基于虚拟机技术的安全系统研究

该文在深入分析蜜罐和入侵检测技术的基础上,提出了基于虚拟机技术的蜜罐入侵检查系统,它是集蜜罐、HIDS以及NIDS于一体的入侵检查系统,系统中将蜜罐在虚拟机上进行分离,结合IDS来控制蜜罐的安全性,同时结合两者对网络安全的检测信息来实现更强的入侵检查系统。该系统方案在最大化解决蜜罐自身安全问题的同时,结合3者的优点并抑制了各自的缺点,几乎不需要改变现有的入侵检测系统,故具有很强的实用性和广阔的应用前景。     

A necessary and sufficient condition for parameter insensitive disturbance-rejection problem with state feedback

In this paper a necessary and sufficient condition for a parameter insensitive disturbance-rejection problem with state feedback which was pointed out as an open problem by Bhattacharyya to be solvable is proved. A constructive algorithm of simultaneously (A,B)-invariant subspaces for a finite-number of linear systems and a relationship between simultaneously (A,B)-invariant subspaces and generalized (A,B)-invariant subspaces play an important role to prove the main result.     

An Analysis of Linear Subspace Approaches for Computer Vision and Pattern Recognition

Linear subspace analysis (LSA) has become rather ubiquitous in a wide range of problems arising in pattern recognition and computer vision. The essence of these approaches is that certain structures are intrinsically (or approximately) low dimensional: for example, the factorization approach to the problem of structure from motion (SFM) and principal component analysis (PCA) based approach to face recognition. In LSA, the singular value decomposition (SVD) is usually the basic mathematical tool. However, analysis of the performance, in the presence of noise, has been lacking. We present such an analysis here. First, the “denoising capacity” of the SVD is analysed. Specifically, given a rank-r matrix, corrupted by noise—how much noise remains in the rank-r projected version of that corrupted matrix? Second, we study the “learning capacity” of the LSA-based recognition system in a noise-corrupted environment. Specifically, LSA systems that attempt to capture a data class as belonging to a rank-r column space will be affected by noise in both the training samples (measurement noise will mean the learning samples will not produce the “true subspace”) and the test sample (which will also have measurement noise on top of the ideal clean sample belonging to the “true subspace”). These results should help one to predict aspects of performance and to design more optimal systems in computer vision, particularly in tasks, such as SFM and face recognition. Our analysis agrees with certain observed phenomenon, and these observations, together with our simulations, verify the correctness of our theory.     

A method for calculating successive approximate solutions for a class of block banded M/G/1 type Markovian models

This paper presents an efficient equilibrium solution algorithm for a class of infinite block banded M/G/1 type Markov chains. By re-blocking the states, these are a class of the so-called quasi-birth-and-death (QBD) type chains. The proposed algorithm is not based on an iterative approach, so that the exact solution can be computed in a known finite number of steps. The key point on which the algorithm is based is the identification of a linear dependence among variables. This dependence is expressed in terms of a companion matrix. The equilibrium solution of the Markov chain is obtained operating on this matrix.

An attractive feature of the algorithm is that it allows the computation of a succession of approximate solutions with growing accuracy, until the exact solution is obtained in a finite number of steps. The class of block-banded M/G/1 type Markov chains we consider requires that the lower diagonal block is invertible and that the chain is ergodic. However, many models arising from telecommunication systems satisfy this restriction. Results for a case study show that the proposed algorithm is efficient and quite accurate, even when providing approximate solutions.     

Bicriteria robotic cell scheduling

This paper considers the scheduling problems arising in two- and three-machine manufacturing cells configured in a flowshop which repeatedly produces one type of product and where transportation of the parts between the machines is performed by a robot. The cycle time of the cell is affected by the robot move sequence as well as the processing times of the parts on the machines. For highly flexible CNC machines, the processing times can be changed by altering the machining conditions at the expense of increasing the manufacturing cost. As a result, we try to find the robot move sequence as well as the processing times of the parts on each machine that not only minimize the cycle time but, for the first time in robotic cell scheduling literature, also minimize the manufacturing cost. For each 1-unit cycle in two- and three-machine cells, we determine the efficient set of processing time vectors such that no other processing time vector gives both a smaller cycle time and a smaller cost value. We also compare these cycles with each other to determine the sufficient conditions under which each of the cycles dominates the rest. Finally, we show how different assumptions on cost structures affect the results.     

Preemptive Scheduling on Uniform Parallel Machines with Controllable Job Processing Times

In this paper, we provide a unified approach to solving preemptive scheduling problems with uniform parallel machines and controllable processing times. We demonstrate that a single criterion problem of minimizing total compression cost subject to the constraint that all due dates should be met can be formulated in terms of maximizing a linear function over a generalized polymatroid. This justifies applicability of the greedy approach and allows us to develop fast algorithms for solving the problem with arbitrary release and due dates as well as its special case with zero release dates and a common due date. For the bicriteria counterpart of the latter problem we develop an efficient algorithm that constructs the trade-off curve for minimizing the compression cost and the makespan.     

An alternative model for integrated vendor–buyer inventory under controllable lead time and its heuristic solution

Researchers have given a lot of attention to the integrated vendor–buyer problem. Both deterministic and stochastic models on the subject are available in the literature. Most of the models have appeared with the need and requirement of a Just-in-Time (JIT) system environment. The close tie between a vendor and a buyer helps to deliver products in a shorter lead time with reduced inventory cost. Based on this idea, recently, some researchers have presented such a stochastic model with equal sized batch (part of a lot) transfer under controllable lead time. They have shown that their model provides a lower total cost for a numerical problem. To enrich the JIT system literature, considering transportation cost of a batch, this article develops an alternative model of the problem with equal or unequal sized batches transfer under controllable lead time. Then it develops a heuristic solution technique of the model and applying it solves the same numerical example to show a reasonable cost reduction.     

Further decomposition for singular systems and its properties on geometric subspace

This paper focuses on the relationship between the geometric subspaces and the structural decomposition of continuous-time singular systems. The original structural decomposition is not capable of revealing explicitly the invariant geometric subspaces for singular systems. As such, a further decomposition is necessary and is thus investigated in this paper. Under a new decomposition proposed, the supremal output-nulling (A,E, ImB)-invariant subspace of singular systems can be clearly expressed in an explicit form, and some of its applications are also addressed.     

Controllable fair queuing for meeting performance goals

Computing and storage utilities must control resource usage to meet contractual performance targets for hosted customers under dynamic conditions, including flash crowds and unexpected resource failures. This paper explores properties of proportional share resource schedulers that are necessary for stability and responsiveness under feedback control. It shows that the fairness properties commonly defined for proportional share schedulers using Weighted Fair Queuing (WFQ) are not preserved across changes to the relative weights of competing request flows. As a result, conventional WFQ schedulers are not controllable by a resource controller that adapts by adjusting the weights. The paper defines controllable fairness properties, presents an algorithm to adjust any WFQ scheduler when the weights change, and proves that the algorithm results in controllable-fair schedulers.

The analytic results are confirmed by experimental evaluation using a three-tier Web service and a prototype controllable-fair scheduler called C-SFQ(D). C-SFQ(D) extends concurrency-controlled Start-time Fair Queuing (SFQ(D), which supports proportional sharing in multi-tasking computing resources. The prototype includes an adaptive control system that adjusts the flow weights in C-SFQ(D) to meet latency and throughput targets under a variety of conditions. The experimental results demonstrate the importance of controllable-fair scheduling for feedback control of computing utilities.