Measurement of Ultrasonic Nonlinear Parameter by Using Electromagnetic Acoustic Transducer

The nonlinear ultrasonic technology is generally known as an effective method for the microcrack detection. However, most of the previous experimental studies were limited by a contact nonlinearity method. since measurement by the contact method is affected by the coupling conditions, additional nonlinear coefficient are lead into the measurement. This research presents a novel technique for nonlinear ultrasonic wave measurements that uses a non-contact, electromagnetic ultrasonic transducer (EMAT); and is much more efficient than piezoelectric-based detection. And for a better understanding and a more in-depth analysis of the macroscopic nonlinear behavior of microcrack, the developed FEM modeling approach is built to simulate microcrack induced nonlinearities manifested in ultrasonic waves and analyzed experimentally. The 2D finite element simulation is implemented in the multi-physics module of COMSOL, and the performance between Rayleigh wave EMAT and microcrack includes transduction process that the electromagnetic field and mechanical field are coupled together by electromagnetic force, wave propagation process, nonlinear acoustic response process as shown in Figure.1.This study has yielded a quantitative characterization strategy for microcrack using EMAT, facilitating deployment of structural health monitoring by noncontact electromagnetic nondestructive testing

Finite Element Analysis for the Inhibition of EMAT Lamb Waves Multimode

The guided waves, especially Lamb waves, due to its longer propagation, lower loss and higher efficiency and sensitivity, are widely used in various kinds of thin layer structure test-ing (for example plates, pipelines and tanks). Electromagnetic ultrasonic Lamb waves testing combining the characteristics of Electromagnetic ultrasonic testing and guided waves, which has a better application prospect. Unfortunately, Lamb waves possess the multi-modes char-acteristic: several different modes propagate in the specimen simultaneous. Moreover, all of the modes of lamb waves are dispersive. Both make the received signals so complex and messy that the echo signals of the flaws might be difficult or even impossible to interpret in the practical application. In this paper, according to the characteristics of electromagnetic ul-trasonic excitation and combining with the structure of the double transducer and the method of phase cancellation [1,2], the characteristics of single lamb waves were studied by theory and simulation methods. The simulation results show that the structure of the double transducers can completely eliminates a mode and enhances another to excite single-mode. The single-mode exciting re-duces the difficulty of the subsequent signal analysis and processing, which provides reliable information for the practical application of detecting flaws. This work is supported by National Natural Science Foundation of China (51077036, 51207105, 51307043) and Natural Science Foundation of Hebei Province (E2016202260)

Growth and New Directions: CALA Academic Resources and Repository System

The Chinese American Librarians Association’s Academic Resources & Repository System (CALASYS) was established in 2013 and has been growing gradually ever since. To seek sustainable and greater growth in the future, the CALASYS 2019-2020 Committee reviewed previous efforts and explored new potentials in the repository’s content development, interface and functionality improvement and community engagement. This presentation will cover several issues that the Committee has addressed since its forming: developing new content for CALASYS such as a new top-level collection called ”Chinese Culture Heritage & Chinese Studies” and its children collections including the CALA Best Book Award Collection; starting or resuming testing on several Omeka plugins whose implementation would enhance the system’s functionality and performance significantly, such as Exhibit Builder, User Profile, Search by Metadata, CSS Editor and Geolocation; exploring other Omeka instances’ interfaces and improving the CALASYS’ appearance and presentation. This poster will also cover the continuing development of the CALA Archives, CALA Chapter Collections and CALA Member Scholarly Achievements collection, metadata editing and enhancement, statistics and usage of the repository, as well as involving students and CALA members in working with the repository. To develop an organization’s institutional repository is a long-term task, this presentation will conclude with a discussion of the lessons learned and strategies and tips on working with the repository for the committee members and the community

Opening CALASYS to All Members

Since the Chinese American Librarians Association’s Academic Resources and Repository System (CALASYS, https://ir.cala-web.org/) was initiated in 2013, its collections have grown gradually by way of the Committee’s curation and entries with occasional help from LIS students. In order to resolve the bottleneck problems, promote CALASYS and expand its content, the 2020-2021 CALASYS Committee has strongly pursued the idea of opening CALASYS to all of the CALA members. The Committee began to implement the author self-contribution plug-in in the CALASYS’ Omeka platform in 2020. This poster will focus on the implementation of the self-contribution plug-in. It will cover the main steps and tasks of the implementation, including making metadata contribution templates, selecting copyright options, establishing contributor verification, testing workflow and developing end-user guide and back-end management documentations. It will also address the Committee’s work on creating training materials on workflow and metadata and plans on providing training sessions online to the CALA community. It will include the CALASYS’ history, its main features, collections, and usage statistics as well. By opening CALASYS to all members, it is hoped that it will better achieve the CALA’s strategic plan of 2020-2025, “Make CALA’s impact on local, state, national, and international levels.” Meanwhile, the bottleneck problems will be resolved and CALASYS will continue to grow at a faster pace in a more inclusive direction. The accompanying video is also available at: https://youtu.be/q9g4SXsnuO0

Using 3D seismic exploration to detect ground fissure

   As a kind of supergene geological phenomenon, ground fissure has brought great inconvenience to human life. In addition, it also has a close relationship with earthquake. However, it is very difficult to ascertain the extension depth of ground fissure since its concealment and uncertainty. In this paper, 3D seismic exploration is used to detect ground fissure in Shanxi Province of China. Specific parameters for seismic data acquisition, processing and interpretation are analysed. Firstly, seismic data acquisition method and its corresponding parameters are discussed. Small dose explosive sources and high frequency geophones are used. Small trace interval and appropriate fold are also adopted. Secondly, seismic data processing is processed from shot record to seismic profile. Multi-domain loop iteration de-noising is used to get high signal-to-noise ratio data. Accurate near surface model, interactive iteration and residual static correction are used to eliminate the impact of low velocity zone and the static correction problem. Large common middle point bin and small velocity analysis interval are used for high accuracy velocity spectrum analysis. The mute parameter of stretching distortion and the migration aperture are researched for shallow ground fissure detection. Thirdly, seismic data interpretation is processed to get ground fissure distribution. Fault enhanced filter is used to improve the signal-to-noise ratio effectively and the chimney cube is used to identify ground fissure automatically. Thus, the specific 3D seismic exploration method used in this paper is suitable for ground fissure detection.Cited as: Shi, S., Liu, Z., Feng, J., Feng, G., Li, M. Using 3D seismic exploration to detect ground fissure. Advances in Geo-Energy Research, 2020, 4(1): 13-19, doi: 10.26804/ager.2020.01.0

Meta-analysis of effects of long-term exposure to PM2.5 on C-reactive protein levels

BackgroundFine particulate matter (PM2.5) is a serious air pollutant associated with elevated levels of C-reactive protein (CRP), an inflammatory indicator.ObjectiveTo assess the potential impacts of long-term exposure to PM2.5 on CRP levels based on previous epidemiological studies.MethodsPubMed, Embase, Web of Science, CNKI, and Wanfang databases were searched to screen the cohort studies published from January 1, 2000 to January 1, 2022 on the effects of long-term exposure to PM2.5 on CRP levels. "Fine Particulate Matter", "PM2.5", "Particulate Air Pollutants", "Ambient Particulate Matter", "CRP", "C-reactive Protein", and "High Sensitivity C-reactive Protein" in English or Chinese were the key words used in the search. The percentage change in CRP level per 10 μg·m−3 increase in PM2.5 concentration in each study was extracted, followed by meta-analysis, subgroup analysis, and sensitivity analysis.ResultsA total of 1241 articles were retrieved, and 7 articles were included. Random-effects models were used to merge the included data, and it was found that the percentage of CRP level increased by 10.41% (95%CI: 2.24%-18.57%, P<0.05), when PM2.5 concentration increased by 10 μg·m−3, І2=84.2%. The subgroup analysis conducted with grouping based on the annual mean concentration of PM2.5 long-term exposure showed that the intra-group heterogeneity was significantly reduced in the <15 μg·m−3 and the 15- μg·m−3 groups, and the subgroup forest analysis showed differences between the two groups. The results of sensitivity analysis showed that there was a high degree of heterogeneity among the 7 studies, and the 2 papers with the highest annual average PM2.5 concentration were the sources of heterogeneity. The Egger test and the funnel plot indicated that no obvious publication bias was found.ConclusionLong-term exposure to PM2.5 can raise levels of CRP in human body

Conservation and reintroduction of the rare and endangered orchid Paphiopedilum armeniacum

Paphiopedilum armeniacum is a rare and endangered lady’s slipper orchid in China. It is distributed around the mid-elevations of the Nu Mountains in southwest China. Due to over-harvest, habitat loss, and degradation, wild populations of P. armeniacum has declined drastically. A combination of approaches involving biotechnology, habitat restoration, and interspecific relationship reconstruction was used to carry out the reintroduction of the species. Integrated conservation program for this species included in-situ protection, ex-situ conservation, and reintroduction, which helped to rebuild a harmonious relationship between local farmers and P. armeniacum. The sustainable utilization of native plant resources in poor areas can promote regional sustainable development which is compatible with species protection

Genome-Wide Gene Expression Profiling of Nucleus Accumbens Neurons Projecting to Ventral Pallidum Using both Microarray and Transcriptome Sequencing

The cellular heterogeneity of brain poses a particularly thorny issue in genome-wide gene expression studies. Because laser capture microdissection (LCM) enables the precise extraction of a small area of tissue, we combined LCM with neuronal track tracing to collect nucleus accumbens shell neurons that project to ventral pallidum, which are of particular interest in the study of reward and addiction. Four independent biological samples of accumbens projection neurons were obtained. Approximately 500 pg of total RNA from each sample was then amplified linearly and subjected to Affymetrix microarray and Applied Biosystems sequencing by oligonucleotide ligation and detection (SOLiD) transcriptome sequencing (RNA-seq). A total of 375 million 50-bp reads were obtained from RNA-seq. Approximately 57% of these reads were mapped to the rat reference genome (Baylor 3.4/rn4). Approximately 11,000 unique RefSeq genes and 100,000 unique exons were identified from each sample. Of the unmapped reads, the quality scores were 4.74 ± 0.42 lower than the mapped reads. When RNA-seq and microarray data from the same samples were compared, Pearson correlations were between 0.764 and 0.798. The variances in data obtained for the four samples by microarray and RNA-seq were similar for medium to high abundance genes, but less among low abundance genes detected by microarray. Analysis of 34 genes by real-time polymerase chain reaction showed higher correlation with RNA-seq (0.66) than with microarray (0.46). Further analysis showed 20–30 million 50-bp reads are sufficient to provide estimates of gene expression levels comparable to those produced by microarray. In summary, this study showed that picogram quantities of total RNA obtained by LCM of ∼700 individual neurons is sufficient to take advantage of the benefits provided by the transcriptome sequencing technology, such as low background noise, high dynamic range, and high precision

Insolation driven biomagnetic response to the Holocene Warm Period in semi-arid East Asia

The Holocene Warm Period (HWP) provides valuable insights into the climate system and biotic responses to environmental variability and thus serves as an excellent analogue for future global climate changes. Here we document, for the first time, that warm and wet HWP conditions were highly favourable for magnetofossil proliferation in the semi-arid Asian interior. The pronounced increase of magnetofossil concentrations at ~9.8 ka and decrease at ~5.9 ka in Dali Lake coincided respectively with the onset and termination of the HWP, and are respectively linked to increased nutrient supply due to postglacial warming and poor nutrition due to drying at ~6 ka in the Asian interior. The two-stage transition at ~7.7 ka correlates well with increased organic carbon in middle HWP and suggests that improved climate conditions, leading to high quality nutrient influx, fostered magnetofossil proliferation. Our findings represent an excellent lake record in which magnetofossil abundance is, through nutrient availability, controlled by insolation driven climate changes.This research was supported by the NSFC grant 41330104 and the 973 program grant 2012CB821900. J.X. was supported by the 973 program grant 2010CB833400 and the NSFC grant 41130101. J.L. received support from the NSFC grant 41374004. C.D. acknowledges further support from the NSFC grant 40925012 and the CAS Bairen Program

A novel understanding of the normalized fatigue delamination model for composite multidirectional laminates

Normalized fatigue delamination models have been widely applied by researchers in the characterization of the fatigue delamination behavior of composite laminates. However, the inherent mechanism of this normalization method has not been explored. This study aims to present a physical understanding on the normalized fatigue delamination model from a viewpoint of energy. The fatigue delamination behavior is considered to be governed by the driving force and delamination resistance, and based on this principle the physical mechanism of the fatigue delamination is studied. A new physics-based normalized fatigue delamination model is proposed in this paper. In order to experimentally validate the proposed fatigue delamination model, mode I fatigue delamination tests are performed on double cantilever beam specimens to obtain the experimental data with different amounts of the fiber bridging. The results show that the normalized model is suitable to accurately characterize the fatigue delamination behavior of the composite laminates by using a single master curve. The master curve is finally employed as a standard approach to predict the fatigue results. Good agreement between the predicted and the experimental results is achieved, therefore it approves the applicability of the proposed fatigue delamination model in characterizing the fatigue delamination growth behavior