Engineering A-site cation deficiency into LaCoO3 thin sheets for improved microwave absorption performance

Journal of Materials Science - Rationally designing microwave absorption materials with highly efficient and tunable bandwidth is in great demand but remains a huge challenge. In this study,...     

一种有效折扣证据源的冲突证据合成方法

为解决证据组合规则中一票否决和弱决策证据在低冲突情况下出现的反直观推理的现象，提出一种有效折扣证据源的冲突证据合成方法。首先根据证据的信任函数和似然函数求得证据间的相似度，然后求出证据之间的支持程度，并确定折扣因子，最后采用Dempster组合规则合成利用折扣因子修正后的证据源。数值算例分析结果表明，改进后的证据组合方法可以有效地处理证据冲突。     

临涣选煤厂粗煤泥回收工艺优化的实践应用

临涣选煤厂针对洗选过程中存在的精煤泥旋流器组溢流跑粗、精煤泥弧形筛筛下水跑粗、精煤泥弧形筛脱水效果较差等问题，重点开展精煤泥分级旋流器组入料分配不均匀、筛分错配物影响、弧形筛脱水效果的现场攻关和研究。现场大量试验表明:通过停止精煤泥旋流器组，增加精煤泥弧形筛数量、减小筛缝尺寸，改变精煤泥弧形筛击打，改用高频脱水筛等方式，从源头上解决了精煤泥分级旋流器组跑粗，明显改善了精煤泥弧形筛筛下水跑粗的问题，提高了精煤泥弧形筛分选效果。在降低介泥灰分、减少浮选过程中粗颗粒的含量、缓解浮选回收压力、降低降低浮选油耗、提高浮选精煤灰分、保证精煤产率、节约生产成本方面有实践意义。     

2种灰色模型在矿区地表沉陷预计中的适用性

目前矿区地表单点沉陷动态预计方法主要基于传统的水准测量数据,监测方法单一,成本高,观测点易破坏,不能保证地表形变信息的实时性,且采用灰色模型进行地表沉陷预计时只针对单一模型的应用,没有结合模型自身特点分析其适用性。以袁店二矿7221工作面为试验区域,采用合成孔径雷达差分干涉测量技术监测矿区地表沉陷量,分别建立了描述沉陷量与时间关系的GM(1,1)与灰色Verhulst模型进行地表沉陷量预计,实现了矿区地表沉陷监测与动态预计一体化。通过比较、分析GM(1,1)与灰色Verhulst模型对地表沉陷量的拟合及预计结果,得出了2种灰色模型在矿区地表沉陷预计中的适用性:在矿区开采沉陷开始至活跃前期,若地表单点沉陷量曲线呈近似单峰型,则宜采用GM(1,1)进行短期预计;当矿区地表沉陷进入衰退阶段,单点沉陷量曲线呈平底饱和状态,则宜采用灰色Verhulst模型进行中长期预计。     

任意角带式输送机转弯装置应用研究

煤炭运输线路出现变向转弯时，通过多台传统带式输送机搭接实现输送，存在设备投资大、运输系统复杂、人员需求多等问题。介绍了任意角带式输送机转弯装置的工作原理、结构组成和特点，任意角带式输送机转弯装置由转向模块、改向模块、受料模块及其他辅助装置组成，当巷道转弯角度变化后，仅需要调节转向和改向滚筒即可实现带式输送机转向。该设备结构新颖、承载力大、运转安全可靠，可实现对带式输送机防逆转、制动，克服了转向运行时胶带的滑移和受力不均等问题，实现了减人提效，同时，安装时不需要开掘机电设备硐室，减少了巷道工程量，具有广阔的推广前景。     

The effect of neodymium content on dibenzothiophene HDS performance over a bulk Ni2P catalyst

Neodymium (Nd)-modified Ni₂P catalysts (Nd_xNi₂P, where x is the molar fraction of Nd to Ni₂P) have been successfully prepared. An appropriate amount of Nd can dramatically increase the surface area and promote the formation of smaller and highly dispersed Ni₂P particles. The Nd_xNi₂P catalyst with x = 0.10 exhibited the highest dibenzothiophene hydrodesulfurization activity of 97.4%, which is an increase of 35% when compared with that found for bulk Ni₂P.     

Electronic structure and absolute band edge position of tetragonal AgInS2 photocatalyst: A hybrid density functional study

Energy bands, effective mass of carriers, absolute band edge positions and optical properties of tetragonal AgInS₂ were calculated using a first-principles approach with the exchange correlation described by B3LYP hybrid functional. The results indicate that tetragonal AgInS₂ has a direct band gap of 1.93 eV, which reproduce well experimental value. Calculated effective masses of electrons and holes are both small which are beneficial to separation and migration of electron and hole pairs. This implies that AgInS₂ has good photocatalytic performance. The calculated optical characteristics indicate that AgInS₂ has a slight anisotropy for both the real and imaginary parts of the dielectric function and exhibits large optical absorption in the visible light region. Furthermore, the calculated band edge positions in (100), (010) and (001) surfaces indicate that tetragonal AgInS₂ is beneficial to the reduction and oxidation of water to hydrogen and oxygen under visible light irradiation.     

Construction of CoTiO3/BiOI p-n heterojunction with nanosheets-on microrods structure for enhanced photocatalytic degradation of organic pollutions

Herein, a novel CoTiO₃/BiOI (CTOB) p-n heterojunction with nanosheets-on microrods structure were prepared via a simple coprecipitation method for the first time. The catalysts were carefully characterized by various instruments. The CTOB heterostructures display improved photocatalytic performance towards RhB degradation. Among CTOB composites, CTOB-15 exhibits the optimal photocatalytic performance. Moreover, CTOB-15 also shows enhanced photocatalytic activity for MO and TC degradation compared to bare catalysts. The degradation rate constants for RhB and MO by CTOB-15 heterostructure are ca 1.6 and 1.4-fold higher than bare BiOI. The improved photocatalytic performance could be on account of the efficient separation of photoinduced carriers as well as enhanced light absorbance. Trapping experiments indicates that holes (h⁺) and superoxide anion radical (O₂^–) play a significant role in the removal of RhB by CTOB composites. The excellent photocatalytic activity and stability make it a promising photocatalyst in environmental remediation.     

Construction of hierarchical FeIn2S4/BiOBr S-scheme heterojunction with enhanced visible-light photocatalytic performance for antibiotics degradation

Constructing heterojunction provides a promising tactic to improve the photocatalytic efficiency of catalysts. In this paper, hierarchical FeIn₂S₄/BiOBr heterostructure photocatalysts were prepared by facile two step methods and applied to effectively remove ciprofloxacin (CIP) and tetracycline (TC) under visible light. Compared to single catalyst, FeIn₂S₄/BiOBr hybrids display significantly improved photocatalytic activity. Among the series, 6 wt% FeIn₂S₄/BiOBr shows the optimal photocatalytic performance, where the degradation efficiencies of TC and CIP are 3.15 and 2.88 times greater than pure BiOBr, respectively. Such an improvement could arise from the S-scheme heterojunctions and unique hierarchical structures, which brings stronger light absorption, higher photoexcited charge separation efficiency and superior redox ability. Furthermore, 6 wt% FeIn₂S₄/BiOBr composite exhibits excellent stability and reusability. Radical capture experiments and EPR analyses uncover that O₂^–, h⁺ and OH are primarily reactive substances during photocatalytic removal of TC. The products of TC were detected by LC-MS analyses and possible decomposition paths are proposed. Eventually, a possible photodegradation mechanism over FeIn₂S₄/BiOBr S-scheme heterojunction is proposed. These findings supply new perspective for the simple synthesis of S-scheme photocatalysts with promising applications in environment remediation.     

某型号收割机割刀机构及其传动部件惯性力平衡的研究

针对某型号收割机割刀执行及传动机构的实际工作中的性能需求,在完成机构惯性力最小的基础上,考虑实际工作情况权衡各方面因素的部分平衡的最优方案,最终得出了最优的设计参数,其研究方案可为类似杆机构惯性力平衡问题提供有益的参考。