Small-scale Mechanism Research Articles

Effects of urban financial agglomeration on managerial mobility and corporate management compensation

Considering the geographical and economic characteristics of corporations, this article examines the impact of financial agglomeration on managerial compensation level and structure in A-share listed corporations from 2008 – 2022. Results demonstrate a direct relationship between urban financial agglomeration and managerial remuneration. Furthermore, the remuneration structure of these managers includes a significant proportion of equity incentives. This conclusion remains significant after conducting robustness tests to ensure reliability and validity. Additional research suggests that management migration is a small-scale mechanism through which urban financial agglomeration boosts managerial compensation and the proportion of equity incentives.

Asymmetry of the spectral lines of the coronal hole and quiet Sun in the transition region

ABSTRACT The asymmetry of line profiles, i.e. the secondary component, is crucial to understanding the energy release of coronal holes (CH), quiet Sun (QS), and bright points (BPs). We investigate the asymmetry of Si iv 1393.75 Å of the transition-region (TR) line recorded by Interface Region Imaging Spectrograph (IRIS) and co-spatial-temporal Atmospheric Imaging Assembly (AIA) and Helioseismic and Magnetic Imager (HMI) data onboard Solar Dynamics Observatory (SDO) for three time series on 2015 April 26, 2014 July 24, and 2014 July 26. Most asymmetric profiles are in the complex magnetic field regions of the networks. The asymmetric profiles are fitted with both single and double Gaussian models. The mean value of Doppler velocity of the second component is almost zero (with a significant standard deviation) in QS/CH, which may indicate that the physical process to trigger the secondary Gaussian originates at the formation height of Si iv. While the mean Doppler velocity from secondary Gaussian in BPs is around +4.0 km s−1 (redshifted). The non-thermal velocities of the secondary Gaussian in all three regions are slightly higher than the single Gaussian. The statistical investigation leads to the prevalence of blueshifted secondary components in QS/CH. However, secondary Gaussian in the BPs redshifted, i.e. the BPs redshift behaviour could be interpreted due to the site of reconnection located above the formation height of the Si iv line. The peak intensity of the second component for all three regions is likely to follow a power law that is a signature of the small-scale flaring-like trigger mechanism.

Multi-scale invariant solutions in plane Couette flow: a reduced-order model approach

Plane Couette flow at Reynolds number $Re=1200$ (based on the channel half-height and half the velocity difference between the top and bottom plates) is investigated with a spatial domain designed to retain only two spanwise integral length scales. In this system, the computation of invariant solutions that are physically representative of the turbulent state has been understood to be challenging. To address this challenge, our approach is to employ an accurate reduced-order model with 600 degrees of freedom (Cavalieri & Nogueira, Phys. Rev. Fluids, vol. 7, 2022, L102601). Using the two-scale energy budget and the temporal cross-correlation of key observables, it is first demonstrated that the model contains most of the multi-scale physical processes identified recently (Doohan et al., J. Fluid Mech., vol. 913, 2021, A8); i.e. the large- and small-scale self-sustaining processes, the energy cascade for turbulent dissipation, and an energy-cascade mediated small-scale production mechanism. Invariant solutions of the reduced-order model are subsequently computed, including 96 equilibria and 43 periodic orbits. It is found that none of the computed equilibrium solutions are able to reproduce an accurate energy balance associated with the multi-scale dynamics of the turbulent state. Incorporation of unsteadiness into invariant solutions is seen to be essential for a sensible description of the multi-scale turbulent dynamics and the related energetics, at least in this type of flow, as periodic orbits with a sufficiently long period are mainly able to describe the complex spatio-temporal dynamics associated with the known multi-scale phenomena.

Probing the small-scale impact deformation mechanism in an aluminum single-crystal

Although the rate-dependence of metals has been widely researched, the deformation mechanism under small-scale impact conditions lacked exploration and in-depth understanding. Using quasi-static nanoindentation (strain rate, SR, < 1 s–1) and high strain-rate nano-impact (SR > 103 s–1) with a pyramidal Berkovich tip, this study investigates the influence of SR on the deformation response of an aluminium single crystal (110). The underlying microstructural variance was analyzed using on-axis TKD and TEM. The results show that the impact deformation involves great elastic recovery and different substructural characteristics. In contrast to the uniform sub-grain substructure with medium and high-angle grain boundaries formed during quasi-static indentation, the substructure formed under impact has a more heterogeneous nature including microbands near the surface and sub-grains underneath with dominant low-angle grain boundaries. The significant change in substructure for the impact deformation comes from suppressed thermally activated dislocation motion, leading to the conversion of dislocation glide from wave-like (quasi-static) to planar regime (impacting), and the insufficient rearrangement of geometrically necessary dislocations (GNDs). The heterogeneous microstructure develops due to the competition between high strain-rate-induced planar-slip and strain gradient-induced GND rearrangement, as well as the uneven distribution of SR and strain gradient. Moreover, the underlying incipient mechanism of the microband is proposed, in which successive primary dislocations are nucleated at the surface and glide perpendicular to flanks to pile up. Finally, the influence of SR on indentation size effects is discussed.

How Ritual an Animal? Harvey Whitehouse on Ritual, Trust, and Cooperation

Harvey Whitehouse documents the great variety of ritual in human life, while offering a unified framework. Ritual’s essential social role is to support social cohesion and cooperation, but it does so via distinct mechanisms: through social fusion and through social identification. For, despite variation, ritual clusters at two poles: rare, intense, often aversive rituals; and frequent, low arousal rituals. Those frequent rituals operate through social identification primed by mutual recognition of common doctrine. In principle, this mechanism is scale independent. Rare, intense rituals generate cohesion through social fusion, itself triggered by shared, congruent autobiographical memory. This is intrinsically a small-scale mechanism. In this paper, I (i) argue that cost-based analyses of the function of ritual have a larger scope than Whitehouse supposes, (ii) offer a modified view of social fusion and the role of autobiographical memory, and (iii) argue that the primary upshot of doctrinal ritual is the legitimation of hierarchy rather than social cohesion over large social scales.

Smart Sediment Particle: A novel approach to investigating fluvial bed entrainment using instrumented sensors

The Smart Sediment Particle (SSP) instrumented with multiple sensors to obtain tri-axial linear accelerations is used for studying the mechanism of coarse grain entrainment. Three bed arrangements are tested to examine their influences on entrainment processes and the threshold force and impulse conditions. The SSP shows satisfactory precision to capture the imperceptible movement tendencies immediately (e.g., 0.15 s) after the dislodgement. The experimental results show that bed packing can significantly affect the particle's entrainment threshold and the path of movement. Lateral movement is predominant for some cases because the entrainment path is based on the least work done by the flow, even if the direction is not aligned with the flow. The concept of effective protrusion height is proposed to quantify the effect of local bed arrangement on entrainment. The mean velocity field around the SSP is also measured together with the acceleration data. The mean threshold velocity and resultant impulse show consistent dependence on the bed arrangement. In general, the SSP shows a good prospect of being used to study small-scale entrainment mechanism.

Insensitivity of a turbulent laser-plasma dynamo to initial conditions

It has recently been demonstrated experimentally that a turbulent plasma created by the collision of two inhomogeneous, asymmetric, weakly magnetized, laser-produced plasma jets can generate strong stochastic magnetic fields via the small-scale turbulent dynamo mechanism, provided the magnetic Reynolds number of the plasma is sufficiently large. In this paper, we compare such a plasma with one arising from two pre-magnetized plasma jets whose creation is identical save for the addition of a strong external magnetic field imposed by a pulsed magnetic field generator. We investigate the differences between the two turbulent systems using a Thomson-scattering diagnostic, x-ray self-emission imaging, and proton radiography. The Thomson-scattering spectra and x-ray images suggest that the external magnetic field has a limited effect on the plasma dynamics in the experiment. Although the external magnetic field induces collimation of the flows in the colliding plasma jets and although the initial strengths of the magnetic fields arising from the interaction between the colliding jets are significantly larger as a result of the external field, the energies and morphologies of the stochastic magnetic fields post-amplification are indistinguishable. We conclude that, for turbulent laser-plasmas with supercritical magnetic Reynolds numbers, the dynamo-amplified magnetic fields are determined by the turbulent dynamics rather than the seed fields or modest changes in the initial flow dynamics of the plasma, a finding consistent with theoretical expectations and simulations of turbulent dynamos.

Hinges and Curved Lamina Emergent Torsional Joints in Cylindrical Developable Mechanisms

Abstract Cylindrical developable mechanisms are devices that conform to and emerge from a cylindrical surface. These mechanisms can be formed or cut from the cylinder wall itself. This paper presents a study on adapting traditional hinge options to achieve revolute motion in these mechanisms. A brief overview of options is given, including classical pin hinges, small-length flexural pivots, initially curved beams, and an adaptation of the membrane thickness-accommodation technique. Curved lamina emergent torsional (LET) joints are then evaluated in detail, and a thin-walled modeling assumption is checked analytically and empirically. A small-scale cylindrical developable mechanism is then evaluated with Nitinol curved LET joints.

Techno-economic and environmental assessment of methane oxidation layer measures through small-scale clean development mechanism – The case of the Seychelles

Unclosed coastal landfills in small island developing states are major sources of greenhouse gases and other environmental impacts. This is a major problem for sustainable waste management systems mainly due to the lack of economic resources. The clean development mechanism (CDM) appears as a possibility to facilitate sustainable financing. Implementing a methane oxidation layer (MOL) emerges as a feasible technical option for this kind of small landfills since landfill gas extraction is usually not viable. This paper presents a techno-economic and environmental assessment of MOL implementation in the Providence landfill (Seychelles) as a small-scale CDM measure. Results show that the MOL measure could avoid by 2030 between 94 and 20 kt CO2 eq. Concerning profitability, results clearly show that it depends on the existence of stabilized biomass material within the island. Thus, the MOL measure starts to be profitable in some scenarios for certified emission reductions (CER) prices higher than 26 €/t CO2 eq. that seem possible depending on the emissions’ market development. When not profitable under CDM, the MOL measure might be used to reduce CO2 emissions from the domestic climate effort under the Paris Agreement since the unitary abatement costs is between 10 and 423 €/t CO2 eq. Moreover, the MOL measure contributes to the sustainable development goals (SDG) achievement – mainly SDG8, SDG13, and SDG14. Finally, results call for a prompt action in Seychelles since the sooner the MOL is implemented after the landfill is closed, the more profitable.

Quasi-waveform seismic tomography of crustal structures in the capital circle region of China

Seismic tomography is one of the main tools to explore the interior of the earth. In this study, the quasi-waveform seismic tomographic method is used for the first time to reveal the crustal structures in the capital region of China. 3-D high-resolution VP, VS and the Poisson’s ratio models are generated by inverting 29839 direct P- and 29972 direct S-wave traveltimes selected from 3231 local earthquakes. The results reveal strong crustal heterogeneities. The velocity anomalies at shallow depths are well consistent with surface geologic structures. The relatively low-velocity anomaly layer in the middle crust may be the result of multiple phases of tectonic activity. Earthquakes generally occurred on the boundaries of high- and low-velocity and Poisson’s ratio anomalies. There are obvious low-velocity anomalies below the hypocenters of the Tangshan earthquake and the historical Sanhe-Pinggu earthquake, implying the existence of fluids. The similar velocity structures around the hypocenters of the two earthquakes indicate that the occurrences of the two earthquakes may be related to the same mechanism. The highresolution velocity models provide important observational constraints on the small-scale heterogeneities and dynamic mechanism of the crust in the capital region of China.

Research on Decentralized Trading Strategy of Electricity Market Based on Blockchain Technology

With the gradual opening of the bilateral electricity market and the increase in distributed new energy generation, under the new market structure, various types of members should be encouraged to develop flexible cooperation and competition models in the new situation in order to improve the operating efficiency in the electricity market, encouraging the reduction of operating costs to improve the economic benefits of the market. Based on the relevant theories of blockchain technology, this paper proposes a decentralized small-scale distribution network intra-network transaction model and market mechanism, which can eventually be truly decentralized and achieve a lower cost and high efficiency market.

Is habitat fragmentation bad for biodiversity?

In a review of landscape-scale empirical studies, Fahrig (2017a) found that ecological responses to habitat fragmentation per se (fragmentation independent of habitat amount) were usually non-significant (>70% of responses) and that 76% of significant relationships were positive, with species abundance, occurrence, richness, and other response variables increasing with habitat fragmentation per se. Fahrig concluded that to date there is no empirical evidence supporting the widespread assumption that a group of small habitat patches generally has lower ecological value than large patches of the same total area. Fletcher et al. (2018) dispute this conclusion, arguing that the literature to date indicates generally negative ecological effects of habitat fragmentation per se. They base their argument largely on extrapolation from patch-scale patterns and mechanisms (effects of patch size and isolation, and edge effects) to landscape-scale effects of habitat fragmentation. We argue that such extrapolation is unreliable because: (1) it ignores other mechanisms, especially those acting at landscape scales (e.g., increased habitat diversity, spreading of risk, landscape complementation) that can counteract effects of the documented patch-scale mechanisms; and (2) extrapolation of a small-scale mechanism to a large-scale pattern is not evidence of that pattern but, rather a prediction that must be tested at the larger scale. Such tests were the subject of Fahrig's review. We find no support for Fletcher et al.'s claim that biases in Fahrig's review would alter its conclusions. We encourage further landscape-scale empirical studies of effects of habitat fragmentation per se, and research aimed at uncovering the mechanisms that underlie positive fragmentation effects.

The small-scale dynamo in a spectral representation

ABSTRACTIn this paper, we study the correlation functions for magnetic energy and magnetic helicity generated by a small-scale dynamo mechanism in a mirror-asymmetric and isotropic turbulent conductive fluid. Solving the Kazantsev system for small-scale generation by an iterative approach, we restore the correlation functions in spatial and spectral representations. Studying scales of localisation and their dependence on magnetic Reynolds number, we propose approximate functions, which can be applied for energy and helicity in a spectral space. We show the absence of 3/2-spectrum for Kazantsev assumptions at and helicity sign changing at . Using our results and estimating the relation between helicity and energy at different scales, we speculate about what can be considered as a small scale in a spectral space, and how this scale can be connected with mean-field processes.

Variscan Sb-Au mineralization in Central Brittany (France): A new metallogenic model derived from the Le Semnon district

Numerous Sb-Au deposits are known in the European Variscan belt and are often associated with the late Variscan hydrothermal events linked to postorogenic extension and strike-slip faults, through the whole belt. The central part of the Armorican Massif (Central Brittany) hosts several Sb-Au deposits, such as the Le Semnon deposit. However, little is known about its formation, its structural control or hydrothermal history. In order to provide new constraints on the Sb-Au mineralization framework of the Variscan Armorican Massif, structural, geochronological and chemical analyses have been performed on the Le Semnon Sb-Au deposit. First, we highlight that Sb-Au mineralization consists of fault-fill and flat extensional vein systems resulting from small-scale fault-valve mechanism controlled by fluid overpressure at shallow depth. Indeed, this deposit is characterized by the presence of dolerite dykes which acted as the plumbing system for fluids within impermeable slates. The low permeability of the slates permitted the establishment of local supralithostatic fluid pressure in a predominantly hydrostatic regime. Coupled with new (micro-) textural evidences, a reappraisal of the paragenetic evolution and new physico-chemical data, 40Ar/39Ar and U-Pb analyses show that the Le Semnon Sb-Au mineralization was emplaced around 360 Ma and therefore indicates an early hydrothermal event in the Variscan history of the Armorican Massif. Moreover, absolute dating of mafic magmatism coupled with hydrothermal alteration associated with the deposition of Sb-Au mineralization strongly suggest that the emplacement of the Sb-Au mineralization was coeval with the emplacement of the host rock doleritic dyke. Furthermore, the high temperature recorded in fluid inclusions and the paragenetic evolution suggests an elevated thermal anomaly in Central Brittany. Thus, we propose that the emplacement of the widespread mafic magmatism at ca. 360 Ma played a major role in the mobilization of fluid flows and the redistribution of metals in the Armorican crust.

What drives galactic magnetism?

We aim to use statistical analysis of a large number of various galaxies to probe, model, and understand relations between different galaxy properties and magnetic fields. We have compiled a sample of 55 galaxies including low-mass dwarf and Magellanic-types, normal spirals and several massive starbursts, and applied principal component analysis (PCA) and regression methods to assess the impact of various galaxy properties on the observed magnetic fields. According to PCA the global galaxy parameters (like HI, H2, and dynamical mass, star formation rate (SFR), near-infrared luminosity, size, and rotational velocity) are all mutually correlated and can be reduced to a single principal component. Further PCA performed for global and intensive (not size related) properties of galaxies (such as gas density, and surface density of the star formation rate, SSFR), indicates that magnetic field strength B is connected mainly to the intensive parameters, while the global parameters have only weak relationships with B. We find that the tightest relationship of B is with SSFR, which is described by a power-law with an index of 0.33+-0.03. The observed weaker associations of B with galaxy dynamical mass and the rotational velocity we interpret as indirect ones, resulting from the observed connection of the global SFR with the available total H2 mass in galaxies. Using our sample we constructed a diagram of B across the Hubble sequence which reveals that high values of B are not restricted by the Hubble type. However, weaker fields appear exclusively in later Hubble types and B as low as about 5muG is not seen among typical spirals. The processes of generation of magnetic field in the dwarf and Magellanic-type galaxies are similar to those in the massive spirals and starbursts and are mainly coupled to local star-formation activity involving the small-scale dynamo mechanism.

Constraints on dynamo action in plasmas

Upper bounds are derived on the amount of magnetic energy that can be generated by dynamo action in collisional and collisionless plasmas with and without external forcing. A hierarchy of mathematical descriptions is considered for the plasma dynamics: ideal magnetohydrodynamics (MHD), visco-resistive MHD, the double-adiabatic theory of Chew, Goldberger and Low (CGL), kinetic MHD and other kinetic models. It is found that dynamo action is greatly constrained in models where the magnetic moment of any particle species is conserved. In the absence of external forcing, the magnetic energy then remains small at all times if it is small in the initial state. In other words, a small ‘seed’ magnetic field cannot be amplified significantly, regardless of the nature of flow, as long as the collision frequency and gyroradius are small enough to be negligible. A similar conclusion also holds if the system is subject to external forcing as long as this forcing conserves the magnetic moment of at least one plasma species and does not greatly increase the total energy of the plasma (i.e. in practice, is subsonic). Dynamo action therefore always requires collisions or some small-scale kinetic mechanism for breaking the adiabatic invariance of the magnetic moment.

A bioeconomic analysis of the carbon sequestration potential of agroforestry systems: A case study of Grevillea robusta in South Western Uganda

Grevillea robusta is an agroforestry tree species that has been widely promoted under the carbon forestry schemes in South Western Uganda. The objective of the study was to estimate the amount of carbon sequestered and the profitability of carbon offsets in G. robusta woodlot and agroforestry management options under the Plan Vivo system and small-scale Clean Development Mechanism (CDM). An allometric equation for G. robusta was used to calculate the carbon stocks and merchantable wood volume in the woodlot and agroforestry management options over different crediting periods. The results indicated that G. robusta woodlots and agroforestry management options sequestered 470 and 225 t CO2e ha-1 respectively, over a 20 year rotation. The net present values (NPVs) of the G. robusta agroforestry management option of US$4367 and 4447 ha-1 under the Plan Vivo and small-scale CDM, respectively, were higher than US$1358 and 1902 ha-1 in the G. robusta woodlot management option. The NPV of the traditional agroforestry system was US$ 3992 ha-1. These results show that, whereas the woodlot option stores more carbon, it is the least profitable option. Analysis also revealed that, although poor households were well represented in the Plan Vivo scheme, they preferred the agroforestry option. This suggests that forest carbon offsets on productive agricultural land, should focus on promoting agroforestry technologies in order to increase profitability and targeting of the poor households. Key words: Allometric equation, carbon offsets, profitability

The economics of the carbon sequestration potential of plantation forestry in south-western Uganda

This study assessed the amount of carbon stored and the economic viability of the small-scale Clean Development Mechanism (CDM) carbon offsets in Pinus caribaea and Eucalyptus grandis plantations under varying rotations. Volume equations were used to estimate carbon stocks and merchantable wood volume in the plantations, while net present value (NPV) and annual equivalent value (AEV) were used as measures of profitability at the optimum economic rotation age as well as at the CDM-defined crediting period of 20 years. The findings show that over a 20-year rotation, E. grandis and P. caribaea plantations sequestered 638 and 418 t CO2-e ha−1, respectively. The NPVs of E. grandis and P. caribaea with carbon credits over the CDM carbon-crediting period of 20 years were US$2 540 ha−1 and US$1 814 ha−1, respectively. This is higher than the NPVs without carbon credits of US$1 543 ha−1 and US$1 390 ha−1 for E. grandis and P. caribaea, respectively. The AEV of E. grandis harvested at its optimal economic rotation of 10 years was US$316 ha−1. This is slightly higher than the AEV of US$298 ha−1, utilising the CDM carbon-crediting period of 20 years. In contrast, the AEV of P. caribaea under the 20-year CDM carbon-crediting period was higher than harvesting at the optimal economic rotation of 16 years without carbon credits. When the average CDM contract establishment costs exceed US$500 ha−1 and US$1 000 ha−1 for P. caribaea and E. grandis woodlots, respectively, it is not economically viable for one to participate in the CDM forest carbon offsets programme. In conclusion, the study results indicate that whereas E. grandis has a higher biological potential to sequester carbon than P. caribaea, it is currently not economically viable for participation in the CDM forest carbon offset scheme. In contrast, it is economically viable for P. caribaea plantations to participate in the CDM, if the CDM contract establishment costs are low.

Fabrication of Composite and Sheet Metal Laminated Bistable Jumping Mechanism

A layer-based manufacturing method using composite microstructures is widely used for mesoscale robot fabrication. This fabrication method has enabled the development of a lightweight and robust jumping robot, but there are limitations in relation to the embedding of elastic components. In this paper, a fabrication method for embedding an elastic component at an angled position is developed, extending the capability of the composite microstructures. This method is then used to build an axial spring attached to the bistable mechanism of a jumping robot. Sheet metal is used as an elastic component, which is stamped after the layering and curing process, thereby changing the neutral position of the spring. Two linear springs are designed to be in parallel with a joint to impose bistability; thereby delivering two stable states. This bistable mechanism is triggered with a shape memory alloy (SMA) coil spring actuator. A small-scale jumping mechanism is then fabricated using this mechanism; it jumps when the snap-through of the bistable mechanism occurs. A model of the stamped sheet metal spring is built based on a pseudo rigid body model (PRBM) to estimate the spring performance, and a predictive sheet metal bending model is also built to design the die for stamping. The experimental results show that the stamped sheet metal spring stores 12.63 mJ of elastic energy, and that the mechanism can jump to a height of 175 mm with an initial takeoff velocity of 1.93 m/s.

ARCADE-R2 experiment on board BEXUS 17 stratospheric balloon

This paper provides an overview of the ARCADE-R2 experiment, a technology demonstrator that aimed to prove the feasibility of small-scale satellite and/or aircraft systems with automatic (a) attitude determination, (b) control and (c) docking capabilities. The experiment embodies a simplified scenario in which an unmanned vehicle mock-up performs rendezvous and docking opera- tions with a fixed complementary unit. The experiment is composed by a supporting structure, which holds a small vehicle with one translational and one rotational degree of freedom, and its fixed target. The dual system features three main custom subsystems: a relative infrared navigation sensor, an attitude control system based on a reaction wheel and a small-scale docking mechanism. The experiment bus is equipped with pressure and temperature sensors, and wind probes to monitor the external environmental conditions. The experiment flew on board the BEXUS 17 stratospheric balloon on October 10, 2013, where several