交通拥堵的平均场延迟反馈控制方法

【目的】在优化速度模型的基础上,引入平均场延迟反馈控制方法抑制交通的拥堵。【方法】将当前车受到的所有其它车的作用用一个平均场力来代替,将延迟耦合作为延迟反馈控制项,在交通流演化过程中,通过开-关(on-off)加载控制以抑制交通的拥堵;通过线性稳定性分析得出稳定性条件;最后用数值模拟验证控制方法的有效性。【结果】稳定性分析得出交通流在控制作用下趋于稳定,数值模拟分析对比发现拥堵交通流在施加控制后,车间距-速度相图中的交通滞后曲线区域缩小,以此判断交通拥堵得以缓解。【结论】交通流平均场延迟反馈控制方法可以有效地抑制交通拥堵,控制增益越大,交通拥堵缓解程度越好,而且该反馈控制在智能交通(ITS)中易于实现。     

混合自旋无规律键横向伊辛模型的有限集团近似

用有限集团近似（FCA）研究了自旋为－1／2与－3／2的混合自旋向无规键伊辛模型,讨论了相图与其它的临界性质,发现了来自于交换作用起伏的重入现象。     

面向机群并行计算的分组通信模型

提出了一个计算机机群环境下的分组通信算法,防止通信峰值阶段通信冲突对机群执行效率的影响,给出了完全图通信的形式化定义,构造了基于分组机制的完全图通信模型的实现方法,分析和实现表明,该模型有效地解决了计算机机群环境下通信峰值所造成的集群效率低下的问题,适用于机群的数据密集型并行计算。     

CD38 is critical for social behaviour by regulating oxytocin secretion

CD38, a transmembrane glycoprotein with ADP-ribosyl cyclase activity, catalyses the formation of Ca2+ signalling molecules, but its role in the neuroendocrine system is unknown. Here we show that adult CD38 knockout (CD38-/-) female and male mice show marked defects in maternal nurturing and social behaviour, respectively, with higher locomotor activity. Consistently, the plasma level of oxytocin (OT), but not vasopressin, was strongly decreased in CD38-/- mice. Replacement of OT by subcutaneous injection or lentiviral-vector-mediated delivery of human CD38 in the hypothalamus rescued social memory and maternal care in CD38-/- mice. Depolarization-induced OT secretion and Ca2+ elevation in oxytocinergic neurohypophysial axon terminals were disrupted in CD38-/- mice; this was mimicked by CD38 metabolite antagonists in CD38+/+ mice. These results reveal that CD38 has a key role in neuropeptide release, thereby critically regulating maternal and social behaviours, and may be an element in neurodevelopmental disorders.     

An improvement in selfconsistent cluster method for determining the critical point in Ising spin system

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Unconventional critical behaviour in a quasi-two-dimensional organic conductor

Changing the interactions between particles in an ensemble--by varying the temperature or pressure, for example--can lead to phase transitions whose critical behaviour depends on the collective nature of the many-body system. Despite the diversity of ingredients, which include atoms, molecules, electrons and their spins, the collective behaviour can be grouped into several families (called 'universality classes') represented by canonical spin models. One kind of transition, the Mott transition, occurs when the repulsive Coulomb interaction between electrons is increased, causing wave-like electrons to behave as particles. In two dimensions, the attractive behaviour responsible for the superconductivity in high-transition temperature copper oxide and organic compounds appears near the Mott transition, but the universality class to which two-dimensional, repulsive electronic systems belongs remains unknown. Here we present an observation of the critical phenomena at the pressure-induced Mott transition in a quasi-two-dimensional organic conductor using conductance measurements as a probe. We find that the Mott transition in two dimensions is not consistent with known universality classes, as the observed collective behaviour has previously not been seen. This peculiarity must be involved in any emergent behaviour near the Mott transition in two dimensions.     

非饱和土的临界状态面模型

饱和土与非饱和土之间及非饱和土之间在力学性质上的差别主要是由于它们饱和度的不同而造成的．以饱和度作为参变量,以现有的比较成熟的土的本构理论作为基础,充分考虑饱和度的变化对土的工程性质的影响,根据塑性硬化理论和临界状态以及屈服面的概念,研究了非饱和土的流动法则和硬化规律,导出了非饱和土的应力应变增量公式,建立了一种较为简单的描述非饱和土应力应变特性的本构模型,为丰富和进一步完善非饱和土的本构理论作了有希的探讨．该模型具有广阔的工稃府用前景．     

有机铁磁体的研究进展及应用前景

阐述了有机铁磁体的研究动态。根据铁磁理论制造有机铁磁体的主要途径有有机金属复合物铁磁体与纯有机铁磁体,本文对这两种有机铁磁体特别是对纯有机铁磁体在目前所取得的研究成果做了较为详细的介绍与讨论,根据有机铁磁体的特性对有机铁磁体的应用前景进行了展望。     

HSK刀柄临界使用转速计算模型

为充分发挥空心短锥(hollow short taper, HSK)刀柄在高速切削中的应用潜能,分析了HSK刀柄在高速旋转过程中的失效形式,提出了在材料强度和夹紧力两方面的失效准则,综合考虑刀柄尺寸、过盈量、材料特性、离心力、拉杆拉力、切削力等因素的影响,基于弹塑性理论建立了HSK刀柄临界使用转速的理论计算模型.研究表明: 理论计算结果与有限元分析结果具有较好的一致性.一般情况下,夹紧力不足是夹紧系统高速旋转失效的主要原因.临界转速计算模型的建立,可以提高高速旋转刀具夹紧的安全性,并为充分发挥HSK刀柄的高速潜能提供重要的技术依据.     

中小企业集群复杂网络的局域双向适应度模型

通过综合考虑中小企业集群复杂网络具有局域世界性(群落结构)、竞争性、获取的信息不完全和不对称等特点,在BA模型的基础上构建了局域双向适应度模型. 运用连续介质理论和平均场理论建立起与之对应的演化方程,并计算出了它的严格解,导出了该模型的度分布和幂律指数的表达式. 研究结果表明该模型更具有普适性和真实性.     

S-P波混合超导的平均场理论谨以此文深切怀念敬爱的魏荣爵先生.他的关怀、支持和帮助,铭刻于心

对于由4个费米子相互作用系统组成的哈密顿量的平均场理论,当只有S波超导时,由SU(2)(局域同构于SO(3))代数表达,P波超导可以通过SO(5)表达,而对于S-P混合波超导的情况则由SU(4)(局域同构于SO(6))代数表达.本文通过在SO(6)代数中引入了反映S波和P波混合超导的SO (4)子集,从而可以通过对相干...     

公路车辆行驶临界速度计算模型

为了弥补设计速度理论在公路设计和管理中存在的不足,提出由客观条件决定的车辆最高安全行驶速度的物理量--公路车辆行驶临界速度.首先论述了设计速度理论存在的不足,分析了引入临界速度的必要性;研究了临界速度与设计速度的关系,分析了车辆动力性能、道路线形要素、道路关键设计参数对临界速度的影响机理;提出了临界速度由汽车动力性能和道路坡度决定,并受道路平纵线形、超高和视距等条件影响的观点,建立了临界速度的计算模型;最后,通过算例对临界速度的计算方法予以说明.     

一类具有脉冲的捕食与被捕食系统的动态行为

研究具有周期脉冲的捕食与被捕食模型的动态行为.通过喷洒杀虫剂和投放天敌的周期不同,得到了捕食系统害虫灭绝周期解的全局稳定性的临界值,分析喷洒杀虫剂和投放天敌的周期如何影响生物控制,为害虫治理提供了策略基础.     

准一维基于分子亚铁磁体自旋系统磁化率性质研究

基于交替自旋Ising—Hamiltonian模型,用量子转移矩阵方法,研究了不同外场条件下准一维基于有机分子亚铁磁体磁化率的结构序参量．对磁化率一的研究表明：双自由基和单自由基的交替有机自旋链的亚铁磁自旋排列等效于有效自旋S=1／2的铁磁相互作用链,双自由基有机高分子对具有单一成分的有机基于分子亚磁体具有绝对优势．量子Monte Carlo方法和精确对角化方法的计算结果两者相符,且与某些实验结果定性相符．     

三维伊辛模型临界点温度的模拟计算

用蒙特卡罗方法计算了三维伊辛模型的临界点温度，模拟计算的结果表明：与坐标空间重正化群方法相比，蒙特卡罗方法具有过程简单，效率高．结果准确的特点．     

Quantum critical behaviour in a high-T(c) superconductor

Quantum criticality is associated with a system composed of a nearly infinite number of interacting quantum degrees of freedom at zero temperature, and it implies that the system looks on average the same regardless of the time- and length scale on which it is observed. Electrons on the atomic scale do not exhibit such symmetry, which can only be generated as a collective phenomenon through the interactions between a large number of electrons. In materials with strong electron correlations a quantum phase transition at zero temperature can occur, and a quantum critical state has been predicted, which manifests itself through universal power-law behaviours of the response functions. Candidates have been found both in heavy-fermion systems and in the high-transition temperature (high-T(c)) copper oxide superconductors, but the reality and the physical nature of such a phase transition are still debated. Here we report a universal behaviour that is characteristic of the quantum critical region. We demonstrate that the experimentally measured phase angle agrees precisely with the exponent of the optical conductivity. This points towards a quantum phase transition of an unconventional kind in the high-T(c) superconductors.     

临界导电模式PFC电路的稳态特性

以PFC boost电路为例，近似认为电感电流线性变化，得出了临界导电模式PFC电路的输入电流和输入电压的关系，基于能量守恒原理进一步得出输出电压与输入电压和开关导通时间的关系，讨论了变换器损耗的影响。仿真和实验结果验证了理论分析的正确性。