Control of a Nonlinear System Using the Saturation Phenomenon

In this paper, a theoretical investigation of nonlinear vibrations of a 2 degrees of freedom system when subjected to saturation is studied. The method has been especially applied to a system that consists of a DC motor with a nonlinear controller and a harmonic forcing voltage. Approximate solutions are sought using the method of multiple scales. It is shown that the closed-loop system exhibits different response regimes. The nature and stability of these regimes are studied and the stability boundaries are obtained. The effects of the initial conditions on the response of the system have also been investigated. Furthermore, the second-order solution is presented and the corresponding results are compared with those of the first-order solution. It is shown that by increasing the amplitude of the excitation voltage, the higher-order term in the solution becomes significant and causes a drift in the response. In order to verify the obtained theoretical results, they are compared with the corresponding numerical results. Good agreement between the two sets of results is observed.     

The detection of tetrahydrofuran hydrate formation and saturation using magnetic resonance imaging technique

Tetrahydrofuran (THF) hydrate was formed in bulk as well as in glass beads pack with a mean diameter of 3.0 mm by controlling the temperature under ambient pressure. Images of THF hydrate formation procedure were obtained using the magnetic resonance imaging (MRI) technique. The experiment results showed that MRI is an effective method for the detection of hydrate formation. Saturation of hydrate formed both in bulk and glass beads can be confirmed by intensity integration of MRI images.     

The fluctuating phase error analysis in the digital grating phase-shifting profilometry

The nonlinear response of the experimental system and the saturation of fringe patterns can induce the fluctuating phase error in the projection grating phase-shifting profilometry. Two major factors of the fluctuating phase error are discussed by simulation. The fluctuating phase error caused by the nonlinear response of the system is four times the frequency of the fringe pattern when the conventional four-frame phase extracting algorithm is used. However, such error can be decreased by five-frame algorithm. On the other hand, the fluctuating phase error caused by the fringe saturation is five times the frequency of the fringe pattern by using conventional five-frame phase extracting algorithm. A novel phase recovering algorithm is used to decrease the phase error caused by the saturation. Furthermore, the applicability range of the proposed phase recovering algorithm is analyzed by simulation and experiments with different saturation degree of the fringe pattern and nonlinearity of the measurement system.     

Gluon saturation and net-proton spectra in relativistic nucleus-nucleus collisions

By means of the AKK08 fragmentation function, the net-proton transverse momentum (pT) spectra in A+A collisions are studied with two phenomenological models based on the Color Glass Condensate formalism. After a x2 analysis of the experimental data from BRAHMS, the normalization constant C is extracted at RHIC energies of √SNN =62.4 and 200 GeV, and the theoretical results of the net-proton pT spectra at selected rapidities are also given. It is shown that the theoretical results are in good agreement with the experimental data. Finally, assuming the constant C should have an exponent dependence of √SNN, we also predict the theoretical results of net-proton pT spectra at LHC energies of √SNN = 2.76, 3.94, and 5.52 TeV.     

A facile method to synthesize magnetic polymer nanospheres with multifunctional groups

Magnetic poly(styrene methyl methacrylate)/Fe₃O₄ nanospheres with ester groups were prepared by a modified one-step mini-emulsion polymerization in the presence of Fe₃O₄ ferrofluids. The effects of monomer dose, surfactant content, ferrofluid concentration and initiator content on the particle characteristics such as the size, morphology and magnetic properties were investigated by Fourier-transform infrared spectroscopy, transmission electron microscopy, thermogravimetric analysis and vibrating sample magnetometer. The results indicated that magnetic nanospheres were superparamagnetic with high saturation magnetization of 51.0 emu/g and corresponding magnetite content of 61.5 wt%. Subsequently, magnetic nanospheres with carboxyl and amino groups were also obtained by hydrolysis and ammonolysis reaction. These magnetic nanospheres with multifunctional groups have biomedical applications.     

Initial conditions and global event properties from color glass condensate

Perturbative unitarization from non-linear effects is thought to deplete the gluon density for transverse momenta below the saturation scale. Such effects also modify the distribution of gluons produced in heavy-ion collisions in transverse impact parameter space. I discuss some of the consequences for the initial conditions for hydrodynamic models of heavy-ion collisions and for hard “tomographic” probes. Also, I stress the importance of realistic modelling of the fluctuations of the valence sources for the small-x fields in the impact parameter plane. Such models can now be combined with solutions of running–coupling Balitsky–Kovchegov evolution to obtain controlled predictions for initial conditions at the LHC.     

唇周紫绀新生儿与正常新生儿血氧饱和度对比分析

为了探讨新生儿出现唇周紫绀与缺氧关系，选择了两组新生儿（唇周紫绀组及正常组各101例），进行了血氧饱和度检测，结果表明无论是周紫绀或是正常新生儿，只要其呼吸频率＜600bpm，血氧饱和度均大于等于94％，将这两组新生儿血氧饱和度进行对比检测，证实两组均数无显著性差异（P＞0．05），提示仅有唇周紫绀不能作为缺氧依据。     

13C‐NMR detection of STD spectra

We have investigated the use of ¹³C for the detection of saturation transfer difference (STD) NMR spectra. By detecting the STD spectrum in the ¹³C channel it is possible to eliminate the residual water signal in the STD‐NMR spectrum. We have employed an INEPT transfer in order to shift the magnetization from the proton channel to ¹³C. As a sample system to check our method we have used human serum albumin and phenylalanine. We have shown that such a transfer can be accomplished and gives reasonable signal intensities. Copyright © 2009 John Wiley & Sons, Ltd.     

Method of Probabilistic Convolutions for Interpreting Data of Electromagnetic Logging

A new method is proposed for processing the data of electromagnetic logging in wells. The method is based on the hydrodynamic analysis of drilling mud filtrate penetration into the oil stratum, determination of the field of electrical resistances of the near-well zone with its subsequent averaging by convolutions with a kernel in the form of a logarithmically normal distribution of probe sensitivity.     

多元StancU多项式的最优逼近阶及其特征刻画

对于单纯形上的多元Stancu多项式Mn(f，x)(它是多元Bernstein多项式的广义形式)，我们给出其对连续函数的最优逼近阶及其特征刻画，即我们将依据某-K-泛函确定满足‖Mnf-f‖=O(n^-1)的函数类．同时，得到了逼近的正定理和逆定理．