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＂NEW＂ resource recovery from wastewater using bioelectrochemical systems： Moving forward with functions

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Frontiers of Environmental Science & Engineering 2018年第4期12卷 3-15页

作者： Akshay Jain zhen he Department of Civil and Environmental Engineering Virginia Polytechnic Institute and State University Blacksburg VA 24061 USA

Bioelectrochemical systems （BES） have been extensively studied ｜br resource recovery from wastewater. By taking advantage of interactions between microorganisms and electrodes, BES can accomplish wastewater treatment while simultaneously recovering various resources including nutrients, energy and water （＂NEW＂）. Despite much progress in laboratory sit, dies, BES have not been advanced to practical applications. This paper aims to provide some subjective opinions and a concise discussion of several key challenges in BES-based resource recovery and help identil- the potential application niches that may guide further technological development. In addition to further increasing recovery efficiency, it is also important to have more lbcus on the applications of the recovered resources such as how to use the harvested electricity and gaseous energy and how to separate the recovered nutrients in an energy-efficient way. A changc in mindset fur energy performance of BES is necessary to understand overall energy production and consumption. Scaling up BES can go through laboratory scale, transitional scale, and then pilot scale. Using functions as driving forces lbr BES research and development will better guide the investment of efforts.

关键词： Bioelectrochemical systemsResource recoveryWastewater treatmentEnergy Nutrients

Non-Cooperative Differential Game Based Load Balancing Algorithm in Radio-Over-Fibre System

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China Communications 2014年第A02期11卷 79-85页

作者： he zhen WANG Jianping School of Computer and Communication Engineering University of Science and Technology Beijing (USTB) Beijing 100083 P. R. China

Load balancing plays a critical role in a cellular network. As one kind of cellular network, Radio-over-Fibre （RoF） system can provide ubiquitous high data-rate transmissions, which has attracted many attentions, but it also suffer load unbalancing problem. In order to improve the system performance, in this paper, we propose a novel loading balance scheme in RoF system based on differential game theory. The scheme formulates the load allocated to each RAP （Radio Access Point） as a Nasb Equilibrium, using non-cooperative differential game to obtain the optical load allocation of each RAP. The simulations performed show that the non-cooperative differential game algorithm is applicable and the optimal load solution can be achieved.

关键词： loading balancing RoF RAP non- cooperative differential game

Parametric Resonance Analyses for Spar Platform in Irregular Waves

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China Ocean Engineering 2018年第2期32卷 236-244页

作者： YANG he-zhen XU Pei-ji School of Engineering University of GlasgowGlasgow G128QQUnited Kingdom School of Naval Architecture Ocean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China

The parametric instability of a spar platform in irregular waves is analyzed. Parametric resonance is a phenomenon that may occur when a mechanical system parameter varies over time. When it occurs, a spar platform will have excessive pitch motion and may capsize. Therefore, avoiding parametric resonance is an important design requirement. The traditional methodology includes only a prediction of the Mathieu stability with harmonic excitation in regular waves. However, real sea conditions are irregular, and it has been observed that parametric resonance also occurs in non-harmonic excitations. Thus, it is imperative to predict the parametric resonance of a spar platform in irregular waves. A Hill equation is derived in this work, which can be used to analyze the parametric resonance under multi-frequency excitations. The derived Hill equation for predicting the instability of a spar can include non-harmonic excitation and random phases. The stability charts for multi-frequency excitation in irregular waves are given and compared with that for single frequency excitation in regular waves. Simulations of the pitch dynamic responses are carried out to check the stability. Three-dimensional stability charts with various damping coefficients for irregular waves are also investigated. The results show that the stability property in irregular waves has notable differences compared with that in case of regular waves. In addition, using the Hill equation to obtain the stability chart is an effective method to predict the parametric instability of spar platforms. Moreover, some suggestions for designing spar platforms to avoid parametric resonance are presented, such as increasing the damping coefficient, using an appropriate RAO and increasing the metacentric height.

关键词： spar platform instability parametric resonance Mathieu equation irregular waves dynamic responses

Evolutions of CHCN abundance in molecular clumps

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Research in Astronomy and Astrophysics 2021年第8期21卷 245-252页

作者： zhen-zhen he Guang-Xing Li Chao Zhang Department of Astronomy Yunnan UniversityKunming 650091China South-Western Institute For Astronomy Research Yunnan UniversityKunming 650091China

To investigate the effects of massive star evolution on surrounding molecules,we select nine massive clumps previously observed with the Atacama Pathfinder Experiment(APEX) telescope and the Submillimeter Array(SMA) *** on the observations of APEX,we obtain luminosity to mass ratios Lclump/Mclump that range from 10 to 154 L_(⊙)/M_(⊙),where some of them embedded ultra compact(UC) H Ⅱ *** the SMA,CH3CN(12K-11K) transitions were observed toward nine massive starforming *** derive the CH3CN rotational temperature and column density using the XCLASS program,and calculate its fractional *** find that CH3CN temperature seems to increase with the increase of Lclump/Mclump when the ratio is between 10 to 40 L_(⊙)/M_(⊙),then decrease when L_(clump)/M_(clump)≥ 40 L_(⊙)/M_(⊙).Assuming that the CH3CN gas is heated by radiation from the central star,the effective distance of CH3CN relative to the central star is *** distance ranges from - 0.003 to - 0.083 pc,which accounts for - 1/100 to - 1/1000 of clump *** effective distance increases slightly as Lclump/Mclump increases(Reff-(L_(clump)/M_(clump))0.5±0.2).Overall,the CH3 CN abundance is found to decrease as the clumps evolve,e.g.,XCH3CN -(L_(clump)/M_(clump))-1.0±*** steady decline of CH3CN abundance as the clumps evolution can be interpreted as a result of photodissociation.

关键词： line:identification stars:evolution stars:formation ISM:molecules submillimeter:ISM

Modified Multivariate Process Capability Index Using Principal Component Analysis

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Chinese Journal of Mechanical Engineering 2014年第2期27卷 249-259页

作者： ZHANG Min WANG G Alan he Shuguang he zhen Department of Industrial Engineering Tianjin University Department of Business Information Technology Department of Information Management and Management Science Tianjin University

The existing research of process capability indices of multiple quality characteristics mainly focuses on nonconforming of process output, the concept development of tmivariate process capability indices, quality loss function and various comprehensive evaluation methods. The multivariate complexity increases the computation difficulty of multivariate process capability indices（MPCI）, which makes them hard to be used in practice. In this paper, a new PCA-based MPCI approach is proposed to assess the production capability of the processes that involve multiple product quality characteristics. This approach first transforms the original quality variables into standardized normal variables. MPCI measures are then provided based on the Taam index. Moreover, the statistical properties of these MPCIs, such as confidence intervals and lower confidence bound, are given to let the practitioners understand the capability indices as random variables instead of deterministic variables. A real manufacturing data set and a synthetic data set are used to demonstrate the effectiveness of the proposed method. An implementation procedure is also provided for quality engineers to apply our MPCI approach in their manufacturing processes. The case studies demonstrate the effectiveness and feasibility of this new kind of MPCI, which is easier to be used in production practice. The proposed research provides a novel approach of MPCI calculation.

关键词： process capability index multivariate specification region principal component analysis confidence interval

Pole-to-ground Fault Analysis for HVDC Grid Based on Common-and Differential-mode Transformation

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Journal of Modern Power Systems and Clean Energy 2020年第3期8卷 521-530页

作者： zhen he Jiabing Hu Lei Lin Yuanzhu Chang Zhiyuan he State Key Laboratory of Advanced Electromagnetic Engineering and Technology and School of Electrical and Electronic EngineeringHuazhong University of Science and TechnologyWuhan 430074China Global Energy Interconnection Research Institute State GridBeijing 100192China

Pole-to-ground(PTG) fault analysis is of vital importance for high-voltage direct current(HVDC) grid. However, many factors are not considered in the existing studies such as the asymmetrical property of PTG fault, the coupling issue between DC transmission lines and the complexity of the structure of DC grid. This paper presents a PTG fault analysis method, which is based on common-and differential-mode(CDM)transformation. Similar to the symmetrical component method in AC system, the transformation decomposes the HVDC grid into CDM networks, which is balanced and decoupled. Then, a transfer impedance is defined and calculated based on the impedance matrices of the CDM networks. With the transfer impedance, analytical expressions of fault characteristics that vary with space and time are obtained. The proposed PTG fault analysis method is applicable to arbitrary HVDC grid topologies,and provides a new perspective to understand the fault mechanism. Moreover, the analytical expressions offer theoretical guidance for PTG fault protection. The validity of the proposed PTG fault analysis method is verified in comparison with the simulation results in PSCAD/EMTDC.

关键词： High-voltage direct current(HVDC)grid pole-to-ground(PTG)fault common-and differential-mode(CDM)transformation DC ciruit breaker(DCCB)

Synthesis Mechanism and Material Characterization of C4AF Obtained by the Self-propagating Combustion Reaction Method

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Journal of Wuhan University of Technology(Materials Science) 2018年第5期33卷 1099-1107页

作者： he zhen LI Yang Shaanxi Key Laboratory of Safety and Durability of Concrete Structure Xoing UniversityXi＇an 710123China State Key Laboratory of Water Resources ＆ Hydropower Engineering Science Wuhan UniversityWuhan 430072China

To investigate the influence of preparation process on the properties of synthesized C4AF,the powder was prepared via the self-propagating combustion reaction（SPCR）method using urea as fuel and metal nitrates as cation *** mechanism of the SPCR method,calculation and adjusting principles of urea dosage were detailedly *** characterization of synthesized C4AF was performed with the aid of X-ray diffractometry,Fourier transform infrared spectrometry,scanning electron microscopy,energydispersive X-ray spectroscopy,^27Al nuclear magnetic resonance and isothermal microcalorimetric *** content of transition phase of calcium carbonate in synthesized C4AF was determined by quantitative analysis of X-ray *** was found that there was no difference in the hydration behavior of C4AF synthesized by the SPCR method and the traditional solid-state reaction（SSR）method.C3AH6 and amorphous iron（III）hydroxide（Fe（OH）3）would be formed during the hydration of C4AF while CH *** size of synthesized C4AF was 16.1 A and the apparent activation energy was 36.2 kJ/*** condition of Al in C4AF can be detected by ^27Al NMR technique,but the peaks were broadened and the intensities were relatively low,supporting the use of ^27Al NMR for the quantitative analysis of C3A in Portland cements.

关键词： C4AF self-propagating SPCR urea ^27Al NMR apparent activation energy

Multiple model predictive control of perching maneuver based on guardian maps

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Chinese Journal of Aeronautics 2022年第5期35卷 347-360页

作者： Rui CAO Huiwen WAN zhen he Yuping LU College of Automated Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Considering the strong nonlinearity of Unmanned Aerial Vehicles(UAVs)resulting from high Angle of Attack(AOA)and fast maneuvering,we present a multi-model predictive control strategy for UAV maneuvering,which has a small amount of online ***,we divide the maneuver envelope of UAV into several sub-regions on the basis of the gap metric theory.A novel algorithm is then developed to determine the ploytopic model for each *** to this,a Robust Model Predictive Control based on the Idea of Comprehensive optimization(ICE-RMPC)is *** control law is designed offline and optimized online to reduce the computational ***,the ICE-RMPC method is applied to design the controllers of *** addition,to guarantee the stability of whole closed-loop system,a multi-model switching control strategy based on guardian maps is put ***,the tracking performance of proposed control strategy is demonstrated by an illustrative example.

关键词： Guardian maps Model predictive control Multi-Model switching rule Online comprehensive design Perching maneuver

On spectral characterizations of Willmore hypersurfaces in a sphere

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Applied Mathematics(A Journal of Chinese Universities) 2009年第4期24卷 490-494页

作者： LI zhen-he WANG Wei School of Mathematical Sciences Fudan University Shanghai 200433 China

Let M be a closed Willmore hypersurface in the sphere S^n＋1（1）（n ≥ 2） with the same mean curvature of the Willmore torus Wm,n-m, if SpecP（M） = Spec^P（Wm,n-m ）（p = 0, 1,2）, then M is Wm,n-m.

关键词： spectrum Willmore hypersurface mean curvature