scholarly journals High-performance power grids for nanometer technologies

2004 ◽  
Author(s):  
S.S. Sapatnekar
Keyword(s):  
High Performance ◽  
Power Grids

scholarly journals Cerium Oxide–Polysulfone Composite Separator for an Advanced Alkaline Electrolyzer

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2821
Author(s):  
Jung Won Lee ◽  
ChangSoo Lee ◽  
Jae Hun Lee ◽  
Sang-Kyung Kim ◽  
Hyun-Seok Cho ◽  
...  
Keyword(s):  
High Performance ◽  
Renewable Energy Sources ◽  
Average Pore Size ◽  
Hydrogen Permeability ◽  
Power Grids ◽  
Stable Operation ◽  
Average Pore ◽  
Ohmic Resistance ◽  
Composite Separator ◽  
High Flexibility

The intermittent and volatile nature of renewable energy sources threatens the stable operation of power grids, necessitating dynamically operated energy storage. Power-to-gas technology is a promising method for managing electricity variations on a large gigawatt (GW) scale. The electrolyzer is a key component that can convert excess electricity into hydrogen with high flexibility. Recently, organic/inorganic composite separators have been widely used as diaphragm membranes; however, they are prone to increase ohmic resistance and gas crossover, which inhibit electrolyzer efficiency. Here, we show that the ceria nanoparticle and polysulfone composite separator exhibits a low area resistance of 0.16 Ω cm2 and a hydrogen permeability of 1.2 × 10–12 mol cm–1 s–1 bar–1 in 30 wt% potassium hydroxide (KOH) electrolyte, which outperformed the commercial separator, the Zirfon PERL separator. The cell using a 100 nm ceria nanoparticle/polysulfone separator and advanced catalysts has a remarkable capability of 1.84 V at 800 mA cm−2 at 30 wt% and 80 °C. The decrease in the average pore size of 77 nm and high wettability (contact angle 75°) contributed to the reduced ohmic resistance and low gas crossover. These results demonstrate that the use of ceria nanoparticle-based separators can achieve high performance compared to commercial zirconia-based separators.

scholarly journals The Effective Healing Strategy against Localized Attacks on Interdependent Spatially Embedded Networks

Complexity ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Kai Gong ◽  
Jia-Jian Wu ◽  
Ying Liu ◽  
Qing Li ◽  
Run-Ran Liu ◽  
...  
Keyword(s):  
Communication Networks ◽  
High Performance ◽  
Large Scale ◽  
Power Grids ◽  
Moderate Degree ◽  
Embedded Networks ◽  
Low Degree ◽  
High Degree ◽  
Functional Components ◽  
Failed Node

Many real-world infrastructure networks, such as power grids and communication networks, always depend on each other by their functional components that share geographic proximity. A lot of works were devoted to revealing the vulnerability of interdependent spatially embedded networks (ISENs) when facing node failures and showed that the ISENs are susceptible to geographically localized attacks caused by natural disasters or terrorist attacks. How to take emergency methods to prevent large scale of cascading failures on interdependent infrastructures is a longstanding problem. Here, we propose an effective strategy for the healing of local structures using the connection profile of a failed node, called the healing strategy by prioritizing minimum degrees (HPMD), in which a new link between two active low-degree neighbors of a failed node is established during the cascading process. Afterwards, comparisons are made between HPMD and three healing strategies based on three metrics: random choice, degree centrality, and local centrality, respectively. Simulations are performed on the ISENs composed of two diluted square lattices with the same size under localized attacks. Results show that HPMD can significantly improve the robustness of the system by enhancing the connectivity of low-degree nodes, which prevent the diffusion of failures from low-degree nodes to moderate-degree nodes. In particular, HPMD can outperform other three strategies in the size of the giant component of networks, critical attack radius, and the number of iterative cascade steps for a given quota of newly added links, which means HPMD is more effective, more timely, and less costly. The high performance of HPMD indicates low-degree nodes should be placed on the top priority for effective healing to resist the cascading of failures in the ISENs, which is totally different from the traditional methods that usually take high-degree nodes as critical nodes in a single network. Furthermore, HPMD considers the distance between a pair of nodes to control the variation in the network structures, which is more applicable to spatial networks than previous methods.

scholarly journals An Automatic Design Framework for Real-Time Power System Simulators Supporting Smart Grid Applications

Electronics ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 299 ◽  
Author(s):  
Eleftherios Mylonas ◽  
Nikolaos Tzanis ◽  
Michael Birbas ◽  
Alexios Birbas
Keyword(s):  
Smart Grid ◽  
Power System ◽  
Real Time ◽  
High Speed ◽  
High Performance ◽  
Power Grids ◽  
Low Latency ◽  
Successful Implementation ◽  
Automatic Design ◽  
Design Framework

Smart grid technology is the next step to the evolution of classical power grids, providing robustness, reliability, and security throughout the network, enabling real-time management and control. To achieve these goals, distributed computing (microgrid concept) and intelligent control algorithms, tailored to the nature and needs of the network under study, are necessary. To deal with the vast diversity of power grids, being able to capture the dynamics of any given network, and create tools for network analysis, apparatus testing, and power grid management, an automatic design framework for real-time power system simulators is needed. In this article, a prototype of this approach is presented, employing Field Programmable Gate Array (FPGA) platforms due to their reconfigurability that enables low-power, low-latency, and high-performance designs, as a first attempt towards an open source platform, compatible with the majority of hardware design suites. It comprises two major parts: (i) a user-oriented section, built in Matlab/Simulink; and (ii) a hardware-oriented section, written in Matlab and Very High Speed Integrated Circuit (VHSIC)-Hardware Description Language (VHDL) code. To verify its functionality, two test power networks were given in a schematic format, analyzed through Matlab code and turned into dedicated hardware simulators with the aid of the VHDL template. Then, simulation results from Simulink and the prototype were compared for error estimation. The results show the prototype’s successful implementation with minimal resources utilization, high performance and low latency in the order of nanoseconds in Xilinx 6- and 7-series FPGAs, therefore proving its modularity and efficient use in many different scenarios, meeting low-latency/real-time requirements while enabling further smart grid research.

scholarly journals Power Density Maximization in Medium Frequency Transformers by Using Their Maximum Flux Density for DC–DC Converters

Electronics ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 470
Author(s):  
Dante Ruiz-Robles ◽  
Edgar L. Moreno-Goytia ◽  
Vicente Venegas-Rebollar ◽  
Nadia M. Salgado-Herrera
Keyword(s):  
Flux Density ◽  
Power Density ◽  
High Performance ◽  
High Efficiency ◽  
Electrical Power ◽  
Power Grids ◽  
Medium Frequency ◽  
Maximum Flux ◽  
Conventional Procedure ◽  
Core Losses

The medium frequency transformer (MTF) is a key component of various new DC–DC converters that are designed for applications in modern electrical power grids at medium and high voltage. To attain the high performance that are necessary for targeting these applications, MFTs should have high power density and high efficiency as characteristics. For this endeavor, newly designed MFT procedures, which also take advantages of new core materials, are under investigation. Differently to other design proposals, most of which use conventional transformer design procedures based on equating core losses to copper conduction losses, in this paper, an MTF with a nanocrystalline (VITROPERM 500F) core is designed with a new procedure that is oriented in aiming the maximum flux density (Bmax). The characteristics of the MFTs that are obtained by using this procedure are compared with those of the MFTFs that are designed with a conventional procedure. The results show that by using the proposed technique, we get a 25% reduction in the winding size, a higher power density, and a lower MTF building cost while maintaining a high efficiency (>98%). The design methodology is developed through a rigorous mathematical analysis that is verified with computer simulations in Matlab-Simulink and validated with experimental results from two MTF laboratory prototypes designed at a flux density of 0.9 T (75% Bmax) and 1.2 T (Bmax).

A High Performance Energy Analyzer for Use in Electron Scanning Microscopy

1969 ◽  
Vol 27 ◽  
pp. 14-15
Author(s):  
A. V. Crewe ◽  
M. Isaacson ◽  
D. Johnson
Keyword(s):  
High Performance ◽  
Vertical Plane ◽  
Median Plane ◽  
Electron Gun ◽  
Uniform Field ◽  
Loss Mechanism ◽  
Electron Scanning Microscopy ◽  
Sector Type ◽  
Double Focusing ◽  
Electron Energy Loss

A double focusing magnetic spectrometer has been constructed for use with a field emission electron gun scanning microscope in order to study the electron energy loss mechanism in thin specimens. It is of the uniform field sector type with curved pole pieces. The shape of the pole pieces is determined by requiring that all particles be focused to a point at the image slit (point 1). The resultant shape gives perfect focusing in the median plane (Fig. 1) and first order focusing in the vertical plane (Fig. 2).

Vacuum System to Minimize the Specimen Contamination of High-Performance EM

1977 ◽  
Vol 35 ◽  
pp. 68-69
Author(s):  
N. Yoshimura ◽  
K. Shirota ◽  
T. Etoh
Keyword(s):  
Electron Microscope ◽  
High Speed ◽  
High Performance ◽  
High Vacuum ◽  
Vacuum System ◽  
Pump System ◽  
Pumping System ◽  
Diffusion Pump ◽  
Almost All ◽  
Cascade Type

One of the most important requirements for a high-performance EM, especially an analytical EM using a fine beam probe, is to prevent specimen contamination by providing a clean high vacuum in the vicinity of the specimen. However, in almost all commercial EMs, the pressure in the vicinity of the specimen under observation is usually more than ten times higher than the pressure measured at the punping line. The EM column inevitably requires the use of greased Viton O-rings for fine movement, and specimens and films need to be exchanged frequently and several attachments may also be exchanged. For these reasons, a high speed pumping system, as well as a clean vacuum system, is now required. A newly developed electron microscope, the JEM-100CX features clean high vacuum in the vicinity of the specimen, realized by the use of a CASCADE type diffusion pump system which has been essentially improved over its predeces- sorD employed on the JEM-100C.

Use of the Magnetostatic Analogue In Electromagnetic Lens Engineering

1970 ◽  
Vol 28 ◽  
pp. 360-361
Author(s):  
John W. Coleman
Keyword(s):  
Boundary Conditions ◽  
High Performance ◽  
Force Fields ◽  
Optical Design ◽  
Direct Conversion ◽  
Design Engineering ◽  
Design Data ◽  
Scalar Potentials ◽  
Geometric Elements ◽  
At Will

In the design engineering of high performance electromagnetic lenses, the direct conversion of electron optical design data into drawings for reliable hardware is oftentimes difficult, especially in terms of how to mount parts to each other, how to tolerance dimensions, and how to specify finishes. An answer to this is in the use of magnetostatic analytics, corresponding to boundary conditions for the optical design. With such models, the magnetostatic force on a test pole along the axis may be examined, and in this way one may obtain priority listings for holding dimensions, relieving stresses, etc..The development of magnetostatic models most easily proceeds from the derivation of scalar potentials of separate geometric elements. These potentials can then be conbined at will because of the superposition characteristic of conservative force fields.

Prospects for convergent beam electron diffraction with a 200kV cold field-emission transmission electron microscope

1991 ◽  
Vol 49 ◽  
pp. 466-467
Author(s):  
J W Steeds ◽  
R Vincent
Keyword(s):  
Field Emission ◽  
High Performance ◽  
Small Diameter ◽  
Convergent Beam Electron Diffraction ◽  
Zone Axis ◽  
Medium Voltage ◽  
Transmission Electron ◽  
Good Crystallinity ◽  
Special Modification ◽  
Convergent Beam

We review the analytical powers which will become more widely available as medium voltage (200-300kV) TEMs with facilities for CBED on a nanometre scale come onto the market. Of course, high performance cold field emission STEMs have now been in operation for about twenty years, but it is only in relatively few laboratories that special modification has permitted the performance of CBED experiments. Most notable amongst these pioneering projects is the work in Arizona by Cowley and Spence and, more recently, that in Cambridge by Rodenburg and McMullan.There are a large number of potential advantages of a high intensity, small diameter, focussed probe. We discuss first the advantages for probes larger than the projected unit cell of the crystal under investigation. In this situation we are able to perform CBED on local regions of good crystallinity. Zone axis patterns often contain information which is very sensitive to thickness changes as small as 5nm. In conventional CBED, with a lOnm source, it is very likely that the information will be degraded by thickness averaging within the illuminated area.

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