523 research outputs found
Novel Silica-Based Hybrid Adsorbents: Lead(II) Adsorption Isotherms
Water pollution caused by the lead(II) from the spent liquor has caught much attention. The research from the theoretical model to application fundaments is of vital importance. In this study, lead(II) adsorption isotherms are investigated using a series of hybrid membranes containing mercapto groups (–SH groups) as the hybrid adsorbents. To determine the best fitting equation, the experimental data were analyzed using six two-parameter isotherm equations (i.e., Langmuir, Freundlich, Dubinin-Radushkevich (D-R), Temkin, Harkins-Jura, and Halsey isotherm models). It was found that the lead(II) adsorption on these samples followed the Freundlich, Dubinin-Radushkevich (D-R), and Halsey isotherm models. Moreover, the mean free energy of adsorption was calculated using Dubinin-Radushkevich (D-R) isotherm model and it was confirmed that the adsorption process was physical in nature. These findings are very meaningful in the removal of lead(II) ions from water using the hybrid membranes as adsorbents
The largest crossing number of tanglegrams
A tanglegram consists of two rooted binary trees with the same
number of leaves, and a perfect matching between the two leaf sets. In a
layout, the tanglegrams is drawn with the leaves on two parallel lines, the
trees on either side of the strip created by these lines are drawn as plane
trees, and the perfect matching is drawn in straight line segments inside the
strip. The tanglegram crossing number of is the
smallest number of crossings of pairs of matching edges, over all possible
layouts of . The size of the tanglegram is the number of matching
edges, say . An earlier paper showed that the maximum of the tanglegram
crossing number of size tanglegrams is ; but is
at least for infinitely many .
Now we make better bounds: the maximum crossing number of a size tanglegram
is at most , but for infinitely many ,
at least . The problem shows
analogy with the Unbalancing Lights Problem of Gale and Berlekamp
Moderating effect of classroom sociable norm on the relations between unsociability and internalizing problems in Chinese adolescents
ObjectivesThe goal of the present study was to examine the moderating effect of classroom sociable norm on the relations between unsociability and internalizing problems (the indicators included depression, loneliness and self-esteem) in Chinese adolescents.MethodsParticipants were N = 1,160 adolescents in Grade 4–8 from Shanghai, People’s Republic of China. They completed questionnaires about unsociability, sociability, and social preference via peer nominations, while depression, loneliness, and self-esteem were collected via self-report.ResultsIt was found that unsociability was positively associated with depression and loneliness, and negatively associated with self-esteem. Moreover, the relations between unsociability and indicators of internalizing problems were moderated by classroom sociable norm. More specifically, the significant positive associations between unsociability and depression and loneliness were stronger in classrooms with high sociable norm, and the negative association between unsociability and self-esteem was only significant in such classrooms.ConclusionThe findings suggest that classroom sociable norm plays an important role in unsociable adolescents’ psychological adjustment in China. Researchers should focus more on the influence of classroom environment on adolescents’ development in future
Apparatus and process for freeform fabrication of composite reinforcement preforms
A solid freeform fabrication process and apparatus for making a three-dimensional reinforcement shape. The process comprises the steps of (1) operating a multiple-channel material deposition device for dispensing a liquid adhesive composition and selected reinforcement materials at predetermined proportions onto a work surface; (2) during the material deposition process, moving the deposition device and the work surface relative to each other in an X-Y plane defined by first and second directions and in a Z direction orthogonal to the X-Y plane so that the materials are deposited to form a first layer of the shape; (3) repeating these steps to deposit multiple layers for forming a three-dimensional preform shape; and (4) periodically hardening the adhesive to rigidize individual layers of the preform. These steps are preferably executed under the control of a computer system by taking additional steps of (5) creating a geometry of the shape on the computer with the geometry including a plurality of segments defining the preform shape and each segment being preferably coded with a reinforcement composition defining a specific proportion of different reinforcement materials; (6) generating programmed signals corresponding to each of the segments in a predetermined sequence; and (7) moving the deposition device and the work surface relative to each other in response to these programmed signals. Preferably, the system is also operated to generate a support structure for any un-supported feature of the 3-D preform shape
Learning a More Continuous Zero Level Set in Unsigned Distance Fields through Level Set Projection
Latest methods represent shapes with open surfaces using unsigned distance
functions (UDFs). They train neural networks to learn UDFs and reconstruct
surfaces with the gradients around the zero level set of the UDF. However, the
differential networks struggle from learning the zero level set where the UDF
is not differentiable, which leads to large errors on unsigned distances and
gradients around the zero level set, resulting in highly fragmented and
discontinuous surfaces. To resolve this problem, we propose to learn a more
continuous zero level set in UDFs with level set projections. Our insight is to
guide the learning of zero level set using the rest non-zero level sets via a
projection procedure. Our idea is inspired from the observations that the
non-zero level sets are much smoother and more continuous than the zero level
set. We pull the non-zero level sets onto the zero level set with gradient
constraints which align gradients over different level sets and correct
unsigned distance errors on the zero level set, leading to a smoother and more
continuous unsigned distance field. We conduct comprehensive experiments in
surface reconstruction for point clouds, real scans or depth maps, and further
explore the performance in unsupervised point cloud upsampling and unsupervised
point normal estimation with the learned UDF, which demonstrate our non-trivial
improvements over the state-of-the-art methods. Code is available at
https://github.com/junshengzhou/LevelSetUDF .Comment: To appear at ICCV2023. Code is available at
https://github.com/junshengzhou/LevelSetUD
Learning Consistency-Aware Unsigned Distance Functions Progressively from Raw Point Clouds
Surface reconstruction for point clouds is an important task in 3D computer
vision. Most of the latest methods resolve this problem by learning signed
distance functions (SDF) from point clouds, which are limited to reconstructing
shapes or scenes with closed surfaces. Some other methods tried to represent
shapes or scenes with open surfaces using unsigned distance functions (UDF)
which are learned from large scale ground truth unsigned distances. However,
the learned UDF is hard to provide smooth distance fields near the surface due
to the noncontinuous character of point clouds. In this paper, we propose a
novel method to learn consistency-aware unsigned distance functions directly
from raw point clouds. We achieve this by learning to move 3D queries to reach
the surface with a field consistency constraint, where we also enable to
progressively estimate a more accurate surface. Specifically, we train a neural
network to gradually infer the relationship between 3D queries and the
approximated surface by searching for the moving target of queries in a dynamic
way, which results in a consistent field around the surface. Meanwhile, we
introduce a polygonization algorithm to extract surfaces directly from the
gradient field of the learned UDF. The experimental results in surface
reconstruction for synthetic and real scan data show significant improvements
over the state-of-the-art under the widely used benchmarks.Comment: Accepted by NeurIPS 2022. Project
page:https://junshengzhou.github.io/CAP-UDF.
Code:https://github.com/junshengzhou/CAP-UD
Solitude profiles and psychological adjustment in Chinese late adolescence: a person-centered research
Objectives: From the perspective of person-centered research, the present study aimed to identify the potential profiles of solitude among late adolescents based on their solitary behavior, motivation, attitude, and time alone. In addition, to echo the paradox of solitude, we further explored the links between solitude profiles and adjustment outcomes.Methods: The participants of the study were 355 late adolescents (56.34% female, M age = 19.71 years old) at three universities in Shanghai, China. Measures of solitary behavior, autonomous motivation for solitude, attitude toward being alone, and time spent alone were collected using adolescents' self-report assessments. The UCLA Loneliness Scale, the Beck Depression Inventory, and the Basic Psychological Needs Scales were measured as indices of adjustment.Results: Latent profile analysis revealed four distinct groups: absence of the aloneness group (21.13%), the positive motivational solitude group (29.01%), the negative motivational solitude group (38.03%), and the activity-oriented solitude group (11.83%). Differences emerged among these four groups in terms of loneliness, depressive symptoms, and basic needs satisfaction, with adolescents in the negative motivational solitude group facing the most risk of psychological maladjustment.Conclusion: Findings revealed the possible heterogeneous nature of solitude among Chinese late adolescents and provided a theoretical basis for further understanding of adolescents' solitary state
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