Digitally Coded Electromagnetic Transducers

Electromagnetic transducers had previously been shown to be capable of acting as pulse to achieve improved range resolution. Compression was achieved using pairs of transducers designed to produce or detect a burst with a linear frequency variation. An alternate approach, which is also easier to fabricate, is to impress a digital phase code on single frequency coils. One such code with good autocorrelation properties is the 13 bit Barker coder. Coils with this code were fabricated and evaluated. It will be shown that the operation of these devices is very similar to the coils with dispersive designs. The waveforms, compression ratio,and sidelobe levels to be expected from these devices are describe

Characteristics and Applications of Electromagnetic Surface Wave Transducers

Tom Szabo mentioned during his presentation that there is a great deal of similiarity between the response of a meander line surface wave EMT and that of an interdigital transducer. We have been investigating their common properties to see if they can be exploited for NDE applications. The generation of bulk waves in delay lines is considered a problem for interdigital transducers,2 but for NDE it might provide a convenient means of generating bulk waves propagating at an angle to the surface

Balancing Technological Opportunities vs. Operational Requirements: an AFML Challenge

The mission of the NDE Branch of the Air Force Materials Laboratory is twofold: first, to support the overhaul and maintenance functions, and second, to provide new technology to allow the development of more durable and higher performance equipment. The lack of a mature NDE technology base, coupled with identifiable future needs, necessitates a long term commitment to providing generic capabilities. However, the severity of present day problems and the high payoff which would result from their solution, create\u27s a strong demand for programs aimed at short term results. The attempt by the Materials Laboratory to balance these competing demands will be discussed. In addition, a potential application of quantitative NDE to an Air Force problem will be discussed in terms of the NDE requirements and possible benefits. This will illustrate the necessity of maintaining the effort to develop the technology base

User's manual: Subsonic/supersonic advanced panel pilot code

Sufficient instructions for running the subsonic/supersonic advanced panel pilot code were developed. This software was developed as a vehicle for numerical experimentation and it should not be construed to represent a finished production program. The pilot code is based on a higher order panel method using linearly varying source and quadratically varying doublet distributions for computing both linearized supersonic and subsonic flow over arbitrary wings and bodies. This user's manual contains complete input and output descriptions. A brief description of the method is given as well as practical instructions for proper configurations modeling. Computed results are also included to demonstrate some of the capabilities of the pilot code. The computer program is written in FORTRAN IV for the SCOPE 3.4.4 operations system of the Ames CDC 7600 computer. The program uses overlay structure and thirteen disk files, and it requires approximately 132000 (Octal) central memory words

The mass ratio distribution of short period double degenerate stars

Short period double degenerates (DDs) are close white dwarf - white dwarf binary stars which are the result of the evolution of interacting binary stars. We present the first definitive measurements of the mass ratio for two DDs, WD0136+768 and WD1204+450, and an improved measurement of the mass ratio for WD0957-666. We compare the properties of the 6 known DDs with measured mass ratios to the predictions of various theoretical models. We confirm the result that standard models for the formation of DDs do not predict sufficient DDs with mass ratios near 1. We also show that the observed difference in cooling ages between white dwarfs in DDs is a useful constraint on the initial mass ratio of the binary. A more careful analysis of the properties of the white dwarf pair WD1704+481.2 leads us to conclude that the brighter white dwarf is older than its fainter companion. This is the opposite of the usual case for DDs and is caused by the more massive white dwarf being smaller and cooling faster. The mass ratio in the sense (mass of younger star)/(mass of older star) is then 1.43+-0.06 rather than the value 0.70+-0.03 given previously.Comment: Accepted for publication in MNRA

The triple degenerate star WD1704+481

WD1704+481 is a visual binary in which both components are white dwarfs. We present spectra of the H-alpha line of both stars which show that one component (WD1704+481.2 = Sanduleak B = GR 577) is a close binary with two white dwarf components. Thus, WD1704+481 is the first known triple degenerate star. From radial velocity measurements of the close binary we find an orbital period of 0.1448d, a mass ratio, q=Mbright/Mfaint of q=0.70+-0.03 and a difference in the gravitational redshifts of 11.5+-2.3km/s. The masses of the close pair of white dwarfs predicted by the mass ratio and gravitational redshift difference combined with theoretical cooling curves are 0.39+-0.05 solar mass and 0.56+-0.07 solar masses. WD1704+481 is therefore also likely to be the first example of a double degenerate in which the less massive white dwarf is composed of helium and the other white dwarf is composed of carbon and oxygen.Comment: 5 pages, 4 figure

Orbital periods of the binary sdB stars PG0940+068 and PG1247+554

We have used the radial velocity variations of two sdB stars previously reported to be binaries to establish their orbital periods. They are PG0940+068, (P=8.33d) and PG1247+554 (P=0.599d). The minimum masses of the unseen companions, assuming a mass of 0.5 solar masses for the sdB stars, are 0.090 +/- 0.003 solar masses for PG1247+554 and 0.63 +/- 0.02 solar masses for PG0940+068. The nature of the companions is not constrained further by our data.Comment: 5 pages, 2 figure

The Offender Personality Disorder pathway for women in England and Wales: a hopeful new development?

The Offender Personality Disorder (OPD) pathway was jointly commissioned by Her Majesty’s Prison and Probation Service (HMPPS) and NHS England in 2011. Representing one of the most significant recent developments in mental health and criminal justice, the pathway provides psychologically-informed and relationally-focused treatment for high risk offenders with personality disorder. Acknowledging the gender differences that exist in terms of the psychosocial and criminogenic needs of offenders, the OPD pathway provides female-specific services, delivering “wraparound” support for eligible women throughout their sentences, in custody and in the community. The OPD pathway for women is seeking to make a valuable contribution to managing this population of female offenders who are among the most vulnerable individuals in the criminal justice system, but who pose a high risk to the public. The pathway constitutes an innovative development in terms of delivering improved outcomes for this challenging and complex offender group, but knowledge about its impact will require close on-going evaluation

A Pseudorandom Binary Noise Ultrasonic System

The random noise ultrasonic system represents the state-of-the-art in terms of sensitivity and resolution for ultrasonic NDE systems. The principle impediment to its use in the field is the lack of real-time inspection capability. If a pair of pseudorandom binary noise sources are substituted for the white noise source in the random noise system, a real-time capability is achieved. An instrument using such sources will be demonstrated and its capabilities will be discussed