High-Efficiency Can Be Achieved for Non-Uniformly Flexible Pitching Hydrofoils via Tailored Collective Interactions

New experiments examine the interactions between a pair of three-dimensional (AR = 2) non-uniformly flexible pitching hydrofoils through force and efficiency measurements. It is discovered that the collective efficiency is improved when the follower foil has a nearly out-of-phase synchronization with the leader and is located directly downstream with an optimal streamwise spacing of X*=0.5. The collective efficiency is further improved when the follower operates with a nominal amplitude of motion that is 36% larger than the leader’s amplitude. A slight degradation in the collective efficiency was measured when the follower was slightly-staggered from the in-line arrangement where direct vortex impingement is expected. Operating at the optimal conditions, the measured collective efficiency and thrust are ηC=62% and CT,C=0.44, which are substantial improvements over the efficiency and thrust of ηC=29% and CT,C=0.16 of two fully-rigid foils in isolation. This demonstrates the promise of achieving high-efficiency with simple purely pitching mechanical systems and paves the way for the design of high-efficiency bio-inspired underwater vehicles.

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Finite Element Modeling for Steel Cord Analysis in Radial Tires

Tire Science and Technology ◽

10.2346/tire.13.410104 ◽

2013 ◽

Vol 41 (1) ◽

pp. 60-79 ◽

Cited By ~ 1

Author(s):

Wei Yintao ◽

Luo Yiwen ◽

Miao Yiming ◽

Chai Delong ◽

Feng Xijin

Keyword(s):

Finite Element ◽

High Efficiency ◽

Force Measurement ◽

Three Dimensional ◽

Local Stress ◽

Tension Force ◽

Center Line ◽

Element Analysis ◽

Design Variables ◽

Steel Cord

ABSTRACT: This article focuses on steel cord deformation and force investigation within heavy-duty radial tires. Typical bending deformation and tension force distributions of steel reinforcement within a truck bus radial (TBR) tire have been obtained, and they provide useful input for the local scale modeling of the steel cord. The three-dimensional carpet plots of the cord force distribution within a TBR tire are presented. The carcass-bending curvature is derived from the deformation of the carcass center line. A high-efficiency modeling approach for layered multistrand cord structures has been developed that uses cord design variables such as lay angle, lay length, and radius of the strand center line as input. Several types of steel cord have been modeled using the developed method as an example. The pure tension for two cords and the combined tension bending under various loading conditions relevant to tire deformation have been simulated by a finite element analysis (FEA). Good agreement has been found between experimental and FEA-determined tension force-displacement curves, and the characteristic structural and plastic deformation phases have been revealed by the FE simulation. Furthermore, some interesting local stress and deformation patterns under combined tension and bending are found that have not been previously reported. In addition, an experimental cord force measurement approach is included in this article.

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Application of Poly(Vinylbenzyltrimethylammonium Tribromide) Resin as an Efficient Polymeric Catalyst in the Acetalization and Diacetylation of Benzaldehydes

Letters in Organic Chemistry ◽

10.2174/1570178617999200718002933 ◽

2020 ◽

Vol 17 ◽

Author(s):

Zubiao Zheng ◽

Bingbing Han ◽

Junjun Hu ◽

Xianwei Li

Keyword(s):

High Efficiency ◽

Optimal Conditions ◽

Mild Conditions ◽

Polymeric Catalyst

: The applications of a new supported tribromide reagent (poly(vinylbenzyltrimethylammonium tribromide) resin) were reported. This supported tribromide resin was used as a catalyst in the acetalization and diacetylation of benzaldehydes under mild conditions with high efficiency. The effects of solvents, amount of the supported tribromide resin on the reactions were investigated. Under the optimal conditions, most of acetal and 1,1-diacetates of benzaldehydes were selectively obtained in excellent yields.

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A method for autonomous collision-free navigation of a quadrotor UAV in unknown tunnel-like environments

Robotica ◽

10.1017/s0263574721000849 ◽

2021 ◽

pp. 1-27

Author(s):

Taha Elmokadem ◽

Andrey V. Savkin

Keyword(s):

Unmanned Aerial Vehicles ◽

Autonomous Underwater Vehicles ◽

Three Dimensional ◽

Underwater Vehicles ◽

Practical Implementation ◽

Challenging Problem ◽

Quadrotor Uav ◽

Navigation Algorithm ◽

Aerial Vehicles ◽

Quadrotor Uavs

Abstract Unmanned aerial vehicles (UAVs) have become essential tools for exploring, mapping and inspection of unknown three-dimensional (3D) tunnel-like environments which is a very challenging problem. A computationally light navigation algorithm is developed in this paper for quadrotor UAVs to autonomously guide the vehicle through such environments. It uses sensors observations to safely guide the UAV along the tunnel axis while avoiding collisions with its walls. The approach is evaluated using several computer simulations with realistic sensing models and practical implementation with a quadrotor UAV. The proposed method is also applicable to other UAV types and autonomous underwater vehicles.

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Construction of the Cellulose Nanofibers (CNFs) Aerogel Loading TiO2 NPs and Its Application in Disposal of Organic Pollutants

Polymers ◽

10.3390/polym13111841 ◽

2021 ◽

Vol 13 (11) ◽

pp. 1841

Author(s):

Kang Li ◽

Xuejie Zhang ◽

Yan Qin ◽

Ying Li

Keyword(s):

High Efficiency ◽

Sol Gel ◽

Cellulose Nanofibers ◽

Three Dimensional ◽

Good Mechanical Property ◽

Polar Groups ◽

Dimensional Network ◽

Natural Polysaccharide ◽

Valuable Method ◽

Adsorption Capability

Aerogels have been widely used in the adsorption of pollutants because of their large specific surface area. As an environmentally friendly natural polysaccharide, cellulose is a good candidate for the preparation of aerogels due to its wide sources and abundant polar groups. In this paper, an approach to construct cellulose nanofibers aerogels with both the good mechanical property and the high pollutants adsorption capability through chemical crosslinking was explored. On this basis, TiO2 nanoparticles were loaded on the aerogel through the sol-gel method followed by the hydrothermal method, thereby the enriched pollutants in the aerogel could be degraded synchronously. The chemical cross-linker not only helps build the three-dimensional network structure of aerogels, but also provides loading sites for TiO2. The degradation efficiency of pollutants by the TiO2@CNF Aerogel can reach more than 90% after 4 h, and the efficiency is still more than 70% after five cycles. The prepared TiO2@CNF Aerogels have high potential in the field of environmental management, because of the high efficiency of treating organic pollutes and the sustainability of the materials. The work also provides a choice for the functional utilization of cellulose, offering a valuable method to utilize the large amount of cellulose in nature.

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Three-dimensional macroporous wood-based selective separation membranes decorated with well-designed Nd(III)-imprinted domains: A high-efficiency recovery system for rare earth element

Journal of Colloid and Interface Science ◽

10.1016/j.jcis.2020.11.030 ◽

2020 ◽

Author(s):

Yilin Wu ◽

Rongxin Lin ◽

Faguang Ma ◽

Wendong Xing ◽

Jianming Pan

Keyword(s):

Rare Earth ◽

Rare Earth Element ◽

Earth Element ◽

High Efficiency ◽

Three Dimensional ◽

Selective Separation ◽

Separation Membranes ◽

Recovery System

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Advances in coupled axial turbine and nonaxisymmetric exhaust volute aerodynamics for turbomachinery

Proceedings of the Institution of Mechanical Engineers Part G Journal of Aerospace Engineering ◽

10.1177/0954410020966454 ◽

2020 ◽

pp. 095441002096645

Author(s):

Jie Gao ◽

Chunde Tao ◽

Dongchen Huo ◽

Guojie Wang

Keyword(s):

Performance Improvement ◽

High Efficiency ◽

Three Dimensional ◽

Great Influence ◽

Aerodynamic Characteristics ◽

Turbine Engines ◽

Gas Turbine Engines ◽

Axial Turbine ◽

Flow Interactions ◽

And Performance

Marine, industrial, turboprop and turboshaft gas turbine engines use nonaxisymmetric exhaust volutes for flow diffusion and pressure recovery. These processes result in a three-dimensional complex turbulent flow in the exhaust volute. The flows in the axial turbine and nonaxisymmetric exhaust volute are closely coupled and inherently unsteady, and they have a great influence on the turbine and exhaust aerodynamic characteristics. Therefore, it is very necessary to carry out research on coupled axial turbine and nonaxisymmetric exhaust volute aerodynamics, so as to provide reference for the high-efficiency turbine-volute designs. This paper summarizes and analyzes the recent advances in the field of coupled axial turbine and nonaxisymmetric exhaust volute aerodynamics for turbomachinery. This review covers the following topics that are important for turbine and volute coupled designs: (1) flow and loss characteristics of nonaxisymmetric exhaust volutes, (2) flow interactions between axial turbine and nonaxisymmetric exhaust volute, (3) improvement of turbine and volute performance within spatial limitations and (4) research methods of coupled turbine and exhaust volute aerodynamics. The emphasis is placed on the turbine-volute interactions and performance improvement. We also present our own insights regarding the current research trends and the prospects for future developments.

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