scholarly journals Polyadic Cantor Fractal Ultrasonic Lenses: Design and Characterization

2018 ◽  
Vol 8 (8) ◽  
pp. 1389 ◽  
Author(s):  
Sergio Castiñeira-Ibáñez ◽  
Daniel Tarrazó-Serrano ◽  
Jose Fuster ◽  
Pilar Candelas ◽  
Constanza Rubio

Traditional acoustic lenses modulate the ultrasonic beam due to their curved surfaces and the refractive material of which they are made. In this work, a different type of acoustic lens, based on Polyadic Cantor Fractals (PCF), is presented and thoroughly analyzed. These new Polyadic Cantor Fractal Lenses (PCFLs) are completely flat and easy to build, and they present interesting modulation capabilities over the acoustic profile. The dependence of the focusing profile on the PCFL design parameters is fully characterized, and it is shown that certain design parameters provide a dynamic control, which is critical in many medical applications such as thermal ablation of tumors.

1976 ◽  
Vol 15 (02) ◽  
pp. 69-74
Author(s):  
M. Goldberg ◽  
B. Doyon

This paper describes a general data base management package, devoted to medical applications. SARI is a user-oriented system, able to take into account applications very different by their nature, structure, size, operating procedures and general objectives, without any specific programming. It can be used in conversational mode by users with no previous knowledge of computers, such as physicians or medical clerks.As medical data are often personal data, the privacy problem is emphasized and a satisfactory solution implemented in SARI.The basic principles of the data base and program organization are described ; specific efforts have been made in order to increase compactness and to make maintenance easy.Several medical applications are now operational with SARI. The next steps will mainly consist in the implementation of highly sophisticated functions.


Author(s):  
V. Lisovenko ◽  
D. Lisovenko ◽  
O. Bazyk

Many energy saving tasks can be solved thanks to the current advances in LED technology in the production of semiconductor light sources. Modern production of solid-state LEDs guarantees high-precision compliance with the calculated design parameters of illumination devices. This opens up wide opportunities for high-precision control of the lighting parameters of a multicomponent module: light power, a directional pattern and a distribution of illumination. Today, the methodical issues of the preliminary modeling of LED illumination devices with the given parameters are fundamentally solved. There is a shift from manual calculations to computer design and need to develop and select the most effective mathematical modeling methods. The paper presents a consistent approach to the modeling of the distribution of illumination on a horizontal plane from the planar LED module, based on the Lambert type of radiation of a single point source. Simple mathematical expressions, programmed on a personal computer, are obtained. The example of a 25-LED floodlight has shown the ability of dynamic control the lighting characteristics of the module. Connecting patterns of separate LEDs or their groups allow to change the direction pattern of the lamp by the appropriate way of switching diodes with different aperture of radiation. The lighting power can be controlled within the linearity of the ampere-brightness characteristics by changing the current strength through the LED. The static selection of characteristics is controlled by the geometry of the location of discrete sources. The formation of uniform illumination of the plane is graphically illustrated. The electron-dynamic way of controlling the lighting parameters of the LED floodlight is confirmed by the inventor’s certificate.


1998 ◽  
Vol 37 (9) ◽  
pp. 105-112 ◽  
Author(s):  
Ana María Ingallinella ◽  
Luis María Stecca ◽  
Martin Wegelin

This paper presents the methodology used for the rehabilitation of the pretreatment stage in a water treatment plant for a village located in Bolivia which has 3500 inhabitants. The treatment plant was initially composed by horizontal-flow roughing filters and slow sand filters, but due to the high contents of colloidal turbidity of the providing source, it did not work properly. A plan of rehabilitation was made which comprised laboratory tests, pilot tests and proposal of modifications based on the results of previous stages. The laboratory tests were made in order to find the optimum conditions to coagulate the raw water. It was found that horizontal-flow roughing filters must be turned into up-flow roughing filters, so a pilot plant was built and was operated for three months in order to find suitable design parameters. The results obtained obtained during the operation of the pilot plant and the proposal of modifications are presented. The results of operation of the final plant, which are also reported, demonstrated the advantages of the up-flow roughing filtration as a pretreatment stage when it is necessary to add chemical products in small treatment plants.


1971 ◽  
Vol 93 (1) ◽  
pp. 74-84 ◽  
Author(s):  
S. A. Oleksa ◽  
D. Tesar

The geared five-bar linkage is the foundation for a function generation problem meeting specifications for 5 multiply separated positions and containing 4 free design parameters. The four-bar linkage is shown to be a member of this class of mechanisms. Design examples of rarely treated functions are given with the quality of the generated approximation. Suggestions are made in terms of the 4 design parameters to assist the designer in obtaining good results.


1980 ◽  
Vol 102 (3) ◽  
pp. 395-400 ◽  
Author(s):  
G. G. Hirs ◽  
J. IJ. Sonneveld

The method relates to the production of shallow recesses in surfaces by etching. Recesses in metal surfaces are particularly suitable for use in sliding bearings for rotating components and in some other machine elements. Frequently, such recesses have a depth of 10 microns or more and are made in the form of intricate groove patterns on curved surfaces. According to the new method, etching fluid is caused to flow by means of a flow guiding template onto areas determined by this template along the surface to be etched. The etching rate on the areas to be etched is controlled by adjustment of the flow velocity of the etching fluid and the slit height of the flow guiding template. The recesses or grooves are deeper when the flow velocity of the etching fluid and the slit height are both higher. The paper gives a brief description of the new etching method and a comparison with other fabrication methods such as photochemical etching and electro-chemical machining. The new method appears to be preferable to others for large series production. The paper concludes with theoretical work in which the etching process is explained in terms of mass transfer by connective diffusion and with some experimental results using a simplified flow guiding template design.


Flow visualization is the direct observation of fluid flow. Moving fluids form complex patterns and understanding and visualizing those patterns is an important aspect in aerospace industry. The previously existing research and results were taken into consideration for design parameters and calculation for dimensions of various parts of the wind tunnel. Design calculations allow wind velocities in the range of 1-3 m/s at the test section. The design includes a rectangular test section of 0.06m x 0.30m cross-section for accommodation of test object of width 0.06m. The design was made in SolidWorks and was fabricated with basic materials like plywood and acrylic sheets. PC cabinet fans were used for flow circulation. Liquid wax is utilized for the purpose of smoke generation and rubber and PVC pipes were utilized for smoke containment and delivery system. Profiles that were used for testing included cylinder, sphere, cuboid, NACA airfoils and flat plate.


2018 ◽  
Vol 12 (3) ◽  
Author(s):  
Bradley Hanks ◽  
Mary Frecker ◽  
Matthew Moyer

Radiofrequency ablation (RFA) is an increasingly used, minimally invasive, cancer treatment modality for patients who are unwilling or unable to undergo a major resective surgery. There is a need for RFA electrodes that generate thermal ablation zones that closely match the geometry of typical tumors, especially for endoscopic ultrasound-guided (EUS) RFA. In this paper, the procedure for optimization of an RFA electrode is presented. First, a novel compliant electrode design is proposed. Next, a thermal ablation model is developed to predict the ablation zone produced by an RFA electrode in biological tissue. Then, a multi-objective genetic algorithm is used to optimize two cases of the electrode geometry to match the region of destructed tissue to a spherical tumor of a specified diameter. This optimization procedure is then applied to EUS-RFA ablation of pancreatic tissue. For a target 2.5 cm spherical tumor, the optimal design parameters of the compliant electrode design are found for two cases. Cases 1 and 2 optimal solutions filled 70.9% and 87.0% of the target volume as compared to only 25.1% for a standard straight electrode. The results of the optimization demonstrate how computational models combined with optimization can be used for systematic design of ablation electrodes. The optimization procedure may be applied to RFA of various tissue types for systematic design of electrodes for a specific target shape.


Author(s):  
Olga Krivenko ◽  
Peter Kulikov ◽  
Andrey Zaprivoda ◽  
Vitaliy Zaprivoda

The aim of research is to simulate the zones of solar radiation on the curved surfaces of the shells of high-rise buildings for the effective use of renewable solar energy. An urgent task is the development of tools that can substantiate the decision-making by designers about the location of solar thermal devices in the energy-efficient design of curvilinear high-rise buildings. The main attention is paid to high-rise buildings, is actively growing in modern megalopolises and requires a significant energy resource. To optimize the integration of solar thermal devices in high-rise buildings, it is important to take into account a set of design parameters, including parameters of surface shape and location in space. A feature of curved surfaces, considered in the study, is their aerodynamic properties, which provide them with the advantage of choosing among modern high-rise buildings. At the same time, the complexity of setting the parameters of a curved surface to determine the zones of solar radiation for the effective use of regenerative solar energy lies in providing reliable and convenient tools for optimizing decision-making. The study proposes an application of the method based on a discrete geometric model of solar radiation input on the surface of the shells of high-rise buildings, described by compartments of curved geometric surfaces. As a result of modeling, let’s obtain a family of lines of the same level of solar radiation on a certain curved surface for the given parameters of time and geographic location. As an example of simulation modeling, the performed calculations of the instantaneous model of the distribution of solar radiation on the compartments of the curved surfaces of an ellipsoid of revolution, hemisphere, hyperbolic paraboloid. On the basis of the proposed model for the distribution of solar radiation over curvilinear surfaces of buildings, the influence of factors arising in the design process is investigated: changes in the geometric parameters of the surface shape, orientation to the cardinal points, the formation of zones of its own shadow on surfaces. Calculations were performed and instantaneous solar radiation zones were constructed on the surfaces of a hemisphere, a hyperbolic paraboloid with various geometric parameters, taking into account different orientations relative to the cardinal points, and determining the zones of its own shadow. At this stage of the study, the result is an algorithm for constructing zones of different levels of solar radiation on curved surfaces of high-rise buildings. The advantage of the algorithm is the ability to analyze the results of changes in the design parameters of the surface of a high-rise building when placing solar systems on them. The proposed approach will provide a basis for automating the modeling process, will help expand the scope of solar systems in high-rise construction and increase the efficiency of their work


2017 ◽  
Vol 34 (03) ◽  
pp. 280-287 ◽  
Author(s):  
Raja Shaikh

AbstractUnderstanding and management of vascular anomalies has always been intriguing. These disorders exhibit an expected pattern of clinical presentation and progression, and characteristic imaging findings. Significant progress in understanding and treating patients with vascular anomalies has been made in the past quarter century. Newer multidisciplinary domains for treating these disorders with medical drugs and less invasive image-guided or surgical procedures are constantly evolving. Vascular anomalies can exhibit aggressive tumor-like behavior resulting in recurrence or persistent symptoms after treatment. Thermal ablation has been widely used in tumor treatment. This has generated interest on using thermal ablation for treating vascular anomalies. Percutaneous image-guided cryoablation is increasingly used for this purpose as compared with other ablation technologies. Availability of small caliber cryoprobes and the ability to monitor the freeze zone in real time have made this an attractive option to interventional radiologists. These experiences are relatively new and limited. It is helpful to understand the emerging role of this technology in the treatment of vascular anomalies.


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