8,152 research outputs found
Relation between vibrotactile perception thresholds and reductions in finger blood flow induced by vibration of the hand at frequencies in the range 8–250 Hz
Purpose: this study investigated how the vasoconstriction induced by vibration depends on the frequency of vibration when the vibration magnitude is defined by individual thresholds for perceiving vibration [i.e. sensation levels (SL)].Methods: fourteen healthy subjects attended the laboratory on seven occasions: for six vibration frequencies (8, 16, 31.5, 63, 125, or 250 Hz) and a static control condition. Finger blood flow (FBF) was measured in the middle fingers of both hands at 30-second intervals during five successive periods: (i) no force or vibration, (ii) 2-N force, no vibration, (iii) 2-N force, vibration, (iv) 2-N force, no vibration, (v) no force or vibration. During period (iii), vibration was applied to the right thenar eminence via a 6-mm diameter probe during ten successive 3-min periods as the vibration magnitude increased in ten steps (?10 to +40 dB SL).Results: with vibration at 63, 125, and 250 Hz, there was vasoconstriction on both hands when the vibration magnitude reached 10 dB SL. With vibration at 8, 16, and 31.5 Hz, there was no significant vasoconstriction until the vibration reached 25 dB SL. At all frequencies, there was greater vasoconstriction with greater magnitudes of vibration.Conclusions: it is concluded that at the higher frequencies (63, 125, and 250 Hz), the Pacinian channel mediates vibrotactile sensations near threshold and vasoconstriction occurs when vibration is perceptible. At lower frequencies (8, 16, and 31.5 Hz), the Pacinian channel does not mediate sensations near threshold and vasoconstriction commences at greater magnitudes when the Pacinian channel is activate
Real-Time RGB-D based Template Matching Pedestrian Detection
Pedestrian detection is one of the most popular topics in computer vision and
robotics. Considering challenging issues in multiple pedestrian detection, we
present a real-time depth-based template matching people detector. In this
paper, we propose different approaches for training the depth-based template.
We train multiple templates for handling issues due to various upper-body
orientations of the pedestrians and different levels of detail in depth-map of
the pedestrians with various distances from the camera. And, we take into
account the degree of reliability for different regions of sliding window by
proposing the weighted template approach. Furthermore, we combine the
depth-detector with an appearance based detector as a verifier to take
advantage of the appearance cues for dealing with the limitations of depth
data. We evaluate our method on the challenging ETH dataset sequence. We show
that our method outperforms the state-of-the-art approaches.Comment: published in ICRA 201
Extension of incompressible surfaces on the boundary of 3-manifolds
An incompressible surface on the boundary of a compact orientable
3-manifold is arc-extendible if there is an arc on
Int such that is incompressible, where is a
regular neighborhood of in . Suppose for simplicity that
is irreducible, and has no disk components. If is a product
, or if is a set of annuli, then clearly is not
arc-extendible. The main theorem of this paper shows that these are the only
obstructions for to be arc-extendible
Triplet-based Deep Similarity Learning for Person Re-Identification
In recent years, person re-identification (re-id) catches great attention in
both computer vision community and industry. In this paper, we propose a new
framework for person re-identification with a triplet-based deep similarity
learning using convolutional neural networks (CNNs). The network is trained
with triplet input: two of them have the same class labels and the other one is
different. It aims to learn the deep feature representation, with which the
distance within the same class is decreased, while the distance between the
different classes is increased as much as possible. Moreover, we trained the
model jointly on six different datasets, which differs from common practice -
one model is just trained on one dataset and tested also on the same one.
However, the enormous number of possible triplet data among the large number of
training samples makes the training impossible. To address this challenge, a
double-sampling scheme is proposed to generate triplets of images as effective
as possible. The proposed framework is evaluated on several benchmark datasets.
The experimental results show that, our method is effective for the task of
person re-identification and it is comparable or even outperforms the
state-of-the-art methods.Comment: ICCV Workshops 201
Object Recognition from very few Training Examples for Enhancing Bicycle Maps
In recent years, data-driven methods have shown great success for extracting
information about the infrastructure in urban areas. These algorithms are
usually trained on large datasets consisting of thousands or millions of
labeled training examples. While large datasets have been published regarding
cars, for cyclists very few labeled data is available although appearance,
point of view, and positioning of even relevant objects differ. Unfortunately,
labeling data is costly and requires a huge amount of work. In this paper, we
thus address the problem of learning with very few labels. The aim is to
recognize particular traffic signs in crowdsourced data to collect information
which is of interest to cyclists. We propose a system for object recognition
that is trained with only 15 examples per class on average. To achieve this, we
combine the advantages of convolutional neural networks and random forests to
learn a patch-wise classifier. In the next step, we map the random forest to a
neural network and transform the classifier to a fully convolutional network.
Thereby, the processing of full images is significantly accelerated and
bounding boxes can be predicted. Finally, we integrate data of the Global
Positioning System (GPS) to localize the predictions on the map. In comparison
to Faster R-CNN and other networks for object recognition or algorithms for
transfer learning, we considerably reduce the required amount of labeled data.
We demonstrate good performance on the recognition of traffic signs for
cyclists as well as their localization in maps.Comment: Submitted to IV 2018. This research was supported by German Research
Foundation DFG within Priority Research Programme 1894 "Volunteered
Geographic Information: Interpretation, Visualization and Social Computing
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