Analysis, realization and experiment of Lamb wave phased arrays for damage detection and imaging in carbon composite structures

Phased array theory is utilized in the unmanned aerial vehicle (UAV) wing box to identify the damage in the structure. The phased array theory has been adapted to Lamb wave propagation to improve the detection ability of local defects in the complex composite structure. The validity of the proposed method is demonstrated by experimental research in which input signals exerted at piezoelectric (PZT) actuators/sensors on the UAV wing box are successfully reconstructed by using the phased array method. The recognition result is shown on a mapped image. The original mapped image uses gray level transformation method to enhance the image identifiable degrees. And the time of arrival of the Lamb wave signal is calculated by Shannon Wavelet. The experiments is done on carbon composite structure using one dimensional PZT linear sensors array exemplifies that phased array theory well utilized in scanning and detecting the damage and the screw loosening in the structure. The original image is processed by the gray level transformation to improve the contrast and the recognition

Interaction of a symmetrical α,α',δ,δ'-Tetramethyl-cucurbit[6]uril with Ln³⁺ : potential applications for isolation of lanthanides

The interaction of a symmetrical α,α′,δ,δ′-tetramethyl-cucurbit[6]uril (TMeQ[6]) with a series of lanthanide cations (Ln³⁺) was investigated in neutral water and in acidic solution. Analysis by single crystal X-ray diffraction revealed that different isomorphous families formed under different synthetic conditions. Such differences in the interaction between TMeQ[6] and Ln³⁺ could potentially be used for isolating heavier Ln³⁺ from their lighter counterparts in neutral solution, and lighter lanthanide cations from their heavier counterparts in acidic solution

Scaling of global input–output networks

Examining scaling patterns of networks can help understand how structural features relate to the behavior of the networks. Input–output networks consist of industries as nodes and inter-industrial exchanges of products as links. Previous studies consider limited measures for node strengths and link weights, and also ignore the impact of dataset choice. We consider a comprehensive set of indicators in this study that are important in economic analysis, and also examine the impact of dataset choice, by studying input–output networks in individual countries and the entire world. Results show that Burr, Log-Logistic, Log-normal, and Weibull distributions can better describe scaling patterns of global input–output networks. We also find that dataset choice has limited impacts on the observed scaling patterns. Our findings can help examine the quality of economic statistics, estimate missing data in economic statistics, and identify key nodes and links in input–output networks to support economic policymaking

Design and Evaluation of a Wireless Sensor Network Based Aircraft Strength Testing System

The verification of aerospace structures, including full-scale fatigue and static test programs, is essential for structure strength design and evaluation. However, the current overall ground strength testing systems employ a large number of wires for communication among sensors and data acquisition facilities. The centralized data processing makes test programs lack efficiency and intelligence. Wireless sensor network (WSN) technology might be expected to address the limitations of cable-based aeronautical ground testing systems. This paper presents a wireless sensor network based aircraft strength testing (AST) system design and its evaluation on a real aircraft specimen. In this paper, a miniature, high-precision, and shock-proof wireless sensor node is designed for multi-channel strain gauge signal conditioning and monitoring. A cluster-star network topology protocol and application layer interface are designed in detail. To verify the functionality of the designed wireless sensor network for strength testing capability, a multi-point WSN based AST system is developed for static testing of a real aircraft undercarriage. Based on the designed wireless sensor nodes, the wireless sensor network is deployed to gather, process, and transmit strain gauge signals and monitor results under different static test loads. This paper shows the efficiency of the wireless sensor network based AST system, compared to a conventional AST system

Characteristics of polycyclic aromatic hydrocarbons in PM2.5 emitted from different cooking activities in China

Nineteen polycyclic aromatic hydrocarbons (PAHs) in PM2.5 emitted from five different cooking activities were characterized, and their influencing factors were determined. The total quantified particle-bounded PAH concentrations (Sigma PAHs) in the airs from the cooking activities were 4.2-36.5-fold higher than those in corresponding backgrounds. The highest I PAHs pound were seen in cafeteria frying (783 +/- 499 ng/m(3)), followed by meat roasting (420 +/- 191 ng/m(3)), fish roasting (210 +/- 105 ng/m(3)), snack-street boiling (202 +/- 230 ng/m(3)), and cafeteria boiling (150 +/- 65 ng/m(3)). The main influencing factors on the PAH emissions were cooking methods, fat contents in raw materials, and oil consumptions. Four- to six-ringed PAHs had the highest contributions to the Sigma PAHs (avg. 87.5%). Diagnostic ratios of individual PAH were similar between the two charbroiling and other three conventional Chinese cooking methods, respectively, demonstrating the dominance of cooking methods in the PAH emissions. Remarkably high benzo(b)fluoranthene/benzo(k)fluoranthene (BbF/BkF) ratio (8.31) was seen in the snack-street boiling, attributed to the coal combustion as cooking fuel. Both fluoranthene/(fluoranthene + pyrene) [FLT/(FLT + PYR)] and benzo(a)anthracene/(benzo(a)anthracene + chrysene) [BaA/(BaA + CHR)] ratios were higher for the oil-based cooking than those from the water-based ones. In addition, two ratios of indeno(1,2,3-cd)pyrene/(indeno(1,2,3-cd)pyrene + benzo(g,h,i)perylene) [IPY/(IPY + BPE)] and benzo(a)pyrene/(benzo(a)pyrene + benzo(g,h,i)perylene) [BaP/(BaP + BPE)] were higher for two charbroiling than the three conventional Chinese cooking methods. The characterization work in this study is particularly important since cooking is a potential contributor of atmospheric PAHs in urban China. Carcinogenic potencies of PAHs were assessed by comparison with the air quality guideline and health risk estimation. The BaP and BaP equivalent were higher for the oil-based than the water-based cooking activities

NewsClaims: A New Benchmark for Claim Detection from News with Attribute Knowledge

Claim detection and verification are crucial for news understanding and have emerged as promising technologies for mitigating news misinformation. However, most existing work has focused on claim sentence analysis while overlooking crucial background attributes (e.g., claimer, claim objects). In this work, we present NewsClaims, a new benchmark for knowledge-aware claim detection in the news domain. We redefine the claim detection problem to include extraction of additional background attributes related to each claim and release 889 claims annotated over 143 news articles. NewsClaims aims to benchmark claim detection systems in emerging scenarios, comprising unseen topics with little or no training data. To this end, we provide a comprehensive evaluation of zero-shot and prompt-based baselines for NewsClaims.Comment: Preprin

Qualitative and quantitative analysis of catechin and quercetin in flavonoids extracted from Rosa roxburghii Tratt

Purpose: To perform a qualitative and quantitative analysis of catechin and quercetin in flavonoids extracted from Rosa roxburghii Tratt.Methods: Total flavonoids were determined using ultraviolet spectrophotometry (UV) at 500 nm. The optimal gradient program started with 15 % methanol and was kept within a period of 0 – 20 min, while 25 % methanol was kept within 20 – 33 min. Subsequently, the concentration of methanol was reduced to 15 % and was held for 10 min until the next injection. Mass spectrometry spray voltage was 4,000 V, ionization temperature 350 °C, atomizer pressure 35 psi, nitrogen flow rate 8 L/min, and mass scan range 200 – 800 m/z. The detection wavelength used for catechin and quercetin was 270 and 368 nm, respectively.Results: Based on the UV results, Rosa roxburghii Tratt content was 73.85 %, which is in agreement with the national standard. Liquid chromatography-mass spectrometry (LC-MS) results indicate that Rosa roxburghii Tratt flavonoids contained quercetin, 34.26 %, with relative standard deviation (RSD) of 2.88 % and catechin content of 2.97 % with RSD of 1.49 %.Conclusion: The proposed measurement method for determining the content of flavonoids in Rosa roxburghii Tratt has the advantage of simplicity, feasibility, good repeatability, and rapid and accurate analysis.Keywords: Rosa roxburghii Tratt, Flavonoids, Catechin, Querceti

Scalable Method for Eliminating Residual ZZZZ Interaction between Superconducting Qubits

Unwanted $ZZ$ interaction is a quantum-mechanical crosstalk phenomenon which correlates qubit dynamics and is ubiquitous in superconducting qubit systems. It adversely affects the quality of quantum operations and can be detrimental in scalable quantum information processing. Here we propose and experimentally demonstrate a practically extensible approach for complete cancellation of residual $ZZ$ interaction between fixed-frequency transmon qubits, which are known for long coherence and simple control. We apply to the intermediate coupler that connects the qubits a weak microwave drive at a properly chosen frequency in order to noninvasively induce an ac Stark shift for $ZZ$ cancellation. We verify the cancellation performance by measuring vanishing two-qubit entangling phases and $ZZ$ correlations. In addition, we implement a randomized benchmarking experiment to extract the idling gate fidelity which shows good agreement with the coherence limit, demonstrating the effectiveness of $ZZ$ cancellation. Our method allows independent addressability of each qubit-qubit connection, and is applicable to both nontunable and tunable couplers, promising better compatibility with future large-scale quantum processors.Comment: Main text: 6 pages, 4 figures; Supplement: 7 pages, 6 figure