Sequential Database Research Articles

A spatiotemporal feature fusion-based deep learning framework for synchronous prediction of excavation stability

Under rapid urbanization, analyzing and perceiving synchronous excavation stability is essential to generate valuable and foresightful information in identifying and mitigating potential risks in deep excavations. Although the existing forecasting methods can achieve high accuracy in the safety state perception of deep excavations, it is prone to lack proper consideration of the monitoring item’s fusion and cause error and uncertainty via the single-parameter risk evaluation. To address it, this paper proposes a spatiotemporal feature fusion-based deep learning (FFDL) framework to implement the feature fusion-based data analysis and time-series forecasting on the factor of safety (FS) on behalf of excavation stability, and global sensitivity analysis. The fusion indicators and proposed FFDL framework are validated through a comprehensive case study encompassing 100 typical metro station constructions. The feature fusion-based data analysis results confirm the statistical significance of fusion indicators, contributing to establishing a high-quality spatiotemporal sequential database. As for the real-time prediction, the Bayesian optimization CNN-LSTM model provides a reliable prediction of excavation stability and the relative errors in the training and testing datasets do not exceed 1% and 3% in construction duration. It also enhances the predictive accuracy and outperforms the existing models LSTM, GRU, BiLSTM, and CNN-LSTM, reaching an average improvement of 38%, 32%, and 32% in RMSE, MAE, and MAPE, respectively. Furthermore, the proposed model has an excellent generalization performance in accurately predicting the excavation stability of the other ten excavation cases with an average relative error of 5.37%. In short, this work contributes to not only providing a new perspective in risk management by integrating feature fusion-based indicators and excavation stability but also verifying the applicability of the proposed framework.

Mining frequent temporal duration-based patterns on time interval sequential database

Sequential databases have wide applications, such as market basket analysis, medical prediction, and sign language recognition. Most prior research is based on pointed-based sequential databases, which assume each item/event occurs instantaneously. However, in many real-world scenarios, events persist over intervals of varying durations, such as varying time intervals of a symptom or a gesture of sign language. Assigning the same weight to different times of events and neglecting the duration of events can hinder the recognition of interesting patterns, such as concurrent symptoms preceding a disease. To address these issues, this paper integrates duration with temporal patterns in interval-based sequential databases, introduces the concept of temporal duration-based patterns (TDPs), and designs two algorithms called FTDPMiner-EP (Frequent TDPMiner based on endpoint representation) and FTDPMiner-TM (Frequent TDPMiner based on triangular matrix representation) by using different extension methods to mine frequent TDPs. Due to the complex relationships between events, temporal pattern mining is more challenging than sequential pattern mining. Strategies are used in this paper to accelerate the algorithms' search process. Experiments are conducted on both real and synthetic databases, which show good performance of the two algorithms.

A new tree-based approach to mine sequential patterns

Generic sequential pattern mining problem aims to mine the set of sequential patterns from a sequential database that satisfies a minimum support or occurrence threshold constraint. The main challenges that affect the efficiency of a solution lie in reducing the pattern search space, early detecting the infrequent patterns, representing the database in an efficient format, etc. Also, additional challenges get included when the problem environment transitions from static to incremental database leading to not to re-mine but efficiently tracking the effect of the incremental portion over the complete updated database. In this article, we introduce a new tree-based solution to the sequential pattern mining problem, including two sets of novel solutions for static and incremental sequential databases. We propose two new structures, SP-Tree and IncSP-Tree, and design two efficient algorithms, Tree-Miner and IncTree-Miner to mine the complete set of sequential patterns from static and incremental databases respectively. The proposed novel structures provide an efficient manner to store the complete sequential database maintaining “build-once-mine-many” property and giving scope to perform interactive mining. Additionally, we also design a new breath-first based support counting technique to efficiently identify the infrequent patterns at early stages and a new heuristic pruning strategy to reduce pattern search space. We also design a new pattern storage structure BPFSP-Tree to store the frequent patterns during successive iterations in incremental mining to reduce the number of database scans and to remove the infrequent patterns efficiently. A novel structure named Sequence Summarizer is also introduced to efficiently calculate and update the co-occurrence information of the items, especially in an incremental environment. Experimental results from various real-life and synthetic datasets demonstrate the efficiency of our work in comparison with the related state-of-the-art approaches.

Mining Top-k High Average-Utility Sequential Patterns for Resource Transformation

High-utility sequential pattern mining (HUSPM) helps researchers find all subsequences that have high utility in a quantitative sequential database. The HUSPM approach appears to be well suited for resource transformation in DIKWP graphs. However, all the extensions of a high-utility sequential pattern (HUSP) also have a high utility that increases with its length. Therefore, it is difficult to obtain diverse patterns of resources. The patterns that consist of many low-utility items can also be a HUSP. In practice, such a long pattern is difficult to analyze. In addition, the low-utility items do not always reflect the interestingness of association rules. High average-utility pattern mining is considered a solution to extract more significant patterns by considering the lengths of patterns. In this paper, we formulate the problem of top-k high average-utility sequential pattern mining (HAUSPM) and propose a novel algorithm for resource transformation. We adopt a projection mechanism to improve efficiency. We also adopt the sequence average-utility-raising strategy to increase thresholds. We design the prefix extension average utility and the reduced sequence average utility by incorporating the average utility into the utility upper bounds. The results of our comparative experiments demonstrate that the proposed algorithm can achieve sufficiently good performance.

Improved Peyronie's Disease Curvature Outcomes Using a Novel Collagenase Administration Protocol

To report outcomes of a novel collagenase clostridium histolyticum (CCH) injection protocol. A prospective, sequential database was maintained of all Peyronie's men undergoing CCH injections since 2015. Our protocol has evolved to include changes with injection technique, timing, aggressive modeling/traction, and wrapping. Results of the "traditional" and "novel" techniques were compared using two definitions: "most recent" assessment and final assessments among men who "completed eight (injections) or were satisfied." A total of 509 men underwent greater than or equal to 1 CCH series (traditional, n=280; novel n=229). Baseline demographic/clinicopathologic characteristics were similar between groups. Results demonstrated significantly greater curve improvements with the novel technique ("most recent" median 30° vs 20° or 46% vs 28%; "completed eight or satisfied" 34° vs 20° or 58% vs 30%). Using the "completed eight or satisfied" definition, 94% vs 66% of men achieved greater than or equal to 20% improvement (odds ratio 7.6), and 60% vs 24% achieved greater than or equal to 50% improvements (odds ratio 5.0) in the novel cohort (all P < .0001). Importantly, the International Index of Erectile Function Erectile Function Domain score was unchanged, and subjective erectile function (50% vs 5%, P < .0001) and sensation improved (17% vs 8% improved, P=.01) with the new protocol. The novel cohort also reported higher rates of surgery prevention (53% vs 18%), restored/facilitated penetration (57% vs 21%), and hematomas (56% vs 26%), necessitating changes to wrapping procedures (all P < .0001). Use of the novel CCH protocol results in significant improvements with curvature without negatively impacting erectile function or sensation. Given its specialized nature, it is not recommended for low-volume CCH injectors.

Machine Learning Based Network Traffic Predictive Analysis

Digital enterprises that use various Internet of Things implementation prototypes, such as cloud, mobile, and edge equipment, are experiencing unprecedented traffic volume and dynamicity. Data center networks (DCN) have faced various issues due to the transient and random nature of traffic created by services and apps. The primary objective of this paper is to predict the network traffic using the machine learning (ML) models before the performance of the network start degrading. Because in the last decade, ML has had a tremendous impact on handling the massive amount of data. With the increase in complexity and traffic, we tried to implement four ML models such as K – Nearest Neighbor (KNN), Random Forest (RF), Gradient Boosting (GB), and Decision Tree (Tree), with tuned sub-parameters to predict the network traffic. We create a matching ML environment based on a sequential database and provide a comparison table of mean square error (MSE), root mean square error (RMSE), mean absolute error (MSE), and coefficient of determination (R2) for each prototype. The simulation results show that the GB with different types is the best-suited model for predicting the network traffic with performance matrix parameters such as MSE 0.001 and RMSE of 0.030. Therefore, the Orange tool is used to stimulate the predictive models.

Mining Frequent Serial Positioning Episode Rules with Forward and Backward Search Technique from Event Sequences

Abstract A large event sequence can generate episode rules that are patterns which help to identify the possible dependencies existing among event types. Frequent episodes occurring in a simple sequence of events are commonly used for mining the episodes from a sequential database. Mining serial positioning episode rules (MSPER) using a fixed-gap episode occurrence suffers from unsatisfied scalability with complex sequences to test whether an episode occurs in a sequence. Large number of redundant nodes was generated in the MSPER-trie-based data structure. In this paper, forward and backward search algorithm (FBSA) is proposed here to detect minimal occurrences of frequent peak episodes. An extensive correlation of parameter settings and the generating procedure of fixed-gap episodes are carried out. To generate a fixed-gap episode and estimate the variance that decides the parameter selection in event sequences, Spearman’s correlation coefficient is used for verifying the sequence of occurrences of the episodes. MFSPER with FBSA is developed to eliminate the frequent sequence scans and redundant event sets. The MFSPER–FBSA stores the minimal occurrences of frequent peak episodes from the event sequences. The experimental evaluation on benchmark datasets shows that the proposed technique outperforms the existing methods with respect to memory, execution time, recall and precision.

Detecting and exploiting symmetries in sequential pattern mining

In this paper, we introduce a new framework for discovering and using symmetries in sequential pattern mining tasks. Symmetries are permutations between items that leave invariant the sequential database. Symmetries present several potential benefits. They can be seen as a new kind of structural patterns expressing regularities and similarities between items. As symmetries induce a partition of the sequential patterns into equivalent classes, exploiting them would allow to improve the pattern enumeration process, while reducing the size of the output. To this end, we first address the problem of symmetry discovery from database of sequences. Then, we first show how Apriori-like algorithms can be enhanced by dynamic integration of the detected symmetries. Secondly, we provide a second symmetry breaking approach allowing to eliminate symmetries in a pre-processing step by reformulating the sequential database of transactions. Our experiments clearly show that several sequential pattern mining datasets contain such symmetry-based regularities. We also experimentally demonstrate that using such symmetries would results in significant reduction of the search space on some datasets.

On-Shelf Utility Mining of Sequence Data

Utility mining has emerged as an important and interesting topic owing to its wide application and considerable popularity. However, conventional utility mining methods have a bias toward items that have longer on-shelf time as they have a greater chance to generate a high utility. To eliminate the bias, the problem of on-shelf utility mining (OSUM) is introduced. In this article, we focus on the task of OSUM of sequence data, where the sequential database is divided into several partitions according to time periods and items are associated with utilities and several on-shelf time periods. To address the problem, we propose two methods, OSUM of sequence data (OSUMS) and OSUMS + , to extract on-shelf high-utility sequential patterns. For further efficiency, we also design several strategies to reduce the search space and avoid redundant calculation with two upper bounds time prefix extension utility ( TPEU ) and time reduced sequence utility ( TRSU ). In addition, two novel data structures are developed for facilitating the calculation of upper bounds and utilities. Substantial experimental results on certain real and synthetic datasets show that the two methods outperform the state-of-the-art algorithm. In conclusion, OSUMS may consume a large amount of memory and is unsuitable for cases with limited memory, while OSUMS + has wider real-life applications owing to its high efficiency.

TKUS: Mining top-k high utility sequential patterns

High-utility sequential pattern mining (HUSPM) has recently emerged as a focus of intense research interest. The main task of HUSPM is to find all subsequences, within a quantitative sequential database, that have high utility with respect to a user-defined minimum utility threshold. However, it is difficult to specify the minimum utility threshold, especially when database features, which are invisible in most cases, are not understood. To handle this problem, top- k HUSPM was proposed. Up to now, only very preliminary work has been conducted to capture top- k HUSPs, and existing strategies require improvement in terms of running time, memory consumption, unpromising candidate filtering, and scalability. Moreover, no systematic problem statement has been defined. In this paper, we formulate the problem of top- k HUSPM and propose a novel algorithm called TKUS. To improve efficiency, TKUS adopts a projection and local search mechanism and employs several schemes, including the Sequence Utility Raising, Terminate Descendants Early, and Eliminate Unpromising Items strategies, which allow it to greatly reduce the search space. Finally, experimental results demonstrate that TKUS can achieve sufficiently good top- k HUSPM performance compared to state-of-the-art algorithm TKHUS-Span.

An efficient roadside unit deployment method for vehicular ad-hoc networks

Abstract In big cities, with heavy traffic, tracking vehicle movements undoubtedly generates big data, which can be cumbersome for real time analysis. In the other hand, the process of roadside unit (RSUs) deployment in Vehicular Ad-hoc Networks (VANETs) mainly relies on the analysis of vehicles trajectories, which is considered as big sequential data. The complexity comes from (i) the number of transactions recorded at each time and (ii) the redundancy of transactions in the database. In this respect, several research works focusing on RSUs deployment have been proposed. The thriving challenge would be to (i) reduce the deployment cost by minimizing as far as possible the number of used RSUs; and (ii) to maximize the coverage ratio. In this paper, we introduce a spatio-temporal RSU deployment method consisting of two main parts namely ”finding representative transactions from the sequential database” and ”computing coverage”. The first one identifies the representative transactions, a.k.a transactions having a high utility, from a large sequential database. The second part computes a minimal set of junctions, where RSUs have to be ideally placed. The performed experiments show that our scheme outperforms its competitors in terms of cost, time performance as well as coverage ratio.

Mining of Sequential Patterns using Directed Graphs

Sequential pattern mining is one of the important functionalities of data mining. It is used for analyzing sequential database and discovers sequential patterns. It is focused for extracting interesting subsequences from a set of sequences. Various factors such as rate of occurrence, length, and profit are used to define the interestingness of subsequence derived from the sequence database. Sequential pattern mining has abundant real-life applications since sequential data is logically programmed as sequences of cipher in many fields such as bioinformatics, e-learning, market basket analysis, texts, and webpage click-stream analysis. A large diversity of competent algorithms such as Prefixspan, GSP and Freespan have been proposed during the past few years. In this paper we propose a data model for organizing the sequential database, which consists of a directed graph DGS (cycles and several edges are allowed) and an organization of directed paths in DGS to represent a sequential data for discovering sequential pattern3 from a sequence database. Competent algorithms for constructing the digraph model (DGS) for extracting all sequential patterns and mining association rules are proposed. A number of theoretical parameters of digraph model are also introduced, which lead to more understanding of the problem.

Constraint-Based Sequential Pattern Mining with Decision Diagrams

Constraint-based sequential pattern mining aims at identifying frequent patterns on a sequential database of items while observing constraints defined over the item attributes. We introduce novel techniques for constraint-based sequential pattern mining that rely on a multi-valued decision diagram (MDD) representation of the database. Specifically, our representation can accommodate multiple item attributes and various constraint types, including a number of non-monotone constraints. To evaluate the applicability of our approach, we develop an MDD-based prefix-projection algorithm and compare its performance against a typical generate-and-check variant, as well as a state-of-the-art constraint-based sequential pattern mining algorithm. Results show that our approach is competitive with or superior to these other methods in terms of scalability and efficiency.

Mining High Utility Pattern from Sequential Database

International Journal of Computer Sciences and Engineering (A UGC Approved and indexed with DOI, ICI and Approved, DPI Digital Library) is one of the leading and growing open access, peer-reviewed, monthly, and scientific research journal for scientists, engineers, research scholars, and academicians, which gains a foothold in Asia and opens to the world, aims to publish original, theoretical and practical advances in Computer Science,Information Technology, Engineering (Software, Mechanical, Civil, Electronics & Electrical), and all interdisciplinary streams of Computing Sciences. It intends to disseminate original, scientific, theoretical or applied research in the field of Computer Sciences and allied fields. It provides a platform for publishing results and research with a strong empirical component. It aims to bridge the significant gap between research and practice by promoting the publication of original, novel, industry-relevant research.

A sequential tree approach for incremental sequential pattern mining

“Sequential pattern mining” is a prominent and significant method to explore the knowledge and innovation from the large database. Common sequential pattern mining algorithms handle static databases. Pragmatically, looking into the functional and actual execution, the database grows exponentially thereby leading to the necessity and requirement of such innovation, research, and development culminating into the designing of mining algorithm. Once the database is updated, the previous mining result will be incorrect, and we need to restart and trigger the entire mining process for the new updated sequential database. To overcome and avoid the process of rescanning of the entire database, this unique system of incremental mining of sequential pattern is available. The previous approaches, system, and techniques are a priori-based frameworks but mine patterns is an advanced and sophisticated technique giving the desired solution. We propose and incorporate an algorithm called STISPM for incremental mining of sequential patterns using the sequence tree space structure. STISPM uses the depth-first approach along with backward tracking and the dynamic lookahead pruning strategy that removes infrequent and irregular patterns. The process and approach from the root node to any leaf node depict a sequential pattern in the database. The structural characteristic of the sequence tree makes it convenient and appropriate for incremental sequential pattern mining. The sequence tree also stores all the sequential patterns with its count and statistics, so whenever the support system is withdrawn or changed, our algorithm using frequent sequence tree as the storage structure can find and detect all the sequential patterns without mining the database once again.

IJARCCE - Computer and Communication Engineering

5 Abstract: Sequential Pattern mining is the process of applying data mining techniques to large web data repositories.With the extensive use of Internet, discovery and analysis of useful information from the World Wide Web becomes a practical necessity. Data mining techniques are applied to a sequential database to discover the correlation relationships that exists among the ordered list of events. In this kind of mining, hidden data is extracted to get useful information which helps in knowing the browsing patterns of the users. Web usage mining is a data mining method that can be used in recommending the web usage patterns with the help of users' session and behaviour. The aim of discovering frequent sequential patterns in Web log data is to obtain information about the access behaviour of the users. It helps to understand the buying pattern of the existing customers. This paper focuses on the performance of the sequence tree algorithm which is better than the Generalized Sequential Pattern (GSP) algorithm. This paper emphasizes on the running time of sequence tree algorithm and its ability to discover more number of patterns than the standard GSP algorithm. With the advancement of the Information Technology, usage of World Wide Web is increasing day by day, which is becoming today's necessity. Innumerable visitors interact daily with the web throughout the world. Different kinds of data have to be organized in a way that they can be accessed by many users effectively. Web Mining is the application of data mining technologies which is being used to extract huge Web data repositories. Web mining can be broadly classified into three major parts: Web Contents Mining, Web Usage Mining and Web structure mining.

Directed Graph based Distributed Sequential Pattern Mining Using Hadoop MapReduce

Usual sequential pattern mining algorithms experiences the scalability problem when trade with very big data sets. In existing systems like PrefixSpan, UDDAG major time is needed to generate projected databases like prefix and suffix projected database from given sequential database. In DSPM (Distributed Sequential Pattern Mining) Directed Graph is introduced to generate prefix and suffix projected database which reduces the execution time for scanning large database. In UDDAG, for each unique id UDDAG is created to find next level sequential patterns. So it requires maximum storage for each UDDAG. In DSPM single directed graph is used to generate projected database and finding patterns. To improve the scanning time and scalability problem we introduce a distributed sequential pattern mining algorithm on Hadoop platform using MapReduce programming model. We use transformed database to reduce scanning time and directed graph to optimize the memory storage. Mapper is used to construct prefix and suffix projected databases for each length-1 frequent item parallel. The Reducer combines all intermediary outcomes to get final sequential patterns. Experiment results are compared against UDDAG, different values of minimum support, different massive data sets and with and without Hadoop platform which improves the scaling and speed performances. Experimental results show that DSPM using Hadoop MapReduce solves the scaling problem as well as storage problem of UDDAG. Index Terms — Distributed Environment, Directed Graph, Sequential Pattern Mining, Transformed Database. __________________________________________________*****_________________________________________________

Distributed Sequential Pattern Mining: A Survey and Future Scope

Distributed sequential pattern mining is the data mining method to discover sequential patterns from large sequential database on distributed environment. It is used in many wide applications including web mining, customer shopping record, biomedical analysis, scientific research, etc. A large research has been done on sequential pattern mining on various distributed environments like Grid, Hadoop, Cluster, Cloud, etc. Different types of sequential pattern mining can be performed are sequential patterns, maximal sequential patterns, closed sequences, constraint based and time interval based sequential patterns. This paper presents a systematic review on work done for sequential pattern mining and advanced sequential pattern mining on distributed environment. This paper finally presents future research directions related to sequential pattern mining in distributed environment. General Terms Association Rule Mining, Sequential Pattern Mining.

Techniques for Understanding User Usage Behavior on the Internet

Techniques for Understanding User Usage Behavior on the Internet

Minimizing signal detection time in postmarket sequential analysis: balancing positive predictive value and sensitivity

Outcome misclassification in retrospective epidemiologic analyses has been well-studied, but little is known about such misclassification with respect to sequential statistical analysis during surveillance of medical product-associated risks, a planned capability of the US Food and Drug Administration's Sentinel System. Using a vaccine example, we model and simulate sequential database surveillance in an observational data network using a variety of outcome detection algorithms. We consider how these algorithms, as characterized by sensitivity and positive predictive value, impact the length of surveillance and timeliness of safety signal detection. We show investigators/users of these networks how they can perform preparatory study design calculations that consider outcome misclassification in sequential database surveillance. Non-differential outcome misclassification generates longer surveillance times and less timely safety signal detection as compared with the case of no misclassification. Inclusive algorithms characterized by high sensitivity but low positive predictive value outperform more narrow algorithms when detecting rare outcomes. This decision calculus may change considerably if medical chart validation procedures were required. These findings raise important questions regarding the design of observational data networks used for pharmacovigilance. Specifically, there are tradeoffs involved when choosing to populate such networks with component databases that are large as compared with smaller integrated delivery system databases that can more easily access laboratory or clinical data and perform medical chart validation.