Spectral Reflectance Indices (SRIs) have emerged as a powerful tool for unraveling and deciphering critical information about land cover, vegetation health, water quality, soil characteristics, etc. This approach provides valuable insights for sustainable resource management, agricultural optimizations, etc. However, vast list of available spectral indices makes it challenging to choose most relevant ones for a specific application. Identification of relevant SRIs for an application needs domain experts to analyze the information obtained from indices. Existing studies have used SRIs in a limited way - 1) as a single value for a location (county) and thus suffer from loss of spatial information; 2) only few popular spectral indices e.g. NDVI, SAVI, NDWI, etc. are exploited; 3) have been used for applications like crop yield and snow cover prediction. To circumvent these limitations, we embarked on three novel ideas - 1) compute spectral indices at pixel level of the satellite image resulting in an SRI image for a region; 2) introduce a selection method which selects SRIs relevant to a given application; 3) design a model called Spectral Indices Network, SpInN, utilizing two transformers ViViT and BERT. We use ViViT innovatively on different SRI images treating them as video frames for spatio-spectral index learning. We also use BERT to exploit temporal patterns of the spectral index time series. The proposed model is applied to various prediction and classification earth observation applications such as prediction of crop yield, solar energy, soil moisture, land cover classification, etc., and obtained state-of-the-art results.

Set-wise Clustering is a clustering technique for data streams that groups sets of objects based on distribution patterns, applicable in contexts like retail chain clustering, text-based community clustering, restaurant categorization, etc. The existing set-wise clustering method cannot handle variable and high-speed streams with reasonable accuracy. This paper presents an Anytime Set-wise Clustering method for data streams known as ANYSETCLUS. The method handles the variable inter-arrival rates of stream objects using a proposed indexing structure called AnySetClusTree, which stores a hierarchy of micro-clusters of multi-set entities at varying granularity. ANYSETCLUS is highly adaptive as it supports incremental model updates, segregates outliers, enables outlier-to-concept transition, and captures concept drift. The method also enables anytime offline clustering wherein it can generate multiple clusterings of varying granularity and purity depending upon the available time allowance for final clustering. The experimental results affirm the superior efficacy of the proposed method in handling variable and high-speed streams compared to the state-of-the-art method. The experimental results also showcase its effectiveness in achieving significantly higher micro-cluster purity for low and high-speed streams. This contrasts with the state-of-the-art method, which is unable to generate valid clustering results for high-speed streams. The experiments further validate the proposed method’s capability for anytime offline clustering.

Recent years have seen some of the largest forest fires ever, including the 2020 California megafires and the Australian bushfires, causing billions of dollars in property damage and destroying millions of acres of green reserves. The subject of forest fires becomes even more alarming when viewed in conjunction with the increasingly concerning problems of climate change and global warming. The planning regarding prevention and mitigation of forest fires and management of nearby areas can greatly benefit from an accurate prediction model. The objective of this study is to develop deep learning models which use satellite images and meteorological data to pinpoint potential fires at a pixel granularity. Data from the recently launched Landsat-8 and Landsat-9 satellite systems have been used to predict forest fires at a spatial resolution of 30m. The proposed solution uses the comprehensive geographical, meteorological, and MODIS-based fire history of the region, integrated from different data sources with pixel-level reprojection, as a multivariate time series (MVTS) to model the prediction problem as a binary classification problem. We adopt an encoder-classifier architecture: the BiLSTM-attention-based encoder is trained with supervised contrastive learning, while the fully-connected classifier is optimized against a weighted loss for increased recall. Our experiments demonstrate that the proposed model is robust to spatial and temporal variations in occurrence of fires, thereby making its deployment possible in any region of the world. With a mean AUC of 0.99, our proposed model outperforms the existing forest fire prediction models.

Satellite data provides valuable insights into environmental changes and natural resource management, such as monitoring deforestation, mapping land use changes, and identifying areas at risk of soil degradation. Landsat-8 and Sentine1-2 are the publicly available high spatial resolution satellites launched in recent years. But, both have a moderate temporal resolution which limits their use in the applications like precision agriculture, land cover mapping, disaster monitoring, etc. For such applications, daily or weekly monitoring is better suited. Fusing data from the two satellites can provide enhanced observations. Both Landsat-8 and Sentine1-2 satellites have the same geographic coordinate systems which makes them amiable for fusion. But, fusing data at the pixel level for these satellites is challenging as they visit the same location on different days. The proposed model `LSFuseNet’ effectively fuses data at the feature level. It is a dual-fusion model in which bi-directional cross-modal attention is used to identify and exchange the hotspot information in the two modalities. A feature alignment module learns the fine-grained features and mitigates the noise in the data. We have innovatively applied contrastive learning to improve the quality of the learned representations of the data from the two satellites. We evaluate our model for two applications - crop yield prediction and snow cover prediction. For crop yield prediction, we have taken two crops, viz. corn, and soybean, for approximately 500 counties in the US. For snow cover prediction, we considered approximately 1300 US counties. Our extensive experiments show that LSFuseNet outperforms competing models. Also, the benefit of fusing the data from two satellites over using the data from a single satellite is evident from the results of both applications. We have further modified the model to include meteorological and/or soil data (if applicable) to further enhance the performance of the model.

Stream Clustering algorithms have gained a lot of importance in the recent past due to rapid rising utilities of IoT systems and applications. Anytime algorithms and frameworks play a key role in handling streams that have data arriving/generating at variable rates. They are capable of handling both slow and fast stream speeds, at the same time generate the result with highest possible accuracy. In this paper, we present AnyStreamKM, which is a framework for anytime k-medoids clustering of data streams. It uses a proposed hierarchical data indexing structure known as AnyKMTree that stores the incoming data from the stream in the form of hierarchy of micro-clusters. AnyKMTree is an adaptation of R-tree with its splitting strategy inspired from the design principles of k-medoids clustering. AnyKMTree not only supports anytime features but is also capable of filtering out noise and outliers. Our experimental analysis establishes that AnyKMTree produces micro-clusters that are more compact and purer than the state-of-the-art methods. Also, when offline k-medoids clustering such as PAM (Partitioning Around Medoids) is applied on the micro-clusters produced by AnyKMTree, the resultant clustering has been found to be of higher quality than the state-of-the-art methods.

Early crop yield prediction is crucial in agriculture for making administrative plans to ensure food security, post harvest management and distribution of a crop. Remote sensing data captured using various satellites provide reliable phenological information for a crop through surface reflectance bands. Other important factors, affecting crop yield include meteorological and soil. The data which we have used for crop yield prediction is multimodal. It consists of spatiotemporal meteorological (numeric) and surface reflectance bands (satellite image), and temporally static soil (satellite image) data. We effectively utilize this multimodal data to develop the proposed multimodal deep learning model, CropYieldNet. The objective of the paper is to accurately predict crop yield using high resolution data obtained from recently launched satellites such as Landsat8 and Sentinel-2. We used contrastive learning in a supervised setting and data augmentation techniques to overcome the limited historical data available for training deep learning models.We introduce a depth-level selection module for effectively modelling the depth-variant information of soil data. We have also modified our model to perform in-season (early) crop yield prediction which is as accurate as end-season prediction. We evaluate our model for two crops, corn and soybean, on counties in US and districts in India using data from MODIS, Landsat8, and Sentinel-2 satellites. Our extensive experimentation show that our model outperforms competing models. Our experiments also show that CropYieldNet generalizes well when applied on different crops and geographies.

Malicious Webpages have been a serious threat on Internet for the past few years. As per the latest Google Transparency reports, they continue to be top ranked amongst online threats. Various techniques have been used till date to identify malicious sites, to include, Static Heuristics, Honey Clients, Machine Learning, etc. Recently, with the rapid rise of Deep Learning, an interest has aroused to explore Deep Learning techniques for detecting Malicious Webpages. In this paper Deep Learning has been utilized for such classification. The model proposed in this research has used a Deep Neural Network (DNN) with two hidden layers to distinguish between Malicious and Benign Webpages. This DNN model gave high accuracy of 99.81% with very low False Positives (FP) and False Negatives (FN), and with near real-time response on test sample. The model outperformed earlier machine learning solutions in accuracy, precision, recall and time performance metrics.

The Android platform has emerged as the most popular computing platform that has more than 2.5 billion devices [1] working across the globe. These devices include not only mobiles and tablets, but even Android Auto modules in cars, various Android versions running on Televisions, watches and host of other smart devices. What makes things more challenging and interesting for the Android Developers and security experts is the fact that various versions of Android Operating System, from Android 2.3.3 (Ginger Bread) to Android 11.0 coexist in this ecosystem. This paper discusses threats that emanate from Hybrid Android Apps. These Hybrid Apps use WebView Component for handling web content within Android Apps. WebView allows HTML and JavaScript to run and render webpages inside Apps, thereby allowing them to download content from Web Servers on the Internet. It is used by several popular Apps, like Facebook, Twitter, Instagram, etc. WebView even allows JavaScript code to call Android code for completing various tasks. While this feature gives tremendous capability to create interactive Hybrid Apps, however, it also opens a route for malicious content to infect the Android Platform using targeted JavaScript based malwares. Any malicious JavaScript, from untrusted or even from trusted source, can thus find its way to exploit this unique linkage with Android Platform. In this paper we analyze Android Web View's security vulnerabilities, access authorization, kind of attacks that it can encounter, and mechanisms to prevent these attacks. To do so, we have developed two Android Apps, viz., "WebView Tool" and "WebView Monitor". Our analysis and detection mechanisms are based on Machine Learning techniques.

Hierarchical Agglomerative Clustering (HAC) algorithms are used in many applications where clusters have a hierarchical relationship between them. Their parallelization is challenging due to the dependence of every agglomeration step on all previous agglomerations. Although a few parallel algorithms have been proposed for SLINK HAC algorithm, only limited work has been done to parallelize other HAC algorithms. In this paper, we present a high-level abstraction, which provides a uniform way to specify any HAC algorithm, and a framework for automatic parallelization of the same for distributed memory systems. The abstraction is supported by constructs in a high level, domain specific language, and a compiler translates algorithms expressed in this language to efficient parallel code targeting distributed systems. Our experiments on multiple HAC algorithms proves that the runtime performance achieved is comparable with state-of-the-art manual parallel implementations on Spark and MPI while requiring only a fraction of the programming effort. At runtime, master-slave execution is used, and load is balanced among the slaves in an algorithm-agnostic way, which is a significant contrast to custom load-balancing techniques seen in the literature on parallel HAC algorithms.

Big Data has significantly increased the dependence of data analytics community on High Performance Computing (HPC) systems. However, efficiently programming an HPC system is still a tedious task requiring specialized skills in parallelization and the use of platform-specific languages as well as mechanisms. We present a framework for quickly prototyping new/existing density-based clustering algorithms while obtaining low running times and high speedups via automatic parallelization. The user is required only to specify the sequential algorithm in a Domain Specific Language (DSL) for clustering at a very high level of abstraction. The parallelizing compiler for the DSL does the rest to leverage distributed systems - in particular, typical scale-out clusters made of commodity hardware. Our approach is based on recurring, parallelizable programming patterns known as Kernels, which are identified and parallelized by the compiler. We demonstrate the ease of programming and scalable performance for DBSCAN, SNN, and RECOME algorithms. We also establish that the proposed approach can achieve performance comparable to state-of-the-art manually parallelized implementations while requiring minimal programming effort that is several orders of magnitude smaller than those required on other parallel platforms like MPI/Spark.

Classification of data streams has gained a lot of popularity in recent years owing to its multiple applications. In certain applications like community detection from text feeds, website fingerprinting attack, etc., it is more meaningful to associate class labels with groups of objects rather than the individual objects. This kind of classification problem is known as the set-wise classification problem. The few algorithms available in literature for this problem are budget algorithms, i.e. they are designed to process fixed maximum stream speed, and are not capable of handling variable and high speed streams. We present ANYSC which is the first anytime set-wise classification algorithm for data streams. ANYSC handles variable inter-arrival rate of objects in the stream and performs classification of test entities within any available time allowance, using a proposed data structure referred to as CProf-forest. The experimental results show that ANYSC brings in the features of an anytime algorithm and outperforms the existing approaches.

Ancient Sanskrit manuscripts are a rich source of knowledge about Science, Mathematics, Hindu mythology, Indian civilization, and culture. It therefore becomes critical that access to these manuscripts is made easy, to share this knowledge with the world and to facilitate further research on this Ancient literature. In this paper, we propose a Convolutional Neural Network (CNN) based Optical Character Recognition system (OCR) which accurately digitizes Ancient Sanskrit manuscripts (Devanagari Script) that are not necessarily in good condition. We use an image segmentation algorithm for calculating pixel intensities to identify letters in the image. The OCR considers typical compound characters (half letter combinations) as separate classes in order to improve the segmentation accuracy. The novelty of the OCR is its robustness to image quality, image contrast, font style and font size, which makes it an ideal choice for digitizing soiled and poorly maintained Sanskrit manuscripts.

Ease of programming and optimal parallel performance have historically been on the opposite side of a tradeoff, forcing the user to choose. With the advent of the Big Data era and rapid evolution of sequential algorithms, the data analytics community can no longer afford the tradeoff. We observed that several clustering algorithms often share common traits - particularly, algorithms belonging to same class of clustering exhibit significant overlap in processing steps. Here, we present our observation on domain patterns in Representative-based clustering algorithms and how they manifest as clearly identifiable programming patterns when mapped to a Domain Specific Language (DSL). We have integrated the signatures of these patterns in the DSL compiler for parallelism identification and automatic parallel code generation. Our experiments on different state-of-the-art parallelization frameworks shows that our system is able to achieve near-optimal speedup while requiring a fraction of the programming effort, making it an ideal choice for the data analytics community.

With the rising prevalence of social media, coupled with the ease of sharing images, people with specific needs and applications such as known item search, multimedia question answering, etc., have started searching for visual content, which is expressed in terms of complex queries. A complex query consists of multiple concepts and their attributes are arranged to convey semantics. It is less effective to answer such queries by simply appending the search results gathered from individual or subsets of concepts present in the query. In this paper, we propose to exploit the query constituents and relationships among them. The proposed approach finds image-query relevance by integrating three models - the linguistic pattern-based textual model, the visual model, and the cross modality model. We extract linguistic patterns from complex queries, gather their related crawled images, and assign relevance scores to images in the corpus. The relevance scores are then used to rank the images. We experiment on more than 140k images and compare the [email protected] scores with the state-of-the-art image ranking methods for complex queries. Also, ranking of images obtained by our approach outperforms than that of obtained by a popular search engine.

Mining frequent itemsets from transactional data streams has been vastly studied in literature. The existing algorithms mine frequent itemsets within the stream's constrained environment of limited time and memory. However, none of them are capable of handling varying inter-arrival rates of streams. Moreover, these algorithms are not capable of giving mining results instantaneously, even with compromised accuracy if required, and improve the accuracy with increase in time allowance. These two properties characterize an anytime algorithm. In this paper, we propose AnyFI, which is the first anytime frequent itemset mining algorithm for data streams. We also propose a novel data structure, BFI-forest, which is capable of handling transactions with varying inter-arrival rate. AnyFI maintains itemsets in BFI-forest in such a way that it can give a mining result almost immediately when time allowance to mine is very less and can refine the results for better accuracy with increase in time allowance. Our experimental results show that AnyFI can handle high stream speeds upto 60,000 transactions per second (tps) with recall close to 100%.

Parallelizing data mining algorithms has become a necessity as we try to mine ever increasing volumes of data. Spatial data mining algorithms like Dbscan, Optics, Slink, etc. have been parallelized to exploit a cluster infrastructure. The efficiency achieved by existing algorithms can be attributed to spatial locality preservation using spatial indexing structures like k-d-tree, quad-tree, grid files, etc. for distributing data among cluster nodes. However, these indexing structures are static in nature, i.e., they need to scan the entire dataset to determine the partitioning coordinates. This results in high data distribution cost when the data size is large. In this paper, we propose a dynamic distributed data structure, DD-Rtree, which preserves spatial locality while distributing data across compute nodes in a shared nothing environment. Moreover, DD-Rtree is dynamic, i.e., it can be constructed incrementally making it useful for handling big data. We compare the quality of data distribution achieved by DD-Rtree with one of the recent distributed indexing structure, SD-Rtree. We also compare the efficiency of queries supported by these indexing structures along with the overall efficiency of DBSCAN algorithm. Our experimental results show that DD-Rtree achieves better data distribution and thereby resulting in improved overall efficiency.

Clustering is a popular data mining and machine learning technique which discovers interesting patterns from unlabeled data by grouping similar objects together. Clustering high-dimensional data is a challenging task as points in high dimensional space are nearly equidistant from each other, rendering commonly used similarity measures ineffective. Subspace clustering has emerged as a possible solution to the problem of clustering high-dimensional data. In subspace clustering, we try to find clusters in different subspaces within a dataset. Many subspace clustering algorithms have been proposed in the last two decades to find clusters in multiple overlapping subspaces of high-dimensional data. Subspace clustering algorithms iteratively find the best subset of dimensions for a cluster from 2d-1 possible combinations in d-dimensional data. Subspace clustering is extremely compute intensive because of exhaustive search of subspaces, especially in the bottom-up subspace clustering algorithms. To address this issue, an efficient parallel framework for grid-based bottom-up subspace clustering algorithms is developed, considering popular algorithms belonging to this category. The framework is implemented for shared memory, distributed memory, and hybrid systems and is tested for three grid-based bottom-up subspace clustering algorithms: CLIQUE, MAFIA, and ENCLUS. All parallel implementations exhibit impressive speedup and scalability on real datasets.