More recently, smart agriculture has received widespread attention, which is a deep combination of modern agriculture and the Internet of Things (IoT) technology. To achieve the aim of scientific ...cultivation and precise control, the agricultural environments are monitored in real time by using various types of sensors. As a result, smart agricultural IoT generated a large amount of multidimensional time series data. However, due to the limitation of applied scenarios, smart agricultural IoT often suffers from data loss and misrepresentation. Moreover, some intelligent decision-makings for agricultural management also require the detailed analysis of data. To address the above problems, this article proposes a new anomaly detection model based on generative adversarial networks (GAN), which can process the multidimensional time series data generated by smart agricultural IoT. GAN is a deep learning model to learn the distribution patterns of normal data and capture the temporal dependence of time series and the potential correlations between features through learning. For the problem of generator inversion, an encoder–decoder structure incorporating the attention mechanism is designed to improve the performance of the model in learning normal data. In addition, we also present a new reconstruction error calculation method that measures the error in terms of both point-wise difference and curve similarity to improve the detection effect. Finally, based on three smart agriculture-related datasets, experimental results show that our proposed model can accurately achieve anomaly detection. The experimental precision, recall, and F1 score exceeded the counterpart models by reaching 0.9351, 0.9625, and 0.9482, respectively.
In some emerging wireless applications, such as wearable communication and low-power sensor network applications, wireless devices or nodes not only require simple physical implementation approaches ...but also require certain reliable receiver techniques to overcome the effects of multipath or shadowed fading. Switched diversity combining (SDC) systems could be a simple and promising solution to the above requirements. Recently, a Fisher-Snedecor ℱ composited fading model has gained much interest because of its modeling accuracy and calculation tractability. However, the performance of SDC systems over ℱ fading channels has not yet been analyzed in the open literature. To this end, this paper presents a systematic analysis of SDC systems over ℱ fading channels, including dual-branch switch-and-stay combining (SSC), multibranch switch-and examine combining (SEC), and SEC with post-examining selection (SECps) systems. We first investigate the statistical characteristics of univariate and bivariate ℱ distributions. Then, these statistical expressions are introduced into the above SDC systems and the statistical metrics of the output signal-to-noise ratio (SNR) for these systems are deduced in different ℱ fading scenarios. Thirdly, certain exact and novel expressions of performance criteria, such as the outage probability, the average bit error probability and average symbol error probability, as well as the average channel capacity for SSC, SEC, and SECps are derived. To find the optimum performance, optimal analysis is performed for the independent and identically distributed cases. Finally, numerical evaluation and simulations are carried out to demonstrate the validity of the theoretical analysis under various ℱ fading scenarios. According to the obtained results, the multipath fading parameter has more influence on the performance of SDC systems than the shadowing parameter, the correlation coefficient, or the average SNR. Importantly, the SDC systems can provide switched diversity gains only when the switching threshold is not too large or too small compared to the average SNR.
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Abstract
Power dissipation is a fundamental issue for future chip-based electronics. As promising channel materials, two-dimensional semiconductors show excellent capabilities of scaling dimensions ...and reducing off-state currents. However, field-effect transistors based on two-dimensional materials are still confronted with the fundamental thermionic limitation of the subthreshold swing of 60 mV decade
−1
at room temperature. Here, we present an atomic threshold-switching field-effect transistor constructed by integrating a metal filamentary threshold switch with a two-dimensional MoS
2
channel, and obtain abrupt steepness in the turn-on characteristics and 4.5 mV decade
−1
subthreshold swing (over five decades). This is achieved by using the negative differential resistance effect from the threshold switch to induce an internal voltage amplification across the MoS
2
channel. Notably, in such devices, the simultaneous achievement of efficient electrostatics, very small sub-thermionic subthreshold swings, and ultralow leakage currents, would be highly desirable for next-generation energy-efficient integrated circuits and ultralow-power applications.
Carbon nanotubes (CNTs) are promising candidates for smart electronic devices. However, it is challenging to mediate their bandgap or chirality from a vapor-liquid-solid growth process. Here, we ...demonstrate rate-selected semiconducting CNT arrays based on interlocking between the atomic assembly rate and bandgap of CNTs. Rate analysis confirms the Schulz-Flory distribution which leads to various decay rates as length increases in metallic and semiconducting CNTs. Quantitatively, a nearly ten-fold faster decay rate of metallic CNTs leads to a spontaneous purification of the predicted 99.9999% semiconducting CNTs at a length of 154 mm, and the longest CNT can be 650 mm through an optimized reactor. Transistors fabricated on them deliver a high current of 14 μA μm
with on/off ratio around 10
and mobility over 4000 cm
V
s
. Our rate-selected strategy offers more freedom to control the CNT purity in-situ and offers a robust methodology to synthesize perfectly assembled nanotubes over a long scale.
Recently, a Fisher-Snedecor F composite fading model has gained great attention due to its mathematical tractability and modeling accuracy. However, its bivariate statistical characteristics have not ...been considered yet in the previous technical literature. In this paper, we present a bivariate Fisher-Snedecor F distribution with identical shaping parameters and study its applications in the wireless communication systems. We first derive novel theoretical formulations of the statistical characteristics for the bivariate Fisher-Snedecor F distribution model, which include the joint probability density function (PDF), the joint cumulative distribution function (CDF), the joint moment generating function (MGF) and the joint moments. Then, capitalizing on the above statistical expressions, some exact and asymptotic expressions of performance criteria, such as the outage probability, the average bit/symbol error probability (ABEP/ASEP), and the average channel capacity, for dual-branch selection combing and maximal ratio combing diversity systems are derived, respectively. Especially, the exact expressions of the ABEP/ASEP for several classical modulation schemes are obtained in terms of the multivariate Fox's H-function by applying the Mellin-Barnes type contour integral. Furthermore, we investigate the second-order statistics of a sampled Fisher-Snedecor F composited fading envelope by utilizing the joint CDF, and obtain the mathematical expressions of the level crossing rate (LCR) and the average fade duration (AFD). Finally, we employ numerical and simulation results to demonstrate the validity of the theoretical analysis under various correlated fading and shadowing scenarios.
With the development of 5G technology, Mobile Edge Computing (MEC) has become a promising technology that is widely used in the Industrial Internet of Things (IIoT) and other fields. However, the ...increase in terminal devices and massive data growth has brought new challenges to MEC systems. How to meet the latency requirements of mobile devices while reducing system costs as much as possible is an urgent problem to be solved. To address this problem, we construct a smart factory model and formulate a mixed-integer nonlinear programming problem with the goal of minimizing the weighted sum of task delay and energy consumption. Considering that this problem is non-deterministic polynomial hard (NP-hard), we choose the Deep Q-network (DQN) approach to solve the objective function. In order to avoid the inaccurate Q-value estimation problem of the Double DQN algorithm and the overestimation problem of the Dueling DQN algorithm, we combine them to propose a Double-Dueling DQN (D3QN) algorithm. The simulation results show that the D3QN algorithm significantly outperforms the DQN, the Double DQN, and the Dueling DQN algorithm in reducing the total system cost.
How to model shadow fading by applying the inverse gamma (IGA) distribution has recently gained widespread attention in wireless transmissions. However, the sum of α-μ/IGA variates, and its ...applications under independent and/or correlated scenarios, have yet to be addressed in open research works. Hence, this paper provides a systematic investigation of the α-μ/IGA model. First, we derive the expressions of the fundamental statistics of the univariate and bivariate α-μ/IGA models including the probability density function, cumulative distribution function, and moment generating function, and propose a mixture α-μ model to approximate the α-μ/IGA model. Then, according to the above statistical expressions, the statistical properties of the sum of α-μ/IGA variates are obtained and employed in the maximal ratio combining receivers. Third, the novel exact and approximated expressions of some performance metrics of interest are also derived, for instance, the average bit/symbol error probability, the outage probability, the average channel capacity, and the effective rate. Moreover, to prove the asymptotic properties of the performance metrics at the high signal-to-noise regions, some examples are performed. Finally, we explore numerical analysis and simulations to demonstrate the accuracy of the theoretical expressions under the different channel and system parameters. These results provide some significant insights into the reliability design and deployment of some conventional and emerging wireless communication applications.
ISAR Image Registration Based on Line Features Wu, Linhua; Zhao, Lizhi; Wang, Junling ...
Journal of Electromagnetic Engineering and Science,
05/2024, Volume:
24, Issue:
3
Journal Article
Peer reviewed
Open access
Inverse synthetic aperture radar (ISAR) image registration enables the analysis of target dynamics by comparing registered images from different viewpoints. However, it faces significant challenges ...due to various factors, such as the complex scattering characteristics of the target, limited availability of information, and additive noise in ISAR images. This paper proposes a novel ISAR image registration method based on line features. It integrates information from both dominant scatterers and the target’s outer contour to detect lines. According to the consistency principles of multiple lines in rotation and translation, line features from different ISAR images are matched. Simultaneously, the results of the feature matching are utilized to guide the parameter configuration for optimizing the image registration process. Comparative experiments illustrate the advantages of the proposed method in both feature extraction and registration feasibility.
In this paper, an N-type silicon line tunneling TFET (LT-TFET) with an ultra-shallow N + pocket was proposed. The pocket was formed by using the germanium preamorphization implantation (Ge PAI), ...arsenic ultra-low energy implantation and spike annealing. Due to the Ge PAI, the tunneling probability was improved significantly. As a result, a high on-state current of <inline-formula> <tex-math notation="LaTeX">40 \mu \text{A}/\mu \text{m} </tex-math></inline-formula>, a minimum subthreshold swing (SS) of 69 mV/decade and an average SS of 80 mV/decade over 5 decades of drain current were achieved with <inline-formula> <tex-math notation="LaTeX">\text{V}_{\mathrm{ DS}} =\,\,\text{V}_{\mathrm{ GS}}=1 </tex-math></inline-formula> V at room temperature. It is shown that once the trap assisted tunneling is suppressedat the low temperature, the band-to-band tunneling becomes dominant. When the temperature decreases from 300 K to 4.9 K, the on-state current only reduces 20% and a minimumpoint SS of 10 mV/decadewas obtained. The LT-TFET exhibits improved transconductance efficiency at deep cryogenic temperature range. The proposed structure in this work shows attractive merits in the cryogenic digital and analog application.
We investigated a simple Adaptive selection/maximal-ratio（ASM） combining cooperative system with output threshold over independent nonidentical composite Nakagami-lognormal fading channels using ...Mixture gamma（MG） distribution. Some novel closed-form expressions for the probability density function, the cumulative distribution function and the momentgeneration function of the output Signal-to-noise ratio（SNR） for the ASM system are derived, respectively. The average symbol error rate, outage probability and the diversity order for the ASM system are given based on the above expressions. For the purpose of comparison, we also derive the statistical characterizations of the conventional selection combining and maximal-ratio combining cooperative systems using MG distribution. Numerical and simulation results are shown to verify the accuracy of the analytical results under different scenarios, such as varying average SNR, fading parameters per hop, and the location of relaying nodes. These results show that ASM is a simple and flexible cooperative system, and can be useful in future practical deployment.
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