Integrated Optimal and Robust Control of Spacecraft in Proximity Operations

With the rapid growth of space activities and advancement of aerospace science and technology, many autonomous space missions have been proliferating in recent decades. Control of spacecraft in proximity operations is of great importance to accomplish these missions. The research in this dissertation aims to provide a precise, efficient, optimal, and robust controller to ensure successful spacecraft proximity operations. This is a challenging control task since the problem involves highly nonlinear dynamics including translational motion, rotational motion, and flexible structure deformation and vibration. In addition, uncertainties in the system modeling parameters and disturbances make the precise control more difficult. Four control design approaches are integrated to solve this challenging problem. The first approach is to consider the spacecraft rigid body translational and rotational dynamics together with the flexible motion in one unified optimal control framework so that the overall system performance and constraints can be addressed in one optimization process. The second approach is to formulate the robust control objectives into the optimal control cost function and prove the equivalency between the robust stabilization problem and the transformed optimal control problem. The third approach is to employ the è-D technique, a novel optimal control method that is based on a perturbation solution to the Hamilton-Jacobi-Bellman equation, to solve the nonlinear optimal control problem obtained from the indirect robust control formulation. The resultant optimal control law can be obtained in closedorm, and thus facilitates the onboard implementation. The integration of these three approaches is called the integrated indirect robust control scheme. The fourth approach is to use the inverse optimal adaptive control method combined with the indirect robust control scheme to alleviate the conservativeness of the indirect robust control scheme by using online parameter estimation such that adaptive, robust, and optimal properties can all be achieved. To show the effectiveness of the proposed control approaches, six degree-offreedom spacecraft proximity operation simulation is conducted and demonstrates satisfying performance under various uncertainties and disturbances

Fabrication and Investigation of Two-Component Film of 2,5-Diphenyloxazole and Octafluoronaphthalene Exhibiting Tunable Blue/Bluish Violet Fluorescence Based on Low Vacuum Physical Vapor Deposition Method

Organic luminescent materials play an important role in the fields of light-emitting diodes and fluorescent imaging. Moreover, new synthetic approaches towards π-conjugated molecular systems with high fluorescence quantum efficiency are highly desired. Herein, different 2,5-diphenyloxazole-octafluoronaphthalene (DPO-OFN) films with tunable fluorescence have been prepared by Low Vacuum Physical Vapor Deposition (LVPVD) method. DPO-OFN films showed some changed properties, such as molecular vibration and fluorescence. All films exhibited blue/bluish violet fluorescence and showed blue shift, in comparison with pristine DPO. This work introduced a new method to fabricate two-component molecular materials with tunable blue/bluish violet luminescence properties and provided a new perspective to prepare organic luminescent film materials, layer film materials, cocrystal materials, and cocrystal film materials. Importantly, these materials have potential applications in the fields of next generation of photofunctional materials

Fabrication and Investigation of Two-Component Film of 2,5-Diphenyloxazole and Octafluoronaphthalene Exhibiting Tunable Blue/Bluish Violet Fluorescence Based on Low Vacuum Physical Vapor Deposition Method

Organic luminescent materials play an important role in the fields of light-emitting diodes and fluorescent imaging. Moreover, new synthetic approaches towards -conjugated molecular systems with high fluorescence quantum efficiency are highly desired. Herein, different 2,5-diphenyloxazole-octafluoronaphthalene (DPO-OFN) films with tunable fluorescence have been prepared by Low Vacuum Physical Vapor Deposition (LVPVD) method. DPO-OFN films showed some changed properties, such as molecular vibration and fluorescence. All films exhibited blue/bluish violet fluorescence and showed blue shift, in comparison with pristine DPO. This work introduced a new method to fabricate two-component molecular materials with tunable blue/bluish violet luminescence properties and provided a new perspective to prepare organic luminescent film materials, layer film materials, cocrystal materials, and cocrystal film materials. Importantly, these materials have potential applications in the fields of next generation of photofunctional materials

Mapping of Quantitative Trait Loci Underlying Nodule Traits in Soybean (Glycine max (L.) Merr.) and Identification of Genes Whose Expression Is Affected by the Sinorhizobium fredii HH103 Effector Proteins NopL and NopT

Symbiotic nitrogen fixation provides most of the nitrogen required for soybean growth. Rhizobial nodulation outer proteins (Nops) have been reported to influence host specificity during symbiosis establishment. However, the host proteins that interact with Nops remain unknown. In this study, we generated Sinorhizobium fredii HH103 mutants (HH103ΩNopL, HH103ΩNopT, and HH103ΩNopLΩNopT) and analysed the nodule number (NN) and nodule dry weight (NDW) of 12 soybean germplasms after inoculation with wild-type S. fredii HH103 or the mutant strains. The analysis of chromosome segment substitution lines revealed quantitative trait loci (QTLs) associated with NopL and NopT interactions. A total of 22 QTLs for the 2 nodule traits were detected and mapped to 12 different chromosomes in the soybean genome. Eight and fifteen QTLs were found to be associated with NN and NDW, respectively. Furthermore, 17 candidate genes were selected for further analyses. Considering the results of reverse-transcription quantitative PCR, we propose that the protein products of these 17 candidate genes interact with NopL and NopT

Mapping of Quantitative Trait Loci Underlying Nodule Traits in Soybean (<i>Glycine max</i> (L.) Merr.) and Identification of Genes Whose Expression Is Affected by the <i>Sinorhizobium fredii</i> HH103 Effector Proteins NopL and NopT

Symbiotic nitrogen fixation provides most of the nitrogen required for soybean growth. Rhizobial nodulation outer proteins (Nops) have been reported to influence host specificity during symbiosis establishment. However, the host proteins that interact with Nops remain unknown. In this study, we generated Sinorhizobium fredii HH103 mutants (HH103ΩNopL, HH103ΩNopT, and HH103ΩNopLΩNopT) and analysed the nodule number (NN) and nodule dry weight (NDW) of 12 soybean germplasms after inoculation with wild-type S. fredii HH103 or the mutant strains. The analysis of chromosome segment substitution lines revealed quantitative trait loci (QTLs) associated with NopL and NopT interactions. A total of 22 QTLs for the 2 nodule traits were detected and mapped to 12 different chromosomes in the soybean genome. Eight and fifteen QTLs were found to be associated with NN and NDW, respectively. Furthermore, 17 candidate genes were selected for further analyses. Considering the results of reverse-transcription quantitative PCR, we propose that the protein products of these 17 candidate genes interact with NopL and NopT