远志种植管理技术

远志是山西省的道地药材,山西省襄汾县已形成规模种植,成为当地农民增收致富的主导产业,文章总结了襄汾县远志种植管理技术,为农户提供参考。     

Double hysteresis loops and enhanced mechanical quality factor of Mn-doped 0.75PMN-0.25PT ceramics

Relaxor ferroelectric 0.75 Pb(Mg_1/3Nb_2/3)O₃-0.25PbTiO₃ (0.75PMN-0.25PT) ceramics with Mn-doping concentration of 0%, 1%, 2% and 3 mol% were prepared by two-step sintering. The phase composition, microstructure, dielectric property, ferroelectric property, piezoelectric property and electromechanical property were investigated. Results indicate that all ceramics exhibit pure perovskite phases and high density. Mn-doping induces some decrease in dielectric constant ε_r, dielectric loss tanδ, remnant polarization P_r, piezoelectric coefficient d₃₃, and electromechanical coupling coefficient k_p, while significant increase in mechanical quality factor Q_m and the figure of merit (FOM) of 0.75PMN-0.25PT ceramics. For 3 mol% Mn-doped 0.75PMN-0.25PT ceramics, Q_m enhances by 1449%, FOM increases by 923%, and tanδ decreases by 67%, which makes it more suitable for high power applications. Interestingly, double P-E loops are observed in 3 mol% Mn-doped 0.75PMN-0.25PT ceramics. The phenomenon was investigated by the symmetry-conforming principle of point defects and the internal bias field.     

电磁场作用下球形磁极辅助研磨弯管内表面研究

弯管弯曲成形后,在弯折处易产生微裂纹、褶皱等表面质量缺陷问题。本文通过采用六自由度机械手拖动电磁场发生装置沿加工轨迹往复运动,电磁场发生装置驱动球形辅助磁极绕管件内壁转动,实现了对弯管内表面的光整加工。在此基础上,通过对弯管轮廓采集及曲线拟合,重新构建了弯管中心线并转换为新的研磨加工轨迹。采用超景深3D电子显微镜和触针式表面粗糙度测量仪对研磨试验前后弯管内表面的形貌和粗糙度进行了对比分析。结果表明,通过重新构建研磨加工轨迹,试验装置有效解决了研磨弯折处的干涉与研磨不均匀等问题。研磨55 min后,表面粗糙度由原始的0.713μm降低到0.194μm,铜合金弯管内表面原始质量缺陷基本去除,表面纹理较为致密均匀。该方法有效避免了未规划研磨轨迹时出现的犁耕等纹理缺陷,提高了弯管的服役可靠性。     

榆神矿区煤炭开采的地下水动态演化规律

榆神矿区浅表层水资源短缺,生态脆弱,在划分主采煤层上覆含、隔水层组合类型的基础上,采用Visual Modflow软件构建煤层开采的地下水流数值模型,研究地下水流场演化规律,统计区内地下水位观测网(56个水文观测孔)近3年的有效观测数据,掌握首采煤层开采地下水位动态变化。结果表明:2020年第四系萨拉乌苏组潜水流场与2005年统测地下水流场形态基本一致,地下水位降深值在西南部达10 m;近3年的地下水位未发生明显变化,仅YS22钻孔处受村民井取水引起水位下降。研究成果对榆神矿区地下水资源保护与利用具有重要的指导意义。     

Liquid-phase flash sintering 8YSZ with alkali halide sintering aids

The properties of ZrO₂: 8 mol% Y₂O₃ (8YSZ) ceramics with LiF and KCl sintering aids for liquid phase formation during electric field-assisted sintering were studied. Sintering experiments were carried out at 650 °C under 200 V cm⁻¹ AC electric field by varying current density, current application time, as well as LiF and KCl contents. Pellets sintered with KCl addition had cavities, cracks and fractures. Pellets sintered with 15 wt.% LiF, on the other hand, were homogeneous after thermal removal of LiF upon Joule heating. Low electric current densities coupled with longer application times produced homogeneous specimens. Three different stages were identified during sintering experiments: (i) LiF melting with the electric field applied at furnace temperatures lower than its melting point, (ii) shrinkage due to liquid phase formation and LiF removal, (iii) final densification due to grain growth and pore elimination. The electrical behavior and an estimate of the porosity were carried out by electrochemical impedance spectroscopy measurements.     

Experimental study of a metal –hydrogen reactor's behavior under the action of an external magnetostatic field during absorption and desorption

The aim of this work is to experimentally study, the behavior of a metal-hydrogen reactor (MHR) subjected to the action of an external magnetostatic field, during hydrogen absorption and desorption by the LaNi5 hydride. The reactor was surrounded by a copper coil crossed by a continuous current delivered by a DC generator. In this study, the mass of the absorbed and desorbed hydrogen was measured and plotted for different initial temperatures and pressures functions of the applied magnetostatic field. The ratio of the hydrogen mass absorbed or desorbed with and without supplying a magnetostatic field was estimated after which the change in the saturation magnetization per 1 mol of desorbed hydrogen atom (ΔM_s), for the LaNi₅ compound; was determined.The results demonstrated that while the increase in temperature was not beneficial for the absorption reaction, it improved the desorption process. The increase in pressure leads to an increase in the absorbed hydrogen mass. The effect of the applied magnetostatic field was observed especially for the lowest temperatures in the case of the absorption reaction. In fact, we noticed a small increase in the absorbed mass, which decreased and disappeared in the highest temperatures. It was found that the magnetostatic field had no effect on the desorption reaction for the tested fields and temperatures. The low value of ΔM_s confirmed the paramagnetic nature of the sample.     

小庄煤矿地应力场分布规律实测与模拟研究

地应力场主要由自重应力场和构造应力场组成,是影响井下采掘工程活动最重要和最根本的因素,掌握矿井的地应力场分布规律,对整体提高矿井的经济效益和社会效益具有重要的意义。本文在小庄煤矿区域采用套空应力解除法进行地应力场测量,并采用三维应力场反演验证测量结果,从而得出了小庄煤矿的应力分布规律,为矿井动力现象的预测预防奠定了基础。     

航天发动机叶片电解加工流场设计和试验研究

电解加工作为整体构件制造的主要技术之一,其流场设计的合理性将严重影响电解加工过程的稳定性、加工效率和质量。针对航天发动机叶片式扩压器设计了部分阻隔式反W型流场,并开展了与侧流式和反W型流场的仿真比较。仿真结果表明,该流场方式可以保证加工区电解液的高速流动,并能有效避免进/排气边漏液现象。最后,在部分阻隔式反W型流场中开展了叶片式扩压器电解加工试验,在阴极进给速度为0.5 mm/min时加工出了扩压器叶片,验证了流场设计的合理性。     

Enhanced airborne sound absorption effect in poly(vinylidene fluoride)/(K0.5Na0.5)NbO3-nanofiber composite foams

Introducing electrical conductive function to discharge local piezoelectric effect is found effective for improving airborne sound absorption performance. In this work, instead of conductive fillers, a composite with two piezoelectric materials with opposite piezoelectric responses was explored aiming at enhanced sound absorption effect. Open-cell poly(vinylidene fluoride)/(K_0.5Na_0.5)NbO₃ (PVDF/KNN)-nanofiber composite foams were proposed and investigated for airborne sound absorption purpose. Structural and thermal analyses showed that the KNN nanofibers were well dispersed in the PVDF matrix and enhanced the degree of crystallinity of polar phase of PVDF. Significantly enhanced airborne sound absorption over a broad frequency range was observed in the PVDF/KNN-nanofiber composite foams, with increasing KNN nanofibers. One possible mechanism for the improved sound absorption with the piezoelectric KNN nanofibers with positive piezoelectric coefficient added in the PVDF matrix with negative piezoelectric coefficient is that electrical discharge could be facilitated for energy dissipation with the opposite charges generated through the piezoelectric effects in the two phases with opposite polarity. The experimental results show that the open-cell PVDF/KNN-nanofiber composite foams are promising for broadband airborne sound absorption application, and our analysis shed a light on the strategy in designing piezoelectric composite foam with high sound absorption performance.     

Effects of Winding Attachment Positions on Output Characteristics of Flux‐Modulating Synchronous Machines

The flux‐modulating synchronous machine (FMSM) is a new type of multipole SM with nonoverlapping concentrated armature and field windings on the stator. This paper compares the output characteristics of two FMSMs through finite element analysis (FEA) and experiments. In both of the FMSMs, the attachment positions of the armature and field windings are swapped. To determine the reason for the discrepancies in their output characteristics, unsaturated inductances were calculated using a d‐‐q equivalent circuit. In addition, the calculated results of the inductances were confirmed through a visualization of the leakage fluxes using FEA. The results of the study show that the synchronous inductance can be reduced by attaching the armature winding to the air‐gap side of the stator teeth and that the reduction leads to an increase in output power.