A new geopolymeric grout blended completely weathered granite with blast-furnace slag

Zhang, Jian,Li, Shucai,Li, Zhaofeng,Li, Hengtian,Du, Junqi,Gao, Yifan,Liu, Chao,Qi, Yanhai,Wang, Wenlong Techno-Press 2020 Advances in concrete construction Vol.9 No.6

In order to reduce the usage of cement slurry in grouting engineering and consume the tunnel excavation waste soil, a new geopolymeric grouting material (GGM) was prepared by combine completely weathered granite (CWG) and blast-furnace slag (BFS), which can be applied to in-situ grouting treatment of completely weathered granite strata. The results showed CWG could participate in the geopolymerization process, and GGM slurry has the characteristics of short setting time, high flowability, low viscosity, high stone rate and high mechanical strength, and a design method of grouting pressure based on viscosity evolution was proposed. By adjusted the content of completely weathered granite and alkali activator concentration, the setting time of GGM were ranged from 5 to 30 minutes, the flowability was more than 23.5 cm, the stone rate was higher than 90%, the compressive strength of 28 days were 7.8-16.9 MPa, the porosity were below 30%. This provides a novel grouting treatment and utilizing excavated soil of tunnels in the similar strata.

Sliding-mode Observers for Nonlinear Systems with Unknown Inputs and Measurement Noise

Junqi Yang,Fanglai Zhu,Wei Zhang 제어·로봇·시스템학회 2013 International Journal of Control, Automation, and Vol.11 No.5

This paper deals with the design of observers for Lipschitz nonlinear systems with not only unknown inputs but also measurement noise when the observer matching condition is not satisfied. First, an augmented vector is introduced to construct an augmented system, and an auxiliary output vector is constructed such that the observer matching condition is satisfied and then a high-gain sliding mode observer is considered to get the exact estimates of both the auxiliary outputs and their derivatives in a finite time. Second, for nonlinear system with both unknown inputs and measurement noise, an adaptive robust sliding mode observer is developed to asymptotically estimate the system’s states, and then an unknown input and measurement noise reconstruction method is proposed. Finally, a numerical simulation example is given to illustrate the effectiveness of the proposed methods.

Influences of genetically perturbing synthesis of the typical yellow pigment on conidiation, cell wall integrity, stress tolerance, and cellulase production in Trichoderma reesei

Zhang Weixin,An Ning,Guo Junqi,Wang Zhixing,Meng Xiangfeng,Liu Weifeng 한국미생물학회 2021 The journal of microbiology Vol.59 No.4

The prominent protein producing workhorse Trichoderma reesei secretes a typical yellow pigment that is synthesized by a gene cluster including two polyketide synthase encoding genes sor1 and sor2. Two transcription factors (YPR1 and YPR2) that are encoded in the same cluster have been shown to regulate the expression of the sor genes. However, the physiological relevance of the yellow pigment synthesis in T. reesei is not completely clear. In this study, a yellow pigment hyper-producer OEypr1 and three yellow pigment non-producers, OEypr1-sor1, Δypr1, and OEypr2, were constructed. Their phenotypic features in mycelial growth, conidiation, cell wall integrity, stress tolerance, and cellulase production were determined. Whereas hyperproduction of the yellow pigment caused significant defects in all the physiological aspects tested, the non-producers showed similar colony growth, but improved conidiation, maintenance of cell wall integrity, and stress tolerance compared to the control strain. Moreover, in contrast to the severely compromised extracellular cellobiohydrolase production in the yellow pigment hyperproducer, loss of the yellow pigment hardly affected induced cellulase gene expression. Our results demonstrate that interfering with the yellow pigment synthesis constitutes an engineering strategy to endow T. reesei with preferred features for industrial application.

Frequency capture characteristic of a vibration system driven by four counterrotating unbalanced rotors

Xiaozhe Chen,Junqi Liu,Jiaqi Zhang,Baitong Zhou 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.4

This study investigates the frequency capture characteristic of four unbalanced rotors in multi-frequency ranges. First, using the average method, the synchronous condition of four unbalanced rotors in a vibration system is derived. Then, the stability condition of the vibration system is deduced, which meets the Routh-Hurwitz criterion. On the basis of the theoretical analysis, the phase difference in steady states and the resultant force on the rigid body at different excitation frequency regions are discussed numerically. Five sets of experiments are done to investigate synchronization and the Sommerfeld effect. The results prove that the vibration system has three motion states according to the excitation frequency in different frequency regions. Two stable states appear in the near-resonance region of the system. This study concludes that the synchronization of unbalanced rotors formed before and after the natural frequency is crucial for the occurrence of the Sommerfeld effect. This work can provide theoretical and experimental reference for the design of new vibration equipment in engineering.

IL28B Is Associated with Outcomes of Chronic HBV Infection

Xiaodong Shi,Junqi Niu,Xiumei Chi,Yu Pan,Yanhang Gao,Wanyu Li,Chen Yang,Jin Zhong,Damo Xu,Manna Zhang,Gerald Minuk,Jing Jiang 연세대학교의과대학 2015 Yonsei medical journal Vol.56 No.3

Purpose: The role of IL28B gene variants and expression in hepatitis B virus (HBV) infections are not well understood. Here, we evaluated whether IL28B gene expression and rs12979860 variations are associated with HBV outcomes. Materialsand Methods: IL28B genetic variations (rs12979860) were genotyped by pyrosequencingof DNA samples from 137 individuals with chronic HBV infection [50 inactive carriers (IC), 34 chronic hepatitis B (CHB), 27 cirrhosis, 26 hepatocellular carcinoma (HCC)], and 19 healthy controls. IL28A/B mRNA expression in peripheralblood mononuclear cells was determined by qRT-PCR, and serum IL28B proteinwas measured by ELISA. Results: Patients with IL28B C/C genotype had greater IL28A/B mRNA expression and higher IL28B protein levels than C/T patients. Within the various disease stages, compared to IC and healthy controls, IL28B expression was reduced in the CHB, cirrhosis, and HCC cohorts (CHB vs. IC, p=0.02; cirrhosis vs. IC, p=0.01; HCC vs. IC, p=0.001; CHB vs. controls, p<0.01; cirrhosis vs. controls, p<0.01; HCC vs. controls, p<0.01). When stratified with respect to serum HBV markers in the IC and CHB cohorts, IL28B mRNA and protein levels were higher in HBeAg-positive than negative individuals (p=0.01). Logistic regression analysis revealed that factors associated with high IL28B proteinlevels were C/C versus C/T genotype [p=0.016, odds ratio (OR)=0.25, 95% confidence interval (CI)=0.08‒0.78], high alanine aminotransferase values (p<0.001, OR=8.02, 95% CI=2.64‒24.4), and the IC stage of HBV infection (p<0.001). Conclusion: Our data suggest that IL28B genetic variations may play an important role in long-term development of disease in chronic HBV infections.

Mechanical behavior of the composite curved laminates in practical applications

Lonquan Liu,Junqi Zhang,Hai Wang,Zhongwei Guan 국제구조공학회 2015 Steel and Composite Structures, An International J Vol.19 No.5

In order to determine the mechanical behavior of the curved laminates in practical applications, three right-angled composite brackets with different lay-ups were investigated both experimentally and numerically. In the experimental, quasi-static tests on both unidirectional and multidirectional curved composite brackets were conducted to study the progressive failure and failure modes of the curved laminates. In the numerical modeling, three-dimensional finite element analysis was used to simulate the mechanical behavior of the laminates. Here, a strength-based failure criterion, namely the Ye criterion, was used to predict the delamination failure in the composite curved laminates. The mechanical responses of the laminate subjected to off-axis tensile loading were analyzed, which include the progressive failure, the failure locations, the load-displacement relationships, the load-strain relationships, and the stress distribution around the curved region of the angled bracket. Subsequently, the effects of stacking sequence and thickness on the load carrying capacity and the stiffness of the laminates were discussed in detail. Through the experimental observation and analysis, it was found that the failure mode of all the specimens is delamination, which is initiated abruptly and develops unstably on the symmetric plane, close to the inner surface, and about 29° along the circumferential direction. It was also found that the stacking sequence and the thickness have significant influences on both the load carrying capacity and the stiffness of the laminates. However, the thickness effect is less than that on the curved aluminum plate.

Impeller inlet geometry effect on performance improvement for centrifugal pumps

Xianwu Luo,Yao Zhang,Junqi Peng,Hongyuan Xu,Weiping Yu 대한기계학회 2008 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.22 No.10

This research treats the effect of impeller inlet geometry on performance improvement for a boiler feed pump, who is a centrifugal pump having specific speed of 183 m⋅m3min-1⋅min-1 and close type impeller with exit diameter of 450 mm. The hydraulic performance and cavitation performance of the pump have been tested experimentally. In order to improve the pump, five impellers have been considered by extending the blade leading edge or applying much larger blade angle at impeller inlet compared with the original impeller. The 3-D turbulent flow inside those pumps has been analyzed basing on RNG k-ε turbulence model and VOF cavitation model. It is noted that the numerical results are fairly good compared with the experiments. Based on the experimental test and numerical simulation, the following conclusions can be drawn: (1) Impeller inlet geometry has important influence on performance improvement in the case of centrifugal pump. Favorite effects on performance improvement have been achieved by both extending the blade leading edge and applying much larger blade angle at impeller inlet; (2) It is suspected that the extended leading edge have favorite effect for improving hydraulic performance, and the much larger blade angle at impeller inlet have favorite effect for improving cavitation performance for the test pump; (3) Uniform flow upstream of impeller inlet is helpful for improving cavitation performance of the pump.

Controllable Harmonic Generating Method for Harmonic Impedance Measurement of Traction Power Supply Systems Based on Phase Shifted PWM

Qiujiang Liu,Mingli Wu,Jing Li,Junqi Zhang 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.4

The harmonic impedance characteristic of a traction power supply system (TPSS) is necessary for taking actions to suppress the high-order harmonic resonances caused by AC electric locomotives. This paper proposes a controllable harmonic generating method (CHGM) for measuring the TPSS harmonic impedance by injecting harmonic disturbances of different frequencies and amplitudes into the TPSS. This method applies phase shifted pulse-width modulation (PSPWM) and ensures that the undesired sideband harmonics can be negligible while the desired harmonic is both controllable and adjustable. Multiple harmonics can be emitted at the same time. The implementation of the method is also presented. Simulations are carried out to validate the performance of the proposed method. Finally, experimental results on a 5 H-bridge converters platform verified the effectiveness and feasibility of the proposed method.

A Mean Field Game-Theoretic Cross-Layer Optimization for Multi-Hop Swarm UAV Communications

Tong Li,Cong Li,Chungang Yang,Junqi Shao,Yue Zhang,Lei Pang,Lizhong Chang,Lingli Yang,Zhu Han 한국통신학회 2022 Journal of communications and networks Vol.24 No.1

Unmanned aerial vehicle (UAV) multi-hop communicationnetworks are foreseen to be widely employed inboth military and civilian scenarios. However, in ultra-densescenarios with swarm UAVs, nodes are highly dynamic mobile,ultra-dense deployment and non-centralized distribution. Thesecharacteristics make the centralized resource management policynot apply. Meanwhile, existing routing protocols can’t meetthe performance challenges of high dynamic, topology and linkfrequency changes of ultra-dense scenarios with swarm UAVs. Tosolve the above challenges of resource management and routingprotocol, a cross-layer optimization method is presented witha novel mean field game (MFG) in this paper. It is based onthe cross-layer design method of the MFG theory and jointlyconsiders the power resources in the physical layer, frequencyresources in the medium access control (MAC) layer, and routingresources in the network layer. By dividing into subproblems,the original problem is solved. Meanwhile, the optimal datatransmission path can be selected through the management andallocation of frequency resources and power resources. A crosslayerresource management dynamic source routing (CLRMDSR)protocol is designed based on that which adds link qualitymeasurement. The simulation results show that the presentedCLRM-DSR with the proposed resource management schemecan improve the data packet transmission rate, reduce end-toenddelay, and lower routing overhead for the multi-hop swarmUAV communication network.

Controllable Harmonic Generating Method for Harmonic Impedance Measurement of Traction Power Supply Systems Based on Phase Shifted PWM

Liu, Qiujiang,Wu, Mingli,Li, Jing,Zhang, Junqi The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.4

The harmonic impedance characteristic of a traction power supply system (TPSS) is necessary for taking actions to suppress the high-order harmonic resonances caused by AC electric locomotives. This paper proposes a controllable harmonic generating method (CHGM) for measuring the TPSS harmonic impedance by injecting harmonic disturbances of different frequencies and amplitudes into the TPSS. This method applies phase shifted pulse-width modulation (PSPWM) and ensures that the undesired sideband harmonics can be negligible while the desired harmonic is both controllable and adjustable. Multiple harmonics can be emitted at the same time. The implementation of the method is also presented. Simulations are carried out to validate the performance of the proposed method. Finally, experimental results on a 5 H-bridge converters platform verified the effectiveness and feasibility of the proposed method.