The integrated structure parts are widely used in aircraft. The distortion caused by residual stresses in thick pre-stretched aluminum plates during machining integrated parts is a common and serious problem. To predi...The integrated structure parts are widely used in aircraft. The distortion caused by residual stresses in thick pre-stretched aluminum plates during machining integrated parts is a common and serious problem. To predict and control the machining distortion, the residual stress distribution in the thick plate must be measured firstly. The modified removal method for measuring residual stress in thick pre-stretched aluminum plates is proposed and the stress-strain relation matrix is deduced by elasticity theory. The residual stress distribution in specimen of 7050T7451 plate is measured by using the method, and measurement results are analyzed and compared with data obtained by other methods. The method is effective to measure the residual stress.展开更多
Based on results of saturated vapor pressures of pure substances calculated by SRK equation of state, the factor a in attractive pressure term was modified. Vapor-liquid equilibria of mixtures were calculated by origi...Based on results of saturated vapor pressures of pure substances calculated by SRK equation of state, the factor a in attractive pressure term was modified. Vapor-liquid equilibria of mixtures were calculated by original and modified SRK equation of state combined with MHV1 mixing rule and UNIFAC model, respectively. For 1447 saturated pressure points of 37 substance including alkanes; organics containing chlorine, fluorine, and oxygen; inorganic gases and water, the original SRK equation of state predicted pressure with an average deviation of 2.521% and modified one 1.673%. Binary vapor-liquid equilibria of alcohols containing mixtures and water containing mixtures also indicated that the SRK equation of state with the modified a had a better precision than that with the original one.展开更多
This paper is motivated by looking for a loop solution of the Hamiltonian systems such that (0.1) q'(t)+V′(q(t))=0 for t∈ with some T>0 and (0.2) 12|q′(t)| 2+V(q(t))=h ...This paper is motivated by looking for a loop solution of the Hamiltonian systems such that (0.1) q'(t)+V′(q(t))=0 for t∈ with some T>0 and (0.2) 12|q′(t)| 2+V(q(t))=h for t∈ with q(0)=q(T)=x 0 where q∈C 2(, R n 0}), n≥2, x 0∈R n 0} is a fixed point, h∈R is a given number, V∈C 2(R n 0}), R is a potential with a singularity and V′ denotes its gradient. Our main existence results are obtained by a appropriately defined lengthdecreasing (or rather energy decreasing) deformation and a min max procedure which is a combined version of Bahri Rabinowitz and Klingenberg . Our main assumptions are geodesic convex conditions found by the author and the strong force condition of Gordon . As a direct application, for the relativistic gravitational potential V(x)=|x| -1 +|x| -2 or its large scale perturbation, there always exists an almost periodic solution of (0.1)-(0.2) for any h∈R and any x 0∈R n 0} with | x 0 | small enough. This is an interesting phenomenon because we know that there exists no periodic solution of prescribed nonnegative energy for such a Hamiltonian system.展开更多
文摘The integrated structure parts are widely used in aircraft. The distortion caused by residual stresses in thick pre-stretched aluminum plates during machining integrated parts is a common and serious problem. To predict and control the machining distortion, the residual stress distribution in the thick plate must be measured firstly. The modified removal method for measuring residual stress in thick pre-stretched aluminum plates is proposed and the stress-strain relation matrix is deduced by elasticity theory. The residual stress distribution in specimen of 7050T7451 plate is measured by using the method, and measurement results are analyzed and compared with data obtained by other methods. The method is effective to measure the residual stress.
文摘Based on results of saturated vapor pressures of pure substances calculated by SRK equation of state, the factor a in attractive pressure term was modified. Vapor-liquid equilibria of mixtures were calculated by original and modified SRK equation of state combined with MHV1 mixing rule and UNIFAC model, respectively. For 1447 saturated pressure points of 37 substance including alkanes; organics containing chlorine, fluorine, and oxygen; inorganic gases and water, the original SRK equation of state predicted pressure with an average deviation of 2.521% and modified one 1.673%. Binary vapor-liquid equilibria of alcohols containing mixtures and water containing mixtures also indicated that the SRK equation of state with the modified a had a better precision than that with the original one.
文摘This paper is motivated by looking for a loop solution of the Hamiltonian systems such that (0.1) q'(t)+V′(q(t))=0 for t∈ with some T>0 and (0.2) 12|q′(t)| 2+V(q(t))=h for t∈ with q(0)=q(T)=x 0 where q∈C 2(, R n 0}), n≥2, x 0∈R n 0} is a fixed point, h∈R is a given number, V∈C 2(R n 0}), R is a potential with a singularity and V′ denotes its gradient. Our main existence results are obtained by a appropriately defined lengthdecreasing (or rather energy decreasing) deformation and a min max procedure which is a combined version of Bahri Rabinowitz and Klingenberg . Our main assumptions are geodesic convex conditions found by the author and the strong force condition of Gordon . As a direct application, for the relativistic gravitational potential V(x)=|x| -1 +|x| -2 or its large scale perturbation, there always exists an almost periodic solution of (0.1)-(0.2) for any h∈R and any x 0∈R n 0} with | x 0 | small enough. This is an interesting phenomenon because we know that there exists no periodic solution of prescribed nonnegative energy for such a Hamiltonian system.
