Semicircular Defects Research Articles

Multiple intraductal papillary neoplasms of bile duct diagnosed based on endoscopic ultrasonography and peroral cholangioscopy findings

A man in his 30s was referred to our department for evaluation of bile duct stricture and removal of an intrahepatic bile duct stone. Five years before his presentation, he underwent left hepatectomy for a giant hepatic hemangioma. There were no abnormalities in blood biochemical tests. Magnetic resonance cholangiopancreatography showed one 5 mm oval defect in region B6 and two 8 mm semicircular defects in the hilar bile duct. Endoscopic ultrasound revealed a 3.5 mm hypoechoic focal raised lesion in the hilar bile duct. Oral cholangioscopy revealed his two lesions in the hilar bile duct as white papillary elevations with mucus production. The pathological diagnosis of intraductal papillary neoplasm was determined (low-grade dysplasia, type 1, gastric type). After 1 and a half years, no expansion of the bile duct lesion was observed. Initially, it was thought to be a benign stenosis after liver resection, but based on the results of endoscopic ultrasound, we suspected a tumorous lesion, and we were able to make an accurate diagnosis, including histological type, using transoral cholangioscopy.

Skyrmionium dynamics on a racetrack in the presence of a magnetic defect

Exotic topological textures known as skyrmioniums can stabilize in different types of ferromagnetic nanostructures. They possess a topological charge of Q=0 and can move in straight lines unaffected by the skyrmion Hall effect. In this work, using micromagnetic simulations, we study the behavior of a skyrmionium when a polarized spin current transports it along a racetrack in the presence of a semicircular magnetic defect with different Dzyaloshinskii–Moriya interaction values. As a first step, we obtained the perpendicular uniaxial anisotropy (Kz) and the Dzyaloshinskii–Moriya constants (Dint) for which it is possible to form a skyrmionium in the racetrack. Our results show that the higher the Kz value, the higher the Dint values necessary to stabilize the skyrmionium. Furthermore, interaction energies between the skyrmionium and the semicircular defect are presented. The results show that the interaction energy can be attractive or repulsive, depending on the Dzyaloshinskii–Moriya defect interaction constant (Dintdef). Finally, we conclude that using these types of defects and a spin-polarized current, the motion of the skyrmionium can be either modified in a specific way or even blocked.

Defect Recognition Method for Magnetic Leakage Detection in Oil and Gas Steel Pipes Based on Improved Neural Networks

The aging infrastructure of petroleum and natural gas pipelines poses a threat to national economies, necessitating precise defect detection for safety and efficiency. To enhance the accuracy of predicting pipeline defect sizes, this study introduces a magnetic leakage detection system, employing Backpropagation (BP) neural networks optimized with genetic algorithms. Traditional BP networks face challenges, including parameter determination and slow convergence, addressed through genetic algorithms' global search capabilities. Simulated data are generated using ANSYS software by using models of semi-circular defects in steel pipes, producing magnetic leakage signals of varying intensities. MATLAB was used to construct both standard BP and genetically optimized BP neural networks. Results show that the latter significantly reduces computational errors, demonstrating improved accuracy in defect dimension prediction. The approach contributes to overcoming non-uniqueness in the recognition process and the complex nonlinear relationship between magnetic signals and defect size parameters. The study offers a guided approach for selecting BP neural network parameters, enhancing practicality. Simulations validate the method's effectiveness, indicating low workload and high reliability. This research provides a meaningful advancement in the detection of defects in long-distance pipelines, impacting the safety and efficiency of petroleum and natural gas transportation.

Theoretical modeling and dynamic analysis of designable grillages for repairing material surface defect

Designing structural grillages is an innovative solution to repair material surface defects. The grillages have advantages as lightweight and directionally enhanced, but their stability and stress concentration under dynamic loads may pose significant risks. Three analytical models of grillages above a semicircular defect are constructed. The analytical solution of the frequency-domain wave field around the semicircular defect under SH wave incidence is solved. The complex variable function method is introduced to simplify the wave field expression. The accuracy is verified by comparing it with classic examples. Applying the Modified Time-Frequency Transform to obtain the time-domain wave field. Based on the Multipoint Transient Input Method (MTIM), the transient surface displacement response of the grillage above the defect is derived, mainly discussing the superposition behavior of input waves in the grillage. MTIM is based on the analytical solution of local time-domain wave field and takes the time histories of the surface characteristic points as the wave input. It has been validated as an effective method for studying the dynamic response of structures. The numerical results show that grillage form, incident angle, and wave velocity ratio are important factors affecting the structural responses of grillage above the defect. This research aims to reveal the propagation characteristics of waves in grillages in filling material defects, providing theoretical guidance for the design and application of grillages in this field.

Bilobed Flaps: An Esthetic Method of Reconstructing Circular Defects.

Local flap reconstruction is an important skill used to excise and repair many cutaneous defects in various anatomical regions of body. In this article, the authors have described the bilobed flap reconstruction technique useful in the resection of various circular and semicircular defects, especially over nose tip and lateral wall of the nose. The authors have highlighted various indications, procedural techniques, and complications related to the surgery which will help in better esthetic outcome.

Anatomical variation of the sacroiliac joints: an MRI study with synthetic CT images

BackgroundSynthetic computed tomography (sCT) images are magnetic resonance imaging (MRI)-based images, generated using artificial intelligence. This study aimed to determine the prevalence of anatomical variants of sacroiliac joints (SIJ) on sCT images and the correlation with age, sex and body weight.MethodsMRI of the SIJ including sCT images of 215 patients clinically suspected for sacroiliitis were retrospectively analyzed. The presence of anatomical variants of the SIJ was assessed. Age, sex and body mass index at the time of the MRI were recorded.ResultsSIJ variants were found in 82.8% (356/430) of the evaluated joints. The most frequent variants were iliosacral complex (27.7%), bipartite iliac bony plate (27.2%) and crescent iliac bony plate (27%). One new variant was identified, consisting of an accessory facet of the SIJ on the superior side. Overall, SIJ variants were slightly more frequent in women (85.8% vs. 77.8%), but iliosacral complex was significantly more frequent in men. Isolated synostosis was more prevalent with advancing age, in contrast to semicircular defect and unfused ossification center. The occurrence of iliosacral complex was associated with higher BMI, while crescent iliac bony plate occurred more in patients with lower BMI.ConclusionOver 80% of patients in this study, who were all suspected of sacroiliitis, had at least one SIJ variant. These variants may actually represent subtypes of the normal SIJ. sCT enables detection of very small or subtle findings including SIJ variants.

Sacroiliac Joint Fusion—A Shift Toward Variant Anatomy and Clinical Implications

To investigate impact of patient factors and sacroiliac joint (SIJ) anatomical structure on SIJ fusion outcomes. This single-center, retrospective, observational study evaluated patients diagnosed with SIJ dysfunction refractory to conservative measures who had available preoperative imaging of the sacrum and underwent SIJ fusion surgery. The impact of patient sociodemographics on pain improvement was assessed by Mann-Whitney U test. Differences in patient sociodemographics and outcome information between anatomical subtypes were assessed with χ2 and Kruskal-Wallis tests. χ2 test was used to compare joint anatomy distribution between studies analyzing SIJ variations. We included 77 total joints that underwent instrumentation. There were significant differences between the anatomical subtypes with female sex having significantly higher rates of non-normal joint anatomy. Younger age was significantly more common in bipartite/dysmorphic anatomy (53.9 years) than normal anatomy (70 years) (P < 0.05). There was a trend toward better outcomes in bipartite/dysmorphic and accessory variants, while semicircular defect and crescent variants trended toward worse outcomes. Nonnormal anatomy was significantly more frequent in our population than previous reports on nonpathological SIJ. A pathological SIJ has a significantly higher prevalence of variant joint anatomy. There appears to be a trend toward differences in surgical outcomes based on SIJ anatomy. Future research with larger sample sizes is necessary to confirm these differences.

Planned complex suicide combining pistol head shot and train suicide and Virtopsy examination

• What resolution is necessary for forensic triage post-mortem CT • How to search for and identify gunshot injury to the head in apparent case of train suicide • Comparison of CT and macroscopy of bone fragments This case report focuses on the findings in what appeared to be a planned complex pistol head shot and train suicide. The post mortem computed tomography (PMCT) scan in this instance yielded two interesting skull fragments among the many fragments of a highly fragmented body and head. These two fragments, based on initial resolution, appeared to show findings consistent with a firearm shot to the head. Upon reconstruction of higher resolution data, the necessary discrimination of non-gunshot related semi-circular fragment rims and firearm-related beveling matched the macroscopic aspect of the skull fragments. As a first lesson to be learned, a thorough examination of PMCT data in relatively high degrees of fragmentation may have to inspect all bone edges also for relatively subtle changes, possibly indicative of sharp force trauma or gunshot trauma. To that end, individual bone fragments should be placed on the scanner table carefully and with proper spacing, to expose their edges. Only this allows to capture data that avoids edge overlaps or edge collisions and that allows for optimal checking of the edges of all bone fragments for possible semicircular defects in the PMCT data. A second technical lesson to be learned is that particularly in instances of high fragmentation of at least parts of a body, resolution may have to be at least as good as maximally achievable. To that end, availability of the raw data to reconstruct images with maximal image quality rather than using a trade-off between lesser cost and lesser yield may be a key issue. A third lesson to be learned is that findings in relatively highly fragmented bodies as consequence of an apparent form of injury - fire/thermal, fall from great height, collision with a train - for other forms of trauma - sharp force trauma, firearm injury - may have to interpreted with caution, particularly with regard to what can be ruled out.

Enhancing esophageal repair with bioactive bilayer mesh containing FGF

We aimed to prepare a bioactive and biodegradable bilayer mesh formed by fibroblast growth factor (FGF) loaded gelatin film layer, and poly ε-caprolactone (PCL) film layer, and to investigate its treatment efficacy on esophageal anastomosis. It is envisaged that the bioactive mesh in in vivo model would improve tissue healing in rats. The full thickness semicircular defects of 0.5 × 0.5 cm2 were created in anterior walls of abdominal esophagus. The control group had abdominal esophagus isolated with distal esophageal blunt dissection, and sham group had primary anastomosis. In the test groups, the defects were covered with bilayer polymeric meshes containing FGF (5 μg/2 cm2), or not. All rats were sacrificed for histopathology investigation after 7 or 28 days of operation. The groups are coded as FGF(−)-7th day, FGF(+)-7th day, and FGF(+)-28th day, based on their content and operation day. Highest burst pressures were obtained for FGF(+)-7th day, and FGF(+)-28th day groups (p < 0.005) and decreased inflammation grades were observed. Submucosal and muscular collagen deposition scores were markedly increased in these groups compared to sham and FGF(−)-7th day groups having no FGF (p = 0.002, p = 0.001, respectively). It was proved that FGF loaded bioactive bilayer mesh provided effective repair, reinforcement and tissue healing of esophageal defects.

Anatomical variations of the sacro-iliac joint: a computed tomography study

To identify, describe, and compare the prevalence of sacroiliac joint anatomical variants. A retrospective study was performed on computed tomography scans. Joint space was measured, and variants were classified as accessory joint, ileosacral complex, bipartite bony plate, semicircular defect, iliac bony plate, and ossification centers. 400 scans were analyzed. Mean age was 49years, 180 men (45%), and 220 women (55%). 209 (52.2%) patients presented an anatomical variant with higher prevalence in women (65.4% vs 36.2%), and those older than 40years of age (60% vs 40%). Mean joint space was similar bilaterally (right 2.41 ± 0.65mm vs. left 2.37 ± 0.65mm). Prevalence was: 19.8% accessory joint, 6.5% ileosacral complex, 12.3% bipartite bony plate, 8% semicircular defect, 5% iliac bony plate, and 0.8% for ossification centers. Prevalence of anatomical variants of the SIJ is higher in the Hispanic population, women, and those older than 40years.

Improving the fatigue limit and rendering a defect harmless by laser peening for a high strength steel welded joint

The effects of laser peening (LP) on fatigue limit improvement and acceptable defect size of a high strength steel HT780 (JIS-SHY685) welded joint were investigated. Fatigue tests were performed, following the optimization of the LP conditions. The fatigue limit of the welded specimen without the defect increased by 45% via LP. The specimen containing 0.2 mm deep semicircular defect at the weld toe reached almost the same level of fatigue limit as that of the defect-free, LP-treated specimen. Therefore, a semicircular defect of less than 0.2 mm deep could be rendered harmless by LP. From the results, the fatigue strength and the reliability of HSS-welded joints can be significantly improved by LP. The dominant factor that contributed to fatigue limit improvement was the introduction of compressive residual stress by LP.

Micro-mechanical investigation of fatigue behavior of Al alloys containing surface/superficial defects

A crystal plasticity finite element (CPFE) simulation framework has been proposed in this study for the prediction of combined detrimental effect of mean stress and defects on the fatigue behavior of aluminum alloy. Experimental data for mean-stress effect on fatigue life and crack growth behavior was obtained on metal inter gas (MIG) welded joints of Al-5083/Al-5.8%Mg alloy plates and has been detailed in authors’ previous work, referred later. The present study focuses on its prediction using computational framework only. A 2D representative model for material’s microstructure was used for the simulations, generated using an anisotropic tessellation algorithm using the EBSD measurements data. A total of 10 different microstructure models were generated for each loading condition using six-node plane strain type quadratic triangular (CPE6) elements of mesh size 6 μm. Two different types of cases were investigated: one without defect and other with a semi-circular surface defect. The simulated loadings at different stress ranges and stress ratios (R-ratio) were similar to the experimental conditions for the better comparison of the results. Significant heterogeneity in the distribution of R-ratios and the far-field applied R-ratio was observed. When defect was not considered, a clear deviation in the predicted fatigue lives from the experimental data was observed at different R-ratios: the predicted fatigue lives were higher than the experimentally observed fatigue lives. This was probably because of not considering the detrimental effect of defects on fatigue lives. But, when the defects were considered, the predicted results for different R-ratios were consistent with the experimental fatigue lives. The proposed CPFE simulation framework not only predicted well the effect of defects and mean stress on the fatigue lives, but also the scatter induced in them due to the defects.

Frequency of anatomical variation of the sacroiliac joint in asymptomatic young adults and its relationship with sacroiliac joint degeneration.

To evaluate the variations of the sacroiliac joint (SIJ) in asymptomatic young adults and their relationship to SIJ degeneration. A total of 860 SIJs were retrospectively evaluated in 430 abdominal computed tomographies (CT) of abdominal pain cases. The study population consisted of 430 patients (176 female, 254 male) aged 20-45 years with abdominal pain. The anatomical variations of the SIJ were classified as (1) accessory sacroiliac joint, (2) iliosacral complex, (3) bipartite iliac bony plate, (4) semicircular defects, (5) crescent-like iliac bony plate, and (6) ossification center. The CT findings of SIJ degeneration included joint space narrowing, sclerosis, subcortical cysts, vacuum phenomenon, and osteophytes. Chi-square and cross tabulation tests were used for statistical analysis. The iliosacral complex was the most common (bilateral) anatomical variation (7.7%, n = 66). A total of 71 SIJ degenerations were detected in cases with anatomical variations. They were determined in 22 (2.6%) iliosacral complex, 19 (2.2%) bipartite iliac bony plate, 15 (1.7%) accessory sacroiliac joint, 6 (0.7%) semicircular defect, 5 (0.6%) crescent-like iliac bony plate, and 4 (0.5%) ossification center cases. We found that iliosacral complex was the most common SIJ variation in asymptomatic young adults and also that there was significantly more SIJ degeneration among subjects with anatomical variations of the SIJ than those without. SIJ degeneration was most common in subjects with the iliosacral complex variation.

Use of post-mortem computed tomography in disaster victim identification. Updated positional statement of the members of the disaster victim identification working group of the International Society of Forensic Radiology and Imaging; July 2019

This case report focuses on the findings in what appeared to be a planned complex pistol head shot and train suicide. The post mortem computed tomography (PMCT) scan in this instance yielded two interesting skull fragments among the many fragments of a highly fragmented body and head. These two fragments, based on initial resolution, appeared to show findings consistent with a firearm shot to the head. Upon reconstruction of higher resolution data, the necessary discrimination of non-gunshot related semi-circular fragment rims and firearm-related beveling matched the macroscopic aspect of the skull fragments. As a first lesson to be learned, a thorough examination of PMCT data in relatively high degrees of fragmentation may have to inspect all bone edges also for relatively subtle changes, possibly indicative of sharp force trauma or gunshot trauma. To that end, individual bone fragments should be placed on the scanner table carefully and with proper spacing, to expose their edges. Only this allows to capture data that avoids edge overlaps or edge collisions and that allows for optimal checking of the edges of all bone fragments for possible semicircular defects in the PMCT data. A second technical lesson to be learned is that particularly in instances of high fragmentation of at least parts of a body, resolution may have to be at least as good as maximally achievable. To that end, availability of the raw data to reconstruct images with maximal image quality rather than using a trade-off between lesser cost and lesser yield may be a key issue. A third lesson to be learned is that findings in relatively highly fragmented bodies as consequence of an apparent form of injury - fire/thermal, fall from great height, collision with a train - for other forms of trauma - sharp force trauma, firearm injury - may have to interpreted with caution, particularly with regard to what can be ruled out.

Anatomical variations of the sacroiliacal joint

IntroductionThe sacroiliac joint (SIJ) is the union between the spine and the pelvis. It is a diarthroid joint and complex due to having different types of joint classifications. The presence of an accessory articular facet was described for the first time in 1753, considered the first report of a sacroiliac anatomical variant. Since then different anatomists have reported this variant in skeletons and corpses with variations in their incidence. In 1999, the first classification was made using a Greek population reporting 5 other anatomical variants using computed tomography (CT) and correlating this to lumbar pain, reporting a high incidence when anatomical variants were present. Only one other study analyzes the joint using this classification in a Turkish population. There are no reports of other population, much less Latin American. Our aim was to identify the prevalence of SIJ anatomical variants using CT.Materials and methodsA retrospective study was made based on pelvic and/or abdominal CT that allowed the complete visualization of the SIJ. SIJ space was measured, and variants were classified as: Accessory SIJ, ileosacro complex, bipartite bone plate, semicircular defect, iliac bone plate, and ossification center.ResultsFour hundred CT scans were included for analysis. The mean age was 49 years, 180 (45%) were men and 220 (55%) women. More than half (209, 52.2%) of the patients presented an anatomical variant, and were more predominant in women (65.4% vs 36.2%), as well as those older than 40 years of age (60% vs 40%). The mean joint space was similar between sides (right 2.41 ± 0.65mm vs. left 2.37 ± 0.65mm). Incidence was 19.8% accessory SIJ, 6.5% ileosacro complex, 12.3% bipartite bone plate, 8% semicircular defect, 5% iliac bone plate, and 0.8% for ossification center. No statistically significant differences were found comparing the space with the variables of gender, age, or type of variant.ConclusionThe prevalence of anatomical variants of the SIJ is high in the Latin population, higher in women and those older than 40 years. The most prevalent variant was accessory SIJ.Support or Funding InformationNoneThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Effects of Inner Defects on Creep Damage and Crack Initiation for a Brazed Joint

AbstractIn the brazing process, some brazing defects like semicircular or straight type are generated due to incomplete filling. In this paper, the creep damage and creep crack initiation (CCI) time of Hastelloy C276-BNi2 brazed joint with defects are investigated by a ductility exhaustion damage model. The effects of defect dimension and filler metal thickness are also discussed. The results show that the different defects have different creep damage distributions and CCI times. The maximum creep damage is located at the defect frontier due to the larger stress concentration. With the increase of semicircular defect radius and straight defect length, the CCI time decreases. The creep fracture is inclined to generate in semicircular defect for the smaller defect area ratio, while it is easy to generate in straight defect for the bigger defect area ratio. As the filler metal thickness increases, the CCI time increases. For the thicker filler metal, the creep crack is easy to initiate in semicircular defect.

A compact slot antenna with improved bandwidth and gain for wireless applications

A wide-slot antenna is investigated to achieve a bandwidth of about 162%. The ground plane includes a rectangular slot with dual SRR and two semicircular defects in the bottom side of the rectangular slot. A fork like feed-line with two parasitic stubs to increase the bandwidth is used to feed the slot. 37*37*0.8 mm3 is the size of the proposed antenna and the dielectric substrate used is FR4. The measured bandwidth ranges from 1.8-17.5 GHz which is approximately 162%. Significant improvement in gain for the frequency range of 1.8-6.1 GHz is observed. The proposed antenna has radiation patterns that are stable and omnidirectional in both E and H planes in all the six frequency points for entire frequency range. The simulated and measured results are in good agreement.

Репаративные процессы при алло- и ксеноимплантации внеклеточного матрикса кости

В настоящее время потребность в костно-пластическом материале возрастает при проведении реконструктивно - восстановительных операций на костной ткани в травматологии и ортопедии, челюстно-лицевой хирургии, костной онкологии и в других случаях хирургической практики. Среди имплантационных материалов на основе костной ткани лидирующее место занимают импланты ауто- и аллогенного происхождения. Аутогенные импланты - лучшие с биологической точки зрения, но их достойной альтернативой являются материалы из ксенокости в силу своей доступности и биосовместимости. Цель исследования - изучение репаративных процессов в зоне регенерации при алло - и ксеноимплантации материала, полученного из костной ткани, в полуциркулярный дефект диафиза бедренной кости крыс. Материалы готовили по одинаковой технологии. Методика. Биохимические и морфологические исследования проведены на 18 крысах-самцах линии Вистар в возрасте 6-8 месяцев. Животные были распределены на 3 группы. Первая группа (n = 6) - ксеноимплантация, вторая (n = 6) - аллоимплантация, третья контроль (n = 6) - здоровые животные. Изучены биохимические показатели сыворотки крови на 60-е сут. эксперимента: активность общей щелочной фосфатазы и тартратрезистентного изофермента кислой фосфатазы, содержание кальция, фосфата, общего белка, С-реактивного белка, белковых фракций и проведены морфологические исследования. Результаты и обсуждение. Биохимические исследования белковых фракций и С-реактивного белка сыворотки крови свидетельствуют об отсутствии выраженной воспалительной реакции у крыс при алло - и ксеноимплантации внеклеточного матрикса костной ткани в области дефекта метафиза бедренной кости. В обеих опытных группах отмечена активация репаративных процессов. Гистологический анализ выявил остеоинтеграцию как аллогенных, так и ксеногенных фрагментов губчатой кости, имплантированных в область полуциркулярного дефекта бедренной кости крыс. При использовании аллоимплантатов отмечен более высокий темп их биодеградации и органотипическая перестройка оперированного участка кости реципиента. Во всех случаях показано отсутствие реакции отторжения либо инкапсуляции импланта и признаков воспаления в тканях реципиента. Полученные нами данные биохимического и гистологического исследований являются доказательством возможности использования внеклеточного матрикса ксеногенной природы для замещения дефектов костной ткани.The need for bone-plastic material is presently rapidly increasing, particularly for reconstructive and restorative surgeries on bone tissue in traumatology and orthopedics, maxillofacial surgery, bone oncology, and other cases of surgical practice. Among the implantation materials based on bone tissue the leading place is occupied by auto- and allogeneic implants. Autogenic implants are the best from the biological point of view but xenobone materials are their worthy alternative due to their availability and biocompatibility. The aim of this research was to study reparative processes in the regeneration zone during allo- and xenoimplantation of a material obtained from bone tissue into a semicircular defect in the rat femoral diaphysis. The materials were prepared using the same technology. Methods. Biochemical and morphological studies were performed on 18 male Wistar rats aged 6-8 months. The rats were divided into 3 groups. The first group (n = 6), xenoimplantation; the second group (n = 6), alloimplantation, and the third group, healthy control (n = 6). On the 60 day of experiment, biochemical indexes of blood serum were studied, including activities of total alkaline phosphatase (TCA) and tartrate-resistant isoenzyme of acid phosphatase (TrAP), calcium, phosphate, total protein (TP), C-reactive protein, protein fractions, and morphological studies. Results. Measuring serum protein fractions and C-reactive protein showed the absence of a significant inflammatory reaction to allo- and xenoimplantation of extracellular bone matrix into the defect of femoral metaphysis. Activation of reparative process was noted in both experimental groups. Histological analysis found osteointegration of both allogeneic and xenogenic fragments of the spongy bone implanted into the semicircular defect of rat femur. When alloimplants were used a high rate of their biodegradation and organotypic remodeling of the operated recipient’s bone were observed. However, in all cases, there was no evidence of a rejection reaction, encapsulation of the implant or inflammation in tissues of the maternal bed.

Unidirectional light propagation photonic crystal waveguide incorporating modified defects

In this paper, we have proposed a design of an Optical Diode-like in two-dimensional (2D) Photonic Crystal (PC) waveguide. The proposed device consists of 2D square-lattice PC structures, and it is based on two PC waveguides with different symmetric guiding modes, where various configurations of defects, including elliptic or/and semi-circular defects have been incorporated. The proposed one-way light propagation Optical Diode has been designed and optimized by employing in-house 2D Finite Difference Time Domain (FDTD) numerical method. We have reported that the unidirectional light propagation depends strongly on the coupling region between the introduced defects and the adjacent waveguides, and it also depends on the matching and mismatching between the defects and waveguide modes. It has been shown also that owing to its tunable features, the proposed Optical Diode can be potentially applied as a building block in future complex optical integrated circuits.

A ΔJ approach for the evaluation of Fatigue Crack Growth in nozzle corners

This paper deals with the Fatigue Crack Growth evaluation of a crack located at a nozzle corner and submitted to thermal transients. In such situation, it is well known that it is important to consider the effect of plasticity. Thus, the background of an evaluation scheme relying on the ΔJ parameter is presented in the first part of the paper.In the second part, the Fatigue Crack Growth evaluation scheme relying on semi-circular defects is validated through a comparison to reference Finite Element modeling. It is then shown that the assumed semi-circular defect is justified and also that the complete analytical scheme based on a KI compendium and the simplified kth coefficient formulation allows to accurately evaluate the Fatigue Crack Growth Rate of this complex configuration.