Foreign Inclusions Research Articles

Improving Automatic Detection of Defects in Castings by Applying Wavelet Technique

X-ray-based inspection systems are a well-accepted technique for identification and evaluation of internal defects in castings, such as cracks, porosities, and foreign inclusions. In this paper, some images showing typical internal defects in the castings derived from an X-ray inspection system are processed by some traditional methods and wavelet technique in order to facilitate automatic detection of these internal defects. An X-ray inspection system used to detect the internal defects of castings and the typical internal casting defects is first addressed. Second, the second-order derivative and morphology operations, the row-by-row adaptive thresholding, and the two-dimensional (2-D) wavelet transform methods are described as potentially useful processing techniques. The first method can effectively detect air-holes and foreign-inclusion defects, and the second one can be suitable for detecting shrinkage cavities. Wavelet techniques, however, can effectively detect the three typical defects with a selected wavelet base and multiresolution levels. Results indicate that 2-D wavelet transform is a powerful method to analyze images derived from X-ray inspection for automatically detecting typical internal defects in the casting

Interaction of micropipes with foreign polytype inclusions in SiC

Synchrotron phase sensitive radiography, optical and scanning electron microscopies, and color photoluminescence have been used to study the interaction of micropipes with foreign polytype inclusions in 4H-SiC bulk crystals grown on 6H-SiC substrates. This combination of techniques confirms that micropipes agglomerate at the polytype inclusions and merge into pores. A mechanism for this phenomenon is suggested based on a three-dimensional theoretical model; the inclusion boundaries elastically interact with micropipes, causing them to migrate from the bulk to their equilibrium positions at the polytype boundaries. The turning of micropipes towards the inclusions is experimentally demonstrated, and the reduction of their density in nearby regions is revealed. Supported by experimental observations, our model helps to understand the pore formation and expansion in SiC bulk crystals.

Histologic Evaluation of Implants Following Flapless and Flapped Surgery: A Study in Canines

Flapless surgery requires penetration of the alveolar mucosa and bone without reflection of mucoperiosteal flaps. Do these techniques force gingival tissue or foreign materials into osteotomies? If so, do such tissues or materials interfere with osseointegration? A proof-of-principle study using a canine model attempted to answer these questions. Five young adult Hound Labrador mongrel dogs received implants with a moderately roughened surface by anodic oxidation using flapless or conventional one-stage (control) surgery in contralateral jaw quadrants. The implants were placed into the osteotomies, and the international stability quotient (ISQ) was recorded using resonance frequency analysis. These measurements were repeated following a 3-month healing interval when the animals were euthanized, and implants and surrounding tissues were retrieved and processed for histologic analysis. The implants were stable upon insertion and demonstrated increased stability at 3 months without significant differences between surgical protocols. The histologic evaluation showed high bone-implant contact (flapless surgery: 54.7% +/- 8.4%; control: 52.2% +/- 13.0%; P >0.05) without evidence of gingival tissue or foreign body inclusions. There were no significant differences in marginal bone levels between the surgical protocols. Post-insertion and at 3 months, ISQ values depended on the amount of torque delivered. Immediately post-insertion, for every 1-unit increase in torque value, the ISQ increased by 0.3 (95% confidence interval: 0.1 to 0.4; P = 0.0043). Three months postoperatively, for every one-unit increase in torque the ISQ value decreased 0.2 (95% confidence interval: -0.4 to -0.1; P = 0.0012). The effect of torque on ISQ values was independent of treatment effects and remained significant after adjustment for treatment. The results suggest that implants placed without flap reflection remain stable and exhibit clinically relevant osseointegration similar to when implants are placed with flapped procedures. Greater torque at implant placement resulted in less implant stability at 3 months.

Forensic visualization of foreign matter in human tissue by near‐infrared spectral imaging: Methodology and data mining strategies

Rapidity of data acquisition, high image fidelity and large field of view are of tremendous value when looking for chemical contaminants or for the proverbial "needle in the haystack" - in this case foreign inclusions in histologic sections of biopsy or autopsy tissues. Near infrared chemical imaging is one of three chemical imaging techniques (NIR, MIR and Raman) based on vibrational spectroscopy, and provides distinct technical advantages for this application. We have chosen to utilize and evaluate near infrared (NIR) imaging for studies of foreign materials in tissue because the experimental configuration is relatively simple, data collection is rapid, and large sample areas can be screened with high image fidelity and spatial resolution. We have shown that NIR imaging can readily find and identify silicone gel inclusions in biological tissue samples. Additionally, preliminary results indicate that spectral signatures in the data set are also potentially sensitive to structural changes in the surrounding tissue that may be induced by the foreign body. NIR chemical imaging is a powerful, non-destructive tool for localization and identifying foreign contaminants in biological tissue. Preliminary results indicate that NIR imaging is also sensitive enough to differentiate tissue types (perhaps based on collagen structural differences), and provide data on the spatial localization of these components.

Investigation of Dislocation Behavior during Bulk Crystal Growth of SiC

AbstractIt is well-known that SiC crystal deficiencies are delaying the realization of outstandingly superior SiC power electronics. Efforts to date have centered on eradicating micropipes, and 4H-SiC substrates with extremely low micropipe densities have been achieved. Nevertheless, SiC substrates and epilayers still contain several types of dislocations in densities on the order of thousands per square centimetres, which are nearly 100-fold micropipe densities. While not nearly as detrimental to SiC device performance as micropipes, it has recently been demonstrated that dislocations existing in SiC crystals degrade several characteristics of SiC devices, e.g., the forward bias characteristics of SiC pin diodes and the gate oxide reliability of SiC MOSFETs.This paper reports several dislocation processes occurring during the growth of hexagonal SiC bulk crystals. Particularly, we focus on the dislocation formation and propagation processes in SiC crystals. We have investigated dislocation processes in 4H-SiC bulk crystals grown by the physical vapor transport (PVT) growth method, using defect selective etching and transmission electron microscopy (TEM).It was found that foreign polytype inclusions introduced a high density of dislocations at the polytype boundary. In the polytype-transformed areas of the crystal, very few medium size hexagonal etch pits due to threading screw dislocations were observed, indicating that the polytype transformation ceased the propagation of threading screw dislocations. The oval-shaped etch pit arrays observed on the etched vicinal (0001)Si surface, indicative of the dislocation multiplication in the basal plane, showed characteristic distribution around micropipes and low angle grain boundaries. Based on the results, we will argue the dislocation behavior in PVT grown SiC crystals, suggesting that dislocation interaction and conversion are relevant processes to understanding the behavior.

Dislocation processes during SiC bulk crystal growth

Dislocation processes during physical vapor transport (PVT) growth of silicon carbide (SiC) single crystals were investigated by defect selective etching. It was found that foreign polytype inclusions introduced a high density of dislocations at the polytype boundary. In the polytype-transformed areas of the crystal, very few medium size hexagonal etch pits due to threading screw dislocations were observed, indicating that the polytype transformation ceased the propagation of threading screw dislocations. The oval-shaped etch pit arrays observed on the etched vicinal (0 0 0 1)Si surface, indicative of the dislocation multiplication in the basal plane, showed characteristic distribution around micropipes. Based on the results, we have argued the dislocation behavior in PVT grown SiC crystals, suggesting that dislocation interaction and conversion are relevant processes to understanding the behavior.

Propagation behavior of threading dislocations during physical vapor transport growth of silicon carbide (SiC) single crystals

The dislocation formation and propagation processes in physical vapor transport (PVT) grown 4H silicon carbide (4H–SiC) single crystals have been investigated using defect selective etching and transmission electron microscopy (TEM). It was found that while the growth initiation process generally increased the density of threading dislocations in the grown crystal, for certain areas of the crystal, threading dislocations were terminated at the growth initiation. Foreign polytype inclusions also introduced a high density of dislocations at the polytype boundary. In the polytype-transformed areas of the crystal, almost no medium size hexagonal etch pits due to threading screw dislocations were observed, indicating that the foreign polytype inclusions had ceased the propagation of threading screw dislocations. Based on these results, we argued the formation and propagation of the threading dislocations in PVT grown SiC crystals, and proposed the dislocation conversion process as a plausible cause of the density reduction of threading dislocations during the PVT growth of SiC single crystals.

Comparative analysis of one-particle mathematical models in materials science and oncology. I. Mathematical models

The mathematical formalism is studied for medium — foreign spherical inclusion models (in materials science) and body tissue — spherical tumor models (in oncology). It is established that they are similar, which is a frequently encountered phenomenon for general laws in mathematical descriptions of very different types of processes (for example, diffusion and thermal conductivity, electromagnetic oscillations and sound, statistical mechanics and population dynamics). A typical process occurring with powders in metals technology and nature is a complex process including diffusion and chemical reaction. Such a process sometimes relates to diffusion in the active medium. Special cells in the body (lymphocytes) appear outside tumors, move toward them, penetrate into them, and trap tumor cells. It is suggested that the lymphocytes can be considered as analogs of diffusing particles (the diffusant) while the tumor cells can be considered as analogs of traps in the case of diffusion in an active medium. An equation is also proposed that describes the behavior of an ensemble of tumor cells under the influence of a magnetic field.

A Crack with Interfacial Bonds in an Isotropic Medium Strengthened with a Regular System of Stringers

An isotropic medium containing a system of foreign transverse rectilinear inclusions is considered. Such a medium can be interpreted as an infinite plate strengthened with a regular system of ribs (stringers) whose cross section is a very narrow rectangle. The medium is weakened by a rectilinear crack. The action of the stringers is replaced with unknown equivalent concentrated forces at the points of their connection with the medium. A model of a crack with areas where its faces interact with each other is investigated. This interaction is modeled by introducing bonds (adhesion forces) between faces in the crack tip zone. The boundary-value problem on equilibrium of the crack under the action of external tensile forces is reduced to a nonlinear singular integral equation, from the solution of which the tractions in the bonds are found.

Language learning

Language learning

Foreign language learning and inclusion: Who? Why? What?- and How?

The presumption of mainstream schooling and the removal of core status for foreign language learning at Key Stage 4 are presenting new challenges to our ideal of foreign language learning for all. In the current climate, the case for including children with special educational needs in foreign language classes has to be made with greater clarity than ever. In this article Hilary McColl considers what foreign language learning is really for and how we can justify its inclusion in the curriculum of all our young people. She suggests that for all learners, whatever their ability, foreign language learning only makes sense if it is set within the context of the communities that use the language, and that for some learners these twin concepts of ‘communication’ and ‘community’ can only be understood if we make explicit links between what is distant-and-strange and what is close-and-familiar. She asks whether the courses we currently offer can achieve the outcomes we say we desire, and suggests what steps we need to take to make them more fit for purpose.

Is the Al Solubility Limit in SiC Temperature Dependent or not?

The so-called VLS (Vapour-Liquid-Solid) mechanism in an Al-Si melt has recently demonstrated the capability to grow at low temperature single crystalline 4H-SiC layers, with a high Al content. Using the newly developed VLS technique, we have deposited several 4H-SiC layers and determined the incorporated Al level by SIMS (Secondary Ion Mass Spectroscopy). Depending on the sample, we have found that the SIMS doping level ranges from 5x1019 to 1x1021 at.cm-3. This last value is the highest one reported so far for in-situ doped SiC:Al. From TEM (Transmission Electron Microscopy) analyses we show that the layers are single crystals, with a high density of defects located only at the lower interface and no foreign phase inclusion. These results compare well with the ones obtained in previous works using alternative doping techniques, like ion implantation, chemical vapour deposition or sublimation. It thus suggests that Al solubility limit in SiC is rather temperature independent.

Quasistationary Model of Electromagnetic Fields for a Piecewise-Homogeneous Body

We consider a two- or three-dimensional body of arbitrary shape containing foreign inclusions. These inclusions are in perfect electromagnetic contact with the matrix. A boundary condition of the third kind is imposed on the surface of the body. We propose a method of combined application of the fundamental solution of the nonstationary of heat-conduction equation, near-boundary and contact elements, and a step-by-step time scheme of common initial condition for the construction of integral transformations of the components of the vectors of electromagnetic-field intensity at an arbitrary point of space and time. In the case of perfect electromagnetic contact between the zones, the application of contact elements on the interface of the media (instead of boundary or near-boundary elements) enables one to automatically satisfy the first condition of contact (the equality for the components of the vector of electric-field intensity). As a result, the number of unknown fictitious current sources decreases as compared with the case of application of traditional indirect methods of boundary and near-boundary elements.

Probing the effect of temperature on the incorporation of Al species in a SiC matrix

The so-called VLS (Vapour-Liquid-Solid) mechanism in an Al-Si melt has recently demonstrated the capability to grow at low temperature single crystalline 4H-SiC layers, with a high Al content. Using the newly developed VLS technique, we have deposited several 4H-SiC layers and determined the incorporated Al level by SIMS (Secondary Ion Mass Spectroscopy). Depending on the sample, we have found that the SIMS doping level ranges from 5 × 1019 to 1 × 1021 at.cm–3. This is the highest value reported so far for in-situ doped SiC:Al. From TEM (Transmission Electron Microscopy) analyses we show that the layers are single crystals, with a high density of defects at the lower interface but no foreign phase inclusion. These results compare well with the ones obtained in previous works using alternative doping techniques, like ion implantation, chemical vapour deposition or sublimation. It thus suggests that Al solubility limit in SiC is rather temperature independent. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Inertial phase separation in rotating self-gravitating media

The centrifugal separation of foreign inclusions (particles) in a rotating spherical volume of a self-gravitating medium is considered in the hydrodynamic approximation. Using the full Lagrangian approach, the particle trajectories and radial concentration profiles are studied for a rigid-body velocity distribution in the carrier phase. The regimes of continuum and free-molecular flow around the particles are considered. The cases of a “heavy” (with density greater than that of the carrier phase and traveling toward the center) and a “light-weight” (traveling toward the periphery) admixture are investigated. Analytical and numerical solutions corresponding to steady-state spherically symmetric boundary conditions for the dispersed phase are found. It is shown that the presence of rotation may result in a significant angular anisotropy of the radial particle concentration distributions and, in particular, in the formation of ring-shaped accumulation zones of “heavy” inclusions in the equatorial plane. The solutions obtained can be used to explain the mechanisms of onset of density nonuniformities in planet cores, the formation of planetary systems from gas-particle clouds, and the behavior of aerosol particles in atmospheric vortices.

Abscess formation after lip augmentation with silicone: Case report

This paper describes the development of an abscess after injection of an alloplastic preparation (silicone) for enhancement of the lower lip. The 56-year-old woman presented with a painful swelling of her lower lip which was incised. Pus drained from the incision. A biopsy was taken. Histology revealed homogeneous foreign body inclusions (silicone) with fibrosis, chronic inflammation and multinuclear giant cells. Healing was uneventful with little deformation of the lower lip. Since the number of persons seeking aesthetic lip augmentation is increasing, oral surgeons and dentists should be familiar with adverse effects to filling agents.

Using infrared thermography to analyze substrate and adhesive effects in bonded structures

This study was focused on the application of infrared thermography for assessment of technological procedures used to improve adhesion in bonded structures. Infrared thermography is a remote imaging technique which can be fruitfully exploited either for mapping surface temperature in temperature-dependent manufacturing processes, or for nondestructive evaluation of end products. Basically, for nondestructive evaluation two different approaches are possible: traditional pulse thermography (PT) and lock-in thermography (LT) and the use of both techniques is discussed. Several specimens were fabricated to simulate different bonded structures that are used mainly in the aerospace industry. Such bonded structures included: adhesively-bonded aluminum joints with or without surface treatment before bonding, glass-reinforced epoxy composites and carbon-reinforced epoxy composites with or without plasma treatment before bonding. Pulse and lock-in thermographies are both capable of visualizing inhomogeneities in bulk materials, as well as disbonding, delamination, flaws and foreign inclusions in bonded structures. The results show that lock-in thermography is also capable of evaluating the effect of adhesive thickness and the effects induced in bonded structures by substrate surface treatments.

Application of lock-in thermography in nondestructive evaluation of adhesively-bonded aluminum joints

A major problem in industrial applications of structural adhesives is the quality assurance of manufactured joints. At present, for lack of a suitable nondestructive technique, production standards for adhesively-bonded aluminum joints are established on the basis of destructive tests and statistical inference. An experimental study was carried out to assess if lock-in thermography (LT) could be used as a tool for nondestructive evaluation of adhesively-bonded aluminum joints. Several samples were fabricated by varying the governing parameters such as nature of aluminum alloy, substrate thickness, surface treatment, adhesive type and bondline thickness. The effects of surface treatments on the loading capability of lap joints were evaluated through both destructive tensile tests and nondestructive evaluation with infrared LT. Tensile tests showed that the joint performance was not affected by the nature of the aluminum alloy but by the substrate thickness, the adhesive type and the bondline thickness. LT was capable of detecting imperfections such as scratches on substrates and foreign inclusions in the adhesive layer.

Foreign body inclusion cyst secondary to petroleum following rhinoplasty and sinus surgery

Otolaryngology–Head and Neck SurgeryVolume 129, Issue 2 p. P260-P261 Scientific Posters P150: Foreign Body Inclusion Cyst Secondary to Petroleum following Rhinoplasty and Sinus Surgery Benjamin A Bassichis presenter MD, Benjamin A Bassichis presenter MD Chicago, ILSearch for more papers by this authorJ Regan Thomas MD, J Regan Thomas MD Chicago, ILSearch for more papers by this author Benjamin A Bassichis presenter MD, Benjamin A Bassichis presenter MD Chicago, ILSearch for more papers by this authorJ Regan Thomas MD, J Regan Thomas MD Chicago, ILSearch for more papers by this author First published: 17 May 2016 https://doi.org/10.1016/S0194-59980301185-9Read the full textAboutPDF ToolsExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume129, Issue2August 2003Pages P260-P261 RelatedInformation

Quality requirements and control of high purity niobium for superconducting RF cavities

Niobium is a mainly used material for the fabrication of superconducting accelerating RF cavities. The proposed e +e − linear collider TESLA demands about 500 tons of niobium. High purity Nb should reach the TESLA specification. The required high thermal conductivity can be additionally improved by the post-purification. The quality control includes the residual resistivity ratio measurement, microstructure analysis, analysis of interstitial and metallic impurities, hardness measurement, tensile test, examination of the surface roughness and search for clusters. An eddy current scanning system with rotating table is applied for diagnostic of cracks and foreign material inclusions in niobium sheets. 100% of sheets are eddy current tested. Synchrotron fluorescence analysis and neutron activation analysis used for supplemental non-destructive identification and investigation of detected defects. More than 1000 niobium sheets for TESLA test facility were examined. A SQUID based scanning system has potentially higher sensitivity as a conventional pick up coil. First prototype of SQUID apparatus demonstrates sensitivity sufficient to detect inclusions as small as 0.1 mm in diameter.