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Effect of loading rate on shear strength parameters of mechanically and biologically treated waste

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Frontiers of Environmental Science & engineering 2022年第12期16卷 121-132页

作者： Guoyang Fan Zhenying Zhang Jiahe Zhang Jiayue Zhang Qiaona Wang Min Wang Bang Wang Chengyu Nie school of civil engineering and architecture Zhejiang Sci-tech UniversityHangzhou310018China

Mechanical biological treatment(MBT)technology has attracted increasing attention because it can reduce the volume of waste *** deal with the current trend of increasing waste,MBT practices are being adopted to address waste generated in developing urban *** this study,a total of 20 specimens of consolidated undrained triaxial tests were conducted on waste obtained from the Hangzhou Tianziling landfill,China,to evaluate the effect of loading rate on the shear strength parameters of MBT *** MBT waste samples exhibited an evident strain-hardening behavior,and no peak was observed even when the axial strain exceeded 25%.Further,the shear strength increased with an increase in the loading rate;the effect of loading rate on shear strength under a low confining pressure was greater than that under a high confining ***,the shear strength parameters of MBT waste were related to the loading *** relationship between the cohesion,internal friction angle,and logarithm of the loading rate could be fitted to a linear relationship,which was established in this ***,the ranges of shear strength parameters cohesion c and effective cohesion c′were determined as 1.0–8.2 kPa and 2.1–14.9 kPa,respectively;the ranges of the internal friction angleφand effective internal friction angleφ’were determined as 16.2°–29°and 19.8°–43.9°,*** results could be used as a valuable reference for conducting stability analyses of MBT landfills.

关键词： Mechanically and biologically treated waste Landfill Triaxial test Loading rate Axial strain Shear strength parameter

Multi-Objective Optimization of A Semisubmersible for Ultra-Deep Water

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China Ocean engineering 2008年第1期22卷 11-20页

作者：陈新权谭家华 school of Naval architecture Ocean and Civil EngineeringShanghai JiaoTong University

Semisubmersible will work well when oil exploitation goes to ultra-deep water because of its variable load capacities, and good motion performance in extreme waves. It is considered to be a main type of platform while the water depth is more than 3000 meters. This paper establishes a multi-objective optimization model of semisubmersible for ultra-deep water, and it is solved by a multi-objective genetic algorithm--NSGA-Ⅱ. The model is applied to a practical design, and Pareto results are obtained. The effectiveness of the method is verified by hydrodynamic analysis.

关键词： semisubmersible ultra-deep water hull steel weight heave multi-objectlve optimization Pareto hydrodynamics

Experimental Investigation on the Vibration Attenuation of Tensegrity Prisms Integrated with Particle Dampers

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Acta Mechanica Solida Sinica 2022年第4期35卷 672-681页

作者： Si-Qi An Hao-Ran Zou Wen-Hao Li Zi-Chen Deng school of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi’an710072China

Tensegrities made of tensile strings and compressed struts possess large strength-to-mass ratio values but tend to experience non-negligible vibration in dynamic environments because of poor structural ***,we introduce particle dampers into a tensegrity prism to attenuate vibration,with the goal of establishing a lightweight and efficient approach of vibration *** integrate the particle dampers and the tensegrity,a novel strut structure formed by assembling a solid strut and a hollow strut is devised,in which granular materials are inserted to develop a particle *** vibration attenuation performance of the tensegrity prism is investigated through exciter *** to the experimental parametric study,the influences of system parameters including excitation magnitude,the filling height of particles,particle size and the configuration of tensegrity prism on the vibration attenuation performance is *** addition,the experimental results regarding the dependence of the vibration attenuation on the system parameters are interpreted by the mechanism of collisions and frictions between particles and between particles and *** maximal vibration attenuation ratio of 76%can be achieved in the ***,this research can provide insights into the design of lightweight tensegrity structures where vibration suppression is important,particularly in some dynamic environments.

关键词： Tensegrity structures Particle dampers Vibration suppression Assembling struts

Attractors with controllable basin sizes from cooperation of contracting and expanding dynamics in pulse-coupled oscillators

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Chinese Physics B 2019年第1期28卷 267-274页

作者： Hai-Lin Zou Zi-Chen Deng school of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi’an 710072China

Unstable attractors are a novel type of attractor with local unstable dynamics, but with positive measures of ***, we introduce local contracting dynamics by slightly modifying the function which mediates the interactions among the oscillators. Thus, the property of unstable attractors can be controlled through the cooperation of expanding and contracting dynamics. We demonstrate that one certain type of unstable attractor is successfully controlled through this simple modification. Specifically, the staying time for unstable attractors can be prolonged, and we can even turn the unstable attractors into stable attractors with predictable basin sizes. As an application, we demonstrate how to realize the switching dynamics that is only sensitive to the finite size perturbations.

关键词： unstable attractors switching dynamics pulse-coupled oscillators

Ignition Characteristics of Lean Coal Used a Novel Alternating-Current Plasma Arc Approach

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Journal of Thermal Science 2022年第2期31卷 571-581页

作者： YAN Gaocheng school of Electric Power Civil Engineering and ArchitectureShanxi UniversityTaiyuan 030013China

In order to achieve the target of reducing oil consumption to zero for pulverized coal(PC)boiler in power plant,the paper developed a novel coal pulverized ignition approach,called as Alternating-Current plasma(AC plasma)ignition,with the advantages of excellent PC combustion behavior and longer electrode *** scientific principle of how to generate the AC plasma arc was elaborated in ***,the experiments on life-span of electrodes inside AC plasma generator had been conducted,finding a workable way to extend its life-span beyond 530 ***,a new AC plasma burner specifically designed for lean coal according to the principle of PC staged combustion had been illustrated with diagrams and then used to ignite the PC-air stream under four kinds of conditions with a varying AC plasma power from 150 kW to 300 kW,focusing on analyses of the influence of AC plasma power on combustion behaver,such as combustion temperature,carbon burnout rate as well as PC combustion *** following results showed that in the case of the power of the AC plasma was P=300 kW,a satisfied PC combustion process could achieved,with the average PC combustion temperature of about 940°C,combustion flame length of 6.3 m,and the total carbon burnout rate of up to 52.2%.In addition,about 80%of the nozzle outlet section was filled with bright flame,while 81%of the PC was in zone of the cylindrical flame *** PC combustion modes were changed repeatedly during the process of combustion,which went from homogeneous combustion mode at initial ignition stage to combined combustion mode and heterogeneous combustion mode at middle stage,finally to combined combustion mode at later *** research conclusion in this paper has proved that the AC plasma ignition approach is feasible and effective to ignite low-rank coal without the present of fuel oil.

关键词： pulverized coal combustion alternating-current plasma ignition oil-free ignition utility boiler start-up combustion mode

Resonance System Reliability and Sensitivity Analysis Method for Axially FGM Pipes Conveying Fluid with Adaptive Kriging Model

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Acta Mechanica Solida Sinica 2022年第6期35卷 1021-1029页

作者： Xin Fan Nan Wu Yongshou Liu Qing Guo school of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi’an710129China

This paper aims to solve the resonance failure probability and develop an effective method to estimate the effects of variables and failure modes on failure probability of axially functionally graded material(FGM)pipe conveying ***,the natural frequency of axially FGM pipes conveying fluid is calculated using the differential quadrature method(DQM).A variable sensitivity analysis(VSA)is introduced to measure the effect of each random variable,and a mode sensitivity analysis(MSA)is introduced to acquire the importance ranking of failure ***,an active learning Kriging(ALK)method is established to calculate the resonance failure probability and sensitivity indices,which greatly improves the application of resonance reliability analysis for pipelines in engineering *** on the resonance reliability analysis method,the effects of fluid velocity,volume fraction and fluid density of axially FGM pipe conveying fluid on resonance reliability are *** results demonstrate that the proposed method has great performance in the anti-resonance analysis of pipes conveying fluid.

关键词： Resonance reliability analysis Simply supported pipe conveying fluid Differential quadrature method Variable sensitivity analysis Mode sensitivity analysis Active learning Kriging model

Experimental Investigation and Optimization Design of Multi-Support Pipeline System

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Chinese Journal of Mechanical engineering 2021年第2期34卷 135-149页

作者： Xiantao Zhang Wei Liu Yamei Zhang Yujie Zhao school of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi’an 710129China

The design of aircraft hydraulic pipeline system is limited by many factors,such as the integrity of aviation structure or narrow installation space,so the limited clamp support position should be *** paper studied the frequency adjustment and dynamic responses reduction of the multi-support pipeline system through experiment and numerical *** avoid the resonance of pipeline system,we proposed two different optimization programs,one was to avoid aero-engine working range,and another was to avoid aircraft hydraulic pump pulsation *** optimization method was introduced in this paper to obtain the optimal clamp *** experiments were introduced to validate the optimization results,and the theoretical optimization results can agree well with the *** regard to avoiding the aero-engine vibration frequency,the test results revealed that the first natural frequency was far from the aero-engine vibration *** the dynamic frequency sweep results showed that no resonance occurred on the pipeline in the engine vibration frequency range after ***,with regard to avoiding the pump vibration frequency,the test results revealed that natural frequencies have been adjusted and far from the pump vibration *** the dynamic frequency sweep results showed that pipeline under optimal clamp position cannot lead to *** sensitivity analysis results revealed the changing relationships between different clamp position and natural *** study can provide helpful guidance on the analysis and design of practical aircraft pipeline.

关键词： Multi-support pipeline system Clamp position optimization Frequency adjustment design Dynamic responses

Characteristics of Gas-Liquid Slug Flow in Microchannel by Instantaneous Liquid Film Thickness Measurement

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Journal of Thermal Science 2022年第4期31卷 1194-1205页

作者： SUN Yanhong CHEN Wenjie LU Jinli WANG Changlong school of civil engineering and architecture Anhui University of TechnologyMa'anshan 243002China

This paper seeks to decipher the exact relationship between the liquid film thickness and the hydrodynamics of gas-liquid slug flows. An instantaneous measurement system is developed by integrating the laser focus displacement meter(LFDM) and high-speed camera to characterize the temporal evolution of the liquid film and the dynamic characteristics of continuous slug flows. A glass tube with internal diameter of 0.75 mm is used and the tested ranges of superficial gas and liquid velocities are 0.01–1.2 m/s and 0.01–0.09 m/s respectively. The non-zero signals of LFDM representing the bubble slug flows changed from regular periodic intervals to chaotic fluctuations when slug-annular flow pattern appears. The dominant frequencies of the periodic intermittent slug flows increased from about 0.5–2 Hz to nearly 10–20 Hz as the superficial gas velocity rised from 0.025 to 0.78 m/s. The bubble and liquid slug lengths calculated by the time interval of liquid film thickness and bubble velocity correlated well with the empirical model. Meantime, the average value of void fraction derived from the calculation of transient liquid film thickness shows a linear growth with the gas holdup ratio.

关键词： liquid film thickness slug flow bubble/slug length void fraction

Regional moment-independent sensitivity analysis with its applications in engineering

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Chinese Journal of Aeronautics 2017年第3期30卷 1031-1042页

作者： Changcong ZHOU Chenghu TANG Fuchao LIU Wenxuan WANG Zhufeng YUE school of Mechanics Civil Engineering and Architecture Northwestern Polytechnical University Xi'an 710129 China

Traditional Global Sensitivity Analysis（GSA） focuses on ranking inputs according to their contributions to the output ***,information about how the specific regions inside an input affect the output is beyond the traditional GSA *** fully address this issue,in this work,two regional moment-independent importance measures,Regional Importance Measure based on Probability Density Function（RIMPDF） and Regional Importance Measure based on Cumulative Distribution Function（RIMCDF）,are introduced to find out the contributions of specific regions of an input to the whole output *** two regional importance measures prove to be reasonable supplements of the traditional GSA *** ideas of RIMPDF and RIMCDF are applied in two engineering examples to demonstrate that the regional moment-independent importance analysis can add more information concerning the contributions of model inputs.

关键词： Cumulative distribution function Moment-independent Probability density function Regional importance measure Sensitivity analysis Uncertainty