Influence of operation number on arc erosion behavior of Ag/Ni electrical contact materials

Arc erosion behavior of Ag/Ni materials with different operation numbers was investigated by OM, 3DOP and SEM. The results indicated that the arc erosion of Ag/10Ni electrical contact material fabricated by sintering? extrusion technology was more and more serious with the operation numbers increasing from 1000 to 40000. With the same operation numbers, the arc erosion on anode was more serious than that on cathode. Besides, the pores preferred to emerge around the arc effect spot during the first 10000 operations. And the morphology of the molten silver on cathode and anode was different due to the action of gravity and arc erosion. Furthermore, the relationships among arc energy, arc time, welding force, electric resistivity, temperature and mass change on contacts were discussed, which indicated that the mass loss on cathode was mainly caused by the fracture of molten bridge.     

论中国设计理论与技术创新——技术设计学体系基本问题研究论纲①

一年一度的“中国设计理论与‘中国工匠’培育高端论坛”旨在探讨、研究与实践中国设计理论体系的当代建构问题，以期对中国未来发展做出中国设计理论界自己的努力和贡献。本研究聚焦设计与技术之内在逻辑关系的探讨，重点探索中国设计理论与技术创新问题。系统考察与研究中国设计理论的概念、基本内涵、特征及其价值；深入探讨如何把握技术创新的基本内涵、价值追求及其当代意义；特别考察中国设计理论建设中的技术创新问题。本次的亮点是设计治理理论问题的提出与探索，具有极大的现实价值和理论意义。这些问题正是中国当代文化转型发展的重大理论问题。本研究尝试性探讨技术设计学体系建构的基本问题。     

融合大数据技术和工艺经验的高炉参数优化

 为了更精准地评判高炉运行情况，量化高炉指导方针。根据高炉生产过程的特点，应用大数据技术对高炉生产参数与铁水产量和高炉能耗等指标进行数据驱动分析，提出了一种优化高炉生产参数的新方法。首先，对某钢铁厂高炉各工序历史数据进行了采集、清洗、过滤和整合，建立了高炉数据仓库。然后，将多种聚类算法相结合，完成了对高炉炉况变化的详细划分。运用工艺经验与递归特征消除算法相结合，全面筛选得到能够反映炉况波动的强相关变量。应用统计学方法分析得出Class_a炉况对应的核心参数的最优范围，这对指导现场生产、保持高炉长期稳定顺行具有重要意义。     

Estimation of Antenna Correlation Coefficient of N-Port Lossy MIMO Array

This paper proposes a simple yet accurate method for estimating the antenna correlation coefficient (ACC) of a high-order multiple-input multiple-output (MIMO) antenna. The conventional method employed to obtain the ACC from three-dimensional radiation patterns is costly and difficult to measure. An alternate method is to use the S-parameters, which can be easily measured using a network analyzer. However, this method assumes that the antennas are highly efficient, and it is therefore not suitable for lossy MIMO antenna arrays. To overcome this limitation, we define and utilize the non-coupled radiation efficiency in the S-parameter-based ACC formula. The accuracy of the proposed method is verified by the simulation results of a 4-port highly coupled lossy MIMO array. Further, the proposed method can be applied to N-port arrays by expanding the calculation matrix.     

Hydrodistillation condition adjustment for different material particle sizes: a method to increase batch‐to‐batch quality consistency

Varying material particle sizes represent a common contributing factor to the batch‐to‐batch variation of extraction yields. To increase the batch‐to‐batch quality consistency of extracts, a method was proposed to adjust the extraction conditions for different material particle sizes, taking the hydrodistillation extraction process of Radix Curcumae and Fructus Gardeniae as a case study. Statistical models were built for five sesquiterpenes including curcumenone, curcumenol, curdione, curzerenone and furanodienone, to quantitatively describe the effects of particle size and process parameters on their extraction yields. An increase in sodium chloride concentration remarkably increased the yields of curcumenone and curcumenol, and a larger solvent‐to‐solid ratio increased the yields of five sesquiterpenes. Under the adjusted process parameters for two different particle sizes, the yield for each compound was controlled to fall in the 90–110% target range. The proposed method can be applied to various extraction processes of foods and herbal medicines.     

Cutting parameter optimization for one-step shaft excavation technique based on parallel cutting method

The outcome of the cutting blasting in a one-step shaft excavation is heavily related to the cutting parameters used for parallel cutting method. In this study, the relationships between the cutting parameters (such as the hole spacing L and the empty hole diameter D) and damage zones were investigated by numerical simulation. A damage state index γ was introduced and used to characterize the crushing and crack damage zones through a user-defined subroutine. Two indices, i.e., η₁ and η₂ that can reflect the cutting performance, were also introduced. The simulation results indicate that an optimal value of L can be obtained so that the η₁ and η₂ can reach their optimal states for the best cutting performance. A larger D results in better cutting performance when the L value maintains its best. In addition, the influences of the loading rate and the in-situ stress on the cutting performance were investigated. It is found that an explosive with a high loading rate is suit for cutting blasting. The propagation direction and the length of the tensile cracks are affected by the direction and the magnitude of the maximum principal stress.     

Variability in rheology of cemented paste backfill with hydration age,binder and superplasticizer dosages

The use of (CPB) material to ameliorate geotechnical stability of underground mine is in nascent stage in India. Rheological properties of CPB change with travelling time as it is transported to underground mine stope through pipeline reticulation. In this paper, rheological properties of CPB based on mill tailings of a carbonate rich mineral processing waste are evaluated for different dosages of polycarboxylate (PC) based (SP). Each CPB sample having 78?wt% solids is mixed separately with 4%, 6% or 8% of binder dosages (ratio of the weight of dry binder to the weight of dry tailings) and, 0%, 0.5%, or 1.0% of SP dosages as weight of dry binder. The paper presents a methodology for determining yield stress, plastic viscosity and thixotropic behaviour of CPB mixture as a function of hydration age, binder and SP dosages. Results from the experimental campaigns indicate that SP content has significant influence on rheological behaviour of CPB and can be suitably exploited to enhance the flow characteristics of the carbonate rich process tailings. The study also develops multivariate linear regression models of yield stress, plastic viscosity and thixotropy of CPB depending on the hydration age, binder and SP dosages.