Hierarchical Grid Arrangements Interconnected Power System Fixed
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Computers, switches, andterminals interconnected by network links are collectively called nodes. Thepurpose of network control is to provide a connection between nodes that need tocommunicate. The arrangement of nodes and links in a network is called a topology.A variety of arrangements are possible, each with its own advantages and drawbacks.Network topology has to fit the structure of the organizational unit that will use thenetwork, and this topology should also be adapted to the unit's communication trafficpatterns and to the way the databases will be stored in order to facilitate access tothem.
A WAN has a powerful hostcomputer. The host runs a system program, called a telecommunications monitor, whichprocesses incoming messages, passing them to the appropriate application programs, andaccepts outgoing messages from the applications in order to transmit them into thenetwork.
Abstract:Renewable portfolio standards are targeting high levels of variable solar photovoltaics (PV) in electric distribution systems, which makes reliability more challenging to maintain for distribution system operators (DSOs). Distributed energy resources (DERs), including smart, connected appliances and PV inverters, represent responsive grid resources that can provide flexibility to support the DSO in actively managing their networks to facilitate reliability under extreme levels of solar PV. This flexibility can also be used to optimize system operations with respect to economic signals from wholesale energy and ancillary service markets. Here, we present a novel hierarchical scheme that actively controls behind-the-meter DERs to reliably manage each unbalanced distribution feeder and exploits the available flexibility to ensure reliable operation and economically optimizes the entire distribution network. Each layer of the scheme employs advanced optimization methods at different timescales to ensure that the system operates within both grid and device limits. The hierarchy is validated in a large-scale realistic simulation based on data from the industry. Simulation results show that coordination of flexibility improves both system reliability and economics, and enables greater penetration of solar PV. Discussion is also provided on the practical viability of the required communications and controls to implement the presented scheme within a large DSO.Keywords: distributed energy resources; smart loads; flexibility; distribution system operator; distribution network; optimal power flow; control; large scale; solar energy
It is a severe challenge to construct 3D scaffolds which hold controllable pore structure and similar morphology of the natural extracellular matrix (ECM). In this study, a compound technology is proposed by combining the 3D bioprinting and electrospinning process to fabricate 3D scaffolds, which are composed by orthogonal array gel microfibers in a grid-like arrangement and intercalated by a nonwoven structure with randomly distributed polycaprolactone (PCL) nanofibers. Human adipose-derived stem cells (hASCs) are seeded on the hierarchical scaffold and cultured 21 d for in vitro study. The results of cells culturing show that the microfibers structure with controlled pores can allow the easy entrance of cells and the efficient diffusion of nutrients, and the nanofiber webs layered in the scaffold can significantly improve initial cell attachment and proliferation. The present work demonstrates that the hierarchical PCL/gel scaffolds consisting of controllable 3D architecture with interconnected pores and biomimetic nanofiber structures resembling the ECM can be designed and fabricated by the combination of 3D bioprinting and electrospinning to improve biological performance in tissue engineering applications.
To build the hierarchical scaffolds, a novel comprehensive bioprinting system was developed by combining an electrospinning apparatus into the 3D bioprinting platform. Figure 1 shows the comprehensive bioprinting system for fabrication of hierarchical scaffolds.
In this comprehensive system, the electrospinning apparatus was composed of a syringe with metallic needle, a syringe pump and a high voltage DC power supply. The syringe pump and power supply were modulated by the same computer control system.
A hierarchical scaffold, which consisted of gel microfibers and PCL nanofibers web produced by 3D bioprinting and electrospinning respectively, was fabricated. The images of both wet and dry conditions are presented in Fig. 3a, b. As shown in Fig. 3c, the dried scaffold was characterized by a regular and interconnected pore structure which was formed by vertical aligned gel printed microfibers, whose average fiber diameter was 440 µm with a standard deviation of 41.19 µm, and the strand spacing was (527 ± 34.38) µm. Electrospun PCL nanofiber webs were regularly intercalated among every 2 layers of printed microfibers, as shown in Fig. 3d. The average diameter of nanofiber is (190 ± 15.72) nm and the mean pore size is (20 ± 8.06) µm.
Figure 4 shows the initial attachment of hASCs seeded on the hierarchical scaffold and printed scaffold after one day, respectively. Due to the smaller pore size and high surface area-to-volume ratio, electrospun nanofibers web intercalated in the 3D strands scaffold can act as the cell entrapment systems to increase cell initial attachment efficiency. As shown in Fig. 4a, the seeded hASCs were fully distributed on the nabofibers web between the microfibers layers. On the contrary, there were only a small quantity of cells spread on the printed scaffold (see Fig. 4b), and most cells went through the pores and accumulated at the bottom of the interconnected pores during the cell seeding process. The results indicate that the electrospun nanofibers webs in the hierarchical scaffold can provide a good matrix to improve the attachment efficiency of the seeded cells for tissue regeneration.
In the present research, hierarchical 3D scaffolds have been prepared via combination of 3D bioprinting and electrospinning from gel biomaterials and PCL solution for tissue engineering applications. Scaffolds characterizations and cell culture analysis are performed to explore the effects of hierarchical scaffold on the interactions between cells and scaffold. Using the compound technology, a hierarchical scaffold composed of gel microfibers forming the controlled 3D structure with interconnected macropores network and electrospun nanofibers web with micropores and high surface area can be successfully fabricated. The results of cell culture show that the hierarchical scaffold can improve initial cell attachment, cells growth and proliferation compared to the 3D bioprinting scaffold. The hierarchical PCL/gel scaffold has demonstrated the potential of combination of 3D bioprinting and electrospinning for scaffold fabrication in tissue engineering.
Examples of network topologies are found in local area networks (LAN), a common computer network installation. Any given node in the LAN has one or more physical links to other devices in the network; graphically mapping these links results in a geometric shape that can be used to describe the physical topology of the network. A wide variety of physical topologies have been used in LANs, including ring, bus, mesh and star. Conversely, mapping the data flow between the components determines the logical topology of the network. In comparison, Controller Area Networks, common in vehicles, are primarily distributed control system networks of one or more controllers interconnected with sensors and actuators over, invariably, a physical bus topology.
Network nodes are the points of connection of the transmission medium to transmitters and receivers of the electrical, optical, or radio signals carried in the medium. Nodes may be associated with a computer, but certain types may have only a microcontroller at a node or possibly no programmable device at all. In the simplest of serial arrangements, one RS-232 transmitter can be connected by a pair of wires to one receiver, forming two nodes on one link, or a Point-to-Point topology. Some protocols permit a single node to only either transmit or receive (e.g., ARINC 429). Other protocols have nodes that can both transmit and receive into a single channel (e.g., CAN can have many transceivers connected to a single bus). While the conventional system building blocks of a computer network include network interface controllers (NICs), repeaters, hubs, bridges, switches, routers, modems, gateways, and firewalls, most address network concerns beyond the physical network topology and may be represented as single nodes on a particular physical network topology.
Note that the Cross Reference feature identifies the locations of interconnected Ports and positional grid references for interconnected off sheet connectors. For both types of schematic connection objects, the existing Reports » Port Cross Reference » Add To Project command adds a cross-reference parameter based on the target sheet name and a positional grid reference.
As mentioned previously, power nets can be localized to each schematic sheet in a hierarchical design by selecting the Strict Hierarchical option for the Net Identifier Scope. This approach localizes all power nets on every sheet, so they must be manually wired together, using the same approach as signal nets. If they are not wired together, there will be a Duplicate Net Name error for each power net present on each schematic sheet. You will also need to adjust the Connection Matrix settings to allow Ports to be connected to Power Ports.
SCADA system cannot exist without a properly designed communication network system. All the SCADA system aspects rely solely on the communication network. It provides a channel for the flow of data between the supervisory control, the data acquisition units, and any controller that is connected to the system. The main function of a communication network within a SCADA system is to connect the Conversion units with the SCADA master station. The data can be transmitted through various communication platforms such as ethernet, telephone line, power line carrier communication, optical fiber line, cellular, radio, satellite, Wi-Fi, microwave, or other wireless protocol. Most facilities have specialized integrated network connectivity field buses, wired or wireless, due to security reasons. 2b1af7f3a8