scholarly journals Subjective Effects of Sound Absorption and Investigation of Reverberation Times in Modern Japanese Dwellings

2021 ◽  
Vol 11 (6) ◽  
pp. 2709
Author(s):  
Kazuma Hoshi ◽  
Toshiki Hanyu ◽  
Ryoichi Suzuki ◽  
Daisuke Watanabe
Keyword(s):  
Sound Absorption ◽  
Subjective Evaluation ◽  
Subjective Effects ◽  
Full Scale ◽  
The Other ◽  
Subjective Effect ◽  
Absorption Coefficients ◽  
Subjective Test ◽  
Subjective Experiment ◽  
Room Model

This study aimed to reveal the influence of sound absorption in general dwellings on the subjective evaluation of acoustics. First, a subjective experiment was conducted using a full-scale room model. The results indicate that the feelings of silence and serenity can be experienced at absorption coefficients above 0.17, particularly above 0.25. Additionally, we used the recorded binaural sounds for a subjective test instead of using a full-scale room model. This trial showed that the reverberance, feeling of silence, and feeling of serenity can also be evaluated using a headphone listening test. We also measured the reverberation times and recorded the sound environments in three bedrooms, three living and dining (LD) rooms, and three child rooms in modern Japanese dwellings. The average absorption coefficients of the LD and child rooms were lower than 0.17, in the range of 500 Hz to 4 kHz. Therefore, we analyzed the subjective effect of absorption through a psychological test using binaural recorded sounds. The bedrooms with absorption coefficients of 0.18–0.23 were significantly less reverberant, quieter, and more serene than the other rooms.

Computational and experimental studies of the strength of full-scale samples of pipes with defects "metal loss" and "dent with groove"

2020 ◽  
Vol 10 (3) ◽  
pp. 226-233
Author(s):  
Dmitry A. Neganov ◽  
◽  
Victor M. Varshitsky ◽  
Andrey A. Belkin ◽  
◽  
...  
Keyword(s):  
Internal Pressure ◽  
Experimental Studies ◽  
Full Scale ◽  
The Other ◽  
Metal Loss ◽  
Calculation Methods ◽  
Reliable Operation ◽  
Sufficient Stability ◽  
Comparative Results ◽  
The Moment

The article contains the comparative results of the experimental and calculated research of the strength of a pipeline with such defects as “metal loss” and “dent with groove”. Two coils with diameter of 820 mm and the thickness of 9 mm of 19G steel were used for full-scale pipe sample production. One of the coils was intentionally damaged by machining, which resulted in “metal loss” defect, the other one was dented (by press machine) and got groove mark (by chisel). The testing of pipe samples was performed by applying static internal pressure to the moment of collapse. The calculation of deterioration pressure was carried out with the use of national and foreign methodical approaches. The calculated values of collapsing pressure for the pipe with loss of metal mainly coincided with the calculation experiment results based on Russian method and ASME B31G. In case of pipe with dent and groove the calculated value of collapsing pressure demonstrated greater coincidence with Russian method and to a lesser extent with API 579/ASME FFS-1. In whole, all calculation methods demonstrate sufficient stability of results, which provides reliable operation of pipelines with defects.

scholarly journals Diffuse Sound Absorptive Properties of Parallel-Arranged Perforated Plates with Extended Tubes and Porous Materials

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1091 ◽  
Author(s):  
Dengke Li ◽  
Daoqing Chang ◽  
Bilong Liu
Keyword(s):  
Boundary Condition ◽  
Porous Material ◽  
Porous Materials ◽  
Sound Absorption ◽  
Azimuthal Angle ◽  
Octave Band ◽  
Frequency Range ◽  
Absorption Coefficients ◽  
Perforated Plates ◽  
Absorption Performance

The diffuse sound absorption was investigated theoretically and experimentally for a periodically arranged sound absorber composed of perforated plates with extended tubes (PPETs) and porous materials. The calculation formulae related to the boundary condition are derived for the periodic absorbers, and then the equations are solved numerically. The influences of the incidence and azimuthal angle, and the period of absorber arrangement are investigated on the sound absorption. The sound-absorption coefficients are tested in a standard reverberation room for a periodic absorber composed of units of three parallel-arranged PPETs and porous material. The measured 1/3-octave band sound-absorption coefficients agree well with the theoretical prediction. Both theoretical and measured results suggest that the periodic PPET absorbers have good sound-absorption performance in the low- to mid-frequency range in diffuse field.

scholarly journals Professionally successful adults with attention-deficit/hyperactivity disorder (ADHD): Compensation strategies and subjective effects of pharmacological treatment

2008 ◽  
Vol 2 (1) ◽  
pp. 63-70 ◽  
Author(s):  
Andre Palmini
Keyword(s):  
Subjective Effects ◽  
Executive Dysfunction ◽  
Subjective Effect ◽  
Hyperactivity Disorder ◽  
Excessive Daytime Somnolence ◽  
Independent Life ◽  
Dsm Iv ◽  
Successful Adults ◽  
Subjective Reports ◽  
Do So

Abstract Although as a group, adult patients with ADHD have difficulties in social functioning due to inattention and executive dysfunction, some strive and succeed in living a productive, independent life. Purpose: To report on professionally successful adults with ADHD and analyze their main symptoms, compensation strategies and the subjective effect of methylphenidate on their functioning. Methods: The main symptoms of five patients with ADHD who are University educated and financially independent are reported. These patients were selected from a personally followed cohort of adults with ADHD. All were diagnosed according to DSM-IV adapted criteria (K-SADS E, version 6.0) and completed the Portuguese translated version of the ADHD adult self-reporting scale (ASRS). Results: Main reported symptoms included difficulties with attention, tendency to procrastinate and to 'shuffle' priorities, excessive daytime somnolence, memory difficulties and impulsiveness. Compensation strategies revolve around conscious, 'energy demanding' and time consuming efforts to control and circumvent symptomatic behavioral tendencies. They feel methylphenidate helps by alleviating the need to constantly apply compensation strategies for socially disabling symptoms. In sum, they achieve the same results in a more natural, less effortful fashion. Conclusions: Adults with ADHD may succeed professionally despite significant symptoms of inattention and executive dysfunction. They do so by appropriately using effortful strategies of compensation, the need for which is alleviated by the use of methylphenidate. These subjective reports require confirmation in prospective studies on larger series of patients.

scholarly journals Preparation and Characterization of Gradient Compressed Porous Metal for High-Efficiency and Thin-Thickness Acoustic Absorber

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1413 ◽  
Author(s):  
Xiaocui Yang ◽  
Xinmin Shen ◽  
Panfeng Bai ◽  
Xiaohui He ◽  
Xiaonan Zhang ◽  
...  
Keyword(s):  
Sound Absorption ◽  
High Efficiency ◽  
Structural Parameters ◽  
Porous Metal ◽  
Theoretical Models ◽  
Absorption Efficiency ◽  
Total Thickness ◽  
Porous Metals ◽  
Absorption Coefficients ◽  
Optimal Average

Increasing absorption efficiency and decreasing total thickness of the acoustic absorber is favorable to promote its practical application. Four compressed porous metals with compression ratios of 0%, 30%, 60%, and 90% were prepared to assemble the four-layer gradient compressed porous metals, which aimed to develop the acoustic absorber with high-efficiency and thin thickness. Through deriving structural parameters of thickness, porosity, and static flow resistivity for the compressed porous metals, theoretical models of sound absorption coefficients of the gradient compressed porous metals were constructed through transfer matrix method according to the Johnson–Champoux–Allard model. Sound absorption coefficients of four-layer gradient compressed porous metals with the different permutations were theoretically analyzed and experimentally measured, and the optimal average sound absorption coefficient of 60.33% in 100–6000 Hz was obtained with the total thickness of 11 mm. Sound absorption coefficients of the optimal gradient compressed porous metal were further compared with those of the simple superposed compressed porous metal, which proved that the former could obtain higher absorption efficiency with thinner thickness and fewer materials. These phenomena were explored by morphology characterizations. The developed high-efficiency and thin-thickness acoustic absorber of gradient compressed porous metal can be applied in acoustic environmental detection and industrial noise reduction.

An Analysis of the Aerodynamic Characteristics of Split Flaps

1940 ◽  
Vol 44 (352) ◽  
pp. 338-349
Author(s):  
A. P. West
Keyword(s):  
Experimental Data ◽  
Aerodynamic Characteristics ◽  
Full Scale ◽  
The Other ◽  
Aircraft Industry ◽  
The Past ◽  
The Many ◽  
Lift And Drag ◽  
Scale Data

During the past few years an extensive amount of experimental data on split flaps has been made available to the aircraft industry, through the publications of aeronautical research laboratories, both in this country and abroad. In general, each publication deals with one particular aspect of the problem, and when the effect of wing flaps on the performance of an aircraft is being estimated a certain amount of difficulty may be experienced in deciding which of the many reports available gives results most readily applicable to the case being considered ; and what allowances, if any, should be made for wing taper, flap cut-out, fuselage, etc.In this report the available data has been analysed with a view to answering these questions, and presented in such a form that it may be readily applied to determine the most probable change in the aerodynamic characteristics of a wing that may be expected from the use of this type of flap.From the appendix an estimate of the accuracy of the method can be obtained, as a comparison with full-scale data is given for lift and drag, and for the other flap characteristics the original curves have been reproduced.

scholarly journals A comparative review of the resistance of a 37,000 dwt Chemical Tanker based on experimental tests and calculations

2020 ◽  
Vol 1 ◽  
pp. 59-66
Author(s):  
Liviu Crudu ◽  
Radu Bosoancă ◽  
Dan Obreja
Keyword(s):  
Energy Efficiency ◽  
Experimental Tests ◽  
Full Scale ◽  
The Other ◽  
Towing Tank ◽  
Ship Resistance ◽  
Comparative Review ◽  
Cfd Applications ◽  
Energy Efficiency Design Index ◽  
Comparison Of The Results

The evaluation of ship resistance is of paramount importance having a decisive impact on the economic performances and efficiency depending on mission. If new IMO requirements through the Energy Efficiency Design Index (EEDI) are taken into account the necessity to have more and more accurate tools capable to consider the influences of different parameters became mandatory. The availability of towing tank facilities and the full scale trials are the practical means in order to be able to confirm the accuracy of theoretical formulations and to define the limits of CFD applications. Based on the results of the towing tank tests, a direct comparison with the results provided by classical methods and CFD computations can be systematically can be performed. On the other hand, the influences of the modifications operated on the fore part of the ship aretheoretically evaluated and compared with the towing tank results. Consequently, the paper is focused on the comparison of the results evaluated using different tools which have been carried out for a Chemical Tanker built by Constanta Shipyard Romania.

scholarly journals COMPARATIVE ANALYSIS OF SOUND SUPRESSING LIGHTWEIGHT STRUCTURED PANELS AND MODERN NOISE PROTECTION MEANS

Akustika ◽  
2019 ◽  
Vol 32 ◽  
pp. 30-35
Author(s):  
Valery Murzinov ◽  
Pavel Murzinov ◽  
Irina Ivanovna
Keyword(s):  
Comparative Analysis ◽  
Sound Absorption ◽  
Absorption Coefficients ◽  
Acoustic Insulation ◽  
Materials Used ◽  
And Control

This article provides an overview of modern soundproof materials and structures used for acoustic insulation. Presently, we can find plenty of such noise insulation and sound absorption materials. One of the popular means to reduce noise and control sound today is the acoustic panels able to suppress and absorb different sounds. The article also analyses the effectiveness of acoustic and sound protection materials used in the industrial sphere. The comparative analysis of the sound protection and absorption effectiveness is carried out using sound absorption coefficients. It also presents the construction of a sound suppressing lightweight structured panel designed by the authors. The authors noted that these panels have better characteristics in comparison with other modern sound protection materials.

scholarly journals Effects of heat treatment on sound absorption coefficients in nanosilver‐impregnated and normal solid woods

2016 ◽  
Vol 11 (4) ◽  
pp. 365-369 ◽  
Author(s):  
Ayoub Esmailpour ◽  
Hamid Reza Taghiyari ◽  
Habib Zolfaghari
Keyword(s):  
Heat Treatment ◽  
Sound Absorption ◽  
Absorption Coefficients
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