Kinetic Power Research Articles

Evaluating the Onshore Wind Farms based on Multi-Criteria Decision-Making Model under Neutrosophic Set

This work comprehensively evaluates onshore wind farms, focusing on their technological efficiency, environmental impact, economic viability, and societal implications. Onshore wind energy has emerged as a prominent renewable energy source, leveraging the kinetic power of wind to generate electricity on a substantial scale. The evaluation encompasses a detailed analysis of wind resource assessment, turbine technology, grid integration, environmental considerations, economic feasibility, and stakeholder engagement. Findings reveal that onshore wind farms exhibit commendable technological advancements, with modern turbines showcasing higher efficiency and capacity. Environmental assessments highlight their lower carbon footprint compared to conventional energy sources, albeit with considerations for land use and wildlife impacts. Economic evaluations emphasize the decreasing costs of wind energy, yet challenges persist concerning upfront investment and intermittency. Stakeholder engagement emerges as a crucial aspect, stressing the importance of community acceptance and regulatory compliance. The assessment illuminates the multifaceted aspects of onshore wind farms, underscoring their potential as a sustainable energy source while acknowledging the need to address technological, economic, and social barriers to widespread adoption. We used the multi-criteria decision-making (MCDM) model for evaluating the onshore wind farms. The Measuring Attractiveness by a Categorical Based Evaluation Technique (MACBETH) method is used to rank the alternatives. The MCDM method used under single valued neutrosophic set (SVNS). The SVNS is used to overcoming the uncertainty in the evaluation process.

Study of Wolf-Rayet Stars Using uGMRT

In recent years, systems involving massive stars with large wind kinetic power have been considered as promising sites for investigating relativistic particle acceleration in low radio frequencies. With this aim, we observed two Wolf-Rayet systems, WR 114 and WR 142, using upgraded Giant Meterwave Radio Telescope observations in Band 4 (550–950 MHz) and Band 5 (1050–1450 MHz). None of the targets was detected at these frequencies. Based on the non-detection, we report 3𝜎 upper limits to the radio flux densities at 735 and 1260 MHz (123 and 66 𝜇Jy for WR 114, and 111 and 96 𝜇Jy for WR 142, respectively). Plausible scenarios to interpret this non-detection are presented.

AGN-driven outflows in the OH absorber galaxy IRAS 19154+2704

ABSTRACT We present a two-dimensional study of the gas distribution, excitation, and kinematics of the OH absorber galaxy IRAS 19154+2704 using Gemini Multi-Object Spectrograph integral field unit observations. Its continuum image shows a disturbed morphology indicative of a past or ongoing interaction. The ionized gas emission presents two kinematic components: a narrow (σ ≲ 300 km s−1) component that may be tracing the gas orbiting in the galaxy potential and a broad (σ ≳ 500 km s−1) component, which is produced by an active galactic nucleus (AGN)-driven outflow, with velocities reaching −500 km s−1, which may exceed the escape velocity of the galaxy. The emission-line ratios and Baldwin–Phillips–Terlevich diagrams confirm that the gas excitation in the inner ∼2 kpc is mainly due to the AGN, while in regions farther away, a contribution from star formation is observed. We estimate a mass-outflow rate of $\dot{M}_{\rm out}=4.0\pm 2.6$ M⊙ yr−1 at a distance of 850 pc from the nucleus. The corresponding outflow kinetic power, $\dot{E}_{\rm out} = (2.5\pm 1.6)\times 10^{42}$ erg s−1, is only 3 × 10−4 Lbol (the AGN luminosity), but the large mass-outflow rate, if kept for an ∼10 Myr AGN life cycle, will expel ≈108 M⊙ in ionized gas alone. This is the sixth of a series of papers in which we have investigated the kinematics of ultra-luminous infrared galaxies, most of which are interacting galaxies showing OH megamasers. IRAS 19154 shows the strongest signatures of an active AGN, supporting an evolutionary scenario: interactions trigger AGN that fully appears in the most advanced stages of the interaction.

Hydrodynamics and Mass Transfer in an Airlift Loop Reactor: Comparison between Using Two Kinds of Spargers

The effects of different spargers on the hydrodynamics and mass transfer of an airlift loop reactor were investigated. The gas holdup, liquid loop velocity, and volumetric mass transfer coefficient of the reactor were tested using a ring orifice distributor and a jet nozzle. The study was conducted in a 6 m high airlift loop reactor at a superficial gas velocity of 0.01~0.04 m/s, and the superficial liquid velocity was maintained at 0.0154 m/s. The results showed that using the jet nozzle provided a higher gas holdup, liquid loop velocity, and mass transfer. When the superficial gas velocity was less than 0.0325 m/s, the liquid loop velocity generated by the jet nozzle was approximately 1.1-fold higher than that generated by the ring orifice distributor, and the disparity in gas holdup between the riser and downcomer enhanced the power of liquid circulation. When the superficial gas velocity was more than 0.0325 m/s, the jet kinetic power dominated the improvement in the liquid loop velocity, and the energy input from the nozzle to the airlift loop reactor was greater than 10.8 J/(s·m2). This indicated a threshold of energy input for overcoming the friction loss. In this situation, the liquid loop velocity in the jet form increased considerably, thus favoring the mixing performance and temperature uniformity of the reactor. It was also of significance for avoiding the formation of a flow dead zone in scale-up airlift loop reactors.

Density calculations of NGC 3783 warm absorbers using a time-dependent photoionisation model

Outflowing wind, as one type of AGN feedback involving non-collimated ionised winds such as those prevalent in Seyfert-1 AGNs, impacts the host galaxy by carrying kinetic energy outwards. However, the distance of the outflowing wind is poorly constrained because of a lack of direct imaging observations, which limits our understanding of its kinetic power, and thus of its impact on the local galactic environment. One potential approach to solving this problem involves determination of the density of the ionised plasma, making it possible to derive the distance using the ionisation parameter ξ, which can be measured based on the ionisation state. Here, by applying a new time-dependent photoionisation model, tpho, in SPEX, we define a new approach, the tpho-delay method, which we use to calculate or predict a detectable density range for warm absorbers of NGC 3783. The tpho model solves self-consistently the time-dependent ionic concentrations, which enables us to study the delayed states of the plasma in detail. We show that it is crucial to model the non-equilibrium effects accurately for the delayed phase, where the non-equilibrium and equilibrium models diverge significantly. Finally, we calculate the crossing time to consider the effect of the transverse motion of the outflow on the intrinsic luminosity variation. Future spectroscopic observations with more sensitive instruments are expected to provide more accurate constraints on the outflow density, and therefore on the feedback energetics.

Probing the non-thermal physics of stellar bow shocks using radio observations

Context. Massive runaway stars produce bow shocks in the interstellar medium. Recent observations revealed radio emission from a few of these objects, but the origin of this radiation remains poorly understood. Aims. We aim to interpret this radio emission and assess under which conditions it could be either thermal (free–free) or non-thermal (synchrotron), and how to use the observational data to infer physical properties of the bow shocks. Methods. We used an extended non-thermal emission model for stellar bow shocks for which we incorporated a consistent calculation of the thermal emission from the forward shock. We fitted this model to the available radio data (spectral and intensity maps), including largely unexplored data at low frequencies. In addition, we used a simplified one-zone model to estimate the gamma-ray emission from particles escaping the bow shocks. Results. We can only explain the radio data from the best sampled systems (BD+43°3654 and BD+60°2522) assuming a hard electron energy distribution below ∼1 GeV, a high efficiency of conversion of (shocked) wind kinetic power into relativistic electrons (∼1 − 5%), and a relatively high magnetic-to-thermal pressure ratio of ηB ∼ 0.2. In the other systems, the interpretation of the observed flux density is more ambiguous, although a non-thermal scenario is also favoured. We also show how complementary observations at other frequencies can allow us to place stronger constraints in the model. We also estimated the gamma-ray fluxes from the HII regions around the bow shocks of BD+43°3654 and BD+60°2522, and obtained luminosities at GeV energies of ∼1033 erg s−1 and 1032 erg s−1, respectively, under reasonable assumptions. Conclusions. Stellar bow shocks can potentially be very efficient particle accelerators. This work provides multi-wavelength predictions of their emission and demonstrates the key role of low-frequency radio observations in unveiling particle acceleration processes. The prospects of detections with next-generation observatories such as SKA and ngVLA are very promising. Finally, BD+43°3654 may be detected in GeV in the near future, while bow shocks in general may turn out to be non-negligible sources of (at least leptonic) low-energy cosmic rays.

AGN feedback and star formation in the peculiar galaxy NGC 232: insights from VLT-MUSE observations

ABSTRACT We use VLT-MUSE integral field unit data to study the ionized gas physical properties and kinematics as well as the stellar populations of the Seyfert 2 galaxy NGC 232 as an opportunity to understand the role of AGN feedback on star formation. The data cover a field of view of 60 × 60 arcsec2 at a spatial resolution of ∼850 pc. The emission-line profiles have been fitted with two Gaussian components, one associated to the emission of the gas in the disc and the other due to a bi-conical outflow. The spectral synthesis suggests a predominantly old stellar population with ages exceeding 2 Gyr, with the largest contributions seen at the nucleus and decreasing outwards. Meanwhile, the young and intermediate age stellar populations exhibit a positive gradient with increasing radius and a circum-nuclear star-forming ring with radius of ∼0.5 kpc traced by stars younger than 20 Myr, is observed. This, along with the fact that AGN and SF dominated regions present similar gaseous oxygen abundances, suggests a shared reservoir feeding both star formation and the AGN. We have estimated a maximum outflow rate in ionized gas of ∼1.26 M⊙ yr−1 observed at a distance of ∼560 pc from the nucleus. The corresponding maximum kinetic power of the outflow is ∼3.4 × 1041 erg s−1. This released energy could be sufficient to suppress star formation within the ionization cone, as evidenced by the lower star formation rates observed in this region.

Probing stellar populations and interstellar medium in early-type central galaxies

ABSTRACT In this study, we analyse the characteristics of stellar populations and the interstellar medium (ISM) in 15 107 early-type central galaxies from the SPIDER survey. Using optical spectra from the Sloan Digital Sky Survey (SDSS), we investigate stellar age (Age), metallicity (Z), visual extinction (AV), and H α equivalent width (EWH α) to understand the evolution of the baryonic content in these galaxies. Our analysis explores the relationship between these properties and central velocity dispersion (σ) and halo mass (Mhalo) for isolated centrals (ICs) and group centrals (GCs). Our results confirm that both ICs and GCs’ stellar populations and gas properties are mainly influenced by σ, with Mhalo playing a secondary role. Higher σ values correspond to older, more metal-rich stellar populations in both ICs and GCs. Moreover, fixed σ values we observe younger Ages at higher values of Mhalo, a consistent trend in both ICs and GCs. Furthermore, we investigate the ionization source of the warm gas and propose a scenario where the properties of ionized gas are shaped by a combination of cooling within the intracluster medium (ICM) and feedback from Active Galactic Nuclei (AGNs) assuming a Bondi accretion regime. We observe inherent differences between ICs and GCs, suggesting that the ratio between AGN kinetic power and ICM thermal energy influences EWH α in ICs. Meanwhile, gas deposition in GCs appears to involve a more complex interplay beyond a singular AGN–ICM interaction.

Probing the Interplay between Jets, Winds, and Multi-phase Gas in 11 Radio-quiet PG Quasars: A uGMRT-VLA Study

We present polarization-sensitive images from the Karl G. Jansky Very Large Array (VLA) at 5 GHz of 11 radio-quiet PG quasars. Based on the radio morphology, spectral index, and polarization properties from the VLA study, coupled with the findings of our previous 685 MHz uGMRT data, we find the presence of low-power jets on subarcsecond and arcsecond scales in nine sources; some show signatures of bent jets. The origin of radio emission remains unclear in the remaining two sources. Of the 11 sources, linear polarization is detected in four of them with fractional polarization ranging between 2% and 21%. In PG 1229+204, the inferred B-field direction is parallel to the local kiloparsec-scale jet direction. The inferred B-fields are transverse to the weak southward extension in PG 0934+013. For PG 0050+124 and PG 0923+129, the relationship between the B-field structure and radio outflow direction remains unclear. Localized or small-scale jet–medium interactions can be inferred across the sample based on the VLA jet kinetic power arguments and polarization data. These may have the potential as a feedback mechanism. We find that the radio properties do not show strong correlations with the star formation, [O iii] and CO quantities published in the literature. The lack of evidence of AGN feedback on the global galaxy properties could be due to the relative timescales of AGN activity and those over which any impact might be taking place.

A plausible link between dynamically unsettled molecular gas and the radio jet in NGC 6328

We report the detection of outflowing molecular gas at the center of the nearby radio galaxy NGC6328 (z = 0.014), which has a gigahertz-peaked spectrum radio core and a compact (2 pc) young double radio lobe tracing jet. Utilizing Atacama Large Millimeter/submillimeter Array (ALMA) CO(3 − 2) and CO(2 − 1) observations, as well as a novel code developed to fit the 3D gas distribution and kinematics, to study the molecular gas kinematics, we find that the bulk of the gas is situated within a highly warped disk structure, most likely the result of a past merger event. Our analysis further uncovers, within the inner regions of the gas distribution (R < 300 pc) and at a position angle aligning with that of the radio jet (150°), the existence of two anti-diametric molecular gas structures kinematically detached from the main disk. These structures most likely trace a jet-induced cold gas outflow with a total lower limit mass of 2 × 106 M⊙ mass, corresponding to an outflow rate of 2 M⊙ yr−1 and a kinetic power of 2.7 × 1040 erg s−1. The energy required to maintain such a molecular outflow is aligned with the mechanical power of the jet.

A new discovery space opened by eROSITA

Context.In the context of an evolutionary model, the outflow phase of an active galactic nucleus (AGN) occurs at the peak of its activity, once the central supermassive black hole (SMBH) is massive enough to generate sufficient power to counterbalance the potential well of the host galaxy. This outflow feedback phase plays a vital role in galaxy evolution.Aims.Our aim in this paper is to apply various selection methods to isolate powerful AGNs in the feedback phase, trace and characterise outflows in these AGNs, and explore the link between AGN luminosity and outflow properties.Methods.We applied a combination of methods to the Spectrum Roentgen Gamma (SRG) eROSITA Final Equatorial Depth survey (eFEDS) catalogue and isolated ∼1400 candidates atz > 0.5 out of ∼11 750 AGNs (∼12%). Furthermore, we narrowed down our selection to 427 sources that have 0.5 < z < 1. We tested the robustness of our selection on the small subsample of 50 sources with available good quality SDSS spectra at 0.5 < z < 1 and, for which we fitted the [OIII] emission line complex and searched for the presence of ionised gas outflow signatures.Results.Out of the 50 good quality SDSS spectra, we identified 23 quasars (∼45%) with evidence of ionised outflows based on the presence of significant broad and/or shifted components in [OIII]λ5007 Å. They are on average more luminous (logLbol ∼ 45.2 erg s−1) and more obscured (NH ∼ 1022cm−2) than the parent sample of ∼427 candidates, although this may be ascribed to selection effects affecting the good quality SDSS spectra sample. By adding 118 quasars at 0.5 < z < 3.5 with evidence of outflows reported in the literature, we find a weak correlation between the maximum outflow velocity and the AGN bolometric luminosity. On the contrary, we recovered strong correlations between the mass outflow rate and outflow kinetic power with the AGN bolometric luminosity.Conclusions.About 30% of our sample have kinetic coupling efficiencies,Ė/Lbol> 1%, suggesting that the outflows could have a significant effect on their host galaxies. We find that the majority of the outflows have momentum flux ratios lower than 20 which rules out an energy-conserving nature. Our present work points to the unequivocal existence of a rather short AGN outflow phase, paving the way towards a new avenue to dissect AGN outflows in large samples within eROSITA and beyond.

Reliability of phase-specific outcome measurements in change-of-direction tests using a motorized resistance device.

This study aims to determine test-retest reliability of phase-specific information during initial acceleration, deceleration, and re-acceleration phases of different change-of-direction (CoD) tests using a motorized resistance device (MRD). A total of 21 participants (16 males and five females, with mean age of 22.3 ± 3.9 years, body mass of 75.2 ± 6.9 kg, height of 177.9 ± 6.8 cm) completed the modified 505 (m505), 10-0-5, and 15-0-5 CoD tests on four different test sessions while exposed to an external load (3 kg) provided by the MRD. Outcome variables included overall and phase-specific kinetic (force, power, and impulse) and kinematic (time, distance, velocity, and acceleration/deceleration) data during the initial acceleration, deceleration, and re-acceleration phases. The deceleration and re-acceleration phases were further divided into two subphases, namely, early and late subphases, using 50% of maximum velocity. Reliability was assessed using an intraclass correlation coefficient (ICC), coefficient of variation (CV), typical error (TE), and minimal detectable change (MDC). Good to excellent ICC values (>0.75) and acceptable (<10%) to good (<5%) CV values were observed for most outcome measurements. Specifically, 80.1% (822 out of 1,026) of all variables showed good or better relative reliability (i.e., ICC ≥ 0.75), while 97.0% (995 out of 1,026) of all variables showed acceptable or better absolute reliability (i.e., CV < 10%). In conclusion, the present study demonstrates that the MRD can obtain reliable phase-specific outcome measurements across different CoD tests, providing coaches and researchers with new opportunities to advance our understanding of CoD ability and inform more advanced CoD training prescriptions.

Jet power extracted from ADAFs and the application to Fermi BL Lacertae objects

ABSTRACT We calculate the jet power of the Blandford–Znajek (BZ) model and the hybrid model based on the self-similar solution of advection-dominated accretion flows (ADAFs). We study the formation mechanism of the jets of BL Lacertae (BL Lacs) with known redshifts detected by the Fermi satellite after 10 yr of data (4FGL-DR2). The kinetic power of the jets of Fermi BL Lacs is estimated through radio luminosity. The main results are as follows. (1) We find that the jet kinetic power of about 72 per cent intermediate peak frequency BL Lacs (IBL) and 94 per cent high-frequency peak BL Lacs (HBL) can be explained by the hybrid jet model based on ADAFs surrounding Kerr black holes. However, the jet kinetic power of about 74 per cent low-frequency peak BL Lacs (LBL) cannot be explained by the BZ jet model or the hybrid model. (2) The LBL has a higher accretion rate than IBL and HBL. About 14 per cent IBL and 62 per cent HBL have pure optically thin ADAFs. However, 7 per cent LBL may have a hybrid structure consisting of an standard thin disc (SS) plus optically thin ADAFs. (3) After excluding the redshift dependence, there is a weak correlation between the jet kinetic power and the accretion disc luminosity for Fermi BL Lacs. (4) There is a significant correlation between inverse-Compton luminosity and synchrotron luminosity for Fermi BL Lacs. The slope of the relation between inverse-Compton luminosity and synchrotron luminosity for Fermi BL Lacs is consistent with the synchrotron self-Compton (SSC) process. The result may suggest that the high-energy components of Fermi BL Lacs are dominated by the SSC process.

Search for particle acceleration in two massive Wolf–Rayet stars using uGMRT observations

ABSTRACT Large wind kinetic power of Wolf-Rayet (WR) stars make them ideal targets in low radio frequencies to search for non-thermal emission due to relativistic particle acceleration. In this paper, we present observations of two WR stars, WR 114 and WR 142, in Band 4 (550–950 MHz) and Band 5 (1050–1450 MHz) using the upgraded Giant Meterwave Radio Telescope. Neither star is detected in the observed frequency bands, nor extended emission associated with them. The upper limit to the free–free radio emission from the stellar wind enables us to constrain the mass-loss rate of WR 114 to $\lesssim \rm 10^{-5}\, M_{ \odot }\, yr^{-1}$; this is a factor three smaller than previously estimated using spectroscopic modelling. If we further assume that the WR stars are binaries, the non-detection of synchrotron emission from the putative wind collision region implies that the stars are either in very wide binary systems away from periastron, or that the stars are in close binary systems with an orbital separation &amp;lt;70 AU for WR 114 and &amp;lt;20 AU for WR 142. The non-detection of low-frequency radio emission from these two systems thus provides evidence that narrows their nature, though it does not rule them out as bona fide particle-accelerating colliding-wind binaries.

Effect of variations in blade width on vertical shaft kinetic water turbine power

Various studies and observations have been carried out to produce a turbine design that suits the needs and the relatively low flow speed is a challenge that currently still requires further research. ThereforeThe aim of this research is to determine the effect of variations in the width of the bowl blade on the vertical shaft kinetic water turbine power.The research method used is an experimental method with an experimental design on a laboratory scale. Tests were carried out on three variations of blade width, from the results of the study it can be concluded that increasing the water flow rate, turbine rotation, and the ratio of tangential speed to the turbine blade width can increase the kinetic water turbine power. In this study, variations in blade width were 10 cm, 11 cm, and 12 cm. Increasing turbine blade sheets increased turbine power due to the additional mass of the flow hitting the turbine blades thereby affecting the kinetic water turbine power. Analysis of the water flow rate shows that the maximum turbine power occurs at a blade width of 12 cm and a discharge of 0.017 m3/second with a turbine power value of 25.455 Watt. Analysis of turbine rotation, Maximum turbine power occurs at a blade width of 12 cm and rotation of 80 rpm with a turbine power value of 23,864 Watts. Meanwhile, analysis of the tangential speed ratio shows that the maximum turbine power occurs at a blade width of 12 cm and at a tangential speed ratio of 0.5 rad/s2 with a turbine power value of 23,864 Watts.&#x0D; Keywords: Blade width, power, kinetic turbine, vertical shaft.

Effect of wind turbulences on the burning of a rockrose hedge

With climate change, complex fire scenarios at Wildland Urban Interfaces (WUI) have become a growing concern for authorities worldwide. Such scenarios involve unfavorable wind conditions, which greatly increase the fire spread near communities and makes the intervention of firefighters even more complex. To design effective fire safety regulations to protect communities, it is important to have a clear understanding of the role of wind in the burning of vegetation to help identify the vectors of fire spread within the defensible zone. In this context, this paper attempts to relate the properties of the flames generated by the burning of a reconstructed rockrose hedge to the atmospheric wind turbulence using four field-scale experiments. The experimental setup includes 3 visible cameras to record the flame geometry, extracted by post-processing; 3 pairs of radiant and total heat fluxes to record the heat fluxes downstream of the hedge, and an anemometer to measure the wind speed and direction. The results show that the wind at the experimental site is composed of wall-bounded turbulent structures coupled with strong and short intermittent events such as gusts. Regarding the fire, the four replicates show similarities in phase durations and dynamics, but revealed dependencies on Reynolds number and turbulent kinetic energy when averaging over the fully developed flame phase. In addition, a slight flapping motion of the ensemble flame was observed and associated with wave numbers of the order of the turbulent cascade in the kinetic energy power spectra. Finally, the analysis of wind and fire intermittencies revealed that strong and short wind events generate large fluctuations of flame geometry and received heat fluxes that increase with the characteristic time of the event considered.

General Physical Properties of Fermi Blazars

We study the general physical properties of Fermi blazars using the Fermi fourth source catalog data (4FGL-DR2). The quasi-simultaneous multiwavelength data of Fermi blazars are fitted by using the one-zone leptonic model to obtain some physical parameters, such as jet power, magnetic field, and Doppler factor. We study the distributions of the derived physical parameters as a function of black hole mass and accretion disk luminosity. The main results are as follows. (1) For a standard thin accretion disk, the jet kinetic power of most flat-spectrum radio quasars can be explained by the Blandford–Payne (BP) mechanism. However, the jet kinetic power of most BL Lacertae objects (BL Lacs) cannot be explained by either the Blandford–Znajek mechanism or the BP mechanism. The BL Lacs may have advection-dominated accretion flows surrounding their massive black holes. (2) After excluding the redshift, there is a moderately strong correlation between the jet kinetic power and jet radiation power and the accretion disk luminosity for Fermi blazars. These results confirm a close connection between jet and accretion. The jet kinetic power is slightly larger than the accretion disk luminosity for Fermi blazars. (3) There is a significant correlation between jet kinetic power and gamma-ray luminosity and radio luminosity for Fermi blazars, which suggests that gamma-ray luminosity and radio luminosity can be used to indicate the jet kinetic power.

Effects of Exergames and Conventional Physical Therapy on Functional Physical Performance in Older Adults: A Randomized Controlled Trial.

Objective: To evaluate the effects of exergames added to a conventional physical therapy (CPT) program on functional fitness and dynamometric muscle performance for the sit-to-stand (STS) maneuver in older adults and to compare their results concerning a CPT-only intervention. Materials and Methods: Fifty independent older adults were randomly assigned to CPT and exergames (CPT+ExG group; n = 25; age = 71.8 ± 6.8 years) or CPT alone (CPT group; n = 25; age = 71.3 ± 7.4 years). CPT was performed twice a week (60 min/session) for 8 weeks. The CPT+ExG group added exergames for 30 minutes in each session. The Senior Fitness Test was applied, considering the 30-second chair stand test as the primary outcome. Additionally, dynamometric muscle performance during the STS maneuver was assessed. Results: The CPT+ExG group improved the 30-second chair stand (lower body strength), back scratch (upper body flexibility), and 8-foot up-and-go (agility/dynamic balance) tests (all P < 0.05). Both groups improved the kinetic dynamometric variables peak force, peak power, and total work (all P < 0.05). Also, both groups improved the 30-second arm curl test (upper body strength) (P < 0.05), although the increase was higher in the CPT+ExG group compared with the CPT group (time × group; P < 0.05). Conclusion: Adding exergames to a CPT program only significantly increases upper limb strength compared with CPT alone. The findings of this study have implications for the design of future exergame interventions focused on improving STS maneuver performance in older adults.

Energy optimization of main hydraulic system in a forging press by simulation and experimental methods

The primary cause of the low energy efficiency of hydraulic presses (HPs) is the mismatch between installed power and demanded power. This study adopts the concept of a high-pressure waterjet cutting system and presents an energy-saving method to reduce the energy dissipation of HPs, where a single drive system composed of multi motor-pumps and superchargers-accumulators, is integrated into an HP and partitioned into several drive zones corresponding to load profiles. Meanwhile, a method for scheduling the above system is presented to realize an orderly energy supply with no conflict and shorten the idle time. Pump units, accumulators, and superchargers were selected according to the different load profiles to energize the actuators in various operation stages. Since the kinetic power of the hydraulic oil output from superchargers are significantly higher than those of a conventional power unit, a press with low installed power could achieve high power load operations. Finally, the proposed system was applied to a 31.5 MN forging HP as a case study. Results showed that the installed power and the energy dissipation were reduced by 56% and 52% in one working cycle, respectively. Moreover, the novel HP displayed a processing performance equivalent to that of the conventional setup.

Local positive feedback in the overall negative: the impact of quasar winds on star formation in the FIRE cosmological simulations

ABSTRACT Negative feedback from accreting supermassive black holes is considered crucial in suppressing star formation and quenching massive galaxies. However, several models and observations suggest that black hole feedback may have a positive effect, triggering star formation by compressing interstellar medium gas to higher densities. We investigate the dual role of black hole feedback using cosmological hydrodynamic simulations from the Feedback In Realistic Environment (FIRE) project, incorporating a novel implementation of hyper-refined accretion-disc winds. Focusing on a massive, star-forming galaxy at z ∼ 2 ($M_{\rm halo} \sim 10^{12.5}\, {\rm M}_{\odot }$), we demonstrate that strong quasar winds with a kinetic power of ∼1046 erg s−1, persisting for over 20 Myr, drive the formation of a central gas cavity and significantly reduce the surface density of star formation across the galaxy’s disc. The suppression of star formation primarily occurs by limiting the availability of gas for star formation rather than by evacuating the pre-existing star-forming gas reservoir (preventive feedback dominates over ejective feedback). Despite the overall negative impact of quasar winds, we identify several potential indicators of local positive feedback, including (1) the spatial anticorrelation between wind-dominated regions and star-forming clumps, (2) higher local star formation efficiency in compressed gas at the edge of the cavity, and (3) increased contribution of outflowing material to local star formation. Moreover, stars formed under the influence of quasar winds tend to be located at larger radial distances. Our findings suggest that both positive and negative AGN feedback can coexist within galaxies, although the local positive triggering of star formation has a minor influence on global galaxy growth.