32 research outputs found
3D-Aware Visual Question Answering about Parts, Poses and Occlusions
Despite rapid progress in Visual question answering (VQA), existing datasets
and models mainly focus on testing reasoning in 2D. However, it is important
that VQA models also understand the 3D structure of visual scenes, for example
to support tasks like navigation or manipulation. This includes an
understanding of the 3D object pose, their parts and occlusions. In this work,
we introduce the task of 3D-aware VQA, which focuses on challenging questions
that require a compositional reasoning over the 3D structure of visual scenes.
We address 3D-aware VQA from both the dataset and the model perspective. First,
we introduce Super-CLEVR-3D, a compositional reasoning dataset that contains
questions about object parts, their 3D poses, and occlusions. Second, we
propose PO3D-VQA, a 3D-aware VQA model that marries two powerful ideas:
probabilistic neural symbolic program execution for reasoning and deep neural
networks with 3D generative representations of objects for robust visual
recognition. Our experimental results show our model PO3D-VQA outperforms
existing methods significantly, but we still observe a significant performance
gap compared to 2D VQA benchmarks, indicating that 3D-aware VQA remains an
important open research area.Comment: Accepted by NeurIPS202
Long-term perturbations due to a disturbing body in elliptic inclined orbit
In the current study, a double-averaged analytical model including the action
of the perturbing body's inclination is developed to study third-body
perturbations. The disturbing function is expanded in the form of Legendre
polynomials truncated up to the second-order term, and then is averaged over
the periods of the spacecraft and the perturbing body. The efficiency of the
double-averaged algorithm is verified with the full elliptic restricted
three-body model. Comparisons with the previous study for a lunar satellite
perturbed by Earth are presented to measure the effect of the perturbing body's
inclination, and illustrate that the lunar obliquity with the value 6.68\degree
is important for the mean motion of a lunar satellite. The application to the
Mars-Sun system is shown to prove the validity of the double-averaged model. It
can be seen that the algorithm is effective to predict the long-term behavior
of a high-altitude Martian spacecraft perturbed by Sun. The double-averaged
model presented in this paper is also applicable to other celestial systems.Comment: 28 pages, 6 figure
Equilibria, periodic orbits around equilibria, and heteroclinic connections in the gravity field of a rotating homogeneous cube
This paper investigates the dynamics of a particle orbiting around a rotating
homogeneous cube, and shows fruitful results that have implications for
examining the dynamics of orbits around non-spherical celestial bodies. This
study can be considered as an extension of previous research work on the
dynamics of orbits around simple shaped bodies, including a straight segment, a
circular ring, an annulus disk, and simple planar plates with backgrounds in
celestial mechanics. In the synodic reference frame, the model of a rotating
cube is established, the equilibria are calculated, and their linear
stabilities are determined. Periodic orbits around the equilibria are computed
using the traditional differential correction method, and their stabilities are
determined by the eigenvalues of the monodromy matrix. The existence of
homoclinic and heteroclinic orbits connecting periodic orbits around the
equilibria is examined and proved numerically in order to understand the global
orbit structure of the system. This study contributes to the investigation of
irregular shaped celestial bodies that can be divided into a set of cubes.Comment: 29 pages, 16 figures, accepted for publication in Astrophysics &
Space Scienc
Periodic orbits in the gravity field of a fixed homogeneous cube
In the current study, the existence of periodic orbits around a fixed
homogeneous cube is investigated, and the results have powerful implications
for examining periodic orbits around non-spherical celestial bodies. In the two
different types of symmetry planes of the fixed cube, periodic orbits are
obtained using the method of the Poincar\'e surface of section. While in
general positions, periodic orbits are found by the homotopy method. The
results show that periodic orbits exist extensively in symmetry planes of the
fixed cube, and also exist near asymmetry planes that contain the regular Hex
cross section. The stability of these periodic orbits is determined on the
basis of the eigenvalues of the monodromy matrix. This paper proves that the
homotopy method is effective to find periodic orbits in the gravity field of
the cube, which provides a new thought of searching for periodic orbits around
non-spherical celestial bodies. The investigation of orbits around the cube
could be considered as the first step of the complicated cases, and helps to
understand the dynamics of orbits around bodies with complicated shapes. The
work is an extension of the previous research work about the dynamics of orbits
around some simple shaped bodies, including a straight segment, a circular
ring, an annulus disk, and simple planar plates.Comment: 23 pages, 10 figures, accepted for publication in Astrophysics &
Space Scienc
Tumor necrosis factor-α attenuates starvation-induced apoptosis through upregulation of ferritin heavy chain in hepatocellular carcinoma cells
An Efficient Self-Organized Detection System for Algae
Algal blooms have seriously affected the production and life of people and real-time detection of algae in water samples is a powerful measure to prevent algal blooms. The traditional manual detection of algae with a microscope is extremely time-consuming. In recent years, although there have been many studies using deep learning to classify and detect algae, most of them have focused on the relatively simple task of algal classification. In addition, some existing algal detection studies not only use small datasets containing limited algal species, but also only prove that object detection algorithms can be applied to algal detection tasks. These studies cannot implement the real-time detection of algae and timely warning of algal blooms. Therefore, this paper proposes an efficient self-organized detection system for algae. Benefiting from this system, we propose an interactive method to generate the algal detection dataset containing 28,329 images, 562,512 bounding boxes and 54 genera. Then, based on this dataset, we not only explore and compare the performance of 10 different versions of state-of-the-art object detection algorithms for algal detection, but also tune the detection system we built to its optimum state. In practical application, the system not only has good algal detection results, but also can complete the scanning, photographing and detection of a 2 cm × 2 cm, 0.1 mL algal slide specimen within five minutes (the resolution is 0.25886 μm/pixel); such a task requires a well-trained algal expert to work continuously for more than three hours. The efficient algal self-organized detection system we built makes it possible to detect algae in real time. In the future, with the help of IoT, we can use various smart sensors, actuators and intelligent controllers to achieve real-time collection and wireless transmission of algal data, use the efficient algal self-organized detection system we built to implement real-time algal detection and upload the detection results to the cloud to realize timely warning of algal blooms
A Fuzzy Expert System Architecture Implementing Onboard Planning and Scheduling for Autonomous Small Satellite
A crucial element in achieving small satellite fully autonomy is onboard automated planning and scheduling. Though lots of successful applications about it in spacecraft operations have recently been reported, and all of them are important for the development of this field, the inherent fuzziness and uncertainty of planning and scheduling was ignored made the achieving of onboard automated planning and scheduling system become idealization and no reality. In response to above-mentioned requirement, this paper presents an architecture which is developed using rules-based Fuzzy Expert System (FES). Fuzzy expert systems not only maintains the value of based rules and the merit of using fuzzy logic control to describe uncertainty systems, and utilizes the predominance of using expert systems to denote and control knowledge. In order to adapt the requirement of onboard operation, the resource restrain is considered in the architecture, such as processing speed of CPU, the capacity of storage and the real-time requirement. As the application of this architecture, this paper also describes an onboard automated planning and scheduling system in the SMMS, which is a small satellite of Research Institute of Satellite Engineering and Technology of Harbin Institute of Technology and will be launched in 2000