A digital wide range neutron flux measuring system for HL-2A

To achieve wide-range, high-integration, and real-time performance on the neutron flux measurement on the HL-2A tokamak, a digital neutron flux measuring（DNFM） system based on the peripheral component interconnection（PCI） e Xtension for Instrumentation express（PXIe） bus was designed.This system comprises a charge-sensitive preamplifier and a field programmable gate array（FPGA）-based main electronics plug-in. The DNFM totally covers source-range and intermediate-range neutron flux measurements, and increases system integration by a large margin through joining the pulse-counting mode and Campbell mode. Meanwhile, the neutron flux estimation method based on pulse piling proportions is able to choose and switch measuring modes in accordance with current flux, and this ensures the accuracy of measurements when the neutron flux changes suddenly. It has been demonstrated by simulated signals that the DNFM enhances the full-scale measuring range up to 1.9×10^8cm^-2s^-1, with relative error below 6.1%. The DNFM has been verified to provide a high temporal sensitivity at 10 ms time intervals on a single fission chamber on HL-2A.

Performance Analysis for Dispensing Mechanism of Active Code

The dispensing mechanism of active code is a key technology in an active network. Conventional capsule and programmable switch approaches have their own shortcomings. The DCCAN(distributed code caching for active network) mechanism presented in this paper overcomes these shortcomings. In this paper, capsule and programmable switch approaches are introduced, and their shortcomings are analyzed. The principle of the DCCAN mechanism is described. The theory analysis in transmit width based on the DCCAN mechanism and capsule approach are described. The theory analysis shows that the DCCAN mechanism has many good characteristics and can improve the efficiency of an active network. Key factors which affect the transmit width based on the DCCAN mechanism are discussed. The using condition of the DCCAN mechanism is also discussed.

Research on Dispensing Mechanism of Active Code in Active Network

The dispensing mechanism of active code is the key technology in activenetwork. Conventional capsule and programmable switch approaches have their own shortcomings. DCCANmechanism presented in this paper overcomes their shortcomings. In this paper, capsule andprogrammable switch, approaches are introduced and their shortcomings are analyzed. The principle ofDCCAN mechanism is described. The theoretical analyses in transmission bandwidth based on DCCANmechanism and capsule approach are described, and key factors which affect the transmissionbandwidth based on DCCAN mechanism are also discussed. At the same time, the theoretical analyses inlatency based on DCCAN mechanism and capsule approach are described. The using condition of DCCANmechanism is also discussed.

Analyzing and Optimizing Packet Corruption in RDMA Network

Remote direct memory access (RDMA) has become one of the state-of-the-art high-performance network technologies in datacenters. The reliable transport of RDMA is designed based on a lossless underlying network and cannot endure a high packet loss rate. However, except for switch buffer overflow, there is another kind of packet loss in the RDMA network, i.e., packet corruption, which has not been discussed in depth. The packet corruption incurs long application tail latency by causing timeout retransmissions. The challenges to solving packet corruption in the RDMA network include: 1) packet corruption is inevitable with any remedial mechanisms and 2) RDMA hardware is not programmable. This paper proposes some designs which can guarantee the expected tail latency of applications with the existence of packet corruption. The key idea is controlling the occurring probabilities of timeout events caused by packet corruption through transforming timeout retransmissions into out-of-order retransmissions. We build a probabilistic model to estimate the occurrence probabilities and real effects of the corruption patterns. We implement these two mechanisms with the help of programmable switches and the zero-byte message RDMA feature. We build an ns-3 simulation and implement optimization mechanisms on our testbed. The simulation and testbed experiments show that the optimizations can decrease the flow completion time by several orders of magnitudes with less than 3% bandwidth cost at different packet corruption rates.