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It is a formidable challenge to find the minority carrier recombination lifetime in low-dimensional devices as low-dimensionality increases the surface recombination rate and often reduces the recombination lifetime to a scale of picoseconds. In this work, we demonstrated a simple but powerful method to quantitatively probe the minority carrier recombination lifetime in silicon nanowires or microwires by fitting the experimental photoresponses with our recently established analytical photoresponse principle of photoconductors. The nanowires were passivated with small molecules and Al2O3 to suppress surface recombination, which will increase the minority recombination lifetimes. As expected, the minority carrier recombination lifetime found by this approach increases by orders of magnitude. These wires were also made into PIN diodes, the leakage of which was reduced at least 1 order of magnitude after surface passivation by Al2O3. The minority recombination lifetime found from the leakage current of these devices is largely consistent with what we found from our analytical photoresponse principle. As a further step, we performed scanning photocurrent microscopy to find the minority diffusion length from which we found that the minority recombination lifetime is close to what we found from the analytical photoresponses. In short, this work validated that our analytical response principle is a reliable method to find the minority recombination lifetime in low-dimensional semiconductors. [ABSTRACT FROM AUTHOR]

Building segmentation has extensive research value and application prospects in high-resolution remote sensing image (HRSI) processing. However, complex architectural contexts, varied building morphologies, and non-building occlusions make building segmentation challenging. Compared with traditional methods, deep learning-based methods present certain advantages in terms of accuracy and intelligence. At present, the most popular option is to first apply a single neural network to encode an HRSI, then perform a decoding process through up-sampling or using a transposed convolution operation, and then finally obtain the segmented building image with the help of a loss function. Although effective, this approach not only tends to lead to a loss of detail information, but also fails to fully utilize the contextual features. As an alternative, we propose a novel network called NPSFF-Net. First, using an improved pseudo-Siamese network composed of ResNet-34 and ResNet-50, two sets of deep semantic features of buildings are extracted with the support of transfer learning, and four encoded features at different scales are obtained after fusion. Then, information from the deepest encoded feature is enriched using a feature enhancement module, and the resolutions are recovered via the operations of skip connections and transposed convolutions. Finally, the discriminative features of buildings are obtained using the designed feature fusion algorithm, and the optimal segmentation model is obtained by fitting a cross-entropy loss function. Our method obtained intersection-over-union values of 89.45% for the Aerial Imagery Dataset, 71.88% for the Massachusetts Buildings Dataset, and 68.72% for the Satellite Dataset I. [ABSTRACT FROM AUTHOR]

Plasmonic spectral filters composed of periodic nanostructured metal films offer novel opportunities for the development of multispectral imaging technologies in the mid-infrared region. However, traditional plasmonic filters, which typically feature simplistic structures such as nanoholes or nanorings, are constrained by a narrow bandpass and significant crosstalk, leading to limited practical performance. Filters designed using inverse techniques allow a substantial degree of freedom in creating intricate structures that align with desired spectral characteristics, including a quasi-square spectral profile, high transmission, wide full width at half maximum, and reduced crosstalk. In this study, we have utilized an inverse design algorithm to engineer high-performance bandpass filters for the mid-infrared range, achieving an average transmittance exceeding 80% within the bandpass window and below 10% in the stop band, which is comparable to that of commercial multilayer Bragg filters. Nanofabrication processes were employed to transfer the designed pattern into the gold film on ZnS substrate that is transparent in the mid-infrared range. The resulting filters exhibit spectral performance analogous to that of the inversely designed models, making them suitable for direct integration with mid-infrared photodetector arrays in multispectral imaging systems. [ABSTRACT FROM AUTHOR]

Detecting changes in multisource heterogeneous images is a great challenge for unsupervised change detection methods. Image-translation-based methods, which transform two images to be homogeneous for comparison, have become a mainstream approach. However, most of them primarily rely on information from unchanged regions, resulting in networks that cannot fully capture the connection between two heterogeneous representations. Moreover, the lack of a priori information and sufficient training data makes the training vulnerable to the interference of changed pixels. In this paper, we propose an edge-oriented generative adversarial network (EO-GAN) for change detection that indirectly translates images using edge information, which serves as a core and stable link between heterogeneous representations. The EO-GAN is composed of an edge extraction network and a reconstructive network. During the training process, we ensure that the edges extracted from heterogeneous images are as similar as possible through supplemented data based on superpixel segmentation. Experimental results on both heterogeneous and homogeneous datasets demonstrate the effectiveness of our proposed method. [ABSTRACT FROM AUTHOR]

Optical remote sensing videos, as a new source of remote sensing data that has emerged in recent years, have significant potential in remote sensing applications, especially national defense. In this paper, a tracking pipeline named TDNet (tracking while detecting based on a neural network) is proposed for optical remote sensing videos based on a correlation filter and deep neural networks. The pipeline is used to simultaneously track ships and planes in videos. There are many target tracking methods for general video data, but they suffer some difficulties in remote sensing videos with low resolution and those influenced by weather conditions. The tracked targets are usually misty. Therefore, in TDNet, we propose a new multi-target tracking method called MT-KCF and a detecting-assisted tracking (i.e., DAT) module to improve tracking accuracy and precision. Meanwhile, we also design a new target recognition (i.e., NTR) module to recognise newly emerged targets. In order to verify the performance of TDNet, we compare our method with several state-of-the-art tracking methods on optical video remote sensing data sets acquired from the Jilin No. 1 satellite. The experimental results demonstrate the effectiveness and the state-of-the-art performance of the proposed method. The proposed method can achieve more than 90% performance in terms of precision for single-target tracking tasks and more than 85% performance in terms of MOTA for multi-object tracking tasks. [ABSTRACT FROM AUTHOR]

Impact craters are the most significant topographic features on the lunar surface. They are also essential factors affecting the construction of lunar bases and activities on the lunar surface in the future. Nevertheless, it is difficult to extract the impact craters by image processing methods due to the influence of illumination in the lunar polar region. Furthermore, the digital elevation model (DEM) is unable to extract small impact craters. Therefore, we propose an extraction framework for small craters, namely AE-TransUNet+, for the future lunar South Pole region of interest. The algorithm is applied to grayscale images (0.5 m/pixel) captured by the Lunar Reconnaissance Orbital (LRO) narrow-angle camera (NAC). To improve the channel extract and spatial relationship between features, the convolutional block attention modules (CBAMs) and depthwise-separable convolution (DSC) are added to the core TransUNet model, and the redesigned jump connection enhancement module focuses more on small impact crater features. Experiments on the NAC dataset show that AE-TransUNet+ has a higher F1-Score (0.743) and IOU (0.847) compared to other crater detection models. Besides, based on transfer learning, the visualization results of Mars and Mercury show that the proposed method is more efficient in the processing of remote sensing data for different deep space explorations providing better mobility. [ABSTRACT FROM AUTHOR]

As the world has become increasingly digitalized in recent years, high-dimensional data with geographical location coordinate attributes, mainly referring to latitude and longitude, have been accumulated and spread to many disciplines. It is challenging to analyze such data. The map-in-parallel-coordinates plot (MPCP) is an incorporate visual analysis method that can express, filter, and highlight high-dimensional geographical data to facilitate data exploration and comprehension. In this paper, the MPCP underwent a series of field trial studies to verify its applicability, adaptability, and high efficacy in the real-world. The results of the evaluation were positive, which provides reasonable proof and new insights into the benefits of using MPCP to visually analyze high-dimensional geographical datasets. [ABSTRACT FROM AUTHOR]

Co-substituted U-type hexagonal ferrite bulks, with composition of Ba4Ni2−xCoxFe36O60 (x=0.2, 0.4, 0.6, 0.8), were prepared by a conventional ceramic method. Saturation magnetization (4πMs), coercivity (Hc), and Curie temperature (Tc) were investigated. Anisotropy constant (K1) was calculated by fitting the magnetization curve (M-H) according to the law of approach to saturation, and anisotropy field (Ha) was calculated accordingly. The results reveal that all the samples possess the U-type hexagonal crystallographic structure. With increasing cobalt substitution content (x), the lattice parameters (a and c) almost remain the same owing to the similar radii of Ni2+ (0.72 Å) Co2+ (0.74 Å) ions. 4πMs goes up, while HcHc shows an opposite trend. K1 and Ha monotonously decrease resulting from that cobalt substitution weakens the c-axis orientation. Additionally, Tc increases from 467 °C to 484 °C. [ABSTRACT FROM AUTHOR]

Mg1–xCuxFe2O4 ferrites for electromagnetic interference suppression were systematically investigated in crystallographic structure, morphologies, and magnetic and dielectric spectra over a frequency range of 10–1000 MHz. Findings indicated that the Mg1–xCuxFe2O4 ferrites with $x$ = 0–0.6 showed a single-phase cubic spinel structure, but the sample structure with $x = 0.8$ transforms into a tetragonal phase. Moreover, the substitution of Cu was shown to lower the sintering temperature and enhance densification of the ferrites, resulting in increased saturation magnetization (67%) and decreased coercivity (88%). More importantly, the complex permeability and permittivity of Mg–Cu ferrites could be tailored with Cu content, leading to an enhanced magnetic loss and permeability. The magnetic loss tangent of the Mg0.4Cu0.6Fe2O4 ferrite sintered at 1150 °C was significantly increased by 56% at $f>300$ MHz. [ABSTRACT FROM AUTHOR]

Thick barium hexaferrite Ba2Zn2Fe12O22 (i.e., Zn2Y) films having thicknesses of μ100 μm were epitaxially grown on MgO (111) substrates using an environmentally benign ferrite-salt mixture by vaporizing the salt. X-ray diffraction pole figure analyses showed (00l) crystallographic alignment with little in plane dispersion confirming epitaxial growth. Saturation magnetization, 4πMs, was measured for as-grown films to be 2.51±0.1 kG with an out of plane magnetic anisotropy field HA of 8.9±0.1 kOe. Ferromagnetic resonance linewidth, as the peak-to-peak power absorption derivative at 9.6 GHz, was measured to be 62 Oe. These properties demonstrate a rapid, convenient, cost-effective, and nontoxic method of growing high quality thick crystalline ferrite films which could be used widely for microwave device applications. [ABSTRACT FROM AUTHOR]

The fabrication and high-frequency ferromagnetic performances of (Fe50Co50)1-x(Al2O3)x soft magnetic films (SMFs) were investigated. It is revealed that the modified composition gradient sputtering method dramatically improves the high-frequency soft magnetic properties of the as-prepared films. This method gives rise to a linearly increased distribution of compositions and residual stress. As a result, comparing with the samples prepared by conventional composition gradient sputtering (CGS) method, a very high and uniform ferromagnetic resonance frequency in excess of 5 GHz, high uniaxial magnetic anisotropic field, and low magnetic loss were obtained, which are particularly in favor of the integration between magnetic films and radio-frequency (RF) components. [ABSTRACT FROM AUTHOR]

We report the magnetic and structural properties of a series of W-type barium hexaferrites of composition BaZn2-xCoxFe16O27, where x = 0.15, 0.20, and 0.25. The anisotropy field of these barium ferrites (BaW) decreased with the substitution of divalent Co ions, while they maintained crystallographic c-axis texture. The measured anisotropy field was ∼10 kOe, and a hysteresis loop squareness Mr/Ms = 79% was obtained due to well-controlled grain size within the range of single domain scale. These two properties make the BaW suitable for applications in microwave devices at lower frequencies, such as self-biased circulators operated at X-band frequencies. [ABSTRACT FROM AUTHOR]

The high frequency magnetic spectra of Sr 2+ or Sr 2+ -Gd 3+ doped Co 2 Z hexaferrites were systematically investigated. Of particular interest is the high impedance modulus measured in such dual-ion modified Z-type polycrystalline hexaferrites that have considerable potential for applications as anti -electromagnetic interference (EMI) over a frequency range of 0.5–5 GHz. The experiments indicate that the combination of Sr 3+ and Gd 3+ cations effectively tailors the anisotropy field while concomitantly increasing magnetization, yielding an increase in both real and imaginary components of the complex permeability. Consequently, this results in an enhanced impedance modulus as high as 384 Ω at 2 GHz. The structure and magnetic properties of the hexaferrite materials were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), vibrating sample magnetometry (VSM), and S-parameter measurements using a vector network analyzer (VNA). Furthermore, the physical origins of the improved high frequency performance are discussed. The present results provide a pathway to the development of anti -EMI hexaferrites operating in the GHz range. [ABSTRACT FROM AUTHOR]

A nanoscale-driven crystal growth of magnetic hexaferrites was successfully demonstrated at low growth temperatures (25-40% lower than the temperatures required often for crystal growth). This outcome exhibits thermodynamic processes of crystal growth, allowing ease in fabrication of advanced multifunctional materials. Most importantly, the crystal growth technique is considered theoretically and experimentally to be universal and suitable for the growth of a wide range of diverse crystals. In the present experiment, the conical spin structure of Co2Y ferrite crystals was found to give rise to an intrinsic magnetoelectric effect. Our experiment reveals a remarkable increase in the conical phase transition temperature by ∼150 K for Co2Y ferrite, compared to 5-10 K of Zn2Y ferrites recently reported. The high quality Co2Y ferrite crystals, having low microwave loss and magnetoelectricity, were successfully grown on a wide bandgap semiconductor GaN. The demonstration of the nanostructure materials-based "system on a wafer" architecture is a critical milestone to next generation microwave integrated systems. It is also practical that future microwave integrated systems and their magnetic performances could be tuned by an electric field because of the magnetoelectricity of hexaferrites.