Long-term inorganic plus organic fertilization increases yield and yield stability of winter wheat

An understanding of wheat yield and yield stability response to fertilization is important for sustainable wheat production. A 36-year long-term fertilization experiment was employed to evaluate the yield and yield stability of winter wheat. Five fertilization regimes were compared,including(1) CK, no fertilizer;(2) NPK, inorganic fertilizer only;(3) O, organic fertilizer only;(4)NPKO, 50% of NPK plus 50% of O, and(5) HNPKO, 80% of NPK plus 80% of O. The greatest yield increase was recorded in HNPKO, followed by NPKO, with O producing the lowest mean yield increase. Over the 36 years, the rate of wheat yield increase in fertilized plots ranged from95.31 kg ha-1 year-1 in the HNPKO to 138.65 kg ha-1 year-1 in the O. Yield stability analysis using the additive main effects and multiplicative interactions(AMMI) method assigned 62.3%, 26.3%,and 11.4% of sums of squares to fertilization effect, environmental effect, and fertilization ×environment interaction effect, respectively. The combination of inorganic and organic fertilization(NPKO and HNPKO) appeared to produce more stable yields than O or NPK, with lower coefficients of variation and AMMI stability value. However, wheat grown with O seemed to be the most susceptible to climate change and the least productive among the fertilized plots.Significant correlations of grain yield with soil properties and with mean air temperature were observed. These findings suggest that inorganic + organic fertilizer can increase wheat yield and its stability by improvement in soil fertility and reduction in variability to climate change.

Back analysis of long-term stability of a 92 m span ancient quarrying cavern

Long-term stability of large-span caverns is a challenging issue for design and construction of underground rock engineering.The Heidong cavern group consisting of 21 caverns was constructed about 1400 years ago for quarrying in massive Cretaceous tuff.The cavern No.5 of the Heidong cavern group is characterized by an unsupported span up to 92 m,with the overburden thickness of only 3-25 m.To analyze its long-term stability,a detailed investigation was conducted to obtain its geometry and rock mass characteristics,and to monitor surrounding rock displacements.Based on field survey and laboratory tests,numerical simulations were performed using the finite difference code FLAC;.The analysis results revealed that for the long-term stability of the cavern No.5,some major factors should be carefully considered,such as cavern excavation method in hard massive rocks,site investigation using trial pits,tools like short iron chisel and hammer for manual excavation,geometric dome roof,and waste rocks within abutment or on the floor.The highlights of the technologies obtained from this large-scale ancient underground project can provide reference for other similar project excavations in practice.

Could Long-Term Stability Last Forever?

The subject of the present paper is to prove that the recently introduced conjecture of boundedness puts a ban over the view of stability as asymptotic property. This result comes in sharp contrast with the prescription of the traditional thermodynamics and statistical physics which consider the existence of equilibrium as asymptotic property of all systems. The difference commences from the use of infinitesimal calculus as the basic implement for modelling by the latter while the primary premise of the conjecture of boundedness is sustaining the energy/matter/information permanently bounded and finite. The latter property overrules the infinitesimal calculus as the major implement of modelling because, among all, it is proven that the traditional one suffers unsoluble difficulties.

A two-dimensional air streamer discharge modified model based on artificial stability term under non-uniform electric field at low temperature and sub-atmospheric pressure

In this paper, an improved air discharge fluid model under non-uniform electric field is constructed based on the plasma module COMSOL Multiphysics with artificial stability term, and the boundary conditions developed in the previous paper are applied to the calculation of photoionization rate. Based on the modified model, the characteristics of low temperature subatmospheric air discharge under 13 kV direct current voltage are discussed, including needle-plate and needle-needle electrode structures. Firstly, in order to verify the reliability of the model, a numerical example and an experimental verification were carried out for the modified model respectively. Both verification results show that the model can ensure the accuracy and repeatability of the calculation. Secondly, according to the calculation results of the modified model, under the same voltage and spacing, the reduced electric field under low temperature subatmosphere pressure is larger than that under normal temperature and atmospheric pressure. The high electric field leads to the air discharge at low temperature and sub atmospheric pressure entering the streamer initiation stage earlier, and has a faster propagation speed in the streamer development stage, which shortens the overall discharge time. Finally, the discharge characteristics of the two electrode structures are compared, and it is found that the biggest difference between them is that there is a pre-ionization region near the cathode in the needle-needle electrode structure. When the pre-ionization level reaches 1013 cm-3, the propagation speed of the positive streamer remains unchanged throughout the discharge process, and is no longer affected by the negative streamer. The peak value of electric field decreases with the increase of pre-ionization level, and tends to be constant during streamer propagation. Based on the previous paper, this paper constructs the air discharge model under non-uniform electric field, complements with the previous paper, and forms a relatively complete set of air discharge simulation system under low temperature and sub atmospheric pressure, which provides a certain reference for future research.

Short Term Stability Using Phase Plane

One of the most important problems in the study of transient stability of power systems is the determination of perturbation’s maximum time of permanence without losing the synchronism of the generators that feed the network. The problem is generally solved by either the application of the equal-area criterion or through numerical integration methods. In the present work, the phase-plane is proposed as an alternative tool to solve the above-mentioned problem with greater efficiency.

Long-term stabilization of the optical fiber phase control using dual PID

We propose an approach of long-term stabilization of optical fiber phase by controlling a piezo-based phase modulator and a Peltier component attached to the fiber via a phase-locked loop( PLL) circuit w ith dual proportional-integral- derivative( PID) adjustment. With this approach,we can suppress the fast disturbance and slow drifting of optical fiber to satisfy the requirements of optical phase long-term locking. In theory,a mathematical model of an optical fiber phase control system is established. The disturbance term induced by environment influence is considered into the PLL model. The monotonous and continuous changing environment disturbance w ill cause a steady-state error in this theory model. The experimental results accords w ell w ith the theory. The steady-state performance,adjusting time,and overshoot can be improved by using the dual PID control. As a result,the long-term,highly stable and low noise fiber phase locking is realized experimentally.

STABILITY OF PERTURBED NEUTRAL DIFFERENTIAL EQUATIONS WITH POSITIVE AND NEGATIVE COEFFICIENTS

In this paper the perturbed neutral differential equation with positive and negative coefficientsddt[x(t)-C(t)x(t-r)]+P(t)x(t-τ)-Q(t)x(t-σ)=f(t,x(t)), t≥t 0is considered. Sufficient conditions for the zero solution of this equation to be uniformly stable as well as asymptotically stable are obtained.

Analysis of the SBP-SAT Stabilization for Finite Element Methods Part Ⅱ:Entropy Stability

In the hyperbolic research community,there exists the strong belief that a continuous Galerkin scheme is notoriously unstable and additional stabilization terms have to be added to guarantee stability.In the first part of the series[6],the application of simultaneous approximation terms for linear problems is investigated where the boundary conditions are imposed weakly.By applying this technique,the authors demonstrate that a pure continu-ous Galerkin scheme is indeed linearly stable if the boundary conditions are imposed in the correct way.In this work,we extend this investigation to the nonlinear case and focus on entropy conservation.By switching to entropy variables,we provide an estimation of the boundary operators also for nonlinear problems,that guarantee conservation.In numerical simulations,we verify our theoretical analysis.

Estimation of unloading relaxation depth of Baihetan Arch Dam foundation using long-short term memory network

The unloading relaxation caused by excavation for construction of high arch dams is an important factor influencing the foundation’s integrity and strength.To evaluate the degree of unloading relaxation,the long-short term memory(LSTM)network was used to estimate the depth of unloading relaxation zones on the left bank foundation of the Baihetan Arch Dam.Principal component analysis indicates that rock charac-teristics,the structural plane,the protection layer,lithology,and time are the main factors.The LSTM network results demonstrate the unloading relaxation characteristics of the left bank,and the relationships with the factors were also analyzed.The structural plane has the most significant influence on the distribution of unloading relaxation zones.Compared with massive basalt,the columnar jointed basalt experiences a more significant unloading relaxation phenomenon with a clear time effect,with the average unloading relaxation period being 50 d.The protection layer can effectively reduce the unloading relaxation depth by approximately 20%.

Effects of long-term organic fertilization on soil microbiologic characteristics,yield and sustainable production of winter wheat

We investigated the soil microbiologic characteristics, and the yield and sustainable production of winter wheat, by conducting a long-term fertilization experiment. A single application of N, P and K （NPK） fertilizer was taken as the control （CK） and three organic fertilization treatments were used： NPK fertilizer＋pig manure （T1）, NPK fertilizer＋straw return （T2）, NPK fertilizer＋pig manure＋straw return （T3）. The results showed that all three organic fertilization treatments （T1, T2 and T3） significantly increased both soil total N （STN） and soil organic carbon （SOC） from 2008 onwards. In 2016, the SOC content and soil C/N ratios for T1, T2 and T3 were significantly higher than those for CK. The three organic fertilization treatments increased soil microbial activity. In 2016, the activity of urease （sucrase） and the soil respiration rate （SRS） for T1, T2 and T3 were significantly higher than those under CK. The organic fertilization treatments also increased the content of soil microbial biomass carbon （SMBC） and microbial biomass nitrogen （SMBN）, the SMBC/SMBN ratio and the microbial quotient （qMB）. The yield for T1, T2 and T3 was significantly higher than that of CK, respectively. Over the nine years of the investigation, the average yield increased by 9.9, 13.2 and 17.4% for T1, T2 and T3, respectively, compared to the initial yield for each treatment, whereas the average yield of CK over the same period was reduced by 6.5%. T1, T2, and T3 lowered the coefficient of variation （CV） of wheat yield and increased the sustainable yield index （SYI）. Wheat grain yield was significantly positively correlated with each of the soil microbial properties （P〈0.01）. These results showed that the long-term application of combined organic and chemical fertilizers can stabilize crop yield and make it more sustainable by improving the properties of the soil.

A CONDITIONAL STABILITY FOR AN INVERSE PROBLEM ARISING IN GROUNDWATER POLLUTION

An inverse problem of determining magnitude of groundwater pollution in a hydrologic region is investigated. By applying integral identity methods, a conditional stability for the inverse problem here is constructed with aids of an optimal adjoint problem and a suitable topology.

Climate change and permafrost stability in the eastern Canada Cordillera:The results of 33 years of measurements

Over the last 33 years,a network of climate stations has been set up at high altitude mountain permafrost sites from Plateau Mountain near Claresholm,Alberta,north to Sheldon Lake on the North Canol Road in the Yukon.Taken together with the data from the US National Weather Service and the Canadian Atmospheric Environment Service,the results indicate a cooling of mean annual air temperature south of Calgary,no significant change in Calgary,a slight warming at Jasper,and a major warming at Summit Lake,west of Fort Nelson.In contrast,the south eastern and central Yukon show only a minor warming trend that lies well within the limits of a sixty-year record measured by the Canadian Atmospheric Environment Service.Along the Mackenzie valley and on the North Slope of Alaska,the mean annual air temperature is rising.Permafrost is aggrading on Plateau Mountain,degrading at Summit Lake,and appears to be stable in southern Yukon and southern Alaska.This is in contrast to the warming occurring on the Arctic coastal plain and along the Mackenzie valley.It therefore appears that changes in climate vary considera-bly from place to place,and even where warming may occur,it may not continue indefinitely.There has been a northward shift of the arctic front due to a weakening of air pressure in the Yukon and Alaska relative to the continental tropical(cT) and maritime polar(mT) air masses to the south.Any actual changes that may be occurring appear to undergo amplification along the Mackenzie valley and Arctic coastal plain and reduction by buffering in the interior Yukon and Alaskan mountains,a result of mi-cro-environmental factors.Continued,careful monitoring of the climate is required and needs to be expanded in the National Parks in the mountains in order to provide data on the changes that may be taking place.Such measurements can provide a sound basis for interpreting ecological and other climate-related data.The existing climate models are not working satisfactorily because we do not know enough about the causes and processes involved in climate change.Improved results can indicate where best to site structures such as pipelines so as to minimize maintenance costs.Models may also help explain why certain areas such as Beringia,which saw reduced climate change,acted as important refugia during the glaciations.

Stabilized seventh-order dissipative compact scheme using simultaneous approximation terms

To ensure time stability of a seventh-order dissipative compact finite difference scheme, fourth-order boundary closures are used near domain boundaries previously. However, this would reduce the global convergence rate to fifth-order only. In this paper, we elevate the boundary closures to sixth-order to achieve seventh-order global accuracy. To keep the improved scheme time stable, the simultaneous approximation terms (SATs) are used to impose boundary conditions weakly. Eigenvalue analysis shows that the improved scheme is time stable. Numerical experiments for linear advection equations and one-dimensional Euler equations are implemented to validate the new scheme.

Novel Stability Criteria for Sampled-Data Systems With Variable Sampling Periods

This paper is concerned with a novel Lyapunovlike functional approach to the stability of sampled-data systems with variable sampling periods. The Lyapunov-like functional has four striking characters compared to usual ones. First, it is time-dependent. Second, it may be discontinuous. Third, not every term of it is required to be positive definite. Fourth, the Lyapunov functional includes not only the state and the sampled state but also the integral of the state. By using a recently reported inequality to estimate the derivative of this Lyapunov functional, a sampled-interval-dependent stability criterion with reduced conservatism is obtained. The stability criterion is further extended to sampled-data systems with polytopic uncertainties. Finally, three examples are given to illustrate the reduced conservatism of the stability criteria.

Global Lipschitz Stability in an Inverse Problem for the Non-stationary Transport Equation

An inverse problem of determining the source term of the non-stationary transport equation was considered.The extra lateral boundary condition was chosen as the observation data.Based on a Carleman estimate on the non-stationary transport equation,a global Lipschitz stability for the inverse problem was proved.

Global Exponential Stability Analysis of a Class of Dynamical Neural Networks

The problem of the global exponential stability of a class of Hopfield neural networks is considered. Based on nonnegative matrix theory, a sufficient condition for the existence, uniqueness and global exponential stability of the equilibrium point is presented. And the upper bound for the degree of exponential stability is given. Moreover, a simulation is given to show the effectiveness of the result.

Nonlinear Differential Equation of Macroeconomic Dynamics for Long-Term Forecasting of Economic Development

In this article we derive a general differential equation that describes long-term economic growth in terms of cyclical and trend components. Equation is based on the model of non-linear accelerator of induced investment. A scheme is proposed for obtaining approximate solutions of nonlinear differential equation by splitting solution into the rapidly oscillating business cycles and slowly varying trend using Krylov-Bogoliubov-Mitropolsky averaging. Simplest modes of the economic system are described. Characteristics of the bifurcation point are found and bifurcation phenomenon is interpreted as loss of stability making the economic system available to structural change and accepting innovations. System being in a nonequilibrium state has a dynamics with self-sustained undamped oscillations. The model is verified with economic development of the US during the fifth Kondratieff cycle (1982-2010). Model adequately describes real process of economic growth in both quantitative and qualitative aspects. It is one of major results that the model gives a rough estimation of critical points of system stability loss and falling into a crisis recession. The model is used to forecast the macroeconomic dynamics of the US during the sixth Kondratieff cycle (2018-2050). For this forecast we use fixed production capital functional dependence on a long-term Kondratieff cycle and medium-term Juglar and Kuznets cycles. More accurate estimations of the time of crisis and recession are based on the model of accelerating log-periodic oscillations. The explosive growth of the prices of highly liquid commodities such as gold and oil is taken as real predictors of the global financial crisis. The second wave of crisis is expected to come in June 2011.

用于ECG电极的长期稳定性评估方法:以皮革电极为例

新型柔性电极采集心电(ECG)数据十分便利,但证实电极有效性时缺乏长期稳定性的评估数据,因此提出了一种多维度评价新型柔性电极长期稳定性的方法,包括外观形态、电极-皮肤接触阻抗、三种姿态下ECG采集质量三个方面;其中ECG采集质量的评估由改进的信噪比、设计的汉明距离(HD-RPS-2D)和其他四个常用指标进行量化。通过自制的新型猪皮革电极进行验证,结果表明:在144 h的佩戴过程中,猪皮革电极外观变化小,电极-皮肤接触阻抗在20~50 Hz范围内均低于标准电极,并且在所有测试频段内整体波动小;六个指标能够衡量ECG信号质量,采集ECG的指标值在三种姿态下均与标准电极高度相近,特别是坐姿、站姿状态下长期稳定。

Stability in Inverse Problem of Determining Two Parameters for the Moore-Gibson-Thompson Equation with Memory Terms

In this paper,the authors consider the inverse problem for the Moore-Gibson-Thompson equation with a memory term and variable diffusivity,which introduce a sort of delay in the dynamics,producing nonlocal effects in time.The H¨older stability of simultaneously determining the spatially varying viscosity coefficient and the source term is obtained by means of the key pointwise Carleman estimate for the Moore-Gibson-Thompson equation.For the sake of generality in mathematical tools,the analysis of this paper is discussed within the framework of Riemannian geometry.

基于广义瞬时能量函数法的大规模直驱风电场并入弱交流电网的短期电压稳定性分析

随着大规模直驱风电场并入弱交流电网,两者之间复杂的交互作用使得系统遭受扰动后的短期电压稳定问题愈发突出。如何在线准确分析扰动后直驱风电场并网系统的短期电压稳定性是一个关键性挑战。为此提出一种基于广义瞬时能量函数法的短期电压稳定性分析方法。首先,建立了锁相环dq坐标系下的直驱风电场并网系统的动态模型。然后,根据无功守恒原理构造出直驱风电场并网系统的广义瞬时能量函数。基于广义瞬时能量函数提出动态无功能量安全域(dynamic reactive power energy security regions,DRPESR)来在线评估系统的短期电压稳定性。利用构造出的分层能量结构来分析直驱风电场并网系统的短期电压失稳机理。最后,基于Matlab/Simulink的时域仿真结果,证明了广义瞬时能量函数的有效性和所提判据的准确性。