We developed a new water repellent coating consisting of PTFE particles dispersed in PVDF resin. This coating exhibited a contact angle of 150 degrees. By ice accreting test, the intensity of reflected microwave on the water-repellent coated plate did not decrease, whereas that on uncoated one decreased.

QoS restoration, a new approach to keep QoS of end-to-end ATM connections for failures is proposed. In a network with QoS restoration, each end-to-end connection's customer pre-defines the minimum QoS requirements such as minimum throughput. When a failure occurs, resources such as bandwidth of working connections are reallocated for restoration if they are dispensable to keep the minimum requirements along with the pre-assigned spare resources. This resource reallocation is done in a distributed manner and the result of the modification of a connection is notified to the customer of the connection to help him adjust the way of using it. The effect of the reallocation is mathematically evaluated. It is shown that the reallocation enables to achieve high restoration ratio with insufficient pre-assigned spare resources, such as to restore double-link failures with spare resources prepared for single-link failures, or even to restore single-link failures with no spare resources. It is also shown that pre-assigned spare resources can be reduced if the reallocation is considered in network design phase. The performance of the proposed distributed algorithm is evaluated with an event-driven simulator. The result shows that regardless of whether or not pre-assigned spare resources exist, a restoration ratio which is close to the theoretical maximum can be achieved. A proof-of-concept experimental system is developed by controlling commercial ATM switches via SNMP. The system shows it can effectively manage failures in WAN environment.

This paper proposes an optimal design scheme for photonic transport networks that interconnect multiple wavelength division multiplexing (WDM) self-healing ring systems by using optical cross connects (OXCs). To calculate the number of OXCs required in each hub to interconnect these ring systems, a virtual mesh network is generated, on which the route of each optical path (OP) going through multiple adjacent rings ("ring" is defined as circle in network topology) is determined based on a list of hubs. An integer-programming-based design problem is then formulated that minimizes the overall cost of facilities including OXCs as well as ring systems to accommodate a given demand. By solving this problem, we can simultaneously optimize required number of ring systems in each ring, wavelength assignment within each individual bidirectional ring system, required number of OXCs in each hub, and capacity to be allocated to each OP. Numerical examples show that the ring-based network is more cost-effective than the mesh restorable network when the cost of an OADM is lower than that of an OXC, and the OXC-to-fiber cost-coefficient ratio is sufficiently large.

Capital expenditure (CAPEX) reduction and efficient wavelength allocation are critical for the future access networks. Elastic lambda aggregation network (EλAN) based on WDM and OFDM technologies is expected to realize efficient wavelength allocation. In this paper, we propose adaptive bandwidth allocation (ABA) algorithm for EλAN under the conditions of crowded networks, in which modulation format, symbol rate and the number of sub-carriers are adaptively decided based on the distance of PON-section, QoS and bandwidth demand of each ONU. Network simulation results show that the proposed algorithm can effectively reduce the total bandwidth and achieve steady high spectrum efficiency and contribute to the further reduction of CAPEX of future optical access networks.

A total-field/scattered-field (TF/SF) boundary which is commonly used in the finite-difference time-domain (FDTD) method to illuminate scatterers by plane waves, is developed for use in the constrained interpolation profile (CIP) method. By taking the numerical dispersion into account, the nearly perfect TF/SF boundary can be achieved, which allows us to calculate incident fields containing high frequency components without fictitious scattered fields. First of all, we formulate the TF/SF boundary in the CIP scheme. The numerical dispersion relation is then reviewed. Finally the numerical dispersion is implemented in the TF/SF boundary to estimate deformed incident fields. The performance of the nearly perfect TF/SF boundary is examined by measuring leaked fields in the SF region, and the proposed method drastically diminish the leakage compared with the simple TF/SF boundary.