290 research outputs found
Hermite Positive Definite Solution of a Class of Matrix Equation
AbstractIn this paper, the Hermite positive definite solutions of the nonlinear matrix equation XS+A*X−tA=Q are discussed. A sufficient condition and two necessary and sufficient conditions for the existence of Hermite positive definite solutions for this equation are derived. The existence of minimal Hermite positive definite solution is also studied here, and an iterative method for obtaining the minimal Hermite positive definite solution is given
Implementation of Drone System in Survey for Tomato Chlorotic Spot Virus
As a cutting-edge technology, drone systems have shown great potential in agriculture. This article elucidates the implementation of a drone with a multispectral sensing system in a field survey for tomato chlorotic spot virus in south Florida. The findings demonstrate that drone technology can provide growers with precise and timely information about disease incidence and distribution in a labor-saving manner for decision making in crop management to mitigate yield loss. We provide recommendations for Extension professionals regarding educating producers on applying the technology to manage their crops efficiently
A Novel Multi-Charged Draw Solute That Removes Organic Arsenicals from Water in a Hybrid Membrane Process
The potential of forward osmosis
for water treatment can only be
maximized with suitable draw solutes. Here a three-dimensional, multicharge
draw solute of decasodium phytate (Na<sub>10</sub>-phytate) is designed
and synthesized for removing organic arsenicals from water using a
hybrid forward osmosis (FO) – membrane distillation (MD) process.
Efficient water recovery is achieved using Na<sub>10</sub>-phytate
as a draw solute with a water flux of 20.0 LMH and negligible reverse
solute diffusion when 1000 ppm organic arsenicals as the feed and
operated under ambient conditions with FO mode. At 50 °C, the
novel draw solute increases water flux by more than 30% with water
fluxes higher than 26.0 LMH on the FO side, drastically enhancing
water recovery efficiency. By combining the FO and MD processes into
a single hybrid process, a 100% recovery of Na<sub>10</sub>-phytate
draw solute was achieved. Crucially, organic arsenicals or Na<sub>10</sub>-phytate draw solutes are both rejected 100% and not detected
in the permeate of the hybrid process. The complete rejection of both
organic arsenicals and draw solutes using hybrid membrane processes
is unprecedented; creating a new application for membrane separations
DYNAMIC CONSTRUCTION CONTROL METHOD FOR A DEEP FOUNDATION PIT WITH SAND-PEBBLE GEOLOGY
Taking the water-rich sand and pebble geology deep foundation pit of Jinfu Station of Chengdu Metro Line 6 as the research object, combined with the ladder excavation method of slotting, utilizing finite difference software FLAC 3D as well as on-site monitoring result, the deformation law of the diaphragm wall during the dynamic excavation of the foundation pit is analysed, and the influence of the relative stiffness between the vertical and horizontal walls of the foundation pit on the lateral deformation of the retaining structure is discussed. The results show that while using the ladder excavation method of slotting, the maximum lateral displacement of the underground diaphragm walls decreases gradually with the excavation depth of the foundation pit, which occurs at the intersection of the middle point of the oblique excavation line and the step distance section of the transverse excavation. Additionally, the lateral displacement increases closer to the excavation section. The lateral displacement of the envelope enclosure mainly depends on the relative constraint stiffness of the vertical and horizontal underground diaphragm wall of the foundation pit. The use of the ladder layered excavation method of slotting can effectively reduce the lateral displacement of the underground diaphragm wall. The simulated result and on-site monitoring result are nearly the same. These results can provide a corresponding theory and engineering basis for the selection of excavation methods for the same type of sand and pebble stratum foundation pit
Fatigue Life Simulation and Analysis of Aluminum Alloy Sheet Self-piercing Riveting
The fatigue life prediction model of self-piecing riveting components of aluminum alloy is established and the effects of roughness and residual stress on fatigue life of self-piercing riveting components is analyzed by the model. Finite element software ABAQUS and fatigue analysis software FE-SAFE are used to study the effects of roughness and residual stress on the fatigue life of self-piecing riveting components through finite element simulation and mathematical statistics multivariate orthogonal regression experiment. The quantitative relations between fatigue life and three variables (roughness, residual stress and maximum stress) are fitted, and the variation trend of fatigue life with roughness and residual stress is obtained. The order of influence of roughness, residual stress, maximum stress and two interactions on fatigue life is as follows: residual stress, interaction between roughness and residual stress, roughness. When the maximum stress is fixed, the fatigue life decreases with the increase of roughness with a certain residual stress, and the fatigue life decreases with the increase of roughness with a certain residual stress. The average error between the fatigue experiment results and the simulation results is 9.74%, which proves that the simulation results are reliable
A Linear LMP Model for Active and Reactive Power with Power Loss
Pricing the reactive power is more necessary than ever before because of the
increasing challenge of renewable energy integration on reactive power balance
and voltage control. However, reactive power price is hard to be efficiently
calculated because of the non-linear nature of optimal AC power flow equation.
This paper proposes a linear model to calculate active and reactive power LMP
simultaneously considering power loss. Firstly, a linearized AC power flow
equation is proposed based on an augmented Generation Shift Distribution
Factors (GSDF) matrix. Secondly, a linearized LMP model is derived using GSDF
and loss factors. The formulation of LMP is further decomposed into four
components: energy, congestion, voltage limitation and power loss. Finally, an
iterate algorithm is proposed for calculating LMP with the proposed model. The
performance of the proposed model is validated by the IEEE-118 bus system.Comment: 6 pages, 6 figures, accepted by IEEE Sustainable Power & Energy
Conference (iSPEC2019
Continental drift and plateau uplift control origination and evolution of Asian and Australian monsoons
Evolutions of Asian and Australian monsoons have important significance for understanding the past global change but are still a controversial subject. Here, we explore systematically the effects of plate movement and plateau uplift on the formation and evolution of the Asian and Australian monsoons by numerical simulations based on land-sea distributions and topographic conditions for five typical geological periods during the Cenozoic. Our results suggest that the timings and causes of formation of the monsoons in South Asia, East Asia and northern Australia are different. The Indian Subcontinent, which was located in the tropical Southern Hemisphere in the Paleocene, was influenced by the austral monsoon system simulated at that time. Once it moved to the tropical Northern Hemisphere in the Eocene, the South Asian monsoon established and remained persistently thereafter. However, the monsoons of East Asia and northern Australia did not appear until the Miocene. The establishment of the simulated low-latitude South Asian (northern Australian) monsoon appeared to have strongly depended on the location of mainland India (Australia), associated with northward plate motion, without much relation to the plateau uplift. On the contrary, the establishment of the mid-latitude East Asian monsoon was mainly controlled by the uplift of Tibetan plateau
Continental drift, plateau uplift, and the evolutions of monsoon and arid regions in Asia, Africa, and Australia during the Cenozoic
Monsoon and arid regions in the Asia-Africa-Australia (A-A-A) realm occupy more than 60% of the total area of these continents. Geological evidence showed that significant changes occurred to the A-A-A environments of the monsoon and arid regions, the land-ocean configuration in the Eastern Hemisphere, and the topography of the Tibetan Plateau (TP) in the Cenozoic. Motivated by this background, numerical experiments for 5 typical geological periods during the Cenozoic were conducted using a coupled ocean-atmosphere general circulation model to systemically explore the formations and evolutionary histories of the Cenozoic A-A-A monsoon and arid regions under the influences of continental drift and plateau uplift. Results of the numerical experiments indicate that the timings and causes of the formations of monsoon and arid regions in the A-A-A realm were very different. The northern and southern African monsoons existed during the mid-Paleocene, while the South Asian monsoon appeared in the Eocene after the Indian Subcontinent moved into the tropical Northern Hemisphere. In contrast, the East Asian monsoon and northern Australian monsoon were established much later in the Miocene. The establishment of the tropical monsoons in northern and southern Africa, South Asia, and Australia were determined by both the continental drift and seasonal migration of the Inter-Tropical Convergence Zone (ITCZ), while the position and height of the TP were the key factor for the establishment of the East Asian monsoon. The presence of the subtropical arid regions in northern and southern Africa, Asia, and Australia depended on the positions of the continents and the control of the planetary scale subtropical high pressure zones, while the arid regions in the Arabian Peninsula and West Asia were closely related to the retreat of the Paratethys Sea. The formation of the mid-latitude arid region in the Asian interior, on the other hand, was the consequence of the uplift of the TP. These results from this study provide insight to the important roles played by the earth’s tectonic boundary conditions in the formations and evolutions of regional climates during geological times
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