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To simultaneously improve the strength, deformability, and durability of coral aggregate concrete (CAC), a systematic strengthening program of coral coarse aggregate (CCA) was proposed, and the properties of the strengthened coral aggregate concrete (SCAC) under compression were investigated in this study. For the same, nine groups of 351 concrete specimens were fabricated by condersidering two parameters: CCA strengthening methods (cement paste coated CCA (CPCC) and cement dry-powder coated CCA (CDCC) methods) and strengthening factors (cement-coarse aggregate ratio (c / ca) and water-cement ratio (w / c) of the coating materials). The mechanical mechanism and macro-properties of SCAC were investigated using a novel test system combined with numerical analyses, which included a compression test, digital image correlation measurement, scanning electron microscopy and ABAQUS simulation. The properties and microstructure of CCA were observed to be efficiently enhanced through strengthening, causing a maximum increase of 24.75 % and 110.76 % in compressive strength and energy dissipation capacity of SCAC, respectively, in comparison to CAC. The ductility of SCAC was found to almost the same as that of ordinary concrete after using CPCC due to the improved interfacial transition zones, optimised particle structure and strong aggregates. The strength and deformability of SCAC changed with the variations in the strengthening method and its critical factors. Generally, the peak strain and strength of SCAC adopting CPCC were 6.2 % and 6.48 % greater than the specimens with CDCC, respectively. The splitting strength and ultimate strain of SCAC first increased and then decreased with increasing in strengthening factors, i.e., w / c of the coating materials, and the maximum enhancement in the ultimate strain was 58.16 %. Compared to CAC, the descending branch and curvature of the stress-strain curve of SCAC were significantly improved due to the changes in the crack propagation in concrete and plastic deformation. The typical influences of the characteristics of the strengthened CCA on the mechanism were also studied through numerical simulations, which indicated that the ductility and strength increased with increasing strength of the coating of aggregates. Finally, an analytical stress-strain model of SCAC that considered the effects of strengthening variables was proposed, which provides a basis for the actual application of SCAC structures. • The properties of CAC were significantly improved through strengthening coral aggregates. • CAC mechanical response varied with the variations in aggregate strengthening method and factor. • The mechanical mechanism of strengthened CAC was revealed by a novel analysis system. • An analytical model of CAC considering effects of strengthening factors was established. [ABSTRACT FROM AUTHOR]

• Failure of coral concrete was obviously influenced by the mix component. • The stress-strain curve varied with the variation of mix component. • The deformation distribution was slightly changed after using different types of materials. • Seawater changed the crack propagation of CC, while FA partly counteracted the effect of seawater. Typical influences of mix component on the properties of coral concrete (CC) were analyzed in this paper. Different types of fine aggregates (sea sand and river sand), mixing water (seawater and fresh water) and cementitious materials (cement and fly ash) were considered. An experimental system was developed involving uniaxial compression tests and the use of digital image correlation (DIC) method to investigate the deformation distribution and crack propagation of CC. The variations in failure pattern, strength and deformation of CC were studied. Test results indicated that the failure of CC adopting sea sand and seawater was brittle compared to CC using fresh water and river sand. It was found that axial stress-strain curve (SSC) of ordinary concrete (OC) was different from that of CC. The curvature and the descending slope of SSC obviously changed with the variation of mix components. The seawater improved the strength and elastic modulus of CC compared to fresh water, however, the effect of sea sand was negative. It was verified that prismatic compressive strength of CC with fly ash (FA) developed slowly in early stage, while it increased quickly in late stage. After using different types of aggregates, mixing water and cementitious materials, obvious changes were found in the crack propagation and the axial deformation distribution. However, typical influence of mix component on horizontal displacement distribution was negligible. The cracking of CC was seldom observed before the peak stress when compared to OC, and the seawater and sea sand accelerated the CC crack growth after the peak point. Finally, a numerical stress-strain expression of CC considering the influences of mix component was suggested, which could be used in the theoretical analysis and practical design. [ABSTRACT FROM AUTHOR]

Highlights • Failure of concrete was obviously influenced by the coarse aggregate type. • The strength and stress-strain curve varied with the variation of coarse aggregate type. • After mixing different types of coarse aggregates the deformation distribution was not changed. • Characteristics of cracks in NAC were different from those of cracks in RAC and CAC. Abstract The effects of different types of coarse aggregates on mechanical properties of concrete were compared in this paper. Three different coarse aggregates were considered: natural coarse aggregate (NCA), recycled coarse aggregate (RCA) and coral coarse aggregate (CCA). An experimental campaign was developed involving uniaxial compression tests and the use of digital image correlation (DIC) method to obtain the deformation distribution and crack propagation of specimen. The influence of coarse aggregate on deformation development of concrete phases (cement mortar and interface transition zone (ITZ), etc.) was also studied. Test results indicated stress-strain curve (SSC) of concrete using NCA (natural aggregate concrete) was similar to that of concrete adopting RCA (recycled aggregate concrete), while SSC of coral aggregate concrete (concrete using CCA) was different from the others. Compared with coral aggregate concrete (CAC), the failures of natural aggregate concrete (NAC) and recycled aggregate concrete (RAC) were more ductile. But prismatic compressive strength of CAC was higher than other specimens. Coarse aggregate type had obvious influence on the distribution of axial deformation fields of concrete. It indicated that the axial displacements of cement mortar and ITZ were higher than that of NCA before peak point. After mixing different types of coarse aggregates, obvious changes were not found in the displacement distribution of specimen. It was also found that the large strains (axial and transverse) of NAC and RAC mainly concentrated in cement mortar and ITZs before peak stress, however, those of CAC obviously appeared in CCA. Type of coarse aggregate changed the crack propagation of concrete. Compared with NAC and RAC, CAC cracking seldom appeared before peak stress, and cracks drastically expanded to critical size after that. Finally, a normalized analytical expression for different types of concretes was suggested, which could provide a basis for the application of recycled and coral aggregate concretes. [ABSTRACT FROM AUTHOR]

The hot deformation behavior of nanostructural oxide dispersion-strengthened (ODS) Mo alloy was investigated in the temperature range of 1200–1500 °C and strain rate range of 0.001–1 s−1 with a constant strain of 0.50 by analyzing constitutive equations, hot processing maps, and microstructure evolution. The results show that the flow behavior is greatly affected by the deformation temperatures and strain rates, exhibiting typical hardening, softening, and steady stages. The constitutive equation is established, which can predict the flow stress precisely. The stress exponent n and the apparent activation energy Q are estimated to be 5.44 and 384.26 kJ·mol−1, respectively, revealing that the deformation mechanism is dominated by the dislocation climb. Furthermore, the hot processing maps of ODS Mo alloy are developed based on the dynamic materials model, presenting two stability zones of 1350–1450 °C/0.001 s−1 and 1450–1500 °C/0.1–1 s−1. By observing microstructures, dynamic recovery and dynamic recrystallization occur in the stability zone 1500 °C/1 s−1, and the mechanism of the stability zone 1400 °C/0.001 s−1 is dominated by dynamic recovery and grain growth. • The hot deformation behavior of nanostructural oxide dispersion-strengthened (ODS) Mo alloy was investigated in the temperature range of 1200–1500 °C and strain rate range of 0.001–1 s−1. • The constitutive equation and processing maps were established. • The microstructure evolution and deformation mechanism at instability and safety zones were clarified. [ABSTRACT FROM AUTHOR]

• Failure of fibre reinforced SSRAC was obviously affected by coarse aggregate type. • The concrete stress–strain curve varied with the variation in mix component. • The change of concrete deformation distribution was negligible after adopting fibres. • The crack propagation significantly changed with the variations in fibre type and content. This study investigates the mechanical properties of fibre reinforced seawater sea-sand recycled aggregate concrete (SSRAC). A total of 360 concrete specimens, considering four different variables—the type of concrete (SSRAC, recycled aggregate concrete and ordinary concrete), age (day 7, 14 and 28), fibre type (polypropylene and stainless steel fibres) and content—were fabricated. The macro properties and mechanical mechanism of discrete fibre reinforced SSRAC were systematically studied through a novel experimental system involving axial compression test and digital speckle correlation method (DSCM). The failure pattern, strength, ductility, stress–strain curve, deformation filed, crack initiation and propagation of fibre reinforced SSRAC were analysed. The major research findings indicate that the stainless steel fibres (SSF) could effectively offset the effects of seawater, sea-sand and recycled aggregates on the mechanical properties of concrete compared to polypropylene fibres (PF). The failure pattern of specimen slightly changed with the fibre type used. The compressive and splitting tensile strengths of SSRAC increased with an increase in PF content, while the optimal SSF content for SSRAC was 1.0% by volume content of concrete. Moreover, the typical influence of PF on the elastic modulus of SSRAC was negative but SSF could greatly improve that of specimen. The axial stress–strain curve of fibre reinforced SSRAC consisted of elastic, elastic–plastic ascending and declining stages. Increasing SSF and PF contents decreased the curve curvature while increased the ductility and peak strain, and the descending branch of curve tended to be smooth. Generally, the effects of fibres on the crack initiation of SSRAC and the distributions of deformation field and cracks were negligible compared to coarse aggregates, while the crack propagation of SSRAC significantly changed with the variations in fibre type and content. The cracks and high-value strain of SSF reinforced SSRAC developed slowly compared to plain SSRAC and PF reinforced SSRAC. Finally, an analytical stress–strain model of fibre reinforced SSRAC considering the coupled effects of various variables were proposed, which can be used to conduct a theoretical evaluation and design of the marine structures. [ABSTRACT FROM AUTHOR]

Abstract: A theoretical study of the mechanical response of recycled aggregate concrete (RAC) confined by steel tubes under axial compression is conducted to examine the sensitivity of the confining pressure on the strength and deformation of RAC. The main parameter in this analysis is the recycled coarse aggregate (RCA) replacement percentage. The axial stress–strain relationship of confined RAC is obtained based on the elastoplasticity and verified by experimental results. It is found that the development of the confining pressure can be divided into three sections: linear increase, nonlinear increase and relatively smooth increase. The mechanical proprieties of confined RAC are dependent on the variation of the confining pressure. The analysis results indicate that the assumption of constant confinement or elastic–plastic confinement is not appropriate for concrete confined by steel tubes and the RCA replacement percentage has a moderate effect on the mechanical response of the confined concrete. Finally, a simple model for the constitutive relationship of RAC under varying pressures and different RCA replacement percentages is proposed. [Copyright &y& Elsevier]

An experimental study on the mechanical behavior of glass fiber reinforced plastic (GFRP) tube confined seawater coral aggregate concrete reinforced with epoxy-coated steel bars (GSCACESB) under axial compression were systematically performed. Three different parameters were considered: concrete type (seawater coral aggregate concrete and ordinary concrete), GFRP tube thickness (4 mm, 5 mm and 6 mm) and reinforcement ratio (longitudinal and circumferential reinforcement ratios). Typical influences of concrete, GFRP tube and reinforcement on the bearing capacity, deformation and load-deformation curve of GSCACESB were investigated. Test results showed that the failure pattern of GSCACESB was similar to that of GFRP tube confined ordinary concrete (GCOC). However, the bearing capacity of GSCACESB was significantly decreased compared to GCOC due to the less confinement between seawater coral aggregate concrete and outer tube. The peak deformation and bearing capacity of GSCACESB increased with the increases of tube thickness, and longitudinal and circumferential reinforcement ratios. The load-deformation curve of GSCACESB was divided into elastic-plastic and hardening stages. The more the reinforcement ratio, the less the curve curvature. An analytical expression considering the influences of SCAC was also proposed, which could predict the structural response of GSCACESB. Finally, the numerical simulation analysis was undertaken to investigate the GSCACESB mechanical behaviors. [ABSTRACT FROM AUTHOR]

• A new method for laser welding of steel-PMMA plates was explored. • Laser welding steel-PMMA joint strength is 974 N, much larger than ever reported. • Five types of steel-PMMA welded joints and fracture model have been proposed. • Taguchi method was applied to optimize welding parameters and improve joint quality. Dissimilar joining of 304 stainless steel to PMMA is accomplished by a Nd: YAG pulsed laser. The light and process were represented by laser peak power, welding speed, defocus, pulse duration, pulse frequency and Ar gas flow rate, as these experiment parameters have significant effects on joints strength, weld width, joints quality and appearance. The welding parameters were optimized by an orthogonal experiment design, then the validation and optimization experiments were carried out to obtain the best combination of process parameters. A maximum weld strength of the joints of 974 N was achieved (the joints efficiency reached 70% of the base PMMA), much larger than ever reported. Bead profiles such as bead width and mechanical strength were investigated, and five types of 304 stainless steel-PMMA welded joints and three kinds of fracture model have been proposed. [ABSTRACT FROM AUTHOR]

The bond between epoxy-coated reinforcement (ECR) and seawater coral aggregate concrete (SCAC) were studied by using a series of pull-out tests. Five different parameters were considered in this test: types of concrete (SCAC and ordinary concrete (OC)) and reinforcement (ECR and ordinary reinforcement), the ratio of bond length to reinforcement diameter (3, 5 and 8), and concrete strength (C25 and C35) and thickness of concrete cover. The failure mode, bond-slip curve and strength of specimens were analyzed. Typical failure mode of pull-out specimen was splitting failure, while the failure surface of SCAC specimen was different from that of OC specimen. Test results indicated that the bond strength of specimen with SCAC was high compared to specimen using OC even under the similar concrete strength. Seawater coral aggregate concrete-ECR (SCAC-ECR) bond strength decreased with increasing bond length and decreasing concrete strength and thickness of concrete cover. The bond-slip curve of SCAC-ECR was similar to that of ordinary concrete (OC)-ordinary reinforcement (OR). However, SCAC and ECR reduced the bond-slip curve curvature. The decline of curve was improved by using ECR. Finally, an analytical expression for bond stress-slip curves was proposed. The obtained results provide a basis for the application of reinforced SCAC. • Typical failure mode of SCAC-ECR pull-out specimen is splitting failure. • SCAC enhances the bond strength, while the influence of ECR is negative. • Bond strength obviously increases with an increase in concrete cover thickness. • Types of concrete and reinforcement change the shape of bond-slip curve. [ABSTRACT FROM AUTHOR]

• The effect of laser pulse shapes on Al-Cu dissimilar metals mixing. • Relationship between metals mixing and IMCs formation. • The effect of laser pulse shapes on mechanical and electrical properties of Al-Cu joints. The Nd: YAG laser is utilized to weld 1060 aluminum (Al) and 110 copper (Cu) with a thickness of 0.4 mm. The effect of different pulse shapes on the microstructure, mechanical and electrical properties of Al-Cu lap joints are investigated by using of the optical microscopy, scanning electron microscope (SEM), tensile test device and micro-resistance tester, respectively. This investigation provided a detailed understanding of how the different pulse shapes influence the metal mixing and the formation of intermetallic compounds (IMCs). The results indicate that the pulse shape with an initial preheating phase improved the laser absorption efficiency. Additionally, this pulse shape resulted in less dissimilar metal mixing compared to the pulse shape that maintained the maximum power throughout. Furthermore, the pulse shape in which the laser power was linearly increased and then maintained at maximum power reduced the formation of IMCs at the joint interface. As a result, the joint exhibited mechanical strengths up to 92 % of the Al base material and similar electrical conductivity. The study provides theoretical guidance on how to utilize pulse shape modulation in laser welding to achieve optimal mechanical and electrical properties in typical joints between Al tabs and Cu busbars. [ABSTRACT FROM AUTHOR]

In the present work, a thermodynamic-assisted target-converting strategy was designed by utilizing new 2D DNA nanoprobes (DNPs) to develop electrochemical biosensors for the sensitive determination of trace Pb2+. Herein, a stable DNP with a special structure was prepared through the hybridization reaction between three single-strand DNA (RS1, RS2, and P). Once the existence of Pb2+, the DNP will crumble and then release RS1 and RS2 due to the strong thermodynamic instability of the RS1/RS2 duplex. since RS1 and RS2 were designed in the same sequence in the free domain, they can be simultaneously used as effective output DNA, enhancing the conversion rate of Pb2+to ssDNA up to 1:2. Following the same principle, ferrocene-labeled bipedal DNPs (Fc-bDNPs) are prepared for stable electrochemical signal output. In the presence of RS1, RS2, and a hairpin DNA strand (H1), the ferrocene-labeled DNA strands (S3) escape from the Fc-bDNPs due to strand-displacement reaction, accompanying release of the two ssDNA outputs that can simultaneously trigger another strand-displacement reaction. Consequently, the one Pb2+input makes multiple Fc-labeled DNA strands far away from the electrode surface, resulting in a dramatic decrease in the response current of Fc. The developed biosensors show a linear relationship between current value and logarithmic concentration of Pb2+ ranging from 1 pM to 40 nM with a detection limit of 0.30 pM. [ABSTRACT FROM AUTHOR]

• Laser welding technology is effective for bonding of Al and Cu dissimilar metals. • Relationship between process parameters and joint properties are explored. • Controlling defects and improving joints quality methods are discussed. • Review for welding process, filler metals and process monitoring. Dissimilar metal composite structures have been used in a wide range of applications to meet the requirements of lightness, corrosion resistance, electrical conductivity, and thermal conductivity due to their excellent overall performance. With the global energy conservation and emission reduction policies, dissimilar aluminium (Al) and copper (Cu) for lithium battery welding are more and more discussed. Laser welding is a unique technology for Al and Cu due to its high energy density, precise control, ease of automation, and remote welding. However, high reflectivity and differences in material properties result in poor laser absorption and an unstable welding process. Furthermore, sufficient mixing of Al and Cu during the welding process tends to form brittle intermetallic compounds (IMCs). This paper discusses the laser welding and the challenges faced by joining Al/Cu dissimilar metals, and analyzes the effect of different process parameters and laser output modes on the weld joint. Furthermore, the research progress on filler metals and process monitoring are discussed. [ABSTRACT FROM AUTHOR]

• Laser joining of 316L stainless steel and polylactic acid was studied by orthogonal experiment. • Significant factors affecting the joint quality and morphology were discovered. • Shear force of joint reached 88.73% of the polylactic acid base material. • The relationship between five joint morphologies and four failure modes was established. To realize the joining of dissimilar material 316L stainless steel with polylactic acid (PLA), the laser-assisted metal-plastic direct joining (LAMP) method was applied, and the process parameters were optimized based on the method of orthogonal experiment, and the quality of the joint was studied. The influence law of each influencing factor of the joining process on the joint quality and joint morphology was obtained through orthogonal experiments, to find out the maximum influencing factor and obtain the optimal process combination. By a universal tensile testing machine to find out the influence of the process parameters on the joint failure modes. The results showed that the laser power, pulse duty ratio, and laser speed had a major influence on the shear force, elongation at break and joint width. The maximum shear force achieved by the optimized method was 1694.379 N, reaching 88.73 % of the tensile force of the PLA base material, and the elongation at break was 5.47 %, reaching 76.91 % of the base material, obtained a more satisfactory joint effect. The correspondence between five joint morphologies and four failure modes is established, and different process parameters can be selected according to different applications of 316L stainless steel-PLA composite materials, to optimize industrial manufacturing. [ABSTRACT FROM AUTHOR]

Fine-grained Mo alloys doped with uniformly distributed nanoscale Y 2 O 3 particles were successfully prepared by employing two powerful strategies: fabricating high-quality precursor powders using hydrothermal synthesis and subsequent powder consolidation by spark plasma sintering (SPS) technique. In this study, the effect of hydrothermal variables on the morphology and existent form of yttrium and Mo was systematically studied, and the refinement mechanism of reduced mixing powders and the densification under the different sintering parameters were investigated. The results show that spherical Y 2 (CO 3) 3 ·2H 2 O gradually replaced Y(OH)CO 3 owing to the increased concentration of hydrogen bonds and CO 3 2− at excess alcohol and urea, and lamellar (NH 4) 2 Mo 4 O 13 developed into large pillar-shaped h-MoO 3 with decreasing pH. Due to the low calculated lattice mismatch degree of Mo/Y 2 O 3 interfaces ~10.9%, Y 2 O 3 particles further refined and homogenized the reduced mixing powders as heterogeneous nucleating sites. After sintering at 1700 °C for 5 min with a heating rate of 100 °C/min, Mo-Y 2 O 3 alloys possessed fine grains of 1.80 ± 0.17 μm, a high density of 98.18% and the high indentation hardness of 314.77 ± 26.12 HV 0.3 and 4.82 ± 0.53 GPa H IT. The Y 2 O 3 particles were uniformly distributed in the Mo matrix, and semi-coherent with Mo lattice, with the orientation relationships as follows: (010) Y2O3 //(011) Mo , (01-1) Y2O3 //(020) Mo , and [100] Y2O3 //[100] Mo. • Fine-grained Mo alloys doped with nanoscale Y 2 O 3 particles were fabricated by using hydrothermal synthesis and SPS technique. • Y 2 O 3 particles refined and homogenized the reduced mixing powders by acting as heterogeneous nucleation sites. • The Y 2 O 3 particles were uniformly distributed in the Mo matrix, and semi-coherent with Mo lattice. [ABSTRACT FROM AUTHOR]

[Display omitted] • Probe T shows high selectivity toward β-HB detection. • Detection limit of probe T is as low as 0.154 μM. • The "turn-on" color change of probe T is observed by naked-eye. Beta-hydroxybutyrate (β-HB) serve as a valuable diagnostic biomarker for Diabetic Ketoacidosis (DKA). Here, a new Schiff base fluorescent probe T was designed and synthesized to detect β-HB level in aqueous solution in vitro. The probe T can detect β-HB sensitively and selectively in DMF solution (5.0 × 10−5 M) among other interfering species (cations, anions, amino acids, biomarkers). The detection limit of probe T for β-HB was calculated to be 0.154 μM. These results demonstrate that the probe T may provide a convenient method for rapid detection of β-HB to diagnose diabetic ketoacidosis. [ABSTRACT FROM AUTHOR]

Lesion detection from retinal images is an important topic in the retinal image analysis. Many computer-aided detection techniques have been developed for detecting retinal lesions. However, these techniques are mainly used to detect specific lesion types from retinal images. They cannot be applied to detect diverse types of lesions from retinal images, which is a challenging task because lesion number and types in retinal images are generally unknown in advance, and different lesions may exhibit diverse properties in shapes, sizes, colors, textures and positions. Inspired by the doctors’ visual diagnostic mode, this paper proposes a novel computational framework to detect various types of lesions from retinal images. In this framework, many healthy fundus images are collected to act as ”doctors’ detection experience”, and local visual properties of lesions are used to distinguish true positives from false positives. A specific subspace is learned from the collected normal set and acts as a specific structural filter, by which various lesions in a retinal image can be filtered out while other normal regions keep little changes. By computing the difference image between a target image and its filtered image, different types of lesion candidates can be separated from the image. Furthermore, based on local visual context properties of lesions, the true lesions are identified from the lesion candidates. Extensive experiments have shown that the proposed method can more effectively detect diverse lesions from retinal images compared with related methods. [ABSTRACT FROM AUTHOR]

Detecting defects in weld radiographs is an important research topic in the field of industrial non-destructive testing. Many computer-aided detection techniques have been designed for detecting defects. However, these techniques are mainly used to detect specific defective types. They cannot be applied to detect diverse types of defects, which is a difficult task because the number and types of defects in weld radiographs are generally unknown in advance, and different defects may exhibit different visual properties in shapes, sizes, textures, contrasts and positions. Inspired by the experienced workers' visual inspection mechanism, this paper develops a novel framework to detect diverse types of defects from X-ray images. In the framework, a large number of normal X-ray images are firstly collected to serve as “workers' experience” and guide the defect detection. Then, a dictionary is learned from the collected normal set. It can selectively reconstruct the background and the weld region of a test image while suppressing defective regions via sparsity reconstruction. By computing the difference image between the test image and its reconstructed image, flaws are well highlighted as the reconstruction residuals and separated from the difference image. Extensive experiments have shown that the proposed technique detects diverse defects more accurately compared with the state-of-the-art methods. [ABSTRACT FROM AUTHOR]

Nanostructural Y-Zr-O oxide dispersion-strengthened (ODS) Mo alloys were in-situ prepared based on the dissolution and re-precipitation strategy of oxides during mechanical alloying (MA) and spark plasma sintering (SPS). The effect of Zr addition on the microstructures and mechanical properties of Mo-1Y 2 O 3 -xZr alloy (x = 0.3, 0.6, 0.9, and 1.2 wt%) was investigated. The results show that both intragranular and intergranular Y-Zr-O particles are nanoscale and non-stoichiometric, possessing a different Y/Zr ratio. The Y-Zr-O particles and ultrafine grain structure jointly contribute to high strength (1.87 times over pure Mo) and simultaneously great elongation (2.98 times over pure Mo) of Mo-1Y 2 O 3 -0.3Zr alloy. The yield strength and elongation are reduced as Zr addition beyond 0.6 wt%, owing to the aggregation of Y-Zr-O particles at grain boundaries. The theoretical calculation indicates that the strength is mainly affected by grain refinement strengthening and Orowan precipitate strengthening. But the strength is less predicted due to a great amount of Y-Zr-O nanoclusters smaller than 5 nm cannot be considered in the statistical analysis by conventional TEM. • In-situ preparing nanostructural Y-Zr-O oxide dispersion-strengthened (ODS) Mo alloys byMA and SPS. • Nanoscale intragranular and intergranular Y-Zr-O oxides and ultra-grained structure jointly improved mechanical properties. • Grain refinement strengthening and Orowan precipitate strengthening dominate the improvement of strength. [ABSTRACT FROM AUTHOR]

The nanostructural oxide dispersion strengthened (ODS) Mo alloy was successfully fabricated by mechanical alloying (MA) and spark plasma sintering (SPS). In this study, the MA and SPS conditions were systematically studied, and the characteristics of oxide particles were investigated. The results show that the MA process can refine the powder and promote the dissolution of interstitial atoms, but introduce the ZrO 2 and excess O impurities. To recycle ZrO 2 impurity as a source of active element Zr for alloy preparation, the content of Zr and O with milling time was quantitatively evaluated. In the SPS process, the precipitation of oxide particles retard the densification of as-MA Mo powders. Based on the calculated linear shrinkage, the densification behavior is controlled by sintering temperature, which is driven by grain boundary or dislocation climbing. A high relative density of 99.28% in ODS Mo alloy is achieved using the optimized MA (250 rpm/18 h) and SPS (1400 °C/5 min) parameters. Additionally, the ultrafine Mo grain structure (300 nm) and uniformly dispersed nanoscale Y-Zr-O oxide particles (20.32 nm) inside grains greatly improve the mechanical properties (569.63 ± 28.08 HV 0.3) of ODS Mo alloys. Non-stoichiometric Y-Zr-O particles, with different Y/Zr ratios (Y/Zr <1), possess a special fluorite crystal structure. • The nanostructural ODS Mo alloy with ultrafine Mo grain (300 nm) and nanoscale Y-Zr-O particles (20.32 nm) was fabricated. • The MA can refine powders and promote the dissolution of interstitial atoms, but introduce ZrO 2 and excess O impurities. • The precipitation of oxide particles retard powder densification of as-MA Mo powders. • Non-stoichiometric Y-Zr-O particles, with different Y/Zr ratios (Y/Zr < 1), possess a special fluorite crystal structure. [ABSTRACT FROM AUTHOR]

• Laser welding is applied to joint DP780 to Al5052 plates. • Four types of steel-aluminum welded joint and fracture model are summarized. • The response surface model of welding parameters are analyzed. • The laser power and welding speed are significant effect on lap shear strength. A laser welding of DP780 steel to Al5052 joint has been investigated to optimize the weld width and lap-shear force. Four types of steel-Al welded joints and fracture model have been proposed. Response surface methodology and central composite design were applied to develop mathematical relationships between the control parameters and the responses. Then, the validation and optimization experiments were carried out to check the models adequacy. The results show that there exists good consistency between the predicted and actual value. This indicates the developed models could predict the weld width and lap-shear force within the limits of the process parameters. [ABSTRACT FROM AUTHOR]

• A multi-scale sparse coding based learning algorithm is proposed for effectively learning the individualized retinal background. • A repeated learning strategy is proposed for improving the accuracy of the individualized retinal background. • A feasible approach is developed for detecting both salient and weak retinal lesions. Computer-aided lesion detection (CAD) techniques, which provide potential for automatic early screening of retinal pathologies, are widely studied in retinal image analysis. While many CAD approaches based on lesion samples or lesion features can well detect pre-defined lesion types, it remains challenging to detect various abnormal regions (namely abnormalities) from retinal images. In this paper, we try to identify diverse abnormalities from a retinal test image by finely learning its individualized retinal background (IRB) on which retinal lesions superimpose. 3150 normal retinal images are collected as the priors for IRB learning. A preprocessing step is applied to all retinal images for spatial, scale and color normalization. Retinal blood vessels, which have individual variations in different images, are particularly suppressed from all images. A multi-scale sparse coding based learning (MSSCL) algorithm and a repeated learning strategy are proposed for finely learning the IRB. By the MSSCL algorithm, a background space is constructed by sparsely encoding the test image in a multi-scale manner using the dictionary learned from normal retinal images, which will contain more complete IRB information than any single-scale coding result. From the background space, the IRB can be well learned by low-rank approximation and thus different salient lesions can be separated and detected. The MSSCL algorithm will be iteratively repeated on the modified test image in which the detected salient lesions are suppressed, so as to further improve the accuracy of the IRB and suppress lesions in the IRB. Consequently, a high-accuracy IRB can be learned and thus both salient lesions and weak lesions that have low contrasts with the background can be clearly separated. The effectiveness and contributions of the proposed method are validated by experiments over different clinical data-sets and comparisons with the state-of-the-art CAD methods. [ABSTRACT FROM AUTHOR]

When a multi-UAV is performing a mission, the information obtained by the commander could be highly uncertain. How to choose strategies based on uncertain information will directly affect the success or failure of the UAV mission. In this paper, we present a multi-UAV confrontation model based on uncertain information, which can provide a powerful reference for strategy selection. We established a multi-UAV game model, and proposed a game payment function, and introduce a situation matrix to imitate the uncertainty of war information. In order to complete the calculation of uncertain information, the paper introduces a complex calculation method and establishes an interval decision model. The simulated experiment results show that the situation matrix proposed in this paper could represents the uncertainty in the battle field, and the interval decision method could process data effectively. Furthermore, the proposed algorithm could provide optimal strategy for decision support in battle field with uncertain information, and provide new research direction for game with uncertain information. [ABSTRACT FROM AUTHOR]