Summary As RKO Pathe news was “the eyes and the ears of the world,” so transducers are the eyes and the ears of most ultrasonic systems. From simple beginnings in piezoelectric crystals, transducer technology has branched out into the use of electromagnetic coils, polymer films, and finely partitioned piezoelectrics to take advantage of particular properties useful in certain situations. Research has led to many improvements and many new devices. Coils and magnets can work on metals in a noncontact mode. PVDF films match well into liquids and can radiate into air effectively because of their high coupling coefficient in stretch, which can be translated by geometrical construction into a drumhead sort of radiator. The finely partitioned (sliced, diced, molded) piezoelectrics have a higher coupling coefficient for longitudinal waves and minimize unwanted radial motion. Arrays can be made directly from the diced parts with proper electrical connections. This chapter has given details of theory, manufacture, and analysis of transducers. Examples have been given, but for complete listings of manufacturers and parts, the reader should consult NDT advertising and buyers guides.
This chapter gives an overview of three decades of technology development in surface acoustic wave (SAW) ultrasonics. SAW technology, as applied to modern electronic systems, was born with the concept of a thin-metal interdigital electrode transducer (IDT) on a polished piezoelectric plate and spent its youth exploring the limits of time and frequency domain signal processing functions. Since then it has matured as a manufacturing technology in consumer electronics, found economic success in frequency selectivity for telecommunications, and continues to grow and support a variety of wireless and sensor applications. Its secret to success has been the slow wave velocity accorded elastic waves, its accessibility to surface displacements and electric fields, its passive device nature, its high-frequency capability, the availability of a large dynamic range, and the simplicity of its manufacture. A technology with an explosive beginning, it has evolved into a respected and much needed component for time and frequency control in electronic systems and has a promising applications-filled future.
The Physical Sciences Directorate (PSD) of the Army Research Laboratory (ARL), Fort Monmouth, NJ, has achieved significant success in the technology transfer/strategic alliance arena by blending technology transfer statutes, regulations, and practices into its corporate culture. The essay describes the process and procedure PSD utilized in achieving that success, along with the lessons learned in introducing new and innovative methodologies, techniques, and approaches in transferring federal laboratory technology to the private sector.
The Physical Sciences Directorate of the Army Research Laboratory has achieved significant success in the technology transfer/strategic alliance arena by blending technology transfer statutes, regulations and practices into its corporate culture.
This chapter discusses the perspectives on technology transfer and nondestructive testing (NDT) markets. NDT markets may be too small, too specialized, and too conservative to absorb many new technical developments from university and institute laboratories. These institutions would be well advised to manage their technology transfer expectations down to more achievable goals. Few reliable market studies exist of the various industrial NDT markets. These markets are extremely diverse and include everything from equipment sales to inspection services, software, and engineering consulting. Available equipment includes disparate technologies such as ultrasound, acoustic emission, eddy current, particle and penetrants, x-ray and other radiography, and magnetic or particle emission. In addition, these technologies are used across a variety of end-use markets, such as aerospace, utility, chemical, electronics, energy, metalworking, and transportation.
This chapter discusses the difficulties in technology transfer. As technology transfer is a prerequisite step to commercialization, it is valuable to see the process of technology transfer from the perspective of different people who have had experiences with the process. Other essays treat the subjects of technology transfer and commercialization from the didactic point of view to show ways and means to accomplish the goal of commercialization. The various types of organizations engaged in research and development experience varying degrees of difficulty in effecting technology transfer. For instance, the small company that decides to build a salable object can bring it to market relatively rapidly, provided it has the capital required. Universities experience varying degrees of difficulty in getting their research into and through the process of technology transfer.
This chapter discusses the commercialization—from basic research to sales to profits. The commercialization path begins with basic research and development. For fundamentally new technology, this step generally occurs over a period of ten to twenty years, or more. The purpose of basic research along the commercialization path is to provide the foundation for an innovation that can be "built out" into a product that provides a substantial technology lead over existing products in the market or provides solutions to a range of problems that cannot currently be solved. JENTEK products are founded upon the capability to accurately model the interaction of magnetic and electric fields with multiple layered media, so that sensors can provide quantitative measurement of properties such as conductivity, permeability, dielectric constant, and layer thickness.
This chapter discusses the process of technology transfer and commercialization. 'Technology transfer' has become a popular phrase and a subject of great interest in myriad quarters. Not surprisingly, it has taken on various meanings. To consider it in any detail in the space available, the concept must be bound in several ways. First, technology transfer can be internal—that is, within the same enterprise. It can also be external. Second, it is assumed that external transfers follow strictly arm's-length negotiations. Third, presumably all transfers are undertaken with the expectation that the technology will be utilized in the market, again as the result of arm's-length bargaining. 'Technology transfer' is but the outcome of a process called innovation. This process begins with an invention, an idea, or a concept and concludes with the introduction of a product or service in the marketplace on the basis of an arm's-length transaction.
This essay describes two unusual R&D projects that have resulted in the development of a new paradigm for engineering education. The first project, funded by the Gas Research Institute, consists of a consortium of Battelle (Columbus), Southwest Research Institute, Iowa State University, and a number of gas pipeline inspection companies whose overall goal is to improve the state of the art in gas transmission pipeline inspection. The second project, funded by a Japanese company, Takano, Co., Ltd., involved the design and development to industrial prototype stage of an acoustic microscope. (This project with Takano has since been followed by two other projects for development of other NDE instruments.) Both the GRI and the Takano projects involved large teams of Ph.D. M.S., and undergraduate students that had to interact on a daily basis with faculty, visiting engineers, and postdoctoral researchers while balancing the hard deadlines imposed by the industrial partners and the academic concerns of working toward a degree. Issues relating to project reports, presentations, intellectual property, technology transfer, and industrial interaction were dealt with as a team, which has led to careful consideration of such teams as an integral part of the educational experience for all engineering students. Details of this new paradigm are presented together with suggestions for incorporating it into engineering curricula.
Publisher Summary This chapter discusses the frequency control devices. Frequency control devices provide the precise time and frequency on which modem electronics depends. A vibrating quartz crystal, i.e., a quartz resonator, is the heart of nearly all frequency control devices. Quartz clocks provide accurate time and quartz oscillators are the sources of precise frequency. Time is important not only for the daily schedules of human beings, but also, for example, for determining the sequence of events that take place inside computers, and for time-tagging the information that flows through communication systems. Frequency sources are essential for determining the frequencies of radio and TV transmissions, radar systems, communication and navigation systems, etc. Frequency control technology took a great leap forward in the 1920s when quartz was first utilized to realize crystal resonators for the stabilization of oscillators, thereby launching the field of modem frequency control. With the introduction of quartz control, timekeeping moved from the sun and stars to small, man-made sources that exceeded astronomy-based references in stability.
Publisher Summary This chapter discusses the research instruments and systems. Instrumentation of various degrees of complexity and sophistication for the ultrasonic examination of materials has been developed over the years since Floyd Firestone was granted a patent for his flaw detection device. This chapter presents representative machines designed primarily for the relatively new field of nondestructive evaluation (NDE) of materials using ultrasound over a very wide range of frequencies. In NDE work, the objective is generally to document the quality of the material under test rather than to examine it for gross flaws. Descriptions of some representative NDE instruments developed in the research laboratory and later successfully brought to the commercial marketplace are discussed in this chapter.
Ultrasonic imaging and scanned acoustic microscopy are terms used to describe similar imaging processes at different magnifications and frequencies. Both processes form images by acquiring spatially correlated measurements of the interaction of high-frequency sound waves with materials. With the exception of the interference measurement, called V(z), and the gigahertz frequencies used by the higher frequency scanning acoustic microscopes, it is difficult to establish operational differences between them. This is especially true since almost all commercial ultrasonic imaging systems use transducers producing focused beams and can display magnified high-resolution images.Ultrasonic C-scan imaging was developed largely by the ultrasonic nondestructive testing industry. The development was gradual and evolutionary. Over a 50-year period, better and better broadband transducers, electronics and scanners were developed for operation at progressively higher frequencies, now ranging from 1.0 to 100 MHz. Conversely, scanning acoustic microscopes made a relatively sudden appearance 20 years ago on the campus of Stanford University. The first scanning acoustic microscopes operated at gigahertz frequencies and used microwave electronics that produced acoustic tone bursts with many wavelengths per pulse.Three factors control resolution in an acoustic image:diameter of the acoustic beam or its point spread function (PSF);size and spacing of the pixels making up the image;signal-to-noise ratio (contrast) of the feature being resolved.The beam diameter, or PSF, is controlled by the frequency of the ultrasonic pulse and the focal convergence of the beam (or focal length to diameter ratio Z/d). In the coupling fluid, the Z/d ratio is determined by the transducer diameter and lens, but in the material, Z/d is established by the materials ultrasonic velocities. Pixels are the squares of colour or greyscale that make up computer displays of scanned images. Following Nyquist's criterion, the resolution of those images is twice the size and spacing of the pixels. It follows, therefore, that in order to support the resolution of an ultrasonic beam, the pixels must be no larger than half that beam diameter. Finally, the contrast of the feature being studied must be (at least) a clear shade of grey above the background produced by the image noise. The noise can be due to the material or the electronics. Written to support industrial ultrasonic inspection of materials, this discussion will emphasise the similarities between imaging and microscopy rather than the differences. The roles of the focusing lens, the pulse frequency, and the material being imaged, with respect to the final resolution of an acoustic image, will be considered in detail. It will be shown that additional improvements in resolution can be achieved with image processing. Finally, applications studies in metals, ceramics, composites, attachment methods, coatings, and electronic assemblies will be used to demonstrate specific roles for imaging/microscopy in nondestructive testing.
The acoustic properties of single crystals of the high-temperature superconductor YBa2Cu3O7 have been measured at temperatures between 0.1 and 300 K for frequencies near 103 and 109 Hz. In the GHz regime, longitudinal modes have been studied for propagation directions parallel and perpendicular to the c axis. At Tc, there is a discontinuity in the sound velocities and their temperature derivatives from which the anisotropic strain dependences of Tc are obtained. In the kHz regime, resonant excitation of flexural modes in thin reeds of YBa2Cu3O7 crystals has permitted precise measurement of acoustic damping and dispersion. The temperature-dependent damping is characterized by at least five features associated with the relaxation of defects. At temperatures below 1 K, the velocity of sound is consistent with the presence of a broad “glasslike” distribution of tunneling modes.
