The effect of high-temperature annealing on LaFe_(11.5)Si_(1.5) and the magneto-caloric properties of La_(1-x)Ce_xFe_(11.5)Si_(1.5) compounds

The powder X-ray diffraction patterns of LaFell.sSil.5 compounds annealed at different high temperatures from 1323 K （5 h） to 1623 K （2 h） show that a large amount of 1：13 phase begins to form in LaFell.sSiL5 compound annealed at 1423 K （5 h）. In the temperature range from 1423 to 1523 K, ^-Fe and LaFeSi phases rapidly decrease to form 1：13 phase. LaFeSi phase is rarely observed, and the most amount of 1：13 phase is obtained in the compound annealed at 1523 K （5 h）. With the annealing temperature increasing to 1573 and 1623 K, LaFeSi is detected again in the LaFell.sSil.s compound. According to the results of annealing at different high-temperatures, the Lal-xCexFelt.sSit.5 compounds are annealed at high temperatures of 1373 K （2 h） ＋ 1523 K （5 h）. The main phase is NaZn13-type phase, and the impurity is a small amount of et-Fe in Lal-xCexFexx.sSil.5 compounds with 0 〈 x 〈 0.35, and there is a large amount of CeaFe17 phase in Lao.sCeo.sFela.sSil.s. It indicates that the substitution of cerium atoms for La in LaFelLsSil.5 compounds has limit. At the same time, the substitution of Ce for La has large effect on magnetocaloric properties. With increasing Ce content from x = 0 to x = 0.35, the Curie temperature decreases linearly from 196 to 168 K, the magnetic entropy change increases from 16.5 to 57.3 J-kg-kK-1 in a low magnetic field change of 0-2 T, and the thermal hysteresis also increases from 3 K to 8 K.

高含水率钻孔桩排放泥浆絮凝脱水影响因素试验研究

为解决高含水率钻孔桩排放泥浆难以处理、直接外运的成本高、易撒漏及对环境影响高等问题,采用絮凝法对泥浆进行絮凝作用,使其快速泥水分离,实现钻孔桩排放泥浆减量化,为钻孔桩排放泥浆的处理提供参考。通过泥浆的沉降柱、浊度、比过滤阻力、脱水泥饼含水率试验,结合有机絮凝剂FN剂、无机絮凝剂FP剂与不同水力参数的角度,研究泥浆絮凝脱水效果的影响因素。结果表明:添加适宜掺量的FN与FP,在合适的水力参数下具有优异的脱水效果;当转速为400 r/min时,脱水后泥饼含水率降至97.4%;当搅拌时长为120 s时,脱水后泥饼含水率降至90.4%;而脱水泥饼含水率则随着搅拌温度的增加呈现轻微降低,含水率从15℃时的97.8%降至40℃时的89.1%。在添加复掺絮凝剂后,钻孔桩排放泥浆的比阻值低至4.4×10^(12)m/kg,显著低于单掺下的泥浆比阻值。FN和FP联合投加有效发挥电中和及网捕-卷扫作用;絮凝剂通过吸附架桥作用使泥浆颗粒发生明显聚集效果。因此,在适宜的水力条件下,合适的复掺絮凝剂对高含水率泥浆处理效果显著。

Dynamic characteristics of high stressed red sandstone subjected to unloading and impact loads

In the process of deep projects excavation,deep rock often experiences a full stress process from high stress to unloading and then to impact disturbance failure.To study the dynamic characteristics of three-dimensional high stressed red sandstone subjected to unloading and impact loads,impact compression tests were conducted on red sandstone under confining pressure unloading conditions using a modified split Hopkinson pressure bar.Impact disturbance tests of uniaxial pre-stressed rock were also conducted(without considering confining pressure unloading effect).The results demonstrate that the impact compression strength of red sandstone shows an obvious strain rate effect.With an approximately equal strain rate,the dynamic strength of red sandstone under confining unloading conditions is less than that in the uniaxial pre-stressed impact compression test.Confining pressure unloading produces a strength-weakening effect,and the dynamic strength weakening factor(DSWF)is also defined.The results also indicate that the strain rate of the rock and the incident energy change in a logarithmic relation.With similar incident energies,unloading results in a higher strain rate in pre-stressed rock.According to the experimental analysis,unloading does not affect the failure mode,but reduces the dynamic strength of pre-stressed rock.The influence of confining pressure unloading on the shear strength parameters(cohesion and friction angle)is discussed.Under the same external energy impact compression,prestressed rock subjected to unloading is more likely to be destroyed.Thus,the effect of unloading on the rock mechanical characteristics should be considered in deep rock project excavation design.

Characteristics and displacement mechanisms of the dispersed particle gel soft heterogeneous compound flooding system

Considering high temperature and high salinity in the reservoirs, a dispersed particle gel soft heterogeneous compound(SHC) flooding system was prepared to improve the micro-profile control and displacement efficiency. The characteristics and displacement mechanisms of the system were investigated via core flow tests and visual simulation experiments. The SHC flooding system composed of DPG particles and surfactants was suitable for the reservoirs with the temperature of 80-110 °C and the salinity of 1×10~4-10×10~4 mg/L. The system presented good characteristics: low viscosity, weak negatively charged, temperature and salinity resistance, particles aggregation capacity, wettability alteration on oil wet surface, wettability weaken on water wet surface, and interfacial tension(IFT) still less than 1×10^(-1) mN/m after aging at high temperature. The SHC flooding system achieved the micro-profile control by entering formations deeply and the better performance was found in the formation with the higher permeability difference existing between the layers, which suggested that the flooding system was superior to the surfactants, DPG particles, and polymer/surfactant compound flooding systems. The system could effectively enhance the micro-profile control in porous media through four behaviors, including direct plugging, bridging, adsorption, and retention. Moreover, the surfactant in the system magnified the deep migration capability and oil displacement capacity of the SHC flooding system, and the impact was strengthened through the mechanisms of improved displacement capacity, synergistic emulsification, enhanced wettability alteration ability and coalescence of oil belts. The synergistic effect of the two components of SHC flooding system improved oil displacement efficiency and subsequently enhanced oil recovery.

Structural stability and electrical properties of AlB_2-type MnB_2 under high pressure

The structural stability and electrical properties of AlB2-type MnB2 were studied based on high pressure angledispersive x-ray diffraction, in situ electrical resistivity measured in a diamond anvil cell(DAC) and first-principles calculations under high pressure. The x-ray diffraction results show that the structure of AlB2-type MnB2 remains stable up to 42.6 GPa. From the equation of state of MnB2, we obtained a bulk modulus value of 169.9±3.7 GPa with a fixed pressure derivative of 4, which indicates that AlB2-type MnB2 is a hard and incompressible material. The electrical resistance undergoes a transition at about 19.3 GPa, which can be explained by a transition of manganese 3d electrons from localization to delocalization under high pressure.

永磁同步电机全转速范围无位置传感器控制

为解决IF控制启动速度偏慢、启动转矩能力薄弱等问题,采用高频脉振电压注入法完成电动机零低速启动,并结合中高速区有效磁链法形成全转速范围无位置传感器复合控制策略。为了实现两种控制方法的平滑切换,提出一种基于转速过渡区与状态机结合的滞环切换策略,所提策略将全转速范围划分为零低速区、过渡区以及中高速区,电动机由中高速区进入过渡区时提前开启高频脉振电压注入法,使其位置估计过程达到稳定,为切换做好准备。为了减小注入高频电压对有效磁链法位置估计过程的冲击,在转速过渡区采用软开启的方式实现高频脉振电压注入法的投入与退出。针对转速过渡区两种位置估计方法同时工作时的耦合问题,设置了双同步旋转坐标系,实现了转子位置估计的解耦控制。在一台三相永磁同步电机上对所提方法的有效性进行了验证。

人工智能驱动制造业高质量发展的复合效应研究——基于知识创造与知识地理溢出的双重机制

人工智能作为新一轮产业变革的核心驱动力,对于推动我国制造业高质量发展具有战略意义。本文从技术创新的视角出发,剖析人工智能通过知识创造机制、知识地理溢出机制,提升制造业生产效率的复合效应。利用2012—2021年四大智能制造与数字经济发展先行区的省域面板数据,通过随机前沿生产函数和中介效应模型验证了上述的复合效应。研究结果表明:在组织层面,应当以制造业产业集群为人工智能应用的主体形式;在区域层面,注重区域的软、硬制度要素的构建,推动区域的数字化水平提升和新基建的建设。只有这样,才能充分发挥人工智能对于制造业生产效率提升的势能,促进人工智能在区域的长期“根植性”。

食品中季铵盐类消毒剂检测方法建立及北京市市售食品及膳食样品中含量分析

建立了一种基于超高效液相色谱-串联质谱检测蔬菜、水果、水产等多种食品基质中9种常用季铵盐类消毒剂的分析方法。样品采用改良的QuEChERS(Quick、Easy、Cheap、Effective、Rugged、Safe)法净化,BEH C_(18)色谱柱(100 mm×3.0 mm,1.7μm)分离,电喷雾电离质谱正离子模式下分析。方法学考察结果表明,蔬菜、水果、水产中9种季铵盐的检出限为0.2~5.0μg/kg,定量限为1.0~10.0μg/kg,在各自的检测范围内有良好的线性关系(R^(2)>0.99),平均回收率为65.24%~118.63%,相对标准偏差为0.19%~6.77%。使用本方法检测北京市市售食品季铵盐含量,阳性样品检出率为30.43%;检测北京市膳食样品季铵盐含量,阳性样品检出率为12%,膳食摄入风险在可接受范围内。

High pressure effects on the crystal structure andelectric conductivity of perovskite like (Ca/Sr)_2CuO_2Cl_2 compounds

The crystal structure stability as well as electric conductance of (Sr/Ca)_2CuO_2Cl_2 compound with K_2NiF_4 structure was investigated up to 31 GPa using diamond anvil technique. It seems that (Sr/Ca)_2CuO_2Cl_2 is quite stable under pressure but with obvious anisotropic compressibility. The equation of state (EOS) obtained shows relative large bulk modulus.

复方保健酒中8种有效成分检测及其稳定性分析

该研究采用高效液相色谱(HPLC)法建立测定复方保健酒中8种有效成分(5-羟甲基糠醛、腺苷、虫草素、N6-(2-羟乙基)腺苷、苦番红花素、芦丁、西红花苷Ⅰ、西红花苷Ⅱ)的方法,并对酒样中8种有效成分的稳定性进行分析。结果表明,最佳色谱条件为:采用Agilent SB-Aq C18色谱柱(4.6 mm×250 mm, 5μm),以乙腈-0.1%乙酸水溶液为流动相,流速1.0 mL/min,检测波长260 nm/440 nm,柱温30℃,进样量10μL。在该分析条件下,8种有效成分在各自质量浓度范围内线性关系良好(R^(2)≥0.999 9),检出限(LOD)为15.5~146.1μg/L、定量限(LOQ)为45.5~429.7μg/L,精密度、稳定性、重复性试验结果的相对标准偏差(RSD)均<2.0%,平均加标回收率为96.15%~99.23%。样品稳定性试验结果表明,在不同的贮存条件下贮存90 d,腺苷、虫草素、N6-(2-羟乙基)腺苷、苦番红花素稳定性较好;5-羟甲基糠醛对温度较敏感;芦丁、西红花苷Ⅰ、西红花苷Ⅱ对光和热均极其敏感。

养殖水体NO_(2)^(-)-N降解复合菌剂制备及特性研究

随着我国水产养殖规模也逐年上升,养殖水体中氮化合物累积问题日益严重。为实现我国水产行业的安全生产,本文筛选出一种NO_(2)^(-)-N降解菌,并与光合菌、乳酸菌进行复配以此制备复合菌剂。通过单因素试验分析温度、pH值、亚硝酸盐初始浓度、菌种接种量等对NO_(2)^(-)-N降解的影响,确定不同影响因素下复合菌剂的最佳降解效果和生长状态。研究结果表明,从活性淤泥中筛选带1株具有高效NO_(2)^(-)-N氧化性质的菌株A3,并与光合细菌(Rhodopseudomonas palustris)、乳酸菌(Lactobacillus acidophilus)按照32∶2∶1混合,该比例降解效率最高。复合菌剂在40℃,pH值为9.0、pH值为6.0的条件下,OD600值稳定在0.2~0.4,对NO_(2)^(-)-N的降解率保持在50%左右。复合菌剂在25℃,pH值为7.5的条件下长势最好,降解率最高;复合菌剂的降解率随初始NO_(2)^(-)-N浓度的升高而降低,OD600值变化不明显,表明复合菌剂与A3菌株对NO_(2)^(-)-N有很强的耐受性,能够在0.1~8.0 g/L的条件下维持降解活性,保持一定的降解速率。

Ionic effective radii under high-temperatures state

REFERENCES [1, 2] prove that ionic radii will increase or decrease with temperature rising orlowering. If the ionic radii at room temperature are known, many phenomena of the ioniccompounds occurring at room temperature can be explained. Also if the ionic radii at high tem-perature are known, many phenomena of the ionic compounds occurring at high temperaturecan also be explained. Therefore, to calculate the effective radii of ions at high temperature isconsidered of great significance. For example, the 'investigation of KIO3-CsIO3

木质素快速热裂解试验研究

在红外辐射加热反应器中对生物质的主要组分木质素进行了热裂解试验研究,分析了木质素热裂解产物的产量随温度的变化规律.试验结果表明,在350～800℃,焦炭产量随温度升高而降低,最后趋近质量分数稳定值约为26%;焦油产量随温度升高而增大,在550℃出现质量分数为27%的最大产量,温度进一步升高,部分挥发分的二次裂解使焦油产量降低而轻质气体产量大大增加;气体产物主要有H2、CO、CO2、CH4以及CnHm,其产量随着温度的升高都呈增长趋势.结合木质素热裂解焦油的色谱傅立叶红外光谱(GCFTIR)分析,发现焦油中主要是含有甲氧基、烷基、羟基等官能团的苯酚和酸、酮类化合物,甲酸和乙酸随着温度升高二次裂解加剧导致产量降低.对比纤维素热裂解试验结果可以发现,纤维素对焦油的生成贡献最大,而木质素热裂解主要是生成轻质气体和焦炭.

高效安全的敌草快和百草枯液相色谱分离分析技术

研究了KC lO4、KBF4和KPF6"离液试剂"的浓度及流动相组分对敌草快和百草枯分离的影响。优化后的实验条件是:20 mmol/L的KPF6,在pH=3的条件下用100%的水作为流动相,配合一根耐水性>95%水的反相柱。实验结果无论在保留值的控制、柱效和色谱峰的对称性各方面都优于传统的"离子对"方法。

冻胶分散体软体非均相复合驱油体系特征及驱替机理

针对高温高盐油藏研发了具有微观调控能力并可兼顾驱油效率的冻胶分散体软体非均相复合驱油体系,借助岩心流动实验和可视化实验,研究该体系特征及驱油机理。该体系由冻胶分散体和表面活性剂组成,适用于温度80~110℃、矿化度1×104~~10×10~4 mg/L的油藏,具有低黏度、弱负电性、耐温耐盐的特点,能够聚结长大,使油湿表面润湿性发生反转,水湿表面润湿性减弱,高温老化后的界面张力仍小于1×10^(-1) mN/m。软体非均相复合驱油体系能够进入岩心深部对储集层进行微观调控,岩心渗透率级差越大,调控效果越好,其驱替效果明显优于表面活性剂驱油体系、冻胶分散体或聚合物-表面活性剂二元复合驱油体系。复合驱油体系在多孔介质中的调控行为有直接封堵、架桥封堵、吸附及滞留4种,其中的表面活性剂可强化复合驱油体系的深部运移和洗油能力,通过强化洗油机理、协同乳化机理、强化润湿反转及油带聚增机理提高洗油效率,冻胶分散体和表面活性剂的协同效应增强了复合驱油体系的驱替效率。

复方五仁醇胶囊含药血清指纹图谱与保肝作用的谱效关系

目的:阐明复方五仁醇胶囊保肝作用的药效物质基础.方法:将大鼠灌胃给药分别制备复方五仁醇胶囊及五味子、三七、柴胡、叶下珠4味药的阴性制剂和单味制剂含药血清,对获得的9组含药血清按已经建立的指纹图谱条件进行HPLC测定,同时考察它们对CCL4诱导的损伤肝细胞的增值(MTT法)及丙氨酸氨基转移酶(ALT)泄漏的影响,最后进行谱效关系分析.结果:指纹图谱显示,单味五味子及三七、柴胡、叶下珠阴性制剂含药血清中均检测到大鼠灌服全方制剂后血液中产生的13个药源性成分,而五味子阴性制剂及单味三七、柴胡、叶下珠含药血清中均未检测到药源性成分;药效结果显示,全方、单味五味子及三七、柴胡、叶下珠阴性制剂含药血清对肝细胞损伤均具有明显的保护作用,而单味三七、柴胡、叶下珠含药血清及五味子阴性制剂含药血清作用不明显,且单味五味子与全方制剂含药血清组之间药效无显著差异.谱效之间具有很好的相关性.结论:复方五仁醇胶囊保肝作用的药效物质基础主要来自君药五味子所含有的木脂素类成分.

生物质快速热解过程中产物的在线测定

利用U形反应器与FTIR联动方法对7种生物质在600℃快速热解1min时的热解产物进行了在线测定,同时还进行了不同温度(400℃和800℃)和添加二氧化硅、硅藻土、石灰石等对热解产物影响的研究.结果显示,不同生物质的热解产物有明显差别,但主要产物为CO,CO2,CH4,CH3CH∶CH2,CH3COCH3等;温度是影响生物质有机质分解产物组成的重要因素,低温(400℃)产物中的CO含量明显偏低,而醛类、酮类、酯类等含量随着温度升高而下降;不同添加剂对生物质热解产物的影响不同,硅藻土的催化效果要优于其他2种.实验结果也表明了这一系统对测定生物质快速热解过程中产物组成的有效性.

酚醛树脂种类及用量对天然橡胶/溴化丁基橡胶高阻尼胶料性能的影响

研究酚醛树脂种类及用量对天然橡胶(NR)/溴化丁基橡胶(BIIR)高阻尼胶料性能的影响。结果表明:与采用热塑性烷基酚醛树脂203的胶料相比,采用热反应性辛基酚醛树脂HY-2045的胶料的硫化速率较快,邵尔A型硬度和拉伸强度较高,拉断伸长率略低,有效阻尼温域较宽;随着热反应性辛基酚醛树脂HY-2045用量的增大,胶料的有效阻尼温域呈现变宽的趋势,但高温区域(>0℃)的阻尼性能呈现下降的趋势。

SPE-HPLC测定利咽颗粒中的牛蒡子苷的含量

目的 采用固相萃取 高效液相色谱法分离测定利咽颗粒中的牛蒡子苷的含量。方法 色谱柱为WatersC18柱 ( 2 5cm×4 .6mm ,5 μm) ;柱前加预柱 ( 2 .5cm× 4 .6mm) ,流动相 :乙腈 0 .0 2 %磷酸溶液 ( pH =2 .85 ) ( 2 0∶80 ) ;柱温 35℃ ;检测波长为2 2 8nm ;流速 1.0mL·min-1。结果 牛蒡子苷的平均绝对回收率为 ( 90 .16± 1.4 5 ) % ,RSD为 1.6 1% ;平均相对回收率( 99.74± 1.6 9) % ,RSD为 1.6 9%。结论 本方法准确可靠、重复性好 ,样品净化完全 ,杂质干扰小 ,牛蒡子苷得到了很好的分离 。

炭黑DZ13和白炭黑VN3在高性能轮胎胶料中的应用

研究了低滞后炭黑DZ13和高分散性白炭黑VN3对NR/SSBR(溶聚丁苯橡胶)硫化胶物理机械性能和动态力学性能的影响。结果表明,与普通炭黑N234相比,低滞后炭黑DZ13和高分散性白炭黑VN3能够大幅度降低轮胎生热;与DZ13相比,VN3硫化胶的储能模量(G′)随填充量增加变化幅度较大,损耗因子(tanδ)比DZ13硫化胶小很多;DZ13硫化胶的Payne效应随用量增加而增加,临界应变也随之减小,而VN3硫化胶的Payne效应比DZ13硫化胶强,临界应变也大得多,而且存在两段G′明显下降的过程,表明VN3形成了一种更强的填料网络;高DZ13用量的硫化胶动态力学性能的温度依赖性不符合交联网络弹性理论,VN3硫化胶动态力学性能的温度依赖性更大。