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Cavity-agnostic acoustofluidic manipulations enabled by guided flexural waves on a membrane acoustic waveguide actuator

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Microsystems & Nanoengineering 2024年第2期10卷 153-171页

作者： Philippe Vachon Srinivas Merugu jaibir Sharma Amit Lal Eldwin j.ng Yul Koh joshua E.-Y.Lee Chengkuo Lee Department of Electrical and Computer Engineering National University of SingaporeSingaporeSingapore Institute of Microelectronics Agency for ScienceTechnology and Research(A*STAR)SingaporeSingapore SonicMEMS Laboratory School of Electrical and Computer EngineeringCornell UniversityIthacaNYUSA School of Electrical and Data Engineering University of Technology SydneyUltimoNSWAustralia

This article presents an in-depth exploration of the acoustofluidic capabilities of guided flexural waves(GFWs)generated by a membrane acoustic waveguide actuator(MAWA).By harnessing the potential of GFWs,cavity-agnostic advanced particle manipulation functions are achieved,unlocking new avenues for microfluidic systems and lab-on-a-chip *** localized acoustofluidic effects of GFWs arising from the evanescent nature of the acoustic fields they induce inside a liquid medium are numerically investigated to highlight their unique and promising *** traditional acoustofluidic technologies,the GFWs propagating on the MAWA’s membrane waveguide allow for cavity-agnostic particle manipulation,irrespective of the resonant properties of the fluidic ***,the acoustofluidic functions enabled by the device depend on the flexural mode populating the active region of the membrane *** demonstrations using two types of particles include in-sessile-droplet particle transport,mixing,and spatial separation based on particle diameter,along with streaming-induced counter-flow virtual channel generation in microfluidic PDMS *** experiments emphasize the versatility and potential applications of the MAWA as a microfluidic platform targeted at lab-on-a-chip development and showcase the MAWA’s compatibility with existing microfluidic systems.

关键词： waveguide fluid cavity

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Monolithic ultrasound fingerprint sensor

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Microsystems & Nanoengineering 2017年第1期3卷 37-44页

作者： Xiaoyue jiang Yipeng Lu Hao-Yen Tang julius M.Tsai Eldwin j.ng Michael j.Daneman Bernhard E.Boser David A.Horsley Department of Mechanical Engineering University of CaliforniaBerkeleyCA 94720USA Department of Mechanical and Aerospace Engineering University of CaliforniaDavisCA 95616USA Department of Electrical Engineering and Computer Sciences University of CaliforniaBerkeleyCA 94720USA Invensense Inc. San JoseCA 95110USA

This paper presents a 591×438-DPI ultrasonic fingerprint *** sensor is based on a piezoelectric micromachined ultrasonic transducer(PMUT)array that is bonded at wafer-level to complementary metal oxide semiconductor(CMOS)signal processing electronics to produce a pulse-echo ultrasonic imager on a *** meet the 500-DPI standard for consumer fingerprint sensors,the PMUT pitch was reduced by approximately a factor of two relative to an earlier *** conducted a systematic design study of the individual PMUT and array to achieve this scaling while maintaining a high *** resulting 110×56-PMUT array,composed of 30×43-μm^(2) rectangular PMUTs,achieved a 51.7% fill-factor,three times greater than that of the previous *** with the custom CMOS ASIC,the sensor achieves 2 mV kPa^(−1) sensitivity,15 kPa pressure output,75μm lateral resolution,and 150μm axial resolution in a 4.6 mm×3.2 mm *** the best of our knowledge,we have demonstrated the first MEMS ultrasonic fingerprint sensor capable of imaging epidermis and sub-surface layer fingerprints.

关键词： piezoelectric micromachined ultrasonic transducer(PMUT) fingerprint sensors ultrasound

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基于电路理论的岷江流域生态安全格局构建研究

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水土保持研究 2025年第2期32卷 263-275页

作者：杨艳萍干晓宇吴潇四川大学建筑与环境学院成都610065

[目的]精准提取各生态空间要素,构建生态安全格局,维持流域生态系统的健康稳定及生态环境保护的可持续发展。[方法]以岷江流域为研究区,评估其生态系统服务重要性以筛选生态源地,通过地质灾害敏感性评价修正土地利用基本阻力面,并基于... 详细信息

[目的]精准提取各生态空间要素,构建生态安全格局,维持流域生态系统的健康稳定及生态环境保护的可持续发展。[方法]以岷江流域为研究区,评估其生态系统服务重要性以筛选生态源地,通过地质灾害敏感性评价修正土地利用基本阻力面,并基于电路理论,量化识别廊道、夹点、障碍点等生态空间要素,构建生态安全格局。[结果](1)面积阈值设定为7 km^(2)时,筛选出生态源地77个,面积占比为30.77%,关键生态源地主要在“龙门—邛崃山脉”及其以北的岷山中南段雪宝顶等林地区,以及岷江中下游的部分耕地和林地。(2)生态廊道共176条,总长度2 072.96 km,关键生态廊道总长度占比为21.32%,集中在岷江中游;生态夹点共719处,总面积1 578.5 km^(2);生态障碍点163处,总面积2 410 km^(2)。(3)构建“四区两带一廊”的岷江流域生态安全格局,并以岷江乡为例,探索了岷江流域“全流域—局域单元”生态空间协同修复路径。[结论]生态修复时要考虑多尺度格局的衔接与融合,实行系统性、差异化的生态空间分区治理,提升生态景观连通性及生境质量,促进物质流通。

关键词：生态安全格局生态修复电路理论生态系统服务地质灾害敏感性岷江流域

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VARIATIONAL DISCRETIZATION FOR PARABOLIC OPTIMAL CONTROL PROBLEMS WITH CONTROL CONSTRAINTS

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journal of Systems Science & Complexity 2012年第5期25卷 880-895页

作者： Yuelong TAng yanping CHEN School of Mathematics and Computational Science Xiangtan University School of Mathematical Sciences South China Normal University

This paper studies variational discretization for the optimal control problem governed by parabolic equations with control constraints. First of all, the authors derive a priori error estimates where｜｜｜u - Uh｜｜｜L∞（j;L2（Ω）） = O（h2 ＋ k）. It is much better than a priori error estimates of standard finite element and backward Euler method where ｜｜｜u- Uh｜｜｜L∞（j;L2（Ω）） = O（h ＋ k）. Secondly, the authors obtain a posteriori error estimates of residual type. Finally, the authors present some numerical algorithms for the optimal control problem and do some numerical experiments to illustrate their theoretical results.

关键词： A posteriori error estimates a priori error estimates optimal control problems parabolicequations variational discretization.

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Mechanical and hydraulic properties of carbonate rock:The critical role of porosity

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journal of Rock Mechanics and Geotechnical Engineering 2023年第4期15卷 814-825页

作者： Kam ng j.Carlos Santamarina Department of Civil and Architectural Engineering and Construction Management University of WyomingLaramieWY82071USA Physical Science and Engineering Division King Abdullah University of Science and TechnologyThuwal23955-6900Saudi Arabia

Carbonate rocks are extensively used in civil infrastructure and play a critical role in geoenergy geoengineering,either as hydrocarbon reservoirs or potential repositories for CO_(2)geological *** genesis and diagenetic overprint determine the properties of carbonate *** study combines recent data gathered from Madison Limestone and an extensive dataset compiled from published sources to analyze the hydraulic and mechanical properties of limestone carbonate *** models and data analyses recognize the inherently granular genesis of carbonate rocks and explain the strong dependency of physical properties on *** asymptotically-correct power model in terms of(1-Ф/Ф*)a is a good approximation to global trends of unconfined stiffness E and unconfined compressive strength UCS,cohesive intercept in Mohr-Coulomb failure envelopes,and the brittle-toductile transition *** power model is the analytical solution for the mechanical properties of percolating granular *** adopted a limiting granular porosityФ*=0.5 for all models,which was consistent with the loosest packing of monosize *** fitted power model has exponent(α=2)in agreement with percolation theory and highlights the sensitivity of mechanical properties to *** and models confirm a porosity-independent ratio between unconfined stiffness and strength,and the ratio follows a log-normal distribution with mean(E/UCS)≈*** high angle of internal shear strength measured for carbonate rocks reflects delayed contact failure with increased confinement,and it is not sensitive to *** spans more than six orders of *** size controls pore size and determines the reference permeability k^(*)at the limiting porosityФ*=*** a given grain size from fine to coarse-grained dominant carbonates,permeability is very sensitive to changes in porosity,suggesting preferential changes in the internal pore network during compaction.

关键词： Rock porosity Carbonate permeability Rock unconfined stiffness Unconfined compressive strength(UCS)

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Physical scientists research biomedicine: a call for caution

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Chinese journal of Cancer Research 2015年第1期27卷 94-95页

作者： Yì-Xiáng j.Wáng Department of Imaging and Interventional Radiology Faculty of Medicine The Chinese University of Hong Kong Prince of Wales Hospital

It is noticeable that nowadays there are more and more scientists with physical science or engineering background working on or started to work on biomedical projects, but rarely vice versa. This reflects the multi-discipline nature of some projects, however, also at least partially can be explained that biomedical research is seen as trendy, fundable, and likely to get more citations and with results more publishable in high impact journals （1,2）. It is also apparent with some publications and lectures that not all these physical scientists/engineers are well-prepared to work on projects which do not align with their own expertise. Some studies are against very basic principles of pharmacology or biology, while others try to solve medical problems which do not exist clinically. I reviewed a number of submissions including a few from prestigious American universities to Nature journals which made no sense with the study design. Much of manpower and financial resource are being wasteful spent. There are also examples of clinical trials which were ill-planned right from the start and in the end only causing much inconvenience to patients to say at the least. In addition, ample examples exist where experienced physical scientists worked with inexperienced medical scientists and resulted in avoidable failures.

关键词： a call for caution very Physical scientists research biomedicine

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城市公园绿视率对游人主观热舒适度的影响——以成都市人民公园为例

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城市建筑 2025年第1期22卷 218-223页

作者：宋昊翔钟彦萍西南交通大学建筑学院

文章以成都市人民公园为例,旨在探讨城市公园绿视率如何影响热舒适度。通过深度学习技术计算和测量了公园内29个点位的绿视率,将公园空间分为四种不同类型:广场空间、滨湖空间、茶歇空间和树荫空间,分别选取其中四个具有代表性的点位进... 详细信息

文章以成都市人民公园为例,旨在探讨城市公园绿视率如何影响热舒适度。通过深度学习技术计算和测量了公园内29个点位的绿视率,将公园空间分为四种不同类型:广场空间、滨湖空间、茶歇空间和树荫空间,分别选取其中四个具有代表性的点位进行微气候因素(空气温度、风速、相对湿度和太阳辐射)的测量。此外,研究共收集了375份问卷,详细收集受访者的主观热舒适度和微气候感知度数据。研究结果表明,绿视率与游人的主观热舒适度之间存在显著关联。绿视率的提高能够降低人们对太阳辐射的感知,从而提升主观热舒适度。

关键词：城市公园绿视率深度学习热舒适度微气候因素太阳辐射

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Criteria of limiting temperature and parametric analysis of the large deflection behavior for fully restrained steel beams in fire

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Science China(Technological Sciences) 2012年第1期55卷 264-275页

作者： XI Feng LUAN yanping Shandong Provincial Key Laboratory of Structural Engineering School of Civil Engineering Shandong Jianzhu University Jinan 250101 China School of Civil Engineering Shandong Jianzhu University Jinan 250101 China

This paper mainly involve 3 parts:1) To apply the minimum principle of acceleration in dynamics of elastic-plastic continua at finite deformation to the statics problems,a computing model is presented for the restrained steel beams exposed to the *** this model,both effects of large deflection and thermal expansion deformation are taken into account,and the constitutive equations with the temperature effects are *** a dynamic finite difference(DFD) method is presented by using the dis-crete technique,which can be used in simulating the response of the steel beams at elevated temperature,and the large deflec-tion behavior and catenary action effects of the beams can be adequately *** primary numerical results show that the method is valid and *** with other methods,this technique is very simple,and it can also be further devel-oped to simulate the behavior of steel beams subjected to the coupling loading of explosion and fire when both effects of strain rate and inertia are considered.2) By using this DFD method,detailed parametric analysis are presented so as to check the consistency of response results for several different formulas of thermal expansion deformation and retention factors of steel at elevated temperature,the influence of these parameters on the critical temperature is examined.3) Based on the analysis for the curves of temperature-generalized yield function comprised by the axial force and bending moment,both criteria to determine the limiting temperature(or failure temperature) of large deflection steel beams are presented more explicitly,that is,both lim-iting temperatures can be determined by if the catenary force begins to appear or arrives at the maximum value,*** is shown by numerical results that both limiting temperatures are close to the both critical temperatures which are correspond-ing to the maximum deflections equal to span/20 and span/10,*** conclusion may be helpful to make r

关键词： steel beam fire DFD method large deflection parametric analysis limiting temperature criteria yield function

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Comparison Study on the Microstructure of Nanocrystalline TiO_2 in Different Ti-Si Binary Oxides

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journal of Materials Science & Technology 2007年第5期23卷 604-610页

作者： Luyan WAng yanping SUN Bingshe XU Chemical Engineering Department Taiyuan University of Technology Taiyuan 030024 China Key Laboratory of Interface and Engineering in Advanced Material Ministry of Education Taiyuan University of Technology Taiyuan 030024 China

Three different Ti-Si oxide structuares, silica supported titania, silica coated titania and intimately mixed silicatitania, containing 10%-40% SiO2, were made by sol-gel process. The variations of microstructure parameters of nanocrystalline （nc） TiO2-anatase in the three kirds of binary oxides, including in-plane spacing d, cell constants （ao, co）, cell volume V, cell axial ratio co/ao and crystal grain size, were comparatively investigated by high resolution transmission electron microscopy （HRTEM） and X-ray diffraction （XRD）. It is found that the microstructure parameters vary remarkably with increasing SiO2 content and annealing temperature. Different structured Ti-Si binary oxides lead to different variation tendencies of microstructure parameters. The more SiO2 the binary oxide contains, the more lattice defects of nc TiO2-anatase appear; diffusion or migration of Si cations could be an important influential factor in the variations of microstructure. The grain size of nc TiO2 in the three kinds of binary oxides not only depends on SiO2 content and annealing temperature but also on the degree of lattice microstrain and distortion of nc TiO2-anatase. Both grain size and phase transformation of nc TiO2-anatase are effectively inhibited with increasing SiO2 content.

关键词： Ti-Si binary oxide Sol-gel Microstructure parameter Comparison

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不同状态鲜核桃冷藏期间品质变化的差异

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食品与发酵工业 2025年第1期51卷 244-249页

作者：李媛媛吴方智王斯可马艳萍刘朝斌西北农林科技大学林学院陕西杨凌712100

为探讨不同状态鲜核桃贮藏期间种仁的品质变化差异,以‘清香’鲜核桃为材料,测定3种状态鲜核桃(带壳坚果、整仁和碎仁)在(0±0.5)℃冷藏期间的品质指标动态变化。结果表明,贮藏期间各状态鲜核桃的发霉指数随着贮藏时间的延长而升高,整... 详细信息

为探讨不同状态鲜核桃贮藏期间种仁的品质变化差异,以‘清香’鲜核桃为材料,测定3种状态鲜核桃(带壳坚果、整仁和碎仁)在(0±0.5)℃冷藏期间的品质指标动态变化。结果表明,贮藏期间各状态鲜核桃的发霉指数随着贮藏时间的延长而升高,整仁和碎仁的发霉指数显著降低;脂肪酸组分无显著变化,不饱和脂肪酸含量下降,饱和脂肪酸含量上升;3种状态的粗脂肪含量总体下降,以碎仁的粗脂肪平均含量最高,其在贮藏30 d期间多酚氧化酶活性较低,过氧化物酶活性显著升高,之后其可溶性糖和可溶性蛋白质含量却低于坚果和整仁;酸价和过氧化值均符合林业标准。总体上看,贮藏过程中整仁保持了较好的品质,碎仁油脂品质相对稳定,但因其破碎程度高,营养成分含量损失较多较早失去商品价值,而坚果在保持较高的营养方面具有更大潜力。

关键词：鲜核桃不同状态品质发霉冷藏

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