Fast screening and diagnosis are critical in COVID-19 patient treatment. In addition to the gold standard RT-PCR, radiological imaging like X-ray and CT also works as an important means in patient screening and follow-up. However, due to the excessive number of patients, writing reports becomes a heavy burden for radiologists. To reduce the workload of radiologists, we propose DeltaNet to generate medical reports automatically. Different from typical image captioning approaches that generate reports with an encoder and a decoder, DeltaNet applies a conditional generation process. In particular, given a medical image, DeltaNet employs three steps to generate a report: 1) first retrieving related medical reports, i.e., the historical reports from the same or similar patients; 2) then comparing retrieved images and current image to find the differences; 3) finally generating a new report to accommodate identified differences based on the conditional report. We evaluate DeltaNet on a COVID-19 dataset, where DeltaNet outperforms state-of-the-art approaches. Besides COVID-19, the proposed DeltaNet can be applied to other diseases as well. We validate its generalization capabilities on the public IU-Xray and MIMIC-CXR datasets for chest-related diseases.

In the medical domain, gathering all data and training a global supervised model is very difficult due to scattered data from different hospitals and security and privacy concerns. In recent years, several federated learning models have been proposed for training over isolated data. These models usually employ a client-server framework: 1) train local models on clients in parallel; 2) aggregate local models on the server to produce a global one. By iterating the above two steps, federated learning aims to approximate the performance of a model centrally trained on data. However, due to the non-IID data distribution issue, local models could deviate from the optimal model resulting in a biased aggregated global model. To address this problem, we propose a contractible regularization (ConTre) to act on the local model’s latent space. On each client, we first project the input data into a latent space and then pose regularization to avoid converging too fast to bad local optima. The proposed regularization can be easily integrated into existing federated learning frameworks without bringing in additional parameters. According to experimental results on multiple natural and medical image datasets, the proposed ConTre can significantly improve the performance of various federated learning frameworks. Our code is available at https://github.com/czifan/ConTre.pytorch.

Psoriasis is a chronic skin disease which affects hundreds of millions of people around the world. This disease cannot be fully cured and requires lifelong caring. If the deterioration of Psoriasis is not detected and properly treated in time, it could cause serious complications or even lead to a life threat. Therefore, a quantitative measurement that can track the Psoriasis severity is necessary. Currently, PASI (Psoriasis Area and Severity Index) is the most frequently used measurement in clinical practices. However, PASI has the following disadvantages: (1) Time consuming: calculating PASI usually takes more than 30 minutes which poses a heavy burden on dermatologists; and (2) Inconsistency: due to the complexity of PASI calculation, different or even the same dermatologist could give different scores for the same case. To overcome these drawbacks, we propose PSENet which applies deep neural networks to estimate Psoriasis severity based on skin lesion images. Different from typical deep learning frameworks for image processing, PSENet has the following characteristics: (1) PSENet introduces a score refine module which is able to capture the visual features of skin at both coarse and fine-grained granularities; (2) PSENet uses siamese structure in training and accepts pairwise inputs, which reduces the dependency on large amount of training data; and (3) PSENet can not only estimate the severity, but also locate the skin lesion regions from the input image. To train and evaluate PSENet, we work with professional dermatologists from a top hospital and spend years in building a golden dataset. The experimental results show that PSENet can achieve the mean absolute error of 2.21 and the accuracy of 77.87% in pair comparison, outperforming baseline methods. Overall, PSENet not only relieves dermatologists from the dull PASI calculation but also enables patients to track Psoriasis severity in a much more convenient manner.

In this paper, we propose a new method to realize bidirectional visible light communication (VLC). We implement the bi-directional VLC system based on digital television terrestrial multimedia broadcasting-advanced (DTMB-A) and apply time-domain synchronous OFDM (TDS-OFDM) in the physical layer. A new type of APSK constellation with Gray mapping is used to provide a considerable shaping gain in both the independent demapping and the iterative demapping. Our system realizes the goal of bi- directional transmission between the station and the train, by which we could download driving data conveniently instead of getting on the vehicle. We also measure the output spectrum of photodetector and present our analysis. Through the experiment testing, the download rate of this bi-directional VLC system can achieve 63.67 Mb/s and the physical layer rate can reach 180Mb/s when two computers are connected through our system within the distance of 0.1m. With transmission distance exceeding 0.1m, the signal using 256APSK constellation mapping and 1/2 code rate can still be normally demodulated.

This thesis propose an algorithm which is based on the unmanned aerial vehicle (UAV) remote sensing images geometrical rectification model with the flight attitude parameters. The algorithm can make the flight attitude information of the UAV remote sensing images for the fast geometrical distortion rectification in the course of lacking the ground control points to carry on. The quality assessment of the geometrical rectification results of the model is performed through experimental comparison and analysis. Geometrical rectification algorithm can not only obtain high resolution remote sensing images with effective rectification immediately but also improve the quality, speed and accuracy of UAV remote sensing data processing and quantified disaster information extraction.