14,350 research outputs found
A new approach to secure economic power dispatch
This article presents a new nonlinear convex network flow programming model and algorithm for solving the on-line economic power dispatch with N and N−1 security. Based on the load flow equations, a new nonlinear convex network flow model for secure economic power dispatch is set up and then transformed into a quadratic programming model, in which the search direction in the space of the flow variables is to be solved. The concept of maximum basis in a network flow graph was introduced so that the constrained quadratic programming model was changed into an unconstrained quadratic programming model which was then solved by the reduced gradient method. The proposed model and its algorithm were examined numerically with an IEEE 30-bus test system on an ALPHA 400 Model 610 machine. Satisfactory results were obtaine
Influence of structure on the behavior of a saturated clayey loess
An intensive experimental investigation by means of triaxial and oedometer tests was performed on a clayey loess that was retrieved from two depths at a location on the southern Chinese Loess Plateau. Intact and reconstituted samples were used to identify the effects of the natural structure on soil behavior in saturated conditions. The behavior in compression was clearly affected by structure with the intact samples reaching well-defined gross yield points outside the intrinsic compression line of the reconstituted soil, after which the compression paths converged towards the intrinsic compression lines, behavior which is consistent with destructuration. However, very high stresses were required to give complete convergence. Similarly the triaxial tests that were carried out at lower stress levels also did not give convergence of the critical states so that different critical state lines could be defined for the intact and reconstituted soils. This was consistent with qualitative observations from scanning electron micrographs that natural elements of fabric and possibly bonding persisted even after triaxial shearing. The effects of structure at the two depths on the compression and shearing behavior were slightly larger for the shallower samples. Despite the very different genesis of the soils, it was found that similar frameworks could be applied to those used for sedimentary clays and that the degree of structure was equivalent to a clay of medium sensitivity
Challenges of Internet of Things and Big Data Integration
The Internet of Things anticipates the conjunction of physical gadgets to the
In-ternet and their access to wireless sensor data which makes it expedient to
restrain the physical world. Big Data convergence has put multifarious new
opportunities ahead of business ventures to get into a new market or enhance
their operations in the current market. considering the existing techniques and
technologies, it is probably safe to say that the best solution is to use big
data tools to provide an analytical solution to the Internet of Things. Based
on the current technology deployment and adoption trends, it is envisioned that
the Internet of Things is the technology of the future, while to-day's
real-world devices can provide real and valuable analytics, and people in the
real world use many IoT devices. Despite all the advertisements that companies
offer in connection with the Internet of Things, you as a liable consumer, have
the right to be suspicious about IoT advertise-ments. The primary question is:
What is the promise of the Internet of things con-cerning reality and what are
the prospects for the future.Comment: Proceedings of the International Conference on International
Conference on Emerging Technologies in Computing 2018 (iCETiC '18), 23rd
-24th August, 2018, at London Metropolitan University, London, UK, Published
by Springer-Verla
Three-Dimensional Spectral-Domain Optical Coherence Tomography Data Analysis for Glaucoma Detection
Purpose: To develop a new three-dimensional (3D) spectral-domain optical coherence tomography (SD-OCT) data analysis method using a machine learning technique based on variable-size super pixel segmentation that efficiently utilizes full 3D dataset to improve the discrimination between early glaucomatous and healthy eyes. Methods: 192 eyes of 96 subjects (44 healthy, 59 glaucoma suspect and 89 glaucomatous eyes) were scanned with SD-OCT. Each SD-OCT cube dataset was first converted into 2D feature map based on retinal nerve fiber layer (RNFL) segmentation and then divided into various number of super pixels. Unlike the conventional super pixel having a fixed number of points, this newly developed variable-size super pixel is defined as a cluster of homogeneous adjacent pixels with variable size, shape and number. Features of super pixel map were extracted and used as inputs to machine classifier (LogitBoost adaptive boosting) to automatically identify diseased eyes. For discriminating performance assessment, area under the curve (AUC) of the receiver operating characteristics of the machine classifier outputs were compared with the conventional circumpapillary RNFL (cpRNFL) thickness measurements. Results: The super pixel analysis showed statistically significantly higher AUC than the cpRNFL (0.855 vs. 0.707, respectively, p = 0.031, Jackknife test) when glaucoma suspects were discriminated from healthy, while no significant difference was found when confirmed glaucoma eyes were discriminated from healthy eyes. Conclusions: A novel 3D OCT analysis technique performed at least as well as the cpRNFL in glaucoma discrimination and even better at glaucoma suspect discrimination. This new method has the potential to improve early detection of glaucomatous damage. © 2013 Xu et al
Compressibility effects on the scalar mixing in reacting homogeneous turbulence
The compressibility and heat of reaction influence on the scalar mixing in
decaying isotropic turbulence and homogeneous shear flow are examined via data
generated by direct numerical simulations (DNS). The reaction is modeled as
one-step, exothermic, irreversible and Arrhenius type. For the shear flow
simulations, the scalar dissipation rate, as well as the time scale ratio of
mechanical to scalar dissipation, are affected by compressibility and reaction.
This effect is explained by considering the transport equation for the
normalized mixture fraction gradient variance and the relative orientation
between the mixture fraction gradient and the eigenvectors of the solenoidal
strain rate tensor.Comment: In Turbulent Mixing and Combustion, eds. A. Pollard and S. Candel,
Kluwer, 200
An investigation of particle breakage in loess
The paper presents a detailed experimental investigation of particle breakage in three kinds of loess, i.e., sandy loess, silty loess and clayey loess. It is firstly found that particle breakage can occur within loess in oedometer test, which results in a better-graded soil at the end of the test. Initial breakage stresses for both the silty and clayey loess are less than 0.5 MPa, and about 2 MPa for the sandy loess. The relative breakage (B ) is used to evaluate the particle breakage degree, and it is found that for all the three kinds of loess tested, B increases with the increasing loading stress until it reaches a threshold, after which B tends to keep a constant value. Particles within the loose specimens break more easily than those within the dense ones, especially for the sandy and silty loess. It is also observed that for the specimens reconstituted with previously tested soils, particle breakage degree decreases significantly, which means little particle breakage occurs in the pre-crushed specimens
Mental and behavioral disorders due to substance abuse and perinatal outcomes: A study based on linked population data in New South Wales, Australia
Background: The effects of mental and behavioral disorders (MBD) due to substance use during peri-conception and pregnancy on perinatal outcomes are unclear. The adverse perinatal outcomes of primiparous mothers admitted to hospital with MBD due to substance use before and/or during pregnancy were investigated. Method: This study linked birth and hospital records in NSW, Australia. Subjects included primiparous mothers admitted to hospital for MBD due to use of alcohol, opioids or cannabinoids during peri-conception and pregnancy. Results: There were 304 primiparous mothers admitted to hospital for MBD due to alcohol use (MBDA), 306 for MBD due to opioids use (MBDO) and 497 for MBD due to cannabinoids (MBDC) between the 12 months peri-conception and the end of pregnancy. Primiparous mothers admitted to hospital for MBDA during pregnancy or during both peri-conception and pregnancy were significantly more likely to give birth to a baby of low birthweight (AOR = 4.03, 95%CI: 1.97-8.24 for pregnancy; AOR = 9.21, 95%CI: 3.76-22.57 both periods); preterm birth (AOR = 3.26, 95% CI: 1.52-6.97 for pregnancy; AOR = 4.06, 95%CI: 1.50-11.01 both periods) and admission to SCN or NICU (AOR = 2.42, 95%CI: 1.31-4.49 for pregnancy; AOR = 4.03, 95%CI: 1.72-9.44 both periods). Primiparous mothers admitted to hospital for MBDO, MBDC or a combined diagnosis were almost three times as likely to give birth to preterm babies compared to mothers without hospital admissions for psychiatric or substance use disorders. Babies whose mothers were admitted to hospital with MBDO before and/or during pregnancy were six times more likely to be admitted to SCN or NICU (AOR = 6.29, 95%CI: 4.62-8.57). Conclusion: Consumption of alcohol, opioids or cannabinoids during peri-conception or pregnancy significantly increased the risk of adverse perinatal outcomes. © 2014 by the authors; licensee MDPI, Basel, Switzerland
Analysis and design of a novel linear generator for harvesting oceanic wave energy
© 2015 IEEE. In almost every permanent magnet linear generator (PMLG), demagnetization would greatly degrade the electricity generation capability over time. This paper proposes a novel PMLG which consists of a permanent magnet excitation generator (PMEG) to supply electrical excitation to the field winding of an electromagnetic linear generator (EMLG) which functions as the main power generator. The proposed generator can reduce the demagnetization problem of the conventional PMLG. The finite element analysis is performed by using the commercial software package ANSYS/ANSOFT for designing the proposed PMLG, and the genetic algorithm has been used to find the optimal pole size, pole pitch, air gap length and load variation to maximize the output power. Special m-shaped stator core is designed for the PMEG to minimize the leakage flux and cogging force. The voltage, current, power, magnetic flux density, force components and applied force are also analyzed and discussed
The mechanics of a saturated silty loess with a transitional mode
Problems of identifying unique normal compression and critical state lines have been found in gap-graded soils and also some silty soils, a mode of behaviour sometimes known as ‘transitional’. Loess is a typical silty soil that covers up to 631 000 km2 in China and is of great significance as a result of the large number of engineering projects under construction. To examine the potential transitional behaviour in loess, an extensive series of carefully controlled oedometer tests and triaxial tests on intact and reconstituted specimens were carried out. Loess specimens with a wide range of initial void ratios were reconstituted using different preparation methods. Intact specimens were taken from two depths, but their natural variabilities were not significant and could be neglected, apart from their difference in the initial void ratios. The results have highlighted the features of transitional behaviour in this loess, not only in reconstituted but also intact states, and in particular that there is an influence of the initial density of this loess on its normal compression and critical state lines. Two factors, m and P, as proposed by earlier research, were used to quantify the degree of transitional behaviour. These indicate that this silty loess has a significant degree of transitional behaviour. The intact specimens possibly have an even more pronounced transitional degree than the reconstituted ones, although this is difficult to confirm because of the limited range of initial specific volumes of the intact specimens. The effects of structure on the mechanics of the intact silty loess have also been identified by comparing the behaviour of the intact and reconstituted soils, and the paper discusses the difficulties of doing this for a soil without a unique intrinsic behaviour
Triazolobenzothiadiazole-Based Copolymers for Polymer Light-Emitting Diodes: Pure Near-Infrared Emission via Optimized Energy and Charge Transfer
A series of new near-infrared (NIR) emitting copolymers, based on a low band gap 6-(2-butyloctyl)-4,8-di(thiophen-2-yl)-[1,2,3]triazolo[4′,5′:4,5]benzo[1,2-c]-[1,2,5]thiadiazole (TBTTT) fluorophore copolymerized into a high band gap poly[3,3′-ditetradecyl-2,2′-bithiophene-5,5′-diyl-alt-5-(2-ethylhexyl)-4H-thieno[3,4-c]pyrrole-4,6(5H)-dione-1,3-diyl] (P2TTPD) host backbone, for polymer light-emitting diode (PLED) applications is reported. PLEDs fabricated from the host polymer (P2TTPD-0) show external quantum efficiencies (EQEs) up to 0.49% at 690 nm, with turn-on voltage (Von) at only 2.4 V. By incorporating the TBTTT segments into the host polymer backbone, pure NIR emission peaking at ca. 900 nm is obtained with Von remaining below 5 V. This work demonstrates that such a low Von can be attributed to efficient intrachain energy and/or charge transfer to the TBTTT sites. When the NIR emitting copolymer (P2TTPD-10) is blended with P2TTPD-0, the TBTTT are confined to well-separated polymer chains. As a result, the EQE from the blend is lower and the Von higher than that obtained from the pure copolymer (P2TTPD-1.0) with equal content of TBTTT. An analogous copolymer (P4T-1.0), consisting of poly[3,3′-ditetradecyl-2,2′:5′,2′′:5′′,2′′′-quaterthiophene-5,5′′′-diyl] (P4T) as the host and 1% TBTTT as the NIR emitter, further demonstrates that pure NIR emission can be obtained only through optimized molecular orbital energy levels, as in P2TTPD-1.0, which minimizes chances for either charge trapping or exciton splitting
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