Robust Resistance Research Articles

High metal-loaded sub-nanocluster catalyst enhanced Fenton-like reaction activity for emerging contaminants degradation by generating high-valent copper

High-valent copper (Cu(III)) species are crucial intermediates in CH bond functionalization within both the biological and biomimetic processes, facilitated by copper enzymes and stabilized by multicopper oxidases. Herein, a nitrogen-doped copper sub-nanocluster catalyst (SNC) featured a high metal content (29.1 wt%) and uniform Cu distribution was synthesized by carbonizing the nanosheet-like metal–organic framework (MOF), enhancing bisphenol A degradation by activating peroxymonosulfate (PMS) to generate Cu(III). The degradation performance of the SNC outperformed the catalyst carbonized with the bulk-like MOF and matched the reported single-atom catalysts counterparts. Nitrogen doping decreased the electrons of Cu3d orbital, enhancing its bonding with the oxygen atom within the PMS molecule, thus promoting Cu(III) generation. The Cu-SNC/PMS system also showed robust resistance against anions, pH changes, and diverse water matrices. Importantly, it can selectively degrade electron-rich pollutants through oxygen atom transfer by Cu(III). This study provided new perspectives into SNC preparation, the controlled formation of high-valent metal species, and their role in Fenton-like reactions for pollutants degradation.

Functional Ginger-Derived Extracellular Vesicles-Coated ZIF-8 Containing TNF-α siRNA for Ulcerative Colitis Therapy by Modulating Gut Microbiota.

Tumor necrosis factor-α (TNF-α) plays a causal role in the pathogenesis of ulcerative colitis (UC), and anti-TNF-α siRNA shows great promise in UC therapy. However, delivering siRNA with site-targeted stability and therapeutic efficacy is still challenging due to the complex and dynamic intestinal microenvironment. Here, based on the functional plant-derived ginger extracellular vesicles (EVs) and porous ZIF-8 nanoparticles, we propose a novel TNF-α siRNA delivery strategy (EVs@ZIF-8@siRNA) for UC targeted therapy. Ginger EVs show strong colon and macrophage targeting, as well as robust resistance to acidic degradation in the stomach. Moreover, 6-shogaol in ginger-derived EVs displays anti-inflammatory effects, which enhance the treatment efficiency by cooperation with TNF-α siRNA. In vitro experiments reveal that ZIF-8 nanoparticles have high TNF-α siRNA loading capacity and promote siRNA escape from cellular lysosomes. In vivo experiments show that the TNF-α level is reduced more significantly in colonic tissue than other nontargeted inflammation related factors, showing a good targeting of this composite nanoparticle. Furthermore, gut microbiota sequencing results demonstrate that the nanoparticles can promote intestinal barrier repair by regulating the intestinal microbial balance and restoring the intestinal health of UC mice. Therefore, the developed EVs@ZIF-8@siRNA nanoparticles may represent a novel colon-targeted oral drug, providing a promising therapeutic strategy for UC therapy.

"Straw in the Clay Soil" Strategy: Anticarbon Corrosive Fluorine-Decorated Graphene Nanoribbons@CNT Composite for Long-Term PEMFC.

Carbon corrosion poses a significant challenge in polymer exchange membrane fuel cells (PEMFCs), leading to reduced cell performance due to catalyst layer degradation and catalyst detachment from electrodes. A promising approach to address this issue involves incorporating an anticorrosive carbon material into the oxygen reduction reaction (ORR)electrode, even in small quantities (≈3wt% in electrode). Herein, the successful synthesis of fluorine-doped graphene nanoribbons (F-GNR) incorporated with graphitic carbon nanotubes (F-GNR@CNT), demonstrating robust resistance to carbon corrosion is reported. By controlling the synthesis conditions using an exfoliation method, the properties of the composite are tailored. Electronic structural studies, employing density functional theory (DFT) calculations, to elucidate the roles of fluorine dopants and graphitic carbon nanotubes (CNTs)in mitigating carbon corrosion are conducted. Physicochemical and electrochemical characterization of F-GNR@CNT reveal its effectiveness as a cathode additive at the single-cell scale. The addition of F-GNR@CNT to the Pt/C cathode improves durability by enhancing carbon corrosion resistance and water management, thus mitigating the flooding effect through tailored surface properties. Furthermore, advanced impedance analysis using a transmission line model is performed to gain insights into the internal resistance and capacitive properties of electrode structure.

Rapid synthesis of novel S-scheme CaBi6O10/Bi2WO6 heterojunction film for efficient p-chlorophenol photocatalytic degradation

Efficient photocatalysts played a crucial role for degrading phenol pollutants in wastewater and vital for environmental remediation. In this study, a series of novel CaBi6O10/Bi2WO6 (CBO/BWO) step-scheme (S-scheme) heterojunction films were synthesized on the glass substrates through a facile and rapid spraying-calcination method. The CBO/BWO film demonstrated superior visible-light-driven catalytic activity for p-chlorophenol (4-CP) degradation within the fixed-bed photoreactor setup, compared with those of the single-component samples. Typically, the optimal 40CBO/BWO catalyst achieved 4-CP degradation efficiency of approximately 89.5 % after only 60 min under light exposure, attributed to the enhanced visible-light-absorption property and effective charge separation within the S-scheme heterojunction while maintaining high redox abilities among photoinduced carriers. Furthermore, the CBO/BWO catalyst displayed robust resistance to various metal cationic additives. Multiple key intermediates, such as phenol, dihydroxybenzene, benzoquinone and maleic acid, were identified in catalyzing process of 4-CP decomposition via oxidation processes involving hydroxyl radicals and superoxide radical as the primary active species. The above feasible photodegradation mechanism was elucidated and proven. Hence, this work offers valuable insights into developing efficient heterostructure photocatalysts for practical application of environmental remediation.

Emotion Recognition Using EEG Signals through the Design of a Dry Electrode Based on the Combination of Type 2 Fuzzy Sets and Deep Convolutional Graph Networks.

Emotion is an intricate cognitive state that, when identified, can serve as a crucial component of the brain-computer interface. This study examines the identification of two categories of positive and negative emotions through the development and implementation of a dry electrode electroencephalogram (EEG). To achieve this objective, a dry EEG electrode is created using the silver-copper sintering technique, which is assessed through Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Analysis (EDXA) evaluations. Subsequently, a database is generated utilizing the designated electrode, which is based on the musical stimulus. The collected data are fed into an improved deep network for automatic feature selection/extraction and classification. The deep network architecture is structured by combining type 2 fuzzy sets (FT2) and deep convolutional graph networks. The fabricated electrode demonstrated superior performance, efficiency, and affordability compared to other electrodes (both wet and dry) in this study. Furthermore, the dry EEG electrode was examined in noisy environments and demonstrated robust resistance across a diverse range of Signal-To-Noise ratios (SNRs). Furthermore, the proposed model achieved a classification accuracy of 99% for distinguishing between positive and negative emotions, an improvement of approximately 2% over previous studies. The manufactured dry EEG electrode is very economical and cost-effective in terms of manufacturing costs when compared to recent studies. The proposed deep network, combined with the fabricated dry EEG electrode, can be used in real-time applications for long-term recordings that do not require gel.

Staged dendrite suppression for high safe and stable lithium-sulfur batteries

The unavoidable dendrite growth and shuttle effect have long been stranglehold challenges limiting the safety and practicality of lithium-sulfur batteries. Herein, we propose a dual-action strategy to address the lithium dendrite issue in stages by constructing a multifunctional surface-negatively-charged nanodiamond layer with high ductility and robust puncture resistance on polypropylene (PP) separator. The uniformly loaded compact negative layer can not only significantly enhance electron transmission efficiency and promote uniform lithium deposition, but also reduce the formation of dendrite during early deposition stage. Most importantly, under the strong puncture stress encountered during the deterioration of lithium dendrite growth under limiting current, the high ductility and robust puncture resistance (145.88 MPa) of as-obtained nanodiamond layer can effectively prevent short circuits caused by unavoidable lithium dendrite. The Li||Li symmetrical cells assembled with nanodiamond layer modified PP demonstrated a stable cycle of over 1000 h at 2 mA cm−2 with a polarization voltage of only 29.3 mV. Additionally, the negative charged layer serves as a physical barrier blocking lithium polysulfide ions, effectively mitigating capacity attenuation. The improved cells achieved a capacity decay of only 0.042% per cycle after 700 cycles at 3 C, demonstrating effective suppression of dendrite growth and capacity attenuation, showing promising prospect.

NMR-Based Metabolomic Analysis of Biotic Stress Responses in the Traditional Korean Landrace Red Pepper (Capsicum annuum var. annuum, cv. Subicho).

Korean landrace red peppers (Capsicum annuum var. Subicho), such as the traditional representative Subicho variety, are integral to Korean foods and are often consumed raw or used as a dried powder for cuisine. However, the known vulnerability of local varieties of landrace to biotic stresses can compromise their quality and yield. We employed nuclear magnetic resonance (NMR) spectroscopy coupled with a multivariate analysis to uncover and compare the metabolomic profiles of healthy and biotic-stressed Subicho peppers. We identified 42 metabolites, with significant differences between the groups. The biotic-stressed Subicho red peppers exhibited lower sucrose levels but heightened concentrations of amino acids, particularly branched-chain amino acids (valine, leucine, and isoleucine), suggesting a robust stress resistance mechanism. The biotic-stressed red peppers had increased levels of TCA cycle intermediates (acetic, citric, and succinic acids), nitrogen metabolism-related compounds (alanine, asparagine, and aspartic acid), aromatic amino acids (tyrosine, phenylalanine, and tryptophan), and γ-aminobutyric acid. These findings reveal the unique metabolic adaptations of the Subicho variety, underscoring its potential resilience to biotic stresses. This novel insight into the stress response of the traditional Subicho pepper can inform strategies for developing targeted breeding programs and enhancing the quality and economic returns in the pepper and food industries.

Cross-linked copolyimide-P84/CAU-10-H/branched polyethyleneimine membranes for organic solvent nanofiltration

The advancement of organic solvent nanofiltration (OSN) is often hindered by the inherent trade-off between permeance and rejection. In this study, we present a novel nanocomposite mixed matrix membrane (MMM) fabricated by integrating a compatible metal–organic framework (CAU-10-H) into a co-polyimide (P84) matrix. The resulting P84/CAU-10-H membrane was cross-linked using branched polyethyleneimine (PEI) to produce a P84/CAU-10-H/PEI MMM with robust resistance to harsh organic solvents, making it suitable for OSN applications. The integration of CAU-10-H, PEI, and P84 significantly enhanced the OSN performance, improving sieving efficiency and reducing fouling tendencies. The fabricated membrane exhibited outstanding permeance across various solvents, with values of 42.4, 45.4, 24.5, and 27.1 LMH/bar for methanol, acetone, N-methyl-2-pyrrolidone (NMP), and dimethyl sulfoxide (DMSO), respectively. Besides, the P84/CAU-10-H/PEI MMM demonstrated excellent rejection (Brilliant yellow (BY) > 90 %, Congo red (CR), Methyl blue (MB), Evans blue (EB), and Alcian blue (AB) > 99 %, respectively). In a 96-hour long-term test, the membrane demonstrated excellent stability and anti-fouling properties. This study presents a facile and viable approach for designing and constructing novel OSN MMMs.

Epoxy resin gel particles with adjustable stickiness and deformability for pesticide delivery

It is essential to develop a pesticide delivery system with a simple preparation process and strong leaf retention capability. In this study, epoxy resin (ER) was modified with alcohols with different carbon chain lengths through a one-step reaction to synthesize modified prepolymers (ModER). Among these, the ER modified by dodecanol (ER/Dodecanol) exhibited high flexibility, exceptional stickiness and the highest surface free energy. Subsequently, the organic phase containing emamectin benzoate (EB) and ModER was directly mixed with the aqueous phase containing sodium lignosulfonate (SL) to instantaneously obtain pesticide-loaded epoxy resin gel particles (ModERMP) through self-emulsification and electrostatic interaction. ER/Dodecanol loaded with EB (EB@ER/Dodecanol) had excellent flexibility. The particles underwent significant flattening, transitioning from micron-sized spherical particles to “biscuit-type” particles with nanoscale thickness. EB@ER/Dodecanol exhibited outstanding stickiness, enabling it to adhere to the mouthparts and legs of insects, thereby impacting their feeding behavior. Compared with that of the control, the leaf feeding rate for the experimental group was decreased by 9.36%. EB@ER/Dodecanol also had affinity for foliar micro/nanostructures while displaying excellent washout resistance. Following washing, the residue rate increased by 33.7% compared to that of the emulsifiable concentrate (EC). Furthermore, EB@ER/Dodecanol had excellent insecticidal activity both before and after washout. ModERMP represents a simple preparation process with robust washout resistance, thereby enhancing pesticide utilization rates.

Stable Lithium Oxygen Batteries Enabled by Solvent-diluent Interaction in N,N-dimethylacetamide-based Electrolytes.

In the pursuit of next-generation ultrahigh-energy-density Li-O2 batteries, it is imperative to develop an electrolyte with stability against the strong oxidation environments. N,N-dimethylacetamide (DMA) is a recognized solvent known for its robust resistance to the highly reactive reduced oxygen species, yet its application in Li-O2 batteries has been constrained due to its poor compatibility with the Li metal anode. In this study, a rationally selected hydrofluoroether diluent, methyl nonafluorobutyl ether (M3), has been introduced into the DMA-based electrolyte to construct a localized high concentration electrolyte. The stable -CH3 and C-F bonds within the M3 structure could not only augment the fundamental properties of the electrolyte but also fortify its resilience against attacks from O2 - and 1O2. Additionally, the strong electron-withdrawing groups (-F) presented in the M3 diluent could facilitate coordination with the electron-donating groups (-CH3) in the DMA solvent. This intermolecular interaction promotes more alignments of Li+-anions with a small amount of M3 addition, leading to the construction of an anion-derived inorganic-rich SEI that enhances the stability of the Li anode. As a result, the Li-O2 batteries with the DMA/M3 electrolyte exhibit superior cycling performance at both 30 °C (359th) and -10 °C (120th).

Stable Lithium Oxygen Batteries Enabled by Solvent‐diluent Interaction in N,N‐dimethylacetamide‐based Electrolytes

AbstractIn the pursuit of next‐generation ultrahigh‐energy‐density Li−O2 batteries, it is imperative to develop an electrolyte with stability against the strong oxidation environments. N,N‐dimethylacetamide (DMA) is a recognized solvent known for its robust resistance to the highly reactive reduced oxygen species, yet its application in Li−O2 batteries has been constrained due to its poor compatibility with the Li metal anode. In this study, a rationally selected hydrofluoroether diluent, methyl nonafluorobutyl ether (M3), has been introduced into the DMA‐based electrolyte to construct a localized high concentration electrolyte. The stable −CH3 and C−F bonds within the M3 structure could not only augment the fundamental properties of the electrolyte but also fortify its resilience against attacks from O2− and 1O2. Additionally, the strong electron‐withdrawing groups (−F) presented in the M3 diluent could facilitate coordination with the electron‐donating groups (−CH3) in the DMA solvent. This intermolecular interaction promotes more alignments of Li+‐anions with a small amount of M3 addition, leading to the construction of an anion‐derived inorganic‐rich SEI that enhances the stability of the Li anode. As a result, the Li−O2 batteries with the DMA/M3 electrolyte exhibit superior cycling performance at both 30 °C (359th) and −10 °C (120th).

A robust color image encryption scheme with complex whirl wind spiral chaotic system and quadrant-wise pixel permutation

This paper presents a novel encryption technique that uses a unique chaotic circuit design called as 3D Complex Whirl Wind Spiral chaotic system (CWWS). The major goal of this novel approach is to create an efficient 3D chaotic systems with increased randomness and multistability, specifically designed to encrypt multimedia data. The design incorporates the sine function sin(x) to introduce complexity and unpredictability in the chaotic circuit. The dynamic behaviour of the proposed scheme’s chaotic system is thoroughly evaluated using a variety of analyses, including KY dimension, dissipativity, Lyapunov exponent spectra, and bifurcation diagrams. There are two key stages to the encryption process: diffusion and confusion. The diffusion process is strengthened by the smooth integration of quadrant-wise pixel permutation (QWPP) algorithms, which eliminate correlations between neighbouring pixels. Following that, the image components are concealed using the chaotic sequence that was generated from the 3D CWWS chaotic system. The complete encrypted image is then created by combining these encrypted components. The simulation results of the proposed strategy are thoroughly investigated using statistical analysis, differential analysis, and brute force attacks. The system has optimal key space, entropy, UACI, and NPCR metric values of 2400, 7.99, 0.334, and 0.996, respectively. Furthermore, the experimental findings show robust resistance to statistical, differential, and brute force attacks for a single round of iteration.

Optimized Fabrication of Flexible Paper‐Based PCBs with Pencil and Copper Electroplating

AbstractThis research unveils a transformative methodology for fabricating flexible printed circuit boards (PCBs), focusing on the unique attributes of filter paper substrates. A meticulous parametric exploration scrutinizes critical aspects such as buckling resistance, charging current, plating time, and electrode configurations for copper electroplating. Key findings highlight the exceptional stability of copper electroplating on filter paper, exhibiting robust resistance against environmental variations and bending angles spanning +180° to −180°. Utilizing higher pencil grade material and maintaining a minimum 4 cm distance with a voltage range of 3 to 1.44 V ensures uniform, controlled plating without burning, optimizing the electrode area below 1 cm2for enhanced practicality. The research underscores the longevity and durability of copper‐plated filter paper, with negligible resistance changes even after 1000 folds. Over a year, the shelf‐life assessment emphasizes the excellent stability of electroplated filter paper. Practical applications, including fully functional circuits and a bio‐degradable piano, underscore the versatility and real‐world feasibility of the proposed electroplating technique.

Immunosuppressant therapy averts rejection of allogeneic FKBP1A-disrupted CAR-T cells

Chimeric antigen receptor (CAR) Tcells from allogeneic donors promise "off-the-shelf" availability by overcoming challenges associated with autologous cell manufacturing. However, recipient immunologic rejection of allogeneic CAR-T cells may decrease their invivo lifespan and limit treatment efficacy. Here, we demonstrate that the immunosuppressants rapamycin and tacrolimus effectively mitigate allorejection of HLA-mismatched CAR-T cells in immunocompetent humanized mice, extending their invivo persistence to that of syngeneic humanized mouse-derived CAR-T cells. In turn, genetic knockout (KO) of FKBP prolyl isomerase 1A (FKBP1A), which encodes a protein targeted by both drugs, was necessary to confer CD19-specific CAR-T cells (19CAR) robust functional resistance to these immunosuppressants. FKBP1AKO 19CAR-T cells maintained potent invitro functional profiles and controlled invivo tumor progression similarly to untreated 19CAR-T cells. Moreover, immunosuppressant treatment averted invivo allorejection permitting FKBP1AKO 19CAR-T cell-driven B cell aplasia. Thus, we demonstrate that genome engineering enables immunosuppressant treatment to improve the therapeutic potential of universal donor-derived CAR-T cells.

Resistance of plant diversity to road disturbance: Evidence from the Tibetan Plateau

The expansion of road networks in recent decades has drawn considerable attention due to its impact on biodiversity in high-altitude ecosystems. Here, we conducted a comprehensive field survey to investigate the effects of road disturbance on plant diversity in alpine grasslands on the Tibetan Plateau. Our results indicate that road disturbance caused no significant changes in species richness, Shannon–Wiener’s diversity, or Simpson’s diversity, and the alteration in species composition was limited. These findings demonstrate the robust resistance of alpine grassland plant diversity to road disturbance. Plant diversity exhibited more resistance to road disturbance in regions with more hostile environments, such as plateau sub-frigid regions and alpine steppes. Our study suggests that road construction in the Tibetan Plateau poses limited risk to plant biodiversity.

Developing high-flux dense Janus membrane with robust wetting and scaling resistance: A systematic comparison with Omniphobic membranes

Membrane wetting, scaling and low flux are challenging obstacles for membrane distillation (MD). However, the lack of advanced membranes capable of achieving both high flux and high wetting/scaling resistance constrains MD potential applications. Herein, a dense Janus membrane (JM) was facilely developed by co-depositing a dense PVA/PDA layer on a highly porous PTFE substrate to overcome this dilemma and systematically compared with omniphobic PTFE substrates with varied pore sizes for the first time. Results showed that, unlike flux-resistance “trade-off” observed for PTFE substrates, dense JM effectively resisted 0.4 mM SDS at a high flux of 56.8 LMH and retarded membrane scaling by 20 mM oversaturated gypsum. Robust wetting resistance was primarily attributed to the sieving effect of the sub-nanometer surface layer, which greatly protected substrate from SDS adsorption and feed intrusion, and was less affected by severe surface concentration polarization and relatively low substrate LEP than PTFE substrates. Strongly polar PVA/PDA layer provided a much more thermodynamically unfavorable continuous interface for gypsum adhesion than PTFE substrates, which played a key role in determining anti-scaling behavior. In contrast, gypsum still tended to rapidly cause membrane scaling in stagnant zones within PTFE substrates when flux was increased. This study shall provide new insights in designing high-performance membranes for robust hypersaline wastewater treatment, and highlighting dense JMs with a macroporous substrate and a highly hydrophilic dense surface layer as ideal alternatives.

Expression, Purification, and Anti-UV Irradiation Effect of RsSOD on HCE-T Human Corneal Epithelial Cells.

Superoxide dismutase (SOD) is a class of enzymes that catalyze the disproportionation of superoxide anion radicals into hydrogen peroxide and oxygen. It can remove excessive free radicals in organisms and acts as a potent antioxidant, cleaning free radicals generated by radiation and protecting cells from oxidative damage. In this study, we obtained a MnSOD gene from the radiation-resistant bacterium Radiobacillus sp. (RsSOD) and constructed its recombinant expression vector through gene synthesis. The recombinant RsSOD protein was efficiently expressed using IPTG induction, and purified via repeated freezing and thawing, heating, and DEAE anion-exchange chromatography. The purified RsSOD exhibited an enzyme activity of 2072.5 U/mg. Furthermore, RsSOD was demonstrated to have robust resistance to high temperatures, acid, alkali, and artificial intestinal fluid. Further studies were performed to investigate the radiation resistance of RsSOD against ultraviolet (UV) irradiation in human corneal epithelial (HCE-T) cells. The results indicated that a low concentration of RsSOD (6.25 U/mL) could promote HCE-T cell proliferation and protect these cells from damage caused by both long-term and short-term UV exposure, effectively reducing apoptosis induced by short-term UV irradiation. These findings suggest that the RsSOD protein possesses significant anti-UV irradiation property and is expected to be a candidate for treating ocular radiation-related diseases.

Progressive collapse resistance of self-resilient composite frames under fire conditions

Self-resilient composite frames exhibit robust resistance to progressive collapse and excellent seismic performance. However, their behavior under fire conditions is inadequately explored. This study investigates the collapse resistance mechanisms and response of self-resilient composite frame substructures (SRCFS) under fire-induced progressive collapse. A three-dimensional finite element model was developed, incorporating temperature-dependent thermal and mechanical properties of concrete and steel. Sequentially coupled thermal-mechanical analysis was conducted using the ABAQUS/Explicit solver in a quasi-static manner. Existing experimental data at both ambient and high temperatures were used to validate the proposed model. The study analyzed the contributions of steel beams and strands to vertical resistance, examining their impact on the collapse-resistance mechanism through a constant load-heating transient loading scheme. Structural responses under ambient and fire conditions were compared, focusing on different damage mechanisms. The effects of initial prestressing of strands, angle gauge length, angle thickness, and various heating curves on collapse resistance were evaluated. Findings suggest that the ISO-834 standard's failure criterion is overly conservative for SRCFS, as it neglects the enhanced load-carrying capacity provided by tensile catenary action. This mechanism offers additional escape time, enhancing personnel safety. The study identifies factors influencing the performance of SRCFS against progressive collapse under fire and proposes design recommendations.

Core-Shell PEDOT-PVDF Nanofiber-Based Ammonia Gas Sensor with Robust Humidity Resistance.

Current ammonia sensors exhibit cross-sensitivity to water vapor, leading to false alarms. We developed a core-shell nanofiber (CSNF) structure to address these issues, using conductive poly(3,4-ethylenedioxythiophene) (PEDOT) as the core and hydrophobic polyvinylidene fluoride-tetrafluoroethylene (PVDF-TrFE) as the shell. The PEDOT-PVDF CSNF, with a diameter of ~500 nm and a 300 nm thick PVDF layer, showed a superior sensitivity and humidity resistance compared to conventional PEDOT membranes for ammonia concentrations of 10-100 ppm. In humid environments, CSNF sensors outperformed membrane sensors, exhibiting a tenfold increase in performance at 51% relative humidity (RH). This study highlights the potential of CSNF sensors for practical ammonia detection, maintaining a high performance under varying humidity levels.

An improved histogram algorithm for DOA estimation based on single vector acoustic system

The integration of a singular vector acoustic system onto an unmanned underwater platform can lead to achieving unambiguous direction finding across the entire space. To enhance the direction-finding capabilities of the single vector acoustic system for low noise target, a refined histogram algorithm utilizing coherent spectrum weighting is suggested. A comparative evaluation and analysis of the target azimuth estimation performance of the enhanced histogram algorithm, traditional frequency-weighted histogram algorithm, and energy-weighted histogram algorithm are carried out. Through computer simulations, it is observed that the three Direction of Arrival (DOA) algorithms exhibit comparable direction-finding capabilities for wideband signals, whereas for single-frequency signals, the improved histogram algorithm surpasses the two conventional algorithms in direction-finding accuracy. Specifically, at a signal-to-noise ratio (SNR) of −40 dB, the azimuth estimation root mean square error (RMSE) is approximately 2°. Findings from sea trials indicate that the improved histogram algorithm displays a narrower spectral peak width and robust resistance to noise interference, thereby substantiating the effectiveness of the enhanced histogram algorithm.