As radiografias intraorais ilustram bem os estágios de reabsorção periodontal nas regiões interproximais. Entretanto, a sobreposição de estruturas dificulta avaliação da perda óssea nas corticais vestibular e lingual. A tomografia computadorizada por feixe cônico (TCFC) é de elevada importância em várias especialidades odontológicas, tais como implantodontia, avaliação de lesões ósseas, estudo da articulação têmporo-mandibular e cirurgia buco-maxilo-facial. A TCFC também tem tido crescente indicação em outras áreas, como a periodontia e endodontia. O objetivo no presente estudo foi a) estabelecer o protocolo de aquisição mais adequado para a detecção de lesões incipientes de furca simuladas quimicamente; e b) avaliar a reprodutibilidade, sensibilidade e especificidade da TCFC, para a finalidade previamente citada. No presente estudo, foram utilizadas 15 mandíbulas suínas maceradas, que apresentavam o segundo molar íntegro e as corticais adjacentes preservadas As simulações de lesões em região de furca foram feitas com aplicação de ácido perclórico a 70%, em até quatro sítios possíveis em cada mandíbula (vestibular do lado direito, lingual do lado direito, vestibular do lado esquerdo, lingual do lado esquerdo) por um examinador participante que não avaliou as imagens. Nos 60 sitios possíveis, foram escolhidos aleatoriamente 20 para as simulações das lesões. Posteriormente, as mandíbulas foram submetidas à TCFC (i-CAT Next Generation) em dois. protocolos de aquição: voxel 0,2 mm e 0,25 mm, ambos com FOV de 6 cm de altura por 16 cm de diâmetro e com 26,9 segundos de tempo. Dois observadores (radiologistas previamente calibrados) avaliaram os exames duas vezes, em ordem aleatória, sob iluminação controlada. Os observadores foram orientados a direcionar a avaliação das regiões dos segundos molares, e questionados se havia lesão ou não nos sítios avaliados. A interpretação das imagens foi realizada em uma estação de trabalho independente localizada no Laboratório de Imagem em Terceira Dimensão da Faculdade de Odontologia da Universidade de São Paulo, utilizando o software Xoran (Xoran Technologies). A sensibilidade, especificidade e reprodutibilidade da TCFC foram avaliadas nos dois protocolos. A TCFC apresentou especificidade alta, sensibilidade baixa e reprodutibilidade moderada na detecção de lesões incipientes de furca. A influência do tamanho do voxel não foi estatisticamente significativa na detecção destas lesões. / Intraoral radiographs illustrate the stages of resorption in periodontal interproximal regions. However, overlapping structures hinders evaluation of bone loss in the buccal and lingual cortical plates. The cone beam computed tomography (CBCT) is of high importance in various dental specialties such as implantology, evaluation of bone lesions, the study of temporomandibular joint and maxillo-facial surgery. The CBCT has also been increasing indications in other areas, such as periodontics and endodontics. The aim of this study was to establish a) the acquisition protocol most suitable for the detection of incipient furcation invasion chemically simulated and b) assess the reproducibility, sensitivity and specificity of CBCT for the purpose previously mentioned. In this study, 15 pigs macerated mandibles were used, which showed the second molar and the adjacent cortical integrity preserved. Simulated lesions in the furcation area were made with application of 70% perchloric acid, up to four possible sites in each jaw (the right buccal, the right lingual, the left buccal, and left lingual side) by an examiner participant who did not evaluate the images. In the 60 possible sites, 20 were randomly chosen for the simulated lesions. Subsequently, the mandibles underwent cone beam computed tomography (Next Generation i-CAT) in two acquisition protocols: at 0.2 mm and 0.25 mm voxel, both with FOV of 6 cm height by 16 cm in diameter and 26.9 seconds of time. Two observers (calibrated radiologists) evaluated the examinations twice, in random order under controlled lighting. Observers were instructed to direct the evaluation to the regions of the second molars, and they were asked if there were or not injuries on those avaluated sites. Image interpretation was performed on an independent workstation located at the Third Dimension Laboratory of Image in the School of Dentistry, University of São Paulo, using the software Xoran (Xoran Technologies). The sensitivity, specificity and reproducibility of CBCT were assessed in both trials. The CBCT showed high specificity, low sensitivity and moderate reproducibility in the detection of incipient lesions, furcation. The influence of voxel size was not statistically significant in detecting these lesions.

Electron beam freeform fabrication (EBF3) is a rapid metal deposition process that works efficiently with the wieldable alloy Inconel 718 (IN 718). EBF3 is a developing additive manufacturing (AM) process that can manufacture IN 718 parts directly from computer aided design (CAD) data. EBF3 can produce parts significantly faster and more energy efficient than competing IN 718 AM technologies. The EBF3 process utilizes metal wire feedstock which is induced into a molten pool using a focused electron beam in a vacuum environment. This allows parts to be built layer by layer, creating intricate shapes that can be produced cheaper and faster than traditionally manufactured IN 718 parts. Furthermore, it allows traditionally manufactured parts to be modified as additional form is added to them using EBF3. Multiple industries rely on IN 718 parts and can utilize this technology including aerospace engineering, oil refinery, nuclear power generation, and food processing.A main drawback of EBF3 is the lack of knowledge of the effect different EBF3 build techniques will have on the properties of the deposited materials. Most of the reliable data on the mechanical properties relate to a linear build-up strategy and focus on the mechanical properties in the deposition direction (DD). There is no data related to other build-up techniques such as rotation build-up or transitional builds from forged material to EBF3 material. Reliable data on the behavior and microstructure of EBF3 material in a direction other than the DD is also difficult to find. Previous studies showed build-up height influenced mechanical properties but its role is not fully understood yet. This paper presents the mechanical properties and microstructure of an IN 718 plate built using a EBF3 rotational build-up strategy through utilizing a forged plug in the center. The tensile properties of samples at the transition from forged to EBF3 material showed higher ductility and reduced strength than pure EBF3 material. This is likely due the influence of the forge material in one half of the specimen. Samples taken at approximately 15 degree increments from 0 to 90 degrees rotation to the DD in the additive portion of the plate were subjected to tensile testing. Along the build height, or the transverse direction (TD), the lowest strength was demonstrated and the TD aligned strongly to a <001> texture. Samples 45 degrees to the DD showed the greatest strength due to their preference for aligning to a <111> texture. Samples low on the build height demonstrated a higher strength than those on the top and displayed grain structures along the TD which were long, linear, and narrow across multiple deposition layers.

We have fabricated nanofuses from thin-film, arc-evaporation carbon for use in permanent data storage. Thin film carbon fuses have fewer fabrication barriers and retain the required resistivity and structural stability to work as a data storage medium. Carbon thin films were characterized for their electrical, microstructural, and chemical bonding properties. Annealing the thin-film carbon in an argon environment at 400°C reduced the resistivity from about 4*10-2 Ω cm as deposited down to about 5*10-4 Ω cm, allowing a lower blowing voltage. Nanofuses with widths ranging from 200 nm down to 60 nm were fabricated and tested. They blow with voltages between 2 V and 5.5 V, and the nanofuses remain stable in both a "1" and a "0" state under a constantly applied read voltage of 1 volt for over 90 hours, corresponding to a cumulative time of >1012 reads.

Radiation polymerization is a rapid, sustainable process, requiring no environmentally damaging solvents and less energy than thermal polymerization methods. This process is used extensively each year to produce millions of tons of films, coatings, inks, and adhesives. In this work, kinetic- and property-control strategies were developed for three underdeveloped areas of radiation polymerization: free-radical electron beam (EB) polymerization, free-radical/cationic hybrid photopolymerization, and cationic shadow cure. Raman spectroscopy, an analytical technique for studying photopolymerization kinetics, was established as a method of determining the conversion of EB-initiated polymer films. This technique, in conjunction with dynamic mechanical analysis (DMA), was used to investigate the impact of chemical structure on the magnitude of EB dose rate effects (DREs). A strong correlation was determined between the DRE magnitude and monomer size, which may be attributed to chain transfer opportunities. A preliminary predictive relationship was developed to estimate the magnitude of the DRE using the property shift caused by changes in dose, enabling scale-up of process variables for polymers prone to dose rate effects. In addition, a protocol was developed to produce films with equivalent energy deposition for both EB and photopolymerizations, allowing the effect of the initiating radiation to be studied. Distinct kinetic and physical property differences were shown in the resulting EB- and photo-initiated films, despite equivalent initiation energies and energy rates. Monomer chemistry was determined to be an important factor in the magnitude of these differences. In order to control the phase separation that can occur in free-radical/cationic hybrid systems, the cationic AM mechanism was promoted through a hydroxyl group located on the (meth)acrylate, covalently bonding the (meth)acrylate and epoxide networks. The impact of the AM mechanism on the reaction kinetics and physical properties was studied using real-time Raman spectroscopy and DMA to compare a hydroxyl-containing acrylate and methacrylate to non-hydroxyl-containing controls. The promotion of the AM mechanism improved epoxide conversion and network homogeneity. The affect on the (meth)acrylate kinetics correlated to the propagation rate of the neat (meth)acrylate. It was also demonstrated that the glass transition temperature of the hybrid system could be controlled by varying the ratio of (meth)acrylate to epoxide. Cationic shadow cure, which offers a means of circumventing the light penetration limitations in photopolymerization, was modeled using a central composite design. This model was shown to be predictive of both shadow cure length and gel fraction while varying effective irradiance, exposure time, exposure area, and sample depth. Moreover, the model helped ascertain the impact of each variable and its interactions: shadow cure length was most influenced by sample depth, but the gel fraction was reliant on the other three variables. Active center mobility was also qualitatively tracked, and it was established that the section of solid polymer formed during illumination was restricting the movement of the active centers, preventing complete cure. Through this discovery, a new method of shadow cure was developed, termed transferable shadow cure (TSC). This new method separates the initiation and propagation mechanisms, and, as the name suggests, allows for the active-center-containing monomer to be transferred to areas unreachable by light before solidifying. Conversion of the TSC, as determined via Raman spectroscopy, was also modeled using a central composite design. The model predicts TSC conversion is equally dependent on effective irradiance, sample depth, and exposure time, but independent of exposure area. Through the development of control strategies in these three areas, this work provides a better fundamental understanding of radiation polymerization, as well as guidelines that aid in product design and technology expansion.

Introduction: The use of CBCT to visualize the relationship between the inferior alveolar canal and the mandibular third molar roots continues to grow as it is becoming the standard of care. It becomes important to understand the impact that luminance, one of the factors that affects the viewing conditions of digital images, has on appropriately assessing the third molar-canal relationship. To date, no study has assessed the impact of luminance on visualizing anatomic structures on CBCT. The aim of this study is to determine if there is a difference in the ability to appropriately assess the root development and the third molar-canal relationship on a medical grade monitor with four different luminance settings on CBCT. Materials and methods: 285 scans were randomized and evaluated by three calibrated and masked evaluators. The evaluations were completed on a Barco MDNC-3321 Nio Color 3MP monitor (Kortrijk, Belgium) monitor at four different luminance settings; 200 cd/m2, 300 cd/m2, 400 cd/m2, and 500 cd/m2. The gold standard was established by two board-certified oral and maxillofacial radiologists. All evaluations were performed in a controlled subdued environment lighting of less than 15 lux. There was a washout period of at least one week between each of the four evaluations by an observer. Results: The accuracy of two of the three evaluators was substantial to almost perfect independent of luminance. None of these assessments showed any statistical significance (P = 0.05). The accuracy of one evaluator was moderate to almost perfect for all evaluations with one assessment of one canal showing statistical significance (P = 0.05). Conclusion: There is no difference in the ability to appropriately assess the third molar canal relationship or the root development of third molars on a medical grade monitor at luminance settings between the range of 200 cd/m2 and 500 cd/m2 when viewed in a dimly lit room.

No description available.

Traditional antennas have a lot of limitations as their performance is usually fixed by their initial geometry. On the other hand, modern communication systems are getting way to complicated compared to their earlier counterparts. This necessitates some special types of smart or reconfigurable antennas, which can dynamically adapt to the requirements of the communication systems more effectively. Using conventional single functional antennas is therefore not an efficient approach in these sort of communication systems. Considering all these factors, in this thesis, a beam steerable reconfigurable antenna system is presented that can yield the radiation patterns of multiple antennas with a single structure, necessary for 5G communication. This antenna system occupies comparatively much smaller space and can provide highly directive gain at different directions. It is expected that- in near future, further improvements of this type of antenna system can be performed to pave the way for some additional necessary functions required in modern communication systems.

Shape memory alloys (SMAs) are a unique class of smart materials exhibiting extraordinary properties with a wide range of applications in engineering, biomedical, and aerospace technologies. In this study, an advanced, efficient, low-cost, and highly scalable laser-assisted imprinting method with low environmental impact to create thermally controllable surface patterns is reported. Two different imprinting methods were carried out mainly on Ni50Ti50 (at. %) SMAs by using a nanosecond pulsed Nd:YAG laser operating at 1064 nm wavelength and 10 Hz frequency. First, laser pulses at selected fluences were directly focused on the NiTi surface, which generated pressure pulses of up to a few gigapascal (GPa), and thus created micro-indents. Second, a suitable transparent overlay serving as a confining medium, a sacrificial layer, and a mesh grid was placed on the NiTi sample, whereafter the laser was focused through the confinement medium, ablating the sacrificial layer to create plasma and pressure, and thus pushing and transferring the grid pattern onto the sample. Scanning electron microscope (SEM) and laser profiler images show that surface patterns with tailorable sizes and high fidelity could be obtained. The depth of the patterns was shown to increase and later level off with the increase in laser power and irradiation time. Upon heating, the depth profile of the imprinted SMA surfaces changed where the maximum depth recovery ratio of 30 % was observed. Recovery ratio decreased and saturated at about 15 % when the number of pulses were increased. A numerical simulation of the laser irradiation process was performed showing that considerably high pressure and temperature could be generated depending on the laser fluence. The stress wave closely followed the rise time of the laser pulse to its peak value and followed by the rapid attenuation and dispersion of the stress through the sample.

Active vibration control is a widely implemented method for the helicopter vibration control. Due to the significant progress in microelectronics, this technique outperforms the traditional passive control technique due to weight penalty and lack of adaptability for the changing flight conditions. In this thesis, an optimal controller is designed to attenuate the rotor blade vibration. The mathematical model of the triply coupled vibration of the rotating cantilever beam is used to develop the state-space model of an isolated rotor blade. The required natural frequencies are determined by the modified Galerkin method and only the principal aerodynamic forces acting on the structure are considered to obtain the elements of the input matrix. A linear quadratic regulator is designed to achieve the vibration reduction at the optimum level and the controller is tuned for the hovering and forward flight with different advance ratios.

The research provided in this report examines the behavior of fiber reinforced polymer (FRP) reinforcing bars, embedded in normal weight concrete (NWC) hinged beam-end specimens, tested in accordance with two laboratory conditions. Reinforcing bars of different diameter, material configuration, and finished surface preparation were tested for bond strength parameters determined in accordance with ACI Committee Report 440.3. Bond strength parameters under the first condition were tested within NWC beams at a relatively low compressive strength and minimum embedment length; the second condition allowed testing within NWC beams at twice the design compressive strength of the first condition and moderate embedment length. The load-slip curves developed show the differences that occur under the specified conditions. The influence of embedment length, bar diameter, material configuration, finished surface preparation, and concrete compressive strength are reported in detail. Furthermore, the testing arrangement selected for this study was proven to have a significant influence on bond behavior when compared to conventional pullout test methods.