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Non-intrusive appliance load monitoring (NIALM) helps identify major energy guzzlers in a building without introducing extra metering cost. It motivates users to take proper actions for energy saving and greatly facilitates demand response (DR) programs. Nevertheless, NIALM of large-scale appliances is still an open challenge. To pursue a scalable solution to energy monitoring for contemporary large-scale appliance groups, we propose a distributed metering platform and use parallel optimization for semi-intrusive appliance load monitoring (SIALM). Based on a simple power model, a sparse switching event recovering (SSER) model is established to recover appliance states from their aggregated load data. Furthermore, the sufficient conditions for unambiguous state recovery of multiple appliances are presented. By considering these conditions as well as the electrical network topology constraint, a minimum number of meters are obtained to correctly recover the energy consumption of individual appliances. We evaluate the performance of both SIALM and NIALM with real-world trace data and synthetic data. The results demonstrate that with the help of a small number of meters, the SIALM approach significantly improves the accuracy of energy disaggregation for large-scale appliances.

Attribute reduction is one of the most important topics in rough set theory. In the classical rough sets, the method for attribute reduction is mainly to keep positive region, boundary region, and negative region unchanged. However, the three regions are no longer monotonic with respect to adding or deleting an attribute in decision-theoretic rough sets. In decision-theoretic rough set model, the decision regions are determined by using the Bayesian decision procedure, and decision-making should take consideration of the cost. In this paper, two attribute reduction methods based on minimum decision cost are proposed from the algebraic view and the information theory, respectively. First, significance of joint attributes is introduced to measure the classification ability of selected attribute subset to decision-making, which overcomes the disadvantage of only considering the significance of single attribute. By using significance of joint attributes, a heuristic method based on minimum decision cost for attribute reduction is presented. Second, conditional mutual information is proposed to evaluate the significance of attribute subset for decision-making in minimum cost attribute reduction. To decrease the computational complexity of the conditional mutual information, an approximate computation method is calculated from both maximum relevance and maximum significance. To evaluate the two proposed algorithms, extensive experiments are conducted on 10 University of California at Irvine data sets. We compare our proposed algorithms with several existing cost minimization attribute reduction algorithms. Experiment results show that our proposed algorithms have a superior performance in achieving the reduct. Copyright © 2016 John Wiley & Sons, Ltd.

Energy disaggregation is to discover the energy consumption of individual appliances from their aggregated energy values. Most existing approaches rely on either appliances’ signatures or their state transition patterns, both hard to obtain in practice. In addition, load data may be corrupted due to various reasons. To overcome the problems, this paper utilizes easily accessible knowledge of appliances and the sparsity of the switching events to design a Sparse Switching Event Recovering (SSER) method. Furthermore, a robust version of this method (RSSER) is developed to tackle the problems caused by corrupted data and unknown appliances. By minimizing the total variation of the sparse event matrix and introducing a virtual appliance, RSSER can obtain accurate energy disaggregation results in the presence of outliers, without using any explicit data cleansing method. To speed up RSSER, a Parallel Local Optimization Algorithm (PLOA) is proposed to solve the problem in active epochs of appliance activities in parallel. To automatically acquire the power consumption knowledge of appliances whose information is unknown, we develop a K-median clustering based power division approach and establish an appliance power configuration platform. Using real-world trace data from our energy monitoring platform, the performance of RSSER is compared with that of the state-of-the-art solutions, including the least square estimation methods and a machine learning method using iterative Hidden Markov Model. The results show that RSSER not only has an overall better performance in both detection accuracy and overhead, but also can tolerate the interference of corrupted data and unknown appliances.

With the pervasive of the definition of the smart city, the data volume of the surveillance system, huge number of video surveillance devices is now rapidly expanding. The research to surveillance data mining and analytics has attracted increasing attention due to its applications. Cluster analysis as an important task of data mining in video surveillance has recently been highly explored. K-means algorithm is the most popular and widely-used partitional clustering algorithm in practice. However, traditional k-means algorithm suffers from sensitive initial selection of cluster centers, and it is not easy to specify the number of clusters in advance. In this paper, we propose a robust k-means algorithm that can automatically split and merge clusters which incorporates the new ideas in dealing with huge scale of video data. This novel algorithm not only addresses the sensitivity in selecting initial cluster centers, but also is resilient to the initial number of clusters. The performance is experimentally verified using synthetic and publicly available datasets. The experiments demonstrate the effectiveness and robustness of the proposed algorithm. Moreover, experiment is conducted on a real video surveillance dataset and the result shows that the novel approach can be applicated friendly in video surveillance.

This paper tackles a recent challenge in identifying culprit actors, who try to hide confidential payload with steganography, among many innocent actors in social media networks. The problem is called steganographer detection problem and is significantly different from the traditional stego detection problem that classifies an individual object as a cover or a stego. To solve the steganographer detection problem over large-scale social media networks, this paper proposes a method that uses high-order joint features and clustering ensembles. It employs 250-D features calculated from the high-order joint matrices of Discrete Cosine Transform (DCT) coefficients of JPEG images, which indicate the dependencies of image content. Furthermore, a number of hierarchical sub-clusterings trained by the features are integrated as a clustering ensemble based on the majority voting strategy, which is used to make optimal decisions on suspicious steganographers. Experimental results show that the proposed scheme is effective and efficient in identifying potential steganographers in large-scale social media networks, and has better performance when tested against the state-of-the-art steganographic methods.

Unsupervised hyperspectral band selection has been an important topic in hyperspectral imagery. This technique aims at selecting some critical and decisive spectral bands from an original image for compact representation without compromising and distorting the raw information in the relevant spectral bands. Although many efforts have been made to this topic, the structural information has not yet been well exploited during band selection, and there are still several deficiencies in search strategies, leaving room for further improvement. This paper tackles the unsupervised hyperspectral band selection problem from a global perspective and proposes a novel method claiming the following main contributions: 1) structure-aware measures for band informativeness and independence; and 2) a graph formulation of band selection allowing for an efficient integrated search by means of dominant set extraction. Experiments on three real hyperspectral images demonstrate the superiority of the proposed band selector in comparison with benchmark methods.

With the increasing sensing and communication in cyber physical social system (CPSS), the data volume is growing much rapidly in recent years. Secure deduplication has attracted considerable interests of storage provider for data management efficiency and data privacy preserving. One of the most challenging issues in secure deduplication is how to manage data and the convergent key when users frequently update it. To solve this problem, D. Koo et al . use bilinear paring as the key method. However, bilinear paring requires high computation cost for implementations. In this paper, we propose a session-key-based convergent key management scheme, named SKC, to secure the dynamic update in the data deduplication. Specifically, each data owner in SKC can verify the correctness of the session key and dynamically change it with the data update. Furthermore, to enable group combination and remove the aid of gateway (GW), a convergent key sharing scheme, named CKS, is presented. Security analysis demonstrates that both SKC and CKS can protect the confidentiality of the data and the convergent key in the case of dynamic updates. The simulation results show that our SKC and CKS can significantly reduce computation complexity and communication during the data uploading phase.

Existing stereoscopic 3D (S3D) salient object detection (SOD) networks typically employ a two-branch architecture, in which the RGB and depth channels are learned independently. Conventional methods based on conventional neural networks generally fuse the two branches by combining their deep representations at a later stage with only one path, which can be inefficient and insufficient for retaining a large amount of cross-modal data. In this study, we combine the RGB branch and depth branch to generate a third branch. The first branch is the embedded attention branch containing the attention mechanism, and we introduce the embedded attention module in this branch to give the allocation of available processing resources to the most informative components of an input signal. The second branch is the boundary refinement branch combined with the low-level information of RGB and depth images. Additionally, we propose a new module, called the detail correlation module, to ensure clear object boundaries and salient object refinement. The third branch is the global deep-view branch containing the global view module, which fuses high-level information and expands the sensor field. We also use three different loss functions to match our special SOD network. Extensive experiments demonstrate the effectiveness and robustness of the proposed architecture and show that it represents a significant improvement over other state-of-the-art SOD approaches.

Existing work on steganography mostly assumes that an image remains unchanged during transmission from the sender to the receiver. This assumption, however, may not hold in the era of the Internet due to unknown compression from the network service providers. As a result, the hidden information cannot be correctly recovered at the receiver. To address the problem, we design a new JPEG steganographic method that can resist repetitive compression during network transmission, without even knowing the compression process controlled by the network service providers. Our method uses a simulated repetitive compression network, and based on its feedback performs adaptive dither adjustment to dynamically modify the DCT coefficients disturbed by the compression process. Stego images generated with our method can be used to successfully extract the original secret messages, even after the stego images pass through multiple unknown compression processes during network transmission. Extensive experiments demonstrate that compared with existing JPEG steganographic methods, our method can effectively resist repetitive compression, while maintaining a lower bit error rate and strong anti-steganalysis capability.

This paper tackles a new challenge in high precision load forecasting of larger consumer with the background of electric power big data. The proposed short-term power load forecasting method is based on TensorFlow deep learning framwork and clustering-regression model. Proposed scheme firstly clustering the users with different electrical attributes and then obtains the “load curve of each cluster”, which is considered as the properties of a regional total load, and represents the features of various types of consumers. Furthermore, the “clustering-regression” model is used to forecast the power load of the certain region, which is implemented by TensorFlow deep learning framework. Extensive experiments show that the proposed scheme can predict reasonably the short-term power load and has excellent robustness. Comparing with the traditional model, the proposed method has a higher efficiency in dealing with large-scale data set and can be effectively applied to the power load forecasting.

This work tackles a recent challenge in digital image processing: how to identify the steganographic images from a steganographer, who is unknown among multiple innocent actors. The method does not need a large number of samples to train classification model, and thus it is significantly different from the traditional steganalysis. The proposed scheme consists of textural features and clustering ensembles. Local ternary patterns (LTP) are employed to design low-dimensional textural features which are considered to be more sensitive to steganographic changes in texture regions of image. Furthermore, we use the extracted low-dimensional textural features to train a number of hierarchical clustering results, which are integrated as an ensemble based on the majority voting strategy. Finally, the ensemble is used to make optimal decision for suspected image. Extensive experiments show that the proposed scheme is effective and efficient and outperforms the state-of-the-art steganalysis methods with an average gain from 4 % to 6 % .

Occupancy detection can greatly facilitate heating, ventilation and cooling and lightning control for building energy saving. Sensor-based occupancy detection is usually costly and may suffer from high false positive rates. As such, occupancy detection using load curve data has been proposed. Such methods, however, normally (i) rely on tedious and nontrivial model training process and (ii) do not consider the influence of corrupted data in load curve. To overcome these pitfalls, we develop a practical, robust non-intrusive occupancy detection approach that does not require model training and data cleansing. Only using load curve data and readily available appliance knowledge, the method achieves occupancy detection by three main steps: (i) the appliances’ mode states are firstly decoded via a carefully designed robust sparse switching event recovering model; (ii) the human actions are recovered with a priori knowledge of human-activated switching events; (iii) the occupancy states are then inferred based ...

The aim of clustering ensemble is to combine multiple base partitions into a robust, stable and accurate partition. One of the key problems of clustering ensemble is how to exploit the cluster structure information in each base partition. Evidence accumulation is an effective framework which can convert the base partitions into a co-association matrix. This matrix describes the frequency of a pair of points partitioned into the same cluster, but ignores some hidden information in the base partitions. In this paper, we reveal some of those information by refining the co-association matrix from data point and base cluster level. From the data point level, as pairs of points in the same base cluster may have varied similarities, their contributions to the co-association matrix can be different. From the cluster level, since the base clusters may have diversified qualities, the contribution of a base cluster as a whole can also be different from those of others. After being refined, the co-association matrix is transformed into a path-based similarity matrix so that more global information of the cluster structure is incorporated into the matrix. Finally, spectral clustering is applied to the matrix to generate the final clustering result. Experimental results on 8 synthetic and 8 real data sets demonstrate that the clustering ensemble based on the refined co-association matrix outperforms some state-of-the-art clustering ensemble schemes. HighlightsA two-level-refined co-association matrix for cluster ensemble is proposed.The refined co-association matrix is transformed by path-based measure.A theoretical background of the refinement is given.The proposed method outperforms some state-of-the-art ensemble methods.

We employ a refined and transformed co-association matrix as the input of VAT.An efficient path-based similarity algorithm is presented and its time complexity is O(N2).A simple approach to analyze D* and obtain the clustering is designed.A visual hierarchical cluster structure can be presented. A hierarchical clustering algorithm, such as Single-linkage, can depict the hierarchical relationship of clusters, but its clustering quality mainly depends on the similarity measure used. Visual assessment of cluster tendency (VAT) reorders a similarity matrix to reveal the cluster structure of a data set, and a VAT-based clustering discovers clusters by image segmentation techniques. Although VAT can visually present the cluster structure, its performance also relies on the similarity matrix employed. In this paper, we take a refined co-association matrix, which is originally used in ensemble clustering, as an initial similarity matrix and transform it by path-based measure, and then apply it to VAT. The final clustering is achieved by directly analyzing the transformed and reordered similarity matrix. The proposed method can deal with data sets with some complex cluster structures and reveal the relationship of clusters hierarchically. The experimental results on synthetic and real data sets demonstrate the above mentioned properties.

Current complex engineering software systems are often composed of many components and can be built based on a multiagent approach, resulting in what are called complex multiagent software systems. In a complex multiagent software system, various software agents may cite the operation results of others, and the citation relationships among agents form a citation network; therefore, the importance of a software agent in a system can be described by the citations from other software agents. Moreover, the software agents in a system are often divided into various groups, and each group contains the agents undergoing similar tasks or having related functions; thus, it is necessary to find the influential agent group (not only the influential individual agent) that can influence the system outcome utilities more than the others. To solve such a problem, this paper presents a new model for finding influential agent groups based on group centrality analyses in citation networks. In the presented model, a concept of extended group centrality is presented to evaluate the impact of an agent group, which is collectively determined by both direct and indirect citations from other agents outside the group. Moreover, the presented model addresses two typical types of agent groups: one is the adjacent group where agents of a group are adjacent in the citation network, and the other is the scattering group where agents of a group are distributed separately in the citation network. Finally, we present case studies and simulation experiments to prove the effectiveness of the presented model.

Time synchronization is one of the most fundamental services for wireless sensor networks. Prior studies have investigated the clock stability due to environmental dynamics. In this paper, we demonstrate by experiment that in spite of the surrounding environment, time synchronization is unavoidably impacted by in-network energy heterogeneity, which may incur up to 30-40 ppm clock uncertainty. We mathematically analyze the root cause of such clock uncertainty and propose a protocol called EATS. Sensor nodes with EATS can intelligently select the best synchronization parents that minimize the negative impact of the energy heterogeneity. The selection is robust to multiple impacting factors in the network and provides fine-grained synchronization accuracy. In addition, nodes can make use of local energy information and further calibrate the clocks. In light of this, the logic time maintained among different nodes is more consistent and the synchronization can be performed with a longer re-synchronization interval and less energy consumption. We implement EATS with TelosB motes and evaluate the effectiveness and efficiency of our design through extensive experiments and simulations.

For many vehicular safety applications, it is critical to timely and reliably deliver multimedia data from a traveling vehicle to a roadside access point (AP) in an error-prone vehicular ad hoc network (VANET), which is a typical uplink scenario for drive-thru Internet. To achieve this goal, we propose a cooperative retransmission scheme that exploits a common phenomenon in reality, in which consecutive vehicles can naturally form a platoon to reduce energy consumption. We develop a 4-D Markov chain to model the proposed scheme and analyze the uplink throughput of drive-thru Internet, which also reveals some fundamental relationships among traffic flow, platoon parameters, and system throughput. We conduct extensive simulation in OMNeT++ to validate our scheme and the analytical model. Numerical results show that the proposed platoon-based cooperative retransmission scheme significantly improves the uplink throughput of drive-thru Internet, considerably decreases the total transmission times for a given quantity of upload data, and, hence, achieves a greener mobile multimedia communication.

Social emotion detection of online users has become an important task for mining public opinions. Social emotion detection aims at predicting the readers’ emotions evoked by news articles, tweets, etc. In this article, we focus on building a social emotion detection system for online news. The system is built based on the modules of document selection, Part-of-speech (POS) tagging, and social emotion lexicon generation. Empirical studies are extensively conducted on a large scale real-world collection of news articles. Experiments show that the document selection algorithm has a positive effect on the social emotion detection. The system performs better with the words and POS combination compared to a feature set consisting only of words. POS is also useful to detect emotion ambiguity of words and the context dependence of their sentiment orientations. Furthermore, the proposed method of generating the lexicon outperforms the baselines in terms of social emotion prediction.

The development of smart grid depends on increased deployment of two-way communication to improve its efficiency and reliability of power delivery. However, this additional dependency also expands the risk from pollution attacks, which consist of injecting malicious packets in the network. The pollution attacks are amplified by the network coding process, resulting in a greater damage to the state estimation and decision making. In this paper, we address this issue by designing an efficient authentication protocol, named EAPA, for the smart grid communication. The proposed scheme allows not only recipient nodes, but also intermediate nodes, to verify the integrity and origin of the packets received without having to decode, and thus detect and discard the malicious packets in transit that fail the verification. By this means, the pollution is canceled out before reaching the destinations. Security analysis demonstrates that the EAPA can be resilient to data/tag pollution attacks and replay attacks. Performance evaluation results show that our EAPA can reduce much more communication overhead than Wu’s scheme.

The growing peak-hour power demand has invoked an urgency to increase the peak-hour supply. Although smart grid has been envisioned as the next generation power system due to its two-way communication of information and power, the peak-hour power shortage problem still exists. In this paper, we propose a credit-based incentive tariff CIT scheme with fraud-traceability for smart grid. Specifically, the CIT encourages retail customers to sell the power generated by their renewable resources back to the grid during peak hours via giving additional incentive rate to them based on their credits. If a fraud is detected during the power transaction, the malicious customer's identity can be traced out and his or her credit can be correspondingly reduced. The security analysis shows that the CIT resists various security threats and makes the incentive tariff fair and more secure. The performance evaluation demonstrates that the CIT can dramatically increase the peak-hour supply and reduce the peak-to-average power demand ratio by up to 7%. Copyright © 2013 John Wiley & Sons, Ltd.

Sentiment analysis of online documents such as news articles, blogs and microblogs has received increasing attention in recent years. In this article, we propose an efficient algorithm and three pruning strategies to automatically build a word-level emotional dictionary for social emotion detection. In the dictionary, each word is associated with the distribution on a series of human emotions. In addition, a method based on topic modeling is proposed to construct a topic-level dictionary, where each topic is correlated with social emotions. Experiment on the real-world data sets has validated the effectiveness and reliability of the methods. Compared with other lexicons, the dictionary generated using our approach is language-independent, fine-grained, and volume-unlimited. The generated dictionary has a wide range of applications, including predicting the emotional distribution of news articles, identifying social emotions on certain entities and news events.

Smart grid, envisioned as an indispensable power infrastructure, is featured by real-time and two-way communications. How to securely retrieve and audit the communicated metering data for validation testing is, however, still challenging for smart grid. In this paper, we propose a novel privacy-preserving range query (PaRQ) scheme over encrypted metering data to address the privacy issues in financial auditing for smart grid. Our PaRQ allows a residential user to store metering data on a cloud server in an encrypted form. When financial auditing is needed, an authorized requester can send its range query tokens to the cloud server to retrieve the metering data. Specifically, the PaRQ constructs a hidden vector encryption based range query predicate to encrypt the searchable attributes and session keys of the encrypted data. Meanwhile, the requester's range query can be transferred into two query tokens, which are used to find the matched query results. Security analysis demonstrates that in the PaRQ, only the authorized requesters can obtain the query results, while the data confidentiality and query privacy are also preserved. The simulation results show that our PaRQ can significantly reduce communication and computation costs.

Distributed energy resources DERs, which are characterized by small-scale power generation technologies to provide an enhancement of the traditional power system, have been strongly encouraged to be integrated into the smart grid, and numerous trading strategies have recently been proposed to support the energy auction in the emerging smart grid marketing. However, few of them consider the security aspects of energy trading, such as privacy preservation, bid integrity, and pre-filtering ability. In this paper, we propose an efficient searchable encryption scheme for auction SESA in emerging smart grid marketing. Specifically, SESA uses a public key encryption with keyword search technique to enable the energy sellers e.g., DERs to inquire suitable bids while preserving the privacy of the energy buyers. Additionally, to facilitate the seller to search for detailed information of the bids, we also propose an extension of SESA to support conjunctive keywords search. Security analysis demonstrates that the proposed SESA and its extension can achieve data and keyword privacy, bid integrity and trapdoor unforgeability. Simulation results also show that both SESA and its extension have less computation and communication overhead than the existing searchable encryption approaches. Copyright © 2013 John Wiley & Sons, Ltd.

Multiple sensing agent system is generally used to represent practical distributed multiple sensor systems at an abstract level without worrying about the particulars of sensors, where agents represent the autonomous sensors. There are many multiagent coordination models which require relatively high memory and computation capacities of agents; thus those models are impractical for multiple sensing agent systems where agents have very limited memories and capacities. To fully relax agents from observing and memorizing other agents' actions, this paper proposes the concept of tag vector in multiagent coordination and proposes a novel tag-based solution for data sensing conflicts in multiple sensing agent systems; in the presented tag-based solution, agents can coordinate their sensed data according to their tags. The theoretical proofs and case study prove that the proposed tag-based solution can effectively solve the data sensing conflicts by making the sensed data more consistent and reducing the coordination expense.

A strategy of automatic answer retrieval for repeated or similar questions in user-interactive systems by employing semantic question patterns is proposed in this paper. The used semantic question pattern is a generalized representation of a group of questions with both similar structure and relevant semantics. Specifically, it consists of semantic annotations (or constraints) for the variable components in the pattern and hence enhances the semantic representation and greatly reduces the ambiguity of a question instance when asked by a user using such pattern. The proposed method consists of four major steps: structure processing, similar pattern matching and filtering, automatic pattern generation, question similarity evaluation and answer retrieval. Preliminary experiments in a real question answering system show a precision of more than 90% of the method.

Arrays are one of the most fundamental and widely applied data structures, which are useful for modeling both logical designs and physical implementations of multi-dimensional data objects sharing the same type of homogeneous elements. However, there is a lack of a formal model of the universal array based on it any array instance can be derived. This paper studies the fundamental properties of Universal Array (UA) and presents a comprehensive design pattern. A denotational mathematics, Real-Time Process Algebra (RTPA), allows both architectural and behavioral models of UA to be rigorously designed and refined in a top-down approach. The conceptual model of UA is rigorously described by tuple- and matrix-based mathematical models. The architectural models of UA are created using RTPA architectural modeling methodologies known as the Unified Data Models (UDMs). The physical model of UA is implemented using linear list that is indexed by an offset pointer of elements. The behavioral models of UA are specified and refined by a set of Unified Process Models (UPMs). As a case study, the formal UA models are implemented in Java. This work has been applied in a number of real-time and nonreal-time systems such as compilers, a file management system, the real-time operating system (RTOS+), and the ADT library for an RTPA-based automatic code generation tool.

Focused crawling is increasingly seen as a solution to address the scalability limitations of existing general-purpose search engines, by traversing the Web to only gather pages that are relevant to a specific topic. How to predict the relevance of the unvisited pages pointed to by candidate URLs in the crawling frontier to a given topic is a key issue in the design of focused crawlers. In this paper, we propose a novel approach based on multiple relevance prediction strategies to address this problem. For cross-language crawling, we first introduce a hierarchical taxonomy to describe topics in both English and Chinese. We then present a formal description of the relevance predicting process and discuss four strategies that make use of page contents, anchor texts, URL addresses and link types of Web pages, respectively, to evaluate the relevance more accurately, in which we propose a particular strategy using Chinese URL addresses to estimate the relevance of cross-language Web pages. Finally, we get a new focused crawling algorithm (FCMRPS, Focused Crawling based on Multiple Relevance Prediction Strategies) based on the combination of these strategies and Shark-Search, which is a classic focused crawling algorithm. Experiments show that the FCMRPS is more effective than the traditional algorithms, namely Breadth-First, Best-First and Shark-Search, in terms of precision and sum of information.

Occupancy detection can greatly facilitate HVAC and lightning control for building energy saving. Sensor based occupancy detection is usually costly and may suffer from high false positive rates. As such, occupancy detection using load curve data has been proposed. Such type of methods, however, normally relies on tedious and nontrivial model training process. To overcome this pitfall, we develop a simple, non-intrusive occupancy detection approach that does not require any model training and only uses load curve data and readily-available appliance knowledge. The method consists of three main steps: i) the appliances' mode states are firstly decoded via a carefully designed total variation minimization problem; ii) the human actions are recovered with a-priori knowledge of human-activated switching events; iii) the occupancy states are then inferred based on the recovered human actions along with empirical association rules. We evaluate our approach and compare with existing methods with real-world data. The results show that our approach can achieve similar performance to those using supervised machine learning.

In the big data era, duplicated copies of data may be generated by various smart devices. Although convergent encryption has been extensively adopted for secure deduplication, it is still very challenging to efficiently and reliably manage the convergent keys and support keyword search over encrypted data. This paper addresses this problem by presenting an efficient scheme for big data outsourcing with secure deduplication, named BDO-SD. Specifically, with the convergent encryption technique, data owners can outsource their data to the cloud server with data deduplication; with the idea of public key encryption and keywords search, a data user can query encrypted data while preserving its privacy. Security analysis demonstrates that our proposed BDO-SD scheme can achieve the data confidentiality, query privacy and key security. Simulation results show that compared with other schemes, our scheme can achieve better efficiency than the existing data deduplication schemes.

Load curve data in power systems refers to users' electrical energy consumption data periodically collected with meters. It has become one of the most important assets for modern power systems. Many operational decisions are made based on the information discovered in the data. Load curve data, however, usually suffers from corruptions caused by various factors, such as data transmission errors or malfunctioning meters. To solve the problem, tremendous research efforts have been made on load curve data cleansing. Most existing approaches apply outlier detection methods from the supply side (i.e., electricity service providers), which may only have aggregated load data. In this paper, we propose to seek aid from the demand side (i.e., electricity service users). With the help of readily available knowledge on consumers' appliances, we present an appliance-driven approach to load curve data cleansing. This approach utilizes data generation rules and a Sequential Local Optimization Algorithm (SLOA) to solve the Corrupted Data Identification Problem (CDIP). We evaluate the performance of SLOA with real-world trace data and synthetic data. The results indicate that, comparing to existing load data cleansing methods, such as B-spline smoothing, our approach has an overall better performance and can effectively identify consecutive corrupted data. Experimental results also show that our method is robust in various tests.

In this brief, we have investigated querying techniques in the smart grid. We conclude the brief with the following remarks.

Distributed energy resources (DERs), which are characterized by small scale power generation technologies to provide an enhancement of the traditional power system, have been strongly encouraged to be integrated into the smart grid, and numerous trading strategies have recently been proposed to support the energy auction in the emerging smart grid marketing. However, few of them consider the security aspects of energy trading, such as privacy-preservation, bid integrity and pre-filtering ability. In this chapter, we introduce an efficient Searchable Encryption Scheme for Auction (SESA) in emerging smart grid marketing. Specifically, SESA uses a public key encryption with keyword search technique to enable the energy sellers, e.g. DERs, to inquire suitable bids while preserving the privacy of the energy buyers (EBs). Additionally, to facilitate the seller to search for detailed information of the bids, we also propose an extension of SESA to support conjunctive keywords search.

Smart grid, envisioned as an indispensable power infrastructure, is featured by real-time and two-way communications. However, how to securely retrieve and audit the communicated metering data for validation testing is still challenging for smart grid. In this chapter, we introduce a novel privacy-preserving range query scheme over encrypted metering data, named PaRQ, to address the privacy issues in financial auditing for smart grid. The PaRQ allows a residential user to store metering data on a cloud server in an encrypted form. When financial auditing is needed, an authorized requester can send its range query tokens to the cloud server to retrieve the metering data. Specifically, the PaRQ constructs a hidden vector encryption (HVE) based range query predicate to encrypt the searchable attributes and session keys of the encrypted data. Meanwhile, the requester’s rang query can be transferred into two query tokens, which are used to find the matched query results.

With the development of the Internet, user-generated data has been growing tremendously in Web 2.0 era. Facing such a big volume of resources in folksonomy, people need a method of fast exploration and indexing to find their demanded data. To achieve this goal, contextual information is indispensable and valuable to understand user preference and purpose. In sociolinguistics, context can be mainly categorized as verbal context and social context. Comparing with verbal context, social context not only requires domain knowledge to pre-define contextual attributes but also acquires additional data from users. However, there is no research of addressing irrelevant contextual factors for verbal context model so far. The dominating set from verbal context proposed in this paper is to fill this blank. We present the verbal context in folksonomy to capture the user intention, and propose a dominating set discovering method for this verbal context model to prune the irrelevant contextual factors and keep the major characteristics at the same time. Furthermore, the experiments, which are conducted on a public data set, show that the proposed method gives convincing results.

In power systems, load curve data is one of the most important datasets that are collected and retained by utilities. The quality of load curve data, however, is hard to guarantee since the data is subject to communication losses, meter malfunctions, and many other impacts. In this paper, a new approach to analyzing load curve data is presented. The method adopts a new view, termed \textit{portrait}, on the load curve data by analyzing the periodic patterns in the data and re-organizing the data for ease of analysis. Furthermore, we introduce algorithms to build the virtual portrait load curve data, and demonstrate its application on load curve data cleansing. Compared to existing regression-based methods, our method is much faster and more accurate for both small-scale and large-scale real-world datasets., Comment: 10 pages, 9 figures

A strategy of automatic answer retrieval for repeated or similar questions in user-interactive systems by employing semantic question patterns is proposed in this paper. The used semantic question pattern is a generalized representation of a group of questions with both similar structure and relevant semantics. Specifically, it consists of semantic annotations (or constraints) for the variable components in the pattern and hence enhances the semantic representation and greatly reduces the ambiguity of a question instance when asked by a user using such pattern. The proposed method consists of four major steps: structure processing, similar pattern matching and filtering, automatic pattern generation, question similarity evaluation and answer retrieval. Preliminary experiments in a real question answering system show a precision of more than 90% of the method.

Arrays are one of the most fundamental and widely applied data structures, which are useful for modeling both logical designs and physical implementations of multi-dimensional data objects sharing the same type of homogeneous elements. However, there is a lack of a formal model of the universal array based on it any array instance can be derived. This paper studies the fundamental properties of Universal Array (UA) and presents a comprehensive design pattern. A denotational mathematics, Real-Time Process Algebra (RTPA), allows both architectural and behavioral models of UA to be rigorously designed and refined in a top-down approach. The conceptual model of UA is rigorously described by tuple- and matrix-based mathematical models. The architectural models of UA are created using RTPA architectural modeling methodologies known as the Unified Data Models (UDMs). The physical model of UA is implemented using linear list that is indexed by an offset pointer of elements. The behavioral models of UA are specified and refined by a set of Unified Process Models (UPMs). As a case study, the formal UA models are implemented in Java. This work has been applied in a number of real-time and nonreal-time systems such as compilers, a file management system, the real-time operating system (RTOS+), and the ADT library for an RTPA-based automatic code generation tool.