城市道路网总体容量估算的衍生割集方法及应用

本文基于现代城市道路网总体容量的估算和评价问题，提出了一种新的网络流算法衍生割集网络极大流算法（Evolving Cut Set Method.简称ECS法），实例表明，这种方法是有效的。     

Strain-induced large fluctuations during stress relaxation in polymer melts observed by small-angle neutron scattering. “Lozenges”, “butterflies”, and related theory

We discuss the neutron scattering features of melts containing a fraction of labeled chains, and of rubbers containing a fraction of deuterated paths along several successive elementary chains. Both types of material are studied during relaxation after a fast deformation in very similar conditions. An unusual feature is the shape of the anisotropic scattering as visualized on a bidimensional detector: the isointensity lines have the shape of lozenges. A detailed review of various cases makes this appear as a general feature in SANS scattering from melts and rubbers in a state of partially relaxed deformation. We then describe results for mixtures of small labeled chains inside matrices of large entangled chains or crosslinked matrices: we find another unusual shape of the isointensity levels, called butterfly. We propose the lozenges to be a combination of the classical elliptical scattering with a butterfly scattering, which has a main axis orthogonal to the main axis of the ellipses. We discuss in more details the origin of the butterfly effect, by following two tracks: the first is several theories about demixing under strain, including influence of the strain on the enthalpic, elastic, and conformational terms of the free energy of mixing. The second track is the influence of heterogeneities in crosslinked materials. An explanation which would be common to the case of crosslinked and uncrosslinked material remains to be established.     

Derivation and analysis of an effective model for biofilm growth in evolving porous media

The present article deals with the growth of biofilms produced by bacteria within a saturated porous medium. Starting from the pore‐scale, the process is essentially described by attachment/detachment of mobile microorganisms to a solid surface and their ability to build biomass. The increase in biomass on the surface of the solid matrix changes the porosity and impedes flow through the pores. Using formal periodic homogenization, we derive an averaged model describing the process via Darcy's law and upscaled transport equations with effective coefficients provided by the evolving microstructure at the pore‐scale. Assuming, that the underlying pore geometry may be described by a single parameter, for example, porosity, the level set equation locating the biofilm‐liquid interface transforms into an ordinary differential equation (ODE) for the parameter. For such a setting, we state significant analytical and algebraic properties of these effective parameters. A further objective of this article is the analytical investigation of the resulting coupled PDE–ODE model. In a weak sense, unique solvability either global in time or at least up to a possible clogging phenomenon is shown. Copyright © 2016 John Wiley & Sons, Ltd.     

Monte Carlo Simulation of Contaminant Transport: I. Long-range Correlations in Fracture Conductivity

We develop a network model of fractures, and use the model to study transport of contaminants by groundwater through natural geological media. The fractures are narrow rectangular channels between large flat parallel plates, which are embedded in the surrounding rock matrix. The fracture-permeabilities and the fracture-widths are obtained from both uniform and fBm distributions. The pressure distribution in the network, and subsequently the velocity of groundwater in each channel, is obtained. The transport problem in an individual fracture is solved in Laplace space using the realized groundwater velocities and network mass conservation. The transform space solutions are then inverted to real time using a fast and efficient inversion algorithm. Monte Carlo simulations are then carried out by repeating the above procedure for a large number of realizations. The main focus of this study is to explore the effects correlated fracture-permeabilities and fracture-widths have on the transport of contaminants. While the primary transport mechanism is convection, we also study such processes as adsorption onto the fracture surface, and radioactive decay. We show how these phenomena, individually and in combination with one another, affect the overall transport process. In addition, we investigate the nature of the mixing zone, and discuss how these results can be helpful in developing remediation techniques for a contaminated site.     

Discrimination of Acori Tatarinowii Rhizoma and Acori Calami Rhizoma based on quantitative gas chromatographic fingerprints and chemometric methods

This study was conducted to investigate the chemical differences between Acori Tatarinowii Rhizoma and Acori Calami Rhizoma using gas chromatography with mass spectrometry and chemometric methods. Quantitative fingerprints were established. A total of 90 volatile compounds were identified and quantified using heuristic evolving latent projection and retention index. An efficient model based on partial least squares‐discriminant analysis coupled with variable iterative space shrinkage approach was developed to distinguish Acori Tatarinowii Rhizoma from Acori Calami Rhizoma. The correct rate was 95.83%, and the area under the receiver operating characteristic curve was 100%. Finally, three volatiles, namely, camphor, longicyclene, and δ‐cadinene, were selected as key discrimination factors between Acori Tatarinowii Rhizoma and Acori Calami Rhizoma. The proposed protocol can serve as a valid strategy for quality control and screening of potential bioactive components of herbal medicines.     

A new local-world evolving network model

In some real complex networks, only a few nodes can obtain the global information about the entire networks, but most of the nodes own only local connections therefore own only local information of the networks. A new local-world evolving network model is proposed in this paper. In the model, not all the nodes obtain local network information, which is different from the local world network model proposed by Li and Chen (LC model). In the LC model, each node has only the local connections therefore owns only local information about the entire networks. Theoretical analysis and numerical simulation show that adjusting the ratio of the number of nodes obtaining the global information of the network to the total number of nodes can effectively control the valuing range for the power-law exponent of the new network. Therefore, if the topological structure of a complex network, especially its exponent of power-law degree distribution, needs controlling, we just add or take away a few nodes which own the global information of the network.     

The Spread of Ideas in a Network—The Garbage-Can Model

The main goal of our work is to show how ideas change in social networks. Our analysis is based on three concepts: (i) temporal networks, (ii) the Axelrod model of culture dissemination, (iii) the garbage can model of organizational choice. The use of the concept of temporal networks allows us to show the dynamics of ideas spreading processes in networks, thanks to the analysis of contacts between agents in networks. The Axelrod culture dissemination model allows us to use the importance of cooperative behavior for the dynamics of ideas disseminated in networks. In the third model decisions on solutions of problems are made as an outcome of sequences of pseudorandom numbers. The origin of this model is the Herbert Simon’s view on bounded rationality. In the Axelrod model, ideas are conveyed by strings of symbols. The outcome of the model should be the diversity of evolving ideas as dependent on the chain length, on the number of possible values of symbols and on the threshold value of Hamming distance which enables the combination.     

直观推导式演进特征投影法对酶催化反应的过程分析

以丁香酸(syringic acid)为模型化合物, 研究了漆酶(laccase)催化降解木质素(lignin)的复杂生化反应过程, 设计了一种反应过程动态量测系统, 该系统可以在5 s的时间间隔测定反应体系在190～800 nm波长范围内的实时光谱信息. 利用固定窗口因子分析-直观推导式演进特征投影法(FSMWEFA-HELP), 解析反应过程中测得的实时动力学光谱数据矩阵, 得到反应物和中间体的数目及其浓度的变化和纯物质的光谱曲线, 并推导出合理的反应机理. 将所得结果与多元曲线分辨-交替最小二乘(MCR-ALS)方法进行了比较.     

Dielectric studies of chain dynamics in homogeneous semi‐interpenetrating polymer networks

Semi‐interpenetrating polymer networks (semi‐IPNs) were prepared from linear polyurethane (PUR) and polycyanurate (PCN) networks. Wide‐angle X‐ray scattering measurements showed that the IPNs were amorphous, and differential scanning calorimetry and small‐angle X‐ray scattering measurements suggested that they were macroscopically homogeneous. Here we report the results of detailed studies of the molecular mobility in IPNs with PUR contents greater than or equal to 50% via broadband dielectric relaxation spectroscopy (10⁻²–10⁹ Hz, 210–420 K) and thermally stimulated depolarization current techniques (77–320 K). Both techniques gave a single α relaxation in the IPNs, shifting to higher temperatures in isochronal plots with increasing PCN content, and provided measures for the glass‐transition temperature (T_g) close to and following the calorimetric T_g. The dielectric response in the IPNs was dominated by PUR. The segmental α relaxation, associated with the glass transition and, to a lesser extent, the local secondary β and γ relaxations were analyzed in detail with respect to the timescale, the shape of the response, and the relaxation strength. The α relaxation became broader with increasing PCN content, the broadening being attributed to concentration fluctuations. Fragility decreased in the IPNs in comparison with PUR, the kinetic free volume at T_g increased, and the relaxation strength of the α relaxation, normalized to the same PUR content, increased. The results are discussed in terms of the formation of chemical bonds between the components, as confirmed by IR, and the reduced packing density of PUR chains in the IPNs. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 3070–3087, 2000     

Primary and secondary dielectric relaxations in semi-crystalline and amorphous starch

The thermally stimulated depolarization current technique, TSDC, has been used to study the dielectric relaxations in cassava starch on semi-crystalline and amorphous samples. The A-type structure was observed by WAXS experiments and the variation of the crystallinity as a function of the moisture content, h, was followed on native starch. Retrogradation of the amorphous sample occurred at room temperature after 4 weeks in a closed vessel with a water activity 97.3%. In these conditions the humidity content reached a value of 28.5 wt% dry base and the crystallinity degree was comparable to that of the native starch. Three secondary relaxation modes were detected and attributed to short range orientations of polar groups and to main chain restricted motion. The influence of the moisture plasticization effect on the relaxation parameters of the local modes, was determined by decomposing the global TSDC curve in elementary Debye peaks with Arrhenius relaxation times. The main relaxation, α, which is proposed to be the dielectric manifestation of the dynamic glass transition, sweeps a wide temperature interval around room temperature as the sample dries, shifting to higher temperatures as a result of the plasticization of the polysaccharide by water molecules. The α peak deconvolution lead to the 2D relaxation time distribution and Vogel-Tammann-Fulcher parameters were obtained confirming the cooperative character of this mode. The transformed sample showed a bimodal distribution of segmental relaxation times that is interpreted as the existence of a heterogeneous amorphous phase: the mobile one which is similar to the original disordered phase present in semi-crystalline native starch and a more restricted one originated by the disruption of the crystalline lamellae during the pre-gelatinization process.