bluuebunny/crossref_metadata_2025 huggingface dataset:
A non-Darcy gas flow model for coalbed methane in mine gobs
Authors: Ren Yiwei , Yuan Qiang , Jiang Deyi , Fan Jinyang , Liu Wenhao , Wei Like , Wang Zhen
Published: November 2021

The expected extraction efficiency of coalbed methane (CBM) depends significantly on the laws considered to govern its gas flow. This study applies a non-Darcy gas flow model to describe the CBM migration in mine gobs; by mine gob, we mean that it is a fractured zone along with massive cracks and the primary place where gas flows after mining activities. A permeation experiment involving crushed sandstone is first conducted to prove the CBM undergoes Forchheimer-type non-Darcy flow. Subsequently, the three-dimensional continuous distribution functions of the permeability parameters are determined. The non-Darcy flow model includes the influence of inertial force on the gas flow, which is neglected in the Darcy model. A coupling model is established based on the experimental results and the gas flow characteristics in different regions. Thereafter, the model and distribution functions are applied to a series of numerical simulations of CBM extraction at the Sihe coal mine in China, to ascertain the most appropriate location for a ground borehole. These simulations involve boreholes placed in three different zones: the natural accumulation zone (NAZ), the load affected zone (LAZ), and the compaction stable zone (CSZ). The simulation results show that the total extraction quantity expected from the borehole in the NAZ is 2.4 and 13.5 times that from the boreholes in the LAZ and CSZ, respectively. This confirms that the NAZ is the most suitable zone for a borehole. This research ultimately provides a realistic gas flow model for CBM extraction from mine gobs.
Cavity dynamics following the vertical entry of different-density spheres into a stratified system of viscous liquid floating on water
Authors: Sun Tiezhi , Zhang Rundong , Zhang Guiyong
Published: November 2021

This paper explores the physical phenomena of different-density spheres passing vertically through a stratified liquid containing high-viscosity dimethicone on the water surface. High-speed photography to monitor the cavity evolution and a hydrophone used to record the acoustic features. The results show that the thickness of the dimethicone layer and the density of the sphere have a significant impact on the shape of the splash crown, especially regarding the form of surface sealing and the time at which it occurs. As the thickness of the dimethicone layer increases and the density of the sphere decreases, the shrinkage time of the splash crown of the water layer is delayed, and the number of surface sealing events tends to decrease. Furthermore, the thickness of the dimethicone layer has a significant effect on the deep pinch-off phenomenon for high-density spheres and exhibits a weaker influence on low-density spheres. Moreover, examination of the acoustic signals indicates that the cavity evolution is closely related to acoustic properties, and the thickness of the dimethicone layer presents different effects at different stages of the entering process. These results indicate that the dimethicone layer and the density of the spheres have a considerable influence on cavity development and acoustic features in the wake of water entry.
Electrohydrodynamic conduction pumping of a viscoelastic dielectric fluid with the Onsager–Wien effect
Authors: Chen Di-Lin , Luo Kang , Wu Jian , Yi Hong-Liang
Published: November 2021

Due to the Onsager–Wien effect (enhanced electric field dissociation), electrohydrodynamic (EHD) conduction pumping problems in the Oldroyd-B viscoelastic dielectric liquid are solved using the finite volume method. Fully coupled nonlinear equations, including the Naiver–Stokes (N–S) equation, the Nernst–Plank equation of the ion conduction mechanism, and the constitutive equation of viscoelastic fluid, are thoroughly implemented. Our numerical model is fully verified with two benchmark cases, and simulations are performed under different conduction numbers C0 (0.01–103), Weissenberg numbers Wi (0.01–50), and viscosity ratios (0.3–0.9). Two limiting operating states of EHD conduction pumping, the Ohmic and the saturation regimes, are discussed in detail. Elastic instability is more likely to occur in the Ohmic regime, and the thickness of the heterocharge layer (called the dissociation layer) remains sensitive to C0 and the elasticity values. Current density and pressure generation show crucial degrees of dependence on the fluid elasticity and viscosity ratio.
Vortex-induced rotations of two side-by-side square cylinders in a two-dimensional microchannel
Authors: Li Lichun , Yan Zhe , Pan Zhenhai
Published: November 2021

This paper studies the self-excited rotations of two side-by-side square cylinders and associated flow structures in a two-dimensional microchannel. As the Reynolds number increases from 5 to 300, the dynamic responses of the square cylinders present five distinct modes: rotation mode (Re = 5), where the pressure force on the cylinder overcomes the shear-induced torque and drives the cylinder rotation; oscillation mode (Re = 25, 50), where both the pressure- and shear-induced torques change periodically with the same period as the rotation angle, which pushes the cylinder oscillation at a certain frequency; static mode (Re = 75), where the pressure and shear forces on the cylinders balance each other and the cylinders are thus self-locked and remain static; random mode (Re = 100, 150, 200), where the complicated flow around the cylinder produces irregular pressure and shear forces on the cylinders, making the cylinders rotate in a random manner; and reversal rotation mode (Re = 300, where the rotation direction of each cylinder is opposite to that at Re = 5), where the shear forces drive the cylinder rotation in the abnormal direction while the irregular pressure makes the instant angular velocity vary randomly. Then, the flow structures are discussed in detail to help understand the interaction mechanisms between the cylinders and fluid flow. The influences of the cylinder dynamics and flow structures on the drag and lift coefficients are revealed.
Probing the thermodynamics and kinetics of ethylene carbonate reduction at the electrode–electrolyte interface with molecular simulations
Authors: Gibson Luke D. , Pfaendtner Jim , Mundy Christopher J.
Published: November 2021

Understanding the formation of the solid–electrolyte interphase (SEI) in lithium-ion batteries is an ongoing area of research due to its high degree of complexity and the difficulties encountered by experimental studies. Herein, we investigate the initial stage of SEI growth, the reduction reaction of ethylene carbonate (EC), from both a thermodynamic and a kinetic approach with theory and molecular simulations. We employed both the potential distribution theorem and the Solvation Method based on Density (SMD) to EC solvation for the estimation of reduction potentials of Li+, EC, and Li+-solvating EC (s-EC) as well as reduction rate constants of EC and s-EC. We find that solvation effects greatly influence these quantities of interest, particularly the Li+/Li reference electrode potential in EC solvent. Furthermore, we also compute the inner- and outer-sphere reorganization energies for both EC and s-EC at the interface of liquid EC and a hydroxyl-terminated graphite surface, where total reorganization energies are predicted to be 76.6 and 88.9 kcal/mol, respectively. With the computed reorganization energies, we estimate reduction rate constants across a range of overpotentials and show that EC has a larger electron transfer rate constant than s-EC at equilibrium, despite s-EC being more thermodynamically favorable. Overall, this manuscript demonstrates how ion solvation effects largely govern the prediction of reduction potentials and electron transfer rate constants at the electrode–electrolyte interface.
Probing the theoretical and computational limits of dissipative design
Authors: Chennakesavalu Shriram , Rotskoff Grant M.
Published: November 2021

Self-assembly, the process by which interacting components form well-defined and often intricate structures, is typically thought of as a spontaneous process arising from equilibrium dynamics. When a system is driven by external nonequilibrium forces, states statistically inaccessible to the equilibrium dynamics can arise, a process sometimes termed direct self-assembly. However, if we fix a given target state and a set of external control variables, it is not well-understood (i) how to design a protocol to drive the system toward the desired state nor (ii) the cost of persistently perturbing the stationary distribution. In this work, we derive a bound that relates the proximity to the chosen target with the dissipation associated with the external drive, showing that high-dimensional external control can guide systems toward target distribution but with an inevitable cost. Remarkably, the bound holds arbitrarily far from equilibrium. Second, we investigate the performance of deep reinforcement learning algorithms and provide evidence for the realizability of complex protocols that stabilize otherwise inaccessible states of matter.
Eulerian–Eulerian multiphase models for simulating collapse of submarine sediment column with rheological characteristics in air–water flow
Authors: Meng Wenkang , Liao Lei , Yu Ching-Hao , Li Jia , An Ruidong
Published: November 2021

Submarine massive sediment movement, which may devastate submarine infrastructure and cause huge waves threatening the coastal areas, combined with the air–water interface is a significant issue of the multiphase flows in the areas of ocean engineering and geoscience. Currently, simulating rheology-based sediment flows is still a challenge because of the complex intergranular dynamics and its coupling with computational fluid dynamics. In particular, air–water–sediment multiphase models that can simulate such rheology-based flows while also taking into account the accurate capture of the air–water interface have not been developed yet. Coupling with the coupled level set method and volume of fluid method in the air–water two-phase flow, this study develops two new Eulerian–Eulerian multiphase models for simulating the rheology-based sediment flows. The difference between the two developed models is that how to model the drag force of the particle–fluid interactions. To demonstrate their capabilities, the two developed models are employed to simulate the gravitational collapse of submarine sediment column in air–water flow with loose-packing case and dense-packing case. The results of collapse process, induced air–water interface fluctuation, and contractancy/diltancy behavior are all agree well with those in previous experiments and simulations. In addition, comparing the results of two developed models, it can be concluded that different modeling methods of the drag force not only directly affect the water–sediment interactions, but also indirectly influence the air–water interface fluctuations and the intergranular stresses remarkably.
An assessment of turbulence transportation near regular and random permeable interfaces
Authors: Wang Wenkang , Yang Guang , Evrim Cenk , Terzis Alexandros , Helmig Rainer , Chu Xu
Published: November 2021

Turbulent channel flow with a porous wall is investigated using direct numerical simulation, where the porous media domain consists of regular or random circular cylinder arrays. We compare the statistics and structure of the mean flow and turbulence in the channel flow with a bulk Reynolds number of 2500 and two porosities (φ=0.6 and 0.8) for the porous media. It is shown that the random interface significantly affects the dynamics of turbulence and the time-averaged flow. More intense mixing is observed near the random interface due to augmented form-induced shear stresses. Due to the strong dependence of induced flow direction on the interface geometry, we segmented the flow field into two types of areas based on the slope angle formed by the top-layer cylinders: the windward area and leeward area. The conditional average of turbulence kinematic energy budget over each type of area reveals their respective role in turbulence transportation more explicitly. In addition, we use finite-time Lyapunov exponents to inspect the Lagrangian coherent structures in the flow fields, which reveal the preferential fluid trajectories in the random porous medium geometry.
A pathway toward high-throughput quantum Monte Carlo simulations for alloys: A case study of two-dimensional (2D) GaSxSe1−x
Authors: Wines Daniel , Saritas Kayahan , Ataca Can
Published: November 2021

The study of alloys using computational methods has been a difficult task due to the usually unknown stoichiometry and local atomic ordering of the different structures experimentally. In order to combat this, first-principles methods have been coupled with statistical methods such as the cluster expansion formalism in order to construct the energy hull diagram, which helps to determine if an alloyed structure can exist in nature. Traditionally, density functional theory (DFT) has been used in such workflows. In this paper, we propose to use chemically accurate many-body variational Monte Carlo (VMC) and diffusion Monte Carlo (DMC) methods to construct the energy hull diagram of an alloy system due to the fact that such methods have a weaker dependence on the starting wavefunction and density functional, scale similarly to DFT with the number of electrons, and have had demonstrated success for a variety of materials. To carry out these simulations in a high-throughput manner, we propose a method called Jastrow sharing, which involves recycling the optimized Jastrow parameters between alloys with different stoichiometries. We show that this eliminates the need for extra VMC Jastrow optimization calculations and results in significant computational cost savings (on average 1/4 savings of total computational time). Since it is a novel post-transition metal chalcogenide alloy series that has been synthesized in its few-layer form, we used monolayer GaSxSe1−x as a case study for our workflow. By extensively testing our Jastrow sharing procedure for monolayer GaSxSe1−x and quantifying the cost savings, we demonstrate how a pathway toward chemically accurate high-throughput simulations of alloys can be achieved using many-body VMC and DMC methods.
Effects of the surface tension gradient and viscosity on coalescence-induced droplet jumping on superamphiphobic surfaces
Authors: Hou Huimin , Yuan Zhiping , Hu Zhifeng , Gao Sihang , Wu Xiaomin
Published: November 2021

With the development of superhydrophobic surface preparation technology, coalescence-induced droplet jumping shows broad application prospects in the fields of enhanced condensation heat transfer and self-cleaning. In this work, the coalescence-induced jumping process of heterogeneous and homogeneous droplets on superamphiphobic surfaces was studied by using glycerol–water mixtures with different glycerol volume fractions. The results showed that the surface tension gradient of heterogeneous droplets will lead to asymmetric deformation of droplets, asymmetric distribution of internal pressure of droplets, as well as decrease in the energy conversion efficiency and the vertical departure velocity. Our study also revealed that the effects of surface tension gradient and viscosity on droplet jumping are different in the two regions. When the glycerol volume fraction is less than 40%, the droplet velocity and energy conversion are dominated by the surface tension gradient, and the vertical departure velocity and the energy conversion efficiency of homogeneous droplets are larger. When the glycerol volume fraction is greater than 40%, the droplet velocity and energy conversion are dominated by the surface tension gradient and viscosity together, and the vertical departure velocity and the energy conversion efficiency of heterogeneous droplets are larger.
Semiclassical descriptions of rotational transitions in natural and shifted angles: Analysis of unexpected results
Authors: Bonnet Laurent
Published: November 2021

In the semiclassical theory of rotational transitions, S-matrix elements are expressed as integrals over initial and final angles of probability amplitudes calculated along the classical paths joining these angles, before final passage to an initial value representation [W. H. Miller, J. Phys. Chem. A 105, 2942 (2001)]. These angles can be either natural angles fixing the orientation of the rotor or angles shifted with respect to the previous ones so as to vary only within the interaction region causing the transitions. The two approaches, however, were recently shown to lead to different predictions. While the theory in natural angles lacks precision and exhibits unphysical behavior, the theory in shifted angles is much more accurate and physically well behaved [L. Bonnet, J. Chem. Phys. 153, 174102 (2020)]. The present work is devoted to the analysis of this unexpected finding.
Pulsed laser deposition growth of ultra-wide bandgap GeO2 film and its optical properties
Authors: Deng Gaofeng , Saito Katsuhiko , Tanaka Tooru , Arita Makoto , Guo Qixin
Published: November 2021

In this paper, we report the direct growth of ultra-wide bandgap GeO2 film on the m-plane sapphire substrate by pulsed laser deposition. Raman scattering and x-ray diffraction measurements confirm that the obtained GeO2 film has a (001)-oriented rutile structure mixed with the amorphous phase, and the film has an out-of-plane strain of –0.28% along the c direction. Transmittance spectra and x-ray photoelectron spectroscopy measurements determine that the transparent GeO2 film has an ultra-wide bandgap of about 5.1 eV. Room temperature photoluminescence spectrum exhibits a broad blue–green emission band dominated by two peaks at about 2.4 and 2.8 eV. With the temperature decreasing to 21 K, the peak intensities increase exponentially accompanied by a slight blue-shift in the peak position. We believe that these findings will pave the way for applications of the wide-bandgap GeO2 film in power and optoelectronic devices.
Improvement of the Gaussian Electrostatic Model by separate fitting of Coulomb and exchange-repulsion densities and implementation of a new dispersion term
Authors: Naseem-Khan Sehr , Piquemal Jean-Philip , Cisneros G. Andrés
Published: November 2021

The description of each separable contribution of the intermolecular interaction is a useful approach to develop polarizable force fields (polFFs). The Gaussian Electrostatic Model (GEM) is based on this approach, coupled with the use of density fitting techniques. In this work, we present the implementation and testing of two improvements of GEM: the Coulomb and exchange-repulsion energies are now computed with separate frozen molecular densities and a new dispersion formulation inspired by the Sum of Interactions Between Fragments Ab initio Computed polFF, which has been implemented to describe the dispersion and charge-transfer interactions. Thanks to the combination of GEM characteristics and these new features, we demonstrate a better agreement of the computed structural and condensed properties for water with experimental results, as well as binding energies in the gas phase with the ab initio reference compared with the previous GEM* potential. This work provides further improvements to GEM and the items that remain to be improved and the importance of the accurate reproduction for each separate contribution.
Carbon black-based NIR-responsive superhydrophobic shape memory microplate array with switchable adhesion for droplets and bubbles manipulation
Authors: Wu Sizhu , Wang Yue , Chen Chao , Peng Yubin , Li Longfu , Zhang Yiyuan , Wang Dawei , Li Zhicheng , Li Chuanzong , Zhang Chenchu
Published: November 2021

Superhydrophobic stimuli-responsive shape memory polymer (SMP) surfaces with tunable wettability have been extensively explored, but in situ reversibly switching ability as well as selectively capturing and releasing different liquids or bubbles, unfortunately, is still a blockage. Here, we fabricated a kind of light-responsive superhydrophobic SMP microplate array by utilizing femtosecond laser ablation and replica-mold method to achieve in situ switchable adhesion. By combining the photothermal effect of carbon black with the shape memory effect of SMP, the reversible switching between the upright state and temporary bending state of the microplate array can be readily realized. Simultaneously, the apparent force for the microplate array can be reversibly switched between low and high adhesion. More significantly, the current surface is competent for the amphibious manipulator, that is, the microplate array is adaptive for the selective capture and release of droplets as well as underwater bubbles. The current superhydrophobic SMP microplate array will have potential applications in intelligent droplet and bubble operation.
Plant ecological genomics at the limits of life in the Atacama Desert
Authors: Eshel Gil , Araus Viviana , Undurraga Soledad , Soto Daniela C. , Moraga Carol , Montecinos Alejandro , Moyano Tomás , Maldonado Jonathan , Díaz Francisca P. , Varala Kranthi , Nelson Chase W. , Contreras-López Orlando , Pal-Gabor Henrietta , Kraiser Tatiana , Carrasco-Puga Gabriela , Nilo-Poyanco Ricardo , Zegar Charles M. , Orellana Ariel , Montecino Martín , Maass Alejandro , Allende Miguel L. , DeSalle Robert , Stevenson Dennis W. , González Mauricio , Latorre Claudio , Coruzzi Gloria M. , Gutiérrez Rodrigo A.
Published: November 2021

Significance

In the current changing climate, it is essential to improve crop production and resilience under dry and nutrient-poor conditions. Desert plants have naturally evolved to flourish under such conditions. Therefore, understanding the underlying mechanisms for their adaptation can potentially help to ensure food security. The Atacama Desert, the driest nonpolar place on Earth, offers a unique opportunity to explore plant adaptations to extreme environmental conditions. Here, we reveal how the adaptive strategies common or specific to the major plant lineages in the Atacama include enrichment of plant growth-promoting bacteria near their roots and positive selection of genes that are associated with key beneficial processes for plant survival. These strategies can potentially direct the molecular breeding or engineering of resilient crops.
Growth and thermal maturation of the Toba magma reservoir
Authors: Liu Ping-Ping , Caricchi Luca , Chung Sun-Lin , Li Xian-Hua , Li Qiu-Li , Zhou Mei-Fu , Lai Yu-Ming , Ghani Azman A. , Sihotang Theodora , Sheldrake Tom E. , Simpson Guy
Published: November 2021

Significance

Understanding the thermal state of magma reservoirs before supereruptions is crucial for interpreting the processes leading to such catastrophic events. Here, we show that the two supereruptions of Toba were preceded and followed by protracted magma influx at relatively constant average volumetric rate over the past 2.2 My. This suggests that increased magma flux is not essential before supereruptions. Instead, long-term thermal maturation of the magma reservoir related to significant magma pulses primes the system for eruption. Importantly, our results indicate that significant variations of monitoring parameters, such as increased surface deformation or degassing, may not occur before supereruptions. Our method can be widely applied to other large silicic magmatic systems to evaluate their potential to feed a supereruption.
Cellular microRNA-127-3p suppresses oncogenic herpesvirus-induced transformation and tumorigenesis via down-regulation of SKP2
Authors: Lee Soo Mi , Kaye Kenneth M. , Slack Frank J.
Published: November 2021

Significance

Kaposi’s sarcoma (KS) is one of the most common cancers in sub-Saharan Africa. KS–associated herpesvirus (KSHV)-encoded miRNAs are expressed in KS and promote tumorigenesis, but the role of cellular miRNAs in KS tumorigenesis remains largely unexplored. We find that miR-127-3p is one of the most significantly down-regulated host miRNAs in KSHV-infected endothelial cells and KS patient tumors. We demonstrate that restoring miR-127-3p inhibits KSHV-induced transformation and tumorigenesis by directly targeting the oncogene SKP2 in vitro and in vivo. miR-127-3p–directed SKP2 repression increases p21
Cip1
and down-regulates cyclin E/A-CDK2, resulting in RB activation and suppression of E2F- and Myc-mediated transcriptional programs. This study reveals a critical tumor-suppressive function for miR-127-3p in KS, illuminating the miR-127-3p/SKP2 axis as a promising therapeutic avenue.
The minor pilin PilV provides a conserved adhesion site throughout the antigenically variable meningococcal type IV pilus
Authors: Barnier Jean-Philippe , Meyer Julie , Kolappan Subramania , Bouzinba-Ségard Haniaa , Gesbert Gaël , Jamet Anne , Frapy Eric , Schönherr-Hellec Sophia , Capel Elena , Virion Zoé , Dupuis Marion , Bille Emmanuelle , Morand Philippe , Schmitt Taliah , Bourdoulous Sandrine , Nassif Xavier , Craig Lisa , Coureuil Mathieu
Published: November 2021

Significance

Type IV pili (T4P) are among the most widespread adhesive factors in prokaryotes. In pathogenic
Neisseria
, the major pilin, which provides the structural framework for the filamentous T4P, undergoes antigenic variation allowing the bacteria to evade the humoral immune response without impacting host-cell adhesion. Here, we show that a minor pilin, PilV, is distributed throughout the pilus and contributes to
Neisseria meningitidis
adhesion and that antibodies to PilV block meningococcal adhesion in vivo. Our results provide a mechanism whereby
N. meningitidis
varies its immunodominant major pilin to escape antibody recognition while maintaining conserved sites throughout the pilus for host receptor binding. They further suggest a strategy to prevent or block deadly
N. meningitidis
infections by targeting this minor pilin.
Differential phase register of Hes1 oscillations with mitoses underlies cell-cycle heterogeneity in ER
+
breast cancer cells
Authors: Sabherwal Nitin , Rowntree Andrew , Marinopoulou Elli , Pettini Tom , Hourihane Sean , Thomas Riba , Soto Ximena , Kursawe Jochen , Papalopulu Nancy
Published: November 2021

Significance

Tumors exhibit heterogeneities that are not due to mutations, including cancer stem cells with different potencies. We show that the cancer stem-cell state predisposed to dormancy in vivo has a highly variable and long cell cycle. Using single-cell live imaging for the transcriptional repressor Hes1 (a key molecule in cancer), we show a type of circadian-like oscillatory expression of Hes1 in all cells in the population. The most potent cancer stem cells tend to divide around the trough of the Hes1 oscillatory wave, a feature predictive of a long cell cycle. A concept proposed here is that the position of cell division with respect to the Hes1 wave is predictive of its prospective cell-cycle length and cancer cellular substate.
Transcription as embodied entextualization
Authors: Cavanaugh Jillian R.
Published: November 2021

This article analyzes transcription as a form of knowledge production, distinguishing between the role of transcription as a tool and the contingent nature of transcription as a process. It uses the lens of embodied entextualization, or the culturally specific ways bodies are incorporated into as well as produce texts (Cavanaugh 2017), to illuminate the interdiscursive process of transcription and how it is shaped by social factors such as race, gender, politics, and class. I do so by presenting and analyzing text-objects from my own research on language ideologies and language shift in northern Italy at various stages of entextualization, highlighting the multiple choices that shape transcription and how such choices are in turn shaped by a number of factors often invisible in the final, or at least public, versions of these texts that circulate the most widely. Transcripts such as the ones I discuss endure as evidence, in published and other forms, even as intertextual gaps punctuate their interdiscursive reproduction across instantiations. This work raises questions about the role of transcripts as evidence, their authority, and their varying ontological statuses as text objects in order to further conversations about how scholarship about language in use may be reflexively undertaken.
Dust dynamics during the plasma afterglow
Authors: Denysenko I B , Mikikian M , Azarenkov N A
Published: November 2021

The charge and dynamics of dust particles in an afterglow plasma are studied using a 1D model in the diffusion approximation, taking into account the transition from ambipolar to free diffusion. It is analyzed how external conditions (dust particle size, neutral gas pressure and initial electron density) affect the dust motion. The dust particle dynamics has been examined in microgravity conditions and in presence of gravity. Without gravity, the location of dust particles in plasma volume may change essentially during the afterglow if the dust size and pressure are small (⩽10 nm and ⩽30 mTorr, respectively). At small pressures, in the very beginning of afterglow, small nanoparticles move to the plasma boundary because the ion drag force dominates over the electric force. At afterglow times when the electron temperature becomes time-independent, the ion drag force decreases faster with time than the electric force due to the ion density decrease, and dust particles may move to the slab center. In presence of gravity, the effect of gravity force on dust particles is important only at large afterglow times (t ⩾ 10 ms), when the electric and ion drag forces are small. The dust dynamics depends essentially on the initial plasma density. If the density is large (∼1012 cm−3), small nanoparticles (⩽10 nm) may deposit on plasma walls in the beginning of plasma afterglow because of an enhancement of the ion drag force.
Integration of piezoelectric stacks in components using powder bed fusion
Authors: Weber Rico , Seydel Samuel , Spierings Adriaan B , Bergamini Andrea , Van Damme Bart , Wegener Konrad
Published: November 2021

Laser-based powder bed fusion of metals (PBF-LB/M) is the most commonly used additive manufacturing process for fabricating complex metal parts by selective, layer-wise melting of metallic powder using a laser beam. This manufacturing technique can easily fabricate parts with complex geometries that cannot be fabricated using conventional manufacturing processes. These parts with complex geometries are generally used by aerospace and space industries, and advancement in functionalization of additive manufactured parts is highly beneficial to these industries. However, the parts constructed using additive manufacturing are monolithic, stiff, and lightweight and hence, they are vulnerable to high amplitude resonant vibrations. This is due to the low damping factor of the materials used and the absence of interfaces and connections that contribute to structural damping in conventional structures. The integration of piezoelectric materials within these structures would enable the control of vibration characteristics. The techniques presented in this study will enable a high level of freedom in the placement of piezoelectric materials and investigate the potential of merging parts constructed using additive manufacturing with piezoelectric materials. Furthermore, a technique to track the stress state during the integration process, which is crucial for the pre-stress evaluation of integrated piezoelectric stacks, is presented and shows characteristics similar to a force cell. Pre-stress is successfully tracked during integration and in some concepts tensile stress onto the piezoelectric material is occurring. Finally, to verify the functionality for potential piezoelectric damping, power conversion was reported with laser vibrometer measurements and FE validation.
Substrate tuned reconstructed polymerization of naphthalocyanine on Ag(110)
Authors: Zheng Qi , Huang Li , Bao Deliang , Wu Rongting , Li Yan , Lin Xiao , Du Shixuan , Gao Hong-Jun
Published: November 2021

The linkage structures between monomers make great influence on the properties of polymers. The synthesis of some special linkage structures can be challenging, which is often overcome by employing special reaction conditions. Here,we build dihydropentalene linkage in poly-naphthalocyanine on Ag(110) surface. Scanning tunneling microscopy (STM) and non-contact atomic force microscopy (nc-AFM) measurements confirm the dihydropentalenelinkage structure and a possible formation path with reconstruction steps is proposed. The controlled experiment on Ag(100) surface shows no dihydropentalene structures formed, which indicates the grooved substrate is necessary for the reconstruction. This work provides insights into the surface restricted reactions that can yield special structures in organic polymers.
Design and control of the first foldable single-actuator rotary wing micro aerial vehicle
Authors: Win Shane Kyi Hla , Win Luke Soe Thura , Sufiyan Danial , Foong Shaohui
Published: November 2021

The monocopter is a type of micro aerial vehicle largely inspired from the flight of botanical samaras (Acer palmatum). A large section of its fuselage forms the single wing where all its useful aerodynamic forces are generated, making it achieve a highly efficient mode of flight. However, compared to a multi-rotor of similar weight, monocopters can be large and cumbersome for transport, mainly due to their large and rigid wing structure. In this work, a monocopter with a foldable, semi-rigid wing is proposed and its resulting flight performance is studied. The wing is non-rigid when not in flight and relies on centrifugal forces to become straightened during flight. The wing construction uses a special technique for its lightweight and semi-rigid design, and together with a purpose-designed autopilot board, the entire craft can be folded into a compact pocketable form factor, decreasing its footprint by 69%. Furthermore, the proposed craft accomplishes a controllable flight in 5 degrees of freedom by using only one thrust unit. It achieves altitude control by regulating the force generated from the thrust unit throughout multiple rotations. Lateral control is achieved by pulsing the thrust unit at specific instances during each cycle of rotation. A closed-loop feedback control is achieved using a motion-captured camera system, where a hybrid proportional stabilizer controller and proportional-integral position controller are applied. Waypoint tracking, trajectory tracking and flight time tests were performed and analyzed. Overall, the vehicle weighs 69 g, achieves a maximum lateral speed of about 2.37 m s−1, an average power draw of 9.78 W and a flight time of 16 min with its semi-rigid wing.
Aerosol-modulated heat stress in the present and future climate of India
Authors: Dey Sagnik , Choudhary Rohit Kumar , Upadhyay Abhishek , Dash S K
Published: November 2021

Heat stress is one of the leading natural causes of mortality in India. Aerosols can potentially impact heat stress by modulating the meteorological conditions via radiative feedback. However, a quantitative understanding of such an impact is lacking. Here, using a chemical transport model, Weather Research Forecasting model coupled with chemistry, we show that high aerosol loading in India was able to mask the heat stress (quantified by the wet bulb globe temperature (WBGT)) by 0.3 °C–1.5 °C in 2010 with a regional heterogeneity across the major climate zones in India. However, the cooling effect of aerosol direct radiative forcing is partially compensated by an increase in humidity. To understand the potential impact of air quality improvement (i.e. reducing aerosol load) on heat stress in the future, WBGT was projected for 2030 under two contrasting aerosol emission pathways. We found that heat stress would increase by >0.75 °C in all the climate zones in India except in the montane zone under the RCP4.5 scenario with a bigger margin of increase in the mitigation emission pathway relative to the baseline emission pathway. On the contrary, under the RCP8.5 scenario, heat stress is projected to increase in limited regions, such as the tropical wet and dry, north-eastern part of the humid sub-tropical, tropical wet, and semi-arid climate zone in peninsular India. Our results demonstrate that aerosols modulate heat stress and, therefore, the heat stress projections in India and anywhere else with high aerosol loading should consider aerosol radiative feedback.
Short wave limit of the Novikov equation and its integrable semi-discretizations
Authors: Ma Ruyun , Zhang Yujuan , Xiong Na , Feng Bao-Feng
Published: November 2021

In this paper, we are concerned with one of the generalized short wave equations proposed by Hone et al (2018 Lett. Math. Phys
108 927). We show that the derivative form of this equation can be viewed as a short wave limit of the Novikov (sw-Novikov) equation. Furthermore, this generalized short wave equation and its derivative form are found to be connected to period 3 reduction of two-dimensional CKP(BKP)-Toda hierarchy, same as the short wave limit of the Depasperis–Procesi (sw-DP) equation. We propose a two-component short wave equation which contain the sw-Novikov equation and sw-DP equation as two special cases. As a main result, we construct two types of integrable semi-discretizations via Hirota’s bilinear method and provide multi-soliton solution to the semi-discrete sw-Novikov equation.
Variable energy flux in turbulence
Authors: Verma Mahendra K
Published: November 2021

In three-dimensional hydrodynamic turbulence forced at large length scales, a constant energy flux Π
u
flows from large scales to intermediate scales, and then to small scales. It is well known that for multiscale energy injection and dissipation, the energy flux Π
u
varies with scales. In this review we describe this principle and show how this general framework is useful for describing a variety of turbulent phenomena. Compared to Kolmogorov’s spectrum, the energy spectrum steepens in turbulence involving quasi-static magnetofluid, Ekman friction, stable stratification, magnetohydrodynamics, and solution with dilute polymer. However, in turbulent thermal convection, in unstably stratified turbulence such as Rayleigh–Taylor turbulence, and in shear turbulence, the energy spectrum has an opposite behaviour due to an increase of energy flux with wavenumber. In addition, we briefly describe the role of variable energy flux in quantum turbulence, in binary-fluid turbulence including time-dependent Landau–Ginzburg and Cahn–Hillianrd equations, and in Euler turbulence. We also discuss energy transfers in anisotropic turbulence.
Monotonicity in the averaging process
Authors: Ben-Naim E , Krapivsky P L
Published: November 2021

We investigate an averaging process that describes how interacting agents approach consensus through binary interactions. In each elementary step, two agents are selected at random and they reach compromise by adopting their opinion average. We show that the fraction of agents with a monotonically decreasing opinion decays as e
−αt
, and that the exponent

α
=

1

2

−

1
+
ln

ln

2

4

ln

2

is selected as the extremum from a continuous spectrum of possible values. The opinion distribution of monotonic agents is asymmetric, and it becomes self-similar at large times. Furthermore, the tails of the opinion distribution are algebraic, and they are characterized by two distinct and nontrivial exponents. We also explore statistical properties of agents with an opinion strictly above average.
The Sector Development at Tanjung Sakti, Mount Dempo, Bengkulu by Using Integration of Remote Sensing Data and TOPEX Gravity Satellite
Authors: Athirah Zahrah , Mahendra Muhammad Dhery
Published: November 2021

Mount Dempo is the highest volcano in South Sumatra, which lies between the Bukit Barisan mountains and Gumai. The mountain located in Dempo Makmur Village, Sub-district of Pagar Alam, Lahat Regency, South Sumatra is located at an altitude of 3173 meters above sea level with coordinates of 4.03 ° S 103.13 °E. Mount Dempo’s morphology is formed by pyroclastic deposits consisting of Tuff and Sand rocks. Mount Dempo’s vegetation is dominated by Cassia sp. and Camellia sinensis for upper vegetation, while Strobilanthes hamiltoniana and Strophanthus membranifolium dominate the undergrowth. The purpose of this study is to identify geological structures to predict geothermal prospect areas by integrating remote sensing data and TOPEX Gravity Satellite Data. The remote sensing data used in this study is Landsat 8. This data is used to analyze Land Surface Temperature (LST) from a single thermal infrared band, surface emissivity based on Normalization Difference Vegetation Index (NDVI) from the study area and determine structure delineation. Gravity Satellite Data is used to map gravity anomalies in the volcanic complex of Mount Dempo. Gravity data processing produces a high anomaly zone in the northern part of the study area and is predicted as a prospect area because it is assumed to be related to the plutonic body. High density contrast indicates that there is an error in that area. In line with the error, there are several hot springs because the error serves as a pathway for geothermal fluid to rise to the surface. The study believes that with all the facts stated above, the spots which are located in Tanjung Sakti, Mount Dempo district are very prospective to be developed as a geotourism complex, in which could also increase the welfare of the local citizens.
The Role of 2D Fast Fourier Transform and High Pass Filter in Regional and Residual Anomaly Separation in Gravity
Authors: Palupi I R , Raharjo W , Kiswanti S
Published: November 2021

Regional and residual Separation anomaly is one thing that must do in gravity processing data. It is important before calculating the depth of anomaly by power spectrum. There are several ways to do this, one of them is using 2D Fast Fourier Transform (FFT). 2D FFT will calculate the two-dimensional power of the gravity map (Bouger anomaly) to change the spatial domain into the wavenumber domain. 2D FFT result has no unit because it works in the wavenumber domain. Power spectrum do in wavenumber domain map. Besides that, to make the wavenumber map in the frequency domain, it should be convolved with some filter (high–pass filter) and then inverse to separate the regional and the residual map. The design of the filter matrix depends on the number of the data and the location of anomalies will be enhanced. It will influence the separation result. The best result gets from the trial and error process. 2D FFT is act like Upward Continuation or Polynomial Fitting in the gravity method with the simple process. In this paper, the process fully done in Python. Python is an effective and simple language programming because it has many modules to support the processing and covering the big data. It also gives the flexibility to the researcher to determine the specific location that will be enhanced
Subsurface Sediment Deposits of Tanjung Berikat Coast, Bangka, Determined from GPR Interpretation
Authors: Gustiantini L , Kamiludin U , Zulfikar M , Noviadi Y , Hernawan U , Ismayanto A F
Published: November 2021

Tanjung Berikat Coast in Central Bangka, is a part of the Southeast Asian tin belt. We conducted four Ground-Penetrating Radar (GPR) survey lines and 13 hand auger coring to understand sediment deposition and composition. Two similar units were determined from GPR lines BLG 01–BLG 03: Unit A at the top part, reflected by parallel and continuous reflector configuration, weak–strong electromagnetic wave. Underneath Unit A is Unit B, characterized by subparallel configuration, not continuous–chaotic, weak–medium electromagnetic wave. Unit B is absent in BLG 04. We identify another two units from BLG 04 and BLG 03, Unit C, characterized by subparallel reflector configuration, not continuous– chaotic, weak–strong electromagnetic wave. It exhibits distinctive modulating contact with Unit D. Unit D is characterized by chaotic reflector configuration, relatively stronger electromagnetic wave that might be correlated to the granite intrusion Tanjung Klabat. Sediment deposit is composed of fine–coarse sand, consisting mostly of clastic plutonic and clastic biogenic (coral and mollusk fragments), which increase downward. This indicates marine-fluvial influence, which suggests that sea-level changes strongly influence sedimentation process. Unit A from GPR is correlated to these sediment deposits, the other three units might be correlated to weathering of older insitu deposit.
Landslide Monitoring using Inclinometer with Micro Electromechanical System (MEMS)
Authors: Setiawan Tedy , Fatkhan  , Cysela Ramadhani Yasyfi
Published: November 2021

Being located on the Pacific Ring of Fire and a tectonically active country, Indonesia has to cope with the constant risk of volcanic eruptions, earthquakes, floods and landslides. Landslides and other mass movements are serious geo-environmental hazards in Indonesia. Following report from the Indonesia National Disaster Management Authority (BNPB), landslides are among high disaster death toll throughout the archipelago. It claimed 248 lives last year alone. The number of landslides in Indonesia increase steadily to 376 in 2014 from 291 in 2012. Hence, landslide monitoring system is required to determine style of landslide movement, for risk and even emergency risk management assessments and to assist with the design of mitigation works. A landslide instrumentation program including an inclinometer is designed for landslide monitoring. The inclinometer, or tilt sensor, is an instrument used for measuring slope, tilt, or inclination. In this paper we use Micro Electromechanical System (MEMS) as a sensor to measure changes in an angle. Then information is transferred to a central server soon after real-time accelerations are monitored. A data logger also used as a data recording. With low-cost MEMS accelerometers, the results show this instrument is able to provide reliable ground-motion data in network-scale deployments.
Development Prototype of Indonesia Seismic Microzonation Information System (Inasmis)
Authors: Hardy Thomas , Hakim Arif Rachman , Rohadi Supriyanto , Prayogo Angga Setiyo , Ngadmanto Drajat , Susilanto Pupung , Rasmid  , Sunardi Bambang , Pakpahan Suyanti , Setyonegoro Wiko , Kurniawan Telly , Nugraha Jimmi , Perdana Yusuf Hadi , Setiadi Tio Azhar P. , Sulastri  , Rahman Aditya , Vita Aprilia Nur , Priyobudi  , Martha Agustya Adi , Rachman Asep Nur , Murjaya Jaya , Muzli  , Yuliatmoko Rahmat Setyo
Published: November 2021

Indonesia has a high level of seismic vulnerability because located in the junction area of four large plates, namely the Eurasian plate, Indo-Australian plate, Pacific plate, and Philippine Plate, and also the number of active faults that stretch throughout its regions. One of the efforts to mitigate earthquake disasters is to conduct seismic hazard microzonation efforts. The Research and Development Center of BMKG has carried out ongoing research in the field of seismic microzonation to obtain information on the level of seismic hazard in some regions based on microtremor parameter values, including in the Sukabumi (2009), Bantul (2010), Padang (2011), Cilacap (2012), Kulonprogo (2014), Tasikmalaya (2017), Garut (2018) and Pangandaran (2019). This study tries to prototype the seismic microzonation information system in a web-based spatial information system called InaSMIS (Indonesia Seismic Microzonation Information System). InaSIMS contains information about the analysis of microtremor survey results, including the value of the dominant period (T0), Ground Shear Strain (GSS), and USGS Vs30, which states the level of seismic hazard in an area. InaSMIS is still being developed in the research stage and is not yet an operational service for BMKG. In the future, InaSMIS expected to be a source of public information to determine seismic hazards in Indonesian regions.