Investigation Into the Importance of the Degrees of Freedom for the Characterisation of Structure-Borne Sound Sources: Case Study of a Washing Machine on a Wooden Floor

2011 ◽  
Vol 97 (6) ◽  
pp. 940-948
Author(s):  
Matthias Lievens ◽  
Michael Vorländer
Keyword(s):  
Degrees Of Freedom ◽  
Washing Machine ◽  
Wooden Floor ◽  
Sound Sources

scholarly journals Hybrid Seven-bar Press Mechanism

2018 ◽  
Vol 12 (3) ◽  
pp. 181-187
Author(s):  
M. Erkan Kütük ◽  
L. Canan Dülger
Keyword(s):  
Genetic Algorithm ◽  
Objective Function ◽  
Design Optimization ◽  
Hybrid System ◽  
Degrees Of Freedom ◽  
Dimensional Synthesis ◽  
Design Variables ◽  
Optimization Study ◽  
Metal Stamping

An optimization study with kinetostatic analysis is performed on hybrid seven-bar press mechanism. This study is based on previous studies performed on planar hybrid seven-bar linkage. Dimensional synthesis is performed, and optimum link lengths for the mechanism are found. Optimization study is performed by using genetic algorithm (GA). Genetic Algorithm Toolbox is used with Optimization Toolbox in MATLAB®. The design variables and the constraints are used during design optimization. The objective function is determined and eight precision points are used. A seven-bar linkage system with two degrees of freedom is chosen as an example. Metal stamping operation with a dwell is taken as the case study. Having completed optimization, the kinetostatic analysis is performed. All forces on the links and the crank torques are calculated on the hybrid system with the optimized link lengths

Interface Reduction in Craig-Bampton Component Mode Synthesis by Orthogonal Polynomial Series

2017 ◽  
Author(s):  
Luigi Carassale ◽  
Mirko Maurici
Keyword(s):  
Degrees Of Freedom ◽  
Axial Compressor ◽  
Component Mode Synthesis ◽  
Reduction Techniques ◽  
Interface Reduction ◽  
Reduction Methods ◽  
Interface Displacement ◽  
Polynomial Series ◽  
Efficient Representation

The component mode synthesis based on the Craig-Bampton method has two strong limitations that appear when the number of the interface degrees of freedom is large. First, the reduced-order model obtained is overweighed by many unnecessary degrees of freedom. Second, the reduction step may become extremely time consuming. Several interface reduction techniques addressed successfully the former problem, while the latter remains open. In this paper we tackle this latter problem through a simple interface-reduction technique based on an a-priory choice of the interface modes. An efficient representation of the interface displacement field is achieved adopting a set of orthogonal basis functions determined by the interface geometry. The proposed method is compared with other existing interface reduction methods on a case study regarding a rotor blade of an axial compressor.

scholarly journals Exact Constraint

2009 ◽  
Vol 131 (09) ◽  
pp. 32-36
Author(s):  
James G. Skakoon
Keyword(s):  
Degrees Of Freedom ◽  
Two Dimensions ◽  
Washing Machine ◽  
Design Engineers ◽  
Successful Design ◽  
Tapered Roller ◽  
Tapered Roller Bearings ◽  
Exact Constraint ◽  
Three Degrees Of Freedom

This article discusses the significance of knowing exact constraint in successful design. Although not traditionally taught in mechanical engineering curricula, and not universally known among mechanical engineers, principles of exact constraint have been around for over a century. Designers of precision instruments have for decades used exact constraint, without which they simply would not achieve the precision required by many devices. Exact constraint has a well-developed theory applicable for design engineers. Applying it improves designs by avoiding over-constraint. Over-constrained designs lead to high stresses, tight tolerances, looseness, binding, and difficult assembly. Exact constraint is easier to picture in two dimensions than in three. In two dimensions, there are three degrees of freedom: two translations and one rotation. Some useful compromises to exact constraint are pinned and bolted connections, ball bearings, and tapered roller bearings. Another is in-situ adjustment of over-constraint as in, for example, the thread-adjusted foot pads of a clothes dryer or washing machine.

Comparison of under-actuated and fully-actuated serial robotic arms: a case study

2021 ◽  
pp. 1-13
Author(s):  
Matteo Bottin ◽  
Giulio Rosati
Keyword(s):  
Degrees Of Freedom ◽  
Simple Point ◽  
Controllable System ◽  
Robotic Arms ◽  
Passive Joint ◽  
Final Configuration ◽  
Vibration Behavior ◽  
Rotational Joint ◽  
Point To Point

Abstract Under-actuated robots are very interesting in terms of cost and weight since they can result in a state-controllable system with a number of actuators lower than the number of joints. In this paper, a comparison between an under-actuated planar 3 degrees of freedom (DOF) robot and a comparable fully-actuated 2 degrees of freedom robot is presented, mainly focusing on the performances in terms of trajectories, actuator torques, and vibrations. The under-actuated system is composed of 2 active rotational joints followed by a passive rotational joint equipped with a torsional spring. The fully-actuated robot is inertial equivalent to the under-actuated manipulator: the last link is equal to the sum of the last two links of the under-actuated system. Due to the conditions on the inertia distribution and spring placement, in a simple point-to-point movement the last passive joint starts and ends in a zero-value configuration, so the 3 DOF robot is equivalent, in terms of initial and final configuration, to the 2 DOF fully-actuated robot, thus they can be compared. Results show how while the fully actuated robot is better in terms of reliable trajectory and actuator torques, the under-actuated robot wins in flexibility and vibration behavior.

Piezothermoelasticity and Control of Piezoelectric Laminates Exposed to a Steady-State Temperature Field

1993 ◽  
Author(s):  
H. S. Tzou ◽  
R. Ye
Keyword(s):  
Temperature Field ◽  
Steady State ◽  
Degrees Of Freedom ◽  
Sensors And Actuators ◽  
System Equation ◽  
Thermal Fields ◽  
Steady State Temperature ◽  
And Control ◽  
Internal Degrees Of Freedom

Abstract Piezothermoelastic effects of distributed piezoelectric sensors and actuators are investigated. Vibration control of piezoelectric laminates subjected to a steady-state temperature field is studied. A new 3-D piezothermoelastic finite element with three internal degrees of freedom is formulated using a variational formulation. A system equation for the piezoelectric continuum exposed to combined elastic, electric, and thermal fields is formulated. Distributed sensing and control equations are derived. All these effects are studied in a case study.

Study of grasp-energy based optimal distribution of contact forces on a humanoid robotic hand during object grasp

Robotica ◽  
2021 ◽  
pp. 1-26
Author(s):  
Sourajit Mukherjee ◽  
Abhijit Mahapatra ◽  
Amit Kumar ◽  
Avik Chatterjee
Keyword(s):  
Optimization Algorithm ◽  
Degrees Of Freedom ◽  
Simulated Data ◽  
Performance Measure ◽  
Contact Forces ◽  
Contact Model ◽  
Robotic Hand ◽  
Net Energy ◽  
Optimal Distribution

Abstract A novel grasp optimization algorithm for minimizing the net energy utilized by a five-fingered humanoid robotic hand with twenty degrees of freedom for securing a precise grasp is presented in this study. The algorithm utilizes a compliant contact model with a nonlinear spring and damper system to compute the performance measure, called ‘Grasp Energy’. The measure, subject to constraints, has been minimized to obtain locally optimal cartesian trajectories for securing a grasp. A case study is taken to compare the analytical (applying the optimization algorithm) and the simulated data in MSC.Adams $^{^{\circledR}}$ , to prove the efficacy of the proposed formulation.

A virtual orchestra to qualify the acoustics of historical opera houses

2020 ◽  
Vol 27 (3) ◽  
pp. 235-252 ◽  
Author(s):  
Dario D’Orazio ◽  
Giulia Fratoni ◽  
Anna Rovigatti ◽  
Massimo Garai
Keyword(s):  
18Th Century ◽  
Public Spaces ◽  
Early Age ◽  
Impulse Responses ◽  
Sound Sources ◽  
Social Division ◽  
Subjective Preference ◽  
Acoustic Comfort ◽  
Opera Houses

Italian Historical Opera Houses are private or public spaces built around a cavea, with tiers of boxes on the surrounding walls. At the early age – from 16th to 18th century – boxes were private properties of the richest class, typically the financial responsible of the whole building. The stalls hosted the middle class, that gradually increased its social position and for this reason the wooden seats were progressively replaced by chairs. The gallery was reserved to lower classes. Does this social division correspond to a different acoustic comfort? The present work tries to answer this question using subjective preference models provided by scholars. With this aim, the room criteria defined by different authors and in distinct times are lined up with the ISO 3382 standards and analysed depending on the acoustic peculiarities of an Italian Historical Opera House selected as case study. Calibrated impulse responses were handled through the numerical simulations of a whole orchestra of virtual sound sources in the pit.

Reducing apartment vacancy duration: lessons from affordable housing

2019 ◽  
Vol 37 (3) ◽  
pp. 450-466
Author(s):  
Christina S. Bollo
Keyword(s):  
Affordable Housing ◽  
Mixed Methods Research ◽  
Degrees Of Freedom ◽  
Qualitative Variable ◽  
Content Type ◽  
Non Profit ◽  
Sequential Mixed Methods ◽  
The Usa ◽  
Multiple Variables

Purpose The purpose of this paper is to determine how much variance in vacancy duration can be explained by the architectural attributes of apartments and to illuminate strategies to reduce vacancy duration utilized by non-profit housing providers. Design/methodology/approach This is a sequential mixed methods research study with a qualitative variable-gathering phase followed by a quantitative variable-testing phase. Vacancy duration in days was the dependent variable and the attributes of the apartments were the independent variables. Each building functioned as a separate case, with its own results, and the cases were compared to draw conclusions about the strongest predictors for vacancy duration. Findings Each case study project has a significant linear regression equation with multiple variables contributing to the variance in tenancy duration. The R2 statistic varied for the case study projects from a low of 10.2 percent to a high of 36.9 percent. Factors that resulted in longer vacancies for two or more of the projects include: unit mix, floor level, road proximity and length of tenancy for the tenant moving out. Factors resulting in shorter vacancies include: corner position in the building and relatively larger size of the apartment. Research limitations/implications The geography of the study is limited to Washington State in the USA. However, the case study projects represent three metropolitan statistical areas, with distinct climates and economic conditions. There are limitations to the stepwise analysis method because the degrees of freedom limit the complexity of models that can be estimated. Practical implications This paper highlights influences on vacancy duration and proposes conceptual models for measuring the periods of vacancy duration. Social implications Through this study, architectural contributions to vacancy were uncovered and tested so that subsidized housing, a public good, can be distributed more efficiently. Originality/value This research is the first known study to compare vacancy durations on a unit-by-unit basis.

An Industrial Case Study on Managing Variability with Traceability in Software Product Lines

2015 ◽  
Vol 3 (1) ◽  
pp. 1-15 ◽  
Author(s):  
Taeho Kim ◽  
Sungwon Kang
Keyword(s):  
Product Line ◽  
Washing Machine ◽  
Product Lines ◽  
Industrial Case Study ◽  
Rapid Product Development ◽  
Software Product ◽  
Software Engineers ◽  
Requirement Changes ◽  
Line Engineering

In order to successfully carry out software product line engineering, it is important to manage variability and explicit traceability management of variabilities with development artifacts. Trace links of variability with development artifacts allows software engineers to have rapid product development and reduces maintenance efforts resulting from requirement changes or defect corrections as trace links improve the understandability of their side effects. In this study, the authors present a Variability Tracing Approach (VTA), which consists of variability analysis, variability classification, and variability implementation. The proposed approach is applied to developing the development of a washing machine software platform. This paper describes the results of how a member product can be configured under the proposed VTA.

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