A New Database Intrusion Detection Approach Based on Hybrid Meta-Heuristics

A new secured database management system architecture using intrusion detection systems (IDS) is proposed in this paper for organizations with no previous role mapping for users. A simple representation of Structured Query Language queries is proposed to easily permit the use of the worked clustering algorithm. A new clustering algorithm that uses a tube search with adaptive memory is applied to database log files to create users’ profiles. Then, queries issued for each user are checked against the related user profile using a classifier to determine whether or not each query is malicious. The IDS will stop query execution or report the threat to the responsible person if the query is malicious. A simple classifier based on the Euclidean distance is used and the issued query is transformed to the proposed simple representation using a classifier, where the Euclidean distance between the centers and the profile’s issued query is calculated. A synthetic data set is used for our experimental evaluations. Normal user access behavior in relation to the database is modelled using the data set. The false negative (FN) and false positive (FP) rates are used to compare our proposed algorithm with other methods. The experimental results indicate that our proposed method results in very small FN and FP rates.     

Frenet坐标框架下的自适应避障算法

目的 解决包装车间无人运输车辆在沿全局路径行驶过程中,难以同时保证跟随轨迹平滑及规避障碍物的问题。方法 构建Frenet坐标框架,描述车辆位姿与全局路径的相对关系,利用五次多项式生成多条待选局部路径;采用障碍物势场法模糊处理包装车间障碍的外形轮廓,并设置膨胀区间;结合待选路径采样点经过障碍物膨胀区间得到的碰撞值,以及采样点与全局规划路径的偏差值,综合评估路径的避障能力,筛选出最优的避障路径。结果 该算法能根据障碍物的大小,动态解算出与全局路径偏移量小且运动连贯的局部避障路径。结论 所提算法使得车辆完成运输任务时的效果更好,且效率更高。     

A two-stage path planning approach for multiple car-like robots based on PH curves and a modified harmony search algorithm

In this article, collision-avoidance path planning for multiple car-like robots with variable motion is formulated as a two-stage objective optimization problem minimizing both the total length of all paths and the task’s completion time. Accordingly, a new approach based on Pythagorean Hodograph (PH) curves and Modified Harmony Search algorithm is proposed to solve the two-stage path-planning problem subject to kinematic constraints such as velocity, acceleration, and minimum turning radius. First, a method of path planning based on PH curves for a single robot is proposed. Second, a mathematical model of the two-stage path-planning problem for multiple car-like robots with variable motion subject to kinematic constraints is constructed that the first-stage minimizes the total length of all paths and the second-stage minimizes the task’s completion time. Finally, a modified harmony search algorithm is applied to solve the two-stage optimization problem. A set of experiments demonstrate the effectiveness of the proposed approach.     

Traditional Chinese Medicine Automated Diagnosis Based on Knowledge Graph Reasoning

Syndrome differentiation is the core diagnosis method of Traditional Chinese Medicine (TCM). We propose a method that simulates syndrome differentiation through deductive reasoning on a knowledge graph to achieve automated diagnosis in TCM. We analyze the reasoning path patterns from symptom to syndromes on the knowledge graph. There are two kinds of path patterns in the knowledge graph: one-hop and two-hop. The one-hop path pattern maps the symptom to syndromes immediately. The two-hop path pattern maps the symptom to syndromes through the nature of disease, etiology, and pathomechanism to support the diagnostic reasoning. Considering the different support strengths for the knowledge paths in reasoning, we design a dynamic weight mechanism. We utilize Naïve Bayes and TF-IDF to implement the reasoning method and the weighted score calculation. The proposed method reasons the syndrome results by calculating the possibility according to the weighted score of the path in the knowledge graph based on the reasoning path patterns. We evaluate the method with clinical records and clinical practice in hospitals. The preliminary results suggest that the method achieves high performance and can help TCM doctors make better diagnosis decisions in practice. Meanwhile, the method is robust and explainable under the guide of the knowledge graph. It could help TCM physicians, especially primary physicians in rural areas, and provide clinical decision support in clinical practice.     

Double global optimum genetic algorithm–particle swarm optimization-based welding robot path planning

Spot-welding robots have a wide range of applications in manufacturing industries. There are usually many weld joints in a welding task, and a reasonable welding path to traverse these weld joints has a significant impact on welding efficiency. Traditional manual path planning techniques can handle a few weld joints effectively, but when the number of weld joints is large, it is difficult to obtain the optimal path. The traditional manual path planning method is also time consuming and inefficient, and cannot guarantee optimality. Double global optimum genetic algorithm–particle swarm optimization (GA-PSO) based on the GA and PSO algorithms is proposed to solve the welding robot path planning problem, where the shortest collision-free paths are used as the criteria to optimize the welding path. Besides algorithm effectiveness analysis and verification, the simulation results indicate that the algorithm has strong searching ability and practicality, and is suitable for welding robot path planning.     

Tool path generation for triangular meshes using least-squares conformal map

Tool path generation is an interesting and challenging task in free-form surface machining. Iso-planar tool path generation is one of the common approaches to dealing with this task. However, it suffers from an inherent drawback that intersecting intervals of the iso-planar method are limited to surface geometric features. This results in poor machining efficiency in flat regions due to redundant machining paths. For this problem, a new tool path generation method for triangular meshes is proposed based on the least-squares conformal map (LSCM). After LSCM parameterisation with minimal stretching energy, the triangular meshes are unfolded on a plane, where the principal component analysis (PCA) technique is employed to determine a suitable drive line for calculating cutter contact paths by the iso-planar strategy. Therefore, the tool paths are generated in a plane and the unevenness of the traditional iso-planar method is improved. The feasibility and effectiveness of the developed method is demonstrated through a test experiment.     

上下文感知计算中的时序表示与推理方法研究

分析了基于本体论的上下文建模方法,对现有上下文本体进行了分类和比较,并针对其在时序表示方面存在的问题,提出了基于资源描述框架(RDF)具体化的上下文时序信息表示方法,扩展了上下文本体的描述能力.同时针对上下文感知中的时序推理问题,提出了一个持续时间推理算法;另外还通过整合Allen区间代数和本体推理实现了时序关系推理.最后通过实验验证了上述两种时序推理方法的效率.     

大型旋转机械故障诊断专家系统ETHYLENE的理论研究

本文在模糊产生式规则的基础上引入了加权模糊连接算子的概念,并研究了征兆的类型。在此基础上,为旋转机械模糊诊断知识提出了一个灵活的知识表达方法——广义模糊产生式规则。在征兆类型的基础上引入了征兆认可因子的概念.利用这一概念来描述模糊蕴涵关系的语义,基于征兆认可因子提出了一个模糊推理算法。文中还给出了由基于这一广义模糊产生式规则和模糊推理算法建立的透平压缩机组故障诊断专家系统ETHYLENE得到的两个诊断结果。     

A signal path grouping algorithm for fast detection of shortcircuits on printed circuit boards

In a previous study, Leung (1993) proposed a parallel algorithm to locate all the short circuits on a printed circuit board. This algorithm divides the signal paths into multiple groups such that each group has a predetermined number of signal paths, and it tests M groups of signal paths against M respective groups simultaneously. In this paper, we show that the average number of tests required by Leung's algorithm depends not only on the number of signal paths in each group but also on how the signal paths are grouped. The reason is that a signal path is more likely shorted to its neighboring paths, but it is less likely shorted to the faraway paths. We propose an algorithm, called a signal path grouping algorithm, to selectively group the signal paths. If this signal path grouping algorithm is used to complement Leung's algorithm, the average number of tests required can be reduced     

基于粗集方法的智能专家系统

文章主要介绍基于粗集方法的智能专家系统的基本构成、知识表达方式及学习推理方法。提出了利用不可分辨性或根据算法相容性进行知识简化,导出决策规则的方法,通过研究导师的知识与学习者的知识之间的依赖程度,找出每一概念的有用特征,进行知识简化和系统简化,导出决策规则的学习推理方法。     

考虑冲突避免的多AGV路径规划研究

目的 提高物流企业“货到人”拣选系统在实际生产中的工作效率，避免自动导引小车(AGV)间的冲突死锁，研究大规模多AGV的无冲突路径规划和协同避障问题。方法 首先考虑AGV空载、负载情况和路径扩展成本，改进A^*算法，动态调整代价函数，优化路径扩展方式。其次，提出冲突检测及避免算法，对可能产生局部冲突的路径交叉点进行避障调度，通过预约锁格，实现局部冲突的检测，制定优先级避障策略，解决AGV动态行驶路径上产生的局部冲突和死锁，进而实现全局无冲突路径规划。结果 对多组不同任务量和不同AGV规模的场景进行仿真，实验结果表明，考虑冲突避免的改进A^*算法能有效实现100个任务、90个货架单位和7个拣选站场景下的多AGV动态路径规划，相较于传统A^*算法，其平均拣选时长缩短了52.61%。结论 该方法可实现大规模场景下的多AGV动态路径规划，在付出较小转弯代价的同时有效避免局部动态冲突，该方法可为相关企业实现多AGV协同调度提供新的思路和理论依据。     

Efficient tool path planning for five-axis surface machining with a drum-taper cutter

This paper presents a new efficient approach to NC tool path generation for five-axis surface machining. First, an efficient cutter, named a drum-taper cutter, is proposed; its key dimension is determined to avoid gouging in surface machining according to the maximum curvature of the surface calculated with a genetic algorithm. Then, based on the drum-taper cutter, the tool paths are generated so that the scallop height formed by adjacent tool paths in machining is kept constant, and an improved algorithm for calculating the interval between tool paths is presented. Finally, an example of tool path generation with the above method for arbitrary surface impeller machining is conducted, and the results show that the presented method leads to a significant reduction in the total tool path length and is accompanied by a reduction in machining time.     

基于路段时间窗考虑备选路径的AGV路径规划

针对自动化集装箱码头基于卸箱任务的自动导引车（automated guided vehicle,AGV）路径规划问题,结合最优路径数学模型、路径搜索方法和时间窗,提出了一种基于路段时间窗的AGV路径规划方法。首先,在给AGV下派任务的基础上,用最优路径数学模型为AGV规划出最短路径;其次,用路径搜索方法搜索AGV的备选路径,在路径长度相同的情况下,按照路径中转折次数确定备选路径优先级,转折次数少的备选路径优先级高;最后,在各AGV最短路径下,设置各个路段的时间窗,时间窗无重叠则表明AGV无冲突,对于时间窗重叠的路段,采用在原路径上插入时间窗或者在备选路径上插入时间窗的方法,再进行时间窗重叠测试,若还存在重叠的,则继续调整至最终实现多AGV的无冲突路径规划。为了验证方法的有效性,以8台AGV分区同时工作为例,用实例证明所提出的路径规划方法的避碰效果。结果显示该方法能为多台同时工作的AGV规划出一条无冲突优化路径,并且用时较短;在试验中发现选择在备选路径上插入时间窗的方法效果更好。研究表明所提方法能有效实现AGV的避碰,提高AGV利用率和自动化集装箱码头的运作效率。     

装配尺寸链自动生成的研究

基于装配的计算机辅助公差设计主要包括公差表达、公差链的生成、公差分析和公差综合四个部分。公差链的生成是其余三部分的基础。本文在实体关系模型的基础上研究了装配尺寸链的自动生成算法, 在一维尺寸链生成算法中提出基于搜索方向的配合关系图生成的新算法。该算法中加入了配合关系方向性的取舍, 降低了配合图生成的复杂度, 同时该算法可以判断关系设计的冗余性。     

Two-dimensional representation of machining geometry and tool path generation for ball-end milling of sculptured surfaces

This article applies a two-dimensional representation of the machining geometry relevant to tool path generation for the three-axis ball-end milling of sculptured surfaces. A two-dimensional geometric model detecting the machined strip is suggested as the concept for the ‘effective cutting profile’ which fits well into the three-dimensional machining geometry. The model is the same as the intersection of the cutter with the plane perpendicular to the tangent direction of the cutter location curve and incident with the cutter location point. In order to achieve the specified machining accuracy, an iterative approach is needed. The paper also presents a new iterative method to generate tool paths with a constant scallop height. It is based on the proposed model which resorts to a two-dimensional representation of the three-dimensional machining geometry. The proposed method reduces significantly the computing time to generate tool paths. Implementations and illustrated examples are discussed.     

Region-based surveillance video retrieval with effective object representation

Retrieving the most relevant video frames that contain the object specified in a given query (query-by-region) remains a challenging task. Two common challenges of region-based retrieval approaches are to accurately extract or segment object(s) and select a proper matching strategy. This paper addresses these problems by proposing a retrieval approach that uses a new region-based matching technique equipped with an effective object representation method. In the first stage, the proposed approach selects the most informative instances of each object that appeared in the video by utilizing an adapted clustering algorithm over the extracted features. In the retrieval stage, the new matching technique returns the most relevant sequences of video by mapping a given region with those identified representative instances of objects based on their similarity scores. The proposed approach is evaluated on standard datasets and the results demonstrate a 31% improvement in the retrieval performance compared to other state-of-the-art methods.     

An improvement heuristic framework for the laser cutting tool path problem

This paper deals with generating cutting paths for laser cutting machines by representing a tool path in a novel way. Using the new representation, the tool path problem can be viewed as finding a partitioning of contours which minimises the sum of the costs of a rooted directed minimum spanning tree to connect the partitions and the costs of a generalised travelling salesman problem (GTSP) solutions within each partition. Using Edmond–Liu’s algorithm to solve the arborescence problem, an improved Lin–Kernighan heuristic to solve the GTSP and a heuristic-repartitioning approach, tool paths can be generated that are 4.2% faster than those generated by an existing tool path construction heuristic.     

ICVSS: A New Method for Vulnerability Quantitative Grading

Vulnerability technology is the basic of network security technology, vulnerability quantitative grading methods, such as CVSS, WIVSS, ICVSS, provide a reference to vulnerability management, but the problems of ignoring the risk elevation caused by a group of vulnerabilities and low accuracy of exploitable level evaluation exist in current vulnerability quantitative grading methods. To solve problems above in current network security quantitative evaluation methods, this paper verified the high relevance degree between type and exploitable score of vulnerability, proposed a new vulnerability quantitative grading method ICVSS, ICVSS can explore attack path using continuity level defined by privilege, add vulnerability type to measure indexes of exploitable metrics and use Analytic Hierarchy Process (AHP) to quantify the influence of vulnerability type on exploitable level. Compared with CVSS and WIVSS, ICVSS is proved that it can discover attack path consist of a sequence of vulnerabilities for network security situation evaluation, and has more accuracy and stability.     

A new machine strategy for sculptured surfaces using offset surface

A new CNC tool path planning method is developed for accurate and efficient finishing cutting of sculptured surfaces. The proposed method generates CNC tool paths based on an offset surface of an object instead of the actual surface. The new algorithm consists of two main computational techniques: offset surface generation technique and offset CNC tool path planning technique. In offset surface generation, approximate parametric offset surfaces are generated accurately from an original parametric surface by employing bi-cubic surface patch, surface conversion, and surface subdivision algorithms. In offset CNC tool path planning, the precise geometric models of chordal deviation and cusp height on an offset surface are established. The effectiveness of this proposed CNC tool path planning method is verified by geometric simulation and verification which detect and identify errors in CNC tool paths.     

基于智能Agent的农业智能决策系统研究

提出了一种基于知识的智能Agent逻辑模型,该模型以知识为核心,以推理作为主要规划手段。在此逻辑模型的基础上,提出了以本体为核心的Agent内部知识表示方法。并在任务及实体定义的基础上,结合产生式知识表示方法,构造了规划表示方法,形成了一个完整的智能Agent内部知识模型并基于黑板模型设计了智能Agent的实现结构以及其中的关键算法——规划过程。设计了基于智能Agent及黑板机制的农业智能决策系统的基本框架,并以农场作物生产决策系统证实了该模型能够满足大规模分布式农业决策系统的需求。