Journal articles: 'Dynamic muffler'

1

Zhou, Xin Xiang, Da Meng Han, Xing Long Lei, Cheng Liu, and Guang Yu Hu. "Muffler of High Quality and Efficiency Based on Structural Dynamic Optimization and the Modal Analysis." Advanced Materials Research 753-755 (August 2013): 1156–60. http://dx.doi.org/10.4028/www.scientific.net/amr.753-755.1156.

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According to the mechanism and spectrum characteristics of an oil-free air compressor noise source, determined the muffler installed at the air inlet. According to the characteristics of noise source, muffler is designed into type of expansion chamber, considering the structural dynamic parameters, by means of optimization method to determine the size, and the finite element modal analysis is conducted. By solving the muffler's inherent frequency and mode of vibration, knows weather each order natural frequency is away from the peak frequency, the structural dynamics of the muffler can be modification. Methods of structure modal analysis and dynamic optimization on the muffler provided reliable reference to design a high efficient new muffler.

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Chatterjee, Sushovan. "Computational fluid dynamic analysis of the exhaust gas flow through absorptive and reactive mufflers: some case studies." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 231, no. 11 (December 19, 2016): 1568–88. http://dx.doi.org/10.1177/0954407016676230.

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This paper aims to study comprehensively the flow characteristics of exhaust gases through different types of muffler (e.g. absorptive, reactive and resonating). Geometric models were designed using PRO-E and analysed using ANSYS FLUENT 14. The contours for the pressure, the velocity and the turbulence were plotted for optimization of the muffler design based on the known thermodynamic parameters. On the basis of the variation in these parameters, various hybrid designs were proposed for a muffler and even for a combination of mufflers.

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Mohamad, Barhm, Jalics Karoly, Andrei Zelentsov, and Salah Amroune. "A hybrid method technique for design and optimization of Formula race car exhaust muffler." International Review of Applied Sciences and Engineering 11, no. 2 (August 2020): 174–80. http://dx.doi.org/10.1556/1848.2020.20048.

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AbstractIn this work a multilevel Computational Fluid Dynamics (CFD) analysis has been applied for the design of a Formula race car exhaust muffler with improved characteristics of sound pressure level (SPL) and fluid dynamic response. The approaches developed and applied for the optimization process range from the 1D to fully 3D CFD simulation, exploring hybrid approaches based on the integration of a 1D model with 3D tools. Modern mufflers typically have a complex system of chambers and flow paths. There are a variety of sound damping and absorbing mechanisms working to quiet the sound flowing through a muffler and piping system. Two calculation methods were selected for this study. The muffler has a complex inner structure containing perforated pipe and fiber material. Computer-aided design (CAD) file of the muffler was established for developing Finite Element Analysis (FEA) model in AVL BOOST v2017 and another commercial advanced design software (SolidWorks 2017). FEA model was made to monitor the flow properties, pressure and velocity. After the model was verified, sensitivity studies of design parameters were performed to optimize the SPL of the muffler. The software analysis results are included in the paper. Recommendations are made for obtaining smoother SPL curves for various measurement methods.

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4

Geddes, Earl R. "Active muffler with dynamic tuning." Journal of the Acoustical Society of America 92, no. 2 (August 1992): 1197–98. http://dx.doi.org/10.1121/1.404025.

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5

Shan, Chang-ji, Yi-duo Bian, Ting-ting Dai, Cai Yan, Guo-fang Du, and Hai-tao Yang. "The Design of Follow-up Hydraulic Muffler Based on Spring-Damp Regulating Device." E3S Web of Conferences 79 (2019): 01006. http://dx.doi.org/10.1051/e3sconf/20197901006.

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The follow-up hydraulic muffler can make the natural frequency of the muffler equal to systematic pulsation frequency in time by changing the section area of the quality chamber so as to achieve the best attenuation effect. In this paper, a spring-damp regulator is installed on the basis of the hydraulic muffler, and the static and dynamic characteristics of the follow-up hydraulic muffler are analyzed by measuring the rotational speed of the pump with the sensor. The results show that the hydraulic muffler based on the spring-damp regulator can effectively attenuate the pulsation.

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6

Sofia, Evi, and Ilham Achmal Hakiki. "ANALISIS PENGARUH PEMASANGAN MUFFLER PADA MESIN PESAWAT TANPA AWAK LSU 02 TERHADAP TINGKAT KEBISINGAN." Volume 22 No. 2 Desember 2020 22, no. 2 (November 25, 2020): 51–60. http://dx.doi.org/10.23969/infomatek.v22i2.3304.

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LSU-02 merupakan pesawat tanpa awak yang dikembangkan oleh Pustekbang LAPAN dan mulanya akan menggunakan mesin 3W28i. Namun karena mesin 3W-28i memiliki muffler yang panjang, maka dalam penelitian ini akan dilakukan modifikasi dengan memvariasikan panjang dan diameter muffler. Selanjutnya dilakukan simulasi untuk mengetahui pengurangan tingkat kebisingan yang dihasilkan. Proses simulasi menggunakan metode computational fluid dynamic (CFD) dengan menggunakan perangkat lunak ANSYS Harmonic Acoustic. Dari hasil simulasi diperoleh kesimpulan jika semakin besar diameter muffler (80 mm) memberi kontribusi yang lebih baik dalam mengurang tingkat kebisingan sebesar 21.587 dB. Kemudian pengaruh panjang muffler terhadap pengurangan kebisingan tidak terlalu besar, karena selisih pengurangan kebisingan hanya sebesar 0,658 dB. Sehingga disarankan untuk menggunakan muffler model 5 dengan diameter 80 mm dan panjang 130 mm untuk dipasangkan pada mesin 3W-28i karena memiliki ukuran yang lebih kecil namun mampu mengurangi kebisingan hingga 20,929 dB.

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Wang, Fang, Tianning Chen, Xiaopeng Wang, Kai Bao, and Lele Wan. "A membrane-type acoustic metamaterial muffler." International Journal of Modern Physics B 31, no. 08 (March 30, 2017): 1750049. http://dx.doi.org/10.1142/s0217979217500497.

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Membrane-type acoustic metamaterials (MAMs) with negative dynamic mass have demonstrated the effects in the sound transmission loss (STL) at low-frequency range. This research aims to design a membrane-type acoustic metamaterial muffler (MAMM) based on the present MAMs, and to solve the problem that airflow cannot flow unimpededly in the channel once using the MAMs. For a better understanding of MAMM, the resonance frequency of the membrane was calculated and simulation was used to study the acoustic transmission performance of the MAMM. The simulation results were verified in comparison with the theoretical results of the membrane. This MAMM reduced the structural size of muffler compared with the traditional Helmholtz muffler and expand muffler, which can find application for the MAMs in acoustic absorption and noise control.

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8

Siano, Daniela, Fabio Bozza, and Fabio Auriemma. "Acoustic and fluid-dynamic optimization of an automotive muffler." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 227, no. 5 (December 10, 2012): 735–47. http://dx.doi.org/10.1177/0954407012465689.

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9

Shi, Lei Ming, Guang Hui Jia, Zhi Fei Zhang, and Zhong Ming Xu. "Analysis and Research of the Combustion Process of YN4100QB Diesel Engine." Advanced Materials Research 744 (August 2013): 35–39. http://dx.doi.org/10.4028/www.scientific.net/amr.744.35.

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In order to obtain the foundation to the research on the Diesel Engine YN4100QB combustion process, exhaust, the optimal design of combustion chamber and the useful information for the design of exhaust muffler, the geometric model and mesh model of a type internal combustion engine are constructed by using FIRE software to analyze the working process of internal combustion engine. Exhaust noise is the main component of automobile noise in the study of controlling vehicle noise. It is primary to design a type of muffler which is good for agricultural automobile engine matching and noise reduction effect. The present car mufflers are all development means. So it is bound to cause the long cycle of product development and waste of resources. Even sometimes not only can it not reach the purpose of reducing the noise but also it leads to reduce the engine dynamic. The strength of the exhaust noise is closely related to engine combustion temperature and pressure. The calculation and initial parameters are applied to the software based on the combustion model and theory. According to the specific operation process of internal combustion engine. Five kinds of common operation condition was compiled. It is obtained for the detailed distribution parameters of combusted gas temperature pressure . It is also got for flow velocity of the fields in cylinder and given for the relation of the parameters and crankshaft angle for the further research. At the same time NOx emissions situation are got. The numerical results show that not only does it provide the 3D distribution data in different crank shaft angle inside the cylinder in the simulation of combustion process, but also it provides a basis for the engine combustion ,emission research, the optimization design of the combustion chamber and the useful information for the designs of muffler.

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10

Liu, Zhong Da, Yu Guo, Lin Chen, and Yan Gao. "Optimization Analysis of Exhaust Muffler for a Hybrid Car by GT-Power." Applied Mechanics and Materials 246-247 (December 2012): 17–21. http://dx.doi.org/10.4028/www.scientific.net/amm.246-247.17.

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Both the attenuation performance and the aerodynamic performance should be carefully considered in the muffler design of automobiles. Aim to improve the exhaust-muffler properties of a hybrid car, a design work has been done and introduced in the paper. Firstly, the volume analysis method was utilized to give a rough estimation. Then, the GT-Power software was employed to construct the coupled simulation models of the process of acoustic performance and engine running, by which the insertion loss analysis and the exhaust back pressure difference analysis were completed. By combined the simulation with the experiment analysis, the acoustics performance and air dynamic characteristics of each model was obtained, and it provides the theoretical fundament for the improved design.

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11

Du, Huai Hui, Yu Hong Long, Jun Liang Liu, Wen Shang Li, and Jie Cai. "Research of Single Cavity Exhaust Muffler Based on AML and CFD Method." Advanced Materials Research 926-930 (May 2014): 3179–82. http://dx.doi.org/10.4028/www.scientific.net/amr.926-930.3179.

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Two mufflers of single exhaust muffler and double exhaust muffler were researched based on the method of AML technology of acoustic simulation software LMS Virtual lab and got transmission loss graph of the two mufflers, indicating that the single exhaust muffler had better effect of noise reduction. Then the fluid simulation was carried out on two mufflers and velocity and pressure cloud maps were draw based on the method of computational fluid dynamics in FLUENT. It is pointed out that the double exhaust muffler is slightly greater than the single exhaust muffler on pressure loss, this is because the airflow in single exhaust muffler is mainly jet flow and the pressure loss is mainly local pressure loss, while the airflow of double exhaust muffler is mainly rotary flow and the pressure loss is mainly frictional pressure loss. The impact that the airflow has on the cavity of the double exhaust muffler is higher.

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12

Zheng, Zhong Cai, Na Liu, Jian Li, Yan Gao, and Hai Ou Chen. "Numerical Analysis of Internal Flow in Mufflers with Complex Structures." Applied Mechanics and Materials 29-32 (August 2010): 89–94. http://dx.doi.org/10.4028/www.scientific.net/amm.29-32.89.

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This paper builds three-dimensional finite volume models for 4 different mufflers. Internal flow numerical analysis for mufflers is carried out with computational fluid dynamics software. Velocity field and pressure field are obtained to analyze the airflow influences on muffler performances. The corresponding regularities are obtained from simulation results, which provide a method for design optimization of mufflers.

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13

Su, Zhongya, Enbin Liu, Yawen Xu, Ping Xie, Chen Shang, and Qiyong Zhu. "Flow field and noise characteristics of manifold in natural gas transportation station." Oil & Gas Science and Technology – Revue d’IFP Energies nouvelles 74 (2019): 70. http://dx.doi.org/10.2516/ogst/2019038.

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Manifolds play a role of pressure balance, buffering and rectification for different branch pipelines, the flow noise of manifolds has been a serious problem all this time in natural gas transmission station. By changing the number of outlet pipes of manifolds and the different positions of intake pipes, the distribution of the Sound Pressure Level (SPL) of the manifold flow noise is analyzed based on the Ffowcs Williams-Hawkings (FW-H) acoustic analogy theory and Large Eddy Simulations (LESs). The three-dimensional simulation analysis of the flow field shows that pressure pulsation is the mainly source of manifold noise, as the number of outlet pipe increases, the SPLs of fluid dynamic noise at the end of inlet pipes are significantly reduced by about 10 dB on average, when the inlet and outlet piping are oppositely connected, the SPL is 2 dB~3 dB lower than that in staggered connections. An expansion-chamber muffler is designed with the analysis of its noise reduction effect, the results show that after the muffler is installed, the noise reduction in the low-frequency ranges reaches up to 37.5 dB, which controls the maximum noise to around 82 dB.

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14

Yue, Xiang-Ji, De-Chun Ba, Yao-Shuai Ba, and Fei Wang. "Pressure analysis in a compressor cylinder based on detached eddy simulation and dynamic mesh." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 227, no. 6 (August 13, 2012): 1242–51. http://dx.doi.org/10.1177/0954406212456470.

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Pressure pulsation has a critical importance in the design of refrigerant compressor since it acts as a noise and vibration source. For capturing the pressure pulsation and the transient flow structure, the numerical simulation based on detached eddy simulation and dynamic mesh approach was performed. Numerical results agree well with experimental data in the frequency band of 1000–2900 Hz. The results show that the vortex flows arise when the pressure disturbances propagate in the refrigerant gases and impact against the wall leading to the dramatic increase of the sound pressure level (the frequency band is about over 1800 Hz) in the cylinder and the noise radiated from compressor shell. Furthermore, we employed the numerical model to analyze the noise reduction mechanism of the muffler hole in the cylinder wall.

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Druzhinin, A. A., A. P. Kutrakov, and R. V. Zinko. "Silicon whisker pressure sensors for noise reduction in silencers." Технология и конструирование в электронной аппаратуре, no. 1-2 (2021): 28–32. http://dx.doi.org/10.15222/tkea2021.1-2.28.

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The article contains the results of research and development of a system for active noise damping of an automobile engine. The main source of noise from a running engine is exhaust noise. The frequency spectrum of this sound has a pronounced low-frequency character, which explains its weak absorption when the sound is propagating in open spaces. A possible solution to this problem is to use an active system for suppressing the resonant frequencies of the muffler using strain gauges to read the primary information about the dynamic processes that determine the noise level. It is for such active noise suppression systems that the authors develop a high-temperature pressure sensor based on strain gauges made of silicon whiskers. Such strain gauges have unique mechanical properties, are characterized by high sensitivity and the ability to operate in various amplitude-frequency and temperature ranges up to 500℃. The study of the dynamic characteristics of pressure sensors made it possible to confirm the quality of its electromechanical part and determine that the measurement error of the sensor is ±0.5 in the temperature range of 20 to 500℃. The active noise suppression system is a buffer tank whose volume changes in accordance with signals from pressure sensors. This design makes it possible to dynamically change the resonant frequency of the buffer capacitance depending on the operating modes of the engine, which leads to a decrease in its noise characteristics. Using the developed additional resonator chamber with a variable volume in the exhaust muffler of an internal combustion engine made it possible to reduce resonance phenomena in the zone of low-frequency pulsations of the exhaust gas pressure from 57 to 43 Hz with a frequency drift in the range of 310 to 350 Hz, which significantly improved its noise characteristics.

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Baruah, Sweta, and Sushovan Chatterjee. "Structural analysis for exhaust gas flow through an elliptical chamber muffler under static and dynamic loading condition." Advances in Modelling and Analysis B 61, no. 2 (June 30, 2018): 92–98. http://dx.doi.org/10.18280/ama_b.610207.

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17

Fang, Jian Hua, Qiang Ji, Yi Qi Zhou, and De Li Zhu. "Research on Relation among Inlet/Outlet Pressure, Pressure Loss and Inlet Velocity of a Complex Resistance Muffler." Applied Mechanics and Materials 477-478 (December 2013): 858–63. http://dx.doi.org/10.4028/www.scientific.net/amm.477-478.858.

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Simulation models of resistance mufflers with different typical structures were established, through the computational fluid dynamics method, under the conditions of different inlet velocities, by analyzing distribution characteristic of velocity field and pressure field for flows internal the mufflers, a kind of mathematical relation among the inlet velocity, inlet/outlet pressure, and pressure loss was discovered. Through CFD simulation computation and practical measuring tests of above three parameters for practical muffler with complex configurations, the mathematical relation of them was proved to be correct. With the conclusion, while inlet velocity changed, the variable conditions of inlet/outlet pressure and pressure loss for resistance mufflers could be estimated approximately Therefore, the test expense could be saved, and the designing efficiency for mufflers could also be further improved, so it would bring a certain economic benefit,which would be of great significance for energy saving research of mufflers.

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Pereira, E. L. L., C. J. Deschamps, and F. A. Ribas. "Performance analysis of reciprocating compressors through computational fluid dynamics." Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering 222, no. 4 (November 1, 2008): 183–92. http://dx.doi.org/10.1243/09544089jpme194.

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An experimentally validated numerical analysis of reciprocating refrigeration compressors is presented. The finite-volume methodology is adopted to solve the flow field and a one-degree-of-freedom model is used to describe the valve dynamics. The variation of the computation domain, associated with the valve and piston displacements, is taken into account and the time-dependent flow field and the valve dynamics are coupled and solved simultaneously. The three-dimensional formulation considered in the analysis allowed the simulation of actual suction and discharge muffler geometries. Numerical results were validated with reference to experimental data for valve displacement and pressure in the suction and compression chambers obtained in a calorimeter facility. A study was carried out to identify the contributions of mufflers and valves to the compressor thermodynamic losses.

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C., Mohan Raj. "Analysis of Various Automotive Mufflers: Computational Fluid Dynamics Approach." Revista Gestão Inovação e Tecnologias 11, no. 4 (July 10, 2021): 1339–48. http://dx.doi.org/10.47059/revistageintec.v11i4.2191.

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20

Shan, Chang Ji, Lin Li, and Jun Luo. "A Liquid Analysis of the Rectangular Wave Input Signals of Hydraulic Mufflers." Applied Mechanics and Materials 312 (February 2013): 172–76. http://dx.doi.org/10.4028/www.scientific.net/amm.312.172.

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This paper makes use of the method of computational fluid dynamics (CFD) to group the Hydraulic muffler of network grid and makes a fluidic analysis of the rectangular wave input signal of the hydraulic muffler without intubation noise absorption effect. The result manifests that the employment of CFD simulation technology to hydraulic muffler can provide evident theoretical support for further development and study of hydraulic muffler, and is possible to lay a foundation for continuous studies of the hydraulic muffler.

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Wang, Li, Yi Qi Zhou, and Zhen Hua Wang. "CFD Research on Aerodynamic Performance of Complicated Resistance Muffler." Applied Mechanics and Materials 34-35 (October 2010): 1274–78. http://dx.doi.org/10.4028/www.scientific.net/amm.34-35.1274.

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In this paper, a complicated resistance muffler was designed for a construction machinery. Computational Fluid Dynamics (CFD) method with three dimension models was used to explore the aerodynamic performance of the muffler. With this method the pressure distribution in the muffler is simulated and the pressure loss is predicted for the structure modification. The experiment results verify that the assembly performance of the muffler modified is better than the original muffler. The pressure loss and the insert loss of the improved muffler meet the design specifications and standards of the construction machinary. The integrated performance of the construction machinery has been advanced.

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Xu, Jianmin, and Shuiting Zhou. "Analysis of Flow Field for Automotive Exhaust System Based on Computational Fluid Dynamics." Open Mechanical Engineering Journal 8, no. 1 (December 31, 2014): 587–93. http://dx.doi.org/10.2174/1874155x01408010587.

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In this study, a double mode muffler that can automatically adjust the exhaust resistance according to the engine speed was designed. Based on computational fluid dynamics theory, the governing equation and turbulent equations for numerical simulation of muffler were established. The pressure loss and the internal flow characteristics of the double mode muffler were analyzed by CFD software. The influence of the distance between the main and submuffler on the flow field of exhaust system was researched. In addition, the internal pressure distribution, the turbulence intensity distribution and the velocity vector diagram of the dual mode muffler were also obtained. The pressure loss of double mode muffler is mainly distributed in the area of air mutations. Main silencer plays a leading role in the entire exhaust system. Therefore, the trend of the pressure loss of the exhaust system with the change in the distance between main and auxiliary muffler was also obtained. When the distance between the main and auxiliary silencer changed from 50 mm to 300 mm, the pressure loss of exhaust system muffler first increased and then decreased, and following this, continued to increase. The results will provide a theoretical basis for designing complex exhaust system.

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Ren, Jia Wei, Qin Yu Jiang, and Zhen Wang. "CFD Simulation and Computation of Pressure Loss of Resistance Muffler." Advanced Materials Research 694-697 (May 2013): 307–11. http://dx.doi.org/10.4028/www.scientific.net/amr.694-697.307.

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Computational fluid dynamics (CFD) software was used to simulate the internal flow field of an example muffler, and compared the results with the experimental data, verifying the reliability of the simulation algorithm. On this basis, changed the example muffler structure, researched the pressure loss of muffler which was influenced by the insert duct, the position of the baffle and the inlet air velocity. The corresponding regularities have been obtained with the results of computations, which provide a basis for the design of the muffler.

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Prof. Dr. M.T. Bhoite, Prof Dr M. T. Bhoite, Akshay I. Babar, Prasad S. Yadav, and N. V. Karnath N.V.Karnath. "Case Study on use of Computational Fluid Dynamics for prediction of hydrodynamic characteristics of Exhaust Muffler." Indian Journal of Applied Research 3, no. 6 (October 1, 2011): 156–57. http://dx.doi.org/10.15373/2249555x/june2013/53.

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Jun, Fu, Zhang ZengFeng, Chen Wei, Mao Hong, and Li JianXing. "Computational fluid dynamics simulations of the flow field characteristics in a novel exhaust purification muffler of diesel engine." Journal of Low Frequency Noise, Vibration and Active Control 37, no. 4 (July 25, 2018): 816–33. http://dx.doi.org/10.1177/1461348418790488.

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The purpose of this paper is to improve the emission performance of diesel engines. A novel exhaust purification muffler was proposed and designed. The flow field characteristics of the exhaust purification muffler were studied based on the finite volume method, the pressure loss of the exhaust purification muffler was 3315 Pa, and the pressure loss of the exhaust purification muffler was just 2% higher than the original muffler. Then, a three-dimensional numerical simulation model was established and used to investigate the effect of different expansion ratio, cavity length ratio, and ratio of length to diameter on the flow field characteristics in an exhaust purification muffler of diesel engine. The study was shown that the porous media (ceramic foam) had a great influence on the flow field distribution, where the air flow velocity was stable and the pressure distribution was trapezoidal, having a good pressure reduction and deceleration effect. With the increase of the expansion ratio parameter, the airflow cross-section area changed when air entered into the inlet silencing cavity, which had great influence on the velocity field and the pressure loss. Because of the improvement of cavity length ratio parameter, the flowing distance in the inlet silencing increased, which caused more local turbulence and pressure fluctuation. Also with the increase of the ratio of length to diameter parameter, the volume of inlet silencing chamber and the air flow space increased. The change of the structural parameters of each scheme had a certain influence on the pressure loss. The maximum pressure loss changing value among the expansion ratio schemes was 878 Pa, then the maximum pressure loss changing value among the cavity length ratio schemes was 328 Pa, and it was 89 Pa among the cavity length ratio schemes. The pressure loss caused by the expansion ratio parameter changed greatly, and the pressure loss changing value caused by the change of the cavity length ratio parameter and the ratio of length to diameter parameter was relatively small. In this paper, a muffler which contained a ceramic foam and had the functions of exhaust soot purification and noise elimination was supplied. The effects of the structure factors on flow field characteristics were studied. The guidance for the design and improvement of muffler is able to be supplied in this paper.

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Stadnik, Dmitry M., Alexander A. Igolkin, Victor Y. Sverbilov, and Kirill M. Afanasev. "The Muffler Performance Effect on Pressure Reducing Valve Dynamics." Procedia Engineering 176 (2017): 706–17. http://dx.doi.org/10.1016/j.proeng.2017.02.316.

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HU, Xiaodong. "Computational fluid dynamics research on pressure loss of cross-flow perforated muffler." Chinese Journal of Mechanical Engineering (English Edition) 20, no. 02 (2007): 88. http://dx.doi.org/10.3901/cjme.2007.02.088.

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Avetisov, S., and S. Sorokin. "The analysis of dynamics of periodic fluid-loaded flexible tubes." Transactions of the Krylov State Research Centre S-I, no. 2 (December 28, 2020): 272–75. http://dx.doi.org/10.24937/2542-2324-2020-2-s-i-272-275.

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In this report, we consider a periodic tube consisting of absolutely rigid sections alternated with soft segments of the same inner diameter under the action of a tensile force. The purpose of this analysis is to explore possibilities to suppress wave propagation using this complex tube model as a muffler. Its waveguide properties are assessed by means of a mathematical model formulated in the framework of Floquet theory and the results are compared with the eigenfrequency and eigenmode analysis of a unit symmetric periodicity cell. The setup consisting of these alternating sections creates the stop band effect, so that it may be called a ‘macroscale acoustic metamaterial’.

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Turnova, Zuzana, Tomas Chrebet, Ivana Turekova, and Karol Balog. "Study of Thermal Stability of Magnesium Alloys." Advanced Materials Research 690-693 (May 2013): 74–77. http://dx.doi.org/10.4028/www.scientific.net/amr.690-693.74.

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Today, magnesium (Mg) alloys are recognized alternatives to iron and aluminum to reduce the weight of structural materials. This contribution was performed to provide information on the flammability of magnesium alloys through investigation of the ignition temperature of selected Mg alloys. The test was performed in a muffle furnace with dynamic heating program. Also were performed tests of chemical composition of studied specimens.

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Goto, Adriano Mitsuo, Victor Gustavo Ramos Costa Dos Santos, and José Maria Campos Dos Santos. "Band structure and defect states in acoustic phononic crystals using expansion and micro-perforated chamber mufflers." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, no. 5 (August 1, 2021): 1194–205. http://dx.doi.org/10.3397/in-2021-1775.

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The expansion and the micro-perforated chamber mufflers are acoustic silencers designed to attenuate the sound propagation at duct systems. These silencers can show interesting phononic crystals behavior when set periodically. The concept of phononic crystals still is an emerging topic in vibration and sound control. The periodic arrangement of acoustic silencers can provide a significant enhancement of the sound absorption due to the "wave filtering" property where the wave cannot propagate at certain frequency ranges, called stopbands or bandgaps. However, these properties may be affected by defects, like the break of the periodicity due to manufacturing errors. For the present work, the influence of some defects on the acoustic efficiency is investigated numerically for expansion and micro-perforated chamber mufflers. A direct and efficient approach is used to obtain the transfer and dynamic stiffness matrices. Simulated examples are used to calculate the forced response, transmission loss, and dispersion diagram, which are verified by other methods.

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Chen, Hai Jian, and Guang Yu Zhu. "Noise Reduction of Single Cylinder Diesel Engine Based on Virtual Prototype." Advanced Materials Research 718-720 (July 2013): 1499–503. http://dx.doi.org/10.4028/www.scientific.net/amr.718-720.1499.

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Based on the one-dimensional and unsteady flow theory of gas dynamics and acoustic analysis method, a thermodynamics and acoustics model of single cylinder diesel engine was established, then the model was realized using GT-Power. A method combined with mechanic analysis and acoustic prediction was presented. With this method, the influence of compression ratio, inlet and outlet channels, intake valve and exhaust valve timing on engine exciting force and noise is analyzed. Then the optimization value of each factor is determined to improve the muffler. The intake and exhaust noise of the optimized engine is simulated with this model, the simulating results indicated that the exhaust noise reduces 2.6~3dB, and the intake noise reduces 1.1~1.4dB.

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Weber, Till, and Craig Parsons. "Dynamic party unity: the US Congress in comparative perspective." European Political Science Review 8, no. 4 (July 28, 2015): 637–62. http://dx.doi.org/10.1017/s1755773915000235.

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Moises Ostrogorski once denounced political parties for burying diverse concerns of pluralistic societies under monolithic electoral options. E.E. Schattschneider celebrated them for the same reason: organizing choice and ‘responsible party government’ amid pluralistic complexity. Comparativists have found both dynamics in European legislatures: most European parties exhibit the high average levels of voting unity that Schattschneider’s theory implies, but also display rather Ostrogorskian cycles of discipline, stifling dissent on divisive issues at election time. We use comparativists’ tools to explore the dynamics and normative quality of party unity in the different terrain of the US Congress. We find similar cycles of unity in roll-call voting, but in the American context – with more loosely organized parties, especially historically but still today – Ostrogorskian stifling of dissent operates against a less Schattschneiderian background. In comparative perspective, Congressional parties muffle divisive issues more effectively than they deliver governance, with tenuous implications for representation.

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Liu, Enbin, Shanbi Peng, and Tiaowei Yang. "Noise-silencing technology for upright venting pipe jet noise." Advances in Mechanical Engineering 10, no. 8 (August 2018): 168781401879481. http://dx.doi.org/10.1177/1687814018794819.

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When a natural gas transmission and distribution station performs a planned or emergency venting operation, the jet noise produced by the natural gas venting pipe can have an intensity as high as 110 dB, thereby severely affecting the production and living environment. Jet noise produced by venting pipes is a type of aerodynamic noise. This study investigates the mechanism that produces the jet noise and the radiative characteristics of jet noise using a computational fluid dynamics method that combines large eddy simulation with the Ffowcs Williams–Hawkings acoustic analogy theory. The analysis results show that the sound pressure level of jet noise is relatively high, with a maximum level of 115 dB in the low-frequency range (0–1000 Hz), and the sound pressure level is approximately the average level in the frequency range of 1000–4000 Hz. In addition, the maximum and average sound pressure levels of the noise at the same monitoring point both slightly decrease, and the frequency of the occurrence of a maximum sound pressure level decreases as the Mach number at the outlet of the venting pipe increases. An increase in the flow rate can result in a shift from low-frequency to high-frequency noise. Subsequently, this study includes a design of an expansion-chamber muffler that reduces the jet noise produced by venting pipes and an analysis of its effectiveness in reducing noise. The results show that the expansion-chamber muffler designed in this study can effectively reduce jet noise by 10–40 dB and, thus, achieve effective noise prevention and control.

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Sun, Xing Bin, and Jin Zhu Han. "The Phosphorus-Adsorption Capacity and Influencing Factors Study of Zeolite." Advanced Materials Research 113-116 (June 2010): 766–69. http://dx.doi.org/10.4028/www.scientific.net/amr.113-116.766.

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Because of the poor phosphorus removal of nature zeolite, the best modification method was prepared as follows : First, natural zeolite was soaked in 1mol/L NaOH solution on dynamic condition at 35°C for 1 hour. After washed with deionied water, it was soaked in 20% MgCl2 solution on dynamic condition at 35°C for 48h, then was roasted at 500°C in a muffle furnace for 3h and in the end cooled to normal temperature.Based on this, the capacity of the modified zeolites was studied under different conditions of contact time, dosage and temperature in order to examine dephophorization ability of modified zeolite. The results from batch experiment suggest that the modified zeolite has a more P sorption capacity possibly due to the hydrated magnesium on or in the modified zeolite.

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Gryboś, Dominik, Jacek S. Leszczyński, Dorota Czopek, and Jerzy Wiciak. "Exhaust Noise Reduction by Application of Expanded Collecting System in Pneumatic Tools and Machines." Energies 14, no. 6 (March 13, 2021): 1592. http://dx.doi.org/10.3390/en14061592.

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In this paper, we demonstrate how to reduce the noise level of expanded air from pneumatic tools. Instead of a muffler, we propose the expanded collecting system, where the air expands through the pneumatic tube and expansion collector. We have elaborated a mathematical model which illustrates the dynamics of the air flow, as well as the acoustic pressure at the end of the tube. The computational results were compared with experimental data to check the air dynamics and sound pressure. Moreover, the study presents the methodology of noise measurement generated in a pneumatic screwdriver in a quiet back room and on a window-fitting stand in a production hall. In addition, we have performed noise measurements for the pneumatic screwdriver and the pneumatic screwdriver on an industrial scale. These measurements prove the noise reduction of the pneumatic tools when the expanded collecting system is used. When the expanded collecting system was applied to the screwdriver, the measured Sound Pressure Level (SPL) decreased from 87 to 80 dB(A).

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Bae, Soo Young. "A Trigger or a Muffler? - Examining the Dynamics of Crosscutting Exposure and Political Expression in Online Social Media." JeDEM - eJournal of eDemocracy and Open Government 5, no. 1 (November 20, 2013): 16–27. http://dx.doi.org/10.29379/jedem.v5i1.206.

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This study explores the potential of online social media to serve as a sphere for political discourse and investigates the extent to which everyday uses of online social networking sites can expose citizens to politically diverse viewpoints. In addition, this study asks whether such crosscutting exposure in online social networks will act as a trigger or a muffler for political expression – that is, whether exposure political difference will stimulate or discourage political discussions. With analyses of a sample of online social networking site users in the context of the 2012 presidential election in South Korea, this study explicates the link between crosscutting exposure and citizens’ political expressions in social media. Results reveal that contrary to the predictions in previous literature, exposure to politically incongruent viewpoints in online social networking sites does not seem to undermine users’ expressive behaviors but instead positively contribute to political expression. In addition, this study shows the significant role of citizens’ perceptions of candidate support in their own networks, and illustrates that the dynamics of political expression differ significantly depending on the users’ age.

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Vivan, Rodrigo Ricci, Jussaro Alves Duque, Murilo Priori Alcalde, Marcus Vinicius Reis Só, Clóvis Monteiro Bramante, and Marco Antonio Hungaro Duarte. "Evaluation of Different Passive Ultrasonic Irrigation Protocols on the Removal of Dentinal Debris from Artificial Grooves." Brazilian Dental Journal 27, no. 5 (October 2016): 568–72. http://dx.doi.org/10.1590/0103-6440201600725.

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Abstract The aim of this study was to evaluate the influence of different passive ultrasonic irrigation protocols on the removal of debris in artificially created grooves in the cervical, middle and apical root thirds. Forty extracted bovine incisor roots were instrumented to 1 mm of the root apex with a R50 Reciproc instrument and irrigated with 2.5% sodium hypochlorite. The roots were then inserted in a muffle and cleaved into two hemisections. Grooves (3-mm long) were done at 2, 7 and 12 mm from the root apex in one hemisection and filled with dentinal debris. The hemisections were regrouped into the muffle and divided into 4 groups (n=10) according to the final irrigation protocol: Control group: 3x20 s using a #30 gauge needle without agitation of the irrigating solution; Group PUI-s (static passive ultrasonic irrigation): 3x20 s of passive ultrasonic irrigation with the tip of the insert maintained static on the apical third; Group PUI-t (passive ultrasonic irrigation per third): 20 s of PUI in each third; Group PUI-d (passive dynamic ultrasonic irrigation): 3x20 s of PUI dynamically moving the insert in the whole extent of the root canal. In all groups, was used a total of 6 mL of 2.5% sodium hypochlorite as irrigant. After these procedures, the grooves were analyzed with a stereomicroscope and assigned scores as regards removal of the debris. The data were analyzed statistically (a=0.05). The results showed a better cleaning in all the groups where the irrigating solution was agitated with ultrasonic device than in the control group (p<0.05). In the apical third, the PUI-d and PUI-s showed similar performance (p>0.05) and a better cleanness than PUI-t (p<0.05). The dynamic and static methods of agitation of the irrigating solution provided more effective cleaning. PUI-d provided the most completely clean grooves suggesting that its use is the most adequate in cases of teeth with complex canal anatomy.

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Montenegro, G., A. Della Torre, A. Onorati, and R. Fairbrother. "A Nonlinear Quasi-3D Approach for the Modeling of Mufflers with Perforated Elements and Sound-Absorbing Material." Advances in Acoustics and Vibration 2013 (January 14, 2013): 1–10. http://dx.doi.org/10.1155/2013/546120.

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Increasing demands on the capabilities of engine thermo-fluid dynamic simulation and the ability to accurately predict both performance and acoustics have led to the development of several approaches, ranging from fully 3D to simplified 1D models. The quasi-3D approach is proposed as a compromise between the time-demanding 3D CFD analysis and the fast 1D approach; it allows to model the acoustics of intake and exhaust system components, used in internal combustion engines, resorting to a 3D network of 0D cells. Due to its 3D nature, the model predicts high-order modes, improving the accuracy at high frequencies with respect to conventional plane-wave approaches. The conservation equations of mass and energy are solved at cell centers, whereas the momentum equation is applied to cell connections including specific source term to account for the of sound-absorbing materials and perforated elements. The quasi-3D approach has been validated by comparing the predicted transmission loss to measured data for a number of standard configurations typical of internal combustion engine exhaust systems: a reverse-flow chamber and series chambers with perforates and resistive material.

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Garrison, Lance P., Jason S. Link, D. Patrick Kilduff, Matthew D. Cieri, Brandon Muffley, Douglas S. Vaughan, Alexei Sharov, Behzad Mahmoudi, and Robert J. Latour. "An expansion of the MSVPA approach for quantifying predator–prey interactions in exploited fish communities." ICES Journal of Marine Science 67, no. 5 (February 26, 2010): 856–70. http://dx.doi.org/10.1093/icesjms/fsq005.

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Abstract Garrison, L. P., Link, J. S., Kilduff, D. P., Cieri, M. D., Muffley, B., Vaughan, D. S., Sharov, A., Mahmoudi, B., and Latour, R. J. 2010. An expansion of the MSVPA approach for quantifying predator–prey interactions in exploited fish communities. – ICES Journal of Marine Science, 67: 856–870. Ecosystem-based fisheries management requires tools to place fish-stock dynamics in the broader context of fishery, predator, and competitive removals. Multispecies virtual population analysis (MSVPA) is an approach to quantifying predator–prey interactions and estimating the rates of predation mortality for exploited fish populations. Here, an extended MSVPA (MSVPA-X) is presented as an alternative to existing MSVPA approaches. Notably, MSVPA-X uses index-tuned VPA methods, applies a more flexible feeding model, and includes an alternative functional feeding response. The MSVPA-X model is applied to a western Atlantic fish community, focusing on Atlantic menhaden and its major fish predators, and a sensitivity analysis of major model parameters is presented. The sensitivity analysis highlights the need for adequate diet sampling. The MSVPA-X represents an improvement over previous approaches by increasing the flexibility to model seasonal and interannual dynamics in the strength of predator–prey interactions. Model results demonstrate that, for menhaden in particular, and forage fish in general, quantifying predation mortality is an important part of effective assessments of forage fish, their predators, and the fisheries of both.

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Mishra, Prakash Chandra, Sourav Kumar Kar, Harshit Mishra, and Anand Gupta. "Modeling for combined effect of muffler geometry modification and blended fuel use on exhaust performance of a four stroke engine: A computational fluid dynamics approach." Applied Thermal Engineering 108 (September 2016): 1105–18. http://dx.doi.org/10.1016/j.applthermaleng.2016.08.009.

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Zhang, Hua, Xue Hong Zhang, Yi Nian Zhu, Mei Na Liang, and Rong Rong Lu. "Adsorption of As(V) from Aqueous Solution by the Fe(III)-Impregnated Sorbent Prepared from Sugarcane Bagasse and Applicability of Different Adsorption Models." Applied Mechanics and Materials 316-317 (April 2013): 509–15. http://dx.doi.org/10.4028/www.scientific.net/amm.316-317.509.

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In this study, a Fe(III)-impregnated sorbent was prepared from sugarcane bagasse and FeCl3 solution via carbonization/activation in a muffle furnace at 500 °C for 4h. Batch experiments were carried out to determine the capacity of the Fe(III)-impregnated sorbent to adsorb As(V) from aqueous solution. The dynamical data fitted very well with the pseudo-second-order kinetic model and the calculated adsorption capacities of 4.8263, 5.2219 and 7.1225 mg/g were equal to the actual values of the experiments at temperatures of 20, 25, and 35 °C, respectively. The experimental data were modeled by Langmuir and Freundlich isotherm models. The Langmuir isotherm with R2 values of 0.9926-0.9968 could yield better fits than the Freundlich isotherm, and the adsorption was endothermic, indicating monolayer adsorption of As(V).Freundlich isotherm, and the adsorption was endothermic, indicating monolayer adsorption of As(V).

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Liang, Mei Na, Hong Hu Zeng, Yi Nian Zhu, Ze Long Xu, and Hui Li Liu. "Adsorption Removal of Phosphorus from Aqueous Solution by the Activated Carbon Prepared from Sugarcane Bagasse." Advanced Materials Research 183-185 (January 2011): 1046–50. http://dx.doi.org/10.4028/www.scientific.net/amr.183-185.1046.

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The activated carbon was prepared firstly by soaking sugarcane bagasse in 0.39% AlCl3 solution, and then by carbonization in a charcoal kiln at 400oC for 2 days and activation in a muffle furnace at 900°C for 100 minutes. The adsorption removal of phosphorus from aqueous solution by the prepared activated carbons was studied in a batch adsorption system. The amount of phosphorus adsorbed per unit mass of adsorbent decreased from 1.13 to 0.33 mg/g and the removal percentage of phosphorus increased from 22.64 to 99.27% with increasing adsorbent dosages from 100 to 1500 mg in 50mL solution of the initial phosphorus concentration of 10mg/L. With increasing phosphorus concentrations from 1 to 30 mg/L, the amount of phosphorus adsorbed increased from 0.06 to 1.11 mg/g and the percent adsorption decreased from 91.93 to 57.34%. The dynamical data fit very well with the pseudo-second-order kinetic model (R2>0.9962) and the Langmuir model agreed well with the experimental data (R2>0.9648).

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Cyklis, Piotr, and Przemysław Młynarczyk. "An innovative simulation method for the estimation of the nozzle pressure pulsation attenuation." Journal of Vibration and Control 23, no. 16 (December 13, 2015): 2690–703. http://dx.doi.org/10.1177/1077546315619534.

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Pressure pulsations in volumetric compressor manifolds have a high impact on compression power requirement and the reliability of manifold operation. These pulsations induce vibrations, noise, and in some cases, mechanical failure of piping or compressor valves. For pressure pulsation attenuation, different types of mufflers are applied using a design based upon the Helmholtz resonator approach. This design is particularly effective for constant revolution speed compressors. For contemporary applications of variable revolution speed compressors, other pressure pulsation attenuation methods are needed. It is known that different shapes of nozzles can attenuate pressure pulsations, however, they unfortunately increase the compressor power at the same time. The main criterion for nozzle selection is achieving pressure pulsation attenuation that is as high as possible whilst having the lowest possible effect on compressor power. In this paper, innovative computational fluid dynamics (CFD) simulation methodology is applied for the optimisation of nozzle shape and size. The steady flow simulation results correspond with compressor power consumption and impulse flow simulation results are related to pressure pulsation attenuation. This method has been validated on the basis of the experimental results for three different nozzle geometries. For experimental validation, nozzles have been mounted in the variable speed screw compressor discharge manifold.

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McKee, Christopher F. "Supernova Remnant Shocks in an Inhomogeneous Interstellar Medium." International Astronomical Union Colloquium 101 (1988): 205–22. http://dx.doi.org/10.1017/s0252921100102386.

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AbstractThe inhomogeneity of the interstellar medium (ISM) has a profound effect on the propagation of the interstellar shock generated by a supernova and on the appearance of the resulting supernova remnant (SNR). Low mass supernovae produce remnants that interact with the “pristine” ISM, which has density inhomogeneities (clouds) on a wide range of scales. The shock compresses and accelerates the clouds it encounters; inside the blast wave, the clouds are hydrodynamically unstable, and mass is injected from the clouds into the intercloud medium. Embedded clouds interact thermally with the shock also, adding mass to the hot intercloud medium via thermal evaporation or subtracting it via condensation and thermal instability. Mass injection into the hot intercloud medium, whether dynamical or thermal, leads to infrared emission as dust mixes with the hot gas and is thermally sputtered. The remnants of massive supernovae interact primarily with circumstellar matter and with interstellar material which has been processed by the ionizing radiation and wind of the progenitor star. After passing through any circumstellar material which may be present, the shock encounters a cavity which tends to “muffle” the SNR. The remnants of massive supernovae therefore tell us more about the late stages of the evolution of massive stars than about the ISM.

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Albers, A., H. Weiler, D. Emmrich, and B. Lauber. "A New Approach for Optimization of Sheet Metal Components." Advanced Materials Research 6-8 (May 2005): 255–62. http://dx.doi.org/10.4028/www.scientific.net/amr.6-8.255.

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Beads are a widespread technology for reinforcing sheet metal structures, because they can be applied without any additional manufacturing effort and without significant weight increase. The two main applications of bead technology are to increase the stiffness for static loading conditions and to reduce the noise and vibrations for dynamic loadings. However, it is difficult to design the bead patterns of sheet metal structures due to the direction-controlled reinforcement effect of the beads. A wrong bead pattern layout can even weaken the properties of the structure. In the past, the designs were predominantly determined empirically or by the use of so called bead catalogues. Recently, different optimization approaches for bead patterns were developed, which are based upon classical mathematical programming optimization algorithms together with automatically generated shape basis vectors. However, these approaches usually provide only vague suggestions for the designs. One of the most severe difficulty with these approaches is to transfer the optimized results into manufacturable designs. Furthermore, another severe difficulty is that the optimization problem is non-convex, which frequently leads the mathematical programming algorithms into a local optima and thus to sub-optimal solutions. The investigations in this article show an optimization method, which within a few iterations leads to bead structures with excellent reinforcement effects using optimality criteria based approach. Generally, the results can be transferred without large effort into a final design. The new optimization method calculates the distribution of the bending stress tensor and the principal bending stresses based upon the results of a finite element analysis. The bead orientations are calculated by the trajectories of the principal bending stress with the largest magnitude. The beads are projected on to the mesh of the component using geometric form functions of the desired bead cross section. A local bead ratio of 50% (defined as average area of the beads in relation to total area of the sheet) is used by the algorithm to determine the maximum moment of inertia. The proposed algorithm is numerical implemented in the optimization system TOSCA and available for being applied with the following finite element solvers: ABAQUS, ANSYS, I-DEAS, NX Nastran, MSC.Nastran, MSC.Marc and PERMAS. The optimization algorithm is successfully applied to static and dynamic real world problems like car body parts, oil pans and exhaust mufflers. In the present work several academic and industrial examples are presented.

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Johnsrud, Andrew, Juliana Craig, John H. Baird, Jay Y. Spiegel, Lori S. Muffly, James Zehnder, Robert S. Negrin, et al. "Bleeding and Thrombosis Are Associated with Endothelial Dysfunction in CAR-T Cell Therapy and Are Increased in Patients Experiencing Neurologic Toxicity." Blood 136, Supplement 1 (November 5, 2020): 32–33. http://dx.doi.org/10.1182/blood-2020-142218.

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Background Treatment with chimeric antigen receptor (CAR) T cell therapies have shown dramatic, often durable responses for relapsed/refractory B-cell malignancies. However, it can be associated with significant side effects such as cytokine release syndrome (CRS), immune effector-cell associated neurotoxicity syndrome (ICANS) and life-threatening consumptive coagulopathies. The underlying pathobiology of such hemostatic defects and their distinct clinical sequelae remains obscure. This retrospective study aims at quantifying CAR T therapy associated bleeding and thrombotic complications and their association with CRS, ICANS, and laboratory derangements. Methods 130 adult patients with DLBCL or B-ALL treated between 2017-2020 with CD19 CAR-T therapy axicabtagene ciloleucel (N=90) or a bispecific CD 19/22 CAR construct utilizing 4-1BB costimulatory domains (N=40) were analyzed to determine dynamics of coagulation parameters and platelet counts as well as incidences of bleeding or thrombosis in the first three months after CAR T infusion. Events were included if graded ≥ 2 or if intervention was required. Platelet counts and coagulation parameters were collected prior to lymphodepletion (pre-LD), day 0, 3, 7, 14, 21, 28, 60 and 90. Results 12 (9.2%) and 8 (6.2%) patients developed bleeding and thrombotic complications in the first three months after CAR-T infusion, respectively. Events are characterized in Figure 1. All bleeding events occurred between days 0-30 (median 17.5, range 8-30), while thrombotic events occurred between days 2-91 (median day 29, range, 2-91). Two (1.5%) patients experienced both bleeding and thrombosis. Bleeding events coincided with the onset of thrombocytopenia and hypofibrinogenemia, and patients who bled had lower platelet (median 22.5 vs. 47 K/uL; p=0.03) and fibrinogen (median 151 vs. 351 ug/mL; p=0.007) nadirs in the first 30 days compared to those without bleeding. Temporally, the lowest median platelet nadir occurred at day 7 in patients with bleeding events vs. day 21 in patients without bleeding, while timing of fibrinogen nadirs were at day 21 in both. Patients with bleeding episodes were more likely to be older (median age: 70 vs. 60 yrs, p=0.03), have thrombocytopenia prior to lymphodepletion therapy (median 117.5 vs. 174.5 K/uL, p=0.01), and have elevated LDH (lymphoma subgroup; p=0.07). Other lab derangements in the first 30 days seen more frequently in patients with bleeding included prolonged thrombin time (TT) (21% vs. 6%; p=0.02), PT (16% vs. 5%; p=0.06), and elevated d-dimer (16% vs. 3%; p=0.01) indicative of a consumptive process. Thrombotic events were not significantly associated with elevated or peak d-dimer values (median 4.97 vs. 2.37 ug/mL, p=0.20). Interestingly, occurrence or severity of CRS was not associated with bleeding or thrombotic events, nor was it associated with marked derangements in coagulation abnormalities. However, higher grade ICANS (grade > 3) was associated with bleeding (42% vs. 15%; p=0.038), thrombosis (50% vs. 16%; p=0.03), and evidence of endothelial activation including PT prolongation (78% vs. 35%; p<0.001), hypofibrinogenemia (57% vs. 20%; p=0.001), and trend towards elevated d-dimer (70% vs. 46%; p=0.06). 13 (10%) patients received anticoagulation for prophylaxis or therapeutic indications that predated CAR T infusion. Four started anticoagulation secondarily for thrombotic events after CAR-T infusion, and one received tissue plasminogen activator (tPA) for an acute stroke. In this group, no patients developed bleeding complications from anticoagulation. Conclusion Both bleeding (9.2%), and thrombotic (6.2%) events are observed after CAR T cell therapy, with bleeding limited to the first month in our cohort. Notably, ICANS was uniquely associated with PT prolongation, hypofibrinogenemia, and increased fibrin degradation, in addition to both bleeding and thrombosis. These results suggest that a systemic coagulopathy coincides with high grade ICANS and whether these neurologic events truly represent sequelae of widespread vascular dysfunction warrants further investigation. Anticoagulation was safe in the patients whom it was indicated. Risk factors for bleeding and thrombotic complications should be studied prospectively to develop risk-assessment models and clinical guidelines for management of bleeding and thrombosis (including prophylaxis) during CAR T therapy. Disclosures Muffly: Adaptive: Research Funding; Servier: Research Funding; Amgen: Consultancy. Negrin:BioEclipse Therapeutics: Current equity holder in private company; Magenta Therapeutics: Consultancy, Current equity holder in publicly-traded company; KUUR Therapeutics: Consultancy; Biosource: Current equity holder in private company; Amgen: Consultancy; UpToDate: Honoraria. Shizuru:Jasper Therapeutics, Inc: Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees. Meyer:Orca Bio: Research Funding. Shiraz:Kite, a Gilead Company: Research Funding; ORCA BioSystems: Research Funding. Rezvani:Pharmacyclics: Research Funding. Mackall:Apricity Health: Consultancy, Current equity holder in private company; NeoImmune Tech: Consultancy; Nektar Therapeutics: Consultancy; Allogene: Current equity holder in publicly-traded company; BMS: Consultancy; Lyell Immunopharma: Consultancy, Current equity holder in private company. Miklos:Adaptive Biotech: Consultancy, Other: Travel support, Research Funding; Kite-Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Travel support, Research Funding; Juno-Celgene-Bristol-Myers Squibb: Consultancy, Other: Travel support, Research Funding; Allogene Therapeutics Inc.: Research Funding; Novartis: Consultancy, Other: Travel support, Research Funding; Pharmacyclics: Consultancy, Other: Travel support, Patents & Royalties, Research Funding; Janssen: Consultancy, Other: Travel support; Miltenyi Biotec: Research Funding. Sidana:Janssen: Consultancy.

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"Design and Optimization of an Exhaustive Muffler and Experimentation to reduce Emission using Fly ash." International Journal of Recent Technology and Engineering 8, no. 3 (September 30, 2019): 94–100. http://dx.doi.org/10.35940/ijrte.c3891.098319.

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Exhaust gases from the combustion of the air-fuel mixture are reduced to non-harmful gases before releasing them into the atmosphere using a catalytic converter. Exhaust muffler or silencer are used to reduce noise and vibrations level due to the expansion of gases. In this research, a novel muffler is designed for 4-stroke, 125cc single-cylinder petrol engine and structural analysis are carried out for optimization using ANSYS Static Structural solver. The muffler is subjected to various pressure loads, acceleration loads, and load due to self-weight. Fatigue analysis is further carried out using stress-life approach and mean Soderberg theory of failures to determine Life, Damage, Safety factor, Biaxiality Indication, and Alternating equivalent stress under dynamic loading. Experimental analysis is carried out using an optimized muffler with fly ash as a catalyst to determine the reduction in emission. Structural analysis of the initial model was optimized by slight modification in design which reduced total deformation from 0.0379 mm to 0.0374 mm and equivalent stress from 52.878 Mpa to 50.969 Mpa. The safety factor was also increased from 1.6302 to 1.6902. Experimental results using Gas analyzer used for emission readings have shown a reduction in the emission of carbon monoxide and hydrocarbons by 21.06% and 23.07% respectively as compared to a standard muffler.

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Сусел, Н. В. "Improvement of the working conditions on productions of a chemical and a forest complex by means of noise levels reduction, created by gas dynamics devices." Известия СПбЛТА, no. 216(216) (September 19, 2016). http://dx.doi.org/10.21266/2079-4304.2016.216.166-174.

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Выявлены и проанализированы основные источники шума на деревообрабатывающих предприятиях лесохимического комплекса. Обосновывается актуальность применения устройств шумоглушения, позволяющих преобразовывать турбулентные потоки воздуха в ламинарные. Приведены материалы акустико-аэродинамических экспериментальных исследований модульных элементов глушителя, полученных на специально созданном опытном стенде. Для проведения испытаний применялась заглушенная камера установленного размера. Измерения шума проводились на выходе глушителя. В ходе экспериментов проверялась эффективность глушения шума путем преобразования турбулентных потоков в воздуховодах в ламинарные, которые не образуют завихрений внутри потока. В процессе экспериментов проверены различные комбинации соединений модульных элементов. На каждом этапе исследований определялись параметры шума в контрольных точках. Для установления показателей эффективности глушителя процедура расчета включала оценку акустических характеристик в отсутствие средств шумозащиты, оценку достижимого снижения уровней звуковой мощности при установке глушителей и оценку габаритов шумоглушителя, обеспечивающего технологические и акустические требования к месту установки. На основании полученных данных установлено, что при параллельном соединении модулей глушителя эффективность шумоглушения почти во всех диапазонах частот уменьшается с увеличением количества соединяемых модулей. Это может быть связанно с пропорциональным увеличением входного отверстия испытательной камеры при увеличении площади сечения сборной конструкции глушителя. Следует отметить, что при последовательном соединении элементов глушителя эффект шумоглушения увеличивается с увеличением количества соединяемых модулей. Анализ полученных экспериментальных данных показал эффективность применения глушителей шума, преобразующих разнонаправленные потоки воздуха в однонаправленные. In the article was identified and analyzed the main source of noise in the forest-wood-processing enterprises of the wood-chemical complex. Substantiates the relevance of the using of noise suppression devices, which permit to convert turbulent air flow in laminar.The materials of acoustic and aerodynamic experimental studies for the muffler modular elements obtained on a specially made test unit are listed. Specific size anechoic chamber was utilized for the research. Measurement of the noise was established in the outlet of the muffler. During the experiments noiseproofing efficiency was checked on the basis of transformation turbulent wind flow in laminary flow. Different combinations of connected muffler modular elements were checked. At every step of research noise parameters in control points were defined. For establishment the capability of mufflers, evaluation of acoustic characteristics in the absence of noise protection means was included in the calculation procedure. Moreover,was indicated the feasibility of the sound power levels diminishment during the installation of mufflers and was estimated size of the mufflers, which provides technological and acoustic requirements to the site of installation. This research illuminates that the utilization of parallel muffler connection helps to decrease the efficiency in almost all frequency ranges, as long as the number of bounded modules increases. This can be explained by proportional growth of the inlet of the examined chamber with an augment in a sectional area of the built-up muffler construction. Furthermore, the sequential connections of the muffler parts are increase the efficiency of noise suppression by growing the number of linked modules. To sum up, the efficiency of using of the studied mufflers are obvious.

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"Design Optimization of Muffler of an Internal Combustion Engine using Computational Fluid Dynamics." International Journal of Recent Technology and Engineering 8, no. 5 (January 30, 2020): 2922–27. http://dx.doi.org/10.35940/ijrte.e3107.018520.

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A Muffler is a gadget for lessening the measure of clamor produced by the fumes of an inner burning motor. Inner burning motors are commonly furnished with a fumes suppressor (Silencer) created by the ignition procedure to smother the acoustic beat. The direct cause of back pressure in the engine will be the stress and temperature of exhaust gases that flow through the silencer. To relieve the back pressure in the exhaust system, the engine power must be used. Execution of Muffler underneath different working state is typically acquired through design analysis. Accessibility of compressible flow execution parameters is limited, and trial testing can be cost restrictive. The mathematical fluid Dynamics analysis provides better results for this case. The ability to use analytical fluid components is a test to determine their suitability to determine the conditions of their display. The venture's goal is to examine t he gases gas stream attributes in the suppressor's current and modified structure. Our effort is to focus on enhancing the structure so that there is less back weight and silencer's expanded existence. The Computational Fluid elements investigation would be completed by utilizing CFD apparatus CFX. With parameters such as weight and temperature dissemination, disturbance power and liquid power at different load conditions, an extensive report would be done.

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"A computational fluid dynamics approach for full characterization of muffler without and with exhaust flow." Physics of Fluids 32, no. 6 (June 1, 2020): 066101. http://dx.doi.org/10.1063/5.0008340.

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Journal articles on the topic 'Dynamic muffler'

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