One Stage and Two Stage Vibration Isolators as Applied to High Speed Textile Spindles to Achieve Noise Reduction

1978 ◽  
Vol 100 (1) ◽  
pp. 33-40 ◽  
Author(s):  
L. W. Foster
Keyword(s):  
Low Noise ◽  
Single Stage ◽  
Sound Power ◽  
Octave Band ◽  
Noise Levels ◽  
Two Stage ◽  
Noise And Vibration ◽  
Vibration Isolators ◽  
One Stage ◽  
The Impact

The operation of ring spinning frames in textile mills can create spinning room noise levels of 90 to 95 dBA. The spindle bobbin mechanisms (generally 300 to 400 per machine) which are operated at spindle speeds of 6,000 to 14,000 rpm are major sources of noise in this type of machinery. The rotating unbalance force in the spindle-bobbin mechanism creates high frequency vibrations in the spindle blade and in the spindle bolster which contains the bearings on which the blade rotates. The vibrations generated by the spindle bobbin mechanism and the bearings are transmitted through the spindle bolster to the rail structure of the spinning frame where they cause sand energy to be radiated. This paper describes the use of two types of elastomeric vibration isolators located between the spindle bolster and the rail to achieve reductions of vibration and noise levels associated with the spindle-bobbin-rail subsystem of spinning frames. The two types of elastomeric isolators employed are: (1) a single-stage isolator where a bonded elastomeric mounting of annular design is placed between the bolster and the rail, and (2) a two-stage isolator which incorporates an annular intermediate mass element between two annular elastomeric sections that provide the interfaces to the spindle and to the rail. The two stage isolator is a novel design for rotating spindle type applications and employs the classical two stage isolator principle to achieve greater attenuation of vibrations. While it has been known for some time that single stage elastomeric isolators provide an effective means of reducing vibrations and noise in textile spinning and twisting machines, recent emphasis on reducing machine noise levels has motivated increased effort to better describe and apply elastomeric isolators. The two-stage isolator concept has been employed in an attempt to achieve higher operating speeds and, therefore, higher productivity while keeping noise levels within acceptable limits. In order to demonstrate the degrees of noise and vibration reductions that can be attained using the two types of isolators in comparison with the non-isolated or hard-mounted spindle, tests were performed using a single oil base type spinning spindle with a full bobbin. The spindle-bobbin mechanism was mounted to a representative rail by the three mounting methods described previously and operated at speeds of 11,000 rpm and 14,000 rpm in a reverberation room. Octave band sound power level measurements and one-tenth octave band sound pressure measurements were made to compare the performance of the mounting methods. These measurements were made using six microphones at different locations and sampling their output signals at a high rate over an extended interval of time. One-tenth octave horizontal and vertical rail acceleration responses were obtained concurrently with the noise responses. These noise and vibration responses are presented and discussed in the paper. The results show that the elastomeric isolators provide significant reductions in rail vibration response levels in the spindle bearing vibration frequency range of 500 to 2000 Hz. The corresponding overall sound power levels for the two operating speeds when using one stage isolators were 8 to 18 dBA below the hard-mounted spindle condition. When using the two-stage isolator, the overall sound power levels for the two operating speeds were 9 and 20 dBA below the hard mounted spindle condition. The results demonstrate the importance of properly designing the mounting to tune the system for low noise responses while minimizing the impact on other operatonal criteria such as spindle static deflection and dynamic motion. A discussion of the isolator design parameter trade-offs is presented along with comments regarding the limitations of the testing and the constraints involved in predicting the noise level reduction to be expected for a whole spinning frame.

Blow-Down Valve Noise and Interactions With Downstream Orifice Plates

2003 ◽  
Author(s):  
Denis G. Karczub ◽  
Fred W. Catron ◽  
Allen C. Fagerlund
Keyword(s):  
Noise Exposure ◽  
Control Valve ◽  
Low Noise ◽  
Noise Levels ◽  
Exposure Limits ◽  
Blow Down ◽  
Gas Processing ◽  
The Impact ◽  
Acoustic Fatigue ◽  
Infrequent Event

In a blow-down situation as might occur at a natural gas processing facility, noise levels are very high and significantly exceed the noise levels one would normally associate with a control valve. As the blow-down operation is an infrequent event, this may be permissible but requires consideration of the duration of these high noise levels to ensure that occupational noise exposure limits and acoustic fatigue limits are not exceeded. Tests of noise levels due to an 8-inch control valve in a 12-inch pipeline under blow-down conditions are compared here with noise level predictions based on the IEC standard. Consideration is also given to the impact of placing an orifice plate downstream of the control valve as is often done to reduce pressure drop across the valve in the expectation that control valve noise levels will be reduced. Simple orifice plates often installed by plant operators to achieve this goal are shown to have an adverse impact, and it is shown that a multi-hole diffuser or low-noise control valve should instead be used.

Springs® Design Optimized By Seawater Quality. Laboratory Pilot Tests

2021 ◽  
Author(s):  
Pierre Pedenaud ◽  
Marianna Rondon ◽  
Nicolas Lesage ◽  
Eric Tournis ◽  
Riccardo Giolo ◽  
...  
Keyword(s):  
Water Quality ◽  
Operating Conditions ◽  
Single Stage ◽  
Plant Performance ◽  
Future Application ◽  
Feed Water ◽  
Nanofiltration Membranes ◽  
Two Stage ◽  
Seawater Quality ◽  
The Impact

Abstract A new seawater laboratory pilot has been installed in order to evaluate the impact of the seawater quality on the performance of nanofiltration membranes and filters. The test program implemented was designed to produce the data required to optimize the design and operating parameters of a subsea sulfate removal plant, particularly with respect to the technology developed by Total, Saipem and Veolia, co-owners of the development. The equipment qualification plan is approaching completion with the development of subsea barrier-fluidless pumps, all-electric control systems, high-cycling valves operated by electric actuators and subsea water analyzers. This presented pilot laboratory study completes this plan. Nanofiltration membranes are commonly used to remove the sulfates found in seawater before the water is injected into wells. The principal advantages of relocating this equipment from topside to subsea are better reservoir sweep control, a substantial subsea water injection network reduction and savings on space and weight on the topsides deck. The move to subsea offers the opportunity to simplify the process due to improved deep water quality. This was previously demonstrated through a subsea test campaign. This new pilot study provides data both on the performance of a plant operating with different feed water quality and on the success of operating changes to further optimize the plant performance. The pilot has been installed at the Palavas-les-Flots site in France. Raw water collected from the basin was mixed with ultra-filtered water in order to calibrate the feed water quality. The pilot includes a two stage nanofiltration configuration and single stage nanofiltration unit. The two stage configuration was used to produce data for operation across an array of feed water quality and plant operating conditions. The single stage unit was used to produce data on membrane fouling over a long operating duration. Results from these tests and discussion on how this data relates to subsea plant performance shall be presented. This innovative approach enables a wide range of subsea water quality to be simulated and tested against different process configurations of the subsea unit. Indeed, for each industrial subsea application, the raw seawater quality is dependent on both the region and the depth of the seawater inlet. With this experimental data acquisition campaign and understanding of the seawater quality at inlet, the system design can be tailor-made for each future application case.

Work-related road safety: The impact of the low noise levels produced by electric vehicles according to experienced drivers

2020 ◽  
Vol 121 ◽  
pp. 580-588 ◽  
Author(s):  
María del Carmen Pardo-Ferreira ◽  
Juan Carlos Rubio-Romero ◽  
Fuensanta Carmen Galindo-Reyes ◽  
Antonio Lopez-Arquillos
Keyword(s):  
Electric Vehicles ◽  
Road Safety ◽  
Low Noise ◽  
Noise Levels ◽  
Work Related ◽  
The Impact

scholarly journals The Impact of Thin Asphalt Layers as a Road Traffic Noise Intervention in an Urban Environment

2021 ◽  
Vol 13 (22) ◽  
pp. 12561
Author(s):  
Ablenya Grangeiro de Barros ◽  
Jarl K. Kampen ◽  
Cedric Vuye
Keyword(s):  
Noise Exposure ◽  
Road Traffic ◽  
Traffic Noise ◽  
Low Noise ◽  
Urban Environments ◽  
Comfort Level ◽  
Road Traffic Noise ◽  
Acoustic Measurements ◽  
Noise Levels ◽  
The Impact

Low-noise thin asphalt layers (TALs) are a feasible solution to mitigate road traffic noise in urban environments. Nevertheless, the impacts of this type of noise intervention are reported mostly regarding noise levels, while non-acoustic aspects influencing the population perception are still little-known. This study investigates the implementation of TALs in two streets of Antwerp, Belgium. The effectiveness of the intervention was measured via noise modelling and acoustic measurements of road traffic noise. A reduction of 2.8 dB in noise exposure was observed in Lden and Lnight, while SPB measurements showed decreases up to 5.2 dB on the roadside. The subjective impacts of the TALs were evaluated via self-administered surveys and compared to results from control streets. The annoyance indicators were positively impacted by the TALs implementation, resulting in annoyance levels similar or lower than in the control streets. The TALs did not impact the reported physical complaints, sleep quality, and comfort level to perform activities.

scholarly journals Behavior of Magneto-Rheological Fluids Subject to Impact and Shock Loading

Aerospace ◽  
2003 ◽  
Author(s):  
James A. Norris ◽  
Mehdi Ahmadian
Keyword(s):  
Peak Force ◽  
Single Stage ◽  
Drop Tower ◽  
Two Stage ◽  
Mr Fluid ◽  
Drop Mass ◽  
Fluid Properties ◽  
Supply Current ◽  
Magneto Rheological ◽  
The Impact

Investigations on the design of controllable magneto-rheological (MR) fluid devices have focused heavily on low velocity and frequency applications. The extensive work in this area has led to a good understanding of MR fluid properties at low velocities and frequencies. However, the issues concerning MR fluid behavior in impact and shock applications are relatively unknown. To investigate MR fluid properties in this regime, a drop-tower was developed to subject MR fluid dampers to impulsive loads. The drop-tower design uses a guided drop-mass, which is released from variable heights to achieve different impact energies. The nominal drop-mass is 55 lb and additional weight may be added to reach a maximum of 500 lb. The nominal drop-mass of 55 lb was used throughout this study. Five drop-heights were investigated, 12, 24, 48, 72 and 96 inches, corresponding to impact velocities of 86, 127, 182, 224 and 260 in/s. Two fundamental MR damper configurations were tested, a single-stage, double-ended piston and a two-stage, mono-tube with nitrogen accumulator. Both dampers operate in the valve flow mode and contain MRF-128 TD fluid from Lord Corporation. The results indicate that the two damper configurations exhibit different force-displacement characteristics during impulsive loading. For the single-stage, double-ended damper, the peak force occurs close to the beginning of the impact. Conversely, the two-stage, mono-tube damper does not reach the peak force until after the nitrogen accumulator bottoms out. To verify this behavior, a theoretical model of the accumulator is derived and compared to the experimental data. The results also show that for a given impact velocity, the peak force does not depend on the current supplied to the damper. Since increasing the supply current causes an increase in the apparent yield stress, it was anticipated that the peak force would depend on the supply current as well. This disagreement is hypothesized to be the result of the fluid inertia preventing the fluid from accelerating fast enough to accommodate the rapid piston displacement. Thus, the peak force is primarily attributed to fluid compression, rather than the resistance to flow associated with the fluid passing through the magnetic field. It is important to note that this study is in its early stages and only preliminary conclusions are presented. Follow up publications will include additional results and modeling, and attempt to relate device design and MR fluid properties to dynamic behavior.

Cephalometric and Occlusal outcome in Adults with Unilateral Cleft Lip, Palate, and Alveolus after Two Different Surgical Techniques

2003 ◽  
Vol 40 (3) ◽  
pp. 249-255 ◽  
Author(s):  
Alexander Gaggl ◽  
Matthias Feichtinger ◽  
Günter Schultes ◽  
Gert Santler ◽  
Margit Pichlmaier ◽  
...  
Keyword(s):  
Cleft Lip ◽  
Surgical Techniques ◽  
Single Stage ◽  
Long Term Results ◽  
Two Stage ◽  
Anterior Maxilla ◽  
One Stage ◽  
Cleft Lip Palate ◽  
The One ◽  
Molar Region

Objective To assess differences in the aesthetic and functional long-term results of one-stage and two-stage surgical and orthodontic treatment in patients with cleft lip, palate, and alveolus. Design Sixty adult patients who were operated on as children for unilateral cleft lip, palate, and alveolus were examined. In every patient the lip was closed using Tennison's technique. Thirty patients had soft and hard palate closure in two stages and 30 patients in a single stage. Lateral cephalometric and model analyses were conducted at a mean age of 18.4 years. Results In the model analysis, transverse narrowing was seen in all patients after two-stage operations and in three patients after one-stage operations. The deficit was more severe in the molar region in the two-stage group and nearly similar in the premolar and molar region in the one-stage group. A sagittal deficiency in the anterior maxilla was found in 26 patients after two-stage operations and in 16 patients after one-stage operations. In the lateral cephalometric analysis, the mean sella-nasion-point A angle in the one- and two-stage group was 78.2 degrees and 76.8 degrees, respectively. The ANB angle was normal in both groups. In both groups the inclination of the midface was low. There was a low posterior facial height. Minor scarring was seen in the single-stage group. Conclusion A more severe impairment of growth of the maxilla in the sagittal and frontal plane was observed after two-stage operations on the cleft palate.

scholarly journals An Assessment of the Impact of Helicopter Noise: Case Study of Mgbuoshimini Community Nigeria

2020 ◽  
pp. 1-16
Author(s):  
OF Orikpete ◽  
◽  
DRE Ewim ◽  
Keyword(s):  
Background Noise ◽  
Low Noise ◽  
Sound Level ◽  
Residential Areas ◽  
Noise Levels ◽  
Commercial Aviation ◽  
High Noise ◽  
Statistical Measures ◽  
Level Meter ◽  
The Impact

With the projected growth in demand for commercial aviation, it is anticipated that there will be an increased environmental impact associated with noise, air quality, and climate change. Against this backdrop, the noise levels experienced by the residents of Mgbuoshimini Community due to helicopters takeoff and landing were studied. The study was carried out for 14 days at three different locations using a Class 2 Optimus sound level meter from 7am to 5pm daily. Analysis involved the equivalent noise levels, statistical measures for the background noise, aircraft flyover noise as well as the Noise Gap Index (NGI) . It was found that the equivalent noise levels of the background noise and aircraft flyover noise range from 67.7 dBA to 72.4 dBA and 88.4 dBA to 88.6 dBA respectively. The peak background noise and aircraft flyover noise ranged from 69.17 dBA to 79 dBA and 93.2 dBA to 94.8 dBA respectively. These values exceeded the recommended value of 60 dBA for residential areas. Two models to determine the NGI for both low noise areas and high noise areas were developed. A correlation coefficient of 0.70 and 0.88 were obtained between the actual and predicted values of NGI for both low and high noise areas. Therefore, it is recommended that buildings should be adequately insulated by use of noise-absorbing materials. Furthermore, environmentally friendly (quieter) aircrafts should be used by the airline company operating in that area

Aerodynamic Design and Assessment of a Compact, Single Stage Axial Fan for Low Noise Emission

2019 ◽  
Author(s):  
Daniel Kessler ◽  
Daniel Giesecke ◽  
Jens Friedrichs ◽  
Jörg Leuschner
Keyword(s):  
Axial Length ◽  
Static Pressure ◽  
Test Chamber ◽  
Low Noise ◽  
Single Stage ◽  
Test Facility ◽  
Axial Fan ◽  
Noise Emission ◽  
Cooling Systems ◽  
The Impact

Abstract Axial fans used in automotive and especially in locomotive cooling systems have to follow several, partially contrary specifications. In addition to geometrical and aerodynamic specifications, acoustic limits must be taken into account for new fan stage designs. Legislation will tweak axial fan requirements in the future further and further to lower their noise emission and maximize their efficiency. The main focus of this paper is to design and test a single stage axial fan for locomotive cooling systems with high aerodynamic efficiency and low noise emissions. The fan stage is designed to be installed in a so-called tower construction. The available construction space is limited. Therefore, special attention is paid to reduce the axial length. Extensive blade sweep and dihedral are implemented in the design process. The fan stage design is validated by experimental tests including aerodynamic and acoustic studies. During the aerodynamic studies, it was found that an often used approximation about the static pressure downstream the fan cannot be applied. Downstream the fan stage no further components are installed. Therefore, the static pressure at this position must be approximated. An alternative approach is developed using the results of additional studies including a downstream pipe and scaling factors. The results of the approach are plausible. The acoustic tests were carried out at a fan test facility at TU Braunschweig. To evaluate the impact of the halls acoustic repercussion on the test results, different tests were done. Additionally, another axial fan was tested which has been investigated a few years ago in an acoustic test chamber. The studies show the positive effect of the design methodology on aerodynamic and acoustic of the fan stage. All requirements were achieved as well as a reduction of the axial length of the fan stage.

scholarly journals Evaluation of Building Construction-Induced Noise and Vibration Impact on Residents

2020 ◽  
Vol 12 (4) ◽  
pp. 1579 ◽  
Author(s):  
Chao Zou ◽  
Ruijun Zhu ◽  
Ziyu Tao ◽  
Daiqiao Ouyang ◽  
Yekai Chen
Keyword(s):  
Objective Evaluation ◽  
Building Construction ◽  
Construction Site ◽  
Noise Levels ◽  
Dose Response Relationship ◽  
Noise And Vibration ◽  
Community Environment ◽  
Psychological Capacity ◽  
Vibration Impact ◽  
The Impact

Environmental noise and vibration induced by building construction are increasingly prominent in daily life. If the noise and vibration level exceeds the corresponding standard limits stipulated by the country, humans’ normal life, working, or studying efficiency would be interfered. This paper aims to explore how residents respond to noise and vibration mainly induced by the building construction. The noise and vibration measurements, as well as a questionnaire survey, were conducted. Through analysis and comparisons, it is shown that the noise impacts were concentrated in the area near the construction site. For the noise and vibration transmission within the building, the noise levels were amplified in the lower floors and gradually attenuated with floors, and the vibration levels decayed with the floors. The noise impact was much greater than the vibration impact. Building construction was found to be one of the most annoying noise and vibration sources, while the subway operation has little impact on residents according to either subjective or objective evaluation. The ratio of noise and vibration dissatisfaction was less than that of annoyance, which demonstrated that the residents’ psychological capacity was high toward the impact of noise and vibration. The proposed dose-response relationship can apply in a similar community environment. Once the noise levels within the building obtained, the residents’ noise annoyance can then be estimated.

Removal of fecal coliforms by thermophilic anaerobic digestion processes

2002 ◽  
Vol 46 (10) ◽  
pp. 147-152 ◽  
Author(s):  
C. De Leén ◽  
D. Jenkins
Keyword(s):  
Anaerobic Digestion ◽  
Treatment Plant ◽  
Operating Conditions ◽  
Single Stage ◽  
Fecal Coliforms ◽  
Two Stage ◽  
Class A ◽  
One Stage ◽  
Combustible Gas ◽  
Screening Study

Recent U.S. EPA regulations (40 CFR Section 503) specify maximum concentrations of pathogens and metals for Class A wastewater treatment plant sludges. The most common sludge process is mesophilic (35¡C) digestion which stabilizes the solids, produces a combustible gas but does not create an effluent that meets the 503 Class A pathogen requirements. This investigation was conducted to determine whether anaerobic digestion processes incorporating a thermophilic stage could achieve 503 Class A pathogen levels. The research reported here was a bench-scale screening study meant to identify the most promising process alternatives for further investigation. Fecal Coliform (FC) concentrations were used to assess disinfection efficiency. Digesters were 30 L capacity fed semi-continuously in draw-fill mode. Digester startup was rapid to produce true thermophiles. Temperature staging and pH were assessed in 3 sets of experiments: Set 1 were one stage (“acid phase”), Set 2 were one stage (“acid + methane phases”) and Set 3 were two stage (“acid phase” then “methanogenic phase”). Feed was a 1:1 mixture of Thickened Waste Activated Sludge and Primary Sludge. The following anaerobic digestion configurations and operating parameters allowed the production of digested sludge with a mean FC concentration statistically less than 103 (the regulatory value for Class A sludge): thermophilic single stage acid phase at 52 and 62°C; thermophilic single stage acid + methane phase at 48°C, 52°C and 62°C; two-stage mesophilic acid phase followed by mesophilic methane phase; two stage mesophilic acid phase followed by thermophilic methane phase at 48°C, 52°C and 62°C. If the maximum digested FC concentration must be below 103 MPN/g TS then the following digester configurations and operating conditions will be compliant: two stage mesophilic acid phase followed by thermophilic methane phase at 52°C and 62°C.

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