Diffuse Sources Research Articles

Search of extended emission from HESS J1702-420 with eROSITA

is a peculiar TeV complex with a morphology changing from a diffuse source ( at $ 2$ TeV to a point-like one ( at $ 10$ TeV energies. The morphology and spectral properties of could be understood in terms of (diffusive) hadronic or leptonic models in which the observed TeV emission arises correpondingly from proton-proton or IC-radiation of relativistic particles present in the region. In this work, we perform searches of the X-ray counterpart of the source originating from the synchrotron emission of the primary or secondary relativistic electrons produced within leptonic or hadronic models. Such an emission can be extended and remain beyond the detection capabilities of narrow field-of-view instruments such as We utilised the publicly available first-6-months eROSITA dataset (DR1) fully covering the selected analysis region of $>5^ around We discuss biases connected to variable plasma temperature or neutral hydrogen column density in the region and present results based on the background modelling approach. The performed analysis does not allow us to detect the extended X-ray counterpart of of $0.07^ sizes. The derived upper limits are significantly higher than the expected hadronic model flux of the X-ray counterpart. For the leptonic model, the derived limits indicate the magnetic field in the region $B We argue that further advances in the diffuse X-ray counterpart searches could be achieved with either next-generation missions or Msec-long observational campaigns using currently operating instruments.

Global classical solutions to an indirect chemotaxis-consumption model with signal-dependent degenerate diffusion and logistic source

Global classical solutions to an indirect chemotaxis-consumption model with signal-dependent degenerate diffusion and logistic source

Global sensitivity analysis of water level response to harmonic aquifer disturbances through a Monte-Carlo based surrogate model with random forest algorithm

Oscillatory water levels are often observed in monitoring wells, when aquifers are disturbed by periodical pressure diffusion (PD) sources, such as oscillatory pumping and ocean tide, and by volumetric strain (VS) sources including the far-field seismic wave and earth tide. The measured water level responses are extensively utilized to interpret aquifer properties and seismic hydrological phenomena. However, owing to wellbore effects, water levels are not always truly representative of pore pressure in aquifers, and can be significantly attenuated or even unobservable in wells. To clarify how water level responds to these disturbances, this study analyzes a global parameter sensitivity of the coupled well-aquifer model based on the assumption of a confined homogeneous aquifer. Parameter uncertainties concerning aquifer properties, source characteristics, and wellbore construction are first analyzed separately for the PD and VS sources. Subsequently, Monte-Carlo based surrogate models linking parameters and response indices are developed using the random forest algorithm. For the PD source, sensitivity results indicate that hydraulic conductivity is the most influential parameter for the yes/no responses. When hydraulic conductivity exceeds 10-4 m/s, water level observations basically represent pore pressure in aquifers. Significant amplitude changes and phase delay occur when the period of disturbances is less than 50 s, majorly due to water column inertia. For VS sources, water level responses are typically observed in aquifers with hydraulic conductivity larger than 10-7 m/s and when disturbed by a source with amplitude greater than 10-3 MPa. However, pronounced amplitude changes and phase shifts occur when the source period varies within 100 s. Consideration of the impact of wellbore effects is recommended, when interpreting water level responses induced by all periodic aquifer disturbances, especially in low-conductivity aquifers with conductivities less than 10-4 m/s.

Probing particle acceleration in Abell 2256: From 16 MHz to gamma rays

Merging galaxy clusters often host spectacular diffuse radio synchrotron sources. These sources can be explained by a non-thermal pool of relativistic electrons that are accelerated by shocks and turbulence in the intracluster medium. The origin of the pool and details of the cosmic ray transport and acceleration mechanisms in clusters are still open questions. Due to the often extremely steep spectral indices of diffuse radio emission, it is best studied at low frequencies. However, the lowest frequency window available to ground-based telescopes (10−30 MHz) has remained largely unexplored as radio frequency interference and calibration problems related to the ionosphere become severe. Here, we present LOFAR observations from 16 to 168 MHz targeting the famous cluster Abell 2256. In the deepest-ever images at decametre wavelengths, we detected and resolved the radio halo, radio shock, and various steep spectrum sources. We measured standard single power-law behaviour for the radio halo and radio shock spectra, with spectral indices of α = −1.56 ± 0.02 from 24 to 1500 MHz and α = −1.00 ± 0.02 from 24 to 3000 MHz, respectively. Additionally, we found significant spectral index and curvature fluctuations across the radio halo, indicating an inhomogeneous emitting volume. In contrast to the straight power-law spectra of the large-scale diffuse sources, the various AGN-related sources showed extreme steepening towards higher frequencies and flattening towards low frequencies. We also discovered a new fossil plasma source with a steep spectrum between 23 and 144 MHz, with α = −1.9 ± 0.1. Finally, by comparing radio and gamma-ray observations, we ruled out purely hadronic models for the radio halo origin in Abell 2256, unless the magnetic field strength in the cluster is exceptionally high, which is unsupportable by energetic arguments and inconsistent with the knowledge of other cluster magnetic fields.

High resolution identification and quantification of diffuse deep groundwater discharge in mountain rivers using continuous boat-mounted helium measurements

Discharge of deeply sourced groundwater to streams is difficult to locate and quantify, particularly where both discrete and diffuse discharge points exist, but diffuse discharge is one of the primary controls on solute budgets in mountainous watersheds. The noble gas helium is a unique identifier of deep groundwater discharge because groundwater with long residence times is commonly enriched in helium. In this study, a portable mass spectrometer was used to measure longitudinal variation in dissolved helium concentrations in two mountainous rivers at high spatial resolution not feasible with traditional sampling techniques. Helium profiles were then simulated using a mass-balance model to quantify longitudinal variation in groundwater discharge to the receiving rivers. Results indicate helium concentrations were enriched by multiple orders of magnitude above atmospheric equilibrium in both rivers and that this persisted for up to 18 km below observed pulse inputs in the Colorado River. Helium mass-balance models match observed longitudinal patterns with the exception of sharp initial increases in helium observed in the rivers. Increased longitudinal groundwater discharge rates correspond to mapped geologic structures in both watersheds that likely transport deep geothermal water. Models show variable sensitivity to spatial assignment of input variables representing the groundwater source, illustrating the importance of collecting data from discrete groundwater discharges where possible. The methodology shows promise for field experiments designed to assess air–water exchange rates and to quantify total groundwater discharge from a combination of discrete and diffuse sources.

Modeling the Enceladus dust plume based on in situ measurements performed with the Cassini Cosmic Dust Analyzer

We analyzed data recorded by the Cosmic Dust Analyzer on board the Cassini spacecraft during Enceladus dust plume traversals. Our focus was on profiles of relative abundances of grains of different compositional types derived from mass spectra recorded with the Dust Analyzer subsystem during the Cassini flybys E5 and E17. The E5 profile, corresponding to a steep and fast traversal of the plume, has already been analyzed. In this paper, we included a second profile from the E17 flyby involving a nearly horizontal traversal of the south polar terrain at a significantly lower velocity. Additionally, we incorporated dust detection rates from the High Rate Detector subsystem during flybys E7 and E21. We derived grain size ranges in the different observational data sets and used these data to constrain parameters for a new dust plume model. This model was constructed using a mathematical description of dust ejection implemented in the software package DUDI. Further constraints included published velocities of gas ejection, positions of gas and dust jets, and the mass production rate of the plume. Our model employs two different types of sources: diffuse sources of dust ejected with a lower velocity and jets with a faster and more colimated emission. From our model, we derived dust mass production rates for different compositional grain types, amounting to at least 28 kg/s. Previously, salt-rich dust was believed to dominate the plume mass based on E5 data alone. The E17 profile shows a dominance of organic-enriched grains over the south polar terrain, a region not well constrained by E5 data. By including both E5 and E17 profiles, we find the salt-rich dust contribution to be at most 1<!PCT!> by mass. This revision also results from an improved understanding of grain masses of various compositional types that implies smaller sizes for salt-rich grains. Our new model can predict grain numbers and masses for future mission detectors during plume traversals.

Моделирование системы очистки сточных вод животноводческих ферм

Among the sources of pollution of surface water bodies from agricultural activities, livestock, pig and poultry complexes can be prioritized, which are uncontrolled and diffuse sources of suspended solids, organic compounds, biogenic elements, heavy metals and pathogenic microflora, which causes biochemical pollution and has a particularly detrimental effect on the state of inland reservoirs. Wastewater from agricultural processing enterprises and household water from rural settlements with unpredictable pollutants play a significant role in pollution. The livestock sector is one of the largest consumers of water. The large number of animals in a confined space, the use of hydraulic harvesting systems when removing their waste products, leads to the formation of manure in significant quantities. Sanitary and hygienic standards in industrial premises are supported with the help of water – animals are washed with it, rooms are cleaned, and they are disinfected, food is prepared, dishes and equipment are washed, manure is washed off with water, and so on. Accordingly, as the demand for water in animal husbandry increases, the volume of wastewater discharge that contains manure into nearby water bodies increases. The effluents that are formed as a result of the activities of the livestock sector are classified as containing a large amount of harmful substances with a high concentration. Depending on the sources of pollution and the main pollutants, technical solutions should be developed to reduce the volume of wastewater and its treatment. The effectiveness of their functioning can be ensured with the help of modern information processing methods, using methods of system analysis of complex objects based on a mathematical description of the technological process. To analyze the state of the treatment system as a whole and predict the development of emergency situations, a software implementation of a wastewater treatment system for livestock farms was created.

Diagnosis of The State and Changes in The Ecosystem of Lake Onego and Watershed Based on The Information-Analytical System

The results of the diagnosis of the state and changes in the ecosystem of Onegskoe Lake (Lake Onego) and the watershed are presented using the developed information and analytical system “Lake Onego-watershed” (IAS), consisting of a comprehensive database (DB), a combined database of Roshydromet and Northern water problems institute/Karelian Research Center of the Russian Academy of Sciences on the nutrient load for the modern period 1995–2022, the ILLM mathematical model for assessing the removal of nutrients from the watershed and the formation of the nutrient load on the lake and the 3D-mathematical model SPLEM, developed for Lake Onego. Information was collected on the main sources of nutrient load in the Lake Onego catchment area, as well as available field observation data on the flow of nitrogen and phosphorus into the lake. The contribution of different nutrient sources coming from river runoff, diffuse sources, urban discharges and from trout farms was calculated for the lake and the main limnic areas. Based on data from field observations over the past 30 years and the results of numerical experiments using the SPLEM model with a grid resolution of 1 km it is shown that the ecosystem of the lake not only did not restored after the reduction in anthropogenic load after 1991, but eutrophication of waters in the lips and bays continues due to the influence of industrial and agricultural enterprises, trout farms and noticeable climate warming. Functional for the IAS “Lake Onego-catchment” to visualize the main modeling results on a 1 km grid was developed, and a web application interface has been created.

Insight into the effect of Ce content on the magnetic properties of Ce-magnets with grain boundary diffusion Pr-Al alloys

The development of cost-effective Ce-magnets with high Ce content is urgent to realize the vision of cost reduction and performance enhancement. Dual-main-phase Ce-magnets with different Ce content (Ce accounted for the total amount of rare earths is 40%, 50% and 60%) are prepared. The Pr80Al20 (at%) alloy is selected as diffusion source for the three magnets using the grain boundary diffusion technique under the same conditions. The correlation of magnetic properties and microstructures before and after diffusion with different Ce contents are systematically analyzed. According to the EPMA results, the presence of Ce in the magnets facilitates the diffusion of Pr elements along the grain boundaries, which significantly increases the diffusion depth of Pr inside the magnets. As a consequence, the percentage increment of coercivity increase with the Ce content due to the increased diffusion depth. This study provides new insight into the preparation of dual-main-phase Ce-magnets with high Ce content of 40–60%.

Boosting efficiency and oxidation resistance of Pr-Tb-Cu diffusion source for Nd-Fe-B magnets by synergistic modification of Al or Ni

Diffusion efficiency and oxidation resistance of Pr-Tb-Cu source were simultaneously improved by introducing Al or Ni. The diffusion efficiency of source is effectively improved by deepening element infiltration and modifying interface of the magnet. The added Al or Ni forms a passivation layer on the source and increases the amorphous phase in the source, thus maintaining a high efficiency of sources after oxidation. Furthermore, the modified sources enhanced the chemical stability of magnet mainly because of the increased Volta potential of intergranular phase. This study provides a potential strategy for exploring high-efficient and durable diffusion sources for Nd-Fe-B magnets.

A hybrid radiative energy transfer and image source method for high-frequency vibrational coupled plates

A hybrid approach composed of the radiative energy transfer method (RETM) and image source method (ISM) is proposed in this study for estimating the vibrational energy of coupled plates loaded by high-frequency point excitation. The vibrational energy at a receiver is represented by energy density and intensity, which are superposed by incoherent rays emitted by the load point in the analyzed domain and reflected/transmitted by the domain boundaries. The energy rays reflected/transmitted at the boundaries are described by two modes: diffuse reflection/transmission, which is a basic assumption in RETM, and the other obeys Snell’s law of reflection/refraction, which is deduced by Fermat’s principle and often applied in ISM. The local energy response distribution in the loading subsystem is described by ISM. The energies in other subsystems are described by RETM. The energy transfer relationship between subsystems is expressed by the energy transfer coefficient. At the boundary of coupled plates, a Fredholm equation of the second type is established through the balance among the outgoing energy of the diffuse reflection fictitious sources and the incident energy of actual sources, other diffuse reflection sources, and specular reflection image sources, which can be used to determine the intensity of the diffuse reflection fictitious sources. The average energy transfer coefficient in the transmission direction half-space is used to express the energy transfer relationship associated with diffuse reflection sources, while the energy transfer relationship associated with specular reflection sources is expressed directly by the energy transfer coefficient. Numerical tests show that the energy distributions and energy flow fields of typical coupled plates are well predicted by the proposed hybrid RETM-ISM approach. Compared with RETM, hybrid RETM-ISM is more consistent with the FEM solution.

Alternatives to 137Cs for 210Pb dating validation in south America and in the Carribean region: Point and diffuse sources

As today the 137Cs fallout peak, in sediment cores, corresponds only to 25% of its initial concentration, alternatives to the use of 137Cs as a210Pb sediment dating validation tool are proposed. In highly industrialized bays, such as Guanabara Bay in the Rio de Janeiro metropolitan region, several chemical/compounds from the surrounding industry releases may be applied as validation tools. Chromium and copper profiles in a sediment core adequately fit the expected pattern due to the implementation of a chemical plant in 1958, reaching their maximum discharge in 1982 and subsequently decreasing due to the operation of a new wastewater treatment plant. A diffuse source such, as the PCB-based mixture Askarel, was also applied as an alternative validation tool, and the observed concentration profile reproduced the expected behavior, with increasing concentration after the Second World War and a decrease after the ban of this product in 1981. The observed Aroclor 1254 and 1260 mixture chlorination rates fit the most widely distributed PCB-based products in the country.

Transport and reactivity of nitrous oxide and methane in two contrasting subterranean estuaries

AbstractContinental groundwaters are commonly enriched in nitrous oxide (N2O) and methane (CH4), which can discharge into the coast. The contribution of this diffuse source to coastal N2O and CH4 emissions largely depends on the biogeochemical processes of coastal aquifer exit zones, known as subterranean estuaries. Here, we study the role of subterranean estuaries in modulating N2O and CH4 exports toward the coast. The two studied subterranean estuaries are located at Panxón and Ladeira beaches (Ría de Vigo, NW Iberian Peninsula) and had opposite oxygenation at their interior. Groundwater‐borne N2O was detected in the oxygenated subterranean estuary of Panxón Beach, although denitrification attenuated N2O before porewater was discharged into the coast. An N2O hotspot was detected at about 50 cm depth in this subterranean estuary, characterized by the presence of nitrate under suboxic conditions. This N2O also seems to be consumed along the flow path before discharging into the coast. The anoxic subterranean estuary of Ladeira Beach completely removed groundwater‐borne N2O. Yet, nitrification within its suboxic upper saline plume produced and exported N2O toward the coast, hiding the role of this subterranean estuary as an N2O sink. The anoxic subterranean estuary exported CH4 toward the coast. This CH4 was not sourced by continental groundwater, hence it was produced in situ fuelled by the accumulation of organic matter within the beach. The suboxic upper saline plume in Ladeira Beach and the oxygenated subterranean estuary of Panxón Beach acted as CH4 sinks.

Optimizing the grain boundary structure of sintered Nd-Fe-Co-B magnets by Dy-Al-Cu alloys grain boundary diffusion

The substitution of Fe by Co can effectively increase the Curie temperature of Nd-Fe-B magnets. However, the enrichment of Co in the grain boundary phase makes the grain boundary phase change from nonmagnetic to ferromagnetic, which has a harmful effect on the coercivity. In this paper, Dy70Al10Cu20 alloy was used as the diffusion source for grain boundary diffusion of sintered Nd-Fe-Co-B magnets. The magnetic properties and microstructure of the magnets were investigated by controlling the coating thickness of the diffusion source (thickness of 0.03 mm, 0.09 mm, and 0.15 mm). The results show that the coercivity of the magnet after diffusion is increased to 17.63 kOe, which is 9.69 kOe higher than that of the undiffused magnet. The phase composition analysis shows that the original magnet contains the soft magnetic 2:17 phase, and the 2:17 phase is significantly reduced after diffusion. The microstructure observation shows that the main phase is connected and the grain boundary phase is absent in the high Co original magnet. After diffusion, the thin grain boundary phase in the magnet increases, which effectively isolates the main phase grains. Dy-rich shell is formed on the surface of the main phase grain, which is beneficial to the improvement of coercivity. Therefore, magnetic hardening of Dy-rich shells and exchange-decoupling strengthening of adjacent 2:14:1 grains isolated by intergranular phases contributed to further coercivity increment Hcj of magnet simultaneously. Studies have shown that grain boundary diffusion is an effective way to improve the microstructure of Nd-Fe-Co-B magnets.

Modelling Current-State N- and P-Fluxes into Surface Waters in Germany

For the first time, the AGRUM model consortium—consisting of the agro-economic model RAUMIS, the water balance model mGROWA, the hydrological nutrient transport models DENUZ, WeKu and MEPhos, and the urban emission model MONERIS—was jointly set up throughout Germany (357,000 km2). This provided a nationwide consistent nutrient model to capture the current status of N and P inputs to surface waters from diffuse sources and urban areas. Diffuse nutrient emissions were quantified in high spatial resolution for the input pathways’ groundwater, drainage runoff, and natural interflow (100 m × 100 m), as well as for water erosion and wash-off (25 m × 25 m). The sum of diffuse nutrient inputs to surface waters is about 385,000 metric tons N/yr and ca. 11,530 metric tons P/yr. Urban emissions were quantified either as point source inputs (wastewater treatment plants, industrial direct dischargers) or at municipality scale for different collection and treatment systems, e.g., rainwater sewers or decentralized treatment plants, and sum up to ca. 95,000 t N/yr and 7500 t P/yr. As modelled, total N and P inputs into surface waters correspond well with observed N and P loads in rivers. The model results represent valuable information for water managers, being responsible for the preparation of management plans for the third management cycle of the EC Water Framework Directive spanning from 2021 to 2027.

Green technology diffusion model and simulation considering enterprise technology absorption capacity

ABSTRACT The diffusion and wide application of green technologies are important means to achieve climate change mitigation. Concerning the green technology absorption capacity and technology diffusion willingness of enterprises, this paper divided enterprises into four categories, constructed a green technology diffusion model and analysed the equilibrium point and stability of the model. Then, we studied the diffusion process and laws of green technology through simulation experiments. The results show that in the green technology diffusion system, the basic regeneration number is the key factor in determining the equilibrium state of green technology diffusion. The disease-free equilibrium point of the green technology diffusion system is globally asymptotically stable, and the endemic equilibrium point is locally asymptotically stable. In order to improve the speed and scale of green technology diffusion, it is necessary to create green technology diffusion sources through multiple channels, improve enterprise technology absorption capacity through multiple methods, and enhance enterprise green technology diffusion willingness at multiple levels.

Ultra-low-frequency LOFAR spectral indices of cluster radio halos

A fraction of galaxy clusters harbor diffuse radio sources known as radio halos. The prevailing theory regarding their formation is based on second-order Fermi reacceleration of seed electrons caused by merger-driven turbulence in the intra-cluster medium. This mechanism is expected to be inefficient, which implies that a significant fraction of halos should have very steep energy spectra ($ We start investigating the potential and current limitations of the combination of the two surveys conducted by LOFAR, LoTSS (144 MHz) and LoLSS (54 MHz), to probe the origin of radio halos. We followed up the 20 radio halos detected in Data Release 1 of LoTSS, which covers the HETDEX field, with the LoLSS survey, and we studied their spectral properties between 54 and 144 MHz. After removing compact sources, nine halos were excluded due to unreliable halo flux density measurements at 54 MHz. Our main finding is that 7 out of 11 (sim 64<!PCT!>) exhibit an ultra-steep spectrum ($ < -1.5$), which is a key prediction of turbulent reacceleration models. We also note a tentative trend for more massive systems to host flatter halos, although the currently poor statistics do not allow for a deeper analysis. Our sample suffers from low angular resolution at 54 MHz, which limits the accuracy of the compact-source subtraction. Nevertheless, this study is the first step toward providing compelling evidence for the existence of a large fraction of radio halos with a very steep spectrum, which is a fundamental prediction of turbulent reacceleration models. In this regard, the forthcoming second data release of LoLSS, along with the integration of LOFAR international stations and the instrumental upgrade to LOFAR2.0, will improve both the statistics and the low-frequency angular resolution, allowing us to determine the origin of radio halos in galaxy clusters conclusively.

Dynamics of stratified-convected Eyring-Powell nanoliquid featuring chemically reactive species and Ohmic dissipation: Application of Levenberg-Marquardt artificial neural networks(ALM-ANNs)

Magnetic nanoliquids are pondered cutting-edge heat transference liquids, representing a modern generation because of their aptitude to function as smart liquids. The deployed magnetism externally exerts a readily manageable impact, escalating their adaptableness and practicality in various applications. In this analysis, electro magnetized Powell-Eyring rheological nanoliquid is modeled considering stretching cylinder based buoyancy-driven flow. Transport expressions include thermal radiation, Brownian diffusion, chemical reaction, thermophoresis, and thermal source effect. Prandtl theory of boundary-layer (BL) assists to develop the governing problems. Appropriate transformations are deployed to obtain the dimensionless problems which are then computed numerically through the novel Levenberg-Marquardt artificial neural networks(ALM-ANNs). It is worth to mention that the close agreement between the error analysis of the reference dataset and the proposed datasets roughly from E−10 to E−03, further justifies the approaches utilized in this study. Besides the excellent measures of performance in terms of MSE are achieved at level 5.77E−11, 4.41E−11, 2.09E−12, 2.16E−11, 1.03E−11, 1.65E−11, 2.00E−11, and 1.91E−11against 272, 416, 266, 391, 142, 366, 425, and 508 epochs for first instance of all eight various scenarios. The acquired outcomes are compared with alternate analytical (homotopy) scheme and good agreement is witnessed. Furthermore it is noticed that as the values of Pr,RandS1 increase in size, so does the EPFM temperature profile θ, and the evaluation of AE is between E-04 to E-10.

Human exposure to per- and polyfluoroalkyl substances (PFAS) via the consumption of fish leads to exceedance of safety thresholds

Per- and polyfluoroalkyl substances (PFAS) receive global attention due to their adverse effects on human health and the environment. Fish consumption is a major source of human PFAS exposure. The aim of this work was to address the lack of harmonization within legislations (in the EU and the USA) and highlight the level of PFAS in fish exposed to pollution from diffuse sources in the context of current safety thresholds. A non-exhaustive literature review was carried out to obtain PFAS concentrations in wild fish from the Norwegian mainland, Svalbard, the Netherlands, the USA, as well as sea regions (North Sea, English Channel, Atlantic Ocean), and farmed fish on the Dutch market. Median sum wet weight concentrations of PFOA, PFNA, PFHxS, and PFOS ranged between 0.1 µg kg−1 (farmed fish) and 22 µg kg−1 (Netherlands eel). Most concentrations fell below the EU environmental quality standard (EQSbiota) for PFOS (9.1 µg kg−1) and would not be defined as polluted in the EU. However, using recent tolerable intake or reference dose values in the EU and the USA revealed that even limited fish consumption would lead to exceedance of these thresholds – possibly posing a challenge for risk communication.

Kinetics of voids evolution during diffusion bonding of dissimilar metals on consideration of the realistic surface morphology: Modeling and experiments

A comprehensive model for analyzing the kinetics of void evolution and shrinkage during dissimilar diffusion bonding is proposed based on the sinusoidal profile. The model incorporates atom accumulation at void tip to determine the curvature radius of void neck, and integrates the local effect of surface diffusion to quantify the contribution of surface diffusion, thus avoiding the unrealistic void evolution observed in previous models. Furthermore, the model utilizes a combined diffusion coefficient for multicomponent alloys under the effect of stress and concentration gradients, to determine the interfacial diffusion coefficient for dissimilar joints. In contrast to previous models, the current model demonstrates significant improvements in predicted accuracy, efficiently depicting the realistic void evolution and interpreting the formation of various interfacial voids, which can be applied in various bonding cases, including for the dissimilar base metals with different surface conditions. Simulation results from bonding between austenitic steel and ferritic steel with different surface roughness reveal that interfacial voids predominantly form on the side of the base metal with the rougher bonding surface. Additionally, as surface roughness decreases, the prevailing surface source diffusion and interface source diffusion mechanisms promote void evolution and shrinkage, resulting in a significant reduction of the final bonding time. To achieve a high-quality bonding joint, it's suggested to place the smoother bonding surface on the higher creep-resistant base metal, which can accelerate the void closure process.