NUMERICAL SIMULATION ON THE EXISTENCE OF FLUCTUATION OF INSTANTANEOUS AVAILABILITY

2016 ◽  
Vol 40 (5) ◽  
pp. 703-713 ◽  
Author(s):  
Yang Yi ◽  
Ren Si Chao ◽  
Fan Guimei ◽  
Kang Rui
Keyword(s):  
Numerical Simulation ◽  
Numerical Methods ◽  
Failure Rate ◽  
The Other ◽  
Repairable System ◽  
Repair Rate ◽  
Trapezoidal Formula ◽  
Other Hand ◽  
Increasing Functions

This paper considers the fluctuation of the instantaneous availability by numerical methods for a one-unit repairable system. The choices of the failure rate and repair rate are linear or cubic increasing functions. For the equation of instantaneous availability composing of two convolutions, the following numerical methods are used: the composite Simpson formula and the trapezoidal formula. That is to say, the simulated curves of instantaneous availability under any condition are obtained. Through the simulated results, when the failure rate and repair rate are selected as increasing functions, the extremum of simulated curve exists so fluctuation exists. On the other hand, if parameters of increasing functions become smaller, the fluctuation weakens.

A Hybrid Semi-empirical Model for Lean Blow-Out Limit Predictions of Aero-engine Combustors

2014 ◽  
Vol 137 (3) ◽  
Author(s):  
Bin Hu ◽  
Yong Huang ◽  
Jianzhong Xu
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Empirical Model ◽  
The Other ◽  
Model Parameters ◽  
Model Parameter ◽  
Other Hand ◽  
Aero Engine ◽  
Semi Empirical

According to the Lefebvre's model and flame volume (FV) concept, an FV model about lean blow-out (LBO) was proposed by authors in early study. On the other hand, due to the model parameter (FV) contained in FV model is obtained based on the experimental data, FV model could only be used in LBO analysis instead of prediction. In view of this, a hybrid FV model is proposed that combines the FV model with numerical simulation in the present study. The model parameters contained in the FV model are all estimated from the simulated nonreacting flows. Comparing with the experimental data for 11 combustors, the maximum and average uncertainties of hybrid FV model are ±16% and ±10%.

LINEAR STABILITY ANALYSIS GENERALIZED TO A THERMALLY-DRIVEN FLOW

1999 ◽  
Vol 09 (02) ◽  
pp. 415-425
Author(s):  
JEAN-MICHEL CORNET ◽  
CLAUDE-HENRI LAMARQUE
Keyword(s):  
Stability Analysis ◽  
Numerical Methods ◽  
Linear Stability ◽  
Linear Stability Analysis ◽  
The Other ◽  
Basic Solution ◽  
Driven Cavity ◽  
Convective Flows ◽  
Other Hand ◽  
Thermally Driven

We intend to establish a methodology suited to the search of the first bifurcations of convective flows using a linear stability analysis so that it permits us to define a relationship between amplitude and frequency of the perturbation. We use a particular combination of various numerical methods to compute on one hand the basic solution. On the other hand the perturbation is applied to the search for the bifurcations in a thermally-driven cavity.

Influence of the location of production wells in unconfined groundwater basins: an analysis by numerical simulation

1990 ◽  
Vol 27 (5) ◽  
pp. 657-668 ◽  
Author(s):  
Duke Ophori ◽  
József Tóth
Keyword(s):  
Numerical Simulation ◽  
Steady State ◽  
Groundwater Resources ◽  
The Other ◽  
Recharge Area ◽  
Development Potential ◽  
Discharge Area ◽  
Other Hand ◽  
Well Yield ◽  
Production Wells

Development potential of groundwater resources under continuous production is calculated by numerical simulation for models of unit basins for the plains regions of Alberta, Canada, in order to analyze the relations between the location of water wells on the one hand, and well yield and basin stability, on the other. These relations are expressed in terms of two basin hydrologic parameters, namely the transitional basin yield (TBY) and the sustainable basin yield (SBY). TBY is the net cumulative inflow of water into the system, induced by and during development at a particular site, from an initial to a final steady-state condition. SBY, on the other hand, is the amount of water captured from precipitation due to production at a particular site under the newly established steady-state conditions. TBY is highest for well locations in the discharge area and decreases gradually as the sites are moved toward the recharge area. This is so because more of the naturally discharging, and thus otherwise lost, water is captured by wells located in discharge areas than by wells in recharge areas. On the other hand, SBY is greater if the wells are located in recharge areas than if they are in the discharge areas because an increasing percentage of precipitation is converted to infiltration by production wells as their locations are moved upslope in the basin. From a regional hydrological viewpoint, these are key relations in optimizing the development potential of the groundwater resources in extensive unconfined basins. Precipitation rate, simulated as maximum potential infiltration rate, is assumed to be constant over time. It is shown also that under conditions of restricted rainfall, a recharge-area development results in unstable basin-hydrological conditions sooner than when development takes place in the discharge area. Regional groundwater exploitation should, therefore, be initiated in discharge areas and moved towards recharge regions gradually, and only for compelling reasons. Factors such as precipitation rates and positions of aquifers within a basin affect TBY and SBY to various degrees, thereby influencing the optimal location of well sites in the basin.

Numerical Simulation of AlxGa1-XN/GaN Hetero Junction Quantum Well by AMPS-1D

2011 ◽  
Vol 282-283 ◽  
pp. 518-521
Author(s):  
Kai Ju Zhang ◽  
B. Wan
Keyword(s):  
Numerical Simulation ◽  
Quantum Well ◽  
The Other ◽  
Simulation Program ◽  
One Dimensional ◽  
Photonic Structures ◽  
Other Hand ◽  
Dimensional Simulation ◽  
The One

In this work, the one dimensional simulation program called analysis of microelectronic and photonic structures (AMPS-1D) is used to study the performances of depth of AlxGa1-xN/GaN heterojunction quantum well. The calculated results of AMPS-1D software show that the effect of different Al composition on the depth of AlxGa1-xN/GaN heterojunction quantum well is slight. On the other hand, the effect of different doped concentration in AlxGa1-xN is obvious.

scholarly journals Investigation of the visual appearance of different skirt styles and materials during the fitting simulation with Lectra Modaris

2021 ◽  
Vol 2 (2) ◽  
pp. 141-150
Author(s):  
Tibifez Hailu Nechno ◽  
Yordan Kyosev ◽  
Mulat Alubel ◽  
Sybille Krzywinski
Keyword(s):  
Numerical Simulation ◽  
Material Properties ◽  
The Other ◽  
Comparison Result ◽  
Visual Appearance ◽  
Other Hand ◽  
Clothing Style ◽  
Best Fitting ◽  
The Right

This paper examines the influence of different fabric types and material properties on the visual appearance of three types of skirt styles using numerical simulation. The purpose of the simulation is to present and analyze the appearance of virtual garments, create the best-fitting pattern pieces, and choose the appropriate fabric type based on the multiple clothing styles to achieve the intended design. The results show that when the type of fabric changes without changing the clothing style and on the other hand the style changes without changing the type of material, the appearance of the garment changes and the effect can be clearly seen with the 3d comparison result. These changes should be taken into account when choosing the right fabric for different styles.

A GENERALIZED PREDATOR–PREY SYSTEM WITH HABITAT COMPLEXITY

2017 ◽  
Vol 25 (03) ◽  
pp. 495-520 ◽  
Author(s):  
ZHIHUI MA ◽  
SHUFAN WANG ◽  
TINGTING WANG ◽  
HAOPENG TANG ◽  
ZIZHEN LI
Keyword(s):  
Numerical Simulation ◽  
Habitat Complexity ◽  
The Other ◽  
Predator Prey ◽  
Prey System ◽  
Other Hand ◽  
Stabilizing Effect ◽  
Open Issue ◽  
The One

This paper presents a generalized predator–prey system and considers the effect of habitat complexity on the dynamical consequences. The results show that habitat complexity has a major impact on the dynamical consequences of the considered system. On the one hand, habitat complexity has a stabilizing impact under certain conditions. A numerical simulation in our study and in experiments conducted in the published studies elaborate on this stabilizing effect. On the other hand, the most interesting and open issue is that a destabilizing effect of habitat complexity is found theoretically. All results are explained and illustrated from the ecological viewpoint.

Numerical Simulation of Detonation in Fine Aluminum-Oxygen Mixtures with Hybrid Combustion Model

2013 ◽  
Vol 748 ◽  
pp. 3-6
Author(s):  
Xiang Long Yang ◽  
Zhou Xiao Qing ◽  
Yang Lei ◽  
Zhong Wei Huang
Keyword(s):  
Numerical Simulation ◽  
Detonation Wave ◽  
Wave Structure ◽  
The Other ◽  
Combustion Model ◽  
Gas Temperature ◽  
Other Hand ◽  
Detonation Structure ◽  
Pressure Profiles

The detonation of fine aluminum-oxygen mixtures was numerical simulated using a hybrid combustion model. The emphasis was laid on the influence of the decomposition of Al2O3 on the detonation structure. Results showed that including the decomposition of Al2O3 will limit the gas temperature behind the detonation wave below a certain value. On the other hand, a double-wave structure will appear in the pressure profiles in cases with rich-dust condition if the decomposition of Al2O3 is not included.

A study of cometary eruptions through OH radio-lines

1999 ◽  
Vol 173 ◽  
pp. 249-254
Author(s):  
A.M. Silva ◽  
R.D. Miró
Keyword(s):  
Short Duration ◽  
Growth Curves ◽  
The Other ◽  
Initial Mass ◽  
Radio Lines ◽  
Other Hand ◽  
Sudden Rise

AbstractWe have developed a model for theH2OandOHevolution in a comet outburst, assuming that together with the gas, a distribution of icy grains is ejected. With an initial mass of icy grains of 108kg released, theH2OandOHproductions are increased up to a factor two, and the growth curves change drastically in the first two days. The model is applied to eruptions detected in theOHradio monitorings and fits well with the slow variations in the flux. On the other hand, several events of short duration appear, consisting of a sudden rise ofOHflux, followed by a sudden decay on the second day. These apparent short bursts are frequently found as precursors of a more durable eruption. We suggest that both of them are part of a unique eruption, and that the sudden decay is due to collisions that de-excite theOHmaser, when it reaches the Cometopause region located at 1.35 × 105kmfrom the nucleus.

Closing the GAP—A 5Å Scanning Microscope

1969 ◽  
Vol 27 ◽  
pp. 6-7
Author(s):  
A. V. Crewe
Keyword(s):  
Normal Form ◽  
The Other ◽  
Resolving Power ◽  
Scanning Microscope ◽  
Conventional Microscope ◽  
Other Hand ◽  
Closing The Gap ◽  
Thermal Sources ◽  
Better Than ◽  
Transmission Microscope

We have become accustomed to differentiating between the scanning microscope and the conventional transmission microscope according to the resolving power which the two instruments offer. The conventional microscope is capable of a point resolution of a few angstroms and line resolutions of periodic objects of about 1Å. On the other hand, the scanning microscope, in its normal form, is not ordinarily capable of a point resolution better than 100Å. Upon examining reasons for the 100Å limitation, it becomes clear that this is based more on tradition than reason, and in particular, it is a condition imposed upon the microscope by adherence to thermal sources of electrons.

Life Beyond 1MeV

1980 ◽  
Vol 38 ◽  
pp. 30-33
Author(s):  
K.H. Westmacott
Keyword(s):  
Electron Microscopy ◽  
Past Experience ◽  
The Other ◽  
Good Case ◽  
Other Hand ◽  
The U.S

Life beyond 1MeV – like life after 40 – is not too different unless one takes advantage of past experience and is receptive to new opportunities. At first glance, the returns on performing electron microscopy at voltages greater than 1MeV diminish rather rapidly as the curves which describe the well-known advantages of HVEM often tend towards saturation. However, in a country with a significant HVEM capability, a good case can be made for investing in instruments with a range of maximum accelerating voltages. In this regard, the 1.5MeV KRATOS HVEM being installed in Berkeley will complement the other 650KeV, 1MeV, and 1.2MeV instruments currently operating in the U.S. One other consideration suggests that 1.5MeV is an optimum voltage machine – Its additional advantages may be purchased for not much more than a 1MeV instrument. On the other hand, the 3MeV HVEM's which seem to be operated at 2MeV maximum, are much more expensive.

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