The test of chaos is the first problem when one research economics.using theory of chaos and nonlinear dynamics.There are many methods from various fields,the detection of chaos in financial time series made use of these method,however,it is difficult to detect chaos in financial time series for its short and noise.Nowaday,Gencay-Dechert algorithm and the suuogate data test are applied widely and being developed.
The corrosion of rebars in concrete is a major cause of the falling bearing capacity of concrete structures.The durability of concrete could be effectively enhanced by adding mineral admixtures.Many studies have shown that rust inhibitors can effectively prevent rebar corrosion.Taking commonly used slag, fly ash, and silica fume as mineral admixtures, this paper explores how an alcohol-amine compound rust inhibitor affects the compressive strength, chloride penetration resistance, carbonation resistance, and rebar corrosion resistance of concrete with a large amount of mineral admixtures.The research results show that the addition of rust inhibitor hinders the early hydration of cementitious materials in concrete; the chloride diffusivity and carbonation depth of concrete were minimized, when the ratio of N,N-dimethylethanolamine (DMEA) to sodium monofluorophosphate (MFP) in the compound rust inhibitor stands at 15:1; the addition of rust inhibitor clearly suppressed the corrosion loss of the rebars in concrete, resulting in a low rebar corrosion rate.The research results provide experimental evidence for reducing rebar corrosion in reinforced concrete.
This study investigates the effects of a vibration force field on the mixing and structural properties of polylactic acid (PLA), polybutylene succinate (PBS), and ethylene-glycidyl methacrylate terpolymer (EGMA) blends. A balanced triple-screw dynamic extrusion process was utilized to prepare PLA/PBS/EGMA composites under various vibration parameters, specifically amplitude and frequency. The results indicate that the introduction of a vibration force field significantly enhances the dispersion of the PLA/PBS/EGMA blend, leading to improved mechanical properties, thermal stability, and crystallization behavior. When the vibration frequency was 6 Hz and the amplitude was 1.0 mm, the impact strength increased from the steady-state value of 70.86 KJ/m2 to 88.21 KJ/m2. When the amplitude was 0.4 mm and the frequency was 10 Hz, the impact strength reached 81.86 KJ/m2. The orthogonal experimental design and entropy method analysis revealed that vibration frequency and amplitude play a dominant role in optimizing mechanical performance, whereas processing temperature and rotor speed exhibit minimal impact. Scanning electron microscopy (SEM) analysis confirmed that the vibration force field reduces phase separation, promoting a finer and more homogeneous dispersion of PBS and EGMA within the PLA matrix. Additionally, TGA and DTG curves suggest that when the vibration amplitude and frequency are lower than specific thresholds, the thermal stability of the blend deteriorates. In contrast, when they exceed those thresholds, thermal stability improves. For instance, with an amplitude of 1.0 mm, the initial degradation temperature (T5) climbs from 328.6 °C to 333.7 °C. At a frequency of 10 Hz, T5 reaches 333.1 °C. These findings provide theoretical support for the application of vibration-assisted extrusion in the development of high-performance biodegradable polymer blends.
Based on some testing data of full-depth asphalt pavement of testing section of Shijiazhuang-Huanghuagang Expressway,the influence of temperature on capability of asphalt-stabilized base is analyzed,and the effect of temperature on intensity of asphalt base and non-deformability of asphalt mixture is obtained,which can be consulted by peers.
The study of surge pressure is of significant importance for the safety of drilling process because field practice shows that the surge pressure caused by fluid viscous force can cause a great damage to the drilling operation. The accurate calculation of surge pressure is directly related to the safety of the drilling process. However, the existing surge pressure models rarely take the impact of the collar into consideration and thus will inevitably affect the precision of the surge pressure calculation. In this study, based on the pumping condition, a steady-state calculation model for surge pressure caused by drilling fluid viscous force is developed considering the presence of collar. In the end a case study is presented to demonstrate the importance of collar during the calculation of surge pressure.
This paper proposes using neutral axis locations to monitor and quantify the prestress force in post-tensioned precast segmental beams. Strain measurements are used to obtain the neutral axis locations of specific cross-sections of the precast prestressed segmental beams, based on the plane–remains–plane and linear strain distribution assumption. A theoretical calculation method based on the static equilibrium of a specific cross-section is developed to calculate the prestress force in segmental beams based on the neutral axis location. To verify the accuracy of the proposed method, a post-tensioned prestressed segmental beam is built and tested in the laboratory. A corresponding high-fidelity finite element model is also developed based on the beam design and material properties. Experimental studies and numerical simulations are conducted to verify the feasibility and accuracy of the proposed method in quantifying the prestress force in precast segmental beams. Both experimental and numerical results demonstrate that the proposed method can reliably estimate the prestress force, which can be used to monitor the prestress force loss in post-tensioned structures.
Redundancy technique is an important technique to improve reliability of system.In order to increase the reliability of Inertial Integrated Navigation System,this paper proposes Double Strapdown Inertial instead ofFive- meter measureinstrumentmethod widely used in our country,studies on tolerance scheme of Odd-even Vector Equation on FDI(Failure Detection and Isolation)and adopt residual to test reasonable of estimates of states.
The aircraft passive sonic detects and identification technology as a traditional means of reconnaissance is an important component of airborne early-warning system. Using the sound wave what the acoustic targets produces in the rate process, to identify the targets is the basic task of passive acoustic detection system. This study using modern signal processing method studies the wavelet transform feature information extraction method of target audio signals. Based on the two kinds of battlefields targets about the audio spectrum characteristics, using the characteristic pick-up arithmetic of the wavelet decomposition measure detail signal domain energy which is based on wavelet theorystudy using this algorithm obtains lower-dimensional feature vector.
