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In this brief we optimally solve the problem of multiplierless design of wideband channelizers with sharp transition bandwidth (STB). We adopt frequency response masking (FRM) approach to design optimally the prototype filter and propose a low complexity FRM-based architecture for wideband channelizer with STB, which is suitable for wideband channelizers with high sampling rate. The optimal multiplierless design is further used for the FRM filters and discrete fourier transform (DFT) modules. The improved dynamic kernel function DFT with variable truncation is adopted to reduce the number of adders in multiplierless implementation. The hardware implementation of the optimal multiplierless FRM-based architecture for wideband channelizer with STB is presented. The experimental results show that the optimal multiplierless FRM-based architecture offers respectively 80.88% reduction and 20.97% reduction in chip power than polyphase and FRM architectures.

In this brief, we propose a sub-Nyquist frequency estimation method, which aims to increase the instantaneous bandwidth of discrete Fourier transform (DFT) based digital wideband receiver and estimate the frequencies without ambiguity. The proposed method consists of two parallel coprime sub-Nyquist sampling channels. We firstly address the frequency estimation based on the outputs of DFT, and the no-overlapping frequency components (FCs) can be estimated without grid. To obtain gridless estimation, the overlapping FCs are then reformulated as an finite rate of innovation problem with lower rate of innovation, larger sampling interval and higher signal-to-noise rate after removing the no-overlapping FCs via partial channel reconstruction, and are estimated with smaller errors by the sparse samples. Numerical simulations demonstrate that the proposed method is effective and noise robust.

In order to suppress the sending end transient overvoltage caused by HVDC commutation failure considering large wind power integration, this paper proposes a coordinated optimization method for the control parameters of DC and wind power, which can suppress the sending end transient overvoltage and ensure the performance of the DC control system. By analyzing the mechanism of DC and wind power control parameters affecting the sending end transient overvoltage, and studying the influence of control parameters on the performance of the DC control system, a multi-objective and multi-equipment coordination optimization model of the HVDC transmission system considering large wind power integration is constructed. The multi-objective adaptive differential evolution algorithm is used to realize the coordinated optimization of DC and wind power control parameters based on PSCAD simulation joint invocation. Finally, through simulation and optimization in different cases, it is found that the multi-objective parameter optimization has more obvious advantages than single-objective optimization in the case of weak receiving end power grid. In addition, it is concluded that the same control parameters can be used in different wind power penetration scenarios to achieve the purpose of suppressing transient overvoltage, which verifies the effectiveness and accuracy of the method proposed in this paper.

The onsite surveillance plays an important role in the smart substation since the smart substation is unattended. All the sites and operation staff should be supervised throughout the process since a series of risks exist on the working sites. KCF (Kernel Correlation Filter) is an effective method to track a moving object for safety surveillance. However, the occlusion and shape changes worsen the performance of KCF, especially on the occasion of multi-objective detection. This paper proposes a comprehensive method for improving the precision and robustness of detection. Firstly, all the moving objects are detected by the YOLO method. In the tracking part, an AKCF (Augmented Kernel Correlation Filter) is proposed for the heavily occluded object, and the Kalman Filter (KF) serves as a supplementary output. Moreover, in the target association section, based on priority matching and rematching based on motion estimation, a two-stage target association method is proposed. Test outcomes indicate that the proposed algorithm is accurate and robust for tracking workers’ trajectories and conducting surveillance.

In this paper, we propose a method to design generalized frequency response masking (FRM)-based P-L band multi-channel channelizers for array signal processing system (ASPS), which have sharp transition bandwidth (STB) and low complexity. The order of the prototype filter with STB designed by FRM method is smaller than that of the direct filter design method. The design approach of the proposed generalized FRM-based multi-channel channelizers is presented which solves the problem of high computational complexity of digital channelizer with STB. The proposed generalized FRM-based digital channelizer, which have the characteristics of unification and flexible configuration, is suitable for real signal, complex signal, odd-stacked, even-stacked, maximally decimation and non-maximally decimation structures. The generalized FRM-based P-L band multi-channel channelizers for ASPS is implemented in a Xilinx Kintex UltraScale XCKU115 processor. Experimental results show that the proposed generalized FRM-based digital channelizer offers 84.57% and 76.24% reduction in multipliers complexity and chip power respectively, which is less than conventional polyphase digital channelizer (PDC).

In this brief, we propose a design method of frequency response masking (FRM)-based filter bank for reconnaissance and jamming integrated architecture (RJIA) to solve the problems of low sensitivity and inability to process simultaneous arrival signals of conventional RJIA. The perfect reconstruction filter bank (PRFB) is adopted to increase sensitivity and provide the ability to process simultaneous arrival signals and jam multiple signals. The FRM approach is used to reduce the complexity of the RJIA to ensure the realizability on single field programmable gate array (FPGA). The design and FPGA implementation are presented, and experimental results show that the proposed FRM-based filter band for RJIA offers 60.63% reduction in multipliers complexity and 38.14% reductions in chip power than PRFB, which has advantages of high sensitivity and ability of multiple signals reconnaissance and jamming.

Electronic countermeasures are developing towards intelligence. The multifunctional radar changes its working state in real time according to the task requirements. The traditional jamming decision-making method can not quickly adjust the jamming mode according to the jamming effect and environmental changes. It is not suitable for complex and changeable multifunctional radar. For this problem, a cognitive jamming decision-making system based on reinforcement learning is designed. For the evaluation of jamming effect, an evaluation method based on Improved Sparrow Search Algorithm-Support Vector Machine (ISSA-SVM) is proposed, which can evaluate the jamming effect online. The results are fed back to the jammer to provide basis for jamming decision-making. For the jamming decision-making process, the interference experience table is combined with Heuristic Accelerated Q-Learning (HAQL). A jamming decision-making method based on adaptive HAQL algorithm is proposed, which adaptively adjusts the jamming mode and jamming power according to the change of radar threat level. A one-to-one interference scenario is established and simulated. The results show that the system can realize the closed-loop cognitive interference of learning and confrontation.

Due to limited hardware resources, multi-channel digital channelizers often use a 50% overlapping wide transition bandwidth in array signal processing. In this brief, we proposed an oversampled modulated filter bank (OMFB) with sharp transition bandwidth (STB) based on frequency response masking (FRM). The FRM approach is used to design and optimize the prototype filter with STB. The design process and fast implementation based on Xilinx System Generator of the proposed FRM-based OMFB with STB is presented. The proposed FRM-based OMFB with STB has the advantages of low complexity, which is suitable for high sampling rate system. Compared with conventional polyphase filter bank for digital channelizer, the proposed FRM-based OMFB with STB can offer 81.14% reduction in multipliers complexity.

The trend prediction of dissolved gas concentration in transformer oil can provide basis for transformer fault diagnosis, which is of vital significance to the safe operation of power system. However, due to the inevitable malfunction of monitoring equipment, it is difficult to collect all needed data in actual operation scenarios. Therefore, a method for predicting dissolved gas concentration in transformer oil for data loss scenarios is proposed based on Bayesian probabilistic matrix factorization (BPMF) and gated recurrent unit (GRU) neural network. Firstly, aiming at the problem of data loss in actual monitoring of dissolved gas in oil, BPMF is used to fill in the missing data. Then, a GRU neural network model is established to predict the trend of dissolved gas concentration in oil. Finally, the hyperparameters of the prediction model are selected and optimized by Bayesian theory. The examples show that this method can effectively fill in the missing part of the measured data. Compared with traditional prediction methods, the proposed method has higher prediction accuracy.

Gridless compressed sensing technology mainly relies on multi-coset sampling method. Considering the difficulties it faces in practice, we propose an improved multi-coset sampling method based on modulated wideband converter and channelization, which first preserves the phase information between sampling channels through channel delay. The delayed signals can be sampled at low speed after being multiplied by the periodic signal and subjected to low-pass filtering. After digital channelization, unambiguous frequency estimation can be achieved when conditions are met. The proposed method significantly improves the time interval between sampling channels and the array aperture based on channelization, which is beneficial for estimation accuracy and clock synchronization between sampling channels. And the numerical simulations demonstrate the effectiveness of the parameter estimation and hardware implementation, as well as the noise robustness.

Based on the fluid mechanics and electromagnetic theory, a numerical simulation model of droplet transfer during local dry underwater MIG welding (LDU-MIG) of SUS304 was established by using fluid dynamics software FLUENT. The effects of gas pressure, wire feeding speed (WFS) and pulse peak current on the whole droplet transfer process in LDU-MIG were simulated and investigated. The simulation results indicated that the increase of gas pressure reduced the plasma flow force and enlarged the pressure gradient in the local dry cavity, which hindered the droplet transfer process and led to the larger droplet diameters and longer transfer periods. The increase of WFS decreased transfer period in lower current, but it changed the droplet transfer modes in larger current. With the increase of pulse peak current, the droplet transfer modes changed from globular transfer (200 A) to projected transfer with one pulse one droplet (280 A), then to streaming transfer with one pulse multiple droplets (360 A). Finally, the droplet transfer process was captured by high-speed photography technology in LDU-MIG welding experiments, the simulation results were in good agreement with the experimental results, which provided theory guidance and data supports for manufacturing and remanufacturing of underwater structure.

A superabsorbent polymer (SAP) was synthesized by solution polymerization. The influence of synthesis technology was studied and optimized, and FTIR, SEM, and TGA were used to characterize the structure and morphology of the material. Under the optimal synthesis conditions, the water absorption of the material can achieve about 80% of the saturation value in the first 20 min, and the material absorbs distilled water up to 2013 g/g. The SAP also has remarkable water retention and reswelling capability. The excellent performance makes it have a promising application in agriculture. In addition, the results show that the dosage of the reaction medium is a major factor for performance. Under the condition of the optimum value of other factors, the influence of the dosage of the reaction medium on water absorption can reach about 1000 g in distilled water.

In this paper, we study the application of frequency response masking (FRM) technology in polyphase discrete Fourier transform (DFT) filter bank (FB). Due to the inability of FRM methods with conventional structure to simultaneously meet the needs of sharp transition band polyphase DFT FB to improve the signal-to-interference ratio of channelized signals and reduce the complexity of FBs, an improved conjugate frequency modulation frequency response masking (CFM-FRM) method is proposed. The proposed CFM-FRM method solves the problem by frequency modulation, and consumes less multipliers by taking advantage of the orthogonality between sub-filters in CFM-FRM FB. The efficient realization of CFM-FRM based polyphase DFT FB is derived and the multi-size configuration method is illustrated via coefficient decimation. We analyze the adaptability of related FRM works to polyphase DFT FB. The simulation and analysis show that the CFM-FRM method is applicable to polyphase DFT FB, the CFM-FRM based polyphase DFT FB has less multipliers than related methods in other works, and the performances of multi-size FBs meet the requirements. [ABSTRACT FROM AUTHOR]

Thermosets—polymeric materials that adopt a permanent shape upon curing—have a key role in the modern plastics and rubber industries, comprising about 20 per cent of polymeric materials manufactured today, with a worldwide annual production of about 65 million tons1,2. The high density of crosslinks that gives thermosets their useful properties (for example, chemical and thermal resistance and tensile strength) comes at the expense of degradability and recyclability. Here, using the industrial thermoset polydicyclopentadiene as a model system, we show that when a small number of cleavable bonds are selectively installed within the strands of thermosets using a comonomer additive in otherwise traditional curing workflows, the resulting materials can display the same mechanical properties as the native material, but they can undergo triggered, mild degradation to yield soluble, recyclable products of controlled size and functionality. By contrast, installation of cleavable crosslinks, even at much higher loadings, does not produce degradable materials. These findings reveal that optimization of the cleavable bond location can be used as a design principle to achieve controlled thermoset degradation. Moreover, we introduce a class of recyclable thermosets poised for rapid deployment.

Polymeric membranes are ubiquitous in transport applications including gas separation, water desalination, solid-state batteries, and fuel cells. The transport mechanism in certain classes of membranes is well understood. It is generally believed that polymeric membranes used in gas separation follow the solution–diffusion model. However, the transport mechanism in other membranes such as the ones used in water desalination is less clear as both the solution–diffusion and hydrodynamic models have been proposed. In this contribution, we study the structure as well as the water and polymer dynamics of several polymeric membranes using small-angle and quasi-elastic neutron scattering. We demonstrate that on the scale of a few nanometers, water appears to diffuse through a desalination membrane at a rate comparable to bulk water, while water diffuses at a rate that is a factor of 2 slower in an anion-exchange membrane. These results illustrate the importance of studying both the structure and dynamics of membrane materials and have important implications in understanding the transport mechanisms that differentiate the different types of polymeric membranes.

The performance of ion-exchange membranes in fuel cells is critically linked to their ion-conducting morphology. In this report, we analyzed the connectivity of anion-exchange membranes (AEMs) by electrostatic force microscopy (EFM). As a tapping-mode AFM-based technique, EFM probes height, phase, and electrostatic force gradient through two-pass interleave scans, which reveals the direct relationship between membrane surface morphology and connectivity of the ionic domain. The AEMs are diblock copolymers of a polyisoprene (PIp) block and a polystyrenic block containing the phosphonium ion (P(R3P+)MS). Different alignments of cylinders were observed in the bulk and on the surface for AEMs with different ion-exchange capacities (IECs) and preparation methods. The impacts of the cylinder alignment on the connectivity of the ionic domain were then investigated by EFM. For AEM 13 with IEC = 0.44 mmol/g and a hexagonal morphology, cylinders aligned parallel to the surface, which led to many disconnected regions observed throughout the membrane. In contrast, the perpendicularly aligned channels of AEM 16 with IEC = 0.87 mmol/g consisted only of a well-connected ionic phase throughout the membrane.

Precision synthesis of polyorganosiloxanes and temporal control over the polymerization process during ring-opening polymerization (ROP) of cyclosiloxanes remain challenging due to the occurrence of side reactions, e.g., intramolecular transfer (backbiting) and intermolecular chain transfer, and irreversible catalyst transformation. In this study, a merocyanine-based photoacid catalyst is developed for cationic ROP of different cyclosiloxanes. A series of well-defined cyclotrisiloxane polymers with predetermined molar masses and low dispersities (Đ< 1.30) are successfully synthesized under various conditions (i.e., different catalyst loadings, initiator concentrations, solvents, and monomer types). Mechanistic insights by experiments and theoretical calculations suggest that the cationic active species, siloxonium ions, are combined with the catalyst anions to form tight ion pairs, thereby attenuating the reactivity of active species and subsequently minimizing side reactions. An efficient photocatalytic cycle is established among the catalyst, monomer, and polymer chain due to the rapid and reversible isomeric phototransformation of the catalyst, which endows the polymerization process with excellent temporal control. Successful in situ chain extension further confirms the controlled characteristics of photomediated CROP. This as-developed polymerization strategy effectively addresses long-standing challenges in the field of polyorganosiloxane synthesis.

Vast published dielectric ceramics literature is a natural database for big-data analysis, discovering structure–property relationships, and property prediction. We constructed a data-mining pipeline based on natural language processing (NLP) to extract property information from about 12,900 published dielectric ceramics articles and normalized more than 20 properties. The micro-F1 scores for sentence classification, named entities recognition, relation extraction (related), and relation extraction (same), are 91.6, 82.4, 91.4, and 88.3%, respectively. We demonstrated the distribution of some essential properties according to the publication years to reveal the tendency. In order to test the reliability of the data extraction, we trained an XGBoost model to predict the dielectric constant and used the SHAP module to interpret the contribution of each feature in order to identify some of the factors that determine the dielectric properties. The result shows that including Q× fin the model can increase the dielectric constant prediction accuracy. Our work can give some hints to experimentalists on their way to improve the performances of cutting-edge materials.

Electrolytes with improved thermal and oxidative stability must be developed to achieve greater power and energy densities without compromising safety in modern energy storage devices. Because of their much-reduced solvent vapor pressure and expanded electrochemical windows, solvate ionic liquids (SILs) of lithium salts have recently attracted significant attention in this regard. The current palette of SILs is, however, limited to only a few suitable anions with limited chemical functionality. Guided by fundamental physical organic chemistry principles, we designed a new family of S-substituted fluorinated aryl sulfonamide-tagged anions that feature variable numbers of electronically neutral or withdrawing sulfide, sulfoxide, and sulfone substituents. Several salts of these electron deficient anions display very high electrochemical oxidative stability, good solubility, and a weakly coordinating nature that enables the synthesis of Li-based SILs with high thermal and electrochemical oxidative stability. This new family of functional, noncoordinating anions will potentially expand the scope of applications of SILs as safe electrolytes in battery devices.

Diblock copolymers of isoprene and chloromethylstyrene were synthesized by nitroxide-mediate polymerization. The polychloromethylstyrene block was quaternized with tris(trimethoxyphenyl)phosphine (P(Ph(OMe)3)3) or triphenylphosphine (P(Ph)3). Membranes with ion-exchange capacity (IEC) ranging from 0.87 to 2.35 mmol/g were prepared. The bulk morphology was investigated via small-angle X-ray scattering and transmission electron microscopy, where hexagonal and body-centered cubic morphologies were observed. The surface morphology was revealed by atomic force microscopy where both parallel and perpendicular alignments were observed. Compared to P(Ph(OMe)3)3, P(Ph)3exhibits higher quaternization efficiency due to less steric hindrance. Partially quaternized membranes were prepared using P(Ph)3, and the dependence of domain size on the quaternization level is discussed. The morphologies as a function of relative humidity were investigated. For high IEC membranes, although bulk scattering showed small changes in d-spacing, large changes in domain size on the surface occurred between hydrated and dehydrated conditions. Further investigations of morphological reversibility by humidity cycling showed good recovery between humid and dry conditions, indicating that the expansion and contraction of channels is a reversible process.

Lithium-rich layered oxide Li1.2Mn0.54Ni0.13Co0.13O2 is synthesized by solid phase method and followed by surface modification with 2 wt% nAl2O3/SiO2 (n means the molar ratio of Al2O3 and SiO2). The morphology, structure and electrochemical properties of the material samples before and after coating treatment are systematically investigated by X-ray diffraction, field emission scanning electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, cyclic voltammetry, linear sweeping voltammetry, potentiostatic intermittent titration and electrochemical impedance spectroscopy. The results show that a protective multilayer is formed on the material particle surface with a new coating layer like Lix[AlySizO4] and an intermediate layer with lithium-deficient disordered spinel structure after annealing treatment. This multilayer can prevent the material from corrosion of the electrolyte deposition product, provide improved lithium ion transportation and suppress the evolution from layered structure to spinel. The coated samples present the improved initial coulombic efficiency, capacity retention, cycling stability, rate capability and reduced voltage decay compared to the pristine material and it delivers the best comprehensive electrochemical performance when the molar ratio of Al2O3 and SiO2 is 2:1. The main role of Al2O3 and SiO2 in coating for the improvements of the material performance is further discussed.

In radar specific emitter identification (SEI), various types of unintentional modulation on pulse (UMOP) are selected as the features for discriminating between different radars. Unintentional Phase Modulation on Pulse (UPMOP), a typical type of UMOP, can provide crucial information for identifying radars. In most radar SEI algorithms, sacrificing time efficiency for higher accuracy is a common trade-off. This paper proposes a method to solve this problem by combining denoised UPMOP sequences with an Attention-based Gated Recurrent Units (Attention-GRU) model, which showed an excellent performance. Firstly, the cause of UPMOP is analyzed and the phase observation model of radar emitter signals and mathematical model of UPMOP are given. Then, the least-squares method is used to eliminate the linear trend of the phase observation model and obtain a noised estimation of the UPMOP sequences. Thirdly, the uniform B-spline (UBS) curves are then used to fit the noised estimation, resulting in a denoised and refined UPMOP sequence. Finally, the Attention-GRU model is employed to extract features from the denoised UPMOP sequences to identify radar emitters automatically. Results from simulation and measured data experiments show that the overall recognition rate of the algorithm reaches over 93% and the algorithm has excellent performance, with high identification accuracy and relatively low time consumption, even in low signal-to-noise ratio (SNR) conditions. [ABSTRACT FROM AUTHOR]

To enable future applications of block copolymer assemblies, it is critical to develop simple approaches to achieve ultrasmall domain spacings from readily available polymers. In this report, we demonstrate that reduction of polymethyl(meth)acrylate-containing block copolymers with LiAlH4provides novel poly(hydroxyisobutylene)/poly(methallyl alcohol) and poly(hydroxypropylene)/poly(allyl alcohol))-based block copolymers that after thermal annealing display significantly enhanced microphase separation. The effective χ values for these polymers were found to be ≥0.3, and d-spacing values as small as 6.5–7.2 nm were obtained for various morphologies. This work establishes a simple and universal strategy for generation of high χ block copolymers from readily available precursors.

Radar detection and communication transmission play a crucial role in both civilian and military applications, and their integrated implementation has now become a research hotspot. In this paper, we propose a method aiming at the application requirements of fast estimation to solve the issue of low real-time performance in the estimation of range and velocity for multi-carrier OFDM-based radar and communication (RadCom) shared signal. During the process, the shared signal echo model is transformed into a signal model similar to the uniform line array, and uses a weighted time-frequency smoothing (WTFS) algorithm to achieve decoherence processing, then the ESPRIT-MUSIC (E-M) algorithm is further used to achieve joint range and velocity fast estimation. Finally, theoretical analysis and simulation results demonstrate that the proposed WTFS algorithm has better performance compared with the frequency smoothing algorithm, while the E-M algorithm achieves superior resolution accuracy and fast estimation with similar or lower computational complexity than existing more applied estimation methods. [ABSTRACT FROM AUTHOR]

Temperature/pH-responsive hydrogels are one of the most studied environmental-responsive hydrogels, with sensitivity and rapid response being the sought-after properties, while sensitivity and reusability are generally poor. This study prepared a hydrogel with a temperature/pH-responsive core-shell structure by static template polymerization, using the temperature-sensitive monomer dimethylaminoethyl methacrylate polymerized with 2-acrylamide-2-methylpropanesulfonic acid as the temperature-sensitive shell and popcorn with acrylic acid as the pH-responsive core-layer hydrogel. The chemical structure, thermal stability, and morphology of the core-shell structure hydrogels were characterized by Infrared spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer-Emmett-Teller surface (BET), Scanning electron microscopy (SEM), Atomic force microscopy (AFM) and Thermogravimetric analysis (TG), respectively. The pH responsiveness well as the temperature responsiveness of the shell structure was tested. The results showed that the lowest critical solution temperature (LCST) of the core-shell hydrogel is 43 ℃, with good temperature responsiveness in the range of 25–55 ℃, pH responsiveness from pH= 4 to pH= 13, and a short response time. From SEM, AFM, and BET, it can be concluded that the hydrogel has a rough surface and pore structure with a root mean square roughness value of 0.787 nm, a specific surface area of 1.3381 m²/g, and an average pore size of 4.0911 nm. FTIR and XRD can show that popcorn (PCP) is well-doped in the core-shell structure hydrogel, which also proves the existence of the core-shell structure. The design of the core-shell structure enhanced the stability performance of the shell temperature-sensitive hydrogel so that the retention rate of the sample was still 37% at 800 °C, and the water retention rate was still 80.7% after repeated immersion in distilled water 7 times, which has good prospects for agricultural and pharmaceutical applications.

To reveal the effects of welding speed on welding process stability, microstructure, and mechanical performance of SUS304 weldments fabricated by local dry underwater pulsed metal inert-gas welding (LDU-PMIG), the electrical signals and droplet transfer behaviours of welding process, phase morphologies and distributions, grain sizes and grain boundary characteristics, microhardness, and tensile strength of these weldments were investigated in this work. The results indicated that with the increase of welding speed from 9.0 mm/s to 16.2 mm/s, the welding process stability first improved and then deteriorated. The more rapid water cooling rate caused by the increase of welding speed led to the δ-ferrite morphological evolution from skeletal to lath, which promoted the transformation from brittleness to ductility in the weld mechanical performance. Furthermore, the proportions of small-size grains (less than 10 μm) and low-angle grain boundaries (2–15°) first increased and then decreased, which determined the same variation trend in the comprehensive mechanical performance of weldments. The weldment obtained at 12.6 mm/s exhibited the highest microhardness, tensile strength and elongation, which achieved 70.0 %, 92.3 %, and 61.6 % of base metal. These results are conducive to enhance the SUS304 LDU-PMIG weldment quality and facilitate its application in marine equipment field.

Unattended substations are the basis of intelligent substations, which require remote surveillance and control. Limited by the number of visual sensors, remote manual monitoring is incomplete and inefficient. Onsite workers and intruders are easily hidden by the smart grid facility, which affects the safety surveillance of personnel and equipment. The traditional kernelized correlation filter (KCF) method has a poor ability to adapt to the practical environment. This paper presents an anti-occlusion framework on the basis of imaging techniques to solve the problem of optimized surveillance. The novelty is further strengthened by its more practical Deep Learning model and tracking methods. Firstly, a multi-feature fusion model of the HOG feature and color feature is proposed to enhance target characteristics as the target is severely blocked. Secondly, a target classifier training and fast detection method based on improved CNN is introduced. Lastly, to overcome the drawbacks of the KCF tracking algorithm, such as its inability to scale adaptive and blind updates, a new adaptive learning rate strategy is proposed for occlusion tracking. The effects on the OTB-2013 dataset demonstrate that the improved technique has better accuracy and robustness when compared to KCF methods.

Superabsorbent composites (SACs) have great significance in environmental protection and agricultural production. However, it still remains a huge challenge to prepare SACs with the low-cost, strong water and nutrient retention capacity, slow evaporative loss and low water leakage. Herein, ablmoschus manihot gum-g-poly (acrylic acid-co-2-acrylamide-2- methyl-1-propanesulfonic acid)/microcrystalline cellulose (AMG-g-P(AA-co-AMPS)/MCC) SACs was prepared by radical polymerization method and further applied to prevent deep leakage of water in the soil. In which, the MCC extracted from wheat straw was selected as the skeleton to enhance the porous structure of SACs, and the AMG was used as the main moisture absorption material. Because the uniform distribution and abundant pore structure in AMG-g-P(AA-co-AMPS)/MCC, the water absorption of the SACs under the optimum synthetic conditions reached the equilibrium at 30 min in distilled water, and the optimum water absorption of SACs was 1240 g/g, 248 g/g and 80 g/g in distilled water, tap water and 0.9 wt% NaCl solution, respectively. In addition, SACs has good salt tolerance and pH stability. More importantly, the application of SACs in the soil can help improving the soil water retention and water holding capacity, and can reduce the water permeability in the soil effectively. Therefore, the SACs has broad application potential in agriculture.

Microtubules are self-assembling biological nanotubes made of the protein tubulin that are essential for cell motility, cell architecture, cell division, and intracellular trafficking. They demonstrate unique mechanical properties of high resilience and stiffness due to their quasi-crystalline helical structure. It has been theorized that this hollow molecular nanostructure may function like a quantum wire where optical transitions can take place, and photoinduced changes in microtubule architecture may be mediated via changes in disulfide or peptide bonds or stimulated by photoexcitation of tryptophan, tyrosine, or phenylalanine groups, resulting in subtle protein structural changes owing to alterations in aromatic flexibility. Here, we measured the Raman spectra of a microtubule and its constituent protein tubulin both in dry powdered form and in aqueous solution to determine if molecular bond vibrations show potential Fano resonances, which are indicative of quantum coupling between discrete phonon vibrational states and continuous excitonic many-body spectra. The key findings of this work are that we observed the Raman spectra of tubulin and microtubules and found line shapes characteristic of Fano resonances attributed to aromatic amino acids and disulfide bonds.

To alleviate soil impoverishment and water shortage in desert areas, as well as to reduce the impact of waste cabbage on the environment and human health, we used waste cabbage as a substrate, 2-acrylamide-2-methyl-1-propane sulfonic acid (AMPS) and acrylic acid (AA) as polymerization units, and NH4Cl and KNO3as nutriment to obtain two waste cabbage-superabsorbent polymers (CB-SAPNH4Cland CB-SAPKNO3) by the one-pot method. The chemical structure, thermal stability, and morphology of the polymers were investigated by Fourier-transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), and scanning electron microscope (SEM). Meanwhile, the water retention, water absorption, and salt resistance were compared with the purchased polymers. The results showed that the nutriment was successfully encapsulated inside the polymer, and CB-SAPNH4Cland CB-SAPKNO3at 1% nutrient concentration showed excellent water retention properties, salt resistance, and water absorption performance of 1546 and 1131 g/g (distilled water), 306 and 277 g/g (tap water), and 116 and 91 g/g (0.9% NaCl solution). Therefore, they are highly promising materials for the application.

Graft copolymers offer a versatile platform for the design of self-assembling materials; however, simple strategies for precisely and independently controlling the thermomechanical and morphological properties of graft copolymers remain elusive. Here, using a library of 92 polynorbornene-graft-polydimethylsiloxane (PDMS) copolymers, we discover a versatile backbone-pendant sequence-control strategy that addresses this challenge. Small structural variations of pendant groups, e.g., cyclohexyl versus n-hexyl, of small-molecule comonomers have dramatic impacts on order-to-disorder transitions, glass transitions, mechanical properties, and morphologies of statistical and block silicone-based graft copolymers, providing an exceptionally broad palette of designable materials properties. For example, statistical graft copolymers with high PDMS volume fractions yielded unbridged body-centered cubic morphologies that behaved as soft plastic crystals. By contrast, lamellae-forming graft copolymers provided robust, yet reprocessable silicone thermoplastics (TPs) with transition temperatures spanning over 160 °C and elastic moduli as high as 150 MPa despite being both unentangled and un-cross-linked. Altogether, this study reveals a new pendant-group-mediated self-assembly strategy that simplifies graft copolymer synthesis and enables access to a diverse family of silicone-based materials, setting the stage for the broader development of self-assembling materials with tailored performance specifications.

There have been a lot of reports on the preparation and properties of superabsorbent polymers, but there are still some problems and limitations in practical application. Therefore, a superabsorbent polymer (SAP) was synthesized by solution polymerization with tap water as reaction medium, acrylic acid and cross-linked polyvinylpyrrolidone (PVPP) as raw materials. The results of its performance and application show that the particle size was 0.425–0.85 mm, and the maximum water absorption rate of SAP in distilled water, tap water and 0.9% wt% NaCl solution was 2297 g/g, 333 g/g and 120 g/g, respectively. The water absorption rate can reach about 80% of maximum water absorption rate in 30 min. In addition, when the SAP mass addition amount was 0.56% and the particle size was 0.15–0.25 mm, the saturated moisture of sandy soil increased by 187%, the infiltration rate of sandy soil decreased by 96.7% and at 45 °C and 25 °C, the water evaporation rate of sandy soil decreased by 57.52% and 43.61%, respectively. So the material have a good application prospect in desertification and agriculture, and the way of preparation can be more effectively applied in practical production.

In this article, an effective algorithm is proposed for trajectory optimization in airborne radar for extended target tracking (ETT). The key idea of the proposed airborne radar trajectory planning (ARTP) scheme is to model this problem as a partially observable Markov decision process (POMDP) and plan the waypoints of airborne radar using deep reinforcement learning (DRL) in order to improve the target's kinematic state and shape tracking accuracy, subject to the airborne radar maneuverability limitation. Specifically, at each tracking interval, the predicted Gaussian Wasserstein Distance (GWD) is analytically calculated and subsequently adopted as a reward function to evaluate the performance of extended target tracking. Then the DRL agent autonomously learns trajectory planning strategies to maximize ETT performance. Simulation results demonstrate that the proposed ARTP algorithm can deliver superior performance in terms of maximizing the overall ETT performance compared with other benchmarks. [ABSTRACT FROM AUTHOR]

Block polymers assemble into a variety of phase-separated morphologies based on volume fraction (φ) and interactions (χ) of the respective blocks. The arrangement of three different polymer blocks could either be a 3-arm star, with each block having one terminus attached to a common junction point or a linear A-B-C architecture. A versatile strategy is reported to synthesize a series of well-defined graft polymers that lie along the unexplored continuum between a 3-arm star and an A-B-C linear triblock polymer architecture. Using the technique of single-molecule insertion, precise control over the position of graft arm C along the B chain was achieved. A series of discrete graft polymers (PMMA-b-PS-g-PEO) with fixed φ and prescribed ω values that lie on the continuum between a 3-arm star (ω = 0) and linear triblock polymer (ω = 1) were synthesized. Morphological studies using small-angle X-ray scattering and conventional and energy-filtered transmission electron microscopy reveal the transition between lamellae, perforated lamellae, and cylindrical morphologies with systematic variation in the ω values, a trend attributed to the topological frustration and the associated χ values between the three blocks. Molecular dynamic simulations of coarse-grained models were found to predict phase diagrams that are consistent with the experimentally observed morphologies. Our results suggest that changes in ω lead to topological frustration which is an important additional new design parameter that can be used to tune the morphology of multiblock polymers in addition to φ and χ.

Polymer electrolytes (PEs) have attracted tremendous research interest for their potential to offer improved safety and energy capacity in next-generation battery technologies. Among the different classes of PEs, single-ion conductors (SICs) are particularly interesting due to their high transference numbers. Nevertheless, a detailed understanding of how molecular structure impacts the properties of SIC-PEs is absent, limiting the ability to design improved materials. Here, we present the synthesis and characterization of a new class (seven examples provided) of polyanions featuring fluorinated aryl sulfonimide tagged (FAST) anions as side chains. These “polyFAST” salts are shown to outperform the widely used poly[(4-styrenesulfonyl) (trifluoromethanesulfonyl)imide] due to their strongly electron-withdrawing side chains and enhanced distance between anionic sites, providing higher electronic conductivities at all salt concentrations and in some cases superior electrochemical oxidative stability. Moreover, they provide a platform for discovery of fundamental relationships between macromolecular composition, as programmed through monomer structure, and SIC-PE bulk properties. Finally, we leverage the electron-deficient nature of polyFAST salts to demonstrate a new poly(solvate ionic liquid) (polySIL) concept that offers a promising pathway toward high-performance PEO-free SIC-PEs.

In order to reduce the pollution of the bio-waste cabbage to the environment and achieve recycling of biological waste resources, synthesis of a novel superabsorbent polymer gel based on waste cabbage (CB) using two monomers AMPS (2-acrylamide-2-methyl-1-propane sulfonic acid) and AA (acrylic acid). And the synthesis conditions were optimized, such as the ratio of AMPS and AA, initiator content, and crosslinker content. And the water retention, salt resistance and repeated swelling performance were investigated too. The chemical structure thermal stability and microscopic appearance of the superabsorbent polymer gel were investigated by Fourier transform infrared spectroscopy (FTIR), Thermal gravimetric analysis (TGA) and Scanning electron microscope (SEM). The results showed that the novel superabsorbent polymer gel exhibits excellent water absorbency, which can absorb ultrapure water, distilled water, tap water and 0.9% NaCl solution are 1914 g/g, 1726 g/g, 306g/g and 114g/g, respectively. This is higher than in related studies 30%-40% in distilled water, 60%-70% in tap water and 10%-20% in 0.9% NaCl solution. Therefore, this superabsorbent polymer gel showed a high swelling property and stable salt resistance. It has a broad application prospect.

•A one-step carbonization and mixed metal salts-assisted co-activation method is proposed;.•Biomass-derived porous carbon frameworks with hollow nanostructures is prepared;.•The formation of hollow carbon frameworks and the activation mechanism have been studied;.•ZLPC shows satisfactory specific capacitance, wide operating voltage and high specific energy.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Lithium-rich layered oxide Li1.2Mn0.54Ni0.13Co0.13O2is synthesized by solid phase method and followed by surface modification with 2 wt% nAl2O3/SiO2(n means the molar ratio of Al2O3and SiO2). The morphology, structure and electrochemical properties of the material samples before and after coating treatment are systematically investigated by X-ray diffraction, field emission scanning electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, cyclic voltammetry, linear sweeping voltammetry, potentiostatic intermittent titration and electrochemical impedance spectroscopy. The results show that a protective multilayer is formed on the material particle surface with a new coating layer like Lix[AlySizO4] and an intermediate layer with lithium-deficient disordered spinel structure after annealing treatment. This multilayer can prevent the material from corrosion of the electrolyte deposition product, provide improved lithium ion transportation and suppress the evolution from layered structure to spinel. The coated samples present the improved initial coulombic efficiency, capacity retention, cycling stability, rate capability and reduced voltage decay compared to the pristine material and it delivers the best comprehensive electrochemical performance when the molar ratio of Al2O3and SiO2is 2:1. The main role of Al2O3and SiO2in coating for the improvements of the material performance is further discussed.