bluuebunny/crossref_metadata_2025 huggingface dataset:
Maximum luminosities of normal stripped-envelope supernovae are brighter than explosion models allow
Authors: Sollerman J. , Yang S. , Perley D. , Schulze S. , Fremling C. , Kasliwal M. , Shin K. , Racine B.
Published: October 2021

Context. Stripped-envelope supernovae (SE SNe) of Type Ib and Type Ic are thought to be the result of explosions of massive stars that have lost their outer envelopes. The favored explosion mechanism is via core-collapse, with the shock later revived by neutrino heating. However, there is an upper limit to the amount of radioactive 56Ni that such models can accommodate. Recent studies in the literature point to a tension between the maximum luminosity from such simulations and the observations.

Aims. We used a well-characterized sample of SE SNe from the Zwicky Transient Facility (ZTF) Bright Transient Survey (BTS) to scrutinize the observational caveats regarding estimates of the maximum luminosity (and thus the amount of ejected radioactive nickel) for the sample members.

Methods. We employed the strict selection criteria for the BTS to collect a sample of spectroscopically classified normal Type Ibc SNe, for which we used the ZTF light curves to determine the maximum luminosity. We culled the sample further based on data quality, shape of the light curves, distances, and colors. Then we examined the uncertainties that may affect the measurements. The methodology of the sample construction based on this BTS sample can be used for other future investigations.

Results. We analyzed the observational data, consisting of optical light curves and spectra, for the selected sub-samples. In total, we used 129 Type Ib or Type Ic BTS SNe with an initial rough luminosity distribution peaking at Mr = −17.61 ± 0.72, and where 36% are apparently brighter than the theoretically predicted maximum brightness of Mr = −17.8. When we further culled this sample to ensure that the SNe are normal Type Ibc with good LC data within the Hubble flow, the sample of 94 objects gives Mr = −17.64 ± 0.54. A main uncertainty in absolute magnitude determinations for SNe is the host galaxy extinction correction, but the reddened objects only get more luminous after corrections. If we simply exclude red objects, or those with unusual or uncertain colors, then we are left with 14 objects at Mr = −17.90 ± 0.73, whereof a handful are most certainly brighter than the suggested theoretical limit. The main result of this study is thus that normal SNe Ibc do indeed reach luminosities above 1042.6 erg s−1, which is apparently in conflict with existing explosion models.
Comparison of enthalpy-porosity and lattice Boltzmann-phase field techniques for the simulation of the heat transfer and melting processes in LHTES devices
Authors: Krastev Vesselin Krassimirov , Falcucci Giacomo
Published: October 2021

Thermal energy torage (TES) is a key enabling technology for the efficient exploitation of distributed generation systems based on renewable energy sources. Among the available options, research on latent heat TES (LHTES) solutions has been particularly active in the last decade, due to their ability to store and release high amounts of thermal energy in a very narrow temperature range. LHTES devices are based on phase change materials (PCMs), which act as thermal sinks or sources during their solid-to-liquid transition and vice-versa. As such, the development of reliable numerical tools for the prediction of the heat transfer and phase change characteristics of PCMs is of foremost importance, to help designing innovative and efficiently integrated LHTES implementations. In the present paper, the consolidated enthalpy-porosity (EP) method is compared to a novel lattice Boltzmann-phase field (LB-PF) algorithm in the simulation of a standard numerical benchmark for paraffin-like PCM melting problems. Performances and limitations of the two approaches are discussed, including the influence of model-related and purely numerical parameters. Outcomes from this study are used to confirm general guidelines for the application of well established methodologies, as well as to suggest new pathways for out-of-standard modeling techniques.
A multilayer panel in cork and natural phase change materials: thermal and energy analysis
Authors: Mazzeo Domenico , Matera Nicoletta , Arcuri Natale , Barreca Francesco
Published: October 2021

This paper presents thermal and energy analysis of a multilayer panel in bio-based cork material and natural phase change materials (PCMs) for the development of prefabricated, recyclable and energy-efficient and autonomous building modules. For this purpose, a calculation tool is developed for the dynamic simulation of the thermal and energy behaviour of the sandwich panel. In particular, through an extensive parametric survey, the panel is sized with the identification of the arrangement of the layers, PCM temperature, and layer thicknesses to optimize the insulating and damping properties, considering typical climatic conditions of the Mediterranean climates of Southern Italy. From the conducted simulations, the types of sandwich panels that have the best insulating and storage characteristics for the building module construction were chosen. The results of these simulations will be used in future research for the preliminary design of tests to be carried out in a climatic chamber and to build a building module in real conditions to be constantly monitored through the automatic instrumental survey of internal and external physical quantities such as temperature, humidity and radiant temperature.
Evaluation of Biomimicry-based Strategies to Improve Exterior Environmental parameters: A numerical Study at Urban Scale in a tropical Climate
Authors: Araque Kevin , Palacios Paola , Mora Dafni , Chen Austin Miguel
Published: October 2021

Due to population growth, cities have expanded their urban areas, causing increased temperatures and vegetative scarcity. Therefore, studies have been carried out on the urban heat island phenomenon, its effect on people’s thermal stress, and how to mitigate this problem. This research aims to evaluate the application of biomimetic strategies for improving exterior environmental conditions on an urban scale under a tropical climate through dynamic simulation. The case study takes place in the Casco Antiguo of Panama. Here, two cases were evaluated (base case and proposed case). The proposed case consists of strategies obtained from the application of the biomimetic design methodology. The ENVI-met software was used to evaluate both cases, where the external environmental parameters are compared between both cases for the critical months (March and October) at 15:00. Results showed that the air temperature reached an average reduction for March of 1.9 °C and 2 °C for October, the Tmr had an increase up to 0.6 °C in March and the PET index decreased 1.7 °C in March and in October 2 °C. Although significant changes were obtained, high levels of discomfort persist due to the narrowness and proximity of the buildings in this urban settlement.
Design and development of three test facilities to evaluate heat transfer performances of advanced and low cost materials and coatings for geothermal application
Authors: Pardelli Paolo Taddei , Mannelli Andrea , Tempesti Claretta , Romani Luca , Baroni Alberto , Bosi Lorenzo , Ferrara Giovanni
Published: October 2021

Geothermal energy is accredited as a flexible, controllable and green source of energy.

Heat exchangers (HXs) are one of the most critical components of a geothermal power plant due to corrosion and scaling phenomena. Hence, improvements in the antiscaling and anticorrosion properties as well as heat transfer performance of the HX materials will lead to smaller, more efficient and less costly systems. EU H2020 GeoHex project relies on the use low-cost carbon steel-based material for HXs. Through modifying the surface with nano porous coating and controlling the surface chemistry, the heat transfer performance of single phase and phase change process will be improved.

This paper presents the design and development of three lab scale test rigs to test the effectiveness of innovative materials and superficial treatments on heat exchange with geothermal brine in single, condensing and evaporating phases. The rigs have been equipped with all the necessary instrumentation for control and for data acquisition. In particular, the advanced coatings are applied on a small stainless-steel plate and R134a fluid has been used for heat transfer coefficient characterization in different phase conditions.

GeoHex project has received funding from the European Union’s Horizon 2020 research and innovation programme. Grant agreement n.851917.
Excavator hydraulic circuit solution to reduce dissipations and fuel consumption
Authors: Casoli Paolo , Scolari Fabio , Vescovini Carlo Maria , Mesturini Davide , Zannoni Filippo
Published: October 2021

In the field of mobile machine the research is mainly focused on solutions to reduce the energy dissipations and fuel consumptions being these machines mainly equipped with Diesel engines. This paper presents a solution for improving the performance of a traditional Load sensing flow sharing circuit. The solution concerns the insertion of a Load sensing signal conditioner (LSc), developed by Walvoil S.p.A., that permits to dynamically change the pressure drop across the directional valves. A careful control of this new component permits to obtain a reduction of the fuel consumption without changing the performance of the machine taking as reference a JCMAS duty cycle. This paper presents the mathematical model of a 9 ton excavator that was previously validated with tests carried out on both the single hydraulic and the excavator main components like pump and flow sharing valves. The LSc model was developed and added to the traditional hydraulic circuit. The model of the excavator hydraulic circuit with this new component has permitted to simulate the energy saving achievable in comparison with the traditional solution. The paper presents the relevance of a carefully control of this new device in order to maximize the performance. The physical prototyping of this device has been already developed and will be installed in a mobile machine to confirm the simulated performance.
3D CFD simulation of a gaseous fuel injection in a hydrogen-fueled internal combustion engine
Authors: Barbato Alessio , Cantore Giuseppe
Published: October 2021

Nowadays, one of the hottest topic in the automotive engineering community is the reduction of fossil fuels. Hydrogen is an alternative energy source that is already providing clean, renewable, and efficient power being used in fuel cells. Despite being developed since a few decades, fuel cells are affected by several hurdles, the most impacting one being their cost per unit power. While waiting for their cost reduction and mass-market penetration, hydrogen-fueled internal combustion engines (H2ICEs) can be a rapidly applicable solution to reduce pollution caused by the combustion of fossil fuels. Such engines benefit from the advanced technology of modern internal combustion engines (ICEs) and the advantages related to hydrogen combustion, although some modifications are needed for conventional liquid-fueled engines to run on hydrogen. The gaseous injection of hydrogen directly into the combustion chamber is a challenge both for the designers and for the injection system suppliers. To reduce uncertainties, time, and development cost, computational fluid dynamics (CFD) tools appear extremely useful, since they can accurately predict mixture formation and combustion before the expensive production/testing phase. The high-pressure gaseous injection which takes place in Direct-Injected H2ICEs promotes a super-sonic flow with very high gradients in the zone between the bulk of the injected hydrogen and the flow already inside the combustion chamber. To develop a methodology for an accurate simulation of these phenomena, the SoPHy Engine of the Engine Combustion Network group (ECN) is used and presented. This engine is fed through a single nozzle H2-injector; planar laser-induced fluorescence (PLIF) data are available for comparison with the CFD outcomes.
Impact on the environment and on human health of internal combustion, hybrid and battery electric powered vehicles in a life cycle perspective
Authors: Di Maria Francesco , Cesari Daniela , Sisani Federico
Published: October 2021

Different power trained passenger cars were compared in a life cycle perspective (LCA) considering the Italian context for the year 2019. Main findings shows that battery electric vehicles, based on the current Italian energy mix, have the lower global warming emissions about 0.1 kgCO2eq/km. Lower particulate emissions of about 5x10-4 kgPM2,5eq/km and impact on human health about 7x10-7/km DALY were detected for petrol hybrid electric vehicles. Lower photochemical emissions of about 5x10-4 kgNMVOCeq/km were found for gasoline internal combustion engines vehicles.
Performance and Emissions Comparison between Biomethane and Natural Gas Fuel in Passenger Vehicles: results of the second testing campaign
Authors: Cignini Fabio , Genovese Antonino , Ortenzi Fernando , Valentini Stefano , Caprioli Alberto
Published: October 2021

The present paper illustrates the results of the second set of measurements carried out in the BiomethER project (EU-LIFE). BiomethER aimed to design and build two innovative bio-methane production plants, located in the Emilia Romagna region (Italy), so it aims to demonstrate that bio‑methane could replace traditional methane in several applications. One of these applications is road transport where bio-methane can fuel a compressed natural gas (CNG) vehicle. So, three passenger cars have been tested with two gases: conventional natural gas and bio-methane coming from a BiomethER plant. For each vehicle have been measured the emissions and performances on the chassis dynamometer, while an inspection of combustion chambers of the engines was carried out to evaluate their wear condition. This campaign confirms results achieved in the first one, there are no appreciable deviations for fuel consumption and CO2 emissions between the two fuels, acceleration and maximum power were almost the same for the three vehicles tested. Indeed, the vehicle fuelled by methane has significant carbon deposits on the piston crown while the bio-methane fuelled do not have the same.
Potential of hydrogen addition to natural gas or ammonia as a solution towards low- or zero-carbon fuel for the supply of a small turbocharged SI engine
Authors: Lanotte Alfredo , De Bellis Vincenzo , Malfi Enrica
Published: October 2021

Nowadays there is an increasing interest in carbon-free fuels such as ammonia and hydrogen. Those fuels, on one hand, allow to drastically reduce CO2 emissions, helping to comply with the increasingly stringent emission regulations, and, on the other hand, could lead to possible advantages in performances if blended with conventional fuels. In this regard, this work focuses on the 1D numerical study of an internal combustion engine supplied with different fuels: pure gasoline, and blends of methane-hydrogen and ammonia-hydrogen. The analyses are carried out with reference to a downsized turbocharged two-cylinder engine working in an operating point representative of engine operations along WLTC, namely 1800 rpm and 9.4 bar of BMEP. To evaluate the potential of methane-hydrogen and ammonia-hydrogen blends, a parametric study is performed. The varied parameters are air/fuel proportions (from 1 up to 2) and the hydrogen fraction over the total fuel. Hydrogen volume percentages up to 60% are considered both in the case of methane-hydrogen and ammonia-hydrogen blends. Model predictive capabilities are enhanced through a refined treatment of the laminar flame speed and chemistry of the end gas to improve the description of the combustion process and knock phenomenon, respectively. After the model validation under pure gasoline supply, numerical analyses allowed to estimate the benefits and drawbacks of considered alternative fuels in terms of efficiency, carbon monoxide, and pollutant emissions.
A Double Multiple Stream Tube (DMST) routine for site assessment to select efficient turbine aspect ratios and solidities in real marine environments
Authors: Pucci Micol , Zanforlin Stefania , Bellafiore Debora , Deluca Stefano , Umgiesser Georg
Published: October 2021

A MATLAB routine, based on a Double Multiple Stream Tube model, developed to quickly predict the performance of cross-flow hydrokinetic turbine, here is presented. The routine evaluate flow data obtained with the open-source marine circulation code SHYFEM. The tool can establish the best locations to place tidal devices taking into account bathymetric constraints and the hydrokinetic potential. Hence, it can be used to decide the best set of geometrical parameters. The geometrical variables of our analysis are turbine frontal area, aspect ratio and solidity. Several sub-models, validated with 3D and 2D CFD simulations, reproduce phenomena such as dynamic stall, fluid dynamic tips losses and the lateral deviation of streamlines approaching the turbine. As a case study, the tool is applied to an area of the northern Adriatic Sea. After having identified some suitable sites to exploit the energy resource, we have compared behaviours of different turbines. The set of geometrical parameters that gives the best performance in terms of power coefficient can vary considering several locations. Conversely, the power production is always greater for turbine with low aspect ratio (for a fixed solidity and area). Indeed, shorter devices benefit from higher hydrokinetic potentials at the top of the water column.
Effect of hydrogen addition in diesel/natural gas dual-fuel combustion with late injection
Authors: Caricato Antonio , Carlucci Antonio Paolo , Ficarella Antonio , Strafella Luciano
Published: October 2021

In a previous work, the effectiveness of late pilot injection on improving combustion behaviour – in terms of fuel conversion efficiency and pollutant emission levels – in a diesel/natural gas dual-fuel engine was assessed. Then, an additional set of experiments was performed, aiming at speeding up the combustion process possibly without penalizing NOx levels. Therefore, hydrogen was added to natural gas in a percentage equal to 10%. Results show that hydrogen addition has a significant effect on the combustion development specially during the early stage of combustion: ignition delay is shortened and combustion centre is advanced, while the combustion duration increases when pilot injection timing is set to conventional values, while remains basically unchanged for late timings. Fuel conversion efficiency is only slightly penalized when hydrogen is added. Moreover, it was confirmed that, in general, combustion strategy with late pilot injection timing does not penalize fuel conversion efficiency; indeed, in some cases, it actually increases. Concerning regulated emission levels, it is again proven that late pilot injection does not penalize pollutant production: the hydrocarbons and carbon monoxide reduce as pilot injection is delayed, probably due to the higher temperatures reached into the cylinder during most part of the expansion stroke. Moreover, adding hydrogen always reduces their levels. Concerning NOx, they are drastically reduced delaying pilot injection; as expected, hydrogen addition promotes NOx formation, but the increase, evident with conventional pilot injection timings, becomes marginal with late injection strategy. Therefore, combustion strategy performance with late pilot injection in dual-fuel diesel/natural gas combustion conditions can be further improved with 10% hydrogen addition to natural gas.
Investigation of CO2 mixtures to overcome the limits of sCO2 cycles
Authors: Morosini Ettore , Manzolini Giampaolo , Di Marcoberardino Gioele , Invernizzi Costante , Iora Paolo
Published: October 2021

Supercritical CO2 cycles are a promising technology, but their performance drops for hot cold source, in hot and arid environments, typical of a CSP field. The adoption of CO2-based mixtures as working fluid can turn supercritical CO2 cycles into transcritical cycles even at high temperatures, with performance improvement and significant power block cost reduction. The concept is addressed within the SCARABEUS project, an EU funded Horizon 2020 project dedicated to the use of CO2-based mixtures for CSP plants. In this work, the use of the CO2+C6F6 mixture as working fluid for a power cycle coupled with a solar tower is analysed. The potentiality of the mixture is presented, given its very low toxicity and its good thermal stability limits. Comparisons with the sCO2 cycle is performed for some typical configurations, in order to underline the advantages of the mixture, and a preliminary design of the turbine is presented, developed in a 1D tool.
Performance Assessment of Solar Cooling Systems with Energy Storage
Authors: Brumana Giovanni , Franchini Giuseppe , Ghirardi Elisa
Published: October 2021

The paper presents a complete solar cooling comparison. A detailed model of a tertiary sector building has been evaluated in three locations (Riyadh, Abu Dhabi, and Palermo) and coupled with four solar cooling systems: two solar thermal cooling systems (Li-Br absorption chiller and adsorption chiller), a solar Desiccant Evaporative Cooling system and a solar electric cooling (Photovoltaic coupled with Compression chiller). A multi-variable optimization procedure selects the optimal size of each component. The results show that the solar cooling system based on absorption chiller satisfied the cooling demand regardless of the site location whilst the performance of the Desiccant Evaporative Cooling system is dramatically affected by ambient conditions. The electric solar cooling option shows the best overall efficiency and appears a costeffective solution despite the high cost of the storage system.
Power to Methane technologies through renewable H2 and CO2 from biogas: The case of Sardinia
Authors: Concas Giulia , Lonis Francesco , Tola Vittorio , Cocco Daniele
Published: October 2021

A Power-to-Methane system based on a Biological Hydrogen Methanation (BHM) process using the CO2 produced by a biogas upgrading process and the H2 produced by an alkaline electrolyser was analysed in this work. The electrolyser can be fed by the electrical energy produced by a dedicated PV plant or supplied by the electrical grid. The analysis of the energy production from the PV plant and the consumption of the electrolyser was carried out on an hourly basis considering different sizes for the PV plant and four different scenarios for the operating time of the electrolyser. Also, a preliminary economic analysis was carried out to estimate the levelized cost of biomethane (LCOBM) and the costs of biomethane transport with a dedicate pipeline and in form of LNG by trucks. Finally, the paper investigated the availability of biomass and biogas in Sardinia that can be converted into biomethane, and the contribution of BHM plants to supply the forecast demand of CH4. The availability of biogas in Sardinia, together with the production of biomethane through BHM systems, can supply up to 44% of the forecast demand of CH4.
Characterization of aerosol and assessment of the risk of transmission of SARS-COV-2 VIRUS in a natural thermal cave
Authors: Scungio Mauro , Parlani Giulia
Published: October 2021

Thermal caves represent an environment characterized by unique chemical-physical properties, often used by customers for treatment and care of musculoskeletal, respiratory and skin diseases. The recent pandemic caused by COVID-19 has imposed the need to investigate the potential transmission scenario of SARS-CoV-2 virus also in such atypical and poorly studied indoor environments. This research work was carried out inside a natural thermal cave located in Italy where a waterfall of sulfur-sulfate-bicarbonate-alkaline earth mineral thermal water creates a warm-humid environment with 100% humidity and 48°C temperature. A characterization of the aerosol was carried out in terms of number, surface area and mass, as well as particle size distributions. The physical characteristics of the aerosol were measured inside the natural thermal cave and in other immediately adjacent areas in two different days and in two distinct moments by means of an optical spectrometer. The data obtained showed a predominance of particles with a diameter greater than 8 μm, associated with a low ability of penetration in the human respiratory system. Subsequently, through a model recently proposed in scientific literature, it was evaluated the airborne transmission risk of SARS-CoV-2 inside the cave by quantifying the probability of infection due to exposure in a microenvironment in presence of a SARS-CoV-2 infected subject. The infection risk was evaluated for different scenarios obtained combining parameters such as physical, breathing or talking activities of the occupants, simultaneous or non-simultaneous access to the cave and mechanical ventilation activated or non-activated. In terms of the risk of SARS-CoV-2 infection, evaluated under the hypotheses of the model, it was highlighted the decisive effect of the mechanical ventilation system on the risk of contagion: for all the hypothesized scenarios, there is a substantial reduction in the risk of contagion considering the ventilation system active. Furthermore, the adoption of social distancing measures such as non-simultaneous access to the cave makes the risk of contagion extremely low, according to the assumptions underlying the model, even with the mechanical ventilation system not active.
Analysis and Experimental Validation of the Tribological and Dynamic Characteristics of Journal Bearings
Authors: Yang Xin , Gu Genxiang , Sun Sicong , Li Saili , Zhou Jianming
Published: October 2021

Sliding bearings are the main kinematic pair of a Stirling engine, and one of the main sources of friction power loss and excitation force. There is a coupling effect between the lubrication state and the excitation force. In this paper, the dynamic model of a Sapphire bearing fatigue test bed, which includes thermo-elasto-hydrodynamic (EHD) property, is established and the accuracy of the model is verified by the experimental data. Based on the model, the effects of the load, the oil supply temperature, the oil supply pressure, the bearing clearance on the tribological and dynamic characteristics are studied. With an increase in the load, the orbital path of the journal moves downward, the lubrication state changes from the full hydrodynamic lubrication to the boundary lubrication, the friction power loss increases, and the bearing excitation frequency increases. Due to the decrease of the oil viscosity, the hydraulic friction power loss decreases, but the friction power loss derived from the asperity contact increase, so does the total friction power loss. With the increase of the radial clearance, the shape of the orbital path and the minimum oil film thickness remain unchanged. The increase of the bearing clearance results in the collisions between the journal and bearing bush, thus the amplitude of the frequency multiplication component in the bearing load increases, and the asperity and the total friction power loss increase.
Stirling Engine and absolute sealing
Authors: Raballand Thierry
Published: October 2021

Referring to the sketches, the alternative rotation of shaft (101) allows for absolute sealing between the left side and the right side of seal (1020). A device for total sealing around a shaft in alternating rotation is characterized in that a seal (1020), the main part of the device, called a torsion disc, constitutes the material insulator and is fixed on a shaft (101) by means of two spacers (610) and (620), where the spacer (610) is held in position by the bearing (710) and the spacer (620), which clamps the seal (1020), is held in position by the bearing (720). Along the shaft (101) on both sides of the seal (1020), O-rings (510) and (520) and possibly temperature insulating rings (410) and (420) can be arranged. On both sides of the seal (1020) there are possibly two pressure isolating stops (210) and (220), which slide in rotation on two other stops (110) and (120). The two bearing housings (228) and (8) are positioned relative to each other by means of shims (7) in order to clamp the seal (1020) at the bore and at the shaft. Connecting screws connect the bearing housings (228) and (8) and further connecting screws connect the housing (8) and the wall (22). Absolute sealing of a kinematic Stirling engine is now achievable. A French patent was taken out on August 27th, 2020.
Design and construction of multi-cylinder type liquid piston Stirling engine
Authors: Murti Prastowo , Takizawa Akira , Shoji Eita , Biwa Tetsushi
Published: October 2021

In a multi-cylinder type liquid piston Stirling engine (MCLPSE), liquid columns in U-shaped tubes play the role of solid pistons in a mechanical Stirling engine. Besides the straightforward structure, advantages of the MCLPSE are a relatively low operation temperature difference below 100 K and use of harmless working fluids of air and water. This study presents a mass spring model for the MCLPSE, from which we determine geometrical parameters of MCLPSE to achieve a target acoustic power production under a given temperature condition. The preliminary test results will be presented.
Stirling-Engine in a Novel Alphagamma Configuration – a Key for Maintenance-free Operation
Authors: Frauscher Josef , Diermaier Franz , Brandt Hans-Jürgen , Gschwendtner Michael
Published: October 2021

Since 2001, Frauscher Thermal Motors have been conducting research in the field of thermodynamic machines, in particular Stirling engines of various types. One important development step is the invention of a Stirling engine in an alphagamma® configuration. In this configuration, the expansion piston is designed as a differential piston with its ring surface connected to the cold volume.

In this paper, the design advantages of the alphagamma® configuration in comparison with a traditional alpha configuration are shown analytically by using a polytropic model as a modification of the ideal adiabatic analysis. The findings were confirmed by also simulating the proposed alphagamma® configuration in a Sage model which was validated against experimental data with very good agreement.

The results of both methods show that the counter-productive compression work can be reduced to almost zero – which makes the compression piston a displacer and explains the name alphagamma® – with the expansion work also reduced for the same net work output. As a consequence, the forces on the pistons, and thus, on the bearings can be significantly reduced, also leading to smaller piston side-loads, less friction and wear. The combination of all advantages allows the design of a mechanically sound and inexpensive machine.
Modeling dynamics of the spacecraft power plant consisting of Stirling engine and external thermal circuit
Authors: Valiullin Aigiz , Zenkin Vladimir
Published: October 2021

Modern space programs cover a wide range of missions, including both near-earth missions and those affecting areas of deep space. In the second case, power plants based on the conversion of thermal energy into electrical energy are often considered for the power supply of spacecraft. One of the possible thermoelectric converters is the Stirling engine. To be able to design modern power plants of spacecraft built based on Stirling engines, it is necessary to use calculation tools to simulate their operation in a wide range of modes, to take into consideration the influence of subsystems on each other and the final characteristics of the power plant. As part of the work, a thermodynamic model of an external thermal circuit was created, consisting of heat pipes, heat exchangers and radiator cooler panels. The hot thermal circuit is consisted of two parts: primary and secondary, the cold thermal circuit is consisted of only one part. A mathematical model of the free-piston Stirling engine of the first order has been also implemented. The working fluid in the engine is helium. The developed models were independently debugged and then integrated into a single model of the power plant. For each type of model, the corresponding mathematical models are presented and the basic assumptions are described. The model is implemented in an open simulation environment of xcos/scilab, examples of power plant model implementation are presented. Numerical experiments were carried out to study the dynamics of the heating of the contour elements (with independent, and then with integrated modeling) and the effect of the non-stationary thermal state on the engine performance. The article presents the basic equations and the design schemes for the power plant model, as well as some results of numerical simulation, including the dynamics of hot and cold circuit temperature changes and the dynamics of changes in the indicator diagram of the engine when the external thermal circuit is heated. The developed model can be used in the early stages of spacecraft design for a preliminary assessment of the main indicators of the power plant, its dimensions and thermal loads.
Superradical Hysterectomy for Cervical Cancer as an Alternative to the Usual Okabayashi-Type Radical Hysterectomy
Authors: Mandai Masaki , Yamaguchi Ken , Hamanishi Junzo , Sekiyama Kentaro , Kondoh Eiji
Published: October 2021

Radical hysterectomy is a standard operation for invasive cervical cancers. However, if the invasion to the parametrium is more advanced than estimation in the operation, it is difficult to perform usual radical hysterectomy. Superradical hysterectomy was developed by Prof. Ryukichi Mibayashi of Kyoto University and was published in 1941, and has been performed for the limited cases by a part of Japanese gynecologic surgeons. Superradical hysterectomy is a procedure in which the soft tissues in the pelvis are removed en bloc by sequential processing of the internal iliac vessels, which leads to a complete dissection of the lymphatic tissue in the pelvis to the pelvic wall.
Exploring interest intermediation in Central and Eastern Europe: is higher education different?
Authors: Dobbins Michael , Horváthová Brigitte , Labanino Rafael Pablo
Published: October 2021

Higher education interest groups remain somewhat understudied from a comparative theory-driven perspective. This is surprising because political decisions regarding higher education must increasingly be legitimized to students, taxpayers, the academic community and society. This article aims to advance our understanding of higher education stakeholders in post-communist Europe. In our view, the region deserves more attention, not least because students and academics were very instrumental in bringing down communism and institutionalizing democracy. First, we draw on Klemenčič’s (EJHE 2(1): 2–19, 2012; SHE 39(3):396–411, 2014) distinction between corporatist and pluralist as well as formalized and informal systems of representation in higher education. Looking at survey data from four countries—Poland, the Czech Republic, Hungary and Slovenia—we examine to what extent post-communist democracies have established corporatist institutions to facilitate the formal participation of various crucial stakeholder organizations, e.g. students’ unions, academic unions, rectors’ conferences, etc. Then we address whether higher education organizations enjoy privileged access to policy-makers compared to those from other policy areas, while engaging with the argument that higher education is a particular case of “stakeholder democracy” in a region otherwise characterized by weak civic participation and corporatism. To wrap up, we discuss different “mutations of higher education corporatism” in each country.
Multi-functional photonic processors using coherent network of micro-ring resonators
Authors: Yi Dan , Wang Yi , Tsang Hon Ki
Published: October 2021

Silicon photonics have widespread applications in optical communications, photonic sensors, and quantum information processing systems. Different photonic integrated circuits often require similar basic functional elements such as tunable filters, optical switches, wavelength de-multiplexers, optical delay lines, and polarization crosstalk unscrambling. Other optical signal processing functional elements may be needed in specific applications, for example, the differentiation with respect to time of time-varying optical signals and the implementation of very high extinction interferometers in some integrated quantum photonic circuits. Just as reconfigurable electronic processors in microelectronics have advantages in terms of ready availability and low cost from large-volume generic manufacturing and are useful for configuration into different functionalities in the form of field-programmable gate arrays, here, we show how an integrated coherent network of micro-ring resonators can be used in reconfigurable photonic processors. We demonstrate the implementation of optical filters, optical delay lines, optical space switching fabric, high extinction ratio Mach–Zehnder interferometer, and photonic differentiation in a reconfigurable network where the control of the phase in the different arms of the coherent network can determine the implemented functionality.
Does drought limit resprouter recruitment in
Authors: Leonard Jenny , West Adam G. , van Blerk Justin J. , Ojeda Fernando
Published: October 2021

Context It has been proposed that the distribution of resprouter and seeder Erica in the Cape Floristic Region (CFR) of South Africa is determined by drought rather than by fire frequency. Seedlings of Erica seeders are predicted to withstand the mild droughts of the southwest CFR better than those of Erica resprouters, which would account for the abundance of seeders in this region. Aims This study aimed to test this hypothesis using Erica coccinea (L.), which contains both a resprouter and a seeder form. Methods One-year-old seedlings of both forms were subjected to a progressively severe 50-day drought in the greenhouse. Key results Contrary to expectations, seeder seedlings had 67% higher mortality than resprouters during the initial phase of drought (30% vs 18% after 32 days). However, both forms were unable to survive as the drought progressed, resulting in 95% mortality by Day 50. There were limited differences between the forms in gas exchange and water potential, and no difference in root:shoot ratios. However, resprouters had significantly higher soluble carbohydrates than did seeders, which may have aided in delaying mortality. Conclusions Our results showed no evidence of resprouter seedlings being more vulnerable to mild drought than seeders in E. coccinea. Implications Our findings challenge the hypothesis that the distribution of this species can be explained by the vulnerability of resprouter seedlings to mild drought.
Neural oscillatory activity serving sensorimotor control is predicted by superoxide-sensitive mitochondrial redox environments
Authors: Spooner Rachel K. , Taylor Brittany K. , Ahmad Iman M. , Dyball Kelsey N. , Emanuel Katy , Fox Howard S. , Stauch Kelly L. , Zimmerman Matthew C. , Wilson Tony W.
Published: October 2021

Significance

Mitochondrial integrity and associated redox profiles have long been revered as key contributors to a host of age- and disease-related pathologies, which eventually lead to neuronal and behavioral dysfunction in the sensorimotor and other systems. However, the precise role of the mitochondrial redox environment in human sensorimotor brain systems and motor behavior remains poorly understood. Herein, we provide evidence for a strong predictive capacity of superoxide and its scavenger, superoxide dismutase, on the neural oscillatory dynamics serving motor planning and execution above and beyond the effects of mitochondrial respiratory capacities alone. Importantly, these data provide insight regarding the impact of the redox environment on the population-level neural oscillations that serve motor function in healthy humans.
The Epstein–Barr virus noncoding RNA EBER2 transactivates the UCHL1 deubiquitinase to accelerate cell growth
Authors: Li Zhe , Baccianti Francesco , Delecluse Susanne , Tsai Ming-Han , Shumilov Anatoliy , Cheng Xianliang , Ma Sicong , Hoffmann Ingrid , Poirey Remy , Delecluse Henri-Jacques
Published: October 2021

Significance

The Epstein–Barr virus (EBV) is an oncogenic virus that encodes multiple transforming proteins. EBV transforms resting normal B cells and is associated with multiple types of B cell lymphomas. How EBV transforms these cells is incompletely understood, in particular in tumor cells such as Burkitt’s lymphomas that do not express EBV’s oncogenes. Here, we show that the EBV noncoding RNA EBER2 accelerates B cell division through overexpression of cyclin B1 and of Aurora kinases. Mechanistically, we found that EBER2 induces the expression of the UCHL1 deubiquitinase that itself modulates expression of the cell-cycle proteins. Interestingly, this effect is modulated by the lineage of the infected cell and by polymorphisms within the viral genome.
The development of derivation in early Greek first language
acquisition
Authors: Stephany Ursula
Published: October 2021

This study is concerned with the development of
derivational prefixation and suffixation in early Greek language acquisition
and is based on the speech of a monolingual Greek girl from 1;8 to 3;0 years
in interaction with her mother (Katis Corpus). The most productive
derivational affixes are verbal prefixes while derivational suffixes prevail
in adjectives and nouns. Special attention is paid to the development of
word families (lexemes sharing a base) and word series (sets of derivatives
sharing a derivational affix) in the child’s lexicon and to a comparison
with child-directed speech. The study is committed to usage-based approaches
to language acquisition according to which “language structure emerges from
language use” (Tomasello
2003: 327) and productivity arises within item-based schemas.
Emergence and early development of derivatives in Danish child
language
Authors: Kjærbæk Laila , Basbøll Hans
Published: October 2021

This chapter is a first attempt to describe and
characterize the development of derivational morphology in monolingual
Danish-speaking children’s early spontaneous speech. It introduces the
Danish derivational system and gives an overview of the most common
derivational types in Danish, emphasizing the interaction between derivation
and prosody. It analyses derivatives in a corpus of
parent-child-interactions and discusses factors impacting early development
of derivatives. The results show that conventional derivatives appear from
age 1;3–1;7. The most frequent derivatives and derivational patterns in
child speech are also among the most frequent in child-directed speech. Only
a very small inventory of derivational patterns has emerged up to age 3;11,
and only vague traces of an emerging knowledge of productive derivation are
found.
Early phases of development of German derivational morphology
Authors: Sommer-Lolei Sabine , Mattes Veronika , Korecky-Kröll Katharina , Dressler Wolfgang U.
Published: October 2021

This chapter presents for the first time an overall
description of the development of German derivational morphology. The
longitudinal spontaneous speech corpora of three children acquiring Standard
Austrian German and their mothers is analysed up to 3;0, with outlooks up to
6;0. The analysis focusses on nominal, verbal and adjectival derivation
patterns that play a role at this early age, as well as on age and order of
emergence, productive use and development of various patterns and its
possible correlation to the respective input. The mini-paradigm criterion is
extended to derivational morphology for attesting potential productivity in
child speech. Only a very small inventory of derivational patterns is
acquired up to 3;0; acquisition of derivation accelerates remarkably during
preschool age.
The acquisition of the Lithuanian derivational system
Authors: Kamandulytė-Merfeldienė Laura , Balčiūnienė Ingrida , Dabašinskienė Ineta
Published: October 2021

This study is based on the longitudinal corpus data of
two Lithuanian children (1;7–2;7). The aim of the research is to analyse the
production of suffixed and prefixed nouns, verbs, and adjectives in CS and
CDS during the early stages of the acquisition of Lithuanian morphology. The
acquisition of the Lithuanian derivational system seems to be quite an
effortless process. Although a considerable number of errors occurred at the
initial stages, the first derivational families emerged already at the age
of 1;8–1;9, and the number of errors started to decrease rapidly. The period
during which the first derivatives emerge in child speech corresponds to the
transition from a premorphological to a protomorphological stage.
Positronium emission from GaN(0001) and AlN(0001) surfaces
Authors: Kawasuso A , Maekawa M , Miyashita A , Wada K , Nagashima Y , Ishida A
Published: October 2021

Positronium emission from wurtzite GaN(0001) and AlN(0001) surfaces was observed by positronium time-of-flight spectroscopy. The positronium energy spectra contained two positronium components distinguished by their energies. Through detailed analyses based on Monte Carlo simulations, these two components were attributed to positronium formed from valence and conduction electrons. The obtained results augment the previous arguments regarding the contribution of conduction electrons to positronium emission from 4H SiC(0001) and Si(111) surfaces.
Superior resistance switching in monolayer MoS2 channel-based gated binary resistive random-access memory via gate-bias dependence and a unique forming process
Authors: Ansh  , Shrivastava Mayank
Published: October 2021

Resistance switching (RS) in 2D molybdenum disulfide (MoS2) was recently discovered. Since the discovery, many reports demonstrating MoS2 resistive random-access memory (RRAM) with synapse-like behavior have been published. These reports strongly justify applications of MoS2 RRAM in neuromorphic hardware as well as an alternative to conventional binary memories. In this work, we unveil the effect of RS, induced by current–voltage hysteresis cycles across CVD-grown monolayer MoS2-based gated RRAM, on its transistor’s electrical and reliability characteristics. A unique gate voltage dependence on the RS is identified which has a remarkable impact on the switching performance of MoS2 RRAM. RS behavior was found to be significantly dependent on the charge conduction in the channel. Moreover, we have shown a potential device-forming event when MoS2-gated RRAMs were subjected to a steady-state electrical stress. Both hysteresis and steady-state electrical stress were found to disturb the transistor action of these gated RRAMs, which can in fact be used as a signature of RS. Interestingly, current–voltage hysteresis resulted in unipolar RS, whereas steady-state electrical stress before RS measurement led to bipolar RS. Moreover, successive stress cycles of such electrical stress lead to multiple resistance states, a behavior similar to synaptic properties such as long-term potentiation and long-term depression, typically found in memristors. We find that the charge transport mechanism dominant in the MoS2 FET, in conjunction with steady-state stress-induced device forming, determine the extent of RS induced in thes MoS2-based gated RRAMs. Finally, on the basis of insights developed from the dependence on the charge transport mechanism and steady-state stress-induced forming of the MoS2 channel, we propose a certain steady-state electrical stress condition which can be used as a ‘forming’ process, employed prior to the use of MoS2-based binary RRAMs for improved switching performance.