Kähler流形上的Schwarz导数(Ⅱ)

证明了当目标流形是复投影空间CPⁿ和复超球Bⁿ(具有典则度量)时,Kahler流形的全纯映照的单射定理.至此,连同已经证明的关于复Euclid空间Cⁿ(具有平坦度量)的同样结果,对于全纯截曲率为一1,0,+1的目标流形建立了单射定理.     

热交换器中氦气流量对生长蓝宝石温场影响的研究

采用热交换法生长蓝宝石晶体,通过数值模拟与实验研究了晶体生长过程中热交换器中氦气流量对温场的影响.结果表明:晶体生长过程中固液界面为近弧面;随氦气流量增大,晶体与熔体的温度下降,温度梯度增大;加热器功率缓慢上升.     

CaMoO4∶Eu3+发光材料的制备和发光性质的研究

用共沉淀法与高温焙烧法制备了样品CaMoO4:Eu3+.TG-DTA谱图表明:800℃时,样品吸收的能量最大,即形成稳定的CaMoO4:Eu3+结构.用XRD谱图进一步分析表明:800℃时,样品CaMoO4:Eu3+已形成CaMoO4的白钨矿结构.由于2个Eu3+取代3个Ca2+,导致了晶体产生微小的晶体缺陷,从而形成具有p-n结的半导体.经过激发和发射谱图的测试发现:这种缺陷结构不但可以使Eu3+禁戒的4f电子发生跃迁,而且可以使MoO42-的能量高效地传递给Eu3+.尤其使与MoO42-的发射特征峰(488 nm)部分重叠的Eu3+(465 nm)的7F0→5D2电子跃迁得到了极大的加强,进而在λex=465 nm的发射谱图中,自激活荧光体MoO42-的发射强度被大大减弱甚至猝灭,而Eu3+的5D0→7F2(612 nm)跃迁的红光发光强度被大大增强,使该材料成为有潜在应用价值的发光材料.     

超临界循环流化床锅炉进风系统数值模拟分析与比较

本文针对超临界循环流化床锅炉一次风风箱系统内部的空气流动特性,包括进气管、风箱内部及一次风通过布风板的流动特性,基于FLUENT计算平台结合多孔介质模型进行了数值模拟。针对三种不同进风结构,即底部进风、侧面进风和后侧进风模式进行了分析比较。为准确模拟布风板压降损失同时又减少计算量,利用多孔介质模型模拟一次风通过布风板的...     

Sufficient conditions for invertibility of linear stationary systems

Sufficient conditions for the invertibility of linear stationary dynamical systems are formulated. It is shown that the a priori information that the input signal is bounded substantially expands the class of systems for which the inversion problem is solvable.     

On the problem of finding a bounded solution of unstable differential equation

The problem of finding the unique bounded solution of an unstable differential equation is considered. The properties of the problem and possible approaches to its solution are discussed.     

Transformation of Time-Delay Systems to a Form with Zero Dynamics

The problem of transforming a controlled linear stationary system of differential equations with commensurable time delays into a canonical form with zero dynamics is considered. This problem has been well studied for ODE systems and is closely related to the concept of a relative degree. In this paper, the results are extended to time-delay systems.     

On Reduction of Time-Delay Systems to a Form with Relative Degree

Differential Equations - We consider the problem of reducing a linear differential control system with commensurate delays by a nondegenerate linear change of outputs to a system for which a...