scholarly journals Resilient three-dimensional ordered architectures assembled from nanoparticles by DNA

2021 ◽  
Vol 7 (12) ◽  
pp. eabf0617
Author(s):  
Pawel W. Majewski ◽  
Aaron Michelson ◽  
Marco A. L. Cordeiro ◽  
Cheng Tian ◽  
Chunli Ma ◽  
...  
Keyword(s):  
Narrow Range ◽  
Three Dimensional ◽  
Dna Assembly ◽  
Extreme Temperatures ◽  
Operational Conditions ◽  
Assembly Strategy ◽  
Spatial Topology ◽  
Radiation Conditions

Rapid developments of DNA-based assembly methods provide versatile capabilities in organizing nanoparticles (NPs) in three-dimensional (3D) organized nanomaterials, which is important for optics, catalysis, mechanics, and beyond. However, the use of these nanomaterials is often limited by the narrow range of conditions in which DNA lattices are stable. We demonstrate here an approach to creating an inorganic, silica-based replica of 3D periodic DNA-NP structures with different lattice symmetries. The created ordered nanomaterials, through the precise 3D mineralization, maintain the spatial topology of connections between NPs by DNA struts and exhibit a controllable degree of the porosity. The formed silicated DNA-NP lattices exhibit excellent resiliency. They are stable when exposed to extreme temperatures (>1000°C), pressures (8 GPa), and harsh radiation conditions and can be processed by the conventional nanolithography methods. The presented approach allows the use of a DNA assembly strategy to create organized nanomaterials for a broad range of operational conditions.

Study of a synchronizer mechanism through multibody dynamic analysis

2018 ◽  
Vol 233 (6) ◽  
pp. 1601-1613 ◽  
Author(s):  
Ali Farokhi Nejad ◽  
Giorgio Chiandussi ◽  
Vincenzo Solimine ◽  
Andrea Serra
Keyword(s):  
Dynamic Model ◽  
Three Dimensional ◽  
Time Estimation ◽  
Test Rig ◽  
Operational Conditions ◽  
Multibody Dynamic ◽  
Dynamic Analyses ◽  
Single Cone ◽  
Good Agreement ◽  
Numerical Approaches

The synchronizer mechanism represents the essential component in manual, automatic manual, and dual-clutch transmissions. This paper describes a multibody dynamic model for analysis of a synchronizer mechanism subjected to different operational conditions. The three-dimensional multi-dynamic model is developed to predict the dynamic response of synchronizer, especially for calculation of synchronization time. For the purpose of validation, three different synchronizers (single-cone, double-cone, and triple-cone synchronizers) were used on the test rig machine. For the purpose of synchronizing time estimation, an analytical formulation is proposed. The results of the analytical and multibody dynamic analyses were compared with the experimental data, showing a good agreement. The results of analytical and numerical approaches show that the predicted time of synchronization is more precise than previous works. A sensitivity analysis was performed on the single-cone synchronizer, and the effect of tolerance dimension on the dynamic behavior of the synchronizer was reported.

An Investigation of the Structural Dynamics of a Racing Yacht

1999 ◽  
Author(s):  
Frederic Louarn ◽  
Pandeli Temarel
Keyword(s):  
Dynamic Properties ◽  
Three Dimensional ◽  
Element Model ◽  
Point Of View ◽  
Mode Shapes ◽  
Function Technique ◽  
Operational Conditions ◽  
Principal Coordinates ◽  
Modal Summation ◽  
Structural Responses

The dynamic behaviour of a WOR 60 is investigated using three dimensional hydroelasticity theory. Global structural responses (e.g. stresses) in waves are obtained corresponding to the upright as well as to the more realistic heeled sailing configurations, revealing the connection between the ballast keel and the hull as being a critical area of the structure. For the "dry hull" analysis, a global finite element model has been developed, incorporating the hull and deck shell, the internal structure, the ballast keel and the rig together with rigging loads. The modular nature of the model has been used to assess the relative influence of each of the aforementioned components upon the required characteristic dynamic properties (e.g. natural frequencies and principal mode shapes). Regarding the "wet hull" analysis, a three dimensional Green's function technique, using pulsating sources distributed over the wetted surface, provides a numerical solution to the case of the yacht sailing in regular waves at arbitrary heading. Principal coordinates for the rigid body motions and flexible distortions of interest are evaluated and the latter are used to obtain the dynamic stresses in waves using modal summation. This paper will describe the modelling techniques used and discuss the applicability / limitations of hydroelasticity theory regarding this type of structures in the light of the results obtained for the upright and heeled operational conditions, as well as from the point of view of design aspects such as "L" and "T" keel configurations. The ABS design criteria will provide a practical reference for comparing the results from the dynamic analysis.

Problems Associated with the Use of Skirts on Hovercraft

1967 ◽  
Vol 182 (1) ◽  
pp. 201-218
Author(s):  
W. A. Crago
Keyword(s):  
Three Dimensional ◽  
Model Tests ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Operational Conditions ◽  
The Third ◽  
Rough Water ◽  
Delamination Life ◽  
First Time

The lecture commences with a brief description of early hovercraft work and shows how the advent of flexible extensions to the peripheral jets—or ‘skirts’—constituted a breakthrough without which the hovercraft would never have become a practical proposition with the ability to operate over waves and rough ground. It is shown that the introduction of skirts, whilst providing a solution in one respect, also led to a series of problems and three of these are singled out for further discussion. First it is shown that whilst a relatively high internal skirt pressure is desirable to maintain skirt shape under operational conditions, this pressure can also lead to a high rough water drag. The second problem is that of ‘plough in’ and overturning, which is intimately associated with the use of skins. The hydrodynamic mechanisms of both these undesirable phenomena are for the first time explained in detail and are illustrated by means of data obtained from two- and three-dimensional model tests. The third problem raised by the introduction of skirts is skirt oscillation and wear. The techniques necessary to investigate delamination are described and some of the factors which have been shown to be important in increasing delamination life are outlined.

scholarly journals Numerical Simulation and Experimental Study on Temperature Distribution of Self-Lubricating Packing Rings in Reciprocating Compressors

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Jia Xiaohan ◽  
Zhang Qingqing ◽  
Feng Jianmei ◽  
Peng Xueyuan
Keyword(s):  
Temperature Distribution ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Maximum Temperature ◽  
Transfer Model ◽  
Radial Temperature ◽  
Operational Conditions ◽  
External Cooling ◽  
Packing Rings ◽  
Compressor Reliability

The nonuniform abrasion failure and high-temperature thermal failure of packing rings have a significant influence on compressor reliability, particularly that of oil-free compressors. In this study, a test rig was constructed to measure the dynamic temperature of packing rings under different operational conditions in an oil-free reciprocating compressor. The dynamic axial and radial temperature distributions of the packing rings were obtained using an innovative internal temperature testing device that kept the thermocouples and packing box relatively static during compressor operation. A three-dimensional heat transfer model was also developed to analyze the temperature distribution of the packing boxes, piston rod, and cylinder during such operation. Good agreement was observed between the simulation results and experimental data, which showed an average relative error of less than 2.35%. The results indicate that the pressure ratio exerts a significant effect on the axial temperature distribution and determines which packing ring reaches the maximum temperature. They also show the average temperature to rise with an increase in the rotational speed and to fall with an improvement in the external cooling conditions. Finally, the material of the packing rings was found to affect the temperature gradient from their inner to outer surface.

Second-Order Radiation Condition of Scattering Wave and Its Application

1990 ◽  
Vol 112 (3) ◽  
pp. 177-180
Author(s):  
J. Li ◽  
H. Huang
Keyword(s):  
Differential Operators ◽  
Three Dimensional ◽  
Radiation Condition ◽  
Second Order ◽  
Wave Forces ◽  
Interior Region ◽  
Linear Differential Operators ◽  
Scattering Wave ◽  
Linear Differential ◽  
Radiation Conditions

The first and second-order radiation conditions for scattering waves in two and three-dimensional problems have been derived by virtue of a sequence of linear differential operators. The wave forces on a large circular cylinder are computed by using finite element methods with first and second-order radiation conditions and the Sommerfeld condition, respectively. The results show that an improvement in accuracy is achieved by employing the second-order radiation condition. The interior region in which finite elements are employed can be restricted to a much smaller one, compared with that using the Sommerfeld condition and the computing efforts and required storage in the computer are reduced.

Spatial Topology Identification of Three-Dimensional Complex Block System of Rock Masses

2019 ◽  
Vol 19 (12) ◽  
pp. 04019127
Author(s):  
Xiaodong Fu ◽  
Qian Sheng ◽  
Liwei Wang ◽  
Jian Chen ◽  
Zhenping Zhang ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Rock Masses ◽  
Topology Identification ◽  
Block System ◽  
Spatial Topology ◽  
Complex Block

Leading-edge receptivity of a hypersonic boundary layer on a flat plate

2001 ◽  
Vol 426 ◽  
pp. 73-94 ◽  
Author(s):  
A. A. MASLOV ◽  
A. N. SHIPLYUK ◽  
A. A. SIDORENKO ◽  
D. ARNAL
Keyword(s):  
Boundary Layer ◽  
Acoustic Waves ◽  
Free Stream ◽  
Three Dimensional ◽  
Leading Edge ◽  
Experimental Investigations ◽  
Two Dimensional ◽  
Inclination Angles ◽  
Tollmien Schlichting ◽  
Radiation Conditions

Experimental investigations of the boundary layer receptivity, on the sharp leading edge of a at plate, to acoustic waves induced by two-dimensional and three- dimensional perturbers, have been performed for a free-stream Mach number M∞ = 5.92. The fields of controlled free-stream disturbances were studied. It was shown that two-dimensional and three-dimensional perturbers radiate acoustic waves and that these perturbers present a set of harmonic motionless sources and moving sources with constant amplitude. The disturbances excited in the boundary layer were measured. It was found that acoustic waves impinging on the leading edge generate Tollmien–Schlichting waves in the boundary layer. The receptivity coefficients were obtained for several radiation conditions and intensities. It was shown that there is a dependence of receptivity coefficients on the wave inclination angles.

scholarly journals Effects of Operating Conditions on the Flow in the Moving Blade Passage of a Single Stage Axial-Flow Fan

1997 ◽  
Vol 3 (4) ◽  
pp. 269-276 ◽  
Author(s):  
Tsutomu Adachi ◽  
Yutaka Yamashita ◽  
Kennichiro Yasuhara ◽  
Tatsuo Kawai
Keyword(s):  
Three Dimensional ◽  
Axial Flow ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Hot Wire ◽  
Axial Flow Fan ◽  
Blade Passage ◽  
Operational Conditions ◽  
Flow Phenomena ◽  
Steady Velocity

Three dimensional steady and unsteady velocity distributions in the axial flow fan were measured using a hot wire probe for various operational conditions, various rotational speeds and various measuring positions. For measuring the velocity distributions in the blade passage, a specially designed and manufactured hot wire traversing apparatus was used. Steady velocity distributions, turning angles, effects of incident to the cascade, flow leakage through the tip clearance and effects of the flow separation show the flow phenomena through the blade passages. Unsteady velocity distributions show time dependent procedures of the wake flowing through the moving blade passage. Considering these results of measurements, the effects of the upstream stationary blade and the effects of Reynolds number on the flow were considered.

scholarly journals Enhancement of thrust reverser cascade performance using aerodynamic and structural integration

2004 ◽  
Vol 108 (1090) ◽  
pp. 621-628 ◽  
Author(s):  
J. Butterfield ◽  
H. Yao ◽  
M. Price ◽  
C. Armstrong ◽  
S. Raghunathan ◽  
...  
Keyword(s):  
Structural Model ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Product Development Process ◽  
Structural Performance ◽  
Two Dimensional ◽  
Operational Conditions ◽  
Structural Integration ◽  
Thrust Reverser ◽  
Reverse Thrust

AbstractThis paper focuses on the design of a cascade within a cold stream thrust reverser during the early, conceptual stage of the product development process. A reliable procedure is developed for the exchange of geometric and load data between a two dimensional aerodynamic model and a three dimensional structural model. Aerodynamic and structural simulations are carried out using realistic operating conditions, for three different design configurations with a view to minimising weight for equivalent or improved aerodynamic and structural performance. For normal operational conditions the simulations show that total reverse thrust is unaffected when the performance of the deformed vanes is compared to the un-deformed case. This shows that for the conditions tested, the minimal deformation of the cascade vanes has no significant affect on aerodynamic efficiency and that there is scope for reducing the weight of the cascade. The pressure distribution through a two dimensional thrust reverser section is determined for two additional cascade vane configurations and it is shown that with a small decrease in total reverse thrust, it is possible to reduce weight and eliminate supersonic flow regimes through the nacelle section. By increasing vane sections in high pressure areas and decreasing sections in low pressure areas the structural performance of the cascade vanes in the weight reduced designs, is improved with significantly reduced levels of vane displacement and stress.

Directed self-assembly pathways of three-dimensional Pt/Pd nanocrystal superlattice electrocatalysts for enhanced methanol oxidation reaction

2018 ◽  
Vol 6 (26) ◽  
pp. 12759-12767 ◽  
Author(s):  
Guangran Xu ◽  
Rui Si ◽  
Jiayin Liu ◽  
Luyao Zhang ◽  
Xia Gong ◽  
...  
Keyword(s):  
Methanol Oxidation ◽  
Self Assembly ◽  
Oxidation Reaction ◽  
Active Sites ◽  
Nitrogen Doping ◽  
Three Dimensional ◽  
Methanol Oxidation Reaction ◽  
Assembly Strategy ◽  
Nanocrystal Superlattices ◽  
Assembly Pathways

A new directed self-assembly strategy is developed to achieve 3D Pt/Pd nanocrystal superlattices with enhanced electrocatalytic performance for methanol oxidation reaction due to the enriched metallic Pt active sites by appropriate Pd alloying and surface nitrogen doping.

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