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SMT-based query tracking for differentially private data analytics systems

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Frontiers of Computer Science 2018年第6期12卷 1192-1207页

作者： Chen LUO fei he Tsinghua National Laboratory for Information Science and Technology (TNList) School of SoftwareTsinghua UniversityBeijing 100084China Key Laboratory for Information System Security Ministry of EducationTsinghua UniversityBeijing 100084China

Differential privacy enables sensitive data to be analyzed in a privacy-preserving manner. In this paper, we focus on the online setting where each analyst is assigned a privacy budget and queries the data interactively. However, existing differentially private data analytics systems such as PINQ process each query independently, which may cause an unnecessary waste of the privacy budget. Motivated by this, we present a satisfiability modulo theories (SMT)-based query tracking approach to reduce the privacy budget usage. In brief, our approach automatically locates past queries that access disjoint parts of the dataset with respect to the current query to save the privacy cost using the SMT solving techniques. To improve efficiency, we further propose an optimization based on explicitly specified column ranges to facilitate the search process. We have implemented a prototype of our approach with Z3, and conducted several sets of experiments. The results show our approach can save a considerable amount of the privacy budget and each query can be tracked efficiently within milliseconds.

关键词： differential privacy privacy budget satisfiability modulo theory

Methods for Integrating Energy Consumption and Environmental Impact Considerations into the Production Operation of Machining Processes

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Chinese Journal of Mechanical Engineering 2010年第4期23卷 428-435页

作者： he Yan LIU fei State Key Laboratory of Mechanical Transmission Chongqing University Chongqing 400030 China

Energy consumption and environmental impact considerations of machining processes are viewed as important issues for the global trends towards sustainable manufacturing. The existing research of reducing energy consumption and environmental impacts of machining processes greatly focuses on design and planning activities, but is reasonably sparse for production operation activities. This paper explores a systematic methodology that incorporates energy consumption and environmental impact considerations into the production operation of machining processes. Firstly, the framework of the methodology is proposed to establish the generic procedures for integrating the above considerations in production operation activities. As the two key issues of the framework, the profile index value matrix is determined by valuing the individual quantity of energy consumption and environmental impacts of machining each job on each machine, and the multi-criteria models are constructed by the operational methods. Furthermore, with the guideline of the framework, the specific formulations are modeled by two sub-models for the parallel machine scheduling problem, in which makespan and energy consumption are the optimizing objectives as well as the constraints of environmental impact considerations. The specific formulations provide a practical method to integrate energy consumption and environmental impact considerations into the scheduling activity, and also can serve as a reference to other activities in the production operation. The case study for a batch of jobs, including seven kinds of gears in the machining shop floor, is presented to demonstrate the application of the specific formulations of the methodology. The proposed methodology provides potential opportunities for reducing energy consumption and environmental impacts in machining processes, and helps production managers in decision-making on the issues of energy consumption and environmental impacts in the production operat

关键词： green manufacturing energy environmental impact production operation machining

Equatorial aurora: the aurora-like airglow in the negative magnetic anomaly

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National Science Review 2020年第10期7卷 1606-1615页

作者： fei he Yong Wei Weixing Wan Key Laboratory of Earth and Planetary Physics Institute of Geology and Geophysics Chinese Academy of Sciences College of Earth and Planetary Sciences University of Chinese Academy of Sciences

The most fantastic optical phenomena in the Earth’s upper atmosphere are the auroras. They are highly informative indicators of solar activity, geomagnetic activity, upper atmospheric structures and dynamics,and magnetospheric energetic particles. An area where the geomagnetic field differs significantly from the expected symmetric dipole, such as at the South Atlantic Anomaly, where the magnetic field intensity is low,gives rise to stronger precipitation of energetic particles into the upper atmosphere. Impact excitation and the subsequent airglow emissions exhibit aurora-like dynamic signatures. Nomenclatures of nonpolar aurora or equatorial auroras are similar to those used with the polar auroras owing to their similar excitation mechanisms. This paper provides an overview of the knowledge and the challenges concerning auroral activity at the South Atlantic Anomaly, or more generally, at the negative magnetic anomaly. We emphasize systematic investigation of the equatorial auroras to reveal the temporal and spatial evolution of the magnetic anomaly and the behaviour of energetic particles in near-Earth space.

关键词： aurora geomagnetic field South Atlantic Anomaly negative magnetic anomaly energetic particles

Efficient software product-line model checking using induction and a SAT solver

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Frontiers of Computer Science 2018年第2期12卷 264-279页

作者： fei he Yuan GAO Liangze YIN Tsinghua National Laboratory for Information Science and Technology (TNList) Tsinghua University Beijing 100084 China Key Laboratory for Information System Security Ministry of Education Beijing 100084 China School of Software Tsinghua University Beijing 100084 China Department of Computer Science and Technology National University of Defense Technology Changsha 410073 China

Software product line （SPL） engineering is increasingly being adopted in safety-critical systems. It is highly desirable to rigorously show that these systems are designed correctly. However, formal analysis for SPLs is more difficult than for single systems because an SPL may contain a large number of individual systems. In this paper, we propose an efficient model-checking technique for SPLs using induction and a SAT （Boolean satisfiability problem） solver. We show how an induction-based verification method can be adapted to the SPLs, with the help of a SAT solver. To combat the state space explosion problem, a novel technique that exploits the distinguishing characteristics of SPLs, called feature cube enlargement, is proposed to reduce the verification efforts. The incremental SAT mechanism is applied to further improve the efficiency. The correctness of our technique is proved. Experimental results show dramatic improvement of our technique over the existing binary decision diagram （BDD）-based techniques.

关键词： software product line model checking satisfiability

Tilt of the ring current during the main phases of intense geomagnetic storms

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Science China(Technological Sciences) 2019年第5期62卷 820-828页

作者： LIU BaoJia ZHANG XiaoXin he fei Institute of Space Weather School of Math & Statistics Nanjing University of Information Science & Technology State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesChina Meteorological Administration Key Laboratory of Space Weather National Center for Space Weather China Meteorological Administration Key Laboratory of Earth and Planetary Physics Institute of Geology and Geophysics Chinese Academy of Sciences Institutions of Earth Science Chinese Academy of Sciences College of Earth and Planetary Sciences University of Chinese Academy of Sciences

Based on the data from the SuperMAG collaboration in 2000–2014, the magnetic latitude(MLAT) location of the ring current(RC) denoted by the MLAT of the maximum horizontal magnetic disturbance during the main phase of 67 intense geomagnetic storms(Dst ≤-100 nT) are derived. The results show that the maximum horizontal magnetic disturbance does not always occur in the magnetic equator, indicating that the RC might be tilted in the latitudinal direction during these storms. Specifically, the tilt of the RC near the day-night line is affected by the direction of solar wind. When the solar wind flows southward against the magnetic equatorial plane, the RC is more likely to show a dayside-lifted tilt. When the solar wind flows northward, the pattern is opposite. Tilts of the RC near the dawn-dusk line are also found in most of these storms. The location of the RC is mainly lifted in the dusk side and declined in the dawn side for positive IMF BY, while the tilt is reversed for negative IMF BY. A possible interpretation might be the IMF BY-related twisting of the geomagnetic field. Besides, the monthly averaged MLAT of the fitted RC also varies with seasons. It is shifted to the southern hemisphere in the northern summer and to the northern hemisphere in the northern winter, which might indicate that the RC is not centered on a single plane. Such a seasonal variation might be related to the angle between the solar wind and the magnetic equatorial plane.

关键词： tilt of ring current geomagnetic storm solar wind interplanetary magnetic field

Conversion therapy for unresectable hepatocellular carcinoma:Advances and challenges

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World Journal of Gastrointestinal Oncology 2024年第10期16卷 4289-4297页

作者： Yan-fei he Department of health Management Center The Sixth Medical CenterChinese People’s Liberation Army General HospitalBeijing 100048China

Recently,the World Journal of Gastrointestinal Oncology published an article entitled“Pathologically successful conversion hepatectomy for advanced giant hepatocellular carcinoma after multidisciplinary therapy:A case report and review of the literature”,in which the authors shared their successful experience with complete surgical resection after multidisciplinary conversion *** study by Chu et al demonstrates the great challenges that the advanced hepatocellular carcinoma(HCC)poses to surgical oncology,reveals the complexity of conversion therapy for unresectable HCC,emphasizes the important role of a multidisciplinary management model in conversion therapy,and enriches our understanding of the dynamics of personalized treatment for different *** present,conversion therapy is a hot research topic in the treatment of unresectable HCC,which has brought new hope to many patients with moderately advanced ***,there are still many urgent problems to be solved in conversion ***,we would like to further discuss the advances and challenges of conversion therapy for unresectable HCC with the authors and the general readers.

关键词： Unresectable hepatocellular carcinoma Conversion therapy Challenges Advances Advanced hepatocellular carcinoma Targeted therapy Immunotherapy

A General Vectorial Ekeland's Variational Principle with a P-distance

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Acta Mathematica Sinica,English Series 2013年第9期29卷 1655-1678页

作者： Jing Hui QIU fei he School of Mathematical Sciences Soochow University School of Mathematical Sciences Soochow University School of Mathematical Sciences Inner Mongolia University

In this paper, by using p-distances on uniform spaces, we establish a general vectorial Ekeland variational principle （in short EVP）, where the objective function is defined on a uniform space and taking values in a pre-ordered real linear space and the perturbation involves a p-distance and a monotone function of the objective function. Since p-distances are very extensive, such a form of the perturbation in deed contains many different forms of perturbations appeared in the previous versions of EVP. Besides, we only require the objective function has a very weak property, as a substitute for lower semi-continuity, and only require the domain space （which is a uniform space） has a very weak type of completeness, i.e., completeness with respect to a certain p-distance. Such very weak type of completeness even includes local completeness when the uniform space is a locally convex topological vector space. From the general vectorial EVP, we deduce a general vectorial Caristi＇s fixed point theorem and a general vectorial Takahashi＇s nonconvex minimization theorem. Moreover, we show that the above three theorems are equivalent to each other. We see that the above general vectorial EVP includes many particular versions of EVP, which extend and complement the related known results.

关键词： Vectorial Ekeland’s variational principle vectorial Caristi’s fixed point theorem vectorial Takahashi’s minimization theorem p-distance Gerstewitz’s function

Sequentially Lower Complete Spaces and Ekeland's Variational Principle

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Acta Mathematica Sinica,English Series 2015年第8期31卷 1289-1302页

作者： fei he Jing-Hui QIU School of Mathematical Sciences Inner Mongolia University School of Mathematical Sciences Soochow University

By using sequentially lower complete spaces（see [Zhu, J., Wei, L., Zhu, C. C.： Caristi type coincidence point theorem in topological spaces. J. Applied Math., 2013, ID 902692（2013）]）, we give a new version of vectorial Ekeland＇s variational principle. In the new version, the objective function is defined on a sequentially lower complete space and taking values in a quasi-ordered locally convex space, and the perturbation consists of a weakly countably compact set and a non-negative function p which only needs to satisfy p（x, y） = 0 iff x = y. here, the function p need not satisfy the *** the new Ekeland＇s principle, we deduce a vectorial Caristi＇s fixed point theorem and a vectorial Takahashi＇s non-convex minimization theorem. Moreover, we show that the above three theorems are equivalent to each other. By considering some particular cases, we obtain a number of corollaries,which include some interesting versions of fixed point theorem.

关键词： Vectorial Ekeland variational principle vectorial Caristi's fixed point theorem vectorial Takahashi's non-convex minimization th

P-Distances, Q-Distances and a Generalized Ekeland's Variational Principle in Uniform Spaces

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Acta Mathematica Sinica,English Series 2012年第2期28卷 235-254页

作者： Jing Hui QIU fei he School of Mathematical Sciences Soochow UniversitySuzhou 215006 P.R.China School of Mathematical Sciences Inner Mongolia UniversityHohhot 010021P.R.China

In this paper, we attempt to give a unified approach to the existing several versions of Ekeland＇s variational principle. In the framework of uniiorm spaces, we introduce p-distances and more generally, q-distances. Then we introduce a new type of completeness for uniform spaces, i.e., sequential completeness with respect to a q-distance （particularly, a p-distance）, which is a very extensive concept of completeness. By using q-distances and the new type of completeness, we prove a generalized Takahashi＇s nonconvex minimization theorem, a generalized Ekeland＇s variational principle and a generalized Caristi＇s fixed point theorem. Moreover, we show that the above three theorems are equivalent to each other. From the generalized Ekeland＇s variational principle, we deduce a number of particular versions of Ekeland＇s principle, which include many known versions of the principle and their improvements.

关键词： Ekeland's variational principle Takahashi's nonconvex minimization theorem Caristi'sfixed point theorem uniform space locally convex space p-distance q-distance