The oscillatory behavior of neutral differential equation with positive and negative coefficients is investigated by mathematics analysis technique and the fixed point principle. Some sufficient conditions for oscilla...The oscillatory behavior of neutral differential equation with positive and negative coefficients is investigated by mathematics analysis technique and the fixed point principle. Some sufficient conditions for oscillation of neutral differential equation with positive and negative coefficients are obtained.展开更多
Let C be a nonempty bounded subset of a p-uniformly convex Banach space X, and T = {T(t): t S} be a Lipschitzian semigroup on C with lim inf |||T(t)||| < Np, where Np is n→ t s the normal structure coefficient of ...Let C be a nonempty bounded subset of a p-uniformly convex Banach space X, and T = {T(t): t S} be a Lipschitzian semigroup on C with lim inf |||T(t)||| < Np, where Np is n→ t s the normal structure coefficient of X. Suppose also there exists a nonempty bounded closed convex subset E of C with the following properties: (P1)x: E implies ωω(χ) C E; (P2)T is asymptotically regular on E. The authors prove that there exists a z E such that T(s)z = z for all s S. Fruther, under the similar condition, the existence of fixed points of Lipschitzian semigroups in a uniformly convex Banach space is discussed.展开更多
叶片覆冰会严重影响风机的安全稳定运行。目前,电热防冰是最高效可靠的风机叶片防冰方法,但存在防冰区域受热不均匀、局部覆冰以及过多分区导致防冰系统过于复杂等问题。为此提出采用正温度系数(positive temperature coefficient,PTC)...叶片覆冰会严重影响风机的安全稳定运行。目前,电热防冰是最高效可靠的风机叶片防冰方法,但存在防冰区域受热不均匀、局部覆冰以及过多分区导致防冰系统过于复杂等问题。为此提出采用正温度系数(positive temperature coefficient,PTC)材料进行风机叶片自适应电加热防冰的创新方法,通过原位聚合法成功制备了一种低居里点PTC材料,其居里温度点为1℃。随后,基于该材料的阻-温特性,建立了风机叶片的电加热防冰模型,并进行数值模拟。研究结果显示,当采用低居里点PTC材料进行风机叶片电加热防冰时,无需进行防冰区域的分区,就能使得防冰区域受热更加均匀。在一定的工作电压下,低居里点PTC材料在不同环境温度和风速下展现出自适应调节加热功率的能力,并且经过100次循环阻-温测试后,材料仍具有极强的自适应调节能力。最后,通过试验验证了材料的这种自适应调节能力。该研究结果为后续基于低居里点PTC材料的风机叶片防冰系统的研究奠定了坚实基础。展开更多
Let X be a Banach space with a weak uniform normal structure and C a non–empty convex weakly compact subset of X. Under some suitable restriction, we prove that every asymptotically regular semigroup T = {T(t) : t ∈...Let X be a Banach space with a weak uniform normal structure and C a non–empty convex weakly compact subset of X. Under some suitable restriction, we prove that every asymptotically regular semigroup T = {T(t) : t ∈? S} of selfmappings on C satisfying展开更多
文摘The oscillatory behavior of neutral differential equation with positive and negative coefficients is investigated by mathematics analysis technique and the fixed point principle. Some sufficient conditions for oscillation of neutral differential equation with positive and negative coefficients are obtained.
基金the National Natural Science Foundation of China (No.19801023) and theTeaching and Research Award Fund for Outstanding Young T
文摘Let C be a nonempty bounded subset of a p-uniformly convex Banach space X, and T = {T(t): t S} be a Lipschitzian semigroup on C with lim inf |||T(t)||| < Np, where Np is n→ t s the normal structure coefficient of X. Suppose also there exists a nonempty bounded closed convex subset E of C with the following properties: (P1)x: E implies ωω(χ) C E; (P2)T is asymptotically regular on E. The authors prove that there exists a z E such that T(s)z = z for all s S. Fruther, under the similar condition, the existence of fixed points of Lipschitzian semigroups in a uniformly convex Banach space is discussed.
文摘叶片覆冰会严重影响风机的安全稳定运行。目前,电热防冰是最高效可靠的风机叶片防冰方法,但存在防冰区域受热不均匀、局部覆冰以及过多分区导致防冰系统过于复杂等问题。为此提出采用正温度系数(positive temperature coefficient,PTC)材料进行风机叶片自适应电加热防冰的创新方法,通过原位聚合法成功制备了一种低居里点PTC材料,其居里温度点为1℃。随后,基于该材料的阻-温特性,建立了风机叶片的电加热防冰模型,并进行数值模拟。研究结果显示,当采用低居里点PTC材料进行风机叶片电加热防冰时,无需进行防冰区域的分区,就能使得防冰区域受热更加均匀。在一定的工作电压下,低居里点PTC材料在不同环境温度和风速下展现出自适应调节加热功率的能力,并且经过100次循环阻-温测试后,材料仍具有极强的自适应调节能力。最后,通过试验验证了材料的这种自适应调节能力。该研究结果为后续基于低居里点PTC材料的风机叶片防冰系统的研究奠定了坚实基础。
基金supported both by the Teaching and Research Award Fund for Outstanding Young Teachers in Higher Education Institutions of MOE,P.R.C.by the National Natural Science Foundation 19801023
文摘Let X be a Banach space with a weak uniform normal structure and C a non–empty convex weakly compact subset of X. Under some suitable restriction, we prove that every asymptotically regular semigroup T = {T(t) : t ∈? S} of selfmappings on C satisfying
