露天矿台阶爆破水炮孔深度测量流量尺技术

在露天矿台阶爆破和边帮预裂爆破中,炮孔深度测量工作对装药和控制爆破效果尤为重要。大多数深凹露天矿炮孔都存在孔内渗水情况,不同岩种不同水环境下炮孔孔底存在不同深度的矿泥或岩碴。矿山孔深测量一般采用加配重的测绳,到达孔底与否以绳是否变松通过测量员感观判别,误差较大。在连续快速多孔深测量时,测量含水含泥或含碴炮孔非常麻烦并且耗时,测绳易沾泥浸水不便清洗,甚至无法准确使用(比如冬季测绳沾水易冻硬)。描述了流量尺的结构组成,阐述了测量原理,建立了流量尺操作规范。露天台阶爆破中炮孔含泥碴含水时,将炮孔深度、炮孔含水高度、孔底泥碴深度和炸药陷入泥碴深度一次性在炮孔外流量尺上可读出。流量尺可反复使用,较测绳操作简单、数据准确、效率高,流量尺制作材料来源广泛、造价低廉,为爆破前装药作业提供准确的炮孔状态数据。

小型管道L型流量尺研究

农田灌溉管道管末出流为低压状态，其出流水点的运动轨迹为抛物线形状，根据水平射程Ｄ与竖直落距ｙ之间的关系，推出流量Ｑ与Ｄ和ｙ的函数关系，测出Ｄ值和ｙ值，算出Ｑ值。＃Ｄ和ｙ值分别标在尺子上，并将这两个尺子组合在一起形成Ｌ尺，对管道出流量进行测量，得出流量值，实现流量计算的目的。

等离子体破裂防护快速充气阀性能研究

托卡马克装置在放电过程中经常会发生破裂现象。破裂会对装置造成很大的危害。为了满足在实验先进超导托卡马克(EAST)装置上开展高压气体注入来缓解等离子体破裂研究的需求,基于涡流驱动的等离子体破裂防护快速充气阀已经在中科院等离子体物理研究所研制成功,该阀的成功研制为在EAST上面开展高压气体注入来缓解等离子体破裂研究提供了有效的工具。为了更加精确地测量快阀的响应时间并对其流量进行标定,搭建了基于磁栅尺的测试平台来测量快阀的响应时间,并编写了相应的测试程序,测试结果表明快阀得到触发信号后在0.5 ms时间内就可以开启,其流量可以从0～70000PaL之间方便进行调节,其响应时间及流量完全可以满足等离子体破裂防护对充气系统的要求。

Interannual variations in energy conversion and interaction between the mesoscale eddy field and mean flow in the Kuroshio south of Japan

Using 19-year satellite altimetric data, variations in the eddy kinetic energy, energy exchanges and interaction between the eddy fi eld and mean fl ow are discussed for the Kuroshio south of Japan. In the seasonal cycle, the eddy kinetic energy level is a minimum in December/January and a maximum in April/May. In addition to seasonal variations, the eddy kinetic energy undergoes interannual changes. The energy transfers mainly from the mean fl ow to the eddy fi eld in the Kuroshio south of Japan, and dominant energy exchanges mainly occur along the Kuroshio path south of Japan in each year from 1993 to 2011. In addition, there is often barotropic instability south of Honshu. Regarding interactions between the eddy fi eld and mean fl ow, cyclonic and anticyclonic accelerations are also found along the Kuroshio path and they fl ank each other. There is cyclonic acceleration always imposed on southeast of Kyushu, and anticyclonic acceleration dominates south of Honshu from 2001 to mid-2005. Reynolds stress is used to explain the dynamic process of energy exchange. Furthermore, lag-correlation and linear regression analysis show that variability of the energy conversion rate and Reynolds stress involve responses to eddy acceleration at two time scales. The enhanced eddy acceleration induces large Reynolds stress, and enhanced Reynolds stress or barotropic instability further enforces energy transfer from the mean fl ow to the eddy fi eld.

Temporal Variations of Water Discharge and Sediment Load of Huanghe River,China

Based on the data from gauging stations, the changes in water discharge and sediment load of the Huanghe （Yellow） River were analyzed by using the empirical mode decomposition （EMD） method. The results show that the periodic oscillation of water discharge and sediment load of the Huanghe River occurs at the interannual, decadal, and multi-decadal scales, caused by the periodic oscillations of precipitation, and E1 Nifio/Southern Oscillation （ENSO） af- fects water discharge by influencing precipitation distribution and contributes to periodic varations in precipitation and water discharge at interannual timescale. The water discharge and sediment load of the Huanghe River have decreased since the 1960s under the influence of precipitation and huamn activities, and human activities attribute more than precipitation to the reduction in the water discharge and sediment load, furthermore, water abstraction and water-soil conservation practices are the main causes of the decrease in water discharge and sediment load, respectively. The reduction in sediment load has directly impacted on the lower reaches of the Huanghe River and the river delta, causing considerable erosion of the river channel in the lower reaches since the 1970s along with River Delta changing siltation into erosion around 2000.

Long-term change in low-cloud cover in Southeast China during cold seasons

Southeast China has comparable stratus cloud to that over the oceans,especially in the cold seasons(winter and spring),and this cloud has a substantial impact on energy and hydrological cycles.However,uncertainties remain across datasets and simulation results about the long-term trend in low-cloud cover in Southeast China,making it difficult to understand climate change and related physical processes.In this study,multiple datasets and numerical simulations were applied to show that low-cloud cover in Southeast China has gone through two stages since 1980—specifically,a decline and then a rise,with the turning point around 2008.The regional moisture transport plays a crucial role in low-cloud cover changes in the cold seasons and is mainly affected by the Hadley Cell in winter and the Walker Circulation in spring,respectively.The moisture transport was not well simulated in CMIP6 climate models,leading to poor simulation of the low-cloud cover trend in these models.This study provides insights into further understanding the regional climate changes in Southeast China.

Spray Characteristics Study of Combined Trapezoid Spray Tray

The spray behaviors of the combined trapezoid spray tray(CTST) have a significant effect on the gas-liquid interface. In this paper, the spray process of CTST in a column, 570 mm in diameter, was experimentally investigated by using a high-speed camera, and a theoretical model of the average droplet size was established according to the unstable wave theory. The results demonstrated that gas velocity passing through the hole is the key factor affecting the spray angle, which increases gradually with an increase in the gas velocity. When the gas velocity exceeds 7.5 m/s, the spray angle becomes stable at around 55°. The average flow velocity of the liquid sheet at the spray-hole increases significantly with an increase in the gas velocity, and decreases slightly with an increase in the liquid flow rate; moreover, it increases from the bottom of spray hole upward to the top. The density of liquid drops distribution in the spray area can be described by the RosinRammler function. In addition, the liquid drops are mainly concentrated in the area of spray angle ranging from 20° to 40°, and they gradually become uniform with the increase in the gas velocity and the liquid flow rate. The average liquid drop size deceases with an increase in the gas velocity, and increases slightly with an increasing liquid flow rate. In the normal working range, the average liquid drop size is about 1.0 mm to 2.5 mm in diameter.

Effect of Zn/Mg ratio on cathodic protection of carbon steel using Al-Zn-Mg sacrificial anodes

Al-Zn-Mg alloys with different Zn/Mg mass ratios were evaluated as sacrificial anodes for cathodic protection of carbon steel in 3.5 wt.%Na Cl solution.The anodes were fabricated from pure Al,Zn and Mg metals using casting technique.Optical microscopy,SEM-EDS,XRD and electrochemical techniques were used.The results indicated that with decreasing Zn/Mg mass ratio,the grain size ofα(Al)and the particle size of the precipitates decreased while the volume fraction of the precipitates increased.The anode with Zn/Mg mass ratio>4.0 exhibited the lowest corrosion rate,while the anode with Zn/Mg mass ratio<0.62 gave the highest corrosion rate and provided the highest cathodic protection efficiency for carbon steel(AISI 1018).Furthermore,the results showed that the anode with Zn/Mg mass ratio<0.62 exhibited a porous corrosion product compared to the other anodes.

Anglo-American Special Relations： Atomic Diplomacy and the Canadian Dimension, 1942-1948

In recent years, we have entered a period of increasing impact of world affairs on national politics and international security. Notwithstanding, the present debate on national security and nuclear proliferation, Anglo-American ＂special relations＂ continue to be a subject of vigorous discussion influenced by the impact of new international emergencies as unstable countries acquire nuclear power and refuse ＂to reign＂ in their nuclear programmes （The Globe and Mail, 12 January 2012）. Along these lines the 71st anniversary of the Anglo-American Manhattan Project presents a unique opportunity to reappraise the Anglo-American wartime collaboration （or lack of） in atomic energy developments that resulted in the tragedy of nuclear weapons escalation. The Quebec Agreements of 1943-1944 were crafted to address the controlled flow of scientific information. But did this mean a trend toward more effective collaboration or toward greater American control of the atomic project？ This study explores the subject of nuclear politics from an unique vantage point of Anglo-Canadian and American-Canadian atomic diplomacy. In doing so, it will show that both the American and British atomic policy makers violated the Quebec Agreements. It seeks to demonstrate that （1） in the tangle of competition replacing cooperation, Canada was more important to the American atomic monopolists than the Anglo-AmcTican partnership, （2） the US-Canada Trade and Defence Agreements contributed to United States retaining exclusive control of the ＂absolute weapon＂, and that （3） their post-war nuclear energy agenda delayed Britain＇s atomic venture and isolated Britain from full participation in Arctic research. In practical terms, the emerging atomic policy in Washington boiled down to maintaining the American edge, come what may, and reducing British prestige in the post-war world. The article concludes by raising the question： did the United States, Britain, and Canada really work for atomic control？

Sediment Delivery across Multiple Spatio-temporal Scales in an Agriculture Watershed of the Chinese Loess Plateau

There is a consensus that sediment delivery ratio in the Chinese Loess Plateau is close to 1at the inter-annual timescale. However, little information is available about the sediment delivery at finer timescales. We evaluated the sediment delivery from plots to watersheds at the event or intra-annual, annual, and inter-annual timescales within the Wudinghe river basin, a 30,261 km2 basin in the Loess Plateau. We calculated the ratio of sediment output to sediment input and presented the temporal change of the channel morphology to determine whether sediment deposition occurs.Although a single flood event frequently has a sediment yield exceeding 10,000 t km-2, sediment deposition rarely occurs except during some small runoff events(sediment yield < 5000 t km-2) or dry years(sediment yield < 10,000 t km-2) when moving from slopes up to the main channels of the Wudinghe River. This observation suggests a sediment delivery ratio close to 1 even at the event or intra-annual and the annual timescales, but not necessarily at the interannual timescale. Such a high sediment delivery ratio can be related to hyper-concentrated flows, which have very strong sediment transport capacity even at low flow strength. Because hyper-concentrated flows are well-developed in the whole Loess Plateau, a sediment delivery ratio close to 1 below the interannual timescale possibly remains true for other rivers in the Loess Plateau.

The Effect of Heating Direction on Flow Boiling Heat Transfer of R134a in Microchannels

This paper presents effects of heating directions on heat transfer performance of R134 a flow boiling in micro-channel heat sink. The heat sink has 30 parallel rectangular channels with cross-sectional dimensions of 500mm width 500mm depth and 30 mm length. The experimental operation condition ranges of the heat flux and the mass flux were 13.48 to 82.25 W/cm^2 and 373.3 to 1244.4 kg/m^2 s respectively. The vapor quality ranged from 0.07 to 0.93. The heat transfer coefficients of top heating and bottom heating both were up to 25 k W/m^2 K. Two dominate transfer mechanisms of nucleate boiling and convection boiling were observed according to boiling curves. The experimental results indicated that the heat transfer coefficient of bottom heating was 13.9% higher than top heating in low heat flux, while in high heat flux, the heat transfer coefficient of bottom heating was 9.9%.higher than the top heating, because bubbles were harder to divorce the heating wall. And a modified correlation was provided to predict heat transfer of top heating.

Performance and Flow Condition of Small-Sized Axial Fan and Adoption of Contra-Rotating Rotors

Small-sized axial fans are used as air coolers for electric equipments.But there is a strong demand for higher power of fans according to the increase of quantity of heat from electric devices.Therefore,higher rotational speed design is conducted,although it causes the deterioration of the efficiency and the increase of noise.Then the adoption of contra-rotating rotors for the small-sized axial fan is proposed for the improvement of the performance.In the present paper,the performance and the internal flow condition of the small-sized axial fan are shown as a first step of the research for the contra-rotating small-sized axial fan and the important points to apply contra-rotating rotors to the small-sized axial fan are discussed.Furthermore,the numerical flow analysis is conducted to investigate the performance of the contra-rotating small-sized axial fan and internal flow conditions and pressure distributions are clarified and the effect of contra-rotating rotors is considered.

Effects of bleed hole size on supersonic boundary layer bleed mass flow rate

The bleed hole diameter,depth,and boundary layer thickness are key design parameters of a supersonic bleed system.The evolution trend of single-hole bleed flow coefficient with the ratio of boundary layer thickness to bleed hole diameter and the ratio of bleed hole depth to diameter is investigated by numerical simulations under choking and non-choking conditions.The results show that the subsonic leading edge of the circular hole and the subsonic part of the boundary layer are the main factors causing lateral flow of the bleed hole.The effect of diameter on bleed mass flow rate is due to the viscous effect which reduces the effective diameter.The larger the ratio of displacement thickness to bleed hole diameter,the more obvious the viscous effect is.The depth affects bleed flow rate by changing the opening and closing states of the separation zone.When a certain depth is reached,the development of the boundary layer reduces the effective captured stream tube and thus reduces the bleed mass flow rate.The main objective of the study is to obtain the physical mechanism of the bleed hole size parameters affecting the bleed mass flow rate,and to provide theoretical guidance for the selection of the size of bleed holes in the design of a porous arrays bleed system in hypersonic inlets.

Applications and challenges for single-bacteria analysis by flow cytometry

Flow cytometry(FCM)is a powerful technique for single-bacteria analysis via simultaneous light-scattering and fluorescence measurements.By offering high-throughput,quantitative,and multiparameter analysis at the single-cell level,FCM has gained an increased popularity in microbiological research,food safety monitoring,water quality control,and clinical diagnosis.Here we will review the recent applications of flow cytometry in areas such as(1)total bacterial cell count,(2)bacterial viability analysis,(3)specific bacterial detection and identification,(4)characterization of physiological changes under environmental perturbations,and(5)biological function studies.Nevertheless,despite these widespread applications,challenges still remain for the detection of small sizes of bacteria and biochemical features that cannot be brightly stained via fluorescence.Recent improvement in FCM instrumentation will be discussed,and particularly the development of high sensitivity flow cytometry for advanced analysis of single bacterial cells will be highlighted.

On the rigidity of solitary mass-critical NLS in waves for the focusing dimensions d ≥2 Dedicated to the NSFC-CNRS Chinese-French summer institute on fluid mechanics in 2010

For the focusing mass-critical NLS iu, ＋ △u = --｜u｜u, it is conjectured that the only global nonscattering solution with ground state mass must be a solitary wave up to symmetries of the equation. In this paper, we settle the conjecture for H1 initial data in dimensions d = 2, 3 with spherical symmetry and d ≥ 4 with certain splitting-spherically symmetric initial data.

Breach mechanism and numerical simulation for seepage failure of earth-rock dams

In this study,a numerical model,which can capture the full process of the development of seepage passages,the collapse of dams and the failure due to overtopping,is proposed for earth-rock dams.The critical incipient velocity for the occurrence of seepage failure is derived by analyzing the forces acting on soil particles in the seepage passage.The sediment transport formula is proposed to simulate the erosion process and the evolution of breach within the dam.In this model,the grain size distribution,the compaction density and the strength of dam materials are reasonably accounted for.Furthermore,the influences of the direction of seepage paths,the slope of the dam and the velocity of water flow on the amount of erosion are also taken into consideration.The proposed model and the corresponding numerical programs are employed to simulate the development of breaches and discharge of two typical cases due to seepage failure.The development of breaches,the history of discharge and the peak flood flux predicted by the numerical models are rather comparable to the measured data,which confirms the validity of the proposed model and the feasibility of applying the model in evaluating the disaster consequences and preparing the emergency counter measurements in the case of dam collapse.