Real-time and portable microwave imaging system

Microwave and millimeter wave imaging has shown tremendous utility in a wide variety of applications. These techniques are primarily based on measuring coherent electric field distribution on the target being imaged. Mechanically scanned systems are the simple and low cost solution in microwave imaging. However, these systems are typically bulky and slow. This dissertation presents a design for a 2D switched imaging array that utilizes modulated scattering techniques for spatial multiplexing of the signal. The system was designed to be compact, coherent, possessing high dynamic range, and capable of video frame rate imaging. Various aspects of the system design were optimized to achieve the design objectives. The 2D imaging system as designed and described in this dissertation utilized PIN diode loaded resonant elliptical slot antennas as array elements. The slot antennas allow for incorporating the switching into the antennas thus reducing the cost and size of the array. Furthermore, these slots are integrated in a simple low loss waveguide network. Moreover, the sensitivity and dynamic range of this system is improved by utilizing a custom designed heterodyne receiver and matched filter. This dissertation also presents an analysis on the properties of this system. The performance of the multiplexing scheme, the noise floor and the dynamic range of the receivers are investigated. Furthermore, sources of errors such as mutual coupling and array response dispersion are also investigated. Finally, utilizing this imaging system for various applications such as 2D electric field mapping, scatterer localization, and nondestructive imaging is demonstrated --Abstract, Page iii

Situs inversus totalis with perforated duodenal ulcer: a case report

<p>Abstract</p> <p>Introduction</p> <p>Situs inversus is an uncommon anomaly. Situs inversus viscerum can be either total or partial. Total situs inversus, also termed as mirror image dextrocardia, is characterized by a heart on the right side of the midline while the liver and the gall bladder are on the left side. Patients are usually asymptomatic and have a normal lifespan. The exact etiology is unknown but an autosomal recessive mode of inheritance has been speculated. The first case of perforated duodenal ulcer with situs inversus was reported in 1986; here, we report the second case of this nature in the medical literature.</p> <p>Case presentation</p> <p>A 22-year-old Pakistani man presented with severe epigastric and left hypochondrial pain. Examination and investigations (chest X-ray and ultrasonography) confirm peritonitis in a case of situs inversus totalis. On exploratory laparotomy, a diagnosis of situs inversus totalis with perforated duodenal ulcer was confirmed. Graham's patch closure of the duodenal ulcer was performed with absorbable sutures, and a thorough peritoneal lavage was also performed; an incidental appendectomy was also performed to avoid further diagnostic problems. Our patient had an uneventful recovery.</p> <p>Conclusions</p> <p>A diagnostic dilemma arises whenever abdominal pathology occurs in patients with situs inversus. Although an uncommon anomaly, to choose a proper surgical incision site for abdominal exploration pre-operative recognition of the condition is important.</p

Multimodal Solution for a Rectangular Waveguide Radiating into a Multilayered Dielectric Structure and its Application for Dielectric Property and Thickness Evaluation

Open-ended rectangular waveguides are widely used for microwave and millimeter wave nondestructive testing applications. Applications have included detecting disbonds and delaminations in multilayered composite structures, thickness evaluation of dielectric sheets and coatings on metal substrates, etc. When inspecting a complex multilayered composite structure, made of generally lossy dielectric layers with arbitrary thicknesses and backing, the dielectric properties of a particular layer within the structure is of particular interest, such being health monitoring of structures such as radomes. The same is also true where one may be interested in the thickness or more importantly thickness variation of a particular layer within such structures. An essential tool for estimating the dielectric constant or thickness is an accurate model for simulating reflection coefficient at the aperture of the probing open-ended waveguide. One issue of interest is that radiation from open-ended rectangular waveguides into layered dielectric structures has been considered only when accounting for the dominant waveguide mode. However, when using these models for recalculating dielectric constant or thickness, the results may not be accurate (depending on the measurement requirements). To this end, this paper provides an accurate model for the reflection coefficient which also accounts for the effect of higher-order modes. Finally, the potential of this model for accurately estimating dielectric constant is shown

Optimization of the industrial production of bacterial aamylase in Egypt. V. Analysis of kinetic data for enzyme production by two strains of Bacillus amyloliquefaciens

A kinetic study was conducted for a-amylase production process in shake flasks by the wild type strain of Bacillus amyloliquefaciens (strain 267) and in the fermentor by the amplified variant of the sameorganism (strain 267CH). a-Amylase was produced concurrently with growth up to about 72 h, after which it continued without increase in biomass and, in the case of strain 267 even after biomassdeclined. Application of logistic, Luedeking-Piret and the modified Luedeking-Piret mathematical models to the kinetic data revealed that a-amylase production in both cases occurred through bothgrowth- and non-growth associated mechanisms and that the amount of enzyme produced through non-growth associated mechanism exceeded that produced through growth associated mechanism by 3.5 and 2.3 fold by strains 267 and 267CH, respectively. Although with both strains substrate consumption continued even after growth leveled, the application of the model revealed that the major portion of substrate consumption occurred during growth but that a considerable amount was also consumed after maximum growth was reached, mainly for enzyme production. In the bioreactor, increasing aeration from 1 to 2 vvm increased the overall specific growth rate, the production rate, thespecific production rate, and the specific substrate consumption rate and also shortened the time necessary for maximum production of both biomass and enzyme. The increase in biomass either by prolonging the incubation time or by increasing aeration was accompanied by an increase in enzyme production. However, even after maximum biomass was reached, enzyme production still continued to increase, under both conditions

Method and Apparatus for Nondestructive Sample Inspection

An apparatus for inspecting a sample for defects includes a signal generator for generating a signal and a device for splitting the signal into two separate signals which have substantially equal phase and magnitude. A sensor radiates the two signals on the sample and receives the two signals reflected from the sample. A device is provided for determining a difference between the two signals reflected from the sample without unwanted influence of variations of distance between the sensor and sample, and reflections from nearby sample edges and boundaries. A defect is determined to exist when a difference is found between the two reflected signals

Near-Field Millimeter-Wave Imaging of Exposed and Covered Fatigue Cracks

In this paper, the efficacy of near-field millimeter-wave nondestructive techniques, using open-ended flange-mounted rectangular waveguide probes, for extracting information of 3-D crack area deformation (i.e., in-plane and out-of-plane deformation) is demonstrated. It is shown that this information can be obtained from indications of unique interference patterns that are generated between the probe and the metal surface during the raster scan of a surface-breaking exposed and covered fatigue crack using a phase-sensitive reflectometer

Waveguide Probe for Nondestructive Material Characterization

An open-ended waveguide probe including a finite flange extending outwardly and functioning as an infinite flange. A signal source provides a microwave signal to the waveguide, which in turn transmits microwave electromagnetic energy incident upon an object to be tested. The finite flange at the waveguide\u27s aperture is shaped to reduce scattering of the electromagnetic field reflected from the object and received by the aperture. The probe is adapted for coupling to a receiver for sampling the reflected electromagnetic field received by the aperture and the receiver is adapted for coupling to a processor for determining at least one material characteristic of the object based on sampled electromagnetic field reflected from the object

Multimodal Solution for a Waveguide Radiating into Multilayered Structures -- Dielectric Properties and Thickness Evaluation

Open-ended rectangular waveguides are widely used for microwave and millimeter-wave nondestructive testing (NDT) applications, such as detecting disbond and delamination in multilayered composite structures, thickness evaluation of dielectric sheets and coatings on metal substrates, etc. when inspecting a complex multilayered composite structure that is made of generally lossy dielectric layers with arbitrary thicknesses and backing, the dielectric properties of a particular layer may be of particular interest (e.g., radome inspection). The same is also true when one is interested in the thickness, or, more importantly, thickness variation, of a particular layer within such complex structures. An essential tool for closely estimating the complex permittivity and/or thickness is an accurate forward electromagnetic model for simulating the reflection coefficient at the aperture of the probing open-ended waveguide. To this end, this paper provides a full-wave accurate forward model for calculating the reflection coefficient from a generally lossy multilayered composite structure possessing an arbitrary number of layers and respective thicknesses while accounting for the influence of higher order modes. This model is subsequently validated through comparisons with a commercial numerical tool and actual measurements. Furthermore, a measurement model is provided, which results in an iterative inverse technique for estimating the complex permittivity and thickness of a dielectric layer. Subsequently, this technique is applied to the measured reflection coefficients of several structures. To evaluate the accuracy of this technique, an analysis on its sensitivity to various sources of errors, and, most importantly, the effect of a finite flange size, is also demonstrated by using the simulated data. Finally, the potential of this model to accurately estimate the thickness of an individual layer, which represents a thin disbond, in a multilayered composite structure is presented

Optimization of the industrial production of bacterial alpha amylase in Egypt. IV. Fermentor production and characterization of the enzyme of two strains of Bacillus subtilis and Bacillus amyloliquefaciens

Production of alpha amylase using amplified variants of Bacillus subtilis (strain SCH) and of Bacillus amyloliquefaciens (strain 267CH) was conducted in a bioreactor with multiprotein-mineral media. Thetime course of fermentation in a bioreactor revealed that the highest yield (about 8 x 104 U/ml within 60 h) by strain SCH was obtained by applying: 3.5% initial starch, 2% additional starch after 19 h, 3 vvmaeration and 300 rpm agitation. The highest yield (about 19 x 104 U/ml within 100 h) by strain 267CH was obtained by applying: 2.5% initial starch, 2% additional starch after 24 h, 3 vvm aeration, and 300 rpmagitation with the productivity after 60 h reaching only about 14 x 104 U/ml. Production occurred in both the logarithmic and postlogarithmic phases of growth. Maximum consumption of starch and proteinoccurred during the first day of incubation. The optical density peak coincided with enzyme production peak in case of strain SCH and preceded that of enzyme production in case of strain 267CH. The alphaamylase produced by the two strains was shown to be of the liquefying and not the saccharifying type. Both enzymes liquefied starch to a dextrose equivalent of about 15 - 17 at 95oC hence they areclassified among thermostable alpha amylases. They exhibited broad pH and temperature activity profiles. The optimum pH for activity was 4 - 7 for alpha amylase produced by strain SCH and 4 - 8 foralpha amylase produced by strain 267CH while the optimum temperatures for their activities were in the range 37 -75oC at 0.5% starch and in the range 85 - 95oC at 35% starch

Free-Hand Scanning and Imaging

Wideband synthetic aperture radar (SAR) imaging. A probe transmits a signal through its aperture incident to an object located in a medium of interest remotely from the probe. The probe receives through the aperture a plurality of nonuniformly sampled reflected signals from the object as the probe moves in a measurement plane located a predetermined distance from the object. A processor executes a SAR-based reconstruction algorithm to generate an image