The relationship between duct tissue and several types of malignant disease suggests that methods for characterizing duct structures may be useful tools in ultrasonic tissue characterization. This ...paper presents performance results from ultrasonic phantom experiments and Monte Carlo simulations for detecting and estimating duct wall spacings on the order of those typically found in breast tissue using methods based on the generalized spectrum (GS) and cepstrum. Aperformance comparison demonstrates the advantages of each method and examines the effects of various signal processing options, including a special normalization technique for the GS that effectively whitens the data spectrum and reduces interfering spectral influences with little overall performance loss. Experimental results (for both simulation and phantom) indicate that the GS typically achieves detection rates of over 90% (at 10% false alarm rates) over a broad range of SNR values (3–21 dB). The GS detection performance exceeds that of the cepstrum and exhibits more robustness to noise and signal processing parameters. Simulation results with fixed system effects indicate better estimation performance for cepstral-based methods, while experimental phantom results show the GS estimation performance to be the same or better than the cepstral-based method.
The current trends of the global chemical fibre and thread market are reviewed. Special attention is focused on polyamide and polyester industrial threads. Structural changes in the global textile ...industry due to economic crisis, mechanisms of formation of regional markets in terms of types of fibres, global output and consumption of chemical fibres, and major areas of use are studied. Outlook for future growth of cellulose and synthetic fibres is elucidates, average growth rate and decline of output in various regions are shown, and dominance of China and its driving force in the growth of global textile industry are noted.
Modern suturing materials are developed with a focus on the requirements of surgeons for the optimum mechanical characteristics; interchangeability; compatibility; safety; a lack of allergic, ...teratogenic, and cancerogenic action in vivo; and a lack of capillary action. Biologically active (BA) thread with a complex action that was prepared by impregnating polyamide or polyester thread-base with a modified composition based on the biopolymer chitosan and including the antibacterial preparation ciprofloxacin and the germanium-containing preparation Astragerm-C was selected for the studies. The goal was to study the effects of the selected modification method and the composition of the modifier on the functional properties of a new surgical suturing material. It was shown that the produced surgical suturing material had improved functional properties that comply with modern requirements.
Translated from
Khimicheskie Volokna
, No. 1, pp. 57–62, January-February, 2011.
The degree of the effect of structural parameters on the physical and operational properties of fibre materials was estimated. The determining effect of the thickness of the material on the air ...permeability and sound-absorbing coefficient, thickness, and porosity on the heat resistance, and fibre diameter on the change in the filtering and sorption properties of porous walls was established.PUBLICATION ABSTRACT
This article examines how the structure of a polyethylene filament obtained by the gel method changes during its orientational drawing. It is shown that the length of the crystallites increases and ...the crystallization front moves deep into the amorphous interlayers of the nanofibrils as the drawing operation proceeds. As a result, the amorphous regions of the filament may be almost completely crystallized and a continuous crystalline phase may be formed. The end result of these transformations is the formation of an anisotropic product having excellent elastic and strength characteristics.
We have studied the effect of elastomer additives on the properties of spin dopes for obtaining filled fiber materials by aerodynamic spinning from polymer solutions. We have obtained laboratory ...samples of materials with different polyurethane content. We have analyzed the results of physicomechanical, sorption, and physical tests of these materials. We show that modification of filled fiber materials by introducing elastomeric additives has only an insignificant negative impact on the sorption properties and markedly improves their physicomechanical characteristics.
This paper examines the detection of regular scatterer spacings from backscattered ultrasound using the autoregressive (AR) cepstrum. Monte Carlo simulations present a relationship between the ...probability of detection and the AR model order. An example using liver tissue data supports the observations made in the simulation.
The research groups at Drexel University and Thomas Jefferson University had proposed the use of non-Rayleigh statistics for tissue characterization. Previous work based on the hypothesis that the ...envelope of the backscattered echosignal from abnormal regions of the tissue is more likely to be K-distributed than Rayleigh distributed, used the parameter of the K-distribution, M, to distinguish between regions containing benign or malignant masses and normal ones. In this work the B-scan breast images of 19 patients were studied using this approach. Previous studies have also been extended to exploit the existence of non-uniform phase characteristics of the echosignal from scatterers with some regular spacings, such as those in a periodic or quasi-periodic alignment. Computer simulations were carried out to show that the phase statistics deviate significantly from uniform in the range of {0, 2π} if the imaging region contained a number of periodically aligned (regular lattice) scatterers along with a collection of randomly distributed scatterers resulting in a quasi-periodic arrangement. This methodology was then applied to B-scan images of the breasts to distinguish between benign and malignant masses. If benign lesions show some sort of quasi-periodic or regular structures in the tissue, they will present non-uniform phase characteristics while more randomly structured malignant masses will have uniform phase characteristics. It is seen that the K-distribution may be used to identify the abnormal regions in the breast images and information on the phase may be used to further separate the abnormal regions into benign and malignant ones.
A mathematical model of aerodynamic extension of a polymer jet was developed with consideration of its hyperelastic properties. The results of an experimental study of aerodynamic extension of ...equiviscous solutions in DMF of acrylonitrile copolymers (ANCP) with different specific viscosity are reported. The calculated and experimental characteristics of aerodynamic spinning from polymer solutions are compared. The determining role of hyperelastic strain in strengthening of the jet in stretching it in the secondary spinnability zone is established.PUBLICATION ABSTRACT
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