Novel Stabilization Conditions for Uncertain Singular Systems with Time-Varying Delay

The problem of delay-dependent robust stabilization for continuously singular time-varying delay systems with norm-bounded uncertainties is investigated in this paper. First, based on some mathematical transform, the uncertain singular system is described in a form which involves the time-delay integral items. Then, in terms of the delay-range-dependent Lyapunov functional and the LMI technique, the improved delay-dependent LMIs-based conditions are established for the uncertain singular systems with time-varying delay to be regular, causal, and stable. Furthermore, by solving these LMIs, an explicit expression for the desired state feedback control law can be obtained; thus, the regularity, causality, and stability of the closed-loop system are guaranteed. In the end, numerical examples are given to illustrate the effectiveness of the proposed methods

Polyoxometalate Modified Separator for Performance Enhancement of Magnesium–Sulfur Batteries

The magnesium–sulfur (Mg‐S) battery has attracted considerable attention as a candidate of post‐lithium battery systems owing to its high volumetric energy density, safety, and cost effectiveness. However, the known shuttle effect of the soluble polysulfides during charge and discharge leads to a rapid capacity fade and hinders the realization of sulfur‐based battery technology. Along with the approaches for cathode design and electrolyte formulation, functionalization of separators can be employed to suppress the polysulfide shuttle. In this study, a glass fiber separator coated with decavanadate‐based polyoxometalate (POM) clusters/carbon composite is fabricated by electrospinning technique and its impacts on battery performance and suppression of polysulfide shuttling are investigated. Mg–S batteries with such coated separators and non‐corrosive Mg[B(hfip)4]2 electrolyte show significantly enhanced reversible capacity and cycling stability. Functional modification of separator provides a promising approach for improving metal–sulfur batteries

Novel Stabilization Conditions for Uncertain Singular Systems with Time-Varying Delay

The problem of delay-dependent robust stabilization for continuously singular time-varying delay systems with norm-bounded uncertainties is investigated in this paper. First, based on some mathematical transform, the uncertain singular system is described in a form which involves the time-delay integral items. Then, in terms of the delay-range-dependent Lyapunov functional and the LMI technique, the improved delay-dependent LMIs-based conditions are established for the uncertain singular systems with time-varying delay to be regular, causal, and stable. Furthermore, by solving these LMIs, an explicit expression for the desired state feedback control law can be obtained; thus, the regularity, causality, and stability of the closed-loop system are guaranteed. In the end, numerical examples are given to illustrate the effectiveness of the proposed methods.Peer Reviewe

Adsorption of Human Serum Albumin (HSA) by SWNTs/Py-PW₁₁ Nanocomposite

Covalently grafted pyrene moieties onto the K₇[PW₁₁O₃₉]·13H₂O cluster (K₇-PW₁₁) results in the formation of a new organic/inorganic hybrid with the molecular formula of (Bu₄N)₄{(PW₁₁O₃₉)­[O­(Si­(CH₂)₃NH–COOCH₂C₁₆H₉)₂]} (Py-PW₁₁), which has been immobilized onto single-walled carbon nanotubes (SWNTs) homogeneously via π–π stacking and electrostatic interactions. The resulting SWNTs/Py-PW₁₁ nanocomposite material exhibits excellent adsorption of human serum albumin (HSA), as evidenced by high-resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS) studies. This work paves a new pathway for the development of polyoxometalate (POM)-based biomaterials

Finite-Time Vibration-Attenuation Controller Design for Structural Systems with Parameter Uncertainties

The problem of finite-time vibration-attenuation controller design for buildings structural systems with parameter uncertainties is the concern of this paper. The objective of designing controllers is to guarantee the finite-time stability of closed-loop systems with a prescribed level of disturbance attenuation. First, based on matrix transformation, the structural system is described as state-space model, which contains parameter uncertainties. Then, based on finite-time stability analysis method, some sufficient conditions for the existence of finite-time vibration-attenuation controllers are obtained. By solving these conditions, the desired controllers can be obtained for the closed-loop system to be finite-time stable with the performance ∥z∥2 < γ∥ω∥2. It is shown by the simulation results, that compared with some Lyapunov asymptotic stability results, finite-time stability control can obtain better state responses, especially while the system is under nonzero initial states

Cobalt Disulfide Nanoparticles Embedded in Porous Carbonaceous Micro-Polyhedrons Interlinked by Carbon Nanotubes for Superior Lithium and Sodium Storage

Transition metal sulfides are appealing electrode materials for lithium and sodium batteries owing to their high theoretical capacity. However, they are commonly characterized by rather poor cycling stability and low rate capability. Herein, we investigate CoS₂, serving as a model compound. We synthesized a porous CoS₂/C micro-polyhedron composite entangled in a carbon-nanotube-based network (CoS₂-C/CNT), starting from zeolitic imidazolate frameworks-67 as a single precursor. Following an efficient two-step synthesis strategy, the obtained CoS₂ nanoparticles are uniformly embedded in porous carbonaceous micro-polyhedrons, interwoven with CNTs to ensure high electronic conductivity. The CoS₂-C/CNT nanocomposite provides excellent bifunctional energy storage performance, delivering 1030 mAh g^–1 after 120 cycles and 403 mAh g^–1 after 200 cycles (at 100 mA g^–1) as electrode for lithium-ion (LIBs) and sodium-ion batteries (SIBs), respectively. In addition to these high capacities, the electrodes show outstanding rate capability and excellent long-term cycling stability with a capacity retention of 80% after 500 cycles for LIBs and 90% after 200 cycles for SIBs. <i>In situ</i> X-ray diffraction reveals a significant contribution of the partially graphitized carbon to the lithium and at least in part also for the sodium storage and the report of a two-step conversion reaction mechanism of CoS₂, eventually forming metallic Co and Li₂S/Na₂S. Particularly the lithium storage capability at elevated (dis-)­charge rates, however, appears to be substantially pseudocapacitive, thus benefiting from the highly porous nature of the nanocomposite

Tuning the Photocatalytic Activity of Graphitic Carbon Nitride by Plasma-Based Surface Modification

In this study, we demonstrate that plasma treatment can be a facile and environmentally friendly approach to perform surface modification of graphitic carbon nitride (g-CN), leading to a remarkable modulation on its photocatalytic activity. The bulk properties of g-CN, including the particle size, structure, composition, and electronic band structures, have no changes after being treated by oxygen or nitrogen plasma; however, its surface composition and specific surface area exhibit remarkable differences corresponding to an oxygen functionalization induced by the plasma post-treatment. The introduced oxygen functional groups play a key role in reducing the recombination rate of the photoexcited charge carries. As a consequence, the oxygen-plasma-treated sample shows a much superior photocatalytic activity, which is about 4.2 times higher than that of the pristine g-CN for the degradation of rhodamine B (RhB) under visible light irradiation, while the activity of nitrogen-plasma-treated sample exhibits a slight decrease. Furthermore, both of the plasma-treated samples are found to possess impressive photocatalytic stabilities. Our results suggest that plasma treatment could be a conventional strategy to perform surface modification of g-CN in forms of both powders and thin films, which holds broad interest not only for developing g-CN-based high-performance photocatalysts but also for constructing photoelectrochemical cells and photoelectronic devices with improved energy conversion efficiencies