893 research outputs found
Dynamic modelling for ecological and economic sustainability in a rapid urbanizing region
AbstractRecently years, most of China's rapidly developed regions are becoming China's large industrial cities and drawing the attention of the world. Consequently, the impacts of rapid urbanization to urban ecosystem will be greatly increased with the increasing economic development. If relationship between economic development and ecological sustainability is not fully realized, urban ecosystem will be degraded at a high rate. Therefore, study on ecological and economic sustainability for this area is of great importance. The objectives of this study are: (1) to find a balance between economic development and ecological protection in these regions; (2) to develop a process-based ecological and economic sustainable development model; (3) to supply the optimal controls for these reigns by conducting a policy analysis. To this end, a system dynamic model for urban sustainable development was constructed. The model was based on the analysis of many index and three subsystems, which are society system, economic system, and environmental system. We also selected typical development policies for a rapidly urbanizing region, Tianjin, in the future
Evaluation of African-bred maize germplasm lines for resistance to aflatoxin accumulation
Aflatoxins, produced by the fungus Aspergillus flavus, contaminate maize grain and threaten human food and feed safety. Plant resistance is considered the best strategy for reducing aflatoxin accumulation. Six maize germplasm lines, TZAR101–TZAR106, were released by the International Institute of Tropical Agriculture-Southern Regional Research Center (IITA-SRRC) maize breeding collaboration for use in African National Programs and U.S. maize breeding programs. The present investigation was conducted to evaluate aflatoxin reduction by these lines in a U.S. environment. As germplasm lines, resistance was demonstrated by the lines tested in 2010 and 2014 trials. In 2010, TZAR106 was among the lines with the lowest toxin accumulation, and in 2014, along with TZAR102, supported low aflatoxin. When evaluated as single cross hybrids in 2012, 2013 and 2014, several crosses involving IITA-SRRC lines accumulated low toxin. In 2012, TZAR103 × HBA1 was one of 4 lines with the lowest concentration of aflatoxin. In 2014, five IITA-SRRC hybrids were among the lowest with TZAR102 × Va35 and TZAR102 × LH132 being the two lowest. Results demonstrate significant aflatoxin reduction by IITA-SRRC lines in a U.S. aflatoxin-conducive environment (at Mississippi State University). Further testing in different locations and environments is needed to further evaluate the potential usefulness of these germplasm lines
Mixed rectilinear sources localization under unknown mutual coupling
In this paper, a novel rectilinearity-based localization method for mixed near-field (NF) and far-field (FF) sources is proposed under unknown mutual coupling. The multiple parameters including direction of arrival (DOA), range and mutual coupling coefficient (MCC) are decoupled, thus only three one-dimensional (1-D) spectral searches are required to estimate the parameters of mixed rectilinear signals successively. Furthermore, the closed-form deterministic Cramer–Rao bound (CRB) of the concerned problem is also derived. Simulation results are provided to demonstrate the effectiveness of the proposed method for the classification and localization of mixed rectilinear sources
Historical data based energy management in a microgrid with a hybrid energy storage system
In a micro-grid, due to potential reverse output profiles of the Renewable Energy Source (RES) and the load, energy storage devices are employed to achieve high self-consumption of RES and to minimize power surplus flowing back into the main grid. This paper proposes a variable charging/discharging threshold method to manage energy storage system. And an Adaptive Intelligence Technique (AIT) is put forward to raise the power management efficiency. A battery-ultra-capacitor hybrid energy storage system (HESS) with merits of high energy and power density is used to evaluate the proposed method with onsite measured RES output data. Compared with the PSO algorithm based on the precise predicted data of the load and the RES, the results show that the proposed method can achieve better load smoothing and maximum self-consumption of the RES without the requirement of precise load and RES forecasting
Analytical method of process capability for steel
The mechanical properties of steel are the most important factor in the safety of structures that must be stable and appropriate. In order to investigate whether the process capability of steel production meets the quality requirements or not, Sung et al. proposed a procedure to evaluate the production and quality control of steel manufacturing. This evaluation model uses statistics to judge the quality of steel objectively. However, there are various types of steel which can satisfy the engineering requirements of design and construction, but procedures are lacking with which to evaluate the multi-process capability of the whole steelwork. In this paper, the objective evaluation methods proposed by Sung and Vannman are modified appropriately and extended by using the principles of statistical inference. A procedure to evaluate the quality of the multi-process capability analysis method is proposed. This evaluation method not only completely evaluates the process capability and quality, but it also improves the production process and quality control capability, and so can reduce production loss
Search for Small Trans-Neptunian Objects by the TAOS Project
The Taiwan-America Occultation Survey (TAOS) aims to determine the number of
small icy bodies in the outer reach of the Solar System by means of stellar
occultation. An array of 4 robotic small (D=0.5 m), wide-field (f/1.9)
telescopes have been installed at Lulin Observatory in Taiwan to simultaneously
monitor some thousand of stars for such rare occultation events. Because a
typical occultation event by a TNO a few km across will last for only a
fraction of a second, fast photometry is necessary. A special CCD readout
scheme has been devised to allow for stellar photometry taken a few times per
second. Effective analysis pipelines have been developed to process stellar
light curves and to correlate any possible flux changes among all telescopes. A
few billion photometric measurements have been collected since the routine
survey began in early 2005. Our preliminary result of a very low detection rate
suggests a deficit of small TNOs down to a few km size, consistent with the
extrapolation of some recent studies of larger (30--100 km) TNOs.Comment: 4 pages, 3 figures, IAU Symposium 23
Multilevel Semantic Analysis and Problem-Solving in the Flight Domain: Final Report: NASA Grant NCCI-52, July 11, 1981-July 10, 1982
Coordinated Science Laboratory was formerly known as Control Systems LaboratoryNASA Grant NCCI-5
Transition from band insulator to Mott insulator in one dimension: Critical behavior and phase diagram
We report a systematic study of the transition from a band insulator (BI) to
a Mott insulator (MI) in a one-dimensional Hubbard model at half-filling with
an on-site Coulomb interaction U and an alternating periodic site potential V.
We employ both the zero-temperature density matrix renormalization group (DMRG)
method to determine the gap and critical behavior of the system and the
finite-temperature transfer matrix renormalization group method to evaluate the
thermodynamic properties. We find two critical points at U = and U =
that separate the BI and MI phases for a given V. A charge-neutral
spin-singlet exciton band develops in the BI phase (U<) and drops below
the band gap when U exceeds a special point Ue. The exciton gap closes at the
first critical point while the charge and spin gaps persist and coincide
between <U< where the system is dimerized. Both the charge and spin
gaps collapse at U = when the transition to the MI phase occurs. In the
MI phase (U>) the charge gap increases almost linearly with U while the
spin gap remains zero. These findings clarify earlier published results on the
same model, and offer insights into several important issues regarding an
appropriate scaling analysis of DMRG data and a full physical picture of the
delicate nature of the phase transitions driven by electron correlation. The
present work provides a comprehensive understanding for the critical behavior
and phase diagram for the transition from BI to MI in one-dimensional
correlated electron systems with a periodic alternating site potential.Comment: long version, 10 figure
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