NOVEL METHOD FOR DYNAMIC OPTIMIZATION OF STABILITY IN HIGH-SPEED MILLING SYSTEM

Considering the self-excited and forced vibrations in high-speed milling processes, a novel method for dynamic optimization of system stability is used to determine the cutting parameters and structural parameters by increasing the chatter free material removal rate （CF-MRR） and surface finish. The method is hased on the theory of the chatter stability and the semi-bandwidth of the resonant region. The objective function of the method is material removal rate（MRR）,the constraints are chatter stability and surface finish, and the optimizing variables are cutting and structural parameters. The optimization procedure is stated. The method is applied to a milling system and CF-MRR is increased 18.86%. It is shown that the influences of the chatter stability and the resonance are simultaneously considered in the dynamic optimization of the milling system for increasing CF-MRR and the surface finish.

Reform Dividends and Economic Convenience

Reform dividends refer to the improvements in certain economic actors under the new, reformed institutional system as compared against the original system. Reform leads to greater economic growth potential by changing the institutional environment, which in turn increases the vibrancy and innovation of economic actors. The most economically convenient system is also in actuality the most effective market economic system. Reform based on public and collective actions should be based on the following principle： if institutional reform is evolving towards the enhancement of economic convenience, then we can be sure that reform is embarking on the path of releasing dividends.

Effects of BYHW Decoction and Its Effective Constituents on the Fluidity of the Cell Membrane in a Stroke-Modeled Rat Brain

With in vitro spin labeling electron spin resonance (ESR) spectroscopy, we have studied the effects of Bu Yang Huan Wu (BYHW) decoction and its effective constituents such as astragaloside IV ferulic acid, chuanxiongzine, rutin, chlorogenic acid, 9,10 dimethoxy pterocarpane 7 O β D glucoside, calycosin, formononetin, calycosin 7 O glucoside, paeoniflorin, paeonal and quercein on the cell membrane fluidity of a rat brain which was modeled after the dual cervical arteries were intercepted and released for realizing an ischemia reperfusion injury which was selected as a brain stroke model. Our results indicated that the cell membrane fluidity in the model group decreased approximately 8% compared with the control group, and after brain cells were incubatied with species, the membrane fluidity could be recovered closely to the control level depending on the BYHW decoction and its different constituents. As the membrane fluidity is a very sensitive biological index which reflectsd the cell status, our method will be useful to study the molecular mechanism of tradition Chinese medicine (TCM) and its combination recipe.

Stabilities Analysis of Electromechanical Nonlinear Vibration of Electric Machine

An electromechanical nonlinear model of rotor system of electric machine is built.Respondance curves in parameter excited nonlinear vibration of this system caused by electromagnetic forces are investigated.Further more,the analysis reveals the effects of various electromagnetic and mechanical parameters on resonances, and some valuable results are obtained.The analytical result of this paper provides electric machine with the condition of 1/2 subharmonic resonance under the electromechanical electromagnetic forces.Electromagnetic forces apparently affect the stability zone, and both linear term and nonlinear term can excite parametric resonance.The revealed dynamic phenomena provide some new theories and active methods for the fault recognition of electric machine and the defination of stability range,and the theoretical bases for qualitatively controlling the stable operating state of rotors.

Microscopic damage and dynamic mechanical properties of rock under freeze-thaw environment

For understanding the rock microscopic damage and dynamic mechanical properties subjected to recurrent freeze-thaw cycles, experiments for five groups of homogeneous sandstone under different freeze-thaw cycles were conducted. After freezethaw, nuclear magnetic resonance(NMR) tests and impact loading tests were carried out, from which microscopic damage characteristics of sandstone and dynamic mechanical parameters were obtained. The results indicate that the porosity increases with the increase of cycle number, the rate of porosity growth descends at the beginning of freeze-thaw, yet accelerates after a certain number of cycles. The proportion of pores with different sizes changes dynamically and the multi-scale distribution of pores tends to develop on pore structure with the continuing impact of freeze-thaw and thawing. Dynamic compressive stress-strain curve of sandstone undergoing freeze-thaw can be divided into four phases, and the phase of compaction is inconspicuous compared with the static curve. Elastic modulus and dynamic peak intensity of sandstone gradually decrease with freeze-thaw cycles, while peak strain increases. The higher the porosity is, the more serious the degradation of dynamic intensity is. The porosity is of a polynomial relationship with the dynamic peak intensity.

COMPARISON BETWEEN TWO ANALYTICAL MODELS OF HELICOPTER GROUND RESONANCE

The 2-dimensional equivalent model used in helicopter ground resonance analysis is convenient for its simplicity and clarity. The equivalent body mass, the stiffness and the damping are derived from the modal charaCteristics. In this paper, a 3-dimensional space model is constructed to analyse the ground resonance.There is little difference between the calculated results of the 2-dimensional equivalent model and those of the 3-dimensional space model. Hence, the 2-dimensional model is verified for the practical application. Generally, the linear lead-lag damping of the equivalent rotor blade at the modal frequency is derived from the lead-lag damper characteristics by a procedure of iteration. The transformation of the imaginary part of the complex modulus of the viscoelastic damper into a linear velocity damping is complicated in analysis. A method to use the complex modulus directly in the ground resonance analysis is derived and verified.

Effects of microwave radiation on dynamic compressive properties of basalt

The dynamic mechanical properties of basalt affected by microwave were investigated by performing dynamic compressive tests using the SHPB system.Meanwhile,the thermal damage of the treated basalt was characterized by ultrasonic non-destructive testing and nuclear magnetic resonance technology.The results show that with the increase of microwave power and exposure time,the P-wave velocity,dynamic compressive strength and elastic modulus decrease continuously,and the dynamic failure mode tends to be a more complex fracturing.The increase in microwave power and exposure time can enhance the temperature difference and transfer coefficient among minerals,hence intensifying the rock damage induced by thermal shock.

Comment on Revision of Kaup-Newell's Works on IST for DNLS Equation

In this note, it is shown that the revision of the Kaup-Newell＇s works on 1ST for DNLS equation is only available in the ease of solving the bright one-soliton solution to the equation. An example is taken to illustrate our point of view.

Coexistence Studies on the Interference Performance Between Mobile Satellite System and LTE Network

The interference coexistence performance between the systems of a Long Term Evolution(LTE) network and Mobile Satellite Service(MSS) system,both of which work around the frequency of approximately 2 GHz according to the bandwidth allocation in China,is proposed in this article.The related background of an MSS system and the common terminologies are introduced.Further,the coexistence scenarios of different coverage situations shared by the two systems are discussed.The interference impact of an MSS transmission on an LTE system is evaluated using a specific Monte Carlo method.Finally,simulation results show that although no crucial issues for the coexistence of an LTE downlink and the MSS are observed,the LTE uplink suffers a considerable amount of interference from the MSS transmission.Given the insufficient isolation between LTE and MSS existing networks,and the rapid advance in the field of LTE,problems may emerge in the near future.Further,this article can be of significance in providing reference for frequency spectrum planning in the existing LTE networks.

MAGNETIC RESONANCE IMAGING OF ACUTE CENTRAL CORD SYNDROME: CORRELATION WITH PROGNOSIS

Objective. To report the magnetic resonance imaging (MRI) findings of acute cervical central cord syndrome and to determine their correlation with the prognosis. Methods. MRI findings of 35 patients with acute central cord syndrome were studied and compared with the recovery rate of ASIA score at presentation and in follow- up. Results. MRI data demonstrated spinal cord compression for 32 patients, spinal cord swelling for 16 patients, and abnormal signal intensity within the spinal cord for 19 patients, including 14 with edema and 3 with hematoma. No significant difference of the recovery rate was noted between the patients treated nonoperatively and operatively (P >0.05). There was a significant inverse correlation between the recovery rate and the degree of spinal cord compression as shown in MRI scans (P< 0.01). The presence of hematoma in MRI scans was associated with poor prognosis, as demonstrated by a significant difference of the recovery rate (P< 0.01) among the patients with normal intensity, edema and hematoma within the spinal cord. Conclusions. MRI scans provide an efficient assistance for decision- making and accurate prognostic information regarding neurological function, and therefore should routinely be performed within the early phase of acute central cord syndrome.

Mapping analysis of vibrating fundamental frequency for simple-supported elastic rectangle-plates with concentrated mass

By conformal mapping theory, a trigonometric interpolation method between odd and even sequences in rectangle boundary region was provided, and the conformal mapping function of rectangle-plate with arc radius between complicated region and unite dish region was carried out. Aiming at calculating the vibrating fundamental frequency of special-shaped, elastic simple-supported rectangle-plates, in the in-plane state of constant stress, the vibration function of this complicated plate was depicted by unit dish region. The coefficient of ftmdamental frequency was calculated. Whilst, taking simple-supported elastic rectangle-plates with arc radius as an example, the effects on fundamental frequency caused by the concentrated mass and position, the ratio of the length to width of rectangle, as well as the coefficient of constant in-plane stress were analyzed respectively.

中国经济周期波动的经验分析

本文采用最新的随机游走滤波分析方法对中国1952～2003年间的13个宏观经济总量的波动特征、共动性和因果关系进行了经验分析,结果显示中国总产出的周期长度在改革开放之后呈现出延长且波动幅度下降的趋势,而且总产出的波动主要受到第二和第三产业产出波动的影响,长期以来第一产业发展对总产出的制约在改革开放之后消失了,结果还显示要素投入在中国经济增长中依然发挥着举足轻重的作用。总体来说,中国经济周期在改革开放以后呈现出更加明显的一般性周期特征。

Collective Directional Transport in Symmetric Periodic Potentials by Breaking the Coupling Symmetry

Collective unidirectional motion of an asymmetrically coupled array of oscillators in symmetric periodic potentials is studied. A directed current is observed when the drift coupling is presented, while no external biased force is applied. Negative directed current is found when varying system parameters. An addition of a periodic rocking force may enhance the efficiency of directed transport. Resonant steps of the current are found and interpreted as the mode locking between the array and the ac force. Noise-assisted transport is observed, and an optimal noise intensity can give rise to a most efficient transport. The directed transport thus can be optimized and furthermore controlled by suitably adjusting the parameters of the system.

Multiplicative Stochastic Resonance for a Linear System Driven by O-U Noise

In the paper, we study a linear system driven by O-U noise and give a method which is different from the one stated in Europhys. Lett. 40 （1997） 117. We find the same phenomenon of multiplicative stochastic resonance for the response of the system to the signal as the one found in Europhys. Left. 40 （1997） 117. The merit of our method is that it prevents the complex formulas when making sum from n = 0 to n →∞ as in Europhys. Lett. 40 （1997） 117, which leads to the approximate results of the figures.

Urban Mobility： Method of Analysis of the Adequacy of Public Policies in Cities Based on the Principles Proposed by the UN

Addressing urban mobility is a priority for government agencies due to increasing problems of travel and lack of accessibility, generated by increasing rates of population growth and motorization. The general objective of this study is to propose a method of analysis of the adequacy of policies, aimed at sustainable mobility and its impacts on urbanism. Methodologically, the analysis is based on the parameters proposed by the UN （United Nations）, namely, sectorial planning, mobility funding, management efficiency of urban mobility systems; and mobility system and support for green technology. The object of study is the public policies expressed in urban mobility plans, master plans and regional development plans. Through the applicability of this method, the results show the possibility of verifying the adequacy of public policies as a mechanism that induces improvements in urban mobility with greater levels of sustainability and the possibility of universalized access to users.

How Much Digital Activism Plays a Role in Political Activism： A Case Study of Morocco＇s February 20th Movement

The present paper seeks to investigate the extent to which digital activism plays a role in political activism in Morocco through the intersection between women and young activists movement and the social media. By doing so the author argues that while facebook and the Moroccan political arena are Male dominated public areas, young female activists have emerged as prominent leaders in both spaces. The author will more particularly explain why female and youth activists are important in the current state of Moroccan politics. Next, the author provides a discussion of the February 20th Movement, and the movement＇s utilization of Facebook. It will show that young female activists involved in the February 20th Movement have used Facebook in unique and creative ways to further the Movement.

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.

Numerical Simulation and Control of Two-Phase Flow with Evaporation in a Vertical Tube Submitted to a Conjugate Heat Transfer

A better understanding of two-phase flows with evaporation allows leading to an optimal design of evaporators. For that purpose, numerical simulations are very useful. In this paper, a numerical study has been carried out in order to model and simulate the combination of a two-phase flow with evaporation in a vertical tube. The VOF （volume-of-fluid） multiphase flow method and a phase-change model for the mass transfer have been used. For an accurate modeling, the effect of axial conduction has been also taken into account using a conjugate heat transfer model. Since thermal oscillations are undesirable as they can lead to the failure of the tube, flow instabilities have also been analyzed, using FFT （fast Fourier transforms）, in order to comprehend their behavior and influence. A control study of the flow instabilities in the tube is also presented. For that purpose tube inlet temperature has been varied using a gain control parameter.

Nonlinear Dynamic Reliability of Coupled Stay Cables and Bridge Tower

Nonlinear vibration can cause serious problems in long span cable-stayed bridges.When the internal resonance threshold is reached between the excitation frequency and natural frequency,large amplitudes occur in the cable.Based on the current situation of lacking corresponding constraint criteria,a model was presented for analyzing the dynamic reliability of coupling oscillation between the cable and tower in a cable-stayed bridge.First of all,in the case of cable sag,the d'Alembert principle is applied to studying the nonlinear dynamic behavior of the structure,and resonance failure interval of parametric oscillation is calculated accordingly.Then the dynamic reliability model is set up using the JC method.An application of this model has been developed for the preliminary design of one cable-stayed bridge located on Hai River in Tianjin,and time histories analysis as well as reliability indexes have been obtained.When frequency ratio between the cable and tower is approaching 1∶2,the reliability index is 0.98,indicating high failure probability.And this is consistent with theoretical derivation and experimental results in reference.This model,which is capable of computing the reliability index of resonance failure,provides theoretical basis for the establishment of corresponding rule.

Evolution of Cooperation in Public Goods Games

We investigate the evolution of cooperation with evolutionary public goods games based on finite populations, where four pure strategies： cooperators, defectors, punishers and loners who are unwilling to participate are considered. By adopting approximate best response dynamics, we show that the magnitude of rationality not only quantitatively explains the experiment results in [Nature （London） 425 （2003） 390], but also it will heavily influence the evolution of cooperation. Compared with previous results of infinite populations, which result in two equilibriums, we show that there merely exists a special equilibrium cooperation. In addition, we characterize that loner＇s and the relevant high value of bounded rationality will sustain payoff plays an active role in the maintenance of cooperation, which will only be warranted for the low and moderate values of loner＇s payoff. It thus indicates the effects of rationality and loner＇s payoff will influence the cooperation. Finally, we highlight the important result that the introduction of voluntary participation and punishment will facilitate cooperation greatly.