Search

Recently radio frequency identification (RFID) is promoting the rapid development of Internet of Things and has been widely applied in numerous industrial applications such as inventory management, object tracking and smart logistics, etc. Tags in some RFID applications can be classified into multiple categories according to the types of objects they are attached to. One of the important functionalities for the multi-category RFID systems is the missing tag cardinality estimation of each category. This paper focuses on solving the missing tag iceberg query problem for multi-category RFID systems, i.e., to determine a set of categories, whose missing tags are more than a threshold, with a required reliability. We firstly propose two basic missing tag i ceberg query schemes called MAC-SZE and MAC-HZE, which adopt the singleton-zero estimator and homogeneous-zero estimator, respectively. To further improve the query efficiency, we then propose two segmented enhanced schemes called MAC-SSZE and MAC-SHZE, which eliminate the unnecessary slots in each frame. We conduct theoretical analysis to guarantee the required reliability is satisfied. The simulations are finally conducted and the results illustrate that the proposed missing tag iceberg query schemes greatly outperform other existing one. [ABSTRACT FROM AUTHOR]

Finding the minimum connected dominating set (MCDS) is a key problem in wireless sensor networks, which is crucial for efficient routing and broadcasting. However, the MCDS problem is NP-hard. In this paper, a new approximation algorithm with approximation ratio H(Δ)+3 in time O(n2) is proposed to approach the MCDS problem. The key idea is to divide the sensors in CDS into core sensors and supporting sensors. The core sensors dominate the supporting sensors in CDS, while the supporting sensors dominate other sensors that are not in CDS. To minimize the number of both the cores and the supporters, a three-phased algorithm is proposed. (1) Finding the base-core sensors by constructing independent set (denoted as S1), in which the sensors who have the largest |N2(v)||N(v)| (number of two-hop neighbors over the number of one-hop neighbors) will be selected greedily into S1; (2) Connecting all base-core sensors in S1 to form a connected subgraph, the sensors in the subgraph are called cores; (3) Adding the one-hop neighbors of the core sensors to the supporter set S2. This guarantees a small number of sensors can be added into CDS, which is a novel scheme for MCDS construction. Extensive simulation results are shown to validate the performance of our algorithm. [ABSTRACT FROM AUTHOR]

An introduction is presented in which the editor discusses various articles within the issue on topics including privacy in Internet of Things (IoT), network communication, and intelligent software in healthcare, sports, and financial big data analysis.

Certificate validation in public key infrastructure (PKI) is a vital phase of establishing secure connections on any network. There has been a great deal of speculation on how to efficiently validate digital certificates in PKI on which the security of network communications rests. Developing such a system is challenging because digital certificates need to be quickly and securely validated for a large number of clients in a short period of time at a low cost. On the other hand, our analysis on the TLS handshakes of the Alexa Top 1 Million domains dataset indicates that the current popular certificate validation systems cannot deliver certificate validation information to the clients in a timely fashion and suffer from high overhead at the client side, making them susceptible to a number of attacks. Motivated by these observations, we present SecureGuard, a certificate validation system that can effectively handle certificate validation during TLS handshakes. Our system utilizes Internet service providers (ISPs) as the primary entity for certificate validation exploiting the fact that any Internet access request must pass through the ISP proxy-cache servers. We provide an extensive evaluation on SecureGuard and illustrate its efficiency. Moreover, we introduce a quantitative analysis method that can investigate the costs incurred by our system and other certificate validation approaches under the same evaluation scenarios. Our implementation results demonstrate that SecureGuard is able to validate the digital certificates within a short period of time, in a secure manner, with less network overhead. [ABSTRACT FROM AUTHOR]

In many radio-frequency identification (RFID) applications, one of the essential systematic functionalities is to quickly detect missing-tag event in case of misplacement or other incorrect operations. In this paper, we focus on probabilistically detecting the missing tags for the anonymous multicategory RFID systems without revealing the tag privacy. The main objective is to minimize the detection time while satisfying the required detection reliability of each category. First, we propose to use a multihash technique to sequentially detect the missing tags category-by-category, called segmented sequential detection approach, in which the frame segmentation is adopted to reduce the detection time. Then, we propose an enhanced segmented sequential detection approach to further improve the detection efficiency by deactivating the identified existing tags. We conduct extensive simulations to illustrate the effectiveness of our proposed two missing tag detection approaches. [ABSTRACT FROM AUTHOR]

The advertised quality of an Internet of things service is not always trustable due to the exaggerated quality propagation and dynamic network environment. Therefore, it is more trustable to evaluate the Internet of things service quality based on the historical execution records of service. However, an Internet of things service often has multiple historical records whose invocation time and location are different, which makes it necessary to weigh each historical record of an identical Internet of things service. Besides, for different candidate Internet of things services, their invocation frequencies are often varied, which may also affect the final service selection decision of target user. In view of the above two challenges, a novel service selection approach “Time–Location–Frequency”–aware Service Selection Approach is put forward in this article. In Time–Location–Frequency–aware Service Selection Approach, we first weigh each historical record of an Internet of things service, based on its service invocation time and location; afterward, we weigh each candidate Internet of things service based on its invocation frequency; finally, with the derived two kinds of weights, we evaluate each candidate Internet of things service and return the quality-optimal one to the target user. At last, through a set of experiments deployed on a real service quality data set WS-DREAM, we validate the feasibility of our proposal. [ABSTRACT FROM AUTHOR]

Let $$G=(V,E)$$ be a graph and $$\phi :V\cup E\rightarrow \{1,2,\ldots ,k\}$$ be a total coloring of G. Let C( v) denote the set of the color of vertex v and the colors of the edges incident with v. Let f( v) denote the sum of the color of vertex v and the colors of the edges incident with v. The total coloring $$\phi $$ is called neighbor set distinguishing or adjacent vertex distinguishing if $$C(u)\ne C(v)$$ for each edge $$uv\in E(G)$$ . We say that $$\phi $$ is neighbor sum distinguishing if $$f(u)\ne f(v)$$ for each edge $$uv\in E(G)$$ . In both problems the challenging conjectures presume that such colorings exist for any graph G if $$k\ge \varDelta (G)+3$$ . In this paper, by using the famous Combinatorial Nullstellensatz, we prove that in both problems $$k\ge \varDelta (G)+2\mathrm{col}(G)-2$$ is sufficient, moreover we prove that if G is not a forest and $$\varDelta \ge 4$$ , then $$k\ge \varDelta (G)+2\mathrm{col}(G)-3$$ is sufficient, where $$\mathrm{col}(G)$$ is the coloring number of G. In fact we prove these results in their list versions, which improve the previous results. As a consequence, we obtain an upper bound of the form $$\varDelta (G)+C$$ for some families of graphs, e.g. $$\varDelta +9$$ for planar graphs. In particular, we therefore obtain that when $$\varDelta \ge 4$$ two conjectures we mentioned above hold for 2-degenerate graphs (with coloring number at most 3) in their list versions. [ABSTRACT FROM AUTHOR]

Lane-level navigation has received a lot of attention in recent years. It has played a great role in assisting route planning, as well as navigating automated vehicles. Aside from sticking to the planned route, abnormal traffic situations which result in blocking lanes could impact lane switching decisions. Unfortunately, there is currently no navigation system that can sense and track a vehicle's lane position and to advise the driver of lane switching decisions. Google Maps stores a priori the number of lanes and their directions at each highway exit and provides this information to drivers when navigating. However, even with this information, some drivers may not be able to make an informed decision regarding when and where to make a correct lane switch. This motivated us to develop a mechanism for the detection and tracking of real-time lane changes. In this paper, we propose a GPS-aiding system that can sense and track a vehicle's lane position. The system leverages smart phones’ computing capability, rear cameras, and inertial motion sensors. With little extra computational overhead, the system applies computer vision techniques to achieve lane-level positioning. We also design a machine learning-based algorithm to detect and track lane switching. We conduct a series of experiments, analyze our system in real-world environments, and achieve very promising results. We believe our system can be a great asset to current smart phone navigation systems. [ABSTRACT FROM AUTHOR]

Balancing the security and efficiency of the internet of things (IoT) is difficult due to its numerous heterogeneous devices, different trust levels of stakeholders, and asymmetric resource distribution among layers. Identity-based broadcast encryption (IBBE) is a promising technique to ensure data confidentiality, simplify the certification management issue, and achieve one-to-many data sharing while reducing overheads simultaneously. However, broadcast encryption (BE) schemes without source authentication are not applicable in the real world as they cannot prevent invalid messages from malicious users. Meanwhile, the computation cost of IBBE is heavy and not suitable for constrained devices. This paper proposes a lightweight ID-based broadcast signcryption scheme (LIBBSC), which takes advantage of fog nodes to temporarily store ciphertext and to partially designcrypt for end users. A fog node transforms the ciphertext based on the specific user's public identity key and then sends the outdesigncrypted ciphertext to the end-user (this step transforms the broadcast to the one-to-one communication). Finally, only the designated end-user with the associated secret key can rapidly designcrypt with minimal computational cost. Our scheme is selective-ID secure against chosen-ciphertext attacks in the random oracle model. And the implementation and evaluation of the proposed scheme show that it is efficient and suitable for IoT devices. [ABSTRACT FROM AUTHOR]

Recent research has demonstrated that characteristic gene selection based on gene expression data remains faced with considerable challenges. This is primarily because gene expression data are typically high dimensional, negative, non-sparse and noisy. However, existing methods for data analysis are able to cope with only some of these challenges. In this paper, we address all of these challenges with a unified method: nonnegative matrix factorization via the L2,1-norm (NMF-L2,1). While L2,1-norm minimization is applied to both the error function and the regularization term, our method is robust to outliers and noise in the data and generates sparse results. The application of our method to plant and tumor gene expression data demonstrates that NMF-L2,1 can extract more characteristic genes than other existing state-of-the-art methods. [ABSTRACT FROM AUTHOR]

Due to the imbalanced energy consumption among nodes in wireless sensor networks, some nodes die prematurely, which decreases the network lifetime. To solve this problem, existing clustering protocols usually construct unequal clusters by exploiting uneven competition radius. Taking their imperfection on designing the uneven competition radius and intercluster communication into consideration, this paper proposes an improved distributed unequal clustering protocol (IDUC) for wireless sensor networks, where nodes are energy heterogeneous and scattered unevenly. The cores of IDUC are the formation of unequal cluster topology and the construction of intercluster communication routing tree. Compared with previous protocols, IDUC is suitable for various network scenarios, and it can balance the energy consumption more efficiently and extend the lifetime of networks significantly. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the bilateral symmetry of the global corneal topography in normal corneas with a wide range of curvature, astigmatism and thickness values Design: Cross-Sectional Study Methods: Topography images were recorded for the anterior and posterior surfaces of 342 participants using a Pentacam. Elevation data were fitted to a general quadratic model that considered both translational and rotational displacements. Comparisons between fellow corneas of estimates of corneal shape parameters (elevation, radius in two main directions, Rx and Ry, and corresponding shape factors, Qx and Qy) and corneal position parameters (translational displacements: x0, y0 and z0, and rotational displacements: α, β and γ) were statistically analyzed. Results: The general quadratic model provided average RMS of fit errors with the topography data of 1.7±0.6 µm and 5.7±1.3 µm in anterior and posterior corneal surfaces. The comparisons showed highly significant bilateral correlations with the differences between fellow corneas in Rx, Ry, Qx and Qy of anterior and posterior surfaces remaining insignificantly different from zero. Bilateral differences in elevation measurements at randomly-selected points in both corneal central and peripheral areas indicated strong mirror symmetry between fellow corneas. The mean geometric center (x0, y0, z0) of both right and left corneas was located on the temporal side and inferior-temporal side of the apex in anterior and posterior topography map, respectively. Rotational displacement angle α along X axis had similar distributions in bilateral corneas, while rotation angle β along Y axis showed both eyes tilting towards the nasal side. Further, rotation angle γ along Z axis, which is related to corneal astigmatism, showed clear mirror symmetry. Conclusions: Analysis of corneal topography demonstrated strong and statistically-significant mirror symmetry between bilateral corneas. This characteristic could help in detection of pathological abnormalities, disease diagnosis, measurement validation and surgery planning. [ABSTRACT FROM AUTHOR]