PION CLOUD MIT-BAG MODEL OF HADRON STRUCTURE

We Construct a pion cloud MIT-bag model with chiral symmetry. The pion cloud outside the bag is a classical spherica field. The calculated hadron mass spectra are comparable with the experimental data. The decay width of Δ⁺⁺(1236) calculated in this model is Γ_Δ=115.8 MeV, which is very close to the experimental value. We also calculate the phase shift of P₃₃ resonance. The resultin curve fits the experimental data exceedly well.     

INPUT FORCES ESTIMATION OF BEAM STRUCTURES BY AN INVERSE METHOD

An on-line recursive inverse method to estimate the input forces of beam structures is presented. The inverse method is based on the Kalman filter and a recursive least-squares algorithm. The filter models the system dynamics in a linear set of state equations. The state equations of the beam structures were constructed using the finite element method. The practicability and accuracy of the estimation method were examined with numerical simulations from which the input forces of a cantilever beam with a lumped mass on the free end were estimated from the output responses. In the numerical experiments, the cantilever beam was subjected to five types of input forces, i.e., sinusoidal, triangular impulse, rectangular impulse, a series of impulses and random. The simulation results show that the inverse method has an excellent performance to estimate the input forces of beam structural systems from the noisy measurements.     

INELASTIC SCATTERING OF PION AND KAON MESONS ON Ca NUCLEUS

In the frame of the first order approach of KMT multiple scattering theory, using the eikonal distored wave impulse approximation, together with the empirical transition densities, the inelastic scattering of the pion mesons on ⁴⁰Ca is investigated, and the inelastic scattering of the kaon mesons on ⁴⁰Ca is also predicted.     

晶界裂纹成长的一种可能的机构和蠕变断裂时的估计

本文首先分析了Hull和Rimmer工作。根据对有关实验资料的分析和我们自己的实验研究,同时也吸取了Hull和Rimmer工作中合理的部分,提出一种新的蠕变断裂机构。由此导出蠕变断裂时间公式。理论计算与实测值的比较表明,本文的结果较上述工作有所改进。 关键词：     

PION SCATTERING FROM WELL-DIFORMED NUCLEI

In the framework of the eikonal theory and using the first order π-nucleus optical potential, the elastic and inelastic scatterings of π^± from well-deformed nuclei are discussed. The virtual excitations to the low-lying levels are taken into account in the calculations of the elastic scatterings by using the closure approximation. The theoretical results of pion scatterings from ¹⁵²Sm at T_π=180MeV are compared with the data.     

THE EFFECT OF PION CONDENSATION IN HIGH ENERGY PROTON-NUCLEUS SCATTERING

According to the prediction made by A.B. Migda, a pion condensate should already be present in ordinary finite nuclei, We have studied the effect of pion condensate in high energy proton-nucleus scattering by using the Glauber multiple scattering theory, A calculation has been performed for P-⁴⁰Ca elastic scattering at the incident energy of 1 GeV and compared with the data available. The results strongly indicate that pion condensate does not have an adequate, opportunity to manifest itself in high energy proton-nucleus scattering, at least so for small angle scattering.     

电子束辐照硬铝产生热击波及层裂的估算

 本文对LY-12铝受到强流低能相对论电子束辐照时产生的热击波及层裂效应进行了估算。在预估中等能量沉淀产生材料的动态响应时必须适当地考虑熔化过程。我们所用的状态方程是GRAY三相状态方程，它对熔化区域中的金属作了详细且在热力学上更为完善的描述。将计算值同实验结果进行比较表明，二者基本上是一致的。     

离子轰击引起的表面形貌对Ag的溅射产额的影响

用捕获膜技术和卢瑟福背散射(RBS)谱仪测定Ag靶在27keV Ar⁺离子轰击下的溅射原子角分布,从而确定不同剂量下Ag的溅射产额,并对其靶点表面形貌进行扫描电子显微镜(SEM)观察。结果发现,所有的角分布都呈over-cosine形状,但其溅射产额却随着表面形貌不同而不同。根据溅射产额Y与轰击离子入射角φ变化关系,讨论不同轰击剂量下溅射产额的差别,肯定了表面形貌是影响溅射产额的一个重要因素,并由此提出“表观产额”的新概念。 关键词：     

三线态形成的量子产率研究

本文利用脉冲激光光声微量量热方法，以蒽为标准化合物，尝试求几种有机化合物，如吖啶，二苯酮，吩噻嗪及菲的三线态形成量子产率ХＴ。结果发现吖啶的ХＴ值与文献（１）吻合得很好；由于实验所用传感器时间响应的限制，所求其他三种化合物的ХＴ值与文献值有较大的偏差，为此，利用解卷带积方法，扣除传感器的响应后，即可求得较满意的ХＴ值。     

π凝聚态中的弱过程对中子星振动的阻尼效应

本文主要讨论了中子星内部发生从正常中子物态到π凝聚物态相变所产生的星体振动的阻尼,由弱作用反应u(p₁)→u(p₂)+e^-+v_e和u(p₁)+e^-→u(p₂)+v_e算出振动阻尼时标,并考虑了中子星内部的热演化。 关键词：     

液体定压比热容的理论推算

液体定压比热容的理论推算赵小明，刘志刚，王文，陈钟颀（西安交通大学能源与动力工程学院西安７１００４９）关键词聚集理论，循环，比热容１前言物质的比热容不仅是其重要的热物性参数之一，而且是与物质结构密切相关的特征数据，它对物理学和化学的理论研究及许多化工...     

声达信号谱估计

本文对确定性窄带信号的理论相关函数和信号样本以及随机窄带信号样本用自回归(AR)和FFT两种方法进行了谱估计。这些结果很好地解释了声达信号的谱估计结果,即对靠得很近的双谱峰,AR的分辨率劣于FFT,对于相距较远的双谱峰和单谱峰,AR的估计精度好于FFT。在所有的情况下.AR方法的谱曲线平滑,旁瓣低。这两种方法联合使用是对声达信号进行谱估计的好方法。     

A SYSTEMATIC DISTORTED WAVE IMPULSE APPROXIMATION ANALYSIS OF THE CONVENTIONAL MECHANISM FOR PION DOUBLE CHARGE EXCHANGE

In the framework of the distorted wave impulse approximation,a systematic analysis is performed for the contribution from the conventional mechanism to the double charge exchange to the double isobaric analog state.The effects of distortions of pions,nuclear wave functions,short-range correlation functions,parameters of form factors,the spin-dependent term in the πN amblitude etc.are examined.It is shown that all these elements are very important and not negligible for the conventional mechanism.But after including the effects of all these elements,the conventional mechanism is still not able to reproduce the experimental excitation function and agular distribution for the energy region of 0—300MeV,therefore the effects of some other mechanisms should be included.     

MULTINUCLEON EFFECT IN PION SINGLE CHARGE EXCHANGE REACTION

In the frame of DWBA and by including multinucleon effects in the optical potential and transition matrix elements,we calculate ¹³C(π⁺,π⁰)¹⁹N(IAS) reactions.Angular distribution at 165MeV,forward angle excitation function and integrated cross sections for this reactions are studied.A formula for mass dependence of forward differential cross sections is derived.     

THE ONE PION EXCHANGE POTENTIAL AT FINITE TEMPERATURE

By means of the imaginary time Greer's function method,we extend the One Pion Exchange Potential (OPEP) of nucleon-nucleon interaction to finite temperature.We sum up all the bubble diagrams and find that the temperature effect to OPEP is small at low temperature region but large at high temperature region.The effective mass of pion field M_π(β) will become imaginary at critical temperature T_c=177MeV.It means that the attractive OPEP will disappear at T_c and the phase transition happens.     

π介子核子碰撞产生π介子的色散关系

本文讨论了π介子核子碰撞产生π介子的色散关系,计算了束缚态的贡献。所用的方法是把核子场的算符由态矢量中提出来,对运动学和对称性作了较详细的分。     

ON THE SPONTANEOUS PION EMISSION BY HEAVY NUCLEI

In this paper a method of detecting the pionic nuclear radio-activity discussed by Ion et al.is proposed using in clusive high energy gamma ray measurement.Taking the maximum pion energy given by Ion et al,the energy ranges of the gamma rays from the emitted π⁰ mesons are calculated.     

OCTUPLE DEFORMATION EFFECT IN PION SCATTERING FROM WELL-DEFORMED NUCLEI

The importance of octuple deformation in π^±-¹⁵²Sm scatterings is studied.Results show that the contribution due to octuple deformation to the differential cross section is small.     

原子激光共振电离效率的估计

本文在比较严格条件下求解三能级原子系统的激光共振电离过程的速率方程,仔细分析和计算连续、准连续和脉冲激光激发与电离的效率,文中给出一些典型实验条件下的计算结果,以及电离效率随各种参数变化的趋势,本文给出的计算方法和所用的程序具有普遍的适用性,只要给出必要的参数,即可用该程序对具体的实验过程进行定量计算。 关键词：