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Search Results: 1 - 10 of 36886 matches for " Jingchao Zhao "
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A Framework of Research and Practice: Relationship between Work Engagement, Affective Commitment, and Turnover Intentions  [PDF]
Liyu Zhao, Jingchao Zhao
Open Journal of Social Sciences (JSS) , 2017, DOI: 10.4236/jss.2017.510019
There is a growing research interest in the topic of work engagement over the past years. In reference to Schauefeli, Salanova, Gonzalez-Roma & Bakker (2002) [1], work engagement is described as “a positive, fulfilling work-related state of mind that is characterized by vigor, dedication and absorption”. As compare to the researches based on the relationship between work engagement and organizational commitment and job performance, the existing researches on the relationship between work engagement and turnover intentions are far fewer. We theoretically discussed the relationship among work engagement, affective commitment and turnover intentions. Research results show that work engagement is negatively related to turnover intentions whereby affective commitment plays a regulating role. Affective commitment moderates the relationship between work engagement and turnover intentions whereby employees’ affective commitment is stronger and employees are more willing to invest effort in their work; hence, employees’ turnover intentions are reduced.
Microstructure and Properties of Fe-Based Coating on Column Surface Formed by High Frequency Induction Cladding  [PDF]
Huilong Yang, Yufu Sun, Jingjie Shen, Sumeng Hu, Qing Zhao, Xiangcai Jia, Jingchao Zhang
Journal of Surface Engineered Materials and Advanced Technology (JSEMAT) , 2012, DOI: 10.4236/jsemat.2012.21007
Abstract: The Fe-based coating was produced on the surface of the column substrate with a Al2O3 cylindrical sleeve by high frequency induction cladding, microstructure of the coating was investigated with scanning electron microscope (SEM), the crystal structure was characterized by X-ray diffractometer (XRD), the microhardness and wear resisitance of the coating were evaluated. The results show that a metallurgical bond between coating and substrate was obtained during the rapid solidification, the phases of the coating were composed of austenite and the eutectic of γ-Fe + (Cr, Fe)7(C, B)3. Compared with the substrate, the microhardness and wear resistance of the coating improved apparently, solid-solution strengthening and second-phase particle hardening led to these results.
Two-Fold Circle-Covering of the Plane under Congruent Voronoi Polygon Conditions
Jingchao Chen
Mathematics , 2014,
Abstract: The $k$-coverage problem is to find the minimum number of circles such that each point in a finite plane is covered by at least $k$ circles. Under equal circle condition, when $k$=1, this problem has been solved by Kershner in 1939. However, when $k > 1$, it becomes hopelessly difficult. One tried to tackle this problem with different restrictions. In this paper, we restrict ourself to congruent Voronoi polygon, and prove the minimum density of the two-coverage with such a restriction. Our proof is simpler and more rigorous than that given recently by Yun et al.
Phase Selection Heuristics for Satisfiability Solvers
Jingchao Chen
Computer Science , 2011,
Abstract: In general, a SAT Solver based on conflict-driven DPLL consists of variable selection, phase selection, Boolean Constraint Propagation, conflict analysis, clause learning and its database maintenance. Optimizing any part of these components can enhance the performance of a solver. This paper focuses on optimizing phase selection. Although the ACE (Approximation of the Combined lookahead Evaluation) weight is applied to a lookahead SAT solver such as March, so far, no conflict-driven SAT solver applies successfully the ACE weight, since computing the ACE weight is time-consuming. Here we apply the ACE weight to partial phase selection of conflict-driven SAT solvers. This can be seen as an improvement of the heuristic proposed by Jeroslow-Wang (1990). We incorporate the ACE heuristic and the existing phase selection heuristics in the new solver MPhaseSAT, and select a phase heuristic in a way similar to portfolio methods. Experimental results show that adding the ACE heuristic can improve the conflict-driven solvers. Particularly on application instances, MPhaseSAT with the ACE heuristic is significantly better than MPhaseSAT without the ACE heuristic, and even can solve a few SAT instances that remain unsolvable so far.
Exploiting Dynamically Propositional Logic Structures in SAT
Jingchao Chen
Computer Science , 2011,
Abstract: The 32-bit hwb (hwb-n32 for short) problem is from equivalence checking that arises in combining two circuits computing the hidden weighted bit function. Since 2002, it remains still unsolvable in every SAT competition. This paper focuses on solving problems such as hwb-n32. Generally speaking, modern solvers can detect only XOR, AND, OR and ITE gates. Other non-clausal formulas (propositional logic structures) cannot be detected. To solve the hwb-n32 problem, we extract dynamically some special propositional logic structures, and then use a variant of DPLL-based solvers to solve the subproblem simplified by the extracted structure information. Using the dynamic extraction technique, we solved efficiently the hwb-n32 problem, even some of which were solved within 3000 seconds.
A Dynamic Phase Selection Strategy for Satisfiability Solvers
Jingchao Chen
Computer Science , 2012,
Abstract: The phase selection is an important of a SAT Solver based on conflict-driven DPLL. This paper presents a new phase selection strategy, in which the weight of each literal is defined as the sum of its implied-literals static weights. The implied literals of each literal is computed dynamically during the search. Therefore, it is call a dynamic phase selection strategy. In general, computing dynamically a weight is time-consuming. Hence, so far no SAT solver applies successfully a dynamic phase selection. Since the implied literal of our strategy conforms to that of the search process, the usual two watched-literals scheme can be applied here. Thus, the cost of our dynamic phase selection is very low. To improve Glucose 2.0 which won a Gold Medal for application category at SAT 2011 competition, we build five phase selection schemes using the dynamic phase selection policy. On application instances of SAT 2011, Glucose improved by the dynamic phase selection is significantly better than the original Glucose. We conduct also experiments on Lingeling, using the dynamic phase selection policy, and build two phase selection schemes. Experimental results show that the improved Lingeling is better than the original Lingeling.
Fast Blocked Clause Decomposition with High Quality
Jingchao Chen
Computer Science , 2015,
Abstract: Any CNF formula can be decomposed two blocked subsets such that both can be solved by BCE (Blocked Clause Elimination). To make the decomposition more useful, one hopes to have the decomposition as unbalanced as possible. It is often time consuming to achieve this goal, since it has been proven to be NP-hard. So far there have been several decomposition and post-processing algorithms such as PureDecompose, QuickDecompose, EagerMover etc. We found that these existing algorithms are often either inefficient or low-quality decomposition. To build an efficient and high-quality algorithm, we improve the existing BCE, and present two new variants of PureDecompose, a new heuristic decomposition called LessInterfereDecompose, and a new post-processing algorithm called RsetGuidedDecompose. Combining these new techniques results in a new algorithm called MixDecompose. In our experiments, there is no application formula where the quality of PureDecompose+EagerMover is better than MixDecompose. In terms of speed, MixDecompose is also very fast. Our average runtime is a little longer, but the worst-case runtime is shorter. In theory, our two variants of PureDecompose requires linear time in the number of clauses. By limiting the size of the touch list used by BCE, we can guarantee always that MixDecompose runs in linear time.
Solving Rubik's Cube Using SAT Solvers
Jingchao Chen
Computer Science , 2011,
Abstract: Rubik's Cube is an easily-understood puzzle, which is originally called the "magic cube". It is a well-known planning problem, which has been studied for a long time. Yet many simple properties remain unknown. This paper studies whether modern SAT solvers are applicable to this puzzle. To our best knowledge, we are the first to translate Rubik's Cube to a SAT problem. To reduce the number of variables and clauses needed for the encoding, we replace a naive approach of 6 Boolean variables to represent each color on each facelet with a new approach of 3 or 2 Boolean variables. In order to be able to solve quickly Rubik's Cube, we replace the direct encoding of 18 turns with the layer encoding of 18-subtype turns based on 6-type turns. To speed up the solving further, we encode some properties of two-phase algorithm as an additional constraint, and restrict some move sequences by adding some constraint clauses. Using only efficient encoding cannot solve this puzzle. For this reason, we improve the existing SAT solvers, and develop a new SAT solver based on PrecoSAT, though it is suited only for Rubik's Cube. The new SAT solver replaces the lookahead solving strategy with an ALO (\emph{at-least-one}) solving strategy, and decomposes the original problem into sub-problems. Each sub-problem is solved by PrecoSAT. The empirical results demonstrate both our SAT translation and new solving technique are efficient. Without the efficient SAT encoding and the new solving technique, Rubik's Cube will not be able to be solved still by any SAT solver. Using the improved SAT solver, we can find always a solution of length 20 in a reasonable time. Although our solver is slower than Kociemba's algorithm using lookup tables, but does not require a huge lookup table.
Design and Implementation of Hybrid Light and Microwave Switches Based on Wavelength Selective Switch for Future Satellite Networks  [PDF]
Bin Wu, Hongxi Yin, Anliang Liu, Chang Liu, Jingchao Wang
Journal of Computer and Communications (JCC) , 2016, DOI: 10.4236/jcc.2016.43003

A hybrid switching node structure with light and microwave links is proposed, which is applicable to the future data relay satellite systems, aiming at the development trend of coexistence of light- link and microwave-link in the future. An experimental system for the light and microwave hybrid switching node based on wavelength selective optical switches (WSS) and optical transceiver modules, is established. It is shown by our experiment that this hybrid switching node can realize the dynamic bandwidth allocation and wavelength routing while the bit error rate of light link is less than 10?12, which provides a method for solving the hybrid switching problem of light-link and microwave-link on the future data relay satellite systems.

Study on Preparation of Superhard Nanopowder by Chaos Vibration with High Strength
Jingchao Zou,Xiaolan Yang,Jifeng Liu
Information Technology Journal , 2012,
Abstract: Superhard nanopowder has the advantages both of superhard and nanopowder but reaching to micron is called Limit by academics. It is found that the superhard tiny-powder continued to refine under high vibration intensity by pre-research, reliability and service life can be ensured by researching PLC advanced preview control system of vibration mill with high strength. The dynamic MATLAB simulation model of mill was built so that the behavior features of chaos vibration with high strength and vibration mechanism can be researched. The influence on energy transfer and the probability of collision of barrel medium granular flow can be analyzed. The mechanism of powder cracks and expansion with high vibration intensity can be researched; This research for solving bottleneck restrictions of low-cost, high-quality preparation of various functional ultra-fine, micro, nano powder, has important theoretical and practical value.
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