Tent map as an abstract model of open system evolution

The irreversible equations of thermodynamic transport phenomena are changed to tent mapping. It is shown that a tent map may serve as a model of an open system capable of self-organization and evolution.     

A kinetic study of an advanced reburning process

The possibility of a positive synergism among flue gas recirculation, staged combustion and selective non-catalytic reduction technologies to achieve N-containing emission reductions has been investigated by simulating a 320 MW industrial-scale furnace boiler. A detailed chemical kinetic scheme coupled with a simplified fluid dynamic of the system has allowed us to compare the effectiveness of ammonia and isocyanic acid in removing N-containing pollutant emitted (NPE) with hot exhausts. By keeping the same flue gas composition for both cases, the effect of temperature and the impact of different amounts of NH3 and HNCO injected in the final combustion stage has been analysed. Ammonia was the most effective reducing agent for the particular conditions examined. Due to its high reactivity, the maximum effectiveness of the NH3-promoted process occurs at 940 K and an NH3 molar ratio of about 1.25. NH2 dominates the process mainly following two paths: N2 can be produced from direct interaction between NH2 and NO or via intermediate formation of NNH. On the other hand, HNCO is less effective than ammonia, owing to the influence of the particular radical environment within the boiler. HNCO oxidation is influenced by the amine radical pool which partly contributes to N2 formation but is, at the same time, an important source of NOx in the conditions analysed.     

Parton evolution as a branching process

The evolution of parton distributions in high-energy scattering is described using the methods of branching processes. Exclusive, inclusive and multiplicity distributions can be simply obtained from a functional form of the evolution equations. Previous results derived from leading logarithmic terms in perturbation theory are verified. As a new application, we calculate the multiplicity distribution of partons with momenta above a given cutoff.     

Theory of the kinetic effects in an electron-phonon system

The method of [3] is applied to find the electrical conductivity , the thermo-emf , and the thermal conductivity x of a nondegenerate electron gas, with allowance for electron scattering at optical and acoustic lattice vibrations. The Wiedemann-Franz law is shown to apply for the limiting cases of low and high temperatures.We are indebted to Professor A. G. Samoilovich for direction in this work.     

Fracture of a biopolymer gel as a viscoplastic disentanglement process

We present an extensive experimental study of mode-I, steady, slow crack dynamics in gelatin gels. Taking advantage of the sensitivity of the elastic stiffness to gel composition and history we confirm and extend the model for fracture of physical hydrogels which we proposed in a previous paper (Nature Mater. 5, 552 (2006)), which attributes decohesion to the viscoplastic pull-out of the network-constituting chains. So, we propose that, in contrast with chemically cross-linked ones, reversible gels fracture without chain scission.     

Mixing as an aggregation process

Experiments show how a stirred scalar mixture relaxes towards uniformity through an aggregation process. The elementary bricks are stretched sheets whose rates of diffusive smoothing and coalescence build up the overall mixture concentration distribution. The cases studied, in particular, include mixtures in two and three dimensions, with different stirring protocols and Reynolds numbers which all lead to a unique family of concentration distributions stable by self-convolution, the signature of the aggregation mechanism from which they originate.     

Simulation analysis of an active cancellation stealth system

Active cancellation stealth is a smart signal blanking method, that it has become an important developing direction on modern stealth technology. In order to further explore the active cancellation stealth technology, we are considering the detection and cancellation of receiving/transmitting antenna pattern is different. Put forward active cancellation system simulation structure diagram based on MATLAB/SIMULINK, where the phased array radar system as the modelling object, and established the active cancellation stealth system mathematical model based on digital radio frequency memory (DRFM) and the radar signal processing system of the coherent video simulation model, based on linear frequency modulation and radar coherent pulse signal simulation, verified the rationality and validity of the design, as the active cancellation stealth engineering technology laid the foundation.     

冷却速率对Lennard-Jones体系凝固过程中结构与动力学性质的影响

用分子动力学模拟方法研究了五种不同冷却速率对Lennard-Jones体系凝固过程中结构与动力学性质的影响。采用两种不同的方法来确定玻璃转变温度Tg,并且对结晶温度Tc、径向分布函数g(r)、均方位移函数MSD与扩散系数D、平均配位数进行比较分析。结果表明：冷却速率影响Lennard-Jones体系凝固过程中的结构。当使用足够高的冷却速率冷却时,体系发生玻璃化转变,而且冷却速率越快,玻璃转变温度越高;当冷却速率较小时,体系形成晶体,而且冷却速率越慢,结晶温度越高,结晶程度也越高。同时发现,冷却速率对扩散系数和平均配位数也有很大影响,二者在体系发生玻璃转变时都有一个缓变的过程,表明了过冷液相区的存在。     

Genetic code evolution as an initial driving force for molecular evolution

There is an intrinsic relationship between the molecular evolution in primordial period and genomic or proteomic properties of contemporary species. The genomic data may help us understand the driving force of evolution of life at a molecular level. In the absence of evidence, numerous problems in molecular evolution had to fall into a twilight zone of speculation and controversy in the past. Here we show that delicate variation patterns of genomic base compositions and amino acid frequencies resulted from the genetic code evolution, which underlies the molecular evolution. The theoretical results agree with the experimental observations very well, not only in the evolutionary trends of amino acid frequencies and genomic base compositions but also in many detailed characters. Inversely, the genomic data of contemporary species can help us unravel the genetic code chronology and amino acid chronology. Our results may shed light on the intrinsic mechanism of molecular evolution and the genetic code evolution.     

The evolution of polarization in an inhomogeneous birefringert,optically active medium

This note presents a method giving the change of polarization of an e.m. wave propagating in an inhomogeneous medium which is birefringent and optically active. The method has proved useful in a problem where the medium is a plasma with a magnetic field: it can be applied to other cases of interest, e.g. liquid crystals, as is here briefly discussed.     

Thermodynamic and kinetic properties of an icosahedral quasicrystalline phase in the Al-Pd-Tc system

The properties of a quasicrystalline phase in the Al-Pd-Tc system are studied for the first time. X-ray investigations demonstrate that the quasicrystalline phase in the Al₇₀Pd₂₁Tc₉ alloy has a face-centered icosahedral quasi-lattice with parameter a=6.514 ?. Annealing experiments have revealed that this icosahedral phase is thermodynamically stable. The heat capacity of an Al₇₀Pd₂₁Tc₉ sample is measured in the temperature range 3–30 K. The electrical resistivity and magnetic susceptibility are determined in the temperature range 2–300 K. The electrical resistivity is found to be high (600 μΩ cm at room temperature), which is typical of quasicrystals. The temperature coefficient of electrical resistivity is small and positive at temperatures above 50 K and negative at temperatures below 50 K. The magnetic susceptibility has a weakly paramagnetic character. The coefficient of linear contribution to heat capacity (γ=0.24 mJ/(g-atom K²)) and the Debye characteristic temperature (Θ=410 K) are determined. The origin of the specific features in the vibrational spectrum of the quasicrystals is discussed. __________ Translated from Fizika Tverdogo Tela, Vol. 42, No. 12, 2000, pp. 2113–2119. Original Russian Text Copyright ? 2000 by Mikheeva, Panova, Teplov, Khlopkin, Chernoplekov, Shikov.     

Chaotic synchronization as an information process

The chaotic synchronization phenomenon is studied from the information point of view. Synchronization of a chaos receiver by a chaos source is considered as copy recovery of the chaotic signal transmitted by the source. The main idea of this paper is to show that the necessary condition of chaotic synchronization is not the level of physical action of one system on another but the transmission of a certain volume of information on the chaotic process and, therefore, the capacity of the “communication channel” between the source and the receiver. This work was presented at the Summer Workshop “Dynamic Days” (Nizhny Novgorod, June 30–July 2, 1998). Institute of Radioengineering and Electronics of the Russian Academy of Sciences, Moscow, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 41, No. 12, pp. 1497–1509, December, 1998.     

Enzymatic synthesis of ascorbyl palmitate in ultrasound-assisted system: process optimization and kinetic evaluation

This work is focused on the optimization of reaction parameters for the synthesis of ascorbyl palmitate catalyzed by Candida antarctica lipase in different organic solvents under ultrasound irradiation. The sequential strategy of experimental design proved to be useful in determining the optimal conditions for reaction conversion in tert-butanol system using Novozym 435 as catalyst. The optimum production was achieved at 70°C, ascorbic acid to palmitic acid molar ratio of 1:9, enzyme concentration of 5 wt% at 3h of reaction, resulting in an ascorbyl palmitate conversion of about 27%. Reaction kinetics for ascorbyl palmitate production in ultrasound device showed that satisfactory reaction conversions (～26%) could be achieved in short reaction times (2h). The empirical kinetic model proposed is able to satisfactorily represent and predict the experimental data.     

Interior noise control with an active window system

An active window system to reduce the exterior noise sources, such as traffic noise and construction noise which enter rooms through open windows used for natural ventilation is proposed. The proposed system uses a feedforward control method for active noise control so as not to place the sensors and control sources inside the interior space of the building. For global noise reduction throughout the interior room, the control gains for feedforward control are calculated to minimize the total acoustic power of the new source, which is combined with the noise source corresponding to the open window and control sources on the window frame. The performance of the proposed system for directional exterior noise is confirmed with a scale-model experiment. The experimental results show that the proposed system can achieve a noise reduction of up to 10 dB for the entire room of the scale model regardless of the direction of the incident wave.     

Design considerations for an active feedback optical system

The optical processor proposed here consists basically of a coherent light source and two liquid crystal light valves, of which the first converts incoherent input patterns into coherent ones; the second operates entirely on coherent signals. It is shown that, if the valve operating point is correctly chosen and its transfer characteristic linearized, negative feedback is implemented around the second valve. The valves perform as active system components, because they modulate the source power by their driving signals.The linear dynamic range, modulation transfer function, and time transient behaviour of the system are briefly studied.