With rising environmental concerns, accurate air quality predictions have become paramount as they help in planning preventive measures and policies for potential health hazards and environmental problems caused by poor air quality. Most of the time, air quality data are time series data. However, due to various reasons, we often encounter missing values in datasets collected during data preparation and aggregation steps. The inability to analyze and handle missing data will significantly hinder the data analysis process. To address this issue, this paper offers an extensive review of air quality prediction and missing data imputation techniques for time series, particularly in relation to environmental challenges. In addition, we empirically assess eight imputation methods, including mean, median, kNNI, MICE, SAITS, BRITS, MRNN, and Transformer, to scrutinize their impact on air quality data. The evaluation is conducted using diverse air quality datasets gathered from numerous cities globally. Based on these evaluations, we offer practical recommendations for practitioners dealing with missing data in time series scenarios for environmental data.

The air quality index (AQI) forecast in big cities is an exciting study area in smart cities and healthcare on the Internet of Things. In recent years, a large number of empirical, academic, and review papers using machine learning (ML) for air quality analysis have been published. However, most of those studies focused on traditional centralized processing on a single machine, and there had been few surveys of federated learning (FL) in this field. This overview aims to fill this gap and provide newcomers with a broader perspective to inform future research on this topic, especially for the multi-model approach. In this survey, we went over the works that previous scholars have conducted in AQI forecast both in traditional ML approaches and FL mechanisms. Our objective is to comprehend previous research on AQI prediction including methods, models, data sources, achievements, challenges, and solutions applied in the past. We also convey a new path of using multi-model FL, which has piqued the computer science community’s interest recently.

Information disorder is one of the most typical challenges in the current era of science and technology. The amount of information on the internet is increasing, but its correctness and authenticity are not always guaranteed, leading to false information, fake news, etc. The mentioned problem negatively affects users' reception and use of information. Unlike deepfake, cheapfake is created using simple techniques and does not rely on AI to produce fake multimedia. Cheapfake is becoming increasingly popular due to its ease of creation. Thus, there is a growing need to develop techniques that can detect cheapfake content. Following previous events, the Grand Challenge on Detecting Cheapfakes at ACM ICMR 2024 continues to seek contributions from researchers on cheapfake detection with the goal of improving effectiveness and creativity in approach, and understanding the limitations of the current dataset. This challenge has accepted 6 new proposed methods from participants with the highest private test accuracies achieved at 72.2% for Task 1 and 54.84% for Task 2. The highest public test accuracies for the two tasks are 95.6% and 93% respectively. These new methods focus on incorporating new AI models such as Stable Diffusion, LLM. These new findings represent the latest advancements in cheapfake detection research and introduce new potential approaches for future research.

The explosive growth of the social media community has increased many kinds of misinformation and is attracting tremendous attention from the research community. One of the most prevalent ways of misleading news is cheapfakes. Cheapfakes utilize non-AI techniques such as unaltered images with false context news to create false news, which makes it easy and “cheap” to create and leads to an abundant amount in the social media community. Moreover, the development of deep learning also opens and invents many domains relevant to news such as fake news detection, rumour detection, fact-checking, and verification of claimed images. Nevertheless, despite the impact on and harmfulness of cheapfakes for the social community and the real world, there is little research on detecting cheapfakes in the computer science domain. It is challenging to detect misused/false/out-of-context pairs of images and captions, even with human effort, because of the complex correlation between the attached image and the veracity of the caption content. Existing research focuses mostly on training and evaluating on given dataset, which makes the proposal limited in terms of categories, semantics and situations based on the characteristics of the dataset. In this paper, to address these issues, we aimed to leverage textual semantics understanding from the large corpus and integrated with different combinations of text-image matching and image captioning methods via ANN/Transformer boosting schema to classify a triple of (image, caption₁, caption₂) into OOC (out-of-context) and NOOC (no out-of-context) labels. We customized these combinations according to various exceptional cases that we observed during data analysis. We evaluate our approach using the dataset and evaluation metrics provided by the COSMOS baseline. Compared to other methods, including the baseline, our method achieves the highest Accuracy, Recall, and F1 scores.

Detecting Cheapfakes often requires identifying contextual changes in media resulting from misleading captions. Cheapfake media can be created either by manipulating the content using image or video editing software, or by altering the context of an image or video through misleading claims, without relying on any software. While previous research has shown promising results, these approaches are limited to the data used during training. To overcome this limitation, we propose a Self-Query Adaptive-Context Learning method that is flexible and capable of adapting to new contexts during inference by using image search engine queries to enrich its knowledge. By verifying the context of captions based on the collected information, our approach extends knowledge in a flexible manner. Despite achieving an experimental accuracy of 59.70% on the IEEE ICME 2023 Cheapfakes Challenge dataset, our work has opened up new avenues for detecting out-of-context misuses.