Novel concept of tailorable magnetic field and electron pressure distribution in a magnetic nozzle for effective space propulsion

Magnetic nozzle appears to be a practical solution for prolonged space missions.For efficient handling of the spaceship,an in-flight solution to customize the thrust from the magnetic nozzle is essential.Here a new concept of three-thick coils system is proposed for tailoring the magnetic field in-flight in accordance with electron pressure distribution.The role of peak position of the pressure and its axial gradient is also uncovered for realizing higher thrust.About three-fold increase in thrust is observed when the electron temperature is raised to w2.5 times of its original value at the exit plane.The set-up is optimized for its best performance and efficient use in the electric space propulsion sector with thrust approaching 5 mN.In particular,this can contribute to the attitude control or the precision pointing of the spacecraft,the technology for removal of space debris and manipulating the ion momentum flux lost to a wall or unsteady laser produced plasma flow in a magnetic nozzle.

Space Charges Effect of Static Induction Transistor

The space charge effect (SCE) of static induction transistor (SIT) that occurs in high current region is systematically studied.The I V equations are deduced and well agree with experimental results.Two kinds of barriers are presented in SIT,corresponding to channel voltage barrier control (CVBC) mechanism and space charge limited control (SCLC) mechanism respectively.With the increase of drain voltage,the gradual transferring of operational mechanism from CVBC to SCLC is demonstrated.It points out that CVBC mechanism and its contest relationship with space charge barrier makes the SIT distinctly differentiated from JFET and triode devices,etc.The contest relationship of the two potential barriers also results in three different working regions,which are distinctly marked and analyzed.Furthermore,the extreme importance of grid voltage on SCE is illustrated.

Fieldwork Test Research of the Impact on Building Physical Environment on Six Types of Atrium Space in Cold Climates

Since the research on verification to passive design strategies in sustainable building is at the initial stage,and its test method and verification conclusion are not scientific enough to validate,this paper proposes the necessity of building physical environmental monitoring to quantitative optimization of passive strategies efficiency from the perspective of architecture design and building environment. Adopting comparative research method,this research chooses six types of atrium space in cold climate in China as a prototype,focusing on building physical environmental performance difference in and between atrium and building main space. Spatial parameters of the atrium space will be divided into four factors: spatial geometry,interfacial properties,internal and external related categories. With subdividing these four factors into sub-factors,this paper makes crosscomparison among the sub-factors to clarify passive strategies effectiveness in atrium. Data comparison analysis shows that Winter atrium passive strategy in cold regions from traditional view is not obvious in practical application,and test data need to be stratified refined in atrium design in case of optimizing passive strategy from building prototype perspective.

Design of Electrostatic Focusing for Space Electron Beam Welding Gun

The developmental situation of space welding technology at home and abroad is introduced. Then it is put forward that the designing scheme and the computer aided design （CAD） method of main single lens of the domestic space electron beam gun with equal-diameter three-cylinder simple lens, and the flowing-pipe way of calculating the space charge density of the main lens area ,in the electron gun is analyzed. The parameters calculation of the focusing system is completed through Language C utilizing computer programming and a satisfying result is gotten. The result shows that the calculation and design method are correct ： the dispersed focusing current of electron beam is less, the beam section is less in the deflected magnetic field, the minimal radius of beam spot on the workpiece is about 0.65615mm, and all these can meet the requirements of the space welding and cutting.

Research on Two Types of Buffer Zone Impact on Surrounding Office Space Environment in Winter in Cold Climate Zone—a Fieldwork in Architectural Design Institute Building of Tsinghua University,Beijing

Building buffer zone space is not only one of essential approaches for better mental quality of interior building space, but also an important factor that may influence interior thermal comfort and energy consumption. This study aims to analyze regulative advantages of buffer zone to the surrounding functional spaces. Based on a fieldwork test in a typical office building in cold climate zone in Beijing,China,the monitor data show interior physical performance in the Winter. The research selects two types of different buffer zones in the same building. One is a south-faced greenhouse which has large dimension with plenty of vegetation,and the other is a simple atrium in the middle of five floor building with mount of skylights. The factors and their influence to surrounding functional spaces and the whole building are found out from the comparisons of collected data by floor to floor monitor test on both buffer zones at the same time. The comparisons of two types of buffer zones conclude that the greenhouse is more effective to air quality regulation but not so clearly wellperformed to thermal buffering as expected due to the dominate active central heating in the Winter. This fieldwork test results for building performance can be helpful for both architects and engineers in the early phase of sustainable design.

Electron beam modeling and analyses of the electric field distribution and space charge effect

In electron beam technology, one of the critical focuses of research and development efforts is on improving the measurement of electron beam parameters. The parameters are closely related to the generation, emission, operation environment, and role of the electron beam and the corresponding medium. In this study, a field calculation method is proposed, and the electric field intensity distribution on the electron beam’s cross-section is analyzed. The characteristics of beam diffusion caused by the space charge effect are investigated in simulation, and the obtained data are compared with the experiment. The simulation demonstrated that the cross-sectional electric field distribution is primarily affected by the electron beam current, current density distribution, and electron beam propagation speed.

Space debris tracking based on fuzzy running Gaussian average adaptive particle filter track-before-detect algorithm

Although tracking with a passive optical telescope is a powerful technique for space debris observation, it is limited by its sensitivity to dynamic background noise. Traditionally, in the field of astronomy, static background subtraction based on a median image technique has been used to extract moving space objects prior to the tracking operation, as this is computationally efficient. The main disadvantage of this technique is that it is not robust to variable illumination conditions. In this article, we propose an approach for tracking small and dim space debris in the context of a dynamic background via one of the optical telescopes that is part of the space surveillance network project, named the Asia- Pacific ground-based Optical Space Observation System or APOSOS. The approach combines a fuzzy running Gaussian average for robust moving-object extraction with dim-target tracking using a particle- filter-based track-before-detect method. The performance of the proposed algorithm is experimentally evaluated, and the results show that the scheme achieves a satisfactory level of accuracy for space debris tracking.

Quantitative evaluation of space charge effects of laser-cooled three-dimensional ion system on a secular motion period scale

In this paper,we introduce a method of quantitatively evaluating and controlling the space charge effect of a lasercooled three-dimensional（3 D） ion system in a linear Paul trap.The relationship among cooling efficiency,ion quantity,and trapping strength is analyzed quantitatively,and the dynamic space distribution and temporal evolution of the 3 D ion system on a secular motion period time scale in the cooling process are obtained.The ion number influences the eigen-micromotion feature of the ion system.When trapping parameter q is ～ 0.3,relatively ideal cooling efficiency and equilibrium temperature can be obtained.The decrease of axial electrostatic potential is helpful in reducing the micromotion heating effect and the degradation in the total energy.Within a single secular motion period under different cooling conditions,ions transform from the cloud state（each ion disperses throughout the envelope of the ion system） to the liquid state（each ion is concentrated at a specific location in the ion system） and then to the crystal state（each ion is subjected to a fixed motion track）.These results are conducive to long-term storage and precise control,motion effect suppression,high-efficiency cooling,and increasing the precision of spectroscopy for a 3 D ion system.

Definition and expression of non-symmetric physical properties in space for uniaxial crystals

The anisotropic physical property is the most noteworthy feature of crystals.In this paper,the subscript change method is used to analyze the sign changes of different tensors describing physical properties in uniaxial crystals.The distribution of some physical properties in special point groups exhibits non-symmetry in eight quadrants,which should attract the attention of crystal research.The difference between the crystallographic and physical coordinate systems and the lack of crystal symmetry operations are considered to be the origins of the non-symmetry.To avoid ambiguities and difficulties in characterizing and applying crystal physical properties,eight quadrants in space should be clarified.Hence,we proposed the use of piezoelectric properties to define the positive direction of the optical coordinate axis prior to the research and applications of optical properties.

Space Charge Effects in CSL Gauge——with previously assumed charge distribution

The "cascade static lens （CSL） gauge" has a high sensitivity（S） because the emitted electrons repeat the go and back oscillation before they are received by the electrodes. (S=18.6 Pa-1 (2480 Torr-1 in a

Electromagnetic effects on the orbital motion of a charged spacecraft

This paper deals with the effects of electromagnetic forces on the orbital motion of a spacecraft. The electrostatic charge which a spacecraft generates on its surface in the Earth＇s magnetic field will be subject to a perturbative Lorentz force. A model incorporating all Lorentz forces as a function of orbital elements has been developed on the basis of magnetic and electric fields. This Lorentz force can be used to modify or perturb the spacecraft＇s orbits. Lagrange＇s planetary equations in the Gauss variational form are derived using the Lorentz force as a perturbation to a Keplerian orbit. Our approach incorporates orbital inclination and the true anomaly. The numer- ical results of Lagrange＇s planetary equations for some operational satellites show that the perturbation in the orbital elements of the spacecraft is a second order perturba- tion for a certain value of charge. The effect of the Lorentz force due to its magnetic component is three times that of the Lorentz force due to its electric component. In addition, the numerical results confirm that the strong effects are due to the Lorentz force in a polar orbit, which is consistent with realistic physical phenomena that occur in polar orbits. The results confirm that the magnitude of the Lorentz force depends on the amount of charge. This means that we can use artificial charging to create a force to control the attitude and orbital motion of a spacecraft.

Quadrupole-Linear Ion Trap Tandem Mass Spectrometry System for Clinical Biomarker Analysis

The accurate and efficient measurement of small molecule disease markers for clinical diagnosis is of great importance.In this study,a quadrupole-linear ion trap(Q-LIT)tandem mass spectrometer was designed and built in our laboratory.Target precursor ions were first selected in the quadrupole,and then injected,trapped,and fragmented simultaneously in the linear ion trap(LIT)to reduce the space charge effect,enrich the target product ions,and promote sensitivity.The targeted analytes were measured with selected reaction monitoring using a positive scan mode with electrospray ionization(ESI).Ions with a mass-to-charge ratio(m/z)ranging from 195 to 2022 were demonstrated.When scanning at 1218amu.s^(-1),unit resolution and an accuracy of higher than m/z 0.28 was obtained for m/z up to 2000.The dimensionless Mathieu parameter(q)value used in this study was 0.40 for collision-induced dissociation(CID),which was activated by resonance excitation.And an overall CID efficiency of 64%was achieved(activation time,50 ms).Guanidinoacetic acid(GAA)and creatine(CRE)were used as model compounds for small molecule clinical biomarkers.The limits of quantification were 1.0 and 0.2 nmol.L^(-1)for GAA and CRE,respectively.A total of 77 actual samples were successfully analyzed by the home-built ESI-Q-LIT tandem mass spectrometry system.The developed method can reduce matrix interference,minimize space charge effects,and avoid the chromatographic separation of complex samples to simplify the pretreatment process.This novel Q-LIT system is expected to be a good candidate for the determination of biomarkers in clinical diagnosis and therapeutics.

Differential Quadrature Method for Bending Problem of Plates with Transverse Shear Effects

A differential quadrature (DQ) method for orthotropic plates was proposed based on Reddy' s theory of plates with the effects of the higher-order transverse shear deformations. Wang-Bert's DQ approach was also further extended to handle the boundary conditions of plates. The computational convergence was studied, and the numerical results were obtained for different grid spacings and compared with the existing results. The results show that the DQ method is fairly reliable and effective.

Physical design and cooling test of C-band standing wave accelerating tube

The physical design and cooling test of a C-band 2MeV standing wave （SW） accelerating tube are described in this paper. The designed accelerating structure consists of 3-cell buncher and 4-cell accelerating section with a total length of about 163mm, excited with 1MW magnetron. Dynamic simulation presents that about 150mA beam pulse current and 30% capture efficiency can be achieved. By means of nonlinear Gauss fit on electron transverse distribution, the diameter of beam spot FWHM （full width at half maximum of density distribution） is about 0.55mm. Cooling test results of the accelerating tube show that frequencies of cavities are tuned to 5527MHz and the field distribution of bunching section is about 3：9：10.

Size-dependent behaviors of viscoelastic axially functionally graded Timoshenko micro-beam considering Poisson effects

A size-dependent continuum-based model is developed for the functionally graded(FG)Timoshenko micro-beams with viscoelastic properties,in which material parameters vary according to the power law along its axial direction.The size effect is incorporated by employing the modified couple stress theory and Kelvin-Voigt viscoelastic model,so that viscous components are included in the stress and the deviatoric segments of the symmetric couple stress tensors.The components of strain,curvature,stress and couple stress are formulated by combining them with the Timoshenko beam theory.Based on the Hamilton principle,the governing differential equations and boundary conditions for the micro-beam are expressed with arbitrary beam section shape and arbitrary type of loads.The size effect,FG effect,Poisson effect,and the influence of the beam section shape on the mechanical behaviors of viscoelastic FG micro-beams are investigated by taking the simply supported micro-beam subjected to point load as an example.Results show that the size effect on deflection,normal stress and couple stress are obvious when the size of the micro-beam is small enough,and the FG effects are obvious when the size of the micro-beam is large enough.Moreover,the Poisson ratio influences the size effect significantly and the beam section shape is also an important factor influencing the mechanical behavior of the micro-beam.

Microscopic oil occurrence in high-maturity lacustrine shales:Qingshankou Formation,Gulong Sag,Songliao Basin

Occurrence and mobility of shale oil are prerequisites for evaluating shale oil reserves and prioritizing exploration targets,particularly for heterogeneous lacustrine shales.The Qingshankou Formation in the Gulong Sag,Songliao Basin is a classic lacustrine pure shale reservoir that contains abundant shale oil resources.The predicted geological reserves of the shale are 1.268×10^(9) t.In this study,field emission scanning electron microscope(FE-SEM),the modular automated processing system(MAPS),pyrolysisgas chromatography(Py-GC),low-pressure nitrogen gas adsorption(LPNA),Soxhlet extraction,pyrolysis,and 2-D nuclear magnetic resonance(NMR)were integrated to describe the shale oil components,microscopic occurrence,mobility,and the effective pore size distribution.Meanwhile,the related controlling factors are discussed.The shale oil in the Qingshankou Fm exists dominantly in the matrix pores of the clay minerals,with small amounts distributed in the intergranular pores of terrigenous clastic grains,intercrystalline pores of pyrite,intragranular pores of ostracod shells,and micro-fractures.Shale oil is distributed in the pore spaces of variable sizes in different lithofacies.The clay mineral-laminated shales are characterized by the broadest range of pore size and largest volume of pore spaces with shale oil distribution,while the ostracod-laminated shales have limited pore spaces retaining oil.Furthermore,the proposed integrated analysis evaluates the shale oil molecules existing in two states:movable,and adsorbed oil,respectively.The result illustrates that movable oil takes up 30.6%e79.4%of the total residual oil.TOC,mineral composition,and pore structures of the shale joint together to control the states and mobility of the shale oil.TOC values are positively correlated with the quantities of shale oil regardless of the state of oil.The mineral components significantly impact the state of shale oil.Noticeable differences in the states of oil were observed following the changing types of minerals,possibly due to their difference in adsorption capacity and wettability.Clay minerals attract more adsorbed oil than movable oil.Felsic minerals generally decrease the occurrence of total and adsorbed oil.Carbonate plays a positive role in hydrocarbon retention of all the shale oil states.As for the pore structure,the average pore size exerts a critical impact on the total,movable,and adsorbed oil content.The total pore volume and specific surface area of shales play a principal role in controlling the total yields and amounts of adsorbed oil.This research improves the understanding of the occurrence characteristics and enrichment mechanisms of shale oil in terrestrial pure shales and provides a reference for locating favorable shale oil exploration areas.

Effects of Thickness on the Electrical Conductivity of Sputtered YSZ Film with Nanocrystalline Columnar Microstructure

In order to investigate the effect of the thickness on the electrical conductivity of yttriastabilized zirconia(YSZ) film, the nanocrystalline columnar-structured YSZ film with thickness of 0.67-2.52 μm was prepared by magnetron sputtering through controlling the deposition time. All the sputtered films with different thicknesses consist of the main phase of cubic YSZ as well as a small amount of monoclinic YSZ. The thicker films exhibit a typical columnar grain structure based on the fractured cross-sectional SEM observations. The average diameters of columnar grains increase from about 40 nm to 100 nm with the film thickness from 0.67 μm to 2.52 μm according to TEM analysis. The thinnest YSZ film with 0.67 μm thickness shows the highest apparent electrical conductivity in the four films in 400-800 ℃ due to the contribution from the highly conductive film/substrate interfacial region. On the other hand, the real electrical conductivities of YSZ films increase with film thickness from 0.67 μm to 2.52 μm after eliminating the contribution of the film/substrate interface. The increasing film thickness leads to the grain growth as well as the decrement in the volumetric fraction of the resistive columnar grain boundary and a consequent higher real electrical conductivity.

Microscale comprehensive evaluation of continental shale oil recoverability

This paper targets the shale oil reservoirs of middle to high maturity in four major basins of China,including the Permian Lucaogou Formation of the Jimsar Sag in the Junggar Basin,the Chang 73 Member of the Triassic Yanchang Formation in the Longdong area of the Ordos Basin,the Kong 2 Member of the Paleogene Kongdian Formation in Cangdong Sag of the Bohai Bay Basin,and the Qing 1 Member of the Cretaceous Qingshankou Formation in Changling Sag of the Songliao Basin.The key parameters of the shale oil reservoirs in the four basins,such as reservoirs effectiveness,oil content,crude oil movability,and fracability,have been revealed under identical experimental conditions using the same evaluation technical system,on the basis of technique development and integrated application of multi-scale spatial distribution depiction,effective connectivity calculation,movable oil assessment based on the charging effect,and simulation of fracture propagation during reservoir stimulation.This research overcomes insufficient resolutions of conventional analysis approaches and difficulties in quantitative evaluation,develops the evaluation method for resource recoverability of different types of shale oil,and gains insights into different types of shale oil via comparison.The results of experiments and comparative analysis show that there are significant differences in the endowment of continental shale oil resources in the four major basins in China.Among them,the Lucaogou Formation in the Junggar Basin has more effective shale reservoirs,the Chang 73 sub-member of the Ordos Basin has a comparatively good proportion of movable oil and the Kong 2 Member of the Bohai Bay Basin has the best fracability.These results can provide references and basis for choosing development plans and engineering techniques.

Sensitivity of the area method with mono isotopic fission chambers to reactivity changes in subcritical nuclear reactors

High-level waste is an important safety issue in the development of nuclear power.A proposed solution is the transmutation of waste in fast reactors.The exclusion of the risk of supercriticality by using subcritical reactors is currently under development.Controlling the subcriticality level in such reactors presents difficulties.A problem is posed by the so-called space effect observed when using in reactors many neutron detectors in different locations of the core and reflector.Reactivity obtained from measure-ments,for example,by the Sjo¨strand method,differs by nonnegligible values.Numerical corrections can partially improve this situation.The use of a monoisotopic fission chamber set,designed for a given reactor,when each chamber is intended for a specific position in the system,can improve the situation.A question arises about the sensitivity of the results to reactivity changes.This issue is analyzed by computer simulation for possible fissionable and fissile nuclides for the total range of control rod insertion,changes in reactor fuel enrichment,and fuel temperature.The tested sensitivity was satisfactory at most levels from several dozen to several hundred pcm.A case study was conducted using the VENUS-F core model.

NEW APPROACH TO EMULATE SEU FAULTS ON SRAM BASED FPGAS

Field Programmable Gate Arrays(FPGAs)offer high capability in implementing of complex systems,and currently are an attractive solution for space system electronics.However,FPGAs are susceptible to radiation induced Single-Event Upsets(SEUs).To insure reliable operation of FPGA based systems in a harsh radiation environment,various SEU mitigation techniques have been provided.In this paper we propose a system based on dynamic partial reconfiguration capability of the modern devices to evaluate the SEU fault effect in FPGA.The proposed approach combines the fault injection controller with the host FPGA,and therefore the hardware complexity is minimized.All of the SEU injection and evaluation requirements are performed by a soft-core which realized inside the host FPGA.Experimental results on some standard benchmark circuits reveal that the proposed system is able to speed up the fault injection campaign 50 times in compared to conventional method.