Abstract:
The manuscript reviews the history and quo of the theory of Timoshenko’s method in stability analysis of compressive levers first, taking an example to explain the m-simulation method and putting forward the 3^{rd}-7^{th} boundary conditions demonstrating their superiorities in improving the precision through examples, followed by proposing and applying the join conditions in the stability analysis of combined axial force compressive levers gaining success. Through a brief example showing the effect of some related theories in a simple structural stability analysis, its application prospect is discussed.

Abstract:
On account of the traditional method in hybrid stability analysis being too rough, a new method of taking dual or single mode was put forward for 4 typical levers in the hybrid stability analysis respectively and transited to the dynamic analysis smoothly. After verifying the superiority of the method through examples, the broad application prospect would be given in the end.

Abstract:
The spin-dependent structure functions $g_1(x)$, $g_2(x)$, ${g}_2^{WW}(x)$ and ${\bar g}_2(x)$ and their moments are studied in the CM bag model. The results show that (i) $\int_0^1g_2(x)dx=0$, i.e. the Burkhardt-Cottingham sum rule holds, hence $g_2(x)$ must have at least one non-trivial zero besides $x=0$ and $x=1$. (ii) $\int_0^1x^2g_2(x)dx$ is negative for the proton, neutron and deuteron. (iii) $\int_0^1x^2g_2(x)dx$ is about one order of magnitude smaller than $\int_0^1x^2g_1(x)dx$, hence the twist-3 matrix element is approximately equal to the twist-2 matrix element. The results are compared with most recent data and predictions from the MIT bag model, lattice QCD and QCD sum rules.

Abstract:
Quark spin and orbital angular momentum in the nucleon are calculated in symmetry-breaking chiral quark model. The results are compared with data and other models.

Abstract:
New relations between the quark spin-flavor contents of the nucleon and axial weak coupling constants are obtained in the chiral quark model with both SU(3) and U(1)-breaking effects. Using the nonsinglet spin combinations, $\Delta_3$ and $\Delta_8$, all spin-flavor observables are functions of only one parameter $a$ $-$ probability for the chiral pionic fluctuation. The upper and lower bounds of these observables are given. The optimal range of $a$, determined by NMC data $\bar d-\bar u$, gives a constraint to the cutoff of the chiral quark field theory. The model predictions are in good agreement with the existing data in this range of $a$. The roles of kaon, $\eta$ and $\eta'$ are also discussed.

Abstract:
The spin and orbital angular momentum carried by different quark flavors in the nucleon are calculated in the SU(3) chiral quark model with symmetry-breaking. The model is extended to all octet and decuplet baryons. In this model, the reduction of the quark spin, due to the spin dilution in the chiral splitting processes, is transferred into the orbital motion of quarks and antiquarks. The orbital angular momentum for each quark flavor in the proton as function of the partition factor $\kappa$ and the chiral splitting probability $a$ is shown. Although the total amount of the quark spin reduction is canceled by the the equal amount increase of the quark orbital angular momentum, the cancellation does not apply to each quark flavor. Especially, the cancellation between the spin and orbital contributions in the baryon magnetic moment is discussed. Comparisons of our results with other models are also shown.

Abstract:
The quark spin and flavor structure of the nucleon is discussed in the SU(4) symmetry breaking chiral quark model. The spin and flavor contents for charm quarks and anti-charm quarks are predicted and compared with the results given by other models. The intrinsic charm quark contribution to the Ellis-Jaffe sum rule is discussed.

Abstract:
The spin and orbital angular momentum carried by different quark flavors in the nucleon are calculated in the SU(3) chiral quark model with symmetry-breaking. The similar calculation is also performed for other octet and decuplet baryons. Furthermore, the flavor and spin contents for charm and anti-charm quarks are predicted in the SU(4) symmetry breaking chiral quark model.

Abstract:
If one retains M^2/Q^2 terms in the kinematics, the Nachtmann variable \xi seems to be more appropriate to describe deep inelastic lepton-nucleon scattering. Up to the first power of M^2/Q^2, a modified Wandzura-Wilczek relation with respect to \xi was derived. Kinematical correction factors are given as functions of \xi and Q^2. A comparison of the modified g_2^WW(\xi) and original g_2^WW(x) with the most recent g_2 data is shown.

Abstract:
An unified scheme for describing both spin and orbital motion in symmetry-breaking chiral quark model is suggested. The analytic results of the spin and orbital angular momenta carried by different quark flavors in the nucleon are given. The quark spin reduction due to spin-flip in the chiral splitting processes is compensated by the increase of the orbital angular momentum carried by the quarks and antiquarks. The sum of both spin and orbital angular momenta in the nucleon is 1/2, if the gluons and other degrees of freedom are neglected. The same conclusion holds for other octet and decuplet baryons. Possible modification and application are briefly discussed.