We show that three- and four-stage Bott manifolds are classified up to diffeomorphism by their integral cohomology rings. In addition, any cohomology ring isomorphism between two three-stage Bott ...manifolds can be realized by a diffeomorphism between the Bott manifolds.
A positioning system estimates the position and orientation of a vehicle. Autonomous driving systems plan paths and control the vehicle based on the information from the positioning system. Recently, ...methods of estimating the position in urban areas have been actively studied. In U-turn sections, which are common in urban areas, vehicles perform a rotation to reverse the direction of travel. Through these sections, drivers can reduce the travel distance and save time but with a high risk of an accident. Despite there being a need for the development of autonomous driving schemes for U-turn sections, the existing research is limited. This study proposes an interacting multiple model (IMM) filter-based position estimation algorithm for urban U-turn sections. To reflect the dynamic characteristics of a vehicle during U-turn maneuvers, a multiple vehicle model was used. This model includes kinematic and dynamic vehicle models. The state estimates of the vehicle model and gyroscope are combined using an IMM filter. The position estimation algorithm developed in this study is verified via experiments. The experimental results indicate that, during urban U-turn maneuvers, the position estimation accuracy of the IMM filter-based algorithm is improved than that of the single vehicle model.
This study investigated addictive behaviors (alcohol dependence and gambling tendencies), depression, and quality of life (QoL) among Korean fishermen in the Jeju Island region, Korea. The study ...utilized the Alcohol Use Disorder Identification Test-Korean version, the Korean version of the Canadian Problem Gambling Index, the Center for Epidemiological Studies Depression Scale, and the Korean version of the World Health Organization QOL-BREF to measure the study variables. The results showed that 18.1% of the fishermen had alcohol dependence and 9.9% abused alcohol, 13.6% were categorized as problem gamblers, 15.2% were moderate risk gamblers, and 14.4% were low-risk gamblers; 25.1% and 20.8% suffered from severe and mild depression, respectively. The mean QoL score was 3.13 ± 0.56, and the psychological health section scored the highest. The degree of alcohol dependence varied by age, education level, and job satisfaction; gambling tendency varied by age, job position, and job satisfaction; depression varied by religion and job satisfaction; QoL varied by religion and job satisfaction. Alcohol dependence, gambling tendency, and depression were significantly negatively correlated with QoL. Specifically, higher levels of alcohol dependence were associated with lower QoL scores in the subcategories of physical health and psychological health, while higher levels of gambling tendencies were associated with lower QoL scores in the subcategories of physical health, psychological health, social relationships, and general subcategories. Finally, higher levels of depression were associated with lower QoL scores across all five subcategories. Overall, participants exhibited remarkably elevated levels of alcohol dependence, gambling tendencies, and depression, and lower QoL compared with the general population. Further efforts are required to increase Korean fishermen's job satisfaction to improve these problems. In addition, public health policies must address and promote fishermen's QoL.
A real toric manifold
is said to be cohomologically rigid over
if every real toric manifold whose
-cohomology ring is isomorphic to that of
is actually diffeomorphic to
. Not all real toric manifolds ...are cohomologically rigid over
. In this paper, we prove that the connected sum of three real projective spaces is cohomologically rigid over
.
Biofilm occurs ubiquitously in water system. Excessive biofilm formation deteriorates severely system performance in several water and wastewater treatment processes. Quorum sensing systems were ...controlled in this study with a signal compound
-2-Decenoic acid (CDA) to regulate various functions of microbial communities, including motility, enzyme production, and extracellular polymeric substance (EPS) production in biofilm.
The addition of CDA to six strains extracted from membrane bioreactor sludge and the
PAO1 strain was examined for modulating biofilm development by regulating DSF expression.
As the CDA doses increased, optical density of the biofilm dispersion assay increased, and the decrease in EPS of the biofilm was obvious on membrane surfaces. The three-dimensional visual images and quantitative analyses of biofilm formation with CDA proved thinner, less massive, and more dispersive than those without; to evaluate its dispersive intensity, a dispersion index was proposed. This could compare the dispersive effects of CDA dosing to other biofilms or efficiencies of biofouling control practices such as backwashing or new cleaning methods.
Small covers over wedges of polygons CHOI, Suyoung; PARK, Hanchul
Journal of the Mathematical Society of Japan,
2019, Letnik:
71, Številka:
3
Journal Article
The newly coined term
supoza
(giving up mathematics, 수포자, 數抛者) describes a critical social issue that needs to be addressed in South Korea’s educational policy. Although the term has not received ...precise definition, it refers to students who have given up on learning mathematics. A precise definition would require detailing the current
supoza
situation and identifying its characteristics. This study therefore conducted a statistical investigation of commonalities among students who have given up on learning mathematics; the study results revealed that these students can be characterized by their affective domain for mathematics learning. We found that a statistical model could determine the likelihood that a particular student would report having given up mathematics based on responses to questions related to the affective domain of mathematics learning. This aspect suggests the possibility of understanding
supoza
with the exclusive use of affective factors and emphasizes the significance of the affective domain of mathematics learning. Additionally, this study provides a working example to show how exploratory analysis using big data can be used in relation to mathematical education.
Our characterization can also be described in terms of graph operations on directed acyclic graphs. Using this combinatorial interpretation, we prove that the decomposition of a real Bott manifold ...into a product of indecomposable real Bott manifolds is unique up to permutations of the indecomposable factors. Finally, we produce some numerical invariants of real Bott manifolds from the viewpoint of graph theory and discuss their topological meaning. As a by-product, we prove that the toral rank conjecture holds for real Bott manifolds.>
A fundamental idea in toric topology is that classes of manifolds with well-behaved torus actions (simply, toric spaces) are classified by pairs of simplicial complexes and (non-singular) ...characteristic maps. In a previous paper, the authors provided a new way to find all characteristic maps on a simplicial complex
$K(J)$
obtainable by a sequence of wedgings from
$K$
.The main idea was that characteristic maps on
$K$
theoretically determine all possible characteristic maps on a wedge of
$K$
. We further develop our previous work for classification of toric spaces. For a star-shaped simplicial sphere
$K$
of dimension
$n-1$
with
$m$
vertices, the Picard number Pic
$(K)$
of
$K$
is
$m-n$
. We call
$K$
a seed if
$K$
cannot be obtained by wedgings. First, we show that for a fixed positive integer
$\ell $
, there are at most finitely many seeds of Picard number
$\ell $
supporting characteristic maps. As a corollary, the conjecture proposed by V. V. Batyrev in is solved affirmatively. Secondly, we investigate a systematicmethod to find all characteristic maps on
$K(J)$
using combinatorial objects called (realizable) puzzles that only depend on a seed
$K$
. These two facts lead to a practical way to classify the toric spaces of fixed Picard number.
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