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Physically Realizable Broadband Acoustic Metamaterials with Anisotropic Density

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Chinese Physics Letters 2019年第2期36卷 15-18页

作者： Zhi-Miao Lu Li Cai ji-hong wen Xing Chen Science and Technology on Integrated Logistics Support Laboratory National University of Defense Technology

Transformation acoustics are concentrated for the purpose of designing novel acoustic devices to tailor acoustic waves to achieve desirable characteristics. However, these devices require fluid or fluid-like materials with an anisotropic density that generally does not exist in nature. Therefore, we introduce pentamode metamaterials into an alternating multilayer isotropic medium model to build fluid-like metamaterials with an anisotropic density. A 2D acoustic bending based on transformation acoustics is established and investigated to verify our method. This idea provides a method to design broadband and physically realizable acoustic metamaterials with an anisotropic density and is meaningful for the design of acoustic metamaterials.

关键词： Physically Realizable Broadband Acoustic Metamaterials with Anisotropic Density

Effect of Mean Flow on Acoustic Wave Propagation in a Duct with a Periodic Array of Helmholtz Resonators

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Chinese Physics Letters 2020年第3期37卷 32-35页

作者： jiang-Wei Liu Dian-Long Yu Hai-Bin Yang Hui-jie Shen ji-hong wen Laboratory of Science and Technology on Integrated Logistics Support College of Intelligence Science and TechnologyNational University of Defense TechnologyChangsha 410073 College of Power Engineering Naval University of EngineeringWuhan 430033

Sound propagation properties of a duct system with Helmholtz resonators(HRs)are affected by mean *** studies have tended to focus on the effects of mean flows on acoustic response of a duct system with a finite number of *** an empirical impedance model,we present a modified transfer matrix method for studying the effect of mean flow on the complex band structure of an air duct system with an infinite periodic array of *** efficiency of the modified transfer matrix is demonstrated by comparison between an example of transmission response calculation for a finite single HR loaded duct and the finite element simulation result calculated using the COMSOL *** results are presented to analyze the effect of mean flow on the band structure and transmission loss of the sound wave in the duct *** is hoped that this study will provide theoretical guidance for acoustic wave propagation of HR silencer in the presence of mean flow.

关键词： flow. Helmholtz finite

Impact vibration properties of locally resonant fluid-conveying pipes

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Chinese Physics B 2020年第12期29卷 313-321页

作者： Bing Hu Fu-Lei Zhu Dian-Long Yu jiang-Wei Liu Zhen-Fang Zhang jie Zhong ji-hong wen Laboratory of Science and Technology on Integrated Logistics Support National University of Defense TechnologyChangsha 410073China

Fluid-conveying pipe systems are widely used in various equipments to transport matter and *** to the fluid–structure interaction effect,the fluid acting on the pipe wall is easy to produce strong vibration and noise,which have a serious influence on the safety and concealment of the *** on the theory of phononic crystals,this paper studies the vibration transfer properties of a locally resonant(LR)pipe under the condition of fluid–structure *** band structure and the vibration transfer properties of a finite periodic pipe are obtained by the transfer matrix ***,the different impact excitation and fluid–structure interaction effect on the frequency range of vibration attenuation properties of the LR pipe are mainly considered and calculated by the finite element *** results show that the existence of a low-frequency vibration bandgap in the LR pipe can effectively suppress the vibration propagation under external impact and fluid impact excitation,and the vibration reduction frequency range is near the bandgap under the fluid–structure interaction ***,the pipe impact experiment was performed to verify the effective attenuation of the LR structure to the impact excitation,and to validate the finite element *** research results provide a technical reference for the vibration control of the fluid-conveying pipe systems that need to consider blast load and fluid impact.

关键词： locally resonant pipe fluid-structure interaction transfer matrix method impact vibration properties

Propagation of acoustic waves in a fluid-filled pipe with periodic elastic Helmholtz resonators

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Chinese Physics B 2018年第6期27卷 285-291页

作者： Dian-Long Yu Hui-jie Shen jiang-Wei Liu jian-Fei Yin Zhen-Fang Zhang and ji-hong wen Support National University of Defense Technology Changsha 410073 China College of Power Engineering Naval University of Engineering Wnhan 430033 China

Helmholtz resonators are widely used to reduce noise in a fluid-filled pipe system. It is a challenge to obtain lowfrequency and broadband attenuation with a small sized cavity. In this paper, the propagation of acoustic waves in a fluid-filled pipe system with periodic elastic Helmholtz resonators is studied theoretically. The resonance frequency and sound transmission loss of one unit are analyzed to validate the correctness of simplified acoustic impedance. The band structure of infinite periodic cells and sound transmission loss of finite periodic cells are calculated by the transfer matrix method and finite element software. The effects of several parameters on band gap and sound transmission loss are ***, the negative bulk modulus of periodic cells with elastic Helmholtz resonators is analyzed. Numerical results show that the acoustic propagation properties in the periodic pipe, such as low frequency, broadband sound transmission, can be improved.

关键词： acoustic metamaterial band gap sound transmission loss elastic Helmholtz resonator noise control

Oblique incidence properties of locally resonant sonic materials with resonance and Bragg scattering effects

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Chinese Physics B 2013年第7期22卷 267-273页

作者：袁博温激鸿温熙森 Vibration and Acoustics Research Group Laboratory of Science and Technology on Integrated Logistics SupportNational University of Defense Technology MOE Key Laboratory of Photonic and Phononic Crystals National University of Defense Technology

A locally resonant sonic material （LRSM） is an elastic matrix containing a periodic arrangement of identical local resonators （LRs）, which can reflect strongly near their natural frequencies, where the wavelength in the matrix is still much larger than the structural periodicity. Due to the periodic arrangement, an LRSM can also display a Bragg scattering effect, which is a characteristic of phononic crystals. A specific LRSM which possesses both local resonance and Bragg scattering effects is presented. Via the layered-multiple-scattering theory, the complex band structure and the transmittance of such LRSM are discussed in detail. Through the analysis of the refraction behavior at the boundary of the composite, we find that the transmittance performance of an LRSM for oblique incidence depends on the refraction of its boundary and the transmission behaviors of different wave modes inside the composite. As a result, it is better to use some low-speed materials （compared with the speed of waves in surrounding medium） as the LRSM matrix for designing sound blocking materials in underwater applications, since their acoustic properties are more robust to the incident angle. Finally, a gap-coupled LRSM with a broad sub-wavelength transmission gap is studied, whose acoustic performance is insensitive to the angle of incidence.

关键词： underwater acoustic materials oblique incidence locally resonant sonic materials Bragg scattering

基于无线广播优势的无线Mesh网络负载感知多播算法

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北京邮电大学学报 2017年第4期40卷 80-85页

作者：王继红石文孝东北电力大学信息工程学院吉林132012 吉林大学通信工程学院长春130012

提出了基于无线广播优势的负载感知多信道多播(W-LMCM)算法,以解决最大化服务用户数的多播路由与信道分配问题,将起始于同一节点的兄弟链路视为整体进行信道分配,充分利用无线广播优势节省带宽;提出最大信道号信道分配方法,避免随机信... 详细信息

提出了基于无线广播优势的负载感知多信道多播(W-LMCM)算法,以解决最大化服务用户数的多播路由与信道分配问题,将起始于同一节点的兄弟链路视为整体进行信道分配,充分利用无线广播优势节省带宽;提出最大信道号信道分配方法,避免随机信道分配带来的不利影响;在满足干扰范围内信道容量约束条件下,以最小化干扰为目标为链路分配信道,解决无干扰信道分配引起的服务用户数受限的问题.仿真结果表明,W-LMCM算法能有效提升多播吞吐量及网络服务能力.

关键词：负载感知多播无线广播优势信道分配

乌司他丁对体外循环冠脉搭桥患者凝血系统和血小板功能的影响

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中华医学杂志 2009年第3期89卷 175-178页

作者：纪宏文陈雷中国医学科学院阜外心血管病医院麻醉科北京100037

目的探讨乌司他丁对体外循环冠状动脉旁路移植术患者凝血系统、血小板功能和术后出血的影响。方法择期行体外循环（CPB）冠状动脉旁路移植术患者36例，随机分为对照组（C组，n=18）和乌司他丁组（U组，n=18）。U组将乌司他丁40万单位溶... 详细信息

目的探讨乌司他丁对体外循环冠状动脉旁路移植术患者凝血系统、血小板功能和术后出血的影响。方法择期行体外循环（CPB）冠状动脉旁路移植术患者36例，随机分为对照组（C组，n=18）和乌司他丁组（U组，n=18）。U组将乌司他丁40万单位溶于100ml生理盐水中，自切皮开始静脉输注，30min内输注完毕，另将40万单位加入CPB预充液中，另外20万单位以4～6万单位／h速率输注至术毕，总量100万单位，C组不用乌司他丁及任何抗纤溶药物。分别于切皮前1min（基础值，T0），肝素化前1min（此时U组已用乌司他丁40万单位，T1），术毕（T2），术后6h（T3）和术后24h（T4）经颈内静脉导管采血5ml，用流式细胞仪测定血小板膜糖蛋白GPⅡb／Ⅲa和血小板α颗粒膜蛋白-140（CD62p），用比浊法测定激活部分凝血致活酶时间（APTT）、凝血酶原时间（PT）和纤维蛋白原，用硅藻土激活剂测定激活全血凝固时间（ACT）。记录患者术后24h出血量和输血量。结果组间GPⅡb／Ⅲa、CD62p和PT，以及术后24h出血量和同种输血量比较差异均无统计学意义（P〉0．05）。与基础值比较，U组APTT在T1、T3和T4均缩短（均P〈0．05）。与C组比较，U组：APTT在T1-4均缩短（均P〈0．05），体外循环中ACT缩短，补充肝素量增加（P〈0．01）。结论乌司他丁对血小板聚集和活性无影响，它能缩短APTT及肝素化后的ACT，增加CPB中补充肝素量，对内源性凝血系统有促进作用，该实验所用剂量未见减少CPB术后出血。

关键词：乌司他丁冠状动脉分流术心肺转流术血小板功能试验凝血

Evaluation of liver functional reserve by combining D-sorbitol clearance rate and CT measured liver volume

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World Journal of Gastroenterology 2003年第9期9卷 2092-2095页

作者： Yi-Ming Li Fan Lv Xin Xu hong ji wen-Tao Gao Tuan-jie Lei Gui-Bing Ren Zhi-Lan Bai Qiang Li General Surgery Department,the 2~(nd)Affiliated Hospital of Xi’an jiaotong University,Xi’an 710004,ShaanXi Province,China General Surgery Department the 2nd Hospital of Xi'an Jiaotong University Xi'an 710004 ShaanXi Province China. liyiming@***

AIM: Our research attempted to evaluate the overall functional reserve of cirrhotic liver by combination of hepatic functional blood flow, liver volume, and ChildPugh′s classification, and to discuss its value of clinical ***: Ninety two patients with portal hypertension due to hepatic cirrhosis were investigated. All had a historyof haematemesis and hematochezia, esophageal and gastric fundus varices, splenomegaly and hypersplenia.A 2-year follow-up was routinely performed and no one was lost. Twenty two healthy volunteers were used as control group. Blood and urine samples were collected 4times before and after intravenous D-sorbitol *** hepatic clearance (CLH) of D-sorbitol was then calculated according to enzymatic spectrophotometric method while the total blood flow (QToTAL) and intrahepatic shunt (RINs) were detected by multicolor Doppler ultrasound, and the liver volume was measured by spiral CT. Data were estimated by t-test, variance calculation and chi-squared test. The relationships between all these parameters and different groups were investigated according to Child-Pugh classification and postoperative complications ***: Steady blood concentration was achieved 120 mins after D-sorbitol intravenous infusion, which was (0.358±0.064) mmoⅠ@L-1 in cirrhotic group and (0.189±0.05)mmol@L-1 in control group (P＜0.01). CLH=(812.7±112.4) ml@min-1,QTOTAL=(1280.6±131.4) ml@min-1, and RINS=(36.54±10.65)%in cirrhotic group and CLH=(1248.3±210.5) ***-1, QTOTAL=(1362.4-±126.9) ml@min-1, and RINS=(8.37±3.32) % in control group (P＜0.01). The liver volume of cirrhotic group was 1057±249 cm3, 851±148 cm3 and 663±77 cm3 in Child A, B and C group respectively with significant difference (P＜0.001).The average volume of cirrhotic liver in Child B, C group was significantly reduced in comparison with that in control group (P＜0.001). The patient, whose liver volume decreased by 40 % with the CLH below 600 ml@min-1, would have a higher

关键词： D-山梨醇清除率肝功能 CT检查

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二维水翼局部空泡脱落特性数值分析

水动力学研究与进展（A辑） 2008年第4期23卷 412-418页

作者：季斌洪方文彭晓星中国船舶科学研究中心江苏无锡214082

空化是水动力学中特有的一种物理现象,研究空化现象对改善水力机械和舰船推进器性能具有很现实的工程意义,发展空泡流动的数值模拟技术是现在空化研究领域中的热点。本文通过Fluent软件提供的二次开发接口,把基于状态方程的空化模型添加... 详细信息

空化是水动力学中特有的一种物理现象,研究空化现象对改善水力机械和舰船推进器性能具有很现实的工程意义,发展空泡流动的数值模拟技术是现在空化研究领域中的热点。本文通过Fluent软件提供的二次开发接口,把基于状态方程的空化模型添加到Fluent软件中,并采用非线性汽、液湍流黏性计算模式实现了二维水翼定常、非定常空泡流动的数值模拟。计算的定常空泡翼型表面的压力分布与试验吻合较好,模拟了非定常空泡从初生、发展、断裂、脱落以及在下游溃灭的整个过程。揭示了空泡内部流动结构和非定常周期性脱落的原因。通过数值模拟与试验对比,研究了空泡脉动的St数的规律。

关键词： FLUENT 空化模型数值模拟状态方程