Fan Hehong

Connectivity reliability evaluation for optical layer in IP over WDM networks based on minimal path sets

Reliability evaluation of communication network is the precondition of researching how to provide various traffic QoS (quality of service) guarantee. This paper presented an evaluation method for WDM (wavelength division multiplexing) optical layers connectivity reliability. First, we calculated all the minimal path sets of source-destination node pairs in the network using optimized node-traversal method and direct disjoint method according to adjacency matrix and network structure parameters matrix, then obtained connectivity reliability of source-destination node pairs through probability solution, furthermore, MTBF (mean time between failures) and failure frequency of the network were figured out. Simulation on CERNET, NSFNET and MESH-TORUS network showed that connection reliability of the MESH-TORUS is higher than that of the former two. Data results based on this method is an important reference of integrated reliability evaluation for the whole optical networks

Individual evaluation for freshman in small size group

Individual evaluation in small size groups is an important part for collaborative learning. To evaluate individual contributions, we use a comprehensive assessment method including self-evaluation and mutual-evaluation in freshmen seminar course in Southeast University of china. And the comparison and problem between self-evaluation and mutual-evaluation are presented and analyzed. Relations of the scores between leaders, members and their projects are discussed. Analysis shows that the proposed method could be an effective way to evaluate individual contributions to groups. However, the conclusion may depend strongly on the background that the course is for freshman in an engineering school.

An engineering introductory seminar course for first-year college students

To help first year students adapt to their college lives and to enhance student learning, freshman seminar courses have been popular in many advanced countries. However, seminar courses in China are still in the beginning stage and are mainly for elective courses considering the large number of students in many majors. In this paper, implementation of a new required freshman seminar course, “Introduction to learning in the specialty of electronics and information” in Southeast University, is introduced. The course is composed of three education stages, i.e., lecture, investigation and project, during which the students can have closer and closer views to the applications of electronic science and engineering, and gain in-depth experience of relevant projects step by step. In addition, by making use of flexible class forms, various teaching methods, composite evaluation methods, and collaboration of a teacher team, the seminar course has been successfully run for about 170 students for the first time.

A novel fuzzy evaluation method to evaluate the reliability of FIN

Based on fuzzy theory, we present the novel concept that a complex system should be described with multiple state linguistic terms (SLT). A network performability index given, the reliability indices of the object with multiple working-state are defined for the first time. On the grounds of linguistic cloud model (LCM), a fuzzy evaluation method for the network reliability is introduced. The method is used to examine the reliability of the fiber industry network (FIN) by way of Monte Carlo simulations. The results for FIN show that the method is efficient for reliability evaluation of industrial control networks thus can be used as a tool to design highly reliable industry networks.

An improved three-dimensional full-vectorial finite-difference imaginary-distance beam propagation method

A modified alternating direction implicit approach is proposed to discretize the three-dimensional full-vectorial beam propagation method (3D-FV-BPM) formulation along the longitudinal direction. The cross-coupling terms (CCTs) are neglected at the first substep, and then double used at the second substep. The order of two substeps is reversed for each transverse electric field component so that the CCTs are always expressed in an implicit form, thus the calculation is efficient and stable. Based on the multinomial interpolation, a universal finite difference scheme with a high accuracy is developed to approximate the 3D-FV-BPM formulation along the transverse directions, in which the discontinuities of the normal components of the electric field across the abrupt dielectric interfaces are taken into account and can be applied to both uniform and non-uniform grids. The corresponding imaginary-distance procedure is first applied to a buried rectangular and a GaAs-based deeply-etched rib waveguide. The field patterns and the normalized propagation constants of the fundamental and the first order modes are presented and the hybrid nature of the full-vectorial guided-modes is demonstrated, which shows the validity and utility of the present approach. Then the modal characteristics of the deeply-and shallow-etched rib waveguides based on the InGaAsp/InGaAsP strained multiple quantum wells in InP substrate are investigated in detail. The results are necessary for modeling and the design of the planar lightwave circuits or photonic integrated circuits based on these waveguides.

Cathode life evaluation based on the evolution of heater power and perveance

Reliability of cathodes is critical for the reliability of traveling wave tubes. Accordingly, the reliability test and life prediction of diodes can provide useful information for cathode and TWT reliability evaluation. In this paper, a simple cathode life prediction method considering the evolving of heater power and perveance is presented. The method is applied on the reliability test data for some glass diode samples and several gun samples. The evaluation results show that the cathode life in the electron guns is much longer than those in the diode samples. And the cathode life prediction result for the diodes, based on the evolving of perveance and heater power for a certain anode current and voltage, is close to the final test result.