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: "designing a high efficiency pulse width modulation step down dc dc converter for mobile phone applications"
  Abstract: This paper presents the design and analysis of a high efficiency, PWM (Pulse-Width-Modulation) Buck converters for mobile phone applications. The steady-state and average-value models for the proposed converter are developed and simulated. A practical design approach which aims at systematizing the procedure for the selection of the control parameters is introduced. The switching losses are reduced by using soft switching, additionally, a simple analog and digital form of the controller for practical realization is provided. It is found that this controller adopts a structure similar to the conventional PWM voltage mode controller. The proposed circuit uses a current-mode control and a voltage-to-pulse converter for the PWM. The circuit, fabricated using a 0.18-{\mu}m CMOS technology, reaches a peak load regulation of 20 mV/V and line regulation of 0.5 mV/V at Current load equal 300 mA. The used 10{\mu}H inductance and 22{\mu}F capacitor and requires clock and Vref/Vramp input of 1,23V.

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.OH(Other Computer Science)