11,114 research outputs found
An energy-based coupling degradation propagation model and its application to aviation actuation system
No full textThe degradation of components in complex mechatronic systems involves multiple physical processes which will cause coupling interactions among nodes in the system. The interaction of nodes may be carried out not only by physical connections but also by the environment which cannot be described by single network using the traditional methods. In order to give out a unified model to quantitatively describe the coupling degradation spreading by both physical connections and environment, a novel Energy-Flow-Field Network (EFFN) and a coupling degradation model based on EFFN are proposed in this paper. The EFFN is driven by energy flow and the state transition of spatially related nodes is triggered by the dissipation energy. An application is conducted on aviation actuation system in which the degradation spreading by fluid-thermal-solid interaction is considered. The degradation path and the most probable fault reason can be obtained by combining the state transition and energy output of nodes, which is consistent with the given scenario
High time resolution optical/X-ray cross-correlations for X-ray binaries : anticorrelations and rapid variability
No full textUsing simultaneous observations in X-rays and optical, we have performed a homogeneous analysis of the cross-correlation behaviours of four X-ray binaries: SWIFT J1753.5-0127, GX339-4, Sco X-1 and CygX-2. With high-time-resolution observations using ULTRACAM and RXTE, we concentrate on the short time-scale, delta t < 20 s, variability in these sources. Here we present our data base of observations, with three simultaneous energy bands in both the optical and the X-ray, and multiple epochs of observation for each source, all with similar to second or better time resolution. For the first time, we include a dynamical cross-correlation analysis, i.e. an investigation of how the cross-correlation function changes within an observation. We describe a number of trends which emerge. We include the full data set of results, and pick a few striking relationships from among them for further discussion.
We find, that the surprising form of X-ray/optical cross-correlation functions, a positive correlation signal preceded by an anticorrelation signal, is seen in all the sources at least some of the time. Such behaviour suggests a mechanism other than reprocessing as being the dominant driver of the short-term variability in the optical emission. This behaviour appears more pronounced when the X-ray spectrum is hard. Furthermore, we find that the cross-correlation relationships themselves are not stable in time, but vary significantly in strength and form. This all hints at dynamic interactions between the emitting components which could be modelled through non-linear or differential relationships
Tubifex conicus He, Wang & Cui 2012
No full textTubifex conicus He, Wang & Cui, 2012 (Figs 7–8) Tubifex conicus He, Wang & Cui, 2012: 160 –162, Fig. 1. New material. IHB XZ20150602 a–e, 5 mature specimens, whole-mounted in Canada balsam, from Gyaring Co, preserved in IHB, CAS. Gyaring Co (30°58' 43″N, 88°28′04″E), a lake located in northern Tibet of China, ca. 4,648–4,659 m asl. Water depth 11–37 m, water temperature 6.3–8.9°C, pH 6.3–8.9, dissolved oxygen 7.3–7.7 mg / L, conductivity 323–329 µs/cm. Collected by Yongde Cui and Baoqiang Wang on 2 June 2015. Description. Length 6.1–11.6 mm, width at genital segments X–XI 0.28–0.42 mm. Segments 38–65. Prostomium obtuse. Clitellum inconspicuous. No coelomocytes. Dorsal chaetae (0) 1 hair and 1–4 bifids per bundle. Hairs serrate, posteriorly generally absent (Fig. 7A, B). Dorsal bifids pectinate, upper and lower tooth subequal, with 2–3 fine intermediate teeth (Fig. 7A). Ventral chaetae bifid, 3–4 per bundle anteriorly, 2 per bundle posteriorly, upper tooth slightly longer than lower, with (0) 1–2 fine intermediate teeth (Fig. 7C, D). Ventral chaetae in X present, unmodified. Ventral chaetae in XI absent. Male pores paired in line with ventral chaetae, middle to posterior of XI. Chloragogen cells from VI onwards. Male genitalia paired in X–XI. Sperm funnel cup-shaped, 20 µm long, 40 µm wide (Fig. 8A,B: sf). Vas deferens 400–560 µm long, 12–15 µm wide, nearly 3–4 times as long as atrium, ciliated throughout and entering atrium apically (Fig. 8A, B: vd). Atrium spindle-shaped, 120–160 µm long, maximally 32–40 µm wide (Fig. 8A, B: at). Ejaculatory duct present. Prostate gland solid, 80–84 µm long, 60–64 µm wide, attached to ental portion of atrium (Fig. 8A, B: pr). Penis inconspicuous, surrounded by cuticular, symmetrical and funnel-shaped penial sheath. Penial sheath 36–40 µm long, 48–56 µm wide at ental end (Fig. 8A, B, C: ps). Testes paired in X, immediately behind septum 9/10. Ovaries paired in XI, immediately behind septum 10/11. Spermathecae absent. Remarks. The main difference of our redescription from T. conicus as originally described (He et al. 2012) is the absence of spermathecae. However, after our reinvestigation of the type series (holotype and paratypes), we are sure that the testes of T. conicus were mistaken for spermathecae in the original description. Further slight differences between the descriptions concern thickness of atrial epithelium (thicker in the redescription) and penial sheaths (thicker in the original description). They may relate to the stage of maturity or to different modes of interpretation of observations. The size and shape of atria in the original observation and this research are about the same. Penial sheaths appear to have a thick cuticle laterally in the holotype, but when comparing type series and our material, we found no significant differences in penial sheath thickness. Distribution and habitat. Known from Yamdrok Yumco (Lake Yamzho Yumco), Gyaring Co, Chargut Co, Uruni Co, Chikui Co, Amdo Tsonak Co, Tibet, China. All these lakes are located at above 4,000 m asl in Tibet. Gyaring Co, the locality of present redescribed materials, is about 300 km from the holotype locality of T. conicus, Yamdrok Yumco. Freshwater and brackish water.Published as part of Cui, Yongde, 2017, Four species of Tubifex Lamarck (Annelida: Oligochaeta: Naididae) from Tibet, China, pp. 366-378 in Zootaxa 4320 (2) on pages 371-372, DOI: 10.11646/zootaxa.4320.2.10, http://zenodo.org/record/89195
Navigating the landscape of global sustainable livelihood research: past insights and future trajectory
No full textSustainable livelihoods (SL) have emerged as a crucial area of focus in global environmental change research, aligning with the Sustainable Development Goals (SDGs). This field is rapidly gaining prominence in sustainability science and has become one of the primary research paradigms. In our study, we conducted scientometrics analysis using the ISI Web of Science core collection database to examine research patterns and frontier areas in SL research. We selected 6441 papers and 265,759 references related to SL published from 1991 to 2020. To achieve this, we employed advanced quantitative analysis tools such as CiteSpace and VOSviewer to quantitatively analyze and visualize the evolution of literature in the SL research field. Our overarching objectives were to understand historical research characteristics, identify the knowledge base, and determine future research trends. The results revealed an exponential increase in SL research documentation since 1991, with the Consortium of International Agricultural Research Center (CGIAR) contributing the highest volume of research documents and citations. Key journals in this field included World Development, Global Environmental Change, Ecological Economics, and Ecology and Society. Notably, Singh RK and Shackleton CM emerged as prolific authors in SL research. Through our analysis, we identified six primary clusters of research areas: livelihoods, conservation, food security, management, climate change, and ecosystem services. Additionally, we found that tags such as rural household, agricultural intensification, cultural intensification, and livelihoods vulnerability remained relevant and represented active research hotspots. By analyzing keyword score relevance, we identified frontier areas in SL research, including mass tourism, solar home systems, artisanal and small-scale mining, forest quality, marine-protected areas, agricultural sustainability, sustainable rangeland management, and indigenous knowledge. These findings provide valuable insights to stakeholders regarding the historical, current, and future trends in SL research, offering strategic opportunities to enhance the sustainability of livelihoods for farmers and rural communities in alignment with the SDGs
DS_10.1177_0022034518782461 – Supplemental material for Defective NaCl Reabsorption in Salivary Glands of <i>Eda</i>-Null X-LHED Mice
No full textSupplemental material, DS_10.1177_0022034518782461 for Defective NaCl Reabsorption in Salivary Glands of Eda-Null X-LHED Mice by T. Mukaibo, T. Munemasa, C. Masaki, C.Y. Cui and J.E. Melvin in Journal of Dental Research</p
Mechanism of complexation of toxic arsenate, selenate, and molybdate with hydrotalcites
No full textWastewater from the uranium mining industry contains toxic arsenate (AsO43–), selenate (SeO42–), and molybdate (MoO42–) that can be removed by complexation with MgAlFe(III)CO3SO4 hydrotalcites, yet underlying mechanisms are poorly known. Here, we studied complexation by K–edge Extended X-ray Absorption Fine Structure Spectroscopy, Density Functional Theory, Powder X-ray Diffraction, and Infrared and Raman Spectroscopy. We found that single shell paths with a coordination number of 4 and bond lengths of As–O = 1.69 Å, Se–O = 1.65 Å and Mo–O = 1.76 Å were best fitted for As–MgAlFe, Se–MgAlFe, and Mo–MgAlFe hydrotalcites. We observed a single antisymmetric υ3 band with no splitting at 821 cm−1 for AsO43–, 856 cm−1 for SeO42–, and 852 cm−1 for MoO42–. In all cases, basal (d003) and interlayer (d006) spacings before and after anion adsorption varied by less than 0.1 Å. Therefore, our findings demonstrate that arsenate, selenate, molybdate form outer-sphere-like complexes with MgAlFe hydrotalcite, and that these complexes are surface-bound and not intercalated
Wood decay fungi: an analysis of worldwide research
No full textPurpose: Wood decay fungi are the only forms of life capable of degrading wood to its initial constituents, greatly contributing to the soil ecosystem. This study summarizes the current research status and development characteristics of global wood decay fungi research, in order to better understand their role in soils. Methods: A bibliometric analysis was applied to the literature from 1913 to 2020, based on data from the Web of Science (WOS) Core Collection. For this, various bibliometric analysis methods, R (Biblioshiny package), and VOSviewer were applied. Results: A total of 8089 documents in this field were identified in the WOS Core Collection. The annual number of publications tended to increase, with exponential growth after 2008. Researchers in this field were mainly concentrated in North Europe, the USA, and China. Biotechnology, applied microbiology, environmental sciences, and microbiology were the most popular WOS categories. Bioresource Technology and Applied Environmental Microbiology were the top two journals with the most citations. The top three authors with the most published papers were Dai YC, Martinez AT, and Cui BK. Co-occurrence analysis of author keywords identified six clusters, mainly divided into three categories: the classification and diversity, the degradation mechanisms, and the ecological functions of wood decay fungi. Clustering results further showed that the lignin degradation process and the application of wood decay fungi in industrial production and soil contamination remediation are current research hotspots. Conclusions: We present a comprehensive and systematic overview of research related to wood decay fungi and provide a deep perspective to understand the associated research progress. This is important for facilitating the development of a profound understanding of the contribution of wood decay fungi to soil systems and the degradation of soil contaminants.Full Tex
Managing multiple stressors for sustainable livelihoods in dryland ecosystems: Insights and entry points for resource management
No full textCommunities in dryland ecosystems face multiple stressors that threaten their livelihood resilience. While community resilience in socio-ecological systems is largely determined by access to and sustainable management of natural resources, the underlying mechanisms are still poorly understood. This study, which uses grounded theory integrated with discourse analysis, aims to contribute addressing this knowledge gap. First, we explore global literature describing trends and patterns in the various stressors—including climate change, frequent drought, and famine, ecological, socio-economic, and institutional stressors—that impact the livelihood resilience of these communities, with the goal of summarizing how multiple stressors impact the sustainability of dryland social-ecological systems. Then, using the sustainable development goals (SDGs) as a reference target, we propose potential entry points to support livelihood resilience pathways. These include land, water, livestock and agroforestry, and institutional and social capital. Lastly, we suggest an integrated multi-scalar pathway embedded with cross-sectorial policies and differential cross-social strategies towards combining resilience with SDGs targets. This research can help stakeholders to adapt to and mitigate the impacts of various stressors, ultimately strengthening livelihood resilience in dryland ecosystems
Delamination and debonding failure of laminated composite T-joints
No full textComposites are increasingly being used in aerospace, automotive and other industries. The T-joint (also named stringer stiffened skin) is a typical connection, broadly used in thin-walled structures, such as the wing and fuselage of aircraft. This thesis presents the analysis of the delamination and debonding failure of laminated composite T-joints, in support of the design and manufacture of integrated composite structures. Major attention has been paid to expand current knowledge on the failure response of the subcomponents of the T-joints: the through thickness reinforcements and adhesive layers were investigated both numerically and experimentally. Novel experimental methods and computational models have been developed to facilitate the characterization of these subcomponents and the in-depth understanding of the failure mechanisms of these subcomponents. The cohesive zone model has been used widely for modeling various fracture problems of the investigated materials. Novel cohesive laws were developed to represent the complex constitutive responses of these materials, and different mesh distribution strategies were employed as well. Pull-off and bending tests of T-joints were carried out where the failure process and loading capacity were evaluated. On the basis of the knowledge and analysis methods accumulated from the subcomponent studies, the delamination and debonding failure of T-joints has been numerically modeled; comparisons with experimental results have validated the accuracy and reliability of these numerical models. It is believed that this thesis has contributed to better understanding of the delamination and debonding failure of composite T-joints; the knowledge, methods and philosophy outlined here may also be applied to other composite/adhesively bonded structures as well.Mechanics, Aerospace Structures & MaterialsAerospace Engineerin
Characteristics and trends of grassland degradation research
No full textPurpose Grasslands are the largest type of terrestrial ecosystem on the earth, providing rich and unique ecosystem services.
However, climate change and human activities have triggered a global degradation of grasslands, which has become a major
ecological crisis. In this study, a scientometric analysis was performed to explore the hotspots and frontiers of global grassland
degradation research.
Materials and methods Two methods involving visualization were used to analyze these data: document co-citation analysis
and burst analysis based on the papers indexed in the Web of Science (WOS) during 1970–2020.
Results and discussion A total of 3580 research papers related to grassland degradation research and 54,666 references were
included. The results showed that Harris’s paper in 2010 had the strongest burst value of 26.2, far larger than any other,
which shows that this paper was a turning point in the research process. The document co-citation network was divided into
14 main theme clusters. The most influential and emerging research theme clusters were including alpine meadow, grazing
exclusion, alpine region, and human activities. Alpine meadow was the largest cluster lasting from 2010 to 2020, indicating
that this topic is still active in grassland degradation research. Furthermore, research focus has transferred toward grasslands
in Qinghai-Tibetan Plateau. The topic of grazing exclusion is both classic and currently active as it lasted as a research hotspot
for 15 years (2004–2018). However, the extent and state of grazing effects research are unclear.
Conclusions As the first scientometric review on grassland degradation research, our study identified the research hotspots
and their shifts over the past 50 years, pointing to some potential research frontiers in the future. The scientometric analysis
is a useful tool for a quantitative evaluation of research hotspots and trends of global grassland degradation
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