实时多任务操作系统的开发与应用

介绍了适用于实时嵌入式系统的操作系统软件———IR-OS的开发及其在智能脱扣器系统中的应用。IR-OS采用了微内核结构设计,基于抢占式优先级调度,内核代码简洁,并提供良好的开发接口。将IR-OS作为实时嵌入式系统的开发和运行平台,不但克服了传统顺序结构设计所带来的代码结构复杂、可移植性差和功能扩展不方便的缺点,而且具有更好的实时性、稳定性和可靠性。     

Tracking and load sway reduction for double‐pendulum rotary cranes using adaptive nonlinear control approach

Because of the existence of rotational boom motion, the load sway characteristics is more complex. In particular, when the sway presents double‐pendulum phenomenon, the design of the controller is more challenging. Furthermore, the uncertain parameters and external disturbances in crane system make it difficult for traditional control methods to obtain satisfactory control performance. Hence, this paper presents an adaptive nonlinear controller based on the dynamic model of double‐pendulum rotary crane. Unlike a traditional method, the proposed one does not need to linearize the crane system for controller design; therefore, the control performance can be guaranteed even if the system states are far away from the equilibrium point. By using Lyapunov technique and LaSalle's invariance theorem, it is strictly proved that the whole control system is asymptotically stable at the equilibrium point. The effectiveness of the presented controller is demonstrated via comparative simulations.     

Sequential probabilistic analytical target cascading method for hierarchical multilevel optimization under uncertainty

Probabilistic Analytical Target Cascading (PATC) is a methodology for hierarchical multilevel optimization under uncertainty. In PATC, the statisticalmoments of the stochastic interrelated responses are matched between neighbouring levels to ensure the consistency of the solution. When the interrelated response is far from normal distribution, high order moments may need to be matched in the PATC formulation, which results in great computational difficulty. To overcome this disadvantage, a sequential PATC (SPATC) approach is proposed in this paper. SPATC firstly decouples the original probabilistic design problem into deterministic optimization problem and probabilistic analysis, and then hierarchically decomposes them into subproblems. The statistical information matching between neighbouring levels in the existing PATC framework is eliminated in SPATC. All in one probabilistic analysis and hierarchical probabilistic analysis are established to calculate the probabilistic characteristic of the interrelated responses and linking variables. Three examples are used to demonstrate the effectiveness and efficiency of the proposed SPATC approach. The results show that the SPATC approach is more efficient and accurate than PATC, especially for the multilevel design problem with non-normal interrelated responses.     

软交换技术介绍与应用

NGN新一代网络是以软交换为核心,采用开放、标准化体系结构提供语音、数据、视频等多种媒体业务服务的下一代网络.本文介绍了软交换的引入及定义、软交换技术的网络结构、软交换的主要功能,最后详细说明软交换与传统电信网相比的优势,并对其发展前景进行展望.     

Supervised topic models with weighted words: multi-label document classification

Supervised topic modeling algorithms have been successfully applied to multi-label document classification tasks. Representative models include labeled latent Dirichlet allocation (L-LDA) and dependency-LDA. However, these models neglect the class frequency information of words (i.e., the number of classes where a word has occurred in the training data), which is significant for classification. To address this, we propose a method, namely the class frequency weight (CF-weight), to weight words by considering the class frequency knowledge. This CF-weight is based on the intuition that a word with higher (lower) class frequency will be less (more) discriminative. In this study, the CF-weight is used to improve L-LDA and dependency-LDA. A number of experiments have been conducted on real-world multi-label datasets. Experimental results demonstrate that CF-weight based algorithms are competitive with the existing supervised topic models.     

XML关键字检索的最低公共祖先快速查找方法

XML上的关键字检索由于不需要对XML的模式有所了解,对用户来说是简单而实用的.由于XML的树结构特点,XML上关键字检索需要返回最相关的结果给用户,通常是包含关键字的最小子树.这个问题可以转换为经典的最低公共祖先问题.以前的工作,像XRank和XKsearch都使用dewey编码来解决公共祖先的问题.虽然通过dewey编码来判定祖先后代关系并定位共同祖先结点比较容易,但同时这种方法有如下弊端:首先,频繁的逐段比较dewey编码比较耗时;其次,存储dewey编码比较浪费空间.所以提出了一种有效的基于范围最小值查询的方法来解决XML关键字检索中的最低公共祖先问题.进一步地,将此方法应用到一个计算最小最低公共祖先的非阻塞算法中,并据此实现了一个XML关键字检索系统.实验表明此方法在时间上和空间上都是高效的.     

A neuro-fuzzy system modeling with self-constructing rule generationand hybrid SVD-based learning

We propose an approach for neuro-fuzzy system modeling. A neuro-fuzzy system for a given set of input-output data is obtained in two steps. First, the data set is partitioned automatically into a set of clusters based on input-similarity and output-similarity tests. Membership functions associated with each cluster are defined according to statistical means and variances of the data points included in the cluster. Then, a fuzzy IF-THEN rule is extracted from each cluster to form a fuzzy rule-base. Second, a fuzzy neural network is constructed accordingly and parameters are refined to increase the precision of the fuzzy rule-base. To decrease the size of the search space and to speed up the convergence, we develop a hybrid learning algorithm which combines a recursive singular value decomposition-based least squares estimator and the gradient descent method. The proposed approach has advantages of determining the number of rules automatically and matching membership functions closely with the real distribution of the training data points. Besides, it learns faster, consumes less memory, and produces lower approximation errors than other methods.     

广义Horn集

本文定义了广义Ｈｏｒｎ集，并在广义Ｈｏｒｎ集上证明了广义输入归结的完备性；广义输入对称调解的完备性；以及一定条件下的广义输入有向调解的完备性．文中还证明了广义调解法的提升引理．     

Mass production of highly monodisperse polymeric nanoparticles by parallel flow focusing system

Nanoparticles can be prepared through nanoprecipitation by mixing polymers dissolved in organic solvents with anti-solvents. However, due to the inability to precisely control the mixing processes during the synthesis of polymeric nanoparticles, its application is limited by a lack of homogeneous physicochemical properties. Here, we report that this obstacle can be overcome through rapid and controlled mixing by parallel flow focusing outside the microfluidic channels. Using the nanoprecipitation of methoxyl poly-(ethylene glycol)–poly-(lactic-co-glycolic acid) (MPEG–PLGA) block copolymers as an example, we prove that our parallel flow focusing method is a robust and predictable approach to synthesize highly monodisperse polymeric nanoparticles, and demonstrate that it improves the production speed of nanoparticles by an order of magnitude or more compared with previous microfluidic systems. Possible aggregation on the surface of PDMS wall and clogging of microchannels reported previously were avoided in the synthesis process of our method. This work is a typical application combining the advantages of microfluidics with nanoparticle technologies, suggesting that microfluidics may find applications in the development and mass production of polymeric nanoparticles with high monodispersity in large-scale industrial production field.     

流化床还原碳化法制备超细WC－Co复合粉末

介绍了一种制备超细ＷＣ－Ｃｏ复合粉末的新工艺─—流化床还原碳化法。ＸＲＤ分析结果表明，该法制备的粉末由ＷＣ和Ｃｏ两相组成。Ｘ－射线小角衍射测定粉末的平均颗粒度为０．１２μｍ。将该粉末压制成形的样品在１２８０℃真空烧结１ｈ获得９９．７％理论密度的试块。