Equilibrium shapes and quasi-static formation of bubbles at submerged orifice

A detailed analysis of the effect of chamber volume, orifice radius, orifice submergence and contact angle on quasi-static formation of bubbles is presented. It is shown, that many aspects of slow bubble formation, involving phenomena leading to various modes of the bubble release, as well as the maximum orifice diameter which sustains a bubble at equilibrium, can be explained on the basis of information on equilibrium shapes and conditions. Scaling rules enabling adoption of results for water to other liquids are also presented.     

Effect of government actions on technological innovation for SO2 control

The relationship between government actions and innovation in environmental control technology is important for the design of cost-effective policies to achieve environmental goals. This paper examines such relationships for the case of sulfur dioxide control technology for U.S. coal-fired power plants. The study employs several complementary research methods, including analyses of key government actions, technology patenting activity, technology performance and cost trends, knowledge transfer activities, and expert elicitations. Our results indicate that government regulation appears to be a greater stimulus to inventive activity than government-sponsored research support alone, and that the anticipation of regulation also spurs inventive activity. Regulatory stringency focuses this activity along particular technical pathways and is a key factor in creating markets for environmental technologies. We also find that with greater technology adoption, both new and existing systems experience notable efficiency improvements and capital cost reductions. The important role of government in fostering knowledge transfer via technical conferences and other measures is also seen as an important factor in promoting environmental technology innovation.     

The potential for phytoremediation of MTBE

This paper examines the potential for phytoremediation of MTBE, a gasoline additive that has become a prevalent and persistent groundwater pollutant, due to its' non-sorbing and non-reactive nature in water. A novel experimental design is developed to measure plant uptake and transpiration of MTBE from hydroponic systems, separating these processes from passive volatilization of the chemical. Plant uptake experiments indicate 30% reduction in MTBE mass in water over a 1-week period by small poplar saplings, at both high (1600 ppb) and low (300 ppb) MTBE concentrations. Active plant uptake of MTBE was approximately double that achieved by passive volatilization through a balsa wood control. MTBE was detected in biomass at the 100-ppb level, confirming passage of MTBE through the plant. A mass balance indicated that MTBE was largely untransformed during transport through the small poplar saplings to air. The high degree of MTBE removal achieved by small plants over a short period of time indicates great potential for successful phytoremediation of subsurface MTBE plumes using poplar trees. The fraction of MTBE removed from the hydroponic systems correlated well with volume of water transpired by the plants; the correlation enabled computation of the MTBE transpiration stream concentration factor of approximately 1, an important parameter for the design of engineered MTBE phytoremediation systems.     

On a mechanism of stabilizing turbulent free shear layers in cavity flows

Turbulent free shear flows are subject to the well-known Kelvin–Helmholtz type [Panton RL. Incompressible flow. John Wiley and Sons; 1984. p. 675] instability, and it is well-known that any free shear flow which approximates a thin vorticity layer will be unstable to a wide range of amplitudes and frequencies of disturbance. In fact, much of what constitutes flow control in turbulent free shear layers consists of feeding a prescribed destabilizing disturbance to these layers. The question in the control of free shear flows is not whether the shear layer will be stable, but whether you can influence how the layer becomes unstable. In most cases, since these flows are so receptive to forcing input, and naturally tend toward instability, large changes in flow conditions can be achieved with very small amplitude periodic inputs.

Recently, it has been discovered that turbulent free shear flows can also be stabilized using periodic forcing. This is, at first glance, counter-intuitive, considering our long history of considering these flows to be very unstable to forcing input. It is a phenomenon not described in modern fluid dynamic text books. The forcing required to achieve this effect (which we will call turbulent shear layer stabilization) is of a much higher amplitude and frequency than the more traditional type of shear layer flow control effect seen in the literature (which we will call turbulent shear layer destabilization).

A numerical study is undertaken to investigate the effect of frequency of pulsed mass injection on the nature of stabilization, destabilization and acoustic suppression in high speed cavity flows. An implicit, 2nd-order in space and time flow solver, coupled with a recently developed hybrid RANS-LES (Reynolds Averaged Navier Stokes-Large Eddy Simulation) turbulence model by Nichols and Nelson [Nichols RH, Nelson CC. Weapons bay acoustic predictions using a multi-scale turbulence model. In: Proceedings of the ITEA 2001 aircraft-stores compatibility symposium, March 2001], is utilized in a Chimera-based parallel format. This tool is used to numerically simulate both an unsuppressed cavity in resonance, as well as the effect of mass-addition pulsed jet flow control on cavity flow physics and ultimately, cavity acoustic levels.

Frequency (and in a limited number of cases, amplitude) of pulse is varied, from 0 Hz (steady) up to 5000 Hz. The change in the character of the flow control effect as pulsing frequency is changed is described, and linked to changes in acoustic levels. Limited comparison to 1/10th scale experiments is presented.

The observed local stabilization of the cavity turbulent shear layer, when subjected to high frequency pulsed blowing, is shown in simulation to be the result of a violent instability and breakdown of a pair of opposite sign vortical structures created with each high frequency “pulse”. This unique shear layer stabilization behavior is only observed in simulation above a certain critical pulsing frequency. Below this critical frequency, pulsing is shown in simulation to provide little benefit with respect to suppression of high cavity acoustic levels.     

Cuprate Superconducting Characteristics on the Doping Scale. A Multiband Approach

Some results on the doping dependence of cuprate superconductivity characteristics by an multiband approach are presented. A nonmonotonic dependence of the critical coherence length agrees with the experiment. Periodic spatial structures of T _c , etc. are expected at underdoping by Leggett noncritical mode fluctuations. The paired carrier effective mass diminishes moderately with doping. The inverse plane penetration depth shows a dependence with a maximum dominated by the supercarrier density. For the latter, the isotope effect is predicted and calculated. It is decisive for the isotope effect in the superfluid stiffness. This work was supported by the Estonian Science Foundation Grant No. 6540.     

基于spikes-LFP相关性的相位同步化研究

神经系统的信息处理过程依赖于一种基本的神经机制-相位同步化.已往的研究表明单个神经元的spike与LFP构成同步化时会对应一个精确的相位,该相位能够对进一步处理信息以及与时间相关的可塑性产生影响.本文基于这项研究,提出了一种新颖的研究同步化现象的方法.运用该方法探索局部场电位(LFP)与神经元动作电位发放(Spikes)之间的相关性,该方法不仅能够保证数据分析的可靠性,而且在使用方面更简单、更具普遍性.     

An improved selective attention model considering orientation preferences

An improved selective attention model is proposed in this paper, which is designed as a network of spiking neurons of Hodgkin--Huxley type with star-like connections between the central units and peripheral neurons. In this model, peripheral neurons represent the neurons located in the primary visual cortex. Since orientation preference is an important property of neurons in primary visual cortex, it should be considered except for external stimuli intensity. Simulation results show that the improved model can sequentially select objects with different orientation preferences and has a reliable shift of attention from one object to another, which are consistent with the experimental results that the neurons with different orientation preferences are laid out in pinwheel patterns.     

Heterogeneous calculation of hexagonal lattices by the method of passage probabilities

A method is proposed for determining the characteristics of heterogeneous hexagonal cells using first-collision probabilities—probabilities of passage, escape, and collisions, as well as calculations of the flows in cell zones on the basis of balance equations for the current. The spatial-angular dependence of the current at the sides of a cell is described in a discrete approximation, and the nonuniformity of the sources and flows in zones in described using spatial harmonics. The results obtained in one-group calculations of model lattices by the passage probability and Monte Carlo methods are compared. 3 figures, 5 tables. 5 references. IPé, Belarussian Academy of Sciences. Translated from Atomnaya énergiya, Vol. 87, No. 5, pp. 330–335, November, 1999     

辽宁省凌源县牛河梁出土的炉壁研究

在牛河梁的一座人工建造的金字塔顶部发现的，被认定是从其它地方迁移过去的炉壁残片及其粘附的炉渣是辽西地区年代最早的冶铜遗物，热释光测定其年代为距今３００～３５００年，属夏家店下层化，炉渣含镁较高，夹杂有各种粒度的纯铜颗粒财质广场 河梁附近有多处古代开采遗迹的铜矿点，其脉石矿物也含有较高的镁，这些事实表明这些炉壁残片及其粘附的炉渣是冶炼当地氧化矿石的遗物，炉壁残片结果显示，炼炉上部内径约２５ｃｍ，有     

INTEGRAL EQUATION APPEOACH FOZ SIHULATION-OF - HEAT AND MASS TRANSFER PROCESSES

An integral equation approach was recommended for modelling and simulation of heat and mass transfer processes. It was shown that several mixing models that have been dealt with up to now dlfferently, can be unified in a single integral equation. An effective numerical method was developed for the solution of non-linear integral equation. A construction method for the source and kernel functions were lntroduced in connection with the simulation and control of heat treatlng processes taking place in tunnel kiln and heat and mass transfer processes in tunnel dryer.

We have concluded that our method is advantageous If the slmulated process 1s slgnlficantly affected by the degree of mixing and/or the kernel function can be determined by direct measurement of the streaming phases including feedback, recirculation etc.