Studies into the detection of buried objects (particularly optical fibres) in saturated sediment. Part 2: design and commissioning of test tank

This report is the second in a series of five, designed to investigate the detection oftargets buried in saturated sediment, primarily through acoustical or acoustics-relatedmethods. Although steel targets are included for comparison, the major interest is intargets (polyethylene cylinders and optical fibres) which have a poor acousticimpedance mismatch with the host sediment. This particular report details theconstruction of a laboratory-scale test facility. This consisted of three maincomponents. Budget constraints were an over-riding consideration in the design.First, there is the design and production of a tank containing saturated sediment. Itwas the intention that the physical and acoustical properties of the laboratory systemshould be similar to those found in a real seafloor environment. Particularconsideration is given to those features of the test system which might affect theacoustic performance, such as reverberation, the presence of gas bubbles in thesediment, or a suspension of particles above it. Sound speed and attenuation wereidentified as being critical parameters, requiring particular attention. Hence, thesewere investigated separately for each component of the acoustic path.Second, there is the design and production of a transducer system. It was the intentionthat this would be suitable for an investigation into the non-invasive acousticdetection of buried objects. A focused reflector is considered to be the most costeffectiveway of achieving a high acoustic power and narrow beamwidth. Acomparison of different reflector sizes suggested that a larger aperture would result inless spherical aberration, thus producing a more uniform sound field. Diffractioneffects are reduced by specifying a tolerance of much less than an acousticwavelength over the reflector surface. The free-field performance of the transducerswas found to be in agreement with the model prediction. Several parameters havebeen determined in this report that pertain to the acoustical characteristics of the waterand sediment in the laboratory tank in the 10 – 100 kHz frequency range.Third, there is the design and production of an automated control system wasdeveloped to simplify the data acquisition process. This was, primarily, a motordrivenposition control system which allowed the transducers to be accuratelypositioned in the two-dimensional plane above the sediment. Thus, it was possible forthe combined signal generation, data acquisition and position control process to be coordinatedfrom a central computer.This series of reports is written in support of the article “The detection by sonar ofxdifficult targets (including centimetre-scale plastic objects and optical fibres) buriedin saturated sediment” by T G Leighton and R C P Evans, written for a Special Issueof Applied Acoustics which contains articles on the topic of the detection of objectsburied in marine sediment. Further support material can be found athttp://www.isvr.soton.ac.uk/FDAG/uaua/target_in_sand.HTM

LeviSense: a platform for the multisensory integration in levitating food and insights into its effect on flavour perception

Eating is one of the most multisensory experiences in everyday life. All of our five senses (i.e. taste, smell, vision, hearing and touch) are involved, even if we are not aware of it. However, while multisensory integration has been well studied in psychology, there is not a single platform for testing systematically the effects of different stimuli. This lack of platform results in unresolved design challenges for the design of taste-based immersive experiences. Here, we present LeviSense: the first system designed for multisensory integration in gustatory experiences based on levitated food. Our system enables the systematic exploration of different sensory effects on eating experiences. It also opens up new opportunities for other professionals (e.g., molecular gastronomy chefs) looking for innovative taste-delivery platforms. We describe the design process behind LeviSense and conduct two experiments to test a subset of the crossmodal combinations (i.e., taste and vision, taste and smell). Our results show how different lighting and smell conditions affect the perceived taste intensity, pleasantness, and satisfaction. We discuss how LeviSense creates a new technical, creative, and expressive possibilities in a series of emerging design spaces within Human-Food Interaction

Index to 1984 NASA Tech Briefs, volume 9, numbers 1-4

Short announcements of new technology derived from the R&D activities of NASA are presented. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This index for 1984 Tech B Briefs contains abstracts and four indexes: subject, personal author, originating center, and Tech Brief Number. The following areas are covered: electronic components and circuits, electronic systems, physical sciences, materials, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences

Photoacoustic Microscopy and Photoacoustic Computed Tomography Using High-frequency Linear Array Ultrasonic Transducers

Photoacoustic tomography (PAT) is a highly promising imaging technology which forms images by detecting the induced pressure waves resulting from pulsed light absorption in biological tissues. Because the excitation source is light, PAT is a very safe, non-ionizing, and non-carcinogenic imaging technology. In biomedicine, PAT has the unique advantage of probing endogenous optical absorbers at different length scales with 100% relative sensitivity. With such scalability, PAT can image anatomical, functional, metabolic, molecular, and genetic contrasts of vasculature, hemodynamics, oxygen metabolism, biomarkers, and gene expression. Among several implementations of PAT, optical-resolution photoacoustic microscopy (OR-PAM) and photoacoustic computed tomography (PACT) are two of the most widely used. OR-PAM can achieve optical diffraction limited spatial resolution with maximum imaging depths up to one transport mean free path (~1 mm in biological tissue). PACT can achieve several centimeters imaging depth in tissue by employing ultrasonic array detectors and inverse algorithms. This dissertation aims to improve the functionality of OR-PAM using a high-frequency linear ultrasonic array, and to advance the performance of linear-array PACT to full view angle capability and higher resolution. The first part of this dissertation describes the technological advancement of multifocal optical-resolution photoacoustic microscopy (MFOR-PAM). Compared with single-focus OR-PAM, 1D multifocal OR-PAM utilizes both multifocal optical illumination and an ultrasonic transducer array, significantly increasing the imaging speed. We present a reflection-mode 1D multifocal OR-PAM system based on a 1D microlens array that provides multiple foci as well as an ultrasonic transducer array that receives the excited photoacoustic waves from all foci simultaneously. Using a customized microprism to reflect the incident laser beam to the microlens array, the multiple optical foci are aligned confocally with the focal zone of the ultrasonic transducer array. Experiments show the reflection-mode 1D multifocal OR-PAM is capable of imaging microvessels in vivo, and it can image a 6 × 5 × 2.5 mm3 volume at 16 μm lateral resolution in ∼2.5 min, limited by the signal multiplexing ratio and laser pulse repetition rate. While 1D-MFOR-PAM accelerates the scan in only one direction, a two-dimensional MFOR-PAM (2D-MFOR-PAM) fully explores the advantage of a 2D microlens array. By scanning a small range of 250 mm × 250 mm, we eventually obtained a large field of view of 10 mm × 10 mm in ~50 seconds, with a spatial resolution of 15.2 mm. The second part of this dissertation describes methods of increasing the view angle of linear-array PACT, which suffers from a limited view. While rotating either the transducer array or the imaging objects circularly enables full-view linear-array PACT, this process is time consuming. Here we propose two innovative methods to increase the view angle. The first method is to triple the detection view angle by using two planar acoustic reflectors placed at 120 degrees to each other. Without sacrificing the imaging speed, we form two virtual linear transducer arrays, adding two vantage points. Experimental results show the detection view angle of the linear-array PACT was increased from 80 to 240 degrees. The second method is an ultrasonic thermal encoding approach that is universally applicable to achieve full-view imaging with linear-array PACT. We demonstrate full-view in vivo vascular imaging and compare it to the original linear-array PACT images, showing dramatically enhanced imaging of arbitrarily oriented blood vessels. The last part of the dissertation describes the development of algorithms for linear-array PACT. The first proposed algorithm is a multi-view Hilbert transformation, which provides accurate optical absorption for full-view linear-array PACT. A multi-view high-frequency PACT imaging system was implemented with a commercial 40-MHz central frequency linear transducer array. By rotating the object through multiple angles with respect to the linear transducer array, we acquired full-view photoacoustic pressure measurements. The in-plane spatial resolution of this full-view linear-array PACT was quantified to be isotropically 60 mm within a 10×10 mm2 field of view. The system was demonstrated by imaging both a leaf skeleton and a zebrafish in vivo. The second algorithm is an inverse linear Radon transformation (ILRT), which allows linear-PACT to achieve isotropic resolution at all depth planes. Images of microspheres acquired by inverse linear Radon transformation PACT (ILRT-PACT) demonstrate that our technique improves the elevational resolution by up to 9.4 times over that of a single linear scan. The technique is further demonstrated through in vivo imaging of the mouse brain through an intact scalp

LeviSense: A platform for the multisensory integration in levitating food and insights into its effect on flavour perception

Eating is one of the most multisensory experiences in everyday life. All of our five senses (i.e. taste, smell, vision, hearing and touch) are involved, even if we are not aware of it. However, while multisensory integration has been well studied in psychology, there is not a single platform for testing systematically the effects of different stimuli. This lack of platform results in unresolved design challenges for the design of taste-based immersive experiences. Here, we present LeviSense: the first system designed for multisensory integration in gustatory experiences based on levitated food. Our system enables the systematic exploration of different sensory effects on eating experiences. It also opens up new opportunities for other professionals (e.g., molecular gastronomy chefs) looking for innovative taste-delivery platforms. We describe the design process behind LeviSense and conduct two experiments to test a subset of the crossmodal combinations (i.e., taste and vision, taste and smell). Our results show how different lighting and smell conditions affect the perceived taste intensity, pleasantness, and satisfaction. We discuss how LeviSense creates a new technical, creative, and expressive possibilities in a series of emerging design spaces within Human-Food Interaction

Indigenous Development of Acoustic Sounder (SODAR) in India as an Upgraded Technology for Environmental Protection: A Review

Sound Detection and Ranging (SODAR) has moved to the forefront of consumer technology due to the pressing need toengage the Atmospheric Boundary Layer (ABL) in environmental protection. An active ground-based remote sensingsystem (SODAR) is used to determine the lower-atmosphere wind profile and temperature structure. SODAR can detectturbulence parameters in the ABL from a distance and can be used for wind profiling. SODAR, with its significantlyenhanced capability, is expected to be a futuristic remote sensing device with several uses in the near future. Including anemphasis on its applications and current developments, this article examines SODAR's early history, with a review of Indianstudies. The article examines past breakthroughs in SODAR as well as its advancement and applications, with an emphasison India due to the worldwide nature of SODAR research. Additionally, the article discusses how effective SODAR is inprotecting the environment and how important it is going forward. After summarising the applications, various opportunitiesand barriers incurred in SODAR use, a proposed review article to provide insights into previously understudied, unstudied,and studied research work accomplished on SODAR in India is constructed. The article accentuates the role of SODAR asan environmental safeguarding tool

Index to 1981 NASA Tech Briefs, volume 6, numbers 1-4

Short announcements of new technology derived from the R&D activities of NASA are presented. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This index for 1981 Tech Briefs contains abstracts and four indexes: subject, personal author, originating center, and Tech Brief Number. The following areas are covered: electronic components and circuits, electronic systems, physical sciences, materials, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences

Surface Acoustic Wave Devices as Chemical Vapor Sensors

In order to effectively neutralize non-traditional threats to US forces and population such as improvised explosive devices (IED) and chemical, biological, radio- logical, nuclear, and explosive (CBNRE) weapons, a flexible vapor sensor platform is proposed. This work involves the design, fabrication, and testing of coated surface acoustic wave devices for vapor sensing ability. Devices were fabricated in-house using MEMS fabrication techniques, then coated with a thin layer of a Nafion polymer. The frequency response of coated devices displayed 2 MHz frequency shifts around the resonance frequency upon introduction of ethanol vapors into the nitrogen vapor stream. This indicates strong sensing ability based upon the viscoelastic changes in the polymer film. Further work should include new coating layers such as biological molecule self-assembled monolayers, circuitry to allow portability, and a preconcentrator to increase sensitivity