古盐度对陆相页岩发育的控制作用:以东营凹陷古近系沙三下页岩为例

陆相优质烃源岩发育大多与湖泊咸化相关,但湖泊咸化对页岩发育的影响仍不清晰。以东营凹陷古近系页岩重点取心井樊42井为例,通过岩石薄片观察、XRD、岩石热解测试、XRF二维元素扫描、微量元素测试等分析,结合有机地球化学测试数据、微量元素含量的垂向变化等,分析不同盐度演化阶段页岩成分、纹层结构、有机质丰度的变化。结果表明,研究区目的层段页岩可划分为5种岩相类型。目的层段环境演化可以划分为5个阶段,受控于气候、陆源输入等因素。古气候在沙三下亚段沉积时期呈现暖湿—相对湿冷—暖湿—相对干冷—相对暖湿的变化特征。陆源输入量呈多期旋回变化。不同类型岩石的沉积环境特征各异,高盐度的湖泊水体营养盐浓度高,具有较高的初级生产力,水体分层强烈,水体循环较弱。氧/盐度跃层位置相对较高,富氧带水深较浅,使得有机质更快脱离氧化环境沉降进入还原性水体,有利于有机质的保存。碳酸盐矿物含量高,且呈纹层状发育于滞水层中。

基于光谱变换的高光谱指数土壤盐分反演模型优选

该文探索基于光谱变换建立光谱指数,进而建立土壤盐分反演模型的可行性。运用倒数、导数、对数等15种光谱变换对土壤含盐量进行反演,并利用原始光谱的波段反射率构造光谱指数对土壤盐分进行建模。在15种高光谱变换中,一阶微分R'和一阶对倒数(log1/R')变换下土壤盐分估算模型的精度较高。但总体而言,基于单一光谱变换和光谱指数的模型模拟精度均较低。采用光谱变换建立光谱指数,并进一步建立土壤盐分反演模型,结果表明,基于(log1/R')光谱变换构建归一化植被指数,然后建立的土壤盐分精度最高,经验证,其R2为0.89,均方根误差为3.34 g/kg,高于单一方法构建的模型,可为半干旱地区土壤盐分反演提供参考。

新型文丘里空化器及其空化特性的数值模拟

近年来水力空化技术在降解废水领域快速发展,为提高空化降解效率,本文提出一种基于窄缝型文丘里管的新型空化发生器,其主要特征是在喉部固定了分流部件,以达到增加剪切面积、提升空化汽泡产率的目的。为探究新型空化器的空化流场特性,本文基于稳态RANS方法在均匀多相流模型和Schnerr-Sauer空化模型条件下对其进行数值模拟。围绕入口压力、扩张角度和喉部几何结构的特征尺寸对空化体积的影响规律展开对比分析。定义喉部特征长度L与喉道总长L_(th)的比值γ作为控制参数。数值模拟结果显示:空化数小于0.45时,γ值对空化体积影响较为显著,空化程度随入口压力增大而增强,随扩张角度增大而减弱;当入口压力为0.6 MPa(空化数C_(v)=0.22)、扩张角度为10°、γ为0.67时,空化体积达到最大值。

亚麻木酚素对多囊卵巢综合征大鼠髓源抑制细胞及炎症因子的影响

目的探讨亚麻木酚素(SDG)对多囊卵巢综合征(PCOS)大鼠髓源抑制性细胞(MDSCs)及血浆炎症因子的调节作用。方法32只6周龄雌性SD大鼠随机分为4组。采用来曲唑造模法建立PCOS大鼠模型,每日监测动情周期变化。造模成功后阴性对照组和模型组灌胃生理盐水,SDG对照组和SDG干预模型组灌胃等量SDG溶液。干预8周后,采用流式细胞术检测大鼠外周血、脾脏、肝脏和骨髓中MDSCs比例;ELISA检测血浆中肿瘤坏死因子(TNF-α)、白细胞介素(IL-6)、IL-10的水平;Pearson统计分析MDSCs与炎症因子的相关性。结果与模型组相比,SDG干预模型组脾脏、肝脏和骨髓中MDSCs的比例显著增加,外周血MDSCs比例有增加趋势但无统计学意义;血浆中TNF-α水平显著降低(P<0.01),IL-10显著升高(P<0.05),IL-6水平有所降低,但差异无统计学意义。相关性分析发现,MDSCs与TNF-α、IL-6呈负相关,与IL-10呈正相关。结论SDG通过代偿性增加PCOS大鼠脾脏、肝脏和骨髓的MDSCs以及抑制炎症改善PCOS。

Theoretical analysis on elastic buckling of nanobeams based on stress-driven nonlocal integral model

Several studies indicate that Eringen's nonlocal model may lead to some inconsistencies for both Euler-Bernoulli and Timoshenko beams, such as cantilever beams subjected to an end point force and fixed-fixed beams subjected a uniform distributed load. In this paper, the elastic buckling behavior of nanobeams, including both EulerBernoulli and Timoshenko beams, is investigated on the basis of a stress-driven nonlocal integral model. The constitutive equations are the Fredholm-type integral equations of the first kind, which can be transformed to the Volterra integral equations of the first kind. With the application of the Laplace transformation, the general solutions of the deflections and bending moments for the Euler-Bernoulli and Timoshenko beams as well as the rotation and shear force for the Timoshenko beams are obtained explicitly with several unknown constants. Considering the boundary conditions and extra constitutive constraints, the characteristic equations are obtained explicitly for the Euler-Bernoulli and Timoshenko beams under different boundary conditions, from which one can determine the critical buckling loads of nanobeams. The effects of the nonlocal parameters and buckling order on the buckling loads of nanobeams are studied numerically, and a consistent toughening effect is obtained.

Two-phase nonlocal integral models with a bi-Helmholtz averaging kernel for nanorods

In this work,the static tensile and free vibration of nanorods are studied via both the strain-driven(Strain D)and stress-driven(Stress D)two-phase nonlocal models with a bi-Helmholtz averaging kernel.Merely adjusting the limits of integration,the integral constitutive equation of the Fredholm type is converted to that of the Volterra type and then solved directly via the Laplace transform technique.The unknown constants can be uniquely determined through the standard boundary conditions and two constrained conditions accompanying the Laplace transform process.In the numerical examples,the bi-Helmholtz kernel-based Strain D(or Stress D)two-phase model shows consistently softening(or stiffening)effects on both the tension and the free vibration of nanorods with different boundary edges.The effects of the two nonlocal parameters of the bi-Helmholtz kernel-based two-phase nonlocal models are studied and compared with those of the Helmholtz kernel-based models.

Dynamic stability analysis of porous functionally graded beams under hygro-thermal loading using nonlocal strain gradient integral model

We present a study on the dynamic stability of porous functionally graded(PFG)beams under hygro-thermal loading.The variations of the properties of the beams across the beam thicknesses are described by the power-law model.Unlike most studies on this topic,we consider both the bending deformation of the beams and the hygro-thermal load as size-dependent,simultaneously,by adopting the equivalent differential forms of the well-posed nonlocal strain gradient integral theory(NSGIT)which are strictly equipped with a set of constitutive boundary conditions(CBCs),and through which both the stiffness-hardening and stiffness-softening effects of the structures can be observed with the length-scale parameters changed.All the variables presented in the differential problem formulation are discretized.The numerical solution of the dynamic instability region(DIR)of various bounded beams is then developed via the generalized differential quadrature method(GDQM).After verifying the present formulation and results,we examine the effects of different parameters such as the nonlocal/gradient length-scale parameters,the static force factor,the functionally graded(FG)parameter,and the porosity parameter on the DIR.Furthermore,the influence of considering the size-dependent hygro-thermal load is also presented.

Torsional static and vibration analysis of functionally graded nanotube with bi-Helmholtz kernel based stress-driven nonlocal integral model

A torsional static and free vibration analysis of the functionally graded nanotube(FGNT)composed of two materials varying continuously according to the power-law along the radial direction is performed using the bi-Helmholtz kernel based stress-driven nonlocal integral model.The differential governing equation and boundary conditions are deduced on the basis of Hamilton’s principle,and the constitutive relationship is expressed as an integral equation with the bi-Helmholtz kernel.Several nominal variables are introduced to simplify the differential governing equation,integral constitutive equation,and boundary conditions.Rather than transforming the constitutive equation from integral to differential forms,the Laplace transformation is used directly to solve the integro-differential equations.The explicit expression for nominal torsional rotation and torque contains four unknown constants,which can be determined with the help of two boundary conditions and two extra constraints from the integral constitutive relation.A few benchmarked examples are solved to illustrate the nonlocal influence on the static torsion of a clamped-clamped(CC)FGNT under torsional constraints and a clamped-free(CF)FGNT under concentrated and uniformly distributed torques as well as the torsional free vibration of an FGNT under different boundary conditions.

Osteocyte Remodeling of the Perilacunar and Pericanalicular Matrix

With additional functions of osteocytes being identified, the concept that osteocytes are just ＂static lacunar-dwelling cells＂ is no longer accepted. We reviewed most of the relevant literature on osteocyte＇s function in the direct remodeling of the perilucunar matrix, discussing the advantages and disadvantages. Special attention was paid to how the negative researchers argue about the ＂osteocytic osteolysis＂ principle, and how the positive side addressed the arguments. We also discussed the newly found data of osteocytic remodeling function from our group. With more biotechnology in hand, there is increased excitement in the prospect of now being able to answer the two important questions： do osteocytes have the capability to remove mineral from the perilacunar matrix and if so what are the molecular and cellular mechanisms？ do osteocytes have the capability to deposit new mineral on the perilacunar matrix and if so what are the cellular and molecular mechanisms？

On well-posedness of two-phase nonlocal integral models for higher-order refined shear deformation beams

Due to the conflict between equilibrium and constitutive requirements,Eringen’s strain-driven nonlocal integral model is not applicable to nanostructures of engineering interest.As an alternative,the stress-driven model has been recently developed.In this paper,for higher-order shear deformation beams,the ill-posed issue(i.e.,excessive mandatory boundary conditions(BCs)cannot be met simultaneously)exists not only in strain-driven nonlocal models but also in stress-driven ones.The well-posedness of both the strain-and stress-driven two-phase nonlocal(TPN-Strain D and TPN-Stress D)models is pertinently evidenced by formulating the static bending of curved beams made of functionally graded(FG)materials.The two-phase nonlocal integral constitutive relation is equivalent to a differential law equipped with two restriction conditions.By using the generalized differential quadrature method(GDQM),the coupling governing equations are solved numerically.The results show that the two-phase models can predict consistent scale-effects under different supported and loading conditions.

协同育人模式在高校应用型人才培养改革应用分析

在知识经济的时代背景下,企业和社会对综合型人才的需求量越来越大,单一型技术人才已经不能满足企业生产和发展需要,对于学生的思想素质、道德水平、实践能力、应用能力等有了更高的要求。各所高校面临在应用型人才培养的同时教书育人的方向需要转型的问题,从这一层面来讲,协同育人模式在高校教育机制中具有重要的发展地位。基于此,展开以下论述,从协同育人的相关概述入手,探析其在高校人才培养改革背景下的具体应用策略,希望能为广大高校老师带来实践参考和理论思考。

Nonlocal stress gradient formulation for damping vibration analysis of viscoelastic microbeam in thermal environment

An integral nonlocal stress gradient viscoelastic model is proposed on the basis of the integral nonlocal stress gradient model and the standard viscoelastic model,and is utilized to investigate the free damping vibration analysis of the viscoelastic BernoulliEuler microbeams in thermal environment.Hamilton's principle is used to derive the differential governing equations and corresponding boundary conditions.The integral relations between the strain and the nonlocal stress are converted into a differential form with constitutive constraints.The size-dependent axial thermal stress due to the variation of the environmental temperature is derived explicitly.The Laplace transformation is utilized to obtain the explicit expression for the bending deflection and moment.Considering the boundary conditions and constitutive constraints,one can get a nonlinear equation with complex coefficients,from which the complex characteristic frequency can be determined.A two-step numerical method is proposed to solve the elastic vibration frequency and the damping ratio.The effects of length scale parameters,viscous coefficient,thermal stress,vibration order on the vibration frequencies,and critical viscous coefficient are investigated numerically for the viscoelastic Bernoulli-Euler microbeams under different boundary conditions.

Unified two-phase nonlocal formulation for vibration of functionally graded beams resting on nonlocal viscoelastic Winkler-Pasternak foundation

A nonlocal study of the vibration responses of functionally graded(FG)beams supported by a viscoelastic Winkler-Pasternak foundation is presented.The damping responses of both the Winkler and Pasternak layers of the foundation are considered in the formulation,which were not considered in most literature on this subject,and the bending deformation of the beams and the elastic and damping responses of the foundation as nonlocal by uniting the equivalently differential formulation of well-posed strain-driven(ε-D)and stress-driven(σ-D)two-phase local/nonlocal integral models with constitutive constraints are comprehensively considered,which can address both the stiffness softening and toughing effects due to scale reduction.The generalized differential quadrature method(GDQM)is used to solve the complex eigenvalue problem.After verifying the solution procedure,a series of benchmark results for the vibration frequency of different bounded FG beams supported by the foundation are obtained.Subsequently,the effects of the nonlocality of the foundation on the undamped/damping vibration frequency of the beams are examined.

Well-posedness of two-phase local/nonlocal integral polar models for consistent axisymmetric bending of circular microplates

Previous studies have shown that Eringen’s differential nonlocal model would lead to the ill-posed mathematical formulation for axisymmetric bending of circular microplates.Based on the nonlocal integral models along the radial and circumferential directions,we propose nonlocal integral polar models in this work.The proposed strainand stress-driven two-phase nonlocal integral polar models are applied to model the axisymmetric bending of circular microplates.The governing differential equations and boundary conditions(BCs)as well as constitutive constraints are deduced.It is found that the purely strain-driven nonlocal integral polar model turns to a traditional nonlocal differential polar model if the constitutive constraints are neglected.Meanwhile,the purely strain-and stress-driven nonlocal integral polar models are ill-posed,because the total number of the differential orders of the governing equations is less than that of the BCs plus constitutive constraints.Several nominal variables are introduced to simplify the mathematical expression,and the general differential quadrature method(GDQM)is applied to obtain the numerical solutions.The results from the current models(CMs)are compared with the data in the literature.It is clearly established that the consistent softening and toughening effects can be obtained for the strain-and stress-driven local/nonlocal integral polar models,respectively.The proposed two-phase local/nonlocal integral polar models(TPNIPMs)may provide an efficient method to design and optimize the plate-like structures for microelectro-mechanical systems.

On the consistency of two-phase local/nonlocal piezoelectric integral model

In this paper,we propose general strain-and stress-driven two-phase local/nonlocal piezoelectric integral models,which can distinguish the difference of nonlocal effects on the elastic and piezoelectric behaviors of nanostructures.The nonlocal piezoelectric model is transformed from integral to an equivalent differential form with four constitutive boundary conditions due to the difficulty in solving intergro-differential equations directly.The nonlocal piezoelectric integral models are used to model the static bending of the Euler-Bernoulli piezoelectric beam on the assumption that the nonlocal elastic and piezoelectric parameters are coincident with each other.The governing differential equations as well as constitutive and standard boundary conditions are deduced.It is found that purely strain-and stress-driven nonlocal piezoelectric integral models are ill-posed,because the total number of differential orders for governing equations is less than that of boundary conditions.Meanwhile,the traditional nonlocal piezoelectric differential model would lead to inconsistent bending response for Euler-Bernoulli piezoelectric beam under different boundary and loading conditions.Several nominal variables are introduced to normalize the governing equations and boundary conditions,and the general differential quadrature method(GDQM)is used to obtain the numerical solutions.The results from current models are validated against results in the literature.It is clearly established that a consistent softening and toughening effects can be obtained for static bending of the Euler-Bernoulli beam based on the general strain-and stress-driven local/nonlocal piezoelectric integral models,respectively.

巴林右旗林业机耕林场森林生态服务功能价值对比分析

文章依据林业机耕林场2002年、2016年森林资源二类调查数据,对林场森林植被碳储量、涵养水源、固土保肥、固碳释氧、净化大气环境等生态服务价值进行对比分析。结果表明,2016年与2002年相比,林场森林植被碳储量增加15425.08 t,森林每年净化大气环境价值减少210.19万元,年固土保肥价值增加316.02万元,年固碳释氧价值增加67.46万元,水源涵养价值增加1858.29万元。随着森林总量的不断提高,总体上森林每年提供的生态服务功能价值也不断增加。

Isogeometric Analysis for the Arbitrary AFG Microbeam with Two-Phase Nonlocal Stress-Driven Model

Scale effects play critical roles in the mechanical responses of microstructures.An isogeometric analysis was developed here to investigate the mechanical responses of an axially functionally graded microbeam.The Euler–Bernoulli beam model was utilized,and size effects in the structure were modeled with a stress-driven two-phase local/nonlocal integral constitution.The governing equation of microstructures was given in an equivalent differential form with two additional constitutive boundary conditions.The framework was verified and utilized to analyze the microbeam’s static and dynamic mechanical responses.The present work showed great potential for modeling various types of functionally graded microstructures.

过热度和冷却速度对Al-5Fe合金微观组织的影响

通过将Al-5Fe、Al-5Fe-0.9Ce、Al-5Fe-5Ce等3种合金熔体加热到800、900、1 200℃,并进行炉冷、模冷、液淬3种不同的冷却,研究不同冷却速度下富Fe相微观形貌的变化。结果表明,过热度为127℃时,富Fe相尺寸细化明显。过热度为127℃时,液淬时的富Fe相最为细小。

Finite Element Analysis of the Microstructure–Strength Relationships of Metal Matrix Composites

The influence of the shape and spatial distribution of reinforced particles on strength and damage of metal matrix composite （MMC） is investigated through finite element method under uniaxial tensile, simple shear, biaxial tensile, as well as combined tensile/shear loadings. The particle shapes change randomly from circular to regular n-sided polygon （3 ≤ n ≤ 10）; the particle alignments are determined through a sequentially random number stream and the particle locations are defined through the random sequential adsorption algorithm. The ductile failure in metal matrix and brittle failure in particles are described through damage models based on the stress triaxial indicator and maximum principal stress criterion, respectively, while the debonding behavior of interface between particles and matrix is simulated through cohesive elements. The simulation results show that, under different loadings, interface debonding is the dominated failure mechanism in MMCs and plastic deformation and ductile failure of matrix also play very important roles on the failure of MMCs.