Study on titania nanotube arrays prepared by titanium anodization in NH<Subscript>4</Subscript>F/H<Subscript>2</Subscript>SO<Subscript>4</Subscript> solution

In this paper, the formation of titania nanotube arrays was investigated in NH₄F/H₂SO₄ electrolyte. Under optimized electrolyte conditions, the titania nanotube arrays with an inner diameter of about 120 nm and a length of about 300 nm was obtained. During the formation process, the variety of current was observed. The current–time curve implied that the evolvement process of titania nanotube arrays include three stages. The stability of titania nanotube arrays at elevated temperatures was studied. The as-prepared titania nanotube arrays is amorphous, crystallized in anatase and rutile as the rising of the temperature. The samples were characterized by ESEM and XRD.     

A NEW INTEGRAL INEQUALITY APPROACH TO DELAY‐DEPENDENT ROBUST H∞ CONTROL

A design method for the robust H_∞ control of an uncertain linear system with a time‐varying state delay is proposed. First, an integral inequality that we recently obtained is employed to establish a new delay‐dependent bounded real lemma for a system with a time‐varying delay. The lemma uses neither a model transformation nor a bounding technique for cross terms. Then, the lemma is used in combination with a matrix decomposition method to derive delay‐dependent conditions for the existence of robust H_∞ control based on linear matrix inequalities. Finally, some numerical examples are given to demonstrate the validity of the method.     

一类大气层内超高速飞行器鲁棒控制器设计研究

针对一类带有稳定性导数的大气层内超高速飞行器,根据所给出考虑机体弹性弯曲的线性系统模型,计算其特征值与特征向量,确定其各个模态,进而分析其对应模态之间的耦合效应;同时考察控制输入矩阵,分析控制输入对状态量的影响;针对建模过程中的参数不确定性,基于线性矩阵不等式理论,设计渐进稳定控制器,给出工程化设计过程,并分析控制器控制能量的分配性质.仿真结果表明,所设计的控制器能够有效的镇定参数不确定摄动系统.     

Athermal design for the potassium titanyl phosphate electro-optical modulator

An athermal design for the KTP electro-optical modulator is presented. By using the wave coupling theory of linear electro-optic effect and taking account of thermal expansion, the more accurate athermal static phase retardation (ASPR) directions in potassium titanyl phosphate (KTP) are found, and the optimized design for a transverse amplitude modulator at ASPR orientation is obtained. The numerical results show that the modulator with an athermal Soleil-Babinet compensator is of excellent thermal stability, and the acceptable error of the ASPR direction is less than 0.1 degrees.     

Vacuum Tribological Properties of Titanium Enhanced via Ultrasonic Surface Rolling Processing Pretreatment and Plasma Nitriding

For the purpose of enhancing the vacuum friction-reducing and antiwear performance of UNS R50400 Ti, ultrasonic surface rolling processing (USRP) has been introduced as pretreatment of plasma nitriding (PN). Various nitriding temperatures from 650 to 950°C have been adopted to investigate the effects of USRP pretreatment on plasma nitriding of Ti. The results of experiments show that the friction-reducing and antiwear performance are enhanced by USRP pretreatment when the PN temperature is below 750°C, resulting from the formation of thicker and harder nitriding layer with a reasonable gradient structure. Nevertheless, USRP pretreatment results in a rough surface and a large-sized columnar crystal gradient structure when the PN temperature is above 750°C, leading to poor vacuum tribological performance. In aggregate, USRP pretreatment is an effective pretreatment to decrease the optimized plasma-nitriding temperature from 850 to 750°C.     

加拿大矿业融资的主要方式与金融工具

本文结合加拿大矿业类上市公司的特点,总结和归纳了矿业类上市公司可使用的主要融资方式和金融工具。重点从上市公司层面和项目层面两个方面归纳总结了可选择的融资方式和金融工具,并对每种融资方式和金融工具使用的条件和环境进行了简单介绍。证券市场既为勘查类企业提供符合行业特点的融资方式、手段和工具,同时也拓展了此类公司控制风险和建立信用的渠道。本文中提及的加拿大矿业类上市公司所使用的融资方式和工具相对成熟,是在我国未来多层次资本市场建设中可以学习和借鉴的。     

某石煤钒矿的选矿与提钒试验研究

对某石煤矿的提钒工艺研究结果表明,该石煤矿的最佳提钒工艺路线为预脱碳活化—浓酸熟化—水浸法提钒,但矿区中石煤矿的最高发热值仅为3 450 k J/kg,不能满足脱碳焙烧设备对燃料发热值的最低要求(燃料热值≥4 200 k J/kg)。本研究根据矿山中钒资源主要分布于两个区域,且一个矿区钒资源储量少(占资源量的25.5%),矿石含钒含碳均较低,另一个区域钒资源储量高(占资源量的74.0%),矿石含钒含碳均较高的实际情况,对含钒含碳均较低的矿石进行选矿处理,得到了V2O5含量为1.69%,热值为5 920 k J/kg的碳精矿,将其作为高热值燃料与含钒含碳较高的矿石配制成热值≥4 200 k J/kg的混合料后作为提钒原料,顺利解决了脱碳焙烧设备对燃料热值的要求。     

原位法制备Cu-Nb合金线材的电阻率

本文讨论了用“原位法”制备的Cu-Nb合金线材的电阻率,研究了冷形变时横断面减缩比、退火温度及合金中铌含量对电阻率的影响,提出了近似计算公式,实验证明计算值与实测值基本吻合。     

Kriging法在场地液化势估值中的应用

GIS岩土工程决策评价系统是城市数字化的一个重要组成部分 ,如何充分利用已有的工程勘察信息、评价成果对预测和评价场地工程性状是系统性能效能的重要表征。该文基于地质统计学方法 ,分析了饱和砂土场地液化势数据结构特征 ,并对整个区域进行了空间插值。结果表明Kriging方法适用于砂土场地液化势及其它岩土参数的空间估值。     

一种新结构超支化环氧树脂的合成及其性能研究

以双酚A(BPA)作为A2单体,异氰尿酸三缩水甘油酯(TGIC)作为B3单体,采用质子转移法合成了一种结构新颖的超支化环氧树脂.采用FTIR、NMR、GPC对该环氧树脂的结构和分子量进行了表征.固化产物的极限氧指数达到26,热分解(5%)温度为266℃,具有较好的阻燃性与热稳定性.