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11.
The paper studies nonlinear dynamics and control of a class of space station based mobile flexible two-link manipulators, normally referred to as the Mobile Servicing System (MSS).The governing nonlinear, nonautonomous and coupled equations of motion are described first followed by the modal discretizations procedure. A parametric response study suggests situations with unacceptable levels of deflections and accelerations for certain proposed missions, as well as station libration and payload positioning errors.An inverse control technique is proposed to achieve high tracking accuracy of the MSS in presence of maneuver induced disturbances. The control strategy is so designed as to regulate the libration of the Space Station as well as to insure joints tracking of prescribed trajectories, while limiting the effect of the structural vibration during large slewing maneuvres of the MSS. Two different control schemes, both based on the feedback linearization technique, are developed and their relative merit assessed.This investigation was supported by the Centers of Excellence Program, Grant No. IRIS/C-8, 5-55380, and Natural Sciences and Engineering Research Council of Canada, Grant No. A-2181. 相似文献
12.
Shobhana K. Menon Nishith R. Modi Bhoomika Mistry Kuldeep Joshi 《Journal of inclusion phenomena and macrocyclic chemistry》2011,71(1-2):121-127
As a part of our investigations to unfold the chemistry of calixresorcinarene, we have focused on the formation of inclusion complex of a poorly soluble (43 μg ml?1 at pH 7) drug mycophenolate mofetil (MMF) an immunosuppressive agent and an inosine monophosphate dehydrogenase (IMPDH) inhibitor with para sulphonatocalix[4]resorcinarene (PSC4R). The complete complexation of the drug was achieved after 48 h of stirring with para sulphonatocalix[4]resorcinarene(PSC[4]R) in water and evaporation of water yield the solid complex. The interaction between para sulphonatocalix[4]resorcinarene(PSC[4]R) and MMF in solid state inclusion complexes was accomplished by aqueous phase solubility studies, Thermal Analysis, HPLC, PXRD, FT-IR, and UV–Vis spectroscopy. The results of the phase solubility experiments are in good conformity to signify the formation of 2:1 PSC4R: MMF complexes. The purpose of this study was to enhance solubility and resulting in high dissolution rate and bioavailability of this essentially water insoluble drug. The results of the in vivo study shows that there is a remarkable change in the toxicity of the pure drug MMF and complex did not produce any mortality up to 2200 mg kg?1. 相似文献
13.
Structural and spectroscopic investigation of ZnS nanoparticles grown in quaternary reverse micelles 总被引:1,自引:0,他引:1
Manyar HG Iliade P Bertinetti L Coluccia S Berlier G 《Journal of colloid and interface science》2011,354(2):511-516
ZnS nanoparticles were synthesized in four component "water in oil" microemulsions formed by a cationic surfactant (cetyltrimethylammonium bromide, CTAB), a cosurfactant (pentanol or butanol), n-hexane and water. The effect of various parameters (nature of cosurfactant, water/surfactant W(0), and alcohol/surfactant P(0)) on the formation and stability of ZnS nanoparticles was investigated thoroughly. UV-Vis spectroscopy was employed to directly follow the formation of ZnS systems in the microemulsions. Thus, particle size was estimated from the position of the first excitonic transition by employing an approximate finite-depth equation and an empirical correlation, giving average diameters in the ranges 2.3-2.5 and 3.0-3.5nm, respectively. Stable ZnS nanoparticles were obtained by employing low water and high cosurfactant amounts. This suggests that at high concentration the cosurfactant molecules act as capping agents on the surface of the inverse micelles, while low water amounts are needful to obtain water droplets with a radius close to that of the interfacial film spontaneous curvature. HRTEM analysis showed that the samples are formed by a few crystalline ZnS nanoparticles of spherical shape, embedded in and amorphous organic matrix, with a coherent scattering domain between 2 and 4nm. 相似文献
14.
15.
Summary The DAP architecture brings into consideration the Jacobi method where several non-interacting rotations can be performed in parallel. However the design of the algorithm is crucial in a parallel environment. In this paper we shall consider two techniques specifically designed to reduce the organisation and the arithmetic components of the parallel Jacobi method. 相似文献
16.
N.S. Ramegowda M.N. Modi A.K. Koul J.M. Bora C.K. Narang N.K. Mathur 《Tetrahedron》1973,29(23):3985-3986
Synthesis of certain aldehydes from the carboxylic acids has been carried by reduction of the corresponding N-acyl saccharins using SDA. The N-acyl saccharins are easily prepared by reaction of an acid with γ-saccharin chloride, which can be used for the next step of reduction without isolation and purification. This provides a convenient and one step synthesis of aldehydes by combining the two reactions, viz., preparation of the N-acyl compound and its reduction. The method has been successfully applied for the reduction of aliphatic, alicyclic, aromatic, and a α,β-unsaturated acids to the corresponding aldehydes and the yields obtained are quite satisfactory. 相似文献
17.
The consequences of 50 MeV Li3+ ion irradiation (fluence: 5×1013 ions/cm2) on the structural and electrical properties of the Y3+xFe5?xO12 (x=0.0, 0.2, 0.4 and 0.6) garnet system have been investigated over the temperature range of 300–673 K. It is found that the percentage formation of an additional yttrium orthoferrite phase observed along with the bcc garnet phase considerably reduces for x=0.4 and 0.6 compositions after swift heavy ion (SHI) irradiation. The nature of thermal variation of DC resistivity curves for x=0.0 and 0.2 compositions is different from that for x=0.4 and 0.6 compositions. The SHI irradiation influences the magnitude of DC resistivity and conduction mechanism for the single-phase compositions while for mixed-phase compositions they remain unaffected. The results have been explained in the light of replacement of magnetic (5μB), smaller (0.64 Å), Fe3+ ion by nonmagnetic (0μB), larger (0.89 Å), Y3+ ion, the presence of the yttrium orthoferrite phase and swift heavy ion irradiation-induced paramagnetic centers in the system. 相似文献
18.
Durgesh Dubey Smriti Chaurasia Anupam Guleria Sandeep Kumar Dinesh Raj Modi Ramnath Misra Dinesh Kumar 《Magnetic resonance in chemistry : MRC》2019,57(1):30-43
Currently, there are no reliable biomarkers available that can aid early differential diagnosis of reactive arthritis (ReA) from other inflammatory joint diseases. Metabolic profiling of synovial fluid (SF)—obtained from joints affected in ReA—holds great promise in this regard and will further aid monitoring treatment and improving our understanding about disease mechanism. As a first step in this direction, we report here the metabolite specific assignment of 1H and 13C resonances detected in the NMR spectra of SF samples extracted from human patients with established ReA. The metabolite characterization has been carried out on both normal and ultrafiltered (deproteinized) SF samples of eight ReA patients (n = 8) using high-resolution (800 MHz) 1H and 1H─13C NMR spectroscopy methods such as one-dimensional 1H CPMG and two-dimensional J-resolved1H NMR and homonuclear 1H─1H TOCSY and heteronuclear1H─13C HSQC correlation spectra. Compared with normal SF samples, several distinctive 1H NMR signals were identified and assigned to metabolites in the 1H NMR spectra of ultrafiltered SF samples. Overall, we assigned 53 metabolites in normal filtered SF and 64 metabolites in filtered pooled SF sample compared with nonfiltered SF samples for which only 48 metabolites (including lipid/membrane metabolites as well) have been identified. The established NMR characterization of SF metabolites will serve to guide future metabolomics studies aiming to identify/evaluate the SF-based metabolic biomarkers of diagnostic/prognostic potential or seeking biochemical insights into disease mechanisms in a clinical perspective. 相似文献
19.
One‐pot Synthesis of Fully Substituted Pyrimidines Using Amidine and Ketene Dithioacetals as Synthons and Their Antimicrobial Activity 下载免费PDF全文
Sagar P. Gami Haresh G. Kathrotiya Yogesh T. Naliapara 《Journal of heterocyclic chemistry》2015,52(3):751-755
A simple, convenient, and efficient one‐pot synthesis of fully substituted pyrimidines was developed by cyclocondensation of α‐oxo ketene dithioacetals with amidine in the presence of potassium carbonate in good yield. Structures of all the newly synthesized compounds were elucidated by elemental analysis and spectral analysis. All the newly synthesized compounds are tested toward different microorganisms. 相似文献
20.
Modi Kalpesh V. Jani Hardik K. Gamit Ilesh D. 《Journal of Thermal Analysis and Calorimetry》2021,143(2):899-913
Journal of Thermal Analysis and Calorimetry - The thermal performance of solar still can be enhanced by means of nanoparticles. The core aim of the present work is to identify the influence of... 相似文献