Double pyrovanadates CaMgV2O7: Formation mechanism,phase structure,and thermodynamic properties

A double pyrovanadate CaMgV₂O₇ sample was synthesized via a facile solid-state route under an air atmosphere. The nonequilibrium formation pathways of the CaMgV₂O₇ were investigated via powder X-ray diffraction. A multistep reactions path (metavanadates–pyrovanadates–double pyrovanadate CaMgV₂O₇) was proposed to describe the formation of the CaMgV₂O₇ considering the thermodynamic and kinetic factors. The cell unit parameters of the CaMgV₂O₇ sample indicated the crystallization according to a monoclinic system with space group P12/c1(14), and the lattice parameters of a = 6.756 Å, b = 14.495 Å, c = 11.253 Å, β = 99.12, and V = 108.806 Å³. X-ray photoelectron spectroscopy also confirmed the +5 oxidation state vanadium in CaMgV₂O₇. The endothermic effects at 1033 and 1143 K were related to the incongruent melting and liquidus temperatures of CaMgV₂O₇, respectively. The comprehensive thermodynamic properties of CaMgV₂O₇ were established in both low- and high-temperature regions, utilizing a physical property measurement system and multi-high-temperature calorimetry (96 lines). The heat capacity (200 J mol K⁻¹) and entropy (198 J mol K⁻¹) at 298.15 K were computed based on the low-temperature heat capacity values, and the enthalpy of formation at 298.15 K was also estimated. The fitted high-temperature capacity can be used to obtain the changes in the enthalpy, entropy, and Gibbs free energy. This study is part of building a reliable thermodynamic database of the CaO–MgO–V₂O₅ system.     

脉冲激光与电弧布置方式对铝合金焊接熔滴过渡与焊缝形貌的影响

以2219铝合金为基板，研究了不同脉冲激光-电弧布置方式下的熔滴过渡与焊缝形貌特征，分析了熔深增加的机理. 结果表明，当脉冲激光照射母材时，脉冲激光主要提供对母材的热输入，母材温度的增加有助于促进熔滴铺展，稳定熔滴过渡过程；当脉冲激光照射熔滴缩颈时，主要提供对熔滴的力输入，蒸发反力的作用下形成"一脉一滴"，显著提高熔滴过渡频率与熔滴飞行速度，增加了熔滴对熔池的冲击力，熔深增加；当脉冲激光交替的照射熔池和熔滴时，一方面能够对母材进行加热，有助于熔滴的铺展，另一方面能够提高熔滴过渡频率，提高焊缝的均匀性.     

深井超深井钻井堵漏材料高温老化性能评价

深井超深井钻进裂缝性油气层极易发生频繁的钻井液漏失,造成严重储层损害和重大经济损失。储层段钻进过程中经常发生重复性漏失,意味着仅用酸溶率、粒度分布等常规堵漏材料评价指标已不能满足钻井液漏失控制工程需要。笔者以塔里木盆地克深气田钻井常用的核桃壳、毫米级碳酸钙为研究对象,开展了堵漏材料高温老化评价实验。实验评价结果表明,在180℃的柴油中老化24 h后,核桃壳的颜色由黄色变成黑色,质量损失率为25.16 % ,摩擦系数下降28.24 % ,抗压强度下降21.21 % ;毫米级碳酸钙的颜色由白色变成淡黄色,质量损失率为2.47 % ,摩擦系数下降1.33 % ,抗压强度基本不变;由高温老化后的核桃壳和毫米级碳酸钙所形成的封堵层,其承压能力下降了48.84 % 。分析指出,堵漏材料高温老化失效是深井超深井裂缝封堵层结构破坏并在储层段发生重复性漏失的一个重要因素。     

Parameter estimation for a morphochemical reaction-diffusion model of electrochemical pattern formation

The process of electrodeposition can be described in terms of a reaction-diffusion partial differential equation (PDE) system that models the dynamics of the morphology profile and the chemical composition. Here we fit such a model to the different patterns present in a range of electrodeposited and electrochemically modified alloys using PDE constrained optimization. Experiments with simulated data show how the parameter space of the model can be divided into zones corresponding to the different physical patterns by examining the structure of an appropriate cost function. We then use real data to demonstrate how numerical optimization of the cost function can allow the model to fit the rich variety of patterns arising in experiments. The computational technique developed provides a potential tool for tuning experimental parameters to produce desired patterns.     

Experimental investigation of different morphology textured ceramic tools by in-situ formed for the dry cutting

Surface texture is considered an important measure to improve the cutting performance of a tool. In this study, we have prepared three types of textured and conventional tools on the rake face by an in-situ formed method. During the experiment, the best parameters of three types of textured tools were selected for dry cutting AISI 1045 steel at different cutting speeds. Cutting forces, cutting temperatures, workpiece surface roughness, and tool wear were measured during the cutting process. The results showed that textured tools have significantly reduced cutting force, cutting temperature, and tool wear, and the roughness of the workpiece was improved compared with the conventional tool. The micro-pit texture tool has less stress contact region than the micro-groove width texture tool, but the micro-groove width texture tool exhibiting the best cutting performance. This investigation clearly showed that the textured tool prepared by the in-situ formed method has improved cutting performance.     

吐哈盆地克尔碱凹陷煤层煤质特征与成煤环境

为了揭示吐哈盆地克尔碱凹陷不同矿区煤质形成条件，探讨该区煤质与成煤环境的关系，基于对主采煤层样品工业分析、有害组分及灰成分指标等数据分析，在对克尔碱凹陷地层分布、含煤岩系特征等基本地质条件分析的基础上，运用煤地质学、煤岩学、煤化学等理论和方法，系统总结凹陷内各矿区煤层赋存特征、煤质特征，探讨区内煤岩煤质与成煤环境的关系。结果表明：研究区自西向东划分6个主要矿区,区内煤层主要发育于中侏罗统西山窑组（J2x）和下侏罗统八道湾组（J1b）地层之中。研究区煤质呈低灰、低硫、高挥发分特征，煤灰成分以SiO2、Al2O3为主。综合分析表明，研究区中-下侏罗统主要煤层形成于湖泊-河流三角洲淡水沉积环境，具陆相成煤特征，成煤环境温暖潮湿。     

Challenges and Opportunities of Modeling Biomass Gasification in Aspen Plus: A Review

Aspen Plus has become one of the most common process simulation tools for both academia and industrial applications. In the last decade, the number of the papers on Aspen Plus modeling of biomass gasification has significantly increased. This review focuses on recent developments and studies on modeling biomass gasification in Aspen Plus including key aspects such as tar formation and model validation. Accordingly, challenges in modeling due to specific assumptions and limitations will be highlighted to provide a useful basis for researchers and end-users for further process modeling of biomass gasification in Aspen Plus.     

氯化铵蒸发器结垢成分鉴别及原因分析

多效蒸发器结垢的问题常常发生,影响热效率和装置的正常运行。为明确导致蒸发器结垢的原因和成分,利用X射线衍射（XRD）、等离子发射光谱（ICP）、扫描电镜能谱（SEM-EDS）、偏光显微镜、拉曼光谱和离子色谱等分析测试技术,对浙江大洋生物科技集团股份有限公司的氯化铵多效蒸发器上的不明结垢物做了表征和分析。结果表明,该结垢物的主要成分为磷酸铁、氧化铝和有机物的混合物。探讨了发生上述结垢的原因,并提出相应的解决方案,减少了公司氯化铵蒸发器的结垢。     

高泉背斜地层压力测井多参数综合解释与异常高压成因

目前国内外地层压力测井解释方法较多,但大多数方法基于欠压实沉积理论并局限于单一的地层岩性,尤其是针对盆地边缘山前深层构造,单一测井参数确定地层压力误差较大,且无法解释沉积压实机制以外的异常高压。为此,将多种异常高压机制相关的测井参数进行综合解释,建立适合山前复杂构造的地层压力测井多参数计算模型,评价准噶尔盆地南缘高泉背斜高探1井的地层压力剖面,其计算结果与钻井实测数据吻合,相对误差小于3.00%.同时,基于原始沉积加载—卸载过程力学原理,利用地层压力测井多参数分析判别出高泉背斜深层各层系异常高压的形成机制。     

基于P波模量的原位胶结充填体强度预测模型研究

原位胶结充填体质量评价通常采用单轴抗压强度作为表征指标,由于在现场工程中无法快速、准确获取充填体的强度值,因此需要建立一种参数易于获取且准确的原位胶结充填体强度预测模型。基于胶结充填体物理力学参数的内在联系,从量纲平衡的角度探索了胶结充填体单轴抗压强度与P波模量的关系。根据C矿和I矿两种原位胶结充填体的密度、P波速度及取芯强度的测试数据,采用线性拟合的方法获得了基于P波模量的原位胶结充填体强度预测模型。通过对C矿和I矿的强度预测模型拟合效果分析可知,P波模量与取芯强度呈正相关性,且拟合效果较好,证明原位胶结充填体强度预测模型精度高,具有很强的实用性。