In the current global scenario of extreme competition, factors such as productivity, availability, quality and cost of operations play a vital role in the success of a company. A critical component ...relating to all of the above is maintenance. The conventional maintenance decision support systems have primarily focused on maximising the gains of a single machine system. However, a real life application usually consists of multiple machines, and the operational level decisions are more complex. In this paper, an on line plant-level maintenance decision support system (PMDSS) is developed by combining the short term and long term decision making process to improve the overall system performance while continuously attempting to maximise immediate profits in the short term. The PMDSS works towards two basic aims: (1) unplanned downtime reduction by predicting the remaining useful life of the machines, and (2) efficient utilisation of the finite maintenance and production resources through identifying the throughput-critical machines. The benefits of this approach are presented by considering an industrial case study of an automotive assembly line. The results obtained using this PMDSS approach shows a big throughput improvement as compared to the conventional maintenance policies.
The electronic and magnetic properties of X-C2N (X=F, Cl, Br and I) monolayers have been systematically investigated from first-principles calculations. The F atom can be strongly adsorbed on the top ...of the host carbon atoms, while the Cl, Br and I atoms favor the top of the host nitrogen atoms of C2N monolayers. These functionalized X-C2N (X=F, Cl, Br and I) monolayers exhibit interesting electronic and magnetic features. The F-C2N monolayer system shows a nonmagnetic metallic state, while the X-C2N (X=Cl, Br and I) monolayer systems exhibit the magnetic semiconducting ground state. Moreover, the ferromagnetic state is energetically more stable configuration for the X-C2N (X=Cl, Br and I) monolayer systems. Magnetic analysis further elaborates that the induced magnetism in the X-C2N (X=Cl, Br and I) monolayer systems mainly arises from the local magnetic moments of the halogen adatoms. Thus, the chemical functionalization of nitrogenated honey graphene through halogen atoms adsorption has promising applications in electronic devices.
Summary
1. Renal tubular epithelial cells can undergo epithelial to mesenchymal transition (EMT) under hyperglycaemic conditions, which is associated with renal interstitial fibrosis. Activation of ...the renin–angiotensin system (RAS) is involved in diabetic nephropathy. The present study investigated the positive role of angiotensin AT1 receptors in high glucose‐induced EMT in cultured tubular epithelial cells.
2. A rat kidney proximal tubular epithelial cell line (NRK‐52E) was used in the present study. Levels of EMT makers, namely E‐cadherin and vimentin, were estimated using fluorescence immunocytochemistry, mRNA levels of angiotensinogen (AGT), angiotensin‐converting enzyme (ACE) and AT1 receptors were determined by real‐time polymerase chain reaction, protein levels of E‐cadherin, vimentin, fibronectin, matrix metallopeptidase (MMP)‐9 and phosphorylated extracellular signal‐regulated kinase (ERK) 1/2 were analysed by western blotting and the concentrations of angiotensin (Ang) II and transforming growth factor (TGF)‐β1 in the culture medium were determined by enzyme immunoassay and ELISA.
3. High glucose (30 mmol/L) induced EMT and increased the synthesis of fibronectin and MMP‐9. Furthermore, high glucose increased AGT, ACE and AT1 receptor mRNA levels, as well as AngII and TGF‐β1 concentrations in the culture medium and ERK1/2 phosphorylation. Pretreatment of cells for 15 min with the AT1 receptor antagonist losartan (10−5 mol/L) attenuated high glucose‐induced increases in TGF‐β1 and ERK1/2 phosphorylation and reduced EMT, as well as the consequent synthesis of fibronectin and MMP‐9.
4. The results of the present study suggest that the activated local RAS mediates high glucose‐induced EMT. By activating AT1 receptors and stimulating TGF‐β1 synthesis, the elevated local RAS participates in high glucose‐induced EMT and increased extracellular matrix secretion.
A new finite-time sliding mode control approach is presented for synchronizing two different topological structure chaotic systems. With the help of the Lyapunov method, the convergence property of ...the proposed control strategy is discussed in a rigorous manner. Furthermore, it is mathematically proved that our control strategy has a faster convergence speed than the conventional finite-time sliding mode control scheme. In addition, the proposed control strategy can ensure the finite-time synchronization between the master and the slave chaotic systems under internal uncertainties and external disturbances. Simulation results are provided to show the speediness and robustness of the proposed scheme. It is worth noticing that the proposed control scheme is applicable for secure communications.
A series of yttrium-doped CdO (CYO) thin films have been grown on both amorphous glass and single-crystal MgO(100) substrates at 410 °C by metal−organic chemical vapor deposition (MOCVD), and their ...phase structure, microstructure, electrical, and optical properties have been investigated. XRD data reveal that all as-deposited CYO thin films are phase-pure and polycrystalline, with features assignable to a cubic CdO-type crystal structure. Epitaxial films grown on single-crystal MgO(100) exhibit biaxial, highly textured microstructures. These as-deposited CYO thin films exhibit excellent optical transparency, with an average transmittance of >80% in the visible range. Y doping widens the optical band gap from 2.86 to 3.27 eV via a Burstein−Moss shift. Room temperature thin film conductivities of 8540 and 17 800 S/cm on glass and MgO(100), respectively, are obtained at an optimum Y doping level of 1.2−1.3%. Finally, electronic band structure calculations are carried out to systematically compare the structural, electronic, and optical properties of the In-, Sc-, and Y-doped CdO systems. Both experimental and theoretical results reveal that dopant ionic radius and electronic structure have a significant influence on the CdO-based TCO crystal and band structure: (1) lattice parameters contract as a function of dopant ionic radii in the order Y (1.09 Å) < In (0.94 Å) < Sc (0.89 Å); (2) the carrier mobilities and doping efficiencies decrease in the order In > Y > Sc; (3) the dopant d state has substantial influence on the position and width of the s-based conduction band, which ultimately determines the intrinsic charge transport characteristics.
The importance of maintenance optimization has been recognized over the past decades and is highly emphasized by today's competitive economy. In this paper, an updated sequential predictive ...maintenance (USPM) policy is proposed to decide a real-time preventive maintenance (PM) schedule for a continuously monitored degrading system that will minimize maintenance cost rate (MCR) in the long term, by considering the effect of imperfect PM. The USPM model is continuously updated based on the change in the system state to decide an optimal PM schedule. Mathematical analysis of the proposed USPM model demonstrates the existence and uniqueness of an optimal PM schedule under practical conditions. The results validate that: 1) the proposed USPM model yields PM schedules that are consistent with the change in the system states and 2) the USPM model is able to quickly react to drastic degradation of the system and provide an optimal PM schedule in real time. The proposed maintenance policy can provide significant benefits for real-time maintenance decision making.
A systematic model adaptation methodology is developed in order to continuously update the thermal-error model under varying manufacturing conditions. Process-intermittent probing and adaptive system ...identification techniques are integrated to monitor and estimate machine-tool thermal errors and recursively modify model coefficients as manufacturing process proceeds. The recursive model adaptation, which is based on the Kalman filter parameter estimation technique and multiple-sampling horizons, minimizes intrusion to production while maintaining good model adaptation capability. The experimental results proved that the proposed methodology has good model accuracy and robustness to frequently changing working conditions.
Research into 4D printing has attracted unprecedented interest since 2013 when the idea was first introduced. It is based on 3D printing technology, but requires additional stimulus and ...stimulus-responsive materials. Based on certain interaction mechanisms between the stimulus and smart materials, as well as appropriate design of multi-material structures from mathematical modeling, 4D printed structures evolve as a function of time and exhibit intelligent behavior. Unlike 3D printing, 4D printing is time-dependent, printer-independent, predictable, and targets shape/property/functionality evolution. This allows for self-assembly, multi-functionality, and self-repair. This paper presents a comprehensive review of the 4D printing process and summarizes the practical concepts and related tools that have a prominent role in this field. Unsought aspects of 4D printing are also studied and organized for future research.
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•The 4D printing process is thoroughly reviewed and discussed.•Various types of shape-shifting behaviors and mechanisms in the 4D printed structures are presented.•Different approaches for mathematic modeling of the 4D printing path and material structures are discussed.•Potential applications and topics for future studies of the 4D printing process are suggested.
Lipohyalinosis or atherosclerosis might be responsible for single subcortical infarctions (SSIs); however, ways of differentiating between the two clinically remain uncertain. We aimed to investigate ...whether consecutive slides on axial view or transversal diameter is more effective to differentiate mechanisms by comparing their relationships with white matter hyperintensities (WMHs).
All the participants from the Standard Medical Management in Secondary Prevention of Ischemic stroke in China (SMART) cohort who had SSIs in the lenticulostriate artery territory were included and categorized according to consecutive slides on axial view (≥4 consecutive slices or not) and transversal diameter (≥15 mm or not). The associations between the severity of WMHs and the different categories were analyzed.
Among the 3,821 patients of the SMART study, 281 had diffusion-weighted image-proven SSIs in the lenticulostriate artery territory. When classified by consecutive slides on axial view, SSIs on ≥4 slices were significantly associated with the severity of the WMHs, both in deep WMH (DWMH) (odds ratio OR, 0.32; 95% confidence interval CI, 0.11-0.97;
= 0.04) and periventricular hyperintensity (PVH) (OR, 0.37; 95% CI, 0.17-0.78;
= 0.01). No such association was found on the basis of the transversal diameter (
> 0.1).
Consecutive slides on axial view (≥4 consecutive slices) might be more effective than transversal diameter to identify the atherosclerotic mechanisms of SSIs in the lenticulostriate artery territory.
http://www.clinicaltrials.gov. Unique identifier: NCT00664846.
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