Simulation of self-propelled anguilliform swimming by local domain-free discretization method

2011 ◽  
Vol 69 (12) ◽  
pp. 1891-1906 ◽  
Author(s):  
C.H. Zhou ◽  
C. Shu
Keyword(s):  
Local Domain ◽  
Discretization Method

scholarly journals Modeling and Analysis of a Generic Internal Cargo Airdrop System for a Tandem Helicopter

2021 ◽  
Vol 11 (11) ◽  
pp. 5109
Author(s):  
Guozhi Li ◽  
Yihua Cao ◽  
Maosheng Wang
Keyword(s):  
Nonlinear Dynamics ◽  
Flight Dynamics ◽  
Simulation Method ◽  
Rotational Dynamics ◽  
Discretization Method ◽  
Modeling And Analysis ◽  
Flight Velocity ◽  
Vector Mechanics ◽  
Good Attitude

This article describes the results of modeling and analysis of a generic internal cargo system using a discretization method of the vector mechanics. The model can be easily incorporated into a tandem helicopter model and is intended for use of simulation and investigating the problems of flight dynamics, control, etc., both in flight operation loading a cargo and flight operation in the process of airdrops. The model is derived by considering the main descriptions of the cargo, including the linear and rotational dynamics, the kinematics, and the forces and moments acting on the helicopter. A simulation method embedded with a numerical trim algorithm is developed for the complete coupling helicopter/cargo nonlinear dynamics system. The simulation application of the model is illustrated, including the case of flight operation loading a cargo by considering three mass configurations of 3000, 4500, and 6000 kg, and the case of flight operation in the process of airdrops at velocities of 0, 40, 80, 120, and 160 knots. Stabilities of the helicopter in the process of airdrops are also analyzed. The major conclusions drawn are: (i) the tandem helicopter has a good attitude maintaining ability in the whole flight velocity envelope when it conducts a flight operation loading a cargo; (ii) in the process of airdrops, the increase in flight velocity will constantly decrease the helicopter pitching attitude and increases the total airdrop time and decreases the backward moving velocity of the cargo, and helicopter flying at a velocity between 80 and 120 knots might be acceptable; (iii) the stabilities of both the longitudinal and lateral periodic modes are continuing to decrease during the backward movement of the cargo.

scholarly journals Magnetic Configurations in Modulated Cylindrical Nanowires

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 600
Author(s):  
Cristina Bran ◽  
Jose Angel Fernandez-Roldan ◽  
Rafael P. del Real ◽  
Agustina Asenjo ◽  
Oksana Chubykalo-Fesenko ◽  
...  
Keyword(s):  
Domain Walls ◽  
Magnetocrystalline Anisotropy ◽  
Logic Gates ◽  
Local Domain ◽  
Magnetic Nanowires ◽  
Precise Control ◽  
Magnetic Layers ◽  
State Present ◽  
Circular Domains ◽  
3D Applications

Cylindrical magnetic nanowires show great potential for 3D applications such as magnetic recording, shift registers, and logic gates, as well as in sensing architectures or biomedicine. Their cylindrical geometry leads to interesting properties of the local domain structure, leading to multifunctional responses to magnetic fields and electric currents, mechanical stresses, or thermal gradients. This review article is summarizing the work carried out in our group on the fabrication and magnetic characterization of cylindrical magnetic nanowires with modulated geometry and anisotropy. The nanowires are prepared by electrochemical methods allowing the fabrication of magnetic nanowires with precise control over geometry, morphology, and composition. Different routes to control the magnetization configuration and its dynamics through the geometry and magnetocrystalline anisotropy are presented. The diameter modulations change the typical single domain state present in cubic nanowires, providing the possibility to confine or pin circular domains or domain walls in each segment. The control and stabilization of domains and domain walls in cylindrical wires have been achieved in multisegmented structures by alternating magnetic segments of different magnetic properties (producing alternative anisotropy) or with non-magnetic layers. The results point out the relevance of the geometry and magnetocrystalline anisotropy to promote the occurrence of stable magnetochiral structures and provide further information for the design of cylindrical nanowires for multiple applications.

scholarly journals CSR Initiatives and Practices: Empirical Evidence From Indian Metal and Mining Companies

SAGE Open ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 215824402110326
Author(s):  
Ajay K. Singal
Keyword(s):  
Environmental Sustainability ◽  
Annual Reports ◽  
Local Domain ◽  
Internal Governance ◽  
Domain Experts ◽  
Analysis Technique ◽  
Extractive Sector ◽  
Second Tier ◽  
Corporate Social ◽  
Text Network Analysis

This study investigates the corporate social responsibility (CSR) discourse on community and environment by Indian metal and mining (extractive) sector. Specifically, we examine the change in internal governance and external implementation mechanisms in response to affirmative CSR policy actions. Applying text network analysis technique on CSR related expenditures provided in the annual reports and CSR annexures (2014–2018), our study reveals that CSR discourse of extractive firms improved significantly and became more focused after the introduction of post-affirmative policy. CSR initiatives in the extractive sector are primarily focused toward local social development, with little emphasis on the environmental sustainability. Furthermore, companies have adopted two-tier governance structures for managing CSR. The top tier comprises board members who formulate the CSR programs, while the second tier has executives responsible for the implementation. Another tier of governance involving local domain experts is emerging. The three-tier implementation mechanisms give firms a tighter control on spending and enhance the effectiveness of initiatives. We present the results visually in the form of network graphs.

scholarly journals Geometric Design-based Dimensional Synthesis of a Novel Metamorphic Multi-fingered Hand with Maximal Workspace

2021 ◽  
Vol 34 (1) ◽  
Author(s):  
Wei An ◽  
Jun Wei ◽  
Xiaoyu Lu ◽  
Jian S. Dai ◽  
Yanzeng Li
Keyword(s):  
Geometric Design ◽  
Practical Significance ◽  
Design Parameters ◽  
Control Algorithms ◽  
Discretization Method ◽  
Dimensional Synthesis ◽  
Symmetrical Structure ◽  
Design And Optimization ◽  
Total Length

AbstractCurrent research on robotic dexterous hands mainly focuses on designing new finger and palm structures, as well as developing smarter control algorithms. Although the dimensional synthesis of dexterous hands with traditional rigid palms has been carried out, research on the dimensional synthesis of dexterous hands with metamorphic palms remains insufficient. This study investigated the dimensional synthesis of a palm of a novel metamorphic multi-fingered hand, and explored the geometric design for maximizing the precision manipulation workspace. Different indexes were used to value the workspace of the metamorphic hand, and the best proportions between the five links of the palm to obtain the optimal workspace of the metamorphic hand were explored. Based on the fixed total length of the palm member, four nondimensional design parameters that determine the size of the palm were introduced; through the discretization method, the influence of the four design parameters on the workspace of the metamorphic hand with full-actuated fingers and under-actuated fingers was analyzed. Based on the analysis of the metamorphic multi-fingered hand, the symmetrical structure of the palm was designed, resulting in the largest workspace of the multi-fingered hand, and proved that the metamorphic palm has a massive upgrade for the workspace of underactuated fingers. This research contributed to the dimensional synthesis of metamorphic dexterous hands, with practical significance for the design and optimization of novel metamorphic hands.

Sign in / Sign up

Export Citation Format

Share Document