Biodegradation of Dimethyl Phthalate by Freshwater Unicellular Cyanobacteria

The biodegradation characteristics of dimethyl phthalate (DMP) by three freshwater unicellular organisms were investigated in this study. The findings revealed that all the organisms were capable of metabolizing DMP; among them, Cyanothece sp. PCC7822 achieved the highest degradation efficiency. Lower concentration of DMP supported the growth of the Cyanobacteria; however, with the increase of DMP concentration growth of Cyanobacteria was inhibited remarkably. Phthalic acid (PA) was detected to be an intermediate degradation product of DMP and accumulated in the culture solution. The optimal initial pH value for the degradation was detected to be 9.0, which mitigated the decrease of pH resulting from the production of PA. The optimum temperature for DMP degradation of the three species of organisms is 30 ∘ C. After 72 hours' incubation, no more than 11.8% of the residual of DMP aggregated in Cyanobacteria cells while majority of DMP remained in the medium. Moreover, esterase was induced by DMP and the activity kept increasing during the degradation process. This suggested that esterase could assist in the degradation of DMP

Cellular network based multistatic integrated sensing and communication systems

A novel multistatic integrated sensing and communication (ISAC) system based on cellular network is proposed. It can make use of widespread base stations (BSs) to perform cooperative sensing in wide area. This system is important since the deployment of sensing function can be achieved upon the mobile communication network at low complexity and cost without modifying the architecture of BSs for full duplexing. In this work, the topology of sensing cell is first provided, which can be duplicated to seamlessly cover the cellular network. Each sensing cell consists of a single central BS transmitting signals and multiple neighboring BSs receiving reflected signals from sensing objects. Then an estimating approach is described for obtaining position and velocity of sensing objects that locate in the sensing cell. Joint data processing with an efficient optimization method is also provided. In addition, key issues in the cellular network based multistatic ISAC system are analyzed. Simulation results show that the multistatic ISAC system can reduce interference power by over 10 dBm and significantly improve position and velocity estimation accuracy of objects when compared with the monostatic ISAC system, demonstrating the effectiveness and promise of implementing the proposed system in the mobile network

Research on Wireless Sensor Actuator Distribution Algorithm Meeting Maximum Request Expectation

In wireless sensor actuator networks, actuator nodes are very important to network coverage for wireless sensor. So according to the characteristics that wireless communication is easy to be affected by the environment, in this wireless sensor actuator network the actuator nodes are abstracted to be service providers and the sensor nodes are abstracted to be service consumers. Furthermore, the messages transferred from actuator nodes to sensor nodes are abstracted to be service requests and the coverage of sensor nodes by actuator nodes is service providing. Moreover, the service faulty ratio of actuator nodes is defined in this paper. Based on that, an actuator node coverage algorithm that satisfies the maximum request expectation is put forwarded. Its goal is to solve the mathematical expectation of maximizing the number of service requests with fixed number of sensor nodes and actuator nodes. So the optimal position of actuator nodes could be identified. The theoretic proof and simulation result show that this algorithm is more efficient compared with similar algorithm

Q-Learning-Based High Credibility and Stability Routing Algorithm for Internet of Medical Things

With the outbreak of COVID-19, people’s demand for using the Internet of Medical Things (IoMT) for physical health monitoring has increased dramatically. The considerable amount of data requires stable, reliable, and real-time transmission, which has become an urgent problem to be solved. This paper constructs a health monitoring-enabled IoMT network which is composed of several users carrying wearable devices and a coordinator. One of the important problems for the proposed network is the unstable and inefficient transmission of data packets caused by node congestion and link breakage in the routing process. Based on these, we propose a Q-learning-based dynamic routing selection (QDRS) algorithm. First, a mathematical model of path optimization and a solution named Global Routing selection with high Credibility and Stability (GRCS) is proposed to select the optimal path globally. However, during the data transmission through the optimal path, the node and link status may change, causing packet loss or retransmission. This is a problem not considered by standard routing algorithms. Therefore, this paper proposes a local link dynamic adjustment scheme based on GRCS, using the Q-learning algorithm to select the optimal next-hop node for each intermediate forwarding node. If the selected node is not the same as the original path, the chosen node replaces the downstream node in the original path and so corrects the optimal path in time. This paper considers the congestion state, remaining energy, and mobility of the node when selecting the path and considers the network state changes during packet transmission, which is the most significant innovation of this paper. The simulation results show that compared with other similar algorithms, the proposed algorithm can significantly improve the packet forwarding rate without seriously affecting the network energy consumption and delay

Energy Consumption Balanced Topology Variable Routing Algorithm for WWSN in Disaster Rescue Scenarios

In recent years, the Wearable Wireless Sensor Network (WWSN) has become one of the most popular networks used in disaster and emergency scenarios. We propose a routing algorithm named Energy Consumption Balanced Topology Variable (ECB-TV) on the body of users in WWSN. In the ECB-TV algorithm, network topology can be variable according to the change of network state. A multi-hop topology is used in normal situation and the network will switch to single-hop topology at once when an abnormal event happens. We also design a novel multi-hop routing algorithm for multi-hop topology where we select the node with the highest energy balance factor as next hop node. Energy balance factor is innovatively designed by simultaneously taking into account both energy consumption of transmitting and receiving nodes, which can balance the energy consumption of sensor nodes well. The simulation results show that the proposed ECB-TV algorithm has better performance in terms of lifetime in normal situations and delay in abnormal situations

A Multicast-Traffic-Oriented Energy-Saving Algorithm with a Hybrid Sleep Mode for EPONs

High energy consumption in Ethernet Passive Optical Networks (EPONs) has caused intense research on energy-saving methods in recent years. The most common method for EPON energy saving is to cause optical network units (ONUs) to sleep which are idle or low loaded. With the popularity of multimedia applications, the ONUs carry not only unicast traffic but also more and more multicast traffic. However, existing studies mainly focus on ONUs that support only unicast traffic. The many differences between multicast traffic and unicast traffic make it necessary to design novel energy-saving methods. This paper proposes a multicast-traffic-oriented energy-saving algorithm for EPONs, called the energy-saving algorithm for multicast traffic (ESMT). To save as much energy as possible, the proposed algorithm uses a hybrid sleep mode (composed of a deep sleep state and an independent sleep mode) in which not only can ONU enter a deep sleep state, but also the ONU transmitter and receiver can sleep independently. Simulation results show that the proposed algorithm, which is oriented to multicast traffic in EPONs, is more energy efficient than other algorithms

Biodegradation of Dimethyl Phthalate by Freshwater Unicellular Cyanobacteria

The biodegradation characteristics of dimethyl phthalate (DMP) by three freshwater unicellular organisms were investigated in this study. The findings revealed that all the organisms were capable of metabolizing DMP; among them, Cyanothece sp. PCC7822 achieved the highest degradation efficiency. Lower concentration of DMP supported the growth of the Cyanobacteria; however, with the increase of DMP concentration growth of Cyanobacteria was inhibited remarkably. Phthalic acid (PA) was detected to be an intermediate degradation product of DMP and accumulated in the culture solution. The optimal initial pH value for the degradation was detected to be 9.0, which mitigated the decrease of pH resulting from the production of PA. The optimum temperature for DMP degradation of the three species of organisms is 30°C. After 72 hours’ incubation, no more than 11.8% of the residual of DMP aggregated in Cyanobacteria cells while majority of DMP remained in the medium. Moreover, esterase was induced by DMP and the activity kept increasing during the degradation process. This suggested that esterase could assist in the degradation of DMP

Effect of Sizing Agent on the Mechanical, Thermal, and Electrical Performance of Basalt Fiber/Epoxy Composites

Basalt fiber and its resin composites have gradually supplanted traditional steel and glass fiber composites due to their superior strength, heat resistance, and corrosion resistance. However, basalt fiber still has significant flaws that restrict the functionality and use of its composites, such as less active functional groups and poor resin adherence. This study examines the effects of sizing agent on the characteristics of basalt fiber/epoxy resin composites. Epoxy resin emulsion and acrylate emulsion are employed as the primary auxiliary film-forming agents in this study. Polyurethane emulsion with various content levels is also used. The findings indicate that a 1% wt. of polyurethane emulsion concentration produces the greatest results, increasing the composite’s flexural strength, flexural modulus, tensile strength, and interlaminar shear strength by 122%, 34.0%, 102%, and 10.2%, respectively. At the same time, the storage modulus and Tg of the material will decrease. In addition, the breakdown strength can be raised by 112%, and insulation parameters such as leakage current and dielectric loss factor can be decreased by 26.4% and 15.6%, respectively. The effect of sizing agent B is the best

A Study on the Influence of End-Sheath Aging and Moisture Absorption on Abnormal Heating of Composite Insulators

Abnormal heating of composite insulators of high-voltage transmission lines concentrate at its end, especially in a high-humidity environment. In order to study the influence of end-sheath aging and moisture absorption on abnormal heating of composite insulators, in this paper, we first discuss the appearance test, temperature rise test, and dielectric characteristic test conducted on 110 kV decommissioned composite insulators. Test results indicated the temperature rise in composite insulators increased with ambient humidity, but temperature rise was not severely affected by surface contamination of its shed and sheath; in dry environments, the dielectric constant and dielectric loss factor of high-voltage end sheaths are higher than of those of medium- and low-voltage end sheaths, and the loss effect becomes more severe after moisture absorption in a high-humidity environment. After the tests, the authors established a COMSOL simulation model of composite insulators, to analyze changes in the electric field and thermal field of the end sheath of composite insulators due to the coupling of electric and thermal fields. It was concluded that the dielectric constant of a high-voltage end sheath of the composite insulator increased after moisture absorption, distorting the partial electric field on the surface; meanwhile, the dielectric loss factor increased significantly after water molecules intruded into the aging layer of the sheath as polar molecules. Therefore, the dielectric loss (leakage conductance loss and lossy polarization loss) caused by aging and moisture absorption of the sheath surface under partially high field strength in the high-humidity environment was the leading cause of abnormal heating at the high-voltage end of composite insulators. The conclusion of this paper serves as an important reference for revealing the causes of abnormal heating of composite insulators in high-humidity environments and the influence mechanism of external factors on abnormal heating