scholarly journals Investigation of Wave Overtopping from Various Geometrical Configurations of Coastal Breakwater Ramps

2018 ◽  
Vol 7 (3.28) ◽  
pp. 24
Author(s):  
Mohd Azlan Musa ◽  
Mohammad Fadhli Ahmad ◽  
Nor Aieni Mokhtar ◽  
Ahmad Jusoh
Keyword(s):  
Numerical Simulation ◽  
Discharge Rate ◽  
Rate Performance ◽  
Design Practice ◽  
Wave Overtopping ◽  
Coastal Defence ◽  
The Common ◽  
3D Software ◽  
Linear Ramp ◽  
Erosion Protection

Breakwater is often required for erosion protection. The effectiveness of breakwater structure as a coastal defence could be determined through overtopping wave surpass onto its crest freeboard structure. The common design practice of breakwater structure is using a linear ramp configuration. There is still a limited knowledge on the contribution of various configuration ramps shape into breakwater efficiency. Thus, this study attempts to investigate a few other's configuration of ramp geometries through overtopping discharge rate performance and identified its relationships with the crest freeboard. Three configurations of ramp geometries (convex, concave and cubic) have been investigated using numerical simulation of CFD-Flow 3D software. The result indicates that, there are significant influences of ramp configuration parameters on the overtopping rate and the highest overtopping rate is contributed from cubic shape ramp geometry. It is recommended that the detail study on cubic ramp shape geometry for determining its capability in increasing overtopping rate.   

Maternal and neonatal outcomes following expectant management of preterm prelabour rupture of membranes before viability

2017 ◽  
Vol 45 (1) ◽  
Author(s):  
Winnie Huiyan Sim ◽  
Edward Araujo Júnior ◽  
Fabricio Da Silva Costa ◽  
Penelope Marie Sheehan
Keyword(s):  
Management Practices ◽  
Discharge Rate ◽  
Expectant Management ◽  
Intraventricular Haemorrhage ◽  
Neonatal Morbidity ◽  
Live Birth Rate ◽  
Neonatal Outcomes ◽  
Prognostic Indicators ◽  
Maternal And Neonatal Outcomes ◽  
The Common

AbstractAim:To assess the contemporary maternal and neonatal outcomes following expectant management of preterm premature rupture of membranes (PPROM) prior to 24 weeks’ gestation and to identify prognostic indicators of this morbid presentation.Methods:We performed a systematic review in the Pubmed and EMBASE databases to identify the primary (perinatal mortality, severe neonatal morbidity and serious maternal morbidity) and secondary (neonatal survival and morbidity) outcomes following expectant management of previable PPROM.Results:Mean latency between PPROM and delivery ranged between 20 and 43 days. Women with PPROM <24 weeks had an overall live birth rate of 63.6% and a survival-to-discharge rate of 44.9%. The common neonatal morbidities were respiratory distress syndrome, bronchopulmonary dysplasia and sepsis. The majority of neonatal deaths within 24 h post birth were associated with pulmonary hypoplasia, severe intraventricular haemorrhage and neonatal sepsis. The common maternal outcomes were chorioamnionitis and caesarean sections. The major predictors of neonatal survival were later gestational age at PPROM, adequate residual amniotic fluid levels, C-reactive protein <1 mg/dL within 24 h of admission and PPROM after invasive procedures.Conclusion:Pregnancy latency and neonatal survival following previable PPROM has improved in recent years, although neonatal morbidity remains unchanged despite recent advances in obstetric and neonatal care. There is heterogeneity in management practices across centres worldwide.

Turbine Split Rings Thermal Design Using Conjugate Numerical Simulation

2013 ◽  
Author(s):  
Aleksei S. Tikhonov ◽  
Andrey A. Shvyrev ◽  
Nikolay Yu. Samokhvalov
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Gas Turbine ◽  
Gas Dynamics ◽  
Thermal Condition ◽  
Fuel Efficiency ◽  
Thermal Design ◽  
Design Practice ◽  
Gas Temperature ◽  
Split Ring

One of the key factors ensuring gas turbine engines (GTE) competitiveness is improvement of life, reliability and fuel efficiency. However fuel efficiency improvement and the required increase of turbine inlet gas temperature (T*g) can result in gas turbine engine life reduction because of hot path components structural properties deterioration. Considering circumferential nonuniformity, local gas temperature T*g can reach 2500 K. Under these conditions the largest attention at designing is paid to reliable cooling of turbine vanes and blades. At present in design practice and scientific publications comparatively little attention is paid to detailed study of turbine split rings thermal condition. At the same time the experience of modern GTE operation shows high possibility of defects occurrence in turbine 1st stage split ring. This work objective is to perform conjugate numerical simulation (gas dynamics + heat transfer) of thermal condition for the turbine 1st stage split ring in a modern GTE. This research main task is to determine the split ring thermal condition by defining the conjugate gas dynamics and heat transfer result in ANSYS CFX 13.0 package. The research subject is the turbine 1st stage split ring. The split ring was simulated together with the cavity of cooling air supply from vanes through the case. Besides turbine 1st stage vanes and blades have been simulated. Patterns of total temperature (T*Max = 2000 °C) and pressure and turbulence level at vanes inlet (19.2 %) have been defined based on results of calculating the 1st stage vanes together with the combustor. The obtained results of numerical simulation are well coherent with various experimental studies (measurements of static pressure and temperature in supply cavity, metallography). Based on the obtained performance of the split ring cooling system and its thermal condition, the split ring design has been considerably modified (one supply cavity has been split into separate cavities, the number and arrangement of perforation holes have been changed etc.). All these made it possible to reduce considerably (by 40…50 °C) the split ring temperature comparing with the initial design. The design practice has been added with the methods which make it possible to define thermal condition of GTE turbine components by conjugating gas dynamics and heat transfer problems and this fact will allow to improve the designing level substantially and to consider the influence of different factors on aerodynamics and thermal state of turbine components in an integrated programming and computing suite.

scholarly journals High Discharge Rate Lithium Ion Batteries with the Composite Cathode of LiFePO4/Mesocarbon Nanobead

2010 ◽  
Vol 177 ◽  
pp. 208-210
Author(s):  
Yi Jie Gu ◽  
Cui Song Zeng ◽  
Yu Bo Chen ◽  
Hui Kang Wu ◽  
Hong Quan Liu ◽  
...  
Keyword(s):  
Lithium Ion Batteries ◽  
Room Temperature ◽  
Discharge Rate ◽  
Rate Capability ◽  
Lithium Ion ◽  
Composite Cathode ◽  
Rate Performance ◽  
High Discharge ◽  
High Discharge Rate ◽  
Lifepo4 Cathode

Olivine compounds LiFePO4 were prepared by the solid state reaction, and the electrochemical properties were studied with the composite cathode of LiFePO4/mesocarbon nanobead. High discharge rate performance can be achieved with the designed composite cathode of LiFePO4/mesocarbon nanobead. According to the experiment results, batteries with the composite cathode deliver discharge capacity of 1087mAh for 18650 type cell at 20C discharge rate at room temperature. The analysis shows that the uniformity of mesocarbon nanobead around LiFePO4 can supply enough change for electron transporting, which can enhance the rate capability for LiFePO4 cathode lithium ion batteries. It is confirmed that lithium ion batteries with LiFePO4 as cathode are suitable to electric vehicle application.

scholarly journals Mathematical modeling and numerical simulation of heat dissipation in led bulbs

2020 ◽  
Vol 24 (3 Part A) ◽  
pp. 1877-1884 ◽  
Author(s):  
Diego Alarcón ◽  
Eduardo. Balvís ◽  
Ricardo Bendaña ◽  
Alberto Conejero ◽  
de Fernández ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Numerical Simulation ◽  
Numerical Simulations ◽  
Heat Sink ◽  
Heat Dissipation ◽  
Thermal Contact ◽  
Heat Sinks ◽  
Experimental Measurements ◽  
Heating And Cooling ◽  
The Common

We present a detailed study of heating and cooling processes in LED luminaires with passive heat sinks. Our analysis is supported by numerical simulations as well as experimental measurements, carried on commercial systems used for outdoor lighting. We have focused our analysis on the common case of a single LED source in thermal contact with an aluminum passive heat sink, obtaining an excellent agreement with experimental measurements and the numerical simulations performed. Our results can be easily expanded, without loss of generality, to similar systems.

Numerical simulation of wave overtopping above perforated caisson breakwaters

2021 ◽  
Vol 163 ◽  
pp. 103795
Author(s):  
Xiao Liu ◽  
Yong Liu ◽  
Pengzhi Lin ◽  
Ai-jun Li
Keyword(s):  
Numerical Simulation ◽  
Wave Overtopping ◽  
Perforated Caisson

Chemoreceptor and baroreceptor responses of A1 area neurons projecting to supraoptic nucleus

1992 ◽  
Vol 263 (2) ◽  
pp. R310-R317 ◽  
Author(s):  
Y. W. Li ◽  
Z. J. Gieroba ◽  
W. W. Blessing
Keyword(s):  
Arterial Pressure ◽  
Supraoptic Nucleus ◽  
Discharge Rate ◽  
Sodium Cyanide ◽  
Peripheral Chemoreceptor ◽  
Antidromic Activation ◽  
Hypercapnic Hypoxia ◽  
Nucleus Increase ◽  
The Common ◽  
Baroreceptor Activation

Extracellular recordings were made from 127 neurons, identified by antidromic activation from the supraoptic nucleus, in the A1 area of urethan-anesthetized rabbits. The median axonal conduction velocity was 0.7 m/s, and the median discharge rate was 3.9 spikes/s. Raising arterial pressure decreased the discharge rate in 94 of 101 neurons tested. Lowering arterial pressure increased the discharge rate in 50 of 64 neurons tested. Of 70 neurons inhibited by baroreceptor activation, 40 were excited and 25 inhibited by hypercapnic hypoxia. Of 23 neurons excited by hypercapnic hypoxia, all were excited by hypoxia but only 2 were affected by hypercapnia. Of 16 neurons inhibited by hypercapnic hypoxia, 15 were inhibited by hypoxia and 1 was inhibited by hypercapnia. Of 14 neurons excited by hypoxia, 13 were excited by injection of sodium cyanide into the common carotid artery. Of five neurons inhibited by hypoxia, four were inhibited by sodium cyanide. Our results provide electrophysiological evidence that neurons projecting from the A1 area to the supraoptic nucleus increase their discharge rate in response to baroreceptor unloading and decrease their discharge rate in response to baroreceptor activation. These neurons may form part of the central pathway mediating secretion of vasopressin in response to hemorrhage. A high proportion of the neurons also receive peripheral chemoreceptor inputs, and these A1 cells may also be part of the central pathway whereby chemoreceptor stimulation modifies the secretion of vasopressin.

scholarly journals Numerical Simulation for FSW Process at Welding Aluminium Alloy AA6082-T6

Metals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 747 ◽  
Author(s):  
Nikola Sibalic ◽  
Milan Vukcevic
Keyword(s):  
Numerical Simulation ◽  
Numerical Simulations ◽  
Large Deformations ◽  
Numerical Data ◽  
Longitudinal Force ◽  
Kinematic Parameters ◽  
Friction Stir ◽  
Numerical Research ◽  
3D Software ◽  
Deform 3D

This paper presents the numerical simulation of the Friction stir welding (FSW) process obtained by using the DEFORM 3D software package. Numerical simulations are based on experimental research, welding of aluminum alloy AA6082-T6 by FSW method, which has the thickness of 7.8 mm. The aim of this paper is to determine the reliability of numerical simulations in the FSW process, which is followed by large deformations, where influential geometric and kinematic parameters are varied. Numerical research was done on the basis of the adopted five-phase orthogonal experimental plan with a variety of factors on two levels and repetition at the central point of the plan for four times. The parameters varied in the experiment are: Welding speed v mm/min, a rotation speed of tool ω rpm, angle of pin slopes α o, a diameter of the pin d mm, diameter of the shoulder D mm. During the performing of the FSW process, forces were measured in three normal directions: Axial force Fz, longitudinal force Fx and side force Fy, as well as the temperature in the adopted measuring positions of the workpiece. The experimental results obtained in this way were compared with the numerical experiment in the same adopted measuring positions, i.e., in the paper an analysis and comparison of the obtained experimental and numerical data of the measured forces and the generated temperature field were made.

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