Fatigue Life Prediction of Wire Rope Based on Grey Particle Filter Method under Small Sample Condition

As the fatigue life prediction of wire rope has the defects of large samples and many interference factors, this paper takes the 6×31WS+FC type wire rope as research carrier. Based on small samples, the grey particle filter method has been creatively proposed to realize the wire rope fatigue life prediction under various load conditions. First, combining the reliability life data prediction with the equivalent alternating stress of the dangerous part during the fatigue test, the reliability stress-life curve was determined. Subsequently, the particle filter method has been used to modify the curve to obtain the modified P-S-N curve. Finally, with theory of fatigue damage accumulation, the fatigue life prediction model was established, and compared with the test results. The results show that based on small sample conditions, the proposed method can predict the fatigue life of wire ropes under various loading conditions with high precision, which proves the general applicability.

Improved Grey Particle Swarm Optimization and New Luus-Jaakola Hybrid Algorithm Optimized IMC-PID Controller for Diverse Wing Vibration Systems

The PID control plays important role in wing vibration control systems. However, how to efficiently optimize the PID parameters for different kinds of wing vibration systems is still an open issue for control designers. The problem of PID control optimization is first converted into internal mode control based PID (IMC-PID) parameters optimization problem for complex wing vibration systems. To solve this problem, a novel optimization technique, called GNPSO is proposed based on the hybridization of improved grey particle swarm optimization (GPSO) and new Luus-Jaakola algorithm (NLJ). The original GPSO is modified by using small population size/iteration number, employing new grey analysis rule and designing new updating formula of acceleration coefficients. The hybrid GNPSO benefits improved global exploration of GPSO and strong local search of new Luus-Jaakola (NLJ), so as to avoid arbitrary and inefficient search of global optimum and prevent the trap in local optimum. Diverse wing vibration systems, including linear system, nonlinear system and multiple-input-multiple-output system are considered to verify the effectiveness of proposed method. Simulation results show that GNPSO optimized method obtains improved vibration control performance, stronger robustness and wide applicability on all system cases, compared to existing evolutionary algorithm based tuning methods. Enhanced optimization convergence and computation efficiency obtained by GNPSO tuning technique are also verified by statistical analysis.

Comparative study for target fragmentation in 4He and 6Li interactions with emulsion nuclei at Elab = 3.7A GeV

The multiplicity characteristics of the grey and black particles are studied in 3.7A GeV 4He and 6Li interactions with emulsion nuclei. The dependence on the system size is examined. The data are classified according the emission direction in the 4π space. The forward or backward emitted grey particle multiplicities distributions are approximated by exponential decay law. The black particle distributions also have the decay shapes, except for the CNO target nuclei; they are shoulder-shaped curves. The production probabilities and average multiplicities increase linearly with the target size. Multiplicity correlations are carried out. Regarding the nuclear limiting fragmentation hypothesis, the grey and black particle productions are independent of the projectile size.

Sensibility of grey particle production system to energy and centrality in 60A and 200A GeV 16O–Nucleus interactions

The grey particle production following 60 A and 200[Formula: see text]A GeV [Formula: see text]O interactions with emulsion nuclei is investigated at different centralities. The evaporated target fragment multiplicity is voted as a centrality parameter. The target size effect is examined over a wide range, where the C, N and O nuclei present the light target group while the Br and Ag nuclei are the heavy group. In the framework of the nuclear limiting fragmentation hypothesis, the grey particle multiplicity characteristics depend only on the target size and centrality while the projectile size and energy are not effective. The grey particle is suggested to be a multisource production system. The emission direction in the 4[Formula: see text] space depends upon the production source. Either the exponential decay or the Poisson’s peaking curves are the usual characteristic shapes of the grey particle multiplicity distributions. The decay shape is suggested to be a characteristic feature of the source singularity while the peaking shape is a multisource super-position. The sensibility to the centrality varies from a source to other. The distribution shape is identified at each centrality region according to the associated source contribution. In general, the multiplicity characteristics seem to be limited w.r.t. the collision system centrality using light target nuclei. The selection of the black particle multiplicity as a centrality parameter is successful through the collision with the heavy target nuclei. In the collision with the light target nuclei it may be qualitatively better to vote another centrality parameter.

Emission characteristics of fast target protons in ultrarelativistic16O–nucleus collisions

The target fragmentation in 60A and 200A GeV16O interactions with emulsion nuclei is analyzed. The validity of the nuclear limiting fragmentation hypothesis is confirmed at ultrarelativistic energies. The emission mechanism of the fast target proton (grey particle) is investigated in terms of the multiplicity characteristics. The anisotropy ratio and asymmetry parameter, while found to be independent of the projectile size or incident energy, are dependent on the target size and system centrality. This dependence is insignificant for heavy targets and in more central regions, where constancy exists. In this species, the system of the grey particle emission cannot exhibit the optimum symmetry or asymmetry between the forward and backward hemispheres. It is seen that these target protons originate from two emission sources in the earlier stage of the target fragmentation. One them emits nucleons isotropically in the 4π space. The other is the main emission source, which emits nucleons, in the forward hemisphere only, as a result of the binary nucleon–nucleon collisions and (or) intranuclear cascade.