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ABSTRACTA numerical simulation approach is substantiated and verified for predicting the Taylor-Couette flow with an impermeable outer stationary cylinder and porous rotating inner one. An imposed throughflow is considered, supplied via one end of the annular gap and leaving the domain through another gap end (retentate) and from inside of the rotating cylinder (permeate). The flow is typical for dynamic filtration by rotating cylindrical filters. In contrast to known publications, the rotating porous cylinder is included into the computational domain and the liquid flow inside of it is fully resolved. The influence of the permeate-retentate ratio and permeability of the rotating inner cylinder onto the centrifugal stability boundary and supercritical flow details is discussed. It is found that filtration velocity becomes distributed not uniformly along the porous cylinder when its hydraulic resistance  is less than a definite value. After some critical threshold, the flow structure drastically changes, and spiral vortices appears, which crosses the porous rotating cylinder back and forth several times, providing multiple flow recirculation through the porous cylinder. The results obtained create the basis for the development of dynamic rotational filters for various applications.

Stereotaxic instrument is an indispensable tool for numerous types of neuroscience studies and is routinely performed in neuroscience laboratories as part of a variety of experimental procedures. Due to the development of robotics and automation, the stereotaxic instrument for rodents has made great progress, while it is relatively backward and scarce for birds. A digital stereotaxic instrument for pigeons (Columba livia), a classic animal model for learning, memory and cognition, was developed in this study. Its performance was verified from three aspects including stereotaxic accuracy, stereotaxic stability and stereotaxic reproducibility. The developed stereotaxic instrument has the following characteristics: (1) a digital positioning system was used, which is characterized by high stereotaxic accuracy; (2) a novel head-fixation system was developed to increase the adaptability of head-fixation; (3) a four-point fixation method was suggested, improving the stability of head-fixation; (4) the stereotaxic instrument has strong versatility, which can be suitable for a wide variety of birds. Moreover, the proposed stereotaxic instrument has better positioning accuracy and stability, which will promote the study of neural mechanisms for pigeons.

Mesoporous materials have a wide range of applications in the fields of nanotechnology, biotechnology, information technology, and medicine, but historically, the resource materials used for their synthesis have been expensive. Natural silicate minerals are characterized by their abundance, low cost, and large SiO2contents, making them an alternative silicon source for mesoporous silica. The objective of the present study was to determine the utility of natural chlorite as the source of Si for synthesizing hexagonal mesoporous silica materials (MCM-41). The natural chlorite was pretreated by acid leaching and calcination, followed by a hydrothermal reaction with cetyltrimethylammonium bromide (CTAB) as the template, and subsequent calcination to prepare MCM-41. The structures and the porosity of MCM-41 were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), 29Si magic-angle spinning solid-state nuclear magnetic resonance spectroscopy (29Si MAS NMR), and N2adsorption–desorption measurements. The mechanism of structural evolution from natural chlorite to MCM-41 was investigated using these techniques. Calcination of chlorite results in amorphization and partial structural breakdown, while subsequent acid leaching dissolves the Mg and Al in the octahedral sheets to leave the Si–O framework as a silicon source. 29Si MAS NMR results revealed that the ratio of Q4/Q3increased from 0.91 to 1.21 after hydrothermal synthesis of MCM-41 from leached chlorite, demonstrating more polymerization of the Si–O structure in MCM-41. The final MCM-41 products were amorphous SiO2, with a large surface area of 630 m2/g, a pore volume of 0.46 mL/g, and a narrow pore-size distribution of 2.8 nm. MCM-41 showed favorable adsorption toward methylene blue (MB) with a monolayer adsorption capacity of up to 302 mg/g, indicating potential for application in adsorption.

The cylinder block/valve plate interface is one of the most critical frictional interfaces of the swashplate-type axial piston pump. However, the poor lubrication interface caused rapid wear and high friction loss in an elastohydrodynamic lubrication system, decreasing the pump lifetime. Wear resistant bronze coatings were fabricated on 38CrMoAl substrate by Physical Vapor Deposition (PVD) and Chemical Vapor Deposition (CVD), respectively. Ball-on-disc wear tests were performed to comparatively investigate the wear behaviors of the coatings and bulk ductile iron samples. It can be found that the PVD-bronze coating exhibited better wear resistance than the other two samples. This enhanced wear resistance was attributed to the unique composite microstructure and desired mechanical strength, which could resist to mechanical shear and spallation, decreasing friction loss. The appropriate hardness of (1.33 ± 0.07) GPa could be beneficial for enhancing its wear resistance. The PVD-bronze coating possessed a much lower and stable coefficient of friction (about 0.1) and wear rate (about 6 μm3·N−1·m−1) under the loading forces of about 100 N after 20 min. The wear mechanism was the abrasive wear.

In distributed optimization theory, network topology graphs are important in communications among multiple agents. However, distributed optimization approaches cannot solve optimization problems well if the graphs are infeasible or tampered. To this end, this paper develops two types of modified graph systems for modifying or recovering the communication graphs among agents employed in distributed optimization. Two optimization problems for obtaining feasible graphs are formulated. Based on the two optimization problems, two modified graph systems are derived accordingly and their convergence to the optimal solution is proven. Via a coordination mechanism consisting of a distributed optimization approach and a modified graph system, we can modify an infeasible communication graph into a feasible one or recover a tampered graph, and the distributed optimization approach can resume its solver capability with the modified graphs. Several examples are provided to demonstrate the efficiency of the main results.

Hydraulic piston pump has the advantages of high efficiency and low-pressure pulsation and has been widely used in the field of construction and agriculture machinery. However, the oil leakage problem, especially the internal leakage of the piston, seriously affects the efficiency of the pump and causes unstable state and high noise. First of all, to improve the performance of the hydraulic pump, a nonlinear mathematical model of the Reynolds equation and energy equation was established to predict the oil film thickness and pressure distribution. What's more, the influence of multiple parameters such as pressure, temperature, swash plate angle, leakage clearance, and the length of leakage flow path on the internal leakage of the piston–cylinder interface was explored. Last but not the least, a test rig was built to measure the corresponding values and to evaluate the effectiveness of the mathematic model. Simulations and experiments consider the variables such as pressure, temperature, and swash plate angle. Both results show that the nonlinear mathematical model could predict the piston pair leakage accurately, so it could be an effective way to improve the design of the piston–cylinder surface structure, gaining higher efficiency.

•Thermodynamics of modular nuclear plant with helium reactor and vertical gas turbine was studied.•Two modes of the nuclear plant operation were analyzed.•High efficiency of complex Brayton cycle in electricity production mode was confirmed.•Performance of intercooling heat exchanger affects greatly the unit electrical efficiency.•The sensitive analysis was carried out to assess deterioration of GT-MHR-250 performance during operation.

Lithium metal batteries have emerged as a promising candidate for next-generation power systems. However, the high reactivity of lithium metal with liquid electrolytes has resulted in decreased battery safety and stability, which poses a significant challenge. Herein, we present a modified laponite-supported gel polymer electrolyte (LAP@PDOL GPE) that was fabricated using in situ polymerization initiated by a redox-initiating system at ambient temperature. The LAP@PDOL GPE effectively facilitates the dissociation of lithium salts via electrostatic interaction and simultaneously constructs multiple lithium-ion transport channels within the gel polymer network. This hierarchical GPE demonstrates a remarkable ionic conductivity of 5.16 × 10–4S cm–1at 30 °C. Furthermore, the robust laponite component of the LAP@PDOL GPE forms a barrier against Li dendrite growth while also participating in the establishment of a stable electrode/electrolyte interface with Si-rich components. The in situ polymerization process further improves the interfacial contact, enabling the LiFePO4/LAP@PDOL GPE/Li cell to exhibit an impressive capacity of 137 mAh g–1at 1C, with a capacity retention of 98.5% even after 400 cycles. In summary, the developed LAP@PDOL GPE shows great potential in addressing the critical issues of safety and stability associated with lithium metal batteries while also delivering improved electrochemical performance.

The problem of sliding mode fault-tolerant control (SMFTC) for T–S fuzzy systems is addressed in this paper. The case that the fuzzy system has different input matrices, and the input uncertainties is considered, which is more universal than the existing results. A sliding mode based observer is constructed to estimate the system states. Then, fuzzy linear sliding surfaces are constructed for the error system and the observer, and the restricted condition that all the input matrices are common existing in many results is removed. In the sequel, a singular system approach (SSA) is developed to deal with the input uncertainties. Meanwhile, an adaptive sliding mode fault-tolerant controller is constructed, which can completely compensate the effects of the fault and stabilize the fault system. Finally, the theoretical method is verified by simulation studies.

In this paper, a robust nonlinear tracking control design for an ionic polymer metal composite (IPMC) with uncertainties is proposed by using neural network-based sliding mode approach. The IPMC, also called artificial muscle, is a novel smart polymer material, and many potential applications for low mass high displacement actuators in biomedical and robotic systems have been shown. In general, the IPMC has highly nonlinear property, and there exist uncertainties caused by identifying some physical parameters and approximate calculation in dynamic model. Moreover, the control input is subject to some constraints to ensure safety and longer service life of IPMC. As a result, for a nonlinear dynamic model with uncertainties and input constraints, an IPMC artificial muscles position tracking control system based on sliding mode control approach is presented, where, the improved exponential reaching law is used to design sliding mode controller, a saturation function is used in the sliding mode control law design to suppress chattering. The robust stability can be guaranteed. Moreover, in order to improve tracking performance, a quickly and precisely robust tracking system to the stabilised system is designed and the parameters of tracking controller are optimised by using neural network. Finally, the effectiveness of the proposed method is confirmed by simulation results.

Temporomandibular joint osteoarthritis (TMJOA) is a gradual degenerative jaw joint condition. Until recent years, TMJOA is still relatively unrecognized and ineffective to be treated. Appropriate animal models with reliable detection methods can help researchers understand the pathophysiology of TMJOA and find therapeutic options. In this study, we summarized common animal models of TMJOA created by chemical, surgical, mechanical, and genetical approaches. The relevant pathological symptoms and induction mechanisms were outlined. In addition, different pathological indicators, furthermore, emerging therapeutic regimens, such as intra-articular drug delivery and tissue engineering-based approaches to treat TMJOA based on these animal models, were summarized and updated. Understanding the physiology and pathogenesis of the TMJOA, together using various ways to diagnose the TMJOA, were elaborated, including imaging techniques, molecular techniques for detecting inflammatory cytokines, histochemical staining, and histomorphometry measures. A more reliable diagnosis will enable the development of new prevention and more effective treatment strategies and thereby improve the quality of life of TMJOA patients.Impact statementTemporomandibular joint osteoarthritis (TMJOA) affects 8 to 16 percent of the population worldwide. However, TMJOA is still relatively unrecognized and ineffective to be treated in the clinic. Appropriate animal models with reliable diagnostic methods can help researchers understand the pathophysiology of TMJOA and find therapeutic options. We herein summarized common animal models of TMJOA and various ways to diagnose the TMJOA. More importantly, emerging therapeutic regimens to treat TMJOA based on these animal models were summarized. With the aid of strategies listed, more effective treatment strategies will be developed and thereby improve the life quality of TMJOA patients.

Abstract: Intramolecular N-H…X (X = F, Cl, Br, and I) hydrogen bonding patterns of aromatic amides in the solid state are summarized. It is revealed that the key for the formation of this kind of weak intramolecular hydrogen bonding in X-ray crystal structures is to suppress the competition of strong intermolecular N-H…O-C hydrogen bonding of the amide unit. For amides with identical backbones, the bonding capacity of halogen atoms as hydrogen bonding acceptors is in the order of F>Cl>Br>I, which is in accordance with their electronegativity strength. Generally, the five-membered hydrogen bonding is easier to form than the six-membered one.

A full flight envelope turbofan aero-engine control is developed by H

A full flight envelope turbofan aero-engine control is developed by H ∞ loop-shaping control concept in this paper. First, H∞ loop-shaping control concept which is carried out in frequency domain is introduced and used to aero-engine control design. In order to meet the maximum robustness, multi-objective genetic algorithm is proposed creatively to obtain the global optimum loop-shaping weights. Second, considering the finite robustness of H ∞ loop-shaping controller while implementing the task of flight envelope turbofan engine control, the full flight envelope is divided to eight sub-regions and gain-scheduled control system where the sub-region controller could be switched with the change of the engine Mach number and altitude is constructed as the original work. The simulation results show the ability of the proposed control system in tracking the flight command, it is also verified that switching process has only slight effects on the engine condition under the control of the designed flight envelope controller.