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Two novel ionic red/near-infrared Ir(III) complexes (Ir1 and Ir2) were reasonably designed and prepared using 2-(1-isoquinolinyl)-9,10-anthraquinone as the main ligand and 4,4′-dimethyl-2,2′-bipyridyl and 4,4′-dimethoxy-2,2′-bipyridyl as the auxiliary ligands, respectively. Both complexes showed bright phosphorescence in solution (peak at 618 nm with a shoulder at 670 nm). Interestingly, the phosphorescence peak of two Ir(III) complexes showed a blue-shift of about 36 nm after being ground. Simultaneously, both complexes exhibited mechanical force-induced enhanced emission, and the intensity of the luminescence for Ir1 and Ir2 increased by around two times compared to the one before being ground, respectively. Powder X-ray diffraction (PXRD) and time-dependent density functional theory (TD-DFT) calculation were utilized to understand well the mechanism of this phenomenon and suggested that the destruction of the well-ordered crystalline nature and the decline in triplet-triplet annihilation maybe responsible for the pressure-induced blue-shift and the enhancement of the phosphorescence. [ABSTRACT FROM AUTHOR]

Two novel neutral phosphorescent iridium(III) complexes (Ir1 and Ir2) were rationally designed and synthesized with high yields using 10,11,12,13-tetrahydrodibenzo[a,c]phenazine as the main ligand. The two complexes showed bright-red phosphorescence (625 nm for Ir1, and 620 nm for Ir2, in CH2Cl2), high-luminescence quantum efficiency (0.32 for Ir1, and 0.35 for Ir2), obvious solvatochromism and good thermostability. Then, they were used to fabricate high-efficiency red OLEDs via vacuum evaporation; the maximum current efficiency, power efficiency, and external quantum efficiency of the red devices based on Ir1 and Ir2 are 13.47/15.22 cd/A, 10.35/12.26 lm/W, and 10.08/7.48%, respectively. [ABSTRACT FROM AUTHOR]

The impedance step between different materials inevitably leads to serious energy loss during acoustic emission, transmission, and receiving. In this paper, a tunable gradient impedance matching layer (TGIML) was designed and fabricated to eliminate the impedance step. The TGIML was composed of periodical piezoelectric disks with shunting capacitors. Through the elaborate modulation of the capacitances of the shunting capacitors, the proposed TGIML can adapt interfaces formed by different materials. Two interfaces formed by solid rods were constructed to demonstrate the performance of the TGIML. The simulated and experimental results verified that, after inserting the TGIML, the transmission could be enhanced significantly in a wide frequency range for both interfaces. We believe that the proposed TGIML has great potential for wide applications in the development of ultrasound transducers, nondestructive testing, and energy harvesting. [ABSTRACT FROM AUTHOR]

The method of rigorous coupled-wave analysis (RCWA) is developed to analyze the diffraction properties of acoustic parity-time-symmetric gratings. Asymmetric diffraction can be generated in these gratings, and the +1st order transmitted wave is suppressed completely at the diffraction vanishing point (DVP). The influence factors of the modulation ratio of the DVP, including the modulation amplitude and modulation approach, are systematically discussed using the method of RCWA. Two-beam diffraction with Bragg incident angle is studied in detail. The results show that the modulation ratio of the DVP changes with the modulation amplitude differently for different modulation approaches. The attenuation or enhancement of the sound energy depends on the sign of incident angle and the modulation ratio. [ABSTRACT FROM AUTHOR]

Losses in media have become fresh elements in the designing of asymmetric acoustic transmission and reflection without the nonlinear effect. In this paper, we demonstrate the diffraction control by equipping fine-tuned losses in a non-Hermitian acoustic grating. Compared to the Hermitian grating without losses, the positive first order diffracted wave with negative incidence will be suppressed perfectly, but the negative first order diffracted wave with positive incidence will be enhanced counterintuitively in the lossy diffraction grating. The physical mechanism is that losses can modulate the magnitudes of Bloch wave vectors through the interplay with the real modulation of the refractive index. Absorption is demonstrated as a powerful way to control the acoustic diffraction. [ABSTRACT FROM AUTHOR]

The automatic generation of natural language is a complex and essential task in text processing. This study proposes a novel approach to address this fundamental problem by leveraging an improved version of DST_BERT, a model that converts input text into a vector representation. Our key contribution lies in the joint optimization of two models, NLU (Natural Language Under-standing) and NLG (Natural Language Generation), which enables us to obtain variable representations within a hidden space. This integration enhances the capabilities of both NLU and NLG in generating coherent and contextually appropriate language. The NLU and NLG models are seamlessly integrated with the hidden variable space, forming a generative representation model. To assess the effectiveness of our proposed approach, we conducted extensive experiments on the E2E and Weather datasets. The results highlight the state-of-the-art performance achieved by our model in generating natural language. [ABSTRACT FROM AUTHOR]

This paper reviews ancient Chinese city maps and discusses their categories and features. Based on the status quo of research on the history of Chinese maps, the paper proposes existing problems and argues that ancient Chinese city maps are a kind of "ideological images." Then, it focuses on the relationship between maps and cities. From the perspective of urban planning and architectural studies, it explores the corresponding roles of different maps (chorography, large-scale city maps, and regional maps) in city image, urban structure, and regional urban structure. Finally, it elaborates the significance of combining literature references with actual image analysis, to promote the research on ancient cities through both quantitative analysis based on ancient city database and research tools. [ABSTRACT FROM AUTHOR]

Aiming at the challenges that the traditional photoplethysmography (PPG) biometrics is not robust and precision of recognition, this paper proposes a dual-feature and multi-scale fusion using U2-net deep learning model (DMFUDM). First, to obtain complementary information of different features, we extract the local and global features of one-dimensional multi-resolution local binary patterns (1DMRLBP) and multi-scale differential feature (MSDF). Then, to extract robust discriminant feature information from the 1DMRLBP and MSDF features, a novel two-branch U2-net framework is constructed. In addition, a multi-scale extraction module is designed to capture the transition information. It consists of multiple convolution layers with different receptive fields for capturing multi-scale transition information. At last, a two-level attention module is used to adaptively capture valuable information for ECG biometrics. DMFUDM can obtain the average subject recognition rates of 99.76%, 98.31%, 98.97% and 98.87% on four databases, respectively, and experiment results show that it performs competitively with state-of-the-art methods on all four databases. [ABSTRACT FROM AUTHOR]

We propose a multiband asymmetric acoustic absorption and reflection system constructed from a waveguide and multi-order resonators with different radiant modes. Theoretical and experimental results confirm that the coupling of the dark and bright modes at each resonant frequency enables multiband high-efficiency absorption requiring only two functional units. More interestingly, we demonstrate a hybrid multiband asymmetric system based on customized multi-mode pairs. One side of the hybrid multiband system almost completely absorbs the lower frequency incident sound waves while reflecting the higher frequency ones; conversely, the other side effectively reflects the lower frequency ones and absorbs the higher frequency ones. Our design showcases the flexibility of customized multiband asymmetric absorption and also provides an approach for the design of bidirectional wave-manipulation devices. [ABSTRACT FROM AUTHOR]

The performance improvement using alumina thin film on a dual microchannel plate (MCP) detector for single electron counting was investigated. The alumina thin film was coated on all surfaces of the MCPs by atomic layer deposition method. It was found that the gain, the single electron resolution and the peak-to-valley ratio of the dual MCP detector were significantly enhanced by coating the alumina thin film. The optimum operating conditions of the new dual MCP detector have been studied. [ABSTRACT FROM AUTHOR]

Background: The receptor-like cytoplasmic kinases subfamily VII (RLCK-VII) is critical in regulating plant growth, development, and pattern-triggered immunity. However, a comprehensive exploration of these genes in the allotetraploid Gossypium hirsutum is still lacking. This study aimed to identify RLCK-VII genes in G. hirsutum and investigate their evolutionary history, structural features, expression patterns, and role in plant defense. Results: Seventy-two RLCK-VII genes in the G. hirsutum genome were unveiled and classified into nine groups following their phylogenetic analysis with Arabidopsis thaliana. Group VII-1 was the largest, accounting for 28%, while Groups VII-2 and VII-3 had only one member each. The analysis using MCScanX revealed that these 72 genes formed 166 collinear gene pairs and were resided on 26 chromosomes of G. hirsutum, suggesting that they were derived from whole genome segmental duplication events. Their calculated Ka/Ks values were below one, implying the occurrence of purification selection during the evolution and inhibition of gene function differentiation/loss. All members of the RLCK-VII subfamily possessed two conserved domains, PKinase-Tyr and PKinase, and several conserved PBS1 kinase subdomains, individually included in one of the ten motifs identified using MEME. The RNA-Seq results showed that RLCK-VII genes exhibited different spatiotemporal expression, indicating their involvement in cotton growth, development, and defense responses to Verticillium dahliae. The transcription patterns of RLCK-VII genes found by RNA-Seq were further validated using qRT-PCR assays after inoculating “20B12” (cotton cultivar) with “V991” (V. dahliae). The virus-induced gene silencing (VIGS) assays uncovered that two RLCK-VII genes (Gohir.A13G227248 and Gohir.A10G219900) were essential to G. hirsutum resistance to Verticillium wilt. Conclusions: These observations offer valuable insight into the attributes and roles of RLCK-VII genes in G. hirsutum, potentially enable the breeding of new cotton cultivars with enhanced resistance to Verticillium wilt. [ABSTRACT FROM AUTHOR]

The gain, pulse height resolution and peak-to-valley ratio of single electrons detected by using a Chevron configured Microchannel Plate (MCP) assembly are studied. The two MCPs are separated by a 280 µm gap and are biased by four electrodes. The purpose of the study is to determine the optimum bias voltage arrangements for single electron counting. By comparing the results of various bias voltage combinations, we conclude that good performance for the electron counting can be achieved by operating the MCP assembly in saturation mode. In addition, by applying a small reverse bias voltage across the gap while adjusting the bias voltages of the MCPs, optimum performance of electron counting can be obtained. [ABSTRACT FROM AUTHOR]

Occluded person re-identification (ReID) is a challenging task as the body is partially occluded by obstacles in crowd scenarios. Many previous studies employed an attention mechanism to focus on fine-grained local information with conventional likelihood while ignoring the inherent causality between the final prediction results and attention, especially occluded person always possesses biased clues. To address this problem, we propose a Pose-Guided Multi-Attention Network (PGMA-Net) for occluded person ReID in an end-to-end manner. PGMA-Net contains two main novel components: Pose-Guided Counterfactual Inference Branch (PGCIB) and Striped- and Patched-Attention Module (SPAM). The PGCIB jointly explores the causality between the predicted identities and input clues to alleviate the negative effects brought by occluded bias. Specifically, the counterfactual inference can directly guide the attention learning process via the counterfactual intervention. The SPAM generates a set of attention vectors for storing part prototypes over multiple rounds of attention. We empirically demonstrate that PGMA-Net can improve the recognition in both occluded and non-occluded ReID. With the above designs, our framework achieves 52.2% in mAP and 62.0% in top-1 on the Occluded-DukeMTMC dataset, surpassing the baseline by a large margin. This paper proposes a Pose-Guided Multi-Attention Network (PGMA-Net) for occluded person ReID in an end-to-end manner. PGMA-Net contains two main novel components: Pose-Guided Counterfactual Inference Branch (PGCIB) and Stripedand Patched-Attention Module (SPAM). The PGCIB jointly explores the causality between the predicted identities and input clues to alleviate the negative effects brought by occluded bias. Specifically, the counterfactual inference can directly guide the attention learning process via the counterfactual intervention. The SPAM generates a set of attention vectors for storing part prototypes over multiple rounds of attention. We empirically demonstrate that PGMA-Net can improve the recognition in both occluded and non-occluded ReID. [Display omitted] • Pose-Guided Multi-Attention Network is proposed. • PGCIB extracts discriminative features. • SPAM forms part groups. [ABSTRACT FROM AUTHOR]

The flexible job shop scheduling problem (FJSSP) is a practical extension of classical job shop scheduling problem that is known to be NP-hard. In this paper, an effective modified biogeography-based optimization (MBBO) algorithm with machine-based shifting is proposed to solve FJSSP with makespan minimization. The MBBO attaches great importance to the balance between exploration and exploitation. At the initialization stage, different strategies which correspond to two-vector representation are proposed to generate the initial habitats. At global phase, different migration and mutation operators are properly designed. At local phase, a machine-based shifting decoding strategy and a local search based on insertion to the habitat with best makespan are introduced to enhance the exploitation ability. A series of experiments on two well-known benchmark instances are performed. The comparisons between MBBO and other famous algorithms as well as BBO variants prove the effectiveness and efficiency of MBBO in solving FJSSP. [ABSTRACT FROM AUTHOR]

Acoustic metamaterials have provided a versatile platform to explore more degrees of freedom for tunable topological wave manipulation. Recently, extended topological interface modes (ETIMs) with heterostructure have been proposed to extend the spatial degree of freedom. However, the absence of frequency tunability still restricts the application of the wave transports of ETIMs. Here, we propose a one-dimensional piezoelectric topological phononic crystal (PTPC) with electrically tunable working frequency by introducing external capacitor circuit. With the bandgap frequency actively controlled by appropriately tuning the capacitances, we construct the heterostructured PTPCs possessing high-energy-capacity ETIMs with electrically tunable working frequency range and bandwidth. This work paves the way to wide engineering applications on acoustic sensing enhancement, nondestructive testing, energy harvesting, information processing, and reconfigurable topological wave transports. [ABSTRACT FROM AUTHOR]

Porous materials with corrugated surfaces are widely used in the field of noise control, as they can effectively convert sound energy into heat resulting in sound absorption. It is important to predict the absorption coefficients of sound-absorbing devices for the design of appropriate shape and size. In this study, a semi-analytic method of layered rigorous coupled-wave analysis (LRCWA) is proposed to predict the absorption of nonplanar periodic materials. Starting from the division of corrugated surfaces into multiple layers, we process the sound behavior in each layer as in a rectangular periodic modulation structure. By connecting the interlayer boundary continuity conditions, the acoustic coupling equation of the whole structure can be established. The effectiveness and practicability of the LRCWA method is validated based on the comparisons with the experimental data and the simulation of finite element method. Besides the absorption coefficient that is mainly discussed in this work, the proposed method is universal in analyzing the physical properties of nonplanar periodic structures, which can greatly accelerate the delicate design and optimization of such structures. [ABSTRACT FROM AUTHOR]

Low Gain Avalanche Detectors (LGAD) are silicon particle sensors with intrinsic gain through a thin p-type multiplication layer inserted between n-type implant and p-type bulk. The first prototype of LGAD sensors in China have been developed at the Institute of High Energy Physics (IHEP) of Chinese Academic Sciences and the Novel Device Laboratory (NDL) of Beijing Normal University. With an active thickness of 33 μ m, good breakdown performance, gain > 10, these sensors have reached jitter contribution of 10 ps to timing resolution with laser tests. [ABSTRACT FROM AUTHOR]

In this work, we propose a method for regulating topological states in acoustic systems by introducing airflow circulation. Composed of hollow rings linked with subwavelength rectangular waveguides, the proposed acoustic topological meta-crystals support multi-dimensional boundary states where the corner states merge into the edge ones. With the airflow introduced, the corner states separate from the edge states. We give the relationship between the frequency of the corner state and the speed of airflow and test the result by calculating eigenmodes of the supercell and finite lattice. Simulations for the acoustic field excited by a point source in a finite lattice also agree the relationship we give. The introduction of airflow in a topological system provides a method for manual control of the topological corner states. [ABSTRACT FROM AUTHOR]

Efficient acoustic communication across the water–air interface has always been expected in the field of ocean exploration. However, the existing research works are mainly concentrated on the narrow-band transmission based on resonance, which greatly limits the transmission capacity and efficiency. Here, we combined air-based and water-based metafluids to realize an exponential gradient impedance matching layer for broadband water–air sound transmission. By cooperatively adjusting the sound velocity and thickness in the matching layers, we modulated the required acoustic parameters of each layer into a reasonable range, which can be conveniently achieved by the proposed metafluids. A matching layer sample was constructed and validated in a water tank. Experimental results show that the proposed matching layer can achieve an average sound energy transmission enhancement above 16.7 dB from 880 to 1760 Hz across the water–air interface. A water–air acoustic communication scene was further experimentally demonstrated through transmitting a multicolor picture from air to water, which shows extremely high communication capacity and accuracy. Our work is promising for more applications based on water-air transmission and opens an avenue to the design and implementation of the extreme impedance matching case. [ABSTRACT FROM AUTHOR]

The acoustic artificial structures with tunable parameters have attracted much research interest in these days. In this paper, we present a tunable composite waveguide based on the piezoelectric phononic crystal shunted by an inductor circuit. A pass band based on local resonance will emerge in the complete band gap through modulating the shunted inductor circuit. This local-resonant pass band can be used to realize a waveguide. Both the work frequency and the shape of this waveguide can be tuned simultaneously by modulating the inductance and the space distribution of the external inductor circuit. For the excellent tunable ability, the proposed tunable composite waveguide could be useful in elastic wave sensors and frequency filters. [ABSTRACT FROM AUTHOR]

[Display omitted] [ABSTRACT FROM AUTHOR]

Gossypium hirsutum is an important source of natural textile fibers. Gossypol, which is a sesquiterpenoid compound mainly existing in the cotton pigment glands, can facilitate resistance to the stress from diseases and pests. The level of gossypol in the cotton is positively correlated to the quantity of pigment glands. However, the underlying regulatory mechanisms of gossypol synthesis and gland morphogenesis are still poorly understood, especially from a transcriptional perspective. The transcripts of young leaves and ovules at 30 DPA of the glanded plants and glandless plants were studied by RNA-Seq and 865 million clean reads were obtained. A total of 34,426 differentially expressed genes (DEGs) were identified through comparative transcriptome analysis. Genes related to gossypol synthesis or gland morphogenesis displayed significant differential expression between the two cultivars. Functional annotation revealed that the candidate genes related to catalytic activity, the biosynthesis of secondary metabolites, and biomolecular decomposition processes. Our work herein unveiled several potential candidate genes related to gossypol synthesis or gland morphogenesis and may provide useful clues for a breeding program of cotton cultivars with low cottonseed gossypol contents. [ABSTRACT FROM AUTHOR]

Pure magnesium (MgO) and zinc oxide doped with aluminum oxide (Zn 0.8 Al 0.2 O) were prepared via atomic layer deposition. We have studied the structure and band gap of bulk Zn 0.8 Al 0.2 O material by X-ray diffractometer (XRD) and Tauc method, and the band offsets and alignment of atomic layer deposited MgO/Zn 0.8 Al 0.2 O heterointerface were investigated systematically using X-ray photoelectron spectroscopy (XPS) in this study. Different methodologies, such as neutralizing electron gun, the use of C 1 s peak recalibration and zero charging method, were applied to recover the actual position of the core levels in insulator materials which were easily influenced by differential charging phenomena. Schematic band alignment diagram, valence band offset (Δ E V ) and conduction band offset (Δ E C ) for the interface of the MgO/Zn 0.8 Al 0.2 O heterostructure have been constructed. An accurate value of Δ E V = 0.72 ± 0.11 eV was obtained from various combinations of core levels of heterojunction with varied MgO thickness. Given the experimental band gaps of 7.83 eV for MgO and 5.29 eV for Zn 0.8 Al 0.2 O, a type-II heterojunction with a Δ E C of 3.26 ± 0.11 eV was found. Band offsets and alignment studies of these heterojunctions are important for gaining deep consideration to the design of various optoelectronic devices based on such heterointerface. [ABSTRACT FROM AUTHOR]

Dietary deficiency of selenium (Se) is a global health threat related to low Se concentrations in crops. Southern China has abundant Se-rich land resources, but the cadmium (Cd) pollution problem is prominent, which may lead to Cd exceeding the safety standard in Se-rich crops. Therefore, it is important to delineate Se-rich land without Cd pollution in order to develop green Se-rich agriculture. Based on soil/sediment geochemical survey data covering 2.3 million km2 of southern China, this study analysed the concentration and spatial distribution of Se and Cd, discussed their enrichment mechanisms and proposed suggestions for the safe use of Se-rich land. The results showed that the soil/sediments in southern China were significantly enriched in Se and Cd, and the median values were 0.31 mg·kg−1 and 221 μg·kg−1, which were 1.8 times and 2.5 times the national soil background values, respectively. In addition, a significant positive correlation was observed between Se and Cd, indicating that Cd contamination in Se-rich soils frequently exceeded the pollution limit. According to statistics, Se-rich land accounted for 32.13 % of southern China. However, due to the co-enrichment of Se and Cd, areas without Cd pollution accounted for only one-third of the total Se-rich area. In particular, the areas with co-enrichment of Se Cd are primarily distributed in Yunnan, Guizhou, Guangxi, western Hubei, northwestern Zhejiang, western Hunan, southern Hunan and northern Guangdong. The enrichment of Se is predominantly associated with parent rocks (black and carbonate rocks). At the same time, the enrichment of Cd is influenced by the parent rocks and Pb Zn mineralisation and mining activities. Three recommendations for managing Se-rich land were proposed: imposing restrictions on the utilisation of heavily contaminated Se-rich land for agricultural production, adopting a rational approach towards utilising lightly polluted Se-rich land and actively promoting the development of Se-rich agriculture in uncontaminated Se-rich areas. In the future, it is necessary to develop technologies that simultaneously enhance Se absorption while inhibiting Cd absorption in order to safely exploit Se-rich lands affected by Cd pollution. • Se and Cd are significantly enriched in the soil/sediments in southern China. • There is a significant positive correlation between Se and Cd. • The co-enrichment of Se and Cd is mainly related to the parent rocks and mining activities. • Three suggestions for the management of Se-rich land are put forward. [ABSTRACT FROM AUTHOR]

• A new and efficient cationic orange-red Ir(III) complex is rationally designed and synthesized. • The complex is used to fabricate high-efficiency monochromatic OLED by solution process. • The maximum EQE of the device is up to 10.20%, which is the highest value among the solution-processed devices based on ionic phosphorescent Ir(III) complexes. A new and efficient ionic orange-red Ir(III) complex is rationally designed by utilizing 2-(4-chloro-3-(trifluoromethyl)phenyl)-4-methylquinoline and a large conjugated 2,2′-biquinoline as main ligand and ancillary ligand, respectively. The complex shows bright phosphorescence peaking at 583 and 626 nm (shoulder) with high absolute phosphorescent quantum efficiency of 81.3% and moderate emission lifetime of 1.54 μ s in dichloromethane solution, which is suitable for fabricating high-performance solution-processed organic light-emitting diode. The device based on this ionic complex exhibits excellent electroluminescence performance, with the maximum luminance, external quantum efficiency, current efficiency, and power efficiency of up to 1209 cd/m2, 10.20%, 21.9 cd/A and 9.57 lm/W, respectively, thereby demonstrating that this new cationic Ir(III) complex possesses tremendous potentials for the future solution-processed electroluminescence. [Display omitted]. [ABSTRACT FROM AUTHOR]

Two new and efficient cationic yellow-emissive Ir (III) complexes (Ir1 and Ir2) are rationally designed by using 2-(4-chloro-3-(trifluoromethyl)phenyl)-4-methylquinoline as the main ligand, and, respectively, 4,4′-dimethyl-2,2′-bipyridyl and 4,4′-dimethoxy-2,2′-bipyridyl as the ancillary ligands. Both complexes show enhanced phosphorescence (546 nm with 572 nm as shoulder and high phosphorescent quantum efficiency in solution, which is in favor of efficient solution-processed phosphorescent organic light-emitting diodes. Compared with Ir2, the Ir1-based device displays excellent device performance, with maximum external quantum efficiency, current efficiency, and power efficiency of up to 7.92%, 26.32 cd/A and 15.31 lm/W, respectively, thus proving that the two new ionic Ir (III) complexes exhibit great potential for future solution-processed electroluminescence. [ABSTRACT FROM AUTHOR]

Existing word embeddings learning algorithms only employ the contexts of words, but different text documents use words and their relevant parts of speech very differently. Based on the preceding assumption, in order to obtain appropriate word embeddings and further improve the effect of text classification, this paper studies in depth a representation of words combined with their parts of speech. First, using the parts of speech and context of words, a more expressive word embeddings can be obtained. Further, to improve the efficiency of look‐up tables, we construct a two‐dimensional table that is in the format to represent words in text documents. Finally, the two‐dimensional table and a Bayesian theorem are used for text classification. Experimental results show that our model has achieved more desirable results on standard data sets. And it has more preferable versatility and portability than alternative models. [ABSTRACT FROM AUTHOR]

Conventional approaches to sound localization and separation are based on microphone arrays in artificial systems. Inspired by the selective perception of the human auditory system, a multisource listening system which can separate simultaneous overlapping sounds and localize the sound sources in 3D space, using only a single microphone with a metamaterial enclosure is designed. The enclosure modifies the frequency response of the microphone in a direction‐dependent manner by giving each direction a characteristic signature. Thus, the information about the location and the audio content of sound sources can be experimentally reconstructed from the modulated mixed signals using a compressive sensing algorithm. Due to the low computational complexity of the proposed reconstruction algorithm, the designed system can also be applied in source identification and tracking. The effectiveness of the system in multiple real‐life scenarios is evaluated through multiple random listening tests. The proposed metamaterial‐based single‐sensor listening system opens a new way of sound localization and separation, which can be applied to intelligent scene monitoring and robot audition. [ABSTRACT FROM AUTHOR]

[Display omitted] • An acoustic metafluid made of hollow regular polygons immersed in water is proposed, which can realize independent manipulation of mass density and bulk modulus. • A theory model is established to accurately calculate the effective acoustic parameters of the proposed metafluid. • The underwater impedance-matched gradient index lens and carpet cloak have been designed and experimentally demonstrated based on the proposed metafluid. Tuning the mass density and bulk modulus independently is the key to manipulate the propagation of sound wave. Acoustic metamaterials provide a feasible method to realize various acoustic parameters. However, the relevant studies are mainly concentrated in air, and the huge impedance difference makes it difficult to directly extend these airborne structures to underwater application. Here, we propose a metafluid to realize independent manipulation of the mass density and bulk modulus underwater. The metafluid is composed of hollow regular polygons immersed in the water. By adjusting the side number of the hollow regular polygons and choosing proper materials, the effective mass density and bulk modulus of the metafluid could be modulated independently. Based on the flexible adjustment method, metafluids with same impedance but different sound velocities are designed and used to realize an underwater impedance-matched gradient index lens. In addition, by combining the proposed metafluid with other artificial structures, acoustic parameters with great anisotropy can be achieved, which is exemplified by the design and demonstration of an impedance-matched underwater acoustic carpet cloak. This work can expand the practicability of underwater metamaterials and pave the way for future potential engineering applications in the practical underwater devices. [ABSTRACT FROM AUTHOR]

Abstract The Jiangmen Underground Neutrino Observatory (JUNO) is a 20 kton multi-purpose underground liquid scintillator detector designed to determine the neutrino mass hierarchy, and measure the neutrino oscillation parameters. The excellent energy resolution and the large fiducial volume anticipated for the JUNO detector offer exciting opportunities for addressing many important topics in neutrino and astro-particle physics. Linear alkylbenzene (LAB) will be used as the solvent for the liquid scintillation system in the central detector of JUNO. The light attenuation lengths of LAB should be comparable to the diameter of the JUNO detector, hence very good optical transparency is required. However, the presence of impurities in the LAB renders an intrinsic limit for the transparency. This work focuses on the study of the effects of organic impurities in the LAB, and their light absorption properties particularly in the wavelength region of 350–450 nm. We have prepared LAB samples and measured their light attenuation lengths. These samples were then analyzed by a gas chromatography–mass spectrometry (GC–MS), and the structure formulas of organic impurities were ascertained. These impurities' light-absorption properties in the wavelength region of 350–450 nm were theoretically investigated with time-dependent density functional theory (TDDFT). The overall optical transparency of the LAB samples was studied, which would further help us in promoting the LAB preparation technique for the mass production thereof, thus improving the transparency of the high quality LAB samples in the near future. [ABSTRACT FROM AUTHOR]

We present the design, architecture, and detailed performance of a three-dimensional (3D) underwater acoustic carpet cloak (UACC). The proposed system of the 3D UACC is an octahedral pyramid, which is composed of periodical steel strips. This underwater acoustic device, placed over the target to hide, is able to manipulate the scattered wavefront to mimic a reflecting plane. The effectiveness of the prototype is experimentally demonstrated in an anechoic tank. The measured acoustic pressure distributions show that the 3D UACC can work in all directions in a wide frequency range. This experimental verification of 3D device paves the way for guidelines on future practical applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Dispersion relation in honeycomb structure is calculated more accurately by taking advantage of the space periodicity of the core. • A flexural wave band gap is discovered and verified in the intact area of the honeycomb structure. • A new nondestructive method for detecting the debonding defect is proposed by using the band gap feature and the corresponding detection device is developed. Honeycomb structure is increasingly applied in various fields due to its high strength-to-weight ratios. However, due to the complex wave field in the structure, how to detect the defect accurately and efficiently is always an important problem. In this article, the honeycomb core, instead of being an obstacle to obtain the dispersion characteristic for traditional guided wave method, provides a way to calculate the wave propagation by being taken advantage of its space periodicity. By analyzing, simulating, and experimental testing, it is exhibited that there is a gap in the dispersion relation of the honeycomb structure which caused by the interaction between the local resonant vibration of the skins and the bending vibration of the structure. This gap disappears in the debonding area. Then a nondestructive testing method is proposed to detect the debonding defects based on this feature. The detection results of this proposed method are accord with that of ultrasonic C-scan. The results indicate that this method is suitable for detecting and locating the debonding defects in honeycomb structure with quite high sensitivity and efficiency, and it has a great potential to be widely used in filed test of honeycomb structure for its high feasibility. [ABSTRACT FROM AUTHOR]