Asymptotic Estimates for Blocking Probabilities in a Large Multi-Rate Loss Network

1997 ◽  
Vol 29 (3) ◽  
pp. 806-829 ◽  
Author(s):  
A. Simonian ◽  
J. W. Roberts ◽  
F. Théberge ◽  
R. Mazumdar
Keyword(s):  
Critical Load ◽  
Blocking Probability ◽  
Asymptotic Estimates ◽  
Switched Network ◽  
Blocking Probabilities ◽  
Low Load ◽  
Rate Loss ◽  
Load Conditions

In this paper, asymptotic estimates for the blocking probability of a call pertaining to a given route in a large multi-rate circuit-switched network are given. Concentrating on low load and critical load conditions, these estimates are essentially derived by using probability change techniques applied to the distribution of the number of occupied links. Such estimates for blocking probabilities are also given a uniform expression applicable to both load regimes. This uniform expression is numerically validated via simple examples.

Asymptotic Estimates for Blocking Probabilities in a Large Multi-Rate Loss Network

1997 ◽  
Vol 29 (03) ◽  
pp. 806-829 ◽  
Author(s):  
A. Simonian ◽  
J. W. Roberts ◽  
F. Théberge ◽  
R. Mazumdar
Keyword(s):  
Critical Load ◽  
Blocking Probability ◽  
Asymptotic Estimates ◽  
Switched Network ◽  
Blocking Probabilities ◽  
Low Load ◽  
Rate Loss ◽  
Load Conditions

In this paper, asymptotic estimates for the blocking probability of a call pertaining to a given route in a large multi-rate circuit-switched network are given. Concentrating on low load and critical load conditions, these estimates are essentially derived by using probability change techniques applied to the distribution of the number of occupied links. Such estimates for blocking probabilities are also given a uniform expression applicable to both load regimes. This uniform expression is numerically validated via simple examples.

scholarly journals The Effect of Pure Oxygenated Biofuels on Efficiency and Emissions in a Gasoline Optimised DISI Engine

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3908
Author(s):  
Tara Larsson ◽  
Senthil Krishnan Mahendar ◽  
Anders Christiansen-Erlandsson ◽  
Ulf Olofsson
Keyword(s):  
Internal Combustion Engines ◽  
Negative Impact ◽  
The Other ◽  
Nox Emissions ◽  
Combustion Engines ◽  
Engine Efficiency ◽  
Spark Timing ◽  
Low Load ◽  
Oxygenated Fuels ◽  
Load Conditions

The negative impact of transport on climate has led to incentives to increase the amount of renewable fuels used in internal combustion engines (ICEs). Oxygenated, liquid biofuels are promising alternatives, as they exhibit similar combustion behaviour to gasoline. In this article, the effect of the different biofuels on engine efficiency, combustion propagation and emissions of a gasoline-optimised direct injected spark ignited (DISI) engine were evaluated through engine experiments. The experiments were performed without any engine hardware modifications. The investigated fuels are gasoline, four alcohols (methanol, ethanol, n-butanol and iso-butanol) and one ether (MTBE). All fuels were tested at two speed sweeps at low and mid load conditions, and a spark timing sweep at low load conditions. The oxygenated biofuels exhibit increased efficiencies, even at non-knock-limited conditions. At lower loads, the oxygenated fuels decrease CO, HC and NOx emissions. However, at mid load conditions, decreased volatility of the alcohols leads to increased emissions due to fuel impingement effects. Methanol exhibited the highest efficiencies and significantly increased burn rates compared to the other fuels. Gasoline exhibited the lowest level of PN and PM emissions. N-butanol and iso-butanol show significantly increased levels of particle emissions compared to the other fuels.

Routing Based on Security

2014 ◽  
pp. 365-380
Author(s):  
I. A. Almerhag
Keyword(s):  
Network Security ◽  
Standard Method ◽  
Blocking Probability ◽  
Computational Effort ◽  
Routing Algorithms ◽  
Measure Data ◽  
Security Metrics ◽  
Essential Requirement ◽  
Blocking Probabilities ◽  
Common Technique

Even though it is an essential requirement of any computer system, there is not yet a standard method to measure data security, especially when sending information over a network. However, the most common technique used to achieve the three goals of security is encryption. Three security metrics are derived from important issues of network security in this chapter. Each metric demonstrates the level of achievement in preserving one of the security goals. Routing algorithms based on these metrics are implemented to test the proposed solution. Computational effort and blocking probability are used to assess the behavior and the performance of these routing algorithms. Results show that the algorithms are able to find feasible paths between communicating parties and make reasonable savings in the computational effort needed to find an acceptable path. Consequently, higher blocking probabilities are encountered, which is the price to be paid for such savings.

Aerodynamic Numerical Investigation of Low-Pressure Steam Turbine Last Stage Under Low Load Conditions With Mode Decomposition Methods

2019 ◽  
Author(s):  
Ping Hu ◽  
Tong Lin ◽  
Rui Yang ◽  
Xiaocheng Zhu ◽  
Zhaohui Du
Keyword(s):  
Steam Turbine ◽  
Frequency Spectrum ◽  
Low Frequency ◽  
Low Pressure ◽  
Unsteady Pressure ◽  
Mode Decomposition ◽  
Low Load ◽  
Last Stage ◽  
Operating Points ◽  
Load Conditions

Abstract It is common that steam turbine works at different operating points, especially under low load conditions, to cater to complex and varied demands for power generation recently. Considering the long and thin shape of last stage moving blades (LSMBs) in a low-pressure (LP) steam turbine, there are many challenges to design a suitable case which balances global efficiency against sufficient structure strength when suffering excitations at low load operating points. In present work, the aim is to extract specific aerodynamic excitations and recognize their distribution and propagation features. Firstly, steady 3D computational fluid dynamics (CFD) calculations are simulated at 25GV and 17GV (25% and 17% of design mass flow conditions) and corresponding unsteady calculations are performed with enough rotor revolutions to obtain integrated flow periodicities. Unsteady pressure signals near tip region of LSMBs are monitored circumferentially in both static and rotating coordinates. The fast Fourier transformation (FFT) results of unsteady pressure signals show that there are broadband humps with small disturbance amplitudes in low frequency spectrum at 25GV, however, a sharp spike is shown in low frequency spectrum at 17GV. Further, circumferential mode decomposition (CMD) method has been applied to distinguish different fluctuations in frequency and the mode numbers and circumferential propagating pace of which have been obtained. Finally, dynamic mode decomposition (DMD) method has been performed to describe detailed mode shapes of featured flow perturbances both in static and rotating coordinate system. These analyses indicate that at 25GV, a band of unsteady responses with very low amplitude was noted which has some features similar to rotating instability (RI). However, distribution and propagation features of flow unsteadiness at 17GV are in good agreement with rotating stall (RS) in compressor.

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