bluuebunny/crossref_metadata_2025 huggingface dataset:
Towards Onboard Li-ion Battery State-of-health Diagnosis by a Virtual Sensor
Authors: Mingant Rémy , Bernard Julien , Sauvant-Moynot Valérie
Published: May 2018

The development of improved State-of-Health (SoH) diagnosis methods is a current research topic for battery-powered applications. For instance, Hybrid Electric Vehicles (HEV) are in rapid extension and create a strong demand for an accurate and reliable SoH indicator during operation. Such an indicator is a key parameter required to optimize battery energy management and to track the degradation of the system performances. Electrochemical impedance spectroscopy is one of the most promising methods for characterizing ageing effects of secondary batteries online because it can be sensitive to different ageing mechanisms. This paper presents a method to measure the electrochemical transfer function of the cell at different frequencies simultaneously with the data treatment of free current and voltage during operation. Impedance parameters were then estimated by a non linear least square algorithm. Based on this approach, an experimental investigation of ageing effects of a lithium ion battery was carried out. After 1400 HEV cycles, the battery showed a 7 % decreased capacity, and 8 % increased resistance at 0.5 Hz. Modelling results show that charge transfer resistance have a similar evolution in function of ageing time than the resistance of battery measured by electrochemical impedance spectroscopy. To our knowledge on the topic, this constitutes a substantial step towards SoH indicator that could be reliable and precise enough under realistic user conditions.
Voltage Stability and System Behavior of Cybernetic Loads in Vehicular Power Nets
Authors: Kohler Tom , Willems Niklas , Froeschl Joachim , Thanheiser Andreas , Buecherl Dominik , Herzog Hans-Georg
Published: May 2018

Voltage stability has to be ensured within automotive power buses in order to reliably supply all components with sufficient energy. Especially in modern vehicles (conventional, hybrid electric, or electric), the stability is endangered due to electric loads with high dynamics, for example chassis control systems. In this paper, a power distribution management based on cybernetic principles is described. To manage the power flow efficiently, it is reasonable to distribute some intelligence from the central control unit to the system’s components such as loads. A load’s control algorithm is presented that is able to fulfill the power management functions autonomously. Its stability is examined both in theory and in real cases. Therefore, evaluation criterions are derived from the component’s system behavior. Based on the algorithm’s equations, the transfer function is defined in order to proof the stability. Furthermore, over 200 test cases had been conducted and analyzed at a power net test bench that contains the whole vehicular power net, including wiring harness and chassis ground. The impact of all variables and influence factors on the stability is checked and, likewise, malfunctions are examined, such as measurement errors or data transfer with long dead times. By this means, the most critical variables could be detected. Based on the results, some improvements of the control algorithm are made and, as a result, a stable implementation is realized.
A Dry Clutch Control Algorithm for AMT Systems in a Parallel Hybrid Electric Bus
Authors: Shin Changwoo , Kim Moseong , Zheng Chunhua , Lim Wonsik , Cha Sukwon
Published: May 2018

A clutch is a mechanical device which provides engine torque to the drive shaft of a vehicle. A dry clutch control for AMT (Automated Manual Transmission) systems has been an important issue to improve fuel economy and drivability in hybrid electric systems. In this paper, we propose a dry clutch control system to apply to the parallel hybrid electric bus. In order to analysis dynamic performance of the target vehicle, a vehicle dynamic model including engine, clutch, motor, transmission and vehicle is designed. For gear shifting simulation, the shifting maps for the hybrid electric bus are applied from the analysis results of DP (Dynamic Programming) theory that is one of the optimal control methods. The shifting maps consist of a pure electric mode and a hybrid electric mode calculated by using driving cycles for commercial vehicles. From vehicle dynamic equations, the control algorithm for a dry clutch is organized by using feedback loops based on the value of an engine, a clutch speed, a clutch release travel and an estimated clutch torque. Simulations are performed to analyze the dynamic performance of the proposed clutch control system during gear shifting. As a result, the vehicle model with the designed clutch controller compares to one with only the lockup controller in energy dissipation during gear shifting.
Electromechanical Components and its Energy Saving Design Strategy in PHEV Powertrain
Authors: Szumanowski Antoni , Liu Zhiyin , Chang Yuhua
Published: May 2018

This paper presents advanced Compact Hybrid Planetary Transmission Drive (CHPTD) as a solution for the plug-in hybrid electric vehicle (PHEV). Proper architecture and elements were designed to achieve the functions of PHEV. The parameters of powertrain were adjusted and optimized by simulation. Two basic control strategies were selected and analyzed to achieve minimum energy consumption and the proper operation range of battery state of charge (SOC). The very effective operation of the improved powertrain was proved by tests in different driving cycles regarding the traffic both in city and suburb area. The advantage of planetary transmission, which is power summing mechanical unit, was obtained by the proper design and the control of innovative high energy saving electromagnetic clutch-brake device based on classic dual-diaphragm spring system, which also permits to apply multi-speed additional automatic mechanical transmission.
Effective Thermal Simulation of Power Electronics in Hybrid and Electric Vehicles
Authors: Liu Wenjun , Torsten Hauck , Drobnik Josef
Published: May 2018

Thermal management is critical in development of hybrid and electric vehicles since they contain multiple high-density power modules that require compact integration and effective cooling. During operation the power modules generate large amounts of heat leading to significant temperature increases and thermal gradients inside dies and across the packages. Electro-thermal simulation is needed to choose the best operating regime to meet the thermal and electrical requirements. However, this is usually computationally expensive. One effective method is to develop a compact but accurate thermal model to capture the thermal physics that can be used in the system-level electro-thermal model. In this paper an effective Model Order Reduction (MOR) is developed that drastically reduces the number of Degree of Freedoms (DOFs) of the original large-dimension ODE system. Finite Element Analysis (FEA)/ Computational Fluid Dynamics (CFD) simulation is first conducted to find the optimal pin-fin to rear channel ratio and the optimal pin fin shape that gives lowest peak temperature and pressure drop. The convective heat transfer coefficients exacted from FEA/CFD is input to the MOR model. The MOR model is then applied to a converter assembly, and results show that it can reduce the computation time from 2 hours to 1 second with reasonable error compared to the FEA/CFD predictions. The MOR thermal model can be further coupled with electrical circuit models to form a system model to predict the temperature profile and the power modules’ electrical transient performance.
Smart Charging Systems for Plug-in Electric Vehicles
Authors: Shocket Abe
Published: May 2018

This paper describes “smart charging” systems for plug-in hybrid electric vehicles (PHEVs). The principal design feature is that the system uses gathered information to adaptively control PHEV charging, and does so in a way that allows customer PHEVs to still be charged at a preferred rate (cost). This paper reviews the drivers for smart charging, including electric grid readiness for large adoption rates of PHEVs, and considers national, regional and local distribution level issues. At the distribution level, the effect of increased PHEV charging loads on transformers is considered. The current state of standardization is reviewed with emphasis on communication messages and use cases that reflect smart charging attributes. Centralized system approaches are described, such as integrating electric vehicle supply equipment (EVSE), i.e. chargers, into Advanced Metering Infrastructure (AMI) networks, and treating EVSEs as controllable loads for Demand Response programs. Metering and monitoring the transformers that feed EVSEs can drive a control scheme that is either centralized or distributed. Alternatives to AMI-integration for centralized networks are also reviewed, including commercially available systems. Additionally, smart charging is considered from the billing perspective, where system approaches are described that allow for identification and association between connected PHEVs, EVSEs, premise meters and other smart devices.
The Norwegian Charging Station Database for Electromobility (NOBIL)
Authors: Kvisle Hans
Published: May 2018

How did Norway get a highly developed database for charging stations, capable of real-time updates on availability, ready and free to be adopted by any country? A co-operation between Transnova, a governmental entity, and the association of EV-users to develop an open database which allows everyone to build services upon standardized data.
Neighbourhood Electric Vehicles in Mature Suburbs
Authors: Magarian David , Seimbab Walter
Published: May 2018

This is a Report on the first phase of a demonstration of Neighborhood Electric Vehicles (NEVs) in the South Bay Subregion of Los Angeles County. The project is sponsored by the South Bay Cities Council of Governments (SBCCOG) and funded by the South Coast Air Quality Management District (AQMD). Active use of the first demonstration phase began May 1, 2010 and ran for 18 months ending October 31, 2011. This Report, based on the 18 months of data collection and analysis, aims to identify the positive role NEVs can play in addressing the following issues: • Reducing green house gas emissions, criteria air pollutants, and consumption of fossil fuels by passenger vehicles and light trucks. • Informing government plans and policies currently being formulated, including the 2012 Regional Transportation Plan, California Energy Commission’s initiative for electric vehicle readiness, and the California Air Resources Board AB 118 vehicle voucher program. • Implementing the Sustainable South Bay Strategy with its mobility initiative based on transitioning the gasoline fueled passenger vehicle fleet to some form of electric vehicle. Because this study is extremely data rich, a very detailed and scientific analysis has been completed for a somewhat small sample size of 29 participating households. From these findings it is clear that significant GHG and criteria air pollutant reductions could be achieved from wide spread use of NEVs for suburban residential driving. This research has also identified numerous market barriers that prevent wide spread adoption of NEVs as well as strategies to overcome market barriers such as production quality, speed limitations, and NEV prices.
Evolving a Cleaner Grid: Uses of Natural Gas in Transportation
Authors: Bromaghim Geoffrey , Hinkle Jerome
Published: May 2018

Achieving greenhouse gas emissions reduction goals from the transportation sector will be a monumental challenge. Various alternative vehicle technologies such as plug-in hybrids, battery and fuel cell electric vehicles offer the promise of sharply reducing end use emissions. However, when considering the full fuel cycle, it is clear that a dramatically cleaner electricity grid will also be necessary if we ever hope to meet ambitious long-term reduction goals. To demonstrate the importance of achieving this dramatically cleaner grid, our analysis implements Argonne National Laboratory’s GREET model and the latest Annual Energy Outlook data to evaluate the relative merit of various alternative vehicles on a well-to-wheel basis while taking into account projections for the evolution of the U.S. electricity supply. Fortunately, significant progress is now underway to transform the electricity sector. The emergence of substantial supplies of shale gas, at low cost and substantial abundance, has dramatically reshaped the energy landscape. There are multiple pathways for this abundant supply of natural gas to help reduce the transportation sector emissions footprint, whether through greater utilization in highly efficient natural gas combined-cycle electricity generators, direct use in compressed natural gas vehicles, or steam reformation to provide hydrogen for fuel cell vehicles. Greater reliance on high efficiency natural gas combined cycle generators, combined with the steady expansion of renewable generation and energy efficiency, is providing a critical alternative to continued reliance on dirty, legacy generators. This emerging new clean power paradigm can multiply the benefits of more rapid growth in electric drive vehicles.
Advanced VDC simulations of In-wheel electric vehicle using Carsim and Simulink
Authors: Ha Hyunuk , Kim Jongmoo , Chung Shiuk , Lee Jangmyung
Published: May 2018

Conventional engine based vehicles inevitably have complicated structures due to lots of elements. Because of this characteristic, research, development, and also marketing are mainly conducted by the conglomerate, like GM, BMW, Honda, and Hyundai motors, etc. But environmental pollution and fuel exhaustion by the stated vehicle increase the necessity of EV(Electric Vehicle) as a representative of green car. First of all, the structure of EV is relatively simple, and energy transmission ratio of electric motor is more efficient than the engine based power train system. In addition to these, inwheel EV can estimate exact wheel torque, which is the most fundamental information for slip control, such as VDC(Vehicle dynamics control)/TCS(Traction control system)/ABS(Anti-lock brake system). Various kinds of expectable situations during EV’s navigation have been simulated through the coordination between ‘Carsim’ and ‘Simulink’.
Design considerations for fast AC battery chargers
Authors: Bertoluzzo Manuele , Buja Giuseppe , Pede Giovanni
Published: May 2018

Proliferation of electric vehicles (EVs) is tightly associated to the fast charging of their batteries. Both high-power DC and AC supply options are envisaged for the fast charging of the EV batteries, each of them having different features. This paper considers the AC supply option and deals with the main issues that it poses like an onboard high-power battery charger and its impact on the grid. To face with these issues, a possible arrangement for the battery chargers consists in the integral use of the inverter bound to supply the traction motor and in the proper conditioning of the current absorbed from the grid. In the paper, design considerations for this arrangement are given and applied to the case study of a purely electric, mid-size car.
Realistic estimates of EV range based on extensive laboratory and field tests in Nordic climate conditions
Authors: Laurikko Juhani , Granström Robert , Haakana Arto
Published: May 2018

Shortage of range is by far the greatest flaw in current electric vehicle technology. Furthermore, energy use is also highly dependent on duty cycles, driving conditions and traffic situation. Additionally, cabin heating in an EV will not be supported by energy losses as in an ICE-car. Therefore, actual range can differ sub-stantially in real-life situations, and can be much shorter than the official figures given by the manufactur-ers. Project RekkEVidde is aiming at drafting a testing scheme to address EV driving in Nordic conditions, and produce realistic range estimates for the consumers to help them understand this raising technology and make successful purchase decisions. Both in-laboratory and field testing in actual winter weather condi-tions has been performed with almost all publicly available electric vehicles. The outcome of the project is a confirmation that in Nordic climate the adverse driving conditions and especially thermal management of the cabin for adequate driving comfort will seriously shorten the range. Therefore, additional testing to re-flect this is definitely needed to complement the official regulatory test. However, it may not have to be very complex, as the testing workshop held in Northern Sweden proved. Already steady-speed driving with heater on and logging the cabin temperatures and energy consumption from the CAN-bus can provide val-uable information on how the vehicle can perform in cold climate
SuperLIB Project – Analysis of the Performances of the Hybrid Lithium HE-HP Architecture For Plug-In Hybrid Electric Vehicles
Authors: Omar Noshin , Fleurbaey Karel , Kurtulus Can , Van den Bossche Peter , Coosemans Thierry , Van Mierlo Joeri
Published: May 2018

This paper represents the latest results of the FP7 European Project SuperLIB: Advanced Dual-Cell Battery Concept for Battery Electric Vehicles. The electrical characteristics of the proposed hybrid topology based on high power and high-energy cells are presented. In the framework of project, dedicated research work has been carried out in the field of characterization and modeling. From these characterization results advanced simulation models have been developed for investigation and prediction of the proposed hybrid concept in detail based on innovative simulation tool for evaluation and optimization of the power flow in the driveline. From the simulation results have been concluded that the performances of the vehicle can be enhanced in terms of power capabilities and range extension. Then, the results also show that the abilities of the highenergy battery can be improved in terms of energy efficiency, voltage drop and heat development inside the battery. Finally the comparative analysis illustrates that the SuperLIB hybrid architecture has several merits against the hybrid topology based on high-energy batteries and electrical double-layer capacitors in terms of weight and volume.
Residential Smart-Charging Pilot Program in Toronto: Results of a Utility Controlled Charging Pilot
Authors: Bauman J. , Stevens M.B. , Hacikyan S. , Tremblay L. , Mallia E. , Mendes C.J.
Published: May 2018

Thirty plug-in electric vehicle (PEV) owners in Toronto participated in the 15-month ChargeTO program, which actively curtailed their vehicles during charging. The intent was to demonstrate the technical feasibility of the smart-charging system and evaluate its limitations, quantify the real-world curtailment availability of the PEVs, and to capture the participant’s impressions and response to various incentive structures. A key feature of this program was the use of vehicle-side data, namely battery state-of-charge (SOC), to ensure that charge curtailments did not negatively affect the participants. This paper summarizes the findings from the ChargeTO program.
Development of electromobility in France: Causes, facts and figures
Authors: Castelli Marie , Beretta Joseph
Published: May 2018

With more than 65 000 electric vehicles on the road, France is one of the most dynamic markets in the world. The paper aims at explaining how French authorities and industry managed to develop electric mobility in the country and to review the growth of electric vehicle uses. The paper will make a specific focus on the evolution of charging infrastructures networks and public subsidies.
Key Findings of German Showcase Region for Electric Mobility: E-Mobility Works! Economic Feasibility and Legal Frameworks as Main Challenges
Authors: RUPRECHT Michael
Published: May 2018

The Showcase Region for Electric Mobility LivingLab BWe mobil takes place in the two largest cities of Baden-Wuerttemberg in the south-west of Germany. The results of large-scale regional government-funded demonstration projects are described in this paper. Electric mobility works in various use cases and different types of vehicles, but economic feasibility is still a challenge in some use cases. For this reason continuous R&D activities are needed and appropriated legal frameworks help to overcome obstacles and offer incentives.
Plug-in Vehicle Behaviors: An analysis of charging and driving behavior of Ford plug-in electric vehicles in the real world
Authors: Boston Daniel , Werthman Alyssa
Published: May 2018

This paper analyzes the charging and driving behavior collected from thousands of North American Ford full battery electric vehicles (BEVs) and plug-in hybrid electric vehicles (PHEVs) whose owners utilize the MyFord Mobile smart phone app, thus enabling aggregated data for analysis. The trends investigated include charging frequency, electric vehicle miles travelled (eVMT), daily miles driven, and other factors.
Expanding the Fast Charging Network
Authors: Allen Jeff
Published: May 2018

Oregon has more DC Fast Chargers (DCFC) for electric vehicles per capita than any other US region. This network has played a major role in making Oregon one of the strongest markets for electric vehicle sales in the US, despite the lack of a state purchase incentive. This paper summarizes Oregon’s experience with fast charging, evaluates the impact of this network, proposes new ways of defining network “success,” and makes recommendations for cost effectively expanding the network. These findings and recommendations should help inform other regions that are just beginning to build out their fast charging networks.
Les archives épistolaires d’Albrecht von Haller : formation, perception, réception d’une correspondance
Authors: Stuber Martin
Published: May 2018

Le réseau de correspondance d’Albrecht von Haller compta parmi les plus puissants de l’histoire moderne. L’article se propose de reconstruire et d’analyser tant le contexte de son développement que sa tradition manuscrite. Ces deux aspects sont essentiels pour interpréter un tel corpus de sources, puisque, d’un côté, ils donnent des renseignements sur l’image qu’avaient d’eux-mêmes les acteurs du réseau et, de l’autre, ils permettent d’éclairer la représentativité des lettres conservées. Un accent particulier est mis sur la distinction entre les niveaux privé et public de communication ainsi qu’entre représentation de soi et pratiques effectives.
La tradition française de l’infortiat et le livre de Jostice et de Plet
Authors: Pastore Graziella , Duval Frédéric
Published: May 2018

The Infortiatum, one of the three parts of the Digestum in theMiddle Ages, was translated into French in the thirteenth century. The translation is directly preserved in two manuscripts, and excerpted in the Livre de jostice et de plet, of which only one manuscript is known. This article highlights the connections between all three French witnesses, drawing conclusions that should prove useful for future critical editions of the translation, on the one hand, and of the Livre de jostice et de plet, on the other. In addition, it sheds light on the circulation of learned translations of Roman law texts and raises new questions concerning the nature of the single manuscript of the Livre de jostice et de plet.
Engagement et appartenances : les vies des magistrats Étienne de Lestang (1510-1581) et Antoine de Lestang (1541-1617)
Authors: Cassan Michel
Published: May 2018

Fondé sur un important corpus de sources, l’article propose une reconstitution des itinéraires de deux magistrats brivistes, fervents catholiques très engagés dans la lutte contre le protestantisme, Étienne de Lestang (vers 1510-1581) et son fils

Antoine de Lestang (1541-1617). La méthode retenue ¢ l’histoire sociale nominative qui emprunte une partie de sa démarche à la microstoria ¢ permet d’interroger la diversité des engagements définis comme des manifestations du «je » liées à la part de liberté dont dispose chaque individu dans une société de type holiste. Les deux cas questionnent les effets d’engagements religieux comparables sur des appartenances plurielles, professionnelles, sociales, communautaires, politiques. Ils démontrent la singularité de chaque existence qui doit composer avec des contingences surplombantes, susceptibles de ruiner des appartenances ou difficilement compatibles avec un engagement.
Electronic conduction during the formation stages of a single-molecule junction
Authors: Pal Atindra Nath , Klein Tal , Vilan Ayelet , Tal Oren
Published: May 2018

Single-molecule junctions are versatile test beds for electronic transport at the atomic scale. However, not much is known about the early formation steps of such junctions. Here, we study the electronic transport properties of premature junction configurations before the realization of a single-molecule bridge based on vanadocene molecules and silver electrodes. With the aid of conductance measurements, inelastic electron spectroscopy and shot noise analysis, we identify the formation of a single-molecule junction in parallel to a single-atom junction and examine the interplay between these two conductance pathways. Furthermore, the role of this structure in the formation of single-molecule junctions is studied. Our findings reveal the conductance and structural properties of premature molecular junction configurations and uncover the different scenarios in which a single-molecule junction is formed. Future control over such processes may pave the way for directed formation of preferred junction structures.
Synthetic avenues towards a tetrasaccharide related to Streptococcus pneumonia of serotype 6A
Authors: Chaudhury Aritra , Mukherjee Mana Mohan , Ghosh Rina
Published: May 2018

Streptococcus pneumonia (SPn) is a Gram-positive bacterium which causes life threatening diseases. The bacteria protect themselves against non-specific host defence by an external polysaccharide (PS) capsule which bears a repeating unit, α-D-Galp(1->3)-α-D-Glcp(1->3)-α-L-Rhap(1->3)-D-Rib (SPn 6A). A closer look at the structure reveals the presence of α-linked galactose and glucose residues. The synthesis of these 1,2-cis glycosidic linkages are considered challenging particularly in the context of a one-pot oligosaccharide synthesis. We have synthesized the aforesaid tetrasaccharide (SPn 6A) based on both stepwise and sequential one-pot glycosylation reactions using easily accessible common building blocks; eventually similar overall yields were obtained in both cases.
On the Detectability of Planet X with LSST
Authors: Trilling David E. , Bellm Eric C. , Malhotra Renu
Published: May 2018

Two planetary mass objects in the far outer solar system—collectively referred to here as Planet X— have recently been hypothesized to explain the orbital distribution of distant Kuiper Belt Objects. Neither planet is thought to be exceptionally faint, but the sky locations of these putative planets are poorly constrained. Therefore, a wide area survey is needed to detect these possible planets. The Large Synoptic Survey Telescope (LSST) will carry out an unbiased, large area (around 18000 deg2), deep (limiting magnitude of individual frames of 24.5) survey (the “wide-fast-deep (WFD)” survey) of the southern sky beginning in 2022, and it will therefore be an important tool in searching for these hypothesized planets. Here, we explore the effectiveness of LSST as a search platform for these possible planets. Assuming the current baseline cadence (which includes the WFD survey plus additional coverage), we estimate that LSST will confidently detect or rule out the existence of Planet X in 61% of the entire sky. At orbital distances up to ∼75 au, Planet X could simply be found in the normal nightly moving object processing; at larger distances, it will require custom data processing. We also discuss the implications of a nondetection of Planet X in LSST data.
The Clustering of High-redshift (2.9 ≤ z ≤ 5.1) Quasars in SDSS Stripe 82
Authors: Timlin John D. , Ross Nicholas P. , Richards Gordon T. , Myers Adam D. , Pellegrino Andrew , Bauer Franz E. , Lacy Mark , Schneider Donald P. , Wollack Edward J. , Zakamska Nadia L.
Published: May 2018

We present a measurement of the two-point autocorrelation function of photometrically selected high-z quasars over ∼100 deg2 on the Sloan Digital Sky Survey Stripe 82 field. Selection is performed using three machine-learning algorithms in a six-dimensional optical/mid-infrared color space. Optical data from the Sloan Digital Sky Survey are combined with overlapping deep mid-infrared data from the Spitzer IRAC Equatorial Survey and the Spitzer-HETDEX Exploratory Large-Area survey. Our selection algorithms are trained on the colors of known high-z quasars. The selected quasar sample consists of 1378 objects and contains both spectroscopically confirmed quasars and photometrically selected quasar candidates. These objects span a redshift range of 2.9 ≤ z ≤ 5.1 and are generally fainter than i = 20.2, a regime that has lacked sufficient number density to perform autocorrelation function measurements of photometrically classified quasars. We compute the angular correlation function of these data, marginally detecting quasar clustering. We fit a single power law with an index of δ = 1.39 ± 0.618 and amplitude of θ
0 = 0.′71 ± 0.′546 . A dark matter model is fit to the angular correlation function to estimate the linear bias. At the average redshift of our survey (

), the bias is b = 6.78 ± 1.79. Using this bias, we calculate a characteristic dark matter halo mass of 1.70–9.83

. Our bias estimate suggests that quasar feedback intermittently shuts down the accretion of gas onto the central supermassive black hole at early times. If confirmed, these results hint at a level of luminosity dependence in the clustering of quasars at high-z.
Generation of a Large-scale Magnetic Field in a Convective Full-sphere Cross-helicity Dynamo
Authors: Pipin V. V. , Yokoi N.
Published: May 2018

We study the effects of the cross-helicity in the full-sphere large-scale mean-field dynamo models of a 0.3 M
⊙ star rotating with a period of 10 days. In exploring several dynamo scenarios that stem from magnetic field generation by the cross-helicity effect, we found that the cross-helicity provides the natural generation mechanisms for the large-scale scale axisymmetric and nonaxisymmetric magnetic field. Therefore, the rotating stars with convective envelopes can produce a large-scale magnetic field generated solely due to the turbulent cross-helicity effect (we call it γ
2-dynamo). Using mean-field models we compare the properties of the large-scale magnetic field organization that stems from dynamo mechanisms based on the kinetic helicity (associated with the α
2 dynamos) and cross-helicity. For the fully convective stars, both generation mechanisms can maintain large-scale dynamos even for the solid body rotation law inside the star. The nonaxisymmetric magnetic configurations become preferable when the cross-helicity and the α-effect operate independently of each other. This corresponds to situations with purely γ
2 or α
2 dynamos. The combination of these scenarios, i.e., the γ
2
α
2 dynamo, can generate preferably axisymmetric, dipole-like magnetic fields at strengths of several kGs. Thus, we found a new dynamo scenario that is able to generate an axisymmetric magnetic field even in the case of a solid body rotation of the star. We discuss the possible applications of our findings to stellar observations.
The Peculiar Radial Distribution of Multiple Populations in the Massive Globular Cluster M80
Authors: Dalessandro E. , Cadelano M. , Vesperini E. , Salaris M. , Ferraro F. R. , Lanzoni B. , Raso S. , Hong J. , Webb J. J. , Zocchi A.
Published: May 2018

We present a detailed analysis of the radial distribution of light-element multiple populations (LE-MPs) in the massive and dense globular cluster M80, based on a combination of UV and optical Hubble Space Telescope data. Surprisingly, we find that first-generation (FG) stars (FG) are significantly more centrally concentrated than extreme second-generation (SG) stars out to ∼2.5r

h
from the cluster center. To understand the origin of such peculiar behavior, we used a set of N-body simulations following the long-term dynamical evolution of LE-MPs. We find that, given the advanced dynamical state of the cluster, the observed difference does not depend on the primordial relative distributions of FG and SG stars. On the contrary, a difference of ∼0.05–0.10 M
⊙ between the average masses of the two subpopulations is needed to account for the observed radial distributions. We argue that such a mass difference might be the result of the higher He abundance of SG stars (of the order of ΔY ∼ 0.05–0.06) with respect to FG stars. Interestingly, we find that a similar He variation is necessary to reproduce the horizontal branch morphology of M80. These results demonstrate that differences in mass among LE-MPs, due to different He content, should be properly taken into account for a correct interpretation of their radial distribution, at least in dynamically evolved systems.
A Particle Module for the PLUTO Code. I. An Implementation of the MHD–PIC Equations
Authors: Mignone A. , Bodo G. , Vaidya B. , Mattia G.
Published: May 2018

We describe an implementation of a particle physics module available for the PLUTO code appropriate for the dynamical evolution of a plasma consisting of a thermal fluid and a nonthermal component represented by relativistic charged particles or cosmic rays (CRs). While the fluid is approached using standard numerical schemes for magnetohydrodynamics, CR particles are treated kinetically using conventional Particle-In-Cell (PIC) techniques. The module can be used either to describe test-particle motion in the fluid electromagnetic field or to solve the fully coupled magnetohydrodynamics (MHD)–PIC system of equations with particle backreaction on the fluid as originally introduced by Bai et al. Particle backreaction on the fluid is included in the form of momentum–energy feedback and by introducing the CR-induced Hall term in Ohm’s law. The hybrid MHD–PIC module can be employed to study CR kinetic effects on scales larger than the (ion) skin depth provided that the Larmor gyration scale is properly resolved. When applicable, this formulation avoids resolving microscopic scales, offering substantial computational savings with respect to PIC simulations. We present a fully conservative formulation that is second-order accurate in time and space, and extends to either the Runge–Kutta (RK) or the corner transport upwind time-stepping schemes (for the fluid), while a standard Boris integrator is employed for the particles. For highly energetic relativistic CRs and in order to overcome the time-step restriction, a novel subcycling strategy that retains second-order accuracy in time is presented. Numerical benchmarks and applications including Bell instability, diffusive shock acceleration, and test-particle acceleration in reconnecting layers are discussed.
The Dust and [C ii] Morphologies of Redshift ∼4.5 Sub-millimeter Galaxies at ∼200 pc Resolution: The Absence of Large Clumps in the Interstellar Medium at High-redshift
Authors: Gullberg B. , Swinbank A. M. , Smail I. , Biggs A. D. , Bertoldi F. , Breuck C. De , Chapman S. C. , Chen C.-C. , Cooke E. A. , Coppin K. E. K. , Cox P. , Dannerbauer H. , Dunlop J. S. , Edge A. C. , Farrah D. , Geach J. E. , Greve T. R. , Hodge J. , Ibar E. , Ivison R. J. , Karim A. , Schinnerer E. , Scott D. , Simpson J. M. , Stach S. M. , Thomson A. P. , van der Werf P. , Walter F. , Wardlow J. L. , Weiss A.
Published: May 2018

We present deep, high-resolution (0.″03, 200 pc) ALMA Band 7 observations covering the dust continuum and [C ii] λ157.7 μm emission in four z ∼ 4.4–4.8 sub-millimeter galaxies (SMGs) selected from the ALESS and AS2UDS surveys. The data show that the rest-frame 160 μm (observed 345 GHz) dust emission is consistent with smooth morphologies on kpc scales for three of the sources. One source, UDS 47.0, displays apparent substructure, but this is also consistent with a smooth morphology—as indicated by simulations showing that smooth exponential disks can appear clumpy when observed at the high angular resolution (0.″03) and depth of these observations (

μJy beam−1). The four SMGs are bright [C ii] emitters. We extract [C ii] spectra from the high-resolution data, and recover ∼20%–100% of the [C ii] flux and ∼40%–80% of the dust continuum emission, compared to the previous lower-resolution observations. When tapered to 0.″2 resolution, our maps recover ∼80%–100% of the continuum emission, indicating that ∼60% of the emission is resolved out on ∼200 pc scales. We find that the [C ii] emission in high-redshift galaxies is more spatially extended than the rest-frame 160 μm dust continuum by a factor of 1.6 ± 0.4. By considering the

/

ratio as a function of the star formation rate surface density (

), we revisit the [C ii] deficit and suggest that the decline in the

/

ratio as a function of

is consistent with local processes. We also explore the physical drivers that may be responsible for these trends and can give rise to the properties found in the densest regions of SMGs.
Dust Attenuation Curves in the Local Universe: Demographics and New Laws for Star-forming Galaxies and High-redshift Analogs
Authors: Salim Samir , Boquien Médéric , Lee Janice C.
Published: May 2018

We study the dust attenuation curves of 230,000 individual galaxies in the local universe, ranging from quiescent to intensely star-forming systems, using GALEX, SDSS, and WISE photometry calibrated on the Herschel ATLAS. We use a new method of constraining SED fits with infrared luminosity (SED+LIR fitting), and parameterized attenuation curves determined with the CIGALE SED-fitting code. Attenuation curve slopes and UV bump strengths are reasonably well constrained independently from one another. We find that

attenuation curves exhibit a very wide range of slopes that are on average as steep as the curve slope of the Small Magellanic Cloud (SMC). The slope is a strong function of optical opacity. Opaque galaxies have shallower curves—in agreement with recent radiative transfer models. The dependence of slopes on the opacity produces an apparent dependence on stellar mass: more massive galaxies have shallower slopes. Attenuation curves exhibit a wide range of UV bump amplitudes, from none to Milky Way (MW)-like, with an average strength one-third that of the MW bump. Notably, local analogs of high-redshift galaxies have an average curve that is somewhat steeper than the SMC curve, with a modest UV bump that can be, to first order, ignored, as its effect on the near-UV magnitude is 0.1 mag. Neither the slopes nor the strengths of the UV bump depend on gas-phase metallicity. Functional forms for attenuation laws are presented for normal star-forming galaxies, high-z analogs, and quiescent galaxies. We release the catalog of associated star formation rates and stellar masses (GALEX–SDSS–WISE Legacy Catalog 2).
The Mochi LabJet Experiment for Measurements of Canonical Helicity Injection in a Laboratory Astrophysical Jet
Authors: You Setthivoine , von der Linden Jens , Lavine Eric Sander , Carroll Evan Grant , Card Alexander , Quinley Morgan , Azuara-Rosales Manuel
Published: May 2018

The Mochi device is a new pulsed power plasma experiment designed to produce long, collimated, stable, magnetized plasma jets when set up in the LabJet configuration. The LabJet configuration aims to simulate an astrophysical jet in the laboratory by mimicking an accretion disk threaded by a poloidal magnetic field with concentric planar electrodes in front of a solenoidal coil. The unique setup consists of three electrodes, each with azimuthally symmetric gas slits. Two of the electrodes are biased independently with respect to the third electrode to control the radial electric field profile across the poloidal bias magnetic field. This design approximates a shear azimuthal rotation profile in an accretion disk. The azimuthally symmetric gas slits provide a continuously symmetric mass source at the footpoint of the plasma jet, so any azimuthal rotation of the plasma jet is not hindered by a discrete number of gas holes. The initial set of diagnostics consists of current Rogowski coils, voltage probes, magnetic field probe arrays, an interferometer and ion Doppler spectroscopy, supplemented by a fast ion gauge and a retarding grid energy analyzer. The measured parameters of the first plasmas are ∼1022 m−3, ∼0.4 T, and 5–25 eV, with velocities of ∼20–80 km s−1. The combination of a controllable electric field profile, a flared poloidal magnetic field, and azimuthally symmetric mass sources in the experiment successfully produces short-lived (∼10 μs, ≳5 Alfvén times) collimated magnetic jets with a ∼10:1 aspect ratio and long-lived (∼100 μs, ≳40 Alfvén times) flow-stabilized, collimated, magnetic jets with a ∼30:1 aspect ratio.
New Y and T Dwarfs from WISE Identified by Methane Imaging*

†
Authors: Tinney C. G. , Kirkpatrick J. Davy , Faherty Jacqueline K. , Mace Gregory N. , Cushing Mike , Gelino Christopher R. , Burgasser Adam J. , Sheppard Scott S. , Wright Edward L.
Published: May 2018

We identify new Y- and T-type brown dwarfs from the WISE All Sky data release using images obtained in filters that divide the traditional near-infrared H and J bands into two halves—specifically

and CH4l in the H and J2, and J3 in the J. This proves to be very effective at identifying cool brown dwarfs via the detection of their methane absorption, as well as providing preliminary classification using methane colors and WISE -to-near-infrared colors. New and updated calibrations between T/Y spectral types and

–CH4l J3–W2, and

–W2 colors are derived, producing classification estimates good to a few spectral sub-types. We present photometry for a large sample of T and Y dwarfs in these filters, together with spectroscopy for 23 new ultra-cool dwarfs—2 Y dwarfs and 21 T dwarfs. We identify a further 8 new cool brown dwarfs, which we have high confidence are T dwarfs based on their methane photometry. We find that, for objects observed on a 4 m class telescope at J-band magnitudes of ∼20 or brighter,

–CH4l is the more powerful color for detecting objects and then estimating spectral types. Due to the lower sky background in the J-band, the J3 and J2 bands are more useful for identifying fainter cool dwarfs at J ≳ 22. The J3–J2 color is poor at estimating spectral types. But fortunately, once J3–J2 confirms that an object is a cool dwarf, the J3–W2 color is very effective at estimating approximate spectral types.
The APOGEE-2 Survey of the Orion Star-forming Complex. I. Target Selection and Validation with Early Observations
Authors: Cottle J’Neil , Covey Kevin R. , Suárez Genaro , Román-Zúñiga Carlos , Schlafly Edward , Downes Juan Jose , Ybarra Jason E. , Hernandez Jesus , Stassun Keivan , Stringfellow Guy S. , Getman Konstantin , Feigelson Eric , Borissova Jura , Kim J. Serena , Roman-Lopes A. , Da Rio Nicola , De Lee Nathan , Frinchaboy Peter M. , Kounkel Marina , Majewski Steven R. , Mennickent Ronald E. , Nidever David L. , Nitschelm Christian , Pan Kaike , Shetrone Matthew , Zasowski Gail , Chambers Ken , Magnier Eugene , Valenti Jeff
Published: May 2018

The Orion Star-forming Complex (OSFC) is a central target for the APOGEE-2 Young Cluster Survey. Existing membership catalogs span limited portions of the OSFC, reflecting the difficulty of selecting targets homogeneously across this extended, highly structured region. We have used data from wide-field photometric surveys to produce a less biased parent sample of young stellar objects (YSOs) with infrared (IR) excesses indicative of warm circumstellar material or photometric variability at optical wavelengths across the full 420 square degree extent of the OSFC. When restricted to YSO candidates with H < 12.4, to ensure S/N ∼ 100 for a six-visit source, this uniformly selected sample includes 1307 IR excess sources selected using criteria vetted by Koenig & Liesawitz (2014) and 990 optical variables identified in the Pan-STARRS1 3π survey: 319 sources exhibit both optical variability and evidence of circumstellar disks through IR excess. Objects from this uniformly selected sample received the highest priority for targeting, but required fewer than half of the fibers on each APOGEE-2 plate. We filled the remaining fibers with previously confirmed and new color–magnitude selected candidate OSFC members. Radial velocity measurements from APOGEE-1 and new APOGEE-2 observations taken in the survey’s first year indicate that ∼90% of the uniformly selected targets have radial velocities consistent with Orion membership. The APOGEE-2 Orion survey will include >1100 bona fide YSOs whose uniform selection function will provide a robust sample for comparative analyses of the stellar populations and properties across all sub-regions of Orion.
Constraining the Type of Central Engine of GRBs with Swift Data
Authors: Li Liang , Wu Xue-Feng , Lei Wei-Hua , Dai Zi-Gao , Liang En-Wei , Ryde Felix
Published: May 2018

The central engine of gamma-ray bursts (GRBs) is poorly constrained. There exist two main candidates: a fast-rotating black hole and a rapidly spinning magnetar. Furthermore, X-ray plateaus are widely accepted to be the energy injection into the external shock. In this paper, we systematically analyze the Swift/XRT light curves of 101 GRBs having plateau phases and known redshifts (before 2017 May). Since a maximum energy budget (∼2 × 1052 erg) exists for magnetars but not for black holes, this provides a good clue to identifying the type of GRB central engine. We calculate the isotropic kinetic energy E
K,iso and the isotropic X-ray energy release E
X,iso for individual GRBs. We identify three categories based on how likely a black hole harbors a central engine: “Gold” (9 out of 101; both E
X,iso and E
K,iso exceed the energy budget), “Silver” (69 out of 101; E
X,iso less than the limit but E
K,iso greater than the limit), and “Bronze” (23 out of 101; the energies are not above the limit). We then derive and test the black hole parameters with the Blandford–Znajek mechanism, and find that the observations of the black hole candidate (“Gold” + “Silver”) samples are consistent with the expectations of the black hole model. Furthermore, we also test the magnetar candidate (“Bronze”) sample with the magnetar model, and find that the magnetar surface magnetic field (B

p
) and initial spin period (P
0) fall into reasonable ranges. Our analysis indicates that if the magnetar wind is isotropic, a magnetar central engine is possible for 20% of the analyzed GRBs. For most GRBs, a black hole is most likely operating.
New records and range extensions of several species of native bees (Hymenoptera: Apoidea) from Mississippi
Authors: Parys Katherine , Griswold Terry , Ikerd Harold , Orr Michael
Published: May 2018

The native bee fauna of Mississippi, USA has been historically poorly sampled, but is of particular relevance to determine range limits for species that occur in the southern United States. Currently published literature includes 184 species of bees that occur within the state of Mississippi. Additions to the list of native bees known for Mississippi are reported with notes on range, ecology and resources for identification.

The geographic ranges of seven additional species are extended into the state of Mississippi: Andrena (Melandrena) obscuripennis Smith, 1853, Anthemurgus passiflorae Robertson, 1902, Dieunomia bolliana (Cockerell 1910), Diadasia (Diadasia) enavata (Cresson 1872), Peponapis crassidentata (Cockerell 1949), Triepeolus subnitens Cockerell and Timberlake, 1929 and Brachynomada nimia (Snelling and Rozen 1987). These records raise the total number of published species known from the state to 191. Anthemurgus and Brachynomada are also genera new to Mississippi.
Discovery of the male of a rare aulacid wasp, Pristaulacus emarginaticeps Turner, 1922 (Hymenoptera: Aulacidae) from Vietnam and Laos
Authors: Kuroda Keita
Published: May 2018

Pristaulacus emarginaticeps Turner, 1922 was described from a single female from Hòa Bình Province, Vietnam and it has remained the only recorded specimen.

The male of Pristaulacus emarginaticeps Turner, 1922 is described for the first time and the species is newly recorded from Hà Tĩnh Province, Vietnam and Houaphanh Province, Laos.