神府矿区某矿井紧急通信信息规范化水平分析与研究

安全疏散过程中,信息传递是其中一个重要环节。很多事故案例表明,当事故发生时,疏散人员在疏散过程中获得的信息根本就不够完整。为保证信息流的完整,必须对紧急通信中的信息进行规范化。此次研究将结合矿井紧急通信三角模型的提法,将紧急通信信息可以精简为6个基本信息类,即“who”、“where”、“what”、“miners”、“event”和“response”;并以此作为考核指标,运用模糊数学的研究方法对神府矿区某矿井的通信信息规范程度进行评价。经模糊评价,“非常完整”、“完整”、“一般”、“不完整”4个指标的隶属度分别为0.28,0.36,0.28,0.08。     

AZ31B表面合金化接头显微组织及耐蚀性的研究

采用AZ31B镁合金真空扩散连接工艺,在AZ31B表面形成合金化扩散溶解结构。借助OM、SEM、EDS及XRD等方法分析不同工艺条件下结合界面扩散溶解层的微观组织及组成成分,利用PS-168a型电化学腐蚀测试系统对表面合金化扩散溶解层进行了耐蚀性测试。结果表明:恒温条件下,随保温时间的延长,在AZ31B表面形成宽度不等、与基材呈"锯齿"状咬合的扩散溶解层;扩散溶解层由过渡层和共晶区组成,自腐蚀电流比AZ31B镁合金基体提高约77%。     

Slagging behavior and mechanism of high-sodium–chlorine coal combustion in a full-scale circulating fluidized bed boiler

The contents of chlorine and sodium in Xinjiang Shaerhu (SEH) coal are extremely high, leading to severe slagging. In this paper, the slag was sampled from a circulating fluidized bed (CFB) boiler purely burning SEH coal, to analyze the slagging mechanism based on the characterization of morphology and composition. The results show a three-layer structure for the slag sampled from the buried heat-exchanger in the dense-phase zone of the CFB boiler. The inner layer close to the heat-exchanger is NaCl, which enhances the adhesion of ash particles, while the middle layer and the outer layer are mainly composed of Ca₂Al₂SiO₇ and other Si–Al materials. In comparison, the slag sampled from the refractory wall shows a molten state without a layered structure and mainly composed of NaCl, NaAlSiO₄, Ca₂Al₂SiO₇, and CaSiO₃. The effect of mixing bed material, on the ash melting and release of chlorine and sodium was further conducted, which indicates that the mixing of bed material has no significant effect on the release of chlorine(Cl) and sodium(Na) but highly affects the melting temperature and compositions. The ash fusion temperature reaches the lowest with a 50% mixing ratio of bed material, which is 120 °C lower than that of SEH coal ash. This study can provide better guidance for controlling severe slagging, from the combustion of high Na and Cl coal in industrial furnaces.     

Effect of singly,doubly and triply ionized ions on downconversion photoluminescence in Eu3+ doped Na2Sr2Al2PO4Cl9 phosphor: A comparative study

We report a change in the red photoluminescence of the Eu³⁺ doped Na₂Sr₂Al₂PO₄Cl₉ phosphor via doping of singly, doubly and triply ionized ions. The synthesized phosphors show good crystalline nature. The EDS analysis confirms the presence of desired elements in the phosphor samples. The vibrational feature of the phosphor was confirmed by FTIR analysis. The photoluminescence excitation spectra of the phosphor show three peaks at 317, 395 and 467 nm. The Eu³⁺ doped Na₂Sr₂Al₂PO₄Cl₉ phosphor emits intense red color on excitations with 395 and 467 nm wavelengths. However, the photoluminescence intensity of the phosphor is larger for 395 nm excitation. When the singly, doubly and triply ionized ions are co-doped in the Eu³⁺ doped Na₂Sr₂Al₂PO₄Cl₉ phosphor (i.e. F⁻, WO₄²⁻, MoO₄²⁻, VO₄³⁻, La³⁺, and Y³⁺) the photoluminescence intensity of the phosphor is decreased significantly. The decrease in photoluminescence intensity is due to change in local crystal structure created by these ions. Interestingly, the photoluminescence intensity of phosphor increases many times when the (Y³⁺) ion incorporated phosphor is excited with 317 nm wavelength. The CIE diagram shows color emitted in the red region of visible spectrum and the color purity is larger for triply ionized (Y³⁺) ion. Thus, the singly, doubly and triply ionized ions activated Na₂Sr₂Al₂PO₄Cl₉: Eu³⁺ phosphor may be used in displays devices, photonic devices, solid state lighting and white LEDs.     

A comprehensive DFT study of CO2 catalytic conversion by H2 over Pt-doped Ni catalysts

PtNi bimetallic catalysts show superior performance for CO₂ catalytic conversion by hydrogen, but the underlying mechanism and the key elementary steps in controlling the activity and selectivity of CO₂ hydrogenation remain unclear. In present work, the complete reaction network for CO₂ hydrogenation has been investigated systematically over Pt/Ni (111) surface based on periodic density functional theory, and active sites and reaction mechanism have been determined. It is found that HCOOH is mainly produced by undergoing the HCOO pathways while synthesis of CH₃OH and CH₄ via RWGS+CO hydrogenation is the dominant reaction pathway, and their selectivity are determined by the competitive reaction between hydrogenation and CO bond scission of H₂COH species. The dissociation of COOH is regarded as the rate-determining step as it has the highest barrier (2.07 eV) in RWGS+CO hydrogenation. Moreover, it is observed that the doping of Pt on Ni surface can promote the transformation of CO₂ into chemisorbed CO₂^δ− and reduce the barrier in H₂ dissociation, which further facilitate the activation and hydrogenation of CO₂. More importantly, the doped Pt atom could promote H_xCO hydrogenation to H_xCOH, meanwhile, suppress H_xCOH dissociation into CH_x. Especially, the activation barrier and reaction energy for C formation is markedly enhanced, and the ability for C hydrogenation is promoted over Pt/Ni (111) surface, which could lower the possibility of coke formation. These results provide helpful information in understanding the process of CO₂ hydrogenation at atomic scale, and could benefit for the synthesis of Ni-based bimetallic catalysts.     

Transparent lead lanthanum zirconate titanate (PLZT) ceramic fibers for high-frequency ultrasonic transducer applications

This paper presents fabrication of transparent lanthanum zirconate titanate (PLZT) fibers using extrusion technique. The diameter of the sintered PLZT fiber is about 400-μm, and the fibers exhibit very good transparency. Measured dielectric constant, remnant polarization and coercive field of PLZT fiber were found to be 2340, 22.5-μC/cm², and 9.8-kV/cm, respectively. The transparent piezoelectric materials may exhibit great potential for Photoacoustic (PA) imaging and hybrid intravascular imaging combining OCT and ultrasound imaging by using the transparent fiber as the path of light propagation and ultrasonic transducer material. In our study, these transparent PLZT fibers were designed to fabricate two types of high-frequency ultrasonic transducers: small aperture single PLZT fiber/epoxy composite and large aperture 1–3 PLZT fiber/epoxy composite ultrasonic transducers. Besides, a 20-μm tungsten wire phantom and the cornea of the porcine eye were also imaged with the 1–3 PLZT fiber/epoxy composite ultrasonic transducer to demonstrate its imaging capability.     

Excellent energy-storage performances in La2O3 doped (Na,K)NbO3-based lead-free relaxor ferroelectrics

Relaxor ferroelectric (FE) materials have received increasing attention owing to their great potentials for energy-storage applications, especially for the ones with high energy-storage density, efficiency and thermal stability simultaneously. A novel lead-free [(Na_0.5K_0.5)_0.97-xLi_0.03](Nb_0.94-xSb_0.06)O₃-xBi(Zn_1/2Zr_1/2)O₃ (NKLNS-xBZZ) ceramics was developed by a solid-state reaction method. The addition of BZZ has induced obvious dielectric relaxation behavior, as well as improved thermal stability of dielectric response. Furthermore, 0.4 wt.% La₂O₃ was added into the NKLNS-0.06BZZ ceramic, leading to an increased breakdown strength as a result of the reduction of grain size, improvement of bulk resistivity and decrease of dielectric loss. A large recoverable energy-storage density (∼4.85 J/cm³) and a high efficiency (∼88.2 %) as well as an excellent thermal stability (±12 %, 25–140 °C) were simultaneously obtained, together with a fast discharge rate (t_0.9∼112 ns). These results suggest that La₂O₃ doped NKLNS-0.06BZZ ceramic could become an attractive dielectric material for temperature-stable energy-storage capacitors.     

镁合金表面高转速搅拌摩擦加工区的微观组织和耐腐蚀性能

目的 采用高转速搅拌摩擦加工技术在AZ31B镁合金表面制备一层组织结构均匀化和致密化的加工层,改善镁合金表面的耐腐蚀性能.方法 采用高转速搅拌摩擦加工技术对AZ31B镁合金表面进行单道次加工,并利用XRD、OM、EBSD、TEM和SEM分析不同转速下加工区的相组成、晶粒形貌、织构特征、二次相分布和表面腐蚀形貌,利用无纸记录仪和电化学工作站分别测试加工区的热循环曲线和表面耐腐蚀性能.结果 经高转速搅拌摩擦加工之后,在AZ31B镁合金表面制备了宏观成形美观且微观组织结构明显细化、均匀化和致密化的加工区.加工区相组成与基材一致,均由α-Mg和β-Al12Mg17组成.加工区平均晶粒尺寸较基材明显细化,织构强度明显增大.随着转速的增大,加工区平均晶粒尺寸逐渐粗化,织构强度逐渐减弱,β-Al12Mg17相分布更加均匀弥散.加工区耐腐蚀性能较基材明显提升,自腐蚀电位由基材的–1.49 V增至–1.28 V,自腐蚀电流由基材的2.08×10–4 A减小至9.51×10–5 A.在转速为3000 r/min和加工速度为100 mm/min的工艺条件下,加工区展现出较佳的耐腐蚀性能.结论 高转速搅拌摩擦加工可显著细化晶粒,均匀化和弥散化析出相分布,有效改善镁合金表面耐腐蚀性能.     

High thermal conductive diamond/Ag–Ti composites fabricated by low-cost cold pressing and vacuum liquid sintering techniques

Diamond/Ag–Ti composites were fabricated by a low-cost liquid sintering technique. The Ti addition can effectively improve wetting and promote penetration in composite pores during liquid sintering. The interface structure of the diamond/Ag–Ti composite was identified as Ag/TiC/Ag–Ti/diamond. A high thermal conductivity of 719 W/mK was obtained for the 50 vol.% diamond/Ag-1 at.% Ti composite. Using a bimodal mixture (60 vol.% 150 μm + 10 vol.% 50 μm diamond/Ag-2 at.% Ti composite), a low coefficient of thermal expansion of 6.3 × 10^− 6/K still with high thermal conductivity of 687 W/mK was achieved. These composites have potential applications for thermal management of high integration electronic devices.