Search

The problem of optimizing the maximum range of a glide guided bomb is studied based on the principle of solving optimal control problems using the Radau pseudo-spectral method. The dynamic model of the guided bomb is nondimensionalized. Combining with the Pontryagin minimum principle, the analytic solution of the optimal control and the first-order necessary condition are derived. The trajectory optimization problem is translated to a nonlinear programming via the Radau pseudo-spectral method. Based on covector mapping principle, an optimality verification method is presented for the numerical solution. Simulation results show that the Radau pseudo-spectral method can provide a highly valuable optimal solution for engineering application. Compared with the conventional maximum lift-to-drag ratio gliding trajectory, the trajectory after optimization can be extended by more than 10%. [ABSTRACT FROM AUTHOR]

Abstract: The self-affine measure corresponding to an expanding integer matrix is supported on the attractor (or invariant set) of the iterated function system . In the present paper we show that if and is not a multiple of 3, then there exist at most 3 mutually orthogonal exponential functions in , and the number 3 is the best. This extends several known results on the non-spectral self-affine measure problem. The proof of such result depends on the characterization of the zero set of the Fourier transform , and provides a way of dealing with the non-spectral problem. [Copyright &y& Elsevier]

Abstract: The self-affine measure corresponding to the expanding integer matrix is supported on the generalized three-dimensional Sierpinski gasket , where p is odd. In the present paper we show that there exist at most 7 mutually orthogonal exponential functions in . This generalizes the result of Dutkay and Jorgensen [D.E. Dutkay, P.E.T. Jorgensen, Analysis of orthogonality and of orbits in affine iterated function systems, Math. Z. 256 (2007) 801–823] on the non-spectral self-affine measure problem. By using the same method, we also obtain that for self-affine measure corresponding to the expanding integer matrix where p is odd, there exist at most 5 mutually orthogonal exponential functions in . [Copyright &y& Elsevier]

Abstract: Rapamycin-loaded chitosan/polylactic acid nanoparticles with size of about 300nm in diameter were prepared through nanoprecipitation method using cholesterol-modified chitosan as a stabilizer. The surface coating of chitosan, which was demonstrated by zeta potential measurement, endowed the nanoparticles good retention ability at the procorneal area, facilitating the sustained release of rapamycin on the corneal. The immunosuppression in corneal transplantation of the nanoparticles was investigated using rabbit as animal model, the median survival time of the corneal allografts treated with nanoparticles was 27.2±1.03 days and 50% grafts still remained surviving by the end of the observation, while the group treated with 0.5% rapamycin suspension was 23.7±3.20 days. The median survival time of drug-free nanoparticles group and untreated groups were 10.9±1.45 and 10.6±1.26 days, respectively. The results demonstrated the excellent immunosuppression of rapamycin-loaded chitosan/polylactic acid nanoparticles in corneal transplantation. [Copyright &y& Elsevier]

Abstract: Cholesterol hydrophobically modified chitosan (CS-CH) containing 1.7–4.7 cholesterol groups per 100 anhydroglucosamine units of chitosan were synthesized by an EDC-mediated coupling reaction. The physicochemical properties of the self-aggregated nanoparticles in physiological saline were studied using transmission electron microscopy, dynamic light scattering, and fluorescence spectroscopy. The mean diameters of all samples were less than 230nm, and the critical aggregation concentration (CAC) of all self-aggregated nanoparticles in physiological saline less than 4.0×10−2 mg/ml. Both the mean diameters and the CAC decreased slightly with the increasing degree of substitution (DS) by hydrophobic groups. The self-aggregated CS-CH nanoparticles were radiolabeled by 99mTc, their ocular distribution was investigated using single photon emission computed tomography (SPECT) and scintillation counter. The CS-CH nanoparticles retained at the procorneal area, and no radioactivity was found in the posterior segment. The drug-loading and release behavior of the nanoparticles were investigated using Cyclosporine A (CyA) as the model drug. CyA was physically entrapped in the nanoparticles during the dialysis process, and the drug-loading ratio was 6.2%. A sustained release of CyA from CS-CH nanoparticles was observed. The results showed that CS-CH nanoparticles might represent an interesting vehicle to enhance the therapeutic index of clinically challenging drugs with potential application at extraocular level. [Copyright &y& Elsevier]

Objective Modify hydroxyapatite whisker (HAPw) by nano zinc oxide(ZnO) to synthesize a kind of antibacterial implant bone compound material, and study its degradation and substantial changing in extreme environment. Methods Nano ZnO was prepared through sol-gel method, and modified HAPw by nano ZnO to achieve nano ZnO-HAPw compound material. According to ISO 10993-14 standards,the degradation rate of nano ZnO-HAPw was tested after soaked in citrate buffer solution, the surface morphology change was examined with by scanning electric microscope(SEM) and XRD analysis. Results The degradation rate was 25.44% (HAPw/n-ZnO),18.59% (HAPw), respectively. SEMshowed apparently that HAPw fractured and the quantities of nano ZnO particles significantly reduced after soaking. XRD analysis indicated that the three strong peaks of HAPw lowered. Conclusion Nano ZnO-HAPw is a low soluble materials. [ABSTRACT FROM AUTHOR]