Nonlinear Optics and Applications

Nonlinear optics is the result of laser beam interaction with materials and started with the advent of lasers in the early 1960s. The field is growing daily and plays a major role in emerging photonic technology. Nonlinear optics play a major role in many of the optical applications such as optical signal processing, optical computers, ultrafast switches, ultra-short pulsed lasers, sensors, laser amplifiers, and many others. This special review volume on Nonlinear Optics and Applications is intended for those who want to be aware of the most recent technology. This book presents a survey of the recent advances of nonlinear optical applications. Emphasis will be on novel devices and materials, switching technology, optical computing, and important experimental results. Recent developments in topics which are of historical interest to researchers, and in the same time of potential use in the fields of all-optical communication and computing technologies, are also included. Additionally, a few new related topics which might provoke discussion are presented. The book includes chapters on nonlinear optics and applications; the nonlinear Schrodinger and associated equations that model spatio-temporal propagation; the supercontinuum light source; wideband ultrashort pulse fiber laser sources; lattice fabrication as well as their linear and nonlinear light guiding properties; the second-order EO effect (Pockels), the third-order (Kerr) and thermo-optical effects in optical waveguides and their applications in optical communication; and, the effect of magnetic field and its role in nonlinear optics, among other chapters

A case of parasitic leiomyoma with serpentine omental blood vessels: An unusual variant of uterine leiomyoma

AbstractLeiomyoma is considered as the commonest benign tumor of the genital tract. This case represents a multiparous woman who presented with a history of progressive abdominal distension. On examination, a mobile ill-defined centrally located intra-abdominal mass was noticed. At laparotomy a parasitic fibroid attached to the greater omentum was seen. Resection of the mass and partial omentectomy was performed which was reported as leiomyoma by the histological examination. The patient had an uneventful post-operative recovery. She has been followed up for twelve months with no evidence of recurrence or residual disease

Off-design of a CO2-based mixture transcritical cycle for CSP applications: Analysis at part load and variable ambient temperature

This work focuses on the off-design analysis of a simple recuperative transcritical power cycle working with the CO2 + C6F6 mixture as working fluid. The cycle is aircooled and proposed for a state-of-the-art concentrated solar plant with solar salts as heat transfer fluid in a hot region, with a cycle minimum and maximum temperature of 51 degrees C and 550 degrees C at design conditions. The design of each cycle heat exchanger (primary, recuperator and condenser) is carried out in MATLAB with referenced models and the turbine designed in CFD, providing performance maps adopted by the cycle operating in sliding pressure. The off-design of the cycle is developed with a routine simulating the thermodynamic conditions of the cycle at variable ambient temperature and thermal inputs down to 40 % of the nominal value. The results show that the cycle can efficiently run in a wide range of part load conditions and ambient temperatures, from around 0 degrees C to over 40 degrees C, with net electric cycle efficiencies from 45 % to 36 %: according to the control philosophy proposed, the condenser fans are fixed at design speed, while the cycle operates in sliding pressure, when is possible. The results evidence the flexibility and good performances of the proposed system in various operating conditions

Anti-Annexin V Antibodies: Association with Vascular Involvement and Disease Outcome in Patients with Systemic Sclerosis

Background: Systemic Sclerosis (SSc) is characterized by skin thickening, fibrosis and vascular obliteration. The onset and course are heterogeneous. Prominent features include autoimmunity, inflammation and vascular damage. Aim of study: To measure the level of serum Anti-Annexin V antibodies in SSc patients and to study its significance in relation to vascular damage in these patients. Patients and methods: Twenty patients with SSc (12 with diffuse SSc and 8 with the limited form) and 10 healthy age and sex matched volunteers as controls were all subjected to routine laboratory testing and immunological profiling including antinuclear, anti-Scl-70, anticentomere, anticardiolipin antibodies and anti-annexin V antibodies titres. Vascular damage was assessed by clinical examination and assessment of the disease activity score, nailfold capillaroscopy and colour flow Doppler of the renal arteries; Doppler echocardiography was used for assessing pulmonary hypertension. Results: Anti-annexin V antibodies were detected in 75% of patients. Comparisons between anti-annexin V in diffuse and limited subgroups showed no significance; however a statistically significant positive correlation was found between Anti-annexin V titre and the degree of vascular damage in SSc patients. Anti-annexin V increased significantly in patients with severe vascular damage in comparison with those less affected (15.3 ± 6.6 vs. 11.25 ± 3.6, P , 0.05). A significant positive correlation was found between Anti-annexin V titre and both the ACL titre (r = 0.79, P , 0.001) and the resistive index of the main renal artery (r = 0.42, P , 0.05). Conclusion: Anti-annexin V antibodies were significantly present in sera of patients with SSc. Patients with more severe forms of vascular damage had higher titres of these antibodies. Anti-annexin V antibodies are a sensitive predictor of vascular damage in SSc and could serve as a useful parameter in discriminating patients with a higher risk of vascular affection from those without

Design of a 130 MW axial turbine operating with a supercritical carbon dioxide mixture for the SCARABEUS project

Paper ID: ETC2023-133.The application of supercritical carbon dioxide (sCO2) mixtures in power generation cycles has been shown to improve the cycle efficiency for concentrated solar power applications. That could be achieved through mixing CO2 with dopants to raise the critical temperature of the working fluid to allow condensation at ambient temperatures in solar filed locations. This enables converting the supercritical power cycle into a transcritical power cycle with lower compression power and hence higher thermal efficiency. This paper presents the flow-path design of a commercial scale axial turbine operating with an 80-20% mix of CO2 and sulfur dioxide (SO2) by mole as the SO2 dopant is found to be promising to increase the cycle thermal efficiency while offering a good thermal stability at the proposed turbine inlet temperature. The turbine design process for non-conventional working fluids is challenged by the availability of validated loss models, as well as the nature of the working fluid. Aerodynamic and mechanical constraints have been integrated into an in-house mean-line design code to derive the basic flow path at a turbine inlet conditions of 700 C and 240 bar, with a total-to-static pressure ratio of 2.94 and gross power output of 130 MW. It was found that suitable stress and rotodynamic constraints lead to a 14-stages design with 310 mm hub diameter and 1700 mm axial length which cannot be considered compact as mentioned in other sCO2 turbines case studies from the literature. The 3D blade geometry was then generated based on the initial mean-line design parameters along with preliminary assumptions that are evaluated and optimised utilising a computational fluid dynamics (CFD) model. The blade shape optimisation was carried out using a single-stage, steady-state model applied to the first and last turbine stages of the multi-stage design. The resulting modifications were extrapolated to the other turbine stages to evaluate the performance of the whole turbine. The final turbine design has shown a total-to-total efficiency of 93.3% with maximum stress that is less than 260 MPa and a mass-flow rate within 2% of the intended cycle mass-flow rate

Integrated Aerodynamic and Structural Blade Shape Optimization of Axial Turbines Operating With Supercritical Carbon Dioxide Blended With Dopants

Paper No: GTP-22-1269.Within this study, the blade shape of a large-scale axial turbine operating with sCO2 blended with dopants is optimized using an integrated aerodynamic-structural three-dimensional (3D) numerical model, whereby the optimization aims at maximizing the aerodynamic efficiency whilst meeting a set of stress constraints to ensure safe operation. Specifically, three candidate mixtures are considered, namely, CO2 blended with titanium tetrachloride (TiCl4), hexafluorobenzene (C6F6), or sulfur dioxide (SO2), where the selected blends and boundary conditions are defined by the EU project, SCARABEUS. A single passage axial turbine numerical model is setup and applied to the first stage of a large-scale multistage axial turbine design. The aerodynamic performance is simulated using a 3D steady-state viscous computational fluid dynamic (CFD) model while the blade stress distribution is obtained from a static structural finite element analysis simulation (FEA). A genetic algorithm is used to optimize parameters defining the blade angle and thickness distributions along the chord line while a surrogate model is used to provide fast and reliable model predictions during optimization using a genetic aggregation response surface. The uncertainty of the surrogate model, represented by the difference between the surrogate model results and the CFD/FEA model results, is evaluated using a set of verification points and is found to be less than 0.3% for aerodynamic efficiency and 1% for both the mass-flow rate and the maximum equivalent stresses. The comparison between the final optimized blade cross section has shown some common trends in optimizing the blade design by decreasing the stator and rotor trailing edge thickness, increasing the stator thickness near the trailing edge, and decreasing the rotor thickness near the trailing edge and decreasing the rotor outlet angle. Further investigations of the loss breakdown of the optimized and reference blade designs are presented to highlight the role of the optimization process in reducing aerodynamic losses. It has been noted that the performance improvement achieved through shape optimization is mainly due to decreasing the endwall losses with both the stator and rotor passages.European Union's Horizon 2020 (Funding Topic: LC-SC3-RES-11-2018, Grant Agreement No. 814985; Funder ID: 10.13039/100010661)

Off-design performance assessment of an axial turbine for a 100 MWe concentrated solar power plant operating with CO2 mixtures

This paper presents an investigation of the aerodynamic performance of a 130 MW axial turbine operating with a CO2/SO2 mixture using a mean-line off-design performance model; where the validity of this model has been confirmed through verification against results from the literature and computational fluid dynamic (CFD) simulations. This analysis also includes assessing the impact of varying the number of stages on the part-load operation. Additionally, the application of similitude theory to non-dimensionalise performance characteristics is validated by assessing the performance of the same turbine with different working fluids, mixture compositions, and rotational speeds. The mean-line performance model applied throughout this study is based on the Aungier loss model, whilst a multi-stage, Reynolds averaged CFD model is employed to assess the 3D flow behaviour using the turbulence model. Significant deviations in total-to-total efficiency were observed between the mean-line and CFD results during part-load operation, especially at lower mass flow rates. These deviations can reach up to 18% when the blade Mach number exceeds the design point by 12%. This is attributed to flow separation, which is evident from the CFD simulations, and the mean-line loss model fails to predict. From a purely aerodynamic standpoint, the turbine can operate at part-load conditions up to 88.5% of the design flow coefficient based on the CFD results and achieve an efficiency of 80.2%. It was also found that increasing the number of stages from 4 to 14 can improve the off-design total-to-total efficiency by approximately 7.7% at 93% of the design flow coefficient. This demonstrates that increasing the number of stages enhances turbine performance at both design and part-load operations. Finally, the similitude scaling laws formulated using real-gas equation of state were found to remain valid for all the mixtures, molar compositions, and operating conditions considered

Integrated aerodynamic and structural blade shape optimisation of axial turbines operating with supercritical carbon dioxide blended with dopants

Paper No: GT2022-81223, V009T28A004.Within this study, the blade shape of a large-scale axial turbine operating with sCO2 blended with dopants is optimised using an integrated aerodynamic-structural 3D numerical model, whereby the optimisation aims at maximising the aerodynamic efficiency whilst meeting a set of stress constraints to ensure safe operation. Specifically, three candidate mixtures are considered, namely CO2 blended with titaniumtetrachloride (TiCl4), hexafluorobenzene (C6F6) or sulfur dioxide (SO2), where the selected blends and boundary conditions are defined by the EU project, SCARABEUS. A single passage axial turbine numerical model is setup and applied to the first stage of a large-scale multi-stage axial turbine design. The aerodynamic performance is simulated using a 3D steady-state viscous computational fluid dynamic (CFD) model while the blade stress distribution is obtained from a static structural finite element analysis (FEA). A genetic algorithm is used to optimise parameters defining the blade angle and thickness distributions along the chord line while a surrogate model is used to provide fast and reliable model predictions during optimisation using genetic aggregation response surface. The uncertainty of the surrogate model represented by the difference between the surrogate model results and the CFD/FEA model results is evaluated using a set of verification points and found to be less than 0.3% for aerodynamic efficiency and 1% for both the mass flow rate and the maximum equivalent stresses. The comparison between the final optimised blade cross-sections have shown some common trends in optimising the blade design by decreasing stator and rotor trailing edge thickness, increasing stator thickness near the trailing edge, decreasing rotor thickness near the trailing edge and decreasing the rotor outlet angle. Further investigations of the loss breakdown of the optimised and reference blade designs are presented to highlight the role of the optimisation process in reducing aerodynamic losses. It has been noted that the performance improvement achieved through shape optimisation is mainly due to decreasing the endwall losses of both stator and rotor blades

Design of a 130 MW axial turbine operating with a supercritical carbon dioxide mixture for the SCARABEUS project

The application of supercritical carbon dioxide (sCO2) mixtures in power generation cycles could improve power block efficiency for concentrated solar power applications. Mixing CO2 with titanium tetrachloride (TiCl4), hexafluoro-benzene (C6F6), sulphur dioxide (SO2) or others increases the critical temperature of the working fluid, allowing it to condense at ambient temperatures in dry solar field locations. Therefore, transcritical power cycles, which have lower compression work and higher thermal efficiency compared to supercritical cycles, become feasible. This paper presents the flow path design of a utility-scale axial turbine operating with an 80-20% molar mix of CO2 and sulphur dioxide (SO2). A preliminary turbine design has been developed for the selected mixture using an in-house mean-line design code considering both mechanical and rotor dynamic criteria. Furthermore, 3D blades have been generated and blade shape optimisation has been carried out for the first and last turbine stages of the multi-stage design. It has been found that increasing the number of stages from 4 to 14 stages increase the total-to-total efficiency by 6.3%. The final turbine design has a total-to-total efficiency of 92.9% as predicted by the 3D numerical results with maximum stress less than 260 MPa and a mass flow rate within 1% of the intended cycle mass-flow rate. Optimum aerodynamic performance was achieved with a 14-stages design where the hub radius and the flow path length are 310 mm and 1800 mm respectively

A comparative study of microcystin-LR degradation by UV-a, solar and visible light irradiation using bare and C/N/S-modified titania

In an endeavor to tackle environmental problems, the photodegradation of microcystin- LR (MC-LR), one of the most common and toxic cyanotoxins, produced by the cyanobacteria blooms, was examined using nanostructured TiO2 photocatalysts (anatase, brookite, anatase- brookite, and C/N/S co-modified anatase-brookite) under UV-A, solar and visible light irradiation. The tailoring of TiO2 properties to hinder the electron-hole recombination and improve MC-LR adsorption on TiO2 surface was achieved by altering the preparation pH value. The highest photocatalytic efficiency was 97% and 99% with degradation rate of 0.002 mmol L-1 min-1 and 0.0007 mmol L-1 min-1 under UV and solar irradiation, respectively, using a bare TiO2 photocatalyst prepared at pH 10 with anatase to brookite ratio of ca. 1:2.5. However, the bare TiO2 samples were hardly active under visible light irradiation (<25%) due to a large band gap. Upon UV, solar and vis irradiation, the complete MC-LR degradation (100%) was obtained in the presence of C/N/S comodified TiO2 with a degradation rate constant of 0.26 min-1, 0.11 min-1 and 0.04 min-1, respectively. It was proposed that the remarkable activity of co-modified TiO2 might originate from its mixedphase composition, mesoporous structure, and non-metal co-modification