A Critical Review of Passive Noise Control Techniques in Industrial Fans

2013 ◽  
Vol 136 (4) ◽  
Author(s):  
Stefano Bianchi ◽  
Alessandro Corsini ◽  
A.G. Sheard
Keyword(s):  
High Speed ◽  
Noise Control ◽  
Theoretical Research ◽  
Future Research ◽  
Fan Noise ◽  
Acoustic Effect ◽  
Control Techniques ◽  
Current State ◽  
Control Technologies ◽  
Passive Noise

This review aims to assist engineers in understanding and applying passive solutions for reducing industrial fan noise. The paper systematically reviews the extant literature on passive noise techniques, with a particular focus on experimental rather than theoretical research. The review provides an assessment of the current state of the art in industrial fan flow and noise control. It offers a vision for potential improvements in noise reduction via novel application of flow and noise control technologies. The review examines the interaction between aerodynamic cause and acoustic effect and the application of control technologies that current cause and effect theories have inspired. The purpose is to provide a vision for aerodynamics research during the next decade that will serve as a basis for systematically reducing industrial fan noise emissions. The review provides an assessment of recent flow and noise control advances and considers some opportunities for future research. The review reflects an emphasis on low-speed industrial fans. The authors consider high-speed turbomachinery noise control, with the objective of illustrating the linkages between the two technologies. The review concludes with a summary of the opportunities for future research and its application to flow and noise control in industrial fan design.

A Review of Active Noise Control Applications on Noise Barrier in Three-Dimensional/Open Space: Myths and Challenges

2019 ◽  
Vol 18 (04) ◽  
pp. 1930002 ◽  
Author(s):  
Hsiao Mun Lee ◽  
Zhaomeng Wang ◽  
Kian Meng Lim ◽  
Heow Pueh Lee
Keyword(s):  
Open Space ◽  
Noise Control ◽  
Active Noise Control ◽  
Three Dimensional ◽  
Construction Site ◽  
Noise Sources ◽  
Current State ◽  
Active Noise ◽  
Noise Barrier ◽  
Passive Noise

Active noise control (ANC), with counteracting sound in exact equal magnitude and opposite phase to the noise to be controlled, is often considered as a potential solution for solving complex noise problems. However, there are both myths and challenges in its implementations. In a crowded city like Singapore, many noise sources from construction site and subway track are located very close to the residential and commercial buildings. It was suggested by few researchers that by placing suitable control speakers at the construction site (working principle of ANC), the noise from the construction site could be prevented from propagating to the surrounding buildings. Similarly, for viaduct or subway track, by placing control speakers along the viaduct or track, the noise generated by the passing trains or vehicles could be reduced based on the principle of ANC technique. However, implementation of ANC technique on these noise issues is not easy as all of these noise control problems involve multiple noise sources with complex or transient frequency spectrum in large three-dimensional/open space. Therefore, the main intention of the present paper is to discuss the current state of the art of this topic as well as to examine the potential application and limitation of the ANC technique in mitigating unwanted noise, particularly in large three-dimensional/open space and with cooperation of passive noise barrier.

scholarly journals Development of Adaptive Acoustic Impedance Control Technologies of Acoustic Duct Liner

2011 ◽  
Vol 2011 ◽  
pp. 1-14 ◽  
Author(s):  
Hiroshi Kobayashi ◽  
Schunichi Ozaki ◽  
Makoto Yokochi
Keyword(s):  
Noise Reduction ◽  
Acoustic Impedance ◽  
High Speed ◽  
Impedance Control ◽  
Test Facility ◽  
Fan Noise ◽  
Acoustic Liner ◽  
Trial Basis ◽  
Fan Speed ◽  
Control Technologies

This paper describes the development of adaptive acoustic impedance control (AAC) technologies to achieve a larger fan noise reduction, by adaptively adjusting reactance and resistance of the acoustic liner impedance. For the actual proof of the AAC technology III performance, the advanced fan noise absorption control duct liner II was made on trial basis, with the simple control system and the plain device. And, then, the duct liner II was examined for the AAC technology I, II, and III models, using the high speed fan test facility. The test results made clear that the duct liner II of the AAC technology III model could achieve the fan noise reduction higher than O.A. SPL 10 dB (A) at the maximum fan speed 6000 rpm, containing the reduction of fundamental BPF tone of 18 dB and 2nd BPF tone of 10 dB in response to the fan peed change from 3000 to 6000 rpm.

Autonomous Flight

2018 ◽  
Vol 1 (1) ◽  
pp. 29-52 ◽  
Author(s):  
Sarah Tang ◽  
Vijay Kumar
Keyword(s):  
High Speed ◽  
State Of The Art ◽  
Low Cost ◽  
Research Trends ◽  
Multirobot Systems ◽  
Future Research ◽  
Full Vehicle ◽  
Current State ◽  
Tremendous Progress ◽  
New Research

This review surveys the current state of the art in the development of unmanned aerial vehicles, focusing on algorithms for quadrotors. Tremendous progress has been made across both industry and academia, and full vehicle autonomy is now well within reach. We begin by presenting recent successes in control, estimation, and trajectory planning that have enabled agile, high-speed flight using low-cost onboard sensors. We then examine new research trends in learning and multirobot systems and conclude with a discussion of open challenges and directions for future research.

Active and passive noise control in practice on the Saab 2000 high speed turboprop

1998 ◽  
Author(s):  
Urban Emborg ◽  
Fredrik Samuelsson ◽  
Joakim Holmgren ◽  
Siv Leth
Keyword(s):  
High Speed ◽  
Noise Control ◽  
Passive Noise

scholarly journals Sustainability Assessment of Cotton-Based Textile Wet Processing

2019 ◽  
Vol 1 (1) ◽  
pp. 232-246 ◽  
Author(s):  
S M Fijul Kabir ◽  
Samit Chakraborty ◽  
S M Azizul Hoque ◽  
Kavita Mathur
Keyword(s):  
Sustainability Assessment ◽  
Industrial Applications ◽  
Theoretical Research ◽  
Future Research ◽  
Global Business ◽  
Bottom Line ◽  
Current State ◽  
Wet Processing ◽  
State Of Research ◽  
Textile Fabric

The textile and fashion industries account for a significant part of global business. Textile wet processing (TWP) is a crucial stage in textile manufacturing. It imparts aesthetics as well as functional appeal on the textile fabric and ultimate products. Nevertheless, it is considered as one of the most polluting industries and threatens sustainability. There have been different approaches to transform this polluting industry to a sustainable industry. Many researchers have found this challenging, as sustainable, eco-friendly, green or cleaner wet processing might not be always applicable and relevant from the perspective of industrial applications. The present work helps us understand the current state of research of cotton-based textile processes including proposed sustainable approaches. It also examines the achievement of the degree of sustainability of those proposed processes with the lens of the triple bottom line (TBL) framework, identifies existing limitations, and suggests future research scopes that might pave ways for young researchers to learn and undertake new experimental and theoretical research.

The study of terrorist leadership: where do we go from here?

2017 ◽  
Vol 3 (3) ◽  
pp. 208-221 ◽  
Author(s):  
David C. Hofmann
Keyword(s):  
Theoretical Research ◽  
Future Research ◽  
Political Movements ◽  
Critical Approach ◽  
Content Type ◽  
Scholarly Literature ◽  
Current State ◽  
Theoretical Perspectives ◽  
Key Concepts ◽  
Terrorist Groups

Purpose Despite the recognition of the importance of leaders for the formation and ongoing success of social and political movements, the study of leadership in terrorist groups remains underdeveloped. The purpose of this paper, therefore, is to stimulate additional research into terrorist leadership in three main ways: by providing a broad overview of the theoretical perspectives that scholars have used to examine terrorist leadership, by critically reviewing the current state of the academic literature on terrorist leadership, and by presenting various ways in which future research on terrorist leadership can be improved. Design/methodology/approach This paper takes a conceptual and critical approach to reviewing the scholarly literature on terrorist leadership, and draws upon the author’s expertise with the wider multidisciplinary literature on leadership to make methodological and conceptual recommendations to improve related future research. Findings There is a paucity of empirical and theoretical research devoted to understanding important social and strategic aspects of terrorist leadership, and existing scholarly research is largely conducted in isolation with differing methodological and epistemological starting points. This has hampered efforts to measure, operationalize, and understand key concepts involving leadership in terrorist groups. Practical implications This paper provides several methodological and conceptual recommendations by which future research on terrorist leadership can be improved from insights taken from the wider scholarly literature on leadership. By virtue of being published in a criminology journal, this paper helps disseminate and expose key concepts in the study of terrorism to related disciplines. Originality/value This paper provides a general overview of the strengths and weaknesses of the study of terrorist leadership to scholars and students interested in the topic. It provides a foundational discussion of how the current literature on terrorist conceives of and utilizes the concept of leadership. It also provides methodological and conceptual recommendations to improve future research on terrorist leadership.

scholarly journals EEG-Based Control for Upper and Lower Limb Exoskeletons and Prostheses: A Systematic Review

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3342 ◽  
Author(s):  
Maged AL-Quraishi ◽  
Irraivan Elamvazuthi ◽  
Siti Daud ◽  
S. Parasuraman ◽  
Alberto Borboni
Keyword(s):  
State Of The Art ◽  
Human Motion ◽  
Assistive Devices ◽  
Future Research ◽  
Eeg Signals ◽  
Control Techniques ◽  
The Third ◽  
Current State ◽  
Rehabilitation Devices ◽  
State Of Research

Electroencephalography (EEG) signals have great impact on the development of assistive rehabilitation devices. These signals are used as a popular tool to investigate the functions and the behavior of the human motion in recent research. The study of EEG-based control of assistive devices is still in early stages. Although the EEG-based control of assistive devices has attracted a considerable level of attention over the last few years, few studies have been carried out to systematically review these studies, as a means of offering researchers and experts a comprehensive summary of the present, state-of-the-art EEG-based control techniques used for assistive technology. Therefore, this research has three main goals. The first aim is to systematically gather, summarize, evaluate and synthesize information regarding the accuracy and the value of previous research published in the literature between 2011 and 2018. The second goal is to extensively report on the holistic, experimental outcomes of this domain in relation to current research. It is systematically performed to provide a wealthy image and grounded evidence of the current state of research covering EEG-based control for assistive rehabilitation devices to all the experts and scientists. The third goal is to recognize the gap of knowledge that demands further investigation and to recommend directions for future research in this area.

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