factors. ORs with their 95% CIs were reported. Results: The prevalence of current cigarette use among adolescents was 2.3%, with boys (3.4%) significantly higher than girls (1.0%). Smoking rates in junior high schools, senior high schools, and vocational senior high schools were 1.0%, 2.7%, and 4.1%, respectively. The results of multivariate logistic regression analysis indicated that gender, age, parental smoking, teachers smoking in schools, friends smoking, exposure to tobacco marketing, and misconceptions about cigarette use were associated factors for adolescent smoking behaviour. Conclusions: The prevalence of current smoking was relatively low among adolescent in Shenzhen, China. Personal characteristics, family, and school were associated with current adolescent smokers. [ABSTRACT FROM AUTHOR]

In this work, the tribological performance and the friction- induced vibration and noise (FIVN) of Ni 3 Al matrix bio-composite surface structures (NMCSS) with different surface texture densities were studied. NMCSS was inspired by biological characteristics and composed of Ni 3 Al alloys and Sn3.0Ag0.5Cu (SAC305) alloys. The results show that the friction film can be formed on the contact surface of NMCSS samples to improve the tribological performance and suppress the FIVN behaviors. However, the surface texture density has the positive impacts on the thickness of friction film, which results in the different tribological performance. The possible relations between the interfacial tribological characteristics of NMCSS and the self-excited vibration have been confirmed by the numerical simulation. It demonstrates that the thickness of friction film on the contact surface can alleviate effectively the occurrence of self-excited vibration. This investigation help us understand the FIVN generation and provide a potential surface design strategy for the engineering application. [Display omitted] • The bio-inspired shell-like composite surface structure is designed. • Effect of surface texture density on the thickness of friction film and the FIVN signals is studied. • The FIVN generation of friction system is studied. • The relationship between the friction film and the self-excited vibration is investigated by the experiments and the numerical analysis. [ABSTRACT FROM AUTHOR]

The automation of tolerance design process and the exchange of tolerance data semantics are currently two of the hottest research topics in computer-aided tolerancing. In previous work, we have proposed a description logic-based approach to implement the automation of the process of tolerance-type design. This approach can not only generate tolerance types automatically in CAD systems, but also ground for the exchange of tolerance data semantics among heterogeneous CAD systems. In this paper, we continue this line of research. We further extend the above approach by using description logic SROIQ( D) to implement the automatic generation of geometric tolerance zones (GTZs) in CAD systems. This extension mainly includes: (1) constructing a meta-model of each type of GTZs with SROIQ( D) concept definition axioms, (2) defining some generation rules of GTZ types in SROIQ( D) concept subsumption axioms according to the constructed meta-model, (3) designing a generation algorithm of GTZs on the basis of the meta-model, the defined rules, and the satisfiability decision algorithm of SROIQ( D) concepts, and (4) implementing the designed algorithm with the use of the second generation web ontology language description logic (OWL 2 DL) ontology-based technologies. This extended approach will further reduce the uncertainty in product tolerance design and lay a solid basis for the future study of the automation of tolerance allocation and analysis and the exchange of tolerance data semantics. [ABSTRACT FROM AUTHOR]

Lack of explicit semantics in the product data to be exchanged among product development systems is a major problem for existing product data exchange standards. To solve this problem, the semantics of product data should be enriched to form a basis for exchanging them. This paper proposes an ontology-based approach to enrich the semantics of variational geometric constraint data, one of the most important kinds of product data in product development systems. In this approach, an ontology for variational geometric constraint specifications is constructed by formalizing the specifications in the variational geometric constraint network theory in Web Ontology Language 2 Description Logic (OWL 2 DL) and Semantic Web Rule Language (SWRL). This ontology has rigorous computer-interpretable semantics due to the mathematic logic-based semantics of OWL 2 DL and SWRL. It is capable of providing a semantic enrichment model for the variational geometric constraint data extracted from CAD systems. The ontology is implemented with the use of the OWL 2 DL/SWRL ontology based technologies. As the benefits of the implemented ontology, consistency checking, knowledge reasoning and semantic queries can be automatically performed. These benefits will lay a basis for further exchanging the explicit semantics of variational geometric constraint data among heterogeneous product development systems. [ABSTRACT FROM AUTHOR]

[Objective] This study was conducted to investigate the effects of traditional fertilization and formula fertilization by soil testing on the chemical forms of nitrogen in dark brown soil and its distribution in different aggregates. [Method] A physico-chemistry method was adopted in a comparative study on the chemical forms of nitrogen and their distribution in different-sized aggregates of dark brown soil under traditional fertilization and formula fertilization by soil testing respectively. [Result] Compared with traditional fertilization in spring and autumn, the formula fertilization by soil testing averagely decreased, the total nitrogen in soil by 23.2% in spring and by 20% in autumn in the soil layer of 0-20 cm, by 48.8% in the layer of 20-40 cm. Ammonium nitrogen was so sensitive to the methods of fertilization that the content of ammonium nitrogen was reduced much more under formula fertilization by soil testing in autumn than under traditional fertilization. Nitrogen in soil under traditional fertilization pattern was mainly distributed in the aggregates of 0-0.25 and 0.5-1 mm, while in formula fertilization by soil testing it was mainly distributed in the aggregates of 0.25-0.5 and 0-0.25 mm. [Conclusion] The study proved that formula fertilization by soil testing helped to reduce the risk of nitrogen pollution and had huge effects on the chemical forms and distribution of nitrogen in different aggregates in dark brown soil. [ABSTRACT FROM AUTHOR]

Background: Shenzhen has made great efforts to address the tobacco epidemic in the past decade. This study aims to evaluate the current status of the tobacco epidemic among adolescent in Shenzhen, China. Methods: The multi-stage random cluster sampling method was used in the school-based cross-sectional study in 2019 and a total of 7,423 junior and high school (both senior and vocational) students were recruited. Information on cigarette use was collected by the electronic questionnaire. Logistic regression analysis was used to examine the associations between current cigarette use and associated factors. ORs with their 95% CIs were reported. Results: The prevalence of current cigarette use among adolescents was 2.3%, with boys (3.4%) significantly higher than girls (1.0%). Smoking rates in junior high schools, senior high schools, and vocational senior high schools were 1.0%, 2.7%, and 4.1%, respectively. The results of multivariate logistic regression analysis indicated that gender, age, parental smoking, teachers smoking in schools, friends smoking, exposure to tobacco marketing, and misconceptions about cigarette use were associated factors for adolescent smoking behaviour. Conclusions: The prevalence of current smoking was relatively low among adolescent in Shenzhen, China. Personal characteristics, family, and school were associated with current adolescent smokers. [ABSTRACT FROM AUTHOR]

[Display omitted] • An ordered patterning composite (OPC) structures are bio-inspired by shells. • The surface texture density promotes the formation of lubricating film. • The excellent tribological properties of OPC structures depends on the materials properties, components, and surface texture density. • The self-compensating lubrication behaviors are explained by theoretical models and experiments. Composite surface structures inspired by biological characteristics have the potential to strengthen the synergistic effects of surface micro-textures and solid lubricants by improving their tribological properties. This investigation sought to discuss the lubrication mechanisms by designing bio-inspired shell-like Ni 3 Al matrix composite surface structure, in which an ordered patterning composite (OPC) structures contained Ni 3 Al matrix and solid lubricants Sn-3.0Ag-0.5Cu(SAC305) alloys. Reciprocating dry sliding tests of OPC structures with different surface texture densities against high-carbon steel balls were performed, and the results were compared to those for orderly pattern (OP) structures without the SAC305 alloy. The results showed that the appropriate volume fraction of the SAC305 alloy should further promote decreases in the friction coefficients and wear losses. This could be attributed to the self-compensating lubrication behaviors of the SAC305 alloy. It formed a lubricating film with a certain area and thickness, which should be controlled by the material properties and components of the bio-composite surface structures, as well as the surface texture density. Additionally, methods based on a combination of theoretical models and experimental measurements further confirmed that the soft and hard materials of the OPC structure played different roles. The soft material (SAC305 alloy), which had a high surface energy and low hardness, had a better material transfer tendency than the hard material (Ni 3 Al matrix), which had a low surface energy and high hardness. This resulted in the formation of a transfer film and the occurrence of self-compensating lubrication behaviors. [ABSTRACT FROM AUTHOR]

Abstract: Tactile scanning method is widely used for curved surface topography measurement. Owing to the non-linear transformation process from the vertical translational displacement of the measured point (the coordinates of stylus tip) to the angular displacement of the stylus tip (measured by the cylindrical diffraction grating), the non-linear error exists within the horizontal and vertical coordinates of the obtained sampling data. And the non-linear error normally rises with the increasing of the measurement range. To solve the non-linear problem, a tactile scanning measurement system based on cylindrical grating interference principle is constructed for curved surface topography; the originations of the non-linear error in this system are analyzed, the error compensation model is established, through which the non-linear error of the collected data is dynamically compensated. Subsequently, for the non-uniform distribution of the sampling points, data analysis method is investigated, in which non-uniform interpolation and re-sampling techniques are investigated to obtain accurate data with uniform interval, so that the analysis and evaluation of surface profile can be conducted based on GPS (Geometrical Product Specifications) standards. Experimental results prove the improvements. [Copyright &y& Elsevier]

Through laboratory simulation, the influence of cadmium on soil respiratory intensity and microbial community were studied by adding different concentrations of heavy metal cadmium. The results indicated that, the soil respiration had a significant weakening trend in the same culture days with increasing exogenous cadmium content; the soil respiration intensity was decreased obviously with the increase of culture time, especially after 14 d when the soil exogenous cadmium content was in the range of 0.5-3.0 mg/kg, while the soil respiration had not obvious variation over time when the exogenous cadmium content was in the range of 5.0-10.0 mg/kg. The soil microbial communities decreased significantly and were much lower than that of the control treatment in the same culture days with the increasing of soil exogenous cadmium content; the soil microbial community declined significantly with increasing of culture time for all exogenous cadmium treatments. The number of soil microbial communities in treatment with 10 mg/kg of exogenous cadmium were only 46.43%, 32.26%, 28.74%, 27.39% and 24.62% of that in control treatment on the 7th, 14th, 21st, 28th and 42nd d of culture, respectively. It indicated that higher concentration of cadmium in dark brown soil had a significant inhibitory effect on soil microbial growth. [ABSTRACT FROM AUTHOR]

Short fiber reinforced polymers (SFRP) based on unidirectionally arrayed chopped strands (UACS) offer exceptional formability and great mechanical properties. To ensure its stability and safety in applications, it is crucial to enhance the impact performance of UACS laminates. This study investigated the low‐velocity impact (LVI) responses and damage evolution of UACS laminates with different slit sizes and continuous carbon fiber reinforced polymer (CFRP) laminates under various impact energies (4, 7, and 11 J). The curves of force and energy were recorded during LVI tests, and the post‐impact damage area was detected by the ultrasonic C‐scan technique. Moreover, a user‐defined subroutine VUMAT, containing a progressive damage model and a Johnson‐Cook constitutive model, was written to mimic the damage evolution. Based on experiments and numerical prediction, it was found that when the size was reduced from 25 to 5 mm, the vertical slits had the effect of suppressing delamination and could restrain the propagation of delamination, which explains the distinct difference in delamination area. Highlights: The effect of slit size on the impact behavior of UACS laminate was revealed.The damage mechanism was simulated with a progressive damage model.The novel UACS laminate exhibits excellent energy absorption capacity.The resistance of the slits greatly suppresses the delamination behavior. [ABSTRACT FROM AUTHOR]

Due to the irregularity and complexity of ground and non-ground objects, filtering non-ground data from airborne LiDAR point clouds to create Digital Elevation Models (DEMs) remains a longstanding and unresolved challenge. Recent advancements in deep learning have offered effective solutions for understanding three-dimensional semantic scenes. However, existing studies lack the capability to model global semantic relationships and fail to integrate global and local semantic information effectively, which are crucial for the ground filtering of point cloud data, especially for larger objects. This study focuses on ground filtering challenges in large scenes and introduces an elevation offset-attention (E-OA) module, which considers global semantic features and integrates them into existing network frameworks. The performance of this module has been validated on three classic benchmark models (RandLA-Net, point transformer, and PointMeta-L). It was compared with two traditional filtering methods and the advanced CDFormer model. Additionally, the E-OA module was compared with three state-of-the-art attention frameworks. Experiments were conducted on two distinct data sources. The results show that our proposed E-OA module improves the filtering performance of all three benchmark models across both data sources, with a maximum improvement of 6.15%. The performance of models was enhanced with the E-OA module, consistently exceeding that of traditional methods and all competing attention frameworks. The proposed E-OA module can serve as a plug-and-play component, compatible with existing networks featuring local feature extraction capabilities. [ABSTRACT FROM AUTHOR]

Atomic force microscope (AFM) is widely applied to the measurement of the micro-nano structures due to its three-dimensional spatial resolution of sub-nanometer. However, the height measurement traceability in the z-axis is complex to be implemented in conventional AFMs. In this paper, a traceable AFM is developed based on the monochromatic light interference (MLI) principle without probe calibration. The height change of the AFM's probe is directly detected by extracting the phase change of the MLI fringes on the probe tip with the Hilbert transform based phase extraction algorithm, and the three-dimensional surface topography is reconstructed with a surface recovery algorithm. The configuration of tracing to the wavelength of the monochromatic light in real-time further improves the measurement accuracy of the MLI-AFM. A prototype MLI-AFM is established to demonstrate its measurement accuracy enhancement. • A traceable atomic force microscope (AFM) is developed without probe calibration. • The probe height is traced to the monochromatic wavelength in real-time. • A prototype AFM is established to demonstrate its measurement performance. [ABSTRACT FROM AUTHOR]

Ferrofluids are novel functional materials that have extensively been exploited in fluid-based management and control systems, and thus underlying the dynamic interactions between ferrofluid and solid under various conditions is rather essential. Herein, we report an experimental investigation on the impingement of millimeter-sized ferrofluid droplets on superamphiphobic surfaces. Comparing to droplet impact under no magnetic field, the employment of a non-uniform vertical magnetic field does not change the types of impact phenomena but alters their transitional boundaries and affects droplet dynamic behaviors. At low We , the magnetic force couples with hydrodynamic forces to slightly enlarge the upper threshold for complete rebound, while the enhanced droplet–surface adhesion prolongs the contact time and decreases the restitution coefficient of bouncing droplets; at intermediate We , the promoting effect of the magnetic field on partial rebound was also identified due to the strong droplet–surface adhesion and the additional magnetic force; at high We , a decrease in the damping coefficient and spring constant of the post-impact droplet oscillations emerges if a magnetic field is applied, which is attributed to the volume and shape effects and well explained by simple scaling analyses. We also demonstrate that upward jets are still stimulated in ferrofluid droplet impacts, but they follow scaling laws distinct from simple liquids. Regardless of whether a magnetic field is applied, ferrofluid droplet spreading is mainly dominated by capillary and inertial forces, and such a conclusion can only be drawn when the characteristic length scale for droplet inertia is correctly chosen for data analyses. [ABSTRACT FROM AUTHOR]

Solid‐liquid triboelectric nanogenerators (SL‐TENGs) are a new technology that combines contact electrification (CE) and electrostatic induction to collect clean energy stored in natural water. Considering their unique advantages of high energy density, wide selection of materials and being suitable for large‐scale promotion, they have attracted more and more attention in recent years, and numerous studies have shown their great potential in various applications. Many critical applications of SL‐TENGs inevitably involve sustained and stable high electrical output. To achieve stable output performance and long cycle life in these applications, the adaptability of SL‐TENGs to material selection, structural design, and working environment is necessary. Therefore, the construction of SL‐TENGs matching different applications has become a critical research direction in TENGs. This review provides a historical summary of the development of SL‐TENGs in the past few years and analyzes the key factors affecting their electrical output performance. The exciting achievements of different constructions of SL‐TENGs for practical applications is also demonstrated such as energy harvesting, self‐powered sensing, and self‐powered cathodic protection. Finally, the development prospects of SL‐TENGs and the significant challenges for their further development is discussed. [ABSTRACT FROM AUTHOR]

Background: The ischemia–reperfusion (IR) environment during deep hypothermic circulatory arrest (DHCA) cardiovascular surgery is a major cause of acute kidney injury (AKI), which lacks preventive measure and treatment. It was reported that cold inducible RNA-binding protein (CIRP) can be induced under hypoxic and hypothermic stress and may have a protective effect on multiple organs. The purpose of this study was to investigate whether CIRP could exert renoprotective effect during hypothermic IR and the potential mechanisms. Methods: Utilizing RNA-sequencing, we compared the differences in gene expression between Cirp knockout rats and wild-type rats after DHCA and screened the possible mechanisms. Then, we established the hypothermic oxygen–glucose deprivation (OGD) model using HK-2 cells transfected with siRNA to verify the downstream pathways and explore potential pharmacological approach. The effects of CIRP and enarodustat (JTZ-951) on renal IR injury (IRI) were investigated in vivo and in vitro using multiple levels of pathological and molecular biological experiments. Results: We discovered that Cirp knockout significantly upregulated rat Phd3 expression, which is the key regulator of HIF-1α, thereby inhibiting HIF-1α after DHCA. In addition, deletion of Cirp in rat model promoted apoptosis and aggravated renal injury by reactive oxygen species (ROS) accumulation and significant activation of the TGF-β1/p38 MAPK inflammatory pathway. Then, based on the HK-2 cell model of hypothermic OGD, we found that CIRP silencing significantly stimulated the expression of the TGF-β1/p38 MAPK inflammatory pathway by activating the PHD3/HIF-1α axis, and induced more severe apoptosis through the mitochondrial cytochrome c-Apaf-1-caspase 9 and FADD-caspase 8 death receptor pathways compared with untransfected cells. However, silencing PHD3 remarkably activated the expression of HIF-1α and alleviated the apoptosis of HK-2 cells in hypothermic OGD. On this basis, by pretreating HK-2 and rats with enarodustat, a novel HIF-1α stabilizer, we found that enarodustat significantly mitigated renal cellular apoptosis under hypothermic IR and reversed the aggravated IRI induced by CIRP defect, both in vitro and in vivo. Conclusion: Our findings indicated that CIRP may confer renoprotection against hypothermic IRI by suppressing PHD3/HIF-1α-mediated apoptosis. PHD3 inhibitors and HIF-1α stabilizers may have clinical value in renal IRI. [ABSTRACT FROM AUTHOR]

Diffraction limit is usually a thorny problem in an optical inspection system. In this investigation, a model-based deconvolution technique was developed to recover diffraction-limited images, where images with sizes smaller than the diffraction limit could be recognized. Experiments were carried out with a traditional microscope at 200× magnification coupled with a halogen light source for a series of line width samples. The point spread function of the imaging optics was first obtained from an estimated model and then combined with a nonlinear deconvolution algorithm to calculate the full width at half maximum and reconstruct the line widths. Experimental results indicate that a measurement error below one pixel size of the measurement system is achievable. Accordingly, the target of nanoscale line width inspection based on a low cost and real-time image processing technique can be fulfilled, which greatly increases the ability of nanoscaling on optical microscopes. [ABSTRACT FROM AUTHOR]

Fretting wear behavior of CuNiAl against 42CrMo4 was investigated under different lubrication conditions with the flat on flat contact configuration. In oil, filtered water and artificial seawater, it was under a mixture of liquid lubrication and third body solid lubrication, so the friction torque was lower than that under dry fretting. Wear was the slightest in oil and the most serious under dry fretting. The corrosion products under seawater lubrication presented a friction and wear reducing effect. The wear mechanisms depended on the lubrications. In oil, they were dominated by abrasive wear and plastic deformation; under the two water lubrications, they were mainly cracks, delamination and abrasion; under dry fretting, they were mainly abrasive wear and oxidation wear. [ABSTRACT FROM AUTHOR]

The dynamic characteristics of an atomic force probe are important for rapid and accurate measurement in white light interference (WLI) based atomic force microscope (AFM). The tip of the probe will fly from the surface when its dynamic characteristics are poor, which will cause measurement error. Generally such tip flight can be avoided by reducing the scanning speed, which will decrease the error at the cost of measurement efficiency. In this paper, a dynamical model of atomic force probe is presented to analyze the causes of tip flight in the measurement process. A numerical simulation is performed on a typical sample surface to investigate the influence of profile, preloading and probe parameters on scanning speed. Experimental testing is conducted on a self-developed WLI based AFM, and the experimental results agree well with that of the theory. The maximum scanning speeds of the probe for a sample are tested under certain conditions. It is shown that for a certain probe, the tip flight occurs at the upwards points of the measured sample when the scanning speed exceeds the critical speed, which is constrained by the preloading. [ABSTRACT FROM AUTHOR]

Probe calibration is the basis of accurate atomic force microscope (AFM) measurement. In white light interference based AFM (WLI-AFM), the relationship between the vertical displacement of probe and the position of the interference fringes on probe cantilever should be calibrated for accurate measurement. In this paper, a traceable probe calibration method for WLI-AFM is proposed. A high resolution displacement measurement system based on laser interference is constructed to obtain the vertical displacement of probe with high accuracy. This system is used for standard displacement input for calibration and makes the measurement result traceable to optical wavelength. A zero-order fringe positioning algorithm is presented to determine the position of the interference fringes on probe cantilever. A probe deflection model is established for the calibration relationship which is continuous and can be used for measurement. While calibration is conducted, series of zero-order fringe positions are obtained corresponding to the probe displacement inputs. The data are processed by the probe deflection model to obtain the calibration relationship. The proposed method is applied in a self-developed WLI-AFM. It is verified that the accuracy of the method is higher than the previous methods by certain experiments on this WLI-AFM. [ABSTRACT FROM AUTHOR]

The ability to detect biomolecules at the single‐molecule level is at the forefront of biological research, precision medicine, and early diagnosis. Recently, solid‐state nanopore sensors have emerged as a promising technique for label‐free and precise diagnosis assay. However, insufficient sensitivity and selectivity for small analytes are a great challenge for clinical diagnosis applications via solid‐state nanopores. Here, for the first time, a metal–organic cage, PCC‐57, is employed as a carrier to increase the sensitivity and selectivity of solid‐state nanopores based on the intrinsic interaction of the nanocage with biomolecules. Firstly, it is found that the carrier itself is undetectable unless bound with the target analytes and used oligonucleotides as linkers to attach PCC‐57 and target analytes. Secondly, two small analytes, oligonucleotide conjugated angiopep‐2 and polyphosphoric acid, are successfully distinguished using the molecular carrier. Finally, selectivity of nanopore detection is achieved by attaching PCC‐57 to oligonucleotide‐tailed aptamers, and the human alpha‐thrombin sample is successfully detected. It is believed that the highly designable metal–organic cage could serve as a rich carrier repository for a variety of biomolecules, facilitating single‐molecule screening of clinically relevant biomolecules based on solid‐state nanopores in the future. [ABSTRACT FROM AUTHOR]

We consider complex scenarios involving two-way coupled interactions between compressible fluids and solid bodies under extreme conditions where monolithic, as opposed to partitioned, schemes are preferred for maintaining stability. When considering such problems, spurious numerical cavitation can be quite common and have deleterious consequences on the flow field stability, accuracy, etc. Thus, it is desirable to devise numerical methods that maintain the positivity of important physical quantities such as density, internal energy and pressure. We begin by showing that for an arbitrary flux function, one can put conditions on the time step in order to preserve positivity by solving a linear equation for density fluxes and a quadratic equation for energy fluxes. Our formulation is independent of the underlying equation of state. After deriving the method for forward Euler time integration, we further extend it to higher order accurate Runge–Kutta methods. Although the scheme works well in general, there are some cases where no lower bound on the size of the allowable time step exists. Thus, to prevent the size of the time step from becoming arbitrarily small, we introduce a conservative flux clamping scheme which is also positivity preserving. Exploiting the generality of our formulation, we then design a positivity preserving scheme for a semi-implicit approach to time integration that solves a symmetric positive definite linear system to determine the pressure associated with an equation of state. Finally, this modified semi-implicit approach is extended to monolithic two-way solid–fluid coupling problems for modeling fluid structure interactions such as those generated by blast waves impacting complex solid objects. [ABSTRACT FROM AUTHOR]

• An improved level-set model is proposed for honing groove feature segmentation. • The level-set Heaviside function is approximated using a piecewise linear function. • A 30% accuracy improvement over the best-tested algorithms has been observed. • A folder metal characterization case study validates the algorithm's performance. Honing groove features of a cylinder liner surface contain helpful information on surface performance. Traditional honing surface evaluation methods do not focus on groove features, which is significant to surface functions. Hence, a topographical feature segmentation algorithm and corresponding evaluation parameters are needed. This paper proposes an improved level-set-based segmentation algorithm for groove feature extraction. The proposed algorithm was tested on a real honing surface dataset compared to some state-of-art algorithms, including the classical height thresholding and watershed segmentation. The results show that the proposed method is robust against initial conditions and improves both segmentation accuracy and computational speed. Specifically, a 30% accuracy improvement over the best-tested level-set algorithm has been observed. Another case study on fold-mental characterization was conducted, which also validated the accuracy and speed performance of the proposed algorithm. [ABSTRACT FROM AUTHOR]

• Our work presents a minimally invasive and portable tool for quantitative phase imaging (QPI) of unlabeled thick samples, with potential applications in biomedical imaging at cellular level resolution. We highlight the features of the system performance and performed experiments and analysis in vivo. • In brief, our fiber-bundle-based endoscopic microscopy (FEM) has a flexible front probe with a small form factor, with a QPI module located at the proximal end. The optical phase transmits through the sample is easily obtained via wavefront modulation and straightforward post-processing. FEM overcomes limitations in competing methods, such as iterative phase calculation, image speckle, intensive modeling of the system transfer function, complicated system setup with lateral scanning module or reference arm, and time cost on sample staining. • We explored biomedical imaging potential of FEM by histological slices and in vivo experiments. For cancer diagnosis, FEM distinguishes benign and diseased endometrial slides with differences on morphology and scattering parameters. For thick tissue, FEM images unlabeled mammalian skin in vivo, identifying the boundary and morphology differences between the scar and normal skin, as well as the variations from the scab to scar during 15 days post wounding, such as fibroblast proliferation and inflammation resolution. These findings contribute significantly to our understanding of wound healing mechanisms, wound care, and the development of therapeutic drugs. • With the quantitative information, high sensitivity, and label-free imaging capabilities, we believe the system can greatly benefit the biomedical community. We hope that it will be of interest to the readers of optics and lasers in engineering and we thank you for considering our manuscript. The flexible endoscope is a minimally invasive tool in clinical settings. Conventional modalities record bright field images that are usually low contrast and report qualitative information of the sample surface. Here, we demonstrated a flexible endoscopic microscopy (FEM) for quantitative phase imaging of unlabeled thick samples. FEM employs a 2.5 mm diameter fiber tip, followed by a wavefront shaping module for direct phase measurement. Our instrument yields lateral and axial resolutions of 1.2 and 8.3 um, respectively. Demonstrating the performance on pathologic slices, thick opaque mammalian wound healing skin in vivo, FEM identifies normal and tumor glandular structures, secreta, and tomographic skin layers. With the advantages of direct phase measurement, cellular level resolution, thin fiber tip, and simple setup, FEM has potential value for investigation in vivo. [ABSTRACT FROM AUTHOR]

• Nonlinear errors severely interfere with the accuracy of chromatic confocal measurements at the submicron scale. • Nonlinear error stems from the deviation between the wavelength-distance mapping and the polynomial model. • The proposed method can effectively record the nonlinear error in calibration and compensate it in measurement. • The results show that the method can achieve a 40 % accuracy improvement over a 4 mm range. The mechanisms of the nonlinear error, primarily stemming from the deviation of the polynomial model fitting the wavelength-distance mapping relationship in chromatic confocal measurement, have been elucidated. A compensation method is proposed for the nonlinear error, based on a regression tree model. Through calibration experiments using our chromatic confocal sensor, an impressive improvement of over 40 % in precision could be achieved by our proposed compensation method, which advances from ±1 μm to ±0.6 μm within a 4 mm measurement range. [ABSTRACT FROM AUTHOR]