一种接近最小热条件的精馏塔优化分析

建立了一种每块板上都允许存在中间换热器的接近最小热条件的复杂精馏塔模型,根据精馏过程的火用损最小,优化了回流比和塔内换热负荷。对于影响精馏过程用能的因素:理论板数、进料位置、进料热状况进行了分析,得出了,要设计一个节能的精馏塔如何选择合适的理论板数、进料位置及进料的热状况的方法。并比较分析了该塔和具有相同理论板数的传统简单塔的传质推动力,发现在这种塔的整个塔内的传质推动力比较平均,而整个精馏过程的火用损比简单塔的小。     

Dynamic Cesaro-Wardrop equilibration in networks

We analyze a routing scheme for a broad class of networks which converges (in the Cesaro sense) with probability one to the set of approximate Cesaro-Wardrop equilibria, an extension of the notion of a Wardrop equilibrium. The network model allows for wireline networks where delays are caused by flows on links, as well as wireless networks, a primary motivation for us, where delays are caused by other flows in the vicinity of nodes. The routing algorithm is distributed, using only the local information about observed delays by the nodes, and is moreover impervious to clock offsets at nodes. The scheme is also fully asynchronous, since different iterates have their own counters and the orders of packets and their acknowledgments may be scrambled. Finally, the scheme is adaptive to the traffic patterns in the network. The demonstration of convergence in a fully dynamic context involves the treatment of two-time scale distributed asynchronous stochastic iterations. Using an ordinary differential equation approach, the invariant measures are identified. Due to a randomization feature in the algorithm, a direct stochastic analysis shows that the algorithm avoids non-Wardrop equilibria. Finally, some comments on the existence, uniqueness, stability, and other properties of Wardrop equilibria are made.     

介观压光型加速度传感器

对于光子晶体而言,角度、厚度、周期数等对其透射率产生很大的影响,但相对于这些,轴向压力的影响更大。通过对介观压光效应的应用,用光子晶体代替传统的力敏电阻器,设计一种新型的加速度传感器,使其测量精度得到很大的提高,测量量程也有很大的改进。所设计的加速度传感器采用四端固支梁结构,有效地消除了偏轴效应,具有很好的稳定性。利用ANSYS软件对所设计的结构进行了应力模拟分析和三阶模态分析。这种加速度传感器具有很大的优势,可以运用到以后的航天、军事、车辆等领域。     

Microprocessor-controlled mixing system for rebreathing equilibration

A simple, economic, and accurate microprocessor system for the determination of mixed venous PCO2 has been described. Through the automatic gas mixing system, it is possible to facilitate the use of the rebreathing equilibration technique for the purpose of cardiac output calculations. It was also possible to flush the rebreathing bag within a brief time, providing the investigator with an automatic three-way valve driven by a solenoid.     

Mesoscopic analysis of networks with genetic algorithms

The detection of communities is an important problem, intensively investigated in recent years, to uncover the complex interconnections hidden in networks. In this paper a genetic based approach to discover communities in networks is proposed. The algorithm optimizes a simple but efficacious fitness function able to identify densely connected groups of nodes with sparse connections between groups. The method is efficient because the variation operators are modified to take into consideration only the actual correlations among the nodes, thus sensibly reducing the search space of possible solutions. Experiments on synthetic and real life networks show the ability of the method to successfully detect the network structure.     

Optimization of the equilibration algorithm for a sampling converter

Several ways of reducing acquisition intervals and errors in sampling transformations using up-and-down and statistical methods are suggested.     

Diffusion and equilibration in 2D fluid codes

The problems associated with diffusion and rapid equipartition of energy between electrons and ions in two-dimensional fluid codes are investigated numerically. It is shown that a commonly used procedure of averaging the exchange term over the hydrodynamic timescales of interest can be problematic in modelling the equipartition unless very small timesteps are used. A simple model, in which the electron and ion diffusion equations are solved simultaneously, is found to prevent the problems introduced by the average exchange model. The simultaneous solution method increases storage requirements as large scale matrix equations have to be solved. Various algorithms are considered in terms of the increase in storage and execution time required to implement the simultaneous solution method. In particular, a new simple point-iterative algorithm is introduced which is particularly efficient at solving the above problem and offers much scope when applied as a solution method for multi-species diffusion and equilibration problems.     

Visibility Equalizer Cutaway Visualization of Mesoscopic Biological Models

In scientific illustrations and visualization, cutaway views are often employed as an effective technique for occlusion management in densely packed scenes. We propose a novel method for authoring cutaway illustrations of mesoscopic biological models. In contrast to the existing cutaway algorithms, we take advantage of the specific nature of the biological models. These models consist of thousands of instances with a comparably smaller number of different types. Our method constitutes a two stage process. In the first step, clipping objects are placed in the scene, creating a cutaway visualization of the model. During this process, a hierarchical list of stacked bars inform the user about the instance visibility distribution of each individual molecular type in the scene. In the second step, the visibility of each molecular type is fine‐tuned through these bars, which at this point act as interactive visibility equalizers. An evaluation of our technique with domain experts confirmed that our equalizer‐based approach for visibility specification is valuable and effective for both, scientific and educational purposes.     

Progressive equilibration algorithms: The case of linear transaction costs

In this paper we consider the solution of large-scale market equilibrium problems with linear transaction costs which can be formulated as strictly convex quadratic programming problems, subject to supply and demand constraints. In particular, we introduce two new classes of progressive equilibration algorithms, which retain the simplicity of the original cyclic ones in that at each step either the supply or demand market equilibrium subproblem can be solved explicitly in closed form. However, rather than equilibrating the markets in cyclic manner, the next market to be equilibrated is selected in a more strategic fashion.We then provide qualitative results for the entire family of progressive equilibration algorithms, i.e., the rate of convergence and computational complexity. We discuss implementation issues and give computational results for large-scale examples in order to illustrate and give insights into the theoretical analysis. Furthermore, we show that one of the new classes of algorithms, the good-enough one, is computationally the most efficient. Theoretical results are important in that the relative efficiency of different algorithms need no longer be language, machine, or programmer dependent. Instead, the theory can guide both practitioners and researchers in ensuring that their implementation of these algorithms is, indeed, good.Since an equivalent quadratic programming problem arises in a certain class of constrained matrix problems, our results can be applied there, as well. Finally, since more general asymmetric multicommodity market equilibrium problems can be solved as series of the type of problems considered here, the result$ are also applicable to such equilibrium problems.     

Landscape estimation of solidity version usage on Ethereum via version identification

The creative introduction of the smart contracts in Ethereum, which are Turing-complete programs, boosted blockchain to the second generation. Meantime, the specifically designed young and fast-evolving programming languages, such as Solidity, become the key factors behind smart contracts being the breeding ground of ubiquitous defects. As many contract defects occur within certain compiler versions, knowing the specific compiler version used to generate the contract's bytecode, facilitates the design of more targeted defect detection approaches, and provides ways to estimate the risks faced of invoking it. To this end, we propose VSmart (compiler Version identification for Smart contract), which takes in the bytecode of the smart contract to be analyzed and outputs the major compiler version used to produce it. The basic idea is to leverage deep neural networks to grasp version-indicative features from contracts' normalized opcode sequences, and train classifiers on a data set consisting of 131,546 smart contracts with ground-truth labels we collected from Etherscan. The performance evaluation conducted shows that VSmart achieves nearly 98% accuracy in identifying major Solidity compiler versions. Further, on the basis of VSmart, we perform an empirical study on the distribution of the Solidity compiler versions on a wild data set consisting of 15,326,672 nontrivial smart contracts actually deployed on the Ethereum blockchain. The landscape estimation results show that the Solidity version distribution is rather imbalanced, with Solidity 0.4 being the most popular one; and the developers' Solidity usage practices conflict with the official's suggestion of always using the latest version, while they tend to gradually switch to newer versions.     

Mesoscopic simulations of electroosmotic flow and electrophoresis in nanochannels

We review recent dissipative particle dynamics (DPD) simulations of electrolyte flow in nanochannels. A method is presented by which the slip length δB at the channel boundaries can be tuned systematically from negative to infinity by introducing suitably adjusted wall-fluid friction forces. Using this method, we study electroosmotic flow (EOF) in nanochannels for varying surface slip conditions and fluids of different ionic strength. Analytic expressions for the flow profiles are derived from the Stokes equation, which are in good agreement with the numerical results. Finally, we investigate the influence of EOF on the effective mobility of polyelectrolytes in nanochannels. The relevant quantity characterizing the effect of slippage is found to be the dimensionless quantity κδB, where 1/κ is an effective electrostatic screening length at the channel boundaries.     

Interference of Mesoscopic Particles: Quantum–Classical Transition

We analyze the double slit interference of a mesoscopic particle. We calculate the visibility of the interference pattern in the far field case, introduce a characteristic temperature that defines the onset to decoherence and scrutinize the conditions that must be satisfied for an interference experiment to be possible.     

Dephasing of Quantum Bits by a Quasi-Static Mesoscopic Environment

We examine coherent processes in a two-state quantum system that is strongly coupled to a mesoscopic spin bath and weakly coupled to other environmental degrees of freedom. Our analysis is specifically aimed at understanding the quantum dynamics of solid-state quantum bits such as electron spins in semiconductor structures and superconducting islands. The role of mesoscopic degrees of freedom with long correlation times (local degrees of freedom such as nuclear spins and charge traps) in qubit-related dephasing is discussed in terms of a quasi-static bath. A mathematical framework simultaneously describing coupling to the slow mesoscopic bath and a Markovian environment is developed and the dephasing and decoherence properties of the total system are investigated. The model is applied to several specific examples with direct relevance to current experiments. Comparisons to experiments suggests that such quasi-static degrees of freedom play an important role in current qubit implementations. Several methods of mitigating the bath-induced error are considered.Dedicated to Anton Zeilinger, whose work has inspired exploration of quantum phenomenon in many avenues of physics and beyond.     

细观元胞自动机与三分子反应模拟

为了刻划多组分宏观系统中粒子间的复杂且随机的局部相互作用,作者打破现有元胞自动机的局限,借用粗粒化的思想,将多个状态变量引入随机元胞自动机,提出了称之为“细观元胞自动机”的一种扩展的元胞自动机概念模型,然后将该模型应用于Ｂｒｕｓｓｅｌａｔｏｒ的计算机模拟,制定了４组分系统中粒子的随机运动和反应碰撞等的演化规则,建立了三分子反应的二维地胞自动机模型,并在计算机上对该模型成功地进行了动态模拟。