Acoustic sensing with a single coiled monomode fiber

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磁声发射信号样本熵特征量的应力检测方法研究

引用格式：陈炫宇, 龙盛蓉, 韩壮禄, 等. 磁声发射信号样本熵特征量的应力检测方法研究[J]. 中国测试，2024, 50(2): 7-13. CHEN Xuanyu, LONG Shengrong, HAN Zhuanglu, et al. Research on stress detection method based on sample entropy characteristic of magnetic acoustic emission signal[J]. China Measurement & Test, 2024, 50(2): 7-13. DOI: 10.11857/j.issn.1674-5124.2022020039磁声发射信号样本熵特征量的应力检测方法研究陈炫宇1,2，龙盛蓉1,2，韩壮禄1,2，陈学宽1,2，李志农1,2(1. 南昌航空大学江西省图像处理与模式识别重点实验室，江西南昌 330063;2. 南昌航空大学无损检测教育部重点实验室，江西南昌 330063)摘　要: 为解决在应力检测中传统磁声发射(magnetic acoustic emission, MAE)特征量易受噪声干扰的问题，提出基于磁声发射信号样本熵特征量的应力检测方法。

在研究Q235钢试样在0~400 MPa 拉伸应力状态下磁声发射信号中样本熵变化规律的基础上，分析励磁强度、嵌入维数、容限系数对磁声发射信号样本熵特征量的影响规律。

结果表明磁声发射信号样本熵特征量与应力具有良好的对应关系，并且相较于传统时域特征量(峰峰值和均方根值)，样本熵值的波动性指标分别下降89%和33%，在所选励磁条件下由样本熵值计算得到的应力值和实际应力值平均误差仅为8.5%，其受噪声干扰较小且一致性更好，更适合应用于铁磁性材料的应力检测。

关键词: 样本熵; 应力特征; 铁磁性材料; 磁声发射中图分类号: TH165;TG115.28;TB9文献标志码: A文章编号: 1674–5124(2024)02–0007–07Research on stress detection method based on sample entropy characteristic ofmagnetic acoustic emission signalCHEN Xuanyu 1,2, LONG Shengrong 1,2, HAN Zhuanglu 1,2, CHEN Xuekuan 1,2, LI Zhinong 1,2(1. Key Laboratory of Jiangxi Province for Image Processing & Pattern Recognition, Nanchang Hangkong University,Nanchang 330063, China; 2. Key Laboratory of Nondestructive Testing of the Ministry of Education, NanchangHangkong University, Nanchang 330063, China)Abstract : In order to solve the problem that the characteristic quantity of traditional magnetic acoustic emission(MAE) signal is easily disturbed by noise in stress detection, a stress detection method based on sample entropy eigenvalues of magnetic acoustic emission signals is proposed. Based on the study of the variation law of sample entropy in magnetoacoustic emission signal of Q235 steel sample under 0-400 MPa tensile stress, the effects of excitation intensity, embedding dimension and tolerance coefficient on the characteristic quantity of sample entropy of magnetic acoustic emission signal are analyzed. The results show that the sample entropy characteristic quantity of magnetic acoustic emission signal has a good corresponding收稿日期: 2022-02-15；收到修改稿日期: 2022-03-23基金项目: 国家自然科学基金(52075236)；装备预研基金(6142003190210)；江西省图像处理与模式识别重点实验室开放基金(ET202008414)作者简介: 陈炫宇（1995-），男，河南安阳市人，硕士研究生，专业方向为超声无损检测方法与信号处理。

Acoustic absorption evaluation

Original articleAcoustic absorption evaluation of high-modulus puncture resistance composites made by recycled selvagesTing-Ting Li1, Rui Wang1, Ching-Wen Lou2 and Jia-Horng Lin3,4Textile Research Journal 82(15) 1597–1611 ! The Author(s) 2012 Reprints and permissions: /journalsPermissions.nav DOI: 10.1177/0040517512454189 Abstract Glass fabric and Kevlar fabric reinforced recycled nonwovens were produced to form G-Ply and K-Ply high-modulus composites. Three types of composites — non-hot-pressed (N-), hot-pressed (H-) and laminated (L-) composites, were respectively combined by various plies, including non-treated G-Ply or K-Ply, hot-pressed G-Ply or K-Ply, and laminated-together G-Ply or K-Ply. Their acoustic absorption and puncture resistance were respectively discussed in terms of plies number, fabric interlayer, ply sequence and backed air thickness. It is found that the maximum acoustic absorption coefficient occurs at lower frequencies as increase of layers. The K-Ply N-composite shows higher porous acoustic absorption coefficient but lower puncture resistance as compared to G-Ply at more than three layers. The backed air improves acoustic absorption of N-composite almost at entire frequency and H-, L-composites at certain vibrating frequency. For combinations of one K-Ply and four G-Ply, the K-Ply sequence has a significant effect on acoustic absorption of N-composite and L-composite.Keywords needle-punched nonwoven, high-modulus fabric, recycled selvages, acoustic absorption, puncture resistanceIntroductionAs economy and industrialization develop, noise pollution has become the third pollution following air pollution and water pollution. Noise produces many harmful eﬀects to the human nervous system, such as sleeplessness, exhaustion and hypomnesis. Furthermore, digestive problems can also be caused by long-term noise. In addition, some dangerous signals are diﬃcult to perceive and thus cause accidents due to the shielding eﬀect of noise.1 The use of acousticabsorbing materials is one of the present eﬀective noise controls in automobiles, the manufacturing environment, building compartments and equipments. In addition, ﬂexible compartments often suﬀer from penetration due to sharp weapons, such as sharp spikes, broken glass and needles especially in violent places, such as prisons, police stations and mechanical assembling workshops. Acoustic-absorbing materials include porous acoustic-absorbing materials and resonance acousticabsorbing materials in accordance with absorption mechanisms.2 The common porous absorbing materialscomprise glass wool, foam, mineral ﬁber and their related composites. Even though such materials have excellent acoustic absorption, they bring about environment pollution and then harm to human health. Moreover, these materials have a high acoustic absorption coeﬃcient at high frequencies, but a low coeﬃcient at low and medium frequencies;3 their mechanical properties alone are not enough to defend against noise pollution. Resonance absorbing materials showSchool of Textiles, Tianjin Polytechnic University, Tianjin, China Institute of Biomedical Engineering and Material Science, Central Taiwan University of Science and Technology, Taichung, Taiwan 3 Laboratory of Fiber Application and Manufacturing, Department of Fiber and Composite Materials, Feng Chia University, Taichung, Taiwan 4 School of Chinese Medicine, China Medical University, Taichung, Taiwan21Corresponding author: Jia-Horng Lin, Feng Chia University, No. 100, Wenhwa Rd., Seatwen, Taichung 40724, Taiwan; China Medical Universit, No.91, Hsueh-Shih Road, Taichung 40402, Taiwan Email: jhlin@.twDownloaded from by Pro Quest on September 18, 20121598 a high absorption coeﬃcient around the vibrating frequency; thus, they are appropriate for absorbing noises at low and medium frequencies.3 Therefore, it is clear that the independent porous or resonance absorbing materials have no ability for wide-frequency noise absorption. In view of their puncture resistance property, composite materials are a good choice for improvement of both acoustic absorption and puncture resistance. In 1995, Narang4 conducted a numerical model of acoustic absorption related to ﬁber volume fraction for predicting the porous absorbing property. Afterwards, many researches were devoted to improving porous acoustic absorption at low and medium frequencies. Lou et al.5 and Tai et al.6 successfully improved acoustic absorption by increasing ﬁber density and thickness at low and medium frequencies. Lin et al.7–10 prepared nonwoven/polyurethane (PU) foam, nonwoven/PU foam/thermoplastic polyurethane (TPU) grid and nonwoven/TPU ﬁlm, and found that resonance between nonwoven and PU foam or TPU ﬁlm or grid, and between PU foam and TPU grid improves the acoustic absorption at low and medium frequencies; in addition, they found that multiple needle-punched nonwovens inserted with polypropylene (PP) selvages improves the acoustic absorption. In 2009, Ersoy and Ku ¸u ¨c ¨ k11 showed that using backing with single cotton cloth, the acoustic absorption of PET/PP nonwoven and tea-leaf-ﬁber were both enhanced at frequencies of 500–4500 Hz and 500–6300 Hz, respectively. The eﬀect of layer sequence on acoustic absorption was discussed by Nazire et al.12 In puncture resistance studies, ﬁbers used have high shear strength, high impact strength and high modulus, such as ultrahigh molecular weight polyethylene (UHMWPE), p-aramid, polybutylece terephthalate (PBT) and poly-p-phenylenebenzobisthiazole (PBO). Many studies emphasize Kevlar ﬁber and its products, and the puncture resistance property is discussed in relation to number of layers, thickness, density, modulus and structure.13–16 In addition, by means of thermoplastic-impregnate, it was found that the puncture resistance of aramid fabric signiﬁcantly improved due to windowing reduction in the fabric.17 In this paper, we intended to improve acoustic properties in wide-range frequencies; high-modulus fabric-reinforced nonwovens were prepared by the needle-punch process to meet the demand for puncture resistance by reduced windowing. Afterwards, three types of composites were prepared to review the eﬀects of hot-pressing and interlaminar mobilization on acoustic absorption and puncture resistance. In addition, parameters including the number of layers, the fabric interlayer, ply sequence and backed air gap were studied as related to these two properties.Textile Research Journal 82(15)Experimental details Experimental materialsKevlar ﬁbers taken from recycled unidirectional selvages (DuPont Company, America) had a length of 50– 60 mm. The selvages are mainly composed of 2820 Denier (D) K129 multiﬁlaments. Nylon 6 staple ﬁbers with tenacity of 10 g/d (ﬁneness: 6 Denier, length: 64 mm) were provided by Taiwan Chemical Fiber Co., Ltd, Taiwan. Sheath-core low-Tm polyester ﬁbers (Huvis Chemical Fiber Co., South Korea) were had a ﬁneness of 4 D and length of 51 mm; their sheath was low-melting-point polyester with a melting point of 110 C, and their core was general polyester with a melting point of 265 C. The low-Tm polyester ﬁbers formed spot-bonded nonwoven fabrics with higher strength and softer texture. The 0.31-mm-thick KN2600N1 glass fabric (Jinsor-Tech Industrial Corp., Taiwan), composed of 1100 Denier glass ﬁbers, had a weight of 328 g/m2 and density of 34 ends Â 26 picks/inch. The 17 ends Â 17 picks/inch 0.31-mm-thick EK10 Kevlar fabric composed of 1500 Denier Kevlar ﬁbers with a weight of 227 g/m2 was supplied by Formosa Taﬀeta Co., Ltd, Taiwan.Composite preparationNonwoven fabrics with a weight of 150 Æ 20 g/m2 were manufactured at the needle-punching density of 100 needles/cm2. They were composed of 20 wt% Kevlar ﬁbers, 50 wt% nylon 6 ﬁbers and 30 wt% low-Tm polyester ﬁbers. Afterwards, high-modulus glass fabric and Kevlar fabric were respectively inserted between double nonwoven fabrics, forming glass-fabric-reinforced ply (G-Ply) and Kevlar-fabric-reinforced ply (K-Ply) at the needle-punching density of 100 needles/cm2, as shown in Figures 1(a) and (b). Diﬀerent layers (from one layer to ﬁve layers) of G-Ply and K-Ply were used to form three types of composites – the N-composite, H-composite and L-composite. The N-composite was directly composed of diﬀerent layers of non-treated G-Ply and K-Ply during testing. The H-composite was composed of diﬀerent layers of G-ply or K-ply, respectively, hotpressed by a twin-roller hot-presser (0.5 m/min velocity, 1.5 mm distance, 160 C) during testing. The L-composite was performed by diﬀerent layers of G-ply and K-ply laminated together using a ﬂat hotpresser (5 min, 10 mm distance). The structural parameters of single G-Ply and K-Ply in diﬀerent types of composites are given in Table 1. Because composites that are too thick could bring inconvenient and uncomfortable results, the composites at most have ﬁve layers. Moreover, only single K-PlyDownloaded from by Pro Quest on September 18, 2012Li et al.1599(a) Nonwoven fabric Glass fabric G -Ply (c)(b) Nonwoven fabricKevlar fabric K-PlyThicknes1K/4GFigure 1. 1K/4G composite. The top layer is Kevlar-fabric-reinforced ply (K-Ply) (a), and the other four layers are glass-fabricreinforced ply (G-Ply) (b). The nonwoven fiber orientation of each ply is perpendicular to that of the following ply. Table 1. Parameters of single-layer glass-fabric-reinforced ply (G-Ply) and Kevlar-fabric-reinforced ply (K-Ply) in three types of composites Single-layer thickness (mm) 2.53 Æ 0.10 2.06 Æ 0.08 2.02 Æ 0.10 2.42 Æ 0.15 2.01 Æ 0.07 2.08 Æ 0.06 Area density (g/m2) 656 Æ 12 661 Æ 12 660 Æ 11 568 Æ 10 560 Æ 15 562 Æ 15 Volume density (kg/m3) 259.39 Æ 8.50 320.8 Æ 12.51 324.28 Æ 13.09 244.58 Æ 13.25 274.67 Æ 6.76 287.9 Æ 8.48at a frequency range of 128–4000 Hz at a relative humidity of 65 Æ 2% and room temperature of 20 Æ 1%. Sound waves were incident and then reﬂected by the rigid wall. The normal acoustic absorption coefﬁcient was deﬁned as ¼ Ea Ei À Er ¼ Ei Ei ð 1ÞComposites G-Ply Hot-pressed G-Ply Laminated G-Ply K-Ply Hot-pressed K-Ply Laminated K-Plywhere Ea is absorbing acoustic energy, Ei is incident acoustic energy and Er is reﬂected acoustic energy; greater represents better acoustic absorption.Puncture testBased on ASTM F1342-05, the puncture test was conducted using an Instron 5566 universal tester. Probe A (2.03-mm diameter, rounded tip radius of 2.03 mm and conical angle of 26 ) was ﬁxed on the load cell and driven at a constant rate of 508 mm/min. The samples were in the size of 100 mm Â 100 mm and were placed between two circular plates each with a 10 mm-diameter hole in the center. Five specimens were replicated for deﬁnitive puncture resistance and its standard deviation.was stacked for ﬁve-layer composites in view of the lower cost. The sequence of single K-Ply changed in ﬁve-layer composites, forming 1K/4G, 1G/1K/3G, 2 G/1K/2G, 3G/1K/1G and 4G/1K composites. ‘‘G’’ represents G-ply, ‘‘K’’ represents K-ply, and the digit preceding G or K refers to the number of plies. Figure 1(c) shows the structural diagram of the 4G/1K composite.Testing methods Acoustic absorption propertyAccording to ASTM E1050-10, the acoustic absorption coeﬃcient was tested by a 40-mm-diameter twomicrophone impedance tube, as shown in Figure 2,Results and discussion The stereomicroscope observations of high-modulus compositesThe N-composite was composed of non-treated G-Ply, including a glass fabric interlayer and nonwovens, as shown in Figure 3. After needle-punching, the verticalDownloaded from by Pro Quest on September 18, 20121600Textile Research Journal 82(15)Sample MIC MICSound SourceSound WavesImpedanceRigid WallFigure 2. Two-microphone impedance acoustical absorber apparatus.ﬁber tuft was formed to bond the fabric and nonwoven webs. Coupled with hot-pressing, the ﬁber web was spot-bonded to reinforce the nonwovens, and thus inﬂuenced the acoustic and puncture resistance property. Therefore, H- and L-composites were prepared in contrast to the N-composite. The H-composite, composed of three layers of hot-pressed G-Ply, is shown in Figure 4. The thermobonding points due to low-Tm polyester are successfully observed in puncture damage, as displayed in Figure 5.Nonwoven fabric Glass fabricFigure 3. Cross-section observations of glass-fabric-reinforced ply composed of double nonwoven fabrics and a glass fabric interlayer.Acoustic absorption property of the high-modulus composite Effect of number of layers on acoustic absorptionFigure 6 shows the acoustic absorptions of N-composites from a single layer to ﬁve layers of G-Ply. In almost the entire frequency range, the absorption coefﬁcient ﬁrstly increases to the maximum at lower frequencies and then changes to be minor (at least two layers) at higher frequencies, which shows a similar sound-absorbing property to porous sound-absorbing materials.6,11,12,18–21 That gradual increase of absorption coeﬃcient is attributed to the fact that the sound pressure makes the air in the composite nonwovens vibrate, which then results in frictional resistance between the nonwovens, and an air gap when the sound strikes the face of the nonwovens. To overcome this friction resistance, the incident sound energy is consumed as heat is dissipated in the surrounding air.20 Moreover, with the addition of G-Ply (at least two layers), the maximum absorption coeﬃcient is produced at a lower frequency; however, the maximum absorption coeﬃcient becomes lower. For ﬁve-layer G-Ply, its maximum acoustic absorption coeﬃcient decreases to 0.491. This is because as the number of layers increases, the amount of glass fabric grows accordingly. Thus, more high-frequency acousticKevlar fiberGlassFigure 4. Cross-section of the three-layer glass-fabric-reinforced ply H-composite.Thermobonding pointFigure 5. Damage observations of hot-pressed glass-fabricreinforced ply after the puncture test.Downloaded from by Pro Quest on September 18, 2012Li et al. waves are reﬂected back and, simultaneously, the acoustic energy elsewhere is conversely heightened in the closed impedance tube. Subsequently, the absorption coeﬃcient at high frequency, that is, where the1601 maximum coeﬃcient occurs, falls signiﬁcantly with the addition of G-Plies. Figure 7 displays the acoustic-absorbing property of H-composites with diﬀerent layers of hot-pressed G-Ply1.0 1-layer 0.9 0.8 0.7 Absorption Coefficient 0.6 0.5 0.4 0.3 0.2 0.1 0.0 0 500 1000 1500 2000 Frequency (Hz) 2500 3000 3500 4000 2-layer 3-layer 4-layer 5-layerFigure 6. Acoustic absorption coefficients of N-composites with different layers of glass-fabric-reinforced ply at frequencies from 128 to 4000 Hz.1.0 0.9 0.8 0.7 Absorption Coefficient 0.6 0.5 0.4 0.3 0.2 0.1 0.0 0 500 1000 1500 2000 Frequency (Hz) 2500 3000 3500 4000 1-layer 2-layer 3-layer 4-layer 5-layerFigure 7. Acoustic absorption coefficients of H-composites with different layers of glass-fabric-reinforced ply at frequencies from 128 to 4000 Hz.Downloaded from by Pro Quest on September 18, 20121602Textile Research Journal 82(15)1.0 0.9 0.8 Absorption Coefficient 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 0 500 1000 1500 2000 2500 3000 3500 4000 Frequency (Hz) 1-layer 2-layer 3-layer 4-layer 5-layerFigure 8. Acoustic absorption coefficients of L-composites with different layers of glass-fabric-reinforced ply at frequencies from 128 to 4000 Hz.at frequencies from 128 to 4000 Hz. From a single layer to three layers, the acoustic absorption coeﬃcient steadily rises up at entire frequency range; nevertheless, a relatively wider absorption peak occurs at about 1000 Hz at four or ﬁve layers. Increasing from a single layer to three layers, the absorption coeﬃcient becomes higher over the entire frequency range; however, from four layers to ﬁve layers, the absorption peak occurs at lower frequencies. Figure 8 reveals the acoustic absorption coeﬃcient of L-composites with diﬀerent layers. At a single layer or two layers, the acoustic absorption proﬁles present the same as that of ﬂuﬀy porous sound-absorbing materials. When increasing to four or ﬁve layers, the absorption coeﬃcient yields a peak before reaching an almost plateau. This is due to a combination of soundabsorbing eﬀects of porous sound-absorbing material and panel resonance. As shown in Figures 6–8, it is found that the layer increase (more than one layer), namely thickness increase, results in a higher absorption coeﬃcient at low and medium frequencies but a lower coeﬃcient at high frequency, irrespective of types of composites. That is because the low-frequency and mediumfrequency sound waves have a longer wavelength, and generate diﬀraction attenuation when encountering with composite obstacles. Due to this, the acoustic energy would be decreased more after thickening composites, which results in a higher absorption coeﬃcient.However, sound waves at high frequency are easily reﬂected on the surface of glass ﬁber. Thus, more sound energy is accumulated in the impedance tube owing to the multilayer glass fabric, and the absorption coeﬃcient reduces. Comparing N-, H- and L-composites, the N-composite presents a higher maximum absorption coeﬃcient than H-, and L-composites at the same number of layers; however, at low frequency and high frequency, the H-composite has better acoustic-absorbing performance than N- and L-composites at four and ﬁve layers. In general, the maximum absorption coeﬃcient occurs for the two-layer N-composite, as high as 0.77, and with four layers the absorption coeﬃcient of the H-composite is above 0.5 at 1000 Hz. In addition, the H-composite has better acoustic-absorbing property than the L-composite with the same number of layers. Because separated inter-plies vibrate more intensely than integrated plies, the H-composite consumes more acoustic energy than the L-composite.Effect of fabric interlayer on acoustic absorptionFigure 9 shows acoustic absorption coeﬃcients of N-composites with multilayer K-Ply. With an increasing number of layers, the maximum acoustic absorption coeﬃcient occurs at lower frequencies. For ﬁve layers of K-Ply, the absorption coeﬃcient reaches about 0.7 at 1000 Hz, higher than the same layers of G-Ply, which isDownloaded from by Pro Quest on September 18, 2012Li et al.16031.0 1-layer 0.9 0.8 0.7 Absorption Coefficient 0.6 0.5 0.4 0.3 0.2 0.1 0.0 0 500 1000 1500 2000 Frequency (Hz) 2500 3000 3500 4000 2-layer 3-layer 4-layer 5-layerFigure 9. Acoustic absorption coefficients of N-composites with different layers of Kevlar-fabric-reinforced ply at frequencies from 128 to 4000 Hz.due to higher ﬂow resistivity resulting from lower ﬁber density, based on the equation as follows:22 r0 d2 À1:5 ¼ C ð2Þwhere r0 is ﬂow resistivity, d is ﬁber diameter, is ﬁber density and C is a constant. In addition, all maximum acoustic absorption coefﬁcients reach above 0.7 for diﬀerent numbers of layers of K-Ply. With additional layers, the maximum absorption shows a minor decrease, showing that multilayer Kevlar fabric only reﬂects few acoustic waves. Figure 10 shows comparative acoustic absorption coeﬃcients of the N-composite, H-composite and L-composite, respectively, composed of ﬁve-layer K-Ply. It is found that the N-composite has a higher absorption coeﬃcient than the other two composites when the frequency is below 800 Hz and above 1000 Hz. However, in the range from 800 to 1000 Hz, the H-composite absorption is a little better than that of the N-composite, showing vibration between hotpressed plies. In addition, the L-composite acoustic property is worst of all. This is due to the hot-pressing eﬀect. The low-melting polyester after hot-pressing bonds the ﬁbers in nonwovens, blocking the air way and thus reﬂecting the acoustic energy on to the face.Effect of ply sequence on acoustic absorptionBy comparative study of Figures 6–8 and Figures 9 and 10, it is found that the same layer of K-Plyshows better acoustic absorption than that of G-Ply. Hence, due to the higher cost of K-Ply, only a single layer of K-Ply was inserted between four layers of G-Ply. Moreover, lower-density K-Ply sequences produce various transmitting paths of sound waves, impacting the acoustic property of the composites. Figures 11–13 show comparative acoustic absorption coeﬃcients of N-composites, H-composites and L-composites with diﬀerent K-Ply sequences. As shown in Figure 11, the 1K/4G, herein single K-Ply on the surface, displays the optimum acoustic absorption over the entire testing frequency. With a diﬀerent K-Ply sequence, the absorption coeﬃcients of the H-composite reveal almost the same at below 2250 Hz, as shown in Figure 12; however, the 1K/4G H-composite shows higher acoustic absorption than the other at above 2250 Hz. Nevertheless, it is interesting that the 3G/1K/1G L-composite has the optimum acoustic absorption, as shown in Figure 13. When K-Ply lies in the second and the fourth places, the acoustic absorption coeﬃcients ﬁrstly increase and then plateau; however, when K-Ply is located at the ﬁrst, third and ﬁfth places, their absorption of the L-composite shows a sharp peak before reaching a plateau. That indicates that at uneven K-Ply, the vibration due to composites themselves consumes the sound energy as heat; the L-composite at even K-Ply produces boundary layer losses to oﬀset sound energy due to the relative acoustic speed between air molecular and porous composites. Generally, the 1K/4G N- andDownloaded from by Pro Quest on September 18, 20121604Textile Research Journal 82(15)1.0 0.9 0.8 0.7 Absorption Coefficient 0.6 0.5 0.4 0.3 0.2 0.1 0.0 0 500 1000 1500 2000 Frequency (Hz) 2500 3000 3500 4000 N-composite H-composite L-compositeFigure 10. Acoustic absorption coefficients of the N-composite, H-composite and L-composite with five-layer Kevlar-fabric-reinforced ply at frequencies from 128 to 4000 Hz.1.0 0.9 0.8 0.7 Absorption Coefficient 0.6 0.5 0.4 0.3 0.2 0.1 0.0 1K/4G 1G/1K/3G 2G/1K/2G 3G/1K/1G 4G/1K0500100015002000 Frequency (Hz)2500300035004000Figure 11. Acoustic absorption coefficients of N-composites with different sequences of Kevlar-fabric-reinforced ply at frequencies from 128 to 4000 Hz.H-composites and 3G/1K/1G L-composites have the maximum acoustic absorption property. It is found from Figure 13 that the absorption coeﬃcients of 10 mm-thickness 4G/1K and 3G/1K/1G L-composites is only most about 0.25 at 1000 Hz, meaning that only 25% of acoustic energy is being absorbed. That demonstrates that a 10 mm thickness L-composite is insuﬃcient to improve theDownloaded from by Pro Quest on September 18, 2012Li et al.16051.0 0.9 0.8 0.7 Absorption Coefficient 0.6 0.5 0.4 0.3 0.2 0.1 0.0 0 500 1000 1500 2000 Frequency (Hz) 2500 3000 3500 4000 1K/4G 1G/1K/3G 2G/1K/2G 3G/1K/1G 4G/1KFigure 12. Acoustic absorption coefficients of H-composites with different sequences of Kevlar-fabric-reinforced ply at frequencies from 128 to 4000 Hz.1.0 0.9 0.8 Absorption Coefficient 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 0 500 1000 1500 2000 Frequency (Hz) 2500 3000 3500 4000 1K/4G 1G/1K/3G 2G/1K/2G 3G/1K/1G 4G/1KFigure 13. Acoustic absorption coefficients of L-composites with different sequences of Kevlar-fabric-reinforced ply at frequencies from 128 to 4000 Hz.acoustic-absorbing property at medium frequency. This is due to a sole porous absorbing structure. When the thickness of 4G/1K and 3G/1K/1G L-composites both increase to 20 mm, their maximum absorption coeﬃcient reaches up to 0.614 at880 Hz and 0.635 at 992 Hz; at a thickness of 30 mm, maximum absorption occurs at 0.584 at 880 Hz and 0.617 at 1024 Hz, as shown in Figure 14. This indicates that the eﬀect of the thickness increase on the absorption coeﬃcientDownloaded from by Pro Quest on September 18, 20121606Textile Research Journal 82(15)1.0 0.9 0.8 0.7 Absorption Coefficient 0.6 0.5 0.4 0.3 0.2 0.1 0.0 500 1000 1500 2000 2500 3000 3500 4000 Frequency (Hz) 4G/1K (20mm) 4G/1K (30mm) 3G/1K/1G (20mm) 3G/1K/1G (30mm)Figure 14. Acoustic absorption coefficients of 20 mm-thick and 30 mm-thick 4G/1K and 3G/1K/1G L-composites at frequencies from 128 to 4000 Hz.1.0 0.9 0.8 0.7 Absorption Coefficient 0.6 0.5 0.4 0.3 0.2 0.1 0.0 0 500 1000 1500 2000 2500 3000 3500 4000 10mm-thick air gap 20 mm-thick air gap 30 mm-thick air gap 40mm-thick air gapFrequency (Hz)Figure 15. Acoustic absorption coefficients of the 1K/4G N-composite backed with 10, 20, 30 and 40 mm-thick air gaps at frequencies from 128 to 4000 Hz.achieves the maximum at up to 20 mm thickness. In addition, a sharp peak is found on the absorption proﬁles, which shows that the panel resonance has become the main absorption mechanism.Effect of backed air thickness on acoustic absorptionFigures 15–17 show acoustic absorption coeﬃcients of the 1K/4G N-composite, H-composite and L-composite with 10, 20 and 30 mm-thick backed airDownloaded from by Pro Quest on September 18, 2012gaps between the composites and the rigid wall.As shown in Figure15,the acoustic absorption property improves over all frequencies when the backed air gap is thickened from10to30mm,whereas the backed air gap is conﬁned to acoustic absorption when increasing from30to40mm.When backing with a30mm-thick air gap,the max-imum absorption coeﬃcient reaches0.77at high fre-quency and above0.5from500Hz,increasing by an absorption coeﬃcient of about0.1at high frequency and0.2at500Hz,compared to that with non-backed air.This is because sound waves are reﬂected back and forth between the composites and rigid wall,damping the sound energy and then increasing additional acous-tic absorption.Figure16shows the acoustic absorption of the1K/ 4G H-composite with a backed air gap.The acoustic absorption proﬁles show a sharp peaks at648Hz (10mm thick),676Hz(20mm thick)and600Hz (30mm thick),which characterize the resonance panel vibrating at certain frequencies when sound waves are incident on the surface of composites.20Moreover,the 1K/4G H-composite with a30mm thick air gap has the maximum absorption coeﬃcient of0.71at600Hz. From Figure17,the maximum absorption coeﬃcient of the1K/4G L-composite is lower than that of H-composite shown in Figure16,which reveals a weaker panel resonance when transmitting the sound waves in the composites.In addition,it is found that after being backed with the air gap,the3G/1K/1G L-composite acoustic property displays a panel reson-ance characteristic rather than the porous sound-absorbing feature shown in Figure13,which is indi-cated in Figure18.Above all,the air gap thickness increase is conduct-ive to improving the acoustic-absorbing property over almost the entire frequency for the porous acoustic-absorbing N-composite.However,the increase in the backed air gap H-composite only improves the absorp-tion coeﬃcient at the vibrating frequency.However,for the L-composite,increasing the backed air gap shows almost no improvement.Moreover,the increase of backed air thickness is amount to the increase of composites thickness,compared with Figure11and Figures17and18.Puncture resistance property of thehigh-modulus compositeEffect of number of layers on puncture resistance Figure19shows puncture resistances of the N-compo-site,H-composite and L-composite with layers of G-Ply from one toﬁve layers.With the addition of layers,the three composites yield a gradual increase in puncture resistances.The N-composite reveals an almost steady puncture resistance at four layers of G-Ply.Moreover, the puncture resistance of the N-composite is higher than that of the other composites.Theﬁve layers the G-Ply N-composite exhibit the highest punctureFigure16.Acoustic absorption coefficients of the1K/4G H-composite backed with10,20and30mm-thick air gaps at frequencies from128to4000Hz.Li et al.1607。

Resolution 系列耳机说明书

Resolution SubwooferPowered SubwooferQUICK SETUP GUIDEGetting StartedTHE LEADER IN AUDIO ENGINEERINGThank you for your purchase of the Resolution Subwoofer, a powered subwoofer in the Resolution Series of loudspeakers.The Resolution Subwoofer delivers large amounts of sustained low frequency infor-mation without reservation. Excellent cabinet construction, robust driver selection and 650 watts of genuine Krell amplification combine to offer the huge output, speed and resolution necessary for the ultimate home theater or music system experience. The Resolution Subwoofer features a one-inch MDF enclosure with 2-inch thick front and rear baffles. The sealed box design promotes clean, accurate bass. A separate control cavity completely isolates electronics package from the driver.The single 15-inch driver has a very stiff, reinforced polypropylene cone. Peak to Peak linear travel is 1-3/8-inch, and the voice coil is extra long. Motor geometry fea-tures a focused magnetic field that promotes control and lowers distortion.The 650 watt Krell Current Mode power amplifier is a Class AB design featuring a 1000 watt transformer and 55,000 microfarads of filter capacitance. Class AB amplifi-cation provides power quickly and sustains power indefinitely, thereby providing complete control of the driver under the most demanding conditions.This document outlines the basic steps for unpacking, placing, connecting, and oper-ating the Resolution Subwoofer. The owner’s reference for this product, including a detailed description of features and the product warranty, is available on the web at:Please contact your authorized dealer, distributor, or Krell if you have any ques-tions not addressed in the owner’s reference.Follow these steps to safely unpack your subwoofer:1.Set the shipping box right side up using the arrows on the box as a guide.2 people needede a box-cutting knife and slit the tape all along the top seams of the outer carton.3.Open the flaps to reveal the inner carton.4.Slit the tape along the top seams of the inner carton.5.Open the flaps and remove the power cord and two cardboard boxes, marked “accessories” and “grille”, and set aside.6.Carefully invert the box, so that the top foam piece is on the floor. Make certain that the subwoofer stays inside the carton as you bring it to the vertical position.2 people needed7.Kneel down and grasp the top foam piece.8.Carefully lift the inner and outer cartons straight up, and off the box. The sub-woofer is still inverted.9.Remove the bottom foam piece.10.Set the inner and outer cartons and the bottom foam piece aside.11.Gently slide the protective sleeve around the subwoofer down, toward the top ofthe subwoofer and toward the top foam piece on the floor.WARNINGSTHERE ARE NO USER-SERVICE-ABLE PARTS INSIDE ANY KRELL PRODUCT.Krell Resolution Subwoofer 1UnpackingNoteSave all packing materials. If you need to ship a Resolution Series loudspeaker in the future,repack the unit in its original packaging to prevent shipping damage.This product complies with the EMC directive (89/336/EEC) and the low-voltage directive (73/23/EEC).2 Krell Resolution SubwooferNotesBe careful not to scratch the loudspeaker cabinet with the grille locator pins.Clean the grille periodically to remove accumulated dust.Gently wipe the grille from top to bottom using a soft, dry, lint-free cloth. Do not use rubber condi-tioner or solvent.Attach the grille to the loudspeaker before you play music. The Resolution Subwoofer has a snap-on grille, which is comprised of grille cord strung between 2 metal grille blocks. The grille is shipped in the cardboard box marked “grille”.Follow These Steps to Attach the Subwoofer Grille:1.Grasp the grille blocks on each end of the grille and lift the grille out of the grille box. Place the grille block with the Krell logo on the bottom front of the sub-woofer; and place the other grille block on the top front.2.Gently guide the grille locator pins into the 3 grille holes on the bottom front of the subwoofer.3.Grasp the remaining grille block,allowing it to rest between thethumb and forefinger of each hand.4.Pull firmly to stretch the grille cords,until the grille locator pins align with the 3 grille holes on the top front of the subwoofer.5.Gently guide the pins into the grille holes. You hear a click when the grille is in place.Detach the Grille Before You Repack the Subwoofer:1.Grasp the grille block attached to the top front of the subwoofer.2.Gently pull the grille block straight out until the grille locator pins slide out of the grille holes.3.Remove the grille block with the Krell logo from the bottom front of the subwoofer.4.T o protect the grille, place it in the grille box until you are ready to rein-stall it.This product is manufactured in the United States of America. Krell ®is a registered trademark of Krell Industries, Inc.,and is restricted for use by Krell Industries, Inc., its subsidiaries, and authorized agents. All rights reserved. All other trademarks and trade names are registered to their respective companies.©2004 by Krell Industries, Inc., All rights reserved12.Locate the spikes, rubber feet and locking washers, in the small cardboardbox marked “accessories”.13.Choose the set of feet you want to use on your subwoofer.14.Thread the washers onto the feet.15.Screw each foot/washer assembly into the 4 screw holes located on the bot-tom of the subwoofer.16.Carefully invert the subwoofer so that it is resting on the feet, right side up.17.Spin the washers counterclockwise up the shaft of each foot to fix the heightof the foot.18.Remove the top foam piece and protective sleeve. You are ready to positionthe subwoofer in the listening area. 2 people needed Each Resolution Subwoofer requires at least 2 inches (5 cm) of clearance on each side and in front, and at least 2 inches (5 cm) of clearance above and to the rear of the subwoofer for adequate ventilation. The subwoofer delivers excellent per-formance in nearly any location in the listening room. Two placement options fol-low:Option 1: Stereo.Place the Resolution Subwoofer midway between the left and right loudspeakers.Option 2: Home Theater. Place the subwoofer in a corner of the room, preferably one foot from any wall.AC Power Guidelines.The subwoofer has superb regulation and does not require a dedicated AC circuit. Operate the subwoofer only with the power cord supplied.PlacementTo Install Feet On Your LoudspeakerPosition the loudspeaker in the listening area before attaching the grille.Each Resolution Subwoofer is provided with 2 sets of feet: 4spikes and 4 rubber feet. The sharp, pointed spikes are ideal for carpeted floors. The rubber feet protect tile and wood floors.Unpacking , continuedTo Attach/Detach the Subwoofer Grille(not illustrated)Figure 1 Resolution Subwoofer Back Back Panel FunctionsIEC ConnectorFrequency Adjust ButtonsIMPORTANTDo not disconnect signal cables when the amplifier is on and con-nected to the loudspeaker. Doing so will cause a loud pop that may damage your components.Tighten loudspeaker binding posts by hand only.NotesWhen powering up any system,always turn amplifiers on last.When powering down, always turn amplifiers off first.When single-ended inputs are used, shorting jumpers must be inserted into pins 1 and 3 on the XLR connectors. The jumper is not necessary for the right XLR when in mono/LFE mode.Jumpers are provided in the accessory box.Krell Industries, Inc., 45 Connair Road,Orange, CT 06477-3650 USA TEL 203-799-9954, FAX 203-891-2028, E-MAIL *********************WEB SITE 4 Krell Resolution SubwooferYour Resolution subwoofer product serial number is:P/N 307978-W v 04.0Krell recommends using balanced interconnect cables which minimize sonic loss and are immune to induced noise, especially with installations using long cables.Balanced connections have 6 dB more gain than single-ended connections. Before connecting the subwoofer to your system, make sure that all power sources and components are off. Neatly organize wiring between the subwoofer and all sys-tem components. Separate AC wires from audio cable to prevent hum or other unwanted noise from being introduced into the system.There are 2 connection modes for the subwoofer, 1) Mono/LFE (LFE is active) and 2) Stereo (LFE is not active). In addition, there are 2 connection options under the Stereo mode: A) Stereo with 1 subwoofer and B) Stereo with 2 subwoofers.Choose the LFE mode to use the Resolution Subwoofer in your home theater sys-tem, driven by the LFE/sub processor output. Choose the stereo mode if you want the subwoofer(s) to interface with the main left and right loudspeakers full time, driv-en by the left and right channel outputs of your preamplifier or processor.Connect the subwoofer to AC power, and turn signal sensing off. Follow these steps: 1.To connect the subwoofer in the LFE mode (LFE is active)Put the input switch in the down position. Mono/LFE is selected. The mono/LFE input is active, and the right stereo input and output are disabled.Put the filter switch in the down position. LFE is selected. The left mono output is now disabled. Low pass and high pass filters are deactivated. Do not select filter frequencies.Connect the LFE output from the processor to the left mono/LFE input. Use either a single-ended or balanced connection.Set the level control to the three o’clock position.Use the surround processor to balance the subwoofer level with the system loudspeakers.2A.To connect 1 subwoofer in the stereo mode (LFE is not active)Put the input switch in the up position. Stereo is selected. All inputs are enabled. Put the filter switch in the up position. Low pass is selected. The filters are active.Connect the left and right preamplifier outputs to the left mono/LFE and right inputs. Connect the left/mono and right outputs to the left and right amplifier inputs. Use either single-ended or balanced connections.Set the crossover points for high-pass frequency and low-pass frequency using the frequency adjust buttons.Adjust the level control to balance the subwoofer with the system loudspeakers.2B.To connect 2 subwoofers in the stereo mode (LFE not active)Put the input switch in the down position. Mono/LFE is selected. The right stereo input and output are disabled.Put the filter switch in the up position. Low pass is selected. The filters are active.Connect the left or right preamplifier output to the left mono/LFE input.Connect the left mono output to the left or right amplifier input. Use either single-ended or balanced connections.Set the crossover points for high-pass frequency and low-pass frequency using the frequency adjust buttons.Adjust the level control to balance the subwoofer with system loudspeakers.Repeat for the second subwoofer.Connecting theResolution Subwoofer to Your System。

touchscreen 中文

Capacitive sensing
A capacitive touchscreen panel consists of an insulator such as glass, coated with a transparent conductor such as indium tin oxide (ITO). As the human body is also a conductor, touching the surface of the screen results in a distortion of the body's electrostatic field, measurable as a change in capacitance. Different technologies may be used to determine the location of the touch. The location can be passed to a computer running a software application which will calculate how the user's touch relates to the computer software.
Resistive touchscreen
A resistive touchscreen panel is composed of several layers, the most important of which are two thin, metallic, electrically conductive layers separated by a narrow gap. When an object, such as a finger, presses down on a point on the panel's outer surface the two metallic layers become connected at that point: the panel then behaves as a pair of voltage dividers with connected outputs. This causes a change in the electrical current which is registered as a touch event and sent to the controller fally refers to touch or contact to the display of the device by a finger or hand. Touchscreens can also sense other passive objects, such as a pen. However, if the object sensed is active, as with a light pen, the term touchscreen is generally not applicable. The ability to interact physically with what is shown on a display (a form of "direct manipulation") typically indicates the presence of a touchscreen.

老人和狼英语作文

老人和狼英语作文The Old Man and the WolfIn a remote village nestled in the heart of the mountains, there lived an old man whose life had been shaped by the harsh realities of the wilderness. His name was Grigori, and he had spent his entire existence in this rugged, untamed land, eking out a humble existence through a lifetime of hard work and resilience.As the years had passed, Grigori's body had become weathered and worn, his face etched with the lines of a life spent battling the elements. Yet, despite the toll time had taken, his spirit remained unbroken, his eyes still shining with a fierce determination to survive in this unforgiving landscape.One bitterly cold winter, as Grigori tended to his meager flock of sheep, he noticed a strange and unsettling sight in the distance. A lone wolf, its fur matted and its eyes gleaming with a predatory hunger, had emerged from the shadows of the forest, its sights set on the defenseless sheep.Grigori's heart raced as he realized the danger his flock was in. Heknew that the wolf, driven by the relentless demands of its own survival, would stop at nothing to claim its prey. Without hesitation, the old man grabbed his trusty rifle and set out to confront the fearsome creature, determined to protect his livelihood and the animals he had come to cherish.As Grigori approached the wolf, he could see the animal's muscles coiled, ready to pounce. The two adversaries locked eyes, each sizing up the other, the tension thick in the frigid air. Grigori steadied his aim, his weathered hands gripping the rifle with a lifetime of experience.In that moment, something unexpected happened. The wolf, instead of lashing out, let out a low, guttural growl, its eyes fixed on the old man. Grigori, sensing a strange connection, lowered his weapon, his curiosity piqued.The wolf, sensing Grigori's hesitation, took a tentative step forward, its movements slow and cautious. Grigori, intrigued by this unusual behavior, remained still, his gaze unwavering.Slowly, the wolf inched closer, its eyes never leaving the old man's face. Grigori could see the animal's ribs protruding, its body wracked with the ravages of hunger. In that moment, something shifted within the old man, a deep empathy stirring in his heart.Without a word, Grigori reached into his pack and pulled out a small piece of dried meat, offering it to the wolf. The animal hesitated for a moment, its instincts warring with the promise of sustenance. But then, with a tentative sniff, the wolf accepted the offering, its jaws closing gently around the morsel.From that day on, a remarkable bond began to form between the old man and the wolf. Grigori would regularly bring food for the animal, and the wolf, in turn, would keep a watchful eye over the old man's flock, deterring other predators from encroaching on his domain.As the seasons changed and the years passed, Grigori and the wolf became inseparable, their unlikely friendship a testament to the power of compassion and understanding. The old man would often sit with the wolf, sharing his meager meals and speaking softly to the animal, as if it were a trusted companion.In the twilight of his life, Grigori found solace in the presence of his lupine friend, the wolf's unwavering loyalty and fierce protectiveness a comfort in the face of his own mortality. And when the time came for Grigori to leave this world, the wolf stood vigil by his side, a silent guardian until the very end.The villagers, who had once viewed the wolf with fear and suspicion,now looked upon the creature with a newfound respect and admiration. They understood that the bond between the old man and the wolf was something extraordinary, a testament to the power of empathy and the ability of even the most unlikely of creatures to form deep and meaningful connections.As the years passed, the legend of the old man and the wolf grew, becoming a source of inspiration and wonder for all who heard it. And in the heart of the mountains, where the wind whispers through the trees, the spirit of Grigori and his lupine friend lives on, a timeless reminder of the transformative power of compassion and the beauty that can emerge from the most unexpected of encounters.。

Acoustic sensor

专利名称：Acoustic sensor发明人：松本美治男,藤村勝典,服部勝治,直野博之申请号：JP特願昭62-8518申请日：19870116公开号：JP特公平6-76912B2公开日：19940928专利内容由知识产权出版社提供摘要：PURPOSE:To obtain a high-reliability acoustic sensor which is easily assembled by feeding feedback light back to a single-mode optical fiber from a Fabry-Perot interferometer formed of the single-mode optical fiber and a diaphragm, and detecting the feedback light. CONSTITUTION:The incidence end surface 11r of the diaphragm is coated with a translucent film for reflection and the projection end surface is coated for nonreflection. The single-mode optical fiber 16 is coupled with a semiconductor laser and its projection end surface 16r is coated with a translucent film for reflection. The Fabry-Perot interferometer is formed of the end surfaces 11r and 16r. Detection light (i) in the optical fiber which is propagated in the core 16a of the fiber 16 from a semiconductor laser enters the interferometer and becomes repeatedly reflected interference light (k). Part of the interference light (k) is transmitted to go to external emitted light (t) and the remainder is fed back to become a signal (o) in the optical fiber. The film 11 is displaced with an acoustic signal and signal light on which intensity modulation corresponding to its is imposed is obtained. Thus, the high-reliability acoustic sensor which is easily assembled is obtained.申请人：松下電器産業株式会社,社団法人日本電子工業振興協会地址：大阪府門真市大字門真1006番地,東京都港区芝公園3丁目5番8号国籍：JP,JP代理人：小鍜治明 (外2名)更多信息请下载全文后查看。

Interfaces in Thermoplastic Composites Probed by Laser-Induced Acoustic Emission

Interfaces in Thermoplastic Composites Probed by Laser-Induced Acoustic EmissionW. H. ProsserNondestructive Evaluation Science BranchJ. A. HinkleyPolymeric Materials BranchNASA Langley Research CenterHampton, V A 23681-0001Journal of Materials Science Letters, V ol. 13 (1994), pp. 213-214The mechanical properties and durability of carbon Þber composites depend not only on the proper-ties of the constituent Þber and matrix but also on the quality of the interfacial bond. Many of the tech-niques for evaluating this bonding rely on model (e. g. single Þlament) composites (1-3). Besides being difÞcult to prepare and test, these specimens are subject to the criticism that they may not reßect actual behavior in a full-scale composite with a reasonable volume fraction of Þbers. This is an important con-sideration especially in thermoplastics, whose morphology may be sensitive to processing details.A few interface measurement techniques use actual composites, but are destructive (4-6). The ther-moacoustic technique of Wu, on the other hand, is applied to actual laminates and probes a very small area (7). Thus, although it is not entirely nondestructive, it could be used for quality control of manufactured parts, for example.This letter reports on application of Wu's technique to some well-characterized amorphous thermo-plastic composites.Unidirectional composite panels were fabricated by molding thoroughly dried solution-impregnated, drum-wound prepreg in matched metal molds. Composite Þber volume fractions were calculated from prepreg Þber areal weights. The materials studied are listed in Table I.* The two Þbers chosen have similar nominal tensile properties, but embedded single-Þlament tests (8) and fracture toughness results (9,10) indicate that they differ in their afÞnities for thermoplastic resins.An unfocused 6 watt Argon Ion laser beam was trained on a specimen for 10 seconds. Acoustic emis-sion (AE) was detected by a 150 kHz resonant AE sensor (Physical Acoustics Corporation model R15). The signals were ampliÞed 40 dB by a preampliÞer (Physical Acoustics Corporation model 1220A) which had a bandpass Þlter of 100-300 kHz. The distance from the center of the laser spot to the center of thesensor was nominally 2.9 cm along the Þber direction. The detected signals were analyzed with a conven-tional AE system (Physical Acoustics Corporation Locan-AT) which had a system gain of 20 dB and a threshold set at 26 dB. The AE system was activated 10 seconds before the laser was turned on to verify that extraneous noise was not being detected. AE threshold crossing counts were monitored during the laser heating period and for approximately 110 seconds afterwards. The total cumulative counts from two experiments at different locations on the same panel were averaged.A plot of the cumulative counts versus time data from the measurements on the PPO matrix samples is shown in Figure 1. In this Þgure, zero on the time scale corresponds to the point at which the laser was turned on. Acoustic emission began shortly after the shutter was opened. Emissions continued at a lower rate for approximately 30 seconds after it was closed, and then slowed further. After the test, a raised blis-ter several millimeters in extent surrounded the laser spot. A polished section through the laser spot shows (Fig. 2) that the laser damage penetrated through several plies.Table II shows the correlation between total counts and composite transverse ßexural strength, which is thought to be a reliable indicator of Þber/matrix interfacial bond strength (11). We note Þrst of all that the thermoacoustic data are not comparable between the two resin systems. This was expected since the specimens were different in size and shape. For each resin system, however, the material with the lower strength gave the higher acoustic output. The relative magnitude of the acoustic output does not seem to directly reßect the mechanical strength, but there is no a priori reason that it should.These results suggest that the technique may be a useful tool to assess interfacial bonding in thermo-plastic composites. Future studies will seek to identify the mechanisms that lead to acoustic emission under these conditions.References[1]Broutman, L. J.: "Measurement of the Fiber Polymer Matrix Interfacial Strength," Interfaces inComposites, ASTM STP 327, Amer. Soc. for Testing Materials, Philadelphia, PA, 1963, p. 133.[2]Miller, B., Muri, P. and Rebenfeld, L.: "A Microbond Method for Determination of the ShearStrength of a Fiber/Resin Interface," Compos. Sci. and Technol., 28, 17(1986).[3]Drzal, L. T., Rich, M. J. and Lloyd, P. F.: "Adhesion of Graphite Fibers to Epoxy Matrices-I TheRole of Fiber Surface Treatment," J. Adhesion, 16, 1(1983).[4]Mandell, J. F., Grande, D. N., Tsiang, T. H. and McGarry, F. J.: "ModiÞed Microdebonding Testfor Direct Insitu Fiber/Matrix Bond Strength Determinations in Fiber Composites," ASTM STP 893, Test and Design, 7th Conf., J. Whitney, ed., Philadelphia, PA, 1986, p. 87.[5]Carman, G. P. , Lesko, J. J., Reifsneider, K. L. and Dillard, D. A. "Micromechanical Model ofComposite Materials Subjected to Ball Indentation", J. Compos. Mater. 27(3), 303 (1993) [6]Sato, N and Kurauchi, T., "Effect of Þbre sizing on composite interfacial deformation studied bythermo-acoustic emisssion measurement", J. Mater. Sci. Lett. 11, 362 (1992)[7]Wu, W. L.: "Thermoacoustic Technique for Determining the Interface and/or Interply Strengthin Polymeric Composites," SAMPE J., 26(2), 11(1990).[8]W. D. Bascom, R. M., Jensen and L. W. Cordner, Int'l. Conf. on Composite Materials (6th:1987, London) F. L. Mathews, ed. London: Elsevier, p. 5, 424.[9]J.A. Hinkley, J. Reinf. Plast. Compos. 9, 470 (1990)[10]Hinkley, J.A. "Effect of Fiber-Matrix Adhesion on Interlaminar Fracture Toughness of Graphite Thermoplastic Composites," in Composite Applications, T. L. Vigo and B. J. Kinzig, eds. VCH Publishers, New York, 1992, p.267[11]Adams, D. F., King, T. R. and Blackletter, D. M.: Compos. Sci. and Technol., 1991.aHercules Inc. bHysol GraÞl.c Bisphenol A polycarbonate (GE, Lexan 101).d Ply(2,6-dimethyl phenylene oxide) (GE, Noryl).* Certain commercial materials are identiÞed in this letter in order to specify adequately the experimental procedure. In no case does such identiÞcation imply endorsement by NASA.Table 1: Composite MaterialsFiber Matrix Fiber V olume(%)Panel Thickness(mm)AS4 a PC c 59.4 3.5XAS b PC 63.2 3.6AS4PPO d 49.7 1.9XASPPO50.52.0Table 2: Thermoacoustic and Mechanical ResultsFiber Matrix 90 Degree Flexural Strength,MPa(+/- standard deviation)Acoustic Counts AS4PC 42.0 +/- 0.6400XAS PC 14.2 +/- 1.4520AS4PPO 66.4 +/- 1.63600XASPPO79.9 +/- 3.22100Figure 1Thermo-acoustic output from two materials systems as a function of time. La-ser was on for the Þrst 10 seconds.Figure 2Optical micrograph of polished cross-section of specimen after test. Full lami-nate thickness (1.9 mm) is shown.010002000300040005000020406080100120C u m u l a t i v e C o u n t sTime (s)AS4/PPO XAS/PPO。

石油涉外钻井英语-沙特阿美常用缩略词-对照表

Abbreviation Detail+VE PositiveA/D Analog/DigitalAACE American Association of Cost Engineers AAR After Action ReviewABC Antecedents, Behavior, Consequences ABHD Abu Hadriya AramcoABJF Abu Jifan AramcoABL Alternate Borehole LinerABQQ Abqaiq AramcoABR Additional Budget RequestABSF Abu Sa'fah AramcoAC Alternating CurrentAC Alternating Current or Air Conditioning Aramco ACC Acceptable Ceiling Concentration Aramco ACD Above chart datumACGIH American Conference Of Governmental Industrial Hygienists AramcoACI American Concrete Institute AramcoACS Anti-Collision System AramcoACT Accident Control TechniqueACV Approved Contract ValueAD Assistant DrillerADM Arrow Diagram Method AramcoADS Applications Software Development System AEA Asia Emergency AssistanceAED Automated External DefibrillationAEDC Award Engineering/Design ContractAEIC Association of Edison Illuminating companies AELB Atomic Energy Licensing ActAEOS All Employees Opinion SurveyAFBMA Anti-Friction Bearing Manufacturers Association AramcoAFC Approved for Construction; Automatic Frequency Control AramcoAFE Authorisation for expenditureAFE Approval for ExpenditureAFIS Automated Fingerprint Identification System AFNOR Association Francaise de Normalization AGA American Gas AssociationAGC Automatic Generation Control; Associated General ContractorsAGMA American Gear Manufacturers Association AH Arabian Heavy Crude OilAH Along holeAHBDF Along hole below derrick floorAHBRT Along Hole Below Rotary Table Datum line from which measurements are takenAHBTHF Along hole below tubing head flange AHD Along hole depthAHORT Along hole original rotary tableAI Artificial IntelligenceAIMS Aramco IMS SystemAIO Area ID OfficeAISC American Institute of Steel ContructionAISOD Area Industrial Security OperationsDepartmentAITD Air Information Technology DepartmentAKO Adjustable kick-off sub (directional drillingtool)AL Arabian Light Crude OilALARP As Low As Reasonably PracticableAM Arabian Medium Crude Oil; Amplitude Modulation AMC Area Maintenance CenterAMRS Advanced Mobile Radio SystemANDR ' Ain Dar (Ghawar) AramcoANSI American National Standards InstituteANSI American National Standards Institute API American Petroleum Institute AramcoANSI American National Standards InstituteAramcoANSI American National Standards Institute(previous ASA)AOA Asian and Other Arab Employees Aramco AOB Any Other BusinessAOC Aramco Overseas Company AramcoAOSM Arab Organization of Standardization &Materials AramcoAOV Air Operated Valve AramcoAPD Automated Piping Design AramcoAPI American Petroleum InstituteAPL Annulus Pressure LossAPNE Apprenticeship Program for Non-Employee APP As per programmeAPP Arabian Project Proposal or AssociatedProfessional Program AramcoAPS Applications Software AramcoAR Automated RoughneckARP Asset Reference PlanARPR Annual Review of Petroleum ResourcesASA American Standards Association (now ANSI) ASA Anchor Seal Assembly1ASAP As Soon As PossibleASC Aramco Services Company in Houston ASCE American Society of Civil Engineers ASCII American Standard Code for Information Interchange AramcoASCL Acoustic Super Combo LogASHRAE American Society of Heating, Refrig. & Air Condit. EngineersASME American Society of Mechanical Engineers ASR Appraisal & Strategy ReviewASS Asset ManagementAssy AssemblyASTM American Society for Testing and Materials ASTM American Society-for Testing MaterialsAT Audit TeamATB All Trunks BusyAUP Average Unit PriceAVG AverageAVO Visa On ArrivalAWG American Wire GaugeAWO Additional Work OrderAWPA American Wood Preservers Association AWS American Welding SocietyAWWA American Water Works AssociationAzim Azimuth (compass bearing)B/D Barrels per dayB/H Bent housing (directional drilling tool)B/O Break outBA Breathing ApparatusBAA Business Alignment AreaBALS Baker Atlas Logging ServicesBB Budget Brief AramcoBBL Barrelbbls/d Barrels per daybbls/min Barrels per minuteBBS Behavior Based Safety (WFT)BCD Below chart datumBCOT Bintulu Crude Oil TerminalBDF Below derrick floorBDO Baram Delta OperationsBDT Bulk Data TransferBFO Beneficial OccupancyBG Back groundBGG Background gasBGT Borehole geometry toolBHA Bottom hole AssemblyBHC Borehole compensated sonic logBHCT Bottom-Hole Circulating TemperatureBHD (Type of packer)BHP Bottom Hole PressureBHP Brake horsepowerBHST Bottom-Hole Static TemperatureBHT Bottom hole temperatureBI Number Budget Item Number AramcoBIF Bintulu Integrated FacilitiesBIM Business Interface ManagerBISR Budget Item Summary Report AramcoBJ Blast jointBLC Big Lever ClubBLIND A Blank FlangeBO E xplosive service (back-off)BOE Barrel of Oil EquivalentBOP Blowout PreventerBOP Blowout Preventer （Prevention of gas blow out from well）BOP Blow out PreventersBOPD Barrels of Oil Per Day AramcoBOPE Blow Out Prevention EquipmentBOPs Blowout Preventer StacksBP Bridge plugBP Business PlanBPC Bean performance curveBPCD Barrels Per Calendar DayBPD Barrels Per DayBpf Blow per footBPH Barrels per hourBPM Barrels per minuteBPR Bottom Pipe RamBPS Bytes Per SecondBPV Back Pressure ValveBPV Backpressure valveBS Base sedimentBS & W Base sediment and waterBSI British Standards InstitutionBSIT Basit AramcoBSP Brunei Shell PetroleumBTFS Basic Training For SupervisorsBTI Big Ticket ItemBTM BottomBTM Business Technology MappingBTU, Btu British thermal unitBU Business Unit2BU Bottoms up (circulating)BU Build up (pressure, temperature, inclination) BUPs Business Unit PlansBUS Build up section (of a deviated well)BV Ball valveBWPD Barrels of Water Per DayC&C Circulate & ConditionC/R Change RequestC/R Construction/RepairC/w Comes withC2V Capital to ValueCA Capital AllocationCA Corporate AffairsCAD Computer Aided Drafting AramcoCADD Computer Aided Drafting & Design Aramco CALM Catamery anchor leg mooringCAMA Centralized Automatic Message Accounting CAO Certified Acceptance by OperationsCAO Computer applications for operationsCAO Computer assisted operations (Obsolete) CAPEX Capital Expenditure AramcoCAPO Computer assisted production operation CAPS Corrective Action Preventive SystemCAR Campaign Action RegisterCART CAM ActuatedCAS Chemical Abstract ServiceCAT Corrective Action TeamCB Control BuildingCBBL Core BarrelsCBD Competency Based DevelopmentCBHP Closed in bottom hole pressureCBHT Closed in bottom hole temperatureCBL Cemented Bond Log To test the integrity of the cementingCBP Country Business PlanCCC Commodity Classification Code Aramco CCEI Common Class Expansion Indices Aramco CCIR International Radio Consulative Committee CCIS Common Channel Interoffice Signalling CCL Casing collar locatorCCN Catalog Classification NumberCCO Current Cost OutlookCCOS Construction Camp Office ServicesCCR Continuing Certification RequirementCCS Computer and Communication Services CCSD Central Community Services DepartmentCD C hart datumCDC Central Dispatch CenterCDOI Communications Department OperatingInstructionsCDPNE College Degree Program for Non-Employee CDPP Circulating Drill Pipe PressureCDR Critical Design ReviewCDS Central Dispatch SystemCE Chief EngineerCE Capital EmployedCEC Change Evaluation CommitteeCEMA Conveyor Equipment ManufacturersAssociationCEO Chief Executive OfficerCEP Current Estimated PotentialCERCLA Comprehensive EnvironmentalResponse, Compensation, and Liability Act Aramco CERP Capital Expenditure Review PanelCESP Conceptual Estimate Scoping PaperCESR Computer Equipment Service RequestCET Cement evaluation toolCFP Capital Facilities PlanCFR Code of Federal Regulations (USA) Aramco cft Cubic feetCG Casing gun (shaped charge perforator)CGA Compressed Gas Association (USA)CGS Chevron Geothermal SafetyCGT Combustion Gas TurbineCGTG Combustion Gas Turbine GeneratorCHH Casing head housingCHP Casing head pressureCHS Casing head spoolCHT Casing head tensionCI Close(d) inCIBHP Closed in bottom hole pressureCIBHT Closed in bottom hole temperatureCIF Community and Industrial FacilityCIIP Condensate Initially In PlaceCirc CirculateCIS Contract Information System (now SAP)CIS Customer instrument serviceCITHP Closed in tubing head pressureCITHT Closed in tubing head temperatureCL, C/L Control lineCLFL Choke Line Friction LossesCM Capability Management/ Manager3CMC Crisis Management CentreCMC Chronic Medical Conditions Aramco CMC Carboxy methyl celluloseCMT CementCMT Crisis Management TeamCMT Construction Management TeamCNG Compressed Natural GasCNL Compensated neutron logCNPC China National Petroleum CorporationCO Change OrderCOB Close Of BusinessCoEs Centres Of ExcellenceCOMM OPS Communications Operations DepartmentCompl Complete(d), completionCONT, C ont’d ContinuedCOPES Cost Planning and Evaluation System CORAL Cost Reduction Alliance MalaysiaCOS Computer Operations and SupportCOSHH Control of substances hazardous to health COT Character Oriented TerminalCP Casing pressureCP Conductor pressureCP Conductor Pipe, Casing PressureCP&B Capital Programs & Budgets Aramco CPAR Corrective Preventative Action Request CPC Corporate Planning Committee Aramco CPC Computer production controlCPCP Communications and Process Computer PlanningCPD Corporate Planning DepartmentCPDS Control Pressure Drilling ServicesCPDT Control Pressure Drilling & TestingCPH Baker Oil Tools tie back packerCPO Corporation Planning OrganizationCPR Cardiopulmonary ResuscitationCPS Completion and Production Services Division CPU Central Processing UnitCR Company RepresentativeCRCC Contract Review and Cost ComplianceCRG Control Risks GroupCRP Commercial Review PanelCRS Computerized Reporting SystemsCRT Cathode Ray TubeCS Construction StartCSA Customer Service AgreementCSC CORAL Steering CouncilCSES Cable Sidedoor Entry SubCSF Critical Success FactorCsg CasingCSI Customer Satisfaction IndexCSL Computer Security LiasionCSO Complete Shut OffCSR Company Site RepresentativeCSSM Construction Support Services Material CST Casing seat testCSUD Construction Start-up DateCT Coiled tubingCT Check tripCTC Central Tender CommitteeCTD Coiled Tubing DrillingCTHP Closed in tubing head pressureCTHT Closed in tubing head temperatureCTI Cooling Tower InstituteCTS Composite Tubular SystemsCTS Construction Technical SupportCTT Cup type testedCTT Cup type testerCTU Coiled Tubing UnitCW, C/W Complete withCWOP Completing the well on paperCWP Contractor's Work PlanCYA Cover your arse (political astuteness and insurance…)D & I Diversity and InclusivenessD & O Development & OperationsD&WOOD Drilling and Workover OperationsDepartmentsD-A Digitial to AnalogDAQ Data AcquisitionDASD Direct Access Storage DeviceDAV Data Above VoicedB DecibeldBA Decibels using the A-Weighted scaleDBM Design Basis MemorandumDBSP Design Basis Scoping PaperDC Drill CollarDC Direct CurrentDCC Disaster Control CenterDCCS Drilling Cost Control SystemDCLM Direct Charge List of MaterialsDCS Distributed Control System4DD Directional DrillerDD Depth determinationDDD Direct Distance Dial AramcoDDM Data & Document ManagementDDOR Daily Drilling Operations ReportDDS Document Distribution SystemDEL Direct Exchange LineDEMA Diesel Engineer Manufacturers Association DEPCO Dammam Electric Power CompanyDF Drilling floorDFE Derrick floor elevationDHALPD Dhahran Area Loss Prevention Division DHYN Duhaynah AramcoDID Direct Inward DialingDIH Drilling Information Highway.DIL Dual induction laterologDIMS Drilling Information Management System Directional ( O ) Orientate Same as 'sliding' drilling Directional ( R ) RotateDIS Downhole and Industrial ScreensDLL Dual laterologDLS Dogleg SeverityDM Driller's MethodDNV Det Norske Veritas 挪威船级社DO Drop off section (in a deviated well)DOBIS/LIBIS Dortmunder Bibliothek system/Leuvens Integraal Bibliotheek SystemDOD Direct Onward DialingDOE Department of EnergyDOE Department of EnvironmentDOI U. S. Department of Interior AramcoDOL U. S. Department of Labor AramcoDOSH Department of Occupational Safety & Health DOT U. S. Department of Transportation Aramco DOX Direct Overhead Expense AramcoDP Drill PipeDP Dynamically PositionedDP Dial Pulse•5。

枕下乙状窦后入路内听道后壁磨除的研究进展

·综述· 枕下乙状窦后入路内听道后壁磨除的研究进展李鑫吕璇陈刚【摘要】听神经瘤是桥小脑角最常见肿瘤，随着科学技术的发展，其诊断率和治疗手段不断得到改善，但显微外科手术依然是其主要治疗手段。

枕下乙状窦后入路行肿瘤全切需要磨除内听道后壁，但受空间位置等解剖因素的限制，磨除内听道后壁过程较为困难。

目前术者主要依据影像学图像结合显微外科技术指导术中磨除内听道后壁。

本文对磨除内听道后壁相关解剖结构和其研究进展作一综述。

【关键词】神经瘤，听；内听道；乙状窦后Advancement of drilling posterior wall of the interal auditory canal through the retrosigmoid approachLi Xin, Lyu Xuan, Chen Gang. Department of Neurosurgery, the Second Hospital Affiliated to SoochowUniversity, Suzhou 215004, ChinaCorresponding author: Chen Gang, Email: jhy_501@【Abstract】Acoustic neuroma is the most common tumor in the cerebellopontine angle. Thediagnostic yield and treatments of acoustic neuroma have been improved with the development of scienceand technology. However, the microsurgical technique is still the main treatment. Internal auditory canalwas opened to remove the tumor totally during resecting acoustic neuroma under the retrosigmoidapproach; it is difficult to drilling posterior wall because the space of cerebellopontine angle is narrow.Now the majority of surgeons according to the images to drilling posterior wall of the interal auditorycanal. Here was to make a review on the concept of the internal auditory canal and its adjacent structuresand the studies in drilling posterior wall of the interal auditory canal through retrosigmoid approach.【Key words】Neuroma, acoustic; Interal auditory canal; Retrosigmoid听神经瘤又称前庭神经鞘瘤，是桥小脑角最常见肿瘤，占颅内肿瘤的6%～8%，占桥小脑角肿瘤的80%～90%[1]。

音乐器具的英语作文

音乐器具的英语作文Title: Exploring the World of Musical Instruments。

Music is a universal language that transcends barriers and connects people from different cultures and backgrounds. At the heart of music are the instruments, each with its unique sounds and characteristics. In this essay, we will delve into the fascinating world of musical instruments.Firstly, let's explore string instruments. These instruments produce sound through the vibration of strings. The violin, for example, is a quintessential string instrument known for its melodious tones. Its smaller cousin, the viola, has a deeper sound, while the cellooffers rich and resonant tones. The double bass, with its towering presence, provides the low-end foundation in orchestral settings. Other string instruments include the harp, guitar, and ukulele, each offering its own distinct timbre and playing style.Next, we encounter wind instruments, which generate sound by vibrating air within a tube. The flute, a memberof the woodwind family, produces clear and agile melodies. The clarinet and saxophone offer a wide range of tones,from warm and mellow to bright and brassy. Brass instruments, such as the trumpet, trombone, and tuba,create bold and powerful sounds through the buzzing of lips into a mouthpiece. The French horn, with its coiled tubing and unique timbre, adds depth and richness to orchestral compositions.Percussion instruments provide rhythm and texture to music through the use of striking, shaking, or scraping.The drum kit, comprising various drums and cymbals, formsthe backbone of many contemporary music genres, driving the beat and adding dynamics. The xylophone and marimba produce bright and percussive tones, while the timpani, or kettle drums, offer majestic and resonant sounds in orchestral pieces. Other percussion instruments include the tambourine, triangle, and glockenspiel, each contributing to the rhythmic tapestry of music.In addition to these traditional instruments, modern technology has given rise to electronic instruments, which utilize electronic circuits and digital interfaces to produce sound. Synthesizers, samplers, and drum machines enable musicians to create an endless array of sounds and textures, pushing the boundaries of music production and composition. Electronic keyboards offer versatility and convenience, with the ability to replicate the sounds of various acoustic instruments.Furthermore, there are folk and traditional instruments from cultures around the world, each with its own unique history and significance. The sitar and tabla from India, the shamisen from Japan, and the djembe from West Africa are just a few examples of the rich diversity of musical traditions. These instruments not only serve as musical tools but also carry cultural heritage and storytelling.In conclusion, musical instruments are the building blocks of music, allowing artists to express themselves creatively and connect with audiences on a profound level. Whether it's the soaring melodies of a violin concerto, thedriving rhythms of a drum solo, or the ethereal sounds of electronic synthesis, each instrument brings its own voice to the symphony of human expression. As we continue to explore the world of music, may we appreciate the beauty and diversity of musical instruments and the transformative power of music itself.。

空间差分干涉的光纤分布式水下声波测量

空间差分干涉的光纤分布式水下声波测量董杰【摘要】To detect weak underwater acoustic signal over large areas ,an optical Distributed Acoustic Sensing(DAS) scheme based on space difference of Rayleigh backscattering was presented .In thisscheme ,Rayleigh backscattered light with phase changes induced by the acoustic signal along a single-mode sensing fiber was split and fed into an imbalanced Michelson interferometer .Adjusting the path difference of the imbalanced Michelson interferometer ,the Rayleigh backscattered light interference of different lengths of adjacent space segments along the sensing fiber was realized .Subsequently ,the phase information including the acoustic signal was demodulated by the 3 × 3 coupler demodulation technology .An underwater acoustic wave measuring system based on DAS was implemented ,which can not only locate the two acoustic positions accurately in real time ,but also restore the amplitude ,frequency and phase of sound waves .In addition ,the acoustic phase sensitivity is -148 .8 dB (re rad/μPa) at 1 kHz ,and the frequency response flatness at frequencies ranging from 100 Hz to 1500 Hz is within 1 .2 dB .The experimental results confirm that the novel Φ-OTDR technology can enable quantitative measurements of multiple acoustic information in real time .%为了实现大范围的水下微弱声波探测,提出了一种基于后向瑞利散射空间差分干涉的光纤分布式声波检测(DAS)技术.声波振动引起单模传感光纤中后向瑞利散射光的变化,将含有声波信息的后向瑞利散射光注入到非平衡迈克尔逊干涉仪,调节干涉仪的臂长差实现不同长度的相邻空间段的后向瑞利散射光干涉,然后采用3×3耦合器解调技术解调出相位信息,实现声波信号的测量.实验搭建了一套基于DAS 技术的水下声波测量系统,该系统不仅能够实时准确定位两个声波位置,还能还原声波的幅值、频率、相位等信息,并且实现了1 kHz情况下的-148.8 dB(re rad/μPa)水下声压相位灵敏度,100~1500 Hz频率的频响平坦度在1.2 dB之内.实验结果证实DAS技术能够实时快速地实现多个声波信息的定量测量.【期刊名称】《光学精密工程》【年(卷),期】2017(025)009【总页数】7页(P2317-2323)【关键词】光纤传感;后向瑞利散射;空间差分干涉;非平衡迈克尔逊干涉仪;声压相位灵敏度【作者】董杰【作者单位】山东青年政治学院信息工程学院,山东济南250103【正文语种】中文【中图分类】TP212.1;TN253Abstract： To detect weak underwater acoustic signal over large areas，an optical Distributed Acoustic Sensing(DAS) scheme based on space difference of Rayleigh backscattering was presented. In this scheme，Rayleigh backscattered light with phase changes induced by the acoustic signal along a single-mode sensing fiber was split and fed into an imbalanced Michelson interferometer. Adjusting the path difference of theimbalanced Michelson interferometer， the Rayleigh backscattered light interference of different lengths of adjacent space segments along the sensing fiber was realized. Subsequently， the phase information including the acoustic signal was demodulated by the 3×3 coupler demodulation technology. An underwater acoustic wave measuring system based on DAS was implemented， which can not only locate the two acoustic positions accurately in real time， but also restore the amplitude， frequency and phase of sound waves. In addition， the acoustic phase sensitivity is -148.8 dB(re rad/μPa) at 1 k Hz， and the frequency response flatness at frequencies ranging from 100 Hz to 1 500 Hz is within 1.2 dB. The experimental results confirm that the novel Φ-OTDR technology can enable quantitative measurements of multiple acoustic information in real time.Key words： optical fiber sensing； Rayleigh backscattering； space difference； imbalanced Michelson interferometer； acoustic phase sensitivity水声信号在建筑、地球物理和军事领域具有重要应用[1]，通常采用光纤水听器进行测量。

竖起耳朵作文600字记叙文

竖起耳朵作文600字记叙文英文回答：In the realm of auditory perception, where sounds weave a tapestry of information and experiences, the ears stand as sentinels, ever alert and ready to capture the nuances of the world around us. Their intricate structure and exquisite sensitivity allow us to navigate our acoustic environment, discern the complexities of speech, and appreciate the beauty of music.When we "prick up our ears," we instinctively heighten our attention to sound, sharpening our ability to locate the source, interpret its meaning, and respond accordingly. This reflexive action, often accompanied by a subtle twitching of the ear muscles, is an evolutionary adaptation that has served us well in avoiding danger, detecting opportunities, and connecting with our surroundings.The ears are remarkable transducers, converting soundwaves into electrical signals that are transmitted to the brain for interpretation. Each ear consists of an outer, middle, and inner chamber, each playing a specific role in the auditory process. The outer ear, composed of theauricle (the visible part) and the ear canal, directs sound waves into the middle ear. The middle ear, containing the eardrum, ossicles, and Eustachian tube, amplifies and transmits sound vibrations to the inner ear.The inner ear, or cochlea, is a coiled structure filled with a fluid and lined with sensitive hair cells. As sound vibrations reach the cochlea, they cause the hair cells to move, generating electrical signals that are transmittedvia the auditory nerve to the brain. The brain then interprets these signals, allowing us to perceive the pitch, loudness, and direction of the sound.Beyond their primary auditory function, the ears also play a crucial role in balance. The vestibular system, located within the inner ear, contains fluid-filled canals and a sensory organ called the saccule. These structures detect head movements and changes in acceleration,providing us with a sense of spatial orientation and equilibrium.The ears are not only physiological marvels but also conduits of emotional expression. The ability to hear enables us to connect with others through language, music, and other forms of sound. It fosters empathy, understanding, and the sharing of experiences. The loss of hearing,whether temporary or permanent, can have a profound impact on an individual's quality of life, affecting their social interactions, education, and overall well-being.中文回答：竖起耳朵，是我们下意识的一种行为，意在提高我们的听力灵敏度，以便更好地捕捉周围环境中的声音信息。

叫醒你的耳朵作文500字

叫醒你的耳朵作文500字英文回答：In the realm of slumber, where dreams dance and consciousness fades, there exists a hidden portal that leads to a world of auditory wonders. It is a place where the symphony of life reverberates through the corridors of the soul, awakening senses and igniting the spark of imagination. This magical gateway lies within the depths of our ears, beckoning us to embark on a journey of sonic exploration.Within this extraordinary chamber, a tapestry of intricate structures unfolds, each component playing avital role in the symphony of sound. The outer ear, a delicate funnel, collects sound waves from the surrounding environment and channels them towards the inner sanctum. Here, the eardrum, a vibrant membrane, vibrates with the incoming sound, transforming it into mechanical energy.As the eardrum trembles, its vibrations are transmitted to the middle ear, a complex system of tiny bones known as ossicles. These ossicles amplify the sound, enhancing its intensity and clarity. The malleus, incus, and stapes, working in harmonious synchrony, conduct the sound waves towards the inner ear, a labyrinthine structure concealed deep within the skull.Within the inner ear, the cochlea, a coiled spiral of fluid-filled chambers, awaits. Here, the sound waves are converted into electrical signals, a process facilitated by the delicate hairs of the hair cells. These hair cells, adorned with tiny cilia, sway and dance in response to the vibrations, triggering electrical impulses that travel along the auditory nerve, carrying the symphony of sound to the brain.In the auditory cortex, the brain's command center for sound processing, the electrical signals are deciphered, revealing the hidden melodies, harmonies, and rhythms that compose our acoustic world. The brain interprets these signals, giving birth to the rich and captivatingexperiences of sound that enrich our lives.From the gentle whisper of a lover's voice to the thunderous roar of a crashing wave, our ears serve as conduits to a realm of auditory delight. They allow us to communicate, connect, and express our emotions through the universal language of sound. Music, that ethereal tapestry of melodies and rhythms, paints vibrant hues upon the canvas of our souls, evoking joy, sorrow, and everything in between.The symphony of sound is not merely a passive experience; it is an active engagement, a dance between the vibrations of the external world and the resonant chords of our inner selves. By attuning our ears to the myriad sonic wonders that surround us, we awaken a dormant part of our being, unlocking a profound connection to the world and to ourselves.中文回答：叫醒你的耳朵。

音乐让我放松初中八年级英语作文

音乐让我放松初中八年级英语作文Music Lets Me RelaxI love music! It's one of my favorite things in the whole world. Music can make me feel so many different emotions - happy, sad, excited, calm. But most of all, music really helps me relax when I'm feeling stressed out or anxious.Being in 8th grade can be really stressful sometimes. There's so much schoolwork, tests, projects, and activities to keep up with. Not to mention all the social pressures and drama of being a teenager! Some days I come home feeling completely overwhelmed and wound up. That's when I turn to my favorite relaxing playlist.As soon as those first few notes start playing through my headphones, I can feel my body instantly start to unwind. The melodies and rhythms just seem to wash away all the tension and worries spinning around in my head. It's like my brain gets this reset button pushed and I can take a deep breath again.Different types of music affect me in different relaxing ways too. Sometimes I'll put on some soft acoustic guitar or piano music if I want something really mellow and peaceful. The gentle, sparse sounds are almost like audio comfort food. They wrap meup in this warm, cozy feeling like I'm all bundled up in a fuzzy blanket on a rainy day. No loud, harsh noises to overstimulate me, just simple, pretty tones to rest my mind.Other times when I need a bit more of a mental escape, I'll choose some atmospheric ambient or new age instrumentals. Those swirling, atmospheric textures and nature soundscapes transport me to this whole other dreamy, meditative space. I'll close my eyes and imagine myself in a lush rainforest, by a peaceful stream, or even drifting through outer space! My imagination can just freely drift and wander as the hypnotic, flowing melodies cradle my thoughts.Then there are the more upbeat, high energy dance tracks that I'll blast to help me physically release stress and anxiety. Sometimes after a long, tough day I've got all this pent-up restlessness inside. So I'll crank up some thumping beats and rhythms and just go wild - jumping around my room, waving my arms, even busting out silly dance moves! It's like aerobic stress-relief. I'll be drenched in sweat but feeling so rejuvenated and refreshed afterwards. All that formerly coiled-up tension just melts away.My all-time favorite relaxing song though has to be my mom's lullaby from when I was a baby. Even now, over a decadelater, those gentle wordless vocals and soothing guitar notes still instantly melt away any anxiety and fill me with this deep sense of security and peace, like being wrapped up in a big, warm hug. It never fails to slow my racing thoughts and rapid heartbeat back down to a calm, steady rhythm. Listening to that lullaby is truly like being a little kid again - safe, relaxed, with no worries in the world.I don't know what I'd do without music's power to destress and recharge me. On my most overwhelming days, those melodies, rhythms and lyrics are like a lifeline pulling me out of the chaos and helping me find my center again. Whether it's rocking out to dance tunes, meditating to ambient soundscapes, or just zoning out to a cozy folk playlist, music never fails to wash away my tensions and anxieties, relaxing both my mind and body.For me, putting on my headphones and getting lost in those notes is the ultimate form of self-care and therapy. No matter how wound up I'm feeling, music is always there to gently unwind me. It's honestly the healthiest stress-relief and relaxation tool I have. I can't imagine getting through these crazy teenage years without those musical moments of peace to recenter myself! Music is truly a precious gift that has awesomehealing powers. I feel so lucky to have it as my constant companion to help keep me relaxed and grounded.。

Dispersion effects in elliptical-core highly birefringent fibers

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Available from: Wojtek J Bock Retrieved on: 16 June 2015
OCIS codes: 060.2310, 060.2420, 060.2370, 060.2400.
1. Introduction
Elliptical-core highly birefringent ͑HB͒ ﬁbers can be used as active elements of ﬁber-optic sensors for measuring numerous physical parameters such as temperature, hydrostatic pressure, and elongation.1–3 Such ﬁbers can propagate two orthogonally polarized fundamental modes ͑E11x and E11y͒ with different propagation constants. One of the parameters characterizing HB ﬁber is modal birefringence B.4,5 A measurand acting on HB ﬁber causes a change in the modal birefringence and consequently a change in the phase shift between orthogonally polarized modes at the ﬁber output. This phase shift can be detected by use of interferometric or polarimetric methods. The sensitivity of the HB ﬁber to a given measurand X is represented by the parameter ‫ץ‬B͞‫ץ‬X. It is already known from the literature4–9 that modal

AE sensors

M e a s u r i n g H e a d sS o f t w a r e B a l a n c i n g H e a d s E l e c t r o n i c U n i t s A c c e s s o r i e s n s o rAE SensorsACOUSTIC EMISSION SENSORS FOR GRINDING MACHINESMARPOSS supplies a wide range of acoustic sensors for grinding machines, able to satisfy various requirements including continuous monitoring and air gap check, dressing, grinding wheel and part collision.These sensors are based on ultrasonic (acoustic emission) technology which can check the noise emitted when the part or the dresser touches the grinding wheel.This noise typically relates to acoustic emission signals which are high frequency waves, generated by the energy stored and released in the machine structure. Monitoring of these waves and their comparison with a basic reference allows checks of possible changes in condition, for which corrective action may be applied on the machine.For example, this may be used to identify contact between the grinding wheel and the part, or contact between the grinding wheel and the dressing tool.Variations in the acoustic emission may indicate changes in the cutting force which can consequently be corrected with adaptive cycles.For grinding machines the acoustic sensor can be supplied in the most suitable version for positioning as close as possible to the machining where the signal/noise ratio is at its best.Measuring Heads Software Balancing Heads Electronic Units AccessoriesSensorsAE sensor versions and typical applications on grinding machinesM e a s u r i n g H e a d sS o f t w a r eB a l a n c i n g H e a d s E l e c t r o n i c U n i t sA c c e s s o r i e sn s o rMeasuring Heads Software Balancing Heads Electronic Units AccessoriesSensors。

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Fiber-optic acoustic sensors in the form of a two-fiber Mach-Zehnder interferometer have demonstrated high sensitivity together with a maximum obtainable fringe visibility of unity.1' 2 Other simpler interferometric
392
OPTICS LETTERS / Vol. 5, No. 9 / September 1980
Acoustic sensing with a single coiled monomode fiber
S. C. Rashleigh
Naval Research Laboratory, Washington, D.C. 20375 Received May 21, 1980 A single monomode fiber-optic acoustic sensor is proposed. The acoustic wave differentially changes the phase velocities of the polarization eigenmodes in a tension-coiled fiber, leading to a polarization rotation of the transmitplexity are significantly reduced.
velocity of both unequally, leading to an intensity change in the detected light when the two eigenmodes interfere suitably. Alternatively, the acoustic pressure changes the birefringence 3 of the fiber coil, resulting in a polarization rotation of the propagating light and an intensity change in the light transmitted by a suitable analyzer.
into the fiber coil at 7r/4 to the eigenmodes. After propagating through the fiber of length 1,the electric field amplitudes E1 and E 2 of the eigenmodes can be expressed by
0146-9592/80/090392-03$0.50/0
Fig. 1.
Schematic arrangement
of the acoustic sensor.
© 1980, Optical Society of America
September 1980 / Vol. 5, No. 9 / OPTICS LETTERS
coiling the fiber on a small-diameter cylindrical former
breaks the near degeneracy of the two mutually orthogonal polarizations of the HE1, mode and thus introduces a large linear birefringence j3in the fiber.6 For silica fibers at X = 0.633 Atm, = -4.9 X

peib - 1.34 X 106 p 2 /b 2 rad/m,
(1)
where 2p is the fiber's outer diameter, e is the fiber's longitudinal strain, and 2b is the outer diameter of the former. In this way, polarization beat lengths Lp 2... .5 cm can be realized, indicating that the fiber coil can hold linear polarization and thus can propagate the two linearly polarized eigenmodes independently. These eigenmodes are automatically aligned perpendicularly and parallel to the coil axis. In this sensing arrangement, the reference and sensing beams can be considered to propagate within the same fiber. The acoustic pressure alters the phase
ted light. Sensitivities exceeding those of multimode fiber-optic hydrophones and -40 times less than those of the two-fiber interferometric sensor should be realizable while environmental instability problems and the sensor com-
393
the fiber-coil eigenmodes. The amplitudes of these
beams are
E3
= E exp(ikl)cos[ol/2 + A(31/2)],
=
(3)
(a)
E4
iE exp(ikl)sin[ol/2+ A(01/2)],
(4)
which, when incident upon the photodetectors, give currents I, and 12. These can be electronically processed to give the signal
106
where k is the average propagation constant of the eigenmodes, E is the incident amplitude, and A(fl/2) is the phase change induced in each eigenmode by the acoustic pressure. The time dependence exp(-iwt) and the fiber losses have been suppressed. At the fiber output, the Wollaston prism WP is oriented to transmit linearly polarized beams at azimuths +lr/4 relative to
sensing schemes3' 4 show greatly reduced sensitivity and problems arise in maintaining a stable fringe visibility.
visibility. For all these sensor configurations, severe This is because the state of polarization (SOP) of the light in the fibers varies sensitively and irregularly with environmental perturbations. As such, the SOP of the two interfering beams may occasionally be mutually orthogonal, leading to zero visibility or, alternatively, to a complete fading of the detected signal. This problem is particularly serious for the two-fiber interferometer, as the the two fibers followseparate paths, further magnifying any differential environmental perturbations. To overcome these stability problems, 6 are being polarization-holding fibers5 and schemes developed. This polarization-fading problem and the associated reduction in sensitivity are distinct from the reduced sensitivity seen when the interferometer drifts out of quadrature. In this Letter, we report an alternative interferometric sensing scheme in which the acoustic wave is
E1,2
=
They are excited equally by launching light
(E/fJ) exp(ikl)expkii[f1/2 + A(/1/2)],