This paper presents properties of role-based access control which were obtained through a development of a prototype of a teaching management system. These properties are related to assignment of temporal constraints and access control procedure in terms of the corresponding flow of user's view and considered to be suitable to other information systems.

Interactive multimedia applications (IMAs) require not only adequate bandwidth to support large volume data transmission but also bounded end-to-end transmission delay between end users. This study proposes a Delay and Degree constrained Multicasting Spanning Tree (D2MST) algorithm to build an any-to-any share tree for IMAs. D2MST comprises root selection and spanning tree generation. A weighting function is defined based on the novel concept of network center and gravity to choose the root of a share tree. From the root, a spanning tree is built by incrementally connecting nodes with larger "power" to the tree so that the degree constraint is satisfied. Simulation results show that D2MST can successfully generate a Δ-constraint MST in which a high percentage of nodes can interact within the bounded delay.

This paper proposes an efficient two-phase optimization approach for a compact W-band double-plane stepped rectangular waveguide filter design, which combines genetic algorithms (GAs) with the simplified transmission-line model and full-wave analysis. Being more efficient and robust than the gradient-based method, the approach can lead to a compact waveguide filter design. Numerical results show that the resultant waveguide filter design with 4 sections (total length 19.6 mm) is sufficient to meet the design goal and provides comparable performance to that with 8 sections (total length 35.6 mm) by the Chebyshev synthesis approach. Based on the present approach, nineteen compact high-pass waveguide filters have been implemented and measured at the W-band with satisfactory performance.

This paper presents two novel blind set-theoretic adaptive filtering algorithms for suppressing "Multiple Access Interference (MAI)," which is one of the central burdens in DS/CDMA systems. We naturally formulate the problem of MAI suppression as an asymptotic minimization of a sequence of cost functions under some linear constraint defined by the desired user's signature. The proposed algorithms embed the constraint into the direction of update, and thus the adaptive filter moves toward the optimal filter without stepping away from the constraint set. In addition, using parallel processors, the proposed algorithms attain excellent performance with linear computational complexity. Geometric interpretation clarifies an advantage of the proposed methods over existing methods. Simulation results demonstrate that the proposed algorithms achieve (i) much higher speed of convergence with rather better bit error rate performance than other blind methods and (ii) much higher speed of convergence than the non-blind NLMS algorithm (indeed, the speed of convergence of the proposed algorithms is comparable to the non-blind RLS algorithm).

This paper presents a model and its effect for on-line handwritten Japanese text recognition free from line-direction constraint and writing format constraint such as character writing boxes or ruled lines. The model evaluates the likelihood composed of character segmentation, character recognition, character pattern structure and context. The likelihood of character pattern structure considers the plausible height, width and inner gaps within a character pattern that appear in Chinese characters composed of multiple radicals (subpatterns). The recognition system incorporating this model separates freely written text into text line elements, estimates the average character size of each element, hypothetically segments it into characters using geometric features, applies character recognition to segmented patterns and employs the model to search the text interpretation that maximizes likelihood as Japanese text. We show the effectiveness of the model through recognition experiments and clarify how the newly modeled factors in the likelihood affect the overall recognition rate.

This paper describes an on-line handwritten Japanese text recognition system that is liberated from constraints on line direction and character orientation. The recognition system first separates freely written text into text line elements, second estimates the line direction and character orientation using the time sequence information of pen-tip coordinates, third hypothetically segment it into characters using geometric features and apply character recognition. The final step is to select the most plausible interpretation by evaluating the likelihood composed of character segmentation, character recognition, character pattern structure and context. The method can cope with a mixture of vertical, horizontal and skewed text lines with arbitrary character orientations. It is expected useful for tablet PC's, interactive electronic whiteboards and so on.

The technological development of wireless environment has made real-time multimedia communications possible in wireless networks. Many studies have been done on real-time communications in wireless networks in order to overcome a higher bit error rate in wireless channels. However, none of work deals with firm real-time communications which can be applied to multimedia communications. In this paper, we propose an adaptive error correcting scheme for firm real-time multimedia communications in wireless networks in order to maximize the expected net profit. The proposed scheme adaptively selects an error correcting code under the current air state and the message state of a message stream. Throughout simulation results, we show that the suggested scheme provides more profit than single error-correcting code schemes.

In this paper, two techniques are proposed for accelerating and stabilizing the Levenberg-Marquardt (LM) method where its conventional stabilizer matrix (identity matrix) is superseded by (1) a diagonal matrix whose elements are column norms of Jacobian matrix J, or (2) a non-diagonal square root matrix of J TJ. Geometrically, these techniques make constraint conditions of the LM method fitted better to relevant cost function than conventional one. Results of numerical simulations show that proposed techniques are effective when both column norm ratio of J and mutual interactions between arguments of the cost function are large. Especially, the technique (2) introduces a new LM method of damped Gauss-Newton (GN) type which satisfies both properties of global convergence and quadratic convergence by controlling Marquardt factor and can stabilize convergence numerically. Performance of the LMM techniques are compared also with a damped GN method with line search procedure.

As the complexity of VLSI circuits increases, the routability problem becomes more and more important in modern VLSI design. In general, the flexibility improvement of the edges in a routing tree has been exploited to release the routing congestion and increase the routability in the routing stage. Given an initial rectilinear Steiner tree, the rectilinear Steiner tree can be transformed into a Steiner routing tree by deleting all the corner points in the rectilinear Steiner tree. Based on the definition of the routing flexibility in a Steiner routing tree and the timing-constrained location flexibility of the Steiner-point in any Y-type wire, the simulated-annealing-based approach is proposed to construct a better timing-constrained flexibility-driven Steiner routing tree by reassigning the feasible locations of the Steiner points in all the Y-type wires. The experimental results show that our proposed algorithm, STFSRT, can increase about 0.005-0.020% wire length to improve about 43-173% routing flexibility for the tested benchmark circuits.

In this paper we consider algorithms for the logical topology design and traffic grooming problem in WDM networks with router interface constraints as well as optical constraints. The optical constraints include restricted transmission range due to optical impairments as well as limits on the number of available wavelengths. We formulate this problem as an integer linear program which is NP-complete. We then introduce heuristic algorithms which use a graphical modeling tool called the Virtual Neighbor Graph and add lightpaths sequentially. The best performing heuristic uses a so-called Resource Efficiency Factor to determine the order in which paths are provisioned for the traffic demands. By giving priority to demands that can be routed over paths that make efficient use of network resources, it is able to achieve good performance both in terms of weighted hop count and network throughput. For finding optimal multi-hop paths sequentially, we introduce interface constraint shortest path problem and solve it using minimum weight perfect matching.

One of the important problems in overlay multicast is how to deal with node failures and ungraceful leavings. When a non-leaf end host fails or leaves the multicast session, all downstream nodes will be affected. In this paper, we adopt the proactive approach, which pre-calculates a candidate node (called parent-to-be) for each node to connect to in case its current parent dies. The goal is to recover the overlay multicast tree quickly so that the disruption of service to those affected nodes is minimized. We combine the local parent-to-be locating and global parent-to-be locating schemes together, in order to take advantage of less interference in the local scheme and the flexibility of the global scheme. The quality of the recovered tree is improved while the responsiveness of the proactive approach is maintained.

The 2-vertex-connectivity augmentation problem of a graph with degree constraints, 2VCA-DC, is defined as follows: "Given an undirected graph G = (V,E) and an upper bound a(v;G) Z+{} on vertex-degree increase for each v V, find a smallest set E′ of edges such that (V,E E′) has at least two internally-disjoint paths between any pair of vertices in V and such that vertex-degree increase of each v V by the addition of E′ to G is at most a(v;G), where Z+ is the set of nonnegative integers." In this paper we show that checking the existence of a feasible solution and finding an optimum solution to 2VCA-DC can be done in O(|V|+|E|) time.

We report tunable optical devices based on fiber Bragg gratings (FBGs), whose filtering characteristics are controlled by strain distributions. These devices include a widely wavelength tunable filter, a tunable group-velocity dispersion (GVD) compensator, a tunable dispersion slope (DS) compensator, and a variable-bandwidth optical add/drop multiplexer (OADM), which will play important roles for next-generation reconfigurable optical networks.

This paper presents a method of searching for the shortest route via the most designated points with the length not exceeding the preset upper bound. The proposed algorithm can obtain the quasi-optimum route efficiently and its effectiveness is verified by applying the algorithm to the actual map data.

The current scheme of access control judges the legality of each access based on immediate information without considering associate information hidden in a series of accesses. Due to the deficiency, access control systems do not efficiently limit attacks consist of ordinary operations. For trusted operating system developments, we extended RBAC and added negative procedural constraints to refuse those attacks. With the procedural constraints, the access control of trusted operating systems can discriminate attack trials from normal behaviors. This paper shows the specification of the extended concept and model, and presents simple analysis results.

To support high data rate wireless communications, in this paper, based on the linearly constrained constant modulus (LCCM) criterion, the reverse link performance of the multi-carrier code division multiple access (MC-CDMA) receiver, with frequency combiner, and having smart antenna arrays beamformer in base station, has been investigated over the Rayleigh fading channel. By using the Kronecker product an equivalent direct formulation, which integrates the information of spatial-domain as well as temporal-domain, with constraint matrix could be obtained. In consequence, the modified normalized LCCM-gradient algorithm is devised to adaptively implement the direct constrained optimal weights solution of the fully space-time MC-CDMA detector. We show that the proposed method outperforms the constrained minimum output energy (CMOE) algorithm and is more robust against to the signal mismatch, due to imperfect channel and direction-of-arrival estimation used in the array beamformer.

This paper presents a novel algorithm for crosspoint assignment (CPA) that takes into consideration crosstalk noise and shielding effects in deep sub-micron design. We introduce a conditional constraint which is imposed on a sensitive net-pair to detach one net from the other or to put another insensitive net between them for shielding. We provide two algorithms which can handle the conditional constraint: One is based on an ILP, which outputs an exact optimum solution. The other is a fast heuristics whose time complexity is O(n2 log n), where n is the number of pins. In experiments, we tested these algorithms for industrial examples. The results showed that the conditional constraint for shielding released algorithms from a tight space of feasible assignments. Our heuristics ran quickly and attained near optimum solutions.

In wide-area wireless access systems such as satellite communications systems and stratospheric platform systems, electric power supplies for radio communications are realized using solar photovoltaic cells and/or fuel cells. However, the on-board weight limits restrict the number of cells that can be equipped. In addition, the transmission power of such systems is limited taking account of issues and regulations on sharing the same frequency band with other systems. Hence, both the frequency band and electric power is limited, which are crucial radio resources for those systems. Although radio channel allocation methods taking account of the frequency constraint only or the power constraint only have been proposed, radio channel allocation methods taking account of both constraints simultaneously have been insufficiently studied. This paper proposes a radio channel allocation method that provides global optimum allocation results by utilizing the linear programming method. The proposed method has features such that the method first allocates radio channels in proportion to the traffic demand distributed over the service coverage area and then maximizes the total radio channels allocated to systems. Numerical results are presented for a stratospheric platform system that covers an area of Japan, as an example, to demonstrate that the proposed method optimally allocates radio channels taking account of both constraints while efficiently allocating excess resources. In addition, whether a system reaches either the frequency or power limit can be estimated, by investigating the radio channel allocation results. Furthermore, enhanced linear programming models based on a method aiming at practical use of the radio channel allocation results in operation are also introduced. The enhanced model is demonstrated to work effectively to avoid unbalanced radio channel allocations over geographical areas. The proposed method and linear programming models are useful not only for making pre-plans but also for determining the amount of necessary frequency and power resources in designing systems.

A challenge to an automated layout of analog ICs starts with the insight into high quality placements crafted by experts. We observe first that matched devices or elemental functions such as input, output, amplifiers, etc are clustered. Second, devices in the same cluster are located faithfully to the drawn schema. Third, these two features are simultaneously fulfilled in a well-compacted placement. This paper proposes a novel device-level placement that simulates the above features based on Sequence-Pair. A slight modification of the meaning, say, of relation "A is left-of B" to relation "A is not right-of B" enlarges the freedom and allows a neater compaction of clusters allowing zigzag border curves. As the consequence, clusters are placed faithfully to relative position in the schema. We tested our algorithm for industrial instances and compared results with those by manual design. The results showed better features in performance figures than the those of manual designs by, on average, 13.5% and 21.2% with respect to the area and total net-length.

We study analysis of hybrid systems under incomplete knowledge. The class of hybrid systems to be considered is assumed to have the form of a rectangular hybrid automaton such that each constant in invariants and guards is given as a parameter. We develop a method based on symbolic computation that computes an approximation of the discrete behavior of the automaton. We also show an implementation on a constraint logic programming language.