Siamese Meets Diffusion Network: SMDNet for Enhanced Change Detection in High-Resolution RS Imagery

Recently, the application of deep learning to change detection (CD) has significantly progressed in remote sensing images. In recent years, CD tasks have mostly used architectures such as CNN and Transformer to identify these changes. However, these architectures have shortcomings in representing boundary details and are prone to false alarms and missed detections under complex lighting and weather conditions. For that, we propose a new network, Siamese Meets Diffusion Network (SMDNet). This network combines the Siam-U2Net Feature Differential Encoder (SU-FDE) and the denoising diffusion implicit model to improve the accuracy of image edge change detection and enhance the model's robustness under environmental changes. First, we propose an innovative SU-FDE module that utilizes shared weight features to capture differences between time series images and identify similarities between features to enhance edge detail detection. Furthermore, we add an attention mechanism to identify key coarse features to improve the model's sensitivity and accuracy. Finally, the diffusion model of progressive sampling is used to fuse key coarse features, and the noise reduction ability of the diffusion model and the advantages of capturing the probability distribution of image data are used to enhance the adaptability of the model in different environments. Our method's combination of feature extraction and diffusion models demonstrates effectiveness in change detection in remote sensing images. The performance evaluation of SMDNet on LEVIR-CD, DSIFN-CD, and CDD datasets yields validated F1 scores of 90.99%, 88.40%, and 88.47%, respectively. This substantiates the advanced capabilities of our model in accurately identifying variations and intricate details.Comment: 12 pages, 4 figure

Oxidation Layer Formation on Aluminum Substrates with Surface Defects using Molecular Dynamics Simulation

Aluminum Oxide Layer Affects the Integrity of Electrical Contact and Can Contribute Adversely to Passive Intermodulation (PIM) Behavior in Radio Frequency (RF) Devices, necessitating a Need for Understanding its Formation Mechanism and Realistic Estimation of its Thickness. using ReaxFF Molecular Dynamics Simulation Technique, This Study Investigated the Impact of Surface Defects on Aluminum Oxide Layer Formation. Results Reveal that Crystallographic Orientation Did Not Affect the Kinetics of Oxidation Process of Aluminum. However, the Reaction Kinetics Increased Significantly with Surface Inhomogeneities Such as Cracks, Scratches, and Grain Boundaries. a Non-Uniform Oxide Layer with Thickness Variation in the Range of 72-77% Was Observed Due to Surface Imperfections. Concurrent Crack Healing and Oxidation Was Observed, Where the Crack Tips Acted as Sites for Oxygen Diffusion, Thus Increasing Oxidation Kinetics. the Observations from This Simulation Agree with Experimental Reports and Have Important Implications for Optimizing the Contact Integrity in RF Devices and for PIM Control

Static I-V based PIM Evaluation for Spring and Fabric-Over-Foam Contacts

Spring Clips and Fabric-Over-Foams (FOFs) Are Widely Used in Mobile Devices for Electrical Connection Purposes. However, the Imperfect Metallic Connections Tend to Induce Passive Intermodulation (PIM), Resulting in a Receiver Sensitivity Degradation, Known as RP Desensitization. Due to the Complexity of the PIM Characterization, there is Not Yet a Way to Evaluate PIM Performance using a Simple Setup for Environments Like Factories. in This Paper, a Current-Voltage (I-V) Behavior-Based PIM Evaluation Method is Proposed and Validated with Various Metallic Contacts and Contact Forces. the Test Results Demonstrated the Feasibility of the PIM Performance Evaluation based on the Measured Static I-V Curve

Practical Fixture Design for Passive Intermodulation Tests for Flexible Metallic Contacts

Passive intermodulation (PIM) commonly exists in non-ideal metallic contacts. Since PIM typically represents an extremely low level of nonlinearity, it has not drawn enough attention over the years except for extremely high-power applications such as base stations. However, in recent years, the study on PIM has become essential in universally used consumer electronics design because of the higher requirement on the radio frequency (RF) sensitivity of wireless communications. The metal contacts caused PIM can create the sideband spectrum to interfere with the receiving band in the frequency divide duplex (FDD) mode. Therefore, the study on PIM for the frequently used flexible metallic components is important in the industry. The PIM characterizations for the flexible components at least demand the compression variability and the capability to inject high-power signals while monitoring the sideband spectrum. It is preferred to have the access to measuring more relevant quantities. This paper aims to summarize the practical experience in designing a high-dynamic range and multi-purpose applicable test setup for characterizing PIM in the flexible components. Capabilities to precisely measure/control PIM, gap variability, tilted angle variability, and DC resistance (DCR) are presented with measurement examples

Passive Intermodulation under Different Spring Contact Conditions

Modularized designs have been widely used in today\u27s consumer electronic devices and flexible RF springs are used for electrical connections between the modules. In the meantime, aluminum alloy material becomes a common chassis option. It is well known that the oxidized chassis surface introduces a certain level of nonlinearity when contacted by the springs, as known as passive intermodulation (PIM). PIM is one of the well-known root causes of the RF desensitization (desense). This paper is focused on investigating the relationship between PIM and contact conditions of the springs, especially contact area. The PIM level behavior is explained mathematically by the regrowth rate and the RF power distributions on the contacts. Full-wave simulations and mechanical simulations were conducted to further support the hypothesis

Corticofugal Modulation of Initial Neural Processing of Sound Information from the Ipsilateral Ear in the Mouse

Background: Cortical neurons implement a high frequency-specific modulation of subcortical nuclei that includes the cochlear nucleus. Anatomical studies show that corticofugal fibers terminating in the auditory thalamus and midbrain are mostly ipsilateral. Differently, corticofugal fibers terminating in the cochlear nucleus are bilateral, which fits to the needs of binaural hearing that improves hearing quality. This leads to our hypothesis that corticofugal modulation of initial neural processing of sound information from the contralateral and ipsilateral ears could be equivalent or coordinated at the first sound processing level. Methodology/Principal Findings: With the focal electrical stimulation of the auditory cortex and single unit recording, this study examined corticofugal modulation of the ipsilateral cochlear nucleus. The same methods and procedures as described in our previous study of corticofugal modulation of contralateral cochlear nucleus were employed simply for comparison. We found that focal electrical stimulation of cortical neurons induced substantial changes in the response magnitude, response latency and receptive field of ipsilateral cochlear nucleus neurons. Cortical stimulation facilitated auditory response and shortened the response latency of physiologically matched neurons whereas it inhibited auditory response and lengthened the response latency of unmatched neurons. Finally, cortical stimulation shifted the best frequencies of cochlear neurons towards those of stimulated cortical neurons

MIMO Performance of Low Mutual Performance of Low Mutual Coupling Antennas in Indoor and Hallway Environments

In this thesis, the 2×2 MIMO performance of several low mutual coupling antennas has been investigated in indoor and hallway scenarios. Three compact antennas intended for mobile applications with low mutual coupling between the input ports are presented in this thesis. To gauge the performances of the three designed antennas, two reference antennas are also used. Channel capacity measurements were conducted in Bahen Center Antenna Lab room 8175 and the Bahen Center 8th floor hallway by using the five antennas as receivers. The antenna spatial location, orientation, line-of-sight and non-line-of-sight situation and richness of multipath effect were considered in the measurements. By averaging the results, it is found that in an indoor environment, low mutual coupling antennas can outperform the reference high mutual coupling antennas especially in higher SNR scenarios. In the hallway environment, low mutual coupling antennas always outperform the reference high mutual coupling antennas due to pattern diversity.MAS

Metamaterial Devices for Wavefront Manipulation from Microwave to Optical Frequencies

This thesis presents highly efficient metamaterial devices for wavefront manipulation from microwave to optical frequencies. In this framework, compact and efficient quarter-wave and half-wave plates for long-wave infrared applications are designed based on elliptical antenna array sheets. Half-wave plate unit cells are used in conjunction with the Pancharatnam-Berry (PB) phase principle for efficient refraction, focusing and polarization discrimination. To avoid high losses introduced by metal in the near-infrared regime, an all-dielectric metalens is proposed. The metalenses comprises an array of tapered nano-holes etched into the indium phosphide (InP) substrate. This tapering of the nano-holes acts as a graded-index matching layer, resulting in metalenses with near-unity transmission from 0.9 μm to 1.7 μm. Furthermore, the hole array concept is adapted to designing a grade-index (GRIN) lens at millimeter-wave frequencies. GRIN matching layers are proposed to match the GRIN lens. The optimal permittivity in the GRIN matching layers is calculated through the transfer-matrix method. The resulting matched GRIN lens has very high radiation efficiency. In this thesis, anti-reflection or impedance matching with anisotropic metamaterials is also investigated. With specific material tensors, an anisotropic matching layer can be used to match an arbitrary substrate to free space at an arbitrary incident angle. Realistic metamaterial structures are proposed at microwaves to achieve the required material parameter tensors and perfect matching is demonstrated for either TE or TM polarization at a near grazing angle of 88 degrees. To match TE and TM polarizations simultaneously, a magneto-electric uniaxial matching layer (MEUML) is proposed and matching is demonstrated at 45 degrees. The MEUML is applied to a sandwich radome design at X-band and the resulting radome has an exceptional angular performance. Lastly, a single-layer metamaterial radome is designed at 34.3 GHz. Two coupled metasurfaces are patterned on a regular dielectric substrate to transform it into a homogenized metamaterial slab. By tuning the metasurfaces and their coupling, the metamaterial slab exhibits equal effective permittivity and permeability. The resulting structure is impedance matched to free space. The single-layer metamaterial radome is polarization-insensitive, low loss, broadband, and easy to fabricate, making it attractive for many millimeter-wave applications.Ph.D