Simulation is essential for embedded control systems with task jitter

Sampling or task jitter affects the performance of digital control systems but realistic simulation of this effect has not been possible to date. Our previous work has developed a novel method to simulate sampling jitter in MATLAB/Simulink simulation software where the jitter is generated randomly. What has been missing is a way to capture sampling jitter from a target platform and then feed this timing information into the simulation. This paper presents a low-cost and novel solution to these problems. The method uses an Arduino board to capture task jitter from two different hardware platforms with multiple stressing conditions. Then the recorded performance data is used to drive realistic simulations of a control system. Measurement shows that the task jitter data does not follow any specific random distribution such as Gaussian or Uniform. Furthermore, very occasional timing patterns, which may not be picked up while testing a real system, can result in extreme controller responses. This novel method allows comparisons of different platforms and reduces the effort required to choose the most appropriate platform for full implementation.

     

Hash算法在数据库安全中的应用

介绍了Hash算法在数据库加密系统中的应用,包括在用户身份验证中的应用,在数据库完整性认证中的应用,以及在密文检索中的应用。     

基于SEBAL模型的浙江省区域蒸散发量估算研究

地表蒸散发(ET)是地气相互作用中水分平衡的重要部分.利用新一代对地观测数据MODIS,基于地表能量平衡的SEBAL模型,对浙江省2006年8月2日和11月4日的蒸散发进行了反演.结果表明,蒸散发具有明显的时空差异性,由于温度更高,夏季的日蒸散发量明显高于冬季,可达到10 mm/d以上.另外,在地表水含量丰富、风速较大处以及水体周围蒸散发量相对较高.     

Hammerstein-Wiener nonlinear model based predictive control for relative QoS performance and resource management of software systems

Runtime management of Quality of Service (QoS) performance and resource provisioning is a vital issue in shared resource software environments. A useful performance management technique for such software systems is the relative guarantee feedback control scheme. The existing approaches for this class of control systems are mainly based on off-line linear or on-line model identification and control techniques, which tend to have performance issues in the presence of nonlinearities induced by this scheme. Instead of using such modeling techniques, this paper proposes a new approach for QoS performance management and resource provisioning by using an off-line identification of Hammerstein and Wiener nonlinear block structural model. Using the characteristic structure of the nonlinear model, a predictive feedback controller based on a gain schedule technique is incorporated in the design to achieve the performance objectives. The proposed approach is validated using experiments based on a prototype, demonstrating superior runtime QoS performance management and resource provisioning in a complex software system.     

2015-2019年云南省家庭食源性疾病暴发事件分析

目的 分析2015-2019年云南省家庭食源性疾病暴发事件的流行病学特点,为制定家庭食源性疾病防控措施提供参考.方法 对2015-2019年云南省食源性疾病暴发监测系统中报告的家庭食源性疾病暴发事件数据进行统计分析.结果 2015-2019年云南省共报告家庭食源性疾病3 159起,发病12 402人,死亡229人,病死...     

TaNBR1, a Novel Wheat NBR1-like Domain Gene Negatively Regulates Drought Stress Tolerance in Transgenic Arabidopsis

Drought stress is an important factor that severely affects crop yield and quality. Autophagy has a crucial role in the responses to abiotic stresses. In this study, we explore TaNBR1 in response to drought stress. Expression of the TaNBR1 gene was strongly induced by NaCl, PEG, and abscisic acid treatments. The TaNBR1 protein is localized in the Golgi apparatus and autophagosome. Transgenic Arabidopsis plants overexpressing TaNBR1 exhibited reduced drought tolerance. When subjected to drought stress, compared to the wild-type (WT) lines, the transgenic overexpressing TaNBR1 plants had a lower seed germination rate, relative water content, proline content, and reduced accumulation of antioxidant enzymes, i.e., superoxide dismutase, peroxidase, and catalase, as well as higher chlorophyll losses, malondialdehyde contents, and water loss. The transgenic plants overexpressing TaNBR1 produced much shorter roots in response to mannitol stress, in comparison to the WT plants, and they exhibited greater sensitivity to abscisic acid treatment. The expression levels of the genes related to stress in the transgenic plants were affected in response to drought stress. Our results indicate that TaNBR1 negatively regulates drought stress responses by affecting the expression of stress-related genes in Arabidopsis.     

保温时间对废催化裂化平衡剂合成莫来石的影响

采用X射线粉末衍射和扫描电子显微镜研究了保温时间对废催化裂化平衡剂合成莫来石的影响。结果表明，二次莫来石化反应发生在1 450 ℃，保温3 h后，莫来石质量分数达94%，晶体发育良好；当保温时间超过4 h，由于反应物中Si4+被Al3+取代，导致空位增多，过渡金属进入结构的空位，使莫来石熔点降低，表现为保温时间越长，液相越多，莫来石晶体粘结于液相之中，使机械性能降低。由此可见，保温时间对二次莫来石生成反应影响较大。     

翅果油超临界CO2流体萃取工艺优化及其不同提取方法的比较

对翅果油的超临界CO_2流体萃取工艺条件进行研究。在单因素试验的基础上,以萃取压力、萃取温度、萃取时间和原料粒度为影响因素,以翅果油得率为指标,采用正交试验优化工艺条件。比较了浸出法、超临界CO_2流体萃取法、冷榨法和热榨法4种不同提取方法对翅果油得率和微量活性成分的影响。结果表明:超临界CO_2流体萃取翅果油最优工艺条件为萃取压力30 MPa、萃取温度50℃、萃取时间150 min、原料粒度80目,此条件下翅果油得率为(28. 32±1. 15)%; 4种提取方法中,浸出法的翅果油得率、VE及甾醇含量最高,其次是超临界CO_2流体萃取法,除热榨法的翅果油角鲨烯含量最高外,压榨法的其他指标均最低。     

西峰油田延长组长8段储层流体作用期次分析

采用显微荧光技术以及包裹体显微测温技术,结合鄂尔多斯盆地西峰油田埋藏史及地热史演化过程模拟,确定了该区油气运移主要分两期,第一期发生于中、晚侏罗世,第二期发生于早白垩世末期,该期是鄂尔多斯盆地西峰地区中生代油气运聚的重要时刻。油气运聚的第一期和第二期分别对应于早成岩B期和晚成岩A期成岩阶段。由于该区盐水包裹体以石英裂缝中形成的为主,包裹体的保存条件相对较差,使得均一温度具有一定的多解性,因此制定了裂缝中流体包裹体测温数据应用的筛选原则,为类似情况流体包裹体的应用提供了参考。     

Enhancing Physicochemical Properties and Indium Leachability of Indium-Bearing Zinc Ferrite Mechanically Activated Using Tumbling Mill

The synthetic indium-bearing zinc ferrite (IBZF) was activated mechanically using a tumbling mill under different rotation speeds, milling times, media fillings, and ball-to-material ratios. Subsequently, the changes in the physicochemical properties and leaching behavior of IBZF induced by mechanical activation were studied by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectra (FT-IR), M?ssbauer spectrometry, particle size analysis, and leaching tests in sulfuric acid. The results showed that different milling conditions could form different particle size distribution, morphologies, and crystal structures, which influenced indium extraction differently. In addition, the indium extractions from various activated samples were related closely to the changes of physicochemical properties induced by mechanical activation. The strengthening effect of mechanical activation in IBZF decomposition lies mainly in the damage of crystal structure besides the decrease of the particle size because the indium-leaching efficiencies increased significantly with the increase of the damage of the crystal structure when the particle size is kept constant.