Smart meters are considered as foundational part of the smart metering infrastructure (SMI) in smart energy networks. Smart meter is a digital device that makes use of twoway communication between consumer and utility to exchange, manage and control energy consumptions within a home. However, despite all the features, a smart meter raises several securityrelated concerns. For instance, how to exchange data between the legal entities (e.g., smart meter and utility server) while maintaining privacy of the consumer. To address these concerns, authentication and key agreement in SMI can provide important security properties that not only to maintain a trust between the legitimate entities but also to satisfy other security services. This work presents a lightweight authentication and key agreement (LAKA) that enables trust, anonymity, integrity and adequate security in the domain of smart energy network. The proposed scheme employs hybrid cryptography to facilitate mutual trust (authentication), dynamic session key, integrity, and anonymity. We justify the feasibility of the proposed scheme with a testbed using 802.15.4 based device (i.e., smart meter). Moreover, through the security and performance analysis, we show that the proposed scheme is more effective and energy efficient compared to the previous schemes.
The smart home is an environment, where heterogeneous electronic devices and appliances are networked together to provide smart services in a ubiquitous manner to the individuals. As the homes become smarter, more complex, and technology dependent, the need for an adequate security mechanism with minimum individual's intervention is growing. The recent serious security attacks have shown how the Internetenabled smart homes can be turned into very dangerous spots for various ill intentions, and thus lead the privacy concerns for the individuals. For instance, an eavesdropper is able to derive the identity of a particular device/appliance via public channels that can be used to infer in the life pattern of an individual within the home area network. This paper proposes an anonymous secure framework (ASF) in connected smart home environments, using solely lightweight operations. The proposed framework in this paper provides efficient authentication and key agreement, and enables devices (identity and data) anonymity and unlinkability. One-time session key progression regularly renews the session key for the smart devices and dilutes the risk of using a compromised session key in the ASF. It is demonstrated that computation complexity of the proposed framework is low as compared with the existing schemes, while security has been significantly improved.
Background and Purpose: Rate of force development (RFD) is influential, and possibly more influential than other muscular performance parameters, for mobility in older adults. However, only a few studies have investigated this matter, and this has not been examined for the plantar flexors (PFs). The purpose of this study was to examine the contribution of PF RFD and other common tests of muscular performance to Up-and-Go (UG) performance and walking speed (WS) in older adults. Methods: Twenty-six (19 females) healthy, community-dwelling older adults (73.7 ± 4.9 years) were recruited from a senior citizen center for this observational study. Handgrip strength, UG performance, as well as preferred and maximal WS were obtained. Time taken to complete 5-chair rises and the number of chair rises completed in 30 seconds were recorded. Rate of force development of the PFs was obtained during a rapid, bilateral calf raise performed on a force plate. Hierarchical multiple linear regression was used to identify significant predictors, after adjusting for physical activity level and body mass index, of mobility (ie, UG, preferred and maximal WS). Results and Discussion: No muscular performance variables correlated with preferred WS. Rate of force development (adjusted R 2 = 0.356; P = .008) and handgrip strength (adjusted R 2 = 0.293; P = .026) were the only predictors of maximal WS and accounted for a 21.7% and 16.1% change in R 2, respectively, after accounting for physical activity level and body mass index. Rate of force development was the only predictor of UG performance (adjusted R 2 = 0.212; P = .006) and accounted for a 29.2% change in R 2 after adjustment variables were applied. Conclusions: Compared to common assessments of muscular performance, such as handgrip strength and chair rise performance, PF RFD was a greater predictor of mobility in older adults. These findings, in conjunction with recent reports, indicate that the assessment of RFD likely complements strength testing, thereby enabling a more robust assessment of functional decline in older adults.
Modern multiprocessor systems offer advanced synchronization primitives, built in hardware, to support the development of efficient parallel algorithms. In this article, we develop a simple and efficient algorithm, the READERSFIELD algorithm, for atomic registers (variables) of arbitrary length. The simplicity and better complexity of the algorithm is achieved via the utilization of two such common synchronization primitives. In this article, we also experimentally evaluate the performance of our algorithm, together with lock-based approaches and a practical, previously known algorithm that is based only on read and write primitives. The experimental evaluation is performed on three well-known parallel architectures. This evaluation clearly shows that both algorithms are practical and that as the size of the register increases the READERSFIELD algorithm performs better, following its analytical evaluation.
Online search is a basic online problem. The fact that its optimal deterministic/randomized solutions are given by simple formulas (however with difficult analysis) makes the problem attractive as a target to which other practical online problems can be transformed to find optimal solutions. However, since the upper/lower bounds of prices in available models are constant, natural online problems in which these bounds vary with time do not fit in the available models.We present two new models where the bounds of prices are not constant but vary with time in certain ways. The first model, where the upper and lower bounds of (logarithmic) prices have decay speed, arises from a problem in concurrent data structures, namely to maximize the (appropriately defined) freshness of data in concurrent objects. For this model we present an optimal deterministic algorithm with competitive ratio √ D, where D is the known duration of the game, and a nearly-optimal randomized algorithm with competitive ratio. We also prove that the lower bound of competitive ratios of randomized algorithms is asymptotically ln D .The second model is inspired by the fact that some applications do not utilize the decay speed of the lower bound of prices in the first model. In the second model, only the upper bound decreases arbitrarily with time and the lower bound is constant. Clearly, the lower bound of competitive ratios proved for the first model holds also against the stronger adversary in the second model. For the second model, we present an optimal randomized algorithm. Our numerical experiments on the freshness problem show that this new algorithm achieves much better/smaller competitive ratios than previous algorithms do, for instance 2.25 versus 3.77 for D = 128.
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