Bio-based production of chemical building blocks from renewable resources is an attractive alternative to petroleum-based platform chemicals. Metabolic pathway and strain engineering is the key element in constructing...
详细信息
Bio-based production of chemical building blocks from renewable resources is an attractive alternative to petroleum-based platform chemicals. Metabolic pathway and strain engineering is the key element in constructing robust microbial chemical factories within the constraints of cost effective production. Here we discuss how the development of computational algorithms, novel modules and methods, omics-based techniques combined with modeling refinement are enabling reduction in development time and thus advance the field of industrial biotechnology. We further discuss how recent technological developments contribute to the development of novel cell factories for the production of the building block chemicals: adipic acid, succinic acid and 3-hydroxypropionic acid.
A solution is presented in this note to the problem of improving the transient response of a MIMO nonlinear system driven by a VSC law, in the presence of large plant uncertainties. The proposed control scheme is give...
详细信息
A solution is presented in this note to the problem of improving the transient response of a MIMO nonlinear system driven by a VSC law, in the presence of large plant uncertainties. The proposed control scheme is given in terms of a supervisor and of a deterministic time-varying compensator, built using sliding-mode control and assuming a finite number of possible different configurations. The task of the supervisor is that of guiding the scanning among the elements of the family, according to a suitably defined experimental test. The proposed approach noticeably improves the performances of sliding-mode control in the presence of large plant uncertain ties, and has the substantial advantage of a great simplicity of design and implementation. Moreover, even in case of a large number of configurations constituting the stabilizing family, it has been shown to be able to attain the stabilizing controller in an arbitrarily small time interval. Another appealing feature of the paper consists in the inclusion of an intelligent adaptation scheme in the control algorithm.
Association rules mining is a popular data mining modeling tool. It discovers interesting associations or correlation relationships among a large set of data items, showing attribute values that occur frequently toget...
详细信息
Association rules mining is a popular data mining modeling tool. It discovers interesting associations or correlation relationships among a large set of data items, showing attribute values that occur frequently together in a given dataset. Despite their great potential benefit, current association rules modeling tools are far from optimal. This article studies how visualization techniques can be applied to facilitate the association rules modeling process, particularly what visualization elements should be incorporated and how they can be displayed. Original designs for visualization of rules, integration of data and rule visualizations, and visualization of rule derivation process for supporting interactive visual association rules modeling are proposed in this research. Experimental results indicated that, compared to an automatic association rules modeling process, the proposed interactive visual association rules modeling can significantly improve the effectiveness of modeling, enhance understanding of the applied algorithm, and bring users greater safisfaction with the task. The proposed integration of data and rule visualizations can significantly facilitate understanding rules compared to their nonintegrated counterpart.
A set of explicit finite difference schemes with large stencil was optimized to obtain maximum resolution characteristics for various spatial truncation orders. The effect of integral interval range of the objective f...
详细信息
A set of explicit finite difference schemes with large stencil was optimized to obtain maximum resolution characteristics for various spatial truncation orders. The effect of integral interval range of the objective function on the optimized schemes' performance is discussed. An algorithm is developed for the automatic determination of this integral interval. Three types of objective functions in the optimization procedure are compared in detail, which show that Tam's objective function gets the best resolution in explicit centered finite difference scheme. Actual performances of the proposed optimized schemes are demonstrated by numerical simulation of three CAA benchmark problems. The effective accuracy, strengths, and weakness of these proposed schemes are then discussed. At the end, general conclusion on how to choose optimization objective function and optimization ranges is drawn. The results provide clear understanding of the relative effective accuracy of the various truncation orders, especially the trade-off when using large stencil with a relatively high truncation order.
Audio segmentation is a basis for multimedia content analysis which is the most important and widely used application nowadays. An optimized audio classification and segmentation algorithm is presented in this paper t...
详细信息
Audio segmentation is a basis for multimedia content analysis which is the most important and widely used application nowadays. An optimized audio classification and segmentation algorithm is presented in this paper that segments a superimposed audio stream on the basis of its content into four main audio types: pure-speech, music, environment sound, and silence. An algorithm is proposed that preserves important audio content and reduces the misclassification rate without using large amount of training data, which handles noise and is suitable for use for real-time applications. Noise in an audio stream is segmented out as environment sound. A hybrid classification approach is used, bagged support vector machines (SVMs) with artificial neural networks (ANNs). Audio stream is classified, firstly, into speech and nonspeech segment by using bagged support vector machines;nonspeech segment is further classified into music and environment sound by using artificial neural networks and lastly, speech segment is classified into silence and pure-speech segments on the basis of rule-based classifier. Minimum data is used for training classifier;ensemble methods are used for minimizing misclassification rate and approximately 98% accurate segments are obtained. A fast and efficient algorithm is designed that can be used with real-time multimedia applications.
The imaginary part of the complex potential energy surface (CPES) provides the autoionization, Auger and ICD (Intermolecular Coulombic Decay) ionization decay rates as functions of the variations in the molecular elec...
详细信息
The imaginary part of the complex potential energy surface (CPES) provides the autoionization, Auger and ICD (Intermolecular Coulombic Decay) ionization decay rates as functions of the variations in the molecular electronic structure and geometry. We introduce here a novel approach which enables the calculations the molecular complex potential energy surfaces by the standard computational algorithms which were originally developed for calculating real PES of stable molecules. As an illustrative numerical example we have calculated the CPES for the molecular autoionization of hydrogen molecule, H-2[(1)Sigma(+)(g)] where the two electrons are doubly excited. (C) 2011 Elsevier B. V. All rights reserved.
Stabilization problem for a linear plant with time delay control is considered. A new method of the sliding mode control design minimizing the effects of system disturbances is presented. It is based on a combination ...
详细信息
Stabilization problem for a linear plant with time delay control is considered. A new method of the sliding mode control design minimizing the effects of system disturbances is presented. It is based on a combination of the well-known predictor-based sliding mode control algorithm with the recently developed invariant ellipsoid method. The theoretical results are supported by numerical simulations. (C) 2011 The Franklin Institute. Published by Elsevier Ltd. All rights reserved.
In the paper, taint analysis problem is considered. To solve it, static interprocedural context-, flow-, and object-sensitive algorithm is proposed. Characteristics of the algorithm are evaluated, and specific feature...
详细信息
In the paper, taint analysis problem is considered. To solve it, static interprocedural context-, flow-, and object-sensitive algorithm is proposed. Characteristics of the algorithm are evaluated, and specific features of the implementation of the algorithm on the basis of the LLVM compiler infrastructure are discussed. Results of evaluation are presented.
A plasma sheath generated around a hypersonic vehicle can be a serious obstacle to fixed-frequency communications, especially navigation systems. This paper studies the effects of a plasma sheath on a Beidou navigatio...
详细信息
A plasma sheath generated around a hypersonic vehicle can be a serious obstacle to fixed-frequency communications, especially navigation systems. This paper studies the effects of a plasma sheath on a Beidou navigation circular microstrip patch antenna. The dynamic stratified medium model method, which is based on the gradient of electron density profile curve, is employed to model the nonuniform plasma sheath. Using the algorithm calculation of the time-domain finite integration, the navigation antenna radiation pattern property is obtained, along with the changes in the reflection coefficient and input impedance properties. Results show that antenna pattern distortion, resonant frequency shift, and impedance mismatch caused by plasma are proportional to the electron density. The process of reentry blackout is also reproduced from the perspective of the antenna performance degradation. The inductor L and capacitor C (LC tuning circuit) impedance mismatch compensation scheme proposed is demonstrated to be effective and it can decrease return loss by 19.4dB under the most serious plasma environment, thus reducing signal reflection and enhancing navigation system performance.
Isolation from disturbances, particularly from foundations of high precision instruments, is achieved through either passive or active vibration control systems. Although a passive isolation system offers a simple and...
详细信息
Isolation from disturbances, particularly from foundations of high precision instruments, is achieved through either passive or active vibration control systems. Although a passive isolation system offers a simple and reliable means of protecting precision equipment from a vibration environment, it has performance limitations since its controllable frequency range is limited. An effective method for reducing an oscillation is by using an active vibration isolation system, which allows control of the dynamic rigidity of shock absorbers. In this paper, by considering the characteristics of the disturbing influences acting upon vibro-isolated objects, the dynamic characteristics of the AVIS device and control restriction, new optimal and quasi-optimal control algorithms are proposed. The characteristics of the new quasi-optimal active vibration isolation system proposed in the paper are investigated via experiments. It is shown that the adopted quasi-optimal active vibration isolation system can improve performance using in situ measurements. (c) 2005 Published by Elsevier Ltd.
暂无评论