scholarly journals Determining the Horizontal Tail Optimum Dimension of Civil Transport Class Aircraft Based on the Previous Model for Upgrading the Passengers Number

2018 ◽  
Vol 449 ◽  
pp. 012012
Author(s):  
N Aditya ◽  
W Nirbito
Keyword(s):  
Previous Model ◽  
Optimum Dimension

An Optimality Criterion for the Structural Optimization of Machine Elements

2005 ◽  
Vol 127 (3) ◽  
pp. 415-423 ◽  
Author(s):  
C.-P. Teng ◽  
J. Angeles
Keyword(s):  
Structural Optimization ◽  
Optimality Criterion ◽  
Mass Reduction ◽  
Speed Reduction ◽  
Optimum Dimension ◽  
Novel Approach ◽  
Cam Follower ◽  
Machine Elements ◽  
A Current

Methods of structural optimization have been studied and developed over the last three decades. An important aspect of structural optimization pertains to the condition under which the loads are applied. Most machine structures in operation are subject to loads varying as functions of time. In this paper, a novel approach is proposed to cope with loads whose magnitudes vary within given bounds and with variable directions. The underlying ideas are applied to the structural optimization of the roller-carrying disk of a novel class of cam-follower speed reduction devices termed Speed-o-Cam (SoC). Results obtained in this paper are compared with a current prototype and with an intermediate design in which the dimensions of the roller pins are optimized. Combined with the optimum dimension of the roller pins, our structural-optimization results lead to an improvement of almost twice the stiffness with a mass reduction of 40% of the original prototype.

Extending a Van der Pol Based Reduced-Order Model for Fluid-Structure Interaction Applied to Non-Synchronous Vibrations in Turbomachinery

2021 ◽  
Author(s):  
Richard Hollenbach ◽  
Robert Kielb ◽  
Kenneth Hall
Keyword(s):  
Fluid Structure Interaction ◽  
Reduced Order Model ◽  
Van Der Pol Oscillator ◽  
Previous Model ◽  
Stable Limit ◽  
Order Model ◽  
Van Der Pol ◽  
Fluid Structure ◽  
Reduced Order ◽  
Structure Interaction

Abstract This paper expands upon a multi-degree-of-freedom, Van der Pol oscillator used to model buffet and Nonsynchronous Vibrations (NSV) in turbines. Two degrees-of-freedom are used, a fluid tracking variable incorporating a Van der Pol oscillator and a classic spring, mass, damper mounted cylinder variable; thus, this model is one of fluid-structure interaction. This model has been previously shown to exhibit the two main aspects of NSV. The first is the lock-in or entrainment phenomenon of the fluid shedding frequency jumping onto the natural frequency of the oscillator, while the second is a stable limit cycle oscillation (LCO) once the transient solution disappears. Improvements are made to the previous model to better understand this aeroelastic phenomenon. First, an error minimizing technique through a system identification method is used to tune the coefficients in the Reduced Order Model (ROM) to improve the accuracy in comparison to experimental data. Secondly, a cubic stiffness term is added to the fluid equation; this term is often seen in the Duffing Oscillator equation, which allows this ROM to capture the experimental behavior more accurately, seen in previous literature. The finalized model captures the experimental cylinder data found in literature much better than the previous model. These improvements also open the door for future models, such as that of a pitching airfoil or a turbomachinery blade, to create a preliminary design tool for studying NSV in turbomachinery.

Voltage clamping induces resistance and current-voltage plot changes in frog gastric mucosa

1984 ◽  
Vol 246 (5) ◽  
pp. G574-G579
Author(s):  
G. W. Kidder ◽  
M. G. Elrod
Keyword(s):  
Gastric Mucosa ◽  
Membrane Resistance ◽  
Previous Model ◽  
Half Time ◽  
Ion Content ◽  
Zero Current ◽  
Current Voltage ◽  
Measured Resistance ◽  
Voltage Clamping ◽  
Voltage Transients

Changing the potential across the isolated frog gastric mucosa by voltage clamping changes the measured resistance of the tissue in two ways. An immediate change in resistance results from changing the measuring position on the nonlinear current-voltage (I-V) plot. Subsequent to this, the resistance changes slowly with a half-time of about 3 min, a change that is not predicted by a previous model for voltage transients and that implies slow changes in membrane resistance following changes in intracellular ion content. The I-V plot over the range examined shows three breakpoints; changing clamp voltage alters the position of two of these breakpoints as well as the slope of the connecting resistances. The central breakpoint agrees with the potential at zero current and varies with it as the clamp potential is changed, as predicted from a diode model for breakpoint generation.

Revisiting the Butler-Mokrys Model for the Vapor-Extraction Process

SPE Journal ◽  
2019 ◽  
Vol 24 (02) ◽  
pp. 511-521
Author(s):  
V.. Mohan ◽  
P.. Neogi ◽  
B.. Bai
Keyword(s):  
Concentration Profile ◽  
Heavy Oil ◽  
Extraction Process ◽  
Previous Model ◽  
Oil Reservoir ◽  
Vapor Extraction ◽  
Oil Viscosity ◽  
Solvent Vapor ◽  
Vapor Interface ◽  
Heavy Oil Reservoir

Summary The dynamics of a process in which a solvent in the form of a vapor or gas is introduced in a heavy-oil reservoir is considered. The process is called the solvent vapor-extraction process (VAPEX). When the vapor dissolves in the oil, it reduces its viscosity, allowing oil to flow under gravity and be collected at the bottom producer well. The conservation-of-species equation is analyzed to obtain a more-appropriate equation that differentiates between the velocity within the oil and the velocity at the interface, which can be solved to obtain a concentration profile of the solvent in oil. We diverge from an earlier model in which the concentration profile is assumed. However, the final result provides the rate at which oil is collected, which agrees with the previous model in that it is proportional to h, where h is the pay-zone height; in contrast, some of the later data show a dependence on h. Improved velocity profiles can capture this dependence. A dramatic increase in output is seen if the oil viscosity decreases in the presence of the solvent, although the penetration of the solvent into the oil is reduced because under such conditions the diffusivity decreases with decreased solvent. One other important feature we observe is that when the viscosity-reducing effect is very large, the recovered fluid is mainly solvent. Apparently, some optimum might exist in the solubility φo, where the ratio of oil recovered to solvent lost is the largest. Finally, the present approach also allows us to show how the oil/vapor interface evolves with time.

scholarly journals Power Train Designing for Formula styled Racing Car

2021 ◽  
Vol 9 (10) ◽  
pp. 1883-1901
Author(s):  
Malav Sevak
Keyword(s):  
Power Transmission ◽  
Suspension System ◽  
Previous Model ◽  
Brake System ◽  
Maximum Acceleration ◽  
Power Train ◽  
The Road ◽  
Work Done

Abstract: A wheel assembly is an integral part of a vehicle’s design that connects the wheel to the suspension system and transfers pressure from the road to the suspension system. It also holds the brake system and facilitates steering. Power transmission is also addressed in the powertrain department. We describe the process and simulation that result in the hub, upright, and differential mounting of a formula student car and the size of the sprocket for maximum acceleration in this report. As a result of the work done on this project, the resulting car has improved acceleration, is easy and reliable to assemble, and has fewer breakdowns than the previous model. The report includes all the calculations that support the simulations and a validating statement about the bearing selection.

Gondola car designs 1937–1941 and their modernization

Innotrans ◽  
2020 ◽  
pp. 54-60
Author(s):  
Alexey V. Zavadich ◽  
◽  
Alexander V. Smolyaninov ◽  
Keyword(s):  
Cross Section ◽  
Previous Model ◽  
Design Bureau ◽  
Design Elements ◽  
Coupling Buffer ◽  
The Cross ◽  
Constituent Elements ◽  
Interdepartmental Commission ◽  
Building Plant

The authors of the article continue to publish materials on the development and design of gondola structures at the Ural car building plant. The article is devoted to the development of a gondola car by the Ural design Bureau in 1937 and its subsequent modernization. The design elements of the gondola car that differ from the previous model are considered: size, trolley, automatic coupling and brakes, manhole cover, parameters of the gondola car, etc. The results of the work of the Interdepartmental Commission are presented. A new design is considered: coupling buffer beam and the connection of the beams with the lower belt, the constituent elements of the cross section of a center girder and corner posts, etc.

The Impact of Marketing Strategy in Small Family Businesses

2015 ◽  
pp. 1695-1707 ◽  
Author(s):  
Anastasios Ntanos ◽  
Stamatios Ntanos
Keyword(s):  
Marketing Strategy ◽  
Economic Crisis ◽  
Second Generation ◽  
Family Businesses ◽  
Previous Model ◽  
Crisis Period ◽  
Small Family ◽  
First And Second Generation ◽  
The Impact ◽  
Structured Questionnaire

This chapter refers to small family businesses in Greece and examines the impact of their marketing strategy during an economic crisis period. The research took place in the broad area of Athens between December 2011 and March 2012. Data were collected to form a database of Greek independent private family companies (n=380) using personal interviews (structured questionnaire) with owners/managers of first- and second-generation family businesses. The chapter shows how small family businesses indicate marketing strategy using Carson's model. Limitations of expertise outline the marketing background, which can be described as “self-assisted.” The research offers a verification of a previous model so that problems that arise from companies not putting into practice any marketing concepts can be examined. The significance of the chapter is that there have not formerly been any reviews made about Carson's model in Greece during the economic crisis period emphasizing family businesses.

scholarly journals PISMS: Parental Influence on Student Motivation and Self-esteem in Primary Education

2015 ◽  
Vol 5 (4) ◽  
pp. 165
Author(s):  
Yaron Ghilay ◽  
Ruth Ghilay
Keyword(s):  
Primary School ◽  
Student Learning ◽  
Primary Education ◽  
Student Motivation ◽  
Parental Influence ◽  
Self Esteem ◽  
Previous Model ◽  
Additional Method ◽  
New Model ◽  
Key Variables

<p>The study presents a new model for primary education called PISMS (Parental Influence on Student Motivation and Self-esteem). Previous model named ISMS (Improving Student Motivation and Self-esteem) is designed to help schools foster motivation and self-esteem of students. PISMS is a complementary model because it allows schools to train parents how to become involved and to continue strengthening the mission of the school to improve students' motivation and self-esteem.</p><p>Parents who participated in a three-year study conducted in a primary school (n = 73), reported that a course based on the principles of PISMS, was very helpful in strengthening their ability of how to improve their children's motivation and self-esteem. The significance of these findings is that an additional method for improving key variables having an essential impact on student learning, has been found.</p><p>The PISMS model has been found to be applicable to primary education, in particular, but it may be suitable for other schools as well. </p>

Model-Based Multi-Objective Reinforcement Learning by a Reward Occurrence Probability Vector

2020 ◽  
pp. 269-295
Author(s):  
Tomohiro Yamaguchi ◽  
Shota Nagahama ◽  
Yoshihiro Ichikawa ◽  
Yoshimichi Honma ◽  
Keiki Takadama
Keyword(s):  
Reinforcement Learning ◽  
Experimental Results ◽  
Previous Model ◽  
Pareto Optimal ◽  
Occurrence Probability ◽  
Contrast Model ◽  
Multi Objective ◽  
Model Based ◽  
Model Free ◽  
Optimal Policies

This chapter describes solving multi-objective reinforcement learning (MORL) problems where there are multiple conflicting objectives with unknown weights. Previous model-free MORL methods take large number of calculations to collect a Pareto optimal set for each V/Q-value vector. In contrast, model-based MORL can reduce such a calculation cost than model-free MORLs. However, previous model-based MORL method is for only deterministic environments. To solve them, this chapter proposes a novel model-based MORL method by a reward occurrence probability (ROP) vector with unknown weights. The experimental results are reported under the stochastic learning environments with up to 10 states, 3 actions, and 3 reward rules. The experimental results show that the proposed method collects all Pareto optimal policies, and it took about 214 seconds (10 states, 3 actions, 3 rewards) for total learning time. In future research directions, the ways to speed up methods and how to use non-optimal policies are discussed.

The Mechanics of a Helically Wrapped Thin-Shell Supported by an Externally Pressurized Air Cushion

2002 ◽  
Author(s):  
Sinan Mu¨ftu¨
Keyword(s):  
Steady State ◽  
Thin Shell ◽  
Previous Model ◽  
Fluid Structure Interactions ◽  
Oblique Angle ◽  
Equilibrium Equations ◽  
State Equilibrium ◽  
Air Cushion ◽  
The Web

The mechanics of the fluid structure interactions between a flexible web and an externally pressurized air cushion is modeled. The web is wrapped around the porous cylindrical air-reverser at an oblique angle. The air reverser supplies pressurized air into the web/air-reverser clearance. This model is an extension of a previous model and allows the web to be wrapped around the cylinder in a helical fashion. The geometric relations are based on Rongen’s work (1994) and steady state equilibrium equations are developed based on the work of Mu¨ftu¨ and Cole (1999). This paper describes the theory. A case study is presented.

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