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An online electricity cost budgeting algorithm for maximizing green energy usage across data centers

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Frontiers of Computer Science 2017年第4期11卷 661-674页

作者： Hui DOU Yong qi School of Electronic and Information Engineering Xi'an Jiaotong University Xi'an 710049 China

With the sky-rocketing development of Internet services, the power usage in data centers has been signifi- cantly increasing. This ever increasing energy consumption leads to negative environmental impact such as global warming. To reduce their carbon footprints, large Internet service operators begin to utilize green energy. Since green energy is currently more expensive than the traditional brown one, it is important for the operators to maximize the green en- ergy usage subject to their desired long-term （e.g., a month） cost budget constraint. In this paper, we propose an online algorithm GreenBudget based on the Lyapunov optimization framework. We prove that our algorithm is able to achieve a delicate tradeoff between the green energy usage and the en- forcement of the cost budget constraint, and a control parameter V is the knob to arbitrarily tune such a tradeoff. We evaluate GreenBudget utilizing real-life traces of user requests, cooling efficiency, electricity price and green energy avail- ability. Experimental results demonstrate that under the same cost budget constraint, GreenBudget can increase the green energy usage by 11.55% compared with the state-of-the-art work, without incurring any performance violation of user requests.

关键词： electricity cost budgeting green energy coolingefficiency data center Lyapunov optimization

Bifurcation analysis and stability design for aircraft longitudinal motion with high angle of attack

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Chinese Journal of Aeronautics 2015年第1期28卷 250-259页

作者： Xin qi Shi Zhongke School of Automation Northwestern Polytechnical University

Bifurcation analysis and stability design for aircraft longitudinal motion are investigated when the nonlinearity in flight dynamics takes place severely at high angle of attack regime. To predict the special nonlinear flight phenomena, bifurcation theory and continuation method are employed to systematically analyze the nonlinear motions. With the refinement of the flight dynamics for F-8 Crusader longitudinal motion, a framework is derived to identify the stationary bifurcation and dynamic bifurcation for high-dimensional system. Case study shows that the F-8longitudinal motion undergoes saddle node bifurcation, Hopf bifurcation, Zero-Hopf bifurcation and branch point bifurcation under certain conditions. Moreover, the Hopf bifurcation renders series of multiple frequency pitch oscillation phenomena, which deteriorate the flight control stability severely. To relieve the adverse effects of these phenomena, a stabilization control based on gain scheduling and polynomial fitting for F-8 longitudinal motion is presented to enlarge the flight envelope. Simulation results validate the effectiveness of the proposed scheme.

关键词： bifurcation longitudinal aircraft saddle continuation stabilization scheduling unstable stationary exponent

Design of evacuation strategies with crowd density feedback

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Science China(Information Sciences) 2016年第1期59卷 47-57页

作者： Luyuan qi Xiaoming HU Department of mathematics Royal Institute of Technology

A second-order stochastic model describing a large scale crowd is formulated, and an efficient evacuation strategy for agents in complex surroundings is proposed and solved numerically. The method consists in reshaping the crowd contour by making use of the crowd density feedback that is commonly available from geolocation technologies, and Kantorovich distance is used to transport the current shape into the desired one. The availability of the crowd density enables to solve the otherwise challenging forward-backward problem. Using this approach, we demonstrate via numerical results that the crowd migrates through the complex environment as designed.

关键词： crowd dynamics multi-agent system stochastic differential equation optimal control congestion control

The “twinkling star” materials: highly superior molecular switches for bioimaging

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Science China Chemistry 2019年第6期62卷 657-658页

作者： qi Zou Shanghai Key Laboratory of Materials Protection and Advanced Materials in Electric Power Shanghai University of Electric Power

Artificial molecular switches have been the robust tools for diverse fields of modern science and technology, including molecular machines, smart materials, and bioimaging [1]. The development of new concepts to enable the creation of efficient molecular switches has been a longstanding activity in these fields. Up to date, various kinds of molecular switches have been developed, most of which work between two or more stable states, and the rest of them requires at least an additional energy or chemical stimuli.

关键词： molecular development states

A group priority earliest deadline first scheduling algorithm

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Frontiers of Computer Science 2012年第5期6卷 560-567页

作者： qi LI Wei BA School of Control Science and Engineering Dalian University of TechnologyDalian 116024China Science and Technology on Underwater Test and Control Laboratory Dalian 116013China

In most priority scheduling algorithms, the num- ber of priority levels is assumed to be unlimited. However, if a task set requires more priority levels than the system can support, several jobs must in practice be assigned the same priority level. To solve this problem, a novel group priority earliest deadline first （GPEDF） scheduling algorithm is pre- sented. In this algorithm, a schedulability test is given to form a job group, in which the jobs can arbitrarily change their or- der without reducing the schedulability. We consider jobs in the group having the same priority level and use shortest job first （SJF） to schedule the jobs in the group to improve the performance of the system. Compared with earliest deadline first （EDF）, best effort （BE）, and group-EDF （gEDF）, simu- lation results show that the new algorithm exhibits the least switching, the shortest average response time, and the fewest required priority levels. It also has a higher success ratio than both EDF and gEDF.

关键词： real-time system group priority success ratio,switching

Formation of membrane pores by gasdermin-N causes pyroptosis

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Science China(Life Sciences) 2016年第10期59卷 1071-1073页

作者： Xiaopeng qi Key Laboratory of Animal Models and Human Disease Mechanisms Kunming Institute of Zoology Chinese Academy of Sciences

Pyroptosis, a lytic, highly inflammatory form of pro- grammed cell death, plays an important role in the defense against microbial infections and danger signals. However, excessive pyroptosis can be detrimental to host defense. Pyroptosis is uniquely dependent on inflammatory caspases such as caspase-1, murine caspase-ll, and its human hom- ologs caspases-4 and -5. Caspase-1 is a central component of canonical NLRP3, NLRC4, AIM2,

关键词：细胞程序性死亡 caspase 膜孔宿主防御微生物感染半胱天冬酶组成部分炎症

Obstacle-avoiding path planning for multiple autonomousunderwater vehicles with simultaneous arrival

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Science China(Technological Sciences) 2019年第1期62卷 121-132页

作者： YAO Peng qi ShengBo College of Engineering Ocean University of China

This paper focuses on planning the obstacle-avoiding paths of multiple autonomous underwater vehicles(AUVs) in complex ocean environment, with the time coordination of simultaneous arrival. By imitating the nature phenomenon that river water avoids rocks and reaches the destination, the interfered fluid dynamical system(IFDS) is first presented to obtain the single-AUV path for obstacle avoidance, where the modulation matrix is calculated to quantify the influence of obstacles especially. Then the two-layer comprehensive adjustment to path length and voyage speed is utilized, aiming to achieve the simultaneous arrival at destination between multi-AUVs. By adjusting reactive parameters of IFDS, the former is to roughly ensure the intersection of AUVs' potential arrival time range to be non-null. On this basis, the latter adjusts each AUV's voyage speed finely using the consensus method with state predictor, which has faster convergence speed. If the multi-AUVs communication network is connected, the whole system will quickly converge to the consensus state, i.e., the estimated time of arrival(ETA) of each AUV tends to be equal. Finally, the simulation results verify the advantages of our proposed method.

关键词： autonomous underwater vehicles (AUVs) obstacle-avoiding paths simultaneous arrival interfered fluid dynamical system (IFDS) consensus method with state predictor

A redox shuttle imparts operational durability to perovskite solar cells

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Science Bulletin 2019年第4期64卷 224-226页

作者： Yabing qi Energy Materials and Surface Sciences Unit (EMSSU) Okinawa Institute of Science and Technology Graduate University (OIST)

The family of perovskite materials are described by the formula ABX3, where A are monovalent cations, B are divalent cations, and X are anions.

关键词： cells family anions

Shear-induced Precursors of Fibrillar Crystals of Poly(butene-1):A Rheological Study

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Chinese Journal of Polymer Science 2022年第6期40卷 618-623页

作者： Jia-qi Zhang Quan Chen State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China University of Science and Technology of China Hefei 230026China

Strong preshear flow stretches poly(butene-1)chains to form flow-induced precursors of fibrillar *** formation leads to further growth of shear/normal stress after the stress reaches the steady *** this study,stress relaxation measurements are performed after intervals of a strong flow during which the precursors *** small-angle X-ray scattering(SAXS)and wide-angle X-ray diffraction(WAXD)measurements are conducted to characterize the crystalline structure formed after the preshear and relaxation processes,each of different periods.A combination of the stress relaxation and scattering results reveal that for the precursors formed within 5 s,the stress can fully relax and the orientation of the subsequent crystals(formed upon quenching the sample at different stress levels)decays gradually with the *** comparison,for those precursors formed after 5 s,the stress hardly relaxes during~10^(4) s,and the orientation of the subsequent crystals hardly decays,suggesting that the precursors have been somehow stabilized during the *** features have been discussed with respect to the percolation of the precursors to form a reversible network.

关键词： PB-1 Rheology Precursor Fibrillar crystal