中国金融将进入“大爆炸”时期

中国人民大学金融与证券研究所所长吴晓求称,中国金融业将进入一个'大爆炸'时期。金融'大爆炸'将推进国家快速发展,这在很多发达国家已经出现过,而中国正在积蓄这种'大爆炸'所需的能源。

奥伯斯佯谬浅析

给出满足宇宙学原理的宇宙模型中计算星体视光度的一般公式 ,作为特例 ,导出“稳恒态”和“大爆炸”模型中星体视光度的表达式 ,结果表明这些模型是可以避免奥伯斯佯谬的 .

进化模式将是胜利者

本文的目的在于指出那些一般经济学家(也包括本章作者)都认同的和不认同的论点,同时解释形成这些论点的原因。同时,作者通过明确提出和回答一些问题,来证明目前政策争论中使用的一些主流词汇实际上含义不明,传统的转轨战略中的一些基本政策工具,实际上并没有很好地支持转轨战略,反倒对政策目标起了颠覆作用。

Comparative experimental study on inhibiting gas explosion using ABC dry powder and diatomite powder

Using a 20 L spherical explosion suppressing test system, the largest gas explosion pressure and maximum pressure rising rate with additives of ultra-fine ABC dry powder and diatomite powder were tested and compared, and the explosion suppression effect of the two kinds of powder was analyzed. Experimental results show that both powders can suppress gas ex- plosion and ABC dry powder is superior to diatomite powder. Adding two powders under the same experimental conditions, when methane concentration is 7.0%, the maximum explosion pressure decreased 39% and 4%, respectively, while the rising rate of the maximum pressure decreased 80% and 53%, respectively. When methane concentration is 9.5%, the maximum ex- plosion pressure decreased 14% and 12%, respectively, the rising rate of maximum pressure decreased 62% and 27%, respec- tively, the maximum explosion pressure decreased 23% and 18%, respectively, while the rising rate of the maximum pressure decreased 77% and 70%, respectively. When methane concentration is 12.0%, the explosion suppression effect of ultra-fine ABC dry powder is not affected by the methane concentration, and the explosion suppression effect of diatomite powder under high methane concentrations is more obvious.

Mechanism research of gas and coal dust explosion

Combined with the experimental results from the large tunnel of the ChongqingResearch Institute,the mechanism of gas and coal dust explosion was studied.Someconcepts about gas and coal dust explosion were introduced such as the form conditionand influential factors.Gas and coal dust explosion propagation was researched and thelifting process of coal dust was simulated.When an explosion occurred due to great mixtureof gas and air,the maximum explosion pressure appeared in the neighborhood of theexplosion source point.Before it propagated to the tunnel of the deposited coal dust,themaximum explosion pressure appeared to be in declining trend.Part of the energy waslost in the process of raising the deposited coal dust through a shock wave,so the maximumexplosion pressure was smallest on the foreside of the deposited coal dust sector.On the deposited coal dust sector,the explosion pressure rapidly increased and droppedoff after achieving the largest peak value.Because of coal dust participation in the explosion,the flame velocity rose rapidly on the deposited coal dust and achieved a basic stablevalue;coal dust was ignited to explode by initial laminar flame,and the laminar flametransformed into turbulent flame.The turbulence transformed the flame fold into a funnelshape and the shock wave interacted with the flame,so the combustion rate rose and thepressure wave was further enhanced.The regeneration mechanism between the flamecombustion rate and the aerodynamic flowing structure achieved the final critical state forforming the detonation.

Mechanical Model of Domestic Gas Explosion Load

With the increase of domestic gas consumption in cities and towns in China,gas explo-sion accidents happened rather frequently,and many structures were damaged greatly.Rational physical design could protect structures from being destroyed,but the character of explosion load must be learned firstly by establishing a correct mechanical model to simulate vented gas explo-sions.The explosion process has been studied for many years towards the safety of chemical in-dustry equipments.The key problem of these studies was the equations usually involved some ad-justable parameters that must be evaluated by experimental data,and the procedure of calculation was extremely complicated,so the reliability of these studies was seriously limited.Based on these studies,a simple mathematical model was established in this paper by using energy conservation,mass conservation,gas state equation,adiabatic compression equation and gas venting equation.Explosion load must be estimated by considering the room layout; the rate of pressure rise was then corrected by using a turbulence factor,so the pressure-time curve could be obtained.By using this method,complicated calculation was avoided,while experimental and calculated results fitted fairly well.Some pressure-time curves in a typical rectangular room were calculated to inves-tigate the influences of different ignition locations,gas thickness,concentration,room size and venting area on the explosion pressure.The results indicated that: it was the most dangerous con-dition when being ignited in the geometry centre of the room; the greater the burning velocity,the worse the venting effect; the larger the venting pressure,the higher the peak pressure; the larger the venting area,the lower the peak pressure.

Experimental study on prediction model for maximum rebound ratio

The proposed prediction model for estimating the maximum rebound ratio was applied to a field explosion test, Mandai test in Singapore. The estimated possible maximum peak particle velocities(PPVs) were compared with the field records. Three of the four available field-recorded PPVs lie exactly below the estimated possible maximum values as expected, while the fourth available field-recorded PPV lies close to and a bit higher than the estimated maximum possible PPV. The comparison results show that the predicted PPVs from the proposed prediction model for the maximum rebound ratio match the field-recorded PPVs better than those from two empirical formulae. The very good agreement between the estimated and field-recorded values validates the proposed prediction model for estimating PPV in a rock mass with a set of joints due to application of a two dimensional compressional wave at the boundary of a tunnel or a borehole.

Numerical study on maximum rebound ratio in blasting wave propagation along radian direction normal to joints

In the process of 2-D compressional wave propagation in a rock mass with multiple parallel joints along the radian direction normal to the joints, the maximum possible wave amplitude corresponding to the points between the two adjacent joints in the joint set is controlled by superposition of the multiple transmitted and the reflected waves, measured by the maximum rebound ratio. Parametric studies on the maximum rebound ratio along the radian direction normal to the joints were performed in universal distinct element code. The results show that the maximum rebound ratio is influenced by three factors, i.e., the normalized normal stiffness of joints, the ratio of joint spacing to wavelength and the joint from which the wave rebounds. The relationship between the maximum rebound ratio and the influence factors is generalized into five charts. Those charts can be used as the prediction model for estimating the maximum rebound ratio.

Study on explosion process of methane-coal dust mixture

The experimental system of 10 m3 large-scale multiphase combustion explosion tank was used for research into the explosion development process under the ignition conditions of methane-coal dust-air mixture, and the overpressure development processes of the mixture at different distances were obtained. For the methane-coal dust-air mixture with an equivalence ratio of 1, the explosion pressure and pressure rise rate reached their maximum under a methane concentration of 8% and a coal dust concentration of 25 g/m3, while the maximum explosion pressure and pressure rise rate both occurred 0.5 m away from the ignition point under a methane concentration of between 4.5% and 8%, and a coal dust concentration of between 25 g/m3 and 1 O0 g/m3. Moreover, the greater the explosion intensity of mixture, the closer the occurrence location of maximum overpres- sure was to the ignition source.

Spatial Distribution and Seasonal Variation of Explosive Cyclones over the North Atlantic

Spatial distribution and seasonal variation of explosive cyclones （ECs） over the North Atlantic from October 2000 to September 2016 are investigated using the reanalysis data of Final Analysis （FNL）, Mean Sea Level Pressure （MSLP） and Optimum Interpolation （OI） Sea Surface Temperature （SST） provided by the National Centers for Environmental Prediction （NCEP）, the European Centre for Medium-Range Weather Forecasts （ECMWF） and the National Oceanic and Atmospheric Administration （NOAA）, respectively. Considering the meridional distribution of ECs and 10-m height wind field associated with the ECs, the definition of EC given by Yoshida and Asuma （2004） is modified. It is found that the ECs occurred mainly in four regions during winter season, namely, North America continent （NAC）, the Northwest Atlantic （NWA）, the North-centzal Atlantic （NCA）, and the Northeast Atlantic （NEA）, depending on the spatial distribution of EC＇s maximum deepening rate of central sea level pressure （SLP）. According to the magnitude of maximum deepening rate, the trend of EC numbers basically decrease with the increase of EC＇s maximum deepening rate over the North Atlantic during the whole time period. Over the North Atlantic basin, for monthly statistics, the NEA, NCA, and NWA cyclones occur mainly in December, from December to March, and from January to February, respectively. NWA, NCA and NEA cyclones in winter are associated with low-level barocliincity, both low-level baroclinicity and upper-level forcing and upper-level forcing, respectively. According to monthly variation, the averaged maximum deepening rate of central SLP firstly increases and then decreases from July to June. Overall, the distribution of ECs＇ tracks is basically in the southwest-northeast direction. During winter circulation stage （from October to May）, the averaged maximum deepening rate of central SLP and the averaged minimum central SLP of ECs decrease, and the averaged explosive-deepening duration of ECs shortens from west to east over the North Atlantic basin. During summer circulation stage （from June to September）, the number of ECs is far less than that of winter circulation. NCA cyclones are the lowest in the average minimum central SLP of ECs, and the longest in the average explosive-deepening duration ofECs. NEA cyclones are the strongest in the average maximum deepening rate of central SLR

Structures and Evolutions of Explosive Cyclones over the Northwestern and Northeastern Pacific

In this study, the structures and evolutions of moderate(MO) explosive cyclones(ECs) over the Northwestern Pacific(NWP) and Northeastern Pacific(NEP) are investigated and compared using composite analysis with cyclone-relative coordinates. Final Operational Global Analysis data gathered during the cold seasons(October–April) of the 15 years from 2000 to 2015 are used. The results indicate that MO NWP ECs have strong baroclinicity and abundant latent heat release at low levels and strong upper-level forcing, which favors explosive cyclogenesis. The rapid development of MO NEP ECs results from their interaction with a northern cyclone and a large middle-level advection of cyclonic vorticity. The structural differences between MO NWP ECs and MO NEP ECs are significant. This results from their specific large-scale atmospheric and oceanic environments. MO NWP ECs usually develop rapidly in the east and southeast of the Japan Islands; the intrusion of cold dry air from the East Asian continent leads to strong baroclinicity, and the Kuroshio/Kuroshio Extension provides abundant latent heat release at low levels. The East Asian subtropical westerly jet stream supplies strong upper-level forcing. While MO NEP ECs mainly occur over the NEP, the low-level baroclinicity, upper-level jet stream, and warm ocean currents are relatively weaker. The merged cyclone associated with a strong middle-level trough transports large cyclonic vorticity to MO NEP ECs, which favors their rapid development.

Rhetorical Devices in Dialogues of The Big Bang Theory

This paper analyzes the effect of rhetorical devices, such as irony, sarcasm, parody, hyperbole, pun, antonomasia, etc., in dialogues of the American TV series The Big Bang Theory （2007） with an aim to help improve English learners＇ awareness and appreciation of rhetorical means in English-based literary works. Instances are cited with the use of such rhetoric means in the dialogue transcriptions. It is discovered that integrated use of a variety of rhetorical devices is a significant means for vivid and impressive characterization in literature. Such an analysis is a rewarding journey on either an academic or entertainment basis, and a process of discovery and learning that may particularly be well-received with EFL （English as a Foreign Language） learners

Explosive characteristics of nanometer and micrometer aluminum-powder

The explosive characteristics of aluminum powder have great significance in preventing and controlling aluminum-dust explosion accidents, especially the nano-aluminum powder. The explosion characteristics of 100 nm and 75 μm aluminum powders were investigated by using a 20 L spherical explosion cavity and a horizontal pipe whose cross-section area is 80 mm × 80 mm and length is 8 m. The results show that the maximum explosion pressure and its rising rate of 100 nm aluminum powder gradually increase with increasing concentration of aluminum-powder at the beginning. When aluminum-powder concentration is I kg/m3, the maximum explosion pressure reaches its maximum, and then gradually decreases. While when the concentration is 1.25 kg/m3, the maximum rate of pressure rise obtains its maximum, and then decreases. After 100 nm aluminum powder is exploded in pipes, the peak overpressure of blast wave first decreases and then increases to the maximum at a distance of 298 cm from the ignition source, and then gradually decreases. The most violent concentration is about 0.4 kg/m3 which is lower than 0.8 kg/m3 of 75 μm aluminum powder, so 100 nm aluminum powders are more easily exploded. The change laws of maximum explosion pressure, maximum rate of pressure rise and blast-wave peak overpressure of 100 nm aluminum powders with concentration are similar to those of 75 ktm aluminum powders, but these values are much higher than 75 Bm aluminum powders under the same concentration, so the aluminum-powders explosion of 100 nm will produce more harms. In the process of production, storage and transportation of aluminum powder, some relevant preventive measures can be taken to reduce the loss caused by aluminum-dust explosion according to nano-aluminum dust.

Characteristics of gas explosion flow fields in complex pipelines

The explosion flow field in five straight pipes with different diameters and one bending pipe selected from a domestic coal mine are studied by the method of numerical simulation. And the results show that,both in the straight and bending pipes, the pressure wave and velocity wave are accelerated by the rising of reaction rate. As the explosion progressed, with the temperature reaching approximately 3000 K, only one pressure wave and one reaction rate wave were observed, while several velocity waves were found.The larger diameter presented the highest relative pressure as well as the largest velocity increase and subsequent decrease inside the tube. The bent pipes caused both turbulence and kinetic energy to increase, resulting in the acceleration of the reaction rate. The burning time was 7.4% shorter than the burning time observed for the straight pipe. Based on these results, designing one explosion resistance device, and in the practical engineering applications, it was to be proved to meet the security requirements fully.

Meteorites Penetration into the Dense Layers of the Earth＇s Atmosphere： Physical Mechanism behind the Explosive Phenomena

This discussion paper is an attempt to consider new ideas about the nature of explosive phenomena of the meteorite bodies in the Earth＇s atmosphere. Authors attract approaches, based on the concepts of physics of combustion, explosion and detonation in order to explain the explosive collapse of the meteorite. Authors believe that the meteorite explosion may be the result of gas-detonation mechanism of overheated meteoric bodies explosive boiling-up （the ＂vapor explosion＂）, accompanied by the formation of a supersonic front of shock wave. The considered hypothesis regarding the role of the ＂vapor explosion＂ in geological disasters can be used to explain the mechanisms of explosive phenomena in Volcanology： （1） With respect to the description of nature of phreatic eruptions; （2） for interpretation of dynamic regularities of the volcano crater opening and the subsequent shock-wave emission of steam-gas ＂fountain＂ to a height of several kilometers with fragments of magma and rocks as a result of the ＂vapor explosion＂ of overheated magma mass under the dome of the volcano.

A股市场“泡沫”：内涵、衡量、形成机理及防范对策

股市“泡沫”的主要特征表现为股价短期内持续迅猛上涨、投资者非理性入市及股市剧烈波动。股市“泡沫”源于大量资金持续盲目涌入，但随着这些资金的回归理性，股市“泡沫”必然会破灭。我国股市的真实“泡沫”要大于名义“泡沫”。今后几年内，我国股市的“泡沫”还将继续增加，我们要未雨绸缪，防止股市“泡沫”破灭带来的危害，尤其是要防止国际游资对我国A股市场的冲击。