Hierarchical porous carbon/selenium composites derived from abandoned paper cup as Li-Se battery cathodes

Paper cup composed of crude cellulose is a common waste in daily life. In this paper, hierarchical porous carbons have been successfully prepared by an initial hydrothermal treatment and subsequent activation route from abandoned paper cup, and then paper cup derived carbons are used as scaffolds to fabricate serial carbon/Se composites. The optimal composite presents unique 3D porous structure, with amorphous selenium uniformly confined into the micropores of carbon. As the cathode materials of Li-Se battery, this composite reveals an initial reversible discharge capacity of 517.2 mAh g⁻¹ at 0.2C, and a capacity value of 431.9 mAh g⁻¹ can be retained after 60 cycles. Even at a high rate of 4C, a capacity value of 295.8 mAh g⁻¹ can be obtained. By comparison, the improved electrochemical performance of the optimal composite should be attributed to reasonable porous structure and effective encapsulation of amorphous selenium.     

隐丹参酮和丹参酮IIA滤纸基质室温磷光法的研究

考察了隐丹参酮和丹参酮 IIA的滤纸基质室温磷光法 ( PS- RTP)特性。选择Cd( Ac) 2 作为重原子微扰剂 ,对影响这两种丹参酮类化合物发光强度的各种因素进行了详细研究。同时建立了隐丹参酮和丹参酮 IIA的 PS- RTP分析测定的新方法     

从非线性动力学的视角认识细长压杆的稳定性

工程上大部分机构和结构都处于动载的作用下，受压细长杆的失稳是复杂的动力破坏事件．应用Lagrange描述法建立了两端角铰支受压细长杆的非线性动力学模型，通过对这种模型简化分别得到非线性静力学模型、线性动力学模型和含三次非线性项的动力学模型．利用谱截断方法，讨论了线性动力学模型的局部分岔．通过讨论平衡态存在性和稳定性，得到了含三次非线性项的动力学模型分岔条件．研究表明，受压细长杆的非线性动力学模型中存在叉形分岔．     

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利用有限元软件,通过对撑竿跳高过程的大变形动力学数值模拟,得到了不同材料 撑竿的变形过程、跳高成绩,以及能量的转化效率指标. 通过截面尺寸设计,预测了不同材 料撑竿所能达到的最大高度. 最后以布勃卡的体能参数为标准,为其设计能越过最大高度的 等截面和变截面碳纤维复合材料撑竿.     

纸质活性炭纤维的制备及性能表征

通过KOH活化纸巾制备活性炭纤维, 比表面积高达1388 m²/g. 用制得的活性炭纤维作为吸附剂进行亚甲基蓝吸附实验研究,用Langmuir和Freundlich吸附模型分析实验数据,并研究pH值对活性炭纤维吸附亚甲基蓝影响. 活性炭纤维吸附速率更适于Pseudo-second-order动力学模型,相关系数高达0.998. 整个浓度变化区间Langmuir吸附等温线比Freundlich吸附等温线更适合实验数据. 所制备活性炭纤维对亚甲基蓝最大平衡吸附量为520 mg/g,实验发现,pH值越高活性炭纤维对亚甲基蓝吸附量越大.     

L-Factor of Irreducible x1×x2(×)σ

The L-factor of irreducible x1×x2(×)σ defined by Piatetski-Shapiro is computed by using non-split Bessel functional.     

预给极点的向量有理插值及性质

1　引　　言在工程技术中经常会遇到一些多元奇异函数的计算问题,常规的有理插值方法无疑为这类问题的近似求解提供了有效的途径,但有时逼近效果不一定十分理想,其重要原因之一是人们往往采用统一的框架去构造有理插值公式,而忽略了被逼近对象的一些本质特征.针对某些具体问题,例如已知被逼近的向量值函数的奇异点的有关信息,构造一种预给极点的向量有理插值格式就显得很有必要,其逼近效果自然会更理想.设R2中的点集Πn,m={(xi,yj)|i=0,1,…,n;j=0,1,…,m},相应的d维向量集Vn,m={Vi,j∈Cd|i=0,1,…,n;j=0,1,…,m}.设V∈Cd为任一d维…     

一类预给极点的有理样条的构造

构造了一类特殊的有理样条,给出其表现公式及唯一性证明,并通过实例说明其优越性.     

Nonequivalence transformation of λ‐matrix eigenproblems and model embedding approach to model tuning

In this paper we present some theory for a non‐equivalence transformation of matrix eigenvalues for λ‐matrix polynomials. Application of this transformation to eigenvalue embedding for model tuning on a realistic industry problem is illustrated. The new approach has several advantages such as flexibility, efficiency, and structure‐preservation. A numerical experiment on a pseudosimulation data set from The Boeing Company is reported. Copyright © 2001 John Wiley & Sons, Ltd.     

退化时滞系统的极点配置

This paper deals with the pole placement of the singular system Ex~.=Ax(t) Dx(t-(?)) Bu, y=Cx, where x∈R~n,u∈R~m,and y∈R~n are its state,control input and measure output respectively;E,A∈R~(n×n),B∈R~(n×m),and C∈R~((?)×n) are constant matrices.It is also assumed that rankE相似文献