A note on vertex orders for stability number

We investigate vertex orders that can be used to obtain maximum stable sets by a simple greedy algorithm in polynomial time in some classes of graphs. We characterize a class of graphs for which the stability number can be obtained by a simple greedy algorithm. This class properly contains previously known classes of graphs for which the stability number can be computed in polynomial time. © 1999 John Wiley & Sons, Inc. J Graph Theory 30: 113–120, 1999     

IPv4/IPv6转换网关的SNMP代理设计与实现

基于NAT-PT技术的IPv4/IPv6转换网关部署在IPv4/IPv6网络边缘,用于两网互通.对转换网关提供网络管理功能对保障两网互通有着重要意义.然而,网关所在网络业务流量的复杂性和其基于网络处理器的架构对网络管理的实现提出了挑战.本文提出了一种转换网关SNMP代理的设计方案,定义了NAT-PT MIB,实现了网络处理器环境下分布式MIB的采集并提供了对IPv4/IPv6两网内进行网络管理的支持.     

Determination of triazine herbicides in human body fluids by solid-phase microextraction and capillary gas chromatography

Summary Eight triazine herbicides, prometon, propazine, atrazine, simazine, prometryn, ametryn, metribuzin, and cyanazine, have been extracted from human whole blood and urine samples by headspace solid-phase microextraction (SPME) with a polydimethylsiloxane-coated fiber and quantified by capillary gas chromatography with nitrogen-phosphorus detection. Extraction efficiencies for all compounds were 0.21–0.99% for whole blood, except for cyanazine (0.06%). For urine, the extraction efficiencies for prometon, propazine, atrazine, prometryn and ametryn were 13.6–38.1%, and those of simazine, metribuzin and cyanazine were 1.35–8.73%. The regression equations for the compounds extracted from whole blood were linear within the concentration ranged 0.01–1 μg (0.5 mL)⁻¹ for prometon, propazine, atrazine, prometryn, and ametryn, and 0.02–1 μg (0.5 mL)⁻¹ for simazine, metribuzin, and cyanazine. For urine, regression equations for all compounds were linear within the concentration range 0.005–0.25 μg mL⁻¹. Compound detection limits were 2.8–9.0 ng (0.5 mL)⁻¹ and 0.4–2.0 ng mL⁻¹ for whole blood and urine, respectively. The coefficients of within-day and day-to-day variation were satisfactory for all the compounds, and not greater than 10.3 and 14.2%, respectively. Data obtained from determination of atrazine in rat whole blood after oral administration of the compound are also presented.     

基于概率增益的电路划分算法

该文提出了一种新的划分算法,算法中引入可变线网权重。由于超图(hypergraph)中的线网连接节点数一般多于两个,为了充分将线网增加的权重作用到与该线网相连的所有节点上去,线网增益采用了概率增益模型。该算法与原有算法相比较,可以有效地让电路的划分跳出局部最小,结果有较大的改进,特别是当电路规模比较大的时候,改进更明显。由于采用概率增益模型,出现浮点数,节点增益的存储采用了平衡二叉树(balanced binary tree),因此算法的速度相对于FM算法有所下降,但是时间复杂度仍然接近为线性复杂度,时间复杂度为O(P log2(n))(P为电路所有逻辑单元的引脚数之和,n为电路的逻辑单元数)。     

K-means聚类算法研究综述

总结评述了K-means聚类算法的研究现状,指出K-means聚类算法是一个NP难优化问题,无法获得全局最优。介绍了K-means聚类算法的目标函数、算法流程,并列举了一个实例,指出了数据子集的数目K、初始聚类中心选取、相似性度量和距离矩阵为K-means聚类算法的3个基本参数。总结了K-means聚类算法存在的问题及其改进算法,指出了K-means聚类的进一步研究方向。     

Novel Biological Functions of ZIF‐NP as a Delivery Vehicle: High Pulmonary Accumulation,Favorable Biocompatibility,and Improved Therapeutic Outcome

Though zeolitic imidazole framework (ZIF) emerges as an advanced functional material for small‐molecule delivery due to its unique features such as high loading and pH‐sensitive degradation, there are extreme short of knowledge regarding its biological functions. To qualify this category of delivery vehicle, ZIF‐8 nanoparticles (ZIF‐NPs) with or without cargo are engineered and comprehensively investigated in vitro and in vivo. Interestingly, ZIF‐NPs demonstrate strong bioadhesion but with limited internalization themselves, which enhance the membrane‐mediated ROS and are different from that of inorganic ZnO inducing mitochondria‐mediated reactive oxygen species (ROS) without biomembrane damage. Unexpected high concentration is found in lung, probably due to the particle size and distribution of the nanocarriers; however, the drug levels drop dramatically with time, revealing the fast degradation and elimination. At the given doses, ZIF‐NPs exhibit reasonably biosafety in animal tests as evidenced by their acceptable system and blood biocompatibilities, and minimal impacts on the liver and renal functions, immune cells, inflammatory factors, etc. ZIF‐NPs with fluorouracil loading (5F@ZIF‐NPs) significantly improve the therapeutic outcome of lung metastasis tumor in a nude mice model. Generally, ZIF‐NPs demonstrate unique biological functions in terms of bio–nano interaction, pulmonary accumulation, biocompatibility, and antitumor therapy, which endow them potential as the delivery vehicles.     

Convergence of an annealing algorithm

The annealing algorithm is a stochastic optimization method which has attracted attention because of its success with certain difficult problems, including NP-hard combinatorial problems such as the travelling salesman, Steiner trees and others. There is an appealing physical analogy for its operation, but a more formal model seems desirable. In this paper we present such a model and prove that the algorithm converges with probability arbitrarily close to 1. We also show that there are cases where convergence takes exponentially long—that is, it is no better than a deterministic method. We study how the convergence rate is affected by the form of the problem. Finally we describe a version of the algorithm that terminates in polynomial time and allows a good deal of practical confidence in the solution.     

Theories on Solving the Travelling Salesman Problem Based on Artificial Neural Network and Their Applications

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面向机器翻译的英语词性标注研究及其应用

A hybrid approach to English Part-of-Speech (PoS) tagging with its target application being English-Chinese machine translation in business domain is presented, demonstrating how a present tagger can be adapted to learn from a small amount of data and handle unknown words for the purpose of machine translation. A small size of 998 k English annotated corpus in business domain is built semi-automatically based on a new tagset; the max-imum entropy model is adopted, and rule-based approach is used in post-processing. The tagger is further applied in Noun Phrase (NP) chunking. Exper-iments show that our tagger achieves an accuracy of 98.14%, which is a quite satisfactory result. In the application to NP chunking, the tagger gives rise to 2.21% increase in F-score, compared with the results using Stanford tagger.