bluuebunny/crossref_metadata_2025_split huggingface dataset:
Computed tomography with Hounsfield unit assessment is useful in the diagnosis of liver lobe torsion in pet rabbits (Oryctolagus cuniculus)
Authors: Daggett Alexis , Loeber Samantha , Le Roux Alexandre B. , Beaufrere Hugues , Doss Grayson 
Published: December 2020

AbstractClinical signs of liver lobe torsion in rabbits are often nonspecific and mimic those that are also generally detected with gastrointestinal stasis. Nonspecific clinical signs may result in pursuit of full‐body imaging such as computed tomography (CT). The aim of this multicenter, retrospective, case series study was to describe CT findings of liver lobe torsion in a group of rabbits. Computed tomography studies of six rabbits with confirmed liver lobe torsion by surgery or necropsy were evaluated. The caudate liver lobe was affected in six out of six rabbits and was enlarged, rounded, hypoattenuating, heterogeneous, and minimally to noncontrast enhancing, with scant regional peritoneal effusion. Precontrast, mean Hounsfield units (HU) of the torsed liver lobe (39.3 HU [range, 24.4‐48.1 HU]) were lower than mean HU of normal liver (55.1 HU [range, 49.6‐60.8 HU]), with a mean torsed:normal HU ratio of 0.71 (range, 0.49‐0.91). Postcontrast, mean HU of the torsed liver lobe (38.4 HU [range, 19.7‐48.9 HU]) were also lower than mean HU of normal liver (108.4 HU [range, 84.5‐142.0 HU]), with a lower postcontrast mean torsed:normal HU ratio of 0.35 (range, 0.14‐0.48) compared to precontrast. Mean HU of torsed liver lobes had little difference pre‐ and postcontrast (postcontrast HU 1.0 times the average precontrast HU [range, 0.81‐1.1]), and contrast enhancement of the torsed liver lobes was on average 50% lower than in normal liver. Liver lobe torsion should be considered in rabbits with an enlarged, hypoattenuating, heterogeneous, minimally to noncontrast enhancing liver lobe, particularly the caudate lobe, and scant regional peritoneal effusion.
Sedimentary Dynamic and Composition of a Tidal Channel in a Tropical Hot Semi-Arid Environment, NE Brazil
Authors: Souza Ian Cerdeira de Oliveira , Maia Guilherme Augusto Mendonça , Almeida Narelle Maia de , Abreu Neto João Capistrano , Freire George Satander Sá 
Published: December 2020

Tidal channels comprise a peculiar and dynamic environment. This paper aims to recognize the sedimentary distribution and composition of a tidal channel located in a semi-arid climate area in order to understand the sedimentary dynamics of the region. This region has economic and environmental importance considering that several activities are developed in the area such as; salt industry and aquaculture with shrimp farming. The results and discussion presented here on the Barra Grande Port tidal channel are based on 43 superficial samples distributed in the area, in which we analyzed the grain-size distribution and the calcium carbonate and organic matter contents. The data enabled the characterization and compartmentalization of the tidal channel on five sections and the interpretation of the sedimentary dynamics of the area. The sections present an important variation in the composition and selection. The section 1 is located in supratidal zone while sections 02, 03, 04 and 05 are in intertidal zone. The grain-size mean has a tendency to decrease toward the end of the channel as well as the gravel percentage, and the carbonate and organic matter contents. Differently, the mud content and the sorting increase toward the end of the channel and the skewness becomes more positive. In a general way, the carbonate content is high throughout the tidal channel ranging from 20 to 98% while the organic matter content is low ranging from 0 to 3%. This sedimentary distribution occurs due to the development of a hydraulic dam on section 3, causing a morphological growth of this sand bar, which acts as a natural hydraulic dam, hampering the access of the tide and consequently reducing the effectiveness of the transport, resulting in the deposition of fine sediments in the sheltered areas of the channel (sections 04 and 05). The high temperatures and low rainfall of the tropical hot semi-arid climate allowed the development of carbonate sedimentation as well as the development of anthropic activities such as salt extraction in artificial salt pans which may have influenced the low levels of organic matter.
Direct Radiative Forcing Due to Aerosol Properties at the Peruvian Antarctic Station and Metropolitan Huancayo Area
Authors: Angeles Suazo Julio Miguel , Suarez Salas Luis , Huaman De La Cruz Alex Rubén , Angeles Vasquez Roberto , Rosales Aylas Georgynio , Rocha Condor Alicia , Requena Rojas Edilson , Muñoz Ccuro Felipa , Flores Rojas Jose Luis , Abi Karam Hugo 
Published: December 2020

Descrevemos os resultados do estudo da profundidade ótica do aerossol (POA) e do Forçamento Radiativo Direto (FRD) no topo da atmosfera (TOA), obtidos durante a campanha de medição e monitoramento, XXI Expedição Antártica do Peru, entre os meses de janeiro e fevereiro de 2013, e na área metropolitana de Huancayo (AMH) entre os meses de junho e julho de 2019. Na Estação Antártica Peruana Machu Picchu utilizou-se um fotômetro solar SP02-L. Tal instrumento possui 4 canais: 412 nm, 500 nm, 675 nm e 862 nm, permitindo realizar medições diretas do espectro de radiação visível. Na AMH usamos o sensor BF5, que mede a radiação direta, difusa e global em comprimento de onda curta. Os cálculos de AOD em latitudes polares variaram entre 0,0646 e 0,1061. Na AMH apresenta valor máximo de 0,58 (11 de junho) e mínimo de 0,19 (12 de junho). Determinou-se o coeficiente de Angstrom variando de 0 a 0,07, esses valores indicam a presença de partículas grandes. Na AMH varia de 0 a 1,8, que indica a presença de aerossóis de fonte de queima de biomassa e industrial. As propriedades óticas observadas foram usadas para estimar a forçante radiativa direta por aerossóis (FRDA) no topo da atmosfera. Os resultados indicam que no King George Island, o FRDA, está entre -2 e 4 W/m2; já para a AMH a forçante radiativa direta de aerossol está entre 0 e 20 W/m2.
Maintenance Factors Affecting Increased Lutetium-177 Production
Authors: Danielsson Niklas 
Published: December 2020

Abstract
With lutetium (Lu-177) demand forecasted to increase following the conclusion of clinical trials and product registration in key jurisdictions, manufacturers are seeking to improve their production outputs. Naturally, the question falls to operation and maintenance of these production centers to ensure reliable supply to market. Maintenance in the radiopharmaceutical industry is a complex environment with many competing interactions between radiation safety and good manufacturing practice (GMP) requirements. With the view of doubling lutetium production by the end of 2020 and plans for continued increases over the coming years, a key question was whether the plant reliability could accommodate this increase sustainably. As plant use increases the potential frequency of failure as well as the impact of outages increases, it results in a general increase in risk. Since its development by the aviation industry in 1960s, the reliability centered maintenance (RCM) concept has seen adoption by many industries. The International Atomic Energy Agency (IAEA) developed a technical document on RCM applications in nuclear industry in May 2007 while the International Society of Pharmaceutical Engineers (ISPE) refers to the concept in their own baseline guides as well as other risk-based methods in line with international standards. Blame for reliability issues often falls at the feet of the equipment design with suggestions that wholesale redesign of equipment will solve reliability issues. Careful review of existing strategies against these baseline guidelines tells a different story with clear gaps between existing maintenance strategies and current best practice. This document details the results of that investigation, providing information on the gaps found and the systems implemented to bring maintenance strategies back in alignment with current best practice. The article also offers commentary on situations requiring compromises between those best practices defined by IAEA and ISPE.
Impact of the Stabilized Finite Element Method on Acoustic and Vortical Perturbations in Thermoacoustic Systems
Authors: Hofmeister Thomas , Hummel Tobias , Sattelmayer Thomas 
Published: December 2020

Abstract
This paper seeks to advance linear stability analyses of thermoacoustic systems conducted with the stabilized finite element method (sFEM). Specifically, this work analyzes and quantifies the impact of the streamline-upwind-Petrov–Galerkin (SUPG) artificial diffusion scheme on (eigen)mode shapes and damping rates of the isentropic linearized Euler equations (LEEs) in frequency space. The LEE (eigen)mode shapes are separated into acoustic and vortical perturbation components via a Helmholtz decomposition and their sensitivity on the employed stabilization scheme is investigated separately. The regions where numerical stabilization mainly acts on the perturbation types are identified and explanations for the observations are provided. A methodology is established, which allows the quantification of the impact of artificial diffusion on the acoustic field in terms of a damping rate. This nonphysical damping rate is used to determine the physically meaningful, acoustic LEE damping rate, which is corrected by the contribution of artificial diffusion. Hence, the presented method eliminates a main shortcoming of LEE eigenfrequency analyses with the sFEM and, as a result, provides more accurate information on the stability of thermoacoustic systems.
A High-Fidelity Modeling Tool to Support the Design of Oxy-Combustors for Direct-Fired Supercritical CO2 Cycles
Authors: Zambon Andrea C. , Hosangadi Ashvin , Weathers Tim , Winquist Mark , Mays Jeff , Miyata Shinjiro , Subbaraman Ganesan 
Published: December 2020

Abstract
The challenge in the design of oxy-combustors for direct-fired supercritical CO2 (sCO2) cycles is in addressing disparate performance metrics and objectives. Key design parameters to consider include, among others, injector design for mixing and flame stability, split of recycled CO2 diluent between injectors and cooling films, target flame temperatures to control noncondensable products, and strategies to inject the diluent CO2 for film cooling and thermal control. In order to support novel oxy-combustor designs, a high-fidelity yet numerically efficient modeling framework based on the CRUNCH CFD® flow solver is presented, featuring key physics-based submodels relevant in this regime. For computational efficiency in modeling large kinetic sets, a flamelet/progress variable (FPV) based tabulated-chemistry approach is utilized featuring a three-stream extension to allow for the simulation of the CO2 film cooling stream in addition to the fuel and oxidizer streams. Finite rate chemistry effects are modeled in terms of multiple progress variables for the primary flame as well as for slower-evolving chemical species such as NOx and SOx contaminants. Real fluid effects are modeled using advanced equations of states. The predictive capabilities of this computationally tractable design support tool are demonstrated on a conceptual injector design for an oxy-combustor operating near 30 MPa. Simulations results provide quantitative feedback on the effectiveness of the film cooling as well as the level of contaminants (CO, NO, and N) in the exhaust due to impurities entering from the injectors. These results indicate that this framework would be a useful tool for refining and optimizing the oxy-combustor designs as well as risk mitigation analyses.
The Impact of Exceptional Points on the Reliability of Thermoacoustic Stability Analysis
Authors: Schaefer Felicitas , Guo Shuai , Polifke Wolfgang 
Published: December 2020

Abstract
Exceptional points can be found for specific sets of parameters in thermoacoustic systems. At an exceptional point, two eigenvalues and their corresponding eigenfunctions coalesce. Given that the sensitivity of these eigenvalues to parameter changes becomes infinite at the exceptional point, their occurrence may greatly affect the outcome and reliability of numerical stability analysis. We propose a new method to identify exceptional points in thermoacoustic systems. By iteratively updating the system parameters, two initially selected eigenvalues are shifted toward each other, ultimately colliding and generating the exceptional point. Using this algorithm, we were able to identify for the first time a physically meaningful exceptional point with positive growth rate in a thermoacoustic model. Furthermore, our analysis goes beyond previous studies inasmuch as we employ a more realistic flame transfer function to model flame dynamics. Building on these results, we analyze the effect of exceptional points on the reliability of thermoacoustic stability analysis. In the context of uncertainty quantification, we show that surrogate modeling is not reliable in the vicinity of an exceptional point, even when large sets of training samples are provided. The impact of exceptional points on the propagation of input uncertainties is demonstrated via Monte Carlo computations. The increased sensitivity associated with the exceptional point results in large variances for eigenvalue predictions, which needs to be taken into account for reliable stability analysis.
A Model Reduction Method for Bladed Disks With Large Geometric Mistuning Using a Partially Reduced Intermediate System Model
Authors: Schwerdt Lukas , Panning-von Scheidt Lars , Wallaschek Jörg 
Published: December 2020

Abstract
Reduced order models (ROMs) are widely used to enable efficient simulation of mistuned bladed disks. ROMs based on projecting the system dynamics into a subspace spanned by the modes of the tuned structure work well for small amounts of mistuning. When presented with large mistuning, including changes of geometry and number of finite element mesh nodes, advanced methods such as the pristine-rogue-interface modal expansion (PRIME) are necessary. PRIME builds a reduced model from two full cyclic symmetric analyses, one for the nominal and one for the modified type of sector. In this paper, a new reduced order model suitable for large mistuning with arbitrary mesh modifications is presented. It achieves higher accuracy than PRIME, while saving approximately 25% computational effort during the reduction process, when using the same number of cyclic modes. The new method gains its efficiency by recognizing that large modifications from damage or repair are unlikely to be exactly the same for multiple blades. It works by building a partially reduced intermediate model: All nominal sectors are reduced using cyclic modes of the tuned structure. The single modified sector is kept as the full model. For this reason, the new reduction method is called partially reduced intermediate system model (PRISM) method. The accuracy of the PRISM method is demonstrated on an axial compressor blisk and an academic blisk geometry.
Generation of Surfaces With Isotropic and Anisotropic Wetting Properties by Curved Water Jet-Guided Laser Micromachining
Authors: Shi Yi , Cao Jian , Ehmann Kornel F. 
Published: December 2020

Abstract
This experimental work utilizes a newly developed method, curved water jet-guided laser micromachining, to generate microfeatures on metallic surfaces. During the process, material is removed by a high-power nanosecond laser beam, which is transmitted through a high-pressure microwater jet via total internal reflection. To achieve intricate texturing patterns, a secondary motion component is superimposed on the XY motion of the workpiece provided by the motion stage. The secondary motion is generated by deflecting the water jet trajectory by a controllable dielectrophoretic force. The induced secondary motion of the water jet cuts the processing time to one half when generating texture patterns for isotropic wetting as compared to processes with only XY motion. The ability to alter the water jet's trajectory by tens of microns at high frequencies, which is beyond the capability of conventional CNC machines, allows a wide range of different micropatterns to be generated, profoundly increasing the flexibility and efficiency of the process as compared to conventional approaches. As a demonstration, surface textures for isotropic and anisotropic behaviors are generated on stainless steel surfaces. The influence of feature spacing, motion speed (frequency), and texturing patterns on surface wettability is studied.
Energy Consideration in the Microextrusion of Aluminum Alloy 6063
Authors: Sucharitpwatskul Sedthawatt , Mahayotsanun Numpon , Bureerat Sujin , Dohda Kuniaki 
Published: December 2020

Abstract
This paper investigated key factors influencing energy consumption in the microextrusion process. The considered factors were: extrusion ratio (ER), die angle (α), billet length (BL), bearing length (LB), coefficient of friction (COF), and die shift (DS). The finite element simulation was carried out to determine the extrusion energy required to complete one extrusion cycle. The simulation results showed that the increased values of all the considered factors (except the die shift) led to increased extrusion energy. The results also provided percentages of energy variation in steps, which helped evaluate the energy savings with regards to the crucial other production considerations. The percentage increase in energy consumption in the lower ER values was considered higher than those of, the higher ER values. Increasing die angle (α) from 60 to 90 deg barely affected the consumed energy. The highest increase percentage of extrusion energy was found while increasing billet lengths (BL) from 3.00 mm to 4.00 mm. The lower bearing length (LB) values offered lower consumed energy. The consumed extrusion energy linearly increased with COF. The die shift (DS) did not affect the extrusion energy, but the final part geometry (curved pins). The results and analysis from this study could be used to potential energy savings and overall production costs of the microextrusion process.
A Study on Micromilling Process of Multidirectional Carbon Fiber Reinforced Plastic Composite Using Nano-Solid Dry Lubrication
Authors: Kim Jin Woo , Nam Jungsoo , Lee Sang Won 
Published: December 2020

Abstract
In this research, the micromilling process using nano-solid dry lubrication is studied for machining multidirectional carbon fiber reinforced plastic (MD-CFRP). For this lubrication, two kinds of graphene nanoplatelets and multiwall carbon nanotubes are used as nanoparticles. The workpiece is an MD-CFRP composite in which 10 plies of prepreg are laminated, and it consists of four carbon fiber orientations—0 deg, 45 deg, 90 deg, and 135 deg. The micromilling experiments are conducted, and the workpiece surface quality and tool wear are investigated. As a result, it is confirmed that the nano-solid dry lubrication can improve the surface quality and reduce the tool wear. In particular, larger graphene nanoplatelets (xGnP H-5) are more advantageous than smaller graphene nanoplatelets (xGnP C-750). In addition, multiwall carbon nanotubes having a tube-shape structure are less effective than graphene nanoplatelets having a two-dimensional thin sheet shape for enhancing the micromilling performances, which may be due to better lubrication effect with the graphene nanoplatelets' sliding phenomenon at the cutting region.
Guaranteeing String Stability of Multiple Interconnected Vehicles Using Heterogeneous Controllers
Authors: Farnam A. , Crevecoeur G. 
Published: December 2020

Abstract
In this paper, the issue of string stability for acceleration-controlled vehicles interconnected in a chain is studied. String stability is concerned with having bounded displacements between vehicles in such a way that displacements should not grow unboundedly with respect to the perturbation. Different definitions can be given to string stability: one that relates to the amplification of a local disturbance acting on one vehicle toward the whole vehicle chain, more strict definition that is related to the boundedness of vector norm of displacements with respect to the bounded vector norm of disturbance inputs acting on all vehicles; and, most practical definition that considers the boundedness of signal norm of each individual displacement with respect to the bounded signal norm of disturbance inputs acting on all vehicles, independently from the number of vehicles. It has been proven that these definitions are all impossible to be achieved using any linear homogeneous unidirectional distributed controllers with constant spacing policy. This paper proposes linear heterogeneous controllers where each vehicle behaves differently from others in a vehicle chain. We prove that three different definitions of string stability can be attained using the proposed heterogeneous controller. We propose sufficient conditions to guarantee string stability and boundedness of acceleration of each vehicle. Finally, simulation results are given to illustrate the effectiveness of proposed heterogeneous control synthesis.
Description of Unsteady Flow Characteristics in a Side Channel Pump With a Convex Blade
Authors: Zhang Fan , Chen Ke , Appiah Desmond , Yuan Shouqi , Adu-Poku Kofi Asamoah , Hong Feng 
Published: December 2020

Abstract
To investigate the unsteady flow characteristics in side channel pumps, the vortex structures and their evolutions in the impeller and side channel flow passages have been comprehensively studied. Systematically, three impeller schemes were designed with different ratios of convex blade height h to impeller blade length l (h/l = 0.2, 0.5, and 0.8) for detailed analysis. The findings indicated that the convex blade broadens the high-efficiency range and improves the efficiency at the best efficiency point (BEP) for scheme h/l = 0.2. Impeller scheme h/l = 0.2 records the highest vortex concentration region, scheme h/l = 0.5 displays as scattered spots, while scheme h/l = 0.8 exhibits significant flow pattern changes in the impeller. The vortex distribution area and vortex intensity in the lengthways between the impeller and side channel of h/I = 0.2 are almost analogous, but the other two impeller schemes have obvious separation and very chaotic. Although the shrinkages of axial vortexes in the impeller did not reflect on hydraulic performance, impeller schemes h/l = 0.5 and 0.8 provided an outstanding performance in reducing the pressure fluctuations. The objective of this study is to provide a theoretical basis for optimal design and analysis of strong vortex flows in side channel pumps.
Numerical Study of Supersonic Mixed Compression Air Intake With an Array of Air Jets
Authors: Gahlot N. K. , Singh N. K. 
Published: December 2020

Abstract
Computational study of flow physics inside the mixed compression air intake has been carried out with and without air jets (AJs) at design Mach number of 2.2. Reynolds-averaged Navier–Stokes (RANS) equations were solved with k–ω turbulence model by using commercially available software ansys. The scope of this research is to improve the flow field inside the air intake and efficiency of supersonic air intake by implementing AJs on the ramp surface. An array of AJs containing two, four, and five AJ holes, respectively, of 1 mm each has been made on the ramp surface perpendicular to the flow with equal spacing between them. The injection pressure through AJ has been kept constant for all the cases. Flow distortion (FD) and total pressure recovery (TPR) were selected to measure the performance of air intake. All the simulations have been performed at a back-pressure ratio of 6. The results obtained suggest that implementation of proper spacing between AJs can improve the performance of air intake due to the mixing of vortices generated by AJs with freestream flow. It is revealed that an array of AJs containing four holes on ramp surface works best and helps in controlling the shock-induced separation.