Geochemical characteristics of the Permian marine mudstone and constraints on its provenance and paleoenvironment in the Fenghai area, Fujian Province, southeastern China

Permian marine strata have gradually become a research focus in the world. The marine strata of the Late Permian Dalong Formation (P₃d) in the Fenghai area, Fujian Province, have become more and more important as their geochemical characteristics record important geological information and are a good indicator for recovering and reconstructing the paleosedimentary environments and tectonic attributes. The major elements, trace elements and rare earth elements were analyzed by XRF and ICP-MS, respectively. Based on the results of detailed field geological surveys, profile measurements as well as typical sample collection, the tectonic setting and provenance of Permian marine mudstone were comprehensively discussed. The results showed that the Dalong Formation (P₃d) was deposited in an active continental margin tectonic environment as revealed by the relation between Fe₂O₃ + MgO and TiO₂ and Al₂O₃/SiO₂. The fingerprint characteristics of Mn, Fe, Co, Ni and REE and the ratio of U/Th, V/Cr, Sr/Ba, (La/Yb)_N and V/(V + Ni) indicated that the sedimentary provenance was mainly derived from potassium feldspar, followed by muscovite. Sedimentary water bodies showed a gradually decreasing depositional rate trend, water depth gradually shallowing and paleo-salinity and productivity gradually increasing. Moreover, since transient delamination occurred during sedimentary processes, sedimentary water bodies showed obvious neritic characteristics. It was consistent with the results revealed by lithological and geochemical characteristics. Calcareous mudstone and siltstone transitioned into fine sandstone from bottom to top, indicating paleo-water bodies became shallow. The research results provided good reference and guidance for understanding Permian paleo-sedimentary environments and tectonic attributes of the Yong’an area, Fujian Province, southeastern China.     

中低温煤焦油加氢精制催化剂预硫化过程分析

重点分析了预硫化过程中,催化剂进出口温度,以及循环氢中硫化氢浓度的变化。结果显示,催化剂进出口温差控制在1～8℃,硫化速度处于合理范围内,反应器床层未发生任何超温、飞温现象,循环氢中硫化氢浓度的大小,保证了催化剂在不同温度下被充分硫化。     

Evaluation of a coal seam roof water inrush: case study in the Wangjialing coal mine,China

Mine Water and the Environment - The Wangjialing Mine in southern Shanxi Province is seriously threatened by roof water and is infamous for a water inrush disaster that happened there in 2010. A...     

Designing novel sodium bismuth titanate lead-free incipient perovskite for piezoactuator applications

Bismuth-based lead-free incipient piezoceramics have potential in piezoactuators owing to their large strain response. However, a substantial strain hysteresis and poor temperature/frequency stability heavily restrict their practical applications. Herein, we designed a compositional inhomogeneity and constructed quenched random fields to enhance the relaxor dynamics by introducing a classical relaxor material, Ba(Zr_0.2Ti_0.8)O₃, into a nonergodic material, (Na_0.5Bi_0.5)TiO₃–0.15SrTiO₃. Intriguingly, we obtained a large piezoelectric coefficient of 602 pm/V and a narrow hysteresis of 32% at the x = 0.04 (BZT4) composition. The strain properties present a robust frequency (~2%, 1-20 Hz) and temperature stability (~13%, 25-150°C). The excellent actuating properties of BZT4 were due to a field-induced reversible ergodic relaxor-ferroelectric transformation, and the narrow hysteresis can be attributed to quick switching of the dynamic relaxor phase to external stimuli. The origin of the structural transition and salient strain performance was systematically investigated. This study provides a novel route for designing lead-free incipient perovskite with a large strain, narrow hysteresis and high stability for eco-friendly actuators.     

高校学生管理工作面临的问题及对策

社会主义市场经济和高等教育改革的发展,使传统的高校学生管理工作面临严峻的挑战.从分析新形势下学校外部环境、学生主体及高等教育改革的现状出发,指出高校学生管理工作应树立以人为本的管理理念,积极探索适应时代要求的高校学生管理模式,改革和创新高校学生管理工作.     

多层涂层体系界面应力的求解

基于弹性力学平面问题的位移函数解法,运用Fourier积分变换推导了多层涂层体系界面应力及位移分量的一般解,得到一种高效、简便的涂层界面应力计算方法。     

内燃机测试技术的现状与发展

着重论述了国内外内燃机测试技术的发展概况，并对发展我国内燃机测试技术提出了一些建议。     

一种自寻优前馈预控参数整定的复合控制系统实现

针对采用惯量电模拟技术的汽车同步器试验系统研制 ,通过探讨同步器试验的特点和技术要求 ,开发了以自寻优方法实现前馈预控参数整定的复合控制系统。试验结果表明 ,以自寻优方法整定预控参数进行复合控制 ,不仅简单实用 ,而且前馈补偿控制效果良好 ,充分满足了同步器试验系统的技术要求。     

基于遗传算法工具箱的插铣切削力的预测模型

根据插铣核电材料A508-3钢各向最大切削力的正交实验数据,建立插铣过程的切削参数(切削速度、每齿进给量和径向切削宽度)各向最大切削力预测模型。把切削力预测值与实验值的残差平方和为适合度函数,采用谢菲尔大学研究的遗传算法工具箱实现各向最大切削力预测模型的各项参数。结果表明切削力预测模型与实验值吻合较好。本文目的是在特定插铣切削参数条件下预测切削力。