Structural Damage Identification in Wind Turbine Blades Using Piezoelectric Active Sensing with Ultrasonic Validation

Download Structural Damage Identification in Wind Turbine Blades Using Piezoelectric Active Sensing with Ultrasonic Validation PDF Online Free

Author :
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (727 download)

DOWNLOAD NOW!


Book Synopsis Structural Damage Identification in Wind Turbine Blades Using Piezoelectric Active Sensing with Ultrasonic Validation by :

Download or read book Structural Damage Identification in Wind Turbine Blades Using Piezoelectric Active Sensing with Ultrasonic Validation written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper gives a brief overview of a new project at LANL in structural damage identification for wind turbines. This project makes use of modeling capabilities and sensing technology to understand realistic blade loading on large turbine blades, with the goal of developing the technology needed to automatically detect early damage. Several structural health monitoring (SHM) techniques using piezoelectric active materials are being investigated for the development of wireless, low power sensors that interrogate sections of the wind turbine blade using Lamb wave propagation data, frequency response functions (FRFs), and time-series analysis methods. The modeling and sensor research will be compared with extensive experimental testing, including wind tunnel experiments, load and fatigue tests, and ultrasonic scans - on small- to mid-scale turbine blades. Furthermore, this study will investigate the effect of local damage on the global response of the blade by monitoring low-frequency response changes.

Piezoelectric Active Sensing Techniques for Damage Detection on Wind Turbine Blades

Download Piezoelectric Active Sensing Techniques for Damage Detection on Wind Turbine Blades PDF Online Free

Author :
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (16 download)

DOWNLOAD NOW!


Book Synopsis Piezoelectric Active Sensing Techniques for Damage Detection on Wind Turbine Blades by :

Download or read book Piezoelectric Active Sensing Techniques for Damage Detection on Wind Turbine Blades written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Application of Piezoelectric Active-sensors for SHM of Wind Turbine Blades

Download Application of Piezoelectric Active-sensors for SHM of Wind Turbine Blades PDF Online Free

Author :
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (16 download)

DOWNLOAD NOW!


Book Synopsis Application of Piezoelectric Active-sensors for SHM of Wind Turbine Blades by :

Download or read book Application of Piezoelectric Active-sensors for SHM of Wind Turbine Blades written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of this study is to characterize the dynamic response of a CX-100 wind blade and the design parameters of SHM techniques as they apply to wind turbine blades, and to investigate the performance of high-frequency active-sensing SHM techniques, including lamb wave and frequency response functions, as a way to monitor the health of a wind turbine blade. The results of the dynamic characterization will be used to validate a numerical model and understand the effect of structural damage on the performance of the blades. The focus of SHM study is to assess and compare the performance of each method in identifying incipient damage, with a special consideration given to field deployability. For experiments, a 9-m CX-100 blade was used. Overall, the methods yielded sufficient damage detection to warrant further investigation into field deployment. This paper also summarizes the SHM results of a full-scale fatigue test of 9-m CX-100 blade using piezoelectric active-sensors.

Topics in Experimental Dynamics Substructuring and Wind Turbine Dynamics, Volume 2

Download Topics in Experimental Dynamics Substructuring and Wind Turbine Dynamics, Volume 2 PDF Online Free

Author :
Publisher : Springer Science & Business Media
ISBN 13 : 1461424216
Total Pages : 354 pages
Book Rating : 4.4/5 (614 download)

DOWNLOAD NOW!


Book Synopsis Topics in Experimental Dynamics Substructuring and Wind Turbine Dynamics, Volume 2 by : R. Mayes

Download or read book Topics in Experimental Dynamics Substructuring and Wind Turbine Dynamics, Volume 2 written by R. Mayes and published by Springer Science & Business Media. This book was released on 2012-04-11 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt: Topics in Experimental Dynamics Substructuring and Wind Turbine Dynamics, Volume 2, Proceedings of the 30th IMAC, A Conference and Exposition on Structural Dynamics, 2012, the second volume of six from the Conference, brings together 31 contributions to this important area of research and engineering. The collection presents early findings and case studies on fundamental and applied aspects of Structural Dynamics.

Piezoelectric Active Sensing Techniques for Damage Detection on the Wind Turbine Blades

Download Piezoelectric Active Sensing Techniques for Damage Detection on the Wind Turbine Blades PDF Online Free

Author :
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (16 download)

DOWNLOAD NOW!


Book Synopsis Piezoelectric Active Sensing Techniques for Damage Detection on the Wind Turbine Blades by :

Download or read book Piezoelectric Active Sensing Techniques for Damage Detection on the Wind Turbine Blades written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

SHM of Wind Turbine Blades Using Piezoelectric Active-sensors

Download SHM of Wind Turbine Blades Using Piezoelectric Active-sensors PDF Online Free

Author :
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (873 download)

DOWNLOAD NOW!


Book Synopsis SHM of Wind Turbine Blades Using Piezoelectric Active-sensors by :

Download or read book SHM of Wind Turbine Blades Using Piezoelectric Active-sensors written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper presents a variety of structural health monitoring (SHM) techniques, based on the use of piezoelectric active-sensors, used to determine the structural integrity of wind turbine blades. Specifically, Lamb wave propagations, frequency response functions, and time series based methods are utilized to estimate the condition of wind turbine blades. For experiments, a 1m section of a 9m CX100 blade is used. Overall, these three methods yielded a sufficient damage detection capability to warrant further investigation into field deployment. A full-scale fatigue test of a CX-100 wind turbine blade is also conducted. This paper summarizes considerations needed to design such SHM systems, experimental procedures and results, and practical implementation issues that can be used as guidelines for future investigations.

Acoustic Emission Signal Analysis and Damage Mode Identification of Composite Wind Turbine Blades

Download Acoustic Emission Signal Analysis and Damage Mode Identification of Composite Wind Turbine Blades PDF Online Free

Author :
Publisher : Elsevier
ISBN 13 : 0323886477
Total Pages : 366 pages
Book Rating : 4.3/5 (238 download)

DOWNLOAD NOW!


Book Synopsis Acoustic Emission Signal Analysis and Damage Mode Identification of Composite Wind Turbine Blades by : Pengfei Liu

Download or read book Acoustic Emission Signal Analysis and Damage Mode Identification of Composite Wind Turbine Blades written by Pengfei Liu and published by Elsevier. This book was released on 2023-05-20 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt: Acoustic Emission Signal Analysis and Damage Mode Identification of Composite Wind Turbine Blades covers both the underlying theory and various techniques for effective structural monitoring of composite wind turbine blades via acoustic emission signal analysis, helping readers solve critical problems such as noise elimination, defect detection, damage mode identification, and more. Author Pengfei Liu introduces techniques for identifying and analyzing progressive failure under tension, delamination, damage localization, adhesive composite joint failure, and other degradation phenomena, outlining methods such as time-difference, wavelet, machine learning, and more including combined methods. The disadvantages and advantages of using each method are covered as are techniques for different blade-lengths and various blade substructures. Piezoelectric sensors are discussed as is experimental analysis of damage source localization. The book also takes great lengths to let readers know when techniques and concepts discussed can be applied to composite materials and structures beyond just wind turbine blades. Features fundamental acoustic emission theories and techniques for monitoring the structural integrity of wind turbine blades Covers sensor arrangements, noise elimination, defect detection, and dominating damage mode identification using acoustic emission techniques Outlines the wavelet method, the time-difference defect detection method, and damage mode identification techniques using machine learning Discusses how the techniques covered can be extended and adapted for use in other composite structures under complex loads and in different environments

MARE-WINT

Download MARE-WINT PDF Online Free

Author :
Publisher : Springer
ISBN 13 : 3319390953
Total Pages : 432 pages
Book Rating : 4.3/5 (193 download)

DOWNLOAD NOW!


Book Synopsis MARE-WINT by : Wiesław Ostachowicz

Download or read book MARE-WINT written by Wiesław Ostachowicz and published by Springer. This book was released on 2016-08-30 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a holistic, interdisciplinary overview of offshore wind energy, and is a must-read for advanced researchers. Topics, from the design and analysis of future turbines, to the decommissioning of wind farms, are covered. The scope of the work ranges from analytical, numerical and experimental advancements in structural and fluid mechanics, to novel developments in risk, safety & reliability engineering for offshore wind.The core objective of the current work is to make offshore wind energy more competitive, by improving the reliability, and operations and maintenance (O&M) strategies of wind turbines. The research was carried out under the auspices of the EU-funded project, MARE-WINT. The project provided a unique opportunity for a group of researchers to work closely together, undergo multidisciplinary doctoral training, and conduct research in the area of offshore wind energy generation. Contributions from expert, external authors are also included, and the complete work seeks to bridge the gap between research and a rapidly-evolving industry.

Applications of Passive Vibration Control and Damage Detection in Composite Wind Turbine Blades

Download Applications of Passive Vibration Control and Damage Detection in Composite Wind Turbine Blades PDF Online Free

Author :
Publisher :
ISBN 13 : 9781321452037
Total Pages : 106 pages
Book Rating : 4.4/5 (52 download)

DOWNLOAD NOW!


Book Synopsis Applications of Passive Vibration Control and Damage Detection in Composite Wind Turbine Blades by : Jeffery Dwayne Tippmann

Download or read book Applications of Passive Vibration Control and Damage Detection in Composite Wind Turbine Blades written by Jeffery Dwayne Tippmann and published by . This book was released on 2014 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt: The aim of this dissertation was to develop passive techniques for vibration control and structural health monitoring applications in structures operating in conditions of significant ambient noise. These goals were accomplished through the use of an experimental wind turbine blade that represents the materials and design of a full scale wind turbine with the inclusion of devices simulating the presence of known manufacturing defects. The vibration control aim was accomplished using a shunted array of piezoelectric elements tuned to the vibration properties of the blade skin. The macro-fiber composite (MFC) composite piezoelectric transducer was bonded to the wind turbine blade skin and connected to the tuned shunt circuit. The damage detection techniques were developed using both an aluminum plate and the experimental wind turbine blade. Two approaches using a reconstructed impulse response function are presented. The first examines the break in reciprocity of impulse response functions. A single similarity damage index was proposed and then extended into a multi-feature analysis. The second method applied linear and nonlinear beamforming techniques using an experimentally generated replica field and cross-spectral signal processing techniques. The passive reconstruction of the impulse response function between two sensors is an important topic in NDE and SHM. Previously studied methods using active pitch-catch approaches between any two sensors is well suited for structures such as wind turbine blades that experience significant amounts of noise during operation. The study of these approaches advances the understanding of passive damage detection using reconstructed impulse response functions.

Structural Health Monitoring

Download Structural Health Monitoring PDF Online Free

Author :
Publisher : John Wiley & Sons
ISBN 13 : 0470394404
Total Pages : 496 pages
Book Rating : 4.4/5 (73 download)

DOWNLOAD NOW!


Book Synopsis Structural Health Monitoring by : Daniel Balageas

Download or read book Structural Health Monitoring written by Daniel Balageas and published by John Wiley & Sons. This book was released on 2010-01-05 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is organized around the various sensing techniques used to achieve structural health monitoring. Its main focus is on sensors, signal and data reduction methods and inverse techniques, which enable the identification of the physical parameters, affected by the presence of the damage, on which a diagnostic is established. Structural Health Monitoring is not oriented by the type of applications or linked to special classes of problems, but rather presents broader families of techniques: vibration and modal analysis; optical fibre sensing; acousto-ultrasonics, using piezoelectric transducers; and electric and electromagnetic techniques. Each chapter has been written by specialists in the subject area who possess a broad range of practical experience. The book will be accessible to students and those new to the field, but the exhaustive overview of present research and development, as well as the numerous references provided, also make it required reading for experienced researchers and engineers.

Wind Turbine Blade Fatigue Tests

Download Wind Turbine Blade Fatigue Tests PDF Online Free

Author :
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (16 download)

DOWNLOAD NOW!


Book Synopsis Wind Turbine Blade Fatigue Tests by :

Download or read book Wind Turbine Blade Fatigue Tests written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper presents experimental results of several structural health monitoring (SHM) methods applied to a 9-meter CX-100 wind turbine blade that underwent fatigue loading. The blade was instrumented with piezoelectric transducers, accelerometers, acoustic emission sensors, and foil strain gauges. It underwent harmonic excitation at its first natural frequency using a hydraulically actuated resonant excitation system. The blade was initially excited at 25% of its design load, and then with steadily increasing loads until it failed. Various data were collected between and during fatigue loading sessions. The data were measured over multiple frequency ranges using a variety of acquisition equipment, including off-the-shelf systems and specially designed hardware developed by the authors. Modal response, diffuse wave-field transfer functions, and ultrasonic guided wave methods were applied to assess the condition of the wind turbine blade. The piezoelectric sensors themselves were also monitored using a sensor diagnostics procedure. This paper summarizes experimental procedures and results, focusing particularly on fatigue crack detection, and concludes with considerations for implementing such damage identification systems, which will be used as a guideline for future SHM system development for operating wind turbine blades.

Structural Health Monitoring For Advanced Composite Structures

Download Structural Health Monitoring For Advanced Composite Structures PDF Online Free

Author :
Publisher : World Scientific
ISBN 13 : 1786343940
Total Pages : 286 pages
Book Rating : 4.7/5 (863 download)

DOWNLOAD NOW!


Book Synopsis Structural Health Monitoring For Advanced Composite Structures by : M H Ferri Aliabadi

Download or read book Structural Health Monitoring For Advanced Composite Structures written by M H Ferri Aliabadi and published by World Scientific. This book was released on 2017-12-18 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt: Structural health monitoring (SHM) is a relatively new and alternative way of non-destructive inspection (NDI). It is the process of implementing a damage detection and characterization strategy for composite structures. The basis of SHM is the application of permanent fixed sensors on a structure, combined with minimum manual intervention to monitor its structural integrity. These sensors detect changes to the material and/or geometric properties of a structural system, including changes to the boundary conditions and system connectivity, which adversely affect the system's performance.This book's primary focus is on the diagnostics element of SHM, namely damage detection in composite structures. The techniques covered include the use of Piezoelectric transducers for active and passive Ultrasonics guided waves and electromechanical impedance measurements, and fiber optic sensors for strain sensing. It also includes numerical modeling of wave propagation in composite structures. Contributed chapters written by leading researchers in the field describe each of these techniques, making it a key text for researchers and NDI practitioners as well as postgraduate students in a number of specialties including materials, aerospace, mechanical and computational engineering.

Predictive Maintenance in Dynamic Systems

Download Predictive Maintenance in Dynamic Systems PDF Online Free

Author :
Publisher : Springer
ISBN 13 : 3030056457
Total Pages : 567 pages
Book Rating : 4.0/5 (3 download)

DOWNLOAD NOW!


Book Synopsis Predictive Maintenance in Dynamic Systems by : Edwin Lughofer

Download or read book Predictive Maintenance in Dynamic Systems written by Edwin Lughofer and published by Springer. This book was released on 2019-02-28 with total page 567 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a complete picture of several decision support tools for predictive maintenance. These include embedding early anomaly/fault detection, diagnosis and reasoning, remaining useful life prediction (fault prognostics), quality prediction and self-reaction, as well as optimization, control and self-healing techniques. It shows recent applications of these techniques within various types of industrial (production/utilities/equipment/plants/smart devices, etc.) systems addressing several challenges in Industry 4.0 and different tasks dealing with Big Data Streams, Internet of Things, specific infrastructures and tools, high system dynamics and non-stationary environments . Applications discussed include production and manufacturing systems, renewable energy production and management, maritime systems, power plants and turbines, conditioning systems, compressor valves, induction motors, flight simulators, railway infrastructures, mobile robots, cyber security and Internet of Things. The contributors go beyond state of the art by placing a specific focus on dynamic systems, where it is of utmost importance to update system and maintenance models on the fly to maintain their predictive power.

Polycrystalline Silicon Capacitive MEMS Strain Sensor for Structural Health Monitoring of Wind Turbines

Download Polycrystalline Silicon Capacitive MEMS Strain Sensor for Structural Health Monitoring of Wind Turbines PDF Online Free

Author :
Publisher :
ISBN 13 :
Total Pages : 120 pages
Book Rating : 4.:/5 (988 download)

DOWNLOAD NOW!


Book Synopsis Polycrystalline Silicon Capacitive MEMS Strain Sensor for Structural Health Monitoring of Wind Turbines by : Maziar Moradi

Download or read book Polycrystalline Silicon Capacitive MEMS Strain Sensor for Structural Health Monitoring of Wind Turbines written by Maziar Moradi and published by . This book was released on 2016 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wind energy is a fast-growing sustainable energy technology and driven by the need for more efficient energy harvesting, size of the wind turbines has increased over the years for both off-shore and land-based installations. Therefore, structural health monitoring and maintenance of such turbine structures have become critical and challenging. In order to keep the number of physical inspections to minimum without increasing the risk of structural failure, a precise and reliable remote monitoring system for damage identification is necessary. Condition-based maintenance which significantly improves safety compared to periodic visual inspections, necessitates a method to determine the condition of machines while in operation and involves the observation of the system by sampling dynamic response measurements from a group of sensors and the analysis of the data to determine the current state of system health. This goal is being pursued in this thesis through the development of reliable sensors, and reliable damage detection algorithms. Blade strain is the most important quantities to judge the health of wind turbine structure. Sensing high stress fields or early detection of cracks in blades bring safety and saving in rehabilitation costs. Therefore, high performance strain measurement system, consisting of sensors and interface electronics, is highly desirable and the best choice. It has been revealed that the conventional strain gauge techniques exhibit significant errors and uncertainties when applied to composite materials of wind turbine blades. Micro-electro-mechanical system (MEMS) based sensors are very attractive among other sensing techniques owing to high sensitivity, low noise, better scaling characteristics, low cost and higher potential for integration with low power CMOS circuits. MEMS sensors that are fabricated on a chip can be either bonded to the surface of wind turbine blade or embedded into the fiber reinforced composite. Therefore, MEMS technology is selected to fabricate the strain sensor in this work. Two new sensor structures that can be used for strain measurement are designed. While the proposed sensors focus on high sensitivity, they are based on simple operating principle of comb-drive differential variable capacitances and chevron displacement amplification. Device performances are validated both by analytical solutions and finite element method simulations. The transmission of strain fields in adhesively bonded strain sensors is also studied. In strain sensors that are attached to host structures using adhesive layers such as epoxy, complete strain transfer to the sensor is hindered due to the influence of the adhesive layer on the transfer. An analytical model, validated by finite element method simulation, to provide insight and accurate formulation for strain transfer mechanism for bonded sensors is developed. The model is capable of predicting the strain transmission ratio through a sensor gauge factor, and it clearly establishes the effects of the flexibility, length, and thickness of the adhesive layer and sensor substrate. Several fabrication steps were required to realize the MEMS capacitive strain sensor in our lab. Polycrystalline silicon is selected as the structural layer and silicon nitride as the sacrificial layer. Polysilicon is deposited using LPCVD and SiN is deposited by PECVD in our lab. A comprehensive material study of silicon nitride and polycrystalline silicon layers is therefore performed. The whole fabrication process involves deposition, etching, and photolithography of five material layers. Although this process is developed to realize the MEMS strain sensors, it is also able to fabricate other designs of surface micromachining structures as well. The fabricated MEMS capacitive strain sensors are tested on a test fixture setup. The measurement setup is created under the probe station by using a cantilever beam fixed on one side and free on other side where a micrometer applies accurate displacement. The displacement creates bending stress on the beam which transfers to the MEMS sensor through the adhesive bond. Measurement results are in a good match with the simulation results. Finally, a real-time non-destructive health monitoring technique based on multi-sensor data fusion is proposed. The objective is to evaluate the feasibility of the proposed method to identify and localize damages in wind turbine blades. The structural properties of turbine blade before and after damage are investigated and based on the obtained results, it is shown that information from smart sensors, measuring strains and vibrations, distributed over the turbine blades can be used to assist in more accurate damage detection and overall understanding of the health condition of blades. Data fusion technique is proposed to combine the diagnostic tools to improve the detection system with providing a more robust reading and fewer false alarms.

Structural Health Monitoring 2015

Download Structural Health Monitoring 2015 PDF Online Free

Author :
Publisher : DEStech Publications, Inc
ISBN 13 : 1605952753
Total Pages : 1644 pages
Book Rating : 4.6/5 (59 download)

DOWNLOAD NOW!


Book Synopsis Structural Health Monitoring 2015 by : Fu-Kuo Chang

Download or read book Structural Health Monitoring 2015 written by Fu-Kuo Chang and published by DEStech Publications, Inc. This book was released on 2015-10-01 with total page 1644 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of the Tenth International Workshop on Structural Health Monitoring, September 1–3, 2015. Selected research on the entire spectrum of structural health techniques and areas of applicationAvailable in print, complete online text download or individual articles. Series book comprising two volumes provides selected international research on the entire spectrum of structural health monitoring techniques used to diagnose and safeguard aircraft, vehicles, buildings, civil infrastructure, ships and railroads, as well as their components such as joints, bondlines, coatings and more. Includes special sections on system design, signal processing, multifunctional materials, sensor distribution, embedded sensors for monitoring composites, reliability and applicability in extreme environments. The extensive contents can be viewed below.

Fundamentals for Remote Structural Health Monitoring of Wind Turbine Blades - a Pre-project. Annex B - Sensors and Non-destructive Testing Methods for Damage Detection in Wind Turbine Blades

Download Fundamentals for Remote Structural Health Monitoring of Wind Turbine Blades - a Pre-project. Annex B - Sensors and Non-destructive Testing Methods for Damage Detection in Wind Turbine Blades PDF Online Free

Author :
Publisher :
ISBN 13 : 9788755030565
Total Pages : 43 pages
Book Rating : 4.0/5 (35 download)

DOWNLOAD NOW!


Book Synopsis Fundamentals for Remote Structural Health Monitoring of Wind Turbine Blades - a Pre-project. Annex B - Sensors and Non-destructive Testing Methods for Damage Detection in Wind Turbine Blades by : L. Lading

Download or read book Fundamentals for Remote Structural Health Monitoring of Wind Turbine Blades - a Pre-project. Annex B - Sensors and Non-destructive Testing Methods for Damage Detection in Wind Turbine Blades written by L. Lading and published by . This book was released on 2002 with total page 43 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Vibration-based Structural Damage Identification Enhancement Via Piezoelectric Circuitry Network and Active Feedback Control

Download Vibration-based Structural Damage Identification Enhancement Via Piezoelectric Circuitry Network and Active Feedback Control PDF Online Free

Author :
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (299 download)

DOWNLOAD NOW!


Book Synopsis Vibration-based Structural Damage Identification Enhancement Via Piezoelectric Circuitry Network and Active Feedback Control by : Lijun Jiang

Download or read book Vibration-based Structural Damage Identification Enhancement Via Piezoelectric Circuitry Network and Active Feedback Control written by Lijun Jiang and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: