Prescribed-time second-order sliding mode controller design subject to mismatched term

This paper investigates the second-order sliding mode (SOSM) control for uncertain nonlinear systems subject to unknown mismatched terms. A new prescribed-time SOSM controller is developed by applying a time-varying coordinate transformation. The proposed controller can allow to prescribe the convergence time a priori and irrespective of initial conditions even in the presence of mismatched terms. Moreover, all the upper bounds of matched and mismatched uncertainties are not required to be exactly known. Finally, a simulation example with different initial conditions is given to show the effectiveness of the proposed controller. </p

Interpretable Machine Learning to Discover Perovskites with High Spontaneous Polarization

Machine learning can accelerate the design of new materials by screening large quantities of materials. We investigated the spontaneous polarization intensity of inorganic perovskite ferroelectrics using a machine learning approach. The machine learning model covers the entire structure type of perovskite ferroelectrics. We make a large number of predictions for perovskite materials based on our model and screen 20 perovskite materials that have high spontaneous polarization intensity. We employ the SHAP (Shapley additive explanations) technique to qualitatively explain the machine learning model’s correctness from a physical point of view. The results show that the larger the average atomic radius and the smaller the electronegativity of the metal atoms of the perovskite, the easier it is to find greater spontaneous polarization intensity. We also screen and verify the reasonableness of descriptors based on the model interpretation to improve the reliability of the model. By utilizing an interpretable machine learning approach, we can predict and optimize the properties of ferroelectrics, which facilitates the evaluation and application of materials

Prescribed-time second-order sliding mode controller design subject to mismatched term

This paper investigates the second-order sliding mode (SOSM) control for uncertain nonlinear systems subject to unknown mismatched terms. A new prescribed-time SOSM controller is developed by applying a time-varying coordinate transformation. The proposed controller can allow to prescribe the convergence time a priori and irrespective of initial conditions even in the presence of mismatched terms. Moreover, all the upper bounds of matched and mismatched uncertainties are not required to be exactly known. Finally, a simulation example with different initial conditions is given to show the effectiveness of the proposed controller. </p

Sustainable Cooling Strategies Using New Chemical System Solutions

Energy-efficient cooling concepts play an important role for numerous applications in the area of comfort and industrial cooling. In this regard, it represents a huge challenge to ensure that the cooling demand of industrialized countries is covered in a sustainable manner with a drastically reduced carbon footprint. In recent years, several innovations in the field of absorption have been introduced. While some of them are based on process improvements, other innovations are based on newly developed chemical system solutions. One example is the use of new working pairs for absorption chillers. In the past, working pair related drawbacks such as crystallization, corrosion, and instability led to a number of innovation barriers. One very promising way to overcome these drawbacks and thereby to allow for new or improved absorption chiller processes is the replacement of the state-of-the-art absorbent LiBr by a suitable ionic liquid (IL). This review aims at discussing new, energy-efficient cooling concepts with a special focus on using ionic liquid based working pairs in absorption chillers/absorption heat pumps. The most relevant research and development activities are analyzed, a patent overview is provided, and both new technological opportunities and remaining scientific challenges are identified. Although a large number of ionic liquid papers have been published in this field during the last 10 years, many contributions do not adequately address the interdisciplinary set of application requirements and do not fully recognize that most imidazole-based ionic liquids are not suitable for being used in multieffect absorption cycles since their (in)­stability at high temperatures in the presence of water and the resulting cooling capacity do not meet the industrial requirements

Electrospun Nanofibers Modified with Copper Nanoparticles for Simultaneous Extraction and Detection of Three Ochratoxins in Foods

In this study, several electrospun nanofibers were prepared and characterized, and the electrospun polystyrene/poly(ether sulfone) nanofiber coated with copper nanoparticles (PS/PES-CuNP nanofibers) was selected and utilized as solid-phase extraction adsorbent. And then, the packed-fiber solid-phase extraction coupled with high-performance liquid chromatography-fluorescence detection method was established for the efficient determination of ochratoxins in foods. With the proposed method, several factors including the type and dosage of nanofibers, sample pH, extraction time, type, and volume of elution solvent were optimized. The results suggested that low limit of detection (0.102–0.126 ng/mL), limit of quantification (0.382–0.436 ng/mL), and recoveries (85.5–111.1%) for ochratoxin A, B, and C with relative standard deviations <7% were achieved. As-synthesized PS/PES-CuNP nanofibers displayed satisfactory potential practical application in the simultaneous pretreatment and determination of mycotoxins in complex matrice samples

On stability of model predictive control with finite-control-set constraints and disturbances

This paper investigates the stability issues of model predictive control (MPC) for discrete-time linear systems with state and finite control set (FCS) constraints subject to time-varying disturbances. A new FCS-MPC design and analysis framework is developed using the disturbance estimation approaches and the tool of robust positive invariant (RPI) set sequence. It encompasses a discrete-time exogenous signal observer that helps characterize the estimated dynamics within well-defined bounds and a quantized control law that adheres to both state and input constraints. The practical asymptotical stability of the resulting closed-loop system is shown to be guaranteed, and the tracking error remains uniformly bounded. Finally, simulation results of a numerical example validate the effectiveness of the proposed method.</p

Two Novel Cu/Mn Metal-Organic Framework Based on Aromatic Dicarboxylic Acid: Synthesis, Crystal Structure, Thermal Stability, and Luminescence Properties

<p>Two novel transition metal complexes formulated as [Cu(4,5-Himdc)(phen)]<i>_n</i> (<b>1</b>) and [Mn(5,6-Hbidc)(H₂O)]<i>_n</i> (<b>2</b>) (4,5-H₃imdc = imidazole-4,5-dicarboxylic acid, 5,6-H₃bidc = 1<i>H</i>-benzimidazole-5,6-dicarboxylic acid, phen = 1,10-phenanthroline) have been synthesized under hydro(solvo)thermal method at a relatively low temperature and characterized by elemental analysis, IR spectroscopy, and X-ray single-crystal diffraction. <b>1</b> based on 4,5-H₃imdc displays one-dimensional zigzag chain structure. <b>2</b> based on 5,6-H₃bidc features a two-dimensional framework with 4-connected topology. Thermal stabilities and luminescence properties of the two complexes were investigated.</p

Ketamine-induced antidepressant-like behavioral effects in the FST.

<p>Ketamine-induced immobility and swimming time, respectively, in C57BL/6N mice (A,B) and in mice lacking NMDAR specifically in PV neurons (PV-Cre+/NR1f/f, <i>red bars</i>) compared with control (NR1f/f, <i>black bars</i>)(C,D). (A) Immobility of C57BL/6N mice in repeated FST 30 min, 24 h and 1 week after acute treatment with 3.0 mg/kg ketamine (<i>grey bars</i>, n = 8) or saline (<i>black bars</i>, n = 8). Results (sec/4 min) are presented as mean values ±SEM. Ketamine induces a rapid antidepressant response by significantly reducing immobility already 30 min after treatment. The antidepressant effect decreases over time. Ketamine-induced immobility time is: 192±5 saline and 116±16 ketamine (30 min) (p<0.001 Student's t-test); 196±8 saline and 149±17 ketamine (24 h) (p<0.05 Student's t-test); 183±14 saline and 163±14 ketamine (1 week) (p>0.05 Student's t-test). (B) Swimming scored in the experiment in (A). Ketamine-induced swimming time is: 47±5 saline and 123±16 ketamine (30 min) (p<0.001 Student's t-test); 44±8 saline and 91±17 ketamine (24 h) (p<0.05 Student's t-test); 57±14 saline and 77±14 ketamine (1 week) (p>0.05 Student's t-test). (C) Immobility of PV-Cre+/NR1f/f and NR1f/f mice in repeated FST after acute treatment with 3.0 mg/kg ketamine. Immobility time 30 min, 24 h and 1 week after ketamine is: 89±15, 121±13 and 174±11 (NR1f/f <i>black bars</i>, n = 6); 84±19, 83±14 and 155±12 (PV-Cre+/NR1f/f <i>red bars</i>, n = 9), respectively. (D) Swimming scored in the experiment in (C). Swimming time 30 min, 24 h and 1 week after ketamine is: 145±14, 118±13 and 66±11 (NR1f/f <i>black bars</i>, n = 6); 149±18, 156±14 and 85±12 (PV-Cre+/NR1f/<i>red bars</i>, n = 9), respectively. Both genotypes display similar behavioral response to the ketamine treatment. Results (sec/4 min) are presented as mean values ±SEM.</p

Sucrose preference test in animals lacking NMDAR in PV neurons.

<p>(A) Outline of the water intake and the sucrose preference test in PV-Cre+/NR1f/f and NR1f/f mice. (B) Water intake test (WIT) in mice lacking NMDAR specifically in PV neurons (PV-Cre+/NR1f/f, <i>red bars</i>, n = 9) compared with control mice (NR1f/f, <i>black bars</i>, n = 6). WIT was run for 24 h. Results (gr) are presented as mean values ±SEM (p>0,05;Student's t-test). (C) Sucrose preference test (SPT) in mice lacking NMDAR specifically in PV neurons (PV-Cre+/NR1f/f, <i>red bars</i>, n = 9) compared with control mice (NR1f/f, <i>black bars</i>, n = 6). SPT was run for 72 h. Results (sucrose intake/total intake ×100) are presented as mean values ±SEM (p>0,05;Student's t-test). Both genotypes display similar behavioral response.</p