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Dive into the research topics where Masayuki Numao is active.

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Featured researches published by Masayuki Numao.


Computer-aided Design | 1997

A cell-based approach for generating solid objects from orthographic projections

Hiroshi Masuda; Masayuki Numao

Abstract This paper describes an efficient method for converting orthographic projections into solid models based on non-manifold topology and the assumption-based truth maintenance system (ATMS), and then describes an error recovery method for incorrect orthographic projections. A combination of non-manifold modelling and ATMS achieves excellent performance for conversion problems. In our method, all solid candidates are maintained by a cellular model using non-manifold topology. Since a combination of cells in a cellular model determines the shape of a solid, solid models that match orthographic projections can be derived by solving constraints between cells and orthographic projections. A sufficient group of constraints can be expressed as a set of Boolean equations, which can be solved efficiently by using ATMS. Our method can even be applied to incorrect draftings. In actual design, many draftings contain human errors, but conventional methods cannot handle such incorrect draftings. We discuss methods for detecting inconsistent lines that should not have been included, or missing lines that should have been included.


Proceedings of the International Workshop on Artificial Intelligence for Industrial Applications | 1988

Scheplan-a scheduling expert for steel-making process

Masayuki Numao; Shinichi Morishita

Scheplan is an expert system kernel that was developed for scheduling steel-making processes. The typical constraints in such processes are a fixed sequence of production stages, no machine conflicts among products, low waiting time, continuous use of some machines, and a resting time requirement for some machines. The approach presented for designing a schedule that satisfies the constraints, is not to obtain an optimal solution, but rather to obtain a feasible solution efficiently. The reason for this is that it is very difficult to define an evaluation function for the optimum, and that a combinatorial explosion may prevent a schedule from being obtained in a reasonable time. A cooperative schedule method is introduced in which the system efficiently generates a candidate schedule by a subscheduling and merging method, and the user evaluates and modifies the candidate schedule by interactive refinement.<<ETX>>


international conference on tools with artificial intelligence | 1991

An ATMS-based geometric constraint solver for 3D CAD

Shuichi Shimizu; Keisuke Inoue; Masayuki Numao

The authors have developed a constraint-based method of describing features. Every feature is controlled by geometric constraints, which naturally specify the dimensioning information that reflects the designers intent. An ATMS-based geometric reasoning system is proposed that efficiently evaluates the constraints in order to determine geometric attributes, and detects over-constrained situations in order to resolve conflicts among the constraints.<<ETX>>


conference on logic programming | 1987

Prolog computation model BPM and its debugger PROEDIT2

Shinichi Morishita; Masayuki Numao

This paper presents a debugger for Prolog ‘PROEDIT2’. In order to express the complex execution mechanism of Prolog, a new execution model for Prolog ‘BPM’ is also proposed. PROEDIT2 shows the execution of Prolog in BPM notation.


european symposium on research in computer security | 2003

Multi-round Secure Light-Weight Broadcast Exclusion Protocol with Pre-processing

Yuji Watanabe; Masayuki Numao

A broadcast exclusion protocol allows a broadcaster to transmit a encrypted message to a set of n users over a broadcast channel so that all but some specified small group of k excluded users can decrypt the message, even if these excluded users collude with each other in an arbitrary manner. Recently, Matsuzaki et al. pointed out a potential problem in the earlier works regarding the number of modular exponentiation, and proposed an extended scheme in which decryption requires only two modular exponentiations regardless of n and k. However, our analysis shows this scheme has a limitation of the number of rounds.


international symposium on computing and networking | 2015

An Efficient Generalized Clustering Method for Achieving K-Anonymization

Xiaoshuang Xu; Masayuki Numao

This paper proposed an efficient generalized clustering method which derives from the k-means algorithm for achieving k-anonymization with good data quality and minimum information loss. We defined the distance function for the three major attribute types: numerical type, categorical type, and structural type. Then we proceeded the method in two stages: preprocessing stage and postprocessing stage. The preprocessing stage is to partitions all records into[n/k] groups, and then add the records that are naturally similar to each other into every group. The postprocessing stage is to add each remaining record into a cluster with respect to which the increment of the information loss is minimal. We experimentally compared our method with other two clustering-based k-anonymization methods. The experiment showed that our method outperforms their method and also ensures the anonymization of data.


Expert Systems With Applications | 1995

An integrated scheduling/planning environment for petrochemical production processes

Masayuki Numao

Abstract Production planning/scheduling is a very difficult task because it has to deal with many conflicting constraints. Some attempts have been made to obtain an optimal solution that satisfies all constraints, but this approach is not practical, because the scheduling problem is NP-complete. This paper proposes a practical approach to actual scheduling and planning problems and describes its application to creating monthly schedules for synthetic rubber production, a typical petrochemical process. Cooperative scheduling is a new approach in which procedures, rules, and the user cooperate to make feasible schedules efficiently. The procedures, collectively called a “scheduling engine,” work as a local constraint satisfier to solve general primitive constraints. Rules that represent domain-dependent knowledge then solve domain-specific constraints by means of a pattern-matching function. Finally, the user evaluates the schedule and modifies it via a user-friendly interface with direct-manipulation functions. The user interaction is therefore included in the system architecture as a global constraint satisfier. The integrated planning and scheduling environment described here was designed within this cooperative framework. The system produces a production plan that satisfies a due date limitation, taking account of stock shortages; the plan is checked concurrently to determine whether it leads to a realizable schedule. The prototype system has been transferred to one of the major petrochemical companies in Japan, and is being tested and evaluated in an actual environment for operational use.


conference on logic programming | 1985

PROEDIT–a screen oriented Prolog programming environment

Masayuki Numao; Hiroshi Maruyama

A screen oriented programming environment for Prolog was designed and implemented. To visualize the control flow of the execution of a Prolog program, A new execution model is proposed, which is based on the box model, but has been extended so that control flow between subgoals is displayed over time. It is written for VM/Prolog which runs under the VM/CMS operating system. The system is actually being used by researchers in IBM laboratories.


international symposium on autonomous decentralized systems | 1999

A secure key registration system based on proactive secret-sharing scheme

Masayuki Numao

We designed a secure key registration system based on the proactive secret-sharing scheme. A user can register important data such as a session key to a distributed system in a (t, n)-threshold scheme, which means that the data can be recovered if t sewers cooperate (in other words, that the data cannot be revealed unless t sewers collude). The proactive scheme provides stronger security against an active adversary. We designed the protocol to generate an implicit secret, to distribute shares of it, and to reconstruct the secret for proactive secret-sharing without a dealer. We also developed a prototype of a data archiving service framework on the Internet. To allow users to access the system via a Web browser, we implemented a system based on the PKI (public key infrastructure), where the client/server authentication is done by means of X.509 certification. We also used the publish/subscribe communication model to realize interaction between key management servers, because it is easy to implement the broadcasting channels used in the share update phase.


international cryptology conference | 1999

Periodical Multi-secret Threshold Cryptosystems

Masayuki Numao

A periodical multi-secret threshold cryptosystem enables a sender to encrypt a message by using a cyclical sequence of keys which are shared by n parties and periodically updated. The same keys appear in the same order in each cycle, and thus any subset of t+1 parties can decrypt the message only in the periodical time-frames, while no subset of t corrupted parties can control the system (in particular, none can learn the decryption key). This scheme can be applied to a timed-release cryptosystem whose release time is determined when the number of share update phases equals the period of the sequence. The system is implemented by sharing a pseudo-random sequence generator function. It realizes n≥3t+1 robustness, and is therefore secure against an adversary who can corrupt at most one third of the parties.

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Haitao Chen

University of Electronic Science and Technology of China

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Jieyun Zhou

University of Electronic Science and Technology of China

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