scholarly journals Fact-Alternating Mutex Groups for Classical Planning

2018 ◽  
Vol 61 ◽  
pp. 475-521
Author(s):  
Daniel Fišer ◽  
Antonín Komenda
Keyword(s):  
Linear Programming ◽  
Theoretical Analysis ◽  
Complexity Analysis ◽  
Simple Algorithm ◽  
Finite Domain ◽  
Initial State ◽  
Pruning Algorithm ◽  
Dead End ◽  
New Type ◽  
Np Complete

Mutex groups are defined in the context of STRIPS planning as sets of facts out of which, maximally, one can be true in any state reachable from the initial state. The importance of computing and exploiting mutex groups was repeatedly pointed out in many studies. However, the theoretical analysis of mutex groups is sparse in current literature. This work provides a complexity analysis showing that inference of mutex groups is as hard as planning itself (PSPACE-Complete) and it also shows a tight relationship between mutex groups and graph cliques. This result motivates us to propose a new type of mutex group called a fact-alternating mutex group (fam-group) of which inference is NP-Complete. Moreover, we introduce an algorithm for the inference of fam-groups based on integer linear programming that is complete with respect to the maximal fam-groups and we demonstrate how beneficial fam-groups can be in the translation of planning tasks into finite domain representation. Finally, we show that fam-groups can be used for the detection of dead-end states and we propose a simple algorithm for the pruning of operators and facts as a preprocessing step that takes advantage of the properties of fam-groups. The experimental evaluation of the pruning algorithm shows a substantial increase in a number of solved tasks in domains from the optimal deterministic track of the last two planning competitions (IPC 2011 and 2014).

scholarly journals Fact-Alternating Mutex Groups for Classical Planning (Extended Abstract)

2018 ◽  
Author(s):  
Daniel Fišer ◽  
Antonín Komenda
Keyword(s):  
Linear Programming ◽  
Integer Linear Programming ◽  
Experimental Evaluation ◽  
Complexity Analysis ◽  
Finite Domain ◽  
Initial State ◽  
Pruning Algorithm ◽  
Dead End ◽  
New Type ◽  
Np Complete

Mutex groups are defined in the context of STRIPS planning as sets of facts out of which, maximally, one can be true in any state reachable from the initial state. This work provides a complexity analysis showing that inference of mutex groups is as hard as planning itself (PSPACE-Complete) and it also shows a tight relationship between mutex groups and graph cliques. Furthermore, we propose a new type of mutex group called a fact-alternating mutex group (fam-group) of which inference is NP-Complete. We introduce an algorithm for the inference of fam-groups based on integer linear programming that is complete with respect to the maximal fam-groups and we demonstrate that fam-groups can be beneficial in the translation of planning tasks into finite domain representation, for the detection of dead-end state and for the pruning of spurious operators. The experimental evaluation of the pruning algorithm shows a substantial increase in a number of solved tasks in domains from the optimal deterministic track of the last two planning competitions (IPC 2011 and 2014).

scholarly journals Molecular Simulation and Theoretical Analysis of Slide-Ring Gels under Biaxial Deformation

Gels ◽  
2021 ◽  
Vol 7 (3) ◽  
pp. 129
Author(s):  
Kotaro Tanahashi ◽  
Tsuyoshi Koga
Keyword(s):  
Theoretical Analysis ◽  
Molecular Mechanism ◽  
Elastic Properties ◽  
Mechanical Characteristics ◽  
Slip Model ◽  
Biaxial Deformation ◽  
New Type ◽  
Cross Links ◽  
Nonlinear Stretching ◽  
Stretching Effect

Slide-ring (SR) gels, a new type of gels that have cross-links moving along the chains, are known to have unique mechanical characteristics. In the case of biaxial deformations, it has been experimentally shown that the stress–strain (S–S) relationships of SR gels can be well described by the neo-Hookean (NH) model. This behavior is quite different from that of conventional chemical gels, where the S–S curves deviate from the NH model. To understand the molecular mechanism of such peculiar elastic properties of SR gels, we studied the effects of movable cross-links by using molecular simulations and theoretical analysis. We calculate the S–S relationships in biaxial deformation for two types of models: slip model, where the cross-links can slide along chains representing SR gels, and non-slip model, which corresponds to conventional chemical gels. In the theoretical analysis, we calculate the S–S relationships by using the models with the Gaussian and the Langevin chains to investigate the nonlinear stretching effect of the chain in the slip and non-slip models. As a result, we found that the peculiar elastic behaviors of SR gels in biaxial deformations are well explained by the effect of movable cross-links suppressing the nonlinear stretching of the chain.

Goal Programming and Its Variants

2011 ◽  
pp. 410-417
Author(s):  
John Wang ◽  
Dajin Wang ◽  
Aihua Li
Keyword(s):  
Decision Making ◽  
Linear Programming ◽  
Goal Programming ◽  
Multicriteria Decision Making ◽  
Industrial Applications ◽  
Multiple Objective ◽  
Multi Criteria Decision Making ◽  
Powerful Method ◽  
Noticeable Increase ◽  
New Type

Within the realm of multicriteria decision making (MCDM) exists a powerful method for solving problems with multiple objectives. Goal programming (GP) was the first multiple-objective technique presented in the literature (Dowlatshahi, 2001). The premise of GP traces its origin back to a linear programming study on executive compensation in 1955 by Charnes, Cooper, and Ferguson even though the specific name did not appear in publications until the 1961 textbook entitled Management Models and Industrial Applications of Linear Programming, also by Charnes and Cooper (Schniederjans, 1995). Initial applications of this new type of modeling technique demonstrated its potential for a variety of applications in numerous different areas. Until the middle of the 1970s, GP applications reported in the literature were few and far between. Since that time, primarily due to influential works by Lee and Ignizio, a noticeable increase of published GP applications and technical improvements has been recognized. The number of case studies, along with the range of fields, to which GP has been and still is being applied is impressive, as shown in surveys by Romero (1991) and Aouni and Kettani (2001). It can be said that GP has been, and still is, the “most widely used multi-criteria decision making technique” (Tamiz, Jones, & Romero, 1998, p. 570).

A Hybrid Model of Cross-Domain Authentication for Password Synchronization

2011 ◽  
Vol 474-476 ◽  
pp. 729-734
Author(s):  
Qiu Yu Zhang ◽  
Zhi Peng Cai ◽  
Zhan Ting Yuan ◽  
Feng Man Miao
Keyword(s):  
Distributed Computing ◽  
Theoretical Analysis ◽  
Hybrid Model ◽  
Transport Protocols ◽  
Key Technology ◽  
Cross Domain ◽  
New Type ◽  
Hybrid Cross

Cross-domain authentication is a key technology used in distributed computing, however, it isn’t perfect. In this paper, a new type of hybrid cross-domain authentication model is proposed to make up its shortcoming in safety, scalability and password synchronization. In this model, advantages of Kerberos and SAML in cross-domain authentication process are combined, and it mixed password transport protocols is adopted to achieve password synchronization. Theoretical analysis shows it can enhance the security and scalability of cross-domain authentication, the efficiency of cross-domain authentication is also improved as the attainment of password synchronization.

Some NP-complete problems in linear programming

1982 ◽  
Vol 1 (3) ◽  
pp. 101-104 ◽  
Author(s):  
R. Chandrasekaran ◽  
Santosh N. Kabadi ◽  
Katta G. Murthy
Keyword(s):  
Linear Programming ◽  
Complete Problems ◽  
Np Complete

Analysis on the Static Characteristics of the New Type Externally Pressurized Spherical Air Bearings

2010 ◽  
Author(s):  
Fusheng Wang ◽  
Gang Bao
Keyword(s):  
Stokes Equations ◽  
Three Dimensional ◽  
Simple Algorithm ◽  
Structure Design ◽  
Measuring Instruments ◽  
Air Bearings ◽  
Static Characteristics ◽  
Mass Properties ◽  
New Type ◽  
Spherical Air Bearings

The new type externally pressurized spherical air bearings used mass properties measuring instruments are studied which are particularly recommended for determining mass properties of rockets, satellites and ballistic objects. The air bearings are the key component of the mass properties measuring instruments. In order to provide some theoretical guideline for the structure design of the new type externally pressurized spherical air bearings, this paper analyzes static characteristics and the factors affecting the static characteristics of the new type air bearings. A finite volume method is adopted to discretize the three-dimensional steady-state compressible Navier-Stokes equations, and a modified SIMPLE algorithm for compressible fluid is applied to solve the discretized governing equations. The pressure field and velocity field of the air bearings are obtained, from which the carrying capacity, static stiffness and mass flow of the air bearings can be derived, and the factors and rules affecting the static characteristics are analyzed. The calculation method proposed in this paper fits well the general principle, which can be extended to the characteristics analysis of other air bearings.

scholarly journals Modeling, Testing, and Characteristic Analysis of a Planetary Flywheel Inerter

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Zheng Ge ◽  
Weirui Wang
Keyword(s):  
Theoretical Analysis ◽  
Planetary Gear ◽  
Gear Ratio ◽  
Ball Screw ◽  
Ring Gear ◽  
Characteristic Analysis ◽  
Planetary Gears ◽  
Nonlinear Dynamical ◽  
Output Force ◽  
New Type

We propose the planetary flywheel inerter, which is a new type of ball screw inerter. A planetary flywheel consists of several planetary gears mounted on a flywheel bracket. When the flywheel bracket is driven by a screw and rotating, each planetary gear meshing with an outer ring gear generates a compound motion composed of revolution and rotation. Theoretical analysis shows that the output force of the planetary flywheel inerter is proportional to the relative acceleration of one terminal of the inerter to the other. Optimizing the gear ratio of the planetary gears to the ring gear allows the planetary flywheel to be lighter than its traditional counterpart, without any loss on the inertance. According to the structure of the planetary flywheel inerter, nonlinear factors of the inerter are analyzed, and a nonlinear dynamical model of the inerter is established. Then the parameters in the model are identified and the accuracy of the model is validated by experiment. Theoretical analysis and experimental data show that the dynamical characteristics of a planetary flywheel inerter and those of a traditional flywheel inerter are basically the same. It is concluded that a planetary flywheel can completely replace a traditional flywheel, making the inerter lighter.

Compound Synchronization Based on Memristive Cellular Neural Network of Chaos System

2016 ◽  
Vol 12 (3) ◽  
Author(s):  
Xiaohong Zhang ◽  
Linyu Liao
Keyword(s):  
Neural Network ◽  
Neural Networks ◽  
Theoretical Analysis ◽  
Lyapunov Stability Theory ◽  
Cellular Neural Network ◽  
Synchronous Control ◽  
Compound Synchronization ◽  
New Type ◽  
Response Systems ◽  
Drive Systems

As a especial type of synchronous method, compound synchronization is designed by multiple drive systems and response systems. In this paper, a new type of compound synchronization of three drive systems and two response systems is investigated. According to synchronous control of five memristive cellular neural networks (CNNs), the theoretical analysis and demonstration are given out by using Lyapunov stability theory. The corresponding numerical simulations and synchronous performance analysis are supplied to verify the feasibility and scalability of compound synchronization design.

scholarly journals Magnetohydrodynamic evolution of magnetic skeletons

2007 ◽  
Vol 463 (2080) ◽  
pp. 1097-1115 ◽  
Author(s):  
Andrew L Haynes ◽  
Clare E Parnell ◽  
Klaus Galsgaard ◽  
Eric R Priest
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Three Dimensional ◽  
Heating Process ◽  
Initial State ◽  
Fundamental Building Block ◽  
New Type ◽  
Field Lines ◽  
First Time ◽  
The Magnetic Field

The heating of the solar corona is probably due to reconnection of the highly complex magnetic field that threads throughout its volume. We have run a numerical experiment of an elementary interaction between the magnetic field of two photospheric sources in an overlying field that represents a fundamental building block of the coronal heating process. The key to explaining where, how and how much energy is released during such an interaction is to calculate the resulting evolution of the magnetic skeleton. A skeleton is essentially the web of magnetic flux surfaces (called separatrix surfaces) that separate the coronal volume into topologically distinct parts. For the first time, the skeleton of the magnetic field in a three-dimensional numerical magnetohydrodynamic experiment is calculated and carefully analysed, as are the ways in which it bifurcates into different topologies. A change in topology normally changes the number of magnetic reconnection sites. In our experiment, the magnetic field evolves through a total of six distinct topologies. Initially, no magnetic flux joins the two sources. Then, a new type of bifurcation, called a global double-separator bifurcation , takes place. This bifurcation is probably one of the main ways in which new separators are created in the corona (separators are field lines at which three-dimensional reconnection takes place). This is the first of five bifurcations in which the skeleton becomes progressively more complex before simplifying. Surprisingly, for such a simple initial state, at the peak of complexity there are five separators and eight flux domains present.

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