On sums of Darboux and nowhere constant continuous functions

We show that the property

(P)

for every Darboux function there exists a continuous nowhere constant function such that is Darboux

follows from the following two propositions:

(A)

for every subset of of cardinality there exists a uniformly continuous function such that ,

(B)

for an arbitrary function whose image contains a non-trivial interval there exists an of cardinality such that the restriction of to is uniformly continuous,

which hold in the iterated perfect set model.

     

Scale-Invariant Branch Distribution from a Soluble Stochastic Model

We consider a general model of branch competition that automatically leads to a critical branching configuration. This model is inspired by the 4– expansion of the dielectric breakdown model, but the mechanism of arriving at the critical point may be of relevance to other branching systems as well, such as fractures. The exact solution of this model clarifies the direct renormalization procedure used for the dielectric breakdown model, and demonstrates nonperturbatively the existence of additional irrelevant operators with complex scaling dimensions leading to discrete scale invariance. The anomalous exponents are shown to depend upon the details of branch interaction; we contrast with the branched growth model in which these exponents are universal to lowest order in 1–, and show that the branched growth model includes an inherent branch interaction different from that found in the dielectric breakdown model. We consider stationary and non-stationary regimes, corresponding to different growth geometries in the dielectric-breakdown model.     

Dielectric Relaxation of the β-Cyclodextrin Complexes with Tridecanoic Acid and 1,13-Tridecanedioic Acid

The frequency and temperature dependence of the real (') and imaginary (') parts of the dielectric permittivity of the polycrystalline complex-cyclodextrin-tridecanoic acid in two hydration forms (with 16.2 and 10.7 water molecules) and -cyclodextrin-1,13-tridecanedioic acid with 16.4 and 10.5 water molecules have been investigated, in the frequency range 0.1–100 kHz and temperature range 120–310 K. The dielectric behavior is described well by Debye-type relaxation dispersion. All systems except for the complex of partially dehydrated monocarboxylic acid, exhibit an additional -dispersion, at low frequencies (f < 1000 Hz). Only one-step was found in the ' vs. Tplots of both complexes in the two hydration forms, a fact indicating that the watermolecules cannot be divided into strongly bound and easily movable molecules. The'vs. T plots, at a fixed frequency (200 Hz), show the characteristic peakattributed to a transition between ordered and disordered -CD hydroxyl groupsand water molecules. The transition temperature was 202.7 K for all systems examinedexcept for the complex -CD-tridecanoic acid.16.2 H₂O (214.5 K). This means that the order to disorder transformation process was unaffected by the dehydration process in the case of the dicarboxylic acid complex, whereas in the case of the monocarboxylic acid, it was unexpectedly facilitated. The relaxation time varies with temperature, in a like curve (in the range 8–14 s), with maximum values located at the corresponding order-disorder transition temperatures. The activation energies of the fully hydrated complexes have absolute values of 5 kJ/mol in the range 1.98–3.82 K_{BT transition} which are higher than the corresponding values of :2 kJ/mol of the dehydrated complexes. A thermal hysteresis observed in all complexes is a result of the order-disorder transformation.     

低渗透油藏矢量井网设计与整体压裂优化研究

低渗透油藏渗流规律的研究表明,受储层非均质性及微裂缝的影响,注采井网的部署、整体压裂方案的优化对于改善低渗透油藏的开发效果和提高采收率有着重要的影响。提出了矢量井网的概念,阐述了矢量井网与储层非均质性的关系,研究了与矢量井网配套的压裂工艺,包括深井限流压裂、转向压裂、分步加砂压裂等。将矢量井网与整体压裂方案在胜利油田史深100块进行了现场实施。结果表明,矢量井网是实现低渗透油田高效开发的重要手段。     

水力裂缝层内爆燃压裂油井产能计算模型

基于水力裂缝层内爆燃压裂技术提高低渗透油田采收率和油井产量的基本设想,利用油藏渗流理论和节点系统分析方法,建立了水力裂缝层内爆燃压裂油井产能计算模型,并分析了水力裂缝和爆燃裂缝参数对油井产能的影响。研究结果表明,在低渗透油藏中,增加水力裂缝的长度比增加水力裂缝的导流能力对油井增产更有利;爆燃裂缝的存在可在水力裂缝增加油井产量的基础上进一步增产,相对于水力压裂油井,爆燃压裂油井增产倍数可达1.55。由此说明,利用水力裂缝层内爆燃压裂技术来提高低渗透油田油井产量是可行的。     

低渗透岩石非饱和非Darcy渗流机理

为了探讨低渗透岩石非饱和非D arcy的机理,以毛管模型为基础,通过对流体非饱和系列流动状况的运动分析,相应推导得出流体非饱和渗流的毛管模型,从理论上论证在微小尺度孔隙中流体自身的力学特性,以及与固体、气体的相互作用,指出毛管压力与边界层的存在,是导致流体非D arcy渗流现象的一个主要原因。研究这些因素对渗流运动的影响机制,是探索低渗透岩石非D arcy渗流机理的一个重要方向。     

The Application of Microwave Low Temperature Plasma in Pretreatment of Cotton Fabric

The effect of microwave low temperature plasma pretreatment on desizing and removing natural impurity of cellulose fiber was studied. The influencing factors of pretreatment such as treating power, gas pressures and time were discussed in detail and the final effect had been compared with that of traditional pretreating process of cotton fabric. The results showed that better capillary effect, strength, whiteness and dyeing K/S value could be given by means of microwave low temperature plasma treatment.     

x强流相对论环形电子束在低磁场中传输分析

 用理论和粒子模拟相结合的方法分析了强流薄环形相对论电子束在低磁场导引下，在均匀波导，无箔二极管，以及锥形波导和渐减磁场位形条件下的传输过程，研究了束包络的波动和如何减少波动的问题。分析表明：在无箔二极管中一个适当渐增的磁场位形可以有效地抑制束电子的径向运动，从而减少电子在波导中的波动幅度；电子束在锥形波导和渐减磁场位形中运动，不会增加束电子的波动。因此适当的磁场位形可以降低微波器件对导引磁场的要求，有利于实现永磁包装微波器件。     

N＋NO2反应动力学研究

采用UMP2(full)/6-31G*方法从理论上对N和NO2的反应进行了研究,计算了各反应通道上所有驻点的构型参数和振动频率,根据相对的G2MP2能量绘制的势能剖面图详细给出了N和NO2的反应机理.在此基础上,应用经Wigner校正的Eyring过渡态理论计算了在280~1 500 K温度范围内,1大气压下该反应3个反应通道的活化热力学量、反应速率常数、频率因子.计算结果表明:N NO2→IM→TS1→N2 O2是主要反应通道,N2和O2为主要产物.