非理想第二类超导体局域磁弛豫的计算模拟：非均匀钉扎势和表面势垒影响

从热激活模型出发,对非理想第二类超导的局域磁行为进行了计算模拟.讨论了超导体体内非均匀钉扎势和表面势垒对局域磁通运动的影响.计算结果表明,体内非均匀钉扎势对磁通线的运动产生大的阻碍,表面势垒明显抑制了磁通线的进入和离开样品.相对于样品的平均磁弛豫行为和平均磁滞回线,非均匀钉扎以及扫场速率的差异更强地显示在样品的局域磁行为. 关键词： 非理想第二类超导体 局域磁弛豫 非均匀钉扎 表面势叠     

AMS重核素测量的入射离子X射线探测法

介绍了在加速器质谱学中发展的入射离子 X射线的探测技术,以便应用于测定中重同位素的同量异位素鉴别 .描述了在中国原子能科学研究院加速器质谱计上建立的入射离子 X射线探测装置和实验结果 .通过测量入射离子 X射线,实现了64Cu测量中对同量异位素64Ni和64Zn的鉴别 ,以及79Se测量中对79Br的鉴别. In recent years, a new technique to detect the charteristic X ray from projectile ions in accelerator mass spectrometry (AMS) has been developed. After analysis in the routine AMS system, the ions are stopped in an appropriately chosen target in steat of an ion detector and induced X ray are detected for identification of ions by atomic number. For the application of AMS to higher mass isotopes with mass number>20 using small accelerator, the characteristic X rays technique is better...     

Projectile dynamics at low barrel pressures

A mathematical model for a projectile shot at low pressures in the space behind the projectile space is developed. The pressure rise is limited because of the nonsimultaneity of propellant ignition and combustion and the discharge of the propellant combustion products through the gap between the projectile and the walls of the gun barrel. The kinetic characteristics of flame propagation over the propellant particles are determined. A comparison of calculation and experimental data is performed. The calculation results are used in designing 2A85 self-propelled launchers and upgrading 2A30 self-propelled launchers. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 48, No. 6, pp. 44–49, November–December, 2007.     

Influence of massive projectile size and energy on secondary ion yields from organic surfaces

We investigated the influence of the projectile size and energy using Au_n^q+ clusters (5 < n < 400, 1 < q < 4) impacting on a glycine target with a 19q-34q keV energy range. We show that both CN⁻ fragment and Gly⁻ molecular ion yields are equivalent for projectiles with n > 9 and increase with the energy per projectile atoms. A maximum yield of 0.5 (50%) for both CN⁻ and Gly⁻ was obtained with the Au₄₀₀⁴⁺ projectile at 136 keV total energy. For Gly⁻, the yield enhancement is linear for Au_n when n > 5. Trends for the CN⁻ fragment are different. A nonlinear yield enhancement proportional to n³ is observed for Au_n when n < 9.     

Production of helium projectile fragments in {16O－emulsion interactions at 4.5 A GeV/c

The measurements of partial production cross sections of the multiple helium projectile fragments emitted at 4.5 A GeV/c {}^{16}O－Em interactions are reported. We have studied the production rate of helium projectile fragments due to fragmentation of {}^{16}O ions and compared it with that obtained from different projectiles at various energies. The dependence of on the mass number of the incident beams is formulated. The multiplicity distributions of the helium fragments produced in {}^{16}O－Em interactions at different energies exhibit Koba－Nielson－Olesen (KNO) scaling. The correlation of helium projectile fragments and target fragments is also investigated and it is found that the average of target fragments is increased with the decrease of the number of helium fragments in peripheral interactions.     

Incremental Gravimetry: A Method for Two-Parameter Model Building of Binary Gas Co-Adsorption Equilibria

This paper presents and develops a novel methodology to determine thermodynamic parameters of binary gas co-adsorption equilibria at given total pressure, based exclusively on binary gravimetric measurements at this same total pressure, together with single component isotherms. By Incremental Gravimetry, we designate a procedure in which the adsorbent sample is submitted to increments of composition of a flowing binary gas, and the corresponding increments of weight of the sample at equilibrium are measured. The experimental example is the co-adsorption of methane and carbon dioxide on Norit activated carbon near ambient temperature and pressure. The approach relies on the thermodynamics of non-ideal adsorbed solutions. The experimental methodology is described, the underlying theory is then presented. Compact analytical expressions are established that relate the measured limiting slopes of the incremental gravimetric curves (at infinite dilution of one component in the other) to quantities that derive only from the pure component isotherms, and to the infinite dilution activity coefficients. The latter are then uniquely determined. Classical two-parameter models for the composition dependence of activity coefficients are then implemented to reconstruct the complete binary isotherms and the incremental gravimetric curves. The comparison of the latter with the measured curves permits to test the different models.     

Uniqueness of Gibbs State for Non-Ideal Gas in ℝd: The Case of Multibody Interaction

We study the question of existence and uniqueness of non-ideal gas in ^d with multi-body interactions among its particles. For each k-tuple of the gas particles, 2km ₀<, their interaction is represented by a potential function _k of a finite range. We introduce a stabilizing potential function , such that (x ₁,..., ) grows sufficiently fast, when diam{x ₁,..., } shrinks to 0. Our results hold under the assumption that at least one of the potential functions is stabilizing, which causes a sufficiently strong repulsive force. We prove that (i) for any temperature there exists at least one Gibbs field, and (ii) there exists exactly one Gibbs field at sufficiently high temperature, such that for any >0, C(V ₀)< for all volumes V smaller than a certain fixed finite volume V ₀. The proofs use the criterion of the uniqueness of Gibbs field in non-compact case developed in ref. 4, and the technique employed in ref. 1 for studying a gas with pair interaction.     

反钢筋混凝土串联聚能装药技术研究

根据钢筋混凝土目标的特点,提出了一种高速杆流与低速杆流相结合的新型串联聚能装药结构。利用有限元软件分别对前级装药、后级装药的成型过程进行了数值仿真。在此基础上开展了系列串联聚能装药毁伤钢筋混凝土目标的静破甲实验。结果表明:该串联装药可有效提高对钢筋混凝土目标的毁伤能力,能起到对钢筋混凝土的扩孔作用。实验和数值仿真计算结果都表明该串联装药在对付钢筋混凝土、机场跑道、多层间隔靶等反硬目标串联型战斗部中有较好的应用前景。     

Hydrodynamic behavior of an underwater moving body after water entry

An experimental study was conducted to investigate the water entry phenomenon. A facility was designed to carry out the tests with the entry velocities of around 352 m/s. Visualization, pressure measurement, velocity measurement and underwater impact test were performed to investigate the hydroballistic behavior of the underwater moving body, the underwater flow field, the supercavitation, etc.. This study shows that the motion of a high-speed underwater body is strongly three-dimensional and chaotic. Furthermore, it is found that the distribution of the trajectory deflection of the underwater projectile depends on the depth of water. It is also found by measuring the deformation on a witness plate submerged in water, that the impact energy of an underwater projectile is reduced as it penetrates deeper into water. The project supported by Japan Society for the Promotion of Science under a Grant-in-Aid for Scientific Research (C) (Grant No. 12650162)     

INTERACTION MEAN FREE PATH OF He PROJECTILE FRAGMENTS FROM 16O-EM COLLISION AT 60 A GeV

The interaction mean free path of He projectile fragments, produced by the collisions of ^{16O at 60 A GeV in a nuclear emulsion, has been investigated. In the present analysis, 1555 He projectile fragments, giving rise to 320 secondary interactions, have been used. At a level of 3% a very weak signal of anomalons is observed, which comes mainly from the 3×He channel.}