The Social Internet of Things (S-IoT) paradigm is focused on topic of the Internet of Things (IoT), which accelerates the object issues by working with the concept of social networks. Searching and finding a new object in the community are considered to manage the number of friends and complex relationships between them and affect the ability to navigate at the cloud-edge layer, and resources, such as battery lifetime of S-IoT devices and energy resources, are important challenges in this field. In the processing of social messages of remote devices, increasing the battery life of devices that require such requirements plays the most important role. In this research, a collaboration scenario is presented to consider object attributes, friend’s functions and intelligent friend selection among objects for group messaging. First, a general reference model is designed and presented to select a friend to access group message remote processing services and minimize cloud-edge resources. The simulation results show that, for the correct communication of friends at the edge of the network and in each service discovery, according to the length of the path in the network, it is possible to establish stable communication and make better service with the least possible. The results show that if we want to develop a method for friendship between objects in communication in cloud computing, the proposed method can greatly improve the effectiveness of providing reliable message processing types.

Prechamber jet ignition is a promising technology that enables stable ignition and fast combustion by combining thermal effects, chemical kinetics, and turbulent disturbance. The development and application of the prechamber ignition require a comprehensive and in-depth understanding of the operating characteristics of the prechamber ignition in the real engine working cycle. Therefore, numerical simulations are conducted to explore the operating performance of the prechamber ignition applied to a large-bore natural gas engine in this study. The differences between the passive prechamber (PPRE) and active prechamber (APRE) near the lean burn limit are compared. The results show that the jet ignition performance of the PPRE is hampered by the high residual gas coefficient and lean mixture in the prechamber under lean burn conditions. The ignition mode of the PPRE is similar to torch ignition, and the combustion process in the main chamber is mainly turbulent flame propagation. The ignition mechanism of the APRE is flame jet ignition. The main chamber combustion process presents a two-stage heat release characteristic, which can be subdivided into three phases: the initial flame development phase, the rapid combustion phase, and the late combustion phase. The heat release rate during the initial flame development phase depends on the physical and chemical properties of the prechamber jet and the mixture conditions in the main chamber. During the rapid combustion phase, the flame propagation along the radial direction of the jet largely depends on the time scale of the chemical reaction. The heat release rate depends on the coverage area of the jet, the jet residual momentum, and the turbulent flame speed. During the late combustion phase, the flame propagation is mainly affected by the turbulent flame speed. These results provide theoretical guidance for the subsequent application of prechamber ignition systems in various powertrains.

In this paper, On the basis of analyzing the model of three-phase PWM rectifier for wind power grid-connected inverter, the mathematical model of the vector decoupling controlled PWM rectifier at three-phase synchronous rotating coordinate system is deduced. This paper proposes a novel vector decoupling control strategy, which consists of two control loop, i.e. outer voltage loop and inner current loop. It can realize decoupling control of active current and reactive current, thus the active power and reactive power can be regulated independently. PI regulators are used in voltage and current loop to achieve no static error control. Experimental results prove that the proposed rectifier has the satisfactory control performance, and it can achieve approximate unity power factor correction. The experiments also show that the efficiency of proposed rectifier is high, the reliability is well and its application is wide.

Prechamber jet ignition, as an efficient ignition technology, can enhance ignition stability and enable rapid combustion. The mixture formation and flow dynamics inside the prechamber are very important for the jet ignition process and engine performance. Active prechamber is an effective method to achieve turbulent jet ignition, but at present there is currently limited understanding of the impact of auxiliary fuel injection (AFI) in an active prechamber. In this study, it is suggested to use auxiliary hydrogen injection to improve the mixture in the prechamber, thereby improving the ignition performance of the prechamber jet. The influences of AFI on the combustion process and engine performance are studied by numerical simulation. Under different AFI strategies, the in-cylinder flow, ignition, and combustion processes are simulated. The effect of different AFI schemes on prechamber combustion, jet characteristics, combustion process in the main chamber, active radicals, and engine performance are compared. The results show that operating the natural gas engine under lean burn conditions increases the indicated thermal efficiency and lowers NO _x emissions. The introduction of an auxiliary hydrogen injection shortens the time interval between the spark ignition timing and the injection timing of the hot jet, thereby advancing the ignition timing for lean combustion in the main chamber. As the amount of hydrogen injected rises, the injection velocity and temperature of the prechamber jet increase, so the jet ignition performance is strengthened. Moreover, the auxiliary hydrogen that flows into the main chamber increases the chemical activity of the lean mixture present there. The combination of the prechamber jet ignition with auxiliary hydrogen injection significantly improves the ignition performance and accelerates the lean burn rate in the main chamber, showing the potential to expand the lean burn limit of natural gas engines.