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  • 1
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    Fault Tolerant Control for Uncertain Time-Delay Systems with a Trajectory Tracking Approach (2015)
    Hindawi
    Details
    Publication Date: 2015-05-21
    Description: This paper studies the problem of fault tolerant control by trajectory tracking for a class of linear constant time-delay systems. The aim is to design a control law by considering the fault detected by the observer to make the faulty system track the reference model even if faults occur. By considering two kinds of actuator faults, one constant and another time-varying, the corresponding proportional integral observers and active FTC control laws are designed, respectively. State tracking error, state estimation error, output estimation error, and fault estimation error are combined into a descriptor system. Based on Lyapunov-Krasovskii functional approach stability problems of the descriptor system are easily solved in terms of the Linear Matrix Inequalities (LMI). Finally, a numerical example is considered to prove the effectiveness in both cases.
    Print ISSN: 1024-123X
    Electronic ISSN: 1563-5147
    Topics: Mathematics , Technology
    Published by Hindawi
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  • 2
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    Optimization of Ionic Liquid Based Simultaneous Ultrasonic- and Microwave-Assisted Extraction of Rutin and Quercetin from Leaves of Velvetleaf (Abutilon theophrasti) by Response Surface Methodology (2014)
    Hindawi
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    Publication Date: 2014-08-28
    Description: An ionic liquids based simultaneous ultrasonic and microwave assisted extraction (ILs-UMAE) method has been proposed for the extraction of rutin (RU), quercetin (QU), from velvetleaf leaves. The influential parameters of the ILs-UMAE were optimized by the single factor and the central composite design (CCD) experiments. A 2.00 M 1-butyl-3-methylimidazolium bromide ([C4mim]Br) was used as the experimental ionic liquid, extraction temperature 60°C, extraction time 12 min, liquid-solid ratio 32 mL/g, microwave power of 534 W, and a fixed ultrasonic power of 50 W. Compared to conventional heating reflux extraction (HRE), the RU and QU extraction yields obtained by ILs-UMAE were, respectively, 5.49 mg/g and 0.27 mg/g, which increased, respectively, 2.01-fold and 2.34-fold with the recoveries that were in the range of 97.62–102.36% for RU and 97.33–102.21% for QU with RSDs lower than 3.2% under the optimized UMAE conditions. In addition, the shorter extraction time was used in ILs-UMAE, compared with HRE. Therefore, ILs-UMAE was a rapid and an efficient method for the extraction of RU and QU from the leaves of velvetleaf.
    Electronic ISSN: 1537-744X
    Topics: Natural Sciences in General
    Published by Hindawi
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  • 3
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    Intelligent Deep Adversarial Network Fault Diagnosis Method Using Semisupervised Learning (2020)
    Hindawi
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    Publication Date: 2020-05-22
    Description: In recent years, deep learning has become a popular issue in the intelligent fault diagnosis of industrial equipment. Under practical working conditions, although the collected vibration data are of large capacity, most of the vibration data are not labeled. Collecting and labeling sufficient fault data for each condition are unrealistic. Therefore, constructing a reliable fault diagnosis model with a small amount of labeled vibration data is a significant problem. In this paper, the vibration time-domain signal of the fault bearing is transformed into a 2-dimensional image by wavelet transform to obtain the time-frequency domain information of the original data. A deep adversarial convolutional neural network based on semisupervised learning is proposed. A large amount of fake data generated by the generator and unlabeled true vibration data are used in the discriminator to learn the overall distribution of data by judging the authenticity of the input. Three regular terms for different loss functions are designed to constrain the parameters of the discriminator to improve the learning ability of the model. The proposed method is validated by two bearing fault diagnosis cases. The experiment results show that the proposed method has higher diagnostic accuracy than traditional deep models on multigroup small datasets of different capacities. The proposed method provides a new solution to the fault diagnosis problem with large vibration data but few labels.
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    Electronic ISSN: 1563-5147
    Topics: Mathematics , Technology
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  • 4
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    Circulating Sestrin Levels Are Increased in Hypertension Patients (2020)
    Hindawi
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    Publication Date: 2020-06-13
    Description: Background. Sestrins (Sesns), a group of oxidative stress-related proteins, have been reported to be involved in various cardiovascular diseases, including aortic dissection and chronic heart failure. This study is aimed at investigating the level of circulating Sesn1, Sesn2, and Sesn3 in hypertension patients. Methods. Plasma levels of Sesn1, Sesn2, and Sesn3 in 400 hypertensive patients and 100 normotensive subjects were detected using enzyme-linked immunosorbent assay (ELISA) kits. The hypertension patients were divided into groups with grade I (n=140), grade II (n=180), and grade III (n=80) hypertension. Results. Compared with the normotensive subjects, Sesn1, Sesn2, and Sesn3 levels were increased in patients with hypertension, with a gradual increase between the groups with grade I, grade II, and grade III hypertension. Elevated Sesn1, Sesn2, and Sesn3 levels were positively correlated with both the systolic blood pressure (SBP) and diastolic blood pressure (DBP). Moreover, Sesn1, Sesn2, and Sesn3 levels were elevated in patients with dipper hypertension and further increased in patients with nondipper hypertension. In addition, smokers, as well as patients with higher levels of angiotensin II (Ang II) and carotid atherosclerotic plaque (CAP), exhibited increased Sesn1, Sesn2, and Sesn3 levels when compared with patients without these clinical characteristics. Furthermore, plasma levels of Sesn1, Sesn2, and Sesn3 were negatively correlated with the presence of CAP. Conclusions. Circulating Sesn levels are increased in patients with hypertension and may be a target for the prevention and treatment of clinical hypertension.
    Print ISSN: 0278-0240
    Electronic ISSN: 1875-8630
    Topics: Biology , Chemistry and Pharmacology
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  • 5
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    Investor Sentiment in an Artificial Limit Order Market (2020)
    Hindawi
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    Publication Date: 2020-06-30
    Description: This paper examines the under/overreaction effect driven by sentiment belief in an artificial limit order market when agents are risk averse and arrive in the market with different time horizons. We employ agent-based modeling to build up an artificial stock market with order book and model a type of sentiment belief display over/underreaction by following a Bayesian learning scheme with a Markov regime switching between conservative bias and representative bias. Simulations show that when compared with classic noise belief without learning, sentiment belief gives rise to short-term intraday return predictability. In particular, under/overreaction trading strategies are profitable under sentiment beliefs, but not under noise belief. Moreover, we find that sentiment belief leads to significantly lower volatility, lower bid-ask spread, and larger order book depth near the best quotes but lower trading volume when compared with noise belief.
    Print ISSN: 1076-2787
    Electronic ISSN: 1099-0526
    Topics: Computer Science , Mathematics
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  • 6
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    Research on Key Technologies of Floor Heave Control in Soft Rock Roadway (2020)
    Hindawi
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    Publication Date: 2020-09-03
    Description: Aiming at the floor heave of transportation concentrated roadway on the West Wing (TCRWW) of No. 1 Coal Seam in Danhou Mine, it affects underground coal transportation and mine safety production. First, the lithology and structure of the roadway floor were sampled and tested, and it was found that it contained clay minerals with high hydrophilicity. Secondly, starting from the mechanical mechanism of the roadway floor, a mechanical model of the roadway floor is established. By increasing the floor anchoring layer thickness m1, the floor deformation can be effectively controlled to guarantee the stability of the surrounding rock of the roadway. Thirdly, the FLAC3D numerical simulation analysis of the roadway deformation under the existing support scheme of the roadway is consistent with the measured deformation results on-site, thereby revealing that the existing support scheme and parameters are not reasonable. Finally, the unreasonable support scheme and parameters of the existing roadway were disclosed, and an antifloor arch structure was proposed: “quicklime bottom paving + prestressed anchor cable + concrete arc beam + metal mesh + C20 high-strength concrete filling.” This floor treatment plan is adopted for the industrial verification of the test section of TCRWW. Engineering practice shows that the optimized roadway support scheme has a better effect on the deformation control of the roof-to-floor and rib-to-rib, thereby effectively ensuring safe and efficient production in the mine.
    Print ISSN: 1687-8086
    Electronic ISSN: 1687-8094
    Topics: Architecture, Civil Engineering, Surveying
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  • 7
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    Spatiotemporal Characteristics of Winter Wheat Waterlogging in the Middle and Lower Reaches of the Yangtze River, China (2018)
    Hindawi
    Details
    Publication Date: 2018-01-01
    Description: The waterlogging is a serious agrometeorological disaster caused by excessive soil water during crop growth stages. The middle and lower reaches of the Yangtze River are one of the major winter wheat growing regions in China and at the same time they are waterlogging-prone due to their specific climatic conditions. In this study, we integrated a set of tools to analyze the spatiotemporal features of winter wheat waterlogging in this region. We proposed a waterlogging precipitation index (WPI) based on winter wheat yield loss rate and precipitation anomaly percentage and analyzed the frequency, scope, and intensity of winter wheat waterlogging. The results showed that the spring rainfall had a direct and significant effect on winter wheat yield, and the meteorological yield of winter wheat was negatively correlated with precipitation abnormal event from jointing to maturity stages (March to May) across the whole study area. The matching between the waterlogging severity identified by the WPI and historical winter wheat waterlogging records was relatively high. We also discussed the influences of the other nonmeteorological factors, for example, soil texture, topographic and geomorphic conditions, and local disaster-resisting ability, on the extent of waterlogging damage.
    Print ISSN: 1687-9309
    Electronic ISSN: 1687-9317
    Topics: Geosciences , Physics
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  • 8
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    Contractual Efficiency of PPP Infrastructure Projects: An Incomplete Contract Model (2018)
    Hindawi
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    Publication Date: 2018-01-01
    Description: This study analyses the contractual efficiency of public-private partnership (PPP) infrastructure projects, with a focus on two financial aspects: the nonrecourse principal and incompleteness of debt contracts. The nonrecourse principal releases the sponsoring companies from the debt contract when the special purpose vehicle (SPV) established by the sponsoring companies falls into default. Consequently, all obligations under the debt contract are limited to the liability of the SPV following its default. Because the debt contract is incomplete, a renegotiation of an additional loan between the bank and the SPV might occur to enable project continuation or liquidation, which in turn influences the SPV’s ex ante strategies (moral hazard). Considering these two financial features of PPP infrastructure projects, this study develops an incomplete contract model to investigate how the renegotiation triggers ex ante moral hazard and ex post inefficient liquidation. We derive equilibrium strategies under service fees endogenously determined via bidding and examine the effect of equilibrium strategies on contractual efficiency. Finally, we propose an optimal combination of a performance guarantee, the government’s termination right, and a service fee to improve the contractual efficiency of PPP infrastructure projects.
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    Topics: Mathematics , Technology
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  • 9
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    Research on Overflow Monitoring Mechanism Based on Downhole Microflow Detection (2014)
    Hindawi
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    Publication Date: 2014-01-01
    Description: The flow rate variation of the drilling fluid and micro-overflow loss is difficult to analyze. The purpose to prevent the occurrence of kick, lost circulation, and other complex conditions is not easy to be achieved. Therefore, the microflow-induced annulus multiphase flow rate and annulus pressure field model were studied, and a downhole microflow measurement system has been developed. A differential pressure type flow measurement was used in the system, and real-time downhole information was obtained to achieve deep, narrow windows and other safety-density complex formation security. This paper introduced a new bottom-hole flow meter which can measure the annular flux while drilling and monitor overflow and circulation loss. The accuracy and reliability of the MPD (managed pressure drilling) system can be improved obviously by applying the device; as a result, the safety of drilling is enhanced and the cost is reduced.
    Print ISSN: 1024-123X
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    Topics: Mathematics , Technology
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  • 10
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    On a Subclass of Meromorphic Close-to-Convex Functions (2014)
    Hindawi
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    Publication Date: 2014-01-01
    Description: The main purpose of this paper is to introduce and investigate a certain subclass of meromorphic close-to-convex functions. Such results as coefficient inequalities, convolution property, inclusion relationship, distortion property, and radius of meromorphic convexity are derived.
    Print ISSN: 2356-6140
    Electronic ISSN: 1537-744X
    Topics: Natural Sciences in General
    Published by Hindawi
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