Enabling Efficient and Scalable Service Search in IoT With Topic Modeling: An Evaluation

Application-aware resource allocation and data management for MEC-assisted IoT service providers

A hybrid IoT services recommender system using social IoT

With the emerging of massive short texts, e.g., social media posts and question titles from Q&A systems, discovering valuable information from them is increasingly significant for many real-world applications of content analysis. The family of topic modeling can effectively explore the hidden structures of documents through the assumptions of latent topics. However, due to the sparseness of short texts, the existing topic models, e.g., latent Dirichlet allocation, lose effectiveness on them. To this end, an effective solution, namely Dirichlet multinomial mixture (DMM), supposing that each short text is only associated with a single topic, indirectly enriches document-level word co-occurrences. However, DMM is sensitive to noisy words, where it often learns inaccurate topic representations at the document level. To address this problem, we extend DMM to a novel Laplacian Dirichlet Multinomial Mixture (LapDMM) topic model for short texts. The basic idea of LapDMM is to preserve local neighborhood structures of short texts, enabling to spread topical signals among neighboring documents, so as to modify the inaccurate topic representations. This is achieved by incorporating the variational manifold regularization into the variational objective of DMM, constraining the close short texts with similar variational topic representations. To find nearest neighbors of short texts, before model inference, we construct an offline document graph, where the distances of short texts can be computed by the word mover’s distance. We further develop an online version of LapDMM, namely Online LapDMM, to achieve inference speedup on massive short texts. Carrying this implications, we exploit the spirit of stochastic optimization with mini-batches and an up-to-date document graph that can efficiently find approximate nearest neighbors instead. To evaluate our models, we compare against the state-of-the-art short text topic models on several traditional tasks, i.e., topic quality, document clustering and classification. The empirical results demonstrate that our models achieve very significant performance gains over the baseline models.

Topic modeling extracts useful potential topics that reflect market information from massive financial news and is widely used in data mining and economic research. Traditional topic modeling approaches such as Latent Dirichlet Allocation (LDA) and Non-Negative Matrix Factorization (NMF) lack semantic information, and short texts have feature sparse problems. We develop a topic clustering model based on BERT-LDA joint embedding that takes both contextual semantics and thematic narrative into account. We cluster document embeddings with the HDBSCAN algorithm and utilize a class-based TF-IDF (c-TF-IDF) method to create topic representations. Empirical results show that the BERT-LDA model is competitive compared with traditional and single topic models. It generates coherent topic words that are dissimilar to each other.

In this article, first a comprehensive study of the impact of term weighting schemes on the topic modeling performance (i.e., LDA and DMM) on Arabic long and short texts is presented. We investigate six term weighting methods including Word count method (standard topic models), TFIDF, PMI, BDC, CLPB, and CEW. Moreover, we propose a novel combination term weighting scheme, namely, CmTLB. We utilize the mTFIDF that takes into account the missing terms and the number of the documents in which the term appears when calculating the term weight. For further robust term weight, we combine mTFIDF with two weighting methods. We evaluate CmTLB against the studied weighting schemes by the quality of the learned topics (topic visualization and topic coherence), classification, and clustering tasks. We applied weighting schemes to Latent Dirichlet allocation (LDA) and Dirichlet multinomial mixture (DMM) on eight Arabic long and short document datasets, respectively. The experiment results outline that appropriate weighting schemes can effectively improve topic modeling performance on Arabic texts. More importantly, our proposed CmTLB significantly outperforms the other weighting schemes. Secondly, we investigate whether the Arabic stemming process can improve topic modeling performance. We study the three approaches of Arabic stemming including root-based, stem-based, and statistical approaches. We also train topic models with weighting schemes on documents after applying four stemmers related to different stemming approaches. The results outline that applying the stemming process not only reduces the dimensionality of term-document matrix leading to fast estimation process, but also show enhancement of topic modeling performance both on short and long Arabic documents. Moreover, Farasa stemmer achieves the highest performance in most cases, since it prevents the ambiguity that may happen because of the blind removal of the affixes such as in root-based or stem-based stemmers.

With the rapid development of social media and e-commerce on the Internet, many short texts such as instant messages, tweets and product comments have become an important form of Internet information. Compared with regular texts, short texts suffer severe data sparsity and informal format. Because of that, mining latent semantics such as topics in short texts is a critical challenge. There are many limitations directly applying common topic models like Latent Dirichlet Allocation (LDA) to short texts. In result of that, many short text topic models were put forward. The Word Network Topic Model (WNTM) is the typical one among them, which transfers sparse document to word space into dense word to word space and then learn topics from it. However, WNTM has its own limitation. The word co-occurrence matrix of the original document is used to construct the word network. This method is simple and intuitive, which can't express the deep meaning between words and words. To solve this problem, we proposed W2V-WNTM, which uses Word2Vec model instead of word co–occurrence to construct word network. Experiment shows it can describe relationship between words better.

In this paper, we propose a method for short text categorization using topic model and integrated classifier. To enrich the representation of short text, the Latent Dirichlet Allocation (LDA) model is used to extract latent topic information. While for classification, we combine two classifiers for achieving high reliability. Particularly, we train LDA models with variable number of topics using the Wikipedia corpus as external knowledge base, and extend labeled Web snippets by potential topics extracted by LDA. Then, the enriched representation of snippets are used to learn Maximum Entropy (MaxEnt) and support vector machine (SVM) classifiers separately. Finally, viewing that the most possible predicted result will appear in the top two candidates selected by MaxEnt classifier, we develop a novel scheme that if the gap between these candidates is large enough, the predicted result is considered to be reliable; otherwise, the SVM classifier will be integrated with MaxEnt classifier to make a comprehensive prediction. Experimental results show that our framework is effective and can outperform the state-of-the-art techniques.

More than 150 cellular networks worldwide have rolled out massive IoT services such as smart metering and environmental monitoring. Such cellular IoT services share the existing cellular network architecture with non-IoT (e.g., smartphone) ones. When they are newly integrated into the cellular network, new security vulnerabilities may happen from imprudent integration. In this work, we explore the security vulnerabilities of the cellular IoT from both system-integrated and service-integrated aspects. We discover five vulnerabilities spanning cellular standard design defects, network operation slips, and IoT device implementation flaws. Threateningly, they allow an adversary to remotely identify IP addresses and phone numbers assigned to cellular IoT devices and launch data/text spamming attacks against them. We experimentally validate these vulnerabilities and attacks with three major U.S. IoT carriers. The attack evaluation result shows that the adversary can raise an IoT data bill by up to $226 with less than 120 MB spam traffic and increase an IoT text bill at a rate of $5 per second; moreover, cellular IoT devices may suffer from denial of IoT services. We finally propose, prototype, and evaluate recommended solutions.

Internet of Things has become a common paradigm for various domains. To meet a user’s complex requirement, we should compose multiple IoT devices (IoT services) to provide comprehensive services to the user. However, these services usually coexist, which is likely to lead to conflicts. Moreover, each user may have different kinds of needs. Suppose that in a smart home there are more than one person, a conflict may occur when they request the same service in this environment. Actually, even though they request different IoT services, among which if there exists function impact or QoS impact, a conflict could still occur. In this paper, we propose to employ high-level Petri nets to detect conflicts among IoT services. We first model the formal methods for conflict policies. Then, we present a Petri nets-based mechanism for modeling and detecting conflicts. Finally, we expand the previous model and use high-level Petri nets for handling fuzzy IoT conflict policies modeling and reasoning. The experimental results show that the proposed approach performs well in accuracy.

Multi-label text classification is an increasingly important field as large amounts of text data are available and extracting relevant information is important in many application contexts. Probabilistic generative models are the basis of a number of popular text mining methods such as Naive Bayes or Latent Dirichlet Allocation. However, Bayesian models for multi-label text classification often are overly complicated to account for label dependencies and skewed label frequencies while at the same time preventing overfitting. To solve this problem we employ the same technique that contributed to the success of deep learning in recent years: greedy layer-wise training. Applying this technique in the supervised setting prevents overfitting and leads to better classification accuracy. The intuition behind this approach is to learn the labels first and subsequently add a more abstract layer to represent dependencies among the labels. This allows using a relatively simple hierarchical topic model which can easily be adapted to the online setting. We show that our method successfully models dependencies online for large-scale multi-label datasets with many labels and improves over the baseline method not modeling dependencies. The same strategy, layer-wise greedy training, also makes the batch variant competitive with existing more complex multi-label topic models.

A massive of text that is generated every minute is increasing dramatically. Therefore, it is more and more important to find an effective model to automatic classify the amount of text. Topic models is the most powerful techniques in text classification. There are many research results in the field of topic model have been published in scholarly journals. The Latent Dirichlet Allocation (LDA) is one of the most popular topic models in text classification. Researchers have proposed many topic evolution models based on LDA to solve some specific problems in applications of text classification. And some joint models which based on topic models combined other algorithms have been studied to enhance the performance of text classification. In this paper, we investigated three categories topic models for text classification and briefly introduced their advantages and disadvantages in the applications of text mining. Also, we introduce the generated process of documents and illustrate the graphical model for each topic models.

Short text differs from traditional documents in its shortness and sparseness. Feature extension can ease the problem of high sparseness in the vector space model, but it inevitably introduces noise. To resolve this problem, this paper proposes a high-frequency feature expansion method based on a latent Dirichlet allocation (LDA) topic model. High-frequency features are extracted from each category as the feature space, using LDA to derive latent topics from the corpus, and topic words are extended to the short text. Extensive experiments are conducted on Chinese short messages and news titles. The proposed method for classifying Chinese short texts outperforms conventional classification methods.

Integrating Big Data Into Evaluation: R Code for Topic Identification and Modeling

Background IoT and smart devices have become extremely popular in the last few years. With their capabilities to collect data, it is reasonable to have concerns about the protection of users’ personal information and privacy in general. Objectives Comparing existing regulations on data protection and information security rules with the new capabilities provided by IoT and smart devices. Methods/approach This paper will analyse information on data collected by IoT and smart devices and the corresponding legal framework to explore whether the legal framework also covers these new devices and their functionalities. Results Various IoT and smart devices pose a high risk to an individual's privacy. The General Data Protection Regulation, although a relatively recent law, may not adequately regulate all instances and uses of this technology. Also, due to inadequate technological protection, abuse of such devices by unauthorized persons is possible and even likely. Conclusions The number of IoT and smart devices is rapidly increasing. The number of IoT and smart home device security incidents is on the rise. The regulatory framework to ensure data controller and processor compliance needs to be improved in order to create a safer environment for new innovative IoT services and products without jeopardizing the rights and freedoms of data subjects. Also, it is important to increase awareness of homeowners about potential security threats when using IoT and smart devices and services.

Topic modelling is an important technique for extracting meaningful insights from large volumes of unstructured text data. The paper presents a federated technique for topic modelling that is based on a novel approach of the Latent Dirichlet Allocation (LDA) method for topic model generation. The proposed approach enables a topic model to be developed in a distributed environment using data continually generated from multiple sources without the need for sharing actual data. The first iteration of the topic modelling uses unsupervised LDA at each device generating the data. The results of each device are aggregated at a central server to generate a set of seed words that are used for guided LDA by the subsequent iterations of topic modelling. The proposed work, Federated LDA (F-LDA) has been evaluated using two datasets: a text dataset of dialogues between patients and doctors based on factual conversations and another comprising tweets related to depression. Comparing the performance of F-LDA with that of a centralized LDA, it was observed that F-LDA results in improved coherence score as well as diversity score in comparison to centralized LDA. This indicates that F-LDA achieves better interpretable topics covering a wide range of themes without redundancy.