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  1. Book ; Online: AC Power Flow Feasibility Restoration via a State Estimation-Based Post-Processing Algorithm

    Taheri, Babak / Molzahn, Daniel K.

    2023  

    Abstract: This paper presents an algorithm for restoring AC power flow feasibility from solutions to simplified optimal power flow (OPF) problems, including convex relaxations, power flow approximations, and machine learning (ML) models. The proposed algorithm ... ...

    Abstract This paper presents an algorithm for restoring AC power flow feasibility from solutions to simplified optimal power flow (OPF) problems, including convex relaxations, power flow approximations, and machine learning (ML) models. The proposed algorithm employs a state estimation-based post-processing technique in which voltage phasors, power injections, and line flows from solutions to relaxed, approximated, or ML-based OPF problems are treated similarly to noisy measurements in a state estimation algorithm. The algorithm leverages information from various quantities to obtain feasible voltage phasors and power injections that satisfy the AC power flow equations. Weight and bias parameters are computed offline using an adaptive stochastic gradient descent method. These parameters inform the online computations of the state estimation-based algorithm to recover feasible solutions. Furthermore, the proposed algorithm can simultaneously utilize combined solutions from different relaxations, approximations, and ML models to enhance performance. Case studies demonstrate the effectiveness and scalability of the proposed algorithm, with numerical results showing several orders of magnitude improvement over traditional methods for restoring AC power flow feasible solutions.
    Keywords Electrical Engineering and Systems Science - Systems and Control
    Subject code 006
    Publishing date 2023-04-22
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Book ; Online: Optimizing Parameters of the DC Power Flow

    Taheri, Babak / Molzahn, Daniel K.

    2023  

    Abstract: Many power system operation and planning problems use the DC power flow approximation to address computational challenges from the nonlinearity of the AC power flow equations. The DC power flow simplifies the AC power flow equations to a linear form that ...

    Abstract Many power system operation and planning problems use the DC power flow approximation to address computational challenges from the nonlinearity of the AC power flow equations. The DC power flow simplifies the AC power flow equations to a linear form that relates active power flows to phase angle differences across branches, parameterized by coefficients based on the branches' susceptances. Inspired by techniques for training machine learning models, this paper proposes an algorithm that seeks optimal coefficient and bias parameters to improve the DC power flow approximation's accuracy. Specifically, the proposed algorithm selects the coefficient and bias parameter values that minimize the discrepancy, across a specified set of operational scenarios, between the power flows given by the DC approximation and the power flows from the AC equations. Gradient-based optimization methods like Broyden-Fletcher-Goldfarb-Shanno (BFGS), Limited-Memory BFGS (L-BFGS), and Truncated Newton Conjugate-Gradient (TNC) enable solution of the proposed algorithm for large systems. After an off-line training phase, the optimized parameters are used to improve the accuracy of the DC power flow during on-line computations. Numerical results show several orders of magnitude improvements in accuracy relative to a hot-start DC power flow approximation across a range of test cases.
    Keywords Electrical Engineering and Systems Science - Systems and Control
    Subject code 621
    Publishing date 2023-09-30
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Book ; Online: Restoring AC Power Flow Feasibility from Relaxed and Approximated Optimal Power Flow Models

    Taheri, Babak / Molzahn, Daniel K.

    2022  

    Abstract: To address computational challenges associated with power flow nonconvexities, significant research efforts over the last decade have developed convex relaxations and approximations of optimal power flow (OPF) problems. However, benefits associated with ... ...

    Abstract To address computational challenges associated with power flow nonconvexities, significant research efforts over the last decade have developed convex relaxations and approximations of optimal power flow (OPF) problems. However, benefits associated with the convexity of these relaxations and approximations can have tradeoffs in terms of solution accuracy since they may yield voltage phasors that are inconsistent with the power injections and line flows, limiting their usefulness for some applications. Inspired by state estimation (SE) techniques, this paper proposes a new method for obtaining an AC power flow feasible point from the solution to a relaxed or approximated optimal power flow (OPF) problem. By treating the inconsistent voltage phasors, power injections, and line flows analogously to noisy measurements in a state estimation algorithm, the proposed method yields power injections and voltage phasors that are feasible with respect to the AC power flow equations while incorporating information from many quantities in the solution to a relaxed or approximated OPF problem. We improve this method by adjusting weighting terms with an approach inspired by algorithms used to train machine learning models. We demonstrate the proposed method using several relaxations and approximations. The results show up to several orders of magnitude improvement in accuracy over traditional methods.
    Keywords Electrical Engineering and Systems Science - Systems and Control
    Subject code 621
    Publishing date 2022-09-09
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Book ; Online: Co-Optimization of Damage Assessment and Restoration

    Jalilian, Ali / Taheri, Babak / Molzahn, Daniel K.

    A Resilience-Driven Dynamic Crew Allocation for Power Distribution Systems

    2023  

    Abstract: This study introduces a mixed-integer linear programming (MILP) model, effectively co-optimizing patrolling, damage assessment, fault isolation, repair, and load re-energization processes. The model is designed to solve a vital operational conundrum: ... ...

    Abstract This study introduces a mixed-integer linear programming (MILP) model, effectively co-optimizing patrolling, damage assessment, fault isolation, repair, and load re-energization processes. The model is designed to solve a vital operational conundrum: deciding between further network exploration to obtain more comprehensive data or addressing the repair of already identified faults. As information on the fault location and repair timelines becomes available, the model allows for dynamic adaptation of crew dispatch decisions. In addition, this study proposes a conservative power flow constraint set that considers two network loading scenarios within the final network configuration. This approach results in the determination of an upper and a lower bound for node voltage levels and an upper bound for power line flows. To underscore the practicality and scalability of the proposed model, we have demonstrated its application using IEEE 123-node and 8500-node test systems, where it delivered promising results.
    Keywords Electrical Engineering and Systems Science - Systems and Control
    Publishing date 2023-09-15
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article: Mechanism of fungal remediation of wetland water:

    Sen, Keya / Llewellyn, Marina / Taheri, Babak / Turner, Robert J / Berglund, Tanner / Maloney, Kellen

    Frontiers in microbiology

    2023  Volume 14, Page(s) 1234586

    Abstract: Mycoremediation uses mushroom forming fungi for remediation of sites contaminated with biotic and abiotic contaminants. The root-like hyphae of many fungi, the mycelia, have been used to remediate soil and water. In this study mushroom mycelia biofilters ...

    Abstract Mycoremediation uses mushroom forming fungi for remediation of sites contaminated with biotic and abiotic contaminants. The root-like hyphae of many fungi, the mycelia, have been used to remediate soil and water. In this study mushroom mycelia biofilters were evaluated for remediation efficacy of wetland water polluted with crow feces containing antibiotic resistant (AMR) bacteria. Three strains of fungi,
    Language English
    Publishing date 2023-10-18
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2587354-4
    ISSN 1664-302X
    ISSN 1664-302X
    DOI 10.3389/fmicb.2023.1234586
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Book ; Online: Improving Distribution System Resilience by Undergrounding Lines and Deploying Mobile Generators

    Taheri, Babak / Molzahn, Daniel K. / Grijalva, Santiago

    2022  

    Abstract: To improve the resilience of electric distribution systems, this paper proposes a stochastic multi-period mixed-integer linear programming model that determines where to underground distribution lines and how to coordinate mobile generators in order to ... ...

    Abstract To improve the resilience of electric distribution systems, this paper proposes a stochastic multi-period mixed-integer linear programming model that determines where to underground distribution lines and how to coordinate mobile generators in order to serve critical loads during extreme events. The proposed model represents the service restoration process using the linearized DistFlow approximation of the AC power flow equations as well as binary variables for the undergrounding statuses of the lines, the configurations of switches, and the locations of mobile generators during each time period. The model also enforces a radial configuration of the distribution network and considers the transportation times needed to reposition the mobile generators. Using an extended version of the IEEE 123-bus test system, numerical simulations show that combining the ability to underground distribution lines with the deployment of mobile generators can significantly improve the resilience of the power supply to critical loads.
    Keywords Electrical Engineering and Systems Science - Systems and Control
    Subject code 600
    Publishing date 2022-04-21
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  7. Article: Modelling perceived service quality and turnover intentions in gender‐segregated environments

    Olya, Hossein / Taheri, Babak / Farmaki, Anna / Joseph Gannon, Martin

    International journal of consumer studies. 2022 Jan., v. 46, no. 1

    2022  

    Abstract: This study extends current understanding of how gender shapes value co‐creation, perceived service quality and turnover intention within health and fitness clubs. Survey responses were collected from 485 fitness club customers in Iran. Partial least ... ...

    Abstract This study extends current understanding of how gender shapes value co‐creation, perceived service quality and turnover intention within health and fitness clubs. Survey responses were collected from 485 fitness club customers in Iran. Partial least squares structural equation modelling (PLS‐SEM) was deployed to demonstrate the effects of predictor variables while fuzzy‐set qualitative comparative analysis (fsQCA) was used to identify combinations of value co‐creation behaviours capable of predicting model outcomes. Necessary condition analysis (NCA) was also employed to identify the value co‐creation factors required to achieve low turnover intentions and high service quality perceptions. Results reveal the moderating role of gender in shaping the complex combinations of value co‐creation factors leading to low turnover and high perceived quality; fsQCA findings demonstrate how this differs between male and female consumers. NCA findings suggest that fitness club managers should foster an interactive environment through advocacy programmes, promoting responsible behaviours andwboosting tolerance, to encourage both male and female customers to participate in co‐creation processes. This is the first empirical study to apply complexity theory to explore whether service quality perceptions and turnover intentions vary across gender via structural and configurational modelling.
    Keywords advocacy ; empirical research ; equations ; females ; males ; surveys ; Iran
    Language English
    Dates of publication 2022-01
    Size p. 200-217.
    Publishing place John Wiley & Sons, Ltd
    Document type Article
    Note JOURNAL ARTICLE
    ZDB-ID 2045189-1
    ISSN 1470-6423
    ISSN 1470-6423
    DOI 10.1111/ijcs.12664
    Database NAL-Catalogue (AGRICOLA)

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  8. Article ; Online: Semitransparent Perovskite Solar Cells with Ultrathin Protective Buffer Layers.

    Magliano, Erica / Mariani, Paolo / Agresti, Antonio / Pescetelli, Sara / Matteocci, Fabio / Taheri, Babak / Cricenti, Antonio / Luce, Marco / Di Carlo, Aldo

    ACS applied energy materials

    2023  Volume 6, Issue 20, Page(s) 10340–10353

    Abstract: Semitransparent perovskite solar cells (ST-PSCs) are increasingly important in a range of applications, including top cells in tandem devices and see-through photovoltaics. Transparent conductive oxides (TCOs) are commonly used as transparent electrodes, ...

    Abstract Semitransparent perovskite solar cells (ST-PSCs) are increasingly important in a range of applications, including top cells in tandem devices and see-through photovoltaics. Transparent conductive oxides (TCOs) are commonly used as transparent electrodes, with sputtering being the preferred deposition method. However, this process can damage exposed layers, affecting the electrical performance of the devices. In this study, an indium tin oxide (ITO) deposition process that effectively suppresses sputtering damage was developed using a transition metal oxides (TMOs)-based buffer layer. An ultrathin (<10 nm) layer of evaporated vanadium oxide or molybdenum oxide was found to be effective in protecting against sputtering damage in ST-PSCs for tandem applications, as well as in thin perovskite-based devices for building-integrated photovoltaics. The identification of minimal parasitic absorption, the high work function and the analysis of oxygen vacancies denoted that the TMO layers are suitable for use in ST-PSCs. The highest fill factor (FF) achieved was 76%, and the efficiency (16.4%) was reduced by less than 10% when compared with the efficiency of gold-based PSCs. Moreover, up-scaling to 1 cm
    Language English
    Publishing date 2023-10-05
    Publishing country United States
    Document type Journal Article
    ISSN 2574-0962
    ISSN (online) 2574-0962
    DOI 10.1021/acsaem.3c00735
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Book: Special issue: contemporary issues in museums and heritage marketing management

    Baxter, Ian / O'Gorman, Kevin / Taheri, Babak

    (Journal of marketing management ; volume 32, issues 15/16 (November 2016))

    2016  

    Title variant Contemporary issues in museums and heritage marketing management
    Author's details guest editors: Babak Taheri, Kevin O'Gorman and Ian Baxter
    Series title Journal of marketing management ; volume 32, issues 15/16 (November 2016)
    Language English
    Size Seite 1387-1512, Illustrationen
    Publisher Routledge, Taylor & Francis Group
    Publishing place Abingdon
    Document type Book
    Note Enthält 6 Beiträge
    Database ECONomics Information System

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  10. Article ; Online: Attributes of High-Performance Electron Transport Layers for Perovskite Solar Cells on Flexible PET versus on Glass.

    Dkhili, Marwa / Lucarelli, Giulia / De Rossi, Francesca / Taheri, Babak / Hammedi, Khadija / Ezzaouia, Hatem / Brunetti, Francesca / Brown, Thomas M

    ACS applied energy materials

    2022  Volume 5, Issue 4, Page(s) 4096–4107

    Abstract: Electron transport layers (ETLs) play a fundamental role in perovskite solar cells (PSCs) through charge extraction. Here, we developed flexible PSCs on 12 different kinds of ETLs based on ... ...

    Abstract Electron transport layers (ETLs) play a fundamental role in perovskite solar cells (PSCs) through charge extraction. Here, we developed flexible PSCs on 12 different kinds of ETLs based on SnO
    Language English
    Publishing date 2022-04-06
    Publishing country United States
    Document type Journal Article
    ISSN 2574-0962
    ISSN (online) 2574-0962
    DOI 10.1021/acsaem.1c03311
    Database MEDical Literature Analysis and Retrieval System OnLINE

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