Natural surface design for sliding mode control with multiple discontinuous inputs     

Pedro Acosta 《Journal of The Franklin Institute》2014

It is well known that sliding mode control is based on the definition of an invariant manifold, where the system dynamics are forced to in a finite time. Such a manifold is somewhat arbitrarily defined, as long as the system dynamics are stable on it. Computational and control effort may vary depending on selected manifold. Obviously, if a system has naturally acceptable stable dynamics around a desired equilibrium point, no control is needed unless uncertainties or disturbances are present. It would be desirable that if such a system had uncertainties or disturbances, the control effort be designed only to overcome the effect of such factors. For a system with first order dynamics and affine control input, designing a sliding mode control overcoming only such uncertainties or disturbances is a trivial task. When a higher order dynamics system is involved, unit control may be used, where the input control signals are not discontinuous, but when only discontinuous control inputs are available, a design approach is not readily available. In this paper, taking advantage of the natural stable dynamics of a system, a sliding mode control approach is introduced for designing multiple discontinuous control inputs, where the control effort overcomes only uncertainties, disturbances or unstable dynamics. Two illustrative examples are given in order to show the feasibility of the method.  相似文献   

四川省地震灾区婴幼儿营养监测状况分析     

李晓杰 《科学中国人》2014,(8):92-95

作者通过对四川省青川县和彭州市两个地震灾区6-24个月龄婴幼儿健康状况的统计分析,发现该地区生长发育状况不佳,存在营养不良现象,其中贫血率较高。经过对比进行营养包6个月干预后的人群统计分析,发现营养状况稍得到改善,其中彭州市目标人群贫血改善明显,由此提出面对四川其它或其它类似贫困地震地区,由于贫困,天灾必然加剧受灾人群的营养状况,特别是贫血率状况,针对这些地区的求援,必须紧迫加强营养包的干预,而且需要持续性的干预,比较可靠的预算应该在灾难期6个月以上方有一定的作用,同时必要的管理措施有利于保证营养干预对象的稳定性,提高营养干预的有效性的。  相似文献   

异址灾备播出系统应用实践     

罗小武 《大众科技》2014,(5):13-14,17

为了贯彻落实国家广电总局第62号令,广西电视台从实际情况出发,搭建了异址灾备播出系统。在灾难性故障发生时,灾备系统可以保障电视节目同步、连续和高质量的播出。文章简要介绍广西电视台异址灾备播出系统的设计思路、硬件架构、业务流程、技术特点和灾备系统运行时能够达到的应用效果。  相似文献   

浅谈天然药物化学设计性实验教学方案的构建与实施     

廖彭莹 《大众科技》2014,(2):108-109,118

实验课对天然药物化学教学有着关键性影响,在其中引入设计性实验教学是对现有实验课程的一次探索性改革。设计性实验教学方案的构建和实施需要从课题选择、方案设计、实验准备、实验实施及结果分析等多个环节入手,在教学实践中这种教学方式取得了良好的效果。  相似文献   

Reviewer assignment algorithms for peer review automation: A survey     

《Information processing & management》2022,59(5):103028

Assigning paper to suitable reviewers is of great significance to ensure the accuracy and fairness of peer review results. In the past three decades, many researchers have made a wealth of achievements on the reviewer assignment problem (RAP). In this survey, we provide a comprehensive review of the primary research achievements on reviewer assignment algorithm from 1992 to 2022. Specially, this survey first discusses the background and necessity of automatic reviewer assignment, and then systematically summarize the existing research work from three aspects, i.e., construction of candidate reviewer database, computation of matching degree between reviewers and papers, and reviewer assignment optimization algorithm, with objective comments on the advantages and disadvantages of the current algorithms. Afterwards, the evaluation metrics and datasets of reviewer assignment algorithm are summarized. To conclude, we prospect the potential research directions of RAP. Since there are few comprehensive survey papers on reviewer assignment algorithm in the past ten years, this survey can serve as a valuable reference for the related researchers and peer review organizers.  相似文献   

A Dual-Pointer guided transition system for end-to-end structured sentiment analysis with global graph reasoning     

《Information processing & management》2022,59(4):102992

Structured sentiment analysis is a newly proposed task, which aims to summarize the overall sentiment and opinion status on given texts, i.e., the opinion expression, the sentiment polarity of the opinion, the holder of the opinion, and the target the opinion towards. In this work, we investigate a transition-based model for end-to-end structured sentiment analysis task. We design a transition architecture which supports the recognition of all the possible opinion quadruples in one shot. Based on the transition backbone, we then propose a Dual-Pointer module for more accurate term boundary detection. Besides, we further introduce a global graph reasoning mechanism, which helps to learn the global-level interactions between the overlapped quadruples. The high-order features are navigated into the transition system to enhance the final predictions. Extensive experimental results on five benchmarks demonstrate both the prominent efficacy and efficiency of our system. Our model outperforms all baselines in terms of all metrics, especially achieving a 10.5% point gain over the current best-performing system only detecting the holder-target-opinion triplets. Further analyses reveal that our framework is also effective in solving the overlapping structure and long-range dependency issues.  相似文献   

“双一流”建设下我国药学学科的科研竞争力水平——来自48家高校院所的实证     

路亮  陈永法 《科技管理研究》2022,(20)

为丰富从获取科研基金角度分析我国高校院所药学科研竞争力的研究,基于2005－2019年间国家自然科学基金（NSFC）在药物学、药理学领域有关资助数据,从获取科研经费、基金项目负责人数量等维度构建改进的药学学科科研竞争力指数（PSCI）,以国内设有药学一级学科博士学位授权点的48家高校院所为实证对象,分析其药学学科科研资助情况、科研竞争力及变化趋势。结果显示：NSFC在药物学、药理学领域资助以面上项目和青年科学基金项目为主,资助项目数量和经费均呈现出先快速增长后平稳发展的态势,表明我国药物学与药理学领域基础研究水平已达一定高度;药学科研竞争力强的单位主要集中在东部沿海和北部沿海综合经济区;高校院所药学科研竞争力位次呈固化趋势,科研资源聚集现象显著。  相似文献   

视觉设计思维助力高校灾难教育传播的理路探析     

丁雅晴 《科教文汇》2022,(2)

视觉设计是人们交流观念、传递思想的重要媒介,在现代社会通过丰富多样的载体发挥其效能。随着信息数字技术的发展,高校灾难教育面临新的形势与挑战。我们要借助视觉设计思维的传播特性,丰富高校灾难教育的内容与形式,运用视觉设计思维实现高校灾难教育传播的理路:(1)立足优势学科资源,重新审视灾难教育终极目标;(2)整合和优化高校灾难教育资源形式,推动灾难教育手段创新;(3)强化多方主体合作,形成学校、家庭、社区“三位一体”信息传播网。  相似文献   

泰安市地质灾害预警预报系统研究     

夏学生 《环球赛鸽科技》2014,(36)

该文主要介绍了泰安市地质灾害气象风险预警与指挥系统。系统开发的主要目的是为了更好的与泰安市地质灾害防治工作相结合,通过对气象因素及地质灾害资料的分析和研究,基于地质灾害气象预警模型,采用先进的GIS技术能实现对地质灾害易发风险性区域预警,能直观地了解到各部分区域的地质灾害易发风险性,为各级政府防灾减灾提供科学的技术支撑。  相似文献   

Unveiling the colour palette of Arraiolos carpets: Material study of carpets from the 17th to 19th century period by HPLC-DAD-MS and ICP-MS     

《Journal of Cultural Heritage》2014,15(3):292-299

Wool samples collected from thirteen Arraiolos carpets from the 17th–19th century belonging to the National Museum of Ancient Art (NMAA, Lisboa, Portugal) collection were analysed to identify the natural dyes and mordants employed in the traditional dyeing process, in a way to complement and improve actual knowledge on this rugs. Natural dyes were extracted from Arraiolos historical wool fibres using a mild extraction method, followed by high-performance liquid chromatography with diode array and mass spectrometry detection (HPLC-DAD-MS) for compound identification. Colourimetry was used to measure colour parameters in all historical samples. Quantification of mordants in the historical fibres was carried out by inductively coupled plasma-mass spectrometry (ICP-MS). Weld, indigo, spurge flax, brazilwood, madder and cochineal were identified as dye sources in the fibres. Alum was the most commonly used mordant, but the presence of iron and zinc was also detected in some darker samples. The use of madder and cochineal is not referred in the available historical dyeing recipes. This study also proved that the actual visual perception of these carpets is strongly affected by the natural dyes photodegradation, which was mostly unaccounted for before.  相似文献