In unmanned aerial vehicle (UAV)-aided wireless sensor networks (UWSNs), a UAV is employed as a mobile sink to gather data from sensor nodes. Incorporating UAV helps prolong the network lifetime and avoid the energy-hole problem faced by sensor networks. In emergency applications, timely data collection from sensor nodes and transferal of the data to the base station (BS) is a prime requisite. The timely and safe path of UAV is one of the fundamental premises for effective UWSN operations. It is essential and challenging to identify a suitable path in an environment comprising various obstacles and to ensure that the path can efficiently reach the target point. This paper proposes a hybrid path planning (HPP) algorithm for efficient data collection by assuring the shortest collision-free path for UAV in emergency environments. In the proposed HPP scheme, the probabilistic roadmap (PRM) algorithm is used to design the shortest trajectory map and the optimized artificial bee colony (ABC) algorithm to improve different path constraints in a three-dimensional environment. Our simulation results show that the proposed HPP outperforms the PRM and conventional ABC schemes significantly in terms of flight time, energy consumption, convergence time, and flight path.
Unmanned aerial vehicle (UAV)-aided wireless sensor networks (UWSNs) can be effectively used for time-critical sensing applications. UAVs can be used to collect the sensed data from sensors and transfer them to a base station. The real-time transfer of data is highly desired in the time-critical applications. However, the medium access control (MAC) protocols designed for UWSNs so far are primarily focused on the efficient use of UAVs to collect data in the sensing areas. In this paper, we propose an energy-efficient and fast MAC (EF-MAC) protocol in UWSNs for time-critical sensing applications. EF-MAC adopts carrier sense multiple access (CSMA) for the registration of sensor nodes with a UAV and time division multiple access (TDMA) with variable slot time for the transmission of collected data. The UAV is equipped with two transceivers to minimize both energy consumption and delay in air-to-ground communication. The energy consumption and delay are formally analyzed and the performance of EF-MAC is evaluated via extensive simulation. The simulation results show that the proposed EF-MAC outperforms the conventional MAC protocols in terms of energy efficiency and communication delay.
Aim: Unmanned aerial vehicle (UAV)-aided wireless sensor networks (WSNs) are effectively used for surveillance, monitoring, and rescue applications in military and commercial domains. In UAV-aided WSNs (UWSNs), efficient data gathered from sensor nodes are desired to enhance network performance. However, communication between UAV and sensor nodes is challenging due to the high mobility of the UAV and a large number of sensor nodes. Clustering in UWSNs limits the number of sensor nodes communicating with the UAV, i.e., only the cluster head in a cluster can transmit the sensed data to the UAV, which reduces collision probability. Methods: In this paper, we propose a residual energy-based clustering algorithm for sensor-to-UAV communication in UWSNs. The cluster size and the number of sensor nodes in a cluster are determined on the basis of the residual energy of the sensor nodes. The performance of the proposed algorithm is evaluated by using the MATLAB simulator and then compared with that of the conventional clustering algorithm. Results: According to our extensive simulation results, the proposed clustering scheme significantly outperforms the conventional one in terms of network lifetime and data delivery ratio. Conclusion: Hence, through our studies and simulations, it can be assured that the network lifetime of UWSNs can be prolonged and the throughput of the network can also be elevated by controlling the early death of sensor nodes due to the uneven energy consumptions. We will come up with further analysis and validation of our work in the future.
Advancements in electronics and software have enabled the rapid development of unmanned aerial vehicles (UAVs) and UAV-assisted applications. Although the mobility of UAVs allows for flexible deployment of networks, it introduces challenges regarding throughput, delay, cost, and energy. Therefore, path planning is an important aspect of UAV communications. Bio-inspired algorithms rely on the inspiration and principles of the biological evolution of nature to achieve robust survival techniques. However, the issues have many nonlinear constraints, which pose a number of problems such as time restrictions and high dimensionality. Recent trends tend to employ bio-inspired optimization algorithms, which are a potential method for handling difficult optimization problems, to address the issues associated with standard optimization algorithms. Focusing on these points, we investigate various bio-inspired algorithms for UAV path planning over the past decade. To the best of our knowledge, no survey on existing bio-inspired algorithms for UAV path planning has been reported in the literature. In this study, we investigate the prevailing bio-inspired algorithms extensively from the perspective of key features, working principles, advantages, and limitations. Subsequently, path planning algorithms are compared with each other in terms of their major features, characteristics, and performance factors. Furthermore, the challenges and future research trends in UAV path planning are summarized and discussed.
Sodium nitrite was determined in 64 meat and meat products available in National Food and Feed Reference Laboratory from July 2017 to June 2018 following the AOAC (2016). None of the samples exceeded the Government of Nepal and India standard (200 ppm) and approximately five percent of the total samples had crossed the European Union standard (150ppm). Highest range (1.49-165.72 ppm) of sodium nitrite was found in chicken sausages and lowest (Not detected-55.83 ppm) in miscellaneous products (meat pickle, mo:mo, kebab, dried meat, and claws) .Chicken and buff sausages were spiked at 50, 100 and 200 ppm level and the recovery were found to be 84.32, 94.97, 89.97 and 99.84, 104.36, 105.99% respectively. Overall recovery were significantly higher (p=0.000) in buff sausage (103.40 ± 3.57%) than in chicken sausage (89.75 ± 4.79 %) at 5% level of significance. Sodium nitrite in the quality control sample was found to be 162.5±1.08 ppm which was within the range (138-226ppm) given by the supplier.
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