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101.
In this paper, the problem of configuration selection, i.e. sensor/actuator placement for piecewise affine (PWA) systems subject to both sensor and actuator faults is considered. A method is proposed that provides a tool for the design phase to decide about the optimal placement of sensor/actuators where the reconfigurability of the system subject to sensor and actuator faults is also taken into account. Using a lattice of possible configurations (sensor/actuator placements), the reconfigurability of the system subject to faults for each configuration is evaluated and based on that one can draw conclusions about the reconfigurability of the system and the optimal configuration in the architecture design phase. A reconfigurable control must ensure stability of the reconfigured system and, if possible, a graceful degradation in the performance. Therefore, in the proposed reconfigurability analysis, we consider both stabilisability and performance of the system. The efficiency of the proposed method is demonstrated in several numerical examples. 相似文献
102.
Christopher Skea Alireza Rezagholilou Pouria Behnoud Far Raoof Gholami Mohammad Sarmadivleh 《岩石力学与岩土工程学报(英文版)》2018,10(5):865-878
There have been interests to link different cuttings/cavings to various wellbore failure types during drilling. This concept is essential when caliper and image logs are not available. Identification of wellbore failure during drilling gives more chance of immediate actions before wireline logging program. In this paper, an approach was presented based on the image processing of ditch cuttings. This approach uses the sphericity and roundness of cuttings as input data to classify caving types and subsequently determine the dominant failure type. Likewise, common definitions of cavings were discussed initially before a new criterion is suggested. This quantitative criterion was examined by observations from caliper and acoustic image logs as well. The proposed approach and criterion were implemented on ditch cuttings taken from a well in Western Australia. Results indicate that the primary failure is shear failure (breakout) due to high levels of angular cavings. However, another failure due to the fluid invasion into pre-existing fractures was also recorded by blocky cavings. 相似文献
103.
Oliver Schulte Mahmoud Khademi Sajjad Gholami Zeyu Zhao Mehrsan Javan Philippe Desaulniers 《Data mining and knowledge discovery》2017,31(6):1735-1757
We apply the Markov Game formalism to develop a context-aware approach to valuing player actions, locations, and team performance in ice hockey. The Markov Game formalism uses machine learning and AI techniques to incorporate context and look-ahead. Dynamic programming is applied to learn value functions that quantify the impact of actions on goal scoring. Learning is based on a massive new dataset, from SportLogiq, that contains over 1.3M events in the National Hockey League. The SportLogiq data include the location of an action, which has previously been unavailable in hockey analytics. We give examples showing how the model assigns context and location aware values to a large set of 13 action types. Team performance can be assessed as the aggregate value of actions performed by the team’s players, or the aggregate value of states reached by the team. Model validation shows that the total team action and state value both provide a strong indicator predictor of team success, as measured by the team’s average goal ratio. 相似文献
104.
Sanaz Jarolmasjed Carlos Zúñiga Espinoza Sindhuja Sankaran 《Sensing and Instrumentation for Food Quality and Safety》2017,11(3):987-993
Bitter pit is a physiological disorder in apples. Several major apple varieties are susceptible to this disorder that poses a great challenge to growers and the associated industry as it significantly reduces the produce utilization value and marketability. The current method of bitter pit detection is through visual assessment of symptoms. Near infrared (NIR) spectroscopy is a non-invasive technique that can be utilized towards detecting bitter pit development in fruits in pre-/non-symptomatic stages. Therefore, NIR spectra (935–2500 nm) of apples were collected from healthy and bitter pit Honeycrisp, Golden Delicious, and Granny Smith apples from a commercial orchard. The apples were stored in a controlled environment and spectral reflectance data were acquired at days 0, 7, 14, 35, and 63 after harvest. Chemical analysis was performed at the end of the storage period to estimate calcium, magnesium, and potassium content in the fruit peel. Partial least square regression (PLSR) was used to identify the apples as healthy or bitter pit using NIR-based spectral features. In addition, specific spectral features were selected by implementing two feature extraction methods: PLSR and stepwise discriminant analysis (SDA) on day 63 spectral dataset. The PLSR and SDA-based selected features from day 63 in Honeycrisp apples classified the same dataset with classification accuracies of about 100% with both methods. Regression analysis indicated a strong relationship between the PLSR-based spectral features and magnesium-to-calcium ratio in fruit peel in all three (Honeycrisp, Golden Delicious, and Granny Smith) apple varieties. 相似文献
105.
Mansor Bin Ahmad Asma Fatehi Azmi Zakaria Shahrom Mahmud Sanaz A. Mohammadi 《International journal of molecular sciences》2012,13(12):15640-15652
This study focuses on the fabrication and electrical characterization of a polymer composite based on nano-sized varistor powder. The polymer composite was fabricated by the melt-blending method. The developed nano-composite was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FeSEM), and energy-dispersive X-ray spectroscopy (EDAX). The XRD pattern revealed the crystallinity of the composite. The XRD study also showed the presence of secondary phases due to the substitution of zinc by other cations, such as bismuth and manganese. The TEM picture of the sample revealed the distribution of the spherical, nano-sized, filler particles throughout the matrix, which were in the 10–50 nm range with an average of approximately 11 nm. The presence of a bismuth-rich phase and a ZnO matrix phase in the ZnO-based varistor powder was confirmed by FeSEM images and EDX spectra. From the current-voltage curves, the non-linear coefficient of the varistor polymer composite with 70 wt% of nano filler was 3.57, and its electrical resistivity after the onset point was 861 KΩ. The non-linear coefficient was 1.11 in the sample with 100 wt% polymer content. Thus, it was concluded that the composites established a better electrical non-linearity at higher filler amounts due to the nano-metric structure and closer particle linkages. 相似文献
106.
Parisa Zadehnajar Mohammad Hussein Mirmusavi Sanaz Soleymani Eil Bakhtiari Hamid Reza Bakhsheshi-Rad Saeed Karbasi Seeram RamaKrishna Filippo Berto 《International Journal of Applied Ceramic Technology》2021,18(6):1901-1920
Owing to great biocompatibility and high capacity of apatite formation, bioceramics, especially calcium silicate-based compounds, were extensively employed in orthopedic and dental uses concerning biomedical applications. Lately, akermanite (AK; Ca2MgSi2O7), as a bioceramic containing Ca-, Mg- and Si, has gained an increased level of attention because of its more tunable mechanical characteristics and degradation rate. All studies indicate that this magnesium incorporating Ca-silicate ceramic has a great capacity to use as a bone graft material to fulfill the necessity of bone reconstruction. Despite the rising interest in using these materials in biomedical fields, there has not yet been an extensive overview of this bioceramic property and its potential benefits. Thus, it has been speculated that this concept and the emergence of akermanite bioactive ceramics might lead to significant upcoming advancements in the field of bone tissue engineering (BTE). Definitely, the approach still requires additional advances to considerably better respond to the vital concerns regarding the clinical application. The review tackles the present research trends on akermanite ceramics for biomedical purposes such as bone scaffold, coating materials, bone cement, and treatment of osteoporotic bone defects, commencing with recent status and shifting to upcoming developments. 相似文献
107.
In this paper an approximate formulation for torsional analysis of tubes with multi-layered non-circular cross-sections is
presented. A previously presented method based on Bredt’s theory is extended to achieve these formulas. Layers are assumed
to be isotropic and may possess different thicknesses and material properties. The obtained formulas for shear stress and
angle of twist are applicable to thin to moderately thick closed cross-sections. It is shown that depending on the properties
of the layers, maximum shear stress does not necessarily happen on the outer boundary. Furthermore, the effect of different
cross-sectional shapes on torsional response is studied. Using the presented method, one can achieve desirable shear stresses
and angles of twist for a polygonal multi-layered tube with a proper choice of bluntness. The method can be extended for torsion
problem of FGM tubes as well. The presented formulas for torsion problem are relatively accurate and suitable to be implemented
in optimization programs. 相似文献
108.
S. Hassan Firoozifar Sanaz Foroutan Sara Foroutan 《Chemical Engineering Research and Design》2011,89(10):2044-2048
Chemical composition and any variation of four main components of bitumen (asphaltene, saturated, naphthene aromatic and polar aromatic) have effective impact on its properties and especially, thermal properties. In other words, in order to have asphalt pavements with reasonable temperature susceptibility and thermal stability, first of all it is essential to know the effect of these components on bitumen properties. Therefore, in this research these effects were investigated and it was found that penetration index (PI) and penetration viscosity number (PVN) of bitumen were increased with increasing in asphaltene content.Thermal behavior of bitumen in an oxidizing environment was also studied using thermogravimetric analysis (TGA) technique. The results showed that increasing the asphaltene content of bitumen decreases the temperature susceptibility and improves the resistance of samples to thermal decomposition. 相似文献
109.
Mannitol is an important polyol which is being used mainly in the food and pharmaceutical industries. The current techniques for the production of mannitol are reviewed. The present commercial production of d-mannitol takes place by hydrogenation reaction. The low d-mannitol yield, however, asks for the development of alternative procedures. The shortcomings and major drawbacks of commercial conventional methods and the potential prospects and incentives of new developing techniques such as supercritical and subcritical fluid extraction, and microorganism processing are discussed. Furthermore, important research obstacles and challenges in the development of an alternative technology for the mannitol production are pinpointed. 相似文献
110.
Poly vinyl alcohol (PVA) is a hydrophilic, biocompatible, and biodegradable polymer which has found application in biodrugs and tissue engineering. Sericin accompanying silk is a waste which is produced in scouring silk and has interesting properties which has attracted the attention of researchers. Silk sericin is also hydrophilic, biodegradable, and biocompatible. Moreover, it is cheap and anti-cancerous. Mixture of PVA and sericin in the form of 2D membrane or 3D hydrogels has been employed to heal skin damages. This research aimed at electrospinning PVA–sericin blend nanofibers in the form of a mat which has applications in tissue engineering, using dimethyl sulfoxide (DMSO) as an organic solvent. This research showed that the solution of PVA–sericin in DMSO was electrospinnable; however, the addition of urea to the solution made the electrospinning easier. The electrospinning solution contained ratio of 0:100, 10:90, 15:85, 20:80, and 25:75 sericin (%w/w)–PVA (%w/w). The electrospun PVA–sericin nanofibers had an average diameter in the range of 179–285 nm. X-ray diffractometer and differential scanning calorimetry investigations showed no reaction occurring between PVA and sericin. Polyvinyl alcohol 100% was also electrospun in DMSO. Up to now, the electrospinning of PVA in non-aqueous media has not been reported in the literature. 相似文献