Distribution of the circulation times in a batch mixed by two impellers on a common shaft

1989 ◽  
Vol 54 (3) ◽  
pp. 633-644
Author(s):  
Vladimír Kudrna ◽  
Václav Koza ◽  
Jiří Hájek
Keyword(s):  
Theoretical Model ◽  
Tracer Particle ◽  
Visual Observation ◽  
Expected Value ◽  
Experimental Results ◽  
Statistical Characteristics ◽  
Frequency Function ◽  
Simple Method ◽  
Primary Processing ◽  
Mixed Batch

The paper has been devoted to the study of the circulation times in a batch mixed by several impellers on a common shaft. A simple method has been used to carry out the measurements based on visual observation of the motion of a tracer particle in the mixed batch. Individual passages of the tracer particle through the check surface have been signalized to a computer performing the primary processing of data, calculation of the basic statistical characteristics (expected value and variance) and the frequency function of the circulation times of the tracer particle. A model developed earlier for a vessel mixed by a single impeller has been used to interpret the data. This theoretical model has been compared with experimental results.

Actuation and dynamic mechanical characteristics of a core free flat dielectric electro-active polymer soft actuator

2020 ◽  
Vol 14 (4) ◽  
pp. 7396-7404
Author(s):  
Abdul Malek Abdul Wahab ◽  
Emiliano Rustighi ◽  
Zainudin A.
Keyword(s):  
Theoretical Model ◽  
Resonance Frequency ◽  
Dynamic Testing ◽  
Experimental Results ◽  
Percentage Error ◽  
Initial Tension ◽  
Average Percentage ◽  
Soft Actuator ◽  
Average Percentage Error ◽  
Mechanical Dynamics

Various complex shapes of dielectric electro-active polymer (DEAP) actuator have been promoted for several types of applications. In this study, the actuation and mechanical dynamics characteristics of a new core free flat DEAP soft actuator were investigated. This actuator was developed by Danfoss PolyPower. DC voltage of up to 2000 V was supplied for identifying the actuation characteristics of the actuator and compare with the existing formula. The operational frequency of the actuator was determined by dynamic testing. Then, the soft actuator has been modelled as a uniform bar rigidly fixed at one end and attached to mass at another end. Results from the theoretical model were compared with the experimental results. It was found that the deformation of the current actuator was quadratic proportional to the voltage supplied. It was found that experimental results and theory were not in good agreement for low and high voltage with average percentage error are 104% and 20.7%, respectively. The resonance frequency of the actuator was near 14 Hz. Mass of load added, inhomogeneity and initial tension significantly affected the resonance frequency of the soft actuator. The experimental results were consistent with the theoretical model at zero load. However, due to inhomogeneity, the frequency response function’s plot underlines a poor prediction where the theoretical calculation was far from experimental results as values of load increasing with the average percentage error 15.7%. Hence, it shows the proposed analytical procedure not suitable to provide accurate natural frequency for the DEAP soft actuator.

scholarly journals Investigation of thermal conductivity of single-wall carbon nanotubes

2011 ◽  
Vol 15 (2) ◽  
pp. 565-570 ◽  
Author(s):  
Mahmoud Jafari ◽  
Majid Vaezzadeh ◽  
Momhamad Mansouri ◽  
Abazar Hajnorouzi
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Theoretical Model ◽  
Potential Energy ◽  
Experimental Results ◽  
Single Wall Carbon Nanotubes ◽  
Lattice Vibrations ◽  
Single Wall Carbon ◽  
Thermal Potential ◽  
Conductivity Behavior

In this paper, the thermal conductivity of Single-wall carbon nanotubes (SWCNTs) is determined by lattice vibrations (phonons) and free elections. The thermal conductivity of SWCNTs is modeled up to 8-300 K and the observed deviations in K-T figures of SWCNTs are explained in terms of phonon vibrations models. An suitable theoretical model is shown for thermal conductivity behavior with respect to temperature and is generalized for experimental results. This model enables us to calculate thermal conductivity SWNTs and Thermal Potential Energy (TPE).

Theoretical Model for Interfacial Nonlinear Bond Softening Behavior between Embedded Steel and HSHPC

2007 ◽  
Vol 348-349 ◽  
pp. 845-848
Author(s):  
Shan Suo Zheng ◽  
Lei Li ◽  
Guo Zhuan Deng ◽  
Shun Li Che ◽  
Wei Zhao
Keyword(s):  
Theoretical Model ◽  
High Performance ◽  
High Performance Concrete ◽  
High Strength ◽  
Nonlinear Process ◽  
Experimental Results ◽  
Interfacial Bond ◽  
Bond Slip ◽  
Softening Behavior ◽  
Bond Softening

The latest experimental study on steel reinforced high strength and high performance concrete (SRHSHPC) specimens shows that there exists interfacial bond softening phenomenon between embedded steel and high strength and high performance concrete (HSHPC), and it makes the shear transfer capacity between shaped steel and HSHPC be progressively reduced. To predict failure load in design, a theoretical model for interfacial bond softening behavior is required. As interfacial bond softening behavior is a nonlinear process involving material properties, it can be analyzed once the relation of interfacial bond stress (τ ) and slippage ( s ) is known. In this paper, the mechanism of interfacial bond-slip is studied, thus a simplified τ − s relation including ascending and descending parts is proposed and employed to analyze the interfacial nonlinear bond-slip process. Based on the interfacial equilibrium between steel and HSHPC as well as the τ − s relation, the basic governing equations in both softened region and elastic region are established and solved for steel strain or stress. At last, the application of the model is verified through comparison with experimental results. The calculating results of the model are found to be in good agreement with experimental results, showing that the model can describe the bond-slip process in real material systems.

Initial Experiments on the Control of a Mobile Tower Crane

2007 ◽  
Author(s):  
Joshua Vaughan ◽  
William Singhose ◽  
Paulo Debenest ◽  
Edwardo Fukushima ◽  
Shigeo Hirose
Keyword(s):  
Theoretical Model ◽  
Material Handling ◽  
Operational Efficiency ◽  
Experimental Results ◽  
Input Shaping ◽  
Oscillatory Dynamics ◽  
Tower Crane ◽  
Operational Capabilities ◽  
The World

Cranes are used extensively throughout the world in a wide variety of construction and material handling applications. The speed at which these cranes are operated is limited by payload oscillation. Input shaping is one method that reduces this oscillation, allowing higher speeds and improving operational efficiency. Another method to improve the operational capabilities of cranes is to allow base motion. This paper presents initial experimental results from a portable, mobile tower crane. A theoretical model of the crane is presented and experimentally verified. The oscillatory dynamics of the crane are highlighted and controllers to combat these unwanted dynamics are presented.

Physics-Based Friction Model With Potential Application in Numerical Models for Tire-Road Traction

2017 ◽  
Author(s):  
Anahita Emami ◽  
Seyedmeysam Khaleghian ◽  
Chuang Su ◽  
Saied Taheri
Keyword(s):  
Theoretical Model ◽  
Friction Coefficient ◽  
Numerical Models ◽  
Surface Profile ◽  
Viscoelastic Behavior ◽  
Numerical Results ◽  
Experimental Results ◽  
Real Contact Area ◽  
Computer Algorithms ◽  
Road Surfaces

Good understanding of friction in tire-road interaction is of critical importance for vehicle dynamic control systems. Most of the friction models proposed to describe the friction coefficient between tire-treads and road surfaces have been developed based on empirical or semi-empirical relations that are not able to include many effective parameters involved in the tire-road interactions. Therefore, these models are just useful in limited conditions similar to the experiments, and do not accurately represent tire-road traction in numerical tire models. However, in last two decades, a few theoretical models have been developed to calculate the tire-road friction coefficient theoretically by considering both viscoelastic behavior of tire tread compounds and multi-scale interactions between tire treads and rough road surfaces. In this article, a novel physics-based model proposed by Persson has been investigated and used to develop computer algorithms for calculation of sliding friction coefficient between a tire tread compound and a rough substrate. The viscoelastic behavior of tread compound and the surface profile of rough counter surface are the inputs of this physics-based theoretical model. The numerical results of the model have been compared with the experimental results obtained from a dynamic friction tester designed and built in the Center for Tire Research (CenTire). Good agreement between numerical results of theoretical model and experimental results has been found at intermediate range of slip velocities considering the effect of adhesion and shearing in the real contact area in addition to hysteresis friction due to internal energy dissipation in the tire tread compound.

A Simple Method for Simultaneous Projection of a Schlieren Image on a Viewing Screen and into a Camera

1963 ◽  
Vol 67 (631) ◽  
pp. 454-454 ◽  
Author(s):  
C. Nebbeling
Keyword(s):  
Light Beam ◽  
Time Lag ◽  
Visual Observation ◽  
Schlieren Image ◽  
Steady Flows ◽  
Knife Edge ◽  
Simple Method ◽  
Schlieren System ◽  
Simple Arrangement ◽  
Viewing Screen

The toepler schlieren system of wind tunnels is usually designed in such a way that an image of the flow in the test section can be formed in a camera for taking flow pictures. For visual observation, a mirror is inserted in the light beam and the image is projected on a screen. When a photograph or film record of the flow is desired, the mirror is removed by some quick-acting mechanism to allow the light beam to enter the camera. Especially in the case of non-steady flows, the time lag involved in removing the mirror can prove to be a drawback. An interesting pattern observed upon the screen may have vanished by the time the light beam is switched over to the camera. At the same time the image disappears from the screen, leaving the operator in doubt whether or not the pattern lasted long enough to be recorded by the camera. In this note a very simple arrangement of the schlieren system is described, which gives simultaneously an image on the viewing screen and in the camera. So far as the author knows, it is not applied elsewhere. The method consists of the use of a mirror knife edge instead of the usual knife edge.

An Algorithm for Modeling the Covalent Triazine-Based Frameworks

2019 ◽  
Vol 956 ◽  
pp. 212-217
Author(s):  
Ce Song ◽  
Zhao Liang Meng ◽  
Jin Yan Wang ◽  
Fang Yuan Hu ◽  
Xi Gao Jian
Keyword(s):  
Theoretical Model ◽  
Pore Size ◽  
Structural Properties ◽  
Experimental Results ◽  
Size Distributions ◽  
Design Strategies ◽  
Surface Areas ◽  
Pore Size Distributions ◽  
Amorphous Structures ◽  
Acceptable Consistency

An algorithm for generating the representative structures of covalent triazine-based frameworks (CTFs) is proposed, and examined by being applied to the framework synthesized by the trimerization of dicyanobenzene. The algorithm is validated by the comparison between the calculated and experimental results of the structural properties such as surface areas and pore size distributions, which shows acceptable consistency. Moreover, the presented modeling approach can be expected for more extensive use for other CTFs. Thus the simulated atomistic strucutures produced from the modeling method can improve the understanding for amorphous structures of the CTFs which have already been developed, as well as predict the theoretical model of new CTFs, and provide useful design strategies for the future experimental efforts.

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