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HIMENO, Takehiro, i Toshinori WATANABE. "Thermo-Fluid Management under Low-gravity Conditions. 1st Report. TCUP Method for the Analysis of Thermo-Fluid Phenomena." Transactions of the Japan Society of Mechanical Engineers Series B 69, nr 678 (2003): 266–73. http://dx.doi.org/10.1299/kikaib.69.266.
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Fotovvati, Behzad, i Kevin Chou. "Multi-layer thermo-fluid modeling of powder bed fusion (PBF) process". Journal of Manufacturing Processes 83 (listopad 2022): 203–11. http://dx.doi.org/10.1016/j.jmapro.2022.09.003.
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Di Piazza, I., M. Angelucci, R. Marinari, M. Tarantino i D. Martelli. "Thermo-fluid dynamic transients in the NACIE-UP facility". Nuclear Engineering and Design 352 (październik 2019): 110182. http://dx.doi.org/10.1016/j.nucengdes.2019.110182.
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Martelli, D., R. Marinari, I. Di Piazza, P. Lorusso i M. Tarantino. "Thermo-fluid dynamic analysis of HLM pool. Circe experiments". Nuclear Engineering and Design 409 (sierpień 2023): 112347. http://dx.doi.org/10.1016/j.nucengdes.2023.112347.
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Gabrielaitienė, Irena, Rimantas Kačianauskas i Bengt Sunden. "THERMO-HYDRAULIC FINITE ELEMENT MODELLING OF DISTRICT HEATING NETWORK BY THE UNCOUPLED APPROACH". JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 9, nr 3 (30.09.2003): 153–62. http://dx.doi.org/10.3846/13923730.2003.10531321.
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The modelling of uncoupled fluid flow and heat transfer problems of a district heating network using the finite element method (FEM) is presented. Since the standard thermo-hydraulic pipe elements cannot be directly used for modelling insulation, the main attention was paid to discretisation of multilayered structure of pipes and surrounding by one-dimensional thermal elements. In addition, validity of the finite element method was verified numerically by solving fluid flow and heat transfer problems in district heating pipelines. Verification analysis involves standard single pipe problems and simulation of fragment of district heating in Vilnius. Pressure and temperature results obtained by finite element method are compared with those by other approaches.
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HIMENO, Takehiro, i Toshinori WATANABE. "Thermo-Fluid Management under Low-gravity Conditions (2nd Report, Free-Surface Flows Driven by Surface Forces)". Transactions of the Japan Society of Mechanical Engineers Series B 69, nr 687 (2003): 2400–2407. http://dx.doi.org/10.1299/kikaib.69.2400.
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Lee, Seung D., Jong K. Lee i Kune Y. Suh. "Natural convection thermo fluid dynamics in a volumetrically heated rectangular pool". Nuclear Engineering and Design 237, nr 5 (marzec 2007): 473–83. http://dx.doi.org/10.1016/j.nucengdes.2006.07.012.
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Tahmasebi, Pejman, i Serveh Kamrava. "A pore-scale mathematical modeling of fluid-particle interactions: Thermo-hydro-mechanical coupling". International Journal of Greenhouse Gas Control 83 (kwiecień 2019): 245–55. http://dx.doi.org/10.1016/j.ijggc.2018.12.014.
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Jayaraman, Balaji, Siddharth Thakur i Wei Shyy. "Modeling of Fluid Dynamics and Heat Transfer Induced by Dielectric Barrier Plasma Actuator". Journal of Heat Transfer 129, nr 4 (2.01.2007): 517–25. http://dx.doi.org/10.1115/1.2709659.
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Glow discharge at atmospheric pressure using a dielectric barrier discharge can induce fluid flow, and can be used for active control of aerodynamics and heat transfer. In the present work, a modeling framework is presented to study the evolution and interaction of such athermal nonequilibrium plasma discharges in conjunction with low Mach number fluid dynamics and heat transfer. The model is self-consistent, coupling the first-principles-based discharge dynamics with the fluid dynamics and heat transfer equations. Under atmospheric pressure, the discharge can be simulated using a plasma–fluid instead of a kinetic model. The plasma and fluid species are treated as a two-fluid system coupled through force and pressure interactions, over decades of length and time scales. The multiple-scale processes such as convection, diffusion, and reaction/ionization mechanisms make the transport equations of the plasma dynamics stiff. To handle the stiffness, a finite-volume operator-split algorithm capable of conserving space charge is employed. A body force treatment is devised to link the plasma dynamics and thermo-fluid dynamics. The potential of the actuator for flow control and thermal management is illustrated using case studies.
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Rinaldi, Claudia, Valerio Bicego i Pier Paolo Colombo. "Validation of CESI Blade Life Management System by Case Histories and in situ NDT". Journal of Engineering for Gas Turbines and Power 128, nr 1 (1.03.2004): 73–80. http://dx.doi.org/10.1115/1.2056534.
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A life management system was developed for hot components of large industrial gas turbines, in the form of a software tool for predicting component lives under typical operational transients (normal and also abnormal) and steady-state periods. The method utilizes results of previous thermo-mechanical finite element and finite volume fluid mechanics analyses. The basic idea of this method is using data from structural and aero-thermal analyses (pressures and temperatures), blade life theory, and material properties as an input to algorithms, and using operational and historical data to validate the predicted damage amounts. The software developed in this project, of general applicability to all GT models, has been implemented with reference to the geometries, materials, and service conditions of a Fiat-Westinghouse model.
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Adesanya, Samuel O., Peace O. Banjo i Ramoshweu S. Lebelo. "Exergy Analysis for Combustible Third-Grade Fluid Flow through a Medium with Variable Electrical Conductivity and Porous Permeability". Mathematics 11, nr 8 (15.04.2023): 1882. http://dx.doi.org/10.3390/math11081882.
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A mathematical investigation of a thermodynamical system linked with energy management and its impact on the environment, especially climate change, is presented in this study. In this regard, a numerical investigation of the flow and heat transfer of hydromagnetic third-grade liquid through a porous medium. The permeability of the medium and electrical conductivity of the fluid are assumed to be temperature functions. The appropriate mathematical formulations for momentum, energy, and entropy equations are presented in both dimensional and dimensionless forms. We obtained the numerical solutions using the spectral version of the Chebyshev collocation method and compared the result with the shooting Runge–Kutta method. Numerical results for velocity, temperature, entropy, and Bejan profiles are communicated through tables and graphs with adequate physical interpretation. The thermal stability of the thermo-fluid system that guarantees the prevention of spontaneous fluid heating that fuels climate change is also included in the analysis.
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Angelova, Radostina A., Priscilla Reiners, Elena Georgieva i Yordan Kyosev. "The effect of the transfer abilities of single layers on the heat and mass transport through multilayered outerwear clothing for cold protection". Textile Research Journal 88, nr 10 (10.03.2017): 1125–37. http://dx.doi.org/10.1177/0040517517697642.
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This paper deals with performance properties related to human thermo-physiological comfort of three-layer textile systems used for the production of outerwear for cold protection. The transfer of heat and fluids through the compound single layers (woven and non-woven) is investigated and compared to the heat and mass transfer of the systems for clothing. Six characteristics are measured for both single layers and systems of layers: thermal resistance, air permeability, water vapor resistance, relative water vapor permeability, the accumulative one-way transport index and overall moisture management capacity. For each of the characteristics, regression analysis is applied to prove or reject the proposed mathematical dependencies between the transfer abilities of the single layers and the respective systems. The results obtained showed that the fluid transfer abilities of the single layers applied in clothing for cold protection strongly affect the fluid transfer ability of the system of layers, while the heat transfer of the system is dominated by the heat transfer ability of the thermo-insulating layer. The proposed approach for assessment of the transfer processes through a system of layers for the production of outerwear for cold protection could be successfully applied in the design of other textile and clothing items, produced by using systems of different textile layers.
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Alam, Mir Waqas, i Basma Souayeh. "Parametric CFD Thermal Performance Analysis of Full, Medium, Half and Short Length Dimple Solar Air Tube". Sustainability 13, nr 11 (7.06.2021): 6462. http://dx.doi.org/10.3390/su13116462.
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In the present decade, research regarding solar thermal air heaters (SAHs) has noticed a continuous progression in thermo-hydraulic performance augmentation approaches. There now exists a wide variety of thermo-hydraulic performance augmentation approaches and researchers have designated various structures. Nevertheless, there seems to be no generalization to any of the approaches employed. The present numerical investigation reports on the thermo-hydraulic characteristics and thermal performance for flow through a varied length (full, medium, half, and short length) dimple solar air heater (SAH) tube. The study highlights recent developments on enhanced tubes to augment heat transfer in SAH. The influence of different length ratio, dimple height ratio (H), and pitch ratio (s) on thermo-hydraulic characteristics have been investigated in the Reynolds number (Re) range from 5000 to 25,000. Air is used as the working fluid. The commercial software ANSYS Fluent is used for simulation. The shear stress transport (SST) model is used as the turbulence model. Thermal energy transport coefficient is increased in the full-length dimple tube (FLDT), compared to the medium-length dimple tube (MLDT), half-length dimple tube (HLDT) and short-length dimple tube (SLDT). Similarly, the pitch ratio (s) has more influence on Nusselt number (Nu) compared to the dimple height ratio (H). The friction factor decreases with an increase in pitch ratio. Nu increases and f decreases with increasing Re for all combinations of H and s. Low s and higher H yields high enhancement of HT and PD. Integration of artificial roughness on the tube increases the values of Nu and f by 5.12 times and 77.23 times for H = 0.07, s = 1.0 at Re value of 5000 and 25,000, respectively, in regard to the plain tube. For all the tested cases, the thermo-hydraulic performances (η) are greater than unity.
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Jiang, Tieliu, Mingqi Liu i Jianqing Lin. "A Detailed Numerical Study of a Nanofluid-Based Photovoltaic/THERMAL Hybrid System under Non-Uniform Solar Flux Distribution". Sustainability 15, nr 5 (1.03.2023): 4377. http://dx.doi.org/10.3390/su15054377.
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The concentrated photovoltaic/thermal system (CPVT) adopting spectral beam splitting is a promising field of solar energy research. However, the thermo-electric properties of fluid-based CPVT collectors, which depend strongly on the non-uniform concentrated energy flux, remain unclear. This study aims to fill the gap and explore the thermo-electric properties of fluid-based CPVT collectors under non-uniform energy flux based on the finite volume method (FVM) with the Monte Carlo Ray-Trace (MCRT) method. The actual solar flux distribution on the receiver surface is obtained using Tracepro software. Then, the realistic non-uniform energy flux was employed in ANSYS Workbench 2022R1 software as a boundary condition to increase the accuracy of the CFD modeling of the system. The model is validated by comparing the results of the reference data. Moreover, the impact of uniform and non-uniform energy flux on the PV cell temperature is analyzed. In addition, the effects of mass flow rate on the electrical and thermal performance of the system are investigated. The results show that the PVT hybrid system has high conversion efficiency, with a total efficiency of more than 50%. Notably, the extreme non-uniformity of the solar-concentrated energy flux can result in local overheating of the PV cell, which may lead to irreversible damage.
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Suvarna, T., i Dr M. Ravindra. "Combined Influence of Thermal Radiation, ThermoDiffusion, Radiation Absorption on Mixed Convective Heat and Mass Transfer Flow of a Micropolar Fluid in a Vertical Channel with Variable Temperature in the presence of Heat Sources". YMER Digital 21, nr 05 (7.05.2022): 152–61. http://dx.doi.org/10.37896/ymer21.05/19.
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The purpose of the present chapter is to analyze the thermal radiation, radiation absorption and thermo-diffusion on mixed convective heat and mass transfer flow of a micropolar fluid between two vertical parallel plates with varying temperature in the presence of heat sources. Such type of study may be applicable in nuclear reactors, heat exchangers and various electronic devices. The non-linear governinmg equations have been solved by employing Galerkin finite element technique with three nodded line segments.The velocity ,micro-rotation temperature and concentration have been analysed for different variations of Rd,Sr,Q1 , and p
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Yu, Peng, i Weimin Ma. "Comparative analysis of reactor pressure vessel failure using two thermo-fluid-structure coupling approaches". Nuclear Engineering and Design 368 (listopad 2020): 110819. http://dx.doi.org/10.1016/j.nucengdes.2020.110819.
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García-García, V., I. Mejía, H. Hernández-Belmontes, F. Reyes-Calderón, J. A. Benito i J. M. Cabrera. "Computational simulation of thermo-mechanical field and fluid flow and their effect on the solidification process in TWIP steel welds". Journal of Manufacturing Processes 84 (grudzień 2022): 100–120. http://dx.doi.org/10.1016/j.jmapro.2022.09.062.
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Zając, Piotr. "Compact Thermal Modelling Tool for Fast Design Space Exploration of 3D ICs with Integrated Microchannels". Energies 13, nr 9 (2.05.2020): 2217. http://dx.doi.org/10.3390/en13092217.
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Integrated microchannel cooling is a very promising concept for thermal management of 3D ICs, because it offers much higher cooling performance than conventional forced-air convection. The thermo-fluidic simulations of such chips are usually performed using a computational fluid dynamics (CFD) approach. However, due to the complexity of the fluid flow modelling, such simulations are typically very long and faster models are therefore considered. This paper demonstrates the advantages of TIMiTIC—a compact thermal simulator for chips with liquid cooling—and shows its practical usefulness in design space exploration of 3D ICs with integrated microchannels. Moreover, thermal simulations of a 3D processor model using the proposed tool are used to estimate the optimal power dissipation profile in the chip and to prove that such an optimal profile allows for a very significant (more than 10 °C) peak temperature reduction. Finally, a custom correlation metric is introduced which allows the comparison of the power distribution profiles in terms of the peak chip temperature that they produce. Statistical analysis of the simulation results demonstrates that this metric is very accurate and can be used for example in thermal-aware task scheduling or dynamic voltage and frequency scaling (DVFS) algorithms.
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Yan, Xufeng, Kangsheng Xue, Xiaobo Liu i Xiaolou Chi. "A Novel Numerical Method for Geothermal Reservoirs Embedded with Fracture Networks and Parameter Optimization for Power Generation". Sustainability 15, nr 12 (19.06.2023): 9744. http://dx.doi.org/10.3390/su15129744.
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Geothermal recovery involves a coupled thermo-hydro-mechanical (THM) process in fractured rocks. A fluid transient equilibrium equation, considering thermal conduction, convection, and heat exchange, is established. The evolution of the reservoir permeability and the variance in the fracture aperture due to a change in the stress field are derived simultaneously. THM coupling is accomplished through iterative hydromechanical and thermo-hydro processes. To overcome the difficulty of geometric discretization, a three-dimensional THM coupler model embedded with discrete fracture networks, using a zero-thickness surface and line elements to simulate fractures and injection/production wells, is established to evaluate the geothermal production. The reliability of the method is verified by a case study. Then, this method is applied to evaluate the influence of the geometric topological characteristics of fracture networks and the fracture aperture on the reservoir temperature evolution and heat extraction effectiveness. The results show that the power generation efficiency and geothermal depletion rate are significantly affected by the injection–production pressure. Injection wells and production wells with pressures higher than the initial fluid pressure in the fractures can be used to significantly increase power generation, but the consumption of geothermal energy and loss of efficiency are significant and rapid. To achieve better benefits for the geothermal recovery system, an optimization algorithm based on simultaneous perturbation stochastic approximation (SPSA) is proposed; it takes the power generation efficiency as the objective function, and the corresponding program is developed using MATLAB to optimize the position and pressure values for each production well. The results show that the heat transfer for the entire EGS reservoir becomes more uniform after optimization, and the heat transfer efficiency is greatly improved.
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Rücker, Carsten. "Open Source Software Library for Thermo-Hydro-Mechanical Coupled Processes in Python". Safety of Nuclear Waste Disposal 1 (10.11.2021): 185–86. http://dx.doi.org/10.5194/sand-1-185-2021.
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Abstract. This contributed poster shows the current state of development of a finite element implementation as part of an open source software library (OSSL) for the simulation of thermo-hydro-mechanical (THM) coupled processes. The reliable handling of numerical methods is fundamental for the understanding of scientific interrelationships and thus, a crucial prerequisite for modeling THM scenarios, as well as for the understanding and evaluation of preliminary safety investigations during the site selection process for the storage of high-level radioactive waste. There are several motivations for developing an in-house OSSL, which will allow us to: Build capacity and maintenance within BASE (Federal Office for the Safety of Nuclear Waste Management) regarding issues of the numerical modeling of safety-relevant aspects on the long-term safety analyses specified by the German legislator in the site selection process. Develop a collection of known benchmarks and evaluation examples for the comparison of different software tools, applying a uniform interface to simplify the use of the available highly specialized open source codes. Diversify the testing possibilities regarding the preliminary safety investigations by means of our own, independent modeling software. Document basic THM scenarios for internal or, if necessary, public technical training, e.g., density-driven fluid flow (Fig. 1), convergence in salt, temperature propagation in the repository area, crack development, diffusive or advective mass transport. Ensure transparency and, in principle, might allow for appropriately proven-quality (validated) and documented simulation tools for the public regarding questions about the preliminary safety investigations during the site selection process. The development of the OSSL is mainly based on the scripting language Python, which allows the necessary flexibility for the diverse fields of application and at the same time enables maximum transparency for all aspects of the source code. To ensure the high quality of the software, state of the art development tools are used (e.g., version control, automated tests, and documentation generation). Figure 1 shows our preliminary simulation results of the so-called Elder problem (Elder, 1967), a popular standard benchmark for thermo-hydrogeological coupling in which fluid motion in a porous medium is driven by buoyancy forces.
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Tak, Nam-il, Hong Sik Lim, Jonggan Hong, Jung Yoon, Byung Ha Park i Jaehyuk Eoh. "Improvement of GAMMA+ code for system transient and thermo-fluid safety analysis of sodium-cooled fast reactors". Nuclear Engineering and Design 399 (grudzień 2022): 112002. http://dx.doi.org/10.1016/j.nucengdes.2022.112002.
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Choi, Hwi-Ung, Kwang-Am Moon, Seong-Bhin Kim i Kwang-Hwan Choi. "CFD Analysis of the Heat Transfer and Fluid Flow Characteristics Using the Rectangular Rib Attached to the Fin Surface in a Solar Air Heater". Sustainability 15, nr 6 (17.03.2023): 5382. http://dx.doi.org/10.3390/su15065382.
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This study discussed the effect of ribbed fin, which was suggested by the authors, on the enhancement of heat transfer and flow characteristics of fluid in a solar air heater. The ribbed fin has a rectangular rib at the base and side surfaces of the fin. Thus, it can increase the heat transfer coefficient in the fluid field of a solar air heater as well as extend the heat transfer area. The simulation was performed with various Reynolds numbers, relative heights, and pitches of the rib. The presence of the rib enhances the heat transfer performance by 3.497 times over a smooth fin. However, the addition of the rib also increases pressure drop. Thus, the thermo-hydraulic performance, which considers both heat transfer enhancement and pressure drop increase, was also discussed. Furthermore, this study developed correlations for the Nusselt number and friction factor as a function of geometric condition of the rib and Reynolds number. The correlations accurately predicted the Nusselt number for the base and side surfaces of the fin and friction factor with mean absolute percent errors of 4.24%, 4.53%, and 7.33%, respectively.
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Tak, Nam-Il, Yonghee Kim, Jae-Hyuk Choi i Won Jae Lee. "Thermo-fluid investigation on a double-side-cooled annular fuel for the prismatic very high temperature gas-cooled reactor". Nuclear Engineering and Design 238, nr 10 (październik 2008): 2821–27. http://dx.doi.org/10.1016/j.nucengdes.2008.05.008.
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Vitali, M., G. Biancini, B. Marchetti i F. Corvaro. "Experimental and numerical analysis of the convective flow induced over a dry-ice bank with Particle Image Velocimetry". Journal of Physics: Conference Series 2385, nr 1 (1.12.2022): 012056. http://dx.doi.org/10.1088/1742-6596/2385/1/012056.
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Abstract The utilization of carbon dioxide in new technologies opens a wide range of interesting applications which depend strictly upon heat transfer phenomena. The momentum on the deployment of Carbon Capture Utilization and Storage (CCUS) infrastructures will potentially enlarge the diffusion of technologies for the utilization and recycling of CO2. Such applications, however, require appropriate laboratory investigations for a complete characterization of the CO2 thermo-fluid-dynamic behaviour. The safety management of carbon dioxide is important; thus, accurate modelling is needed since solidification and sublimation of dry-ice can be very challenging to predict analytically. One of the dry-ice applications is the utilisation in refrigeration cycles and in novel CO2 heat pump technologies. For this reason, knowledge about the entity of sublimating CO2 from a solid surface is crucial. This work proposes an innovative experimental setup for the measurement of temperature and convective velocity fields in the sublimating phenomenon of CO2 under atmospheric conditions by means of Particle Image Velocimetry (PIV). The experimental results have been compared and validated with numeric CFD models.
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Jamil, Muhammad, Asif Iqbal, Ning He i Quentin Cheok. "Thermophysical Properties and Heat Transfer Performance of Novel Dry-Ice-Based Sustainable Hybrid Lubri-Coolant". Sustainability 14, nr 4 (20.02.2022): 2430. http://dx.doi.org/10.3390/su14042430.
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It is a well-known fact that the consumption of conventional cutting fluids in metalworking industries leads to severe health and environmental issues. Owing to the EPA (Environmental Protection Agency) increasing regulations regarding pollution and contamination, there is a dire need for a greener fluid with excellent cooling and lubrication characteristics to diminish the environmental impact of cutting fluids, as well as to improve machinability. Cryogens are greener and excellent coolants but poor lubricants, while ester oils are excellent lubricants and poor coolants. Therefore, a hybrid lubri-coolant cutting fluid with synergistic cooling and lubrication characteristics could be a desideratum to replace conventional cutting fluid. To investigate a newly proposed hybrid lubri-coolant, thermophysical properties (density, thermal conductivity, specific heat, and viscosity), heat transfer properties (surface temperature, heat flux, and heat transfer coefficient), and machinability properties (tool life, etc.) are key characteristics of the fluids that decide phase change and heat dissipation capabilities during their application in machining. In the current experimental study, hybrid ethanol–ester oils with/without dry ice (−78 °C) are proposed as cutting fluids and holistically investigated in terms of thermo-physical properties, heat transfer properties, and machinability properties under different cutting conditions. Experimental findings have depicted a 20%, 10%, and 5% decrease in density, specific heat, and viscosity, respectively, with a 15% increase in the thermal conductivity of the fluid with the addition of dry ice. The dry-ice-based hybrid lubri-coolant sprayed onto a Ti-6Al-4V plate enhanced the heat transfer coefficient significantly by 17% compared to hybrid lubri-coolant without dry ice. Besides, hybrid ethanol–ester oil dry ice was treated as a trendsetter and indicated an 11% improvement of the tool life at a cutting speed of 75 m/min and a feed rate of 0.04 mm/z. Therefore, dry-ice-based hybrid lubri-coolant can be applied as a cutting fluid by practitioners in aerospace, automotive, prosthetic body parts manufacturing, and manufacturing industries.
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Chiavola, Ornella, Edoardo Frattini, Fulvio Palmieri, Ambra Fioravanti i Pietro Marani. "On the Efficiency of Mobile Hydraulic Power Packs Operating with New and Aged Eco-Friendly Fluids". Energies 16, nr 15 (28.07.2023): 5681. http://dx.doi.org/10.3390/en16155681.
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With the increasing environmental awareness, in many applications, ranging from agriculture to industry and logistics, a wider and wider use of eco-friendly fluids is desirable. Although the chemical and biological aspects related to environmental compatibility have been extensively investigated by industries and researchers for obvious environmental reasons, not much literature is available on the performance of hydraulic components and systems operating with eco-friendly fluids, especially on the possible degradation of performance due to fluid aging. This work is aimed at studying the influence of eco-friendly fluids on the performance of external gear pumps for compact mobile hydraulic power units, which are among the most widespread hydraulic devices in the world, for their cost-effective and flexible construction. Once the experimental set-up is implemented to be well representative of the hydraulic power packs’ typical arrangement, pump performance is investigated. Pump energy performance is obtained in terms of volumetric efficiency and torque efficiency. Alongside the traditional fluid, two types of eco-friendly fluid available in the market are tested. Once the comparison is complete, the investigations are devoted to highlighting the impact of fluid aging on the pump performance. The fluids were aged through 2000 h operation under heavy-duty thermo-mechanical stress on a separate set-up and, afterwards, the pump performance was tested again with aged fluids. The results allow the assessment of the influence of different fluids on pump performance and a comparison of the impact of new versus aged eco-friendly fluids. The eco-friendly fluids exert a significant effect on the pump energy profile. The pump overall efficiency increases, marking an up to 5% improvement, depending on the cases. Fluid aging is found to reduce the pump’s overall performance. This paper addresses the key points defining the pump performance and provides new information on the topic. The results are original and represent a fundamental contribution to define the best practices for energy and maintenance management of hydraulic systems and to foster the deployment of further studies on models and simulation tools to catch the effect of the fluid condition.
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Odhiambo, Morice R. O., Adnan Abbas, Xiaochan Wang i Ehsan Elahi. "Thermo-Environmental Assessment of a Heated Venlo-Type Greenhouse in the Yangtze River Delta Region". Sustainability 12, nr 24 (12.12.2020): 10412. http://dx.doi.org/10.3390/su122410412.
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Accurate evaluation of microclimate conditions in a greenhouse can assist producers to manage crop production and designers to optimize climate control systems. An assessment of the variable thermo-environmental behavior of a heated Venlo-type greenhouse under the influence of naturally changing climate conditions in the Yangtze River Delta region was undertaken. A three-dimensional transient computational fluid dynamics (CFD) model was developed to analyze the airflow pattern and dynamic distribution of temperature and humidity inside the greenhouse. Validation of the numerical model showed a satisfactory agreement between measured and simulated values of air velocity, temperature, and absolute humidity, with mean hourly air temperature mean absolute error (MAE) and root mean square error (RMSE) values of 7.7% and 7.9%, respectively, and mean hourly air humidity MAE and RMSE values of 16.18% and 16.42%, respectively. Simulation results demonstrated that the airflow pattern shaped the distribution of temperature and absolute humidity, and homogeneity of both variables was prevalent inside the greenhouse. These results could be adopted by growers and designers in the Yangtze River Delta region and other sub-tropical climatic regions to improve crop production and optimize climate control systems.
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Introini, Carolina, Davide Chiesa, Stefano Lorenzi, Massimiliano Nastasi, Ezio Previtali, Andrea Salvini, Monica Sisti, Luka Snoj i Antonio Cammi. "Assessment of the integrated mass conservative Kalman filter algorithm for Computational Thermo-Fluid Dynamics on the TRIGA Mark II reactor". Nuclear Engineering and Design 384 (grudzień 2021): 111431. http://dx.doi.org/10.1016/j.nucengdes.2021.111431.
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Alphonso, W. E., M. Baier, S. Carmignato, J. H. Hattel i M. Bayat. "On the possibility of doing reduced order, thermo-fluid modelling of laser powder bed fusion (L-PBF) – Assessment of the importance of recoil pressure and surface tension". Journal of Manufacturing Processes 94 (maj 2023): 564–77. http://dx.doi.org/10.1016/j.jmapro.2023.03.040.
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Mohamed, W. A. N. W., M. F. Remeli, A. H. A. Hamid i R. Atan. "Thermal and Coolant Flow Computational Analysis of Cooling Channels for an Air-Cooled PEM Fuel Cell". Applied Mechanics and Materials 110-116 (październik 2011): 2746–53. http://dx.doi.org/10.4028/www.scientific.net/amm.110-116.2746.
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Polymer Electrolyte Membrane (PEM) fuel cells are clean electrical power generators for applications normally up to 100 kW power requirements. It has the advantage of fast start-up due to its low operating temperatures of 60oC to 100oC. However, the low temperature requirement has to be addressed with an efficient thermal management system. For an air-cooled PEM fuel cell, cooling channels with a straight rectangular configuration are widely applied. This work establishes a computational methodology for the analysis of coolant flow mechanics related to the channel geometry for a specific bipolar plate size. The velocity and thermal gradient, average velocity rise factor (AVRF) and total cooling rates were determined from Computational Fluid Dynamics simulation based on initial coolant Reynolds number of approximately 250 to 750 with a steady heat flow of 82W. All geometries showed nearly 100% cooling capability respective to the heat load, but differ in the aspects of average plate temperature achieved, its temperature profile as well as existing gradient. From the analytical perspective of thermo fluids engineering, the selection criteria of suitable micro cooling channel configurations, depending on operating priority, was established.
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Selimefendigil, Fatih, Mondher Hamzaoui, Abdelkarim Aydi, Badr M. Alshammari i Lioua Kolsi. "Hybrid Nano-Jet Impingement Cooling of Double Rotating Cylinders Immersed in Porous Medium". Mathematics 11, nr 1 (23.12.2022): 51. http://dx.doi.org/10.3390/math11010051.
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A cooling system with impinging jets is used extensively in diverse engineering applications, such as solar panels, electronic equipments, battery thermal management, textiles and drying applications. Over the years many methods have been offered to increase the effectiveness of the cooling system design by different techniques. In one of the available methods, nano-jets are used to achieve a higher local and average heat transfer coefficient. In this study, convective cooling of double rotating cylinders embedded in a porous medium is analyzed by using hybrid nano-jets. A finite element formulation of the thermo-fluid system is considered, while impacts of Reynolds number, rotational speed of the double cylinders, permeability of the porous medium and distance between the cylinders on the cooling performance are numerically assessed. Hybrid and pure fluid performances in the jet cooling system are compared. It is observed that the cooling performance improves when the rotating speed of the cylinder, permeability of the medium and jet Reynolds number are increased. The heat transfer behavior when varying the distance between the cylinders is different for the first and second cylinder. Higher thermal performances are achieved when hybrid nanofluid with higher nanoparticle loading is used. An optimization algorithm is used for finding the optimum distance and rotational speeds of the cylinders for obtaining an improved cooling performance, while results show higher effectiveness as compared to a parametric study. The outcomes of the present work are useful for the thermal design and optimization of the cooling system design for configurations encountered in electronic cooling, energy extraction and waste heat recovery.
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Sharma, Pradeep Kumar, i Manvijay Singh. "EFFECT OF NANOFLUIDS ON PERFORMANCE OF SOLAR APPLIANCES: A Review". YMER Digital 20, nr 11 (23.11.2021): 331–39. http://dx.doi.org/10.37896/ymer20.11/30.
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The sun is a natural source of renewable energy. The use of solar energy may be especially important within global warming and the reduction of carbon dioxide emissions. solar energy is tested using solar thermal energy, photovoltaic energy development, and so on. Solar heat is the most common use around it. For solar-powered solar collectors, plates or tubes are coated with a layer of selective immersion fabric used to soak up solar energy, after which the energy is filled with excitement with the help of an active liquid within the heat form. This type of collector presents a number of shortcomings, including rules regarding incident congestion and relatively high heat loss. Lack of fossil fuels and environmental considerations have encouraged researchers to use energy sources that include solar energy. Therefore, it is important to maximize the efficiency and replicate solar thermal systems. Continuously, a few of the aforementioned nanofluid packages for thermal energy storage, solar cells, and sun exposure are being updated. Distribution defines the values of nanoparticles in a normal fluid base has a significant impact on the visible homes and the thermo-body of the fluid base. Enhancement of solar irradiance assimilation results in better heat transfer fines followed by more efficient heat transfer. Nanofluid suspension of nanoparticles in basic liquid, a new therapeutic goal of nanotechnology has been developed. Nanofluids have unique functions of a single type from a common stable liquid mixture in which mm or µm particles of metal and non-metallic particles are dispersed. due to its amazing properties, nanofluids are widely used to improve heat transfer. The purpose of this experimental manuscript is to examine nanofluids in solar panels. To overcome those problems, a direct sun suction collector has been used to exploit the heat of the sun.
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Layton, James, Benjamin C. Rothwell, Stephen Ambrose, Carol Eastwick, Humberto Medina i Neville Rebelo. "A New Thermal Elasto-Hydrodynamic Lubrication Solver Implementation in OpenFOAM". Lubricants 11, nr 7 (22.07.2023): 308. http://dx.doi.org/10.3390/lubricants11070308.
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Designing effective thermal management systems within transmission systems requires simulations to consider the contributions from phenomena such as hydrodynamic lubrication regions. Computational fluid dynamics (CFD) remains computationally expensive for practical cases of hydrodynamic lubrication while the thermo elasto-hydrodynamic lubrication (TEHL) theory has demonstrated good accuracy at a lower computational cost. To account for the effects of hydrodynamic lubrication in high-power transmission systems requires integrating TEHL into a CFD framework such that these methodologies can be interfaced. This study takes an initial step by developing a TEHL solver within OpenFOAM such that the program is prepared to be interfaced with a CFD module in future versions. The OpenFOAM solver includes the Elrod–Adams cavitation model, thermal effects, and elastic deformation of the surfaces, and considers mixing between the recirculating flow and oil feed by applying energy and mass continuity. A sensitivity study of the film mesh is presented to show the solution variation with refinement along the circumferential, axial and radial directions. A validation case is presented of an experimental single axial groove journal bearing which shows good agreement in the pressure and temperature results. The peak pressure in the film is predicted within 12% and the peak temperature in the bush is predicted within 5% when comparing the centerline profiles.
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Kumari, Wanniarachchige Gnamani Pabasara, i Pathegama Gamage Ranjith. "Experimental and Numerical Investigation of the Flow Behaviour of Fractured Granite under Extreme Temperature and Pressure Conditions". Sustainability 14, nr 14 (13.07.2022): 8587. http://dx.doi.org/10.3390/su14148587.
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As a result of negligible connected porosity—and thus, minimal matrix permeability—the fluid-transport characteristics of crystalline rocks are strongly influenced by the fractures at all scales. Understanding the flow behaviour of fractured rock under extreme stress and temperature conditions is essential for safe and effective deep geo-engineering applications, such as deep geothermal recovery, geological nuclear waste disposal, oil and gas extraction, geological storage and deep mining operations. Therefore, this study aims to investigate the flow characteristics of mechanically fractured Australian Strathbogie granite under a wide range of stress (confining pressures 1–80 MPa) and temperature conditions (20 °C to 350 °C). The study utilised a sophisticated high-temperature, high-pressure tri-axial setup capable of simulating extreme geological conditions, followed by a numerical simulation. According to the experimental results, a linear increment in the steady-state flow rate was observed, with increased injection pressure for the experimental conditions considered. Therefore, linear laminar Darcy flow was considered, and the fracture permeability was calculated using the cubic law. It was found that stress and temperature strongly depend on the flow of fluid through fractures. The steady-state flow rate decreased exponentially with the increase in normal stress, showcasing fracture shrinkage with an increment in effective stress. With regard to permeability through the fractures, increasing temperature was found to cause an initial reduction in fracture permeability due to an increased interlock effect (induced by thermal overclosure), followed by increments because of the thermally induced damage. Furthermore, the increasing temperature caused significant non-linear increments in the fluid flow rates due to the associated viscosity and density reduction in water. Considering the laboratory-scale flow-through exercises, a fully coupled numerical model that can predict hydro–thermo–mechanical variations in the reservoir rocks was developed using the COMSOL Multiphysics simulator. The developed model was calibrated, utilising the temperature- and pressure-dependent properties of granite rocks and fluid (water); was validated against the experimental results; and was used to predict the permeability, pressure development and strain of rock samples under extreme conditions, which were difficult to achieve in the laboratory.
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Pichler, Mario, Markus Bösenhofer i Michael Harasek. "Dataset for the Heat-Up and Heat Transfer towards Single Particles and Synthetic Particle Clusters from Particle-Resolved CFD Simulations". Data 7, nr 2 (14.02.2022): 23. http://dx.doi.org/10.3390/data7020023.
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Heat transfer to particles is a key aspect of thermo-chemical conversion of pulverized fuels. These fuels tend to agglomerate in some areas of turbulent flow and to form particle clusters. Heat transfer and drag of such clusters are significantly different from single-particle approximations commonly used in Euler–Lagrange models. This fact prompted a direct numerical investigation of the heat transfer and drag behavior of synthetic particle clusters consisting of 44 spheres of uniform diameter (60 μm). Particle-resolved computational fluid dynamic simulations were carried out to investigate the heat fluxes, the forces acting upon the particle cluster, and the heat-up times of particle clusters with multiple void fractions (0.477–0.999) and varying relative velocities (0.5–25 m/s). The integral heat fluxes and exact particle positions for each particle in the cluster, integral heat fluxes, and the total acting force, derived from steady-state simulations, are reported for 85 different cases. The heat-up times of individual particles and the particle clusters are provided for six cases (three cluster void fractions and two relative velocities each). Furthermore, the heat-up times of single particles with different commonly used representative particle diameters are presented. Depending on the case, the particle Reynolds number, the cluster void fraction, the Nusselt number, and the cluster drag coefficient are included in the secondary data.
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Manan, Abdul, Saif Ur Rehman, Nageen Fatima, Muhammad Imran, Bagh Ali, Nehad Ali Shah i Jae Dong Chung. "Dynamics of Eyring–Powell Nanofluids When Bioconvection and Lorentz Forces Are Significant: The Case of a Slender Elastic Sheet of Variable Thickness with Porous Medium". Mathematics 10, nr 17 (23.08.2022): 3039. http://dx.doi.org/10.3390/math10173039.
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We examine thermal management in the heat exchange of compact density nanoentities in crude base liquids. It demands the study of the heat and flow problem with non-uniform physical properties. This study was conceived to analyze magnetohydrodynamic Eyring–Powell nanofluid transformations due to slender sheets with varying thicknesses. Temperature-dependent thermal conductivity and viscosity prevail. Bioconvection due to motivated and dynamic microorganisms for Eyring–Powell fluid flow is a novel aspect herein. The governing PDEs are transmuted into a nonlinear differential structure of coupled ODEs using a series of viable similarity transformations. An efficient code for the Runge–Kutta method is developed in MATLAB script to attain numeric solutions. These findings are also compared to previous research to ensure that current findings are accurate. Computational activities were carried out with a variation in pertinent parameters to perceive physical insights on the quantities of interest. Representative outcomes for velocity, temperature, nanoparticles concentration, and bioconvection distributions as well as the local thermal transport for different inputs of parameters are portrayed in both graphical and tabular forms. The results show that the fluid’s velocity increases with mixed convection parameters due to growing buoyancy effects and the fluid’s temperature also increased with higher Brownian motion Nb and thermophoretic Nt. The numerical findings might be used to create efficient heat exchangers for increasingly challenging thermo-technical activities in manufacturing, construction, and transportation.
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Saha, Surojit, Tabish Alam, Md Irfanul Haque Siddiqui, Mukesh Kumar, Masood Ashraf Ali, Naveen Kumar Gupta i Dan Dobrotă. "Analysis of Microchannel Heat Sink of Silicon Material with Right Triangular Groove on Sidewall of Passage". Materials 15, nr 19 (10.10.2022): 7020. http://dx.doi.org/10.3390/ma15197020.
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Microchannel heat sink (MCHS) is a promising solution for removing the excess heat from an electronic component such as a microprocessor, electronic chip, etc. In order to increase the heat removal rate, the design of MCHS plays a vital role, and can avoid damaging heat-sensitive components. Therefore, the passage of the MCHS has been designed with a periodic right triangular groove in the flow passage. The motivation for this form of groove shape is taken from heat transfer enhancement techniques used in solar air heaters. In this paper, a numerical study of this new design of microchannel passage is presented. The microchannel design has five variable groove angles, ranging from 15° to 75°. Computational fluid dynamics (CFD) is used to simulate this unique microchannel. Based on the Navier–Stokes and energy equations, a 3D model of the microchannel heat sink was built, discretized, and laminar numerical solutions for heat transfer, pressure drop, and thermohydraulic performance were derived. It was found that Nusselt number and thermo-hydraulic performance are superior in the microchannel with a 15° groove angle. In addition, thermohydraulic performance parameters (THPP) were evaluated and discussed. THPP values were found to be more than unity for a designed microchannel that had all angles except 75°, which confirm that the proposed design of the microchannel is a viable solution for thermal management.
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De Vita, Mariangela, Francesco Duronio, Angelo De Vita i Pierluigi De Berardinis. "Adaptive Retrofit for Adaptive Reuse: Converting an Industrial Chimney into a Ventilation Duct to Improve Internal Comfort in a Historic Environment". Sustainability 14, nr 6 (13.03.2022): 3360. http://dx.doi.org/10.3390/su14063360.
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The reuse of architectural heritage is a topic of great interest for scientific research, involving aspects ranging from the architectural compatibility of the interventions to the performance updating of the artefacts, from the point of view of both energy consumption and internal comfort suitable for the new use. Compatible technological solutions exploit the passive cooling activating latent physical mechanisms of the building, of the envelope or its parts, such as openings and disused shafts. This work concerns the conversion of an old chimney, completely integrated into the historical envelope, into a ventilation duct for the air exchange and the internal comfort improvement of an old factory, proposing an adaptive retrofit solution during adaptive reuse intervention. Thermo-fluid dynamics analyses, performed with an ad hoc CFD solver for flows with flotation effects, verified the effective functionality of the device in summer and winter conditions. The results show that, in summer, the activation of passive ventilation improves the indoor comfort of the environment, while, in winter, it worsens them. This study demonstrates the usefulness of activating passive cooling phenomena in preserving historical architecture. Finally, the future potential of the application is presented by integrating the ventilation chimney with a mechanical control system to optimize its operation even in winter conditions.
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Owebor, K., C. O. C. Oko, E. O. Diemuodeke i O. J. Ogorure. "Thermo-environmental and economic analysis of an integrated municipal waste-to-energy solid oxide fuel cell, gas-, steam-, organic fluid- and absorption refrigeration cycle thermal power plants". Applied Energy 239 (kwiecień 2019): 1385–401. http://dx.doi.org/10.1016/j.apenergy.2019.02.032.
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Jager, L., L. J. Jennings, J. Blanco, B. Choy i R. Nayar. "Supernatant Fluid from Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration for Rapid Next-Generation Sequencing". American Journal of Clinical Pathology 158, Supplement_1 (1.11.2022): S50. http://dx.doi.org/10.1093/ajcp/aqac126.098.
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Abstract Introduction/Objective The aims of our study were to optimize the workflow of non-small cell carcinoma (NSCC) endobronchial ultrasound-guided bronchoscopy with transbronchial needle aspiration (EBUS-TBNA) samples to maximize tissue available for next-generation sequencing (NGS), preserve formalin-fixed paraffin-embedded (FFPE) cell blocks (CBs) for future testing, and shorten turnaround time (TAT) of NGS results. We evaluated the performance of supernatant fluid (SNF) processed from a dedicated aspirate for NGS testing. Methods/Case Report 20 EBUS-TBNA samples positive for NSCC on rapid on-site evaluation were collected and processed using a new workflow (Figure 1). Five aspirates were collected in formalin. One additional dedicated pass was collected fresh and centrifuged. The resulting cell pellet was added to the passes in formalin for FFPE CB processing. The SNF was recentrifuged. DNA and RNA were extracted from concentrated SNF for targeted testing using the Oncomine™ Precision Assay (Thermo Scientific™, Waltham, MA). NGS results from the corresponding FFPE CBs were used as “controls” for comparison. Results (if a Case Study enter NA) A total of 31 mutations were detected in SNF (Table 1). The most frequently mutated genes were TP53 (35%), EGFR (23%), KRAS (13%), CTNNB1 (6%), and ERBB2 (6%). EGFR and KRAS amplification, CDKN2A deletion, and SQSTM1-NTRK3 fusion alteration were also detected. There was 100% concordance between the mutations detected in SNF and corresponding FFPE CBs with comparable variant allele frequencies. TAT of NGS results was 1 day for SNF compared to 4 – 10 days for FFPE CB. Conclusion In our study, we were able to demonstrate the usefulness of NGS on SNF to provide reliable, rapid molecular results. This testing strategy was successfully incorporated into the workflow for tissue handling and processing between our clinical, cytopathology, and molecular teams. Molecular results were available at the same time as the cytologic diagnosis, allowing for timely reporting of a comprehensive diagnosis. This approach is particularly useful in patients with advanced disease requiring urgent management.
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Le Carlier De Veslud, Christian, Paul Alexandre, Michel Cuney, Gilles Ruffet, Alain Cheilletz i Denis Virlogeux. "40 Ar/39Ar thermochronology and thermal evolution of Meso-Variscan granitoids of the Charroux-Civray plutonic complex (Seuil du Poitou)". Bulletin de la Société Géologique de France 175, nr 2 (1.03.2004): 147–56. http://dx.doi.org/10.2113/175.2.147.
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Abstract The eastern part of the “Seuil du Poitou” area had been selected by the French National radioactive waste management agency (ANDRA) as a potential site for building an underground laboratory in granitic rocks. 17 cored bore holes, completed by petrographical, geochemical [Cuney et al., 2001], geophysical [Virlogeux et al., 1999] and structural [Gros and Genter, 1999] studies, have provided a detailed knowledge of the Charroux-Civray complex, hidden under a Jurassic sedimentary cover. Three main types of magmas were distinguished : medium-K calk-alkaline, high-K calk-alkaline and peraluminous. The first two types are largely predominant and belong to the “Limousin Tonalitic line” (LTL) [Peiffer, 1985 ; 1986]. They were emplaced between 356 ± 5 Ma to 349 ± 5 Ma from U-Pb dating of zircon [Bertrand et al., 2001], at a depth of 14 ± 2 km [Freiberger et al., 2001]. This work aims to reconstruct the thermochronological evolution of the Charroux-Civray complex from 40Ar/39Ar dating of biotite and amphibole, combined with available U/Pb ages [Bertrand et al., 2001] and thermo-barometric data derived from mineral paragenesis and fluid inclusions [Freiberger et al., 2001]. This reconstruction may provide interesting constraints on a stage not well understood in the evolution of the French Massif Central : the emplacement of the LTL granitoids. The datings were performed on alteration-free, single grain of biotite and amphibole from the main petrologic types, according to the procedure described by Ruffet et al. [1991] and [1995]. The closure temperatures of the isotopic systems have been assumed to be 300 ± 30 oC for biotites, 500 ± 50 oC for amphiboles, and 850 ± 50 oC for zircons [Villa, 1998 ; McDougall and Harrison, 1999]. Six samples were dated : two tonalites (samples 112 and 212t), a monzogranite (sample 106), a monzogabbro-diorite (sample 115), a monzodiorite (sample 104), and a granodiorite (sample 105). Some of the analyses have been performed twice to test the reproducibility of the 40Ar/39Ar measurements. The 14 age spectra obtained may be divided into four groups : plateau ages, which provide robust ages for the amphiboles of samples 104, 106, 112, and biotites from samples 106, 115 and 212t ; pseudo-plateaux ages : three biotites (samples 104, 105 and 112) display spectrum shapes that could be interpreted as resulting from 39Ar recoil, related to an incipient chloritisation [Ruffet et al., 1991 ; McDougall and Harrison, 1999]. The most reliable ages are therefore close to the apparent ages given by the high temperature steps ; 40Ar* excess, as suggested by the spectrum shape of the amphibole from sample 212t [McDougall and Harrison, 1999]. The preferred age is defined with 83 % of released gas, and has been confirmed by a duplicate analysis ; a meaningless spectrum has been obtained on the amphiboles from sample 115. A duplicate analysis provided an approximate age of 347 ± 1 Ma, calculated on a relatively flat segment of the age spectrum. These results show that : (1) the closure of the isotopic system of the amphiboles occurred at approximately the same time over the entire complex (about 348 Ma) ; (2) the closure of the isotopic system of the biotites occurred slightly after the closure of the amphiboles, but spread over a larger time interval (350–343 Ma), (3) all the samples display high temperature gradients between 500 and 300 oC (> 40 oC.my-1). These results are in good agreement with mineralogical and fluid inclusion thermo-barometric data [Freiberger et al., 2001]. Two scénarios may be invoked to explain such high temperature gradients : a fast exhumation episode (several mm/y) during the 350–340 Ma period. This model is not acceptable because it is incompatible with pre- and post-intrusion conditions constrained by thermo-barometric data ; a fast thermal equilibration of the complex with surrounding rocks at the end of a succession of nearly-synchronous emplacement of calk-alkaline intrusions. First-order numerical models were used to simulate the thermal equilibration of the intrusive bodies with surrounding rocks, assuming a purely conductive heat regime [Carslaw and Jaeger, 1959]. These models show that according to the size of intrusions, the thermal equilibrium with surrounding rocks is reached in less than 5 to 10 m.y. The calculated temperature gradients derived from these models are compatible with those deduced from 40Ar/39Ar ages. These data confirm the existence of a major calk-alkaline magmatic event on the Seuil du Poitou, at about 355–350 Ma, which would be synchronous with the emplacement of the large peraluminous Guéret-type granodiorites in the northern Limousin. The 40Ar/39Ar biotite ages indicate that a regional temperature of 250–300 oC was reached at ca. 340 Ma at a depth of about 9 km.
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Fatigati, Fabio, Davide Di Battista, Marco Di Bartolomeo, Luigi Mariani i Roberto Cipollone. "On the optimal design of sliding rotary vane pump for heavy-duty engine cooling systems". E3S Web of Conferences 312 (2021): 07017. http://dx.doi.org/10.1051/e3sconf/202131207017.
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Presently the on-the-road transportation sector is responsible of the 21% of the whole CO2 amount emitted into atmosphere. This pushes the International Governments and Organizations to provide strict limitations in terms of ICEs emissions, also introducing fees payment for the car manufacturers. The vehicle electrification allows certainly to meet these requirements, but the higher cost and the need of a green electricity still limit a widespread diffusion among all social classes. Thus, the technological improvement of internal combustion engine plays a key role in the transition period. Among these technologies, the engine thermal management allows to achieve a good compromise between the CO2 emission reduction and related costs. It was demonstrated that replacing the conventional centrifugal pump of engine cooling system with a sliding vane rotary pump (SVRP), important benefits in terms of CO2 emission reduction can be achieved as centrifugal pump efficiency decreases significantly when the engine works far from the maximum load (i.e. design point of the pump). Nevertheless, the complex thermo-fluid-dynamic phenomena taking place inside a SVRP make its design not immediate, particularly if heavy duty ICE cooling systems are considered. These applications indeed are challenging due to the wide operating range and the huge flow rates which pump must deliver. These operating requirements make difficult the choice of the main design parameters: among the different ones, the pump revolution speed and displaced volume. In the present paper a design strategy is developed for this type of pumps based on a comprehensive mathematical model of the processes occurring, predicting volumetric, indicated and mechanical efficiencies. The model was validated with a wide experimental activity so acting as virtual development platform. The results show how the best global efficiency (0.59) is achieved adopting a dual axial intake port configuration, with a suitable choice result of a trade-off between displaced volume and revolution speed. The analysis also show that the pump keeps its efficiency close to the design one for a wide operating range which is particularly suitable for the cooling of an ICE.
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Abbondanza, Marco, Nicolò Cavina, Enrico Corti, Davide Moro, Fabrizio Ponti i Vittorio Ravaglioli. "Development of a Combustion Delay Model in the Control of Innovative Combustions". E3S Web of Conferences 197 (2020): 06013. http://dx.doi.org/10.1051/e3sconf/202019706013.
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In modern internal combustion engines the research for innovative solutions aimed at the simultaneous reduction of engine-out pollutants and fuel consumption requires synergies from different application areas: the thermo-fluid dynamic design of the combustion chamber, the study and production of specific components for air and fuel supply, the development of sensors and related methods of analyzing their signals to control the combustion process. The most promising innovative combustion methodologies suitable to achieve high efficiency and low emissions, commonly named Low Temperature Combustions (LTC), usually require sophisticated techniques for the management of the combustion phase. With respect to the combustion angular position control, directly performed in traditional spark ignition engines through the ignition from the spark plug and in compression ignition engines by the timing of fuel injection, the ignition mechanisms of LTC combustions are characterized by a high sensitivity to the thermal conditions of the combustion chamber which greatly modifies the angular position of the combustion, mainly due to the combination of high ignition delays and lean homogeneous mixture. Once the hardware of the air and fuel supply systems has been defined, it is therefore essential to ensure the correct management of the combustion phase. In this paper a model for the estimation of the delay between the start of injection and the start of combustion is presented. The model has been developed analyzing the experimental data from a modified cylinder of a diesel engine, fueled with gasoline, while the other three cylinders were still running with Diesel fuel. This solution represents a first step that allows analyzing the behavior of the combustion of gasoline in a Diesel engine, with the final goal to inject gasoline in all the engine cylinders. In particular, the approach used is similar to the one already applied in a traditional turbocharged gasoline engine, where the goal was to estimate the time delay between the spark firing and the start of combustion, mainly to detect the presence of undesired pre-ignition due to the presence of hot spots related to slightly knocking conditions. As it is well known, the role of the pilot injection is to reduce the ignition delay of the main injection. However, to significantly accelerate the ignition of the fuel injected with the main injection, it is necessary to burn a sufficient quantity of the fuel injected by the pilot before the Top Dead Center position (TDC). The application of this model has to allow the implementation of a feed-forward control to stabilize the whole combustion process and achieve the best conversion efficiency from energy to work, taking into account the operational constraints that must be satisfied to guarantee the integrity of the engine and the compliance with the homologation rules.
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De Santis, M., N. Isailovic, A. Ceribelli, F. Motta, M. Vecellio, M. Caprioli, G. M. Guidelli, N. Luciano i C. Selmi. "AB0098 TOFACITINIB IS SUPERIOR TO DEXAMETHASONE IN MODULATING MAIT CELLS, INNATE LYMPHOID CELLS, AND Th9 CELLS IN PSORIATIC ARTHRITIS". Annals of the Rheumatic Diseases 81, Suppl 1 (23.05.2022): 1180.1–1180. http://dx.doi.org/10.1136/annrheumdis-2022-eular.4905.
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BackgroundTofacitinib is a potent and selective oral inhibitor prevalently of JAK1 and JAK3and is currently included in the international recommendations for the management of psoriatic arthritis (PsA). Nonetheless, the mechanisms of the immune response to the treatment remain unclear, particularly regarding the effects on overlooked immune cell subpopulations specifically involved in the pathogenesis of PsA, i.e. mucosal-associated invariant T cells (MAIT), innate lymphoid cells (ILCs), both relevant sources of IL-17, and T lymphocytes producing interleukin 9 (Th9). We thus investigated the effect of tofacitinib on these cell population function and compared with glucocorticoids.ObjectivesTo investigate the effect of tofacitinib and dexamethasone on MAIT cells, ILCs, and Th9 cells in PsA.MethodsWe investigated synovial fluid and peripheral blood mononuclear cells from patients with PsA that were cultured with phorbol myristate acetate (PMA)/ionomycin in the presence or absence of 100 or 300nM Tofacitinib or 1000uM Dexamethasone for 24 hours and the addition of brefeldin in the last 2 hours. FACS analysis allowed to identify MAIT cells by CD3+CD161+Valpha7.2TCR; ILCs by CD3+CD45+CD127+, from this population ILC1 were arrayed as cKit- CRTH2-; ILC2 as cKit +/- and CRTH2+, and ILC3 as cKit+ and CRTH2-; Th9: CD3+CD4+IL-9+.ResultsA significant decrease in IL-17 production was observed in CD8+ MAIT cells treated with tofacitinib 300 nM compared to untreated conditions, with a magnitude similar to what observed with dexamethasone [mean fluorescence intensity-MFI median 1920 (interquartile range-IQR 1597-2761), 18.6% (3.9-31.4) in untreated cultures; 1481 (1325-3163), 13.4% (4.5-9.3) in tofacitinib-treated cultures; 1511 (1147-2882); 11.5% (2.5-49) in Dexamethasone-treated cultures; Figure 1]. A reduction of IL-17 production was observed also in ILC3 [52.1% (4.2-59.4) in untreated cultures; 25.8% (5.3-40.3) in Tofacitinib-treated cultures; 35.4% (6.3-47.9) in dexamethasone-treated cultures]. A reduction of IL-9 production was observed in peripheral blood T cells [2.19% (1.3-2.3) in untreated cultures; 0.6% (0.0-1.8) in Tofacitinib-treated cultures; 0.97% (0.07-1.13) in Dexamethasone-treated cultures].Figure 1.ConclusionIn PsA, tofacitinib is superior to dexamethasone in reducing the production of IL-17 by synovial fluid MAIT cells and ILC3 cells and of IL-9 by peripheral blood T cells.Disclosure of InterestsMaria De Santis Grant/research support from: AbbVie, Amgen, Alfa-Wassermann, Biogen, Celgene, Eli-Lilly, Gilead, Janssen, MSD, Novartis, Pfizer, Sanofi-Genzyme, Actelion, Boehringer, Italfarmaco, Grunenthal, Roche, Natasa Isailovic: None declared, Angela Ceribelli Speakers bureau: Amgen, Paid instructor for: SPA Farmaceutici, Grant/research support from: Eli-Lilly, Grunenthal, GSK, Novartis, Pfizer, Francesca Motta Consultant of: Thermo-Fisher, Matteo Vecellio: None declared, Marta Caprioli: None declared, Giacomo Maria Guidelli Speakers bureau: Amgen, UCB, Galapagos, Eli-Lilly, Consultant of: Amgen, UCB, Galapagos, Eli-Lilly, Nicoletta Luciano Speakers bureau: Eli-Lilly, Galapagos, Consultant of: Eli-Lilly, Galapagos, Carlo Selmi Speakers bureau: AbbVie, Amgen, Alfa-Wassermann, Biogen, Celgene, Eli-Lilly, Gilead, Janssen, MSD, Novartis, Pfizer, Sanofi-Genzyme), Paid instructor for: AbbVie, Amgen, Alfa-Wassermann, Biogen, Celgene, Eli-Lilly, Gilead, Janssen, MSD, Novartis, Pfizer, Sanofi-Genzyme), Consultant of: AbbVie, Amgen, Alfa-Wassermann, Biogen, Celgene, Eli-Lilly, Gilead, Janssen, MSD, Novartis, Pfizer, Sanofi-Genzyme), Grant/research support from: AbbVie, Amgen, Janssen, Pfizer
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Singh, Niranjan Ramendra, Singh Onkar i Janakarajan Ramkumar. "Thermo-Hydraulic Performance of Square Micro Pin Fins under Forced Convection". International Journal of Heat and Technology 39, nr 1 (28.02.2021): 170–78. http://dx.doi.org/10.18280/ijht.390118.
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Thermal management of the new generation’s high performance electronic and mechanical devices is becoming important due to their miniaturization. Conventionally, the plate fin arrangement is widely used for removal of dissipated heat but, their effectiveness is not up to mark. Among different options, the most attractive and efficient alternative for overcoming this problem is micro pin fin heat sink. This paper presents the experimental investigation of square micro-pin fins heat sink for identifying the most suitable pin fin geometry for heat removal applications under forced convection. Twenty five square micro pin fin heat sinks were tested for three different heat load and Reynolds number. The results show that for large fin height lower thermal resistance was observed at the cost of large pressure drop. The dimensionless heat transfer coefficient increases with fin height and Reynolds number while it decreases with increasing fin spacing. The improvement in micro pin fin efficiency were observed by about 2 to 9% owing to presence of fins on the impingement surface, flow mixing, disruption of the boundary layers, and augmentation of turbulent transport.
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Kumar, Shailesh Ranjan, i Satyendra Singh. "Thermo-Hydraulic Management System Employing Single-Phase Water Flow through Microchannels with Micro-Inserts Added Aiming for Performance Improvement". Processes 11, nr 6 (20.06.2023): 1858. http://dx.doi.org/10.3390/pr11061858.
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A microchannel heat exchanger effectively evacuates heat from a confined space. This paper attempts to gain insight into the combinatorial repercussions of simultaneously coupling two factors that affect a microchannel’s performance, of which channel size and micro-insert complexity are the two main contributors. With water as the working fluid, an ANSYS-based numerical analysis was carried out for two distinct channel sizes, 1 and 2 mm, both with and without micro-inserts. The Reynolds numbers varied between 125 and 4992 and between 250 and 9985 for the 1 and 2 mm channels, respectively. For the 2 mm diameter channel, adding micro-inserts raised the overall pressure drop with increased Reynolds number. The inclusion of micro-inserts increased the pressure drop in the 1 mm channel at first, and thereafter the pressure drop decreased. Incorporating micro-inserts into the channel resulted in enhanced heat transfer. The trade-off between enhanced heat transfer performance and a larger pressure drop was calculated by evaluating the channel’s overall performance using the thermal performance factor. Micro-inserts were found to be most useful for improving overall performance in the low-to-moderate Reynolds number range, and their effectiveness increased with decreasing channel size. Changing the channel diameter and structure of the design can improve heat transmission through microchannels.
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Nadim Zarizi, Muhammad Amirul, Irnie Azlin Zakaria, Mohamad Noor Izwan Johari, Wan Ahmad Najmi Wan Mohamed i Raja Mazuir Raja Ahsan Shah. "Thermo-Electrical Behavior of Al2O3 and SiO2 Nanofluids in A Proton-Exchange Membrane Fuel Cell (PEMFC) Cooling Channel". Pertanika Journal of Science and Technology 30, nr 2 (28.03.2022): 1381–96. http://dx.doi.org/10.47836/pjst.30.2.29.
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Proton Exchange Membrane Fuel Cell (PEMFC) generates electricity through the reaction of hydrogen and oxygen. PEMFC is considered clean technology since the by-products of the reaction are only electricity, water, and heat. Thermal management of PEMFC can be further improved through the adoption of nanofluids as its cooling medium. Nanofluids are fluids that contain suspensions of nanoparticles in their base fluid. Nanofluids have better heat transfer performance as compared to their base fluid due to their significant thermal conductivity improvement. However, unlike any other heat transfer application, there is a strict limit on the electrical conductivity of the nanofluids due to their electrically active environment. Therefore, there is a possible current leakage to the coolant due to the nanofluids’ conductive behavior. In this study, heat transfer performance and current drop of 0.5% Al2O3 and 0.5% SiO2 water were investigated. The nanofluids were forced to flow in a charged channel subjected to a heater pad of 60°C to 70°C to mimic the operating condition of a PEMFC. The performance of each nanofluid was observed and compared to distilled water. The channel temperature was reduced by 43.3 % and 42.7 % by Al2O3 and SiO2 nanofluids, respectively, compared to base fluids at Re 700. In terms of current drop, SiO2 nanofluids have the highest current drop with 2.33 % from the initial current value. It was further justified with the increment in electrical conductivity value of the fluids after the experiment, thus justifying the current leakage hypothesis.
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Kanematsu, Takeshi, Nobuaki Suzuki, Naomi Sanda, Mika Ogawa, Mayuko Kishimoto, Atsuo Suzuki, Hitoshi Kiyoi, Ryu Kasai i Tadashi Matsushita. "Clinical Course and Management of Surgical Emergency in a Severe Hemophilia a Patient Under Weekly Subcutaneous Administration of a Bispecific Antibody to Factors IXa and X (ACE910)". Blood 126, nr 23 (3.12.2015): 1099. http://dx.doi.org/10.1182/blood.v126.23.1099.1099.
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Abstract Background FVIIIa acts as a cofactor in the intrinsic pathway in which FIXa activates FX. ACE910 is a FIXa/FX-recognizing bispecific antibody that was designed to be a replacement for FVIIIa. Because of its nature, ACE910 is not affected by FVIII inhibitor. A clinical trial is now being conducted for the potential effect in the prophylactic treatment for bleeding hemophilia A patients. Here we present the perioperative care of a patient who had incidentally suffered from appendicitis and underwent an emergency surgery during the clinical trial. Methods Plasma ACE910 concentration and FXIa-triggered thrombin generation assay (TGA) was obtained in the central measurement of the trial. An activated partial thromboplastin time (APTT), and the tissue factor (TF)-triggered TGA were conducted at our laboratory. TF-triggered TGA was performed by means of calibrated automated thrombogram (Thrombinoscope BV), in accordance with the manufacturer's instructions. We used PPP-reagent LOWTM and FluCa-KitTM in Fluoroscan Ascent FLTM (Thermo Fisher Scientific Inc.) and monitored the thrombin generation for 2 hours, set at an excitation wavelength of 390 nm and an emission wavelength of 460 nm, and ThrombinoscopeTM software (Thrombinoscope BV). ROTEM® was performed as manufactured (Tem Innovations GmbH). Case The patient is a 60-year-old man suffering from hemophilia A without inhibitors and had severe hemophilic arthropathy in the number of target joints. Even after biweekly prophylaxis had been introduced by 2000 units of rFVIII concentrates, the annualized bleeding rate remained to be 10.1 In November 2013, ACE910 was introduced by way of subcutaneous administration and the initial dose was 3 mg/kg, followed by weekly administration of 1 mg/kg. After that, he had not had any of joint or soft tissue bleeding. In the 63rd week after the initial administration, he had severe abdominal pain and diagnosed as acute appendicitis that required emergency surgery. His APTT was consistently normal since ACE910 administration, we selected to undergo the surgery without any additional FVIII replacement, although his previous product was set up to be administrated any time on demand. ACE910 had been administered as scheduled earlier on the day of the diagnosis of acute appendicitis, followed by the emergency appendectomy. Results The appendectomy was performed by pararectal incision. Although the patient's appendix was necrosed and perforated, it was easy to stop bleeding during surgery and the total amount of bleeding was only 45 mL. On postoperative day 11, a small amount of bleeding was found after the removal of drainage catheter placed subfascially, however, the bleeding stopped immediately after the bleeding site was sutured. No other issues on bleeding were found. Trough levels of plasma ACE910 concentration were maintained at 27-41 µg/mL during the period between the 12th week after the initiation of ACE910 and the time of preoperative stage. In FXIa-triggered TGA, lag time was remarkably improved after the initiation of ACE910 and remained stable throughout the course of emergency surgery (Table 1). Although peak thrombin levels were slightly decreased a week after surgery, APTT and several In-TEM values by ROTEM® remained at almost normal levels (Table 2). Discussion and Conclusion We successfully conducted the hemostatic management for appendicitis in the perioperative period without any additional administration of FVIII concentrate. The patient showed less bleeding under ACE910 prophylaxis. To date there are little information on appropriate use of FVIII concentrate in patients with acute bleeding or major surgery who are under ACE910 prophylaxis. Generally in bleeding hemophilic patients with major surgery, the loss of clotting factors due to hemodilution by fluid replacement should also be carefully monitored. In such condition, the optimum ACE910 concentration could not be well interpreted, however, the careful monitoring might be required especially in highly invasive surgeries. In our experience, TF-triggered TGA demonstrated a marginal change only between postoperative days 7 and 13, although it is not totally known whether these changes were affected by ACE910 pharmacodynamics. Further researches are needed to explore the suitable biomarkers to indicate hemostasis of hemophilic patients under the administration of ACE910. Disclosures Suzuki: Baxalta: Honoraria; Bayer Healthcare: Honoraria; Novo Nordisk Pharma: Honoraria. Kiyoi:Novartis Pharma K.K.: Research Funding; MSD K.K.: Research Funding; Pfizer Inc.: Research Funding; Takeda Pharmaceutical Co., Ltd.: Research Funding; Yakult Honsha Co.,Ltd.: Research Funding; Alexion Pharmaceuticals: Research Funding; Teijin Ltd.: Research Funding; Taisho Toyama Pharmaceutical Co., Ltd.: Research Funding; Eisai Co., Ltd.: Research Funding; Astellas Pharma Inc.: Consultancy, Research Funding; Japan Blood Products Organization: Research Funding; Nippon Shinyaku Co., Ltd.: Research Funding; FUJIFILM RI Pharma Co.,Ltd.: Research Funding; Nippon Boehringer Ingelheim Co., Ltd.: Research Funding; FUJIFILM Corporation: Patents & Royalties, Research Funding; Zenyaku Kogyo Co., Ltd.: Research Funding; Sumitomo Dainippon Pharma Co., Ltd.: Research Funding; Kyowa Hakko Kirin Co., Ltd.: Consultancy, Research Funding; Bristol-Myers Squibb: Research Funding; Chugai Pharmaceutical Co., Ltd.: Research Funding; Mochida Pharmaceutical Co., Ltd.: Research Funding. Kasai:Chugai Pharmaceutical Co., Ltd.: Employment. Matsushita:Asahi Kasei Pharma: Honoraria, Research Funding, Speakers Bureau; Sysmex: Speakers Bureau; Octapharma AG: Honoraria; Kyowa-Kirin: Honoraria, Research Funding; CLS-Behling: Research Funding; Biogen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Bayer Healthcare: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Seamens: Speakers Bureau; Nihon Pharmaceutical: Honoraria, Research Funding, Speakers Bureau; Kaketsuken: Honoraria, Research Funding, Speakers Bureau; Eisai: Research Funding; Baxalta: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Japan Blood Products Organization: Honoraria, Research Funding; Novartis Pharma: Honoraria, Speakers Bureau; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Novo Nordisk Pharma: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Chugai Pharmaceutical Co., Ltd.: Research Funding.
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Aisien, Felix Aibuedefe, i Eki Tina Aisien. "LIQUID FLUIDS FROM THERMO-CATALYTIC DEGRADATION OF WASTE LOW-DENSITY POLYETHYLENE USING SPENT FCC CATALYST". Detritus, nr 19 (30.06.2022): 75–83. http://dx.doi.org/10.31025/2611-4135/2022.15199.
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ABSTRACT: The widely-used plastics, especially low-density polyethylene (LDPE), have resulted in a considerable accumulation of plastics in the waste stream, causing a global environmental problem. Therefore, the research aims to examine the thermal and catalytic degradation of waste LDPE plastic using spent fluid catalytic cracking (FCC) catalyst and compare the properties of the produced liquid oils with commercial fuels. The potential of converting the most energy from waste plastics to valuable liquid oil, gaseous, and char was investigated. A batch reactor was used to thermally and catalytically degrade LDPE at temperatures 350 to 550oC and catalyst to plastic ratio of 0.10 to 0.25. The physical properties of the produced liquid oils, flash point, pour point, viscosity, API-gravity, carbon residue, density, etc., were determined using standard methods. We characterized the chemical properties of produced pyrolysis liquid oils with Gas chromatography-mass spectrometry (GC-MS). The liquid oil, gas, and char produced at catalyst to plastic ratio of 0.20 at 500oC were 92.7 wt.%, 6.1 wt.%, and 1.2 wt.% respectively. The thermal pyrolysis at 500 oC gave 76.6 wt.%, 20.7 wt.%, and 2.7 wt.% for produced liquid oil, gas, and char, respectively. The GC-MS shows that the produced LDPE liquid oil contains many hydrocarbons from C7-C29. The major hydrocarbons common to LDPE are benzene, 1, 3 dimethyl benzene, and toluene. The produced liquid oil’s properties compare favorably with that of commercial fuels.
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Zhou, Aizhao, Xianwen Huang, Wei Wang, Pengming Jiang i Xinwei Li. "Thermo-Hydraulic Performance of U-Tube Borehole Heat Exchanger with Different Cross-Sections". Sustainability 13, nr 6 (16.03.2021): 3255. http://dx.doi.org/10.3390/su13063255.
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For reducing the initial GSHP investment, the heat transfer efficiency of the borehole heat exchange (BHE) system can be enhanced to reduce the number or depth of drilling. This paper proposes a novel and simple BHE design by changing the cross-sectional shape of the U-tube to increase the heat transfer efficiency of BHEs. Specifically, in this study, we (1) verified the reliability of the three-dimensional numerical model based on the thermal response test (TRT) and (2) compared the inlet and outlet temperatures of the different U-tubes at 48 h under the premise of constant leg distance and fluid area. Referent to the circular tube, the increases in the heat exchange efficiencies of the curved oval tube, flat oval tube, semicircle tube, and sector tube were 13.0%, 19.1%, 9.4%, and 14.8%, respectively. (3) The heat flux heterogeneity of the tubes on the inlet and outlet sides of the BHE, in decreasing order, is flat oval, semicircle, curved oval, sector, and circle shapes. (4) The temperature heterogeneity of the borehole wall in the BHE in decreasing order is circle, sector, curved oval, flat oval, and semicircle shapes. (5) Under the premise of maximum leg distance, referent to the heat resistance of the tube with a circle shape at 48 h, the heat exchange efficiency of the curved oval, flat oval, semicircle, and sector tubes increased 12.6%, 17.7%, 10.3%, and 7.8%, respectively. (6) We found that the adjustments of the leg distance and the tube shape affect the heat resistance by about 25% and 12%, respectively. (7) The flat-oval-shaped tube at the maximum leg distance was found to be the best tube design for BHEs.