Mathematical models for failure reconfiguration of telecommunication networks : Part 1
- Authors: Dzalilov, Zari , Ouveysi, Iradj
- Date: 2009
- Type: Text , Journal article
- Relation: Optimization Vol. 58, no. 5 (2009), p. 483-504
- Full Text: false
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- Description: This article proposes various mathematical modelling of networks for failure recovery. We consider a survivable communication network which is designed to carry different types of services under service level agreements (SLAs) between the network provider and the network users. Two different approaches for dynamical reconfiguration of networks are presented: with and without penalization. The approach without penalization does not require to consider the status of SLAs during the process of network reconfiguration. The second approach considers the status of the SLAs in the network and the corresponding re-optimization model for network reconfiguration is more complicated as the dimension of the linear programming problem in this case is higher than one for the problem of optimization without penalization. Some mathematical models and solution methodologies for this network operation problem are presented and an extensive implementation result has been provided.
Mathematical models for failure reconfiguration of telecommunication networks : Part 2
- Authors: Dzalilov, Zari , Ouveysi, Iradj
- Date: 2009
- Type: Text , Journal article
- Relation: Optimization Vol. 58, no. 5 (2009), p. 505-520
- Full Text: false
- Reviewed:
- Description: This article proposes an efficient network reconfiguration model for failure recovery of a communication network. The novelty of our methodology is that, it considers a small neighbourhood of failed component(s) in the network in order to perform network reconfiguration. This approach significantly reduces the size of proposed linear programming problem, making our reconfiguration procedure theoretically scalable and practically implementable. Targeting a small neighbourhood of failed area in the network also minimizes the amount of traffic rerouting in the network. This is ideal in the management of a communication network.
Delayed self-regulation and time-dependent chemical drive leads to novel states in epigenetic landscapes
- Authors: Mitra, Mitra , Taylor, Paul , Hutchison, Chris , McLeish, T. C. B. , Chakrabarti, Buddapriya
- Date: 2014
- Type: Text , Journal article
- Relation: Journal of the Royal Society Interface Vol. 11, no. 100 (2014), p.
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- Description: The epigenetic pathway of a cell as it differentiates from a stem cell state to a mature lineage-committed one has been historically understood in terms of Waddington's landscape, consisting of hills and valleys. The smooth top and valley-strewn bottom of the hill represent their undifferentiated and differentiated states, respectively. Although mathematical ideas rooted in nonlinear dynamics and bifurcation theory have been used to quantify this picture, the importance of time delays arising from multistep chemical reactions or cellular shape transformations have been ignored so far.We argue that this feature is crucial in understanding cell differentiation and explore the role of time delay in a model of a single-gene regulatory circuit.We show that the interplay of time-dependent drive and delay introduces a new regime where the system shows sustained oscillations between the two admissible steady states. We interpret these results in the light of recent perplexing experiments on inducing the pluripotent state in mouse somatic cells.We also comment on howsuch an oscillatory state can provide a framework for understanding more general feedback circuits in cell development. © 2014 The Author(s) Published by the Royal Society. All rights reserved.
- Description: The epigenetic pathway of a cell as it differentiates from a stem cell state to a mature lineage-committed one has been historically understood in terms of Waddington's landscape, consisting of hills and valleys. The smooth top and valley-strewn bottom of the hill represent their undifferentiated and differentiated states, respectively. Although mathematical ideas rooted in nonlinear dynamics and bifurcation theory have been used to quantify this picture, the importance of time delays arising from multistep chemical reactions or cellular shape transformations have been ignored so far.We argue that this feature is crucial in understanding cell differentiation and explore the role of time delay in a model of a single-gene regulatory circuit.We showthat the interplay of time-dependent drive and delay introduces a new regime where the system shows sustained oscillations between the two admissible steady states. We interpret these results in the light of recent perplexing experiments on inducing the pluripotent state in mouse somatic cells.We also comment on howsuch an oscillatory state can provide a framework for understanding more general feedback circuits in cell development. © 2014 The Author(s) Published by the Royal Society. All rights reserved.
Enhanced power extraction from thermoelectric generators considering non-uniform heat distribution
- Authors: Fauzan, Miftah , Muyeen, S. , Islam, Syed
- Date: 2021
- Type: Text , Journal article
- Relation: Energy Conversion and Management Vol. 246, no. (2021), p.
- Full Text: false
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- Description: In this paper, a technique to enhance the performances of the thermoelectric generator under non-uniform heat distribution is developed. A large area of heat source is needed when the thermoelectric generator is used for high power applications such as powering air conditioners, household appliances, and distributed generation systems. Non-uniform heat distribution is a natural phenomenon in large surface of heat source. A model was developed and was validated with a prototype of thermoelectric panel 80 V, 2 A. Results show very good similarities between the model and the prototype outputs under various operating conditions. The error during the tests for the voltage performances was 6.5%, while the current was 1.1%. A method of maximizing power, i.e., developing a specialized maximum power point tracker (MPPT) along with blocking diodes, is proposed to overcome the effects of non-uniform heat distribution. In a typical condition, the output power dropped by 30% when a non-uniform thermal distribution is imposed to the array. The blocking diode can save power by 15%, and the MPPT expands up to 20% power when adopting this method. © 2021