The quality of an architectural design of a software system has a great influence on achieving non-functional requirements to the system, so formal evaluation and validation techniques to designed architectures are necessary in the early phase of development processes. In this paper, we present a technique for describing software architectures formally based on Coloured Petri Nets (CPNs) and a technique for reusing architectural constituents. Architectural descriptions are essentially written with a CPN language, so that the evaluation and analysis on the architectural descriptions can be made in architectural design phrase. We extract reusable architectural parts from standard architecture styles and architectural patterns so that a designer can construct an architecture by only retrieving the parts and combine them. We also designed the language for describing the combination of the architectural parts. To show the effectiveness of our techniques, we illustrate how a blackboard architecture can be composed of reusable parts and be simulated on a CPN tool (Design/CPN).

In a software maintenance phase, since quality assurance engineers frequently only change source codes, the consistency between the source codes and their specification documents cannot be kept. In this paper we propose a supporting technique for changing specification documents automatically so that the specifications can be consistent with the source codes. In our technique, we represent a program with multiple graphs and we consider the changes on programs as the modification of the graphs. The modification of the graphs is formalized with a sequence of the operation on the graphs. We design the rules of how to relate the operations on program graphs to the operations on graphs that represent specification documents. By applying these rules, we can detect what modification and which parts of the specification document should be made to maintain the consistency between the specification and the program, when the program is modified.

A software requirements specification (SRS) is a document at the first phase of software development. Since it is difficult to make an accurate SRS at the beginning of software development, we propose a supporting method to detect and interpret the inconsistency of SRS. First, we classify and define the inconsistency of SRS. Next, we describe how to detect and interpret the inconsistency of SRS. We use the Requirements Frame Model to detect the inconsistency of SRS. We apply the Dempster and Shafer's theory to interpret the inconsistency of SRS. We illustrate our method with an example.

This paper proposes a method of automatically eliciting knowledge which is used to detect feature interactions in telecommunication services. With conventional methods, the knowledge is provided manually. With the proposed method, the knowledge is automatically elicited as service constraints. In telecommunication systems, when a new service is added, new state transitions are created. In case of new service, the new state should be reached in the state transitions. On the other hand, some states of existing services should not be reached. These constraints can be considered as knowledge for detecting feature interactions. This paper also proposes a scenario for detecting feature interactions using elicited knowledge. This scenario was confirmed as effective.

There are the following three targets to be achieved in a software project from the three viewpoints of process management (or progress management), cost management, and quality management for software project to be successful: (a) drafting a software development plan based on accurate estimation, (b) early detection of risks that the project includes based on correct situation appraisal, (c) early avoidance of risks that the project includes. In this paper, the authors propose a method and facilities to project risks in a software project through Kepner-Tregoe program, and propose schedule re-planning by using genetic algorithm for avoiding the projected risks. Furthermore the authors show, from the results of execution of the system, that the system is effective in early avoidance of risks that the software project includes.

Knowledge-based program understanding is widely known as one of the key issues in programming education support systems and environments for novices. Most program understanders, however, have limitations. One of them is an ability to deal with a single programming language, while human tutors can comprehend plural languages by means of generalized knowledge on programming languages and techniques. This paper proposes the concepts and methodology of the knowledge-based program understander ALPUS II, which deals with plural programming languages, i. e. , Pascal and C, by means of generalized abstract syntax AL and knowledge representations based on it. ALPUS II is an extension of ALPUS, which dealt with a single programming language Pascal, and is a sub-system of an intelligent programming environment INTELLITUTOR. The INTELLITUTOR system consists of a guided programming editor GUIDE and a knowledge-based program understander ALPUS II, and is available on the Internet. In the process of comprehension source statements written in Pascal or C are translated into AL representation first. Since the contents of the programming knowledge bases are adjusted to deal with the AL representations the program comprehension procedure is available for both Pascal and C. It is possible to append other programming languages by simply attaching a transformation module for each additional procedural language. It is noted that knowledge acquisition tasks for additional languages are not needed since the contents of the knowledge base are generalized for multiple use. The INTELLITUTOR system was implemented in the frame-based knowledge engineering environment ZERO on a UNIX server machine in the Internet environment. ALPUS II demonstrates interesting features in program comprehension for the C language by means of the transformed knowledge from the already available knowledge for Pascal, which was developed for ALPUS, in a feasibility study. The current version of ALPUS II supports almost full specifications for Pascal and a Pascal-associated subset for C. This limitation should be reasonable for programming practice at freshmen classes of a university.

The construction of photo-realistic 3D scenes from video data is an active and competitive area of research in the fields of computer vision, image processing and computer graphics. In this paper we address our recent work in this area. Unlike most methods of 3D scene construction, we consider the generation of virtual environments from video sequence with a video-cam's forward motion. Each frame is decomposed into sub-images, which are registered correspondingly using the Levenberg-Marquardt iterative algorithm to estimate motion parameters. The registered sub-images are correspondingly pasted together to form a pseudo-3D space. By controlling the position and direction, the virtual camera can walk through this virtual space to generate novel 2D views to acquire an immersive impression. Even if the virtual camera goes deep into this virtual environment, it can still obtain a novel view while maintaining relatively high resolution.

We propose a learning algorithm for simple deterministic languages from queries and a priori knowledge. To the learner, a special finite subset of the target language, called a representative sample, is provided at the beginning and two types of queries, equivalence queries and membership queries, are available. This learning algorithm constructs nonterminals of a hypothesis grammar based on Ishizaka(1990)'s idea. In Ishizaka(1990)'s algorithm, the learner makes rules as many as possible from positive counterexamples, and diagnoses wrong rules from negative counterexamples. In contrast, our algorithm guesses a simple deterministic grammar and diagnoses them using positive and negative counterexamples based on Angluin(1987)'s algorithm.

We propose a new inferring programmers' intention system COSMO based on a classification of assignment statements. COSMO is a subsystem of our intelligent programming environment for programming education. The programming environment consists of a program understanding system designed for novice programmers and a novice program evaluation support system designed for teachers, both of which use the technique of the program slicing. Usually, the method of program slicing requires selection of slicing criteria. However, automatic selection of effective slicing criteria is difficult. Here we propose a new inferring programmers' intention system COSMO with automatic selection of effective slicing criteria. In our system, the slicing criteria are inferred using the context structure model of programs. Programs are regarded as natural language texts in the model and analyzed using a similar thinking in context structure analyses of natural language texts. The model is based on a classification of assignment statements using dependence analysis of programs. Furthermore, COSMO obtains networks with information on top-down decomposition of problems as a result of inferring programmers' intention. Therefore, COSMO is useful for understanding programs without presupposed knowledge.

This paper describes the architecture to implement an application in network environments, which adapts to unexpected change in the development phase. In this architecture, an application is expressed as an agent which consists of two layers: base level and meta level. The base level program is an application program and the meta level program is the program that controls the execution of the base level and changes the base level program. Virtual places are also provided in the network. They are used for the release of programs and information which agents retrieve to change their own base level program. An application (or an agent), when a change is required, moves from places to places for the retrieval of programs to adapt to the change. A program search strategy is introduced to adapt to changes by using distributed thesauri of released programs, which realizes an agent's program retrieval method in network environments.

Continuous-wave operation at room-tempera-ture has been demonstrated for InGaN multi-quantum-well (MQW) laser diodes (LDs) grown on FIELO GaN substrates with a backside n-contact. This was made possible by introducing important new concept of reducing threading dislocations that occur during the growth of the GaN substrates. We found that InGaN active layers grown on FIELO GaN are superior to those grown on conventional sapphire substrates in terms of their growth mode and the resultant In compositional fluctuation. The fabricated laser diode shows the threshold current, the threshold current density and the threshold voltage were 36 mA, 5.4 kA/cm2 and 7.5 V, respectively, with the lasing wavelength of 412 nm and internal quantum efficiency as high as 98%.

Let l be a positive integer, and let G be a graph with nonnegative integer weights on edges. Then a generalized vertex-coloring, called an l-coloring of G, is an assignment of colors to the vertices of G in such a way that any two vertices u and v get different colors if the distance between u and v in G is at most l. In this paper we give an algorithm to find an l-coloring of a given graph G with the minimum number of colors. The algorithm takes polynomial time if G is a partial k-tree and both l and k are bounded integers.

This paper presents a dosimetric analysis in an anatomically realistic human head model for a helical antenna portable telephone by using the finite-difference time-domain (FDTD) method. The head model, developed from magnetic resonance imaging (MRI) data of a Japanese adult head, consists of 530 thousand voxels, of 2 mm dimensions, segmented into 15 tissue types. The helical antenna was modeled as a stack of dipoles and loops with an adequate relative weight, whose validity was confirmed by comparing the calculated near magnetic fields with published measured data. SARs are given both for the spatial peak value in the whole head and the averages in various major organs.

The Virtual Path (VP) concept in ATM networks simplifies network structure, traffic control and resource management. For VP formulation, a VP can carry traffic of the same type (the separate scheme) or of different types (the unified scheme). For VP adjustment, a certain amount of bandwidth can be dynamically assigned (reserved) to VPs, where the amount (the bandwidth incremental/decremental size) is a predetermined system parameter. In this paper, we study Least Loaded Path-based dynamic routing schemes with various residual bandwidth definitions under different bandwidth allocation (VP formulation and adjustment) schemes. In particular, we evaluate the call blocking probability and VP set-up processing load with varying (bandwidth) incremental sizes. Also, We investigate numerically how the use of VP trades the blocking probability with the processing load. It is found that the unified scheme could outperform the separate scheme in certain incremental sizes. Moreover, we propose two ways to reduce the processing load without increasing the blocking probability. Using these methods, the separate scheme always outperforms the unified scheme.

This is a survey of algorithmic results in the theory of "discrete convex analysis" for integer-valued functions defined on integer lattice points. The theory parallels the ordinary convex analysis, covering discrete analogues of the fundamental concepts such as conjugacy, the Fenchel min-max duality, and separation theorems. The technical development is based on matroid-theoretic concepts, in particular, submodular functions and exchange axioms.

In this paper, a puzzle called Cell-Maze is analyzed. In this puzzle, cells are arranged in checker board squares. Each cell is rotated when a player arrives at the cell. Cell-Maze asks whether or not a player started from a start cell can reach a goal cell. The reachability problem for ordinary graphs can be easily solved in linear time, however a reachability problem for the network such as Cell-Maze may be extremely difficult. In this paper, NP-hardness of this puzzle is proved. It is proved by reducing Hamiltonian Circuit Problem of directed planar graph G such that each vertex involved in just three arcs. Furthermore, we consider subproblems, which can be solved in polynomial time.

Given a combinatorial problem on a set of weighted elements, if we change the weight using a parameter, we obtain a parametric version of the problem, which is often used as a tool for solving mathematical programming problems. One interesting question is how to describe and analyze the trajectory of the solution. If we consider the trajectory of each weight function as a curve in a plane, we have a set of curves from the problem instance. The curves induces a cell complex called an arrangement, which is a popular research target in computational geometry. Especially, for the parametric version of the problem of computing the minimum weight base of a matroid or polymatroid, the trajectory of the solution becomes a subcomplex in an arrangement. We introduce the interaction between the two research areas, combinatorial optimization and computational geometry, through this bridge.

This paper surveys how geometric information can be effectively used for efficient algorithms with focus on clustering problems. Given a complete weighted graph G of n vertices, is there a partition of the vertex set into k disjoint subsets so that the maximum weight of an innercluster edge (whose two endpoints both belong to the same subset) is minimized? This problem is known to be NP-complete even for k = 3. The case of k=2, that is, bipartition problem is solvable in polynomial time. On the other hand, in geometric setting where vertices are points in the plane and weights of edges equal the distances between corresponding points, the same problem is solvable in polynomial time even for k 3 as far as k is a fixed constant. For the case k=2, effective use of geometric property of an optimal solution leads to considerable improvement on the computational complexity. Other related topics are also discussed.

A novel polarimetric fiber optics current sensor configuration using an in-line 22.5 degree Faraday rotator is proposed on this paper. The introduction of the 22.5 degree Faraday rotator allows to obtain a sensor configuration that does not require adjustment on most optical elements, resulting in an accuracy immune to manufacturing issues. Two prototypes are presented in this paper that are designed to measure AC current, yielding in an excellent accuracy over more than 3 decades.

Signal conservation logic (SCL) is a model of logic for the physical world subject to the matter conservation law. This letter proves that replication, complementary replication, and computational universality called elemental universality are equivalent in SCL. Since intelligence has a close relation to computational universality, the presented theorem may mean that life under the matter conservation law eventually acquires some kind of intelligence.