ℒ 1 adaptive controller for tailless unstable aircraft in the presence of unknown actuator failures

This article considers application of ?₁ adaptive controller to multi-input multi-output open loop unstable unmanned military aircraft. The control is designed to accommodate and to be robust to actuator failures as well as to pitch break uncertainty, which is used to model uncertain aerodynamics. Results of using the ?₁ adaptive controller are compared with the conventional model reference adaptive control scheme to show improved transient command tracking as well as guaranteed time-delay margin.     

In-situ FTIR analyses of bentonite under high-pressure

The stability of bentonite is of particular interest for containment barriers in nuclear waste disposal facilities. However, very little is known about the stability of montmorillonite (the major component of bentonite) under high-pressure (HP) conditions. The objective of this work is to investigate the stability of montmorillonite under HP conditions, using a sample of bentonite in which the major component is a dioctahedral calcium montmorillonite. This montmorillonite was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray fluorescence (XRF), specific surface area (SA), thermogravimetric analysis (TGA) and differential thermal analysis (DTA). HP experiments up to 7.7 GPa at room temperature (RT) were performed using toroidal chambers (TC). The samples were characterized by XRD after the HP processing. In-situ FTIR analyses were performed in the samples inside a diamond anvil cell (DAC) up to 8 GPa (dispersed in KBr) and up to 13 GPa (pure bentonite). In-situ FTIR measurements inside the DAC showed that montmorillonite was stable despite a reversible deformation in the Si–O bond and did not lose water up to 13 GPa. XRD analysis of the samples processed at 8 GPa at RT inside the TC showed no marked modification in the (001) reflections and b-parameter (060) reflections of montmorillonite induced by high pressure. The obtained results indicated that montmorillonite remained stable under high pressure conditions.     

Stable adaptation in the presence of input constraints

For a class of linear dynamical systems with unknown parameters a direct model reference adaptive control framework is developed that provides stable adaptation in the presence of input constraints. The proposed design methodology, termed “positive μ-modification”, has the ability to protect the control law from actuator position saturation. The reference system is adaptively modified to ensure global asymptotic tracking for open-loop stable systems. For unstable systems an estimate for the domain of attraction is derived based on the input saturation magnitude and system parameters. Simulation of a benchmark example verifies the theoretical statements.     

Neural network adaptive control for a class of nonlinear uncertain dynamical systems with asymptotic stability guarantees.

In this paper, a neuroadaptive control framework for continuous- and discrete-time nonlinear uncertain dynamical systems with input-to-state stable internal dynamics is developed. The proposed framework is Lyapunov based and unlike standard neural network (NN) controllers guaranteeing ultimate boundedness, the framework guarantees partial asymptotic stability of the closed-loop system, that is, asymptotic stability with respect to part of the closed-loop system states associated with the system plant states. The neuroadaptive controllers are constructed without requiring explicit knowledge of the system dynamics other than the assumption that the plant dynamics are continuously differentiable and that the approximation error of uncertain system nonlinearities lie in a small gain-type norm bounded conic sector. This allows us to merge robust control synthesis tools with NN adaptive control tools to guarantee system stability. Finally, two illustrative numerical examples are provided to demonstrate the efficacy of the proposed approach.     

Mobility study of amorphous polymers by high-resolution NMR at solid-state

Summary Mobility of amorphous polymers such as poly(vinyl chloride) (PVC), atactic polypropylene (PPA) and ethylene-propylene-diene terpolymer (EPDM) were studied by proton spin-lattice relaxation time (T₁ H), proton spin-lattice relaxation time in the rotating frame (T₁H), and dipolar dephasing pulse sequence. The data are discussed in terms of mobility and by the distribution of configurational sequences.     

A Patent Review on the Therapeutic Application of Monoclonal Antibodies in COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) contains spike proteins that assist the virus in entering host cells. In the absence of a specific intervention, efforts are afoot throughout the world to find an effective treatment for SARS-CoV-2. Through innovative techniques, monoclonal antibodies (MAbs) are being designed and developed to block a particular pathway of SARS-CoV-2 infection. More than 100 patent applications describing the development of MAbs and their application against SARS-CoV-2 have been registered. Most of them target the receptor binding protein so that the interaction between virus and host cell can be prevented. A few monoclonal antibodies are also being patented for the diagnosis of SARS-CoV-2. Some of them, like Regeneron^® have already received emergency use authorization. These protein molecules are currently preferred for high-risk patients such as those over 65 years old with compromised immunity and those with metabolic disorders such as obesity. Being highly specific in action, monoclonal antibodies offer one of the most appropriate interventions for both the prevention and treatment of SARS-CoV-2. Technological advancement has helped in producing highly efficacious MAbs. However, these agents are known to induce immunogenic and non-immunogenic reactions. More research and testing are required to establish the suitability of administering MAbs to all patients at risk of developing a severe illness. This patent study is focused on MAbs as a therapeutic option for treating COVID-19, as well as their invention, patenting information, and key characteristics.     

Adaptive Dynamic Inversion for Nonaffine-in-Control Uncertain Systems via Time-Scale Separation. Part II

This paper presents an adaptive dynamic inversion method for uncertain nonaffine-in-control dynamical systems. Online approximation of the adaptive dynamic inversion controller is performed using time-scale separation. The resulting control signal is sought as a solution of a “fast” dynamical equation, which inverts a series-parallel model, whose state is shown to track the state of the original nonaffine-in-control system. The design methodology is constructive, and numerically verifiable sufficient conditions on the system parameters are given. A simulation example, motivated by aerospace applications, illustrates the theoretical results.      

Characterization of EPDM/atactic polypropylene blends by high-resolution solid-state NMR

The study of EPDM/atactic polypropylene blend compatibility was investigated by cross-polarization/magic angle spinning carbon-13 NMR spectra, variation contact time experiment analysis, proton spin-lattice relaxation time in the rotating frame, carbon-13 spin-lattice relaxation time, and a dipolar dephasing experiment. The data are discussed in terms of mobility and compatibility of polymeric blends. © 1996 John Wiley & Sons, Inc.