No description available.

Integration of material composition, microstructure, and mechanical properties with geometry information enables many product development activities, including design, analysis, and manufacturing. To address such needs, models of material composition have been integrated into CAD systems, creating systems called heterogeneous CAD modeling. In order to support the heterogeneous CAD system, extensive process-structure-property relationships have to be captured and integrated into current CAD system. A new method for reverse engineering of materials will be presented such that microstructure models can be constructed and used in the heterogeneous CAD system. Reverse engineering of material consists of three parts: image analysis, structure-property-process relationship, and repository. In this research, an image processing method, which comprises the Radon transform and the wavelet transform, will be used in order to recognize geometric features from a microstructure image. Recognizing geometric features can be obtained by combinations of three techniques, masking, clustering, and high frequency component on wavelet transform, that are integrated with the Radon transform. Then, recognized geometric features can be used to construct an explicit geometric model of microstructure. The proposed work will provide an explicit mathematical method to recognize and to quantify microstructure features from an image. In addition, explicit geometric models of microstructure can be automatically constructed and utilized to get effective mechanical properties, establishing structure-property relationship of the material. In order to demonstrate this, polymer nano-composite sample and metal alloy sample will be used.

Published Article / Atkinson distinguishes between four types of prototypes, categorised through its end-use: •Design or aesthetic prototypes •Geometrical prototypes •Functional prototypes •Technological prototypes Shigley and Mitchell define the design process according to the following six phases: Recognition of need Definition of problem Synthesis Analysis and optimization Evaluation Presentation The Centre for Rapid Prototyping and Manufacture (CRPM) of the Central University of Technology, Free State was asked to assist in the development of a newly developed gynaecological cream applicator. Apart from needing a freeform fabrication system to give form fit and function to the very complex design, the product needed Rapid Tooling / Rapid Manufacturing support to enable a first batch production for medical trials and evaluation. The paper will describe the total product development process alongside prototype categories described by Atkinson and design phases defined by Shigley and Mitchell (including some iterations enabled through timeous prototyping, including various Rapid Prototyping (RP) Technologies, soft tooling and vacuum casting). More importantly, results from Rapid Tooling for limited run production (due to the complexity of the product the cycle time of the Prototype Tool is fairly long), as well as the economical impact made possible through the support of CAD / CAM and RP Technologies, will be discussed.

Published Article / This article examines the synergy between aesthetic and technical issues surrounding current input and output modes applicable to digital sculpture built by means of additive fabrication technologies. The scope is limited to select sculptural aspects that either transcend, question or fall short when measured against traditional manufacturing and aesthetic modes. Presented are a range of technical as well as aesthetic aspects that have impacted on this ''new form'' of sculpture delivery. It is indicated that irrespective of current strengths and weaknesses, for the evolving sculptor, an interactive creative partnership between technologies equally positions this ''new form'' of sculpture delivery as a leading role player towards defining a new digital aesthetic.

Rapporten går igenom steg för steg processen att ta fram datormodellen Diasock. Idag så finns det många människor som lider av diabetes och många utav dessa personer drabbas även av fotproblem. Fotkomplikationer är svåra att behandla och patienter kommer ofta in för sent med sina sår som i värsta fall kan leda till amputation. I samarbete med forskarna på Linköpings universitetssjukhus gavs uppdraget att ta fram en strumpa med insydda sensorer. Strumpan kommer underlätta för diabetiker då de själva kan ha en överblick på sina egna värden och på så sätt söka vård i tid om de behövs. Gruppen har blivit inspirerad av Fredy Olssons metod princip och primärkonstruktion(1995) som använts i tidigare kurser. Det gjordes även ett studiebesök på sjukhuset för att få mer insikt i alla problem som kan uppstå och för att få nya perspektiv från andra yrkesroller. Gruppen lade ner mycket tid på att anpassa strumpan efter en diabetikers fot, då de har speciella krav och inte kan använda vanliga strumpor. Mycket fokus hamnade även på placering av sensorerna. Det gjordes många skisser och efterhand valdes det att utgå ifrån funktionsstrumpan med sensorer på/vid tryckpunkterna. Strumpan är ritad i CATIA V5 där det valdes att arbeta i arbetsbänken Imagine & Shape. För att bättre visualisera datormodellen användes programvaran Keyshot där materialen blir mer realistiska. Projektet resulterade i en datormodell av en strumpa, speciellt utformad för att motverka uppkomsten av diabetessår. Strumpan blev anpassad för att passa en diabetiker.

International Telemetering Conference Proceedings / October 30-November 02, 1995 / Riviera Hotel, Las Vegas, Nevada / Conformal printed antennas of arbitrary shape are used for telemetry applications on high velocity vehicles due to their small size and light weight. The design of these antennas is difficult, however, since there are few accurate analytical models that take the effects of curvature into account. This paper discusses a computer aided design (CAD) tool for arbitrarily shaped printed antennas on cylindrical structures based on a rigorous analytical model. The tool is combined with a graphical user interface and can help antenna designers achieve close to optimal performance. An overview of the mathematical model is given here and the CAD tool is used to highlight the effects of curvature on printed antenna performance. Methods of obtaining circular polarization are reviewed.

No description available.

Myocardial perfusion imaging (MPI) is an effective technique used to study the left ventricular ejection function (LVEF), myocardial perfusion, wall motion, and wall thickening. Positron emission tomography (PET) and single photon emission computed tomography (SPECT) are two modalities that can be used to quantify the left global and regional perfusion at rest and stress. While PET and SPECT rely on similar principles to produce images, important differences in instrumentation and experimental applications are dictated by inherent differences in their respective physics of radioactive decay. With a sensitivity > 90% in combination with a high specificity, PET is today the best available nuclear imaging technique for the diagnosis of coronary artery disease (CAD). The short half-life of the perfusion tracers in combination with highly sophisticated hard- and software enables rapid PET studies with high patient throughput. Rubidium-82 (82Rb) is a PET perfusion imaging agent that has a shot half-life of 76 seconds which enables multiple sequential data acquisitions in a short duration of time. It also reduces the number of false-positive SPECT scans and artifacts from soft tissue attenuation due to the routine application of attenuation correction. However 82Rb PET imaging is under-utilized clinically due to difficulty optimizing the imaging parameters. The major challenge of 82Rb imaging is determining when to begin the image acquisition post infusion, as imaging too early results in images with high background (low contrast), and imaging too late results in noisy images due to low count statistics. 82Rb rest/stress dynamic and gated data from 16 patients were available for analysis. The FWHM of the 82Rb infusion, LV cavity and LV myocardial uptake in time activity curves were generated and compared to isolate the dominant parameter in determining image quality. The measured and actual infusion-time correlated only at rest (r = 0.93, P = 0.006). Splitting-time at rest and stress correlated (r = 0.74, P = 0.09). But the study was not able to identify a single dominant parameter that would determine the image quality due to the unpredictable nature of hemodynamics during the vasodilatory induced cardiovascular stress. First pass radionuclide angiography (FPRNA) is the gold standard for quantification of ejection fraction. We examined the quantification of the ejection function (LVEF) to determine whether the gated 82Rb PET data, using quantitative gated SPECT (QGS), would accurately predict changes in the chamber volume and correlated the results with those obtained from FPRNA technique. There was a good correlation between the resting FPRNA data and resting gated 82Rb QGS data (r= 0.81, P=0.0005) showing that this method can be applied to 82Rb PET.99mTc SPECT was considered the gold standard for this study, as it is the most widely used technique for myocardial perfusion imaging. The under-perfused area of the myocardium is defined as defect. 99mTc agents, 18F-FDG, and 82Rb can all be used for cardiac imaging 1-7. However, count rates, energy and camera differences can yield image differences that are independent of the actual biological distribution. We examined whether PET with an 82Rb-labeled tracer would provide information on defect size similar to that provided by 99mTc SPECT, using a cardiac phantom in which the true defect size is known. Since 82Rb has such a short half-life (76 seconds), filling and imaging a phantom was going be a great challenge. Hence 124I which is a high-energy radioisotope like 82Rb, was used in this phantom study as a surrogate for 82Rb. Static cardiac phantom studies with 99mTc, 18F and 124I (surrogate for 82Rb) were conducted. The percent defect sizes were measured and compared with the true defect size. Our results demonstrated that at 45% threshold, the measured defect size was representative of true defect size for 99mTc SPECT data. Using this threshold as the standard, we smoothed the 18F and 124I PET data until the measured defect size for PET was representative of the true defect size. An optimal filter cutoff frequency (Butterworth filter, cutoff = 0.80 cycles/pixel, order=5 at 45% threshold for 124I or 82Rb) was found for the PET data within the range of values studied, and this frequency was higher than the clinical norm for SPECT data. Our results also illustrated that the measured SPECT defect size varied greatly depending on the thresholds used to define a defect, whereas measure PET defect size was relatively constant over the range of cutoffs tested7. The optimal cutoff may depend on defect size, patient variability, and noise level. When assessing myocardial defect size, physical properties need to be taken into consideration, particularly when comparing images obtained using different nuclides (i.e. 82Rb or 99mTc agent perfusion and 18F FDG viability).

Detta är ett projekt som har utförts under hösten 2016 för Högskoleingenjör i maskinteknik vid Umeå universitet. Arbetet omfattade 15 högskolepoäng.  Syftet med projektet är att ta fram nya formatdelar till en maskin som APL använder i sin produktion. Maskinen i fråga fyller flaskor med vätska som sedan försluts och skickas vidare till nästa station. APL använder sig av flera olika storlekar på dessa flaskor men har endast tillgång till en storlek på formatdelarna. Detta skapade ett problem när man arbetade med de mindre flaskorna eftersom man då blev man tvingad att lägga in inlägg på de ställen där formatdelarna var för stora.  De material som de gamla formatdelarna bestod av var även ett område som undersöktes. Detta med anledning av att alla delarna värmesteriliseras innan de används i maskinen och under en sådan behandling så utsätts materialet för höga temperaturer. Med det material som används i dagsläget så orsakar uppvärmningen att delarna tappar sin form eftersom de inte är gjorda för de temperaturer som de utsätts för i autoklaven. Syfte med de här projekten är alltså att ta fram 3D-modeller för nya formatdelar som är anpassade efter de flaskorna med mindre dimensioner, samt att undersöka om det finns andra material som kan vara mer lämpade för de påfrestningar som delarna utsätts för.   För att uppnå detta så har de gamla formatdelarna undersökts och skissats av. Därefter har de relevanta måtten korrigerats och de nya modellerna har ritats upp i CAD-programmet Solid Works.  En undersökning om materialmöjligheterna har även gjorts, då med fokus på olika plastmaterial samt de tillverkningsmetoder som är relevanta. Fokus när det gällde materialen låg till största del på egenskaper vid höga temperaturer. Värden har tagits ur tabeller, beräkningar har gjorts och tillsammans visar detta vilket material som är bäst lämpat för APLs ändamål. / This is a project that has been carried out in autumn 2016 for Bachelor of engineering in mechanical engineering at Umeå University. The work included 15 credits.  The aim of the project is to produce new parts for a machine that APL uses in its production. The machine in question fills bottles with liquid which is then sealed and sent on to the next station. APL makes use of several different sizes of these bottles but only have access to one size of format elements. This created a problem in that when you are working with the smaller bottles you are forced to put some extra material in where the format parts were too big.   The materials that the old format parts consisted of was also an area that was investigated. This is because all parts are Heat-sterilized before they are used in the machine and during such treatment they are exposed to high temperatures. With the material used at the present time this heating process was causing the parts to lose their shape as they are not made for the temperature to which they are exposed. The purpose of this project is thus to produce 3d-drawings for the new format elements that are tailored to the bottles with smaller dimensions, as well as to investigate whether there are other materials that may be more suitable for the strain that parts are exposed to.   To achieve this, i have examined the old parts and have taken the relevant measurements. The old measurements have been corrected and the new models have been drawn up in the CAD program SolidWorks. Since then, dimensioned drawings designed to serve as a manufacturing base have been made.   A study on material opportunities has also taken place, focusing on different plastic materials and the manufacturing processes that are relevant. Focus in terms of the materials was largely put on properties at high temperatures. Values are obtained from tables and calculations have been made, and together, this shows what material is best suited for the APLs purposes.

OBJECTIVE: The purpose of this in vitro study was to evaluate the cutting performance and accuracy of CAD/CAM diamond burs in different chemo-mechanical conditions when machining yttria-stabilized zirconia (YTZ), lithium-disilicate, feldspathic porcelain, and double network hybrid ceramic material. The study also examined bur wear mechanisms. MATERIALS AND METHODS: Two experiments were performed. Experiment 1: 45 samples of each material were milled, and four criteria were tested: milling time; surface roughness; change in bur weight after machining, and total cement space. Experiment 2: Four different coolant liquids were used while machining 15 samples of lithium-disilicate, feldspathic porcelain, and double network hybrid ceramic material. The four criteria in Experiment 1, plus marginal adaptation, were measured. Burs and ceramic materials used were examined with SEM before and after machining. RESULTS: Experiment 1: All burs milled 15 crowns of each material successfully, with a general increase in milling time and decrease in weight. Four wear patterns were identified: grit cracks, micro-fractures, dislodgement, and matrix abrasion. Sequential milling time increased for all of the ceramic materials. Surface roughness (Ra) decreased in general for all materials used in the study except YTZ, which showed an increase in Ra by the end of the machining series. Experiment 2: Additives used in this study had no significant effect on IPS e.max CAD milling efficiency or Ra. Boric acid reduced Vita MarkII machining time significantly and Ra. CONCLUSIONS: The cutting rate of diamond burs differed when machining different ceramic materials. In sequential machining, every consecutive milling demonstrated lower cutting efficacy. The surface roughness of consecutive machined samples differed. Some cooling liquids affected the quality of the machined surface. The bur wear mechanism was the same when different ceramic materials were machined, and their microstructure affected their machinability. / 2019-09-26T00:00:00Z