OBS分片机制中分片比例的性能分析

光突发交换(OBS)网络中,突发分片是有效地解决突发竞争、提高网络性能的一种重要措施,通过对OBS中分片技术的分析,对比了各种突发分片比例对分片机制下OBS网络的丢包率性能影响。仿真表明:当网络处于通常负荷强度时,平均分片比例可使分组的丢包率最低。

降低跨分片交易比例的区块链分片方法

针对分片技术在优化区块链性能时引起的跨分片交易比例过高、跨分片交易验证复杂的问题,提出一种降低跨分片交易比例的区块链分片方法。首先,从数据分片的角度出发,构造区块链交易分片模型,并给出分片性能评价指标;其次,针对区块链中长期积累的交易数据,从账号关联性角度出发,构造发送方和接收方的交易频次集合;最后,设计考虑交易频次的区块链交易分片算法(FBTS),从而解决交易分片中跨分片比例过高的问题。在分片粒度为2、3、5、7、15、20、30和50的情况下,所提算法在跨分片交易比例、账号平均跨分片次数、账号的加权平均跨分片次数等性能指标方面均优于随机分片算法(RSA)和取模分片算法(MSA)。另外所提算法的大多数账号和交易量都集中分布在低跨分片次数处,说明交易的完成不需要多次跨分片。实验结果表明,所提算法可以有效地降低跨分片交易比例,缩短跨分片的交易的时延。

Precise Control of Temperature Rising Speed of Wafer during Rapid Thermal Processing

In rapid thermal processing of a semiconductor wafer, it is important to keep a given temperature rising speed of the wafer during the temperature rising process. We made an experimental apparatus to measure the temperature rising speed of a ceramic ball of 2 mm in diameter heated with four halogen lamp heaters. The heating rate of the halogen lamp heaters was controlled by computer to keep a given temperature rising speed of 50 ℃/s with a controlling time interval of 0.1 s. We examined the effect of various heating control methods on the error of the temperature rising speed of the ceramic ball. We found that a combined method of control with prepared correlation and PID （proportional integral derivative） control is a good method to decrease the error of the temperature rising speed. The average error of the temperature rising speed is 0.5 ℃/s, and the repetition error is almost zero for the temperature rising speed of 50 ℃/s from 330 ℃ to 370 ℃. We also measured the effects of artificial control delay time and measuring error of the monitoring temperature on the error of the temperature rising speed.