Control Synthesis Research Articles

Optimal and simultaneous synthesis of fractional order QFT controllers and prefilters for non-minimum phase hydro power systems

Abstract Ideally, the operating frequency of the power units, working in parallel, must not deviate from its nominal value. However, due to the dynamic nature of the load, operating frequency varies throughout the day; thus, the control of governors in the prime movers is essential to balance out the demand, and prevent any frequency deviation. To address this, present study investigates the design of optimal and robust quantitative feedback theory based (QFT) controllers and pre-filters for single area load frequency control of hydro power systems. Hydropower system model considered in the present study features a right-hand side zero, thus exhibiting non-minimum phase; these characteristics make the control more challenging. Also, the work investigates the optimal design of the QFT controllers and prefilters simultaneously by automating the loop shaping procedure, which else follows a sequential manual process on Nichols charts. The proposed automation also empowers the control designer to predefine the controller structure. In the present work the design of fractional order QFT controllers and pre-filters is considered. The study also compares the proposed work with the methods proposed in the existing literature as well as the optimal controllers obtained using the time domain indices. The obtained results establishes that the developed fractional QFT controller offers good tracking, stability, and robustness to disturbances when compared to existing approaches. The proposed fractional order QFT controllers offer the elimination of the overshoot and the undershoot from the closed loop response of the system; outperforms the existing controllers in terms of disturbance rejection; offers 0% steady-state deviation, while providing improved phase margin (60.1°) for enhanced stability compared to existing controllers. Also, the proposed QFT-GA attains the ideal values for both the peak complementary sensitivity functions; thus, establishing excellent robustness. Also, the proposed controllers ensure adequate tolerance to frequency deviation in case of load change.

Self‐promoted Controlled Ring‐opening Polymerization via Side Chain‐mediated Proton Transfer for the Synthesis of Tertiary Amine‐pendant Polypeptoids

Proton transfer is essential in virtually all biochemical processes, with enzymes facilitating this transfer by optimizing the proximity and orientation of reactants through site‐specific hydrogen bonds. Proton transfer is also crucial in the rate‐determining step for the ring‐opening polymerization of N‐carboxyanhydrides (NCAs), widely used to prepare various peptidomimetic materials. This study utilizes side chain‐assisted strategy to accelerate the rate of chain propagation by using NCAs with tertiary amine pendants. This moiety enables hydrogen bond formation between the incoming NCA and the polymer amino growing end. The tertiary amine side chain of the NCA forms a proton shuttle, via a less constrained transition state, to facilitate the proton transfer process. Moreover, the tertiary amine side chains enable the precipitation of NCA monomers through in situ protonation during the monomer synthesis. This greatly facilitates the synthesis of these unreported monomers, allowing the direct controlled synthesis of tertiary amine‐pendant polypeptoids. This side chain‐promoted polymerization has rarely been reported. Additionally, the tertiary amine side chains, as widely used functional groups, endow the polymers with unique properties including pH‐ and thermo‐responsiveness, tunable pKas, and siRNA transfection capability. The self‐promoted synthesis, facile monomer preparation, and attractive properties make tertiary amine‐pendant polypeptoids promising materials for various applications.

Deuteration Degree Controllable Synthesis of Aryl Deuteromethyl Ethers Through Dual photoredox and Thiol Catalysis.

Herein, we report a facile and efficient deuteration degree controllable method for the preparation of aryl deuteromethyl ethers through dual photoredox and thiol catalysis using phenols as the starting materials and inexpensive D2O and CDCl3 as the deuterium sources. All aryl d1, d2, and d3 deuteromethyl ethers can be precisely prepared with good to excellent yields and deuteration ratios. The reaction operates under mild conditions without the need for high temperatures or high loading of transition metal catalysts, and a wide range of functional groups are well tolerated.

Self-promoted Controlled Ring-opening Polymerization via Side Chain-mediated Proton Transfer for the Synthesis of Tertiary Amine-pendant Polypeptoids.

Proton transfer is essential in virtually all biochemical processes, with enzymes facilitating this transfer by optimizing the proximity and orientation of reactants through site-specific hydrogen bonds. Proton transfer is also crucial in the rate-determining step for the ring-opening polymerization of N-carboxyanhydrides (NCAs), widely used to prepare various peptidomimetic materials. This study utilizes side chain-assisted strategy to accelerate the rate of chain propagation by using NCAs with tertiary amine pendants. This moiety enables hydrogen bond formation between the incoming NCA and the polymer amino growing end. The tertiary amine side chain of the NCA forms a proton shuttle, via a less constrained transition state, to facilitate the proton transfer process. Moreover, the tertiary amine side chains enable the precipitation of NCA monomers through in situ protonation during the monomer synthesis. This greatly facilitates the synthesis of these unreported monomers, allowing the direct controlled synthesis of tertiary amine-pendant polypeptoids. This side chain-promoted polymerization has rarely been reported. Additionally, the tertiary amine side chains, as widely used functional groups, endow the polymers with unique properties including pH- and thermo-responsiveness, tunable pKas, and siRNA transfection capability. The self-promoted synthesis, facile monomer preparation, and attractive properties make tertiary amine-pendant polypeptoids promising materials for various applications.

Advanced Model with a Trajectory Tracking Stabilisation System and Feasible Solution of the Optimal Control Problem

In this study, we consider the extended optimal control problem and search for a control function in the class of feasible functions for a real control object. Unlike the classical optimal control problem, the control function should depend on the state, not time. Therefore, the control synthesis problem for the initial-state domain should be solved, instead of the optimal control problem with one initial state. Alternatively, an optimal trajectory motion stabilisation system may be constructed. Both approaches—control and trajectory motion stabilisation system syntheses—cannot be applied to real-time control, as the task is too complex. The minimum threshold of quality criteria is searched for in the space of mathematical expression codes. Among other problems, the search space is difficult to define and the gradient is hard to determine. Therefore, the advanced control object model is used to obtain a feasible control function. The advanced model is firstly obtained before solving the optimal control problem and it already includes a trajectory motion stabilisation system; in particular, this stabilisation system is synthesised in advance at the control system design stage. When the optimal control problem appears, it is solved in real time in the classical statement, and a control function is searched for as a function of time. The advanced control object model also uses the reference model to generate the optimal trajectory. The search for the optimal control function is performed in real time and considers the synthesised stabilisation system of motion along a determined trajectory. Machine learning control via symbolic regression, namely, the network operator method, is used to directly solve the control synthesis problem. An example solution of the optimal control problem, with an advanced model moving in the environment with obstacles for a group of two mobile robots, is presented. The obtained solution is a control function for a reference model that generates a trajectory from a class of trajectories stabilised with the object’s control system.

Nonlinear control of a planar vertical take‐off and landing with a slung load

AbstractThis paper presents the development of the dynamical model of a planar vertical take‐off and landing (PVTOL) carrying a suspended load. The complete model is obtained using the Euler–Lagrange approach. Furthermore, the synthesis of a nonlinear control is presented that stabilizes the vehicle to a desired position, and the load is stabilized as well. The stability is obtained using LaSalle invariance theorem. The performance of the obtained controller is shown in numerical simulations.

Controllable Synthesis of Thioacetals/Thioketals and β-Sulfanyl Ketones Mediated by Methanesulfonic Anhydride and Sulfuric Acid Sulfuric Acid from Aldehyde/Acetone and Thiols.

A novel and controllable synthesis of thioacetals/thioketals and β-sulfanyl ketones mediated by the reaction of aldehyde/acetone with thiols has been developed. In this protocol, β-sulfanyl ketones can be generated without the prior preparation of α, β-unsaturated carbonyl compounds. A variety of thiols reacted with aldehyde/acetone and provided the corresponding thioacetals/thioketals and β-sulfanyl ketones in good to excellent yields, respectively. This protocol is operationally simple, mild, and atom-economical, providing controllable access to thioacetals/thioketals and thia-Michael addition products under mild conditions.

Electrodeposition-Grown Mixed-Halide Inorganic Perovskite CsPbI3-xBrx Nanowires for Nanolaser Applications.

Exploring new low-cost and controllable synthesis methods for perovskite nanowires plays an important role in achieving their large-scale applications. However, there have been no studies on the synthesis of cesium lead halide nanowires using the electrodeposition method. In this study, the single-crystal mixed-halide W-CsPbI3-xBrx nanowires are first synthesized via a low-cost and controllable electrodeposition method. The growth process of the W-CsPbI3-xBrx nanowires is observed in situ by using a metallurgical microscope. It is found that the W-CsPbI3-xBrx nanowires are grown via the oriented attachment of B-CsPbI3-xBrx nanocubes. More importantly, the mixed-halide W-CsPbI3-xBrx nanowires can transform into single-crystal B-CsPbI3-xBrx nanowires at a moderate annealing temperature. The obtained B-CsPbI3-xBrx nanowires are applied to nanolasers, and two lasing peaks are observed at 679 and 675nm, with a threshold of 277.6µJcm-2. These results can promote the development of growth methods for perovskite nanomaterials, which can broaden the applicability of perovskite nanowires in integrated nanophotonic and optoelectronic devices.

A Novel Convexification Method for Control Synthesis Analysis of Continuous-Time Saturated Positive Polynomial Fuzzy Systems Under Imperfect Premise Matching

A Novel Convexification Method for Control Synthesis Analysis of Continuous-Time Saturated Positive Polynomial Fuzzy Systems Under Imperfect Premise Matching

Nano-Metal-Organic Frameworks and Nano-Covalent-Organic Frameworks: Controllable Synthesis and Applications.

Nanoscale framework materials have received much attention due to their diverse morphologies as well as good properties, and synthetic methods to construct different dimensions have been reported. Therefore, the study of the relationship between different sizes, dimensions and properties has become a hot research topic. This article provides a comprehensive examination of the controllable synthesis strategies of nano-metal-organic frameworks (nano-MOFs) and nano-covalent-organic frameworks (nano-COFs) and their applications in energy storage and catalysis. Commences with an overview of the synthetic evolution of nanoscale framework materials, which have garnered attention due to their exceptional specific surface area, regular pores, and tunable structural functionality. Various preparation methods for 0D, 1D, 2D and 3D nanostructures are then highlighted. These synthesis strategies not only improve the stability and activity of the materials, but also provide a basis for the design of novel energy storage and catalytic materials. Furthermore, the article presents an overview of the recent advancements in the field of energy storage and catalysis, with a particular focus on the applications of nano-MOFs/COFs in zinc-, lithium-, and sodium-based batteries as well as supercapacitors. ​.

Experimental and computational insights into oxygen vacancy-rich MoO2-x/N-doped carbon nanowires as high-performance cathode for magnesium batteries and magnesium-lithium hybrid batteries

This work aims to develop efficient cathode materials for magnesium based batteries, which are considered promising next-generation energy storage and conversion devices. One major challenge in magnesium based batteries is the strong Coulomb interaction between magnesium ions and cathode materials, which hinders ion storage and diffusion. To overcome this, we designed and synthesized oxygen vacancy-rich MoO2-x/N-doped carbon nanowires (MoO2-x-NC-NWS). The materials were prepared through a controlled synthesis process, ensuring the incorporation of N-doped carbon and oxygen vacancies, which play crucial roles in improving magnesium ion diffusion and storage. The prepared MoO2-x-NC-NWS demonstrated superior energy storage performance, achieving a capacity of 64 mAh/g in magnesium batteries and 263 mAh/g in magnesium-lithium hybrid batteries at a current density of 50 mA/g. Theoretical calculations further confirmed that oxygen vacancies enhance the diffusion capabilities of magnesium and lithium ions, thereby improving the overall energy storage performance. Therefore, the controllable synthesis of defects such as oxygen vacancies and the development of composite cathode materials are clearly effective strategies for enhancing the performance of magnesium-based battery cathodes. Meanwhile, this rational design of MoO2-based nanostructures provides valuable insights into the development of high-performance cathode materials for magnesium-based energy storage systems.

Efficient ethylbenzene production from CO2 and benzene in a single-bed reactor

The selective synthesis of specific value-added aromatic hydrocarbons through CO2 hydrogenation holds significant strategic importance in mitigating energy and climate issues. However, the process of forming ethylated side chains on benzene rings is challenging, and the methods reported are often limited by multi-bed systems. Here, we show the first CO2 hydrogenation in tandem coupling with benzene alkylation to synthesize ethylbenzene over a single-bed system containing ZnFeOx and nano ZSM-5 catalysts. The results indicated that the bifunctional catalyst composed of ZnFeOx with a Zn/Fe ratio of 0.5 and nano-HZSM-5 exhibits excellent catalytic performance under optimized conditions. The benzene conversion reaches 28.0 %, ethylbenzene selectivity is 61.3 % and the conversion of CO2 is remarkably high, achieving 45.0 %. This single-bed system significantly promotes the in-situ utilization of ethylation intermediates. The introduction of zinc promoted the formation of ZnFe2O4 spinel, which increased the number of active sites due to its superior dispersibility and reducibility. Nano-HZSM-5 demonstrated outstanding ethylbenzene selectivity and catalytic stability owing to its unique shape selectivity, moderate acidity, and superior diffusion properties. This study further explores the reaction network and mechanism through GC–MS analysis and various model reactions, elucidating the formation pathways of primary products in detail. This research provides a new strategy for the controllable synthesis of ethylbenzene using CO2 as a C1 source in a single-bed system.

Controllable synthesis of Pt-rich shell/Mx core [M = Ni, Fe, Co] metal aerogels as efficient electrocatalysts for hydrogen evolution reaction

Water electrolysis for hydrogen production offers a solution to the fossil fuel crisis, relying heavily on electrocatalysts for the hydrogen evolution reaction (HER). Fortunately, metal aerogels (MAs) with three-dimensional network structures reveal great potential as HER electrocatalysts. However, their simple synthesis and widespread application still present significant challenges. Here, PtNix MAs electrocatalysts, by controlling the Ni/Pt feeding ratio and using NaBH4 reduction, are prepared via a simple one-step method. Notably, PtNi4 MAs with Pt-rich shell/Ni core structure exhibit excellent HER property, showing a low overpotential of 16.3 mV at 10 mA cm−2 and a mass activity density of 2.28 A mgPt-1 at 70 mV. The outstanding HER properties of PtNi4 MAs are ascribed to the synergistic catalytic effect of Pt and Ni, the core–shell structure of the sample, and the abundant three-dimensional network porosity. Density functional theory (DFT) demonstrates that PtNi4 MAs’ core–shell structure have the lowest dissociation energy of H2O and ΔGH* on the catalyst surface. Furthermore, the replacement of non-precious metal (Ni/Fe/Co) does not affect the formation of the Pt-rich shell structure. Opposite the substitution of reducing agent species affects the formation of Pt-rich shell structure. This work can offer valuable insights for the future sustainable energy applications of MAs materials.

Controllable synthesis and multiple applications of multi-color sp2c-covalent organic frameworks based on side-chain regulation

Controllable synthesis and multiple applications of multi-color sp2c-covalent organic frameworks based on side-chain regulation

Self-Organizing a Latent Hierarchy of Sketch Patterns for Controllable Sketch Synthesis.

Encoding sketches as Gaussian mixture model (GMM)-distributed latent codes is an effective way to control sketch synthesis. Each Gaussian component represents a specific sketch pattern, and a code randomly sampled from the Gaussian can be decoded to synthesize a sketch with the target pattern. However, existing methods treat the Gaussians as individual clusters, which neglects the relationships between them. For example, the giraffe and horse sketches heading left are related to each other by their face orientation. The relationships between sketch patterns are important messages to reveal cognitive knowledge in sketch data. Thus, it is promising to learn accurate sketch representations by modeling the pattern relationships into a latent structure. In this article, we construct a tree-structured taxonomic hierarchy over the clusters of sketch codes. The clusters with the more specific descriptions of sketch patterns are placed at the lower levels, while the ones with the more general patterns are ranked at the higher levels. The clusters at the same rank relate to each other through the inheritance of features from common ancestors. We propose a hierarchical expectation-maximization (EM)-like algorithm to explicitly learn the hierarchy, jointly with the training of encoder-decoder network. Moreover, the learned latent hierarchy is utilized to regularize sketch codes with structural constraints. Experimental results show that our method significantly improves controllable synthesis performance and obtains effective sketch analogy results.

Controllable syntheses and magnetic and photoelectric properties modulations of CuFeS2 nanoplates

As an antiferromagnetic material, chalcopyrite CuFeS2 has both magnetic and semiconductor properties, which brings great prospects for the application of spintronics devices. Here, chalcopyrite CuFeS2 nanoplates were successfully synthesized through a template mediated method. The CuFeS2 exhibits a tetragonal phase while largely maintaining the hexagonal morphology of the CuS template, with particle sizes ranging between 90 and 120 nm. Specifically, the magnetic properties of CuFeS2 can be tuned by varying the Fe content. The strong room-temperature ferromagnetism is attributed to the coexistence of the ferromagnetic Fe7S8 and the antiferromagnetic CuFeS2, as well as to the unsaturated spin states of Fe on the surfaces of the nanoplates. Furthermore, the photoresponses of CuFeS2 nanoplates were confirmed by I-V measurements under dark and light illumination. The stable photoresponse capability is attributed to its semiconductor properties. This novel room-temperature ferromagnetism and photoelectric effect promotes the development of CuFeS2 nanoplates, and has great significance for the synthetic pathways of other ternary magnetic compounds.

Direct Synthesis of Reduced-Order Controllers With Integrating Action for a Class of Norm-Bounded Uncertain Plants

Direct Synthesis of Reduced-Order Controllers With Integrating Action for a Class of Norm-Bounded Uncertain Plants

Modeling and Robust H∞ Control Synthesis of the CAV-HDV Heterogeneous Traffic System With Different Car-Following Modes

Modeling and Robust H_∞ Control Synthesis of the CAV-HDV Heterogeneous Traffic System With Different Car-Following Modes

Carboxymethyl cellulose assisted morphology controlled synthesis of Mn3O4 nanostructures for adsorptive removal of malachite green from water

The physicochemical properties of manganese oxides and their different applications mainly depend upon their crystallite size, morphology, phase structure, and surface properties, which are again dependent on the preparation methods. So, a simple, cost-effective, and versatile synthesis method for such materials is highly desirable. Intending to accomplish this, herein we report the synthesis of Mn3O4 nanostructures by alkaline hydrolysis of the corresponding metal ions in an aqueous medium. The addition of a biodegradable polymer, sodium salt of carboxymethyl cellulose (Na-CMC) assisted the development of specific morphology, which is tunable by varying the concentration of the biopolymer. The spectroscopic, microscopic, and diffractometric analyses of the synthesized Mn3O4 nanostructures confirm that this particular simple technique is very effective in controlling the morphology of the formed nanostructures. These Mn3O4 nanostructures exhibit excellent adsorption capacity in the removal of malachite green (MG) from its aqueous solution under ambient conditions. The adsorption process is exothermic following pseudo-second-order kinetics with a maximum dye adsorption capacity of 489.68 mg g−1 according to the Sips isotherm model. The Mn3O4 nanostructures can be reused for up to five cycles of dye adsorption without significant loss of their adsorption performance.

Combustion synthesis of TiO2/C composites for enhanced photocatalytic H2O2 production and solar steam evaporation efficiency

In this work, a simple combustion method was proposed for the controllable synthesis of TiO2/C composites, which can achieve both the efficient solar water evaporation at the interface and photocatalytic H2O2 production. Structural and morphological characteristic indicated the co-existence of carbon quantum dots and amorphous carbon, which were well distributed on the surface of the TiO2. TiO2/C composites displayed the enhanced visible light absorption and the rapid separation of photogenerated electron-hole pairs. TiO2/C-10 exhibited an excellent photocatalytic H2O2 production activity of 3068.46 μmol/g/h under simulated solar irradiation. Besides, its water evaporation rate reach up to 5.81 kg·m−2·h−1 under the simulated solar irradiation.