A novel algorithm to analyze the dynamics of digital chaotic maps in finite-precision domain

Chaotic maps are widely used to design pseudo-random sequence generators, chaotic ciphers, and secure communication systems. Nevertheless, the dynamic characteristics of digital chaos in finite-precision domain must be degraded in varying degrees due to the limited calculation accuracy of hardware equipment. To assess the dynamic properties of digital chaos, we design a periodic cycle location algorithm(PCLA) from a new perspective to analyze the dynamic degradation of digital chaos. The PCLA can divide the state-mapping graph of digital chaos into several connected subgraphs for the purpose of locating all fixed points and periodic limit cycles contained in a digital chaotic map. To test the versatility and availability of our proposed algorithm, the periodic distribution and security of 1-D logistic maps and 2-D Baker maps are analyzed in detail. Moreover, this algorithm is helpful to the design of anti-degradation algorithms for digital chaotic dynamics. These related studies can promote the application of chaos in engineering practice.

Degradation Behavior and Safe Application Technology of 30% Kresoxim-methyl SC in Cucumber and Soil

[ Objective ] The paper was to determine the residue behavior and environmental safety of 30% kresoxim-methyl SC applied on cucumber under green- house conditions. [Method] Referring to Test Standard of Pesticide Residues, the residue dynamics of kresoxim-methyl SC in cucumber was determined by GC. [ Result ] The half lives of kresoxim-methly in cucumber of Yinchuan, Changsha, Harbin were 2.8 - 3.1,2.4 - 3.7, 2.1 - 5.1 d, respectively, and the final resi- due in cucumber after application for 3,5,7 d was less than 0.500 0 mg/kg that was the limited standards of the state. [ Conclusion] Under the proposed cultiva- tion conditions, it is recommended to use the maximum dosage formulation of 270 g. a. i/ha （ preparation 0.09 g/m2 ）, with spraying up to three times and the safe interval of 3 -5 d.

A novel method of constructing high-dimensional digital chaotic systems on finite-state automata

When chaotic systems are implemented on finite precision machines, it will lead to the problem of dynamical degradation. Aiming at this problem, most previous related works have been proposed to improve the dynamical degradation of low-dimensional chaotic maps. This paper presents a novel method to construct high-dimensional digital chaotic systems in the domain of finite computing precision. The model is proposed by coupling a high-dimensional digital system with a continuous chaotic system. A rigorous proof is given that the controlled digital system is chaotic in the sense of Devaney's definition of chaos. Numerical experimental results for different high-dimensional digital systems indicate that the proposed method can overcome the degradation problem and construct high-dimensional digital chaos with complicated dynamical properties. Based on the construction method, a kind of pseudorandom number generator (PRNG) is also proposed as an application.

Numerical Analyses of Caisson Breakwaters on Soft Foundations Under Wave Cyclic Loading

A caisson breakwater is built on soft foundations after replacing the upper soft layer with sand. This paper presents a dynamic finite element method to investigate the strength degradation and associated pore pressure development of the intercalated soft layer under wave cyclic loading. By combining the undrained shear strength with the empirical formula of overconsolidation clay produced by unloading and the development model of pore pressure, the dynamic degradation law that describes the undrained shear strength as a function of cycle number and stress level is derived. Based on the proposed dynamic degradation law and M-C yield criterion, a dynamic finite element method is numerically implemented to predict changes in undrained shear strength of the intercalated soft layer by using the general-purpose FEM software ABAQUS, and the accuracy of the method is verified. The effects of cycle number and amplitude of the wave force on the degradation of the undrained shear strength of the intercalated soft layer and the associated excess pore pressure response are investigated by analyzing an overall distribution and three typical sections underneath the breakwater. By comparing the undrained shear strength distributions obtained by the static method and the quasi-static method with the undrained shear strength distributions obtained by the dynamic finite element method in the three typical sections, the superiority of the dynamic finite element method in predicting changes in undrained shear strength is demonstrated.

Dynamic degradation patterns of porous polycaprolactone/β-tricalcium phosphate composites orchestrate macrophage responses and immunoregulatory bone regeneration

Biodegradable polycaprolactone/β-tricalcium phosphate(PT)composites are desirable candidates for bone tissue engineering applications.A higherβ-tricalcium phosphate(TCP)ceramic content improves the mechanical,hydrophilic and osteogenic properties of PT scaffolds in vitro.Using a dynamic degradation reactor,we estab-lished a steady in vitro degradation model to investigate the changes in the physio-chemical and biological properties of PT scaffolds during degradation.PT46 and PT37 scaffolds underwent degradation more rapidly than PT scaffolds with lower TCP contents.In vivo studies revealed the rapid degradation of PT(PT46 and PT37)scaffolds disturbed macrophage responses and lead to bone healing failure.Macrophage co-culture assays and a subcutaneous implantation model indicated that the scaffold degradation process dynamically affected macro-phage responses,especially polarization.RNA-Seq analysis indicated phagocytosis of the degradation products of PT37 scaffolds induces oxidative stress and inflammatory M1 polarization in macrophages.Overall,this study reveals that the dynamic patterns of biodegradation of degradable bone scaffolds highly orchestrate immune responses and thus determine the success of bone regeneration.Therefore,through evaluation of the biological effects of biomaterials during the entire process of degradation on immune responses and bone regeneration are necessary in order to develop more promising biomaterials for bone regeneration.

Fluid-induced corrosion behavior of degradable zinc for stent application

The influence of laminar flow on the corrosion of pure zinc(Zn) and cell response was investigated and compared with the static measurements.The results revealed that laminar flow accelerated the corrosion and enhanced the localized corrosion of pure Zn.The dynamic corrosion rate was 0.184 mm/yr after 168 h corrosion.More corrosion products were formed under flow condition,which were mainly composed of Zn_(3)(PO_(4))_(2)·4 H_(2) O,Ca_(3)(PO_(4))_(2),ZnO and Zn_(5)(OH)_(6)(CO_(3))_(2).Moreover,the adhered rat aortic endothelial cells(RAEC) on Zn samples exhibited notably cell loss and round configuration under laminar flow.