Some Problems of Nonlinear Mechanics in Geophysics, Planetology, and Strength of Materials

We generalize results of investigations in nonlinear mechanics as applied to the phenomena at the interface between strength of materials, stability of discrete-continuous complex systems, and physicoengineering problems of verifying the unified theories of fundamental fields. The principle of a fundamental triad is formulated. In this case, systems analysis can be useful for simulating the dynamics of complex discrete-continuous mechanical systems of different dimentional scales.     

Order-preserving random dynamical systems: equilibria, attractors, applications

This paper is meant as a first step towards a systematic study of order-preserving (or monotone) random dynamical systems, in particular of their long-term behavior and their attractors. A series of examples (including random I stochastic cooperative systems and random I stochastic parabolic equations) gives ample proof of the usefulness of the subject. We show that, given a sub- and super-equilibrium, there is always an equilibrium between them. Also, the random attractor of an order-preserving random dynamical system is bounded below and above by equilibria. We finally show by way of an example that omega-limit sets can contain non-trivial totally ordered subsets.     

Some characteristics of the heave,pitch and roll vibrations within urban delivery routes

Until recently, laboratory testing of packaged systems has been undertaken by simulating vertical vibrations alone. However, with increasing demand for a reduction in packaging waste, the use lightweight systems, such as stretch film, is increasing. Such containment systems are susceptible to the lateral forces generated by the pitch and roll vibratory motion of vehicles due to road surface unevenness. If laboratory simulation is to be realistic, multi-axial motion must be taken into account and an understanding of the relationships between the random heave, pitch, and roll vibrations is essential. This paper uses vibration data collected from a number of transport vehicles traveling along typical urban and suburban routes to establish the nature and level of the multi-axial vibrations that exist. These are presented with average Power Density Spectra (PDS) as well as statistical distributions of the moving root-mean-square (rms). The paper analyses the data for correlation of the rms levels with respect to nonstationarity. This is important when simulating nonstationary (randomly fluctuating rms) vibrations for heave, pitch and roll. These statistical correlation functions are used to manage the relative rms levels of each of the three Degrees of Freedom (DoFs) when undertaking vibration simulations using multi-axis vibration test systems. The results show that the relationships between the moving rms of heave, pitch and roll vibrations are not strongly correlated but can be characterized statistically as joint distributions to enable realistic simulation of multi-axial random vibrations of road transport vehicles under controlled laboratory conditions .     

Intelligent systems using triboelectric,piezoelectric, and pyroelectric nanogenerators

Recent advances in artificial intelligence, computer science, communication, sensing and actuation technologies have resulted in the development of several novel intelligent systems. At the same time, the emergence of nanogenerators has opened a new research avenue with the overarching goal of developing self-powered sensing systems. The concepts of self-powered sensing, based on nanogenerators and intelligent systems can be fused together to open a new area of interdisciplinary research. In this article, we aim to show how these two emerging technologies have been combined to develop self-powered intelligent sensing systems. We first focus on the main keywords in the area of nanogenerators. Keyword co-occurrence network graphs are generated based on the most used keywords in the area of nanogenerators to select key concepts that are directly connected to the concept of intelligent systems. Thus, a detailed review is provided on different intelligent self-powered sensing systems based on nanogenerators. We also discuss the challenges presented by combining intelligent systems and self-powered sensing. As most of intelligent devices rely on machine learning techniques, a comprehensive section is allocated to this topic to focus on its applications in nanogenerator-based devices.     

Portable, Fiber-Based, Diffuse Reflection Spectroscopy (DRS) Systems for Estimating Tissue Optical Properties

Steady-state diffuse reflection spectroscopy is a well-studied optical technique that can provide a noninvasive and quantitative method for characterizing the absorption and scattering properties of biological tissues. Here, we compare three fiber-based diffuse reflection spectroscopy systems that were assembled to create a light-weight, portable, and robust optical spectrometer that could be easily translated for repeated and reliable use in mobile settings. The three systems were built using a broadband light source and a compact, commercially available spectrograph. We tested two different light sources and two spectrographs (manufactured by two different vendors). The assembled systems were characterized by their signal-to-noise ratios, the source-intensity drifts, and detector linearity. We quantified the performance of these instruments in extracting optical properties from diffuse reflectance spectra in tissue-mimicking liquid phantoms with well-controlled optical absorption and scattering coefficients. We show that all assembled systems were able to extract the optical absorption and scattering properties with errors less than 10%, while providing greater than ten-fold decrease in footprint and cost (relative to a previously well-characterized and widely used commercial system). Finally, we demonstrate the use of these small systems to measure optical biomarkers in vivo in a small-animal model cancer therapy study. We show that optical measurements from the simple portable system provide estimates of tumor oxygen saturation similar to those detected using the commercial system in murine tumor models of head and neck cancer.     

Fractional Fourier transforms, symmetrical lens systems, and their cardinal planes

We study the relation between optical lens systems that perform a fractional Fourier transform (FRFT) with the geometrical cardinal planes. We demonstrate that lens systems symmetrical with respect to the central plane provide an exact FRFT link between the input and output planes. Moreover, we show that the fractional order of the transform has real values between 0 and 2 when light propagation is produced between principal planes and antiprincipal planes, respectively. Finally, we use this new point of view to design an optical lens system that provides FRFTs with variable fractional order in the range (0,2) without moving the input and output planes.     

Pseudo-orbits,stationary measures and metastability

We characterize absolutely continuous stationary measures (acsms) of randomly perturbed dynamical systems in terms of pseudo-orbits linking the ergodic components of absolutely continuous invariant measures (acims) of the unperturbed system. We focus on those components, called least elements, which attract pseudo-orbits. Under the assumption that the transfer operators of both systems, the random and the unperturbed, satisfy a uniform Lasota–Yorke inequality on a suitable Banach space, we show that each least element is in a one-to-one correspondence with an ergodic acsm of the random system.     

Curvature sensors, adaptive optics, and Neumann boundary conditions

We consider the Neumann boundary-value problem for curvature adaptive optics systems. We show that, because curvature sensors average over extended regions of the wave front, inconsistent data for the solution of the Neumann problem result when the measurements are treated as local. Because this inconsistency is generally resolved passively in the adaptive mirror itself, it can be interpreted as an uncontrolled degree of freedom of the system. We offer several procedures for treating the data in a more consistent fashion.     

New State of Matter: Heavy Fermion Systems,Quantum Spin Liquids,Quasicrystals, Cold Gases,and High-Temperature Superconductors

We report on a new state of matter manifested by strongly correlated Fermi systems including various heavy fermion (HF) metals, two-dimensional quantum liquids such as \(^3\)He films, certain quasicrystals, and systems behaving as quantum spin liquids. Generically, these systems can be viewed as HF systems or HF compounds, in that they exhibit typical behavior of HF metals. At zero temperature, such systems can experience a so-called fermion condensation quantum phase transition (FCQPT). Combining analytical considerations with arguments based entirely on experimental grounds, we argue and demonstrate that the class of HF systems is characterized by universal scaling behavior of their thermodynamic, transport, and relaxation properties. That is, the quantum physics of different HF compounds is found to be universal, emerging irrespective of the individual details of their symmetries, interactions, and microscopic structure. This observed universal behavior reveals the existence of a new state of matter manifest in HF compounds. We propose a simple, realistic model to study the appearance of flat bands in two-dimensional ensembles of ultracold fermionic atoms, interacting with coherent resonant light. It is shown that signatures of these flat bands may be found in peculiarities in their thermodynamic and spectroscopic properties. We also show that the FCQPT, in generating flat bands and altering Fermi surface topology, is an essential progenitor of the exotic behavior of the overdoped high-temperature superconductors represented by \(\hbox {La}_{2-x}\hbox {Sr}_{x}x\hbox {CuO}_4\), whose superconductivity differs from that predicted by the classical Bardeen–Cooper–Schrieffer theory. The theoretical results presented are in good agreement with recent experimental observations, closing the colossal gap between these empirical findings and Bardeen–Cooper–Schrieffer-like theories.     

Field quantization,photons and non-Hermitean modes

Field quantization in unstable optical systems is treated by expanding the vector potential in terms of non-Hermitean (Fox-Li) modes. We define non-Hermitean modes and their adjoints in both the cavity and external regions and make use of the important bi-orthogonality relationships that exist within each mode set. We employ a standard canonical quantization procedure involving the introduction of generalized coordinates and momenta for the electromagnetic (EM) field. Three-dimensional systems are treated, making use of the paraxial and monochromaticity approximations for the cavity non-Hermitean modes. We show that the quantum EM field is equivalent to a set of quantum harmonic oscillators (QHOs), associated with either the cavity or the external region non-Hermitean modes, and thus confirming the validity of the photon model in unstable optical systems. Unlike in the conventional (Hermitean mode) case, the annihilation and creation operators we define for each QHO are not Hermitean adjoints. It is shown that the quantum Hamiltonian for the EM field is the sum of non-commuting cavity and external region contributions, each of which can be expressed as a sum of independent QHO Hamiltonians for each non-Hermitean mode, except that the external field Hamiltonian also includes a coupling term responsible for external non-Hermitean mode photon exchange processes. The non-commutativity of certain cavity and external region annihilation and creation operators is associated with cavity energy gain and loss processes, and may be described in terms of surface integrals involving cavity and external region non-Hermitean mode functions on the cavity-external region boundary. Using the essential states approach and the rotating wave approximation, our results are applied to the spontaneous decay of a two-level atom inside an unstable cavity. We find that atomic transitions leading to cavity non-Hermitean mode photon absorption are associated with a different coupling constant to that for transitions leading to photon emission, a feature consequent on the use of non-Hermitean mode functions. We show that under certain conditions the spontaneous decay rate is enhanced by the Petermann factor.     

大功率超声清洗机研制中的一些技术问题

本文介绍了微机控制的大功率超声清洗机研制的一些技术问题，探索了单片机在功率超声中的应用，提出了大功率超声振动子的一种新的设计方法，解决了一些影响振动子性能的关键问题，对于楔形工具头的超声振动子平均振幅的测量以及与同类机型的比较成为可能，文中还给出了部分比较曲线，实际测量证明，本文所述的系统比同类进口机平均振幅提高一倍以上，对工件的清效果明显优于进口机。     

Some results on the entropy of non-autonomous dynamical systems

In this paper, we advance the entropy theory of discrete non-autonomous dynamical systems that was initiated by Kolyada and Snoha in 1996. The first part of the paper is devoted to the measure-theoretic entropy theory of general topological systems. We derive several conditions guaranteeing that an initial probability measure, when pushed forward by the system, produces an invariant measure sequence whose entropy captures the dynamics on arbitrarily fine scales. In the second part of the paper, we apply the general theory to the non-stationary subshifts of finite type, introduced by Fisher and Arnoux. In particular, we give sufficient conditions for the variational principle, relating the topological and measure-theoretic entropy, to hold.     

Nanotube Boiler: Attogram Copper Evaporation Driven by Electric Current, Joule Heating, Charge, and Ionization

Controlled copper evaporation at attogram level from individual carbon nanotube (CNT) vessels, which we call nanotube boilers, is investigated experimentally and theoretically. We compared the evaporation modes induced by electric current, Joule heating, charge, and ionization in these CNT boilers, which can serve as sources for mass transport and deposition in nanofluidic systems. Experiments and molecular dynamics simulations show that the most effective method for evaporation is by positively ionizing the encapsulated copper; therefore, an electrostatic field can be used to guide the flow.     

Some amorphous alloys in Zr-Ru-Mo and Zr-Ru-W systems prepared by rapid solidification

All binary systems of the ternary systems Zr-Mo-Ru and Zr-W-Ru show at least one eutectic point. This indicates the existence of low melting eutectic alloys in these ternary systems (∼ 1200–1300°C). As starting materials, homogeneous Zr-Mo-Ru and Zr-W-Ru samples of different compositions were prepared by rapid solidification (∼10⁶Ks⁻¹) in a splat-cooling apparatus with a rf levitation coil and a high-velocity two-piston arrangement driven by solenoids. The possibility of obtaining alloys in amorphous state from low-melting areas of these ternary systems with the addition of boron or silicon has been investigated.     

Some ways to increase flexibility in manufacturing systems

In recent years, many flexible manufacturing systems have been or are being developed. FMS is important in order to adapt to severe changes in market and technology and also to increase productivity. In this paper, the evaluation variables of flexibility are proposed and factors improving the flexibility of single-stage production systems with different characters are discussed. However, most production systems are multi-stage mixed type systems. This paper also points out the characteristics of the amplification of multi-stage production systems as one of the important factors affecting the flexibility and productivity of the systems. Furthermore, some ways of reducing the amplification by the ordering systems are also presented. The multi-stage ordering models discussed here are simplified, neglecting the characteristics of the single production systems which make up total multi-stage production systems and neglecting parameters concerning transportation and material flows. The flexible manufacturing system of today is treated as a stage which is part of an overall system consisting of a succession of production stages with difference characteristics. However, it should also be considered as a way to increase the flexibility and productivity of the system as a whole.     

Propagation of fluctuations in biochemical systems, II: Nonlinear chains

We consider biochemical reaction chains and investigate how random external fluctuations, as characterised by variance and coefficient of variation, propagate down the chains. We perform such a study under the assumption that the number of molecules is high enough so that the behaviour of the concentrations of the system is well approximated by differential equations. We conclude that the variances and coefficients of variation of the fluxes will decrease as one moves down the chain and, through an example, show that there is no corresponding result for the variances of the concentrations of the chemical species. We also prove that the fluctuations of the fluxes as characterised by their time averages decrease down reaction chains. The results presented give insight into how biochemical reaction systems are buffered against external perturbations solely by their underlying graphical structure and point out the benefits of studying the out-of-equilibrium dynamics of systems.     

Some considerations of fracture mechanics applications in ships design,construction and operation

The structural performance demands placed on present day high performance ships and some types of shipboard liquid natural gas (LNG) cargo containment systems requires the use of new materials which can perform under higher loadings and severe service environments. Such critical designs must be accomplished while maintaining a high structural reliability and decreased life-cycle costs. For high performance ships these critical designs can be accomplished with damage-tolerant design procedures which provide for redundant load paths and/or crack arrest capabilities. The ship construction and maintenance requirements must also be included in the design because of their effect on the structural life performance of the high performance ship. For shipboard LNG cargo containment systems modified LEFM (linear elastic fracture mechanics) is used in the design phase.The paper discusses the philosophy of a fatigue and fracture control plan for high performance ships and the use of modified LEFM for shipboard LNG cargo containment systems. Current applications of a fatigue and fracture control plan are discussed. The types of shipboard cargo containment systems designed using the modified LNG approach are described.The paper addresses the need for an integrated life time quality assurance program. Such a program is shown to require a synthesis of materials characterization, structural analysis and nondestructive testing. A service performance feedback loop will assist the designers in continually improving the then governing design criteria. In addition, areas requiring further work and possible future applications for fatigue and fracture analysis will be discussed.     

Some peculiarities of (Hg,Cd) Te liquid-phase epitaxial growth in a semi-closed,two-zone system

A semi-closed, two-zone system for (Hg, Cd) Te liquid-phase epitaxy (LPE) is described which has the main advantage of closed systems: namely, there is no loss of mercury from the solution. The system retains all the good properties of open systems, i.e. it simplifies the repeated use. One other advantage is the possibility of rinsing the system in pure hydrogen. In order to establish the experimental conditions for obtaining the LPE (Hg, Cd) Te layers of desired composition on the CdTe or CdZnTe substrates, it is first necessary to study the problems of maintenance of the already homogenized solution composition, homogenization rate, and the epitaxial layers' composition changes as a function of solution supercooling.     

Some Formulation Properties of Lapachol, A Potential Oncolytic Agent of Natural Origin

Lapachol is a naphthaquinone of natural origin with reported oncolytic activity. However, earlier antitumor studies were inhibited by inadequate blood levels, allegedly due to formulation difficulties.

This present study shows that water solubility is markedly influenced by pH, varying from 1.5 μg/mL at pH 4.0 to 5 mg/mL at pH 10.0.

Evaluation of mixed solvent systems demonstrated that up to 30 mg/mL could be dissolved in polyethylene glycol (PEG) 400. Aqueous PEG 400 solutions of lapachol were stable at refrigerator temperatures but deteriorated when exposed to light or autoclaving. Aqueous ethanol or propylene glycol are realistic alternative solvent systems for injectable lapachol solutions that may be sterilized by autoclaving.

Phosphatide stabilized triglyceride emulsions are broken down by lapachol, suggesting an interfacial interaction between the phosphatide and the lapachol in the aqueous phase.     

关于一些非牛顿流体(英文)

我们考虑了满足Clausius-Puhem不等式的一类二维Rivlin Ericksen流体.对于严格孤立的流体,我们证明了如果处于均衡时Helmhdtz自由能量非最小,则在一定条件下所有原始扰动不仅会放大而且会增加.这些结果推广了Fosclish Rajagopal在1982年得到的二维Rivlin Ericksen流体的一种特例一二等级流体的相关结果.