bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multi-Dimensional Modeling of the CFR Engine for the Investigation of SI Natural Gas Combustion and Controlled End-Gas Autoignition
Authors: Bestel Diego , Bayliff Scott , Marchese Anthony , Olsen Daniel , Windom Bret , Xu Hui 
Published: December 2020

Abstract
Engine knock and misfire are barriers to pathways leading to high-efficiency Spark-Ignited (SI) Natural Gas engines. The general tendency to knock is highly dependent on engine operating conditions and the fuel reactivity. The problem is further complicated by low emission limits and the wide range of chemical reactivity in pipeline quality natural gas. Depending on the region and the source of the natural gas, its reactivity, described by its methane number (analogous to the octane number for liquid SI fuels) can span from 65–95. In order to realize diesel-like efficiencies, SI natural gas engines must be designed to operate at high BMEP near knock limits over a wide range of fuel reactivity. This requires a deep understanding regarding the combustion-engine interactions pertaining to flame propagation and end-gas autoignition (EGAI). However, EGAI, if controlled, provides an opportunity to increase SI natural gas engine efficiency by increasing combustion rate and the total burned fuel, mitigating the effects of the slow flame speeds of natural gas fuels which generally reduce BMEP and increase unburned hydrocarbon emissions. For this reason, in order to study EGAI phenomenon, the present work highlights multi-dimensional computational fluid dynamics (CFD) models of the Cooperative Fuel Research (CFR) engine. The CFR engine models are used to investigate fuel-engine interactions that lead to EGAI with natural gas, including effects of fuel reactivity, engine operating parameters, and exhaust gas recirculation (EGR). A Three-Pressure Analysis, performed with GT-Power, was used to estimate initial and boundary conditions for the three-dimensional CFD model. CONVERGE CFD v2.4 was used for the three-dimensional CFD modeling where the level set G-Equation model and SAGE detailed chemical kinetics solver were used. An assessment of the different modeling approaches is also provided to evaluate their limitations, advantages and disadvantages, and for which situations they are most applicable. Model validation was performed with experimental data taken with a CFR engine over varying compression ratio, CA50, EGR fraction, and IMEP and shows good agreement in Peak Cylinder Pressure (PCP), PCP crank angle, and the location of the 10%, 50%, and 90% mass fraction burned (CA10, CA50, and CA90, respectively). The models can predict the onset crank angle and pressure rise rate for light, medium, and heavy EGAI under a variety of fuel reactivities and engine operating conditions.
Cavitation-Suppressing Orifice Design Applied to a Heavy-Duty Diesel Engine Injector Operating With Gasoline
Authors: Torelli Roberto , Pei Yuanjiang , Zhang Yu , Traver Michael , Som Sibendu 
Published: December 2020

Abstract
Measurements of fuel injectors via non-destructive X-ray techniques can provide unique insights about an injector’s internal surface. Using real measured geometry rather than nominal design geometry in computational fluid dynamics simulations can improve the accuracy of the numerical models dramatically. Recent work from the authors investigated the influence of the injector design on the internal flow development and occurrence of cavitation in a production multi-hole heavy-duty diesel injector operating with a straight-run gasoline for gasoline compression ignition (GCI) applications. This was achieved by evaluating a series of design parameters which showed that the intensity and duration of cavitation structures could be mitigated by acting on certain injector parameters such as K-factor, orifice inlet ellipticity, and sac-to-orifice radius of curvature. In the present work, the findings from the previous parametric study were combined to generate two attempts at improving the injector design and numerically evaluate their ability to suppress cavitation inside the orifices at three levels of injection pressure (1000, 1500, and 2500 bar), while operating with the same high-volatility gasoline fuel. Qualitative and quantitative analyses showed that, compared to the results obtained with the original X-ray scanned geometry, the improved designs were able to prevent fuel vapor formation at the two lowest injection pressures and avoid super-cavitation at the higher pressure. It was shown that these results were due to the strong influence that the orifice shape can have on the pressure and fuel vapor volume fraction distributions within the orifices. The informed design choices proposed in this study can therefore be vital for extending the durability and reliability of heavy-duty injectors for GCI applications.
Numerical Investigation of Pre-Chamber Jet Combustion in a Light-Duty Gasoline Engine
Authors: Zhang Anqi , Yu Xin , Engineer Nayan , Zhang Yu , Pei Yuanjiang 
Published: December 2020

Abstract
Open-cycle engine simulations of a passive pre-chamber operating inside a direct-injected gasoline engine are performed and analyzed in this study. A comprehensive three-dimensional computational fluid dynamics (CFD) model has been formulated with state-of-the-art physical sub-models to account for the complex processes of engine gas exchange, fuel injection and mixing, ignition, and combustion. Numerical results are validated against experimental measurements under low load condition with high internal EGR. Realistic modeling considerations are discussed to ensure proper fidelity. In particular, the mixture conditions and flow motions could present very different features between the pre- and main chamber, which requires comprehensive simulation of the full engine cycle and imposes challenges for combustion modeling. Practically validated chemical kinetics models are essential for proper prediction of cylinder pressure history of pre-chamber jet combustion systems. Detailed analysis is then carried out to highlight key processes associated with pre-chamber operation, including residual scavenging, fuel/air mixture formation, flow pattern and turbulence development within the pre-chamber, and the ignition of main chamber mixture by issued turbulent jets. Numerical evaluation of pre-chamber design variants has been attempted, and less commonly investigated geometry parameters such as swirl nozzles and nozzle umbrella angle are found impactful for pre-chamber ignition performances.
Factors associated with calendar literacy and last menstrual period (LMP) recall: a prospective programmatic implication to maternal health in Bangladesh
Authors: Sarker Bidhan Krishna , Rahman Musfikur , Rahman Tanjina , Rahman Tawhidur , Rahman Fariya , Khalil Jubaida Jahan , Hasan Mehedi , Mahfuz Sadia Nishat , Ahmmed Faisal , Miah Muhammad Salim , Ahmed Anisuddin , Mitra Dipak , Mridha Malay Kanti , Rahman Anisur 
Published: December 2020

ObjectiveTo explore the prevalence and determinants of calendar literacy and last menstrual period (LMP) recall among women in Bangladesh.DesignCross-sectional survey.SettingsTwo rural subdistricts and one urban area from three Northern districts of Bangladesh.ParticipantsWe interviewed 2731 women who had a live birth in the last 1 year.Primary and secondary outcome measuresThe primary outcome variable was LMP recall and the secondary outcome was calendar literacy.ResultsThe majority of participants (65%) correctly mentioned the current date according to the English calendar while 12% mentioned according to the Bengali calendar. During the interview sessions, we used three different calendars: Bengali, English and Hijri to assess calendar literacy. We asked women to mark the current date using the calendar on the day of the interview. Almost 61% women marked the English calendar, 16% marked the Bengali calendar and 4% marked the Hijri calendar correctly. Sixty-three per cent women were found as calendar literate who marked any of the calendars. Among the participants, 58% had calendars available at their home and only 10% of women used calendars to track their LMPs. Overall, 53% women were able to recall their recent LMP. Among the calendar literate, 60% could recall their LMPs. Factors found associated with recalling LMP were: completed eight or more years of schooling (adj.OR 1.39), primigravida (adj.OR 1.88), the richest wealth quintile (adj.OR 1.55) and calendar literacy (adj.OR 1.59).ConclusionsDespite having reasonable calendar literacy and availability, the use of calendars for tracking LMP found very low. Calendar literacy and sociodemographic characteristics were found as the key factors associated with LMP recall. Maternal, neonatal and child health programmes in low-resource settings can promote a simple tool like calendar and target the communities where ultrasound is not available to ensure accurate LMP recall for early pregnancy registration and timely antenatal care coverage.
Psychometric properties and construct validity of PLAYself: a self-reported measure of physical literacy for children and youth
Authors: Jefferies Philip , Bremer Emily , Kozera Tanya , Cairney John , Kriellaars Dean 
Published: December 2020

PLAYself is a tool designed for self-description of physical literacy in children and youth. We examined the tool using both the Rasch model and Classical Test Theory to explore its psychometric properties. A random selection of 300 children aged 8–14 years (47.3% female) from a dataset of 8513 Canadian children were involved in the Rasch analysis. The 3 subscales of the measure demonstrated good fit to the Rasch model, satisfying requirements of unidimensionality, having good fit statistics (item and person fit residuals = –0.17–1.47) and internal reliability (Person Separation Index = 0.70–0.82), and a lack of item bias and problematic local dependency. In a separate comparable sample, 297 children also aged 8–14 years (53.9% female) completed the PLAYfun, Physical Self-Description Questionnaire (PSDQ), Physical Activities Measure-Revised (MPAM-R), a physical activity inventory (PLAYinventory), and repeated the PLAYself 7 days later. The tests with this sample confirmed test–retest reliability (intraclass correlation coefficient = 0.81–0.84), and convergent and construct validity consistent with contemporary physical literacy definitions. Overall, the PLAYself demonstrated robust psychometric properties, and is recommended for researchers and practitioners who are interested in assessing self-reported physical literacy. Novelty: The PLAYself is a self-reported measure of physical literacy This study validates the measure using the Rasch model and classical test theory The PLAYself was found to have strong psychometric properties
Square–torsion gravity, dark matter halos and the baryonic Tully–Fisher relation
Authors: Mégier Elias A. S. 
Published: December 2020

AbstractSquare–torsion gravity is applied to the long standing dark matter problem. In this context the theory reduces to General Relativity complemented by a dark stress–energy tensor due to the torsion of spacetime and is studied under the simplifying assumption of spherical symmetry. The dark stress–energy tensor satisfies an anisotropic structure equation. In vacuum this is equivalent to a wave equation with sources. A natural class of exact solutions is found which explicitly perturbs any seed spacetime metric by a conformal factor. This leads to the concept of dark coating. Static solutions are then used to construct structures that model dark matter halos surrounding baryonic bodies. In the Newtonian régime the baryonic mass $$m_b$$

m
b

and the flat rotation curve velocity $$v_f$$

v
f

are related by the baryonic Tully–Fisher relation$$m_b\propto v_f^4$$

m
b

∝

v
f
4

, a hitherto purely empirical result. The example of a dark halo on the Schwarzschild geometry is made as a toy model for a galaxy. Qualitative an quantitative features of galactic rotation curves are recovered. In this setting, a boundary of staticity is found, called torsion sphere, placed between the photon sphere and the event horizon. The phenomenon of dark radiation is briefly exposed.
Running of effective dimension and cosmological entropy in early universe
Authors: Xiao Yong 
Published: December 2020

AbstractIn this paper, we suggest that the early universe starts from a high-energetic state with a two dimensional description and the state recovers to be four dimensional when the universe evolves into the radiation dominated phase. This scenario is consistent with the recent viewpoint that quantum gravity should be effectively two dimensional in the ultraviolet and recovers to be four dimensional in the infrared. A relationship has been established between the running of effective dimension and that of the entropy inside particle horizon of the universe, i.e., as the effective dimension runs from two to four, the corresponding entropy runs from the holographic entropy to the normal entropy appropriate to radiation. These results can be generalized to higher dimensional cases.
$$T\bar{T}$$ deformation of chiral bosons and Chern–Simons $$\hbox {AdS}_3$$ gravity
Authors: Ouyang Hao , Shu Hongfei 
Published: December 2020

AbstractWe study the $$T\bar{T}$$

T

T

¯

deformation of the chiral bosons and show the equivalence between the chiral bosons of opposite chiralities and the scalar fields at the Hamiltonian level under the deformation. We also derive the deformed Lagrangian of more generic theories which contain an arbitrary number of chiral bosons to all orders. By using these results, we derive the $$T\bar{T}$$

T

T

¯

deformed boundary action of the $$\hbox {AdS}_3$$

AdS
3

gravity theory in the Chern–Simons formulation. We compute the deformed one-loop torus partition function, which satisfies the $$T\bar{T}$$

T

T

¯

flow equation up to the one-loop order. Finally, we calculate the deformed stress–energy tensor of a solution describing a BTZ black hole in the boundary theory, which coincides with the boundary stress–energy tensor derived from the BTZ black hole with a finite cutoff.
Thermodynamics of spherically symmetric black holes in scale-dependent gravity
Authors: Bargueño P. , Miralles J. A. , Pons J. A. 
Published: December 2020

AbstractIn this work we extend the first law of thermodynamics to spherically symmetric black hole solutions in the context of scale-dependent gravity. After deriving generalized expressions for both the entropy and energy due to the spatial variation of the gravitational constant we analize, by pointing out some relations between scale-dependent andf(R) theories, whether or not the former can be described using equilibrium thermodynamics.
Weather derivatives for managing weather and climate risk in agriculture
Authors: Gyamerah Samuel Asante , Ngare Philip , Ikpe Dennis 
Published: December 2020

In this paper, we develop a pricing model for weather derivatives at a single location and multiple locations. In the first model, a Lévy regime-switching temperature model for a single location is used to price futures written on cumulative average temperature and growing degree-days indices at a single location. To allow analytical pricing for futures on temperature basket, an [Formula: see text]-dimension regime-switching temperature model whose driving noise is captured by a Brownian motion is developed. The correlation between the driving noise in each regime is assumed to be a function of the space between the different farming locations and increases with decreasing space. The temperature basket index assigns a weight to each location that is exposed to risk. However, a location with a higher risk is assigned a larger weight and vice versa. By assuming that the regimes are independent to each other, the future is calculated for each regime model. The final futures price is calculated using the weighted sum of the individual regimes. These pricing models can be applied in the future markets to price weather derivatives for the agricultural sector. Research on spatial-temporal pricing model is vital to the development of the weather derivatives market, as investors are more vulnerable to temperature risk over different farming locations as compared to single location.
Ectoparasite insects of bats from the fields and weedlands eco-region of Argentina
Authors: Autino Analía Gladys , Idoeta Fabricio Miguel , Claps Guillermo Luis , Barquez Rubén Marcos 
Published: December 2020

New information is presented for bats and their ectoparasite insects from the Argentine Field and Weedlands Ecoregion. Bats of the families Molossidae, Phyllostomidae and Vespertilionidae containing ectoparasites belonging to families Polyctenidae (Hemiptera), Nycteribiidae and Streblidae (Diptera) were collected. Here is presented the first record of Hesperoctenes cartus Jordan, 1922 for Argentina. Basilia plaumanni Scott, 1940 and H. vicinus Jordan, 1922 are added to the province of Misiones and Paratrichobius longicrus (Miranda Ribeiro, 1907) is added to the province of Corrientes. Additionally, the distributions of some ectoparasite insects are extended and new host-ectoparasite associations are reported.
A new species of Brethesiamyia Maia (Diptera: Cecidomyiidae) from Colombia with description of immature forms
Authors: Ospina-Peñuela Esau Adenawer , Lamas Carlos José Einicker , Serna Francisco , Urso-Guimarães Maria Virginia 
Published: December 2020

A new species of Brethesiamyia (Diptera: Cecidomyiidae) is described from Colombia, which represents the first record of the genus for the country. We described the species based on male, female, pupa, larva of third instar and gall morphology, which the larva induces on leaves of Myrcia sp. (Myrtaceae) from the foothills situated at the connection of the Andes and the Amazon basin from Colombia. The first description of the third larval instar is provided for the genus.
Segregação socioespacial e o "Direito à Cidade"
Authors: Carlos Ana Fani Alessandri 
Published: December 2020

As ideias contidas neste artigo se desdobram da hipótese segundo a qual a propriedade privada da riqueza, em sua várias formas, está no fundamento da produção do espaço urbano. A propriedade aparece, neste momento do processo histórico, como abstrata. Nesta condição a propriedade domina as relações sociais que se realizam, concretamente, num espaço marcado pela segregação e vivida como a negação da cidade. Esses elementos iluminam as lutas entorno do direto à cidade.
“A História Literária e a Sociologia” – Gustave Lanson
Authors: Anjos Yuri Cerqueira dos 
Published: December 2020

Nesta conferência intitulada “A História Literária e a Sociologia”, proferida na École des Hautes Études Sociales em 29 de janeiro de 1904, Gustave Lanson (1857-1934) aborda uma miríade de temas que marcaram sua visão pioneira acerca da história da literatura: da relação entre indivíduo e contexto social à literatura como parte de um sistema de comunicação, passando pela questão da recepção. As análises propostas neste texto se configuram como um germe de importantes discussões futuras no campo dos estudos literários não só no contexto francês. Esta tradução inédita para o português baseou-se na versão deste texto publicada na Revue de Métaphysique et de Morale (1904).
Anaesthetic, clinical, morphometric, haematological, and serum chemistry evaluations of an Andean Cat Leopardus jacobita (Cornalia, 1865) (Mammalia: Carnivora: Felidae) before release in Bolivia
Authors: Beltrán-Saavedra L. Fabián , Limachi Quiñajo Rolando , Ledezma Grace , Morales-Moreno Daniela , Villalba M. Lilian 
Published: December 2020

The Andean Cat Leopardus jacobita, one of the most rare and endangered feline species in the world, is distributed from central Peru to central Argentina. The aim of this study was to evaluate the health and morphometry of a subadult male Andean Cat that was rescued from wildlife trade in Bolivia and held captive for 165 days before being released back into its natural habitat. Physical immobilizations followed by anaesthesia using ketamine hydrochloride (KH) and xylazine hydrochloride (XH) were performed to obtain clinical, morphometric, haematological and serum chemical parameters. Physical immobilizations were efficient using capture nets. The combination of KH + XH had an average initial sedation effect within 12min with a range of 10–16 min after intramuscular application. Anaesthetic average plane lasted 41.7min with a range of 40–45 min and was extended to 64.5min (63–66 min range) with an addition of KH. The individual was underweight on arrival and gradually reached an ideal condition and was overweight before its release. Morphometry parameters showed that it grew during the captive period. It was released back into the wild when it was considered healthy. This is the first report of a protocol of physical and chemical immobilization, physiological values, and biometric variation of an Andean Cat under captive conditions.
Angiotensin‐Converting Enzyme Inhibitors or Angiotensin Receptor Blockers Use and COVID‐19 Infection Among 824 650 Patients With Hypertension From a US Integrated Healthcare System
Authors: An Jaejin , Wei Rong , Zhou Hui , Luong Tiffany Q. , Gould Michael K. , Mefford Matthew T. , Harrison Teresa N. , Creekmur Beth , Lee Ming‐Sum , Sim John J. , Brettler Jeffrey W. , Martin John P. , Ong‐Su Angeline L. , Reynolds Kristi 
Published: December 2020

Background
Previous reports suggest that the use of angiotensin‐converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs) may upregulate angiotensin‐converting enzyme 2 receptors and increase severe acute respiratory syndrome coronavirus 2 infectivity. We evaluated the association between ACEI or ARB use and coronavirus disease 2019 (COVID‐19) infection among patients with hypertension.

Methods and Results

We identified patients with hypertension as of March 1, 2020 (index date) from Kaiser Permanente Southern California. Patients who received ACEIs, ARBs, calcium channel blockers, beta blockers, thiazide diuretics (TD), or no therapy were identified using outpatient pharmacy data covering the index date. Outcome of interest was a positive reverse transcription polymerase chain reaction test for COVID‐19 between March 1 and May 6, 2020. Patient sociodemographic and clinical characteristics were identified within 1 year preindex date. Among 824 650 patients with hypertension, 16 898 (2.0%) were tested for COVID‐19. Of those tested, 1794 (10.6%) had a positive result. Overall, exposure to ACEIs or ARBs was not statistically significantly associated with COVID‐19 infection after propensity score adjustment (odds ratio [OR], 1.06; 95% CI, 0.90–1.25) for ACEIs versus calcium channel blockers/beta blockers/TD; OR, 1.10; 95% CI, 0.91–1.31 for ARBs versus calcium channel blockers/beta blockers/TD). The associations between ACEI use and COVID‐19 infection varied in different age groups (
P
‐interaction=0.03). ACEI use was associated with lower odds of COVID‐19 among those aged ≥85 years (OR, 0.30; 95% CI, 0.12–0.77). Use of no antihypertensive medication was significantly associated with increased odds of COVID‐19 infection compared with calcium channel blockers/beta blockers/TD (OR, 1.32; 95% CI, 1.11–1.56).

Conclusions
Neither ACEI nor ARB use was associated with increased likelihood of COVID‐19 infection. Decreased odds of COVID‐19 infection among adults ≥85 years using ACEIs warrants further investigation.