Metal doped black phosphorus/molybdenum disulfide (BP/MoS2–Y (Y: Ni,Co)) heterojunctions for the photocatalytic hydrogen evolution and electrochemical nitrite sensing applications

Recently, 2D semiconductor-based heterojunctions emerge as a focal point of intensive research owing to their unique properties, including efficient charge separation and large interface areas. Herein, Ni or Co-doped black phosphorus/molybdenum disulfide (BP/MoS₂–Y (Y: Ni, Co)) heterojunctions fabricate for photocatalytic H₂ evolution and electrochemical nitrite sensor. Compared to the BP/MoS₂, the BP/MoS₂–Ni and BP/MoS₂–Co exhibit enhanced H₂ performance, as 6.4139 mmol h⁻¹ g⁻¹ and 7.4282 mmol h⁻¹ g⁻¹, respectively, in the presence of Eosin-Y (λ ≥ 420 nm). Furthermore, BP/MoS₂–Co applies as an electrocatalyst on a GCE for the electrochemical detection of nitrite. To optimize the nitrite sensing performance of BP/MoS₂–Co, the effect of the pH, amount of material, scan rates, and other conditions study in detail. The BP/MoS₂–Co displays a linear response within the range of 100–2000 μM with a detection limit of 4.1 μM for DPV. This work can offer an opportunity for hydrogen systems as well as electrochemical sensor applications.     

Effect of hydroxyl and Mo doping on activity and carbon deposition resistance of hydroxyapatite supported NixMoy catalyst for syngas production via DRM reaction

The doping of the second metal Mo is expected to further enhance the carbon deposition resistance of Ni-based catalysts for syngas production via dry reforming of methane (DRM). In this study, the hydroxyapatite (HAP) was used as the support and a small Mo dosage was doped in the Ni-based catalysts to investigate the effect of intrinsic hydroxyl and Mo doping on the catalytic activity and carbon deposition resistance in DRM reaction. The catalyst characterization results show that both Ni and Mo are doped into the HAP structure with relatively uniform dispersion. The basic site strength of Ni4Mo0.2-HAP catalyst containing Mo is significantly higher than that of without Mo. The Mo dopant significantly improves the initial catalytic activity, but has minimal effect on the stability enhancement. Whether the catalyst is pre-reduced or not is crucial to the initial activity of the DRM reaction, the non-pre-reduced catalysts will go through a “self-activation” stage at the beginning of the reaction, where the “hydroxyl group” are proved to play as an “oxygen supply” for the partial oxidation of CH₄ or the oxidation of the carbon deposition in the initial stage. Only trace amount of carbon deposition is found after 100 h of DRM reaction on Ni3Mo0.2-HAP catalyst. The NiMo-HAP catalysts exhibit excellent initial activity and resistance to carbon deposition due to the synergistic effect of Ni–Mo alloy and hydroxyl groups in the hydroxyapatite support.     

基于迁移学习的采煤机摇臂传动故障研究

针对传统故障诊断方法无法有效识别并自动分类实际工况中采煤机摇臂传动故障多的非线性、非平稳信号,提出一种基于迁移学习的采煤机摇臂传动故障诊断模型。基于迁移学习思想,构建基于深度迁移学习的采煤机摇臂传动故障诊断模型;采用多标签分类及sigmoid函数,对模型进行改进,实现对采煤机摇臂传动复合故障的识别与分类;最后,通过仿真实验验证了改进模型性能,并对比了提出模型与传统智能故障诊断模型DCNN、SVM、LSTM、CNN在迁移任务中的分类准确率。结果表明,相较于传统智能故障诊断模型,基于深度迁移学习的采煤机摇臂传动故障诊断模型具有更高的诊断精度,且收敛速度更快,可提高采煤机摇臂传动系统的工作可靠性。     

长安旬东煤矿顶板分散空腔离层判别及离层位置相似模拟分析

长安旬东煤矿采掘工作面频繁遭受空腔离层水患,尤其是顶板分散空腔离层水患严重干扰采掘工作面的正常生产,通过对长安旬东煤矿矿区水文地质进行研究,分析生产采区离层的裂隙发育条件,通过判别验证顶板“空腔型”离层并进行数值模拟分析,形成针对性的水害疏放治理的4点治理建议。通过对离层水的疏放治理,可以有效避免或减少离层水害,为井下安全作业提供水文地质保障。研究过程包括了分析顶底板围岩特征、判别离层层位、离层数值验证、进行煤矿顶板分散空腔离层位置相似模拟分析、形成疏放治理建议等内容。在对特征离层水层位判别、数值验证等方面进行有效尝试的同时,补充了“分散型”离层水治理理论,丰富了井下疏水工程设计,对研究井下探放水有一定的实际意义。     

煤矿测量地理信息系统设计与应用研究

煤矿在建设和实际生产过程中,都会产生大量的测量数据信息,针对煤矿领域的测量及其数据处理工作,对煤矿测量地理信息系统进行了详细的研究.首先,对系统整体的方案框架进行了详细的介绍,从技术层面分析了系统的整体架构;然后,对信息系统在测量观测数据处理过程中涉及到的主要功能算法进行了详细研究,介绍了基础数据库和空间数据库的设计情...     

Using Al2O3 defect levels to enhance the photoelectrocatalytic activity of SnS2 nanosheets

Hexagonal SnS₂ nanosheets and Al₂O₃/SnS₂ composites were fabricated via a one-step hydrothermal synthesis method. The investigation indicates that hexagonal SnS₂ with diameters of 100–200 nm are well dispersed on the surface of Al₂O₃. The band gap of SnS₂ after coupling with 11 wt%-Al₂O₃ is reduced by 0.042 eV compared with the pure SnS_2. The composite with 11 wt%-Al₂O₃ shows the highest photocurrent density of 37 μA/cm² at 0.49 V (vs. Ag/AgCl) under visible light (λ>420 nm), which is approximately 1.2 times that of the pure SnS₂ nanosheets. Photoelectrocatalytic measurements demonstrate that an appropriate amount of Al₂O₃ can enhance the photoelectrocatalytic efficiency of SnS₂. The 11 wt%-Al₂O₃/SnS₂ composite (AOSS-11) can degrade 85.9% MB after 3 h under visible light illumination at an applied potential of 0.49 V (vs. Ag/AgCl). The highly effective photoelectrocatalytic activity of the Al₂O₃/SnS₂ composite is attributed to the efficient separation of photoinduced electron-hole pairs based on the defect levels. This work may provide a new design idea for constructing the effective SnS₂-based photocatalysts with other defective semiconductors.     

基于DSP嵌入式英语识别系统开发研究

为了适应我国互联技术与移动设备的快速发展,非常迫切需要设计一款不但又友好,而且能方便用户操作的新系统。文章使用两级识别网络,立足于连续隐含马尔可夫模型作为网络架构,构建一个每秒钟内能够处理的百万级的机器语言指令数的16位定点DSP语音芯片平台,设计出一款嵌入式英语实时识别系统;最后通过相关实验表明:该系统能够提升英语识别性能,同时还能使得内存占用量与计算复杂度得到降低。     

煤矿发电机组风闸制动系统自动化改造

我国煤炭资源的特点是难燃煤多,高灰、高硫煤比重大,煤质差且波动大,对于煤粉燃烧锅炉运行安全构成严重威胁。风闸制动系统具有煤种适应性广、环境性能好、负荷调节范围大等优点,在火电领域得到迅速发展。不过风闸制动控制系统由于具有多种不确定性因素,难以获得较为完备的知识,难于建模,故采用传统的方法很难获得理想的效果。文章首先详细分析了煤矿发电机组风闸制动系统的功能要求,然后从硬件与软件方面进行了自动化改造,取得了很好的运行稳定性。     

Towards a better understanding of polymer-based light-emitting diodes: a theoretical insight into the basic phenomena

In this contribution, we try to illustrate that quantum-chemistry calculations can prove useful to comprehend better the phenomena occurring in the active layer of polymer-based light-emitting diodes. We review the results of recent theoretical calculations conducted at the correlated level on conjugated oligomers that address several topics of prime interest in the search of new routes towards the achievement of devices with enhanced characteristics. These studies performed on oligomers representative of poly (para-phenylenevinylene) and polythiophene deal with: (i) the modeling of the optical properties of the conjugated polymers involved in the emitting layer; (ii) the investigation of the relative locations of, and relaxation phenomena taking place in, the lowest singlet and triplet excited states; and (iii) the analysis of the effects of derivatization of the conjugated backbone. The theoretical approach we follow allows us to rationalize a wide range of experimental measurements and to provide guidelines in the design of novel attractive materials.