Characteristics of the pressure profile in the accelerator on the RF negative ion source at ASIPP

Neutral beam injection(NBI)systems based on negative hydrogen ion sources-rather than the positive ion sources that have typically been used to date-will be used in the future magnetically confined nuclear fusion experiments to heat the plasma.The collisions between the fast negative ions and neutral background gas result in a significant number of high-energy positive ions being produced in the acceleration area,and for the high-power long-pulse operation of NBI systems,this acceleration of positive ions back to the ion source creates heat load and material sputtering on the source backplate.This difficulty cannot be ignored,with the neutral gas density in the acceleration region having a significant impact on the flux density of the backstreaming positive ions.In the work reported here,the pressure gradient in the acceleration region was estimated using an ionization gauge and a straightforward 1D computation,and it was found that once gas traveled through the acceleration region,the pressure dropped by nearly one order of magnitude,with the largest pressure drop occurring at the plasma grid.The computation also revealed that the pressure drop in the grid gaps was substantially smaller than that in the grid apertures.

Effects of atomization parameters of dust removal nozzles on the de-dusting results for different dust sources

In order to obtain appropriate spray pressure and enhance the spraying and dust removal efficiency, various factors including the dust characteristics, nozzle spraying angle, effective spraying range, water consumption and droplet size are taken into account. The dust characteristics from different mines and atomization parameters of different pressure nozzles were measured. It was found that the internal pressure of coal cutters and roadheaders should be kept at 2 MPa, which could ensure large droplet size, large spraying angle and low water consumption and hence realizing a large-area covering and capture for large particle dusts. However, the external spray pressure should be kept at 4 MPa for smaller droplet size and longer effective spraying range, leading to effective dust removal in the operator zone. The spray pressure of support moving, drawing opening, and stage loader on a fully mechanized caving face and stage loader on a fully mechanized driving face should be kept at 8 MPa, under which the nozzles have long effective spraying range, high water flow and small droplet size for the rapid capture of instantaneous, high-concentration and small size dust groups. From the applications on the caving and driving faces in the coal mines, it is indicated that the optimization of spray pressure in different spraying positions could effectively enhance dust removal efficiency. Selecting appropriate nozzles according to the dust characteristics at different positions is also favorable for dust removal efficiency. With the selected nozzles under optimal pressures, the removal rates of both total dust and respirable dust could reach over70%, showing a significant de-dusting effect.

Au Microdisk-Size Dependence of Quantum Dot Emission from the Hybrid Metal-Distributed Bragg Reflector Structures Employed for Single Photon Sources

We investigate metallic microdisk-size dependence of quantum dot （QD） spontaneous emission rate and micro- antenna directional emission effect for the hybrid metM-distributed Bragg reflector structures based on a particular single QD emission. It is found that the measured photolumineseence （PL） intensity is very sensitive to the size of metMlic disk, showing an enhancement factor of 11 when the optimal disk diameter is 2μm and the numerical aperture of microscope objective NA=0.5. It is found that for large metal disks, the Purcell effect is dominant for enhanced PL intensity, whereas for small size disks the main contribution comes from plasmon scattering at the disk edge within the light cone collected by the microscope objective.

Analysis of water vapour flux between alpine wetlands underlying surface and atmosphere in the source region of the Yellow River

An underlying wetland surface comprises soil, water and vegetation and is sensitive to local climate change. Analysis of the degree of coupling between wetlands and the atmosphere and a quantitative assessment of how environmental factors influence latent heat flux have considerable scientific significance. Using data from observational tests of the Maduo Observatory of Climate and Environment of the Northwest Institute of Eco-Environment and Resource, CAS, from June 1 to August 31, 2014, this study analysed the time-varying characteristics and causes of the degree of coupling(Ω factor)between alpine wetlands underlying surface and the atmosphere and quantitatively calculated the influences of different environmental factors(solar radiation and vapour pressure deficit) on latent heat flux. The results were as follows:(1) Due to diurnal variations of solar radiation and wind speed, a trend developed where diurnal variations of the Ω factor were small in the morning and large in the evening. Due to the vegetation growing cycle, seasonal variations of the Ω factor present a reverse "U" trend. These trends are similar to the diurnal and seasonal variations of the absolute control exercised by solar radiation over latent heat flux. This conforms to the Omega Theory.(2) The values for average absolute atmospheric factor(surface factor or total) control exercised by solar radiation and water vapour pressure are 0.20(0.02 or 0.22) and 0.005(-0.07 or-0.06) W/(m2·Pa), respectively. Generally speaking, solar radiation and water vapour pressure deficit exert opposite forces on latent heat flux.(3) At the underlying alpine wetland surface, solar radiation primarily influences latent heat flux through its direct effects(atmospheric factor controls). Water vapour pressure deficit primarily influences latent heat flux through its indirect effects(surface factor controls) on changing the surface resistance.(4) The average Ω factor in the underlying alpine wetland surface is high during the vegetation growing season, with a value of 0.38, and the degree of coupling between alpine wetland surface and atmosphere system is low. The actual measurements agree with the Omega Theory. The latent heat flux is mainly influenced by solar radiation.

Research on the characteristics of noise source on heading face and noise propagation in mine laneway

Based on the complexity and dynamic random analysis of machine noise source in mine heading face, this article established the noise pressure mathematical model of noise propagation in mine laneway of different noise sources, carried out noise propagation numerical simulation in long space, and revealed noise propagation law of more radiated noise sources in the mine roadway. The results show that, under conditions that the total noise power is always the same, regardless of point source, surface noise source, or body noise source, the corresponding noise attenuation trend along the mine laneway and attenuation curve shape are basically the same. However, the attenuation velocity corresponding to complex stereo noise source is slower than single point source and the noise pressure value is higher than the single point source. The actual noise of measured values is close to the theoretical value or, say, there is little error for complex stereo noise source, whereas the error to single point source and surface noise is higher, respectively.

Research and application of thermal insulation effect of natural gas hydrate freezing corer based on the wireline-coring principle

Natural gas hydrate(NGH)holds great promise as a source of clean energy.It is critical for acquiring the largest possible in situ NGH core for NGH eigen features and resource assessment.However,the existing NGH coring technology has limitations,such as temperature increments,limited coring diameters,low coring rates,and complex coring structures.Therefore,this study designs and proposes an NGH freezing coring(NGHFC)method and verifies the freezing and coring capacities of the NGHFC method in laboratories and experimental wells.Results suggest that NGHFC shows good freezing and heat-retention properties.A freezing core heat transfer model is developed.According to the actual air temperature and operating time,the optimum initial temperature of the cold source can be determined using this model.The average coring rate of NGHFC can reach 77.86%.The research results will provide a new idea of coring gas hydrates.

The change of anterior segment parameters after cataract surgery in normal-tension glaucoma

AIM： To investigate the change of anterior chamber angle morphology and intraocular pressure （lOP） reduction after cataract surgery in patients with normal-tension glaucoma （NTG） using swept-source optical coherence tomography （SS-OCT）. METHODS： This prospective, comparative, observational study recruited patients into two groups. Group 1 was the control group including normal subjects except those with cataracts （cataract group, n=67 eyes of 67 patients）, and group 2 was NTG group including patients who were diagnosed with NTG and cataracts （n=43 eyes of 43 patients）, which were treated with phacoemulsification and intraocular lens implantation. Before surgery, and at postoperative 1 and 6too, anterior chamber angles were evaluated by SS-OCT under dark conditions using three- dimensional angle analysis scan protocol. Angle opening distance （AOD）, angle recess area （ARA）, and trabecular- iris surface area （TISA） at four quadrants （temporal, nasal, superior, and inferior） were calculated automatically by SS-OGT, after the observer marked scleral spurs. RESULTS： A total of 106 patients （54 males and 52 females） were enrolled in the study. Angle parameters, AOD, ARA, and TISA were increased after surgery in both groups. However, changes of angle parameters were only significant in group 2. In group 2, preoperative lOP was 13.2＋2.9 mm Hg, and postoperative lOP at 1 and 6mo were 10.5＋3.0 and 10.7＋2.8 mm Hg, respectively. In group 1, preoperative lOP was 12.42.8 mm Hg, and postoperative lOP at 1 and 6mo were 11.6＋2.5 and 12.0＋2.8 mm Hg, respectively. After cataract surgery, angle parameters changed significantly while IOP significantly reduced and was maintained in group 2 （P〈0.001）. The changes in angle parameters （＆AOD500, ATISAS00 at temporal; ＆AOD500, S, RA500 at nasal） were linearly correlated with postoperative IOP changes. CONCLUSION： Cataract surgery may have improved antedor chamber angle parameters and decreased lOP in NTG patients.

Focused electron beam transport through a long narrow metal tube at elevated pressures in the forevacuum range

We present here our investigations of the features of focused electron beam transport in free space at elevated pressures of a few pascals.We have explored the effect of the beam accelerating voltage,operating gas pressure,and magnetic focusing upon the trajectory of beam electrons in the crossover region,in particular on the beam convergence and divergence angles.It is shown that for the forevacuum pressure range of 2-5 Pa explored,a distinctive feature of the propagation of a focused electron beam with a current of up to 20 mA at an accelerating voltage of 10-20 kV is the difference in the angles of convergence(before the focus)and divergence(after the focus).Whereas at a low pressure of 2 Pa the divergence angle is smaller than the convergence angle,as the pressure increases the divergence angle increases and for pressures greater than 5 Pa the divergence angle is greater than the convergence angle.The results obtained were used in experiments on electron beam transport through a long narrow metal tube with a diameter of 5.8-9.2 mm and length of 10-30 cm.We show that for a 30 cm long tube of 7.5 mm diameter,the focused beam transmission can exceed 70%.

Self-calibration and algorithm of sample set of piezoresistive pressure sensors

Aiming at piezoresistive pressure sensors, this paper studies simulation of standard pressure by using benchmark current source and self-calibration of the sampling data characteristics. A data fusion algorithm for sample set is presented which transforms a surface problem into a curve fitting and interpolation problem. The simulation result shows that benchmark current source simulating pressure is successful and data fusion algorithm is effective. The maximum measurement error is only 0.098 kPa and maximum relative error is 0.92% at 0-45 kPa and -10-45~C.

Measurment of gas-liquid two-phase slug flow with a Venturi meter based on blind source separation

We propose a novel flow measurement method for gas–liquid two-phase slug flow by using the blind source separation technique. The flow measurement model is established based on the fluctuation characteristics of differential pressure(DP) signals measured from a Venturi meter. It is demonstrated that DP signals of two-phase flow are a linear mixture of DP signals of single phase fluids. The measurement model is a combination of throttle relationship and blind source separation model. In addition, we estimate the mixture matrix using the independent component analysis(ICA) technique. The mixture matrix could be described using the variances of two DP signals acquired from two Venturi meters. The validity of the proposed model was tested in the gas–liquid twophase flow loop facility. Experimental results showed that for most slug flow the relative error is within 10%.We also find that the mixture matrix is beneficial to investigate the flow mechanism of gas–liquid two-phase flow.

Investigation,Analysis,and Countermeasures of College Teachers'Psychological Pressure

Objective:This paper aims to explore the investigation,analysis,and countermeasures of the psychological pressure of college teachers.Method:From March 2023 to May 2023,3266 college teachers in our city were selected as the research objects,and the sources of their psychological stress were analyzed through a questionnaire survey.Results:In this paper,there were 500 cases of education and teaching pressure accounting for 15.31%,600 cases of research pressure accounting for 18.37%,1000 cases of professional title evaluation pressure accounting for 30.62%,and 1266 cases of life pressure accounting for 35.70%.Conclusion:The psychological pressure on teachers in colleges and universities in our city is relatively high,and this paper puts forward targeted countermeasures for this problem.

The minimization of non-equilibrium plasma source at high pressure

The density of plasma produced by atmospheric non-equilibrium plasma source is the function of en-ergy dissipation rate in ionization electric field and gas particles momentum.The experiment shows that the plasma density highly rises with the increasing of energy dissipation rate and gas particles momentum.When the energy dissipation rate of activation field is 2.18 Wh/m3 and the average gas particles momentum is 109×10-22 g·m/s,the air throughput of plasma source whose volume is only 2.5 cm3 can be up to 12 m3/h and the density of plasma can be up to 1010 cm-3.The research can develop a method of producing minitype plasma source which is low energy consumption but high ion concen-tration used for chemical industry,environmental engineering and military.

Diffraction of plane SV waves by a cavity in poroelastic half-space

This paper presents an indirect boundary integration equation method for diffraction of plane SV waves by a 2-D cavity in a poroelastic half-space.The Green＇s functions of compressive and shear wave sources are derived based on Biot＇s theory. The scattered waves are constructed using fictitious wave sources close to the boundary of the cavity, and their magnitudes are determined by the boundary conditions. Verification of the accuracy is performed by： （1） checking the satisfaction extent of the boundary conditions, （2） comparing the degenerated solutions of a single-phased case with well- known solutions, and （3） examining the numerical stability of the solutions. The nature of diffraction of plane SV waves around a cavity in a poroelastic half-space is investigated by numerical examples.

A DISCUSSION ABOUT THE ROLE OF THE WATER VAPOR SOURCE/SINK TERM IN CONTINUITY EQUATION OF NUMERICAL MODELS

At present, in numerical weather prediction models (e. g. [1] ), general circulation or climate models (e. g. [2, 3] ) or meso-scale models (e. g. [4, 5] ), the influence of the water vapor source/sink term (WVST) in the continuity equation (CE) of moist air has not been taken into account generally. Though Hansen et al. listed source and sink terms in the CE ( Eq. T2 ), they still neglected these terms in the approximate form employed in computations ( Eq. T6 ). In the real atmosphere there exist condensation and evaporation, sometimes strong condensation. In this note the role of the WVSTs in the CE and its related equations of numerical models and their influences on forecast results are discussed.

Cause Analysis of a Double-cyclone Type of Rainstorm Process with Easterly Wave

On the basis of comprehensive analysis on weather background and main influencing system of rainstorm formation,using NCEP reanalysis data,rainfall data of Shaoyang ground regional automatic station,a new generation of Doppler weather radar product information,etc.,high-altitude weather situation and physical formation mechanism of local double-cyclone type of rainstorm process with easterly wave in Shaoyang area on August 14,2016 were analyzed in detail,to find out prophase signal features which had indicating significance for rainstorm forecast. The results showed that:(1) the position of zonal subtropical high pressure in east-west direction was the necessary condition for the formation of easterly wave.(2) The rainstorm formation was closely related to double tropical depressions acting in the south of subtropical high pressure,and westward movement of easterly wave over 500 hPa and low-pressure inverted trough at low layer were main impact systems of the rainstorm.(3) Continuous flow of water vapor from the South China Sea to northwest was the source of water vapor required by this rainstorm.(4) Numerical prediction model products had certain guiding significance for forecasting the heavy precipitation,with important reference value.(5) Doppler radar products had strong forecasting ability in the nowcasting of rainstorm falling zone,which was an important measure of correcting forecast errors.

Interaction due to various sources in saturated porous media with incompressible fluid

The disturbance due to mechanical and thermal sources in saturated porous media with incompressible fluid for two-dimensional axi-symmetric problem is investigated.The Laplace and Hankel transforms techniques are used to investigate the problem.The concentrated source and source over circular region have been taken to show the utility of the approach.The transformed components of displacement,stress and pore pressure are obtained.Numerical inversion techniques are used to obtain the resulting quantities in the physical domain and the effect of porosity is shown on the resulting quantities.All the field quantities are found to be sensitive towards the porosity parameters.It is observed that porosity parameters have both increasing and decreasing effect on the numerical values of the physical quantities.Also the values of the physical quantities are affected by the different boundaries.A special case of interest is also deduced.

Analysis of Forecast Failure of a Regional Rainstorm in Qinghai

Based on the ground observation, ERA5 and other data, the regional rainstorm that occurred in northeastern Qinghai on the night of August 28, 2020 was analyzed. The results show that this precipitation occurred in the climate background of relatively high temperature, high humidity and extreme low pressure, and the precipitation process was divided into warm-area precipitation before the front and frontal precipitation, among which the warm-area precipitation was dominant, and it was a regional warm-area rainstorm. The global models, mesoscale models and forecasters as important operational reference all failed to make effective forecasts or prompts for the warm-area precipitation before the front in advance(24 or 12 h), the predicted precipitation was obviously small, and the predicted frontal precipitation by the models were obviously large. The western low-level meso-β-scale wind direction convergence system moving eastwards encountered the high-humidity area at the front of the meso-γ-scale wind speed convergence system to trigger this regional warm-area rainstorm. From the analysis of the mesoscale convergent system based on the vorticity budget equation, it is found that different terms played different roles in the process of warm-area rainstorm. The advective term dominated before the appearance of precipitation, which was favorable for the generation of mesoscale eddies. During the precipitation period, the torsion term and the convergence term were dominant. The torsion term was beneficial to the conversion of horizontal vorticity to vertical vorticity and the enhancement of precipitation intensity. Its maximum was generated 1-2 h earlier than the heavy precipitation. In the later period of precipitation, the convergence term was dominant, which was beneficial to the maintenance of precipitation. In the early stage of precipitation, the apparent heat source was located behind the apparent water vapor sink, which was conducive to the increase in the thickness of the heating column, and the precipitation intensity gradually increased. During the occurrence of heavy precipitation, the apparent heat source and the apparent water vapor sink basically coincided, and the latent heat released by condensation strengthened the upward movement, so that precipitation intensity increased. In this process, the water vapor mainly came from the southeast of the plateau(southwest airflow), followed by the plateau slope area(southeast airflow). During this regional warm-area rain that was wrongly predicted, the extreme minimum pressure, the torsional term in the vorticity budget equation and the abnormal water vapor transport have certain indications for the warm-area rainstorm.

Employment should top crisis agenda

The global financial crisis has taken a toll on China’s economy and employment.Due to shrinking exports,jobs have been slashed and difficulties have arisen in export-oriented manufacturing,labor-intensive industries and small and medium-sized enterprises(SMEs)in China’s coastal regions.In this context,employment should be our policy target, and counter-shock and counter-cyclical policies should be integrated.

Pressure Tolerant Power Electronics： IGBT Gate Driver for Operation in High Pressure Hydrostatic Environment

Abstract： This paper presents results from an on-going research project on pressure tolerant power electronics at SINTEF Energy Research, Norway. The driving force for this research is to enable power electronic components to operate in pressurized dielectric environment. The intended application is the converters for operation down to 3,000 meters ocean depth, primarily for subsea oil and gas processing. The paper focuses on the needed modifications to a general purpose gate driver for IGBT （insulated gate bipolar transistors） that will give pressure tolerance. Adaptations and modifications of the individual driver components are presented.The results from preliminary testing are promising, which shows that the considered adaptations give feasible solutions.

非均质气藏井间地层压力计算方法及应用

中国陆相沉积气藏储层普遍存在非均质性,常规地层压力计算方法具有很大局限性,难以准确评价井间地层压力。本文以均质地层中的点源解为基础,采用边界元思想,建立了一种可用于非均质气藏井间地层压力计算的半解析方法。基本思想是将非均质储层进行分块处理,分别建立单个均质区域的压力方程,通过各区交界面处的压力和流量连续条件,将各区压力方程耦合求解,并将求解结果回代至单个区域的压力方程,从而计算地层中任意一点的压力。建立了理论模型,对所提出的井间地层压力计算方法进行了数值验证,并将其应用于长庆靖边气田某区块。结果表明,本文所建立的非均质气藏井间地层压力半解析计算方法与数值模拟计算结果相吻合,仅在早期和井筒附近存在微小差异;半解析方法能很好地预测实际气藏中单井及井间的地层压力变化,与实测数据趋势一致。