期货的价格不是未来的现货价格

今天的期货价格、就是今天的期货价格，未来的期货价格就是未来的期货价格；今天的现货价格就是今天的现货价格，未来的现货价格就是未来的现货价格。今天的期货价格与未来的现货价格并没有直接的关系。[编者按]     

教师实践自由的张力及其限度

教师实践自由的张力是指教师作为主动的施力者,其实践自由张开程度、趋势的大小.从教育自身的规律看教师实践自由张力应体现在教师的实践是审美的、智慧的、创新的、愉悦的、实用的、主体的、生命的、开放的、个性的、人文的、生态的、责任的.但教师实践自由不是无边界地肆意驰骋,相反,教师实践自由的张力是有限度的、被约束的,这既体现于教育内在机制对它的约束和牵制,也体现于人类社会发展实践的内在逻辑建构.     

毛泽东思想万岁——纪念中国共产党成立四十五周年

今天,在我国无产阶级文化大革命的高潮中,在世界人民革命斗争波澜壮阔的大好形势下,我们来纪念中国共产党成立四十五周年。我们的党,是伟大的、光荣的、正确的党。我们的党,是毛泽东同志亲手缔造和培育的党,是用马克思列宁主义、毛泽东思想式装起来的党,是理论同实际相结合的、和人民群众紧密地联系在一起的、有认真的自我批评精神的无产价级革命党,是经历了革命历史上最激烈、最艰苦、最长期、最复杂的斗争的无产阶级革命党。我们党的四十五年的历史,是毛泽东同志把马克思列宁主义的普遍真理同中国革命和世界革命的具体实践密切结合起来的历史。我们党四十五年来所取得的伟大胜利,是毛泽东思想的伟大胜利。     

离合器与制动器用纳米粉摩擦材料的现状分析

简介了机械压力机离合器与制动器使用的摩擦材料的基本组成、分类及其各自的特点。分析了传统的摩擦材料的不足之处,简介了含有纳米粉摩擦材料的现状,并明确指出使用含有纳米粉的摩擦材料的优势。揭示了纳米粉改善摩擦材料性能的机理,论述了用于摩擦材料的纳米粉的种类、化学成分、制备工艺及制取的设备,并分析了纳米粉的大小、比例,重点对含有纳米粉的摩擦材料的性能改善情况及在国内外的应用现状进行了分析。     

焊接接头的延迟裂纹及其试验方法

延迟裂纹是焊接构件容易发生的潜藏的、危险的缺陷,弄清延迟裂纹产生的机理,发展定量的探测诱发裂纹的因素及其相互关系的试验方法,对防止延迟裂纹的产生,提高焊接构件的可靠性具有重要的意义。     

试制的超声波脉冲穿透法砂轮硬度试验机

用超声波脉冲穿透法测定的动弹性系数与砂轮的组成有密切的关系,砂轮的组成与动弹性系数的关系用松野的公式.大体上是可以说明的。动弹性系数与砂轮的抗折强度有密切的关系,而抗折强度与实际采用的方法测定出的硬度是互相关联着的。动弹性系数与锥头的压入深度也是有关系的。因此,动弹性系数与用普通方法测定出的硬度是容易对应的,用于实     

关于焊接热输入公式的探讨

焊接热输入对焊接接头的力学性能有着相当大的影响。尽管在焊缝力学性能合格的范围内 ,焊接热输入的取值范围比较宽 ,但是对许多焊接构件 ,特别是重要的焊接构件 ,严格控制焊接热输入的输入 ,提高焊接接头的焊接质量是至关重要的。因此 ,研究焊接热输入公式 ,纠正焊接热输入和公式中尚存的个别欠缺 ,消除因焊接热输入公式而引起的误会或计算误差 ,对保证重要焊接构件的焊接质量和促进焊接科研工作的正常开展具有十分重要的意义。1　焊接热输入定义的改进焊接热输入的定义在不同的教科书上表述的方法是不同的 ,但其实质性的内容是相同的。即 …     

生态学对企业管理之启迪

生态学是生物科学在近代产生的一个分支。按照德国科学家海卡尔的定义:“生态学是研究有机体同周围环境之间相互关系的科学”,而企业生态学则是企业学与生态学相互渗透的结果。企业生态学依据生态学的原理,特别是生态系统、生态平衡、食物链、协同进化等原理与机制,研究各种企业现象及其成因,进而掌握企业发展的规律,揭示企业的发展趋势和方向。简言之,就是研究企业与其周围生态环境(包括自然的、社会的、经济的和规范的之间相互作用的规律和机理的一门学科。传统的企业管理理论通过介绍大量的所谓成功或失败的案例来使企业管理者学习各种各样、层出不穷的管理方法,但是,真正对管理者起作用的不是掌握名目繁多的管理理论与方法,而是如何在合适的时间,应用合适的管理理论,以合适的组织模式管理企业,使企业能在最短的时间生产出满足市场需要的各类产品。传统的企业管理理论的简单应用已无法适应企业竞争发展的需要,企业对其复杂多变的生态环境的反应速度和企业本身组织结构的弹性成为企业能否持续生存和发展的关键所在。企业是一个开放的系统,它必须不停地与外部环境进行物质、能量、信息的交换,才能维持自身的生存与发展。由于自然资源的有限性,企业必须为争夺资源与其他各种企业进行激...     

试论传统本土教学论的建构方法北大核心CSSCI

中国传统本土教学论的发展是以儒学教学思想为主线的流变过程,在这种流变过程中逐渐沉淀出自身独特的构建方法——实践体验法,一种与西方偏重理性十分不同的方法:其一,坚持以教学实践的异质逻辑为中心以回答"教学如何更好地进行?"的实践问题,而非以同质的理论逻辑为中心以回答"教学是什么"的理论问题;其二,坚持以日常教学生活经验总结方式,而非以实验验证方式来建构自身,因而表现为整体探究的而非变量控制的,体验反思的而非假设检验的,描述的而非定量分析的,主客交融的而非主客分离的;其三,坚持以切实体验而非纯粹理性思辨的方式构建自身,因而表现为直觉体认的而非逻辑分析的,意象的而非纯粹抽象的;其四,坚持以实用理性而非空泛的先验理性构建自身,因而表现为入世的而非出世的,历史延续的而非历史断裂的。     

公民的养成:在政治与教育之间

公民既是一种身份,也是一种资格,既有享受法定权利的正当,也需要习得与作为合格公民相匹配的能力。公民的养成既需要政治的教化也需要学校的教育。政治的教化赋予公民身份以政治合法性,学校的教育则奠定公民身份的道德底蕴。从"关于公民的教育"到"为了公民的教育",学校公民教育与政治教化既存在一致性又隐藏着不可避免的冲突。在组织与制度设计上,学校的发明原本是为了知识的生产与传播而非意识形态的灌输;但在民族国家的框架下,学校教育又是政治教化不可分割的组成部分。一方面公民教育指向人的政治社会化,天然具有政治和意识形态性,另一方面学校空间过度的政治化又会压抑人的天性,不利于人性的培养。基于此,公民的养成需要保持政治与教育之间的平衡,学校的公民教育既要满足人的政治社会化的需要,又不能有违"通过教育让人成为人"的初心。     

Effect of pulse time on surface characteristics and corrosion resistance during pulse electrochemical polishing

Pulse electrochemical polishing (PECP) was used to improve the mechanical properties,such as surface roughness and corrosion resistance,of conductive metallic materials.PECP can provide a smooth,bright,reflective,and deburred surface that exhibits superior corrosion resistance.In this work,stainless steel was used as the anode,and copper was used as the cathode due to their low electrical resistances.The surface roughness of the PECP sample was measured by atomic force microscopy (AFM).A scanning electron microscope (SEM) was used to observe surface characteristics,and an Auger electron spectroscope (AES) was used to analyze the metallurgical composition and thickness of the passive film.The aim of this research was to compare the corrosion resistance rates of the unprocessed and PECP-processed stainless steel.     

不同构件的磁记忆检测及分析方法研究

利用EMS－2000金属磁记忆诊断仪对三个不同构件进行检测试验，并使用信号处理软件对检测结果进行了不同方式的分析，结果表明，磁记忆检测技术是检测与应力有关缺陷和应力集中线的有效方法。     

基于DSP-MCU实现焊接电源系统数字化控制的设计

基于DSP-MCU实现焊接电源系统数字化控制的设计采用TMS320F240数字信号处理器和80C196KC单片机，设计成实现多功能IGBT逆变焊接电源双机控制系统。其中，TMS320F240主要用于焊接参数的采样、控制算法的运算，80C196KC用于完成人机接口的功能，包括键盘和显示，与上位机的通信等。设计中人机界面采用液晶显示。系统设计的关键是双机之间的通信技术，为了确保通信的可靠及快速性采用双口RAM(IDT7005)来完成。数字PWM控制单元采用复杂可编程逻辑器件(CPLD)完成，整个系统中所有逻辑控制也由此芯片来完成，设计完成的DSP-MCU双机控制系统实现了焊机的多功能全数字化控制。     

Transformations in machining. Part 1. enhancement of wavelet transformation neural network (WT-NN) combination with a preprocessor

Properly selected transformation methods obtain the most significant characteristics of metal cutting data efficiently and simplify the classification. Wavelet Transformation (WT) and Neural Networks (NN) combination was used to classify the experimental cutting force data of milling operations previously. Preprocessing (PreP) of the approximation coefficients of the WT is proposed just before the classification by using the Adaptive Resonance Theory (ART2) type NNs. Genetic Algorithm (GA) was used to estimate the weights of each coefficient of the PreP. The WT-PreP-NN (ART2) combination worked at lower vigilances by creating only a few meaningful categories without any errors. The WT-NN (ART2) combination could obtain the same error rate only if very high vigilances are used and many categories are allowed.     

The effect of current mode and discharge type on the corrosion resistance of plasma electrolytic oxidation (PEO) coated magnesium alloy AJ62

Magnesium alloys are increasingly being used as lightweight materials in the automotive, defense, electronics, biomaterial and aerospace industries. However, their inherently poor corrosion and wear resistance have, so far, limited their application. Plasma electrolytic oxidation (PEO) in an environmentally friendly aluminates electrolyte has been used to produce oxide coatings with thicknesses of ~ 80 μm on an AJ62 magnesium alloy. Optical emission spectroscopy (OES) in the visible and near ultraviolet (NUV) band (285 nm–800 nm) was employed to characterize the PEO plasma. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to characterize the coated materials, and potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) in a 3.5% NaCl solution were used to determine the corrosion behavior. It was found that the plasma discharge behavior significantly influenced the microstructure and the morphology of the oxide coatings and, hence the corrosion resistance. The corrosion resistance of the coated alloy was increased by changing the current mode from unipolar to bipolar, where the strong plasma discharges had been reduced or eliminated.     

基于VMD和流形学习的滚动轴承故障诊断研究

针对轴承早期故障信号非线性、非平稳和故障特征难以提取的问题,提出一种变分模态分解(VMD)与流形学习相结合的特征提取方法。该方法应用VMD将信号分解成包含不同故障信息的固有模态分量,然后从中提取特征并构建高维的混合域特征集。最后,应用流形学习等度规映射算法将高维的特征集约简为故障区分度更好的低维混合域特征集,并利用支持向量机实现故障分类识别。滚动轴承实验结果表明该方法能准确清晰地提取故障特征信息,与传统方法相比诊断准确率更高。     

Surface morphology of copper deposits by using azine derivatives on an ecofriendly electroless bath

This article reports the effect of azine stabilizers such as pyridine, 2,2'-bipyridine and 1,10-phenanthroline during electroless deposition of copper. In this work, the biodegradable copper methanesulphonate was used instead of the traditionally used copper sulphate and the environmentally safe polyhydroxylic compound xylitol was used as the complexing agent. Commercial para-formaldehyde was used as the reducing agent and potassium hydroxide (KOH) was used to optimize the bath in alkaline medium at pH 13.25. Surface morphologies of the electroless coated copper (Cu) substrates were investigated by atomic force microscopic (AFM) analysis. Crystallite size and specific surface area of copper thin film were observed by x-ray diffraction (XRD). Electrochemical characteristics were studied by cyclic voltammetry (CV) and Tafel polarization. The value of charge transfer resistance and double layer capacitance were determined by impedance techniques. In this xylitol bath, 2,2'-bipyridine was found to act as an enhancer but the results are not very different from the plain xylitol bath. Pyridine acted as a strong inhibitor and 1,10-phenanthroline was a good accelerator. All stabilizers provide high stability to the bath at 28 ± 2°C with 1 ppm addition.     

基于FastICA去噪和改进HHT的转子不平衡故障特征提取方法研究

针对转子不平衡振动信号非平稳性并伴随较强环境噪声的特点，提出一种基于快速独立分量分析（FastICA）和改进希尔伯特-黄变换相结合的故障特征提取方法。该方法采用FastICA法去除环境噪声等因素对于故障特征提取精度的影响，再利用自适应白噪声总体平均模态分解方法将故障信号分解为一系列固有模态函数（IMF），并采用基于相似性评估的虚假IMF选择算法将与故障信息无关的虚假IMF分量剔除，从而保证故障信息提取的准确性和有效性。通过仿真分析证明了所提方法的有效性，并且实际试验表明：该方法可有效提取转子不平衡信号的故障特征，为该类故障的诊断提供了一种切实可行的方法。     

Improved corrosion behavior of nanocrystalline zinc produced by pulse-current electrodeposition

Pulse electrodeposition was used to produce nanocrystalline (nc) zinc from zinc chloride electrolyte with polyacrylamide and thiourea as additives. Field emission scanning electron microscopy (FESEM) was used to study the grain size and surface morphology of the deposits and X-ray diffraction was used to examine their preferred orientation. Corrosion behavior of the electrodeposited nc zinc in comparison with electrogalvanized (EG) steel in de-aerated 0.5 N NaOH solution was studied using potentiodynamic polarization and impedance measurements. A scanning electron microscope (SEM) was used to characterize the surface morphology of the EG steel before corrosion testing. Surface morphologies of nc zinc deposits and EG steel were also studied after potentiondynamic polarization by SEM. Nanocrystalline zinc (56 nm) with random orientation was produced. The estimated corrosion rate of nc zinc was found to be about 60% lower than that of EG steel, 90 and 229 μA/cm², respectively. The surface morphology of corroded nc zinc was characterized by discrete etch pits, however, uniform corrosion was obtained after potentiodynamic polarization of EG steel. The passive film formed on the nc zinc surface seems to be a dominating factor for the corrosion behavior observed.     

Corrosion study of the X52 steel immersed in seawater with a corrosion inhibitor using a rotating cylinder electrode

A corrosion study of API X52 steel was carried out in natural seawater with several concentrations of a corrosion inhibitor (10, 100 and 200 ppm) using a rotating cylinder electrode (RCE) to control the hydrodynamic conditions at environment temperature, atmospheric pressure and 24 h of the exposition time. The rotation speed used was 1000 rpm (turbulent flow). The electrochemical techniques used in the corrosion studies were: linear polarisation resistance (LPR), electrochemical impedance spectroscopy (EIS) and polarisation curves (PCs). The superficial analysis was made using a scanning electron microscope (SEM). The results show a good correlation between electrochemical techniques used. In addition, under turbulent flow, the test solution with 10 ppm had the smallest corrosion rate (CR). It is important to mention that the morphology of the corrosion in all experiments was localised corrosion.