Adaptive Three-Stage Controlled Islanding to Prevent Imminent Wide-area Blackouts

Power blackouts are a recurring problem worldwide, and research in this area continues to focus on developing improved methods for their prediction and prevention. Controlled islanding has been proposed as a last resort action to save the network before imminent blackouts when the usual means fail in an unexpected manner. Successful controlled islanding has to deal with three important issues that are involved in the implementation of islanding: when to island, where to island and what to do after islanding is implemented in each island. This thesis presents a framework that combines all three issues to achieve successful islanding based on wide area measurement systems (WAMS). In addition, this thesis focuses on the question of when to island. This question is critical to the success of the three-stage controlled islanding scheme because the possible issues of false dismissal and false alarm have to be handled. In false dismissal, islanding is triggered too late. However, the potentially unstable system is still allowed to operate, and this unstable system, which could have survived, may cause uncontrolled cascading blackouts. In false alarm, islanding is triggered too early, and an originally stable system is forced to split into islands, resulting in unnecessary disruption and economic loss. Thus, the early recognition and identification of “the point of no return” before blackout is inevitable. The single machine equivalent (SIME) method is adopted online to predict transient stability during cascading outages that would shortly lead to blackouts, giving support in decisions about when to island in terms of transient instability. SIME also evaluates dynamic stability after islanding and ensures that the selected island candidates are stable before action is taken. Moreover, in this thesis, the power flow tracing-based method provides all possible islanding cutsets, and SIME helps to identify the one that has the best transient stability and minimal power flow disruption. If no possible island cut set exists, corrective actions through tripping critical generators or load shedding are undertaken in each island. The IEEE 10-generator, 39-busbar power system and 16-generator 68-busbar system are used to demonstrate the entire framework of the controlled islanding scheme. The performance of each methodology involved in each stage is then presented

Chinese water policy for sustainable water resources: Options for the future

China has no option but to press on with the implementation of the National Water Initiative as stated by its government in ‘’Document No. 1". One might observe that it can be a bit heavy in political terms. Most hydrological means are pretty meaningless in reality. Though the nation is not sure if it can handle such a project effectively yet, it will certainly approach it with a degree of commitment. The paper aims to build an integrated understanding of these issues and to illustrate appropriate policy directions and management practices. These are ambitious goals, but they are essential and relevant in the milestone of the Chinese water resources management and policy.Key words: Climate change, Chinese water vision, the national water initiative, national water resources management, integrated water resources management, policy implications

Research on Continuous Use of B2B Platform in Chinese Intelligent Engineering Companies Based on the Theory of Resource Complementary

What factors affect the continuous use of B2B platforms by intelligent engineering companies is an important issue. Based on the theory of resource complementarity, a model of influencing factors for intelligent engineering companies to continue using the B2B platform is constructed, and four influencing factors including the complementary resources given by the platform, the complementary resources given by the company, interaction quality, and exploration and exploitation capability are analyzed. Using SmartPLS 3.0 to analyze 217 survey data, the results show that the complementary resources given by the platform and companies have positive impact on the interaction quality, and the complementary resources given by the platform have positive effect on the exploration and exploitation capabilities. Interaction quality has positive impact on the company’s continuous use intention of the B2B platform. The complementary resources given by the company have no positive impact on the exploration and exploitation capabilities, and the exploration and exploitation capabilities have no positive impact on the company’s continuous use intention of the B2B platform. Finally, some suggestions are proposed to increase the company’s continuous use intention of B2B platform

Allelopathy regulates wheat genotypes performance at the enhancement stage by soil water and prohydrojasmon (PDJ)

Growth adaptation and allelopathic potential of four winter wheat (Triticum aestivum L.) accessions has been investigated in pot experiments by prohydrojasmon (PDJ, 10 - 5M) and soil water (75 and 45%) at the enhancement stage. This paper also presented the performance of photosynthesis, water use and weed suppression. The effect of soil water and PDJ on wheat performance displayed significant differences depending on tested wheat cultivars and measured parameters. Water deficit decreased plant biomass significantly and changed phenotypic characteristics like plant height and leaf area of wheat. However, PDJ was found to stimulate wheat root growth and development so as to enhance pressure resistance and induce strong allelopathic potential and weed resistance. Physiological response in var. Lankao 95 - 25 to water shortage and PDJ was significantly relative to net photosynthesis rate and water use efficiency. Water deficit and PDJ would lead to plant phenotype and photosynthesis change and consequently, influence allelopathic expression and weed suppression of wheat based on Canonical Correspondence Analysis (CCA). Water deficit would induce the production and accumulation of more allelochemicals in wheat by passive transport of energy cost. Differing the regulation mechanism of water stress, PDJ showed active transport of energy supply in allelopathic stimulation, which implied that PDJ mainly exhibited its hormone effect to regulate and control wheat growth and development such as improving phenotypic features on competition at the basis of increasing growth cost. Therefore, it was possible for artificial measures to regulate allelopathic potential and weed resistance capacity of winter wheat cultivars, especially, in the arid areas of Loess Plateau of China.Keyword: Allelopathic potential, inducible regulation and interaction, prohydrojasmon, soil water stress, weed suppression, winter wheatAfrican Journal of Biotechnology Vol. 9(33), pp. 5430-5440, 16 August, 201

Analysis of Phenolic Acids of Jerusalem Artichoke ( Helianthus tuberosus

Plant phenolics can have applications in pharmaceutical and other industries. To identify and quantify the phenolic compounds in Helianthus tuberosus leaves, qualitative analysis was performed by a reversed phase high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) and quantitative analysis by HPLC. Ten chlorogenic acids (CGAs) were identified (3-o-caffeoylquinic acid, two isomers of caffeoylquinic acid, caffeic acid, p-coumaroyl-quinic acid, feruloylquinic acid, 3,4-dicaffeoyquinic acid, 3,5-dicaffeoylquinic acid, 1,5-dicaffeoylquinic acid, and 4,5-dicaffeoylquinic acid) by comparing their retention times, UV-Vis absorption spectra, and MS/MS spectra with standards. In addition, four other phenolic compounds, including caffeoyl glucopyranose, isorhamnetin glucoside, kaempferol glucuronide, and kaempferol-3-o-glucoside, were tentatively identified in Helianthus tuberosus leaves for the first time. The 3-o-caffeoylquinic acid (7.752 mg/g DW), 4,5-dicaffeoylquinic acid (5.633 mg/g DW), and 3,5-dicaffeoylquinic acid (4.900 mg/g DW) were the major phenolic compounds in leaves of Helianthus tuberosus cultivar NanYu in maturity. The variations in phenolic concentrations and proportions in Helianthus tuberosus leaves were influenced by genotype and plant growth stage. Cultivar NanYu had the highest concentration of phenolic compounds, in particular 3-o-caffeoylquinic acid and 4,5-dicaffeoylquinic acid compared with the other genotypes (wild accession and QingYu). Considering various growth stages, the concentration of total phenolics in cultivar NanYu was higher at flowering stage (5.270 mg/g DW) than at budding and tuber swelling stages. Cultivar NanYu of Helianthus tuberosus is a potential source of natural phenolics that may play an important role in the development of pharmaceuticals

An Integrated Use of Topography with RSI in Gully Mapping, Shandong Peninsula, China

Taking the Quickbird optical satellite imagery of the small watershed of Beiyanzigou valley of Qixia city, Shandong province, as the study data, we proposed a new method by using a fused image of topography with remote sensing imagery (RSI) to achieve a high precision interpretation of gully edge lines. The technique first transformed remote sensing imagery into HSV color space from RGB color space. Then the slope threshold values of gully edge line and gully thalweg were gained through field survey and the slope data were segmented using thresholding, respectively. Based on the fused image in combination with gully thalweg thresholding vectors, the gully thalweg thresholding vectors were amended. Lastly, the gully edge line might be interpreted based on the amended gully thalweg vectors, fused image, gully edge line thresholding vectors, and slope data. A testing region was selected in the study area to assess the accuracy. Then accuracy assessment of the gully information interpreted by both interpreting remote sensing imagery only and the fused image was performed using the deviation, kappa coefficient, and overall accuracy of error matrix. Compared with interpreting remote sensing imagery only, the overall accuracy and kappa coefficient are increased by 24.080% and 264.364%, respectively. The average deviations of gully head and gully edge line are reduced by 60.448% and 67.406%, respectively. The test results show the thematic and the positional accuracy of gully interpreted by new method are significantly higher. Finally, the error sources for interpretation accuracy by the two methods were analyzed

Fast 3D Indoor Scene Synthesis by Learning Spatial Relation Priors of Objects

We present a framework for fast synthesizing indoor scenes, given a room geometry and a list of objects with learnt priors.Unlike existing data-driven solutions, which often learn priors by co-occurrence analysis and statistical model fitting, our methodmeasures the strengths of spatial relations by tests for complete spatial randomness (CSR), and learns discrete priors based onsamples with the ability to accurately represent exact layout patterns. With the learnt priors, our method achieves both acceleration andplausibility by partitioning the input objects into disjoint groups, followed by layout optimization using position-based dynamics (PBD)based on the Hausdorff metric. Experiments show that our framework is capable of measuring more reasonable relations amongobjects and simultaneously generating varied arrangements in seconds compared with the state-of-the-art works.</p