On Reducing Piping Vibration Levels: Attacking the Source

2002 ◽  
Author(s):  
Zheji Liu ◽  
D. Lee Hill ◽  
Roman Motriuk
Keyword(s):  
Noise Level ◽  
Frequency Noise ◽  
Computational Studies ◽  
Acoustic Liners ◽  
Blade Passing Frequency ◽  
The People ◽  
Acoustic Liner ◽  
Structural Failures ◽  
High Level ◽  
Novel Design

Centrifugal compressors used in the pipeline market generate very strong noise, which is typically dominated by the blade passing frequency and its higher harmonics. The high level noise is not only very disturbing to the people living nearby the installation site but also causes expensive structural failures in the downstream piping. A novel design of Helmholtz array has been developed to address this type of noise problem. Computational studies show that the installation of the Helmholtz array acoustic liner on the compressor diffuser walls is very effective in reducing noise level of the compressor, especially the dominant blade passing frequency noise. The acoustic liner design has been built and tested at an installation site by the customer. The data clearly shows that the use of acoustic liners is indeed very effective in the reduction of both the noise and the vibration levels of the machine.

scholarly journals Influence of Interaction with Tangential Lean Blade and Box Type Casing on Blade Passing Frequency Noise Level in Small Axial-Flow Fans

2011 ◽  
Vol 77 (780) ◽  
pp. 1620-1629 ◽  
Author(s):  
Taku IWASE ◽  
Tetsuya HIOKI ◽  
Yoshihiko KATO ◽  
Taro TANNO ◽  
Osamu SEKIGUCHI ◽  
...  
Keyword(s):  
Noise Level ◽  
Axial Flow ◽  
Frequency Noise ◽  
Blade Passing Frequency

scholarly journals Identification of noise level and indication of its impact on residential barrier design in street edge

2020 ◽  
Author(s):  
ARTEKS Jurnal Teknik Arsitektur ◽  
Frengky Benediktus Ola
Keyword(s):  
Human Body ◽  
Noise Level ◽  
Building Design ◽  
Body Parts ◽  
Residential Areas ◽  
The People ◽  
Local Roads ◽  
High Level ◽  
The Impact ◽  
The City

The effect of noises toward human body not only disturb the hearing organs, it can also disturb other human body parts and in some cases may results in reduction of work’s efficiency. This study aims to assess the noise level in residential areas on the edge of the city of Yogyakarta highway and to find any indication of the impact on building design and barriers by homeowners to reduce noise. This research is quantitative associative. Data obtained from measurements and field observations. The results showed that the noise level in residential areas on the edge of the highway, class II street and local roads in the city of Yogyakarta did not meet the standard values of LTNI and LNP. The design of buildings and barriers as a noise reduction factors for the highway was found with a percentage of 100% on the Jalan Bung Tarjo segment, 85.7% on the Jalan Ki Penjawi segment, 20.83% on the Jalan Juminahan segment, 52.08% on the Jalan Bausasran segment, 13.37% on the Jalan Suryodiningratan segment, and 10.7% on the Jalan Mangkuyudan segment. Therefore, the people of Yogyakarta are not fully aware of the high level of road noise.

Evaluation and Prediction of Blade-Passing Frequency Noise Generated by a Centrifugal Blower

1994 ◽  
Author(s):  
Yutaka Ohta ◽  
Elsuke Outa ◽  
Klyohiro Tajima
Keyword(s):  
Frequency Response ◽  
Pressure Fluctuation ◽  
Noise Level ◽  
Noise Source ◽  
Free Field ◽  
Frequency Noise ◽  
Centrifugal Blower ◽  
Density Spectrum ◽  
Blade Passing Frequency ◽  
Field Noise

The blade-passing frequency noise, abbreviated to BPF noise, of low specific speed centrifugal blower is analyzed by separating the frequency-response of the transmission passage and the intensity of the noise source. Frequency-response has previously been evaluated by the authors using a one-dimensional linear wave model, and the results have agreed well with the experimental response in a practical range of the blower speed. In the present study, the intensity of the noise source is estimated by introducing the quasi-steady model of the blade wake impingement on the scroll surface. The effective location of the noise source is determined by analyzing the cross-correlation between measured data of the blower suction noise and pressure fluctuation on the scroll surface. Then, the surface density distribution of a dipole noise source is determined from pressure fluctuation expressed in terms of quasi-steady dynamic pressure of the traveling blade wake. Finally, the free-field noise level is predicted by integrating the density spectrum of the noise source over the effective source area. The sound pressure level of the blower suction noise is easily predicted by multiplying the free-field noise level by the frequency-response characteristics of the noise transmission passage.

Evaluation and Prediction of Blade-Passing Frequency Noise Generated by a Centrifugal Blower

1996 ◽  
Vol 118 (3) ◽  
pp. 597-605 ◽  
Author(s):  
Y. Ohta ◽  
E. Outa ◽  
K. Tajima
Keyword(s):  
Frequency Response ◽  
Pressure Fluctuation ◽  
Noise Level ◽  
Noise Source ◽  
Free Field ◽  
Frequency Noise ◽  
Centrifugal Blower ◽  
Density Spectrum ◽  
Blade Passing Frequency ◽  
Field Noise

The blade-passing frequency noise, abbreviated to BPF noise, of a low-specific-speed centrifugal blower is analyzed by separating the frequency response of the transmission passage and the intensity of the noise source. Frequency response has previously been evaluated by the authors using a one-dimensional linear wave model, and the results have agreed well with the experimental response in a practical range of the blower speed. In the present study, the intensity of the noise source is estimated by introducing the quasi-steady model of the blade wake impingement on the scroll surface. The effective location of the noise source is determined by analyzing the cross-correlation between measured data of the blower suction noise and pressure fluctuation on the scroll surface. Then, the surface density distribution of a dipole noise source is determined from pressure fluctuation expressed in terms of quasi-steady dynamic pressure of the traveling blade wake. Finally, the free-field noise level is predicted by integrating the density spectrum of the noise source over the effective source area. The sound pressure level of the blower suction noise is easily predicted by multiplying the free-field noise level by the frequency-response characteristics of the noise transmission passage.

LADA Synchronization for Symmetric and Asymmetric ATE Test Program Cycles

2019 ◽  
Author(s):  
Arun Kumar Karunanithi ◽  
Joseph Caroselli ◽  
Jason Christensen ◽  
Michell Espitia
Keyword(s):  
Cycle Time ◽  
Dwell Time ◽  
Turnaround Time ◽  
Test Program ◽  
Area Of Interest ◽  
Marginal State ◽  
Structural Failures ◽  
Major Factors ◽  
High Level ◽  
Program Cycle

Abstract Laser Assisted Device Alteration (LADA) or Soft Defect Localization (SDL) is commonly used to root cause device marginality due to functional or structural failures. At a high level, LADA involves setting the device under test (DUT) at its marginal state and using focused near infra-red laser beams to perturb sensitive circuitry [1]. Scanning the focused laser beam over the die can be a long and time-consuming process. In this paper, two LADA cases are presented, which involve a parametric measurement failure while running a dynamic ATE test. Using LADA technique, these two cases were root caused. These two cases also explain how a parametric measurement-based LADA can be setup on ATE, as well as a synchronization method independent of vectors in a pattern. Synchronization was necessitated in the 2nd case due to the asymmetric test program loop, as well as the long test program cycle time. There are many factors which impact LADA turnaround time and it can take anywhere between few seconds to one day. The two major factors are the size of the Area of Interest (AOI) and test program cycle time. Test program cycle time influences the laser “dwell time” for LADA. Dwell time, in simple terms, is the total time the laser is parked at each pixel. The laser can also be synchronized with the test program cycle, keeping the two always in phase. This is explained in Case 2, where LADA synchronization was implemented, and the analysis was successfully completed in time, even though the test cycle time was very long.

Impedance eduction for uniform and multizone acoustic liners

2021 ◽  
pp. 1475472X2110238
Author(s):  
Michael G Jones ◽  
Douglas M Nark ◽  
Brian M Howerton
Keyword(s):  
Impedance Spectra ◽  
International Forum ◽  
Acoustic Liners ◽  
Prony Method ◽  
Research Challenges ◽  
Test Conditions ◽  
Acoustic Liner ◽  
Flow Impedance ◽  
Grazing Flow ◽  
Computationally Expensive

This paper presents results for five uniform and two multizone liners based on data acquired in the NASA Langley Grazing Flow Impedance Tube. Two methods, Prony and CHE, are used to educe the impedance spectra for each of these liners for many test conditions. The Prony method is efficient and generally provides accurate results for uniform liners, but is not well suited for multizone liners. The CHE method supports assessment of both uniform and multizone liners, but is much more computationally expensive. The results from these liners demonstrate the efficacy of both eduction methods, but also clearly demonstrate that sufficient attenuation is required to support accurate impedance eduction. For the liners considered in this study, the data indicate approximately 3 dB attenuation is needed for each zone of a multizone liner in order to ensure quality impedance eduction results. This study was conducted in response to two acoustic liner research challenges in support of a collaboration of multiple national laboratories under the International Forum for Aviation Research.

Love in the High Court: Implications for Indigenous Constitutional Recognition

2021 ◽  
pp. 0067205X2110165
Author(s):  
Shireen Morris
Keyword(s):  
First Nations ◽  
Indigenous Identity ◽  
High Court ◽  
The People ◽  
Australian State ◽  
Proposal A ◽  
Policy Suggestions ◽  
New Race ◽  
High Level ◽  
Policy Incentives

This article considers implications of the recent Love decision in the High Court for the debate about Indigenous constitutional recognition and a First Nations constitutional voice. Conceptually, it considers how the differing judgments reconcile the sui generis position of Indigenous peoples under Australian law with the theoretical ideal of equality—concepts which are in tension both in the judicial reasoning and in constitutional recognition debates. It also discusses the judgments’ limited findings on Indigenous sovereignty, demonstrating the extent to which this is predominantly a political question that cannot be adequately resolved by courts. Surviving First Nations sovereignty can best be recognised and peacefully reconciled with Australian state sovereignty through constitutional reform authorised by Parliament and the people. The article then discusses political ramifications. It argues that allegations of judicial activism enlivened by this case, rather than demonstrating the risks of a First Nations voice, in fact illustrate the foresight of the proposal: a First Nations voice was specifically designed to be non-justiciable and therefore intended to address such concerns. Similarly, objections that this case introduced a new, race-based distinction into the Constitution are misplaced. Such race-based distinctions already exist in the Constitution’s text and operation. The article then briefly offers high-level policy suggestions address two practical issues arising from Love. With respect to the three-part test of Indigenous identity, it suggests a First Nations voice should avoid the unjustly onerous burdens of proof that are perpetuated in some of the reasoning in Love. It also proposes policy incentives to encourage Indigenous non-citizens resident in Australia to seek Australian citizenship, helping to prevent threats of deportation that faced Love and Thoms.

Effects of Diffuser Vane Geometries on Compressor Performance and Noise Characteristics in a Centrifugal Compressor

2013 ◽  
Author(s):  
Yohei Morita ◽  
Nobumichi Fujisawa ◽  
Takashi Goto ◽  
Yutaka Ohta
Keyword(s):  
Centrifugal Compressor ◽  
Noise Level ◽  
Leading Edge ◽  
Broadband Noise ◽  
Frequency Noise ◽  
Numerical Techniques ◽  
Vaned Diffuser ◽  
Noise Characteristics ◽  
Edge Vortex ◽  
Compressor Performance

The effects of the diffuser vane geometries on the compressor performance and noise characteristics of a centrifugal compressor equipped with vaned diffusers were investigated by experiments and numerical techniques. Because we were focusing attention on the geometries of the diffuser vane’s leading edge, diffuser vanes with various leading edge geometries were installed in a vaned diffuser. A tapered diffuser vane with the tapered portion near the leading edge of the diffuser’s hub-side could remarkably reduce both the discrete frequency noise level and broadband noise level. In particular, a hub-side tapered diffuser vane with a taper on only the hub-side could suppress the development of the leading edge vortex (LEV) near the shroud side of the diffuser vane and effectively enhanced the compressor performance.

National Customs and Traditions in the Educational Process for Primary School Students

2020 ◽  
pp. 84-91
Author(s):  
Malik Gabdullin
Keyword(s):  
Cultural Values ◽  
Educational Process ◽  
Educational Institutions ◽  
School Students ◽  
The People ◽  
Social And Economic Development ◽  
Comprehensive Development ◽  
Depth Study ◽  
The Republic ◽  
High Level

The main direction of the educational process is to develop the education system in accordance with the strategic directions of social and economic development of the republic, integrating it into the world educational space, preserving its national essence through the use of national customs and traditions, as well as cultural values, creating conditions for the formation of a personality in the national spirit, development of a high level of outlook and creative potential of the personality, cognitive competences. The implementation of these tasks requires a review of the content of the educational process in the country's schools from a new methodological standpoint, based on the use of elements of national customs and traditions. Such a new methodological system shows the need for radical changes in the traditional educational process, the development of a creative approach to teaching, and the updating of the content of education on a national basis.In the modern period of the development of society in the educational process of educational institutions the principle of education is implemented, taking into account the comprehensive development of students, such a system of education and upbringing provides an opportunity for the formation of cultural and ethnic identity, it is aimed at an in-depth study of the spiritual culture of the people and the ability to connect it with modern values. This system of education and training is based on the link between national customs and traditions (customs and traditions related to children's upbringing, household customs and traditions, social customs and traditions) and the educational process.

Quality assurance and quality control to ensure durability

2021 ◽  
Author(s):  
B. C. Roy ◽  
Tanmoy Guha ◽  
R. Ekambaram
Keyword(s):  
Quality Control ◽  
Quality Assurance ◽  
Service Life ◽  
Performance Standards ◽  
Full Compliance ◽  
Design Build ◽  
Adequate Quality ◽  
Structural Failures ◽  
High Level ◽  
Fundamental Requirement

<p>High level of quality during design, design-build and construction stages is a fundamental requirement to ensure that structure serves its intended purpose. Establishment of a quality assurance manual is prime necessity. Lack of quality control during design, review and approving design drawings are major reasons for structural failures. Designers and design checkers need to work in tandem to ensure more adequate Quality Assurance &amp; Control (QA/QC).</p><p>In structural design Durability is a key parameter and becomes critical for service life of 100/120 years. In design build and construction stages controlling work quality is important to maintain performance standards. Tailor made quality plan for Design-build Contract is essential. Quality procedures, inspection and testing needs implementation in practice to verify full compliance and prevent occurrence of faults and defects towards durability and service life. This paper deals with Quality with special emphasis on durability in design and construction through case studies of design build contracts.</p>

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