Current Issue : April - June Volume : 2020 Issue Number : 2 Articles : 5 Articles
This paper presents a novel control system for chiller plants that is decentralized and\nflat-structured. Each device in chiller plant system is fitted with a smart node. It is a smart agent,\nwhich collects, handles and sends out information to its neighbours. All the smart nodes form a\nnetwork that can realize self-organization and self-recognition. Different kinds of control strategies\ncan be converted into series of decentralized computing processes carried on by the smart nodes.\nThe principle and mechanism of this decentralized, flat-structured control system for chiller plants\nare described in detail. Then a case study is presented to show how to build the decentralized,\nflat-structured control system actually. The measured data shows that the decentralized control\nmethod is energy efficiency. Moreover, it is much more flexible and scalable compared with the\ntraditional centralized control method....
In order to deliver medical products (medicines, vaccines, blood packs, etc.)\nin time for needed areas, a method of transporting goods using drones is being\nstudied. However, temperature-sensitive medical products may decay due\nto outside temperature changes. The time required to transport over the distance\nmay vary a lot as well. As a result, the likelihood of the goods deteriorating\nis very high. There is a need for a study on cargo bay to prevent this\nand to protect the medical goods. In this paper, in order to protect the\ntemperature sensitive medical goods, the inside cargo bay is equipped with\nthe cooling fan device and the electric heating elements. These elements can\nbe monitored and controlled according to the userâ??s discretion. By using the\nweb server built inside the cloud server, the temperature can be controlled in\nreal-time from anywhere without the limitation of distance. We built the\nproposed device, and installed it on the drone cargo bay. The test results show\nthat the cargo bay can be temperature-controlled, and the setting can be\nmaintained over a great distance. The user can watch the temperature variations\nduring the transport and ascertain the goodness of the medical supply\nwith the data. It is expected that such development can greatly enhance the\nutility of the drone operations, especially for the medical supply transport applications....
This paper proposes a distance-based distributionally robust energy and reserve (DBDRER)\ndispatch model via Kullbackâ??Leibler (KL) divergence, considering the volatile of renewable\nenergy generation. Firstly, a two-stage optimization model is formulated to minimize the expected\ntotal cost of energy and reserve (ER) dispatch. Then, KL divergence is adopted to establish the\nambiguity set. Distinguished from conventional robust optimization methodology, the volatile\noutput of renewable power generation is assumed to follow the unknown probability distribution\nthat is restricted in the ambiguity set. DB-DRER aims at minimizing the expected total cost in the\nworst-case probability distributions of renewables. Combining with the designed empirical\ndistribution function, the proposed DB-DRER model can be reformulated into a mixed integer\nnonlinear programming (MINLP) problem. Furthermore, using the generalized Benders\ndecomposition, a decomposition method is proposed and sample average approximation (SAA)\nmethod is applied to solve this problem. Finally, simulation result of the proposed method is\ncompared with those of stochastic optimization and conventional robust optimization methods on\nthe 6-bus system and IEEE 118-bus system, which demonstrates the effectiveness and advantages\nof the method proposed....
This article discusses edge detectors implemented in programmable logic controllers.\nThe behaviors of different vendorsâ?? solutions are presented with pros and cons. The trigger functions\ndefined in the IEC 61131-3 standard were analyzed for implementations. The main contribution\nof this paper is an idea for hardware acceleration of standard trigger functions that enables us to\nbuild single-clock-cycle edge detectors. Additionally, the structure for automatic edge detection\non every input is shown. The structure with a synthesizable Verilog HDL description is presented.\nThe comparison of the solution with vendor programmable logic controllers (PLCs) proves the\neffectiveness of the designed hardware-aided unit....
An electro-hydraulic servo position and pressure compound control method was investigated considering the working principle\nof a hydraulic stepping motor of a shield machine gripper shoe and its practical working characteristics in the supporting process.\nThe control targets were to improve the support efficiency and reduce the disturbance of gripper shoes on the surrounding rock. In\nthis method, a fuzzy switching controller was used to switch between electro-hydraulic position control and electro-hydraulic\npressure control. Numerical and prototype simulation experiments were conducted on the control method. The theoretical\nanalysis and experimental results showed that the control method could effectively convert the gripper shoes from an unsupported\nstate to a supported state in a short amount of time, as well as realize surge-free switching between position control and pressure\ncontrol. Thus, disturbance of the gripper shoes on the surrounding rock could be reduced. The results of this study provide a\ntheoretical basis for research on control strategies of hydraulic stepping propulsion of shield machines....
Loading....