Ion escape is a key mechanism driving the long-term atmospheric evolution of Mars, and variations in solar wind conditions significantly influence ion escape rates. However, the different responses of various ion species within plume and tailward escape channels under varying solar wind velocities and densities remain poorly understood, hindering a comprehensive understanding of Martian atmospheric loss processes. To address this issue, we employ a three-dimensional multifluid MHD model to systematically simulate the escape behaviors of three major heavy ion species (O+, O2 +, and CO2 +) under different solar wind conditions. We propose a novel dynamic channel separation method based on the location of the magnetic pile-up boundary, which enables an accurate distinction between plume and tailward escape regions. This approach allows for a more precise assessment of escape rates, channel contributions, and energy spectra by ion species. Simulation results show that: (a) the total escape rates of all three ions increase significantly with rising solar wind density and velocity, with tailward escape showing a steeper increase. (b) As solar wind density increases, O2 + replaces O+ as the dominant escaping ion. Although CO2 + exhibits the lowest total escape rate, it shows the highest sensitivity to solar wind variations. (c) Energy spectral analysis reveals clear differences between the two escape channels. Plume escape ions generally have higher energies, with O+ more energetic than O2 + and CO2 +. In contrast, the energy of escaping ions shows a positive correlation with ion mass in the tailward escape channel.

Positron emission tomography (PET) technology, with its advantages of strong γ-photon penetration and results unaffected by temperature or electromagnetic fields, has emerged as a novel non-contact monitoring technique for industrial flow fields under harsh conditions. However, dynamic sampling leads to a severe lack of photon data within individual time frames, resulting in an ill-posed nature of positron image reconstruction, which introduces uncertainty in noise statistical characteristics and degradation in imaging quality. This paper proposes a novel noise-suppressing super-resolution enhancement module for positron flow field imaging. The module, based on convolution and SwinTransformer structures, achieves noise reduction and enhancement of positron images under conditions of severe photon scarcity. Furthermore, a multi-loss fusion performance evaluation system is constructed to extract texture and hierarchical feature information from the images. Experimental results demonstrate that the proposed module effectively reduces image noise while preserving critical information, achieving significant improvements in the quality of generated positron flow field images.

Studies commonly assumed that variations in ionospheric conductance were insignificant and proposed that vorticities can be a reliable proxy or diagnostic for ionospheric field-aligned currents (FACs). We propose a complete method for measuring FACs using data from the Super Dual Auroral Radar Network radar and the Defense Meteorological Satellite Program. In our method, the FACs are determined by three terms. The first term is referred to as magnetospheric-origin FACs, while the second and third terms are known as ionospheric-origin FACs. This method incorporates height-integrated conductances based on observational data, thereby addressing the limitation of assuming uniform conductances. Different from previous works, we can calculate FACs at a low altitude of 250 km and obtain high-resolution measurements within observable areas. Another advantage of this method lies in its ability to directly calculate and analyze the impact of ionospheric vorticity and conductance on FACs. We apply this method to obtain FACs in the Northern Hemisphere from 2010 to 2016 and analyze the distributions of height-integrated conductances and total FACs. Our analysis reveals that the average FACs clearly exhibit the large-scale R1 and R2 FAC systems. We conduct statistical analysis on magnetospheric-origin FACs and ionospheric-origin FACs. Our findings show that within the auroral oval, ionospheric-origin FACs reach a comparable level to magnetospheric-origin FACs. However, ionospheric-origin FACs are significantly minor and almost negligible in other regions. This implies that height-integrated conductance gradients and vorticities play equally significant roles within the auroral oval, whereas vorticities dominate in other regions. Field-aligned currents (FACs) refer to current sheets that flow parallel or antiparallel to the geomagnetic field lines in the polar region. Typically, the intensity of FACs is estimated using magnetic perturbation measurements, while the current density is determined by the thickness of current sheets. In this study, we propose another method for calculating FACs based on ionospheric plasma vorticities and conductances. This method allows for FAC calculations at lower altitudes compared to previous methods. Additionally, we investigate the significance of vorticities and height-integrated conductance gradients on FACs. Our findings reveal that both height-integrated conductance gradients and vorticities significantly influence FACs in auroral emission areas. However, the influence of vorticities is more pronounced in other areas. We proposed a complete method for measuring ionospheric field-aligned currents (FACs) Within the auroral oval, both height-integrated conductance gradients and vorticities play equally important roles In non-auroral regions, vorticities take on a dominant role in influencing FACs

Whistler-mode waves have been extensively observed and investigated in terrestrial space. In this study, we present the dynamic response of whistler-mode waves to different solar wind conditions in the dayside terrestrial space based on Magnetospheric Multiscale (MMS) data. Statistical results show that the occurrence rate, amplitudes, and corresponding electron temperature anisotropy of whistler-mode waves increase with P _sw in the dayside terrestrial space, which is attributed to the compression of magnetic fields in these magnetosheath and outer magnetosphere. Furthermore, whistler-mode waves under the southward interplanetary magnetic fields (IMFs) show a higher occurrence rate than that under the northward IMFs, mostly corresponding to T _e _⊥ / T _e _∥ > 1, and have a higher occurrence rate during quasi-radial IMFs. These results present that whistler-mode waves in these magnetosheath and outer magnetosphere are also modulated by the solar wind as clearly as the inner magnetosphere. This work advanced our understanding in the solar–terrestrial interaction.

Using a global magnetohydrodynamics numerical simulation, this work compares the interaction of the solar wind with Mars and Earth from the perspective of energy transfer under north–south interplanetary magnetic fields (IMFs). Mars lacks a global dipole magnetic field like Earth’s and instead has a small-scale crustal magnetic field near highlands in the southern hemisphere. Unlike Earth’s magnetopause reconnection (at the subsolar point or tail under a southward IMF, or behind the cusp under a northward IMF), the reconnection of the Martian magnetic pileup boundary (MPB) occurs near solar zenith angle (SZA) ≈ 45° (SZA ≈ 30° and 60°) for a southward (northward) IMF, resulting in asymmetric energy transfer between the northern and southern hemispheres. The Martian outflow of mechanical energy appears near SZA ≈ 45° (SZA ≈ 30° and 60°) under a southward (northward) IMF, accompanied by an inflow due to the process of “solar wind pickup.” For energy transfer across the MPB, whether the IMF is northward or southward, the input of electromagnetic energy is twice as large as the input of mechanical energy, which is similar to Earth’s magnetopause for a southward IMF, but opposite to it for a northward IMF. The energy transfer rate of the MPB is slightly higher in a northward IMF than in a southward one, whereas the energy transfer rate of Earth’s magnetopause is far higher in a southward IMF than in a northward one.

Images from positron emission tomography (PET) for non-destructive testing of industrial cavities have low resolution and blurred edges. This study proposes an algorithm based on depth of interaction information to improve the image edge recognition and restoration. A synchronous iterative filter–maximum likelihood expectation maximisation (SIF–MELM) algorithm is proposed based on the traditional MLEM algorithm to improve the imaging quality. A set of engine blade simulation models is designed to verify the performance of the algorithm. Image quality evaluations are conducted on the images reconstructed by the algorithm before and after improvement. A set of wind tunnel oil flow experiments are designed to verify the effectiveness and superiority of this method. Experimental results show that, the peak signal-to-noise and structural similarity of the reconstructed images increase from 23.99 and 0.60 to 27.37 and 0.73, respectively. Moreover, the oil flow trajectory conforms to the simulation results.

As a flow display technique, the silk thread method can clearly show the state of the flow field. However, displaying the state of the flow field in industrial closed metal cavities is impossible, and results of the traditional silk thread method fail to present depth information. To address these limitations, we propose a display method based on γ-photon silk thread 3D imaging. Firstly, a flow field visualization experimental platform applicable for industrial closed metal cavity was designed. Then, aiming at the shortcomings of insufficient γ-photon scanning data and limited imaging quality in flow field visualization, an adaptive sinogram interpolation-iterative filtering reconstruction algorithm was proposed to expand the data via the adaptive interpolation processing of the sinogram in image reconstruction. Beltrami filtering was also embedded in the iterative algorithm to effectively reduce noise and artifacts in the imaging image. Finally, the internal flow field inspection of the NACA0018 airfoil and the industrial confinement turbine were used as examples to visualise the wing upper surface flow and turbine blade passage secondary flow, respectively, and the results were consistent with those of the numerical simulation analysis. As the angle of attack of the wing increased, laminar flow separation occurred, and the silk thread structure state changed to the point where the aircraft stalled. After the imaging map analysis, the stall angle ranged between (15°,19°), which is consistent with the simulation results. In the turbine blade passage secondary flow detection, the imaging map formed a horseshoe vortex with airflow separation at the central saddle point and silk threads clearly presenting the structural state of the flow field along different directions.

AbstractThe F10.7 solar radiation flux is a well‐known parameter that is closely linked to solar activity, serving as a key index for measuring the level of solar activity. In this study, the Variational Mode Decomposition (VMD) and Long Short‐term Memory (LSTM) network are combined to construct a VMD‐LSTM model for predicting F10.7 values. The F10.7 sequence is decomposed into several intrinsic mode functions (IMF) by VMD, then the LSTM neural network is utilized to forecast each IMF. All IMF prediction results are aggregated to obtain the final F10.7 value. The data sets from 1957 to 2008 are used for training and the data sets from 2009 to 2019 are used for testing. The results show that the VMD‐LSTM model achieves an annual average root mean square error of only 4.47 sfu and an annual average correlation coefficient (R) of 0.99 during solar cycle 24, which is significantly better than the accuracy of the LSTM model (W. Zhang et al., 2022, https://doi.org/10.3390/universe8010030), the AR model (Du, 2020, https://doi.org/10.1007/s11207-020-01689-x), and the BP model (Xiao et al., 2017, https://doi.org/10.11728/cjss2017.01.001). The VMD‐LSTM model exhibits strong predictive capability for the F10.7 index during solar cycle 24.

In order to realize the y-photon nondestructive detection of industrial confined pipelines, it is necessary to construct large axial ring y-photon detectors, but with the increase of the axial length of the detectors, the acquisition of response lines will be truncated and missing, resulting in the degradation of the detection imaging quality in large axial space. In this paper, we propose a list-mode data-based imaging algorithm for industrial confined pipe detection, which makes full use of the list-mode to conform to the position and time information in the event and to reasonably assign the weights of the system matrix in the image reconstruction. When calculating the weight contribution of the pixels passing through a response line to that response line, only the pixels within the uncertainty range need to be calculated without the pixels corresponding to the complete response line, and the system matrix containing time-of-flight (TOF) information is obtained, thus effectively suppressing the noise caused by truncated and missing large axial spatial data. In addition, the parallel feature of CUDA is also used to divide the system matrix calculation process into small blocks that are independent of each other to achieve accelerated optimization of the algorithm. Finally, two industrial models are used for simulation experiments, and the experimental results show that the proposed method can significantly improve the resolution and spatial contrast of large axial spatial reconstruction images in industrial confined pipeline inspection, and can meet the demand of y-photon nondestructive inspection of industrial confined pipelines.

In this paper, using a three-dimensional multispecies MHD model, we study the effect of the interplanetary magnetic field (IMF) intensity and orientation on the subsolar standoff distance of the Martian magnetic pileup boundary ( r 0 ) and the pressure balance across it. The results show that: (1) with the increasing magnitude of the Y- or Z- component of the IMF, B Y or B Z , r 0 increases, while the radial IMF component, B X , has little effect. With the increasing magnitude of B Y or B Z , the compression degree of the magnetic field ( f ) increases, while the solar wind pressure coefficient ( k ) remains unchanged, resulting in the enhancement of r 0 . (2) Under the same IMF intensity, B t , the impact of the IMF cone angle on r 0 and f is controlled by the ratio of the IMF Y- and Z- components to B t , B Y 2 + B Z 2 / B t . When the ratio is enhanced, both r 0 and f increase, while k generally remains unchanged. Compared with the IMF cone angle, the influence of the IMF clock angle is relatively less. We suggest that the stronger magnetic pileup process controlled by the perpendicular IMFs ( B Y or B Z ) causes the larger r 0 , while the weaker magnetic pileup under the radial IMF leads to the smaller r 0 . The difference in the IMF effect on the size of the Martian magnetic pileup boundary and the terrestrial magnetopause reveals different solar wind interactions with a magnetized and unmagnetized planet. Last, the location of the intense crustal field can also affect r 0 and the pressure balance condition, and the specific impact needs to be further studied.

The nondestructive characteristics of $\gamma $ -photon imaging technology make it attractive potential in the industry. However, in industrial detection with a large detection range and high resolution, iteration method, the image reconstruction algorithm which is most widely used, faces the challenge of an overly large system matrix, and the current compression algorithms using the geometric symmetry of the positron emission tomography (PET) system have problems of complex pixel division and recovery mode. Therefore, this study proposes a lossless compression and linear recovery algorithm of the system matrix based on a polar adaptive pixel (LCLR-PAP). Based on the structure of the detection ring and rotation of the circle, the detection field of view (FOV) is designed as a cylinder and the circular slice is divided into several sectors. The pixels are adaptively divided within the sector to realize the lossless compression of the system matrix from the structure, and based on which the angle change of pixels can be converted to matrix transformation to achieve linear recovery. A partial pixel partition is optimized to compensate for the unevenness of the pixel size in the center of the adaptive image. Experiments show that the LCLR-PAP algorithm can provide an efficient solution to the large-scale system matrix compression recovery problem, that is, through a simple and convenient adaptive pixel division with matrix sparsity and axial symmetry, the system matrix can be compressed to less than 100,000th of the original, and realize the lossless compression and fast linear recovery.

In $\gamma $ -photon industrial large-space high-resolution full 3-D nondestructive testing imaging, when there is a large increase in the number of detection crystals, the number of response lines, the number of computational tasks, and the storage space of the system matrix all increase dramatically; therefore, reducing computation time and storage space becomes challenging. In this study, we propose a $\gamma $ -photon high-resolution fast 3-D image reconstruction method based on a lossless equivalent system matrix (LESM), which divides the cylindrical effective field of view into multiple equivalent sector blocks, performs polar voxel discretization according to adaptive rules, and accurately calculates the system matrix corresponding to one equivalent sector block by a polar voxel stereo angle model. Furthermore, the system matrix elements corresponding to the remaining sector blocks are obtained by rotational symmetry. Meanwhile, the system matrix elements corresponding to the polar voxels in the equivalent sector block are divided into subsets according to radial and mirror symmetry to further reduce the number of system matrix elements that need to be computed, so as to realize the lossless compression and fast recovery of the 3-D system matrix. To improve the accuracy of the system matrix and effectively suppress noise, the error caused by the depth of interaction (DOI) is further reduced based on the LESM calculation, and the display of the image is completed by precomputing the mapping matrix ${T}$ . Parallel computing is used to accelerate the algorithm. Simulation and experimental results show that compared with the traditional Cartesian voxel method, the proposed method significantly reduces the computational tasks and storage space of the system matrix elements and improves the contrast and spatial resolution of industrial 3-D reconstructed images, thus meeting the demand of $\gamma $ -photon industrial large-space detection imaging.

In this study, we introduced a quantitative parameter, the magnetic field strength difference, to denote the intensity of the magnetic pileup effect at Mars. Using a three-dimensional multispecies MHD model, the effects of the interplanetary magnetic field (IMF) and the solar wind dynamic pressure (P d ) constituted with different densities and velocities on the magnetic pileup were examined. Our results show that: (1) the magnetic pileup at Mars mainly occurs at the dayside region and its magnitude is generally decreasing with increasing solar zenith angle. The magnetic pileup is generally weak in the intense crustal field region, while it is strong in the weak crustal field region. (2) The perpendicular IMF components, B Y and B Z , dominate the magnetic pileup, while the radial IMF component, B X , has little effect. In the intense crustal field region, when the IMF and crustal field are primarily in the same direction, the magnetic field is piled up and the pileup magnitude is generally strong. While the directions of the crustal field and IMF are opposite, the occurrence of magnetic reconnection can weaken the local magnetic pileup. (3) Under the same P d , a higher solar wind velocity results in a higher intensity and a larger region of the magnetic pileup. When P d increases, the magnitude of the magnetic pileup is enhanced, but the pileup region shrinks. In addition, for an increasing P d , at the center of the induced magnetotail, the asymmetric current sheet can lead to similar asymmetries of the pileup.

The Martian bow shock (BS) is generated with the mass-loading and magnetic pileup processes when the solar wind interacts with the Martian ionosphere. In this vein, the interplanetary magnetic field (IMF) frozen in the solar wind can affect the location of the Martian BS, which is less reported. Based on the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission, we manually identify 10,283 BS crossings during a period of the gradually declining solar cycle phase (2014 October–2020 December) and investigate the effects of the intensity and orientation of the IMF on the Martian BS. In the Mars Solar Orbital coordinate system, our results show the following: (1) The Martian BS, including the subsolar and flank regions, linearly moves away from Mars when the IMF intensity increases, which confirms the theoretical and the MHD simulation results. (2) Under the radial IMF condition, we first demonstrate that the subsolar and flank regions of the Martian BS are situated closer to Mars compared to other IMF situations. This might be caused by the weaker magnetic pileup process and the “low-pressure magnetosheath” model under the radial IMF condition. (3) Moreover, the cross section of the Martian BS is elongated in the north–south direction when the Y component of the IMF is dominant, which is on account of the fast magnetosonic speed effect and verifies the elongation phenomenon of the terrestrial BS. The IMF intensity and orientation effects cannot be ignored and should be considered in future models of the Martian BS.

Using global magnetohydrodynamic simulations, we construct a 3D parametric model of the Martian magnetic pileup boundary (MPB). This model employs a modified parabola function defined by four parameters. The effects of the solar wind dynamic pressure, the solar wind densities and velocities, and the intensity and orientation of the interplanetary magnetic field (IMF) are examined using 267 simulation cases. The results from our parametric model show that (1) the MPB moves closer to Mars when the upstream solar wind dynamic pressure (Pd) increases, the subsolar standoff distance decreases and the flaring degree of the Martian MPB increases with an increasing Pd according to the power-law relations. For the same Pd, a higher solar wind velocity (a lower density) leads to a farther location of the MPB from Mars, along with a larger flaring degree, which is explained by the higher solar wind convection electric fields and a stronger magnetic pileup process under these conditions. (2) Larger Y or Z components of the IMF, BY or BZ, result in a thicker pileup region and a farther MPB location from Mars, as well as a decrease in the flaring degree. The radial IMF component, BX, has little effect on the geometry of the MPB. (3) In most of the simulations used to derive the current parametric model, the strongest Martian crustal magnetic field is located on the dayside. However, for a larger value of the southward IMF, the Martian MPB is located farther away in the northern hemisphere instead of the southern hemisphere. The north-south asymmetry of the Martian MPB with the southern hemisphere being farther away is observed for other IMF directions. We suggest that the magnetic reconnection of the southward IMF with the crustal field that occurs at middle latitudes of the southern hemisphere results in different magnetic field topologies and the closer location of the MPB under these conditions. Our model results show a relatively good agreement with the previous empirical and theoretical models.

Based on the observations from the Super Dual Auroral Radar Network at the Zhongshan Station (−74.9 MLAT, 97.2 MLON) and GOES satellites X-ray sensor, we present the first statistical study of the dayside ionospheric short-wave fadeout (SWF) events on the Southern Hemispheric high latitude from the years 2010–2019 and provide a normal characteristic of SWF with onset of 6 minutes 54 s, blackout of 20 minutes 24 s, and recovery of 39 minutes 36 s, respectively. All the SWF events in this work are selected to be caused by extreme flares. The statistical analysis shows both short-type and long-type SWF onset phases. Onset/blackout phase duration of long events is highly correlated with flare duration (0.79, 0.60), the SWF is mainly driven by the flare radiation profile, and the soft X-ray flux rise rate is higher for short-onset events than for most long-onset events, which is the main reason for the difference between the two types of events. In addition, the effect of ionospheric sluggishness on long-onset events also needs to be considered. The relationship between each phase’s durations of long SWFs and the effective peak X-ray flux is not obvious. However, the correlation between the integrated effective X-ray flux and the onset/blackout phase duration of long events is significant.

Using a three-dimensional multispecies magnetohydrodynamic model, we study the effects of the orientation of the interplanetary magnetic field (IMF), solar wind dynamic pressure ( P d ), and the location of the intense crustal field, on the dayside magnetic reconnection between the solar wind and the Martian crustal field. Our main results are as follows: (1) Different IMF orientations result in different magnetic field configurations and reconnection conditions on the Martian dayside. When the intense crustal field is located on the dayside, the dayside magnetic reconnection tends to occur in the region with solar zenith angles (SZA) ≈45° in the southern hemisphere for the IMF with a southward component. When the IMF has a northward component, the magnetic field lines are piled up in the same place and the Martian magnetic pileup boundary (MPB) appears as a local bulged “mini-magnetopause”. Under the pure radial IMF, the magnetic reconnection is absent, which might be due to the presence of additional outward magnetic tension and kinetic effects. (2) Dayside reconnection can change the shape of the Martian MPB, while the bow shock is weakly affected. When the IMF has a southward component, the dayside magnetic reconnection happens and the MPB is located closer to Mars with a “cusp” shape. When the IMF has a northward component, the Martian MPB expands with a local bulged “mini-magnetopause”. For the pure radial IMF condition, the subsolar region of the MPB is located closer to Mars than that under other IMF directions. The influence of the IMF cone angles on the Martian bow shock is much less than that on the MPB, and the bow shock locations are very close to the model results of another author found in the literature. (3) With increasing P d , the size of the crustal field region decreases and the draped fields correspondingly move to lower altitudes where the IMF and crustal field have the same direction. When the IMF has a southward component and the magnetic reconnection occurs at SZA ≈ 45°, the reconnection site, the region of the closed topology of the crustal field, and the draped IMF, do not change much with increasing P d . We suggest that the multipolar crustal magnetic fields can protect the solar wind IMF from further reconnecting with the crustal field to a lower altitude when P d is enhanced.

A global MHD model is used to study the energy transfer from solar wind to magnetosphere through magnetopause under radial interplanetary magnetic fields (IMFs). We use the streamline method to determine the smooth surface of the magnetopause by searching the inner boundary of the solar-wind streamline and discuss the roles of magnetic reconnection and viscous interaction under radial IMFs, which we compare with cases of north–south IMFs. We find that (1) the energy transfer across the magnetopause is asymmetric between the northern and southern hemispheres due to different reconnection locations, particularly for electromagnetic energy; (2) for sunward IMF, the most significant area of the net input of mechanical energy occurs on the day side and near-Earth magnetotail, and the electromagnetic energy input in the northern hemisphere is much larger than in the southern hemisphere on the night side; (3) the mechanical and electromagnetic energy-transfer distribution in the northern (southern) hemisphere for earthward IMF is the same as that in the southern (northern) hemisphere for sunward IMF; (4) the electromagnetic energy input for radial IMF is two times larger than for northward IMF, but three times smaller than for southward IMF, the viscous effect is smaller than for northward IMF but comparable to that for southward IMF, the rate of energy transfer is 2.22% for radial IMF, which is lower than 4.95% for southward IMF, but higher than 1.7% for northward IMF; and (5) the Akasofu-type energy-coupling formula, ϵ , is not suitable for the solar-wind events dominated by IMF B x .

Using a 3D multispecies magnetohydrodynamic model, we investigated the effect of the solar wind dynamic pressure ( P d ) with different densities and velocities on the subsolar standoff distance ( r 0 ) of the Martian magnetic pileup boundary (MPB). We fixed the solar maximum condition, the strongest crustal field located in the dayside region, and the Parker spiral interplanetary magnetic field at Mars. We simulated 35 cases with a P d range of 0.1494 to 7.323 nPa (solar wind number density n ∈ [1, 9] cm −3 , and solar wind velocity V ∈ [−258, −1344] km s −1 ). The main results are as follows. (1) r 0 decreases with increasing P d according to the power-law relations. For the same P d , a higher solar wind velocity (lower density) results in a larger r 0 of the Martian MPB. (2) A higher solar wind density leads to a lower ratio of the compressed magnetic field strength to the crustal field strength and a larger plasma β under the same P d . This indicates that the thermal pressure at the Martian MPB plays a significant role for the compressed magnetic field. Because the magnetic pileup process is stronger for a higher solar wind velocity, the magnetic pressure at the Martian MPB is increased. As a result, the thermal pressure decreases and r 0 of the Martian MPB increases. (3) We present a new formula of r 0 with the parameters of the solar wind dynamic pressure, number density, and velocity.

The Venusian plasma environment is divided into two distinct regions by the induced magnetosphere boundary (IMB): the domain of solar wind protons and the domain of local planetary ions. Previous studies on the identification of the IMB gave various IMB definitions. Here we study the well-structured Venusian IMB with a sudden magnetic field rotation and a sharp magnetosheath plasma decrease using Venus Express observations. We statistically investigate the location of such well-structured IMB and give an average location of the IMB at solar maximum. The solar activity and solar wind controls of the Venusian IMB location is also studied in this work. Our results show that the dayside Venusian IMB distance increases with solar activity, but it decreases with increasing solar wind dynamic pressure and interplanetary magnetic field cone angle. The behaviors of the IMB under these conditions are similar to those of the ionopause, indicating that the distance of the Venusian IMB is much correlated with the scale of the ionosphere. We suggest that the variation of the IMB is partially contributed to by the variation of the ionopause, whose altitude is determined by the pressure balance between ionospheric thermal pressure and external magnetic pressure.