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Soil nitrogen balance assessment and its application for sustainable agriculture and environment

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Science China(Life Sciences) 2005年第z2期48卷 843-855页

作者： Rabindra Nath Roy Ram Vimal Misra land and Water Development division FAO Rome 00100Italy

Soil nitrogen balance assessment (SNBA) serves as an effective tool for estimating the magnitude of nitrogen loss/gain of the agro-eco systems and to appraise their sustainability. SNBA brings forth awareness of soil fertility problems, besides providing information relating to the resultant release of nitrogen into the environment consequent to agricultural practices. Quantitative information relating to nitrogen escape into the environment through such exercises can be gainfully utilized for identification of causative factors, enhancing fertilizer use efficiency and formulating programmes aimed at plugging N leakages. An overview of nitrogen balance approaches and methodologies is presented. A deeper understanding and insight into the agro-eco systems provided by the SNBA exercises can lay the basis for the formulation of effective agronomic interventions and policies aimed at promoting sustainable agriculture and a benign environment.

关键词： nitrogen balance soil fertility sustainable agriculture nutrient flows and macro meso and micro levels

Safety-Critical Optimal Control for Autonomous systems

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Journal of systems Science & Complexity 2021年第5期34卷 1723-1742页

作者： XIAO Wei CASSANDRAS G.Christos BELTA Calin division of systems Engineering and Center for Information and systems Engineering Boston UniversityBrooklineMA 02446USA

This paper presents an overview of the state of the art for safety-critical optimal control of autonomous *** control methods are well studied,but become computationally infeasible for real-time applications when there are multiple hard safety constraints *** guarantee such safety constraints,it has been shown that optimizing quadratic costs while stabilizing affine control systems to desired(sets of)states subject to state and control constraints can be reduced to a sequence of Quadratic Programs(QPs)by using Control Barrier Functions(CBFs)and Control Lyapunov Functions(CLFs).The CBF method is computationally efficient,and can easily guarantee the satisfaction of nonlinear constraints for nonlinear systems,but its wide applicability still faces several ***,safety is hard to guarantee for systems with high relative degree,and the above mentioned QPs can easily be infeasible if tight or time-varying control bounds are *** resulting solution is also sub-optimal due to its myopic solving ***,this method works conditioned on the system dynamics being accurately *** authors discuss recent solutions to these issues and then present a framework that combines Optimal Control with CBFs,hence termed OCBF,to obtain near-optimal solutions while guaranteeing safety constraints even in the presence of noisy *** application of the OCBF approach is included for autonomous vehicles in traffic networks.

关键词： Control barrier function optimal control safety

New self-calibration schemes for accelerometers in platform INS

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Journal of systems Engineering and Electronics 2015年第5期26卷 1032-1042页

作者： Hong Cai Anliang Li Yuan Cao College of Aerospace Science and Engineering National University of Defence Technology Science and Technology on Complex land systems Simulation Laboratory

To ensure success of precise navigation, it is necessary to carry out in-field calibration for the accelerometers in platform inertial navigation system(PINS) before a mission is *** continuous self-calibration methods are not fit for fast calibration of accelerometers because the platform misalignments have to be estimated precisely and the nonlinear coupling terms will affect accuracy. The multi-position methods with a "shape of motion" algorithm also have some existing disadvantages: High precision calibration results cannot be obtained when the accelerometer’s output data are used directly and it is difficult to optimize the calibration scheme. Focusing on this field, this paper proposes new fast self-calibration methods for the accelerometers of PINS. A data compression filter is employed to improve the accuracy of parameter estimation because it is impossible to obtain non-biased estimation for accelerometer parameters when using the "shape of motion" algorithm. Besides, continuous calibration schemes are designed and optimized by the genetic algorithm(GA) to improve the observability of parameters. Simulations prove that the proposed methods can estimate the accelerometer parameter more precisely than traditional continuous methods and multi-position methods, and they are more practical to deal with urgent situations than multi-position methods.

关键词： self-calibration accelerometers data compression genetic algorithm

Practical configured microtremor array measurements(MAMs)for the geological investigation of underground space

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Underground Space 2021年第3期6卷 240-251页

作者： Taeseo Ku Subramaniam Palanidoss Yunhuo Zhang Sung-Woo Moon Xiao Wei Ean Seong Huang Jeyatharan Kumarasamy Kok Hun Goh Department of Civil and Environmental Engineering National University of SingaporeSingapore Geotechnical and Tunnel division Land Transport AuthoritySingapore Department of Civil and Environmental Engineering Nazarbayev UniversityKazakhstan Geosystems Land Transport AuthoritySingapore Infrastructure Design and land Land Transport AuthoritySingapore

Underground space utilization is becoming increasingly essential for modern metropolitan cities such as *** a soil/rock interface using traditional borehole investigation methods is expensive and difficult,owing to the numerous physical constraints within a built-up *** are often far apart,resulting in many unforeseen ground conditions during subsequent *** methods are sometimes employed as possible alternatives for fast,economical,and efficient bedrock *** goal of this study is to investigate the practical details of applying microtremor array measurement(MAM)as a non-invasive surface wave survey for mapping soil/rock interfaces in *** configurations in field data acquisition are examined,and practical recommendations for array construction are *** addition,30 in situ MAM tests are carried out for two major geological formations in *** the results,a standard shear wave velocity(V_(s))of 500 m/s is found to be suitable for interpreting the soil/rock interface,for the Bukit Timah Granite and Jurong ***,the method does not predict well when soft Kallang formation deposits are *** limitations are also discussed in the later parts of this *** and practical recommendations are discussed,providing constructive guidance to the *** proposed Vs-based method and associated guidelines and limitations can be used to create a digital geological database and are especially useful for rock profiling in an urban environment.

关键词： Array configuration MAM Non-invasive site investigation Soil/rock interface Surface wave survey

Experimental Studies of Artificial Conscious systems

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Journal of Computer Science & Technology 1995年第4期10卷 344-353页

作者：蔡义发 division of Adaptive Neural systems Zhejiang University Hangzhou

Human consciousness is the most interesting and mysterious phenomenon inthe world. In this paper, the results of the computational study and simulationof the conscious behaviour, such as the learning of 1anguage and image pat-terns, traditional conditioning, association, imagination and dream, have beenpresented. Based on these results, an experimental conscious system - CON-SCITRON, has been developed. Further discussion on development of artificialconscious systems is also provided.

关键词： Artificial conscious systems neural networks neural modelling

An 8-bit 180-kS/s differential SAR ADC with a time-domain comparator and 7.97-ENOB

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Journal of Semiconductors 2010年第9期31卷 118-122页

作者：樊华魏琦 Kobenge Sekedi Bomeh 殷秀梅杨华中 division of Circuits and systems Department of Electronic EngineeringTsinghua University

This paper presents a differential successive approximation register analog-to-digital converter（SAR ADC） with a novel time-domain comparator design for wireless sensor *** prototype chip has been implemented in the UMC 0.18-μm 1P6M CMOS *** proposed ADC achieves a peak ENOB of 7.98 at an input frequency of 39.7 kHz and sampling rate of 180 *** the Nyquist input frequency,68.49-dB SFDR,7.97-ENOB is achieved.A simple quadrate layout is adopted to ease the routing complexity of the common-centroid symmetry *** ADC maintains a maximum differential nonlinearity of less than 0.08 LSB and integral nonlinearity less than 0.34 LSB by this type of layout.

关键词： successive approximation register time-domain comparator analog-to-digital converter

Direct numerical simulation of matrix diffusion across fracture/matrix interface

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Water Science and Engineering 2013年第4期6卷 365-379页

作者： Yong ZHANG Eric M.LABOLLE Donald M.REEVES Charles RUSSELL division of Hydrologic Sciences Desert Research Institute Department of land Airand Water ResourcesUniversity of California

Accurate descriptions of matrix diffusion across the fracture/matrix interface are critical to assessing contaminant migration in fractured media. The classical transfer probability method is only applicable for relatively large diffusion coefficients and small fracture spacings, due to an intrinsic assumption of an equilibrium concentration profile in the matrix blocks. Motivated and required by practical applications, we propose a direct numerical simulation （DNS） approach without any empirical assumptions. A three-step Lagrangian algorithm was developed and validated to directly track the particle dynamics across the fracture/matrix interface, where particle＇s diffusive displacement across the discontinuity is controlled by an analytical, one-side reflection probability. Numerical experiments show that the DNS approach is especially efficient for small diffusion coefficients and large fracture spacings, alleviating limitations of the classical modeling approach.

关键词： Key words: fracture matrix interface direct numerical simulation transfer probability Lagrangian algorithm

A single channel,6-bit 410-MS/s 3bits/stage asynchronous SAR ADC based on resistive DAC

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Journal of Semiconductors 2015年第5期36卷 151-157页

作者：韩雪魏琦杨华中汪蕙 division of Circuits and systems Department of Electronic EngineeringTsinghua University

This paper presents a single channel, low power 6-bit 410-MS/s asynchronous successive approximation register analog-to-digital converter （SAR ADC） for ultrawide bandwidth （UWB） communication, prototyped in a SMIC 65-nm process. Based on the 3 bits/stage structure, resistive DAC, and the modified asynchronous successive approximation register control logic, the proposed ADC attains a peak spurious-free dynamic range （SFDR） of 41.95 dB, and a signal-to-noise and distortion ratio （SNDR） of 28.52 dB for 370 MS/s. At the sampling rate of 410 MS/s, this design still performs well with a 40.71-dB SFDR and 30.02-dB SNDR. A four-input dynamic comparator is designed so as to decrease the power consumption. The measurement results indicate that this SAR ADC consumes 2.03 mW, corresponding to a figure of merit of 189.17 fJ/step at 410 MS/s.

关键词： analog to digital converter asynchronous logic successive approximation register binary-search algorithm dynamic comparator

An 11-bit ENOB,accuracy-programmable,and non-calibrating time-mode SAR ADC

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Journal of Semiconductors 2013年第1期34卷 118-128页

作者：樊华韩雪魏琦杨华中 division of Circuits and systems Department of Electronic EngineeringTsinghua University

A 10 or 12 bit programmable successive approximation register（SAR） ADC incorporating improved time-domain comparator for bridge stress monitoring systems is *** for improving the accuracy of time-domain comparator are *** application of these approaches is illustrated using results from an experimental 10 or 12 bit programmable SAR *** in a 0.18-m,6M1P CMOS process,the ADC,at 12 bit,100 kS/s,achieves a Nyquist signal-to-noise-plus-distortion ratio（SNDR） of 68 dB（11 ENOB）,a spurious free dynamic range（SFDR） of 77.48 dB,while dissipating 558 W from a 1.8-V *** differential nonlinearity（DNL） and integral nonlinearity（INL） are 0.2/-0.74 LSB and C1.27/-0.97 LSB,respectively.

关键词： analog-to-digital converter(ADC) non-calibrating successive approximation register(SAR)