Effects Of Expansion Research Articles

CFD modeling of gas−liquid flow phenomenon in lead smelting oxygen-enriched side-blown furnace

A validated numerical model was established to simulate gas−liquid flow behaviors in the oxygen-enriched side-blown bath furnace. This model included the slip velocity between phases and the gas thermal expansion effect. Its modeling results were verified with theoretical correlations and experiments, and the nozzle-eroded states in practice were also involved in the analysis. Through comparison, it is confirmed that the thermal expansion effect influences the flow pattern significantly, which may lead to the backward motion of airflow and create a potential risk to production safety. Consequently, the influences of air injection velocity and furnace width on airflow behavior were investigated to provide operating and design guidance. It is found that the thin layer melt, which avoids high-rate oxygen airflow eroding nozzles, shrinks as the injection velocity increases, but safety can be guaranteed when the velocity ranges from 175 to 275 m/s. Moreover, the isoline patterns and heights of thin layers change slightly when the furnace width increases from 2.2 to 2.8 m, indicating that the furnace width shows a limited influence on production safety.

Influence of thermal expansion and wear on the temperatures and stresses in railway disc brakes

Thermo-mechanical coupled systems are typically complex, however, the demand for analyses of this kind of multi-physics system is increasing, for example, accurately predicting the temperature and thermal stress of the railway disc brakes. However, many models ignore the phenomenon of thermal expansion and wear on brake pads. Therefore, their influence on the result is unclear. This research aims to investigate the effect of these two phenomena on the temperatures and stresses. These influences represent different heat flux input methods. Based on the finite element method (FEM), a three-dimensional (3D) transient thermo-mechanical model is built up. Three cases with or without thermal expansion and wear are conducted. The model is validated against measurement data. Simulation results show that thermal expansion and wear on the brake pads cause a 10% difference in the average temperatures of the brake discs, while a 257% difference in the maximum temperatures. As for the equivalent stresses (Von Mises stress), the difference can reach 3500%. Overall, this research builds a thermo-mechanical model and quantifies the effects of thermal expansion and wear on the temperatures and stresses of railway brake discs. The model can be transferred to other thermo-mechanical coupled multi-physics systems.

Postcolonial city walks in Germany at the nexus of activism, education, and tourism

Abstract In various ways, postcolonial initiatives in Germany contribute to the formation of ‘national cultures of remembrance’ and to the debate about Europe’s responsibility for the negative effects of colonial expansion that can still be felt today. One approach, which the activist groups use in their educational and activist work, is that of the guided walking tour – a method that allows them to sensitize an interested audience to colonially contoured spaces in German cities. Interestingly, the postcolonial initiatives do not see themselves as providers of tourist services, even though they use the rather fundamental touristic form of the ‘city walk’. As this discrepancy in perception allows discussions about tourism in a more general, conceptual sense, this paper examines the tours at the nexus of activism, education, and tourism. Thereby, it asks what constitutes the walks and discusses their relation to urban tourism. To do so, the article first explains relevant concepts of tourism geographies and postcolonial studies and then connects them to insights gained from the qualitative and quantitative analysis of empirical data collected in a field phase in Germany in 2022.

FLORES: VERDADEIRO RESERVATÓRIO DE ANTIBIÓTICOS E RESINAS ANTIMICROBIANAS

Microbial resistance is the versatility of microorganisms not to succumb to the harsh environment and to maintain themselves in all environmental compartments, organisms and living cells. This phenomenon is a mechanism of acquired adaptation that directly impacts humans and animals, as these organisms have disharmonious relationships with them, causing several practically intractable pathologies, leading to the death of the host. The World Health Organization points out, every year, the increase of microorganisms resistant to drugs, both for domestic and hospital use, publishing in its reports, the frightening reality of organisms resistant to all commercialized drugs, being called Pan-resistant. Therefore, the objective of the study is to investigate in fresh, freshly picked flowers, a new substance with antimicrobial and/or bactericidal power against Enterobacteria. Of the 66 flowers studied, 29 showed some promising antibiotic/bactericidal effect, with passion fruit and mallow being the ones that stood out the most, followed by dahlia and munguba. The hexane extract of the passion fruit flower showed a halo of formation greater than Gentamicin and Amikacin, of 22 mm with only 0.5 g of the flower. Several studies describe the complexity of substances found in passion fruit flower, making it difficult to indicate a possible organic group or the combination of mixed organic compounds with synergistic effects. The mallow flower, which has the coumarin malvina and the terpenoid malvona exclusively, presented an inhibition halo comparable to antibiotic discs already used in drug therapies, with an effect on all three Enterobacteriaceae studied, Salmonella serotype thyphimurium NCTC® 12023, multiresistant Escherichia coli, and the pan-resistant bacterium kpcKlebsiella planticola2019, being a great antimicrobial potential. For a similar bacteriostatic effect of propolis, 22 flowers expressed a glutinous, expansive and resinous effect, in order to immobilize and prevent an aggressive and pathogenic agent from expressing its metabolism or life cycle, with the highlight being azalea, presenting the largest halo.Thus, it is possible to infer that the production of propolis by bees is the sum of the harvesting of resins from several species of flowers, both exotic and native, in the manufacture of the best resin to protect their hives. Finally, the trend of phytotherapy combined with modern biotechnological science may be the key to success against highly specialized parasites. This study falls under SDG 13 (quality health) and SDG 15 (life on land) of the development goals.

Dual-Gradient Concentration Distribution in Sb-Cu Alloy Nanoarrays for Robust Sodium-Ion Storage.

Alloy-type materials are attractive for anodes in sodium-ion batteries (SIBs) owing to their high theoretical capacities and overall performance. However, the accumulation of stress/strain during repeated cycling results in electrode pulverization, leading to rapid capacity decay and eventual disintegration, thus hindering their practical applications. Herein, we report a 3D coral-like Sb-Cu alloy nanoarray with gradient distribution of both elements. The array features a Sb-rich bottom and a Cu-rich top with increasing Sb and decreasing Cu concentrations from top to bottom. The former is the active component that provides the high capacity, whereas the latter serves as an inert additive that acts against volume variation. The gradual transition in composition within the electrode introduces a ladder-type volume expansion effect, facilitating a smooth distribution and effective release of stress, thereby ensuring the wanted mechanical stability and structural integrity. The as-developed nanoarray affords a high reversible capacity (460 mAh g-1 at 0.5 C), stable cycling (89 % retention over 120 cycles at 1.0 C), and superior rate capability (354 mAh g-1 at 10 C). The concentration dual-gradient strategy paves a new pathway of designing alloy-type materials for SIBs.

“School near workplace” or “school near home”: Which one is better for the morning commute with both individual and household travelers in Y-shaped networks?

Household travelers typically need to coordinate their travel decisions in various aspects, such as destination and trip-timing, resulting in distinctive travel patterns compared to individual travelers. This paper investigates the morning commute problem in a “Y-shaped” network featuring “school near workplace” in consideration of both individual and household travelers and further understands the impact of school locations on the morning commute by comparing it with the “school near home” network. We analytically derive all equilibrium cases in the “school near workplace” network and classify them into three traffic patterns. We analyze the welfare effects of the staggering policy, finding that implementing the staggering policy in the “school near workplace” network can achieve a “win–win” scenario for individuals and household travelers in some equilibrium cases. Also, when the capacity ratio of school-constrained bottleneck to common-constrained bottleneck is below a threshold, which one is better (i.e., “school near workplace” or “school near home”) depends on the free-flow travel costs of the two networks. Locating the school “near workplace” is better than “near home” when the difference in the free-flow related costs for children between the two networks is not very large. Furthermore, we analyze the welfare effects of bottleneck expansion in the “school near workplace” network, finding that bottleneck expansion paradox may emerge when expanding the school-constrained bottleneck. Although properly designing the schedule gap can eliminate the paradox, a significant increase in the schedule gap may be needed to escape from the paradoxical cases when the common-constrained bottleneck capacity is slightly larger than the school-constrained bottleneck capacity. Our study sheds light on the importance of school locations in determining the performance of traffic management policies in the morning commute with both individual and household travelers.

Amorphous AlPO4 Layer Coating Vacuum Thermal Reduced SiOx with Fine Silicon Grains to Enhance the Anode Stability.

Micrometer-sized silicon monoxide (SiO) is regarded as a high-capacity anode material with great potential for lithium ion batteries (LIBs). However, the problems of low initial Coulombic efficiency (ICE), poor electrical conductivity, and large volume change of SiO inevitably impede further application. Herein, the vacuum thermal reduced SiOx with amorphous AlPO4 and carbon double-coating layers is used as the ideal anode material in LIBs. The vacuum thermal reduction at low temperature forms fine silicon grains in the internal particles and maintains the external integrity of SiOx particles, contributing to mitigation of the stress intensification and the subsequent design of multifunctional coating. Meanwhile, the innovative introduction of the multifunctional amorphous AlPO4 layer not only improves the ion/electron conduction properties to ensure the fast reversible reaction but also provides a robust protective layer with stable physicochemical characteristics and inhibits the volume expansion effect. The sample of SiOx anode shows an ICE up to 87.6% and a stable cycling of 200 cycles at 1 A g-1 with an initial specific capacity of 1775.8 mAh g-1. In addition, the assembled pouch battery of 1.8 Ah can also ensure a cycling life of over 150 cycles, demonstrating a promising prospect of this optimized micrometer-sized SiOx anode material for industrial applications.

Influence of CO2 on asphaltene adsorption dynamics at the Oil-Gas Interface: New insights into precipitation and aggregation processes

To investigate the effect of CO2 on the precipitation of asphaltene in oil, and verify the advantages of CO2 flooding, this work designs interfacial tension experiments and PVT system experiments to create the experimental environment under different temperature and pressure conditions that make CO2 contact with oil. The results indicate that CO2 can affect the oil morphology, and the trend of oil volume increase and decrease depends on the dynamic balance between the expansion effect and the component extraction effect of CO2 on oil. Under low pressure, the oil expansion caused by dissolved CO2 dominates the experiments, increasing the oil volume. Under high pressure, sufficient CO2 in the oil activates its component extraction effect, and the asphaltene in the oil precipitates and accumulates at the interface between the oil and CO2 due to the disruption of the component equilibrium of the system, exerting a surface activity effect, leading to a decrease in oil volume. Due to the movement of asphaltene towards the system interface and the formation of an asphaltene film during this stage, which hinders the entry of CO2 into the oil, the interfacial tension shows three linear decreasing trends with increasing pressure. This mechanism also changes the variation trend of the oil volume in CO2 during the pressure increase. Moreover, the components of the oil extracted by CO2 will be transferred to CO2, making its properties similar to oil. With the reduction of interfacial tension, this process promotes the miscibility between the two. These effects verify that CO2 can improve the fluidity and quality of oil during reservoir development, and reduce or even eliminate the adhesion work required for the working fluid to displace the oil. These conditions are conducive to improving reservoir development efficiency, reflecting the great application value of CO2 flooding.

Evolution of Displacement Speed Statistics During Head-On Flame-Wall Interaction within Turbulent Boundary Layers

ABSTRACT The statistical behaviours of the density-weighted displacement speed and its curvature and strain rate dependence during head-on interaction of statistically planar premixed flames have been analysed based on Direct Numerical Simulations. The analysis has been conducted within turbulent boundary layers featuring inert walls, under both isothermal and adiabatic wall boundary conditions. The flame quenches due to heat loss when it reaches close to the wall in the case of isothermal wall boundary condition. By contrast, the flame can propagate all the way to the wall before extinguishing due to the consumption of reactants in the case of adiabatic wall boundary conditions. Thus, the effects of thermal expansion, quantified by dilatation rate, and flame normal acceleration during flame-wall interaction in the case of the isothermal wall are weaker than that in the case of the adiabatic wall case due to flame quenching. This gives rise to significant differences in the curvature and strain rate dependences of the reactive scalar gradient magnitude, which affects the statistical behaviours of the reaction and normal diffusion components of density-weighted displacement speed including their mean values, widths of their probability density functions, and their local strain rate and curvature dependences. It has been found that the interaction of near-wall vortical structures with flame surface increases the range of curvature variation during head-on interaction, which acts to widen the probability density function of the density-weighted displacement speed. This trend is relatively stronger for the isothermal wall boundary condition because of the larger variation of the reaction rate component of the density-weighted displacement speed due to local flame quenching, which also acts to widen the range of the density-weighted displacement speed variation in comparison to that in the case of adiabatic wall boundary conditions. Although the qualitative nature of curvature, strain rate, and stretch rate dependences of the density-weighted displacement speed remain unaffected by the wall boundary condition, the strength of the correlation changes with the progress of head-on interaction. It has been found that the negative correlation between the density-weighted displacement speed and flame curvature weakens with the progress of head-on interaction, which gives rise to a reduction in the strength of the correlation between the density-weighted displacement speed and flame stretch rate. Similarly, the correlation between the tangential strain rate and the density-weighted displacement speed weakens with the progress of head-on interaction. Detailed physical explanations are provided for these behaviours, and their modeling implications are indicated.

The crowding out effect of local government debt expansion: Insights from commercial credit financing

Understanding the impact of local government debt expansion on microeconomic entities is crucial in evaluating local government debt policies. This study explored the crowding-out effect of local government debt on firms' commercial credit financing. We found that local government debt plays a crucial role in enhancing corporate commercial credit financing by exacerbating the financing constraints faced by firms. Second, the impact of local government debt on commercial credit financing is more pronounced for firms with lower leverage and a more stable capital chain. Third, state-owned enterprises (SOEs) are more susceptible to the impact of local government debt on commercial credit financing compared to private enterprises. And the crowding-out effect of local government debt on firms' commercial credit financing is more pronounced in the regions where the credit market regulation is relatively weaker. Our findings provide valuable insights that can contribute to the reform of the local government debt management system.

Experimental study on the effect of reaming on the fatigue life of split-sleeve cold-expanded Ti–6Al–4V alloy components

The split-sleeve cold expansion technique has been widely used in the aerospace industry to improve the fatigue life of metal components with holes. Due to the morphology change after the expansion, a reaming process is necessary to improve the machining accuracy of the hole surface. This final reaming process might change the residual stress distribution around the hole significantly but the effect of the reaming ratio has not been fully explored. This paper investigated the effect of reaming depth on the fatigue life of split-sleeve cold-expanded Ti–6Al–4V alloy components using a series of experiments, including the residual stress measurements, uniaxial fatigue tests, and fracture morphology observations. The expectations of the fatigue cycles were estimated using the 2-parameter Weibull distribution and the S-N curves of different components were acquired. Residual stress measuring results and the fracture surface observations explained the effect of cold expansion and reaming on the components. The experimental results showed that the fatigue life of the components decreased with the increase of the reaming ratio, demonstrating that excessive reaming depth is harmful to the fatigue performance of the cold-expanded components.

The interplay between urban expansion, human capital accumulation and innovation performance in Chinese cities

ABSTRACT The impact of spatial expansion on innovation performance has garnered widespread attention. This study establishes a two-sector equilibrium model to elucidate the transmission mechanism among urban expansion, human capital and innovation performance. Our findings indicate that the synergy between compact expansion and human capital enhances innovation performance. Drawing from a sample of 281 cities spanning 2005–2018, we observe that Chinese cities demonstrate compact expansion patterns, and human capital fosters the synergy effect of innovation. Furthermore, the synergistic effect of compact expansion and human capital formation is more pronounced in cities with larger populations, higher income levels and stronger regional status. These results offer both theoretical contributions and practical insights for shaping more effective urbanisation patterns and enhancing innovation capacity.

Effect of particle diameter and void fraction on gas–solid two-phase flow: a numerical investigation using the Eulerian–Eulerian approach

AbstractSudden expansion pipes are crucial in fluid dynamics for studying flow behavior, turbulence, and pressure distribution in various systems. This study focuses on investigating the behavior of a two-phase flow, specifically a gas–solid turbulent flow, in a sudden expansion. The Eulerian–Eulerian approach is employed to model the flow characteristics. The Eulerian–Eulerian approach treats both phases (gas and solid) as separate continua, and their interactions are described using conservation equations for mass, momentum, and energy. The study aims to understand the complex phenomena occurring in the flow, such as particle dispersion, turbulence modulation, and pressure drop. The governing equations are solved using house developed code called FORTRAN, a widely used programming language in scientific and engineering simulations. The results of this study will provide valuable insights into the behavior of gas–solid two-phase flows in sudden expansions, which have important applications in various industries, including chemical engineering, energy systems, and environmental engineering. A parametric study of the impact of particles diameters (20, 120, 220, 500 µm), the solid volume loading ratios $$(0.005, 0.008, 0.01)$$ ( 0.005 , 0.008 , 0.01 ) and area ratios (2.25, 5.76, 9) effect of sudden expansion on the streamlines, local skin friction, pressure, velocity, turbulent kinetic energy, and separation zone.

Spillover Effects of Urban Expansion on Land Green Use Efficiency: An Empirical Study Based on Multi-Source Remote Sensing Data in China

Land is an important carrier of resource elements, and improving land green use efficiency (LGUE) is the key to achieving “smart growth” in cities. This study takes 269 cities in China from 2008 to 2020 as the research object and integrates multisource remote sensing data, GIS spatial analysis, and spatial econometric models to explore the evolutionary characteristics of LGUE and the spatiotemporal effects of urban expansion on LGUE. The results show that (1) urban LGUE increases over time and has certain gradient distribution and spatial dependence characteristics; (2) urban expansion has a significant inverted U-shaped relationship with LGUE, indicating that maintaining reasonable urban expansion is the key to improving LGUE, but excessive urban expansion has a strong negative spatial effect on LGUE. In terms of spillover effect, for every 1% increase in the square term of urban expansion, the LGUE of the local city decreases by 0.0673%, but the neighboring city increases by 0.2283%; and (3) urban expansion has significant spatiotemporal heterogeneous effects on LGUE, and spatial development boundaries must be reasonably determined to achieve “smart growth”. Currently, some cities in China are expanding rapidly, and we hope to provide key support for promoting the “smart growth” of cities and improving LGUE.

Analysis of deformation and multi-angle tip contact in a combined mechanism of thin-walled membrane forces and inextensible layers in soft actuators

Soft actuators have extensive applications in operations, are generally made of elastomers, and generate large deformation. It makes accurately predicting their deformation behavior challenging. This study considers the combined effects of chamber sidewall expansion and inextensible layer strain mechanisms on the actuator's bending and tip contact force. We separately model the expansion of the chamber sidewall and the strain in the inextensible layer using the expanding membrane and strain beam theory. The theoretical model presented to predict the contact area of the sidewall expanding membrane under multiple bending conditions. The analytical models for three actuator states are established: 1) Free space; 2) Tip contact at multiple angles; and 3) Grasping state. The proposed theoretical model accurately predicts deformation, force characteristics, and the requisite pressure for object grasping, and its applicability extends to similar soft actuators. Comparative analyses with finite element methods (FEM) and experimental results validate the model's computational efficiency, reduced design variables, and accurate prediction of diverse deformations and tip contact forces. Notably, the model outperforms with shorter computation times. The large and small chamber spacing errors are approximately 10 % and 5 %, respectively.

Interfacial engineering in SnO2-embedded graphene anode materials for high performance lithium-ion batteries

Tin dioxide is regarded as an alternative anode material rather than graphite due to its high theoretical specific capacity. Modification with carbon is a typical strategy to mitigate the volume expansion effect of SnO2 during the charge process. Strengthening the interface bonding is crucial for improving the electrochemical performance of SnO2/C composites. Here, SnO2-embedded reduced graphene oxide (rGO) composite with a low graphene content of approximately 5 wt.% was in situ synthesized via a cetyltrimethylammonium bromide (CTAB)-assisted hydrothermal method. The structural integrity of the SnO2/rGO composite is significantly improved by optimizing the Sn–O–C electronic structure with CTAB, resulting a reversible capacity of 598 mAh g−1 after 200 cycles at a current density of 1 A g−1. CTAB-assisted synthesis enhances the rate performance and cyclic stability of tin dioxide/graphene composites, and boosts their application as the anode materials for the next-generation lithium-ion batteries.

Flameless venting characteristics and design model of micro-nano PMMA dust explosion

The effects of Fe–Ni foam thickness and dust size on flame propagation, reduced overpressure, and venting efficiency in 30 μm and 150 nm polymethyl methacrylate (PMMA) dust explosions were investigated. The flame quenching mechanism was revealed by coupling the heat transfer and flow of the dust flame within the Fe–Ni foam. It is found that micron dust is more prone to quenching than nano dust, and the differences in the quenching process of micro-nano dust are explained by combining the dust combustion kinetics and the theory of inter-particle heat transfer. The pressure venting mechanism of micro-nano dust was analysed under different thicknesses of Fe–Ni foam, and the thermal expansion effect of the flame passing through the Fe–Ni foam and its flow resistance significantly increased the reduced explosion overpressure. The flow continuity of the micro-nano dust was classified by means of the Knudsen number (Kn), which elucidates the effect of dust size differences on the pressure evolution. A prediction model for the maximum reduced explosion overpressure is proposed based on the explosion pressure venting of micro-nano dust. Changes in vented pressure have a direct impact on the efficiency of flameless venting. Nano-dust has an efficiency of more than 20 % lower than that of micron dust.

Dynamic Programming-Based Track-before-Detect Algorithm for Weak Maneuvering Targets in Range–Doppler Plane

This paper focuses on detecting and tracking maneuvering weak targets in the range–Doppler (RD) plane with the track-before-detect (TBD) algorithm based on dynamic programming (DP). Traditional DP-TBD algorithms integrate target detection and tracking in their framework while searching the paths provided by a predefined model of the kinematic properties within the constraints allowed. However, both the approximate motion model used in the RD plane and the model mismatch caused when the target undergoes a maneuver can degrade the TBD performance sharply. To address these issues, this paper accurately describes the evolution of the RD equation based on Constant Acceleration (CA) and Coordinated Turn (CT) motion models with the process noise in the Cartesian coordinate system, and it also employs a recursive method to estimate the parameters in the equations for efficient energy accumulation and path searches. Facing the situation that targets energy accumulation during the DP iteration process will lead to an expansion of the target energy accumulation process. This paper designs a more efficient Optimization Function (OF) to inhibit the expansion effect, improve the resolution of the nearby targets, and increase the detection probability of the weak targets simultaneously. In addition, to search the trajectory more efficiently and accurately, we improved the process of DP multi-frame accumulation, thus reducing the computation amount of large-scale searches. Finally, the effectiveness of the proposed method for CA and CT motion target detection and tracking is verified by many of the simulation experiments that were conducted in this paper.

Simulating the effects of medicaid expansion on the opioid epidemic in North Carolina

Expanding Medicaid plays a large role in ensuring that people across the United States have access to health care services. Although North Carolina recently moved toward Medicaid expansion, the impact of expansion on overdoses and overdose mortality may vary based on the type of treatment (offering medications for opioid use disorder [MOUD] vs. offering inpatient medically managed withdrawal without linkage to further MOUD treatment or non–MOUD-based treatment) accessed by individuals newly eligible for treatment through expansion. Based on official North Carolina statistics and published peer-reviewed literature, we developed a simulation model that forecasts opioid overdose and mortality under different scenarios for type of treatment accessed (MOUD-based vs. non–MOUD-based) and Medicaid coverage levels. An optimistic scenario assuming 70 % of individuals newly eligible for treatment would enter treatment during the first year of expansion estimated that 332 (Simulation Interval: 246–412) overdose deaths would be averted. A scenario more in line with recent historical trends assuming 38 % of individuals newly eligible for treatment would enter treatment resulted in 213 (Simulation Interval: 157–263) averted overdose deaths. In all scenarios, MOUD-based treatment approaches increased the number of lives saved compared with approaches expanding opioid treatment through non–MOUD-based treatment. Our study emphasized the need to ensure access to MOUD-based treatment for individuals newly covered by the Medicaid expansion.

Tourism development and carbon emissions in sub-Saharan African countries: is there an inverted U-shaped relationship?

ABSTRACT In this study, we examine the existence of an inverted U-shaped relationship between tourism and carbon emissions in 29 sub-Saharan African (SSA) countries using data from 1995 to 2019. Departing from the previous studies, we have also grouped SSA countries into low- and middleincome countries, thereby estimating three panels. We have used a wide range of panel estimation techniques to examine this linkage, including the dynamic common-correlated effects (DCCE), the Driscoll-Kraay estimators, and the fully-modified OLS (FMOLS). Our results show that the relationship between tourism and carbon emissions depends largely on the estimation technique used and the level of income of the individual countries. Overall, we can conclude that there is primafacie evidence of an inverted U-shaped relationship between tourism and carbon emissions in middle-income countries and all SSA countries combined, but not in low-income countries. This means that the perceived adverse effects of tourism expansion on environmental pollution may only be experienced in the early stages of tourism development and that as the tourism sector develops, tourism is likely to promote energy conservation through sustainable tourism or green tourism, thereby leading to a reduction in carbon emissions. Policy implications are discussed.