scholarly journals Measurement of the Hissing-Type Noise and Vibration of the Automotive HVAC System

2018 ◽  
Vol 217 ◽  
pp. 03002
Author(s):  
Muhammad Abdul Rahman Paiman ◽  
Ahmad Zhafran Ahmad Mazlan ◽  
Muhammad Hidayat Hamdan ◽  
Mohamad Syazwan Md. Isa ◽  
Sharum Man ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Common Type ◽  
Operating Conditions ◽  
Noise Measurement ◽  
Hvac System ◽  
Frequency Range ◽  
Noise And Vibration ◽  
Root Cause ◽  
Expansion Valve ◽  
The Common

Noises such as hissing, humming, air-rush and compressor engagement are the common type of noises that can be induced from the automotive heating and ventilating air conditional (HVAC) system. These noises are basically generated from the effects of vibrational HVAC components. Due to this, the root cause of the noises has to be investigated for any implementation of solution. In this study, the hissing-type of noise is taken into consideration whereby the noise and vibration are measured from various HVAC components such as Evaporator Inlet and Outlet and Thermal Expansion Valve (TXV). Three types of measurement sensors are used in this study which is tri-axial accelerometer for the vibration, tachometer for the engine rpm tracking and microphone for the noise measurement. Two types of operating conditions are taken into consideration, when engine running at 850 rpm (idle) and 850-3000 rpm (tracking) conditions and a constant blower speed is applied for both conditions. the result shows that, the hissing type of noise is determined at the frequency range of 4500-5000 Hz for the both idle and running conditions, whereby the vibration at the Evaporator Inlet is the most significant compared to the Evaporator Core and TVX components. the vibration of the Evaporator Inlet shows the drastic vibration increment between 1000-1500 rpm and getting worse towards 3000 rpm. This result is validated with the 3D colour of noise waterfall analysis, whereby the hissing noise shows the dominant result in the frequency range of 4500-5000 Hz.

Characterisation of the Humming-Type Noise and Vibration of the Automotive HVAC System

2019 ◽  
Vol 16 (2) ◽  
pp. 6634-6648
Author(s):  
A. Z. A. Mazlan ◽  
M. H. A. Satar ◽  
M. H. Hamdan ◽  
M. S. Md. Isa ◽  
S. Man ◽  
...  
Keyword(s):  
Vibration Characteristics ◽  
Operating Conditions ◽  
Hvac System ◽  
Frequency Range ◽  
Noise And Vibration ◽  
Power Steering ◽  
Pump Compressor

The automotive heating and ventilating air condition (HVAC) system, when vibrating, can generate various types of noises such as humming, hissing, clicking and air-rushes. These noises can be characterised to determine their root causes. In this study, the humming-type noise is taken into consideration whereby the noise and vibration characteristics are measured from various HVAC components such as power steering pump, compressor and air conditional pipe. Four types of measurement sensors were used in this study - tachometer for rpm tracking; accelerometer for the vibration microphone for the noise; and sound camera for the visualization measurement. Two types of operating conditions were taken into consideration - they were “idle” (850 rpm) and “running” (850-1400 rpm) conditions. A constant blower speed was applied for both conditions. The result shows that the humming noises can be determined at the frequency range of 300-350 Hz and 150-250 Hz for both idle and running conditions, respectively. The vibration of the power steering pump shows the worst acceleration of 1.8 m/s2 at the frequency range of 150-250 Hz, compared to the compressor and air conditional pipe. This result was validated with the 3D colour order and sound camera analyses, in which the humming noise colour mapping shows dominance in this frequency range.  

Validation of Clicking-type Noise and Vibration in Automotive HVAC System

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
M.H.A. Satar ◽  
A. Z. A. Mazlan ◽  
M.H. Hamdan ◽  
M.S. Md. Isa ◽  
M.A.R. Paiman ◽  
...  
Keyword(s):  
Scale Model ◽  
Hvac System ◽  
Frequency Range ◽  
Similar Frequency ◽  
Noise And Vibration ◽  
System A ◽  
Vehicle System ◽  
Operating Frequency Range ◽  
Expansion Valve ◽  
Good Agreement

In this study, the characteristics of clicking-type noise and vibration occurring in the automotive heating, ventilation and air conditional (HVAC) systems are investigated. A lab-scale model of HVAC system is developed, and validation is carried out with a vehicle system. A fixed blower speed of 1 (at an airflow of 2.53 m/s) with alternated air conditional (AC) was implied in this study. Three different sensors namely as tachometer, accelerometer, and microphone were used to measure and prove the existing noise in the HVAC system. The study inferred that the compressor contributed significantly to the total vibration and noise in the HVAC system. Other components such as AC pipe, evaporator, and thermal expansion valve (TXV) also contributed to a slight extent. The clicking noise was observed in the operating frequency range of 200 ~ 300 Hz. This noise and vibration issues are partly influenced by the running conditions of the AC and the effect was significant when the AC was turned on. The validation of the findings in the model shows a good agreement with the results obtained in the vehicle system, whereby the clicking noise and vibration can be observed at a similar frequency range.

Quantification of aerodynamically induced noise and vibration-induced noise in a suction unit

2011 ◽  
Vol 225 (3) ◽  
pp. 617-624 ◽  
Author(s):  
J Prezelj ◽  
M Čudina
Keyword(s):  
Transfer Function ◽  
Noise Reduction ◽  
Noise Source ◽  
Operating Conditions ◽  
Frequency Range ◽  
Centrifugal Blower ◽  
Noise Sources ◽  
Noise And Vibration ◽  
Different Types ◽  
The Individual

Noise, generated by a centrifugal blower, can be divided according to its origin, into aerodynamically induced noise and vibration-induced noise. The contribution of the individual noise source to the total emitted noise is hard to determine, but it is crucial for the design of noise reduction measures. In order to reduce the noise of the centrifugal blower in a broad range of operating conditions, an identification of noise sources needs to be performed. An analysis of the most important noise origin in a centrifugal blower presented in this article was performed by measurements of the transfer function between noise and vibration, under different types of excitation. From the analyses one can conclude that the dominant noise source of a centrifugal blower can be attributed to the aerodynamically generated noise which exceeds the vibration-induced noise for more than 10 dB in a broad frequency range.

Pseudo-Dynamic Fault Isolation Technique Using Backside Emission Microscopy – Case Study, Where All Other Methods Fail

2002 ◽  
Author(s):  
Yoav Weizman ◽  
Ezra Baruch ◽  
Michael Zimin
Keyword(s):  
Failure Analysis ◽  
Process Variations ◽  
Fault Isolation ◽  
Operating Conditions ◽  
Detection Sensitivity ◽  
Isolation Technique ◽  
Root Cause ◽  
Emission Microscopy ◽  
Failure Location ◽  
Noisy Background

Abstract Emission microscopy is usually implemented for static operating conditions of the DUT. Under dynamic operation it is nearly impossible to identify a failure out of the noisy background. In this paper we describe a simple technique that could be used in cases where the temporal location of the failure was identified however the physical location is not known or partially known. The technique was originally introduced to investigate IDDq failures (1) in order to investigate timing related issues with automated tester equipment. Ishii et al (2) improved the technique and coupled an emission microscope to the tester for functional failure analysis of DRAMs and logic LSIs. Using consecutive step-by-step tester halting coupled to a sensitive emission microscope, one is able detect the failure while it occurs. We will describe a failure analysis case in which marginal design and process variations combined to create contention at certain logic states. Since the failure occurred arbitrarily, the use of the traditional LVP, that requires a stable failure, misled the analysts. Furthermore, even if we used advanced tools as PICA, which was actually designed to locate such failures, we believe that there would have been little chance of observing the failure since the failure appeared only below 1.3V where the PICA tool has diminished photon detection sensitivity. For this case the step-by-step halting technique helped to isolate the failure location after a short round of measurements. With the use of logic simulations, the root cause of the failure was clear once the failing gate was known.

Busting Myths in Compound Handling Practices for Assay Developers

2021 ◽  
pp. 247263032110233
Author(s):  
Rosalia Gonzales ◽  
Travis Mathewson ◽  
Jefferson Chin ◽  
Holly McKeith ◽  
Lane Milde ◽  
...  
Keyword(s):  
The Other ◽  
Common Goal ◽  
Collaborative Relationship ◽  
Sample Handling ◽  
Root Cause ◽  
The Common ◽  
Recommended Practices ◽  
Handling Practices ◽  
The One

Since the advent of modern-day screening collections in the early 2000s, various aspects of our knowledge of good handling practices have continued to evolve. Some early practices, however, continue to prevail due to the absence of defining data that would bust the myths of tradition. The lack of defining data leads to a gap between plate-based screeners, on the one hand, and compound sample handling groups, on the other, with the latter being the default party to blame when an assay goes awry. In this paper, we highlight recommended practices that ensure sample integrity and present myth busting data that can help determine the root cause of an assay gone bad. We show how a strong and collaborative relationship between screening and sample handling groups is the better state that leads to the accomplishment of the common goal of finding breakthrough medicines.

Molecular characterization and antimicrobial susceptibility patterns of Clostridium difficile strains isolated from hospitals in south-east Scotland

2007 ◽  
Vol 56 (7) ◽  
pp. 921-929 ◽  
Author(s):  
Esvet Mutlu ◽  
Allison J. Wroe ◽  
Karla Sanchez-Hurtado ◽  
Jon S. Brazier ◽  
Ian R. Poxton
Keyword(s):  
Antibiotic Resistance ◽  
Clostridium Difficile ◽  
Restriction Analysis ◽  
Common Type ◽  
Resistance Pattern ◽  
Binary Toxin ◽  
Resistance Patterns ◽  
The Common ◽  
Antibiotic Resistance Patterns ◽  
Susceptibility Patterns

Clostridium difficile isolates (n=149) collected in south-east Scotland between August and October 2005 were typed by four different methods and their susceptibility to seven different antibiotics was determined. The aims were to define the types of strain occurring in this region and to determine whether there were any clonal relationships among them with respect to genotype and antibiotic resistance pattern. Ribotyping revealed that 001 was the most common type (n=113, 75.8 %), followed by ribotype 106 (12 isolates, 8.1 %). The majority of the isolates (96.6 %, n=144) were of toxinotype 0, with two toxinotype V isolates and single isolates of toxinotypes I, IV and XIII. PCR and restriction analysis of the fliC gene from 147 isolates gave two restriction patterns: 145 of pattern VII and two of pattern I. Binary toxin genes were detected in only three isolates: two isolates of ribotype 126, toxinotype V, and one isolate of ribotype 023, toxinotype IV. S-types showed more variation, with 64.5 % (n=40) of the common S-type (4939) and 21 % (n=13) of S-type 4741, with six other S-types (one to three isolates each). All ribotype 001 isolates were of the same S-type (4939), with three isolates of other ribotypes being this S-type. No resistance was found to metronidazole or vancomycin, with resistance to tetracycline only found in 4.3 % of the isolates. A high proportion of isolates were resistant to clindamycin (62.9 %), moxifloxacin, ceftriaxone (both 87.1 %) and erythromycin (94.8 %). Resistance to three antibiotics (erythromycin, clindamycin and ceftriaxone) was seen in 66 isolates, with erythromycin, ceftriaxone and moxifloxacin resistance seen in 96 isolates. Resistance to all four of these antibiotics was found in 62 isolates and resistance to five (the above plus tetracycline) in one isolate: a ribotype 001, toxinotype 0 strain. Whilst ribotype 001 was the most commonly encountered type, there was no evidence of clonal relationships when all other typing and antibiotic resistance patterns were taken into account.

Risks of Using Statistical Analysis Tools in Project Management Environments

2020 ◽  
Vol 7 (2) ◽  
pp. 1-19
Author(s):  
Brian J. Galli
Keyword(s):  
Risk Management ◽  
Project Management ◽  
Statistical Analysis ◽  
Common Type ◽  
Systematic Search ◽  
Statistical Tools ◽  
Early Stages ◽  
Analysis Tools ◽  
The Common ◽  
The Relationship

The purpose of this study is to examine the risks of using statistical tools in a project basis. A systematic search of certain academic databases has been conducted for this study. Statistical tools could be used in a project, and they should be properly planned and designed. Statistical tools include major activities, such as collecting and analyzing data, providing meaningful interpretation, and reporting findings. When dealing with statistical tools, there are several risks that may exist and impact the project either positively or negatively. This study covers a brief outline of the risk management, statistical tools, and the relationship between the two concepts. Finally, a discussion of the common type of risks that are initiated by using statistical analysis tools are provided, which could be planned, identified, and analyzed in the early stages of the project.

Natural Convection in an Enclosure With Blend of Micro Encapsulated Phase Change Materials

2013 ◽  
Author(s):  
Yasmin Khakpour ◽  
Jamal Seyed-Yagoobi
Keyword(s):  
Heat Transfer ◽  
Thermal Expansion ◽  
Natural Convection ◽  
Phase Change ◽  
Latent Heat ◽  
Phase Change Materials ◽  
Numerical Study ◽  
Pure Water ◽  
Operating Conditions ◽  
Effective Density

This numerical study investigates the effect of using a blend of micro-encapsulated phase change materials (MEPCMs) on the heat transfer characteristics of a liquid in a rectangular enclosure driven by natural convection. A comparison has been made between the cases of using single component MEPCM slurry and a blend of two-component MEPCM slurry. The natural convection is generated by the temperature difference between two vertical walls of the enclosure maintained at constant temperatures. Each of the two phase change materials store latent heat at a specific range of temperatures. During phase change of the PCM, the effective density of the slurry varies. This results in thermal expansion and hence a buoyancy driven flow. The effects of MEPCM concentration in the slurry and changes in the operating conditions such as the wall temperatures compared to that of pure water have been studied. The MEPCM latent heat and the increased volumetric thermal expansion coefficient during phase change of the MEPCM play a major role in this heat transfer augmentation.

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