More Like this

1. Distributed Current Source Method for Modeling Magnetic and Eddy-Current Fields Induced in Non-Ferrous Metallic Objects

   https://doi.org/10.1109/TMECH.2017.2771763  

   Lin, Chun-Yeon; Lee, Kok-Meng; Hao, Bingjie (November 2017, IEEE/ASME Transactions on Mechatronics)

   This paper presents a new modeling method to determine the harmonic eddy-current (EC) field induced in a non-ferrous metal and its corresponding magnetic flux density (MFD) by an EC-based sensing system for geometrical measurements, which accounts for the boundary effects of the object. Modeled using a distributed current source (DCS) method in state-space representation, the EC field is formulated as a two-step constrained least-square (CLS) problem to solve for its real and imaginary parts. Two practical techniques to improve the efficiency and accuracy of the EC solutions are illustrated; the first refines the DCS distribution based on the skin-depth effects, and the second takes advantages of commercial mesh-generation software to facilitate the modeling of EC induced in complex shaped objects. The DCS-based EC models are verified numerically by comparing computed results with 2D analytical axisymmetric solutions and commercial finite-element analysis (FEA), and evaluated experimentally with an EC sensor that measures the MFD generated by the induced EC in different materials and geometrical configurations. 

   more » « less
2. Design Optimization of Coreless Axial-flux PM Machines with Litz Wire and PCB Stator Windings

   Kesgin, M. G.; Han, P.; Taran, N.; Lawhorn, D.; Lewis, D.; Ionel, D. M. (August 2020, Proceedings, 2020 IEEE Energy Conversion Congress and Exposition (ECCE), Detroit, MI)

   Coreless axial-flux permanent-magnet (AFPM) machines may be attractive options for high-speed and high-power density applications due to the elimination of core losses. In order to make full use of the advantages offered by these machines and avoid excessive eddy current losses in windings, advanced technologies for winding conductors need to be employed to suppress the eddy effect, such as the Litz wire and printed circuit board (PCB). In this paper, the best practices for designing Litz wire/PCB windings are discussed and a brief survey of state of the art PCB winding technology is provided. Three coreless AFPM machines are mainly considered. A design optimization procedure based on the multi-objective differential evolution algorithm and 3-dimensional (3D) finite element analysis (FEA) is proposed to take into account the ac winding losses of Litz wires and PCB traces in the machine design stage. Selected designs are being prototyped and will be tested with a customized test fixture. 

   more » « less
3. Analytical Method to Approximate the Impact of Turning on the Macroscopic Fundamental Diagram

   https://doi.org/10.1177/0361198120933274  

   Xu, Guanhao; Yu, Zhengyao; Gayah, Vikash V. (September 2020, Transportation Research Record: Journal of the Transportation Research Board)

   null (Ed.)

   Network macroscopic fundamental diagrams (MFDs) have recently been shown to exist in real-world urban traffic networks. The existence of an MFD facilitates the modeling of urban traffic network dynamics at a regional level, which can be used to identify and refine large-scale network-wide control strategies. To be useful, MFD-based modeling frameworks require an estimate of the functional form of a network’s MFD. Analytical methods have been proposed to estimate a network’s MFD by abstracting the network as a single ring-road or corridor and modeling the flow–density relationship on that simplified element. However, these existing methods cannot account for the impact of turning traffic, as only a single corridor is considered. This paper proposes a method to estimate a network’s MFD when vehicles are allowed to turn into or out of a corridor. A two-ring abstraction is first used to analyze how turning will affect vehicle travel in a more general network, and then the model is further approximated using a single ring-road or corridor. This approximation is useful as it facilitates the application of existing variational theory-based methods (the stochastic method of cuts) to estimate the flow–density relationship on the corridor, while accounting for the stochastic nature of turning. Results of the approximation compared with a more realistic simulation that includes features that cannot be captured using variational theory—such as internal origins and destinations—suggest that this approximation works to estimate a network’s MFD when turning traffic is present. 

   more » « less
4. On the impacts of roadway hierarchy on the network Macroscopic Fundamental Diagram

   Xu, Guanhao; Gayah, Vikash V. (January 2021, 100th Annual Meeting of the Transportation Research Board)

   null (Ed.)

   Relationships between average network productivity and accumulation or density aggregated 2 across spatially compact regions of urban networks—so called network Macroscopic Fundamental 3 Diagrams (MFDs)—have recently been shown to exist. Various analytical methods have been put 4 forward to estimate a network’s MFD as a function of network properties, such as average block 5 lengths, signal timings, and traffic flow characteristics on links. However, real street networks are 6 not homogeneous—they generally have a hierarchical structure where some streets (e.g., arterials) 7 promote higher mobility than others (e.g., local roads). This paper provides an analytical method 8 to estimate the MFDs of hierarchical street networks by considering features that are specific to 9 hierarchical network structures. Since the performance of hierarchical networks is driven by how 10 vehicles are routed across the different street types, two routing conditions— user equilibrium and 11 system optimal routing—are considered in the analytical model. The proposed method is first 12 implemented to describe the MFD of a hierarchical one-way limited access linear corridor and 13 then extended to a more realistic hierarchical two-dimensional grid network. For both cases, it is 14 shown that the MFD of a hierarchical network may no longer be unimodal or concave as 15 traditionally assumed in most MFD-based modeling frameworks. These findings are verified using 16 simulations of hierarchical corridors. Finally, the proposed methodology is applied to demonstrate 17 how it can be used to make decisions related to the design of hierarchical street network structures. 

   more » « less
5. Cytokine-overexpressing dendritic cells for cancer immunotherapy

   https://doi.org/10.1038/s12276-024-01353-5  

   Han, Joonsu; Wang, Hua (December 2024, Experimental & Molecular Medicine)

   Abstract Dendritic cells (DCs), the main type of antigen-presenting cells in the body, act as key mediators of adaptive immunity by sampling antigens from diseased cells for the subsequent priming of antigen-specific T and B cells. While DCs can secrete a diverse array of cytokines that profoundly shape the immune milieu, exogenous cytokines are often needed to maintain the survival, proliferation, and differentiation of DCs, T cells, and B cells. However, conventional cytokine therapies for cancer treatment are limited by their low therapeutic benefit and severe side effects. The overexpression of cytokines in DCs, followed by paracrine release or membrane display, has emerged as a viable approach for controlling the exposure of cytokines to interacting DCs and T/B cells. This approach can potentially reduce the necessary dose of cytokines and associated side effects to achieve comparable or enhanced antitumor efficacy. Various strategies have been developed to enable the overexpression or chemical conjugation of cytokines on DCs for the subsequent modulation of DC–T/B-cell interactions. This review provides a brief overview of strategies that enable the overexpression of cytokines in or on DCs via genetic engineering or chemical modification methods and discusses the promise of cytokine-overexpressing DCs for the development of new-generation cancer immunotherapy. 

   more » « less