bluuebunny/crossref_metadata_2025 huggingface dataset:
All-yarn triboelectric nanogenerator and supercapacitor based self-charging power cloth for wearable applications
Authors: Ren Xiaohu , Xiang Xinyu , Yin Hongfeng , Tang Yun , Yuan Hudie
Published: April 2021

Despite rapid developments, multifunctional wearable electronics are still not significant in practical applications as compared to portable and stretchable power devices. In this paper, we present the flexible and easy large-scale production of single-electrode mode triboelectric nanogenerator (TENG) and supercapacitor yarn-based self-charging power fabric, for simultaneously converting and storing biomechanical energy. Fabricated using traditional knitting technologies, the self-charging power fabric can adapt to complex mechanical deformations owing to its high flexibility and stretchability. Additionally, the output characteristics of the TENG fabric were systematically investigated with the purpose of energy generation. The TENG fabric can generate a maximum peak power density of ∼90 mW·m−2 using nylon as the contact material, with an operating frequency of 4 Hz. The as-prepared yarn-based supercapacitor exhibited high capacitance, good cycling stability, and flexibility, making it an appropriate wearable energy-storage device. Moreover, the proposed design uses energy harvested from biomechanical motions to sustainably power portable electronic devices. The results of this study indicate that the proposed design is a promising sustainable power source for wearable electronic devices.
A deformable wireframe in a uniform magnetic field
Authors: Rizcallah Joseph A
Published: April 2021

The net force and net torque exerted by a uniform magnetic field on a rigid current-carrying loop are discussed in all introductory physics textbooks. A notable omission, however, is the discussion of the equilibrium of a deformable current-carrying loop in a uniform magnetic field. In the article, we present such an analysis for the simplest case of a quadrilateral current-carrying wireframe placed in a uniform magnetic field. We discuss the area-maximizing effect of the field on the frame and use the conditions of translational and rotational equilibrium to establish the ‘cyclicity’ of the latter as well as the uniformity of the magnitude of the contact forces acting at its joints.
Overview of plasma rotation studies on the TCABR tokamak
Authors: Severo J H F , Canal G P , Ronchi G , Andrade N B , Fernandes T , Ikeda M Y , Collares M P , Galvão R M O , Nascimento I C , Tendler M
Published: April 2021

An overview of intrinsic plasma rotation studies in Ohmic L-mode discharges carried out in the Tokamak Chauffage Alfvén Brésilien (TCABR) tokamak is presented. Measurements of plasma poloidal and toroidal rotation, and a comparison against neoclassical theory, are presented. The results show that poloidal rotation is in good agreement with neoclassical theory while toroidal rotation is found to be anomalous. A new technique that allows for high temporal resolution measurements of plasma rotation is presented. This technique is used to test two models of intrinsic toroidal rotation: the so-called Helander model (Helander et al 2003 Physics of Plasmas
10 4396) and Rozhansky model (Rozhansky 2013 Perpendicular currents and electric fields in fully and partially ionized magnetized plasma Physics of Plasmas
24 101614). As TCABR is a relatively small device, the influence of the neutrals that form the basis of this model is expected to be enhanced. The results indicate that the mechanism proposed by Helander does not contribute significantly to the intrinsic toroidal rotation in TCABR plasmas. The measurements, however, indicate that the frictional force proposed by Rozhansky might be responsible for part of the intrinsic toroidal rotation observed in TCABR plasmas.
Untethered rotational system with a stacked dielectric elastomer actuator
Authors: Minaminosono Ayato , Shigemune Hiroki , Murakami Taichi , Maeda Shingo
Published: April 2021

An untethered system can realize wide-area activities of soft robots. Herein we develop an untethered DEA wheel (UD-wheel) with a dielectric elastomer actuator (DEA). DEA is a soft actuator driven by electrostatic force. This UD-wheel is a new rotating device that integrates an untethered system and stacked DEAs. The untethered system consists of a small battery and a small high-voltage circuit. All the components are assembled seamlessly. Because the circuit can control four DEAs, the active time that the circuit continues to control the DEAs with a small battery is estimated. The estimated time matches the experimental result. We evaluated the output torque and back-drivability achieved by stacked DEAs installed in a UD-wheel. We also built a theoretical model for an in-depth evaluation. The stacking DEAs method provides a better back-drivability than the reducer method. This study suggests that our untethered rotational system may provide novel functions in soft robotics.
Extracting piezoresistive response of self-sensing cementitious composites under temperature effect via Bayesian blind source separation
Authors: Ding Siqi , Xu Chi , Ni Yi-Qing , Han Baoguo
Published: April 2021

Abstract

Self-sensing cementitious composite (SSCC) has been viewed as a promising sensing technology for structural health monitoring and traffic detection on account of its high sensitivity, low cost, long-term stability and compatibility with concrete structures. However, temperature variation effects in the electrical resistance measurements would impede the potential application of SSCC. It is therefore of great significance to understand the temperature effects on the piezoresistive performance of SSCC and eliminate such effects. In this study, temperature effects on the electrical and piezoresistive properties of SSCCs with different contents of carbon nanotube/nano carbon black (CNT/NCB) composite fillers are investigated under varying temperatures ranging from −20 °C to 60 °C and under concurrent temperature and loading variations. Experimental results show that an increase in CNT/NCB composite filler content can decrease the activation energy of SSCC and facilitate the transport of the charge carriers, thus attenuating the sensitivity of SSCC to temperature. Temperature variation has no effect on the piezoresistive repeatability of SSCC due to the stable overall distribution of conductive network in SSCC. However, temperature rise can reduce the piezoresistive sensitivity of SSCC. Aiming to diminish the effect of temperature on the piezoresistive property of SSCC, the SSCC responses to simultaneous temperature and loading excitations are then treated using a Bayesian blind source separation (BSS) method to reconstruct two independent sources. Regardless of the CNT/NCB composite filler content, the reconstructed source in relation to temperature variation always has a high correlation with the measured temperature, indicating that the proposed Bayesian BSS method can well extract and separate the electrical resistance variation induced by temperature variation from that induced by simultaneous temperature and loading excitations.
Removing the orientational degeneracy of the TS defect in 4H–SiC by electric fields and strain
Authors: Rühl Maximilian , Lehmeyer Johannes , Nagy Roland , Weisser Matthias , Bockstedte Michel , Krieger Michael , Weber Heiko B
Published: April 2021

We present a photoluminescence (PL) study of the recently discovered TS defect in 4H silicon carbide. It investigates the influence of static electric fields and local strain on the spectral properties by means of low temperature (≈4 K) ensemble measurements. Upon application of static electric fields exerted by graphene electrodes, line splitting patterns are observed, which are investigated for four different angles of the electric field with respect to the principal crystallographic axes. More detailed information can be gained when additionally the excitation polarization angle is systematically varied. Altogether, the data allow for extracting the direction of the associated electric dipole moments, revealing three distinct orientations of the underlying TS defect inside the crystal’s basal plane. We also present three so far unreported PL lines (836.7 nm, 889.7 nm, 950.0 nm) as candidates for out-of-plane oriented counterparts of the TS lines. Similar to symmetry breaking by the electric field applied, strain can reduce the local symmetry. We investigate strain-induced line splitting patterns that also yield a threefold directedness of the TS lines in accordance with the Stark effect measurements. The response to both electrical and strain fields is remarkably strong, leading to line shifts of ±12 meV of the TS1 line. Combining our findings, we can narrow down possible geometries of the TS defect.
Formation of self-organized structures in internal conductor plasma
Authors: Gondal S M , Iqbal M
Published: April 2021

A possibility of the confinement of two-fluid (electrons and ions) magnetized plasma in a simple cylindrical configuration as well as in a cylindrical geometry with an internal conductor is analyzed. By controlling the characteristics roots of Triple Beltrami state the formation of diamagnetic and paramagnetic structures is investigated for a simple cylindrical geometry. For an internal conductor system, the nature of relaxed structures is only paramagnetic. These paramagnetic structures are independent of the type of the characteristics roots. The results of the present investigation will be helpful to explain the equilibrium structure in the astrophysical objects such as Jupiter magnetosphere which is co-rotated with the planet and in the laboratory.
An extended version of the spin-one Duffin–Kemmer–Petiau oscillator
Authors: Chargui Y , Dhahbi A
Published: April 2021

We study a covariant extension of the spin-one DuffinKemmerPetiau (DKP) oscillator constructed by combining a Lorentz tensor spin–orbit coupling with the basic DKP oscillator one. We show that this model has a spin-orbit splitting controllably independent from oscillator shells and admits exact analytical solutions for both natural and unnatural parity states. The corresponding energy spectrum is then obtained for any value of the total angular momentum number and a drastic change in its structure is observed due to the additional spin–orbit coupling. In particular energy bounds and, in some cases, forbidden energy ranges are noted.
Local quantum uncertainty in a two-qubit Heisenberg spin chain with intrinsic decoherence
Authors: Guo You-neng , Peng Hu-ping , Tian Qing-long , Tan Zhi-guang , Chen Ying
Published: April 2021

Quantum correlation plays an important role in quantum information processing, for which various quantifiers have been proposed so far. In this paper, we address the dynamics of local quantum uncertainty (LQU) as a reliable quantifier of quantum correlation in a two-qubit Heisenberg spin chain in the presence of nonuniform external magnetic field and Dzyaloshinski-Moriya interaction with intrinsic decoherence. The influences of the initial states, external magnetic field strength, Dzyaloshinski-Moriya interaction strength and intrinsic decoherence rate on the dynamics of LQU have been in detail investigated. Our analytical results show that the dynamics of LQU is strongly depended on the form of initial states. For an initial correlated state, the dynamical behaviors of LQU exhibit either monotonic decay or damped oscillations with respect to time. While for an initial separable state, quantum correlation quantified by LQU can be created due to the Dzyaloshinski-Moriya interaction and Heisenberg anisotropic interaction. Besides, the relationship between LQU and l-norm coherence or concurrence is also demonstrated in the present model.
Transverse waves incident at the free surface of an initially stressed dissipative half-space
Authors: Selim Mahmoud M , Gepreel Khaled A
Published: April 2021

In this work, an attempt is done to apply Biot`s incremental deformation theory to find out the effects of initial stresses on the reflected transverse waves (S-waves) at a free surface of dissipative half-space medium. Equations of motion and its corresponding solutions are derived in lights of Biot`s theory. The impact of initial stresses and medium`s dissipation on the reflected transverse wave are studied in detail. Numerical calculations carried out using Aswan geological crustal structure and the results are presented graphically. Numerical findings reveal that, the initial stresses and the medium dissipation effects the reflection coefficients of transverse wave considerably. In addition, it has been noted that, the phase velocity decreases considerably as the initial stress parameter increases. Since the crust of the Earth, , is dissipative and initially stressed medium, thus understanding the effects of these parameters may help seismologists to get accurate results of reflected seismic transverse wave at the surface of Earth crust.
Structural and ultraviolet photo-detection properties of laser molecular beam epitaxy grown GaN layers using solid GaN and liquid Ga targets
Authors: Mauraya Amit Kumar , Mahana Debashrita , Tyagi Prashant , Ramesh Ch , Shukla Ajay Kumar , Husale Sudhir , Kushvaha Sunil Singh , Senthil Kumar Muthusamy
Published: April 2021

GaN epitaxial layers have been grown on sapphire (0001) substrate by laser molecular beam epitaxy technique using laser ablation of polycrystalline GaN solid and liquid Ga metal targets in the ambient of nitrogen plasma. In-situ reflection high energy electron diffraction and exsitu atomic force microscopy observations revealed that GaN growth using solid target yields rough surface under three-dimensional growth mode while a flat surface GaN is obtained using liquid Ga target. From X-ray rocking curve measurement, it is also observed that the GaN layer grown using solid GaN target has a relatively better structural quality. X-ray photoelectron spectroscopy confirmed Ga–N bond formation and near-stoichiometric composition of the GaN epilayers. The influence of threading dislocation density on the ultraviolet (UV) photoresponse properties of GaN layers have been studied using metal-semiconductor-metal (MSM) based device structure. It is found that the GaN MSM structure obtained using solid GaN target with lesser screw and dislocation densities exhibits a higher responsivity with fast response and recovery time.
High-order localized waves in the (2+1)-dimensional Ito equation
Authors: Zhang Xiaoxue , Wang Chuanjian , Zhou Yuefeng
Published: April 2021

In this paper, we mainly investigate the high-order localized waves in the (2+1)-dimensional Ito equation. By introducing a translation parameter and employing the Hirota derivative operator, we construct and analyze three kinds of high-order localized waves with a translation parameter: high-order line soliton, lump-type localized wave and their hybrid solutions. The obtained results show that nonlinear localized waves with a translation parameter have more plentiful dynamical behaviors. It is shown that the plus and minus resonance phenomena of two line solitons can be controlled by a translation parameter. The direction of propagation and symmetry characteristics of lump-type localized wave can be also governed by this translation parameter. Through analyzing the time delay effect we finally discuss and demonstrate the absorb-emit and emit-absorb interactions between a line soliton and a lump-type localized wave.
Thermo-bioconvection transport of nanofluid over an inclined stretching cylinder with Cattaneo–Christov double-diffusion
Authors: Waqas Hassan , Manzoor Umair , Muhammad Taseer , Hussain Sajjad
Published: April 2021

In this paper, Newtonian nanofluid flow is observed under the effects of the magnetic field, activation energy and motile microorganisms over an inclined stretchable cylinder. The magnificent aspects of nanoliquid are demonstrated by enduring the Brownian motion and thermophoresis diffusion features. Nonlinear higher order partial differential equations are transformed into first-order ordinary differential equations with suitable similarity variables. The attained sets of governing equations are then cracked by bvp4c procedure in MATLAB mathematical software. The numerical and graphical outcomes of controlling parameters such as Prandtl number, mixed convection, activation energy, thermophoresis, Brownian parameter, Biot number, Lewis number, Peclet number and motile concentration parameter against the velocity, temperature, volumetric concentration and motile concentration of nanoparticles of the fluid are discussed. The velocity is enhanced with the growth valuation in mixed convection and decay by rising variation of buoyancy ratio parameter, magnetic parameter and bio-convective Rayleigh parameter. The evolution in motile microorganisms is due to the increasing values of microorganisms Biot number. The presented data can be helpful in enhancement of manufacturing processes, biomolecules, extrusion systems applications and energy production improvement.
Helium-hydrogen synergistic effects on swelling in in-situ multiple-ion beams irradiated steels*
Authors: Liu Haocheng , Huang Jia , Cao Liuxuan , Su Yue , Gao Zhiying , Ma Pengfei , Xia Songqin , Ge Wei , Liu Qingyuan , Zhao Shuang , Wang Yugang , Huang Jinchi , Zhou Zhehui , Zheng Pengfei , Wang Chenxu
Published: April 2021

The development of reliable fusion energy is one of the most important challenges in this century. The accelerated degradation of structural materials in fusion reactors caused by neutron irradiation would cause severe problems. Due to the lack of suitable fusion neutron testing facilities, we have to rely on ion irradiation experiments to test candidate materials in fusion reactors. Moreover, fusion neutron irradiation effects are accompanied by the simultaneous transmutation production of helium and hydrogen. One important method to study the He–H synergistic effects in materials is multiple simultaneous ion beams (MSIB) irradiation that has been studied for decades. To date, there is no convincing conclusion on these He–H synergistic effects among these experiments. Recently, a multiple ion beam in-situ transmission electron microscopy (TEM) analysis facility was developed in Xiamen University (XIAMEN facility), which is the first triple beam system and the only in-running in-situ irradiation facility with TEM in China. In this work, we conducted the first high-temperature triple simultaneous ion beams irradiation experiment with TEM observation using the XIAMEN facility. The responses to in-situ triple-ion beams irradiation in austenitic steel 304L SS and ferritic/martensitic steel CLF-1 were studied and compared with the results in dual- and single-ion beam(s) irradiated steels. Synergistic effects were observed in MSIB irradiated steels. Helium was found to be critical for cavity formation, while hydrogen has strong synergistic effect on increasing swelling.
Effects of electric fields on 7Be half-life
Authors: Gholamian Farshid , Firoozabadi Mohammad Mehdi , Sarhaddi Reza
Published: April 2021

First-principle calculations based on the density functional theory (DFT) method are adopted to investigate the influence of a strong electric field on the 7Be half-life. Accordingly, electronic structures of Be and BeO are examined in the presence of a homogeneous electric field. The electron density at the nucleus is estimated upon the geometry optimization. Our computations for the Be metal indicate a 0.02% increase in the decay rate of the 7Be nucleus, corresponding to a 0.02% decrease in the 7Be half-life, both at 5.14 V/Å (0.1 a.u.). Furthermore, it is determined that the decay rate of 7Be is not considerably altered up to 3.6 V/Å in the BeO structure. Our results show that the screening energy of the electron can be dependent on the applied electric field strength. Furthermore, we predict variations in the Coulomb potential at the 7Be nucleus due to electric field application.
Consolidation of memory traces in cultured cortical networks requires low cholinergic tone, synchronized activity and high network excitability
Authors: Dias Inês , Levers Marloes R , Lamberti Martina , Hassink Gerco C , van Wezel Richard , le Feber Joost
Published: April 2021

In systems consolidation, encoded memories are replayed by the hippocampus during slow-wave sleep (SWS), and permanently stored in the neocortex. Declarative memory consolidation is believed to benefit from the oscillatory rhythms and low cholinergic tone observed in this sleep stage, but underlying mechanisms remain unclear. To clarify the role of cholinergic modulation and synchronized activity in memory consolidation, we applied repeated electrical stimulation in mature cultures of dissociated rat cortical neurons with high or low cholinergic tone, mimicking the cue replay observed during systems consolidation under distinct cholinergic concentrations. In the absence of cholinergic input, these cultures display activity patterns hallmarked by network bursts, synchronized events reminiscent of the low frequency oscillations observed during SWS. They display stable activity and connectivity, which mutually interact and achieve an equilibrium. Electrical stimulation reforms the equilibrium to include the stimulus response, a phenomenon interpreted as memory trace formation. Without cholinergic input, activity was burst-dominated. First application of a stimulus induced significant connectivity changes, while subsequent repetition no longer affected connectivity. Presenting a second stimulus at a different electrode had the same effect, whereas returning to the initial stimuli did not induce further connectivity alterations, indicating that the second stimulus did not erase the ‘memory trace’ of the first. Distinctively, cultures with high cholinergic tone displayed reduced network excitability and dispersed firing, and electrical stimulation did not induce significant connectivity changes. We conclude that low cholinergic tone facilitates memory formation and consolidation, possibly through enhanced network excitability. Network bursts or SWS oscillations may merely reflect high network excitability.
Examination of stiff ion temperature gradient mode physics in simulations of DIII-D H-mode transport
Authors: Holland C. , Luce T.C. , Grierson B.A. , Smith S.P. , Marinoni A. , Burrell K.H. , Petty C.C. , Bass E.M.
Published: April 2021

A systematic evaluation of gyrokinetic and gyrofluid model predictions of ion temperature gradient (ITG) stability and transport using parameters from DIII-D high confinement mode (H-mode) plasmas has been performed. The nonlinear CGYRO code is used to make the gyrokinetic predictions, and the quasilinear TGLF model for the corresponding gyrofluid predictions. The assessments are made at three radii (normalized toroidal flux ρ
tor = 0.4, 0.55, and 0.7) in three different plasma scenarios with varying levels of neutral beam heating and torque. For each of the nine cases (3 radii × 3 scenarios) considered, ITG turbulence is found to be the dominant long-wavelength instability and transport mechanism. The inclusions of both transverse magnetic fluctuations and dynamic fast beam ions are stabilizing for all cases considered, with strongest effects seen at ρ
or = 0.4 where the fast ion population and normalized plasma pressure β = 2μ
0
nT/B
2 are highest. The further inclusion of parallel magnetic fluctuations does not have a meaningful impact on the ITG turbulence in these scenarios, but does destabilize (in combination with fast ions) new high-frequency instabilities at ρ
tor = 0.4 in the high power scenarios. In each case the linear and nonlinear ITG critical gradients are predicted to be lower than the measured ITG scale lengths and their associated uncertainties. Inclusion of equilibrium flow shear in the transport predictions generally leads to an upshift in effective critical gradient rather than a qualitative change in the predicted stiffness, with stronger responses typically seen in the gyrokinetic predictions than in the gyrofluid results. However, in most cases these upshifted gradients still remain below the measured values and their uncertainties. Although the predicted critical gradients are below the measured gradients, both models predicted flux-matching gradients consistent with measured values in six of the nine cases considered, with no clear systematic over- or underprediction. Thus, while the experimental ion temperature profiles do not appear to be closely pinned to the ITG critical gradient, both gyrokinetic and gyrofluid models are able to accurately match the measured gradients reasonably well in most cases.
Material migration in W and Mo during bubble growth and fuzz formation
Authors: Patino M.I. , Nishijima D. , Tokitani M. , Nagata D. , Yu J.H. , Doerner R.P.
Published: April 2021

Growth of helium (He) induced bubbles and fuzz in tungsten (W) and molybdenum (Mo) is investigated using samples of W films on Mo substrates and Mo films on W substrates exposed to He-containing plasma in the temperature range of 340 to 1075 K, fluence range of 1.0–14 × 1025 He·m−2, and incident ion energy of <50 eV. No fuzz (only up to 2 nm diameter bubbles) and no material transport occur in W films at ⩽750 K, while precursors-of or fully-developed fuzz and material mixing occur in W and Mo films at ⩾800 K. This suggests that fuzz forms in multi-material systems as long as one material meets the conditions for fuzz formation, namely T
s/T
m ∼ 0.27–0.5 where T
s and T
m are the sample exposure and material melting temperatures, respectively. Larger He bubbles, more material mixing, and further-developed fuzz occur at higher temperature due to increased mobility of He atoms and small He clusters. Accumulation of substrate material at the surface of fuzzy W and Mo thin-film (<80 nm) samples suggests fuzz growth by material transport from the bubble layer in the bulk up to the fiber tip, likely by a two-step process: (i) diffusion of punched dislocation loops in the bulk toward the fuzz base and (ii) diffusion of adatoms along the fuzz base and fiber surface (with effective transport of adatoms upwards due to trapping of adatoms at curved surfaces of fiber tips and/or due to the continuous generation of adatoms at the fuzz base). While the bubble size and fuzz thickness increase with reduced W concentration in Mo thin-film samples at 838 K likely due to an increase in trap mutation and dislocation loop punching in Mo compared to W, the fuzz thickness decreases with reduced W concentration at 1075 K despite an increase in the bubble size likely due to slower diffusion of interstitial loops in Mo.
The EEE Multigap Resistive Plate Chambers as tracking devices to monitor the stability of a civil building
Authors: Pinto C. , Abbrescia M. , Avanzini C. , Baldini L. , Baldini Ferroli R. , Batignani L.G. , Battaglieri M. , Boi S. , Bossini E. , Carnesecchi F. , Cicalò C. , Cifarelli L. , Coccetti F. , Coccia E. , Corvaglia A. , De Gruttola D. , De Pasquale S. , Fabbri L. , Galante L. , Galeotti P. , Garbini M. , Gemme G. , Gnesi I. , Grazzi S. , Hatzifotiadou D. , La Rocca P. , Liu Z. , Mandaglio G. , Maron G. , Mazziotta M.N. , Mulliri A. , Nania R. , Noferini F. , Nozzoli F. , Palmonari F. , Panareo M. , Panetta M.P. , Paoletti R. , Pellegrino C. , Perasso L. , Piragino G. , Pisano S. , Riggi F. , Righini G.C. , Ripoli C. , Rizzi M. , Sartorelli G. , Scapparone E. , Schioppa M. , Scribano A. , Selvi M. , Serri G. , Squarcia S. , Taiuti M. , Terreni G. , Trifiró A. , Trimarchi M. , Vistoli M.C. , Votano L. , Williams M.C.S. , Zichichi A. , Zuyeuski R.
Published: April 2021

Due to their efficiency, tracking capabilities and long-term
operational conditions, Multigap Resistive Plate Chambers (MRPC) may
be used in a stable location in coincidence with additional
detectors fixed to other parts of a civil building, to detect
relative displacements of different parts of the building due to
long term deformations of the structure. In this contribution we
report the results of two different measurements carried out in the
Department of Physics and Astronomy of the University of Catania
(with three floors above the ground and an underground basement),
using one of the MRPC telescopes of the Extreme Energy Events
project, in coincidence with two scintillator-based muon telescopes
located in various positions inside the building. Experimental
results obtained by these measurements campaigns over a period of
about three months are reported, together with a discussion about
the performance of the technique. The sensitivity of the method is
also discussed by means of Monte Carlo simulations.
Gas mixture quality studies for the CMS RPC detectors during LHC Run 2
Authors: Gelmi A. , Guida R. , Mandelli B.
Published: April 2021

Resistive Plate Chamber (RPC) detectors are widely employed in the muon trigger systems of three experiments at the CERN Large Hadron Collider (LHC). They are operated with gas mixture recirculation systems to reduce operational costs and greenhouse gas emissions since their gas mixture is based on C2H2F4, which has a high global warning potential. It is well known that the C2H2F4 molecule can break down under the effect of radiation and electric field. This leads to the creation of several impurities and free fluoride ions (F-), which could accumulate under gas recirculation and potentially attach to the RPC bakelite electrode inner surface. For these reasons, an extensive gas analysis campaign has been performed during LHC Run 2 for the CMS RPC system to verify gas mixture quality and possible accumulation of impurities.

During the entire LHC Run 2 period, a gas chromatograph has been used to analyze the RPC gas mixture at different points of the gas system: quality of pure C2H2F4, fresh gas from the mixer, gas at the output of the detectors, and after the purifier module. Several impurities have been found and identified. Few impurities are already present in the C2H2F4 supply, as residuals of the industrial production. Nevertheless, it was found that some of these impurities, as well as others, are created inside the detector gas gap due to the fragmentation of the C2H2F4 molecule under the effects of electric field and radiation.

During the 2018 LHC Run several gas analysis points were added to measure the fluoride ions production in different sectors of the RPC detector system. Indeed the products of the C2H2F4 fragmentation do not always recombine and F- species can stay free in the gas mixture. F- analyses were performed on the gas at the output of the detectors both for barrel and endcap regions, where radiation levels and operational conditions were different. In this way, it was possible to correlate the F- production with integrated charge, and gas mixture flow rate. In parallel, the RPC currents have been constantly monitored to look for possible correlations.
Fluoride measurements have also been performed at GIF++ to better understand the correlation between F- production, radiation levels and gas volume exchanges.

A comprehensive overview of the results obtained from the different types of gas analyses and possible correlation with RPC currents and LHC luminosity will be presented.
Biocompatibility of platinum-based bulk metallic glass in orthopedic applications
Authors: Loye Ayomiposi M , Kwon Hyuk-Kwon , Dellal David , Ojeda Rodrigo , Lee Sangmin , Davis Rose , Nagle Natalie , Doukas Panagiotis G , Schroers Jan , Lee Francis Y , Kyriakides Themis R
Published: April 2021

Bulk metallic glasses (BMGs) are a class of amorphous metals that exhibit high strength, ductility paired with wear and corrosion resistance. These properties suggest that they could serve as an alternative to conventional metallic implants that suffer wear and failure. In the present study, we investigated Platinum (Pt)-BMG biocompatibility in bone applications. Specifically, we investigated osteoclast formation on flat and nanopatterned Pt57.5Cu14.7Ni5.3P22.5 (atomic percent) as well as titanium (control). Specifically, receptor activator of NF-κB (RANK) ligand-induced murine bone marrow derived mononuclear cell fusion was measured on multiple nanopatterns and was found to be reduced on nanorods (80 and 200 nm in diameter) and was associated with reduced tartrate-resistant acid phosphatase (TRAP) and matrix metalloproteinase (MMP9) expression. Evaluation of mesenchymal stem cell (MSC) to osteoblast differentiation on nanopatterned Pt-BMG showed significant reduction in comparison to flat, suggesting that further exploration of nanopatterns is required to have simultaneous induction of osteoblasts and inhibition of osteoclasts.In vivo studies were also pursued to evaluate the biocompatibility of Pt-BMG in comparison to titanium. Rods of each material were implanted in the femurs of mice and evaluated by x-ray, mechanical testing, micro-computed tomography (micro-CT), and histological analysis. Overall, Pt-BMG showed similar biocompatibility with titanium suggesting that it has the potential to improve outcomes by further processing at the nanoscale.
Integrated assessment model diagnostics: key indicators and model evolution
Authors: Harmsen Mathijs , Kriegler Elmar , van Vuuren Detlef P , van der Wijst Kaj-Ivar , Luderer Gunnar , Cui Ryna , Dessens Olivier , Drouet Laurent , Emmerling Johannes , Morris Jennifer Faye , Fosse Florian , Fragkiadakis Dimitris , Fragkiadakis Kostas , Fragkos Panagiotis , Fricko Oliver , Fujimori Shinichiro , Gernaat David , Guivarch Céline , Iyer Gokul , Karkatsoulis Panagiotis , Keppo Ilkka , Keramidas Kimon , Köberle Alexandre , Kolp Peter , Krey Volker , Krüger Christoph , Leblanc Florian , Mittal Shivika , Paltsev Sergey , Rochedo Pedro , van Ruijven Bas J , Sands Ronald D , Sano Fuminori , Strefler Jessica , Arroyo Eveline Vasquez , Wada Kenichi , Zakeri Behnam
Published: April 2021

Integrated assessment models (IAMs) form a prime tool in informing about climate mitigation strategies. Diagnostic indicators that allow comparison across these models can help describe and explain differences in model projections. This increases transparency and comparability. Earlier, the IAM community has developed an approach to diagnose models (Kriegler (2015 Technol. Forecast. Soc. Change
90 45–61)). Here we build on this, by proposing a selected set of well-defined indicators as a community standard, to systematically and routinely assess IAM behaviour, similar to metrics used for other modeling communities such as climate models. These indicators are the relative abatement index, emission reduction type index, inertia timescale, fossil fuel reduction, transformation index and cost per abatement value. We apply the approach to 17 IAMs, assessing both older as well as their latest versions, as applied in the IPCC 6th Assessment Report. The study shows that the approach can be easily applied and used to indentify key differences between models and model versions. Moreover, we demonstrate that this comparison helps to link model behavior to model characteristics and assumptions. We show that together, the set of six indicators can provide useful indication of the main traits of the model and can roughly indicate the general model behavior. The results also show that there is often a considerable spread across the models. Interestingly, the diagnostic values often change for different model versions, but there does not seem to be a distinct trend.
Feynman-type representation of the scattering matrix on the line via a discrete-time quantum walk
Authors: Higuchi Kenta
Published: April 2021

The aim of this article is to relate the discrete quantum walk on

Z

with the continuous Schrödinger operator on

R

in the scattering problem. Each point of

Z

is associated with a barrier of the potential, and the coin operator of the quantum walk is determined by the transfer matrix between bases of WKB solutions on the classically allowed regions of both sides of the barrier. This correspondence enables us to represent each entry of the scattering matrix of the Schrödinger operator as a countable sum of probability amplitudes associated with the paths of the quantum walker. In particular, the barrier-top scattering corresponds to the Hadamard walk in the semiclassical limit.
Gel’fand–Yaglom type equations for calculating fluctuations around instantons in stochastic systems
Authors: Schorlepp Timo , Grafke Tobias , Grauer Rainer
Published: April 2021

In recent years, instanton calculus has successfully been employed to estimate tail probabilities of rare events in various stochastic dynamical systems. Without further corrections, however, these estimates can only capture the exponential scaling. In this paper, we derive a general, closed form expression for the leading prefactor contribution of the fluctuations around the instanton trajectory for the computation of probability density functions of general observables. The key technique is applying the Gel’fand–Yaglom recursive evaluation method to the suitably discretized Gaussian path integral of the fluctuations, in order to obtain matrix evolution equations that yield the fluctuation determinant. We demonstrate agreement between these predictions and direct sampling for examples motivated from turbulence theory.
A spatial prototype of natural ventilation in underground public spaces combining courtyard with wind tower
Authors: Wen Yueming , Leng Jiawei
Published: April 2021

Ventilation is the basis of controlling thermal comfort and air quality in underground spaces. Natural ventilation based on spatial designs can introduce wind, light, and scenery to improve environmental health and spatial experience, and reduce health risks and energy consumption of mechanical ventilation. This paper proposes a spatial prototype that combines courtyard with wind tower, two common spatial forms connecting aboveground and underground, and can provide effective natural ventilation to underground public spaces. Computational fluid dynamics simulations and genetic optimization were conducted in the common architectural software Rhinoceros and Grasshopper. First, spatial defects are identified and optimized by analysing the simulation results. Then, geometric variables of the spatial form that obviously affect the ventilation performance were selected and automatically optimized with the target of air volume per hour. Finally, three key issues for natural ventilation of underground public spaces are discussed including human comfort, air distribution, and ventilation reliability. This paper explores the coupling between the spatial form and ventilation performance of underground public spaces, which not only alleviates the potential conflict between energy saving and environmental health, but also provides an integrated design pattern to create more open, flexible, natural and sustainable underground spaces.
Ryazanskaya Transit Oriented Development
Authors: Ceccotto Arch. Stefano , Msaud
Published: April 2021

The Ryazanskaya Transit Oriented Development (TOD) is a large intervention included in Moscow’s 2030 urban planning, realizing a transit hub, commercial / retail spaces, an office tower and two metro/rail terminal buildings, to be built around a public park where ground transportation is also located. Within this master plan, the Terminal 2 integrates an underground transit hall to provide access for three mass transportation lines merging at Ryazanskaya TOD. Such urban-scale complex required international best practice architectural solutions, particularly focused onto the relationship between underground spaces and above-ground structures. The Ryazanskaya project is a case study useful to understand and explain the typical TOD urban design methodology, as a part of a large city-making process originated by the design of underground infrastructures and concluded with the architectural design of a strategic asset for the contemporary metropolis.
Study on Implementation Strategies of Multifunctional Linear Underground Space: A Case Study in Beijing’s sub-center
Authors: Wei Meng , Chen Pengbo , Su Yunlong
Published: April 2021

DEVELOPMENT CONTROL PLAN FOR THE SUB-CENTER OF BEIJING (2016-2035) says, a facility service ring with complex functions, balanced layout and integrated above ground and underground space will be constructed, which is efficient integrated underground infrastructure, with a total length of about 36.5 kilometers, coordinating the construction of circular underground systems such as subway, utility tunnel, urban underground logistics, and automatic garbage collection and transfer, and jointly building municipal facilities such as hidden municipal facilities, multi-level rainwater control and utilization facilities, emergency evacuation facilities, underground peak-storage and peak-regulation facilities. Aiming at the feasibility of the project, though analyzing in detail the present situation and planning of land use, pipeline and underground space along the ring and surrounding areas, and fully sorting out the functions and space demand characteristics of the major systems in the facility service ring, deeply explore the advanced technologies such as urban underground logistics and automatic garbage collection and transfer, and propose the inclusive and multifunctional underground space implementation strategies, for the meticulous use of underground space.
The main characteristics of urban underground space regulatory plan from the perspective of China’s spatial planning: A practice in Beijing Sub-Center
Authors: Chao Gao , Kejie Wu , Qin Chen
Published: April 2021

In order to better solve the new problems encountered in the national development, China is gradually establishing a new national territory spatial planning system. It can implement the requirements of whole-area and multi-element control of land and space. Underground space planning is a special planning in the new spatial planning system. We will explore how to scientifically and reasonably prepare underground space planning. Combined with the planning practice of Beijing and Sub-Center, we propose that the underground space planning system should be further improved, especially at the regulatory planning level. It can not only refine the master planning requirements of underground space, but also effectively guide the detailed planning and project construction of underground space. This paper attempts to put forward the main characteristics of underground space regulatory planning, hoping to provide reference for other cities’ underground space planning. The first is ecological priority and limited utilization. Detailed geological survey is the basis of underground space planning. In the Sub-Center, we evaluated the requirements of geological ecological protection and the impact of geological disasters, and delineated the three-dimensional utilization boundary of underground space and the influence scope of geological disasters. The second is the improvement of space management and space vitality. We explore the allocation method of underground space covered area, and divide the covered area into each construction site, giving priority to the key areas such as Universal Studios and metro station areas. The third is multi-dimensional utilization and planning integration. The underground facilities are planned in depth and intensively. The plan puts forward detailed in-depth layout guidance, focusing on the construction of Facility Service Ring, and coordinating the intensive construction of underground tunnels, metro and underground municipal facilities. The fourth is to encourage the application of new technologies. The planning will reserve sufficient space for future development, such as the construction of underground logistics, multistage rainwater collection and underground heat utilization in the Sub-Center.
The onset of underground urban planning in Flanders
Authors: Debrock S
Published: April 2021

Urban underground space (UUS) can be an effective means to meet the needs of the cities and simultaneously deal with societal and urban challenges. However, in Flanders the use of UUS remains to be one of the most forgotten urban assets and is characterised by a haphazard, uncoordinated ‘last resort’ practice detrimental to sustainable development. In a search for new possibilities for qualitative densification the Flemish Government instigated a policy exploration to investigate if efficient use of the UUS could be a possible solution for lowering the daily land take. This paper describes the process and content of the policy exploration and sets out policy recommendations. The paper concludes that although the merits of UUS have been thoroughly recognized and the significance of the subsurface in urban renewal is clear, the efficient use of UUS in Flanders and the fulfilment of Flemish policy objectives cannot be guaranteed without the development of UUS policy and the integration of UUS policy in the overall Flemish urban planning system. The research finds that a clear definition of planning factors for the use of UUS is necessary to support the transition from using the UUS to integration of the UUS into wider urban planning processes. It puts forward the need for a comprehensive list of planning factors, gathered in a holistic, integrated manner, necessary to transition from UUS projects to UUS planning.
Spatial accessibility and functional layout impacts on urban underground space development: a case study of Shanghai
Authors: Dong Yun-Hao , Peng Fang-Le , Xing Xiao , Wu Xiao-Lei
Published: April 2021

Over the past decade, China’s megacities such as Shanghai and Beijing have witnessed great progress in their metro networks. With the rapid development of metro system, urban underground space (UUS) in China has been widely utilized in a systematic manner, following the principles of transit-oriented development. A comprehensive understanding of the impacts of the built environment on UUS is doubtlessly conducive to the high-quality and sustainable urban development. However, there are fewer researches conducted to study the impacts on UUS compared with those studies focusing on ground level space. Moreover, quantitative researches using multi-source big data on underground space are limited, which makes it hard to reveal the development regulation with high-precision at a large scale. This paper aims to study the impacts of spatial accessibility and functional layout on UUS. Shanghai, as one of the most prosperous megacities in China with well-developed underground space, was selected as the case study. In this paper, open data from Open Street Map and Point of Interest (POI) in AMAP was adopted. Indices such as integration (index of space syntax) of metro line, road length, road density, POI density, and entropy of POI were chosen to reflect the spatial accessibility and functional layout. Underground POI (UPOI) density was set as a proxy of UUS development intensity. A quantitative analysis using multiple linear regression model was conducted. The results showed that both two kinds of indices strongly correlated to the underground space development, whereas the influences of selected indices on UUS were different. At last, the characteristics of UUS in Shanghai and further development strategies were discussed, which provided a perspective of smart growth for planners, designers and authorities.