重读特罗高等教育系统崩溃预警

高等教育增长与扩张导致诸多问题,在高等教育系统与文化整体中形成一个问题簇。这个问题簇影响高等教育系统核心要素并使它们成为问题要素,影响高等教育系统整体并使它成为问题系统,随之导致高等教育系统质变;系统质变形成精英、大众与普进三种性质不同的高等教育系统。三种系统之中,精英是规范系统与高等教育系统确立系统,大众是非规范系统与高等教育系统分化系统,普进是反规范系统与高等教育系统粉碎系统。大众与普进两个系统衍生后,高等教育系统可能由两种或三种系统构成,作为混合系统存在于教育系统与文化整体中;也可能由一种系统构成,作为纯一系统存在于教育系统与文体整体中。高等教育系统整体,随着非精英系统所占比例增加,逐渐走向系统分化,走向系统粉碎;高等教育系统为纯精英系统时,系统因确立而稳定;为纯大众系统时,系统因分化而震荡;为纯普进系统时,系统因粉碎而崩溃。高等教育系统崩溃,不仅导致高等教育社会心理与社会身份崩溃,而且危害文化其它系统及文化整体。这是特罗在《从精英向大众高等教育转变中的问题》中提出的高等教育系统问题预警,可以称为特罗高等教育系统崩溃预警!这一预警对高等教育健全发展有深远意义。     

铸造模具的模块结构图及总体框架

讨论了参数化设计系统的基本原理,构建了铸造模具工艺装备系统的总体框架和模样系统、浇注系统、冒口系统、工装系统各个分系统的结构组成。     

大型履带起重机起升机构闭式液压集中式补油系统研究

以4000 t级大型履带起重机主起升机构闭式液压系统为研究对象,建立基于MATLAB的系统发热数学模型。分析不同系统工作压力以及输入转速下,集中式补油系统的参数设置。确定最大系统工作压力下,集中式补油系统的排量与冲洗阀的匹配关系。比较定量集中式补油系统与变量集中式补油系统对系统低压腔压力以及系统油温的影响,为后续集中式补油系统的参数设置与选型提供理论依据。     

FMS信息流系统(二)

2.FMS信息流系统的组成及结构2.1 几个概念由一般系统论可知:系统的元素和系统的结构就完全决定了系统的功能,而系统的功能从根本上就决定了系统所能完成的任务(系统具有的各种功能的不同组合可以完成不同的特定任务)。这个观点对于FMS信息流系统也是适用的。FMS信息流系统中的元素就是硬件和软件。关于信息流系统的结构在见到的文献上有许多含混不清的说法。为分辨差异和表达清楚特定义以下四个概念:     

企业安全预警指数系统的研究

本文以企业安全生产预警指数系统为主要内容,介绍了预警指数系统的一般概念,安全预警指数系统问题的提出,企业安全生产管理方面主要表现的问题,企业预警指数系统的建立,企业安全生产预警指数系统的设计,企业安全生产预警指数趋势图的设计,预警指数系统建立的方法,预警指数系统的组织领导,预警指数系统的数据收集,数据分析,数据在表中的填写方法,预警指数系统的系数修正,安全生产预警指数系统工作的能力培训等相关内容。     

低合金钢土壤腐蚀性能灰色模型研究

<正> 1.前言将包含已知信息的系统称为白色系统,包含未知信息的系统称为黑色系统,而灰色系统是指系统中既包含已知信息,又含有未知的或不确切的信息的系统,这种系统作用机制不明确,系统状态难以描述。含有气、液、固三相的土壤体系非常复杂,有水份、O_2、阴阳离子、微生物、气象因     

火炮液压随动系统性能参数测控系统设计

介绍了液压随动系统在常规兵器中的应用以及火炮液压随动系统性能参数测控系统的组成和工作原理，分析了表征液压火炮随动系统性能的各参数特性，讨论了测控系统的软件设计、使用要求和硬件系统环境适应能力的设计。     

液压调速系统速度平稳性的模糊控制

本文在分析常见的调速阀节流调速系统速度平稳性的基础上，得出该系统中溢流阀对突变外负载的影响加剧了系统的速度波动，提出一种能改善系统动态速度平稳性的模糊控制液压比例溢流阀调速系统。仿真结果表明：模糊控制比例溢流阀调速系统能有效地提高系统的速度平稳性。     

国家大学科技园创新体系建构

国家大学科技园包括作为前提和条件的创新导引系统，作为动力的创新激励系统和作为背景的创新环境支撑系统、作为创新源头的人才支撑系统。创新人才向创业人才的升华，导引系统向激励系统的延展，使国家大学科技园充满活力。     

航空航天领域中超声波C扫描检测系统的发展与应用

对超声波C扫描检测系统的发展历史和发展方向作了简要的叙述和归纳,对国内外的超声波C扫描检测系统产品进行了简单介绍,对超声波C扫描检测中常见的平面扫查系统、回转体扫查系统、大型空间曲面构件扫查系统、管材与棒材旋转行进的扫查系统和便携式扫查系统等五类系统的特点和应用范围进行了总结,为业界选择合适的检测系统提供帮助。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

THERMODYNAMICS STUDY ON THE DECOMPOSITION OF CHROMITE WITH KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

INFLUENCE OF HEAT TREATMENT ON DAMPING BEHAVIOUR OF THE MAGNESIUM WROUGHT ALLOY AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.