摘要：With more large-scale scientific computing tasks being delivered to cloud computing platforms, cloud workflow systems are designed for managing and arranging these complicated tasks. However, multi-tenant coexistence service mode of cloud computing brings serious security risks, which will threaten the normal execution of cloud workflows. To strengthen the security of cloud workflows, a mimic cloud computing task execution system for scientific workflows is proposed. The idea of mimic defense contains mainly three aspects: heterogeneity, redundancy, and dynamics. For heterogeneity, the diversities of physical servers, hypervisors, and operating systems are integrated to build a robust system framework. For redundancy, each sub-task of the workflow will be executed simultaneously by multiple executors. Considering efficiency and security, a delayed decision mechanism is proposed to check the results of task execution. For dynamics, a dynamic task scheduling mechanism is devised for switching workflow execution environment and shortening the life cycle of executors, which can confuse the adversaries and purify task executors. Experimental results show that the proposed system can effectively strengthen the security of cloud workflow execution.

摘要：为明确库区浸没影响因素及其在浸没发生过程中的重要性,在系统分析库区浸没成因的基础上,提出了库区浸没影响因素的评价指标体系和方法,以燕山水库为例,对库区浸没影响因素进行评价,确定了该水库库区浸没的主要影响因素,评价结果符合工程实际,指标体系合理可行,评价方法正确有效。

摘要：近几十年里,全球经历了多次重大病毒暴发,包括西非的埃博拉疫情、南美的寨卡病毒流行以及近期的全球COVID-19大流行。在这些疫情应对过程中,有效的疫苗为保护人民健康作出了重大贡献,但面对新发突发传染病防控不断出现的新问题,全球传统疫苗研发模式正面临前所未有的机遇与挑战,暴露了传统疫苗开发的时间长、成本高等局限性。本文探讨了现代疫苗临床试验中的创新设计,深入探讨针对疫苗特有的随机化方法,同时梳理了疫苗试验设计中的关键统计学考量,以期为疫苗开发提供科学支持,推动疫苗研发领域的持续创新与实践优化。

摘要：A conceptual design of using novel telescopic piles to position a multi-modular very large floating structure(VLFS),which is supposed to be severed as a movable floating airport,is *** telescopic piles can automatically plug in the soil to resist the environmental loads and pull out from the soil to evacuate or move on to the next operational *** feasibility demonstration of the conceptual design includes two parts:function verification and structure *** the latter part of the conceptual design,a time-domain structural analysis is firstly conducted by using Abaqus *** simulation results suggest that the preliminary structure scheme is not optimum due to the insufficient structure utilization,although both structure safety of the piles and positioning accuracy are *** realize a cost reduction of construction and installation,a Genetic Algorithm-Finite Element Analysis(GA-FEA)method is employed to perform structural *** optimization,31 percent of the weight of each pile is reduced and higher structure utilization is *** difference of the self-weight and allowable buoyancy of a single module(SMOD)of a semisubmersible-type VLFS is much larger than the weight of the *** with the function verification in our previous work,the conceptual design of using the novel telescopic pile to position VLFS is demonstrated to be feasible.

摘要：Activating basal plane inert sites will endow MoTe_(2) with prominent hydrogen evolution reaction(HER)catalytic capability and arouse a new family of HER ***,we fabricated single MoTe_(2) sheet electrocatalytic microdevice for in situ revealing the activated basal plane sites by vacancies *** the extraction of electrical parameters of single MoTe_(2) sheet,the in-plane and interlayer conductivities were optimized effectively by Te vacancies due to the defect *** deeply,Te vacancies can induce the delocalization of electrons around Mo atoms and shift the d-band center,as a consequence,facilitate the adsorption of H from the catalyst surface for HER *** by the coordinated regulation of band structure and local charge density,the overpotential at−10 mA·cm^(−2)was reduced to 0.32 V after Te vacancies compared to 0.41 V for the basal plane sites of same MoTe_(2) ***,the insights gained from single nanosheet electrocatalytic microdevice can be applied to the improved HER of the commercial MoTe_(2) *** the in situ testing of the atomic structure-electrical behavior-electrochemical properties of a single nanosheet before/after vacancies introducing provides reliable insight to structure-activity relationships.

摘要：随着天然气管网互联互通成环成网,需要利用仿真技术模拟各种工况下的管网运行状态,以提升管网的供气能力,进而降低管网运行成本。现有的智能化仿真方法过于依赖数据驱动,忽略了天然气流动机理,导致精度与稳定性较差且结果不可解释。为此,从机理角度分析了天然气流动基本控制方程与管网拓扑结构,将机理信息耦合至深度学习的损失函数指导结构设计与训练,形成了天然气管网物理信息神经网络PINN(Physics-Informed Neural Network)仿真模型;然后描述了输入输出变量之间的耦合关系,设计边界条件嵌入训练硬约束模式,建立了硬约束和物理信息神经网络结合BHC-PINN(Boundary Hard-Constraint Physics-Informed NeuralNetwork)的模型,实现了天然气管网全时空状态的仿真监测。研究结果表明:(1) PINN模型将管道与拓扑结构的机理信息耦合进损失函数以提高模型的可解释性,并借助管网进出口冗余数据提高了准确性,实现了对管网压力流量的准确监测;(2)建立的边界硬约束模式,使神经网络的输出强制满足边界条件,得到的流量和压力仿真误差分别从2.1%和0.32%下降低至1.5%和0.082%,训练的效率和速度分别提高了48.5%和55.9%;(3) BHC-PINN能实现管网任意位置气体流动状态的观测,对于中间阀室压力的仿真最大误差为0.2%。结论认为,该新方法能准确仿真天然气管网内流动状态,增强了数据驱动模型的可解释性,并为天然气管网瞬态仿真提供了数据加机理混合驱动的新思路。

摘要：从敏感性和适应性角度选取了10项指标因子,设计了农户旱灾脆弱性调查问卷,并在陕西省岐山县雍川镇开展了实地调查,通过问卷调查结果分析评价了区域的农户旱灾脆弱性。结果表明:旱灾对农户的影响属于低脆弱性;农户耕地灌溉状况、农户农业收入比重、作物耐旱性等因素对农户旱灾脆弱性影响强烈。

摘要：陆域磷输入(磷输入)通量研究对于面源污染控制至关重要.利用SWAT模型模拟洞庭湖区磷输入通量,并针对农业控制、畜禽减排与水土保持措施的3种典型削减情景,利用混合模型(LSTM模型和SWAT模型)进行水系区间磷输入通量削减预测.结果表明,洞庭湖区的TP入河总量为3.9×10^(4)t·a^(-1),TP负荷为14.4 kg·(hm^(2)·a)^(-1).磷通量季节变化显著,汛期高,非汛期低,与径流挟带、土壤侵蚀和耕作密度有显著相关性.三口区间是磷输入通量最大的区域,每年平均值为1.87×10^(4)t,需重点关注其磷污染风险.水系面积和农业用地面积是该区域磷输入通量主要的决定因素.多特征输入的LSTM模型在子流域尺度上对磷输入通量模拟效果良好,NSE>0.6.混合模型在水系区间尺度上表现出更好的结果,NSE>0.8,RPE<10%,且对数据特征要求降低.在削减预测中,以三口区间为例,入河泥沙量削减是相对有效的磷减排方式,泥沙作为磷的主要载体是面源污染控制的主要目标,同时还应关注畜禽养殖的污染.研究可为了解洞庭湖区磷输入通量的时空格局并制定磷减排策略提供科学依据和数据支撑.

摘要：简要介绍了300W Ku波段栅控脉冲空间行波管的计算机模拟,形成了可行的设计方案。着重解决栅控脉冲空间行波管的关键技术问题:高效率和高可靠性。

摘要：The initial motivation of the lifting technique is to solve the H∞control problems. However, the conventional weighted H∞design does not meet the conditions required by lifting, so the result often leads to a misjudgement of the design. Two conditions required by using the lifting technique are presented based on the basic formulae of the lifting. It is pointed out that only the H∞disturbance attenuation problem with no weighting functions can meet these conditions, hence, the application of the lifting technique is quite limited.