49 research outputs found
The impact of urban sprawl on green total factor productivity: A spatial econometric analysis in China
The rapid expansion of Chinese cities has led to serious urban productivity and eco-environment changes, and has therefore attracted considerable international academic attention. The main objective of this study is to investigate the theoretical mechanisms and practical effects of urban sprawl on green total factor productivity (GTFP), in order to provide a reference for optimizing the spatial layout of cities and promoting high-quality economic development. Realistic urban land area and population characteristics are extracted using DMSP/OLS and NPP/VIIRS nighttime lighting data, and LandScan global population dynamics statistics to measure the urban sprawl index. GTFP is measured using a super-SBM model that considers undesirable output. Based on the panel data of Chinese cities from 2006 to 2020, a spatial Durbin model was constructed to carry out the empirical analysis. The results show that, overall, urban sprawl in China is detrimental to its own GTFP, while contributing to the GTFP of neighboring cities. The impacts of urban sprawl vary markedly across cities of different sizes and across regions
A theoretical study of parietal vortex shedding in Taylor–Culick flow via linear stability analysis
Interferometric Imaging, and Beam-Formed Study of a Moving Type-IV Radio Burst with LOFAR
Type-IV radio bursts have been studied for over 50 years. However, the specifics of the radio emission mechanisms is still an open question. In order to provide more information about the emission mechanisms, we studied a moving Type-IV radio burst with fine structures (spike group) by using the high-resolution capability of the Low-Frequency Array (LOFAR) on August 25, 2014. We present a comparison of Nançay Radioheliograph (NRH) and the first LOFAR imaging data of the Type-IV radio burst. The degree of circular polarization (DCP) is calculated at frequencies in the range 20 — 180 MHz using LOFAR data, and it was found that the value of DCP gradually increased during the event, with values of 20 — 30%. LOFAR interferometric data were combined with white-light observations in order to track the propagation of this Type-IV burst. The kinematics shows a westward motion of the radio sources, slower than the CME leading edge. The dynamic spectrum of LOFAR shows a large number of fine structures with durations of less than 1 s and high brightness temperatures (TB), i.e., 1012 — 1013 K. The gradual increase of DCP supports gyrosynchrotron emission as the most plausible mechanism for the Type IV. However, coherent emissions such as Electron Cyclotron Maser (ECM) instability may be responsible for small-scale fine structures. Countless fine structures altogether were responsible for such high TB.Peer reviewe
OpenLane-V2: A Topology Reasoning Benchmark for Unified 3D HD Mapping
Accurately depicting the complex traffic scene is a vital component for
autonomous vehicles to execute correct judgments. However, existing benchmarks
tend to oversimplify the scene by solely focusing on lane perception tasks.
Observing that human drivers rely on both lanes and traffic signals to operate
their vehicles safely, we present OpenLane-V2, the first dataset on topology
reasoning for traffic scene structure. The objective of the presented dataset
is to advance research in understanding the structure of road scenes by
examining the relationship between perceived entities, such as traffic elements
and lanes. Leveraging existing datasets, OpenLane-V2 consists of 2,000
annotated road scenes that describe traffic elements and their correlation to
the lanes. It comprises three primary sub-tasks, including the 3D lane
detection inherited from OpenLane, accompanied by corresponding metrics to
evaluate the model's performance. We evaluate various state-of-the-art methods,
and present their quantitative and qualitative results on OpenLane-V2 to
indicate future avenues for investigating topology reasoning in traffic scenes.Comment: Accepted by NeurIPS 2023 Track on Datasets and Benchmarks |
OpenLane-V2 Dataset: https://github.com/OpenDriveLab/OpenLane-V
Revealing influencing factors on global waste distribution via deep-learning based dumpsite detection from satellite imagery
Implementasi Algoritma K-Nearest Neighbour Untuk Menentukan Nomor Klasifikasi Buku Studi Kasus: Perpustakaan Universitas Katolik Musi Charitas)
Classification of library books is important to allow visitors in search of a book. The classification system in the library of the Catholic University of Charity Musi using guide books dewey decimal classification (DDC). The problem in this research is the difficulty in determining the classification number of new books. By utilizing the methods of Information Retrieval (IR) or retrieval of information, so in this study will build an application program for classification of library books. The method will be used to classify the book library is a method of k-nearest neighbor (k-NN). The application program classification of library books is built with training data from library books Musi-Caritas Catholic University and the test data is a new book. Applications are made capable of classifying new library book
Major-Effect Alleles at Relatively Few Loci Underlie Distinct Vernalization and Flowering Variation in Arabidopsis Accessions
We have explored the genetic basis of variation in vernalization requirement and
response in Arabidopsis accessions, selected on the basis of their phenotypic
distinctiveness. Phenotyping of F2 populations in different environments, plus
fine mapping, indicated possible causative genes. Our data support the
identification of FRI and FLC as candidates
for the major-effect QTL underlying variation in vernalization response, and
identify a weak FLC allele, caused by a Mutator-like
transposon, contributing to flowering time variation in two N. American
accessions. They also reveal a number of additional QTL that contribute to
flowering time variation after saturating vernalization. One of these was the
result of expression variation at the FT locus. Overall, our
data suggest that distinct phenotypic variation in the vernalization and
flowering response of Arabidopsis accessions is accounted for by variation that
has arisen independently at relatively few major-effect loci
Flame response of solid propellant AP/Al/HTPB to a longitudinal acoustic wave
This paper is devoted to an experimental work which consists of the analysis of the flame of a small solid propellant sample, AP/Al/HTPB, subjected to a longitudinal acoustic wave. Experiments were conducted in a closed tube under two mean pressures: 1 and 2.5 MPa. The qualitative and quantitative analysis of the flame snapshots, using a microscope and a high-speed camera, revealed that the acoustic wave created at the end of the chamber by a pulser system strongly affects the flame and the combustion products dynamic above the solid propellant surface, namely, the flame and the hot products oscillate around a line perpendicular to the propellant surface. This dynamic of the hot gas disturbs the local burning rate and the regression surface profile. Thus, the thrust and the burning duration will change, therefore, the flight path of the rocket may shift and can lead to failure of the mission