进口铁矿石供需变动情况对铁矿石普氏指数的影响

2019年,国内钢厂的进口铁矿石(下称进口矿)供应因巴西淡水河谷的溃坝矿难事件而出现缺口,供需关系失衡导致国内港口的进口矿库存持续下降,进一步加剧市场恐慌情绪,供需关系不平衡导致进口矿普指价格再创近5年新高。预计,供需关系发生逆转前,铁矿石普指价格难以出现大幅单边回调。2019年,进口矿普指价格预计维持相对高位。

LOCAL CHAOS CHARACTERISTICS IN A SELF ASPIRATED REVERSED FLOW JET LOOP REACTOR

The local chaos characteristics of the time series pressure fluctuations of gas liquid two phase flow in a self aspirated reversed flow jet loop reactor are studied by the deterministic chaos analysis technique. It is found that the estimated local largest Lyapunov exponent is positive in all cases and the profile is similar to that of the local fractal dimension in this reactor. The positive largest Lyapunov exponent shows that the reactor is a nonlinear chaotic system. The obvious distribution indicates that the local nonlinear characteristic parameters such as the Lyapunov exponent and the fractal dimension could be applied to further study the flow characteristics such as the flow regine transitions and flow structures of the multi phase reactors.

LOCAL NONLINEAR CHARACTERISTICS OF GAS LIQUID SOLID THREE PHASE SELF ASPIRATED REVERSED FLOW JET LOOP REACTOR

Hursts rescaled range (R/S) analysis and Wolfs attractor reconstruction technique have been adopted to estimate the local fractal dimensions and the local largest Lyapunov exponents in terms of the time series pressure fluctuations obtained from a gas liquid solid three phase self aspirated reversed flow jet loop reactor,respectively.The results indicate that the local fractal dimensions and the local largest Lyapunov exponents in both the jet region and the tubular region inside the draft tube increase with the increase in the jet liquid flowrates and the solid loadings,the local fractal dimension profiles are similar to those of the largest Lyapunov exponent,the local largest lyapunov exponents are positive for all cases,and the flow behavior of such a reactor is chaotic.The local nonlinear characteristic parameters such as the local fractal dimension and the local largest Lyapunov exponent could be applied to further study the flow properties such as the flow regime transitions and flow structures of this three phase jet loop reactor.

进口铁矿石供需变动情况对铁矿石普氏指数的影响

2019年,国内钢厂的进口铁矿石(下称进口矿)供应因巴西淡水河谷的溃坝矿难事件而出现缺口,供需关系失衡导致国内港口的进口矿库存持续下降,进一步加剧市场恐慌情绪,供需关系不平衡导致进口矿普指价格再创近5年新高。预计,供需关系发生逆转前,铁矿石普指价格难以出现大幅单边回调。2019年,进口矿普指价格预计维持相对高位。

Nonlinear dynamics analysis of a new autonomous chaotic system

In this paper,a new nonlinear autonomous system introduced by Chlouverakis and Sprott is studied further,to present very rich and complex nonlinear dynamical behaviors. Some basic dynamical properties are studied either analytically or nu-merically,such as Poincaré map,Lyapunov exponents and Lyapunov dimension. Based on this flow,a new almost-Hamilton chaotic system with very high Lyapunov dimensions is constructed and investigated. Two new nonlinear autonomous systems can be changed into one another by adding or omitting some constant coefficients.

Absolute Exponential Stability of Generalized Dynamical Neural Networks

This paper investigates the absolute exponential stability of generalized neural networks with a general class of partially Lipschitz continuous and monotone increasing activation functions. The main obtained result is that if the interconnection matrix T of the neural system satisfies that - T is an H matrix with nonnegative diagonal elements, then the neural system is absolutely exponentially stable(AEST). The Hopfield network, Cellular neural network and Bidirectional associative memory network are special cases of the network model considered in this paper. So this work gives some improvements to the previous ones.

Chaotic Roll Motions of Ships in Regular Longitudinal Waves

Parametric resonance can lead to dangerously large rolling motions, endangering the ship, cargo and crew. The QR-faetorization method for calculating （LCEs） Lyapunov Characteristic Exponents was introduced; parametric resonance stability of ships in longitudinal waves was then analyzed using LCEs. Then the safe and unsafe regions of target ships were then identified. The results showed that this method can be used to analyze ship stability and to accurately identify safe and unsafe operating conditions for a ship in longitudinal waves.

Some nonlinear parameters of PP intervals of pulse main peaks

The PP intervals of pulse main peaks from healthy and unhealthy people(arrhythmia) have different nonlinear char-acteristics. In this paper,the extraction of PP intervals of pulse main peaks is achieved by picking up P peaks of pulse wave with wavelet transform. Furthermore,several nonlinear parameters(correlative dimensions,maximum Lyapunov exponents,com-plexity and approximate entropy) of the PP intervals of pulse main peaks extracted from normal and unhealthy pulse signals are calculated,with the results showing that these nonlinear parameters calculated from the main wave interval signals are helpful for analyzing human's health state and diagnosing heart diseases.

Distinguishing between parenchymal and anastomotic leakage at duct-to-mucosa pancreatic reconstruction in pancreaticoduodenectomy

AIM： To distinguish anastomotic from parenchymal leakage at duct-to-mucosa reconstruction of the pancreatic remnant. METHODS： We reviewed the charts of 68 pancreaticoduodenectomies performed between 5/2000 and 12/2005 with end-to-side duct-to-mucosa pancreatojejunostomy （PJ）. The results of pancreatography, as well as peripancreatic drain volumes, and amylase levels were analyzed. RESULTS： Of 68 pancreatojejunostomies, 48 had no leak by pancreatography and had low-drain amylase （normal）; eight had no pancreatographic leak but had elevated drain amylase （parenchymal leak）; and 12 had pancreatographic leak and elevated drain amylase （anastomotic leak）. Although drain volumes in the parenchymal leak group were significantly elevated at postoperative day （POD） 4, no difference was found at POD 7. Drain amylase level was not significantly different at POD 4. In contrast, at POD 7, the anastomotic-leak group had significantly elevated drain amylase level compared with normal and parenchymalleak groups （14158 ＋ 24083 IU/L vs 89 ＋ 139 IU/L and 1707 ＋ 1515 IU/L, respectively, P = 0.012）. CONCLUSION： For pancreatic remnant reconstruction after pancreaticoduodenectomy, a combination of pancreatogram and peripancreatic drain amylase levels can be used to distinguish between parenchymal and anastomotic leakage at pancreatic remnant reconstruction.

Short-Term Forecasting of Urban Water Consumption Based on the Largest Lyapunov Exponent

An approach for short-term forecasting of municipal water consumption was presented based on the largest Lyapunov exponent of chaos theory. The chaotic characteristics of time series of urban water consumption were examined by means of the largest Lyapunov exponent and correlation dimension. By using the largest Lyapunov exponent a short-term forecasting model for urban water consumption was developed, which was compared with the artificial neural network (ANN) approach in a case study. The result indicates that the model based on the largest Lyapunov exponent has higher prediction precision and forecasting stability than the ANN method, and its forecasting mean relative error is 9.6% within its maximum predictable time scale while it is 60.6% beyond the scale.

Effective-Field Theory for Kinetic Ising Model on Honeycomb Lattice

As an analytical method, the effective-field theory （EFT） is used to study the dynamical response of the kinetic Ising model in the presence of a sinusoidal oscillating field. The effective-field equations of motion of the average magnetization are given for the honeycomb lattice （Z = 3）. The Liapunov exponent A is calculated for discussing the stability of the magnetization and it is used to determine the phase boundary. In the field amplitude ho / ZJ-temperature T/ZJ plane, the phase boundary separating the dynamic ordered and the disordered phase has been drawn. In contrast to previous analytical results that predicted a tricritical point separating a dynamic phase boundary line of continuous and discontinuous transitions, we find that the transition is always continuous. There is inconsistency between our results and previous analytical results, because they do not introduce sufficiently strong fluctuations.

Five Nontrivial Solutions of p-Laplacian Problems Involving Critical Exponents and Singular Cylindrical Potential

In this paper, we establish the existence of at least five distinct solutions to a p-Laplacian problems involving critical exponents and singular cylindrical potential, by using the Nehari manifold, concentration-compactness principle and mountain pass theorem

Magnetic Properties of Transverse Ising Model under a Time Oscillating Longitudinal Field

A transverse Ising spin system, in the presence of time-dependent longitudinal field, is studied by the effective-field theory （EFT）. The effective-field equations of motion of the average magnetization are given for the simple cubic lattice （Z ---- 6） and the honeycomb lattice （Z = 3）. The Liapunov exponent A is calculated for discussing the stability of the magnetization and it is used to determine the phase boundary. The dynamic phase transition diagrams in ho/ZJ - F/ZJ plane and in ho/ZJ - T/ZJ plane have been drawn, and there is no dynamical tricritical point on the dynamic phase transition boundary. The effect of the thermal fluctuations upon the dynamic phase boundary has been discussed.

Stochastic Resonance as a Mathematical Model of an Electrogastrogram

An electrogastrogram （EGG） is a recording of the electrical activity in the stomach, as measured on the abdominal surface. In this study, the goal is to obtain a mathematical model of an EGG; to achieve this, the EGG of 14 subjects （seven males and seven females） will be obtained. Initially, the Wayland algorithm to the EGG to measure the degree of determinism is applied. However, it could not be determined whether the EGG could be generated by a chaotic process. In addition, the waveform of the electric potential in the interstitial cells of Cajal is similar to the graphs of the numerical solutions to the Van der Pol equation. Therefore, the Van der Pol equation to a periodic function was added, and random white noise was used to represent the intestinal motility and other biosignals. The EGG and numerical solutions were compared and evaluated on the basis of the translation error （Etrans） in the Wayland algorithm and the maximum Lyapunov exponent （2） in Rosenstein＇s algorithm. By projecting the data from an obtained stationary EGG from the subjects, along with the numerical solutions, onto the Etrans-λ plane, the affinity between them was qualitatively evaluated. The EGG was well described by stochastic resonance from the stochastic differential equations.

Exponential stabilization of distributed parameter switched systems under dwell time constraints

The exponential stabilization problem for finite dimensional switched systems is extended to the infinite dimensional distributed parameter systems in the Hilbert space. Based on the semigroup theory, by applying the multiple Lyapunov function method, the exponential stabilization conditions are derived. These conditions are given in the form of linear operator inequalities where the decision variables are operators in the Hilbert space; while the stabilization properties depend on the switching rule. Being applied to the two-dimensional heat switched propagation equations with the Dirichlet boundary conditions, these linear operator inequalities are transformed into standard linear matrix inequalities. Finally, two examples are given to illustrate the effectiveness of the proposed results.

Novel criteria for global exponential stability and periodic solutions of delayed Hopfield neural networks

The global exponentially stability and the existence of periodic solutions of a class of Hopfield neural networks with time delays are investigated. By constructing a novel Lyapunov function, new criteria are provided to guarantee the global exponentially stability of such systems. For the delayed Hopfield neural networks with time-varying external inputs, new criteria are also acquired for the existence and exponentially stability of periodic solutions. The results are generalizations and improvements of some recent achievements reported in the literature on networks with time delays.

Application of artificial neural networks to the prediction of tunnel boring machine penetration rate

Rate of penetration of a Tunnel Boring Machine(TBM) in a rock environment is generally a key parameter for the successful accomplishment of a tunneling project.This paper presents the results of a study into the application of an Artificial Neural Network(ANN) technique for modeling the penetration rate of tunnel boring machines.A database,including actual,measured TBM penetration rates,uniaxial compressive strengths of the rock,the distance between planes of weakness in the rock mass and rock quality designation was established.Data collected from three different TBM projects(the Queens Water Tunnel,USA,the Karaj-Tehran water transfer tunnel,Iran,and the Gilgel Gibe II hydroelectric project,Ethiopia).A five-layer ANN was found to be optimum,with an architecture of three neurons in the input layer,9,7 and 3 neurons in the first,second and third hidden layers,respectively,and one neuron in the output layer.The correlation coefficient determined for penetration rate predicted by the ANN was 0.94.

Quantile Trends in Temperature Extremes in China

A number of recent studies have examined trends in extreme temperature indices using a linear regression model based on ordinary least-squares. In this study, quantile regression was, for the first time, applied to examine the trends not only in the mean but also in all parts of the distribution of several extreme temperature indices in China for the period 1960–2008. For China as a whole, the slopes in almost all the quantiles of the distribution showed a notable increase in the numbers of warm days and warm nights, and a significant decrease in the number of cool nights. These changes became much faster as the quantile increased. However, although the number of cool days exhibited a significant decrease in the mean trend estimated by classical linear regression, there was no obvious trend in the upper and lower quantiles. This finding suggests that examining the trends in different parts of the distribution of the time-series is of great importance. The spatial distribution of the trend in the 90 th quantile indicated that there was a pronounced increase in the numbers of warm days and warm nights, and a decrease in the number of cool nights for most of China, but especially in the northern and western parts of China, while there was no significant change for the number of cool days at almost all the stations.

Reliability Evaluation Metrics for Open Source Software Selection

Recently, Open Source Software （OSS） is so widely used not only by companies for development but also by common users instead of commercial software. However, the number of OSS is vast, and its quality varies from low to high. So how people can evaluate OSS and ensta-e that it is reliable for use becomes necessary. This paper proposes a set of reliability evaluation metrics considering the states of OSS selected in the early stage. Understandability, Fault tolerance ＆ Recoverability and Community Matmrity as sub-attributes of reliability are defined, and then several evaluation criteria for each of them are identified. A process of reliability evaluation in our study is proposed. For application, we select four OSS projects and evaluate them with our metrics. As a result of compadrison with other evaluation model for OSS, our research presents an easy, effective and trustworthy way for selecting a reliable OSS.

Theoretical Perspective of Social Entrepreneurship： A Study of Determinants of Social Entrepreneurship in the Context of Saudi Arabia

The present paper discusses the different theories on entrepreneurship in general and social entrepreneurship in particular to investigate the different determinants of social entrepreneurship in the context of Saudi Arabia. The present research is a conceptual study. The data were collected to analyze the entrepreneurship theories in Saudi Arabia＇s context. The data related to entrepreneurship spirit, perception of society towards entrepreneurship, and other macroeconomic indicators are collected from different research journals, websites of different corporate houses, and government sources to analyze the social entrepreneurship theories, such as failure thesis, interdependence theories, welfare state theory, supply-side theory, entrepreneurship education, etc.. The theoretical hypothesis of interdependence theory, entrepreneurship spirit, and general education and the theoretical analysis of this paper in light of Saudi Arabia are in line with the theory. But the hypothesis generated out of failure thesis theory, welfare state theory, entrepreneurship education, and individualistic and collective society culture is not in line with these theories.