The Characters of Soil Microbial Biomass and Metabolic Quotient Associated with Shrub Development in the Arid Region

Soil microbial biomass (MBC), as the most active of soil organic constituents, controls many important ecological processes in the ecosystem including nutrient cycling and litter decomposition (Jia et al. 2010), and is considered to be the most sensitive biological indicator of soil quality (Sinha et al. 2009). Moreover, soil microbial metabolic quotient (qCO2) reflects the quantity and quality of soil organic matter, soil nutrient availability, microbial substrate utilization efficiency and ecosystem stability (Mao et al. 2010). Shrub is the dominant vegetation of desert ecosystems, contributing to soil nutrient conservation and carbon sequestration. Considerable research related to shrubs in desert ecosystems has been reported, however changes of soil microbial properties throughout the process of shrub development remains poorly documented. The main objective of this study was to explore how soil microbial biomass and qCO2 change with shrub development

Fatty Acid Analysis of the Transgenic Tobacco Expressing A Delta 6-Desaturase Gene from \u3cem\u3eMicroula sikkimensis\u3c/em\u3e

γ-Linolenic acid (GLA, 18:3Δ6, 9, 12) and octadecatetraenoic acid (OTA, 18:4Δ6, 9, 12, 15) are important polyunsaturated fatty acids (PUFAs), which have been proved to be benefit for human health (Fan and Chapkin 1998; Whelan 2009). Currently, fish are the predominant source of PUFAs. However, with the growth of world’s population and the more nutrition requirements, fishery resources are shrinking. Alternative sources of PUFAs are being investigated (Truksa et al. 2009). The major oil crops do not contain GLA and OTA, only several plant species contain these important fatty acids in their leaf lipids and seed oils (Zhou et al. 2006). Genetic modification of oil crops may be an effective approach to produce these fatty acids. This process requires an enzyme–delta 6-desaturase, which can introduce a double bond at the delta 6 position (Meesa-pyodsuk and Qiu 2012). Microula sikkimensis is a kind of rare wild oil plant, which is widely distributed in Bhutan, Sikkim, Nepal and the northwest region of China (Cao and Suo 2010). Fu et al. (1997) reported that unsaturated fatty acids made up 86.5% of total fatty acids, and that GLA accounted for 6.4% of fatty acids in M. sikkimensis seeds that is known as a new source of GLA. In this research, the delta 6-desaturase gene of M. sikkimensis was introduced into tobacco and the fatty acid composition of transgenic tobacco was analysed

Plant C, N, P Stoichiometry Was Effected with Nitrogen Deposition on the Loess Plateau, China

The mass ratio of C:N:P (Carbon: Nitrogen: Phosphorus) in plant tissue can reflect the utilization efficiency of these basic elements (Piao et al. 2005). Additionally, the N:P ratio in plant tissue can be used to detect nutrient limita-tions as N, P or both are most often the driving force for ecosystem development and change (Koerselman and Meuleman 1996). N deposition has been increasing dramatically and it has great influence on the productivity, stability and nutrient supply conditions in the terrestrial and aquatic ecosystem in recent years (Wang and Yu 2008). Many scholars have focused on the C:N:P stoichiometry of individual plant or the whole plant communities which were based on weighted average of important key species and their element contents, rather than by collecting bio-mass samples of all the plants in the community level. Moreover, less is known of the effects of N deposition on C:N:P stoichiometry characteristics of plant communities, especially the grasslands of the Loess Plateau. An experiment was set to study the effects of N deposition on C, N,P stoichiometry characteristics by simulating N deposition by way of N addition

Estimation of VIV-parameters based on Response Measurements and Bayesian Machine Learning Algorithms

Analysis of structural response levels due to hydro-elastic vortex-induced vibrations (VIV) involves the specification of several parameters both associated with the fluid flow and the structural properties. To the maximum possible extent, the applied values of these parameters should be based on relevant results from experiments and full-scale measurements. This can be achieved by establishing a probabilistic framework which allows continuous learning in relation to the numerical models and associated parameters that are to be applied for the analysis. In this paper, a Bayesian optimization framework for estimating parameters in the VIV time-domain model (VIVANA-TD) is presented. As a case scenario, a simplified VIV model was studied for the purpose of illustration. A simple numerical model of a cylinder with 1 degree of freedom (DOF) was applied in predicting of the time-varying dynamic response. This prediction model is based on the hybrid-analytical concept, which relies on a combination of the time domain model and measured response features. In addition, two methods for estimating the parameter uncertainties are introduced.submittedVersio

Analysis of Full-scale Riser Responses in Field Conditions Based on Gaussian Mixture Model

Offshore slender marine structures experience complex and combined load conditions from waves, current and vessel motions that may result in both wave frequency and vortex shedding response patterns. Field measurements often consist of records of environmental conditions and riser responses, typically with 30-minute intervals. These data can be represented in a high-dimensional parameter space. However, it is difficult to visualize and understand the structural responses, as they are affected by many of these parameters. It becomes easier to identify trends and key parameters if the measurements with the same characteristics can be grouped together. Cluster analysis is an unsupervised learning method, which groups the data based on their relative distance, density of the data space, intervals, or statistical distributions. In the present study, a Gaussian mixture model guided by domain knowledge has been applied to analyze field measurements. Using the 242 measurement events of the Helland-Hansen riser, it is demonstrated that riser responses can be grouped into 12 clusters by the identification of key environmental parameters. This results in an improved understanding of complex structure responses. Furthermore, the cluster results are valuable for evaluating the riser response prediction accuracy.Comment: Matches accepted versio

State-of-the-Art Review of Vortex-Induced Motions of Floating Offshore Wind Turbine Structures

The motivation for this study is the fast development of floating offshore wind energy and the immature methodology and engineering practice related to predictions of vortex-induced motions (VIM). Benefiting from the oil and gas industry, in the past several decades, extensive knowledge and experience on vortex-induced vibrations (VIV) on slender marine structures has been gained. As the learnings from these efforts should be transferred and adapted to the renewable energy industry, a state-of-the-art review on influential VIM research has been carried out in this paper, focusing on: (1) engineering practice, (2) model tests, (3) numerical calculation, and (4) field measurement. Engineering gaps and potential research topics are identified as future work.publishedVersio

Plastic Optical Fiber with Spherical Lens Embedded in Mattress for Sleep Monitoring

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Structural and Hydrodynamic Aspects of Steel Lazy Wave Riser in Deepwater

Abstract Exploration of oil and gas in deep and ultra-deepwater under harsh weather condition is challenging. A steel lazy wave riser (SLWR) is considered to be a cost-effective alternative to get the gas or oil flow up to the platform under these conditions. The staggered buoyant section provides buoyancy force which forms an arch shape of the SLWR. This arch shape makes the SLWR configuration flexible and isolates the dynamic responses of the upper part and lower part of the riser. However, there is a lack of full understanding of the behavior of SLWRs. This is, due to a complicated loading from waves, vessel motions and flow induced vibrations caused by ocean currents, complex structural configurations, and non-linearities. Time-domain simulation is necessary to accurately predict the dynamic responses and capture the non-linearities. Realistic fatigue damage calculation is essential in the design phase of SLWR. The design of SLWR could be optimized with a better understanding of the dynamic responses of SLWR.</jats:p

Cladding mode characteristics simulation of an excessively tilted fiber grating coated with gold nanoshells

The cladding mode characteristics simulation of an excessively tilted fiber grating (ExTFG) coated with gold nanoshells was conducted in this study. First, the effective refractive indices of the core and cladding mode before coating were obtained by solving the eigenvalue equation of the three-layer waveguide structure, and the coupling characteristics were briefly analyzed. Then H E 1 , m and E H 1 , m modes were selected as the research objects, and the spectral characteristics of ExTFG coated with gold nanoshells were simulated by the finite element method. The simulated refractive index sensitivity of H E 1 , 29 and E H 1 , 29 modes is 160.16 and 185.03 nm/RIU, respectively. Compared with the non-localized surface plasmon resonance (LSPR) effect, it increased by 10.76 nm/RIU (7.2%) and 19.53 nm/RIU (11.8%), respectively. Thus, the LSPR effect was verified to be beneficial to improve the refractive index sensitivity of ExTFG.</jats:p