In this paper, a combination of feedback linearization and disturbance observer-based control (DOBC) is adopted for the design of a state-feedback controller that regulates the velocity and altitude ...of air-breathing hypersonic vehicles (AHVs) subject to constrained inputs. First, a disturbance observer is established to estimate the overall effect of possible uncertainties and disturbances on the nominal vehicle model which is called the lumped disturbance. Then, a compensation method is proposed based on disturbance observer and feedback linearization control to counteract the mismatched lumped disturbance. Furthermore, a novel antiwindup modification is implemented on the baseline control to handle the possible input saturation. The designed controller addresses the issue of stability robustness with respect to system uncertainties and disturbances, and achieves zero-error tracking with good performance and antiwindup property meanwhile, which is the major merit compared with other existing AHV controllers. Finally, simulation is presented to verify the effectiveness of this control scheme.
This paper deals with fault-tolerant output tracking control for the flexible air-breathing hypersonic vehicle (AHV) subject to parametric uncertainties, external disturbances, and actuator ...constraints. By regarding the flexible dynamics as equivalent disturbances, the vehicle model can be split into three functional subsystems, namely, horizontal translation subsystem, vertical translation subsystem, and rotation subsystem. Then, for each subsystem, a disturbance observer is utilized to estimate the lumped effect of model uncertainties, external disturbances, and actuator faults, while a novel auxiliary system combined with the command prefilter is constructed to handle the physical constraints on actuators. Furthermore, sliding mode control is employed to design control commands for the three subsystems, sequentially. The proposed controller modifies the reference trajectories dynamically when one or more actuators become constrained, and can steer the AHV to the desired trim finally. Simulation results are provided to demonstrate the effectiveness of the designed controller.
Rutile, anatase, and brookite TiO2 nanorods (TNs) with specific exposed crystal facets have been obtained by a hydrothermal method using peroxide titanic acid (PTA) solution of different pH values. ...Below pHPTA 10, the condensing complex is uncharged Ti2O5(OH)2(H2O)4 or cations Ti2O5(H2O)6 2+, and the corner-shared bonding easily occurs to form rutile phase. Above pHPTA 10, the condensing species is anions Ti2O5(OH)4(H2O)2 2–, resulting in the larger probability of edge-shared bonding which favor the formation of anatase TiO2. Brookite whose structure contains both corner-shared and edge-shared bonding can be formed when pHPTA equals to 10. Rutile TN synthesized from PTA solution at pH 4 showed the optimal photocatalytic oxidation activity for MB degradation; Brookite TN exhibited the highest photocatalytic activity for reduction of Cr (VI) despite that it does not exhibit the largest surface area. The presence of a spatial separation of redox sites in faceted rutile TiO2 nanorod determined the photocatalytic activity of MB decomposition. Compared with rutile and anatase phase, the optimal photocatalytic reduction activity of brookite TN might be resulting from a cathodic shift of the conduction band.
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Bearings are the most commonly used components in rotating machines and the ability to diagnose their faults and predict their remaining useful life (RUL) is critical for system maintenance. This ...paper proposes a smart system combined with a regression model to predict the RUL of bearings. The method converts the azimuth signal through low-pass filtering (LPF) and a chaotic mapping system, and uses Euclidean feature values (EFVs) to extract features in order to construct useful health indicators (HIs). In fault detection, the iterative cumulative moving average (ICMA) is used to smooth the HIs, and the Euclidean norm is used to find the time-to-start prediction (TSP). In terms of prediction, this paper uses a self-selective regression model to select the most suitable regression model to predict the RUL of the bearing. The dataset provided by the Center for Intelligent Maintenance Systems (IMS) is applied for performance evaluation; in comparison with previous research, better prediction results can be achieved by applying the proposed smart assessment system. The proposed system is also applied to the PRONOSTIA (also called FEMTO-ST) bearing dataset in this paper, demonstrating that acceptable prediction performance can be obtained.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Sagittal alignment determines the extension and flexion of knee prostheses in total knee arthroplasty (TKA). The definition of the sagittal axes may be different between the Mako TKA system (Stryker) ...and the conventional manual intramedullary approach. Whether there is any discrepancy between the 2 approaches has not been well studied.
We retrospectively analyzed 60 full-length computed tomographic (CT) scans of the lower extremities of 54 patients. The femur and tibia were modeled by using Mimics (Materialise). The Mako mechanical axes were determined according to the Mako TKA Surgical Guide. The manual intramedullary axes were determined according to the central axis of the tibial proximal and femoral distal medullary cavities. The femoral, tibial, and combined angular discrepancies were measured in the sagittal plane.
On the femoral side, the Mako mechanical axis was more likely to be located in an extended position relative to the manual intramedullary axis (56 of 60 knees). The median angular discrepancy was 2.46° (interquartile range IQR, 1.56° to 3.43° range, -1.06° to 5.24°). On the tibial side, the Mako mechanical axis was likely to be located in a flexed position relative to the manual intramedullary axis (57 of 60 knees). The median angular discrepancy was 2.40° (IQR, 1.87° to 2.84° range, -0.79° to 4.20°). The angular discrepancy of the femoral-tibial sagittal angle was 4.63° (IQR, 3.71° to 5.64° range, 1.20° to 9.02°).
Compared with manual TKA, the Mako system is more likely to result in a decreased posterior tibial slope and extension of the femoral prosthesis. It may also influence the evaluation of lower-extremity extension and flexion. When using the Mako system, special attention should be given to these discrepancies.
Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.
The innate immune system provides a defense against invading pathogens by inducing various interferon (IFN)-stimulated genes (ISGs). We recently reported that tripartite motif protein 25 (TRIM25), an ...important ISG, was highly upregulated in duck embryo hepatocyte cells (DEFs) after infection with duck viral hepatitis A virus type 1 (DHAV-1). However, the mechanism of upregulation of TRIM25 remains unknown. Here we reported that interleukin-22 (IL-22), whose expression was highly facilitated in DEFs and various organs of 1-day-old ducklings after DHAV-1 infection, highly enhanced the IFN-λ-induced production of TRIM25. The treatment with IL-22 neutralizing antibody or the overexpression of IL-22 highly suppressed or facilitated TRIM25 expression, respectively. The phosphorylation of signal transducer and activator of transcription 3 (STAT3) was crucial for the process of IL-22 enhancing IFN-λ-induced TRIM25 production, which was suppressed by WP1066, a novel inhibitor of STAT3 phosphorylation. The overexpression of TRIM25 in DEFs resulted in a high production of IFNs and reduced DHAV-1 replication, whereas the attenuated expression of IFNs and facilitated replication of DHAV-1 were observed in the RNAi group, implying that TRIM25 defended the organism against DHAV-1 propagation by inducing the production of IFNs. In summary, we reported that IL-22 activated the phosphorylation of STAT3 to enhance the IFN-λ-mediated TRIM25 expression and provide a defense against DHAV-1 by inducing IFN production.
Age‐related cognitive decline in neurodegenerative diseases, such as Alzheimer's disease (AD), is associated with the deficits of synaptic plasticity. Therefore, exploring promising targets to ...enhance synaptic plasticity in neurodegenerative disorders is crucial. It has been demonstrated that methyl‐CpG binding protein 2 (MeCP2) plays a vital role in neuronal development and MeCP2 malfunction causes various neurodevelopmental disorders. However, the role of MeCP2 in neurodegenerative diseases has been less reported. In the study, we found that MeCP2 expression in the hippocampus was reduced in the hippocampus of senescence‐accelerated mice P8 (SAMP8) mice. Overexpression of hippocampal MeCP2 could elevate synaptic plasticity and cognitive function in SAMP8 mice, while knockdown of MeCP2 impaired synaptic plasticity and cognitive function in senescence accelerated‐resistant 1 (SAMR1) mice. MeCP2‐mediated regulation of synaptic plasticity may be associated with CREB1 pathway. These results suggest that MeCP2 plays a vital role in age‐related cognitive decline by regulating synaptic plasticity and indicate that MeCP2 may be promising targets for the treatment of age‐related cognitive decline in neurodegenerative diseases.
Decreased hippocampal MeCP2 expression contributes to age‐related cognitive decline by impairing synaptic plasticity. Upregulation of hippocampal MeCP2 could prevent age‐related decline in cognitive function and synaptic plasticity. MeCP2‐mediated regulation of synaptic plasticity may be associated with CREB1 pathway.
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Water scarcity is a critical issue in desert and arid regions, and atmospheric water harvesting is a potential solution. The challenge is lacking ideal adsorbents that can efficiently capture water ...from low-humidity air and be regenerated readily. Herein, we report a hydrolytically stable metal–organic framework (MOF), Cu2(AD)2(SA) (Cu-AD-SA), with excellent performance in water harvesting. More importantly, this material can be facilely prepared from two easily accessible ligands adenine (HAD) and succinic acid (H2SA). Cu-AD-SA has a three-dimensional (3D) framework structure with the crs topology and intersecting channels of ∼5 Å in diameter. The channel surface is decorated by uncoordinated aromatic N atoms, amine groups, and alkyl moieties. Interestingly, Cu-AD-SA shows a high water adsorption capacity of 0.16 g g–1 at low pressure of 0.2 P/P 0 and 25 °C. Furthermore, dynamic water adsorption–desorption cycling experiments demonstrated a stable working capacity of 0.13 g g–1 for uptaking water from a low-humidity air (water partial pressure: 0.85 kPa, 20% RH at 30 °C, 5.3% RH at 55 °C) at 30 °C and desorption at 55 °C. The water adsorption mechanism was also studied by analyzing its single-crystal structure after water loading. The results indicated the existence of strong H-bonding interactions between water molecules and uncoordinated N atoms and amine groups on the framework, which should play an important role in the high adsorption at low pressure. All the above features suggest great potential of Cu-AD-SA for water harvesting in arid regions.
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