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Search Results: 1 - 10 of 2819 matches for " Geguang Pu "
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MDM: A Mode Diagram Modeling Framework
Zheng Wang,Geguang Pu,Jianwen Li,Jifeng He
Electronic Proceedings in Theoretical Computer Science , 2012, DOI: 10.4204/eptcs.105.10
Abstract: Periodic control systems used in spacecrafts and automotives are usually period-driven and can be decomposed into different modes with each mode representing a system state observed from outside. Such systems may also involve intensive computing in their modes. Despite the fact that such control systems are widely used in the above-mentioned safety-critical embedded domains, there is lack of domain-specific formal modelling languages for such systems in the relevant industry. To address this problem, we propose a formal visual modeling framework called mode diagram as a concise and precise way to specify and analyze such systems. To capture the temporal properties of periodic control systems, we provide, along with mode diagram, a property specification language based on interval logic for the description of concrete temporal requirements the engineers are concerned with. The statistical model checking technique can then be used to verify the mode diagram models against desired properties. To demonstrate the viability of our approach, we have applied our modelling framework to some real life case studies from industry and helped detect two design defects for some spacecraft control systems.
SAT-based Explicit LTL Reasoning
Jianwen Li,Shufang Zhu,Geguang Pu,Moshe Vardi
Computer Science , 2015,
Abstract: We present here a new explicit reasoning framework for linear temporal logic (LTL), which is built on top of propositional satisfiability (SAT) solving. As a proof-of-concept of this framework, we describe a new LTL satisfiability tool, Aalta\_v2.0, which is built on top of the MiniSAT SAT solver. We test the effectiveness of this approach by demonnstrating that Aalta\_v2.0 significantly outperforms all existing LTL satisfiability solvers. Furthermore, we show that the framework can be extended from propositional LTL to assertional LTL (where we allow theory atoms), by replacing MiniSAT with the Z3 SMT solver, and demonstrating that this can yield an exponential improvement in performance.
Polsat: A Portfolio LTL Satisfiability Solver
Jianwen Li,Geguang Pu,Lijun Zhang,Yinbo Yao,Moshe Y. Vardi,Jifeng he
Computer Science , 2013,
Abstract: In this paper we present a portfolio LTL-satisfiability solver, called Polsat. To achieve fast satisfiability checking for LTL formulas, the tool integrates four representative LTL solvers: pltl, TRP++, NuSMV, and Aalta. The idea of Polsat is to run the component solvers in parallel to get best overall performance; once one of the solvers terminates, it stops all other solvers. Remarkably, the Polsat solver utilizes the power of modern multi-core compute clusters. The empirical experiments show that Polsat takes advantages of it. Further, Polsat is also a testing plat- form for all LTL solvers.
LTLf satisfiability checking
Jianwen Li,Lijun Zhang,Geguang Pu,Moshe Y. Vardi,Jifeng He
Computer Science , 2014,
Abstract: We consider here Linear Temporal Logic (LTL) formulas interpreted over \emph{finite} traces. We denote this logic by LTLf. The existing approach for LTLf satisfiability checking is based on a reduction to standard LTL satisfiability checking. We describe here a novel direct approach to LTLf satisfiability checking, where we take advantage of the difference in the semantics between LTL and LTLf. While LTL satisfiability checking requires finding a \emph{fair cycle} in an appropriate transition system, here we need to search only for a finite trace. This enables us to introduce specialized heuristics, where we also exploit recent progress in Boolean SAT solving. We have implemented our approach in a prototype tool and experiments show that our approach outperforms existing approaches.
On the Relationship between LTL Normal Forms and Buechi Automata
Jianwen Li,Geguang Pu,Lijun Zhang,Zheng Wang,Jifeng He,Kim G. Larsen
Computer Science , 2012,
Abstract: In this paper, we consider the problem of translating LTL formulas to Buechi automata. We first translate the given LTL formula into a special disjuctive-normal form (DNF). The formula will be part of the state, and its DNF normal form specifies the atomic properties that should hold immediately (labels of the transitions) and the formula that should hold afterwards (the corresponding successor state). Surprisingly, if the given formula is Until-free or Release-free, the Buechi automaton can be obtained directly in this manner. For a general formula, the construction is slightly involved: an additional component will be needed for each formula that helps us to identify the set of accepting states. Notably, our construction is an on-the-fly construction, and the resulting Buechi automaton has in worst case 2^{2n+1} states where n denotes the number of subformulas. Moreover, it has a better bound 2^{n+1} when the formula is Until- (or Release-) free.
Fast LTL Satisfiability Checking by SAT Solvers
Jianwen Li,Geguang Pu,Lijun Zhang,Moshe Y. Vardi,Jifeng He
Computer Science , 2014,
Abstract: Satisfiability checking for Linear Temporal Logic (LTL) is a fundamental step in checking for possible errors in LTL assertions. Extant LTL satisfiability checkers use a variety of different search procedures. With the sole exception of LTL satisfiability checking based on bounded model checking, which does not provide a complete decision procedure, LTL satisfiability checkers have not taken advantage of the remarkable progress over the past 20 years in Boolean satisfiability solving. In this paper, we propose a new LTL satisfiability-checking framework that is accelerated using a Boolean SAT solver. Our approach is based on the variant of the \emph{obligation-set method}, which we proposed in earlier work. We describe here heuristics that allow the use of a Boolean SAT solver to analyze the obligations for a given LTL formula. The experimental evaluation indicates that the new approach provides a a significant performance advantage.
MDM: A Mode Diagram Modeling Framework for Periodic Control Systems
Zheng Wang,Geguang Pu,Shenchao Qin,Jianwen Li,Kim G. Larsen,Jan Madsen,Bin Gu,Jifeng He
Computer Science , 2012,
Abstract: Periodic control systems used in spacecrafts and automotives are usually period-driven and can be decomposed into different modes with each mode representing a system state observed from outside. Such systems may also involve intensive computing in their modes. Despite the fact that such control systems are widely used in the above-mentioned safety-critical embedded domains, there is lack of domain-specific formal modelling languages for such systems in the relevant industry. To address this problem, we propose a formal visual modeling framework called MDM as a concise and precise way to specify and analyze such systems. To capture the temporal properties of periodic control systems, we provide, along with MDM, a property specification language based on interval logic for the description of concrete temporal requirements the engineers are concerned with. The statistical model checking technique can then be used to verify the MDM models against desired properties. To demonstrate the viability of our approach, we have applied our modelling framework to some real life case studies from industry and helped detect two design defects for some spacecraft control systems.
Strategy & Techniques for Restoration of Healthy Aquaecosystem from Toxic Super Eutrophic Water Body  [PDF]
Peimin Pu, Jiangping Pu
Journal of Geoscience and Environment Protection (GEP) , 2015, DOI: 10.4236/gep.2015.36009
Abstract:

There are complex river-lake systems in the Taihu Lake catchment with total water surface area of 6174.7 km2, and population density of 1079/km2, including Taihu Lake water surface area of 2338 km2. The water systems in this catchment have healthy aquaecosystems during long history. However, in some riverlets in this catchment the water quality was estimated as “acute toxicity for higher organisms” and over standards for many heavy metal elements content; there were no any living plants and macro organisms in the water body, because there were developed a series of industry with abundant release of heavy metals and difficult decomposition organic chemical components along the riverlets during last decades. The even more serious situation was observed in sediments of the riverlets. How to restore such riverlet into a healthy aquaeosystem with abound plants and higher organisms? The main strategy and techniques are described in this paper as summarizing a report of engineering in a riverlet in Wuxi New District during last years, which leads to restore the aquaecosystem into a healthy one with abundant surface plant cultured on floating islands and observed living fish, lobster, frog, toad, mollusk and others in the riverlet. The main techniques are: 1) softwall buffer technic; 2) floating eco-island technic by using which can culture any plant which can be cultured in solution; 3) immobilized nitrogen cycle bacteria (INCB) technic; 4) tattering esters and other big-molecule organic chemicals by using electronic pulse technic and photosensitization technic; 5) mist spray facility technic for improving dissolved oxygen in deep water layers; 6) technic for buffering and suppressing H2S release from water; 7) the appropriate portion of surface with cultured plant to the total water surface area is about 1/3; 8) Cress [Oenanthe Ljavanica (Bl.) DC.] and Myriophyllum verticilatum L. may be cultured in Taihu Lake catchment during the whole year as main plants with mosaic combination of other supplement plants in different seasons.

Research on College Students’ Conformity in Sports  [PDF]
Pu Liu
Creative Education (CE) , 2016, DOI: 10.4236/ce.2016.73045
Abstract: As a social member, college student will inevitably be influenced by the other students and the society as a whole. Conformity is a psychological term that indicates the influence. It means that an individual tends to keep accordance with the majority under direction or pressure. Conformity is a common phenomenon among college students when they are having PE class or playing sports after class, which has a great effect on students’ physical activities, sport attitude and philosophy of life. This paper analyzes the effects of conformity on college students in sports and gives some practical suggestions to PE instructors about how to make use of conformity to help students change their attitude to sports and form lifelong sports habit.
Study on the Influencing Factors and Countermeasures of Supply and Demand Balance in Real Estate Market in Dazhou  [PDF]
Xiaomei Pu, Lin Tian, Aili Pu
Open Journal of Business and Management (OJBM) , 2018, DOI: 10.4236/ojbm.2018.63041
Abstract: Taking supply and demand of real estate market in Dazhou as an example, this paper obtains the main factors affecting the supply of real estate market by interviews and consulting relevant information. Through questionnaire and further analysis, the main factors affecting the demand of real estate market are brought forward. Countermeasures are then proposed to achieve the balance between supply and demand as well as stable and healthy development of Dazhou’s real estate market.
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