1,768 research outputs found
Implicit Auctioning on the Kontek Cable: Third Time Lucky?
No full textCross-border capacities in Europe are currently inefficiently used. Implicit auctioning is about eliminating these cross-border trade inefficiencies by internalizing the arbitrage into the auction procedures of the Power Exchanges that are organizing trade nationally. On the Kontek Cable, implicit auctioning has been implemented without price coordination between the involved Power Exchanges. This implementation, referred to as “volume or dome coupling” as opposed to “price coupling”, has been argued to be institutionally easier to implement. The Kontek Cable experimented with three different implicit auctioning implementations whose performance we analyze empirically in this paper. We find that the third implementation is significantly outperforming the previous two implementations, but in this third implementation stakeholders partly abandoned the volume coupling approach they initially believed to be a viable alternative to price coupling.electricity, transmission, congestion management, market coupling
Vibration of Bundled Conductors Following Ice Shedding
No full textThe dynamic behavior of bundled conductors following ice shedding from one subconductor is examined numerically using the finite-element method. An existing model of ice shedding from a single conductor is improved by developing a model of spacers which connect subconductors in the span. The resulting system makes it possible to simulate vibrations following ice shedding from one span of an overhead transmission line with twin, triple, or quad bundles. Vibration characteristics are evaluated as the following parameters are varied: thickness of shed ice, distance between adjacent spacers, and number of subconductors in the bundle. Simulation results will provide information on how the amplitude of vibration and the transient dynamic forces change with the application of spacers. The maximum jump height of the ice-shedding cable, the maximum drop of the loaded cable, and the maximum cable tension are approximated as power functions of ice thickness and the distance between adjacent spacers
Payload Placement on Board a Cable-Driven Parallel Robot with Workspace Including Tilt
No full textPublisher Copyright: © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.When it comes to planning the operation of a cable-driven parallel robot, the Available Wrench Set (AWS) is a very useful tool, describing conditions for suitable payload positions in the platform frame for a described set of poses. However, this is only applicable when no platform tilt is involved, as tilting has an impact on the wrench components when the payload is not placed at the platform reference center. For the cases where rotations are required, which can be combined with translations, the principle of a support polyhedron, derived from the AWS, is proposed in order for the robot designer to know where a payload should be placed on the platform to ensure static equilibrium at the target pose or set of poses, including tilt. With the AWS being based on a admissible range of cable tensions, an improved model of sagging cable focused on collision avoidance between cables, yielding a minimum cable tension, is also proposed in the paper. These analytical tools are then used to give a comprehensive analysis of the Cogiro robot featuring combined rotations around horizontal axes.Peer reviewe
Cable and wireless networks: theory & practice
No full textCable and Wireless Networks: Theory and Practice presents a comprehensive approach to networking, cable and wireless communications, and networking security. It describes the most important state-of-the-art fundamentals and system details in the field, as well as many key aspects concerning the development and understanding of current and emergent services.
In this book, the author gathers in a single volume current and emergent cable and wireless network services and technologies. Unlike other books, which cover each one of these topics independently without establishing their natural relationships, this book allows students to quickly learn and improve their mastering of the covered topics with a deeper understanding of their interconnection. It also collects in a single source the latest developments in the area, typically only within reach of an active researcher.
Each chapter illustrates the theory of cable and wireless communications with relevant examples, hands-on exercises, and review questions suitable for readers with a BSc degree or an MSc degree in computer science or electrical engineering. This approach makes the book well suited for higher education students in courses such as networking, telecommunications, mobile communications, and network security. This is an excellent reference book for academic, institutional, and industrial professionals with technical responsibilities in planning, design and development of networks, telecommunications and security systems, and mobile communications, as well as for Cisco CCNA and CCNP exam preparation
Nitrogen Ion Bombardment of Fuel Cladding Materials
No full textIn a nuclear reactor where there are high stresses, temperatures and radiation levels, a number of material problems can occur including corrosion, thermal fatigue cracking, and embrittlement. Material problems are a serious issue in regards to the performance, the advancement, and the safety of nuclear reactors under accident conditions. Fuel cladding materials are of particular significance since cladding is the most important safety barrier, as it contains the majority of radioactive fission products.
Nitriding is a method proven to improve many material properties including corrosion and wear resistance. Nitriding works by dissolving or implanting nitrogen into the surface of a material where the nitrogen bonds with the material atoms to form nitrides. The nitriding in these studies is performed by the use of ion bombardment with 40 KeV nitrogen atoms.
The purpose of this work is to improve understanding of this type of surface modification on fuel cladding materials. The materials used here are iron, 316L stainless steel, zirconium, and zircaloy-4. The focus of these studies was on fluence dependence and temperature stability of nitride layers induced by ion nitriding. Here it was found that by a fluence of 5E17 N/cm2, both pure Fe and SS316L are saturated and that by a fluence of 1E18 N/cm^2, both zirconium and zircaloy-4 are saturated. By 300��C in both Fe and SS316L and 600��C in zirconium and zircaloy-4, metastable nitrides have become unstable and nitrogen begins to diffuse out. Hardness test show that with a combination of irradiation and annealing, each material���s hardness can greatly be improved. However, the high mobility of nitrogen in iron at temperatures above 300��C limits the uses of iron alloys in very high temperature environments like reactors. Zirconium is shown to be stable up to temperatures approximately twice as high as iron indicating nitrides in zirconium alloys maybe able withstand reactor temperatures
Future Challenges for Cable Accessories in Medium Voltage Networks
No full textIn recent years, the architecture of the power system has been the subject of a major change. The commonly known structure with centralized generation and one directional power flow, gives gradually the place to the new concept of the power network where both the energy generators and consumers are distributed. Particularly, the continuously increasing environmental concerns as well as the legal regulations result in a widespread installation of renewables. In addition, storage devices are incorporated in the network in order to cope with sudden increase of the generated energy. To facilitate the energy flow from the renewables towards the power network, the proper voltage level is maintained by means of transmission controllers. Such controllers consist of high frequency switching elements and the operation of such devices introduces high frequency harmonics that are propagated in the vicinity of the installed controller. On the one hand, a high content of harmonics is an emerging issue for the power network. On the other hand, some researches show the deleterious effect of high frequency signals on the reliability of electrical insulation. Finally, for many years, the harmonic content was not considered neither during the design nor the component’s testing phase. In our paper, we will firstly review the published researches regarding the influence of harmonics on the reliability of cables, terminations and transformers. Further on, an approach to model the influence of high frequency on the electric field and temperature distribution in two types of medium voltage cable termination, will be made. 1 INTRODUCTIONDC systems, Energy conversion & Storag
Testing of a loop heat pipe experimental apparatus under varied acceleration
No full textDue to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to [email protected], referencing the URI of the item.Includes bibliographical references: p. 80-83.Issued also on microfiche from Lange Micrographics.An experimental apparatus was designed and fabricated to test a Loop Heat Pipe under varied acceleration. The experiment consisted of both flight and ground testing as well as comparisons to a model developed from models found in literature. The purpose of the work is to obtain data and compare to thermophysical model. The thermophysical model better explains the conditions of the fluid as it moves through the wick and through the interface. The model is used to evaluate approximate acceleration induced effects and startup temperature profiles in the LHP. Variable acceleration testing was done aboard NASA's KC-1 3 5 with ground testing being performed at Texas A&M's Interphase Transport Phenomena Laboratory. Results indicate that simple correlation's and models may be used to predict steady state and some transient performance of the LHP. The model is adapted from the LHP working cycle found in the patent and other literature describing the device. The predictions closely match test data for steady state operation in both the gravity assisted and gravity opposed orientations. Transient performance predictions also gave good results, but need further evaluation to validate the assumptions. Successful operation of the LHP under high gravitational acceleration and microgravity was completed with satisfactory prediction. The use of experimentally validated predictions will allow designers to use LHP's in space systems with higher confidence in expected performance
Cable\u27s Non-Cable Communications Services: Cable Television as as Common Carrier
No full textCable television companies can now provide two-way communications services allowing users to both receive and send messages. If unregulated, cable companies may gain an unfair advantage over the heavily regulated local telephone companies which formerly were the sole providers of two-way services. The author examines developments transforming the telecommunications industry and the classification of cable\u27s two-way services as non-cable services. The author recommends that cable companies be allowed to enter the telecommunications market and that their non-cable services be regulated under the same guidelines applicable to telephone companies providing similar services
Cable\u27s Non-Cable Communications Services: Cable Television as as Common Carrier
No full textCable television companies can now provide two-way communications services allowing users to both receive and send messages. If unregulated, cable companies may gain an unfair advantage over the heavily regulated local telephone companies which formerly were the sole providers of two-way services. The author examines developments transforming the telecommunications industry and the classification of cable\u27s two-way services as non-cable services. The author recommends that cable companies be allowed to enter the telecommunications market and that their non-cable services be regulated under the same guidelines applicable to telephone companies providing similar services
Axial response of resin-encapsulated cable bolts in monotonic and cyclic loading
No full textThe ease of use and the design flexibility of cable bolts have made them a popular choice for rock support. Cable bolts can be encapsulated with cementitious grout or resin. There is a need to better understand the impact of resins on the behaviour of cable bolts under varying load and stress regimes over their long service life. This study reports on 18 large scale resin pull-out tests using a 1000 kN pull-out apparatus. The testing apparatus minimised the rotational movement of the cable at the exit point by using a fully grouted anchor tube. Six cable bolts, ranging from 50 to 100 tonnes in capacity, anchored using a fast-curing urea silica resin, were tested under monotonic and cyclic loading. Each cable type was tested twice in monotonic loading and then the average initial peak load was used to generate a cyclic loading pattern. The study found that the resin product had a relatively low load capacity regardless of the cable type, and that loading type had a minimal impact on the results. The cable diameter had a minor influence on the pull-out results. The resin provided a stiff behaviour and an excellent response to repeated loading.The presentation of the authors' names and (or) special characters in the title of the pdf file of the accepted manuscript may differ slightly from what is displayed on the item page. The information in the pdf file of the accepted manuscript reflects the original submission by the author
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