0
Your cart

Your cart is empty

Browse All Departments
Price
  • R50 - R100 (4)
  • R100 - R250 (294)
  • R250 - R500 (1,711)
  • R500+ (34,386)
  • -
Status
Format
Author / Contributor
Publisher

Books > Professional & Technical > Electronics & communications engineering

Basic AC Circuits (Paperback, 2nd edition): Clay Rawlins Basic AC Circuits (Paperback, 2nd edition)
Clay Rawlins
R1,621 Discovery Miles 16 210 Ships in 10 - 15 working days

Basic AC Circuits, 2/E is a step-by-step approach to AC circuit technology for the beginning student, hobbyist, technician, or engineer. The book is built into a series of self-paced, individualized learning goals covering electronics concepts, terms and the mathematics required to fully understand AC circuit problems--simple or complex. Each chapter includes learning objectives, fully-illustrated examples, practice problems and quizzes providing teachers, trainers and students a complete AC technology resource. Basic AC Circuits, 2/E has been a staple of the electronics educational market since 1981, but in the new edition the author has updated the book to reflect changes in technology, especially the test equipment available today.
Basic AC Circuits has been a keystone for curriculum plans around the country for nearly two decades. This book was originally part of the Texas Instruments series published by Sams Publishing.
Provides a fully-revised introduction to AC circuit technology that includes full examples, practice problems and quizzes to measure learning
Includes the mathematics training for AC circuit design that so many technicians and engineers are missing
Written in an easy-to-read and follow format with many illustrations, examples, and hands-on practice.

Nanowires for Energy Applications, Volume 98 (Hardcover): Sudha Mokkapati, Chennupati Jagadish Nanowires for Energy Applications, Volume 98 (Hardcover)
Sudha Mokkapati, Chennupati Jagadish
R5,273 Discovery Miles 52 730 Ships in 10 - 15 working days

Nanowires for Energy Applications, Volume 98, covers the latest breakthrough research and exciting developments in nanowires for energy applications. This volume focuses on various aspects of Nanowires for Energy Applications, presenting interesting sections on Electrospun semiconductor metal oxide nanowires for energy and sensing applications, Integration into flexible and functional materials, Nanowire Based Bulk Heterojunction Solar Cells, Semiconductor Nanowires for Thermoelectric Generation, Energy Scavenging: Mechanical, Thermoelectric, and Nanowire synthesis/growth methods, and more.

Industrial Electronics for Engineers, Chemists, and Technicians - With Optional Lab Experiments (Hardcover): Daniel J.... Industrial Electronics for Engineers, Chemists, and Technicians - With Optional Lab Experiments (Hardcover)
Daniel J. Shanefield
R1,850 Discovery Miles 18 500 Ships in 10 - 15 working days

Turn to this multipurpose reference for a practical understanding of electronics in the factory or laboratory. It's perfect for people who are not electrical engineers but who need to use electronic equipment every day at work. Avoid or solve common problems in the use of electronics in the factory or lab and optimize the use of measurement and control equipment with this helpful resource
The guide is easy to understand by anyone who has taken a high school physics courseuyet it provides quick, specific solutions for such electronics issues as feedback oscillation, ground loops, impedance mismatch, noise pickup, and optimization of PID controllers.
Use Industrial Electronics as a hands-on resource to handle typical electronics questions as they arise, as a self-study text to provide a broad background for understanding general electronics issues and design, or even for an instructor-led, on-the-job training course in shop or lab electronics. Because of the highly detailed explanations in the book, instructors themselves do not need to be experts. Of course, the volume is perfect for use as a textbook in college and vocational school courses.
The laboratory experiments are optional and may be used merely as examples. Components are inexpensive and can be obtained from consumer electronics stores such as Radio Shack or from electronics suppliers on the Web. The circuit diagrams are greatly simplified and completely understandable, with every component explained."

Automation, Control and Intelligent Systems (Hardcover): Alfred Silva Automation, Control and Intelligent Systems (Hardcover)
Alfred Silva
R3,061 R2,776 Discovery Miles 27 760 Save R285 (9%) Ships in 18 - 22 working days
Test Generation of Crosstalk Delay Faults in VLSI Circuits (Hardcover, 1st ed. 2019): S. Jayanthy, M.C. Bhuvaneswari Test Generation of Crosstalk Delay Faults in VLSI Circuits (Hardcover, 1st ed. 2019)
S. Jayanthy, M.C. Bhuvaneswari
R3,785 Discovery Miles 37 850 Ships in 18 - 22 working days

This book describes a variety of test generation algorithms for testing crosstalk delay faults in VLSI circuits. It introduces readers to the various crosstalk effects and describes both deterministic and simulation-based methods for testing crosstalk delay faults. The book begins with a focus on currently available crosstalk delay models, test generation algorithms for delay faults and crosstalk delay faults, before moving on to deterministic algorithms and simulation-based algorithms used to test crosstalk delay faults. Given its depth of coverage, the book will be of interest to design engineers and researchers in the field of VLSI Testing.

Communications and Computer Networks (Hardcover): Akira Hanako Communications and Computer Networks (Hardcover)
Akira Hanako
R3,249 R2,944 Discovery Miles 29 440 Save R305 (9%) Ships in 18 - 22 working days
Adaptive Blind Signal & Image Processing - Learning Algorithms & Applications (Hardcover): A Cichocki Adaptive Blind Signal & Image Processing - Learning Algorithms & Applications (Hardcover)
A Cichocki
R4,222 Discovery Miles 42 220 Ships in 10 - 15 working days

With solid theoretical foundations and numerous potential applications, Blind Signal Processing (BSP) is one of the hottest emerging areas in Signal Processing. This volume unifies and extends the theories of adaptive blind signal and image processing and provides practical and efficient algorithms for blind source separation, Independent, Principal, Minor Component Analysis, and Multichannel Blind Deconvolution (MBD) and Equalization. Containing over 1400 references and mathematical expressions Adaptive Blind Signal and Image Processing delivers an unprecedented collection of useful techniques for adaptive blind signal/image separation, extraction, decomposition and filtering of multi-variable signals and data.

  • Offers a broad coverage of blind signal processing techniques and algorithms both from a theoretical and practical point of view
  • Presents more than 50 simple algorithms that can be easily modified to suit the reader's specific real world problems
  • Provides a guide to fundamental mathematics of multi-input, multi-output and multi-sensory systems
  • Includes illustrative worked examples, computer simulations, tables, detailed graphs and conceptual models within self contained chapters to assist self study
  • Accompanying CD-ROM features an electronic, interactive version of the book with fully coloured figures and text. C and MATLAB user-friendly software packages are also provided
MATLAB is a registered trademark of The MathWorks, Inc.

By providing a detailed introduction to BSP, as well as presenting new results and recent developments, this informative and inspiring work will appeal to researchers, postgraduate students, engineers and scientists working in biomedical engineering,
communications, electronics, computer science, optimisations, finance, geophysics and neural networks.

X-Ray Spectroscopy (Hardcover): Shatendra K. Sharma X-Ray Spectroscopy (Hardcover)
Shatendra K. Sharma
R3,126 Discovery Miles 31 260 Ships in 18 - 22 working days
Handbook of Microelectromechanical Systems (Hardcover): Eve Versuh Handbook of Microelectromechanical Systems (Hardcover)
Eve Versuh
R2,380 Discovery Miles 23 800 Ships in 10 - 15 working days
A-GPS - Assisted GPS, GNSS, and SBAS (Hardcover): Frank van Diggelen A-GPS - Assisted GPS, GNSS, and SBAS (Hardcover)
Frank van Diggelen
R3,001 Discovery Miles 30 010 Ships in 18 - 22 working days

Today, increasing demands and expectations are being placed on GPS systems. Assisted GPS (A-GPS) has been developed to provide greatly improved capabilities, helping GPS work better and faster in almost any location. Offering a detailed look at all the technical aspects and underpinnings of A-GPS, this unique book places emphasis on practical implementation. The book reviews standard GPS design, helping professionals understand why GPS requires assistance in the first place. Readers discover how A-GPS enables the computing of a position from navigation satellites in the absence of precise time - a topic not covered in any other book. Moreover, engineers learn how to design and analyze a high sensitivity GPS receiver and determine the achievable sensitivity of a GPS receiver.

Bismuth-Containing Alloys and Nanostructures (Hardcover, 1st ed. 2019): Shumin Wang, Pengfei Lu Bismuth-Containing Alloys and Nanostructures (Hardcover, 1st ed. 2019)
Shumin Wang, Pengfei Lu
R4,072 Discovery Miles 40 720 Ships in 18 - 22 working days

This book focuses on novel bismuth-containing alloys and nanostructures, covering a wide range of materials from semiconductors, topological insulators, silica optical fibers and to multiferroic materials. It provides a timely overview of bismuth alloys and nanostructures, from material synthesis and physical properties to device applications and also includes the latest research findings. Bismuth is considered to be a sustainable and environmentally friendly element, and has received increasing attention in a variety of innovative research areas in recent years. The book is intended as a reference resource and textbook for graduate students and researchers working in these fields.

International Code of Signals - For Visual, Sound, and Radio Communication (Hardcover): Nima International Code of Signals - For Visual, Sound, and Radio Communication (Hardcover)
Nima
R909 R793 Discovery Miles 7 930 Save R116 (13%) Ships in 18 - 22 working days
Fixed-Time Cooperative Control of Multi-Agent Systems (Hardcover, 1st ed. 2019): Zongyu Zuo, Qinglong Han, Boda Ning Fixed-Time Cooperative Control of Multi-Agent Systems (Hardcover, 1st ed. 2019)
Zongyu Zuo, Qinglong Han, Boda Ning
R3,106 Discovery Miles 31 060 Ships in 18 - 22 working days

This monograph presents new theories and methods for fixed-time cooperative control of multi-agent systems. Fundamental concepts of fixed-time stability and stabilization are introduced with insightful understanding. This book presents solutions for several problems of fixed-time cooperative control using systematic design methods. The book compares fixed-time cooperative control with asymptotic cooperative control, demonstrating how the former can achieve better closed-loop performance and disturbance rejection properties. It also discusses the differences from finite-time control, and shows how fixed-time cooperative control can produce the faster rate of convergence and provide an explicit estimate of the settling time independent of initial conditions. This monograph presents multiple applications of fixed-time control schemes, including to distributed optimization of multi-agent systems, making it useful to students, researchers and engineers alike.

Current Progress in Artificial Intelligence (Hardcover): Mick Benson Current Progress in Artificial Intelligence (Hardcover)
Mick Benson
R3,230 R2,925 Discovery Miles 29 250 Save R305 (9%) Ships in 18 - 22 working days
Nonequilibrium Dynamics of Collective Excitations in Quantum Materials (Hardcover, 1st ed. 2018): Edoardo Baldini Nonequilibrium Dynamics of Collective Excitations in Quantum Materials (Hardcover, 1st ed. 2018)
Edoardo Baldini
R2,702 Discovery Miles 27 020 Ships in 18 - 22 working days

This book studies the dynamics of fundamental collective excitations in quantum materials, focusing on the use of state-of-the-art ultrafast broadband optical spectroscopy. Collective behaviour in solids lies at the origin of several cooperative phenomena that can lead to profound transformations, instabilities and phase transitions. Revealing the dynamics of collective excitations is a topic of pivotal importance in contemporary condensed matter physics, as it provides information on the strength and spatial distribution of interactions and correlation. The experimental framework explored in this book relies on setting a material out-of-equilibrium by an ultrashort laser pulse and monitoring the photo-induced changes in its optical properties over a broad spectral region in the visible or deep-ultraviolet. Collective excitations (e.g. plasmons, excitons, phonons...) emerge either in the frequency domain as spectral features across the probed range, or in the time domain as coherent modes triggered by the pump pulse. Mapping the temporal evolution of these collective excitations provides access to the hierarchy of low-energy phenomena occurring in the solid during its path towards thermodynamic equilibrium. This methodology is used to investigate a number of strongly interacting and correlated materials with an increasing degree of internal complexity beyond conventional band theory.

Wireless Positioning: Principles and Practice (Hardcover, 1st ed. 2019): Ian Sharp, Kegen Yu Wireless Positioning: Principles and Practice (Hardcover, 1st ed. 2019)
Ian Sharp, Kegen Yu
R5,606 Discovery Miles 56 060 Ships in 10 - 15 working days

This book focuses on non-GNSS positioning systems and approaches. Although it addresses both theoretical and practical aspects, the primary focus is on engineering practice. This is achieved by providing in-depth studies on a number of major topics such as tracking system architecture, link budget, system design, implementation, testing, and performance evaluation. It studies four positioning application cases in detail: covert vehicle tracking, horse racing, rowing, and tracking for field sports. Its comprehensive and systematic treatment of practical issues in wireless positioning makes the book particularly suitable for readers who are interested in learning about practical wireless positioning solutions. It will also benefit researchers, engineers and graduate students in fields such as positioning and navigation, geospatial engineering and telecommunications.

Optical Switching - Device Technology and Applications in Networks (Hardcover): D Nandi Optical Switching - Device Technology and Applications in Networks (Hardcover)
D Nandi
R3,154 Discovery Miles 31 540 Ships in 18 - 22 working days

OPTICAL SWITCHING Comprehensive coverage of optical switching technologies and their applications in optical networks Optical Switching: Device Technology and Applications in Networks delivers an accessible exploration of the evolution of optical networks with clear explanations of the current state-of-the-art in the field and modern challenges in the development of Internet-of-Things devices. A variety of optical switches--including MEMS-based, magneto, photonic, and SOA-based--are discussed, as is the application of optical switches in networks. The book is written in a tutorial style, easily understood by both undergraduate and graduate students. It describes the fundamentals and recent developments in optical switch networks and examines the architectural and design challenges faced by those who design and construct emerging optical switch networks, as well as how to overcome those challenges. The book offers ways to assess and analyze systems and applications, comparing a variety of approaches available to the reader. It also provides: A thorough introduction to switch characterization, including optical, electro optical, thermo optical, magneto optical, and acoustic-optic switches Comprehensive explorations of MEMS-based, SOA-based, liquid crystal, photonic crystal, and optical electrical optical (OEO) switches Practical discussions of quantum optical switches, as well as nonlinear optical switches In-depth examinations of the application of optical switches in networks, including switch fabric control and optical switching for high-performance computing Perfect for researchers and professionals in the fields of telecommunications, Internet of Things, and optoelectronics, Optical Switching: Device Technology and Applications in Networks will also earn a place in the libraries of advanced undergraduate and graduate students studying optical networks, optical communications, and sensor applications.

Memristor Technology: Synthesis and Modeling for Sensing and Security Applications (Hardcover, 1st ed. 2018): Heba Abunahla,... Memristor Technology: Synthesis and Modeling for Sensing and Security Applications (Hardcover, 1st ed. 2018)
Heba Abunahla, Baker Mohammad
R2,641 Discovery Miles 26 410 Ships in 18 - 22 working days

This book provides readers with a single-source guide to fabricate, characterize and model memristor devices for sensing applications. The authors describe a correlated, physics-based model to simulate and predict the behavior of devices fabricated with different oxide materials, active layer thickness, and operating temperature. They discuss memristors from various perspectives, including working mechanisms, different synthesis methods, characterization procedures, and device employment in radiation sensing and security applications.

Supervised and Unsupervised Learning for Data Science (Hardcover, 1st ed. 2020): Michael W. Berry, Azlinah Mohamed, Bee Wah Yap Supervised and Unsupervised Learning for Data Science (Hardcover, 1st ed. 2020)
Michael W. Berry, Azlinah Mohamed, Bee Wah Yap
R2,533 Discovery Miles 25 330 Ships in 10 - 15 working days

This book covers the state of the art in learning algorithms with an inclusion of semi-supervised methods to provide a broad scope of clustering and classification solutions for big data applications. Case studies and best practices are included along with theoretical models of learning for a comprehensive reference to the field. The book is organized into eight chapters that cover the following topics: discretization, feature extraction and selection, classification, clustering, topic modeling, graph analysis and applications. Practitioners and graduate students can use the volume as an important reference for their current and future research and faculty will find the volume useful for assignments in presenting current approaches to unsupervised and semi-supervised learning in graduate-level seminar courses. The book is based on selected, expanded papers from the Fourth International Conference on Soft Computing in Data Science (2018). Includes new advances in clustering and classification using semi-supervised and unsupervised learning; Address new challenges arising in feature extraction and selection using semi-supervised and unsupervised learning; Features applications from healthcare, engineering, and text/social media mining that exploit techniques from semi-supervised and unsupervised learning.

Inverse Synthetic Aperture Radar Imaging With MATL AB Algorithms, Second Edition (Hardcover, 2nd Edition): C Ozdemir Inverse Synthetic Aperture Radar Imaging With MATL AB Algorithms, Second Edition (Hardcover, 2nd Edition)
C Ozdemir
R3,097 Discovery Miles 30 970 Ships in 18 - 22 working days

Build your knowledge of SAR/ISAR imaging with this comprehensive and insightful resource The newly revised Second Edition of Inverse Synthetic Aperture Radar Imaging with MATLAB Algorithms covers in greater detail the fundamental and advanced topics necessary for a complete understanding of inverse synthetic aperture radar (ISAR) imaging and its concepts. Distinguished author and academician, Caner OEzdemir, describes the practical aspects of ISAR imaging and presents illustrative examples of the radar signal processing algorithms used for ISAR imaging. The topics in each chapter are supplemented with MATLAB codes to assist readers in better understanding each of the principles discussed within the book. This new edition incudes discussions of the most up-to-date topics to arise in the field of ISAR imaging and ISAR hardware design. The book provides a comprehensive analysis of advanced techniques like Fourier-based radar imaging algorithms, and motion compensation techniques along with radar fundamentals for readers new to the subject. The author covers a wide variety of topics, including: Radar fundamentals, including concepts like radar cross section, maximum detectable range, frequency modulated continuous wave, and doppler frequency and pulsed radar The theoretical and practical aspects of signal processing algorithms used in ISAR imaging The numeric implementation of all necessary algorithms in MATLAB ISAR hardware, emerging topics on SAR/ISAR focusing algorithms such as bistatic ISAR imaging, polarimetric ISAR imaging, and near-field ISAR imaging, Applications of SAR/ISAR imaging techniques to other radar imaging problems such as thru-the-wall radar imaging and ground-penetrating radar imaging Perfect for graduate students in the fields of electrical and electronics engineering, electromagnetism, imaging radar, and physics, Inverse Synthetic Aperture Radar Imaging With MATLAB Algorithms also belongs on the bookshelves of practicing researchers in the related areas looking for a useful resource to assist them in their day-to-day professional work.

Processing of 'Wide Band Gap Semiconductors (Hardcover): Stephen J. Pearton Processing of 'Wide Band Gap Semiconductors (Hardcover)
Stephen J. Pearton
R3,851 Discovery Miles 38 510 Ships in 10 - 15 working days

Wide bandgap semiconductors, made from such materials as GaN, SiC, diamond and ZnSe, are undergoing a strong resurgence in recent years, principally because of their direct bandgaps which give them a huge advantage over the indirect gap SiC. As an example, more than 10 million blue LEDs using this technology are sold each month, and new, high-brightness (15 lumens per watt), very-long-lifetime white LEDs are under development with the potential to replace incandescent bulbs in many situations.

WIDE BANDGAP SEMICONDUCTORS provides readers with a broad overview of this rapidly expanding technology, bringing them up to speed on new discoveries and commercial applications. It provides specific technical explanations of key processes such as laser diodes, LEDs and very high temperature electronic controls on engines, focusing on doping, etching, oxidation passivation, growth techniques, and more...

The volume also explores the potential use of these semiconductors in HDTV, power conditioning devices, and high power microwave applications. The contributors are all experts in the fields of growth, processing, and characterization of these semiconductors, including II-VI compounds, processing techniques for SiC, GaN and diamond, and materials analysis of all wide gap semiconductors.

Key Features:

- Explains the development and advantages of broadgap semiconductors, showing their increasing power and their increasingly broader use in commercial and military products

- Features step-by-step explanations of key processes in the fabrication of the semiconductors, including chemistry, testing, design, and more

- Explores the need for advanced electronics capable of operation at 6000C and how silicon-on-insulator technology will meet this need

- Provides an understanding of semiconductor chemistry, thermodynamics and etching, along with technical explanations of common devices, descriptions of processing equipment and techniques, impurity testing, implantation damage, and more

Airborne Maritime Surveillance Radar, Volume 1 - British ASV radars in WWII 1939-1945 (Paperback): Simon Watts Airborne Maritime Surveillance Radar, Volume 1 - British ASV radars in WWII 1939-1945 (Paperback)
Simon Watts
R752 Discovery Miles 7 520 Ships in 10 - 15 working days

Today, air-to-surface vessel (ASV) radars, or more generally airborne maritime surveillance radars, are installed on maritime reconnaissance aircraft for long-range detection, tracking and classification of surface ships (ASuW-anti-surface warfare) and for hunting submarines (ASW-anti-submarine warfare). Such radars were first developed in the UK during WWII as part of the response to the threat to shipping from German U-boats. This book describes the ASV radars developed in the UK and used by RAF Coastal Command during WWII for long-range maritime surveillance.

Airborne Maritime Surveillance Radar, Volume 2 - Post-war British ASV radars 1946-2000 (Paperback): Simon Watts Airborne Maritime Surveillance Radar, Volume 2 - Post-war British ASV radars 1946-2000 (Paperback)
Simon Watts
R752 Discovery Miles 7 520 Ships in 10 - 15 working days

Today, air-to-surface vessel (ASV) radars, or more generally maritime surveillance radars, are installed on maritime reconnaissance aircraft for long-range detection, tracking and classification of surface ships (ASuW-anti-surface warfare) and for hunting submarines (ASW-anti-submarine warfare). Such radars were first developed in the UK during WWII as part of the response to the threat to shipping from German U-Boats. This book describes the ASV radars developed in the UK after WWII (1946-2000) and used by the RAF for long-range maritime surveillance.

Hardware Accelerators in Data Centers (Hardcover, 1st ed. 2019): Christoforos Kachris, Babak Falsafi, Dimitrios Soudris Hardware Accelerators in Data Centers (Hardcover, 1st ed. 2019)
Christoforos Kachris, Babak Falsafi, Dimitrios Soudris
R3,812 Discovery Miles 38 120 Ships in 18 - 22 working days

This book provides readers with an overview of the architectures, programming frameworks, and hardware accelerators for typical cloud computing applications in data centers. The authors present the most recent and promising solutions, using hardware accelerators to provide high throughput, reduced latency and higher energy efficiency compared to current servers based on commodity processors. Readers will benefit from state-of-the-art information regarding application requirements in contemporary data centers, computational complexity of typical tasks in cloud computing, and a programming framework for the efficient utilization of the hardware accelerators.

CMOS Past, Present and Future (Paperback): Henry Radamson, Eddy Simoen, Jun Luo, Chao Zhao CMOS Past, Present and Future (Paperback)
Henry Radamson, Eddy Simoen, Jun Luo, Chao Zhao
R4,358 R4,049 Discovery Miles 40 490 Save R309 (7%) Ships in 10 - 15 working days

CMOS Past, Present and Future provides insight from the basics, to the state-of-the-art of CMOS processing and electrical characterization, including the integration of Group IV semiconductors-based photonics. The book goes into the pitfalls and opportunities associated with the use of hetero-epitaxy on silicon with strain engineering and the integration of photonics and high-mobility channels on a silicon platform. It begins with the basic definitions and equations, but extends to present technologies and challenges, creating a roadmap on the origins of the technology and its evolution to the present, along with a vision for future trends. The book examines the challenges and opportunities that materials beyond silicon provide, including a close look at high-k materials and metal gate, strain engineering, channel material and mobility, and contacts. The book's key approach is on characterizations, device processing and electrical measurements.

Free Delivery
Pinterest Twitter Facebook Google+
You may like...
Querying XML - XQuery, XPath, and…
Jim Melton, Stephen Buxton Paperback R1,479 Discovery Miles 14 790
Chronicles - The Second Book of
King James Hardcover R489 Discovery Miles 4 890
Expert ASP.NET 2.0 Advanced Application…
Tom Barnaby, Dominic Selly, … Hardcover R1,515 Discovery Miles 15 150
A True Estimate of Human Life. in Which…
Edward Young Paperback R416 Discovery Miles 4 160
The Tryal of the Witnesses of the…
Thomas Sherlock Paperback R376 Discovery Miles 3 760
Handbook of Research on Web Log Analysis
Bernard J Jansen, Amanda Spink, … Hardcover R6,726 Discovery Miles 67 260
Coding for Kids Ages 10 and Up - Coding…
Bob Mather Hardcover R866 Discovery Miles 8 660
The Origin of God
Laurence Gardner Hardcover R986 Discovery Miles 9 860
The Expediency of Some Divine…
William Parker Paperback R335 Discovery Miles 3 350
Proverbs - The Book of
King James Hardcover R482 Discovery Miles 4 820

 

Partners