Online Time-Optimal Trajectory Generation for Two Quadrotors with Multi-Waypoints Constraints

The autonomous quadrotor's flying speed has kept increasing in the past 5 years, especially in the field of autonomous drone racing. However, the majority of the research mainly focuses on the aggressive flight of a single quadrotor. In this letter, we propose a novel method called Pairwise Model Predictive Control (PMPC) that can guide two quadrotors online to fly through the waypoints with minimum time without collisions. The flight task is first modeled as a nonlinear optimization problem and then an efficient two-step mass point velocity search method is used to provide initial values and references to improve the solving efficiency so that the method can run online with a frequency of 50 Hz and can handle dynamic waypoints. The simulation and real-world experiments validate the feasibility of the proposed method and in the real-world experiments, the two quadrotors can achieve a top speed of 8.1m/s in a 6-waypoint racing track in a compact flying arena of 6m*4m*2m

EMID: An Emotional Aligned Dataset in Audio-Visual Modality

In this paper, we propose Emotionally paired Music and Image Dataset (EMID), a novel dataset designed for the emotional matching of music and images, to facilitate auditory-visual cross-modal tasks such as generation and retrieval. Unlike existing approaches that primarily focus on semantic correlations or roughly divided emotional relations, EMID emphasizes the significance of emotional consistency between music and images using an advanced 13-dimension emotional model. By incorporating emotional alignment into the dataset, it aims to establish pairs that closely align with human perceptual understanding, thereby raising the performance of auditory-visual cross-modal tasks. We also design a supplemental module named EMI-Adapter to optimize existing cross-modal alignment methods. To validate the effectiveness of the EMID, we conduct a psychological experiment, which has demonstrated that considering the emotional relationship between the two modalities effectively improves the accuracy of matching in abstract perspective. This research lays the foundation for future cross-modal research in domains such as psychotherapy and contributes to advancing the understanding and utilization of emotions in cross-modal alignment. The EMID dataset is available at https://github.com/ecnu-aigc/EMID

Gradient Attention Balance Network: Mitigating Face Recognition Racial Bias via Gradient Attention

Although face recognition has made impressive progress in recent years, we ignore the racial bias of the recognition system when we pursue a high level of accuracy. Previous work found that for different races, face recognition networks focus on different facial regions, and the sensitive regions of darker-skinned people are much smaller. Based on this discovery, we propose a new de-bias method based on gradient attention, called Gradient Attention Balance Network (GABN). Specifically, we use the gradient attention map (GAM) of the face recognition network to track the sensitive facial regions and make the GAMs of different races tend to be consistent through adversarial learning. This method mitigates the bias by making the network focus on similar facial regions. In addition, we also use masks to erase the Top-N sensitive facial regions, forcing the network to allocate its attention to a larger facial region. This method expands the sensitive region of darker-skinned people and further reduces the gap between GAM of darker-skinned people and GAM of Caucasians. Extensive experiments show that GABN successfully mitigates racial bias in face recognition and learns more balanced performance for people of different races.Comment: Accepted by CVPR 2023 worksho

Amplification of light pulses with orbital angular momentum (OAM) in nitrogen ions lasing

Nitrogen ions pumped by intense femtosecond laser pulses give rise to optical amplification in the ultraviolet range. Here, we demonstrated that a seed light pulse carrying orbital angular momentum (OAM) can be significantly amplified in nitrogen plasma excited by a Gaussian femtosecond laser pulse. With the topological charge of +1 and -1, we observed an energy amplification of the seed light pulse by two orders of magnitude, while the amplified pulse carries the same OAM as the incident seed pulse. Moreover, we show that a spatial misalignment of the plasma amplifier with the OAM seed beam leads to an amplified emission of Gaussian mode without OAM, due to the special spatial profile of the OAM seed pulse that presents a donut-shaped intensity distribution. Utilizing this misalignment, we can implement an optical switch that toggles the output signal between Gaussian mode and OAM mode. This work not only certifies the phase transfer from the seed light to the amplified signal, but also highlights the important role of spatial overlap of the donut-shaped seed beam with the gain region of the nitrogen plasma for the achievement of OAM beam amplification.Comment: 10 pages, 7 figure

Fecal Microbiota Dynamics Reveal the Feasibility of Early Weaning of Yak Calves under Conventional Grazing System

Background: The gut microbiota plays an important role in the health and production of animals. However, little information is available on the dynamic variations and comparison of intestinal microbiota in post-weaning yak calves living on the QTP. Methods: We explored the fecal bacterial microbiota succession of yak calves at different months after early weaning (60 d) compared with cattle calves by 16S rRNA gene amplicon sequencing and functional composition prediction. Results: We found no significant difference in blood biochemical parameters related to glucose and lipid metabolism between yaks and calves in different months after weaning. The core fecal bacterial microbiota from both species of calves was dominated by Ruminococcaceae, Rikenellaceae, and Bacteroidaceae. The fecal microbial community has a great alteration within the time after weaning in both cattle and yak calves, but cattle showed a larger change. After five months, the microbiota achieves a stable and concentrated state. This is also similar to the functional profile. Conclusions: Based on the exploration of dynamic changes in the fecal microbiota at an early stage of life, our results illustrated that there were no negative effects of intestinal microbiota succession on yak calves when early weaning was employed

Association of vitamin D with HIV infected individuals, TB infected individuals, and HIV-TB co-infected individuals: a systematic review and meta-analysis

BackgroundVitamin D deficiency (VDD) is a worldwide disease. VDD is also associated with an increased risk of HIV-related comorbidities and mortality, and patients have a tendency to develop active tuberculosis compared to those with latent tuberculosis infection. Vitamin D supplementation may modulate HIV replication, improve TB inflammation and reduce progression of HIV-TB co-infection.MethodsWe meta-analyzed individual participant data from cohort studies, cross-sectional study, and RCTs of vitamin D in HIV group, TB group, and HIV-TB group. The primary outcomes were differences in vitamin D level and VDD prevalence between three groups, the secondary outcomes were CD4 count, HIV viral load, time to sputum smear conversion, time to culture conversion, relapse, morality, and TB score.ResultsFor vitamin D levels, the overall mean difference (MD) between HIV group and TB group was −0.21 (95% CI, −20.80–20.38; p = 0.9, I2 = 84%), HIV group and HIV-TB group was 0.87 (95% CI, −11.45–13.20; p = 0.89, I2 = 87%), and TB group and HIV-TB group was 1.17 (95% CI, −5.21–7.55; p = 0.72, I2 = 85%). For vitamin D deficiency prevalence, the overall odds ratio (OR) for HIV group versus TB group was 1.23 (95% CI, 0.46–3.31; p = 0.68; I2 = 70%), HIV group versus HIV-TB group was 1.53 (95% CI, 1.03–2.29; p = 0.04; I2 = 0%), and TB group versus HIV-TB group was 0.85 (95% CI, 0.61–1.20; p = 0.36; I2 = 22%). In HIV-TB group, the overall OR for vitamin D group versus placebo group was 0.78 (95% CI, 0.34–1.67; p = 0.52; I2 = 60%).ConclusionOur findings indicated that there were no variations in vitamin D levels between three groups. The prevalence of vitamin D deficiency was higher in the HIV-TB group than in the HIV group. Additionally, the administration of vitamin D supplements did not have obvious impact on CD4 count and viral load. Likewise, vitamin D had no effect on time to sputum smear conversion, time to culture conversion, relapse, 12-month morality, and TB score

Establishment and analysis of urban talent attraction evaluation model

Nowadays, the attraction to talents has become increasingly prodominent in determing the future development prospect of cities. How to quantify the attractiveness of cities to talents is an important issue in evaluating the comprehensive competitiveness of cities. This paper takes Xi’an and other emerging first-tier cities in China as the main research object, and classifies the indicators that affect the attractiveness of urban talents into five specific categories. A set of evaluation models are constructed by using entropy weight method, information entropy method and TOPSIS algorithm. The different indicators that measure the level of urban development are normalized and weighted to obtain the attractiveness index of urban talents to describe the attractiveness of talents in cities with similar development levels. To prove the rationality of the model, we apply this evaluation model to different cities and test its stability

Experimental Study on Interface Frictional Characteristics between Sand and Steel Pipe Jacking

In order to study the variation law of shear frictional characteristics of the steel pipe jacking and sand interface under different working conditions, the shear stress–strain curve between five different particle sizes of sand and steel pipe jacking under different normal stress and slurry lubrication conditions was measured by using a direct shear device, and the internal friction angle, friction coefficient and cohesion of the pipe–soil interface were calculated by regression analysis. The test results show that the shear stress between sand and steel pipe jacking decreases with the increase of the average particle size of the sand, and the strain-softening phenomenon occurs. The normal stress does not change the trend of the shear stress–strain curve at the pipe–soil interface, and the peak and residual values of the shear stress increase with the increase of the normal stress. The peak and residual values of the shear stress at the pipe–soil interface under the slurry lubrication condition are smaller than those under the no slurry lubrication condition. The peak shear stress between the pipe and soil under the lubricated slurry condition decreases by about 20%. The internal friction angle and friction coefficient of the pipe–soil interface decrease with the increase of the particle size, and there is no obvious pattern between the cohesion quantity relationship and the average particle size

Prediction and Control of Thermal Transport at Defective State Gr/<i>h</i>-BN Heterojunction Interfaces

The control of interfacial thermal conductivity is the key to two−dimensional heterojunction in semiconductor devices. In this paper, by using non−equilibrium molecular dynamics (NEMD) simulations, we analyze the regulation of interfacial thermal energy transport in graphene (Gr)/hexagonal boron nitride (h-BN) heterojunctions and reveal the variation mechanism of interfacial thermal energy transport. The calculated results show that 2.16% atomic doping can effectively improve interfacial heat transport by more than 15.6%, which is attributed to the enhanced phonon coupling in the mid−frequency region (15–25 THz). The single vacancy in both N and B atoms can significantly reduce the interfacial thermal conductivity (ITC), and the ITC decreases linearly with the increase in vacancy defect concentration, mainly due to the single vacancy defects leading to an increased phonon participation rate (PPR) below 0.4 in the low-frequency region (0–13 THz), which shows the phonon the localization feature, which hinders the interfacial heat transport. Finally, a BP neural network algorithm is constructed using machine learning to achieve fast prediction of the ITC of Gr/h-BN two-dimensional heterogeneous structures, and the results show that the prediction error of the model is less than 2%, and the method will provide guidance and reference for the design and optimization of the ITC of more complex defect-state heterogeneous structures

Research on color planning of campus buildings in Shenyang Jianzhu University

This paper is based on the perspective of regional architectural color planning and selecting campus buildings in cold regions as an example, taking architectural color as the research object, making a multi-viewpoint research on the use of color and its influencing factors. This article conducts actual investigation on the color of exterior facades of buildings in different areas of Shenyang Jianzhu University Campus, systematic evaluation and suggestion on architectural color of Shenyang Jianzhu University on the basis of Munsell color solid system