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Compressibility characteristics of bio-cemented calcareous sand treated through the bio-stimulation approach

Journal of Rock Mechanics and Geotechnical Engineering 2023年第2期15卷 510-522页

作者： Yijie Wang ningjun jiang Alexandra Clarà Saracho Ogul Doygun Yanjun Du Xiaole Han Institute of Geotechnical Engineering Southeast UniversityNanjingChina Department of Civil and Environmental Engineering University of Hawaii at ManoaHonoluluUSA Department of Engineering Cambridge UniversityCambridgeUK Geosyntec Consultants Inc.Huntington BeachUSA

Calcareous sand is widely present in coastal areas around the world and is usually considered as a weak and unstable material due to its high compressibility and low strength.Microbial-induced calcium carbonate precipitation(MICP)is a promising technique for soil improvement.However,the commonly adopted bio-augmented MICP approach is in general less compatible with the natural soil environment.Thus,this study focuses on the bio-stimulated MICP approach,which is likely to enhance the dominance of ureolytic bacteria for longer period and thus is deemed more efficient.The main objective of this paper is to investigate the compressibility of calcareous sand treated by bio-stimulated MICP approach.In the current study,a series of one-dimension compression tests was conducted on bio-cemented sand pre-pared via bio-stimulation with different initial relative densities(D r).Based on the obtained compression curves and particle size distribution(PSD)curves,the parameters including cementation content,the coefficient of compressibility(a v),PSD,relative breakage(B r),and relative agglomeration(A r)were discussed.The results showed that a v decreased with the increasing cementation content.The bio-cemented sand prepared with higher initial D r had smaller(approximately 20%e70%)a v values than that with lower initial D r.The specimen with higher initial D r and higher cementation content resulted in smaller B r but larger A r.Finally,a conceptual framework featuring multiple contact and damage modes was proposed.

关键词： Calcareous sand Bio-cementation Bio-stimulation Compressibility

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Effects of biochar-amended alkali-activated slag on the stabilization of coral sand in coastal areas

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第3期15卷 760-772页

作者： Xiaole Han ningjun jiang Fei Jin Krishna RReddy Yijie Wang Kaiwei Liu Yanjun Du Department of Civil and Environmental Engineering University of Hawaii at ManoaHonoluluUSA Institute of Geotechnical Engineering Southeast UniversityNanjing210096China School of Engineering Cardiff UniversityCardiffUK Department of Civil Materialsand Environmental EngineeringUniversity of Illinois at ChicagoChicagoUSA College of Materials and Chemical Engineering Anhui Jianzhu UniversityHefei230601China

Coral sand is widely encountered in coastal areas of tropical and subtropical regions.Compared with silica sand,it usually exhibits weaker performance from the perspective of engineering geology.To improve the geomechanical performance of coral sand and meet the requirement of foundation construction in coastal areas,a novel alkali activation-based sustainable binder was developed.The alkaliactivated slag(AAS)binder material was composed of ground granulated blast-furnace slag(GGBS)and hydrated lime with the amendment of biochar,an agricultural waste-derived material.The biocharamended AAS stabilized coral sand was subjected to a series of laboratory tests to determine its mechanical,physicochemical,and microstructural characteristics.Results show that adding a moderate amount of biochar in AAS could improve soil strength,elastic modulus,and water holding capacity by up to 20%,70%,and 30%,respectively.Moreover,the addition of biochar in AAS had a marginal effect on the sulfate resistance of the stabilized sand,especially at high biochar content.However,the resistance of the AAS stabilized sand to wet-dry cycles slightly deteriorated with the addition of biochar.Based on these observations,a conceptual model showing biochar-AAS-sand interactions was proposed,in which biochar served as an internal curing agent,micro-reinforcer,and mechanically weak point.

关键词： Coral sand Soil stabilization Biochar Alkali activation

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基于“互联网+教育”的城市地下空间工程专业教学改革与实践研究

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科教文汇 2024年第5期 66-69页

作者：蒋宁俊杜延军丁建文东南大学岩土工程研究所江苏南京211189

教育信息化是顺应智能环境下教育发展的必然选择,是加快实现教育现代化的有效途径。该研究提出基于“互联网+教育”的城市地下空间工程专业课程改革理念。紧跟城市地下空间开发产业发展对高技术人才的需求,建立城市地下空间工程教学内... 详细信息

教育信息化是顺应智能环境下教育发展的必然选择,是加快实现教育现代化的有效途径。该研究提出基于“互联网+教育”的城市地下空间工程专业课程改革理念。紧跟城市地下空间开发产业发展对高技术人才的需求,建立城市地下空间工程教学内容动态调整机制,建设城市地下空间工程开放共享优质教学资源,构建以学生为中心的城市地下空间工程课程建设新模式,满足学生时时学习、处处学习、终身学习的需求。

关键词：互联网+ 城市地下空间工程课程改革新模式

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Aquafeed fermentation improves dietary nutritional quality and benefits feeding behavior,meat flavor,and intestinal microbiota of Chinese mitten crab(Eriocheir sinensis)

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Animal Nutrition 2023年第3期14卷 1-19页

作者： Weibo jiang Xiaoyan Jia ningjun Xie Chuang Wen Shuo Ma Guangzhen jiang Xiangfei Li Cheng Chi Dingdong Zhang Wenbin Liu Key Laboratory of Aquatic Nutrition and Feed Science of jiangsu Province College of Animal Science and TechnologyNanjing Agricultural UniversityNanjing 210095China

Normally,proper fermentation can be an efficient and widely used method to improve feed quality in animal rearing;however,the studies on crustaceans,especially Eriocheir sinensis,remain limited.This study aimed to investigate whether feed fermentation could meliorate dietary nutritional value and benefit E.sinensis rearing.First,non-fermented feed(NFD)and fermented feed(FD)were produced and assessed,respectively.Then,the“Y”maze feed choice behavior test(180 times;30 times,6 rounds)was conducted to assess the attractiveness of these 2 feeds for crabs.Finally,a total of 80 crabs(44.10±0.80 g)were randomly assigned into 2 groups with 4 replicates,and fed the experimental diets for 8 weeks to evaluate the effects of each feed on growth,antioxidant capacity,meat flavor,and intestinal microbiota.In this study,FD showed higher levels of crude protein(P<0.01),soluble protein(P<0.01),amino acids(P<0.05),lactic acid(P<0.001),and lower levels of crude fiber(P<0.05)and antinutritional factors(agglutinin,trypsin inhibitor,glycinin,andβ-conglycinin)(P<0.001)than NFD.Additionally,FD was more attractive to crabs than NFD(P<0.01)and it stimulated the appetite of crabs more than NFD(P<0.05).The growth performance,feed efficiency,and digestive enzyme activity of FDfed crabs were significantly higher than those of NFD-fed crabs(P<0.05).The electronic sensory measurements and free amino acid profiles revealed that the FD diet had positive impacts on the meat flavor of crabs,particularly in“sweet”and“umami”tastes.Moreover,the antioxidant capacity of FD-fed crabs was significantly higher than that of NFD-fed crabs(P<0.05).Fermented feed also affected the diversity and composition of intestinal microflora.The functional prediction of microbial communities showed that crabs fed FD had a better microecological environment in the intestine.In conclusion,the fermentation of aquafeed could be an effective approach to enhance feed quality and therefore benefit E.sinensis rearing.

关键词： Fermentation feed Feed attraction Meat flavor Intestinal microflora Nutritional composition Eriocheir sinensis

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Predictor-based model reference adaptive roll and yaw control of a quad-tiltrotor UAV

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Chinese Journal of Aeronautics 2020年第1期33卷 282-295页

作者： ningjun LIU Zhihao CAI jiang ZHAO Yingxun WANG School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100083China

An attempt is made to apply modern control technology to the roll and yaw control of a rudderless quad-tiltrotor Unmanned Aerial Vehicle(UAV)in the latter part of the flight mode transition,where aerodynamic forces on the tiltrotor’s wings start to take effect.A predictor-based adaptive roll and yaw controller is designed to compensate for system uncertainties and parameter changes.A dynamics model of the tiltrotor is built.A Radial-Basis Function(RBF)neural network and offline adaptation method are used to reduce flight controller workload and cope with the nonlinearities in the controls.Simulations are conducted to verify the reference model response tracking and yaw-roll control decoupling ability of the adaptive controller,as well as the validity of the offline adaptation method.Flight tests are conducted to confirm the ability of the adaptive controller to track different roll and yaw reference model responses.The decoupling of roll and yaw controls is also tested in flight via coordinated turn maneuvers with different rotor tilt angles.

关键词： Adaptive control Flight control Tiltrotor UAV VTOL

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Fast level-flight to hover mode transition and altitude control in tiltrotor’s landing operation

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Chinese Journal of Aeronautics 2021年第1期34卷 181-193页

作者： ningjun LIU Zhihao CAI Yingxun WANG jiang ZHAO Institute of Unmanned System Beihang UniversityBeijing 100083China School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100083China

An attempt is made to implement a faster level-flight to hover mode transition in tiltrotor’s landing process for the purpose of shortening its landing time. A three-stage tiltrotor landing maneuver is designed, and corresponding control modules and algorithms are created based on the analysis of the flight dynamics and the required actions of tiltrotor’s landing operation. As the altitude control is vital for tiltrotor’s near-ground landing, an Extended State Observer(ESO) control module of the Active Disturbance Rejection Control(ADRC) is designed to reduce altitude fluctuations in the fast mode transition, which makes the designed maneuver workable at very low altitudes. Simulations are conducted to verify the effectiveness of the designed maneuver and the validity of ESO control in various flight conditions. Flight test results that finally prove the effectiveness of the desired fast transition maneuver are reported.

关键词： Tiltrotor Transition Flight control VTOL UAV ADRC

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Adsorption Performance of Sliding Wall-Climbing Robot

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Chinese Journal of Mechanical Engineering 2010年第6期23卷 733-741页

作者： LI Jun GAO Xueshan FAN ningjun LI Kejie jiang Zhihong jiang Zhijian School of Mechatronical Engineering Beijing Institute of Technology Beijing 100081 China School of Electric and Information Engineering Beijing University of Civil Engineering and Architecture Beo＇ing 100044 China

Sliding wall-climbing robot （SWCR） is applied worldwide for its continuous motion, however, considerable air leakage causes two problems： great power consumption and big noise, and they constraint the robot＇s comprehensive performance. So far, effective theoretical model is still lacked to solve the problems. The concept of SWCR＇s adsorption performance is presented, and the techniques of improving utilization rate of given adsorption force and utilization rate of power are studied respectively to improve SWCR＇s adsorption performance. The effect of locomotion mechanism selection and seal＇s pressure allocation upon utilization rate of given adsorption force is discussed, and the theoretical way for relevant parameters optimization are provided. The directions for improving utilization rate of power are pointed out based on the detail analysis results of suction system＇s thermodynamics and hydrodynamics. On this condition, a design method for SWCR-specific impeller is presented, which shows how the impeller＇s key parameters impact its aerodynamic performance with the aid of computational fluid dynamics （CFD） simulations. The robot prototype, BIT Climber, is developed, and its functions such as mobility, adaptability on wall surface, payload, obstacle ability and wall surface inspection are tested. Through the experiments for the adhesion performance of the robot adsorption system on the normal wall surface, at the impeller＇s rated rotating speed, the total adsorption force can reach 237.2 N, the average effective negative pressure is 3.02 kPa and the design error is 3.8% only, which indicates a high efficiency. Furthermore, it is found that the robot suction system＇s static pressure efficiency reaches 84% and utilization rate of adsorption force 81% by the experiment. This thermodynamics model and SWCR-specific impeller design method can effectively improve SWCR＇s adsorption performance and expand this robot applicability on the various walls. A sliding wall-climbing robot with high adhesion efficiency is develope

关键词： wall-climbing robot adsorption performance centrifugal impeller CFD simulation

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Onboard actuator model-based Incremental Nonlinear Dynamic Inversion for quadrotor attitude control:Method and application

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Chinese Journal of Aeronautics 2021年第11期34卷 216-227页

作者： Zexin WANG jiang ZHAO Zhihao CAI Yingxun WANG ningjun LIU School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100191China

This paper addresses the robust attitude control problem for quadrotors subject to model mismatch and disturbances.A dynamic inversion based attitude control scheme is proposed,which consists of an outer loop attitude controller and an inner loop angular acceleration controller.The attitude controller is designed based on the Nonlinear Dynamic Inversion(NDI)to precisely linearize the nonlinear dynamics between the angular acceleration and the attitude.An onboard actuator model-based Incremental Nonlinear Dynamic Inversion(INDI)controller is designed in the angular acceleration control loop to improve the robustness against the model mismatch and disturbances.Meanwhile,the onboard actuator model with a modified structure eliminates the oscillation phenomenon when the sampling rate of the controller is higher than that of the actuator.Numerical simulations and flight tests demonstrate the effectiveness and robustness of the proposed controller in comparison with the PID controller.

关键词： Actuator Attitude control INDI NDI Quadrotor

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Control and dynamics analysis for miniature autogyro and compound autogyro

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Science China(Information Sciences) 2019年第1期62卷 64-66页

作者： Zhihao CAI ningjun LIU jiang ZHAO Yingxun WANG School of Automation Science and Electrical Engineering Beihang University

Dear editor,An autogyro is a type of aircraft achieving effective low-speed flight and short take-off and landing performance. A compound autogyro is a "pure" autogyro, designed with additional fixed wings. Its rotor ... 详细信息

关键词： Control and dynamics analysis for miniature autogyro and compound autogyro Figure

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Visualization of CO_2 and oil immiscible and miscible flow processes in porous media using NMR micro-imaging

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Petroleum Science 2011年第2期8卷 183-193页

作者： Zhao Yuechao SongYongchen Liu Yu jiang Lanlan Zhu ningjun Key Laboratory of Ocean Energy Utilization and Energy Conservation of the Ministry of Education Dalian University ofTechnology Dalian Liaoning 116024 China

CO2 flooding is considered not only one of the most effective enhanced oil recovery （EOR） methods, but also an important alternative for geological CO2 storage. In this paper, the visualization of CO2 flooding was studied using a 400 MHz NMR micro-imaging system. For gaseous CO2 immiscible displacement, it was found that CO2 channeling or fingering occurred due to the difference of fluid viscosity and density. Thus, the sweep efficiency was small and the final residual oil saturation was 53.1%. For supercritical CO2 miscible displacement, the results showed that piston-like displacement occurred, viscous fingering and the gravity override caused by the low viscosity and density of the gas was effectively restrained, and the velocity of CO2 front was uniform. The sweep efficiency was so high that the final residual oil saturation was 33.9%, which indicated CO2 miscible displacement could enhance oil recovery more than CO2 immiscible displacement. In addition, the average velocity of CO2 front was evaluated through analyzing the oil saturation profile. A special core analysis method has been applied to in-situ oil saturation data to directly evaluate the local Darcy phase velocities and capillary dispersion rate.

关键词： NMR micro-imaging porous media CO2 flooding enhanced oil recovery saturation

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