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1IEEE SIGNAL PROCESSING MAGAZINE | January 2019 |

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Contents

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Digital Object Identifier 10.1109/MSP.2019.2936748

IEEE SIGNAL PROCESSING MAGAZINE (ISSN 1053-5888) (ISPREG) is published bimonthly by the Institute of Electrical and Electronics Engineers, Inc., 3 Park Avenue, 17th Floor, New York, NY 10016-5997 USA (+1 212 419 7900). Responsibility for the contents rests upon the authors and not the IEEE, the Society, or its members. Annual member subscriptions included in Society fee. Nonmember subscriptions available upon request. Individual copies: IEEE Members US$20.00 (first copy only), nonmembers US$241.00 per copy. Copyright and Reprint Permissions: Abstracting is permitted with credit to the source. Libraries are permitted to photocopy beyond the limits of U.S. Copyright Law for private use of patrons: 1) those post-1977 articles that carry a code at the bottom of the first page, provided the per-copy fee indicated in the code is paid through the Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923 USA; 2) pre-1978 articles without fee. Instructors are permitted to photocopy isolated articles for noncommercial classroom use without fee. For all other copying, reprint, or republication permission, write to IEEE Service Center, 445 Hoes Lane, Piscataway, NJ 08854 USA. Copyright © 2019 by the Institute of Electrical and Electronics Engineers, Inc. All rights reserved. Periodicals postage paid at New York, NY, and at additional mailing offices. Postmaster: Send address changes to IEEE Signal Processing Magazine, IEEE, 445 Hoes Lane, Piscataway, NJ 08854 USA. Canadian GST #125634188 Printed in the U.S.A.

1IEEE SIGNAL PROCESSING MAGAZINE | November 2019 |

12 FROM THE GUEST EDITORSOsvaldo Simeone, Bipin Rajendran, André Grüning, Evangelos S. Eleftheriou, Mike Davies, Sophie Deneve, and Guang-Bin Huang

16 THE IMPORTANCE OF SPACE AND TIME FOR SIGNAL PROCESSING IN NEUROMORPHIC AGENTSGiacomo Indiveri and Yulia Sandamirskaya

29 EVENT-DRIVEN SENSING FOR EFFICIENT PERCEPTIONShih-Chii Liu, Bodo Rueckauer, Enea Ceolini, Adrian Huber,  and Tobi Delbruck

38 SIGNAL PROCESSING FOUNDATIONS FOR TIME-BASED SIGNAL REPRESENTATIONSNoyan C. Sevüktekin, Lav R. Varshney, Pavan K. Hanumolu, and Andrew C. Singer

SPECIAL SECTIONLEARNING ALGORITHMS AND SIGNAL PROCESSING FOR BRAIN-INSPIRED COMPUTING

ON THE COVER

COVER IMAGE: ©ISTOCKPHOTO.COM/VERTIGO3D

This special issue of IEEE Signal Processing Magazine examines the role of signal processing in neuromorphic computing and brings together key researchers to pro-vide readers with up-to-date and survey-style articles on algorithmic, hardware, and neuroscience perspectives on the state-of-the-art aspects of this emerging field.

51 SURROGATE GRADIENT LEARNING IN SPIKING NEURAL NETWORKSEmre O. Neftci, Hesham Mostafa, and Friedemann Zenke

64 AN INTRODUCTION TO PROBABILISTIC SPIKING NEURAL NETWORKSHyeryung Jang, Osvaldo Simeone, Brian Gardner, and André Grüning

78 SPIKING RESERVOIR NETWORKSNicholas Soures and Dhireesha Kudithipudi

88 NEUROSCIENCE-INSPIRED ONLINE UNSUPERVISED LEARNING ALGORITHMSCengiz Pehlevan and Dmitri B. Chklovskii

97 LOW-POWER NEUROMORPHIC HARDWARE FOR SIGNAL PROCESSING APPLICATIONSBipin Rajendran, Abu Sebastian, Michael Schmuker, Narayan Srinivasa, and Evangelos Eleftheriou

8 Special Reports Medicine on the Move John Edwards

125 Applications Corner A Signal Processing Perspective

of Monitoring Active Volcanoes Muhammad Salman Khan,

Millaray Curilem, Fernando Huenupán, Muhammad Farhan Khan, and Néstor Becerra Yoma

COLUMNS

111 SPEECH PROCESSING FOR DIGITAL HOME ASSISTANTSReinhold Haeb-Umbach, Shinji Watanabe, Tomohiro Nakatani, Michiel Bacchiani, Björn Hoffmeister, Michael L. Seltzer, Heiga Zen, and Mehrez Souden

FEATURE

IEEE SIGNAL PROCESSING MAGAZINE | January 2019 |

EDITOR-IN-CHIEFRobert W. Heath, Jr.—The University of Texas

at Austin, U.S.A.

AREA EDITORSFeature ArticlesMatthew McKay—Hong Kong University of Science

and Technology, Hong Kong SAR of ChinaSpecial IssuesNamrata Vaswani—Iowa State University, U.S.A.Columns and ForumRodrigo Capobianco Guido—São Paulo

State University (UNESP), BrazilRoberto Togneri—The University of Western

Australiae-NewsletterErvin Sejdic—University of Pittsburgh, U.S.A.Social Media and OutreachTiago Henrique Falk—INRS, CanadaSpecial InitiativesAndres Kwasinski—Rochester Institute of

Technology, U.S.A.Nuria Gonzalez Prelcic—Universidade de Vigo,

Spain

EDITORIAL BOARDDaniel Bliss—Arizona State University, U.S.ADanijela Cabric—University of California, U.S.A.Volkan Cevher—École polytechnique fédérale de

Lausanne, SwitzerlandMrityunjoy Chakraborty—Indian Institute of

Technology, Kharagpur, IndiaGeorge Chrisikos—Qualcomm, Inc., U.S.A.Elza Erkip—New York University, U.S.A.Alfonso Farina—Leonardo S.p.A., Italy B. Vikrham Gowreesunker—Texas Instruments

Inc., U.S.A.Joseph Guerci—Information Systems

Laboratories, Inc., U.S.A.Nageen Himayat—Intel, U.S.A.Clem Karl—Boston University, U.S.A.C.-C. Jay Kuo—University of Southern California,

U.S.A.Erik Larsson—Linköping University, SwedenDavid Love—Purdue University, U.S.AMaria G. Martini—Kingston University, U.K.Helen Meng—The Chinese University

of Hong Kong, China Meinard Mueller—Friedrich-Alexander Universität

Erlangen-Nürnberg, GermanyPhillip A. Regalia—U.S. National Science

Foundation Alejandro Ribeiro—University of Pennsylvania,

U.S.A.Douglas O’Shaughnessy—INRS Universite de

Recherche, CanadaOsvaldo Simeone—Kings College London, U.K.Milica Stojanovic—Northeastern University, U.S.AAnanthram Swami, Army Research Labs, U.S.A.Jong Chul Ye—KAIST, South KoreaQing Zhao—Cornell University, U.S.AJosiane Zerubia—INRIA Sophia-Antipolis

Mediterranee, France

ASSOCIATE EDITORS—COLUMNS AND FORUM Ivan Bajic—Simon Fraser University, CanadaBalázs Bank—Budapest University of Technology

and Economics, HungaryPanayiotis (Panos) Georgiou—University of

Southern California, U.S.A.Hana Godrich—Rutgers University, U.S.A.Yuan-Hao Huang—National Tsing Hua University,

TaiwanEuee Seon Jang—Hanyang University,

South KoreaVishal M.Patel—Rutgers University, U.S.A.Christian Ritz—University of Wollongong, AustraliaChangshui Zhang—Tsinghua University, ChinaH. Vicky Zhao—Tsinghua University, China

ASSOCIATE EDITORS—e-NEWSLETTERNesreen Ahmed—Intel, U.S.A.Behnaz Ghoraani—Florida Atlantic University, U.S.A.Anubha Gupta—IIIT Delhi, IndiaYang Li—Harbin Institute of Technology, ChinaAlessio Medda—Georgia Tech Research Institute,

U.S.A.Irena Orovic—University of Montenegro, PodgoricaSarah Ostadabbas—Northeastern University, U.S.A.Ronen Talmon—Technion, Israel

ASSOCIATE EDITOR—SOCIAL MEDIA/OUTREACHGuijin Wang—Tsinghua University, China

IEEE SIGNAL PROCESSING SOCIETYAli H. Sayed—PresidentAhmed Tewfik—President-ElectFernando Pereira—Vice President, ConferencesNikos D. Sidiropoulos—Vice President, MembershipSergio Theodoridis—Vice President, Publications Tülay Adalı—Vice President,

Technical Directions

IEEE SIGNAL PROCESSING SOCIETY STAFFWilliam Colacchio—Senior Manager, Publications

and Education Strategy and ServicesRebecca Wollman—Publications Administrator

IEEE PERIODICALS MAGAZINES DEPARTMENTJessica Welsh, Managing EditorGeraldine Krolin-Taylor,

Senior Managing EditorJanet Dudar, Senior Art DirectorGail A. Schnitzer, Associate Art DirectorTheresa L. Smith, Production CoordinatorMark David, Director, Business Development -

Media & AdvertisingFelicia Spagnoli, Advertising Production ManagerPeter M. Tuohy, Production DirectorKevin Lisankie, Editorial Services DirectorDawn M. Melley, Staff Director,

Publishing Operations

SCOPE: IEEE Signal Processing Magazine publishes tutorial-style articles on signal processing research and applications as well as columns and forums on issues of interest. Its coverage ranges from fundamental principles to practical implementation, reflecting the multidimensional facets of interests and concerns of the community. Its mission is to bring up-to-date, emerging and active technical developments, issues, and events to the research, educational, and professional communities. It is also the main Society communication platform addressing important issues concerning all members.

IEEE Signal Processing Magazine

Digital Object Identifier 10.1109/MSP.2019.2936749

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IEEE prohibits discrimination, harassment, and bullying. For more information, visit http://www.ieee.org/web/aboutus/whatis/policies/p9-26.html.

Promoting Sustainable Forestry

SFI-01681

IEEE SIGNAL PROCESSING MAGAZINE | November 2019 |

DEPARTMENTS 3 From the Editor Organizing a Special Issue of IEEE SPM Robert W. Heath, Jr.

5 President’s Message “Guilty of the Good We Did Not Do” Ali H. Sayed

166 Dates Ahead

133 Lecture Notes Understanding the Basis of Graph

Signal Processing via an Intuitive Example-Driven Approach

Ljubiša Stankovic, Danilo P. Mandic, Miloš Dakovic, Ilya Kisil, Ervin Sejdic, and Anthony G. Constantinides

Elucidating the Auxiliary Particle Filter via Multiple Importance Sampling

Víctor Elvira, Luca Martino, Mónica F. Bugallo, and Petar M. Djuric

The Superposition Principle of Linear Time-Invariant Systems

Ming Zhang and Anxue Zhang

157 Tips & Tricks A Fast, Accurate, and Separable Method

for Fitting a Gaussian Function Ibrahim Al-Nahhal, Octavia A. Dobre,

Ertugrul Basar, Cecilia Moloney, and Salama Ikki

168 In the Spotlight The Industry Digital Signal Processing

Technology Standing Committee Mike Polley and Fa-Long Luo

The IEEE International Conference on Image Processing will be held 25–28 October 2020 in Abu Dhabi, United Arab Emirates.

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