scholarly journals Jordan Form-Based Algebraic Conditions for Controllability of Multiagent Systems under Directed Graphs

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-18 ◽  
Author(s):  
Shuai Liu ◽  
Zhijian Ji ◽  
Huizi Ma
Keyword(s):  
Model Simulation ◽  
Directed Graphs ◽  
Jordan Form ◽  
System Matrix ◽  
Information Communication ◽  
Input Disturbance ◽  
Practical Engineering ◽  
Modernization Process ◽  
Sufficiency Conditions ◽  
Selection Of

Based on the Jordan form of system matrix, this paper discusses algebraic conditions for the controllability of the multiagent network system with directed graph from two aspects: leader-follower network attribute and coupling input disturbance. Leader-follower network attribute refers to the topology structure and information communication among agents. Coupling input disturbance includes the number of external coupling inputs and the selection of leader nodes. When the leader-follower network attribute is fixed, the selection method of coupling input disturbance is studied for the controllability, and when the coupling input disturbance is known, we derive necessity and sufficiency conditions to determine the controllability. The reliability of theoretical results is verified by numerical examples and model simulation. Besides, the generally perfect controllability is introduced, that is, the system is always controllable regardless of the number and the locations of leaders. In practical engineering applications, the perfectly controllable topology can improve the system fault tolerance and accelerate the commercialization process, which has a profound significance for promoting the modernization process.

scholarly journals A Multiple and Multi-Level Substructure Method for the Dynamics of Complex Structures

2021 ◽  
Vol 11 (12) ◽  
pp. 5570
Author(s):  
Binbin Wang ◽  
Jingze Liu ◽  
Zhifu Cao ◽  
Dahai Zhang ◽  
Dong Jiang
Keyword(s):  
Structural Characteristics ◽  
Complex Structure ◽  
Complex Structures ◽  
System Matrix ◽  
Substructure Method ◽  
Residual Structure ◽  
The Matrix ◽  
Multi Level ◽  
Fixed Interface ◽  
Selection Of

Based on the fixed interface component mode synthesis, a multiple and multi-level substructure method for the modeling of complex structures is proposed in this paper. Firstly, the residual structure is selected according to the structural characteristics of the assembled complex structure. Secondly, according to the assembly relationship, the parts assembled with the residual structure are divided into a group of substructures, which are named the first-level substructure, the parts assembled with the first-level substructure are divided into a second-level substructure, and consequently the multi-level substructure model is established. Next, the substructures are dynamically condensed and assembled on the boundary of the residual structure. Finally, the substructure system matrix, which is replicated from the matrix of repeated physical geometry, is obtained by preserving the main modes and the constrained modes and the system matrix of the last level of the substructure is assembled to the upper level of the substructure, one level up, until it is assembled in the residual structure. In this paper, an assembly structure with three panels and a gear box is adopted to verify the method by simulation and a rotor is used to experimentally verify the method. The results show that the proposed multiple and multi-level substructure modeling method is not unique to the selection of residual structures, and different classification methods do not affect the calculation accuracy. The selection of 50% external nodes can further improve the analysis efficiency while ensuring the calculation accuracy.

scholarly journals Patient Care, Information, Communication and Social Media Influencing Bias—A Discourse

Informatics ◽  
2021 ◽  
Vol 8 (2) ◽  
pp. 28
Author(s):  
Paula M. Procter
Keyword(s):  
Social Media ◽  
Patient Care ◽  
Information Communication ◽  
Media Communication ◽  
Care Information ◽  
Social Media Communication ◽  
Society Today ◽  
Selection Of

Misinformation and disinformation are prevalent across society today, their rise to prominence developed mainly through the expansion of social media. Communication has always been recognised in health and care settings as the most important element between people who are receiving care and those delivering, managing, and evaluating care. This paper, through a discourse approach, will explore communication through the perception of information formed following personal selection of influencers and try to determine how such affects patient care.

scholarly journals EM Estimation of the X-Ray Spectrum With a Genetically Optimized Step-Wedge Phantom

2021 ◽  
Vol 9 ◽  
Author(s):  
Mengzhou Li ◽  
Feng-Lei Fan ◽  
Wenxiang Cong ◽  
Ge Wang
Keyword(s):  
Energy Spectrum ◽  
Condition Number ◽  
Linear Equations ◽  
Spectrum Estimation ◽  
Genetic Optimization ◽  
System Matrix ◽  
X Ray ◽  
Phantom Design ◽  
Selection Of ◽  
Spectrum Inversion

The energy spectrum of an X-ray tube plays an important role in computed tomography (CT), and is often estimated from physical measurement of dedicated phantoms. Usually, this estimation problem is reduced to solving a system of linear equations, which is generally ill-conditioned. In this paper, we optimize a phantom design to find the most effective combinations of thicknesses for different materials. First, we analyze the ill-posedness of the energy spectrum inversion when the number of unknown variables (N) and measurements (M) are equal, and show the condition number of the system matrix increases exponentially with N if the transmission thicknesses are linearly changed. Then, we present a genetic optimization algorithm to minimize the condition number of the system matrix in a general case (M < N) with respect to the selection of thicknesses and types of phantom materials. Finally, in the simulation with Poisson noise we study the accuracy of the spectrum estimation using the expectation-maximum algorithm. Our results indicate that the proposed method allows high-quality spectrum estimation, and the number of measurements is reduced over two thirds of that required by the widely-used method using a phantom with linearly-changed thicknesses.

Superior Research for Selection of Bracing Structure of Deep Pit Foundation Based on Fussy Theory

2013 ◽  
Vol 838-841 ◽  
pp. 214-218
Author(s):  
Dong Li
Keyword(s):  
General Model ◽  
Engineering Application ◽  
Hard Work ◽  
Deep Foundation ◽  
Scientific Methods ◽  
Deep Pit ◽  
Practical Engineering ◽  
Fuzzy Math ◽  
Selection Of

Before the construction of the deep pit foundation, we must choose a project. Although there aren't many projects to be chosen as usual, we often feel that it's a very complex and hard work. Actually there is no a mature and general model to use. In this paper, the author attempted to use the theory of fuzzy math to establish a former to select the best project, meanwhile provided two ways to solve how to quantify the qualitative targets and how to determine the weights of the targets. Finally they were confirmed to be useful and successful by a practical engineering application. It is worthily to popularize these scientific methods in construction and management in deep foundation pits.

scholarly journals Performance Evaluation of MDO Architectures within a Variable Complexity Problem

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Daiyu Zhang ◽  
Baowei Song ◽  
Peng Wang ◽  
Yanru He
Keyword(s):  
Performance Evaluation ◽  
Multidisciplinary Design Optimization ◽  
Large Scale ◽  
Multidisciplinary Design ◽  
Design Variables ◽  
Complexity Problem ◽  
Engineering Problems ◽  
Practical Engineering ◽  
Coupling Variables ◽  
Selection Of

Though quite a number of multidisciplinary design optimization (MDO) architectures have been proposed for the optimal design of large-scale multidisciplinary systems, how their performance changes with the complexity of MDO problem varied is not well studied. In order to solve this problem, this paper presents a variable complexity problem which allows people to obtain a MDO problem with arbitrary complexity by specifying its changeable parameters, such as the number of disciplines and the numbers of design variables. Then four investigations are performed to evaluate how the performance of different MDO architectures changes with the number of disciplines, global variables, local variables, and coupling variables varied, respectively. Finally, the results supply guidance for the selection of MDO architectures in solving practical engineering problems with different complexity.

Structure Mechanics Analysis with Different Construction Schemes in Large-Span Space Grid Structure

2013 ◽  
Vol 788 ◽  
pp. 534-537 ◽  
Author(s):  
Zhen Xing Li
Keyword(s):  
Great Influence ◽  
Construction Method ◽  
Quality And Safety ◽  
Grid Structure ◽  
Large Span ◽  
Construction Scheme ◽  
Space Grid ◽  
Mechanics Analysis ◽  
Practical Engineering ◽  
Selection Of

Different construction schemes in the same construction method have great influence on structure mechanics of grid structure, which is very important for the security and stability in large-span space grid structure. So in order to guarantee the quality and safety of the structure during construction, the selection of construction scheme is particularly important. In this paper, the following practical engineering is adopted to discuss characteristics of different construction schemes in large-span space grid structure and provide a reference for what construction scheme should be selected in the installation of similar space grid structures.

scholarly journals Study on Selection of Pressure Regulating Valve for Hydropower Station with Both Surge Tank and Pressure Regulating Valve

2018 ◽  
Vol 246 ◽  
pp. 01033
Author(s):  
Tianchi Zhou ◽  
Gaohui Li ◽  
Yimin Chen
Keyword(s):  
Transient Process ◽  
Maximum Flow ◽  
Hydropower Station ◽  
Surge Tank ◽  
Calculation Results ◽  
Practical Engineering ◽  
Spiral Case ◽  
Unit Speed ◽  
Working Principle ◽  
Selection Of

The transient process in the hydropower station with both surge tank and pressure regulating valve is quite complicated and also critical to operation safety. According to the pressure regulating valve working principle, the influence of the valve diameter on the unit speed and spiral case pressure was analyzed theoretically. Mathematical models of the surge tank and pressure regulating valve in the hydropower station were established based on the characteristic method. In a practical engineering, numerical simulation of large fluctuation and hydraulic disturbance transient process are conducted, verifying the correctness of the theoretical analysis. Based on the calculation results, three principles for selecting the valve diameter are concluded: first, making sure the unit speed meet the regulating guarantee requirements when guide vanes fast close; second, the maximum spiral case pressure of two times should be approximate to each other by controlling the superposition of surge wave and water hammer; third, the maximum flow of the valve should be as close to the rated flow of the turbine as possible. The principles are helpful for selecting the valve diameter in similar hydropower station.

The Comparison of Portal Frame Design by Penalty Function Optimization and Traditional Method

2012 ◽  
Vol 452-453 ◽  
pp. 348-353
Author(s):  
Xian Gen Lin ◽  
Yong Xu
Keyword(s):  
Penalty Function ◽  
Traditional Method ◽  
Optimization Design ◽  
Function Optimization ◽  
Frame Design ◽  
Engineering Statistics ◽  
Portal Frame ◽  
Practical Engineering ◽  
Tapered Members ◽  
Selection Of

The comparison of portal frame design by penalty function optimization and traditional method aim at 30m span portal frame with tapered members was made. It was found that the essence of optimization design was to research the reasonable distributing of sections, through the interaction between capacity and key section parameters the optimization design were realized. Now the idea of green and less energy is fashionable, then optimization design is very significant in practical engineering. According to engineering statistics the optimization design can reduce 15%~30% of material quantity. In this article the selection of parameters during optimization design was expounded.

Selecting Materials to Resist Low Cycle Fatigue

1971 ◽  
Vol 93 (3) ◽  
pp. 444-452 ◽  
Author(s):  
C. E. Feltner ◽  
R. W. Landgraf
Keyword(s):  
Low Cycle Fatigue ◽  
Strength Loss ◽  
Cyclic Stress ◽  
Plastic Strain Amplitude ◽  
Step Test ◽  
Cycle Fatigue ◽  
Empirical Relations ◽  
Practical Engineering ◽  
Incremental Step ◽  
Selection Of

The selection of materials in the design of components to resist low cycle fatigue is considered in terms of reliable methods of material comparison which can be used in lieu of extensive testing programs. Specifically, a procedure is proposed for ranking candidate materials on the basis of resistance to strength loss, repeated straining, repeated stressing, and notch fatigue in the low cycle fatigue region. Easily performed tests requiring only two specimens of each material are utilized. Monotonic and cyclic stress-strain curves are determined from a standard tensile test and an incremental step test, respectively. A material’s cyclic stability is immediately apparent from comparison of the two curves. Values from these curves are then used in conjunction with empirical relations to predict fatigue resistance in terms of plastic strain amplitude, stress amplitude and a fatigue notch parameter. Examples, using practical engineering materials, are presented to illustrate the reliability of the procedure.

Aggregation of Selected Three-Day Periods to Estimate Annual and Seasonal Wet Deposition Totals for Sulfate, Nitrate, and Acidity. Part II: Selection of Events, Deposition Totals, and Source–Receptor Relationships

1995 ◽  
Vol 34 (2) ◽  
pp. 326-339 ◽  
Author(s):  
Jeffrey R. Brook ◽  
Perry J. Samson ◽  
Sanford Sillman
Keyword(s):  
New York ◽  
North America ◽  
Model Simulation ◽  
Eastern North America ◽  
So2 Emissions ◽  
Study Program ◽  
Area Of Interest ◽  
Main Components ◽  
Selection Of

Abstract A method for deriving estimates of long-term acidic deposition over eastern North America based on a limited number of Regional Acid Deposition Model runs has been developed. The main components of this method are the identification of a representative sample of events for model simulation and the aggregation of the deposition totals associated with the events. Meteorological categories, defined according to 3-day progressions of 850-mb wind flow over eastern North America, were used to guide the selection of events. This paper describes how events were selected from the categories and how they were combined (aggregated) to estimate long-term deposition. The effectiveness of the category-based approach was compared against alternate aggregation approaches and it was found to provide the best sample-based estimates of long-term wet sulfate deposition across eastern North America. Thirty events from the 1982–85 time period were selected using a set of predetermined criteria and aggregated to estimate seasonal and annual SO2−4, NO−3, and H+ deposition at 20 Utility Acid Precipitation Study Program sites. The accuracy of the estimates varied geographically and depending upon whether they were for the annual or seasonal time periods. Over the main area of interest (a smaller 13-site region), the mean rms errors for annual deposition were 10%, 15%, and 12% for sulfate, nitrate, and acidity, respectively. Source–receptor relationships associated with the 30 events were examined for three sites located in Michigan, North Carolina, and upstate New York. It was found that the amount of time that transport was to these areas from the U.S. Midwest (an area of high SO2 emissions) was represented to within 20%.

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