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Forecasting the effects of EU policy measures on the nitrate pollution of groundwater and surface waters

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Journal of Environmental Sciences 2010年第6期22卷 872-877页

作者： Ralf Kunkel Peter Kreins Bjrn Tetzlaff Frank Wendland research centre Jülich Institute of Chemistry and Dynamics of the Geosphere Institute of Rural Studies Federal Agricultural Research Centre

We used the interdisciplinary model network REGFLUD to predict the actual mean nitrate concentration in percolation water at the scale of the Weser river basin （Germany） using an area differentiated （100 m × 100 m） approach. REGFLUD combines the agro-economic model RAUMIS for estimating nitrogen surpluses and the hydrological models GROWA/DENUZ for assessing the nitrate leaching from the soil. For areas showing predicted nitrate concentrations in percolation water above the European Union （EU） groundwater quality standard of 50 mg NO3-N/L, effective agri-environmental reduction measures need to be derived and implemented to improve groundwater and surface water quality by 2015. The effects of already implemented agricultural policy are quantified by a baseline scenario projecting the N-surpluses from agricultural sector to 2015. The REGFLUD model is used to estimate the effects of this scenario concerning groundwater and surface water pollution by nitrate. From the results of the model analysis the needs for additional measures can be derived in terms of required additional N-surplus reduction and in terms of regional prioritization of measures. research work will therefore directly support the implementation of the Water Framework Directive of the European Union in the Weser basin.

关键词： catchment management diffuse source pollution mitigation methods river basin management Water Framework Directive

Gamma oscillations and their role in orchestrating balance and communication following stroke

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Neural Regeneration research 2025年第2期20卷 477-478页

作者： Montana Samantzis Cong Wang Matilde Balbi Queensland Brain Institute The University of QueenslandBrisbaneQLDAustralia Engineering research centre of Traditional Chinese Medicine Intelligent Rehabilitation Ministry of EducationShanghaiChina

Induced brain oscillations in the gamma range have recently garnered attention due to their reported neuroprotective effects in the treatment of Alzheimer’s *** method differs from pharmacological approaches by tapping into the neuronal population dynamics that underlie the homeostatic processes in the brain that are crucial for the recovery of ***,induced gamma-range oscillations have been used to improve cerebral blood flow,motor function,and synaptic plasticity in a mouse model of focal stroke,highlighting the broad potential of recruiting intrinsic recovery processes for the treatment of neurological *** open questions,such as the frequency specificity of the benefits,will shed light on the intrinsic processes involved and allow clinicians to optimize recovery after stroke.

关键词： protective specificity Alzheimer

Analysis of the periodic solutions of a smooth and discontinuous oscillator

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Acta Mechanica Sinica 2013年第4期29卷 575-582页

作者： Zhi-Xin Li Qing-Jie Cao Marian Wiercigroch Alain Léger centre for Nonlinear dynamics research Harbin Institute of Technology School of Astronautics centre for applied dynamics research School of Engineering University of Aberdeen King's College Laboratoire de Mécanique et d' Acoustique CNRS 31 Chemin Joseph Aiguier 13402 Marseille Cedex 20 France

In this paper, the periodic solutions of the smooth and discontinuous （SD） oscillator, which is a strongly irra- tional nonlinear system are discussed for the system having a viscous damping and an external harmonic excitation. A four dimensional averaging method is employed by using the complete Jacobian elliptic integrals directly to obtain the perturbed primary responses which bifurcate from both the hyperbolic saddle and the non-hyperbolic centres of the un- perturbed system. The stability of these periodic solutions is analysed by examining the four dimensional averaged equa- tion using Lyapunov method. The results presented herein this paper are valid for both smooth （e 〉 0） and discontin- uous （ce = 0） stages providing the answer to the question why the averaging theorem spectacularly fails for the case of medium strength of external forcing in the Duffing system analysed by Holmes. Numerical calculations show a good agreement with the theoretical predictions and an excellent efficiency of the analysis for this particular system, which also suggests the analysis is applicable to strongly nonlinear systems.

关键词： SD oscillator ~ Averaging method. Periodic so-lution ~ Irrational nonlinearity ~ Elliptic integral

A Rotating Pendulum Linked by an Oblique Spring

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Chinese Physics Letters 2011年第6期28卷 63-66页

作者： CAO Qing-Jie HAN Ning TIAN Rui-Lan centre for Nonlinear dynamics research School of AstronauticsHarbin Institute of TechnologyHarbin 150001 centre for Nonlinear dynamics research Department of Mathatics and PhysicsShijiazhuang Tiedao UniversityShijiazhuang 050043

We present a novel model which comprises a rotating pendulum linked by an oblique spring pinned to its rigid *** model provides a cylindrical dynamical system with both smooth and discontinuous regimes depending on the value of a system parameter and also the dynamics transient relying on the coupling strength between the pendulum and the linked *** presented system behaves with both standard(smooth)and nonstandard(discontinuous)nonlinear dynamics of equilibrium bifurcations and the periodic patterns when it is *** resonant structures of period,quasi-period and stochastic phenomena are presented for the system with unique harmonic *** chaotic behavior of the system perturbed by both viscous-damping and external excitations is also demonstrated.

关键词： system perturbed discontinuous

Bifurcations and the penetrating rate analysis of a model for percussive drilling

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Acta Mechanica Sinica 2010年第3期26卷 467-475页

作者： Qing-Jie Cao Marian Wiercigroch Ekaterina Pavlovskaia Shao-Pu Yang centre for Nonlinear dynamics research Shijiazhuang Railway Institute Shijiazhuang 050043 China School of Astronautics Haerbin Institute of Technology Haerbin 150001 China Department of Engineering Centre for Applied Dynamics Research King's College University of Aberdeen Aberdeen AB24 3UE Scotland UK

In this paper, we investigate a low dimensional model of percussive drilling with vibro-impact to mimic the nonlinear dynamics of the bounded progression. Non- holonomity which arises in the stick-slip caused by the impact during drilling fails to be correctly identified via the classical techniques. A reduced model without non-holono- mity is derived by the introduction of a new state variable, of which averaging technique is employed successfully to detect the periodic motions. Local bifurcations are presented directly by using C-L method. Numerical simulations and the penetrating rate analysis along different choices of parame- ters have been carried out to probe the nonlinear behaviour and the optimal penetrating rate of the drilling system.

关键词： Bifurcation Chaos Non-holonomity Percussive drilling

Nonlinear Young’s Modulus of New Red Sandstone:Experimental Studies

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Acta Mechanica Solida Sinica 2021年第6期34卷 989-999页

作者： Evgenii Riabokon Vladimir Poplygin Mikhail Turbakov Evgenii Kozhevnikov Dmitrii Kobiakov Mikhail Guzev Marian Wiercigroch centre for applied dynamics research School of EngineeringUniversity of AberdeenAberdeenUK Department of Oil and Gas Technologies Perm National Research Polytechnic UniversityPermRussia Institute of applied Mathematics Far Eastern Branch of the Russian Academy of SciencesVladivostokRussia

Young’s modulus of New Red Sandstone was investigated experimentally to gain insight into its nonlinear nature.A large experimental programme was carried out by applying a controllable quasi-static and dynamic uniaxial loading to 286 dry sandstone samples of four different *** static and dynamic tests,similar to those aiming at determining the uniaxial compressive strength,were conducted using the state-of-the-art experimental facilities at the University of Aberdeen including a custom-built small experimental rig for inducing a dynamic uniaxial compressive load via a piezoelectric *** obtained results have confirmed a complex nature of Young’s modulus of ***,under a harmonic dynamic loading,it shows strongly nonlinear behaviour,which is hardening and softening with respect to frequency and amplitude of the dynamic loading,respectively.

关键词： Sandstone Young’s modulus Static and dynamic loading Experiments Stress and strain Nonlinearity

Synthesis and Characterization of ZnO Nanowires and ZnO–CuO Nanoflakes from Sputter-Deposited Brass(Cu_(0.65)–Zn_(0.35)) Film and Their Application in Gas Sensing

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Journal of Materials Science & Technology 2015年第11期31卷 1069-1078页

作者： Bhagaban Behera Sudhir Chandra centre for applied research in Electronics Indian Institute of Technology Delhi

A novel method was presented for synthesis of ZnO and ZnO-CuO composites in the form of nanowires, nanorods and nanoflakes on oxidized silicon substrates. Further, the use of the synthesized nanostructures for gas sensing was demonstrated. Pure brass （Cu0.65-Zn0.35） films were deposited on oxidized Si substrate by radio frequency （RF） diode sputtering. Subsequently, these films having thickness in the range of 100-200 nm were oxidized in different oxidizing ambient in the temperature range of 300-550 ℃. The effect of temperature, time and oxidizing ambient on the growth of nanostructures was investigated by scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, X-ray diffraction （XRD） and photoluminescence （PL） techniques. The nanostructures surface was analyzed by X-ray photoelectron spectroscopy （XPS）. The synthesized nanowires had diameter in the range of 60-100 nm and length up to 50 μm. Based on these observations, the growth mechanism has been suggested. For the nanorods, the diameter was observed to be -150 nm. Samples having dense nanowires, nanorods and nanoflakes were used as a gas sensing material. The performance Of the sensor was investigated for different nanostructured materials for various volatile organic compounds （VOCs）, It was observed that ZnO- CuO nanoflakes were more sensitive to VOC sensing compared to ZnO nanowires and nanorods.

关键词： Brass Thermal oxidation Nanostructures ZnO CuO sensor Sensor Volatile organic compounds (VOCs)

Effect of TiO_2 Functionalization on Nano-Porous Silicon for Selective Alcohol Sensing at Room Temperature

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Journal of Materials Science & Technology 2017年第6期33卷 516-522页

作者： Priyanka Dwivedi Saakshi Dhanekar Samaresh Das Sudhir Chandra centre for applied research in Electronics Indian Institute of Technology(IIT)

Room temperature operated sensor for detection of alcohol vapours in low ppm range based on TiO_2 functionalized nano-porous silicon（PSi） is demonstrated. The effect of functionalization by TiO_2 on PSi is investigated using SEM, EDX, Raman spectroscopy, XRD and contact angle measurements. Sensing is accomplished by measuring change in resistance of the sensing layer using Cr-Au inter-digitatedelectrode（IDE） structure formed on top of the functionalized PSi layer. The sensors were tested for volatile organic compounds（VOCs） and water vapours in the wide range of 5–500 ppm concentration at room temperature. Functionalization of the nanostructured PSi by sputter deposited TiO_2 results in significant enhancement of sensitivity and inverse change in selectivity. PSi sensors have displayed strong response to water vapours whereas after functionalization, selective sensing to ethanol is depicted. Minimum detection by PSi sensors is portrayed at 100 ppm and that of functionalized sensors is at 10 ppm. Sensing mechanism is explained on the basis of surfaces and structures of both PSi and TiO_2. This study incites the importance of surface treatment of PSi for tuning the sensing properties and is useful in the development of selective alcohol sensors.

关键词： Functionalization Porous silicon Selectivity Sensor Titanium dioxide(TiO2)

Shilnikov sense chaos in a simple three-dimensional system

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Chinese Physics B 2010年第3期19卷 207-216页

作者：王炜张琪昌田瑞兰 Department of Mechanics School of Mechanical EngineeringTianjin University centre for Nonlinear dynamics research Shijiazhuang Railway Institute

The Shilnikov sense Smale horseshoe chaos in a simple 3D nonlinear system is studied. The proportional integral derivative （PID） controller is improved by introducing the quadratic and cubic nonlinearities into the governing equa- tions. For the discussion of chaos, the bifurcate parameter value is selected in a reasonable regime at the requirement of the Shilnikov theorem. The analytic expression of the Shilnikov type homoclinic orbit is accomplished. It depends on the series form of the manifolds surrounding the saddle-focus equilibrium. Then the methodology is extended to research the dynamical behaviours of the simplified solar-wind-driven-magnetosphere-ionosphere system. As is illustrated, the Lyapunov characteristic exponent spectra of the two systems indicate the existence of chaotic attractor under some specific parameter conditions.

关键词： chaos Shilnikov theorem homoclinic orbit manifold