新时期“两实”管理长效机制建立的难点与破解

"两实"管理是当前推进社会管理创新的一项重大决策。"两实"管理工作必须坚持"政府领导、公安主导、部门协作、社会参与"的原则。通过制度化、法制化、部门沟通与协作、信息资源共建共享等渠道构建"两实"管理长效机制。

用“两实一虚”等效电路分析线性集成运放电路

对各种形式的线性集成运放电路，用本文提出的与含有两条实支路，一条虚支路的电路等效，进而对其激励与响应的关系进行分析，方法简单易掌握，规律性强，有助于学生准确地分析复杂的线性集成运放电路．

立足文本 从“简”从“实”——谈小学语文阅读教学

时下大多数语文课堂都呈现一片繁荣景象,遮蔽了语文教学的本质。教师应正确解读文本,认真做到“四简”“两实”——即制订简明的教学目标,简约教学内容,简单教学手段,简化教学环节,注重文本对话。适当拓展延伸,实实在在地进行阅读教学、扎扎实实地进行语文教学。

Experimental detection of bubble-wall interactions in a vertical gas–liquid flow

Bubble motions and bubble-wall interactions in stagnant liquid were experimentally investigated by high-speed CCD and PIV technique with the main feature parameters such as E?tv?s numbers Eo = 0.98–1.10, Morton number Mo = 3.21 × 10^(-9)and Reynolds numbers Re = 180 ~ 190. The effect of bubble injecting frequency and the distance S between the gas injection nozzle and the wall on the statistical trajectory of bubbles, average velocity distribution of flow field and Reynolds shear stress were studied in detail. It was shown that the combination of bubble injecting frequency and the distance S caused different bubble motion forms and hydrodynamic characteristics.When the normalized initial distance was very little, like S*≈ 1.2(here S*= 2S/d_e, and deis the bubble equivalent diameter), bubbles ascended in a zigzag trajectory with alternant structure of high and low speed flow field around the bubbles, and the distribution of positive and negative Reynolds shear stress looked like a blob. With the increase of distance S*, bubbles' trajectory would tend to be smooth and straight from the zigzag curve. Meanwhile, with the increase of bubble injecting frequency, the camber of bubble trajectory at 20<y<60 mm had a slight increase due to the inhibitory effect from the vertical wall. Under larger spacing, such as S*≈ 3.6, the low-frequency bubbles gradually moved away from the vertical plane wall in a straight trajectory and the high-frequency bubbles gradually moved close to the vertical wall in a similar straight trajectory after an unstable camber motion. Under the circumstances, high-speed fluid was mainly distributed in the region between the wall and the bubbles, while the relative large Reynolds shear stress mainly existed in the region far away from the wall.

An Experimental Study on the Flow Characteristics of OilWater Two-Phase Flow in Horizontal Straight Pipes

The flow patterns and their transitions of oil-water two-phase flow in horizontal pipes were studied. The experiments were conducted in two kinds of horizontal tubes, made of plexiglas pipe and stainless steel pipe with 40 mm ID respectively. No. 46 mechanical oil and tap water were used as working fluids. The superflcial velocity ranges of oil and water were: 0.04-1.2m·s-1 and 0.04-2.2m·s-1, respectively. The flow patterns were identified by visualization and by transient fluctuation signals of differential pressure drop. The flow patterns were defined according to the relative distribution of oil and water phases in the pipes. Flow pattern maps were obtained for both pipelines. In addition, semi-theoretical transition criteria for the flow patterns were proposed, and the proposed transitional criteria are in reasonable agreement with available data in liquid-liquid systems.

Numerical Investigation of a New Method for Reducing Bends Erosion from Particles Impacts

The present paper intends to introduce a new method for reducingbends erosion from particles impacts: the ribbed bend erosionprotection method. Ribs are evenly fixed in the range of 20 deg-80deg on the inner-wall of inside 90 deg bend and the bend (includingribs) is made of medium carbon steel. Three-dimensional numericalworks is performed and the result shows satisfactory agreement withthe experimental measurement. Numerical simulation studies thecharacteristics of axial gas flow along the bend and secondary flowat cross section.

Water invasion and remaining gas distribution in carbonate gas reservoirs using core displacement and NMR

Water invasion is a common phenomenon in gas reservoirs with active edge-and-bottom aquifers.Due to high reservoir heterogeneity and production parameters,carbonate gas reservoirs feature exploitation obstacles and low recovery factors.In this study,combined core displacement and nuclear magnetic resonance(NMR)experiments explored the reservoir gas−water two-phase flow and remaining microscopic gas distribution during water invasion and gas injection.Consequently,for fracture core,the water-phase relative permeability is higher and the co-seepage interval is narrower than that of three pore cores during water invasion,whereas the water-drive recovery efficiency at different invasion rates is the lowest among all cores.Gas injection is beneficial for reducing water saturation and partially restoring the gas-phase relative permeability,especially for fracture core.The remaining gas distribution and the content are related to the core properties.Compared with pore cores,the water invasion rate strongly influences the residual gas distribution in fracture core.The results enhance the understanding of the water invasion mechanism,gas injection to resume production and the remaining gas distribution,so as to improve the recovery factors of carbonate gas reservoirs.

Recent Progress in JAXA Project of Boiling Two-Phase Flow Experiment onboard ISS

The amount of waste heat in a space facility became larger, because of increase in the space platform size and its power consumption. It requires development of high-performance space thermal management systems handling a large amount of waste. Boiling two-phase flow could become powerful means for this system because a boiling and condensation system is one of the most efficient modes of heat transfer due to phase change （liquid-vapor）. However, gravity effects on boiling two-phase flow phenomena and the corresponding heat transfer characteristics are not clear. Therefore, we prepare the experiments of boiling two-phase flow utilizing a long-term microgravity environment onboard a Japanese Experimental Module ＂KIBO＂ in the International Space Station （ISS） as one of the JAXA official projects. In this paper, recent progress of the preparation for the project is reported.

Experimental Investigation of a Single-Stage Four-Valve Pulse Tube Refrigerator

In order to simplify the structure of the cold end of the pulse tube refrigerator (PTR) and have a better utilization of the cold energy of the system, a one-stage four-valve pulse tube refrigerator (FVPTR) with an "L" type pulse tube structure and two orifice valves at the hot end of pulse tube has been constructed. Verification experiments show that the two orifice valve structure performs better than one orifice valve structure. A lowest temperature of 67.5 K was obtained at a frequency of 2.5 Hz under a system average pressure of 1.5 MPa with 200 mesh bronze screens as regenerator material, 80 mesh copper screens as stuffing material of heat exchanger. Due to the difficulty in manufacturing the thin "L" type pulse tube, the wall thickness of the pulse tube in the experiment was relatively difficult for us to reach 0.5 mm as that of the ordinary pulse tube, which resulted in relatively big system loss and affected the minimum temperature of the system to some degree.

Gas-Liquid Two-Phase Axial Backmixing Through Structured Packing at Elevated Pressure

An experimental study of the extent of axial backmixing in both gas and liquid phases was conducted in a 150 mm ID column packed with Mellapak 250Y corrugated structured packing. The column was operated at pressures ranging from 0.3 MPa to 2.0MPa with nitrogen and water flowing countercurrently through the packing. The amount of axial backmixing was experimentally evaluated by the pulse response techniques using hydrogen in gas phase and an aqueous solution of NaCl in liquid phase as inert tracers. The response of the tracer was monitored by means of thermal conductivity in the gas phase and electrical conductance in the liquid phase. The experimentally determined residence time distribution (RTD) curves were interpreted in terms of the diffusion-type modei. The results indicated that the axial backmixing in the gas increased notably with gas flowrate and slightly with operating pressure and liquid flowrate. The liquid-phase axial backmixing was an increasing function of both gas and liquid flowrates and insensitive to pressure. Various correlations were developed for reproducing the experimental mixing data. The agreement between experimental and correlated data appeared to be acceptable and within ±20% of difference.

Developments in the understanding of gas–solid contact efficiency in the circulating fluidized bed riser reactor:A review

In the last several decades, circulating fluidized bed reactors have been studied in many aspects including hydrodynamics, heat and mass transfer and gas–solid two phase contacting. However, despite the abundance of review papers on hydrodynamics, there is no summary paper on gas–solid contact efficiency to date, especially on high density circulating fluidized beds(CFBs). This paper gives an introduction to, and a review of the measurement of contact efficiency in circulating fluidized bed riser. Firstly, the popular testing method of contact efficiency including the method of heating transfer experiment and hot model reaction are discussed, then previous published papers are reviewed based on the discussed methods. Some key results of the experimental work are described and discussed. Gas–solid contact efficiency is affected by the operating conditions as well as the particle size distribution. The result of the contact efficiency shows that the CFB riser is far away from an ideal plug flow reactor due to the characteristics of hydrodynamics in the riser. Lacunae in the available literature have been delineated and recommendations have been made for further work.

Experimental Acoustic Determination of the Void Fraction in Two-Phase Flow in Horizontal Pipelines

In multi-phase flows, the phases can flow and arranged in different spatial configurations in the pipe, which called flow patterns. This type of flow is found in the oil, chemical and nuclear industries. For example, in the production and transport of oil and gas, the identification of the flow patterns are essential for answering those questions which are related to the economic return of the field, such as, measuring the volumetric flow, determining the pressure drop along the flow lines, production management and supervision. In offshore production, these factors are very important. This paper presents a new method for measuring the void fraction in horizontal pipelines, taking the air as gas in water-air two-phase flow. Through acoustic analysis of the frequency response of the pipe, the method gets the parameters to changes in runoff regime, in an experimental arrangement constructed on a small scale. The main advantages are the non-intrusive characteristic and easy to implement. The paper is composed of a qualitative experimental evaluation and transducers （microphone） which are used to analyze variations in the response accompanying variations in void and flow pattern changes. Changes are imposed and controlled by a two-phase flow experimental simulation rig, including a measurement cell constituted of an external casing that can isolate the measurement from the environmental background noise fitted with acoustic pressure transducers radially arranged, and the impact of a monitored excitation mechanism. The signals which captured by the microphones are processed and analyzed by checking their frequency contents changes according to the amount of air in the mixture.

Differences in seed dormancy and germination in amphicarpic legumes:manifold bet-hedging in space and time

Aims Dispersal through space or time via dormancy is one of the primary processes whereby organisms can influence the environment they experience.In plants,strong evolutionary correlations are expected between the two kinds of dispersal because both are performed by the seeds and play comparable adaptive roles.In this paper,we investigated these evolutionary correlations using amphicarpic plants,which simultaneously produce aerial seeds with high spatial dispersal propensity and subterranean seeds that do not disperse.Methods We investigated the variation in dormancy and germination in aerial and subterranean seeds of two amphicarpic legumes(Vicia amphicarpa L.and Lathyrus amphicarpos L.)and two closely related homocarpic taxa(Vicia sativa L.and Lathyrus cicera L.)by estimating germination percentages following different combinations of dormancy breaking treatments(i.e.dry after-ripening,cold stratification and physical scarification).Important Findings Our results showed complex interactions between spatial and temporal dispersal.Right after dispersal,aerial seeds were more dormant than their subterranean counterparts,but this trend reversed with after-ripening,as seeds developed physical dormancy.Seeds of homocarpic plants germinated at higher percentages than those of their amphicarpic congeners and lost dormancy homogeneously with after-ripening.Conversely,amphicarpic seeds exhibited varied dormancy strategies modulated by both physiological and physical dormancy.These are expected to increase variation in emergence timing,providing multiple levels of diversifying bet-hedging.This strategy might be adaptive under highly unpredictable conditions by enabling plants to rely on historically favorable sites in good seasons without preventing spatial and temporal migration.

Experimental Investigation of Boiling Two-phase Flow Instability of Nitrogen in a Vertical Tube

Boiling flow instability of nitrogen in a vertical tube is experimentally investigated in the present study. The experiments reveal that pressure has a significant effect on the characteristics of the heat flux-mass flux type boiling flow instability.First.the pressure has strong effects on both the developing time and the fluctuation amplitude.Especially increasing pressure leads to decrease the fluctuating amplitude of mass flux.Then,the mass flux evolving curves under different pressures feature out a shape like a leaf.The characteristics of the heat flux-mass flux type boiling flow instability under lower pressure are very complicated,however,with increasing pressure,this type of instability is gradually suppressed.

Numerical Simulation and Experiment Analyses for the Gas-liquid Two-phase Vortex Pump

Based on the gas-liquid two-phase mixture transportation test, the k-c-A; turbulence model was applied to simulate the two-phase turbulent flow in a vortex pump. By comparing the simulation and experiment results, inner flow features were revealed. The bubbles in the channel distribute mainly at the pressure side of the blades, and the aggregation degree of the bubbles is enhanced with an increase in inlet gas volume fraction. Experimental results indicate that the influence of the gas phase on vortex pump performance is small when the gas volume fraction is less than 10%. When the gas volume fraction contiuuously increases to 15%, the characteristic curves abruptly drop due to the gas blocking phenomenon.

Experimental Observation of Two Phase Flow of R123 Inside a Herringbone Microfin Tube

Vapor-liquid two phase flow behavior of R123 inside herringbone microfin tubes has been studied. Herringbone microfin tube is a kind of internally finned tube in which microfins are installed inside the tube where the microfins form multi-V-shape in flow direction. For the present experiment three different types of herringbone microfin tubes with helix angle B = 8, 14 and 28 are used. Experimental observations showed how flow diverges and converges inside herringbone microfin tube due to fin arrangement. The effect is more remarkable for larger helix angle. From the measurements of the cross-sectional liquid flow rate distribution, the liquid removal and collection and the entrained droplet are discussed. Quantity of liquid droplets is increased with increase of helix angle. The tube with helix angle B = 28 shows higher quantity of liquid droplets than others.

Experimental Study on the Condensation of a Thermosyphon by Electrical Capacitance Tomography

The study on the condensation and the two-phase flow pattern in the condensation section is important to understand the operating mechanisms in a thermosyphon. In this paper, a new electric capacitance tomography(ECT) sensor was designed for the visualization measurement in a liquid by removing the shielding case and sealing with insulating hydrophobic material. It was successfully used to measure the condensation process in a thermosyphon under different operating temperatures. The thermosyphon was made of silica glass, and alcohol was used as a working fluid. The alcohol vapor was cooled to condense through the heat convection with the cooling water. The operating temperature was controlled by a heater with different power outputs. The experimental results show that the alcohol vapor condensed in stripes and unevenly on the wall surface at a low operating temperature. The liquid bridge will be formed periodically at the operating temperature of 90?C, and the time interval between two liquid bridges will be shorter with the increase of the operating temperature. At 117?C or even higher operating temperatures, the complete liquid bridge cannot be formed sometimes due to the difference of the growth rate of the surface wave around the circumference.

At the Nexus of New Challenges： China＇s Leadership Change and Cross-Strait Relations

China＇s 2012 leadership change revealed signs of factional divide at the top level. The elitist/princeling faction has outnumbered the populist faction. Princelings have better and stronger ties with the military, which tends to have a more hawkish view regarding any potential Taiwan independence. In Taiwan, changing social experiences have created a new Taiwan Residents identity, which is dif- ferent from that of the Chinese. People in Taiwan are increasingly thinking of themselves as Taiwan Residents instead of Chinese. On the mainland, Chinese popular nationalism has been on the rise, as anti-Taiwan independence remains one of the most nationalistic issues. When the forces of new identity and nationalism meet each other, a diverging path regarding the future of Taiwan is being created. Moreover, China＇s economic and military power continues to rise, giving China more confidence. I argue that the overall effect is that China＇s new leadership will increasingly have the capability to act tougher against any potential Taiwan Residents independence. The potential need to act tougher with Taiwan may be beyond the desire and control of Chinese elites due to the rise of popular nationalism in China and the leadership＇s need to maintain internal legitimacy and survival.