Performance analysis of m-retry BEB based DCF under unsaturated traffic condition
- Authors: Siddique, Md , Kamruzzaman, Joarder
- Date: 2010
- Type: Text , Conference paper
- Relation: 2010 IEEE Wireless Communications and Networking Conference (WCNC) p. 1-6
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- Description: The IEEE 802.11 standard offers a cheap and promising solution for small scale wireless networks. Due to the self configuring nature, WLANs do not require large scale infrastructure deployment, and are scalable and easily maintainable which incited its popularity in both literature and industry. In real environment, these networks operate mostly under unsaturated condition. We investigate performance of such a network with m-retry limit BEB based DCF. We consider imperfect channel with provision for power capture. Our method employs a Markov model and represents the most common performance measures in terms of network parameters making the model and mathematical analysis useful in network design and planning. We also explore the effects of packet error, network size, initial contention window, and retry limit on overall performance of WLANs.
Availability measure model for Assistive Care Loop Framework using wireless sensor networks
- Authors: Balasubramanian, Venki , Hoang, Doan
- Date: 2010
- Type: Text , Conference proceedings
- Relation: 6th International Conference on Intelligent Sensors, Sensor Networks and Information Processing, ISSNIP 2010,Brisbane, 7th-10th Dec, 2010 published in Proceedings of ISSNIP 2010 Sixth International Conference on Intelligent Sensors, Sensor Networks and Information Processing, p. 281-286
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- Description: Nowadays, body area wireless sensor networks (BAWSNs) applications are increasingly being used in in-house health monitoring systems. These applications have stringent timing requirements and often run continuously without interruptions. Hence, it becomes imperative to determine the operational continuity of the BAWSN applications by measuring their availability. The BAWSN applications rely on the collection of data within a critical time from all of the source sensor nodes rather than the data from an individual source. Subsequently, the measure of availability for a BAWSN application should be based on the time and the data delivery from all the sensor nodes. Taking into account these specific characteristics and the constraints of the BAWSN, we develop a model to measure the availability of a BAWSN application based on the unavailable time. The proposed model is evaluated through a series of experiments conducted in our existing Assistive Care Loop Framework (ACLF). Furthermore, we also develop an analogous theoretical model to evaluate the availability of a BAWSN application
A comprehensive method for analyzing the effect of geotextile layers on embankment stability
- Authors: Tolooiyan, Ali , Abustan, Ismail , Selamat, Mohamad , Ghaffari, Sh
- Date: 2009
- Type: Text , Journal article
- Relation: Geotextiles and Geomembranes Vol. 27, no. 5 (2009), p. 399-405
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- Description: Commercial software is used widely in slope stability analyses of reinforced embankments. Almost all of these programs consider the tensile strength of geotextiles and soil-geotextile interface friction. However, currently available commercial software generally does not consider the drainage function of nonwoven geotextile reinforcement. In this paper, a reinforced channel embankment reinforced by a nonwoven geotextile is analyzed using two methods. The first method only considers the tensile strength and soil-geotextile interface friction. The second method also considers the drainage function. In both cases, the reinforced embankment is modeled in rapid drawdown condition since this is one of the most important conditions with regard to stability of channel embankments. It is shown that for this type of application, modeling a nonwoven geotextile reinforced embankment using commercial software which neglects the drainage function of the geotextile may be unrealistic.
Investigation on system reliability optimization based on classification of criteria
- Authors: Khorshidi, Hadi , Gunawan, Indra , Ibrahim, Yousef
- Date: 2013
- Type: Text , Conference proceedings
- Relation: Industrial Technology (ICIT), 2013 IEEE International Conference, Capetown, SA. 25-28 Feb. 2013 p.1706-1711
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- Description: System reliability optimization has been considered as an area to improve the operational availability of electrical and manufacturing systems. This research area addresses system reliability estimation and mathematical model development. This paper presents a -review on system reliability optimization techniques based on different classification of criteria. The main criteria considered in this study are system structure, system state, optimization model, allocation model, modeling and solution methods. The classification can provide an overview of all criteria that should be used to make optimal decisions in a system by taking the reliability into account. Not only it can assist the researchers to develop new optimization models, but also it presents the practitioners how system reliability optimization models can help industries. The paper also discusses the limitations of the present techniques in this area.
Predicting and controlling the dynamics of infectious diseases
- Authors: Evans, Robin , Mammadov, Musa
- Date: 2015
- Type: Text , Conference proceedings
- Relation: 54th IEEE Conference on Decision and Control, CDC 2015; Osaka, Japan; 15th-18th December 2015; Published in Proceedings of the IEEE Conference on Decision and Control; p. 5378-5383
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- Description: This paper introduces a new optimal control model to describe and control the dynamics of infectious diseases. In the present model, the average time to isolation (i.e. hospitalization) of infectious population is the main time-dependent parameter that defines the spread of infection. All the preventive measures aim to decrease the average time to isolation under given constraints. The model suggested allows one to generate a small number of possible future scenarios and to determine corresponding trajectories of infected population in different regions. Then, this information is used to find an optimal distribution of bed capabilities across countries/regions according to each scenario. © 2015 IEEE.
Development of a spherical parallel manipulator as a haptic device for a tele-operation system: Application to robotic surgery
- Authors: Saafi, Hadi , Laribi, Med Amine , Zeghoul, Said , Ibrahim, Yousef
- Date: 2013
- Type: Text , Conference proceedings
- Relation: IECON 2013 - 39th Annual Conference of the IEEE Industrial Electronics Society, Nov. 2013, Vienna, Austria p. 4097-4102
- Full Text: false
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- Description: In tele-operation applications, especially in surgery, haptic devices need to exhibit a high degree of rigidity and accuracy. This paper deals with the development of a spherical parallel manipulator (SPM) that enables the satisfaction of those characteristics. The parallel architecture enables the use of this kind of robot as master in a tele-operation system. Moreover, the SPM has a center of rotation that makes it a natural candidate and more adapted to minimally invasive surgery application. However, the parallel manipulator presents a poor behavior in singular configuration. In this paper we discuss the technique we used to overcome the singularity effects. We also present the methodology of using additional sensor to avoid kinematic structure problem without design changes. The investigation of the developed solution is detailed in this paper. Also, the experimental results of the newly developed haptic device are presented in this paper.
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.
Predictive analytics for detecting sensor failure using autoregressive integrated moving average model
- Authors: Thiyagarajan, Karthick , Kodagoda, Sarath , Van Nguyen, Linh
- Date: 2017
- Type: Text , Conference proceedings
- Relation: 2017 12th IEEE Conference on Industrial Electronics and Applications (ICIEA); Siem Reap, Cambodia; 18-20 June 2017 p. 1926-1931
- Full Text: false
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- Description: Sensors play a vital role in monitoring the important parameters of critical infrastructure. Failure of such sensors causes destabilization to the entire system. In this regard, this paper proposes a predictive analytics solution for detecting the failure of a sensor that measures surface temperature from an urban sewer. The proposed approach incorporates a forecasting technique based on the past time series of sparse data using an autoregressive integrated moving average (ARIMA) model. Based on the 95% forecast interval and continuity of faulty data, a criterion was set to detect anomalies and to issue a warning for sensor failure. The forecasted and faulty data were assumed Gaussian distributed. By using the probability density of the distribution, the mean and variance were computed for faulty data to examine the abnormality in the variance value of each day to detect the sensor failure. The experimental results on the sewer temperature data are appealing.
Link prediction by correlation on social network
- Authors: Rahman, Md Shafiur , Dey, Leema Rani , Haider, Sajal , Uddin, Md Ashraf , Islam, Manowarul
- Date: 2017
- Type: Text , Conference proceedings
- Relation: 2017 20th International Conference of Computer and Information Technology (ICCIT); Dhaka, Bangladesh; 22-24 December 2017 p. 1-6
- Full Text: false
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- Description: In a social network, the topology of the network grows through the formation of the link. the connection between two nodes in a social network indicates a confidence in terms of the similarity of some activities. Generally, a new link in the social network is created from different perspectives such as familiarity, cohesiveness, geographical locations etc. The concept of the link in the social network has been utilized to discover the hidden meaning of different fields such as e-commerce, bioinformatics and information retrieval. The prediction of a new link between two nodes in the social network is normally accomplished based on the nature of the topology and the similarity function among the nodes is defined with the help of the number of common friends. In this paper, we propose two link prediction algorithms: Local Link Prediction Algorithm and Global Link prediction by taking into consideration of user's activities as well as the common friends. We apply two formulas called correlation based cScore and influential score based iScore to measure the similarity between the two predicted nodes. Finally, we analyze the performance of the proposed algorithms by using DBLP, PPI, PB, and USAir data sets and the experimental result attests that our link predicted algorithm outperforms over the existing algorithms.
Convex model for controlled Islanding in transmission expansion planning to improve frequency stability
- Authors: Esmaili, Masoud , Ghamsari-Yazdel, Mohammad , Amjady, Nima , Chung, C. Y.
- Date: 2021
- Type: Journal article
- Relation: IEEE transactions on power systems Vol. 36, no. 1 (2021), p. 58-67
- Full Text: false
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- Description: Intentional controlled islanding (ICI) is the last resort to split an endangered power system into smaller islands to prevent blackout. New lines that are planned by transmission expansion planning (TEP) can affect the stability of islands during ICI. In this paper, an ICI-TEP method is proposed to improve the stability of islands by more efficient planning of transmission assets. Moreover, by developing a criterion for the frequency of center of inertia (COI) in each island, the frequency deviations of generators from the COI frequency are minimized to result in more stable islands. The proposed ICI-TEP, incorporating AC network representation, is modeled as mixed-integer linear programming and quadratic convex problems ensuring tractability. A Benders decomposition strategy is also proposed to solve the problem. Results of testing the proposed ICI-TEP method on IEEE 39-bus and 300-bus test systems confirm its effectiveness, compared to conventional TEP, in terms of coping with sever disturbances by creating more stable islands with a lower load shedding.
Short-circuit constrained power system expansion planning considering bundling and voltage levels of lines
- Authors: Esmaili, Masoud , Ghamsari-Yazdel, Mohammad , Amjady, Nima , Conejo, Antonio
- Date: 2020
- Type: Text , Journal article
- Relation: IEEE transactions on power systems Vol. 35, no. 1 (2020), p. 584-593
- Full Text: false
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- Description: System expansion planning (SEP) models do not generally represent voltage levels, bundled conductors in transmission lines, and short-circuit limits. These modeling assumptions may result in suboptimal planning outcomes. To overcome this potential flaw, we propose a short-circuit constrained dynamic SEP (SC-SEP) that allows for investment decisions at different stages of the planning horizon and includes a detailed representation of voltage levels, alternative bundled conductor options per line and short-circuit limits. An effective linearization technique is used to transform the resulting mixed-integer nonlinear model into a mixed-integer linear one. The accuracy of the proposed model and the effectiveness of the proposed linearization technique are illustrated using the IEEE 39-bus system.
A Distributionally robust AC Network-constrained unit commitment
- Authors: Dehghan, Shahab , Aristidou, Petros , Amjady, Nima , Conejo, Antonio
- Date: 2021
- Type: Text , Journal article
- Relation: IEEE transactions on power systems Vol. 36, no. 6 (2021), p. 5258-5270
- Full Text: false
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- Description: This paper presents a distributionally robust network-constrained unit commitment (DR-NCUC) model considering AC network modeling and uncertainties of demands and renewable productions. The proposed model characterizes uncertain parameters using a data-driven ambiguity set constructed by training samples. The non-convex AC power flow equations are approximated by convex quadratic and McCormick relaxations. Since the proposed min-max-min DR-NCUC problem cannot be solved directly by available solvers, a new decomposition algorithm with proof of convergence is reported in this paper. The master problem of this algorithm is solved using both primal and dual cuts, while the max-min sub-problem is solved using the primal-dual hybrid gradient method, obviating the need for using duality theory. Also, an active set strategy is proposed to enhance the tractability of the decomposition algorithm by ignoring the subset of inactive constraints. The proposed model is applied to a 6-bus test system and the IEEE 118-bus test system under different conditions. These case studies illustrate the performance of the proposed DR-NCUC model to characterize uncertainties and the superiority of the proposed decomposition algorithm over other decomposition approaches using either primal or dual cuts.
A probabilistic reverse power flows scenario analysis framework
- Authors: Demazy, Antonin , Alpcan, Tansu , Mareels, Iven
- Date: 2020
- Type: Text , Journal article
- Relation: IEEE open access journal of power and energy Vol. 7, no. (2020), p. 524-532
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- Description: Distributed Energy Resources (DER), mainly residential solar PV, are embedded deep within the power distribution network and their adoption is fast increasing globally. As more customers participate, these power generation units cause Reverse Power Flow (RPF) at the edge of the grid, directed upstream into the network, thus violating one of the traditional design principles for power networks. The effects of a single residential solar PV system is negligible, but as the adoption by end-consumers increases to high percentages, the aggregated effect is no longer negligible and must be considered in the design and configuration of power networks. This article proposes a framework that helps to predict the RPF intensity probability for any given scenario of DER penetration within the distribution network. The considered scenario parameters are the number and location of each residential DERs, their capacity and the daily net-load profiles. Classical simulation-based approach for this is not scalable as it relies on solving the load-flow equations for each individual scenario. The framework leverages machine learning techniques to make fast and precise RPF prediction within the network for each scenario. The framework enables the Distribution Network Service Providers (DNSPs) to assess DERs penetration scenarios at a granular level, derive and localise the RPF risks and assess the respective impacts on the installed assets for network planning purpose. The framework is illustrated with scenario analysis conducted on an IEEE 123 bus system and OpenDSS and shown that it can lead to multiple orders of magnitude savings in computational time while retaining an accuracy of 94% or above compared to classical brute force simulations.
Nested bilevel optimization for dera operation strategy: A stochastic multiobjective igdt model with hybrid endogenous/exogenous scenarios
- Authors: Yazdaninejad, Mohsen , Amjady, Nima , Hatziargyriou, Nikos
- Date: 2021
- Type: Text , Journal article
- Relation: IEEE systems journal Vol. 15, no. 4 (2021), p. 5495-5506
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- Description: An aggregation of distributed energy resources (DERs) can bring economic and technical benefits for the DER owners and system operator. However, the operation of DERs encounters various uncertainties, which can seriously impact the benefits of DER aggregation. This article presents a new operation optimization approach for an aggregator of DERs considering the unavailability of DERs (as discrete uncertainty sources) as well as forecast uncertainties of electricity prices, solar powers, and wind powers (as continuous uncertainty sources). The proposed approach for DER aggregator (DERA) operation optimization comprises stochastic multiobjective information-gap decision theory (IGDT) to model these discrete and continuous uncertain variables. Moreover, a hybrid endogenous/exogenous scenario generation method is incorporated into the proposed approach to enhance the efficiency of the stochastic programming part by producing decision-dependent scenario trees. The proposed approach is formulated as a nested bilevel optimization model. The proposed approach is compared with other DERA operation optimization models using an out-of-sample analysis method. The comparative results illustrate the superiority of the proposed stochastic multiobjective IGDT approach over various deterministic, stochastic, and IGDT methods. In addition, the high tractability of the proposed solution method is illustrated, while its linearization error for the stochastic multiobjective IGDT problem is well below 1%.
Tracking equilibrium point under real-time price-based residential demand response
- Authors: Ding, Tao , Qu, Ming , Amjady, Nima , Wang, Fengyu , Bo, Rui , Shahidehpour, Mohammad
- Date: 2021
- Type: Text , Journal article
- Relation: IEEE transactions on smart grid Vol. 12, no. 3 (2021), p. 2736-2740
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- Description: This letter proposes a model for tracking the equilibrium point of the real-time locational marginal price (LMP) based residential demand response program, where elastic demand is modeled as a monotonously decreasing linear function of the LMP. The resulting bi-level model contains both primary and dual variables, making it difficult to solve. Using duality, the dual model is formulated as a convex quadratic problem which is tractable to solve and find the global optimum. Furthermore, the condition for the existence of the equilibrium point is given. Numerical results on the IEEE 30-bus system verifies the effectiveness of the demand response model.
A Hybrid estimation and identification method for online calculation of voltage-dependent load parameters
- Authors: Kabiri, Mehdi , Amjady, Nima
- Date: 2019
- Type: Text , Journal article
- Relation: IEEE systems journal Vol. 13, no. 1 (2019), p. 792-801
- Full Text: false
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- Description: This paper presents a hybrid estimation and identification (HEI) method for identifying the load model parameters of voltage-dependent loads along with estimating the system states. The parameters of voltage-dependent load models are identified using multiple snapshots consecutively gathered through supervisory control and data acquisition system. The proposed HEI method imposes no additional cost to the installed metering devices or communication network. Mathematical aspects of the proposed HEI method are analytically proved and a four-step approach is presented for implementing it. Comprehensive numerical experiments and statistical analysis are presented to demonstrate the effectiveness of the proposed method for both load model identification and state estimation.