Sensors are used to monitor and control the physical environment. In mobile sensor networks, nodes can self-propel via springs, wheels, or they can be attached to transporters, such as vehicles. ...Sensors have limited energy supply and the sensor network is expected to be functional for a long time, so optimizing the energy consumption to prolong the network lifetime becomes an important issue. In static sensor networks, if sensors are uniformly deployed, sensors near the sinks die first. This is because besides sending their own sensed data, they also participate in forwarding data on behalf of other sensors located farther away from the sink. This uneven energy consumption results in network partitioning and limitation of the network lifetime. In this paper, we survey mechanisms that utilize nodes’ mobility to extend the network lifetime.
We divide these mechanisms into three groups: mechanisms using mobile sinks, mechanisms using mobile sensors redeployment, and mechanisms using mobile relays. Using mobile sinks, energy is saved by using shorter multi-hop data delivery paths and the set of sensors located near a sink changes over time, thus the energy consumption is balanced in the whole network. Using mobile sensors, the initial deployment can be improved through sensor relocation such that to balance energy consumption and to extend network lifetime. Mobile nodes can also be used as relays, which can inherit the responsibilities of the co-locating static sensors or they can carry data to the sink to reduce the cost of long distance communication. We provide overviews and comparisons among different mechanisms.
Pesticide exposure, heavy metal pollution, and biological stressors drive a worldwide, ongoing, and rapid population decline of the crucial pollinator honeybee. Drastic colony loss of honeybees may ...well precipitate a food security crisis. Here a systematic review was conducted, examining reports on a global scale to propose a bench line for common pesticides and potentially toxic element (PTE) residue levels in plant rewards and honeybees and to assess the health risk of chemical residues via oral exposure to honeybees. Relevant articles were retrieved from Scopus, PubMed, ISI Web of Science, and Embase. Recent findings on how chemical and biological stressors cripple honeybee health, and conservation techniques were also summarized. We identified a number of chemical residues at lethal or sublethal risk to honeybees based on their average concentrations, as well as primary evidence pertaining to the bio-accumulative propensity of certain substances. Moreover, combinations of pesticide stressors (“pesticide cocktails”), which are frequently encountered in agricultural landscapes, often interact synergistically with honeybee health via detoxification suppression. Finally, we discuss and describe the relevance of novel, biotechnology-based, approaches to counteract agrochemical and PTE poisoning.
Smartphones are envisioned to provide promising applications and services. At the same time, smartphones are also increasingly becoming the target of malware. Many emerging malware can utilize the ...proximity of devices to propagate in a distributed manner, thus remaining unobserved and making detections substantially more challenging. Different from existing malware coping schemes, which are either totally centralized or purely distributed, we propose a Community-based Proximity Malware Coping scheme, CPMC. CPMC utilizes the social community structure, which reflects a stable and controllable granularity of security, in smartphone-based mobile networks. The CPMC scheme integrates short-term coping components, which deal with individual malware, and long-term evaluation components, which offer vulnerability evaluation towards individual nodes. A closeness-oriented delegation forwarding scheme combined with a community level quarantine method is proposed as the short-term coping components. These components contain a proximity malware by quickly propagating the signature of a detected malware into all communities while avoiding unnecessary redundancy. The long-term components offer vulnerability evaluation towards neighbors, based on the observed infection history, to help users make comprehensive communication decisions. Extensive real- and synthetic-trace driven simulation results are presented to to evaluate the effectiveness of CPMC.
In this paper, we consider an adaptive energy efficient sensor scheduling mechanism. We consider a wireless sensor network where the sink sends queries form time to time, and sensors are equipped ...with one or more sensing components. Our goal is to design an adaptive sensor scheduling mechanism to choose sets of active sensors to work alternatively such that different types of queries are served, the global connectivity requirements can be met, and network lifetime is maximized. A connected dominating set (CDS) based localized mechanism is proposed. Initially, a basic backbone is constructed, then when a query is issued, new sensors are activated locally such that to meet the requirements of the query and global connectivity. When a query expires, some sensors return to sleep and the CDS is restored. Our simulation results show that the solution is effective and it improved network lifetime.
In mobile ad hoc networks, nodes have the inherent ability to move. Aside from conducting attacks to maximize their utility and cooperating with regular nodes to deceive them, malicious nodes get ...better payoffs with the ability to move. In this paper, we propose a game theoretic framework to analyze the strategy profiles for regular and malicious nodes. We model the situation as a dynamic Bayesian signaling game and analyze and present the underlining connection between nodes' best combination of actions and the cost and gain of the individual strategy. Regular nodes consistently update their beliefs based on the opponents' behavior, while malicious nodes evaluate their risk of being caught to decide when to flee. Some possible countermeasures for regular nodes that can impact malicious nodes' decisions are presented as well. An extensive analysis and simulation study shows that the proposed equilibrium strategy profile outperforms other pure or mixed strategies and proves the importance of restricting malicious nodes' advantages brought by the flee option.
Good sensor deployment is vital for wireless sensor networks (WSNs). To improve the initial deployment and to prolong network lifetime, one approach is to relocate sensors in different densities ...which vary with the distance to the sink. Since sensors located closer to the sink are involved in more data forwarding, sensors in this region should have a higher density. In this paper, we address the problem of movement-assisted sensor positioning (MSP) to increase network lifetime with the objective to achieve the theoretical sensor densities while minimizing sensor movement. We propose three solutions: an integer-programming formulation, a localized matching method, and a distributed corona-radius scanning algorithm. Simulation results are presented to evaluate the proposed solutions.
The thesis based on a car engine plant, analyzing the promotion for the introduction of JIT quality control system. Compare the Simultaneous engineering method with traditional JIT quality control ...method in terms of quality control. Analysis shows that the accumulate material waste ratio during the production process has decreased significantly by using the Simultaneous engineering method.Keywords-component; formatting; style; styling; insert (key words)
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