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Cold spray (CS) has emerged as a representative of solid-state additive manufacturing (AM) via supersonic impact. It enables a high deposition rate of solid-state microparticles. Delamination, however, tends to occur when depositing too thick; this remains to be conquered. Here, a CS-like process, warm spray (WS), was presented. Interestingly, it was found that the appropriate increase in particle temperature can effectively reduce the residual stress amplitude, relieving the concentrated tensile stress and safeguarding the additively manufactured components from interfacial delamination even when depositing too thick. The key role of temperature on delamination was identified in solid-state AM via supersonic impact.

Cold spray (CS) is a highly potential solid-state additive manufacturing (AM) technique. In situ shot-peening-assisted CSAM was proposed to additively manufacture fully dense deposits using cost-effective and renewable nitrogen gas. The role of in situ shot-peening particles is critical but remains unclear. Here, the process was quantitatively modeled to visualize the dynamic deformation, energy conversion, as well as cell/sub-grain size and microhardness evolutions, compared to those during the conventional CSAM process, identifying the key role of in situ shot-peening particles in the AA6061 extreme deformation and microstructure characteristics during in situ shot-peening-assisted CSAM. High-fidelity modeling was verified fully by comparing the experimental and model-reproduced deformation profiles, cell/sub-grain size distributions, and increases in microhardness. The results show that the kinetic energy of in situ shot-peening particles was 470 times higher and dissipated mainly through AA6061 plastic deformation (86.36% of total energy), leading to significant enhancement of microhardness and tensile strength. Moreover, the mixing ratio of large-size SS410 particles required to create a fully dense deposit was evaluated from an energy perspective, in good agreement with the experiment. This study elucidates the microforging principle during in situ shot-peening-assisted CSAM, providing scientific guidelines for high-quality and low-cost CSAM of high-strength aluminum alloys.

The present study revealed that a strong CoCrNi medium entropy alloy (MEA)/stainless steel (SS) joint could be obtained by friction welding technique with the formation of a microscale interfacial layer composed of varying degrees of the multi-principal element. A significant refinement in grain size to (∼2.8 µm) compared to the base metals (16.6 µm for MEA and 12.2 µm for SS) was observed arising from the co-occurrence of continuous and discontinuous dynamic recrystallisation where grains nucleated at triple grain boundaries, twin boundaries as well as low angle grain boundaries. A relatively strong brass texture {112} 〈110〉 appeared in the layer after recrystallisation, which was attributed to the grain growth behaviour under large deformation. The formation process of the interfacial layer from mesoscale to nanoscale was then postulated. Nanoindentation test indicated that the grains in the layer showed hardness between two base metals, but the interfacial layer demonstrated much higher yield strength (632 ± 14 MPa) and tensile strength (916 ± 4 MPa) than base metals, being higher than the relevant values reported in the literature. It was further clarified that the grain boundary strengthening mechanism rather than dislocation strengthening or solid-solution strengthening was mainly responsible for the strength enhancement.

In augmented reality, interactive shadow casting between virtual and real objects is crucial for the consistency of the appearance of integrated scenes. Since real shadow-casting objects may not be fully visible in live videos, simulating the shadows that they cast onto virtual objects based on 3D reconstruction will fail. To address this issue, we propose a framework for simulating shadow interactions in live outdoor videos based on shadow edges. The simulation framework consists of two components: real-time casting shadow detection from live videos with moving viewpoints and generation of shadow volumes. First, we propose a novel split-based shadow detection framework that accounts for moving viewpoints. Then, a visual-perception-guided adaptive sampling strategy is developed to generate high-quality shadow volumes. The experimental results demonstrate that our algorithm achieves visually consistent shadow interactions for live outdoor videos, which significantly enhances the photorealism of the generated scenes for augmented reality (AR) applications.

Corrugated-board explosion-proof wall is the main means to prevent explosion shock wave damage, and it is important to study the effect of different corrugated plates on the shock wave. Using a high-speed schlieren experimental system and an air overpressure test system, the wave-blocking characteristics of different forms of corrugated plates are comprehensively studied. The schlieren images were used to analyze the influence that the corrugation shape of a corrugated plate has on the shock wave propagation characteristics. The results show that the reflection process of the triangular-, trapezoidal-, and half-cylindrical-shaped corrugated plates exhibit differences. The number of reflected waves from the triangular corrugated plate is much greater than that from the other corrugated plates, and it will consume more energy. The diffraction wave-front velocity has a trend of initially decreasing and then increasing and is also reduced by different degrees by the reflection. Comparative analysis of the schlieren images and the air shock wave overpressure test shows that plates corrugated with different corrugation shapes decrease the diffraction overpressure peak and exhibit a hysteresis.

The antiexplosion performance of an explosion-proof wall made of engineered cementitious composite was studied, using small-scale explosion-proof walls made of different materials and sizes that were subjected to on-site blasting. The dynamic responses of these walls were evaluated under blast loading using overpressure test system, digital image correlation (DIC) full-field strain testing, and high-speed photography recording of the crushing process. Analysis of the results of the overpressure and strain tests revealed the effect of the wall height on the overpressure behind the wall. Increasing the height of the explosion-proof wall can improve the protection ratio of the wall by more than 2%. The variation of full-field strain of different materials at the same burst ratio was obtained. The engineered cementitious composite explosion-proof wall was obviously superior to that of ordinary concrete in strain control on the back-explosion surface. These theoretical results provide references for the design of explosion-proof walls.

To study the effects of straw utilization methods on dry matter production and yield of japonica rice in northern China, taking the super japonica rice Shennong 265 as the test material, using the planting method of seedling transplanting, setting four treatments, namely, the conventional production, directly returning straws to field (6 t/ha), returning straws to field at low amount of biochar (2 t/ha) and returning straws to field at high amount of biochar (40 t/ha), this paper analyzed the changes in production and yield of super japonica rice Shennong 265. According to the experimental results, compared with the conventional production, after the straws were directly returned to the field, the dry matter accumulation of japonica rice was insufficient, and the leaf output rate and contribution rate were significantly reduced by 41.19% and 34.69%, respectively; the number of filled grains per panicle, 1000-grain weight, and panicles per plant showed negative effect, leading to a decline in the yield; under the condition of returning straws to field at high amount of biochar, the dry matter accumulation showed a decline trend, both the leaf and stem sheath significantly reduced by 21.41% and 17.43%, and the number of filled grains per panicle also declined; under the condition of returning straws to field at low amount of biochar, the dry matter accumulation increased, and the leaf contribution rate increased by 11.68%, the number of filled grains per panicle, 1000-grain weight, and panicles per plant showed positive effect, showing the potential of yield increase. In conclusion, returning suitable straw biochar to field (2 t/ha) is favorable for promoting the japonica rice production in northern China. [ABSTRACT FROM AUTHOR]

The research performed analysis on differences of physiological property and yield of Tiejing No. 11 by different nitrogen fertilization patterns. The results indicated that while the nitrogen of basal: tillering: panicle was 6:3:1, the higher amount of nitrogen improved the chlorophyll content, photosynthetic capacity, effective panicle, grain weight and yield; the medium nitrogen level had advantage under the ratio 4:3:3; nitrogen application at iategrowth stage was suitable for low or medium nitrogen level, which could increase photosynthetic capacity arid optimize the yield components and increase yield; under the same ratio for basic tiller and ear fertilizer, the increase of nitrogen could improve total nitrogen uptake and protein content, decrease nitrogen physiological efficiency and milled rice and tasting, but nitrogen recovery and harvest index changes had difference; as application at late growth stage in same nitrogen rate, total nitrogen uptake and protein content increased, nitrogen physiological efficiency and milled rice and amylose content and tasting decreased, nitrogen recovery and harvest index increased under low or medium nitrogen level and decreased under high nitrogen level. Nitrogen application 210 kg/hm2 and the ratio 4:3:3 of basal: tillering: panicle made the yield increase by 2.8%-11.3%, and this is the optimal mode of nitrogen fertilizer application. [ABSTRACT FROM AUTHOR]