human: Given a node-centered hypergraph: <hypergraph>, where nodes represent papers and hyperedges represent sets of papers co-cited by a source paper.

Details of the hypergraph:
Center node: "transient stability guarantees for ad hoc dc microgrids"
  Abstract: Ad hoc electrical networks are formed by connecting power sources and loads without planning the interconnection structure (topology) in advance. They are designed to be installed and operated by individual communities—without central oversight—and as a result are well-suited to addressing the lack of electricity access in rural and developing areas. However, ad hoc networks are not widely used, and a major technical challenge impeding their development (and deployment) is the difficulty of certifying network stability without  a priori  knowledge of the topology. We develop conditions on individual power sources and loads such that a microgrid comprised of many units will be stable. We use Brayton–Moser potential theory to develop design constraints on individual microgrid components that certify transient stability—guaranteeing that the system will return to a suitable equilibrium after load switching events. Our central result is that stability can be ensured by installing a parallel capacitor at each constant power load, and we derive an expression for the required capacitance.

Connected through hyperedge HE-1 (induced by source paper "differentiation and passivity for control of brayton moser systems"):
  with members:
    - "krasovskii s passivity"
    - "robust passivity based control of boost converters in dc microgrids"
    - "differential passivity like properties for a class of nonlinear systems"
    - "on differential passivity of physical systems"

Connected through hyperedge HE-2 (induced by source paper "power controlled hamiltonian systems application to electrical systems with constant power loads"):
  with members:
    - "stability and frequency regulation of inverters with capacitive inertia"
    - "conditions on shifted passivity of port hamiltonian systems"
    - "nonlinear analysis of an improved swing equation"

Connected through hyperedge HE-3 (induced by source paper "active damping of a dc network with a constant power load an adaptive passivity based control approach"):
  with members:
    - "power controlled hamiltonian systems application to electrical systems with constant power loads"

Connected through hyperedge HE-4 (induced by source paper "making the grid truly smart autonomous system identification in modemless dc microgrids"):
  with members:
    - "multiuser communication through power talk in dc microgrids"
    - "power talk for multibus dc microgrids creating and optimizing communication channels"
    - "modemless multiple access communications over powerlines for dc microgrid control"
    - "power talk how to modulate data over a dc micro grid bus using power electronics"
    - "multi agent distributed optimization via inexact consensus admm"
    - "for the grid and through the grid the role of power line communications in the smart grid"

Question: Please tell me which class the center node belongs to. The 40 classes are: cs.NA(Numerical Analysis), cs.MM(Multimedia), cs.LO(Logic in Computer Science), cs.CY(Computers and Society), cs.CR(Cryptography and Security), cs.DC(Distributed, Parallel, and Cluster Computing), cs.HC(Human-Computer Interaction), cs.CE(Computational Engineering, Finance, and Science), cs.NI(Networking and Internet Architecture), cs.CC(Computational Complexity), cs.AI(Artificial Intelligence), cs.MA(Multiagent Systems), cs.GL(General Literature), cs.NE(Neural and Evolutionary Computing), cs.SC(Symbolic Computation), cs.AR(Hardware Architecture), cs.CV(Computer Vision and Pattern Recognition), cs.GR(Graphics), cs.ET(Emerging Technologies), cs.SY(Systems and Control), cs.CG(Computational Geometry), cs.OH(Other Computer Science), cs.PL(Programming Languages), cs.SE(Software Engineering), cs.LG(Machine Learning), cs.SD(Sound), cs.SI(Social and Information Networks), cs.RO(Robotics), cs.IT(Information Theory), cs.PF(Performance), cs.CL(Computation and Language), cs.IR(Information Retrieval), cs.MS(Mathematical Software), cs.FL(Formal Languages and Automata Theory), cs.DS(Data Structures and Algorithms), cs.OS(Operating Systems), cs.GT(Computer Science and Game Theory), cs.DB(Databases), cs.DL(Digital Libraries), cs.DM(Discrete Mathematics). Directly output the class name.

gpt: cs.SY(Systems and Control)