基于模型预测控制的数据中心节能调度算法

如今日益增长的数据中心能耗,特别是冷却系统能耗已日益受到重视,降低系统能耗能够减少数据中心碳排放.提出了一种基于模型预测控制（model prediction control,简称MPC）的节能调度策略,该策略可以有效地减小数据中心冷却能耗.该方法采用动态电压频率调节技术来调整计算节点频率,从而减少节点间的热循环;所有节点的峰值温度可被保持在温度阈值下,在任务的执行中稳态误差较小.该方法可以通过动态频率调节来抑制由于负载类型变化造成的模型不确定性带来的内部扰动,分析结果表明,基于模型预测的温控算法系统开销较小,具有良好的可扩展性.基于该算法设计的控制器能够有效地降低输入温度,提高数据中心能耗效率.通过在实际数据中心内运行的模拟网上书店,该方法与安全最小热传递算法和传统反馈温控算法这两种经典方法相比,无论是在正常条件下还是在扰动存在的情况下都能取得较好的温度抑制效果,系统性能如吞吐率也达到最大.在相同的负载条件下,该方法能够获得最小的输入峰值温度和最小的冷却能耗.     

Plane waves in pyroelectrics with viscous effect

The present paper analyzes the propagation of plane waves in an infinite pyroelectric medium. In order to consider the real situation, a new thermo-electric-elastic model with viscous effect is presented. The theoretical analysis shows that the elastic viscous effect and the Fourier’s law are in the same level in the evolution equations. So, the thermal viscous effect in Cattaneo’s equation belongs to a second-order effect. Numerical calculations are performed for pyroelectric material BaTiO₃ using three models (Kaliski–Lord–Shulman theory, inertial entropy theory and inertial entropy with viscous effect). Results show that the elastic viscous relaxation time τ ₀ plays a large role on the mechanical waves and admits mechanical waves decaying in propagation process. The effects of the thermo-relaxation time τ _s on the attenuation of mechanical waves are also researched and discussed in detail.     

基于FPGA实现的多轴数控雕刻机系统

介绍一种基于FPGA和MCU配合的数控雕刻机系统,由MCU来完成读取数据,数据处理和响应键盘,液晶显示等人机交互工作,利用FPGA设计一种发送脉冲控制步进电机工作的定制电路,该系统可以做到精确的速度控制以及连续弧线和连续的字体沟边运动。本文着重介绍数据的预处理、MCU和FPGA的数据传送以及如何用FPGA设计定制电路,实现发送脉冲控制步进电机工作的功能。     

基于事理知识图谱的舆情推演方法

一直以来舆情态势发展的多元性、复杂性使其难以有效管控,一些负面舆情会激化矛盾,给社会安定带来不利影响.提出了一种基于事理知识图谱的舆情事件推演方法,通过神经网络挖掘事件因果逻辑,连接因果事件构成事理知识图谱.向量化事件节点以融合归并相似节点降低图谱冗余,增强图谱泛化性.根据事理知识图谱反映的发展逻辑对目标舆情事件的演化趋势进行预测.以自然灾害舆情事件为例,实验结果表明提出的方法能够有效预测舆情事件发展方向,可以为舆情监管提供一定支持.     

Synthesis and characteristics of carbon-coated iron and nickel nanocapsules produced by arc discharge in ethanol vapor

Fe(C) and Ni(C) nanocapsules with low carbon content have been produced via an arc discharge process in ethanol vapor. It is clarified by X-ray diffraction that the core of the Fe(C) nanocapsules consists of γ-Fe, α-Fe and Fe₃C phase, while that of the Ni(C) nanocapsules contains only nickel. High-resolution transmission electron microscopy imaging confirms that these particles have a broad size distribution and the core/shell structure. Besides mutually independent nanocapsules with segregate graphitic shells, those with sharing shells are also observed in the Fe(C) nanocapsules. The remanence and the coercivity at room temperature of both the nanocapsules are higher than those of the corresponding microcrystallines, while the saturation magnetization is lower.     

Effect of mechanical milling and heat treatment on the structure and magnetic properties of gas atomized Mn-Al alloy powders

Ferromagnetic Mn-Al alloy powders were fabricated by mechanical milling and heat treatment with gas-atomized powders. Different processes, i.e., heat treatment before ball milling and ball milling before heat treatment, result in different microstructures and magnetic properties of the powders. It was found that H_c increased and M_r decreased with the size reduction regardless of the sequence of heat treatment and ball milling. However, tendency of the change in H_c and M_r depended on the sequence. Further annealing of the powders ball-milled after heat treatment resulted in slight decrease of H_c and large increase of M_r. The magnetic properties, M_r = 41.2 emu/g, H_c = 3.1 kOe, were obtained from the powders ball-milled for 5 h after heat treatment at 650 °C for 20 min, and subsequent annealing at 280 °C for 20 min.     

食品加工新型杀菌技术研究进展

食品杀菌是食品加工过程不可或缺的环节之一。本文介绍了食品工业中新型杀菌技术和设备的研究进展,重点阐述了超高压杀菌、微波杀菌、高压脉冲电场杀菌、辐照杀菌、脉冲强光杀菌等新型杀菌技术与装备的研究发展进程,并扼要地介绍了相关技术特点。新型杀菌技术特别是冷杀菌技术可以更好地保持食品品质和风味,保证食品质量安全。     

保健食品桂芍舒逸口服液的工艺优选与质量标准建立

目的 对桂芍舒逸口服液制作工艺进行优选, 并建立质量控制方法。方法 以芍药苷为测定指标, 利用正交试验优选出最佳制备工艺; 采用薄层色谱法对黄芪、白芍、炙甘草进行鉴别研究; 采用高效液相色谱法(high performance liquid chromatography, HPLC)测定芍药苷的含量。结果 最佳工艺为8倍量水煎煮3次, 每次1 h, 滤液8000 r/min, 离心20 min, 上清液加入饴糖、苯甲酸钠; 黄芪、白芍、炙甘草薄层定性鉴别。该方法斑点清晰、阴性无干扰、专属性好, 含量测定方法学验证良好, 测得芍药苷含量在190 mg/100 mL以上。结论 优化的提取工艺稳定可行, 建立的质量标准能够控制桂芍舒逸口服液质量, 保证其产品品质。     

化学驱油中浊度法测定HPAM浓度的准确性

大庆油田聚合物驱和三元复合驱中普遍采用冰醋酸－次氯酸钠浊度法测定ＨＰＡＭ浓度,由于应用条件复杂多变,测定结果的准确性不好。实验考察了ＨＰＡＭ的水解度,分子量,水质碱、表面活性剂ＯＲＳ－４１及ＨＰＡＭ生产厂家对测定结果的影响 发现除ＯＲＳ－４１外,其余因素的影响都很大,这使实际生产中很难制作出合乎该法要求的标准工作曲线。     

维生素标准物质的研究进展

维生素是维持生命体健康活动必不可少的重要有机化合物,其最主要的功能是参与机体代谢调节,缺乏或过量均会引起相应的疾病,导致身体健康受损。准确测定维生素含量对监控营养食品质量、维护大众健康具有重要意义,维生素标准物质是保证维生素定量检测结果准确、可比和可溯源的重要物质基础。本文综述了国内外维生素标准物质的种类及技术水平现状,我国在维生素纯度标准物质方面的研究已经比较完善但在复杂基体方面的研究与发达国家仍存在一些差距,另外本文对维生素标准物质定值技术发展和需求进行了介绍。