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This paper presents a comparative study of six common pseudospectral (PS) methods for solving optimal spacecraft attitude control problems. The problems of minimum time, minimum control effort, and...

This paper presents a geometric approach for a sun (or any bright object) avoidance slew maneuver with pointing and actuator constraints. It is assumed that a gyrostat has a single light-sensitive ...

Glycosylated compounds are major secondary metabolites of plants, which have various therapeutic effects on human diseases, by acting as anti-cancer, antioxidant, and anti-inflammatory agents. Glycosylation increases stability, bioactivity, and solubility of compounds and improves their pharmacological properties. Two well-known examples of glycosylated compounds include cardiac and flavonoid, the anti-tumor activities of which have been emphasized by several studies. However, little is known about their role in the treatment or prevention of cancer. In this review, recent studies on anti-tumor properties of cardiac and flavonoid glycosides, and their mechanisms of action, have been investigated. More specifically, this review is aimed at focusing on the multifactorial properties of cardiac and flavonoid compounds as well as their correlation with signaling pathways in the treatment of cancer.

Thanks to the synthetic biology, the laborious and restrictive procedure for producing a target protein in living microorganisms by biotechnological approaches can now experience a robust, pliant yet efficient alternative. The new system combined with lab-on-chip microfluidic devices and nanotechnology offers a tremendous potential envisioning novel cell-free formats such as DNA brushes, hydrogels, vesicular particles, droplets, as well as solid surfaces. Acting as robust microreactors/microcompartments/minimal cells, the new platforms can be tuned to perform various tasks in a parallel and integrated manner encompassing gene expression, protein synthesis, purification, detection, and finally enabling cell-cell signaling to bring a collective cell behavior, such as directing differentiation process, characteristics of higher order entities, and beyond. In this review, we issue an update on recent cell-free protein synthesis (CFPS) formats. Furthermore, the latest advances and applications of CFPS for synthetic biology and biotechnology are highlighted. In the end, contemporary challenges and future opportunities of CFPS systems are discussed.

OBJECTIVES Hypertension has been linked to the presence and severity of nonalcoholic fatty liver disease (NAFLD) through unclear mechanisms. The gain-of-function rs5186 A1166C variant in angtiotensin receptor type 1 (AGTR1) gene has been linked to hypertension, cardiovascular disease and metabolic syndrome. We assessed the impact of AGTR1 A1166C variant on NAFLD incidence and severity and on glucose and lipid metabolism and explored the underlying mechanisms. METHODS We followed up 314 healthy nonobese, nondiabetic, nonhypertensive, insulin-sensitive participants in a population-based study, characterized for AGTR1 rs5186 A1166C variant, adipokine profile, inflammatory and endothelial dysfunction markers. An independent cohort of 78 biopsy-proven nondiabetic NAFLD patients and controls underwent an oral glucose tolerance test with Minimal Model analysis of glucose homeostasis, and an oral fat tolerance test with measurement of plasma lipoproteins, adipokines, MCP-1, calprotectin, and nuclear factor-κB activation in circulating mononuclear cells. RESULTS AGTR1 A1166C polymorphism predicted 9.8-year incident NAFLD (odds ratio: 1.67, 95% CI: 1.26-2.21) and hypertension (odds ratio: 1.49, 95% CI: 1.12-2.63) and 9-year increase in cardiovascular disease risk and endothelial dysfunction markers. In the cross-sectional cohort, AGTR1 C allele carriers had higher insulin resistance. Despite comparable fasting lipid profiles, AGTR1 C allele carriers showed postprandial triglyceride-rich and cholesterol-rich VLDL lipoprotein accumulation, higher resistin, MCP-1 and calprotectin responses and nuclear factor-κB activation in mononuclear cells, and a blunted postprandial adiponectin response to fat, which predicted liver histology, hepatocyte apoptosis activation, insulin resistance, and endothelial dysfunction. DISCUSSION AGTR1 A1166C variant affects liver disease, insulin resistance, and endothelial dysfunction in NAFLD, at least in part by modulating adipokine, chemokine, and pro-inflammatory cell activation in response to fat ingestion.

This paper presents the problem of optimal steering with three single-gimbal control moment gyros (SGCMGs). Most SGCMG configurations use more than three rotors because the resulting Jacobian would always have a nontrivial nullspace. We consider the specific case of a four-CMG pyramid configuration where one CMG has failed and only three CMGs are operational. We use the Gauss pseudospectral method to find the optimal gimbal angle trajectories of the CMGs and the states of an agile spacecraft subject to mission-specific constraints while maximally avoiding the angular-momentum singularities. The proposed steering law is tested in scenarios where the gimbal angles initially start in both nonsingular and singular positions. Results are compared with the standard four-SGCMG maneuvering via the generalized singularity robust steering law in the literature.

In this paper, we utilize the observer/Kalman filter identification (OKID) and the eigensystem realization algorithm (ERA) techniques to identify the modal parameters of a centrifugal machine. To this end, we use an experimental setup to generate a pseudo-impulse input and collect output measurements which are corrupted by noise. We use the pseudo-impulse input and the OKID to find the Markov parameters of the system. Then we form the Hankel matrix of the system and determine the singular values of the system. A minimum-order, state-space model of the system is realized through the Markov parameters and then the natural frequency, damping ratio, mode shapes, and modal amplitudes at the sensor location are estimated by the ERA. We find three models for three separate cases and validate all the three identified models with the measured data and the Waterfall plot. The identified models are useful for designing passive or active vibration suppression control and fault detection systems. The results confirm that OKID/ERA is a reliable time-domain method for identifying the modal parameters of vertical centrifuge machines.

Colorectal cancer (CRC) is one of the most disseminated diseases across the globe engaging the digestive system. Various therapeutic methods from traditional to the state-of-the-art ones have been applied in CRC patients, however, the attempts have been unfortunate to lead to a definite cure. MiRNAs are a smart group of non-coding RNAs having the capabilities of regulating and controlling coding genes. By utilizing this stock-in-trade biomolecules, not only disease's symptoms can be eliminated, there may also be a good chance for the complete cure of the disease in the near future. Herein, we provide a comprehensive review delineating the therapeutic relationship between miRNAs and CRC. To this, various clinical aspects of miRNAs which act as a tumor suppressor and/or an oncogene, their underlying cellular processes and clinical outcomes, and, in particular, their effects and expression level changes in patients treated with chemo- and radiotherapy are discussed. Finally, based on the results deducted from scientific research studies, therapeutic opportunities based on targeting/utilizing miRNAs in the preclinical as well as clinical settings are highlighted.

This paper presents and compares two fuzzy controllers for attitude stabilization of a spacecraft with partially filled fuel tank: a fuzzy controller based on the parallel distributed compensation (PDC) technique and a fuzzy controller based on the linear quadratic regulator. Both controllers are built from the Takagi–Sugeno model of the spacecraft. Using the Lyapunov stability theorem, the fuzzy PDC controller design problem was cast as a minimization problem for the upper bound of control input in the form of linear matrix inequalities. In the end, we compare the efficacy and robustness of each controller via numerical simulations.

During million years, Nature has created a “wealthy repertoire of novel features.” These features are frequently used in the fabric of artificial materials, referred to as “biomaterials.” Hydrogels are among the most attractive biomaterials because they are highly amenable to accept nature-derived properties/functionalities. The inclusion of these features in biomaterials serves as promising tools for today’s most urged clinical needs, among others. In this review, we explore the major applications of different bioinspired hydrogels. We focused on rationale design, multi-faceted biomimetics strategies, and their potentials utility in the clinic. For the clinical application, we focused on four major clinical areas of i) regenerative medicine, ii) tissue engineering, iii) cancer therapy, and iv) bioinspired devices/actuators/robots. We discussed how incorporating nature-inspired properties into hydrogels’ design can introduce novel solutions to the many unresolved and persistent problems in biomedicine. Finally, given the complexity of bioinspired hydrogels, we propose that a collective effort among the material scientists, artificial intelligence experts, clinicians, and life sciences is required to pave the path for the entrance of bioinspired hydrogel into personalized medicine and from bench to bedside.

This study presents a fuzzy tracking controller based on the Takagi-Sugeno (T-S) fuzzy model of the solar sail. First, the T-S fuzzy model is constructed by linearizing the existing nonlinear equations of motion of the solar sail. Then, the T-S fuzzy model is used to derive the state feedback controller gains for the Twin Parallel Distributed Compensation (TPDC) technique. The TPDC tracks and stabilizes the attitude of the solar sail to any desired state in the presence of parameter uncertainties and external disturbances while satisfying actuator constraints. The performance of the TPDC is compared to a PID controller that is tuned using the Ziegler-Nichols method. Numerical simulation shows the TPDC outperforms the PID controller when stabilizing the solar sail to a desired state.

Background: Multiple sclerosis (MS) is an organ-specific autoimmune disorder with remarkable heritability. For MS disorder, interleukin 2 receptor α subunit (IL2RA) is regarded as a genetic risk factor. Results: There was a statistically significant association between alleles and genotypes of rs12722489 SNP and MS risk. The levels of mRNA expression and serum IL-2RA were higher in MS patients than in healthy controls. mRNA expression and serum concentrations of IL-2RA were higher in MS patients with CC genotype for rs12722489 compared with the rest of patients. Conclusion: Our result demonstrate that the rs12722489 SNP within IL2RA gene might be associated with MS pathogenesis through regulating the levels of IL-2RA (or CD25), which is important in the regulation of T cells.

In this paper, we focus on interconnected trajectory optimization of two sets of solenoid actuated butterfly valves dynamically coupled in series. The system undergoes different approach angles of a pipe contraction as a typical profile of the so-called "Smart Valves" network containing tens of actuated valves. A high fidelity interconnected mathematical modeling process is derived to reveal the expected complexity of such a multiphysics system dealing with electromagnetics, fluid mechanics, and nonlinear dynamic effects. A coupled operational optimization scheme is formulated in order to seek the most efficient trajectories of the interconnected valves minimizing the energy consumed enforcing stability and physical constraints. We examine various global optimization methods including Particle Swarm, Simulated Annealing, Genetic, and Gradient based algorithms to avoid being trapped in several possible local minima. The effect of the approach angles of the pipeline contraction on the amount of energy saved is discussed in detail. The results indicate that a substantial amount of energy can be saved by an intelligent operation that uses flow torques to augment the closing efforts.

Multiple sclerosis (MS) is an organ-specific autoimmune disorder with remarkable heritability. For MS disorder, interleukin 2 receptor α subunit (IL2RA) is regarded as a genetic risk factor. There was a statistically significant association between alleles and genotypes of rs12722489 SNP and MS risk. The levels of mRNA expression and serum IL-2RA were higher in MS patients than in healthy controls. mRNA expression and serum concentrations of IL-2RA were higher in MS patients with CC genotype for rs12722489 compared with the rest of patients. Our result demonstrate that the rs12722489 SNP within IL2RA gene might be associated with MS pathogenesis through regulating the levels of IL-2RA (or CD25), which is important in the regulation of T cells.

This paper presents an open-loop, minimum-energy control law for attitude maneuver of a solar-sail. The proposed control law utilizes the magnetic torques and reaction wheels to reorient the solar-sail for near-earth missions. Using the calculus of variations and Pontryagin’s minimum principle, the necessary and sufficient conditions were derived for the nonlinear model of the solar-sail. Then the optimal control problem was formulated as a two-point boundary-value problem and solved via the Shooting method. The computed control law can be utilized in a flight-computer and in a sampled-data feedback closed-loop system which can compensate for disturbance torques.

Catastrophic chaotic and hyperchaotic dynamical behaviors have been experimentally observed in the so-called “smart valves” network, given certain critical parameters and initial conditions. The centralized network-based control of these coupled systems may effectively mitigate the harmful dynamics of the valve-actuator configuration which can be potentially caused by a remote set and would gradually affect the whole network. In this work, we address the centralized control of two bi-directional solenoid actuated butterfly valves dynamically coupled in series subject to the chaotic and hyperchaotic dynamics. An interconnected adaptive scheme is developed and examined to vanish both the chaotic and hyperchaotic dynamics and return the coupled network to its safe domain of operation.

This paper presents a study of fuzzy optimal variance control problem for dynamical systems subject to actuator amplitude and rate constraints. Using Takagi-Sugeno fuzzy modeling and dynamic Parallel Distributed Compensation technique, the stability and the constraints can be cast as a multi-objective optimization problem in the form of Linear Matrix Inequalities. By utilizing the formulations and solutions for the input and output variance constraint problems, we develop a fuzzy full-state feedback controller. The stability and performance of the proposed controller are demonstrated through its application to the airfoil flutter suppression.

During axial thrusting of a spin-stabilized spacecraft undergoing orbital injections or control maneuvers, misalignments and center of mass offset create undesired body-fixed torques. The effects of the body-fixed torques, which in turn cause velocity pointing errors, can be reduced by ramping up (and then ramping down) the thruster. Closed-form solutions for the angular velocity, Euler angles, inertial velocity, and inertial displacement solutions with nonzero initial conditions are given. Using the closed-form solutions, the effect of variations in the spin axis moment of inertia and spin rate on the spacecraft velocity pointing error are shown. The analytical solutions closely match numerical simulations.

This paper presents a Takagi-Sugeno (T-S) fuzzy model-based approach to model and control a rigid spacecraft with flexible antenna. First, the equations of motion of the flexible spacecraft, which are based on Lagrange equations and given in terms of quasi-coordinates and the Rayleigh-Ritz method, are briefly reviewed. Then, the T-S fuzzy modeling and the parallel distributed compensation control technique are introduced. We utilize full state-feedback and optimal H∞ robustness performance via a T-S fuzzy model to achieve position and attitude stabilization, vibration suppression, and disturbance rejection objectives. Finally, this technique is applied to the flexible spacecraft equations of motion resulting in a nonlinear controller. The controller produces an asymptotically stable closed-loop system which is robust to external disturbances and has a simple structure for straightforward implementation. Numerical simulation is provided for performance evaluation of the proposed controller design.

This paper presents a robust-optimal fuzzy controller for position and attitude stabilization and vibration suppression of a flexible spacecraft during antenna retargeting maneuver. The fuzzy controller is based on Takagi–Sugeno (T–S) fuzzy model and uses the parallel distributed compensator (PDC) technique to quadratically stabilize the closed-loop system. The proposed controller is robust to parameter and unstructured uncertainties of the model. We improve the performance and the efficiency of the controller by minimizing the upper bound of the actuator's amplitude and maximizing the uncertainties terms included in the T–S fuzzy model. In addition to actuator amplitude constraint, a fuzzy model-based observer is considered for estimating unmeasurable states. Using Lyapunov stability theory and linear matrix inequalities (LMIs), we formulate the problem of designing an optimal-robust fuzzy controller/observer with actuator amplitude constraint as a convex optimization problem. Numerical simulation is provided to demonstrate and compare the stability, performance, and robustness of the proposed fuzzy controller with a baseline nonlinear controller.

This paper presents the study of a fuzzy optimal covariance control problem for wing shaping control of coupled aeroelastic aircraft models at various flight conditions and subject to actuator amplitude and rate constraints. Using Takagi-Sugeno fuzzy modeling and Parallel Distributed Compensation techniques, the stability and the constraints can be cast as a multi-objective optimization problem in the form of Linear Matrix Inequalities. By utilizing the formulations and solutions for the output covariance constrained problems, we develop a fuzzy full-state feedback controller and a fuzzy full-order observer for aeroelastic aircraft with flexible wings. The efficacy of the proposed controllers are examined on the NASA Generic Transport Model which is configured with the Variable Camber Continuous Trailing Edge Flaps.

We use Kane’s method to derive the equations of motion of a spinning spacecraft with three momentum wheels, a nutation damper, and a spherical pendulum. The spherical pendulum is adopted as a simple mechanical equivalent of fuel sloshing in partially filled tanks. The proposed model is an extension of existing models in the literature. We verify and validate our model for two cases: flat spin and a simple reorientation maneuver. Numerical simulations are in agreement with existing results in the literature. The results confirm the accuracy of the model for a typical spacecraft.

We consider the problem of a spacecraft subjected to constant body-fixed forces and moments about all three axes during a spinning-up, thrusting maneuver. In applications, undesired forces and moments can arise due to thruster imbalances and misalignments and to center-of-mass offset. In previous works, approximate analytical solutions have been found for the attitude motion, and for the change in inertial velocity and inertial position. In this paper we find asymptotic and limiting-case expressions which we derive from the analytic solutions, in order to obtain simplified, practical formulas that lend insight into the motion. Specifically, we investigate how the motion evolves (1) as time grows without bound and (2) for geometric cases of the sphere, the thin rod, and the thin plate. Closed-forms or upper-bound limits are provided for angular velocities, Eulerian angles, angular momentum pointing error, transverse and axial velocities, and transverse and axial displacements. Summaries for the asymptotic limits (for zero initial conditions) are provided in tabular form. Results are verified by numerical simulations.

Introduction I N 1965, Armstrong [1] developed analytical solutions for thrusting, spinning-up, axisymmetric rigid bodies and considered some geometric cases for high spin rates. He introduced compact results for translational and rotational motion of a rigid body in space in the presence of body-fixed forces and moments. Although his results are important, they are not complete and, unfortunately, they have not been presented in a conference or published in an archived journal. In his doctoral thesis, Ayoubi [2] verified and completed Armstrong’s asymptotic theory for thrusting and for spinning-up rigid bodies. In other work, Longuski and Kia [3], Beck and Longuski [4], and Javorsek and Longuski [5] presented asymptotic limits for some special cases for thrusting and spinning-up spacecraft when the body-fixed forces and moments are constant and when the body is axisymmetric or nearly axisymmetric. In this paper, we use the results introduced by Longuski et al. [6] for angular velocity, Eulerian angles, and transverse and axial displacements and examine those solutions for limiting cases of the spinning, thrusting rigid body in which the spin rate remains nearly constant.

An approximate analytical solution is presented for the axial velocity of a spinning-up spacecraft subject to constant body-fixed forces and moments. We assume that the rigid body spins about the maximum or the minimum principal moment of inertia. Also, it is assumed that the deviation of the spin axis from an inertially fixed direction is small. Our closed-form solution for axial velocity applies to axisymmetric, nearly axisymmetric, and in some cases asymmetric rigid bodies. Furthermore, asymptotic limits are determined for large spin rates and for some geometric limits such as a sphere, a thin rod, and a flat disk. When the axial body-fixed force is nonzero, the axial velocity is dominated by the expected secular term of axial acceleration multiplied by time. However, when the axial force is zero, then the much more complicated effects of the transverse forces come into play: there are no longer any secular terms, but rather there is an asymptotic limit to the axial velocity accrued from the projection of the transverse accelerations onto the inertial direction of the initial spin axis. The axial velocity solution consists of Fresnel integrals, integrals of Fresnel integrals, and many new families of related integrals. Numerical simulation demonstrates the accuracy of the analytical solution in a practical example.

This paper presents a robust-optimal fuzzy controller for position and attitude stabilization, and vibration suppression of a flexible spacecraft during antenna retargeting maneuver. The fuzzy controller is based on Takagi-Sugeno (T-S) fuzzy model and uses the dynamic parallel distributed compensator (DPDC) technique to quadratically stabilize the closed-loop system. The proposed controller is robust to parameter and unstructured uncertainties of the model. We improve the performance and the efficiency of the controller by minimizing the upper bound of the actuators amplitude and rate, and maximizing the uncertainties terms included in the T-S fuzzy model. In addition to actuator amplitude and rate constraints, a fuzzy model-based observer is considered for estimating unmeasurable states. Using Lyapunov stability theory and linear matrix inequalities (LMIs), we formulate the problem of designing an optimal-robust fuzzy controller/observer with actuator amplitude and rate constraints as a convex optimization problem. Numerical simulation is provided to demonstrate and compare the stability, performance, and robustness of the proposed fuzzy controller with a baseline nonlinear controller.

We propose a shared fuzzy controller for position and attitude control of multiple quadrotor unmanned aerial vehicles (UAVs). Using the nonlinear governing equations of motion and kinematics of a quadrotor, we develop a Takagi-Sugeno (T-S) fuzzy model for a quadrotor. Then, we consider time-varying delays due to wireless connectioninto the T-S fuzzy model. We use the sufficient stability condition based on the Lyapunov-Krasovskii stability theorem and the parallel distributed compensation (PDC) technique to determine the fuzzy control law. For practical purposes, we include actuator amplitude constraint into the design process. The problem of designing a shared fuzzy controller is cast in the form of linear matrix inequalities (LMIs). A feasible solution region is found in terms of maximum magnitude and rate of time-varying delay. In the end, the stability, performance, and robustness of the proposed shared fuzzy controller are examined via numerical simulation.Copyright © 2015 by ASME

A spinning, nearly axisymmetric rigid body is subject to constant, body-fixed forces and transverse body-fixed torques. Because no torque is applied along the spin axis and the rigid body is nearly axisymmetric, the spin rate remains nearly constant. By further assuming small angular excursions of the spin axis (with respect to an inertially fixed direction), approximate closed-form analytical solutions are obtained for attitude, rotational, and translational motion. The compact solutions in complex form are eminently suitable for analyzing maneuvers of spinning spacecraft. Numerical simulations confirm that the solutions are highly accurate when applied to typical motion of a spacecraft such as the Galileo spacecraft.

This paper presents a Takagi-Sugeno fuzzy model-based controller which stabilizes the attitude of spacecraft with a partially-filled fuel tank. First, the nonlinear equations of motion of spacecraft containing a liquid fuel store is presented briefly. Then, the fuzzy modeling and the parallel distributed compensation control technique are applied. The proposed fuzzy controller is a nonlinear controller which utilizes full-state feedback with bounded control input. Using a quadratic Lyapunov function, the fuzzy control design problem can be formulated in terms of linear matrix inequalities. In the end, we evaluate the proposed control system performance via numerical simulation results.

This paper presents a fuzzy nonlinear controller to regulate the longitudinal dynamics of an aircraft and suppress the bending and torsional vibrations of its flexible wings. The fuzzy controller utilizes full-state feedback with input constraint. First, the Takagi-Sugeno fuzzy linear model is developed which approximates the coupled aeroelastic aircraft model. Then, based on the fuzzy linear model, a fuzzy controller is developed to utilize a full-state feedback and stabilize the system while it satisfies the control input constraint. Linear matrix inequality (LMI) techniques are employed to solve the fuzzy control problem. Finally, the performance of the proposed controller is demonstrated on the NASA Generic Transport Model (GTM).

This paper presents the optimal control for a minimum-time, large-angle reorientation maneuver of a quadrotor unmanned aerial vehicle. We use the Euler’s equations of motion and the Modified Rodrigues Parameters to describe the attitude motion of the vehicle. The minimum-time optimal control problem for large-angle reorientation maneuvers is formulated based on calculus of variations and Pontryagin’s minumum principle. At the end, the minimum-time problem is solved numerically and optimal controls are found for a typical quadrotor unmanned aerial vehicle. The numerical simulations confirm our results are in agreement with analytical methods.Copyright © 2012 by ASME

During axial thrusting of a spinning spacecraft, misalignments and center-of-mass oset result in velocity pointing errors. These pointing errors cause the spacecraft to deviate from its desired trajectory. In the typical case, the axial thrust behaves like a step function, jumping from zero to its maximum value. Alternatively, by linearly ramping-up the axial thrust from zero to its maximum value, the velocity pointing errors are signicantly reduced compared to those arising from the step function. Analytical solutions for the ramp-up case are found for the angular velocities, the Euler angles, the inertial velocities, and the inertial displacement. The analytical solutions closely match numerical simulations.