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Online differential pressure reset method with adaptive adjustment algorithm for variable chilled water flow control in central air-conditioning systems

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Building Simulation 2021年第5期14卷 1407-1422页

作者： tianyi Zhao Ying zhou Jili Zhang Xiuming Li Institute of Building Energy School of Civil EngineeringFaculty of Infrastructure EngineeringDalian University of TechnologyDalian 116024China School of Metallurgy Northeastern UniversityShenyang 110819China

Central air-conditioning systems predominantly operate under partial load *** optimization of a differential pressure setpoint in the chilled water system of a central air-conditioning system leads to a more energy-efficient *** the differential pressure adjustment value based on the terminal user's real-time demand is one of the critical issues to be addressed during the optimal control ***,the online application of the differential pressure setpoint optimization method needs to be considered,along with the stability of the *** paper proposes a variable differential pressure reset method with an adaptive adjustment algorithm based on the Mamdani fuzzy *** proposed method was compared with differential pressure reset methods with reference to the chilled water differential temperature,outdoor temperature,and linear model based on the adjustment *** energy-saving potential,temperature control effect,and avoidance of the most unfavorable thermodynamic loop effects of the four methods were investigated *** results indicated that,while satisfying the terminal user's energy supply demand and ensuring the avoidance of the most unfavorable thermodynamic loop,the proposed adaptive adjustment algorithm also decreased the differential pressure setpoint value by 25.1%—59.1%and achieved energy savings of 10.6%-45.0%.By monitoring the valve position and supply air temperature of each terminal user,the proposed method exhibited suitable online adaptability and could be flexibly applied to buildings with random load changes.

关键词： central air-conditioning system variable water flow control most unfavorable thermodynamic loop differential pressure reset adaptive control

Internal flow in sessile droplets induced by substrate oscillation:towards enhanced mixing and mass transfer in microfluidic systems

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Microsystems & Nanoengineering 2024年第3期10卷 369-379页

作者： tianyi Zhang Peng zhou Terrence Simon Tianhong Cui Department of Mechanical Engineering University of MinnesotaMinneapolisMN 55455USA

The introduction of flows within sessile droplets is highly effective for many lab-on-a-chip chemical and biomedical ***,generating such flows is difficult due to the typically small droplet ***,we present a simple,non-contact strategy to generate internal flows in sessile droplets for enhancing mixing and mass *** flows are driven by actuating a rigid substrate into oscillation with certain amplitude distributions without relying on the resonance of the droplet *** oscillation characteristics and corresponding flow patterns are documented *** indices and mass transfer coefficients of sessile droplets on the substrate surface are measured using optical and electrochemical *** demonstrate complete mixing within the droplets in 1.35 s and increases in mass transfer rates of more than seven times static *** of concept was conducted with experiments of silver nanoparticle synthesis and with heavy metal ion sensing employing the sessile droplet as a microreactor for synthesis and an electrochemical cell for *** degrees of enhancement of synthesis efficiency and detection sensitivity attributed to the internal flows are experimentally documented.

关键词： mixing oscillation synthesis

Design and Modeling on Stranded Wires Helical Springs

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Chinese Journal of Mechanical Engineering 2011年第4期24卷 626-637页

作者： zhou Jie WANG Shilong KANG Ling CHEN tianyi State Key Laboratory of Mechanical Transmissions Chongqing University Chongqing 400044 China China Aerodynamics Research ＆ Development Center Mianyang 621000 China

A stranded wires helical spring is formed of a multilayer and coaxial strand of several wires twisted together with the same direction of spiral. Compared with the conventional single wire spring, the stranded wires helical spring has the notable predominance in strength, damping and vibration reduction, which is usually used in aircraft engines, automatic weapons, etc. However, due to its complicated structure, the precise computation of its strength and rigidity need be a correct mathematical model, which then will be imported to finite element analysis software for solutions. Equations on solving geometric parameters, such as external diameters of strands and screw pitches of wires, are put forward in the paper. It also proposes a novel methodology on solving geometric parameters and establishing entity models of the stranded wires helical spring, which provides foundation of computing mechanical parameters by FEA. Then mathematical models on the centre line of the strand and the surface curve of each wire, after closing two ends in a spring, are proposed. Finally, geometric parameters are solved in a case study, and a 3D entity model of a spring with 3 layers and 16 wires is established, which has validated the accuracy of the proposed methodology and the 3D entity mathematical model. The method provides a new way to design stranded wire helical spring.

关键词： stranded wires helical spring mathematical model finite element analysis closing ends

Microwave Through Wall Imaging via An Induced Current Learning Method

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Journal of Beijing Institute of Technology 2024年第3期33卷 248-254页

作者： Pengjin Lan Jianguo Huang tianyi zhou Faculty of Electrical Engineering and Computer Science Ningbo UniversityNingbo 315211China

In this paper,an induced current learning method(ICLM)for microwave through wall imaging(TWI),named as TWI-ICLM,is *** the inversion of induced current,the unknown object along with the enclosed walls are treated as a combination of ***,a non-iterative method called distorted-Born backpropagation(DB-BP)is utilized to generate the initial *** the training stage,several convolutional neural networks(CNNs)are cascaded to improve the estimated induced *** addition,a hybrid loss function consisting of the induced current error and the permittivity error is used to optimize the network ***,the relative permittivity images are conducted analytically using the predicted current based on *** the numerical and experimental TWI tests prove that,the proposed method can achieve better imaging accuracy compared to traditional distorted-Born iterative method(DBIM).

关键词： through wall imaging inverse scattering problem convolutional neural network(CNN)

Error modeling and compensating of a novel 6-DOF aeroengine rotor docking equipment

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Chinese Journal of Aeronautics 2022年第6期35卷 312-324页

作者： tianyi zhou Hang GAO Xuanping WANG Lun LI Qing LIU Key Laboratory for Precision and Non-traditional Machining Technology of Ministry of Education Dalian University of TechnologyDalian 116024China AECC Shenyang Liming Aero-engine Co. LtdChina

In the docking process of aeroengine rotor parts,docking accuracy that indicates the gaps between the end faces is strictly required.A key issue is improving docking accuracy using automated docking *** this paper,a systematic study is carried out on the error modeling and compensation of a novel six-degrees-of-freedom(6-DOF)docking equipment for aeroengine ***,a new model for indicating the main indexes of docking accuracy is ***,the error model of a specially designed 6-DOF docking equipment is established based on a modified Denavit Hartenberg method with five ***,two error compensation methods are *** on the above models,a docking accuracy simulation algorithm is proposed using the Monte Carlo ***,verification experiments are *** results show that,for the maximum values and standard deviations of the gaps between the rotor end-faces in the actual and target positions and attitudes,i.e.,main indexes that represent docking accuracy,the deviation rates between the simulation and experimental results are less than20%.The modeling methods have referential *** decline rates of these values are 50–65%when using the two proposed compensation *** compensation methods significantly improve the docking accuracy.

关键词： Accuracy analysis Aeroengine rotor Docking Error compensation Error models Multi-degree-of-freedom structures

Polarized imaging dynamic light scattering for simultaneous measurement of nanoparticle size and morphology

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Particuology 2024年第2期85卷 213-223页

作者： Bingyao Wang tianyi Cai Xiaoshu Cai Wu zhou Zeqi Liu Schoolof Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai200093China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai200093China Jiaxing MeaParTech Instrument Technology Co. LtdZhejiang314000China

The performance of nanoparticles is often affected by particle size and ***,electron microscopy or atomic force microscopy is typically utilized to determine the size and morphology of ***,there are issues such as difficult sample preparation,long processing times,and challenges in quantitative ***,it is of great significance to develop a fast,accu-rate,and statistical method to measure the size and morphology of *** this study,a new method,called polarized imaging dynamic light scattering(PIDLS),is *** nanoparticles are irradiated with a vertical linearly polarized laser beam,and a polarization camera collected the dynamic light scattering images of particles at four different polarization directions(0°,45°,90°,and 135°)at a scattering angle of 90°.The average particle size and distribution are obtained using the imaging dy-namic light scattering method at 0°polarization direction,and the morphology of the particles is ob-tained based on the depolarization patterns of the scattered *** optical sphericityΦis defined based on the degree of linear polarization(DoLP).It is also implemented for the quantitative evaluation of the sphericity of the nanoparticles,including spherical,octahedral,nanoplate,nanorod,and linear *** with the Poincarésphere parameterψ,the morphology of the nanoparticles can be roughly *** addition,PIDLS enables the measurement of particle size and morphology distributions simultaneously for evaluating the uniformity of *** effectiveness of PIDLS is verified by the measurement of five kinds of industrial titanium dioxide as well.

关键词： Imaging dynamic light scattering Polarized light scattering Non-spherical nanoparticles Morphology Online measurement

Two-dimensional plane strain consolidation of unsaturated soils considering the depth-dependent stress

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第6期15卷 1603-1614页

作者： Lei Wang Sidong Shen tianyi Li Minjie Wen Annan zhou School of Urban Railway Transportation Shanghai University of Engineering ScienceShanghai201620China Key Laboratory of Soft Soils and Geoenvironmental Engineering of Ministry of Education Zhejiang UniversityHangzhou310058China School of Civil Environmental and Chemical EngineeringRoyal Melbourne Institute of Technology(RMIT)MelbourneVIC3001Australia

In practical engineering,the total vertical stress in the soil layer is not constant due to stress diffusion,and varies with time and ***,the purpose of this paper is to investigate the effect of stress diffusion on the two-dimensional(2D)plane strain consolidation properties of unsaturated soils when the stress varies with time and depth.A series of semi-analytical solutions in terms of excess pore air and water pressures and settlement for 2D plane strain consolidation of unsaturated soils can be derived with the joint use of Laplace transform and Fourier sine series ***,the inverse Laplace transform of the semi-analytical solution is given in the time domain using a self-programmed code based on Crump’s *** reliability of the obtained solutions is proved by the ***,the 2D plots of excess pore pressures and the curves of settlement varying with time,considering different physical parameters of unsaturated soil stratum and depth-dependent stress,are depicted and analyzed to study the 2D plane strain consolidation properties of unsaturated soils subjected to the depthdependent stress.

关键词： Semi-analytical solutions Two-dimensional(2D)plane strain consolidation Unsaturated soils Depth-dependent stress Laplace transform

The squeeze flow of a bi-viscosity fluid between two rigid spheres with wall slip

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Particuology 2023年第8期79卷 153-160页

作者： tianyi zhou Da Lin Yujia Shen Wei Yang Chunhui Xu Xuedong Chen College of Science China Agricultural UniversityBeijing100083China Chinese Academy of Agricultural Mechanization Sciences Group Co. LtdBeijing100083China

In this paper,the squeeze flow between two rigid spheres with a bi-viscosity fluid is *** on lubrication theory,the squeeze force is calculated by deriving the pressure and velocity *** results of the normal squeeze force are discussed,and fitting functions of the squeeze and correction coefficients are *** squeeze force between the rigid spheres increases linearly or logarithmically with the velocity when most or part of the boundary fluid reaches the yield state,***,the slip correction coefficient decreases with the increase in the *** investigation may contribute to the further study of bi-viscosity fluids between rigid spheres with wall slip.

关键词： Squeeze flow Bi-viscosity fluid Rigid spheres Wall slip

Operando modeling and measurements:Powerful tools for revealing the mechanism of alkali carbonate-based sorbents for CO_(2)capture in real conditions

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Frontiers in Energy 2023年第3期17卷 380-389页

作者： tianyi CAI Mengshi WANG Xiaoping CHEN Ye WU Jiliang MA Wu zhou School of Energy and Power Engineering Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power EngineeringUniversity of Shanghai for Science and TechnologyShanghai 200093China Key Laboratory of Energy Thermal Conversion and Control of the Ministry of Education School of Energy and EnvironmentSoutheast UniversityNanjing 210096China Key Laboratory of Thermal Control of Electronic Equipment and Advanced Combustion Laboratory of the Ministry of Industry and Information Technology School of Energy and Power EngineeringNanjing University of Science and TechnologyNanjing 210094China

Alkalicarbonate-based sorbents(ACSs),including Na_(2)CO_(3)-and K2CO_(3)-based sorbents,are promising for CO_(2)***,the complex sorbent components and operation conditions lead to the versatile kinetics of CO_(2)sorption on these *** paper proposed that operando modeling and measurements are powerful tools to understand the mechanism of sorbents in real operating conditions,facilitating the sorbent development,reactor design,and operation parameter *** reviewed the theoretical simulation achievements during the development of *** elucidated the findings obtained by utilizing density functional theory(DFT)calculations,ab initio molecular dynamics(AIMD)simulations,and classical molecular dynamics(CMD)simulations as *** hygroscopicity of sorbent and the humidity of gas flow are crucial to shifting the carbonation reaction from the gas-solid mode to the gas-liquid mode,boosting the ***,it briefly introduced a machine learning(ML)approach as a promising method to aid sorbent ***,it demonstrated a conceptual compact operando measurement system in order to understand the behavior of ACSs in the real operation *** proposed measurement system includes a micro fluidizedbed(MFB)reactor for kinetic analysis,a multi-camera sub-system for 3D particle movement tracking,and a combined Raman and IR sub-system for solid/gas components and temperature *** is believed that this system is useful to evaluate the real-time sorbent performance,validating the theoretical prediction and promoting the industrial scale-up of ACSs for CO_(2)capture.

关键词： CO_(2)capture carbonation theoretical modeling operando techniques reaction visualization