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Increasing isobutanol yield by double-gene deletion of PDC6 and LPD1 in Saccharomyces cerevisiae

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Chinese Journal of Chemical Engineering 2016年第8期24卷 1074-1079页

作者： Aili Zhang Yang Li Yuhan gao Hongxing jin School of Chemical Engineering and Technology Hebei University of Technology

As a new biofuel, isobutanol has received more attentions in recent years. Because of its high tolerance to higher alcohols, Saccharomyces cerevisiae has potential advantages as a platform microbe to produce isobutanol. In this study, we investigated integration effects of enhancing valine biosynthesis by overexpression of ILV2 and BAT2 with eliminating ethanol formation by deletion of PDC6 and decreasing acetyl-Co A biosynthesis by deletion of LPD1 on isobutanol titers. Our results showed that deletion of LPD1 in strains overexpressing BAT2 and ILV2 increased isobutanol titer by 5.3-fold compared with control strain. Additional deletion of PDC6 in lpd1Δ strains carrying overexpressed BAT2 and ILV2 further increased isobutanol titer by 1.5 fold. Overexpression of BAT2 and ILV2 in lpd1Δ strains and pdc6Δ strains decreased ethanol titers. Glycerol titers of the engineered strains did not have greater changes than that of control strain, while their acetic acid titers were higher, perhaps due to the imbalance of cofactors in isobutanol synthesis. Our researches suggest that double-gene deletion of PDC6 and LPD1 in strains overexpressing BAT2 and ILV2 could increase isobutanol production dramatically than single-gene deletion of PDC6 or LPD1. This study reveals the integration effects of overexpression of ILV2/BAT2 and double-gene deletion of LPD1 and PDC6 on isobutanol production, and helps understanding future developments of engineered strains for producing isobutanol.

关键词： Saccharomyces cerevisiae Isobutanol Ethanol Pyruvate decarboxylase

Experimental Study of Operation Performance for Hydrocarbon Fuel Pump with Low Specific Speed

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Journal of Thermal Science 2017年第5期26卷 440-447页

作者： wu Xianyu YANG Jun jin Xuan College of Aerospace Science and Engineering National Univ. of Defense Technology ChangSha 410073 China

In this paper, a small flow rate hydrocarbon turbine pump was used to pressurize the fuel supply system of scramjet engine. Some experiments were carried out to investigate the characteristics of turbine pump driven by nitrogen or combustion gas under different operating conditions. A experimental database with regard to the curves of the rotational speed, mass flow rate and net head with regard to centrifugal pump were plotted. These curves were represented as functions of the pressure and temperature at turbine inlet/outlet and the throttle diameter at downstream of centrifugal pump. A sensitivity study has been carried out based on design of experiments. The experimental was employed to analyze net head of centrifugal and throttle characteristics. The research results can accumulate foundations for the close loop control system of turbine pump.

关键词： expansion cycle scram jet hydrocarbon fuel turbo-pump operation performance

Deep reinforcement learning based task offloading in blockchain enabled smart city

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High Technology Letters 2023年第3期29卷 295-304页

作者：金凯琦 wu Wenjun gao Yang YIN Yufen SI Pengbo Faculty of Information Technology Beijing University of TechnologyBeijing 100124P.R.China

With the expansion of cities and emerging complicated application,smart city has become an in-telligent management *** order to guarantee the information security and quality of service(QoS)of the Internet of Thing(IoT)devices in the smart city,a mobile edge computing(MEC)en-abled blockchain system is considered as the smart city scenario where the offloading process of com-puting tasks is a key aspect infecting the system performance in terms of service profit and *** task offloading process is formulated as a Markov decision process(MDP)and the optimal goal is the cumulative profit for the offloading nodes considering task profit and service latency cost,under the restriction of system timeout as well as processing ***,a policy gradient based task of-floading(PG-TO)algorithm is proposed to solve the optimization ***,the numerical re-sult shows that the proposed PG-TO has better performance than the comparison algorithm,and the system performance as well as QoS is analyzed *** testing result indicates that the pro-posed method has good generalization.

关键词： mobile edge computing(MEC) blockchain policy gradient task offloading

Compressive stress field in the crust deduced from shear-wave anisotropy: an example in capital area ofChina

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Chinese Science Bulletin 2008年第18期53卷 2840-2848页

作者： gao Yuan wu jing Institute of Earthquake Science China Earthquake Administration Beijing 100036 China Earthquake Administration of Jiangsu Province Nanjing 210014 China

The rocks in the crust are pervaded by stress-aligned fluid-saturated microcracks, and the complex fault tectonics and stress control the configuration of the microcracks, however shear-wave splitting could indicate this kind of characteristics. In this paper, Capital Area Seismograph Network (CASN), the widest scope and highest density of regional seismograph network presently in China, is adopted to deduce the principal compressive stress field distribution pattern from polarizations of fast shear- waves, based on shear-wave splitting analysis. The principal compressive stress in capital area of China is at NE85.7°± 41.0° in this study. Compared with the results of principal compressive stress field in North China obtained from other methods, the results in this study are reliable in the principal com- pressive stress field distribution in capital area. The results show that it is an effective way, although it is the first time to directly obtain crustal stress field from seismic anisotropy. It is effectively applied to the zones with dense seismograph stations.

关键词：地震带压缩力地震波地震学

Device design principles and bioelectronic applications for flexible organic electrochemical transistors

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International Journal of Extreme Manufacturing 2024年第1期6卷 126-153页

作者： Lin gao Mengge wu Xinge Yu Junsheng Yu State Key Laboratory of Electronic Thin Films and Integrated Devices School of Optoelectronic Science and EngineeringUniversity of Electronic Science and Technology of China(UESTC)Chengdu 610054People’s Republic of China Department of Biomedical Engineering City University of Hong KongHong Kong Special Administrative Region of ChinaPeople’s Republic of China

Organic electrochemical transistors(OECTs) exhibit significant potential for applications in healthcare and human-machine interfaces, due to their tunable synthesis, facile deposition, and excellent biocompatibility. Expanding OECTs to the fexible devices will significantly facilitate stable contact with the skin and enable more possible bioelectronic applications. In this work,we summarize the device physics of fexible OECTs, aiming to offer a foundational understanding and guidelines for material selection and device architecture. Particular attention is paid to the advanced manufacturing approaches, including photolithography and printing techniques, which establish a robust foundation for the commercialization and large-scale fabrication. And abundantly demonstrated examples ranging from biosensors, artificial synapses/neurons, to bioinspired nervous systems are summarized to highlight the considerable prospects of smart healthcare. In the end, the challenges and opportunities are proposed for fexible OECTs. The purpose of this review is not only to elaborate on the basic design principles of fexible OECTs, but also to act as a roadmap for further exploration of wearable OECTs in advanced bio-applications.

关键词： flexible organic electrochemical transistors wearable bioelectronics manufacturing approaches device physics neuromorphic applications

Wavelet Neural Network Based on NARMA-L2 Model for Prediction of Thermal Characteristics in a Feed System

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Chinese Journal of Mechanical Engineering 2011年第1期24卷 33-41页

作者： jin Chao wu Bo HU Youmin State Key Laboratory for Digital Manufacturing Equipment and Technology Huazhong University of Science and Teehnology Wuhan 430074 China School of Mechanical Science and Engineering Huazhong University of Science and Technology Wuhan 430074 China

Research of thermal characteristics has been a key issue in the development of high-speed feed system. Most of the work carried out thus far is based on the principle of directly mapping the thermal error against the temperature of critical machine elements irrespective of the operating conditions. But recent researches show that different sets of operating parameters generated significantly different error values even though the temperature of the machine elements generated was similar. As such, it is important to develop a generic thermal error model which is capable of evaluating the positioning error induced by different operating parameters. This paper ultimately aims at the development of a comprehensive prediction model that can predict the thermal characteristics under different operating conditions （feeding speed, load and preload of ballscrew） in a feed system. A novel wavelet neural network based on feedback linearization autoregressive moving averaging （NARMA-L2） model is introduced to predict the temperature rise of sensitive points and thermal positioning errors considering the different operating conditions as the model inputs. Particle swarm optimization（PSO） algorithm is brought in as the training method. According to ISO230-2 Positioning Accuracy Measurement and ISO230-3 Thermal Effect Evaluation standards, experiments under different operating conditions were carried out on a self-made quasi high-speed feed system experimental bench HUST-FS-001 by using Pt100 as temperature sensor, and the positioning errors were measured by Heidenhain linear grating scale. The experiment results show that the recommended method can be used to predict temperature rise of sensitive points and thermal positioning errors with good accuracy. The work described in this paper lays a solid foundation of thermal error prediction and compensation in a feed system based on varying operating conditions and machine tool characteristics.

关键词： wavelet neural network NARMA-L2 model particle swarm optimization thermal positioning error feed system

Identification of an Underactuated Unmanned Surface Vehicle

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西北工业大学学报 2012年第5期30卷 699-705页

作者： Zhao Jiang Yan Weisheng jin Xuelian gao Jian College of Marine Engineering Northwestern Polytechnical University Xi'an 710072 China

Hydrodynamic coefficients strongly affect the dynamic performance of underactuated unmanned surface vehicle (USV) . Towing tank test is the traditional approach to identify these coefficients,however, the obtained values are not completely reliable since experimental difficulties and errors are involved. In this paper,an extended Kalman filter (EKF) method and a least squares (LS) method are proposed,only using onboard sensor data for identification of a small underactuated USV. The vehicle prototype as well as the system integration is delineated. Performance of the identification is evaluated by comparing the estimated coefficients,and the feasibility and accuracy of the proposed approach is demonstrated by simulation.

关键词：工业大学教学管理教育事业教育发展

Solving quantified constraint satisfaction problems with value selection rules

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Frontiers of Computer Science 2020年第5期14卷 153-163页

作者： Jian gao jinyan Wang Kuixian wu Rong Chen College of Information Science and Technology Dalian Maritime UniversityDalian116026China Logistics Research Institute Dalian Maritime UniversityDalian116026China College of Computer Science and Information Engineering Guangxi Normal UniversityGuilin541004China

Solving a quantified constraint satisfaction problem(QCSP)is usually a hard task due to its computational *** algorithms play an important role in solving this problem,among which backtrack algorithms are *** a backtrack algorithm,an important step is assigning a variable by a chosen value when exploiting a branch,and thus a good value selection rule may speed up *** this paper,we propose two value selection rules for existentially and universally quantified variables,respectively,to avoid unnecessary *** rule for universally quantified variables is prior to trying failure values in previous branches,and the rule for existentially quantified variables selects the promising values *** rules are integrated into the state-of-the-art QCSP solver,i.e.,QCSP-Solve,which is an exact solver based on *** perform a number of experiments to evaluate improvements brought by our *** computational results,we can conclude that the new value selection rules speed up the solver by 5 times on average and 30 times at *** also show both rules perform well particularly on instances with existentially and universally quantified variables occurring alternatively.

关键词： quantified CSP backtracking value selection fail-first principle

NUMERICAL STUDIES ON LOCOMOTION PERFROMANCE OF FISH-LIKE TAIL FINS

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Journal of Hydrodynamics 2012年第4期24卷 488-495页

作者： LI gao-jin ZHU Luodin LU Xi-ytm Department of Modern Mechanics University of Science and Technology of China Hefei 230026 China Department of Mathematical Sciences Indiana University-Purdue University Indianapolis IndianapolisIN 46202 USA

Flapping plates of typical fishlike tail shapes are simulated to investigate their locomotion performance using the multi-block Lattice Boltzmann Method （LBM） and Immersed Boundary （IB） method. Numerical results show that fishlike forked configurations have better locomotion performance compared with unforked plates. Based on our results, the caudal fin in carangi- form mode has greater thrust, and the lunate tail fin in thtmniform mode has higher efficiency. These findings are qualitatively con- sistent with biological observations of fish swimming. Analysis of wake topology shows that the wake of the forked plate consists of a chain of alternating reverse horseshoe-like vortical structures. These structures induce a backward jet and generate a positive thrust. Moreover, this backward jet has a more favorable direction compared with that behind an unforked plate.

关键词： carangiform and thunniform modes forked-tail fin three-dimensional (3-D) flapping plate multi-block LatticeBoltzmann Method (LBM) Immersed Boundary (IB) method