适用于圆筒形增益区的同轴四镜腔的失调分析

采用矩阵光学方法,对适用于可见光的圆筒形增益区同轴四镜腔中的腔镜因倾斜而产生的失调特性进行了分析,给出了相关计算公式。该四镜腔由同轴的一个复曲面全反镜和两个光学玻璃加工的透镜和一个平面输出镜组成。以He-Ne激光器为例,给出了数值计算结果,关键元件复曲面镜的失调对输出的影响较大。这为腔元件的加工以及腔镜的安装调试提供了参考。     

Determining the Optimal Contour of a Three-Dimensional Supersonic Jet Engine Outlet System

The problem of determining the optimal contour of a two-dimensional jet engine outlet system was solved in [1] using the direct method of the calculus of variations. In this study the method is developed for designing the optimal contour of a three-dimensional outlet system providing maximum thrust in a given direction.     

Properties and applications of cold supersonic gas jet

By analyzing the formation mechanism of a supersonic gas jet, a set of equations which describe the atomic beam properties were established. The influence of initial temperature, initial pressure, background gas pressure and pumping speed was discussed in detail. A simulation program was developed based on the equations, and the results under different initial conditions were obtained. The results are in good agreement with the experimental data, and suggest that, in order to get much smaller transverse momentum in collision experiments, it is necessary to lower the initial temperature and the initial pressure of the supersonic gas jet, together with increasing the pumping speed. These results are very instructive for construction of a new generation of cold supersonic gas jets.     

二元环形孔径全空间轴线上的衍射光强分布

运用Rayleigh-Sommerfeld衍射积分,详细推导了二元环形孔径全空间在轴光强分布公式.由于未作明显的近似,所得公式对衍射距离大于数倍入射波长的衍射空间都是有效的.计算并分析了这种孔径轴线上的光强分布情况.结果显示,它的最大调制深度是入射光强的16倍,比圆形孔径或环形孔径大4倍,近场的光学层析能力比远场的强.在很近场区,二元环形孔径的在轴光强分布对孔径结构比较敏感,这些特性使这种孔径在光子学和光纤光学的应用方面具有潜在的价值.     

Surface ionization detector with a supersonic free jet for gas chromatography some applications

A new design for a gas chromatographic surface ionization detector based upon hyperthermal positive surface ionization has been developed: There were two requirements: supersonic free jet nozzle and the high work function surface of Re-oxide. This detector, which is highly sensitive in response to all organic compounds, can be operated as an universal detector with an additional selectivity towards some species that have low ionization energy, but with selectivity to a much lesser degree than a conventional surface ionization detector. The minimum detectable amount of toluene is ca. 10⁻¹² g/s with a linearity greater than 10⁴. Some applications are demonstrated using three examples for the analysis of different formulations: (1), terpene mixture, (2), polycyclic aromatic hydrocarbon mixture and (3), alkyl alcohol mixture.     

Global entropy solutions to the compressible Euler equations in the isentropic nozzle flow for large data: Application of the generalized invariant regions and the modified Godunov scheme

We study the motion of isentropic gas in nozzles. This is a major subject in fluid dynamics. In fact, the nozzle is utilized to increase the thrust of rocket engines. Moreover, the nozzle flow is closely related to astrophysics. These phenomena are governed by the compressible Euler equations, which are one of crucial equations in inhomogeneous conservation laws.In this paper, we consider its unsteady flow and devote to proving the global existence and stability of solutions to the Cauchy problem for the general nozzle. The theorem has been proved in Tsuge (2013). However, this result is limited to small data. Our aim in the present paper is to remove this restriction, that is, we consider large data. Although the subject is important in Mathematics, Physics and engineering, it remained open for a long time. The problem seems to rely on a bounded estimate of approximate solutions, because we have only method to investigate the behavior with respect to the time variable. To solve this, we first introduce a generalized invariant region. Compared with the existing ones, its upper and lower bounds are extended constants to functions of the space variable. However, we cannot apply the new invariant region to the traditional difference method. Therefore, we invent the modified Godunov scheme. The approximate solutions consist of some functions corresponding to the upper and lower bounds of the invariant regions. These methods enable us to investigate the behavior of approximate solutions with respect to the space variable. The ideas are also applicable to other nonlinear problems involving similar difficulties.     

A THREE-DIMENSIONAL ELASTICITY SOLUTION FOR TWO-DIRECTIONAL FGM ANNULAR PLATES WITH NON-UNIFORM ELASTIC FOUNDATIONS SUBJECTED TO NORMAL AND SHEAR TRACTIONS

In the present paper, bending and stress analyses of two-directional functionally graded （FG） annular plates resting on non-uniform two-parameter Winkler-Pasternak founda- tions and subjected to normal and in-plane-shear tractions is investigated using the exact three- dimensional theory of elasticity. Neither the in-plane shear loading nor the influence of the two- directional material heterogeneity has been investigated by the researchers before. The solution is obtained by employing the state space and differential quadrature methods. The material proper- ties are assumed to vary in both transverse and radial directions. Three different types of variations of the stiffness of the foundation are considered in the radial direction： linear, parabolic, and sinu- soidal. The convergence analysis and the comparative studies demonstrate the high accuracy and high convergence rate of the present approach. A parametric study consisting of evaluating effects of different parameters （e.g., exponents of the material properties laws, the thickness to radius ratio, trends of variations of the foundation stiffness, and different edge conditions） is carried out. The results are reported for the first time and are discussed in detail.     

Assessment of gas thermodynamic characteristics on fluidic thrust vectoring performance: Analytical,experimental and numerical study

The cross injection in a supersonic flow is an issue encountered in several aerodynamic applications such as fuel injection in scramjet combustor, missile control, drag reduction and thrust vector control. In a recent work, an analytical model has been presented to calculate the fluidic thrust vectoring performance for a supersonic axisymmetric nozzle. The model is able to take into account both the injected gas thermodynamic properties and the geometrical nozzle characteristics. The analytical model has been successfully validated following the cold air flow experimental analysis, in the case of fluidic thrust vectoring applied to conical nozzle. The aim of this work is to show how far the injected gas thermodynamic properties, different from that of the nozzle main flow, could influence the fluidic thrust vectorization parameters.In this work, the experimental performance of the fluidic thrust vectoring concept, using numbers of gases as injectant, has been qualitatively and quantitatively analyzed. Schlieren visualization, force balance and wall pressure measurements were used in the case of a truncated ideal contour nozzle. The experimental results are compared to the numerical and analytical findings.Performance analysis are conducted and basic conclusions are drawn in terms of thermodynamic gas properties effect on the fluidic thrust vector system. The primary effect was related to the gas molecular weight and its specific heat ratio product. It is observed that for fixed injection conditions, the vectoring angle is higher when the injected gas molecular weight and specific heat ratio product is less than that of the primary gas. For a given mission of the launcher, it can be concluded that the mass of the embedded gas, used for the fluidic vectorization system, can be significantly reduced, depending on its molecular weight and specific heat ratio.     

High Efficiency Annular Denuder for Formaldehyde Monitoring

Abstract

A practical and correct methodology for evaluating CH₂O in air without sampling artifact formation is presented. Formaldehyde is collected on an annular denuder coated with bisulfite-triethanolamine. The sorbent layer is extracted with water and the solution analyzed by the chromotropic acid (CTA) procedure. Sorption efficiency and loading capacity have been investigated along with storage stability.

Results of laboratory validation studies have indicated that a small annular denuder was able to sample about 300 μg CH₂O without an appreciable decrease in the initial collection efficiency (99% at 2.5 1 min^?1).

Tests on storage stability before and after exposure have also demonstrated that both oxidation of bisulfite and release of CH₂O did not occur for time periods as long as 1 month.     

Investigations of gas and particle dynamics in first generation needle-free drug delivery devices

Abstract. Transdermal powdered drug delivery involves the propulsion of solid drug particles into the skin by means of high-speed gas-particle flow. The fluid dynamics of this technology have been investigated in devices consisting of a convergent-divergent nozzle located downstream of a bursting membrane, which serves both to initiate gas flow (functioning as the diaphragm of a shock tube) and to retain the drug particles before actuation. Pressure surveys of flow in devices with contoured nozzles of relatively low exit-to-throat area ratio and a conical nozzle of higher area ratio have indicated a starting process of approximately 200 s typical duration, followed by a quasi-steady supersonic flow. The velocity of drug particles exiting the contoured nozzles was measured at up to 1050 m/s, indicating that particle acceleration took place primarily in the quasi-steady flow. In the conical nozzle, which had larger exit area ratio, the quasi-steady nozzle flow was found to be overexpanded, resulting in a shock system within the nozzle. Particles were typically delivered by these nozzles at 400 m/s, suggesting that the starting process and the quasi-steady shock processed flow are both responsible for acceleration of the particle payload. The larger exit area of the conical nozzle tested enables drug delivery over a larger target disc, which may be advantageous. Received 12 March 2000 / Accepted 8 June 2000