氧化锰矿直接浸出制备硫酸锰的几个影响因素

根据云南建水锰矿一年多来的生产实践，就氧化锰矿直接浸出制备硫酸锰工业生产的几个影响因素，进行了探讨并提出了提高浸出回收率的措施。     

A general stochastic clustering method for automatic cluster discovery

Finding clusters in data is a challenging problem. Given a dataset, we usually do not know the number of natural clusters hidden in the dataset. The problem is exacerbated when there is little or no additional information except the data itself. This paper proposes a general stochastic clustering method that is a simplification of nature-inspired ant-based clustering approach. It begins with a basic solution and then performs stochastic search to incrementally improve the solution until the underlying clusters emerge, resulting in automatic cluster discovery in datasets. This method differs from several recent methods in that it does not require users to input the number of clusters and it makes no explicit assumption about the underlying distribution of a dataset. Our experimental results show that the proposed method performs better than several existing methods in terms of clustering accuracy and efficiency in majority of the datasets used in this study. Our theoretical analysis shows that the proposed method has linear time and space complexities, and our empirical study shows that it can accurately and efficiently discover clusters in large datasets in which many existing methods fail to run.     

Ultralow feeding gas flow guiding growth of large-scale horizontally aligned single-walled carbon nanotube arrays

On the basis of the rational analysis about the fluidic property of the system, an ultralow gas flow chemical vapor deposition (CVD) strategy was designed to prepare large-scale horizontally aligned ultralong single-walled carbon nanotube (SWNT) arrays. SWNT arrays could be well obtained under extremely low feeding flow of 1.5 sccm in a 1 in. quartz tube reactor. It was confirmed that the tubes grew floatingly and could cross microtrenches or climb over micro-obstacles in ultraslow gas flow. SWNTs arrays also could be formed no matter the substrate was placed vertically or upside down. The growth mechanism was discussed. Both the buoyancy effect induced by gas temperature/density difference and gas flow stability played dominant roles. More attractively, simultaneous batch-scale preparation of SWNT arrays was realized by the ultralow gas flow strategy. This new strategy turns to be more abstemious, efficient, promising, and flexible compared with the high gas flow rate fast-heating CVD processes.     

Architecture engineering of hierarchically porous chitosan/vacuum-stripped graphene scaffold as bioanode for high performance microbial fuel cell

The bioanode is the defining feature of microbial fuel cell (MFC) technology and often limits its performance. In the current work, we report the engineering of a novel hierarchically porous architecture as an efficient bioanode, consisting of biocompatible chitosan and vacuum-stripped graphene (CHI/VSG). With the hierarchical pores and unique VSG, an optimized bioanode delivered a remarkable maximum power density of 1530 mW m(-2) in a mediator-less MFC, 78 times higher than a carbon cloth anode.     

Development of single drive electrode electrical resistance tomography system

A new electrical resistance tomography system has been designed using the single drive electrode method. The bidirectional pulse current is adopted in this system as the exciting current. The model of this new method has been set up in ANSYS and validated by simulation and actual measured data. Based on this model, the influence of medium resistivity and connected resistance as well as the influence of medium distribution on the measured data is studied. The experimental results and the reconstructed images are presented at last to testify to the reliability of the new system and the feasibility of the new method.     

Application of selective implantation in Al0.5Ga0.5As/In0.25Ga0.75As/GaAs pseudomorphic single quantum wire structures

A pseudomorphic Al0.5Ga0.5As/In0.25Ga0.75As/GaAs asymmetric quantum wire (QWR) structure was grown on GaAs V-grooved substrate by low pressure metal organic vapor phase epitaxy. The formation of crescent shaped QWRs at the bottom of the V-grooves was confirmed by both transmission electron microscopy and photoluminescence (PL) spectra. The temperature dependence of PL spectra demonstrated a fast decrease of the sidewall quantum well PL intensity with increasing temperature, which originates from relaxation of carriers from well to wire region. The self-aligned dual implantation technique was successfully used to selectively disable the adjacent quantum structures. Decrease of the PL intensity of QWR at 8 K was observed after selective implantation, which resulted from a decreased number of carriers relaxed from adjacent quantum structures.     

Synthesis of single-walled carbon nanotubes by arc-vaporization under high gravity condition

Arc-vaporization is one of the common methods to synthesize single-walled carbon nanotubes (SWNTs). However the detailed synthesis mechanism is still not clear, and the synthesis of longer and chirality-selected SWNTs has not been obtained. Here influence of the gravity G = 1 g₀, 2 g₀, and 3 g₀ is studied in order to develop the synthesis method of SWNTs. Simultaneously, calculations of heat convection are also carried out by using a fluid simulation program and the results are compared with the experimental results.     

On symbolic manipulation and code generation of a hybrid three-dimensional solid element

A symbolic procedure is utilized to derive the analytical expressions of the component matrices resulting to the closed-form integration of a stiffness matrix of a hybrid finite element. In order to alleviate the expression growth problem, we employ special techniques, including the use of symmetry conditions, pattern search, and introduction of intermediate variables, so that the final form of the derived stiffness matrix is suitable for coding implementation. Application of the symbolic procedure is made on a hybrid three-dimensional 8-node solid element. The same procedure is equally applicable to other types of hybrid elements.     

Design optimization and cold RF test of a 2.6-cell cryogenic RF gun

To further improve the performance of acceler-ators, the first cryogenic normal-conducting RF gun in China was designed and manufactured. As a new and attractiv...