Simulation Research of Charged Particle Discrimination Methods

A simple model was used to simulate the current pulse induced by charged particles with Si detector. With simulated current shapes of three element groups, H/D/T (6MeV), He-3/He-4 (15MeV) and Li-6/Li-7 (35MeV), three methods of pulse shape analysis (PSA), i.e. the m2-m3 method, the integration method and the second moment method, were compared and analyzed. Their discrimination performance and noise resisting property are investigated. The results show that the charge integration method and the m2-m3 method both have good discrimination performance and noise resisting property. While neither the discrimination performance nor the noise resisting property of the second moment method is satisfactory.

The Stability Studies of the Message Transmission in CAN Bus

The message transmission stability is very important for the design of the CAN bus system, which is related to the normal operation of the bus control system. The message transmission time is analyzed based on the Tindell scheduling theory, and the message transmission stability analysis is studied by means of probability analysis based on the second-moment method. An example in vehicle is calculated to get its message stability and the result is contrasted with the MONTE-CARLO method, and then the message transmission stability can be got using the method above; this will be the basis for calculating the stability of the CAN bus system, and provides the foundation for the further scheduling theory studies. It has great practical significe for CAN bus.

The Application of Hasofer-Lind Method in Reliability Design of Thin-Walled Cylindrical Shell

Hasofer-Lind method was applied to reliability design of cylindrical shell with internal pressure. The respective reliability design thickness of different diameter ratio was obtained in the case and compared with the thickness by the second moment reliability design method. The results showed that the wall thickness of cylindrical shell with internal pressure is the thinnest by using Hasofer-Lind method. And it is closest to the wall thickness of the second moment method in which the performance function was defined as the difference in actual wall thickness and the wall thickness needed for cylindrical shell with internal pressure.

On the Domination Number of a Random Graph

In this paper, we show that the domination number $D$ of a random graph enjoys as sharp a concentration as does its chromatic number $\chi$. We first prove this fact for the sequence of graphs $\{G(n,p_n\},\; n\to\infty$, where a two point concentration is obtained with high probability for $p_n=p$ (fixed) or for a sequence $p_n$ that approaches zero sufficiently slowly. We then consider the infinite graph $G({\bf Z}^+, p)$, where $p$ is fixed, and prove a three point concentration for the domination number with probability one. The main results are proved using the second moment method together with the Borel Cantelli lemma.

Spanning Subgraphs of Random Graphs

Let Gp be a random graph on 2d vertices where edges are selected independently with a fixed probability p > ¼, and let H be the d-dimensional hypercube Qd. We answer a question of Bollobás by showing that, as d → ∞, Gp almost surely has a spanning subgraph isomorphic to H. In fact we prove a stronger result which implies that the number of d-cubes in G ∈ [Gscr ](n, M) is asymptotically normally distributed for M in a certain range. The result proved can be applied to many other graphs, also improving previous results for the lattice, that is, the 2-dimensional square grid. The proof uses the second moment method – writing X for the number of subgraphs of G isomorphic to H, where G is a suitable random graph, we expand the variance of X as a sum over all subgraphs of H itself. As the subgraphs of H may be quite complicated, most of the work is in estimating the various terms of this sum.