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Journal articles on the topic 'Attenuator'

Author: Grafiati

Published: 4 June 2021

Last updated: 6 September 2023

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1

Yuzvik, Denis A., and Maksim A. Stepanov. "An algorithm for synthesis of a film attenuator with uniform power dissipation along its length." Proceedings of the Russian higher school Academy of sciences, no. 2 (June 30, 2022): 60–69. http://dx.doi.org/10.17212/1727-2769-2022-2-60-69.

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The problem of synthesizing a film attenuator made by applying an absorbing material to a conductor is considered. Since the absorbing material has a parameter of maximum dissipated power per unit area, then when synthesizing an attenuator to attenuate high powers, the problem of exceeding the maximum dissipated power per unit area may arise. A sectional attenuator structure has been proposed, which is a set of sections having different attenuation to reduce the power dissipated per unit area. An algorithm for the synthesis of a sectional attenuator is proposed. The attenuator sections are rectangles of various widths. The attenuation distribution is performed using the Taylor series expansion of mathematical functions. The properties of the functions used to distribute the attenuation related to the problem under consideration were considered. The graphs of the dependence of power on the attenuator section are presented. Power distribution has been confirmed by simulation results. Theoretical calculations were confirmed by simulation results in the CST Microwave Studio software.

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2

Kim, Jeong-Geun, and Kang-Hee Lee. "An S/C/X-Band 4-Bit Digital Step Attenuator MMIC with 0.25 μm GaN HEMT Technology." Applied Sciences 12, no. 9 (May 7, 2022): 4717. http://dx.doi.org/10.3390/app12094717.

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In this paper, a 4-bit digital step attenuator using 0.25 μm GaN HEMT technology for wideband radar systems is presented. A switched-path attenuator topology with resistive T-type attenuators and double-pole double-throw (DPDT) switches was used to achieve both low insertion loss and phase/amplitude error. The measured insertion loss of the reference state is 2.8–8.3 dB at DC-12 GHz. The input and output return loss are less than 12 dB at DC-12 GHz. An attenuation coverage of 30 dB with a least significant bit of 2 dB was achieved at DC-12 GHz. A root mean square (RMS) amplitude error of 1 dB and a phase error of 8.5° were achieved, respectively. The attenuator chip size is 2.45 mm × 1.75 mm including pads. To the best of the authors’ knowledge, this is the first demonstration of a GaN-based digital step attenuator.

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3

Hao, Dongning, Wei Zhang, Xiubo Liu, and Yanyan Liu. "A Wideband 6-Bit Digital Attenuator in a GaAs pHEMT MMIC." Electronics 11, no. 14 (July 11, 2022): 2166. http://dx.doi.org/10.3390/electronics11142166.

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A low insertion loss, wideband 6-bit digital step attenuator is implemented in the 0.25-μm GaAs pHEMT process. Modified π- or T-type attenuator structures are adopted to expand the operation frequency bandwidth and reduce the insertion phase violation. Furthermore, the through-wafer via (TWV) is analyzed to reduce the influence of the parasitic effect on the high-frequency performance of the attenuator. The depletion mode single-gate switch transistors are used to control the on-off state of the attenuator, which provides low insertion loss and high isolation. The step of the attenuator is 0.5 dB, and the attenuation range is 31.5 dB. The measurement results show a maximum root mean square (RMS) attenuation error of 0.51 dB and RMS phase error of 6.6 degrees from DC-18 GHz. The chip area is 1.8 × 0.6 mm2.

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4

Aubakirov, Constantine Y., and Alexander V. Makeev. "DESIGNING MICROWAVE BAND ATTENUATORS AS ELECTRIC FILTERS WITH LOSSES." Interexpo GEO-Siberia 8 (May 21, 2021): 280–87. http://dx.doi.org/10.33764/2618-981x-2021-8-280-287.

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This paper presents the results of modeling attenuators with an attenuation of 1,2 dB and 1,8 dB, based on a harmonic filter with resistive inserts. Resistive inserts were introduced into the low-resistance sections of the harmonic filter, and resistive loops were connected to the high-resistance sections of the filter. An implementation of a 10 dB attenuator based on a quasi-polynomial bandpass filter with losses is proposed. The working frequency band of such attenuators reaches 4 GHz.

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5

Cui, Hong Ling, Qi Su, and En Li. "Attenuation Distribution Broadband Measurement System of Ceramic Pole Attenuator Used for TWT." Key Engineering Materials 723 (December 2016): 224–29. http://dx.doi.org/10.4028/www.scientific.net/kem.723.224.

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Ceramic pole attenuator is an important part in TWT. The performance of TWT is closely related to the attenuation distribution of ceramic pole. The measurement of attenuation distribution was a difficult problem all the time. The traditional measurement method characterize the attenuation distribution by measuring the resistance distribution. The main disadvantage of this method is that result can not characterize ceramic pole’s performance in microwave condition. In this paper we select double-ridge waveguide as measurement transmission line, and based on the classical “Transmission and Reflection Method” an attenuation distribution measurement system was developed. This measurement system provides a convenient method to get accurate attenuation distribution in microwave condition. X-band and Ku-band ceramic pole attenuators were measured, and curves of attenuation distribution were given in this paper.

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6

Mitkov, A. S., A. A. Stolyarenko, and M. G. Rubanovich. "FILM ATTENUATORS BASED ON FILTER STRUCTURES WITH DISSIPATIVE LOSSES." Issues of radio electronics, no. 4 (May 10, 2019): 84–89. http://dx.doi.org/10.21778/2218-5453-2019-4-84-89.

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The article presents the results of a study of the frequency properties of a multi-stage high-power attenuator with attenuation of 10 dB in the frequency range 0–3 GHz, obtained on a dielectric substrate made of beryllium ceramics. For its construction, microstrip filters with quarter-wave couplings and dissipative losses are used, as well as additional film resistors made in the form of trapezoidal plumes. These loops have a minimum size in the area of a short circuit. The design features of wide-band microwave attenuators of high power are determined, including the conditions for ensuring uniform distribution of the dissipated microwave power and distribution of the resonant frequencies of low-Q resonators. Equivalent circuits were compiled, which allow to determine the initial structure of the attenuator and optimize its frequency characteristics for any power level.

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7

Venkanna, B. K., and Swati B. Wadawadagi. "Experimental Investigations on Noise Attenuation of a Twin Cylinder Stationary Diesel Engine with Different Types of Mufflers." Journal of Vibration and Acoustics 121, no. 3 (July 1, 1999): 351–54. http://dx.doi.org/10.1115/1.2893987.

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Together with atmospheric and water pollution, noise pollution is threatening human society with vehicles constituting the major source of noise. The available literature on control measures (1, 2, 3) indicates purely reactive mufflers in general are of more use for fixed speed machinery and dissipative attenuators have the ability to filler out acoustic energies over a wide range of frequencies. This paper presents cm attempt made to use a combination of these major types of mufflers fitted in the exhaust line of a four stroke, twin cylinder stationary diesel engine to attenuate exhaust noise to an acceptable level. A sound attenuation of 19 dBA has been obtained for combined reactive and dissipative (Model—M2, loosely packed with glass wool) attenuator through entire the load range without affecting the engine performance and a sound attenuation of 21 dBA has been obtained for reactive (with baffle plate. Model—M3) muffler through the entire load range with a nominal increase in BSFC at higher loads.

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8

Fan, Chao, Yahua Ran, and Liqun Ye. "Ultra wideband CMOS digital T-type attenuator with low phase errors." Journal of Semiconductors 43, no. 3 (March 1, 2022): 032401. http://dx.doi.org/10.1088/1674-4926/43/3/032401.

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Abstract A proposed inductive-phase-compensation ultra wideband CMOS digital T-type attenuator design based on an analysis of minimising phase errors is presented in this letter. In a standard CMOS technology, the proposed attenuator is analytically demonstrated to have low phase errors due to the inductive-phase-compensation network. A design equation is inferred and a wide-band 4dB attenuation bit digital attenuator with low phase errors is designed as a test vehicle for the proposed approach.

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9

Zhou, Shenghao, Hangyu Jiao, Dongxu Liu, Weizhen Liu, Junzhe Lin, Qingkai Han, and Zhong Luo. "Numerical and Experimental Analysis of Pressure Pulsation Attenuator Based on Helmholtz Resonator." Applied Sciences 13, no. 14 (July 20, 2023): 8381. http://dx.doi.org/10.3390/app13148381.

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Due to the development of aviation hydraulic systems towards high pressure and high flow, the frequency range of pressure pulsation becomes wider, and the amplitude of pulsation increases. This puts higher requirements on the attenuation characteristics of the pressure pulsation attenuator. To reduce the damage caused by pressure pulsation to the pipeline, a Helmholtz-type pulsation attenuator (HTPA) is designed, which works through the Helmholtz resonant chamber. The theoretical model of HTPA is established by the method of lumped parameter method and distribution parametric method. The insertion loss is adopted to evaluate its attenuation characteristics. The internal pressure dynamic characteristics and attenuation effect of the HTPA are analyzed by simulation and experimentation. The results show that the pulsation attenuation rate δ was 40% after the installation of the attenuator. In the frequency range of 0–1000 Hz, the maximum insertion loss is 19 dB, which verifies the validity and correctness of the theoretical model.

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10

Yuan, Jun, Hang Jiang, Zheng-yan Fang, Tian-sheng Wang, Zhi Luo, Feng-xian Jiang, and Gui-hong Yin. "Design and Characteristic Analysis of a New Type of Hydraulic Pulsation Suppressor." E3S Web of Conferences 293 (2021): 02028. http://dx.doi.org/10.1051/e3sconf/202129302028.

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In order to decrease the pressure pulsation of high-pressure hydraulic system and speed up the process of high-pressure hydraulic system, a new type of hydraulic pulsation suppressor is designed. The hydraulic pulsation suppressor is designed on the basis of the structural characteristics and attenuation performance of the expansion chamber attenuator and H-type muffler. The theoretical model of the modern hydraulic pulsation suppressor is established based on the fluid theory, and the attenuation performance of the new hydraulic pulsation suppressor is analyzed. The results demonstrate that the designed new hydraulic pulsation suppressor can attenuate the pressure pulsation with a pulsation frequency of 20 Hz～2000 Hz, and attenuate the frequency bandwidth; the attenuation effect is above 50dB, and the attenuation effect is ideal.

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11

Huang Chong, Chen Hai-Qing, Liao Zhao-Shu, and Zhao Shuang. "Light attenuation coefficient of polarization attenuator at high attenuation level." Acta Physica Sinica 59, no. 3 (2010): 1756. http://dx.doi.org/10.7498/aps.59.1756.

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12

Luo, Lei, Zhiqun Li, Yan Yao, and Guoxiao Cheng. "A 6-Bit Ku Band Digital Step Attenuator with Low Phase Variation in 0.13-μm SiGe BiCMOS." Electronics 8, no. 10 (October 11, 2019): 1149. http://dx.doi.org/10.3390/electronics8101149.

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A 6-bit Ku band digital step attenuator with low phase variation is presented in this paper. The attenuator is designed with 0.13-μm SiGe BiCMOS process technology using triple well isolation N-Metal-Oxide-Semiconductor (TWNMOS) and through-silicon-via (TSV). TWNMOS is mainly used to improve the performance of switches and reduce the insertion loss (IL). TSV is utilized to provide approximately ideal global current ground plane with low impedance for the attenuator. In addition, substrate floating technique and new capacitance compensation technique are adopted in the attenuator to improve the linearity and decrease the phase variation. The measured results show that the attenuator IL is 6.99–9.33 dB; the maximum relative attenuation is 31.87–30.31 dB with 0.5-dB step (64 states), the root mean square (RMS) for the amplitude error is 0.58–0.36 dB and the phase error RMS is 2.06–3.46° in the 12–17 GHz frequency range. The total chip area is 1 × 0.9 mm2.

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13

Nie, Songlin, Lianwei Li, Hui Ji, Fanglong Yin, and Zhaoyi Dai. "Vibration Characteristic Analysis of Pressure Fluctuating Attenuator with Circular Elastic Sheets for Linear-Driving Pump." Shock and Vibration 2020 (July 24, 2020): 1–12. http://dx.doi.org/10.1155/2020/9270318.

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Aiming at the problem of pipeline vibration caused by fluids in linear-driving pump pipeline system, this paper proposed a vibration reduction method based on a pressure-fluctuating attenuator with circular elastic sheets. Firstly, a new type of pressure-fluctuating attenuator was proposed, and its working principle and frequency characteristics were analyzed. Secondly, the mathematical model of the developed attenuator was established in combination with the dynamic characteristic equations of the pipeline. Besides, the effect of relevant parameters on attenuation performance was investigated through simulation. The size and material of the circular elastic sheet were screened according to the pressure fluctuating frequency of the linear-driving pump under the rated conditions. The prototype of the pressure-fluctuating attenuator was fabricated, and the performance of the prototype in the pipeline was tested. The experimental results show that the pressure-fluctuating attenuator with circular elastic sheets has a good suppression effect on the pulsating pressure of the linear-driving pump under the rated conditions.

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14

Worrall, Mark, Sarah Vinnicombe, and David G. Sutton. "Determining paediatric patient thickness from a single digital radiograph—a proof of principle." British Journal of Radiology 91, no. 1087 (July 2018): 20180139. http://dx.doi.org/10.1259/bjr.20180139.

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Objective: This work presents a proof of principle for a method of estimating the thickness of an attenuator from a single radiograph using the image, the exposure factors with which it was acquired and a priori knowledge of the characteristics of the X-ray unit and detector used for the exposure. It is intended this could be developed into a clinical tool to assist with paediatric patient dose audit, for which a measurement of patient size is required. Methods: The proof of principle used measured pixel value and effective linear attenuation coefficient to estimate the thickness of a Solid Water attenuator. The kerma at the detector was estimated using a measurement of pixel value on the image and measured detector calibrations. The initial kerma was estimated using a lookup table of measured output values. The effective linear attenuation coefficient was measured for Solid Water at varying kVp. 11 test images of known and varying thicknesses of Solid Water were acquired at 60, 70 and 81 kVp. Estimates of attenuator thickness were made using the model and the results compared to the known thickness. Results: Estimates of attenuator thickness made using the model differed from the known thickness by 3.8 mm (3.2%) on average, with a range of 0.5–10.8 mm (0.5–9%). Conclusion: A proof of principle is presented for a method of estimating the thickness of an attenuator using a single radiograph of the attenuator. The method has been shown to be accurate using a Solid Water attenuator, with a maximum difference between estimated and known attenuator thickness of 10.8 mm (9%). The method shows promise as a clinical tool for estimating abdominal paediatric patient thickness for paediatric patient dose audit, and is only contingent on the type of data routinely collected by Medical Physics departments. Advances in knowledge: A computational model has been created that is capable of accurately estimating the thickness of a uniform attenuator using only the radiographic image, the exposure factors with which it was acquired and a priori knowledge of the characteristics of the X-ray unit and detector used for the exposure.

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15

Melior, Hendrik, Siqi Li, Ramakanth Madhugiri, Maximilian Stötzel, Saina Azarderakhsh, Susanne Barth-Weber, Kathrin Baumgardt, John Ziebuhr, and Elena Evguenieva-Hackenberg. "Transcription attenuation-derived small RNA rnTrpL regulates tryptophan biosynthesis gene expression in trans." Nucleic Acids Research 47, no. 12 (April 17, 2019): 6396–410. http://dx.doi.org/10.1093/nar/gkz274.

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Abstract Ribosome-mediated transcription attenuation is a basic posttranscriptional regulation mechanism in bacteria. Liberated attenuator RNAs arising in this process are generally considered nonfunctional. In Sinorhizobium meliloti, the tryptophan (Trp) biosynthesis genes are organized into three operons, trpE(G), ppiD-trpDC-moaC-moeA, and trpFBA-accD-folC, of which only the first one, trpE(G), contains a short ORF (trpL) in the 5′-UTR and is regulated by transcription attenuation. Under conditions of Trp sufficiency, transcription is terminated between trpL and trpE(G), and a small attenuator RNA, rnTrpL, is produced. Here, we show that rnTrpL base-pairs with trpD and destabilizes the polycistronic trpDC mRNA, indicating rnTrpL-mediated downregulation of the trpDC operon in trans. Although all three trp operons are regulated in response to Trp availability, only in the two operons trpE(G) and trpDC the Trp-mediated regulation is controlled by rnTrpL. Together, our data show that the trp attenuator coordinates trpE(G) and trpDC expression posttranscriptionally by two fundamentally different mechanisms: ribosome-mediated transcription attenuation in cis and base-pairing in trans. Also, we present evidence that rnTrpL-mediated regulation of trpDC genes expression in trans is conserved in Agrobacterium and Bradyrhizobium, suggesting that the small attenuator RNAs may have additional conserved functions in the control of bacterial gene expression.

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16

Ito, Hiroyuki. "Electronic attenuator." Journal of the Acoustical Society of America 94, no. 6 (December 1993): 3535. http://dx.doi.org/10.1121/1.407143.

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17

Stief, Reinhard. "Sound attenuator." Journal of the Acoustical Society of America 102, no. 3 (September 1997): 1279. http://dx.doi.org/10.1121/1.420003.

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18

Noguchi, Yoshihiro. "Sound attenuator." Journal of the Acoustical Society of America 92, no. 6 (December 1992): 3455. http://dx.doi.org/10.1121/1.404120.

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19

Dean, Raymond H. "Sound attenuator." Journal of the Acoustical Society of America 80, no. 2 (August 1986): 715. http://dx.doi.org/10.1121/1.393960.

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20

Hornback, Jerry Brian, and Jose Eduardo Lapore. "Noise attenuator." Journal of the Acoustical Society of America 108, no. 1 (2000): 18. http://dx.doi.org/10.1121/1.429500.

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21

Hoy, Robert W. "Sound attenuator." Journal of the Acoustical Society of America 77, no. 3 (March 1985): 1286. http://dx.doi.org/10.1121/1.392138.

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22

Yasir, Muhammad, Sergej Fatikow, and Olaf C. Haenssler. "Amplitude-Phase Variation in a Graphene-Based Microstrip Line." Micromachines 13, no. 7 (June 30, 2022): 1039. http://dx.doi.org/10.3390/mi13071039.

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A graphene-based transmission line with independent amplitude and phase variation capability is proposed. Variation of graphene’s tunable conductivity by an applied DC bias is exploited in designing an attenuator and a phase shifter. The attenuator and phase shifter are separated from each other by an interdigitated capacitor to ensure independent control of each section through an applied DC bias. The phase shifter is designed by optimizing lengths of a tapered line and an open stub for a maximum variation of input reactance with a change in graphene resistance. The attenuator is designed by two pairs of grounded vias connected to the transmission line through graphene. Variation of graphene resistance controls the signal passing through graphene pads into the ground causing attenuation. An independent variation of 5 dB of attenuation is measured along with an independent phase variation of 23 degrees in the frequency range of 4 GHz to 4.5 GHz.

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23

Liang, Peijie, Miao Zhang, Peng Wang, and Chengyu Li. "A six-digit digital attenuator working in the Sub6G band." Journal of Physics: Conference Series 2525, no. 1 (June 1, 2023): 012007. http://dx.doi.org/10.1088/1742-6596/2525/1/012007.

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Abstract A high-performance 3–6 GHz monolithic digital control attenuator chip is designed by using a 0.25 μm GaAs pHEMT process. The circuit adopts a cascade structure of 6 basic attenuation units, and 64 attenuation states are formed by controlling the on-state combination of different attenuation bits, and the attenuation structure connected in parallel to the attenuation resistor is given. The main simulation results show that the designed digitally controlled attenuator takes 0.5dB as the attenuation step, and the maximum attenuation value is 31.5 dB, an insertion loss of less than 2.55 dB, a return loss better than -15 dB, an attenuation accuracy of less than 0.5 dB for all states, an additional phase shift of less than -5°, a root mean square error better than 0.23 dB of attenuation amplitude, and chip size of 1.88 mm×1.0 mm.

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24

Zeng, Jialong, Jiaxuan Li, Yang Yuan, Cheng Tan, and Zhongjun Yu. "A C/X/Ku/K-Band Precision Compact 6-Bit Digital Attenuator with Logic Control Circuits." Electronics 11, no. 21 (November 6, 2022): 3620. http://dx.doi.org/10.3390/electronics11213620.

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This paper proposes a C/X/Ku/K band 6-bit digital step attenuator (DSA) which employs a variety of improved attenuation cells to achieve a wide bandwidth, stable amplitude variation, stable phase variation, and small area. In this paper, the improved T-type, π-type, and switched-path type topologies are analyzed theoretically and applied to different attenuation values to achieve the optimal attenuator performance. In addition, in order to reduce the complexity and to improve the stability of the overall radar system, the logic control circuit is integrated in the DSA chip in this paper. Finally, the proposed attenuator is implemented in 0.15μm GaAs technology, which has a maximum attenuation range of 31.5 dB with 0.5 dB steps. The proposed DSA exhibits a root-mean-square (RMS) attenuation error of less than 0.15 dB and an RMS phase error of less than 3°, at 4–24 GHz. The insertion loss (IL) and the area of the DSA are 4.3–4.5 dB and 1.5 mm × 0.4 mm, respectively. Benefiting from the improvements of the attenuation cells and the characteristic of GaAs technology with strong resistance to radiation and power processing capability, the proposed DSA is suitable for spaceborne radar systems.

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25

Alegre, Maria-Luisa, and Yang-Xin Fu. "Attenuation by Targeting the B- and T-Cell Attenuator." Transplantation 92, no. 10 (November 2011): 1075–76. http://dx.doi.org/10.1097/tp.0b013e3182339d6c.

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26

Wu, Jing Ping, Ling Xu, Tian Long Mei, Shuai Yi, and Li Qun Wang. "Numerical Simulation of the Interaction between Surface Waves and Horizontal Plates at Free Surface." Applied Mechanics and Materials 441 (December 2013): 456–60. http://dx.doi.org/10.4028/www.scientific.net/amm.441.456.

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A horizontal plates flock like Lotus leaves can attenuate incident surface water waves. This paper tries to simulate a numerical wave tank by FLUENT CFD software using k-ω turbulence model in a two-dimensional domain. And a 2nd-order Stokes wave is made by the boundary wave-making method, and attenuated by three kinds of horizontal plates flocks with different relative lengths (flock length/wave length). A flock of horizontal plates consists of multiple plates interspersed with gaps. However the leaves have both movement and deformation in waves, giving rise to a difficult fluid-structure interaction problem. Here a simpler case is studied, involving rigid, infinitely thin plates fixed at the still water level. The Four time steps are tried to find such appropriate time step-not only to make satisfied wave contour but also to decrease computing time. The simulations show that the amplitude of the transient wave decreases while the relative breadth increases. The velocity vectors of water partical near the attenuator are showed, and the velocities behind the attenuator do not follow a perfect wave velocity distribution.

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27

He, Zhi Yong, and Qing Hua He. "Study of Pressure Pulsations Attenuation in Hydraulic System." Advanced Materials Research 139-141 (October 2010): 1040–43. http://dx.doi.org/10.4028/www.scientific.net/amr.139-141.1040.

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A pressure pulsations reactive attenuator for controlling hydraulic system was investigated through theoretical and experimental means. The attenuator consists of many “mass-spring-damp” lumped parameter vibration systems with different natural frequency. Through the fluid-structure coupled vibration, the fluid vibrations are converted into structure vibrations. And on this device, the filter attenuation model was established and the simulation results show that, changing the system flow pulse frequency (from 186 Hz to 225 Hz) near to the resonance frequency (236 Hz) of a certain lumped parameter vibration system, the attenuator has a good effect because of component resonance attenuating hydraulic pulsation energy. To verify the correctness of simulation results, the experiment is tested and the results are homology. It provides a new practical technique for hydraulic system vibration control.

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28

Andreev, D. P., and E. I. Andreeva. "Fiber Optic Attenuator." Journal of Physics: Conference Series 2086, no. 1 (December 1, 2021): 012128. http://dx.doi.org/10.1088/1742-6596/2086/1/012128.

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Abstract A study of a bending-type fiber-optic attenuator has been carried out. It is shown that the use of G.655 - optical fiber provides the largest dynamic range of the attenuator. The spectral dependence of the bending losses was measured in a wide range of wavelengths: from 1270 to 1610 nm.

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29

Chuan, R. L., and H. Chen. "Underwater sound attenuator." Journal of the Acoustical Society of America 94, no. 6 (December 1993): 3531. http://dx.doi.org/10.1121/1.407177.

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30

Karppinen, Arto. "Fiber optic attenuator." Journal of Electronic Imaging 1, no. 1 (January 1, 1992): 104. http://dx.doi.org/10.1117/12.55181.

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31

Tatarenko, A. S., G. Srinivasan, and D. A. Filippov. "Magnetoelectric microwave attenuator." Electronics Letters 43, no. 12 (2007): 674. http://dx.doi.org/10.1049/el:20070949.

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32

Gethmann, Douglas P. "Rotary noise attenuator." Journal of the Acoustical Society of America 98, no. 5 (November 1995): 2402. http://dx.doi.org/10.1121/1.413255.

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33

Riley, Jennifer K. "Sonic boom attenuator." Journal of the Acoustical Society of America 95, no. 5 (May 1994): 2787. http://dx.doi.org/10.1121/1.409803.

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34

Vettorello, Andrea, Giuseppe A. Campo, Giovanni Goldoni, and Mauro Giacalone. "Numerical-Experimental Correlation of Dynamic Test of a Honeycomb Impact Attenuator for a Formula SAE Vehicle." Metals 10, no. 5 (May 18, 2020): 652. http://dx.doi.org/10.3390/met10050652.

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A honeycomb impact attenuator for a Formula SAE (FSAE) prototype vehicle is examined using both experimental and numerical analyses. Two common FSAE impact attenuators were compared to a new design concept, combining four layers of hexagonal honeycomb. The comparison aimed to obtain the combination of the lowest mass and highest energy absorption. The attenuator must comply with both the FSAE championship rules and further internally-defined design constraints. The work continues addressing the numerical-experimental correlation of the applied materials. Finally, the finite element models for virtual crash testing are presented and were validated through the experimental tests.

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35

Iwasaki, T. "A single-mode optical fiber attenuator for intercomparison of attenuation." IEEE Transactions on Instrumentation and Measurement 43, no. 6 (1994): 837–42. http://dx.doi.org/10.1109/19.368088.

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36

Yang, Fan, and Bin Deng. "Filtering performance and optimization of double-chamber compound hydraulic attenuators." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 232, no. 18 (September 28, 2017): 3250–62. http://dx.doi.org/10.1177/0954406217733293.

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At present, double expansion chamber structures are widely used in the field of acoustic attenuation, and two kinds of double-chamber compound structures for hydraulic attenuators are proposed in this paper. A one-dimensional analytical approach was developed to predict the pressure pulsation attenuation performance of these two structures, and comparisons of insertion loss predictions with experimental results illustrated that the one-dimensional approach is suitable for accurate prediction among the research frequency band. This approach was then used to investigate the effects of porosity and geometrical parameters on the pressure pulsation performance of these two double-chamber compound hydraulic attenuators. To optimize the pressure pulsation attenuation performance at the backwash frequency, parameter optimization was performed for these double-chamber compound structures, and a genetic algorithm based on double-precision floating-point encoding was proposed. The results showed that the range of attenuation frequency bands was widened; however, the effect on low frequency filtering characteristics was limited. The insertion loss of the second structure, which had a partially perforated tube, exhibits a superposition of dome attenuation and axial resonance in the plane wave region. By choosing the length and location of the perforated section to match resonances with the troughs of the pulsation attenuator, a desirable broadband pressure pulsation attenuation can be obtained.

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37

Rosato, Adriana, Hubert Vicarini, Alain Bonnefoy, Jean-François Chantot, and Roland Leclercq. "A New Ketolide, HMR 3004, Active against Streptococci Inducibly Resistant to Erythromycin." Antimicrobial Agents and Chemotherapy 42, no. 6 (June 1, 1998): 1392–96. http://dx.doi.org/10.1128/aac.42.6.1392.

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ABSTRACT HMR 3004 is a new hydrazono ketolide characterized by a 3-keto function instead of the cladinose moiety. The effect of this antimicrobial agent on inducible and constitutive macrolide-lincosamide-streptogramin B (MLSB) resistance was tested in a lacZ reporter system under control of severalermAM-like attenuator variants. For one constitutively resistant Streptococcus agalactiae strain, three inducibly resistant Streptococcus pneumoniae strains, and one inducibly resistant Enterococcus faecalis strain, the attenuators fused with lacZ were cloned into the shuttle plasmid pJIM2246 and the plasmid was introduced intoStaphylococcus aureus RN4220. For the wild-type attenuators, HMR 3004 was a very weak inducer, unlike its cladinose counterpart RU 6652 and erythromycin. As expected, for the fusion originating from the constitutively resistant S. agalactiaestrain, the level of uninduced β-galactosidase synthesis was high. For one S. pneumoniae attenuator, mutations in the 3′ end of the attenuator that weakened the stem-loop structure that sequesters the ribosome-binding site and start codon for ermAMmethylase could explain the high level of uninduced β-galactosidase produced. For streptococci, the activity of HMR 3004 correlated with the basal level of β-galactosidase synthesized. The weak inducer activity of HMR 3004 explained its activity against inducibly MLSB-resistant S. pneumoniae but did not correlate with the moderate activity of the antibiotic against inducibly resistant E. faecalis.

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38

Silva, Thiago de Medeiros Silveira, Aneuri Souza De Amorim, Mario Cesar Viegas Balthar, Avelino Dos Santos, Rodrigo Carneiro Curzio, Domingos D'Oliveira Cardoso, Wallace Vallory Nunes, and Raphael Rocha França. "Methodology for checking the stability of the Cesium-137 irradiator system of the Radiation Monitors Calibration Laboratory (LabCal) at IDQBRN / Metodologia para verificar a estabilidade do sistema de irradiação Césio-137 do Laboratório de Calibração de Monitores de Radiação (LabCal) no IDQBRN." Brazilian Journal of Development 8, no. 1 (January 12, 2022): 2813–31. http://dx.doi.org/10.34117/bjdv8n1-186.

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The provision for the Brazilian Army of equipment that provides reliable and safe measurements leads to the need for a metrology study of the calibration system used in the Institute's Radiation Monitor Calibration Laboratory (LabCal) of Chemical, Biological, Radiological and Nuclear Defense (IDQBRN). In order to verify the stability of dosimetry in Cesium-137, the ambient dose equivalent rate, H*(10), was experimentally obtained for certain distance settings and lead attenuators at different dates in order to compare them. To this end, the distance between the source of Cesium-137 and the ionization chamber was varied from 1000, 2000 and 3000 mm without attenuator and with lead attenuators with 15 and 32 mm. In this work, the reproducibility of the system was analyzed by comparing the scenario of equal distance and attenuator, but with a different test date. For this purpose, the correction due to the radioactive decay of the source up to a reference date was used for comparison.Furthermore,the stability of the LabCal in Cesium-137 was verified in the light of the relevant standards for exposures without attenuators and with select attenuators for the tested distances.

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39

Melior, Hendrik, and Elena Evguenieva-Hackenberg. "Trans-agierende Attenuator-RNA und Leaderpeptid in Bakterien." BIOspektrum 27, no. 2 (March 2021): 127–30. http://dx.doi.org/10.1007/s12268-021-1545-0.

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AbstractBacterial transcription attenuators are a source of small RNAs (sRNAs) and leader peptides, for which no own functions were known. However, the attenuator sRNA of the tryptophan (Trp) biosynthesis operon regulates gene expression in trans according to the Trp-availability. Moreover, the cognate leader peptide adopted Trp-independent functions. It builds antibiotic-dependent ribonucleoprotein complexes (ARNPs) for sRNA reprogramming and regulation of ribosomal and multiresistance genes.

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40

Gordon, Jonathan L., Adela S. Oliva Chavez, Dominique Martinez, Nathalie Vachiery, and Damien F. Meyer. "Possible biased virulence attenuation in the Senegal strain of Ehrlichia ruminantium by ntrX gene conversion from an inverted segmental duplication." PLOS ONE 18, no. 2 (February 17, 2023): e0266234. http://dx.doi.org/10.1371/journal.pone.0266234.

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Ehrlichia ruminantium is a tick-borne intracellular pathogen of ruminants that causes heartwater, a disease present in Sub-saharan Africa, islands in the Indian Ocean and the Caribbean, inducing significant economic losses. At present, three avirulent strains of E. ruminantium (Gardel, Welgevonden and Senegal isolates) have been produced by a process of serial passaging in mammalian cells in vitro, but unfortunately their use as vaccines do not offer a large range of protection against other strains, possibly due to the genetic diversity present within the species. So far no genetic basis for virulence attenuation has been identified in any E. ruminantium strain that could offer targets to facilitate vaccine production. Virulence attenuated Senegal strains have been produced twice independently, and require many fewer passages to attenuate than the other strains. We compared the genomes of a virulent and attenuated Senegal strain and identified a likely attenuator gene, ntrX, a global transcription regulator and member of a two-component system that is linked to environmental sensing. This gene has an inverted partial duplicate close to the parental gene that shows evidence of gene conversion in different E. ruminantium strains. The pseudogenisation of the gene in the avirulent Senegal strain occurred by gene conversion from the duplicate to the parent, transferring a 4 bp deletion which is unique to the Senegal strain partial duplicate amongst the wild isolates. We confirmed that the ntrX gene is not expressed in the avirulent Senegal strain by RT-PCR. The inverted duplicate structure combined with the 4 bp deletion in the Senegal strain can explain both the attenuation and the faster speed of attenuation in the Senegal strain relative to other strains of E. ruminantium. Our results identify nrtX as a promising target for the generation of attenuated strains of E. ruminantium by random or directed mutagenesis that could be used for vaccine production.

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41

Nagaraj, K., and R. Turner. "Precision switched-capacitor attenuator." IEEE Transactions on Circuits and Systems 34, no. 4 (April 1987): 446–47. http://dx.doi.org/10.1109/tcs.1987.1086144.

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42

Ealba, Robert H. "Automotive exhaust noise attenuator." Journal of the Acoustical Society of America 92, no. 2 (August 1992): 1197. http://dx.doi.org/10.1121/1.404021.

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43

Lee, Jung Hyun. "MEMS variable optical attenuator." Journal of the Acoustical Society of America 117, no. 5 (2005): 2686. http://dx.doi.org/10.1121/1.1932337.

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44

Kuck, John H. "Automatic attenuator for sonobuoys." Journal of the Acoustical Society of America 83, no. 5 (May 1988): 1988. http://dx.doi.org/10.1121/1.396450.

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45

Rohde, J. R., J. D. Reid, D. L. Sicking, and K. K. Mak. "Trailer truck-mounted attenuator." International Journal of Crashworthiness 13, no. 1 (January 21, 2008): 77–87. http://dx.doi.org/10.1080/13588260701731708.

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46

Fabeni, P., D. Mugnai, G. P. Pazzi, and A. Ranfagni. "Microwave variable waveguide attenuator." Review of Scientific Instruments 79, no. 6 (June 2008): 066104. http://dx.doi.org/10.1063/1.2930798.

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47

Wirt, Leslie S. "Flow duct sound attenuator." Journal of the Acoustical Society of America 79, no. 5 (May 1986): 1643. http://dx.doi.org/10.1121/1.393248.

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48

Granier, J. P., A. Frey, and D. Barat. "General Active Micromotion Attenuator." IFAC Proceedings Volumes 25, no. 22 (September 1992): 435–38. http://dx.doi.org/10.1016/s1474-6670(17)49684-4.

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49

Koshelets, V. P., S. V. Shitov, A. V. Shchukin, A. M. Baryshev, O. V. Kaplunenko, G. M. Fischer, and J. Mygind. "Superconducting mm-wave attenuator." Physica B: Condensed Matter 194-196 (February 1994): 79–80. http://dx.doi.org/10.1016/0921-4526(94)90369-7.

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50

Arian, Abbas. "LOW FREQUENCY ACOUSTIC ATTENUATOR." Journal of the Acoustical Society of America 131, no. 4 (2012): 3198. http://dx.doi.org/10.1121/1.4707483.

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