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  • 1
    Publication Date: 2019
    Description: Complex natural disasters often cause people to suffer hardships, and they can cause a large number of casualties. A population that has been affected by a natural disaster is at high risk and desperately in need of help. Even with the timely assessment and knowledge of the degree that natural disasters affect populations, challenges arise during emergency response in the aftermath of a natural disaster. This paper proposes an approach to assessing the near-real-time intensity of the affected population using social media data. Because of its fatal impact on the Philippines, Typhoon Haiyan was selected as a case study. The results show that the normalized affected population index (NAPI) has a significant ability to indicate the affected population intensity. With the geographic information of disasters, more accurate and relevant disaster relief information can be extracted from social media data. The method proposed in this paper will benefit disaster relief operations and decision-making, which can be executed in a timely manner.
    Electronic ISSN: 2220-9964
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
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  • 2
    Publication Date: 2019
    Description: National large-scale soil and water conservation controls on the Gangjiang River basin have been documented, but the effect of governance on regional watershed hydrology and how the main driving factors act have not been systematically studied yet. To do this, this study evaluated changing trends and detected transition years for both streamflow and sediment discharge using long-term historical records at seven hydrological stations in the Ganjiang River basin over the past 50 years. The double mass curve (DMC) method was used to quantify the effects of both climate change and human activities on hydrological regime shifts. The results showed that the distributions of precipitation, streamflow, and sediment discharge within a year are extremely uneven and mainly concentrated in the flood season of Jiangxi Province. None of the stations showed significant trends over time for either annual precipitation or streamflow, while the annual sediment discharge at most stations decreased significantly over time. The estimation of sediment discharge via DMC indicated that after the transition years, there were rapid reductions in sediment discharge at all hydrological stations, and the average decline degree of midstream and downstream were much larger than that of upstream. Human activities, especially the increase of vegetation cover and construction of large and medium-sized reservoirs, provided a significantly greater contribution to the reduction of sediment discharge than did precipitation changes. As a case study of river evolution under global change environment, this study could provide scientific basis for the control of soil erosion and the management of water resources in Ganjiang River, as well as for the related research of Poyang Lake and the Yangtze River basin of China.
    Electronic ISSN: 2073-4441
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by MDPI
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  • 3
    Publication Date: 2019
    Description: Electrolytic water splitting with evolution of both hydrogen (HER) and oxygen (OER) is an attractive way to produce clean energy hydrogen. It is critical to explore effective, but low-cost electrocatalysts for the evolution of oxygen (OER) owing to its sluggish kinetics for practical applications. Fe-based catalysts have advantages over Ni- and Co-based materials because of low costs, abundance of raw materials, and environmental issues. However, their inefficiency as OER catalysts has caused them to receive little attention. Herein, the FeS2/C catalyst with porous nanostructure was synthesized with rational design via the in situ electrochemical activation method, which serves as a good catalytic reaction in the OER process. The FeS2/C catalyst delivers overpotential values of only 291 mV and 338 mV current densities of 10 mA/cm2 and 50 mA/cm2, respectively, after electrochemical activation, and exhibits staying power for 15 h.
    Electronic ISSN: 1996-1944
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by MDPI
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  • 4
    Publication Date: 2019
    Description: While there is a decline in the annual population of Taiwan, the number of crams schools in the supplementary education industry is increasing. A concern is that there are not enough students to go around. Cram schools are facing a difficult situation to survive in the industry. Therefore, a great and useful leadership method is needed to help leaders lead their faculty members and organizations so that they can survive and even grow in this white-hot industry. In this study, 400 New Taipei City cram school faculties were invited to be the research objects to study the influences of transformational leadership, transactional leadership, and patriarchal leadership on job satisfaction. This study adopted the method of intentional sampling to conduct a questionnaire survey. After collecting data, SPSS 12.0 software was used to analyze the descriptive statistics, reliability analysis, description of statistics, t-test method of single factor analysis of variance, and regression. As a result of this research, the employees under transformational leadership have a larger positive result on outer job satisfaction while patriarchal leadership has positive influences on inner job satisfaction. Encouraging subordinates with positive responses, inspiring speeches, and compliments could make subordinates satisfied with the company and interaction with colleagues, while teaching subordinates behavior sets up a moral and authorized style and controlling the organization directly could let subordinates get a sense of accomplishment from work. This study is aimed to provide suggestions and references for the cram schools’ leaders to change their leadership styles and improve their employees’ job satisfaction. Cram schools that take the suggestions and references could improve their working environment and become more competitive in the education industry.
    Electronic ISSN: 2071-1050
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by MDPI
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  • 5
    Publication Date: 2019
    Description: Air-sea interactions play an important role in atmospheric circulation and boundary layer conditions through changing convection processes and surface heat fluxes, particularly in coastal areas. These changes can affect the concentrations, distributions, and lifetimes of atmospheric pollutants. In this Part II paper, the performance of the Weather Research and Forecasting model with chemistry (WRF/Chem) and the coupled WRF/Chem with the Regional Ocean Model System (ROMS) (WRF/Chem-ROMS) are intercompared for their applications over quadruple-nested domains in Australia during the three following field campaigns: The Sydney Particle Study Stages 1 and 2 (SPS1 and SPS2) and the Measurements of Urban, Marine, and Biogenic Air (MUMBA). The results are used to evaluate the impact of air-sea interaction representation in WRF/Chem-ROMS on model predictions. At 3, 9, and 27 km resolutions, compared to WRF/Chem, the explicit air-sea interactions in WRF/Chem-ROMS lead to substantial improvements in simulated sea-surface temperature (SST), latent heat fluxes (LHF), and sensible heat fluxes (SHF) over the ocean, in terms of statistics and spatial distributions, during all three field campaigns. The use of finer grid resolutions (3 or 9 km) effectively reduces the biases in these variables during SPS1 and SPS2 by WRF/Chem-ROMS, whereas it further increases these biases for WRF/Chem during all field campaigns. The large differences in SST, LHF, and SHF between the two models lead to different radiative, cloud, meteorological, and chemical predictions. WRF/Chem-ROMS generally performs better in terms of statistics and temporal variations for temperature and relative humidity at 2 m, wind speed and direction at 10 m, and precipitation. The percentage differences in simulated surface concentrations between the two models are mostly in the range of ±10% for CO, OH, and O3, ±25% for HCHO, ±30% for NO2, ±35% for H2O2, ±50% for SO2, ±60% for isoprene and terpenes, ±15% for PM2.5, and ±12% for PM10. WRF/Chem-ROMS at 3 km resolution slightly improves the statistical performance of many surface and column concentrations. WRF/Chem simulations with satellite-constrained boundary conditions (BCONs) improve the spatial distributions and magnitudes of column CO for all field campaigns and slightly improve those of the column NO2 for SPS1 and SPS2, column HCHO for SPS1 and MUMBA, and column O3 for SPS2 at 3 km over the Greater Sydney area. The satellite-constrained chemical BCONs reduce the model biases of surface CO, NO, and O3 predictions at 3 km for all field campaigns, surface PM2.5 predictions at 3 km for SPS1 and MUMBA, and surface PM10 predictions at all grid resolutions for all field campaigns. A more important role of chemical BCONs in the Southern Hemisphere, compared to that in the Northern Hemisphere reported in this work, indicates a crucial need in developing more realistic chemical BCONs for O3 in the relatively clean SH.
    Electronic ISSN: 2073-4433
    Topics: Geosciences
    Published by MDPI
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  • 6
    Publication Date: 2019
    Description: Drought and topographic position are the most important factors influencing tree growth and survival in semiarid sandy regions of Northeast China. However, little is known about how trees respond to drought in combination with topographic position by modifying the depth of soil water extraction. Therefore, we identified water sources for 33-year-old Mongolian pine (Pinus sylvestris L. var. mongolica Litv.) trees growing at the top and bottom of sand dunes by comparing stable isotopes δ2H and δ18O in twig xylem water, soil water at various depths and groundwater during dry and wet periods. Needle carbon isotope composition (δ13C) was simultaneously measured to assess water use efficiency. Results showed that when soil moisture was low during the dry period, trees at the top used 40–300 cm soil water while trees at the bottom utilized both 40–300 cm soil water and possibly groundwater. Nevertheless, when soil moisture at 0–100 cm depth was higher during the wet period, it was the dominant water sources for trees at both the top and bottom. Moreover, needle δ13C in the dry period were significantly higher than those in the wet period. These findings suggested that trees at both the top and bottom adjust water uptake towards deeper water sources and improve their water use efficiency under drought condition. Additionally, during the dry period, trees at the top used shallower water sources compared with trees at the bottom, in combination with significantly higher needle δ13C, indicating that trees at the bottom applied a relatively more prodigal use of water by taking up deeper water (possibly groundwater) during drought conditions. Therefore, Mongolian pine trees at the top were more susceptible to suffer dieback under extreme dry years because of shallower soil water uptake and increased water restrictions. Nevertheless, a sharp decline in the groundwater level under extreme dry years had a strong negative impact on the growth and survival of Mongolian pine trees at the bottom due to their utilization of deeper water sources (possibly groundwater).
    Electronic ISSN: 1999-4907
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by MDPI
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  • 7
    Publication Date: 2019
    Description: Effective thermal conductivity (ETC), as a necessary parameter in the thermal properties of rock, is affected by the pore structure and the thermal conduction conditions. To evaluate the effect of fractures and saturated fluids on sandstone’s thermal conductivity, we simulated thermal conduction along three orthogonal (X, Y, and Z) directions under air- and water-saturated conditions on reconstructed digital rocks with different fractures. The results show that the temperature distribution is separated by the fracture. The significant difference between the thermal conductivities of solid and fluid is the primary factor influencing the temperature distribution, and the thermal conduction mainly depends on the solid phase. A nonlinear reduction of ETC is observed with increasing fracture length and angle. Only when the values of the fracture length and angle are large, a negative effect of fracture aperture on the ETC is apparent. Based on the partial least squares (PLS) regression method, the fluid thermal conductivity shows the greatest positive influence on the ETC value. The fracture length and angle are two other factors significantly influencing the ETC, while the impact of fracture aperture may be ignored. We obtained a predictive equation of ETC which considers the related parameters of digital rocks, including the fracture length, fracture aperture, angle between the fracture and the heat flux direction, porosity, and the thermal conductivity of saturated fluid.
    Electronic ISSN: 1996-1073
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by MDPI
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  • 8
    Publication Date: 2019
    Description: The optimal scheduling of multi-energy hub systems plays an important role in the safety, stability, and economic operation of the system. However, due to the strong uncertainty of renewable energy access, serious coupling, and the interaction among energy hubs of multi-energy hub systems, it is difficult for the traditional optimal scheduling method to solve these problems. Therefore, game theory was used to solve the optimal scheduling problem of multi-energy hub systems. According to the internal connection mode and energy conversion relationship of energy hubs, along with the competitive and cooperative relationship between multi-energy hubs, the game theoretic optimal scheduling model of the multi-energy hub system was established. Then, two cases and 50 groups of wind speed series were used to test the robustness of the proposed method. Simulation results show that the total power injection is −16,805.8, 104.1847, and −865.561 and the natural gas injection is 46,046.81, 27,727.65, and 63,039.54 in spring/autumn, summer, and winter, respectively, which is consistent with the characteristics of the four seasons. Furthermore, the optimal scheduling method using game theory has a strong robustness in multi-energy hub systems.
    Electronic ISSN: 1996-1073
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by MDPI
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  • 9
    Publication Date: 2019
    Description: In order to effectively improve the dynamic characteristics of the fixed metal joint interface, it is important to establish a correct equivalent model of the metal joint interface. In this paper, three equivalent methods for simulating the metal joint interface are analyzed, including the virtual material method, spring damping method, finite element method, and verification by modal experiment. First, according to the contact mechanics model of the constructed metal joint interface, the physical properties of the three-dimensional models of the fixed joint interface are assigned in the ANSYS software. Then, three methods are used for the modal analysis and compared with a modal experiment. The results show that the modal shapes of the three theoretical methods are consistent with those of the experimental modes. The first five natural frequencies obtained by the virtual material method are closest to the experimental natural frequencies, and the errors are within 10%. The errors of the other two methods are between 9% and 39%. Therefore, the virtual material method is a better equivalent method of the metal joint interface.
    Electronic ISSN: 1996-1944
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by MDPI
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  • 10
    Publication Date: 2018
    Description: Researchers from different disciplines, such as materials science, computer science, safety science, mechanical engineering and controlling engineering, have aimed to improve the quality of manufacturing engineering processes. Considering the requirements of research and development of advanced materials, reliable manufacturing and collaborative innovation, a multidiscipline integrated platform framework based on probabilistic analysis for manufacturing engineering processes is proposed. The proposed platform consists of three logical layers: The requirement layer, the database layer and the application layer. The platform is intended to be a scalable system to gradually supplement related data, models and approaches. The main key technologies of the platform, encapsulation methods, information fusion approaches and the collaborative mechanism are also discussed. The proposed platform will also be gradually improved in the future. In order to exchange information for manufacturing engineering processes, scientists and engineers of different institutes of materials science and manufacturing engineering should strengthen their cooperation.
    Electronic ISSN: 1999-5903
    Topics: Computer Science
    Published by MDPI
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