scholarly journals Sound Reduction of Ventilation Ducts through Walls: Experimental Results and Updated Models

Acoustics ◽  
2021 ◽  
Vol 3 (4) ◽  
pp. 695-717
Author(s):  
Erik Nilsson ◽  
Nikolaos-Georgios Vardaxis ◽  
Sylvain Ménard ◽  
Delphine Bard Hagberg
Keyword(s):  
Transmission Loss ◽  
Measurement Data ◽  
Combined System ◽  
Ventilation Ducts ◽  
Negative Effect ◽  
The Difference ◽  
Pass Through ◽  
Sound Reduction ◽  
Ventilation Duct ◽  
Reduction Index

Ventilation ducts can have a negative effect on the sound reduction index between two rooms if they pass through the dividing structure without treatments. The overall sound reduction of a ventilation duct is dependent on several factors including the transmission loss when sound is breaking in and out from the duct. This study aims to model the sound reduction of a combined system with a separating wall and a ventilation duct through it. Three walls, characterized according to ISO 717-1, are combined with three different ventilation ducts, two circular and one rectangular with different dimensions. Laboratory measurement data are used to determine the sound reduction of the different configurations and the type of treatments needed for each configuration. A proposed model with existing theory for describing sound transmission losses of circular and rectangular ventilation ducts predicts the shape of the measurement data for many frequency bands. A new theory part is developed through an iterative process for circular ducts, which is based on measurements with previous methods and studies as a guide because the existing prediction scheme is somewhat perplexing. For rectangular ducts, the existing theory has been updated to better match measurement data. The application of the proposed theory and model in this article shows similar results when compared to measurements. The difference in weighted sound reduction index between developed theories and measurement data is 0–1 dB for every configuration.

scholarly journals IMPLEMENTATION OF LABORATORY MEASUREMENT OF AIRBORNE SOUND INSULATION BASED ON ISO AND ASTM STANDARDS IN NATIONAL STANDARDIZATION AGENCY OF INDONESIA (BSN)

2021 ◽  
Vol 23 (1) ◽  
pp. 77
Author(s):  
Bondan Dwisetyo ◽  
Maharani Ratna Palupi ◽  
Fajar Budi Utomo ◽  
Chery Chaen Putri ◽  
Dodi Rusjadi ◽  
...  
Keyword(s):  
Transmission Loss ◽  
Laboratory Measurement ◽  
Sound Insulation ◽  
Reference Curve ◽  
Airborne Sound ◽  
Significant Difference ◽  
Single Number ◽  
Sound Reduction ◽  
Reduction Index

<p>The implementation of laboratory measurement of airborne sound insulation based on ISO and ASTM standards was carried out at SNSU BSN. The aim of this work to realize the measurement of airborne sound insulation for several sample tests, where the procedure of the test is performed according to the updated standard ISO 10140 and ASTM E90. Besides, the single number rating also is determined based on ISO 717-1 and ASTM E413. This measurement has been conducted in the two reverberation rooms using pressure method consist of measuring the sound pressure level, measuring the reverberation time, obtaining the sound reduction index (R) or sound transmission loss (STL), and determination of a single-number ratings of the samples test. From the results, some parameter requirements such as the frequency range and the rounding procedure of R or STL influence the measurement result slightly. Subsequently, the significant difference is obtained for the determination of single number rating in the shifting procedure of the reference curve.</p>

A Comparative Study of Sound Transmission Loss Provided by Glass, Acrylic and Polycarbonate

2013 ◽  
Vol 60 (1) ◽  
Author(s):  
Elwaleed Awad Khidir ◽  
Zambri Harun ◽  
Mohd Jailani Mohd Nor ◽  
Muhamad Razi
Keyword(s):  
Transmission Loss ◽  
Sound Transmission ◽  
Sound Insulation ◽  
Sound Transmission Loss ◽  
Material Density ◽  
Airborne Sound ◽  
Single Number ◽  
Reverberation Chambers ◽  
Sound Reduction ◽  
Reduction Index

This article presents an assessment for the airborne sound insulation provided by single glazed panels. The glazed panels were glass, acrylic and polycarbonate with a thickness of 4 mm. The experiments were conducted in a transmission loss facility consisting of semi anechoic and reverberation chambers. The panels were subjected to airborne sound and the data collected. Glass, acrylic and polycarbonate panel absorb noise most effectively above 500 Hz with the absorption peaks at 1000 Hz. The single number sound reduction index (RW) for glass, polycarbonate and acrylic were 41 dB, 38 dB and 37 dB, respectively. This could be attributed mainly to the material density which is higher for the glass. Keywords: Sound transmission loss; glazing; insulation; weighted index

scholarly journals An integrated control on thermal and noise environment of tropical building material

2018 ◽  
Vol 67 ◽  
pp. 04012
Author(s):  
FX Teddy Badai Samodra ◽  
Irvansyah ◽  
Collinthia Erwindi
Keyword(s):  
Heat Flow ◽  
Urban Area ◽  
Building Material ◽  
Transmission Loss ◽  
Integrated Control ◽  
World Health ◽  
Noise Environment ◽  
Sound Reduction ◽  
Conduction Heat Flow ◽  
Reduction Index

The environmental problems of thermal and noise environment are recently considered the most important contributors to the tropical building in an urban area. The porous tropical materials provide both a solution for cooling and airborne noise problem from the source to receiver when the wind is in the same direction. This research optimizes the integrated control of thermal and noise environment which are directed into building material evaluation. Surabaya is selected as representative of the hotter area of the lowland while Malang is determined as the colder urban area of the highland. An eco-tropical lightweight material, wood, is examined as a case study. The field measurement for surface material temperature and its transmission loss were conducted in order to give information on thermal and acoustical properties of the material. The optimization is conducted by comparing Sound Reduction Index and by Conduction Heat Flow. The results highlighted that for the same material, the thickness that effect on its mass is important for both thermal and noise control. The higher the thickness is, the higher the Sound Reduction Index and the lower the conduction heat flow are. Modifying material by adding the thickness of wood results that by material mass minimum 36.5 kg/m2, the critical lowland building meets the standard of World Health Organization noise limits and has lower heat gain.

Effect of leakage and blockage on the acoustic behavior of particle filters

2019 ◽  
Vol 67 (6) ◽  
pp. 483-492
Author(s):  
Seonghyeon Baek ◽  
Iljae Lee
Keyword(s):  
Transfer Matrix ◽  
Particle Filters ◽  
Acoustic Analysis ◽  
Transmission Loss ◽  
One Dimensional ◽  
Filter System ◽  
The Difference ◽  
The One ◽  
Analytical Approaches ◽  
Good Agreement

The effects of leakage and blockage on the acoustic performance of particle filters have been examined by using one-dimensional acoustic analysis and experimental methods. First, the transfer matrix of a filter system connected to inlet and outlet pipes with conical sections is measured using a two-load method. Then, the transfer matrix of a particle filter only is extracted from the experiments by applying inverse matrices of the conical sections. In the analytical approaches, the one-dimensional acoustic model for the leakage between the filter and the housing is developed. The predicted transmission loss shows a good agreement with the experimental results. Compared to the baseline, the leakage between the filter and housing increases transmission loss at a certain frequency and its harmonics. In addition, the transmission loss for the system with a partially blocked filter is measured. The blockage of the filter also increases the transmission loss at higher frequencies. For the simplicity of experiments to identify the leakage and blockage, the reflection coefficients at the inlet of the filter system have been measured using two different downstream conditions: open pipe and highly absorptive terminations. The experiments show that with highly absorptive terminations, it is easier to see the difference between the baseline and the defects.

Prediction of sound reduction index of plenum window by the surface impedance approach

2021 ◽  
Vol 175 ◽  
pp. 107851
Author(s):  
Liangfen Du ◽  
Siu-Kit Lau ◽  
Siew Eang Lee
Keyword(s):  
Surface Impedance ◽  
Sound Reduction ◽  
Reduction Index

Effects of Diarrhea Associated with Specific Enteropathogens on the Growth of Children in Rural Bangladesh

PEDIATRICS ◽  
1984 ◽  
Vol 73 (6) ◽  
pp. 799-805 ◽  
Author(s):  
Robert E. Black ◽  
Kenneth H. Brown ◽  
Stan Becker
Keyword(s):  
Linear Growth ◽  
Protein Energy Malnutrition ◽  
Growth Control ◽  
Reference Population ◽  
Enterotoxigenic Escherichia Coli ◽  
E Coli ◽  
Rural Bangladesh ◽  
Protein Energy ◽  
Negative Effect ◽  
The Difference

Village-based surveillance data from longitudinal studies in rural Bangladesh have been used to evaluate the nutritional consequences of infectious diseases, including diarrhea due to specific pathogens. The prevalences of specific illnesses were related to the ponderal and linear growth of young children for 2-month and 1-year periods. Of the common illnesses, only diarrhea had a significant inverse relationship with increments of weight during 2-month periods and of length during 1 year. Diarrhea accounted for 20% of the difference in linear growth between the study children and the international reference population during the first 5 years of life. Diarrhea associated with enterotoxigenic Escherichia coli had a significant negative effect on the bimonthly weight gain of children in this community and shigellosis had the strongest negative effect on bimonthly and annual linear growth. Control of diarrhea due to enterotoxigenic E coli and Shigella would not only substantially diminish diarrheal morbidity but would also improve the growth of children and thereby reduce the prevalence of protein-energy malnutrition.

FC 068QUALITY OF LIFE OVER TIME IN OLDER MEN AND WOMEN WITH ADVANCED CKD - RESULTS FROM THE EQUAL STUDY

2021 ◽  
Vol 36 (Supplement_1) ◽  
Author(s):  
Nicholas Chesnaye ◽  
Yvette Meuleman ◽  
Esther De Rooij ◽  
Friedo W Dekker ◽  
Marie Evans ◽  
...  
Keyword(s):  
Harmful Effect ◽  
Patient Characteristics ◽  
P Value ◽  
Joint Models ◽  
Cross Sectional ◽  
Linear Interaction ◽  
Men And Women ◽  
Negative Effect ◽  
The Difference ◽  
Over Time

Abstract Background and Aims Differences between the sexes are apparent in the epidemiology of CKD. Cross-sectional studies show that women consistently report a poorer health-related quality of life (QoL) than men, however, longitudinal studies are lacking. Here we investigate the sex-specific evolution of QoL over time in advanced CKD. As a secondary aim, we explore the sex-specific determinants of QoL. Method EQUAL is an observational prospective cohort study in stages 4 and 5 CKD patients ≥65 years not on dialysis with an incident estimated glomerular filtration rate (eGFR) &lt; 20 ml/min/1.73m². Data on QoL (measured using the RAND-36), clinical and demographic patient characteristics were collected between April 2012 and September 2020. QoL trajectories were modelled by sex using linear mixed models, and joint models were applied to deal with informative censoring. We followed patients until death or dialysis initiation. Results We included 5151 QoL measurements in 1416 patients over a total of 1986 person years of follow-up. Overall, the physical component summary (PCS) declined with 2.0 (95% CI 1.4-2.6) points and the mental component summary (MCS) by 2.4 (95% CI 1.8-3.0) points per year. Although women had overall lower QoL scores, figure 1 demonstrates that PCS and MCS declined more than twice as fast in men (PCS: 2.4 per year, 95% CI 1.7 – 3.1, MCS: 2.9 per year, 95% CI 2.2 – 3.6) compared with women (PCS: 1.1 per year, 95% CI -0.2 – 2.0, MCS: 1.5 per year, 95% CI 0.5 – 2.4). We identified a non-linear interaction effect between sex and eGFR levels on QoL, demonstrating a stronger negative effect of decreased eGFR on both PCS (p=0.02) and MCS (p=0.04) in men compared with women. Subsequent adjustment for renal decline attenuated the difference in rate of QoL decline between men and women (difference after adjustment; PCS: 1.1, 95% CI -0.1 – 2.2, MCS: 1.2, 95% 0.0 – 2.3). In univariable analyses, higher serum haemoglobin was more beneficial to QoL in men compared to women (p-value for interaction; PCS: p=0.03, MCS: p=0.01). Higher serum phosphate had a strong harmful effect on both PCS and MCS in men, but not in women (PCS & MCS: p&lt;0.001). The presence of pre-existing diabetes had a negative effect on PCS and MCS in men, but to a lesser extent in women (PCS: p=0.02, MCS: p=0.01). Conclusion Despite the higher overall QoL reported by men, both their physical and mental QoL declined approximately twice as fast compared with women. The faster decline in men was mediated in part by their lower levels of renal function, which had a stronger impact on their QoL as compared with women. Furthermore, in exploratory analyses we identified that high levels of phosphate, low levels of haemoglobin, and pre-existing diabetes were more detrimental to QoL in men than in women.

The impact of credit risk on the financial stability of commercial banks in Vietnam

2021 ◽  
Vol 11 (2) ◽  
pp. 67-80
Author(s):  
Nguyen Quoc Anh ◽  
Duong Nguyen Thanh Phuong
Keyword(s):  
Credit Risk ◽  
Commercial Banks ◽  
Financial Stability ◽  
Dynamic Panel Data ◽  
Z Score ◽  
Return On Equity ◽  
Score Analysis ◽  
Negative Effect ◽  
The Difference ◽  
The Impact

This study investigates the impact of credit risk on the financial stability of Vietnamese commercial banks. The paper uses the Z-score to proxy the financial stability of banks. We use the data of 27 Vietnamese commercial banks on BankScope, during 2010 - 2019. The paper applied a dynamic panel data approach; the selected method is the difference GMM (DGMM). The key question discussed is which factor impacts on Z-score. Analysis results show the negative effect of non-performing loans on the financial stability of banks. When commercial banks have higher non-performing loans, the lower the financial stability is. Additionally, bank-specific variables such as equity on asset ratio, the return on equity, the size of the bank and set of macroeconomic variables affect the bank’s financial stability. Based on the analysis results, we imply relevant policies for the State Bank of Vietnam and commercial banks.

scholarly journals THE ACCUMULATION OF ELECTROLYTES

1932 ◽  
Vol 15 (6) ◽  
pp. 667-689 ◽  
Author(s):  
W. J. V. Osterhout ◽  
W. M. Stanley
Keyword(s):  
Steady State ◽  
Osmotic Pressure ◽  
Aqueous Phase ◽  
Thermodynamic Potential ◽  
Ph Value ◽  
Molecular Form ◽  
External Solution ◽  
Aqueous Layer ◽  
The Difference ◽  
Pass Through

Inasmuch as attempts to explain accumulation by the Donnan principle have failed in the case of Valonia, a hypothesis of the steady state has been formulated to explain what occurs. In order to see whether this hypothesis is in harmony with physico-chemical laws attempts have been made to imitate its chief features by means of a model. The model consists of a non-aqueous layer (representing the protoplasmic surface) placed between an alkaline aqueous phase (representing the external solution) and a more acid aqueous phase (representing the cell sap). The model reproduces most of the features of the hypothesis. Attention may be called to the following points. 1. The semipermeable surface is a continuous non-aqueous phase. 2. Potassium penetrates by combining with an acid HX in the non-aqueous layer to form KX which in turn reacts with an acid HA in the sap to form KA. Since KX is little dissociated in the non-aqueous layer potassium appears to pass through it chiefly in molecular form. 3. The internal composition depends on permeability, e.g., sodium penetrates less rapidly than potassium and in consequence potassium predominates over sodium in the "artificial sap." The order of penetration in the model is the same as in Valonia, i.e., K &gt; Na &gt; Ca &gt; Mg, and Cl &gt; SO4, but the quantitative resemblance is not close, e.g., the difference between potassium and sodium, and chloride and sulfate is much less in the model. 4. The formation of KA and NaA in the sap raises its osmotic pressure and water enters. 5. The concentration of potassium and sodium and the osmotic pressure become much greater inside than outside. For example, potassium may become 200 times as concentrated inside as outside. 6. No equilibrium occurs but a steady state is reached in which water and salt enter at the same rate so that the composition of the sap remains constant as its volume increases. 7. Since no equilibrium occurs there is a difference of thermodynamic potential between inside and outside. At the start the thermodynamic potential of KOH is much greater outside than inside. This difference gradually diminishes and in the steady state has about the same value as in Valonia. The difference in pH value between the internal and external solutions is also similar in both cases (about 2 pH units). 8. Accumulation does not depend on the presence of molecules or ions inside which are unable to pass out. One important feature of the hypothesis is not seen in the model: this is the exchange of HCO3 for Cl-. Experiments on this point are in progress.

scholarly journals INTERVENSI KEBIJAKAN MONETER TERHADAP INVESTASI PORTOFOLIO: KASUS INDONESIA DAN AMERIKA SERIKAT

2020 ◽  
Vol 2 (1) ◽  
pp. 1
Author(s):  
Nanda Alfarina ◽  
Hasdi Aimon
Keyword(s):  
United States ◽  
Interest Rate ◽  
Secondary Data ◽  
The United States ◽  
Portfolio Investment ◽  
Mechanism Analysis ◽  
Long Run ◽  
Negative Effect ◽  
The Difference ◽  
Effect Of Monetary Policy

This study aims to determine the effect of monetary policy measured by the central bank’s policy rate (X1) on portfolio investment (Y) in Indonesia and United States in the long run. The data used are secondary data seouced from SEKI BI, FRED The FEd, coinmarketcap.com, and investing.com, with the VECM (Vector Error Correction Mechanism) analysis methode. The study show The study shows the differences between the results that occur in Indonesia and the United States. The policy interest rate has a significant positive effect on portfolio investment in the long run in Indonesia, while in the United States the interest rate in the long run has a significant negative effect on portfolio investment. The difference in research results between the two countries shows the need for different treatment for monetary authorities in encouraging portfolio investment 

Sign in / Sign up

Export Citation Format

Share Document