Modeling of ad hoc sensor networks becomes difficult when uncertain features of the network increase. Deterministic modeling is difficult and some stochastic arguments should be introduced instead. In this paper, we introduce the concept of random networks. One remarkable feature of random graphs is that a phase transition occurs as the probability of edge connection increases. At the critical probability, fragmented pieces of edges suddenly start to be mutually connected, forming one large component. This graph-theoretical change parallels phase transitions in states of mutter, e.g. the jump from water to ice. In ad hoc sensor networks, the nodes are connected by wireless links. In order to meet this requirement, we propose a model using percolation, a kind of random graph where the edges are formed only between the nearby nodes. We also present some numerical examples to simulate the jump effects of the phase transition.

Supporting rapid response to changing customer requirements, reduction in both time and cost of manufacturing process, and integration within a heterogeneous wide area networked enterprise are necessary to increase worldwide competitiveness in manufacturing. We propose a CORBA based architecture to realize that manufacturing environment. We have developed an ORB for PLC to realize that architecture. And we have developed two prototypes of a remote monitoring system for factory automation, which are a manufacturing line monitoring system and a remote PLC monitoring system which uses a Web browser, to examine feasibility and effectiveness of the proposed architecture. According to experiments with these prototypes, we show the feasibility and effectiveness of our proposed CORBA based architecture.

LAN systems are widely used in distributed environment and it becomes more indispensable to manage distributed LAN systems in an integrated manner as enterprise-level networks. This paper describes the LAN fault management ensemble which has been developed by the Ensemble Team of INTAP NM (Network Management) Technical Committee. Ensembles represent specific solutions to particular problems of the networks as a collection of managed resources, functions and scenarios. This ensemble provides a method of managing an enterprise-level private network in particular fault management areas. OSI management is adopted as a platform to manage LANs which are assumed to be managed by SNMP or OSI layer management protocols. This ensemble takes a state-oriented approach which is better suited, and provides more efficient integrated network management for large-scale enterprise networks containing many resources to be managed, because SNMP management is performed by polling based on the stateless approach. In addition, this ensemble adopts international standards or publicly available specifications regarding the necessary management information. Integrated management is executed by the OSI manager and proxy agents. Proxy agents act as OSI agents and convert information gathered by SNMP manager/agents or OSI layer management entities to OSI. Various network resources such as FDDI, Ethernet and MIB-II are defined on the basis of definition of the ISO/IEC, IEEE and NM Forum standards and additional necessary resources are uniquely defined for this ensemble requirements.

The authors describe the design of a testing environment, called FOREST (formal environment for systematic testing), for communication systems. The proposed method integrates three major strategies: (1) the use of formal description techniques (FDTs), for their formal semantics, which makes them unambiguous; (2) a stepwise approach to generate appropriate test cases for different test stages; and (3) the systematic support of the testing process, from test development to test execution. FOREST consists of four major subsystems. TENT (test sequence generation tool) is a subsystem that generates test cases from the formal specification of the behavior of a given protocol. APRICOT (ASN.1 pre-compiler, coder and test-debugger) is a subsystem that generates test data from the protocol data structures definition. TESPEC (test specification editor) is a tool producing some test specification based on a standardized formalism. The last subsystem, TEXEC (test executor), is a test execution system which consists of an upper tester and a lower tester, and a simulator of the communication medium.>

The testing environment FOREST (formal environment for systematic testing), which uses formal description techniques systematically, has been developed. FOREST generates the TTCN format test sequence from the specification described in SDL. Furthermore, FOREST generates the test data from the protocol data definition described in ASN.1. By using the FOREST system, the test specification and test execution and test report description are achieved systematically. Therefore, the cost of the testing phase of OSI upper layer software development is reduced. In particular, the facility for test sequence generation of FOREST realizes high coverage with a reasonable cost. The facility can efficiently check protocol specifications. The effectiveness of the approach is demonstrated by an application to the test design for the CCR protocol.>