Automatic sorting of fresh tea leaves using vision-based recognition method

Mechanical tea harvesting using plucking machines is highly efficient, but harvested raw fresh tea leaves (FTLs) are always low quality because they contain a mixture of old leaves and leaf debris. To address this problem, this study developed an automatic sorting machine with a vision-based recognition method to extract high-quality FTLs from plucked raw FTLs. First, the raw FTLs were separated one by one after passing through three sequential conveyor belts with increasing speed, and were then classified into four grades using a vision-based recognition method. Finally, the FTLs were blown by air nozzles into collection boxes according to their specific grade. In the recognition method, the shape-based feature of each FTL is extracted by establishing the FTL's topological structure, and the support vector machine model is used for classification. The experimental results revealed that the vision-based recognition method performed satisfactorily with an accuracy rate of 94% and precision rate of 85%. The sorting success rate and efficiency of the automatic sorting machine were approximately 80% and 15 kg hr⁻¹, respectively. The results indicate that the developed automatic sorting machine can effectively and efficiently sort raw FTLs, which may improve the profitability and promote the automation of tea processing.     

Spiraling elliptic breathers in nonlocal nonlinear media with linear anisotropy

The dynamical properties of spiraling elliptic breathers in nonlocal nonlinear media with linear anisotropy are analytically discussed. Using a two-dimensional asynchronous fractional Fourier transform, the exact analytical solutions of spiraling elliptic breathers are obtained to the nonlocal nonlinear Schrödinger equation with unequal diffraction coefficients in the highly nonlocal limit. It is found that the spiraling elliptic breathers exhibit a kind of molecule-like libration due to the combined effects of the linear anisotropy and the orbital angular momentum. The angular velocity of the spiraling elliptic breathers is discussed, which can be controlled by the linear anisotropy parameter. In the media with linear anisotropy such as uniaxial crystals, the angular velocity of the spiraling elliptic breathers can be controlled by changing the propagation directions of optical beams. Furthermore, the nonlinearity of media is found to enhance the rotation effect of spiraling elliptic breathers.     

含钒废弃物中钒的回收研究现状及展望

金属钒具备一系列优越性质,在许多领域有着广泛的应用。综述了从含钒钢渣、提钒尾渣、失活催化剂以及钒电池失效电解液等含钒废弃物中回收钒的方法,主要阐述了各种方法的原理、优缺点及发展趋势,介绍了回收钒的新工艺并指出提钒工艺的未来发展方向。     

制备金属铪的新进展

金属铪在核能、航天以及军工领域有着得天独厚的优势,国内外对于金属铪的研究正如火如荼的进行。锆铪相伴而生,本文介绍了锆铪的火法和湿法分离,综述了金属热还原法和熔盐电脱氧法制备金属铪通过熔盐电解法、碘化精练法、电子束熔炼法精炼金属铪,就各种方法的优缺点和绿色生产的需求来看,新型熔盐电脱氧法和联合精炼法是值得发展和探究的方向。     

某铜冶炼渣选矿厂SAB流程磨机衬板与钢球优化实践*

目前大多数铜冶炼渣选矿厂采用半自磨机—球磨机流程（SAB流程）进行粉磨作业，由于铜冶炼渣硬度大、性脆、易碎难磨，磨机衬板及磨矿介质消耗较大。针对某铜冶炼渣选矿厂开展了SAB流程衬板和钢球的优化研究。结果表明：①半自磨机用压条型铬钼钢衬板替代整体式锰钢衬板，使用寿命提高106.67%；球磨机用橡胶衬板替代锰钢衬板，使用寿命提高30%以上；检修强度大幅度降低，设备运转率明显提高。②半自磨机和球磨机由添加铸造钢球变更为锻造钢球，失圆率大幅降低；半自磨机补加球球径由120 mm调整为140 mm，增强了冲击破碎效果；球磨机补加钢球球径由60 mm调整为50 mm，磨矿浓度从75%提高到80%，研磨效果得到改善。③在磨矿细度保持不变的情况下，系统台时处理能力提高15.55%，钢球消耗降低26.32%，电力单耗降低26.67%，单位磨矿成本降低29.07%。企业经济效益和社会效益得到显著提高，对同行业具有一定的参考价值。     

A novel numerical method for steady-state thermal simulation based on loop-tree and HBRWG basis functions

Abstract

This article presents a novel numerical method for steady-state thermal simulation. This method firstly solves the heat flux efficiently by applying the loop-tree basis functions. Then, the temperature is obtained by finding solutions of the gradient equation. The half boundary Rao-Wilton-Glisson (HBRWG) basis functions are employed for handling arbitrary boundary conditions. In addition, the triangulation-based interpolation technique is utilized to interpolate temperature profile with obtained results in post-processing. Three examples with mixed boundary conditions are studied to validate the accuracy of proposed method for simulating steady-state thermal problems. Numerical results show that our method has a good accuracy and is well capable of handling arbitrary boundary conditions.     

Joining of dense Si3N4 ceramics with tape cast Lu-Al-Si-O-N interlayer

Lu-Al-Si-O-N tapes with different thickness were used to join gas pressure sintered Si₃N₄ ceramics. The microstructure of the joints and the influences of the joint thickness and joining temperature on the bonding strength of the as-joined Si₃N₄ ceramics have been investigated. The highest bonding strength about ~ 300 MPa of the joined specimens was achieved by using 450 µm interlayer at 1450 °C. The existence of Si₃N₄ nanowires was beneficial for the improvement of the bonding strength by interweaving the oxynitride glass matrix in the joint region.     

选区激光熔化316L不锈钢的各向组织与性能

对采用选区激光熔化(SLM)制备的316L不锈钢增材制造试样进行了横向、纵向力学性能与微观组织分析。结果表明,增材制造SLM试件亚结构组织由尺寸为0.4 μm左右的胞状组织所构成,组织之间无明显的成分偏析,纵向与横向拉伸强度分别达到808和713 MPa,在经过1050 ℃热处理后,原组织中部分胞状组织消失,纵向及横向强度分别下降到673 MPa及579 MPa,增材制造试样相对传统热轧试样(550 MPa)具有明显的强度优势。SLM试样组织中存在未熔合缺陷,缺陷几何形状的方向性对其在拉应力作用下连接成裂纹有显著影响。热处理后缺陷长度方向与拉伸应力平行的纵向试样伸长率达到47.5%,横向试样伸长率为20%,伸长率指标均显著低于热轧316L钢试样,未熔合缺陷是导致3D打印试件塑性指标降低的主要因素之一。     

加工切割精度对研磨的影响

本文主要介绍了在加工基板边部时,需将控制边部质量放在首。对于边部质量控制的重要环节是切割工序,切割的精度将直接影响到研磨边部的质量,从而影响边部良品率。因此,切割精度是作为控制边部质量的第一要素。     

New insight to the oxidation kinetics of silicon-containing steel at high temperature

This study investigated the oxidation kinetics of silicon-containing steel at 1150–1300 °C using a Simultaneous Thermal Analyzer under atmospheric conditions similar to that of an industry reheating furnace. There is a critical time point for the oxidation kinetics at an oxygen concentration of 4·0 vol.-%., following which the oxidation rate constant increases with the increasing oxidation temperature. The model coefficient A in the kinetic oxidation equation was found to be constant. However, before the critical time point, the oxidation rate constant remained unchanged; the model coefficient A decreased with the increasing temperature. Therefore, the kinetic model of silicon-containing steel for isothermal oxidation was observed to be a modified one on the basis of the experimental data. In addition, the critical time point was prolonged with the increasing isothermal oxidation temperature. Moreover, the oxidation activation energy of the tested silicon-containing steel was 366·16 kJ mol^?1.