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[en] We report on the experimental observation of the Fermi–Pasta–Ulam (FPU) recurrence in an experimental bi-modal nonlinear transmission line. The FPU recurrence is observed in the two transmission modes known as the low frequency mode and the high frequency mode. In each case, a spectrum analysis is performed in order to study the waves along the line. (paper)
[en] This report discusses methods of calculating loss costs in transmission grid systems and distribution networks in Norway and updates previous specific loss costs. For this updating, the stylized network on which the specific loss costs are calculated have been modified. The number of radial levels have been reduced by combining the 132 kV and the 66 (47) kV networks. In addition to reducing the number of main levels, it was decided to introduce a stronger differentiation at the distribution level. The principle of alternative loss costs at distribution level has been extended by introduction of a third alternative for distribution networks which concerns cable grids in regions of intermediate area load, in addition to cable grids with high area load and overhead cables. It is found that the loss costs have not changed much for the highest levels since 1992. For the distribution network, however, there is a considerable increase in loss costs. Networks containing energy-intensive industries are not considered. 14 refs., 19 figs., 41 tabs
[en] An RF transmitter is proposed for 3-5 GHz time-hopping ultra wideband (TH-UWB) wireless applications. The transmitter consists of a 4-GHz oscillator, a switch with a controllable attenuator and an output matching circuit. Through controlling the low frequency signals with time-hopping pulse position modulation (TH-PPM), the circuit supplies TH-UWB signals and can directly drive an antenna by a transmission line. The transmitter was implemented in a 0.18-μm CMOS technology; the output amplitude is about 65 mV at a 50 ? load from a 1.8-V supply, the return loss (S11) at the output port is less than -10 dB, and the chip size is 0.7 x 0.8 mm2, with a power consumption of 12.3 mW.
[en] Based on the transmission line code TLCODE, a 1D circuit model for a transmission-line impedance transformer was developed and the simulation results were compared with those in the literature. The model was used to quantify the efficiencies of voltage-transport, energy-transport and power-transport for a transmission-line impedance transformer as functions of ψ (the ratio of the output impedance to the input impedance of the transformer) and Γ (the ratio of the pulse width to the one-way transit time of the transformer) under a large scale of m (the coefficient of the generalized exponential impedance profile). Simulation results suggest that with the increase in Γ, from 0 to ∞, the power transport efficiency first increases and then decreases. The maximum power transport efficiency can reach 90% or even higher for an exponential impedance profile (m = 1). With a consideration of dissipative loss in the dielectric and electrodes of the transformer, two representative designs of the water-insulated transformer are investigated for the next generation of petawatt-class z-pinch drivers. It is found that the dissipative losses in the electrodes are negligibly small, below 0.1%, but the dissipative loss in the water dielectric is about 1% to 4%. (fusion engineering)
[en] The article reviews the theory and technology of electric power cables from the nineteenth century to the present day. It is the second of two planned articles. The present article deals largely with maritime cables
[en] Competitive markets set a framework in which unregulated market-based interconnections are allowed and encouraged. However, the presence of merchant transmission lines in the role of interconnector raises questions about the impact of these agents on the market conditions and system operation. The interconnector could be allowed to withhold capacity in order to keep the price difference (and profit of it) or be enforced by a must-offer provision to bid all its capacity. In this paper, the long-term dynamic of a market interconnection is studied and analyzed in a test system through a bottom-up simulation model. The outcomes are measured by the level of electricity prices along the simulated period and the annual amount of energy not supplied. The results show that the prices are strongly affected in the average value and in the standard deviation. The benefits of an interconnection as regards reliability are not hidden by the merchant nature of the interconnector. The results of the simulation show that letting the interconnector to control the bids of capacity offered to the markets is not detrimental to the markets. However, there is a lost of benefits compared with the case of a mandatory must-offer provision if compared at the same capacity of transmission line. (author)
[en] An efficient numerical code for simulating the propagation of a high-power electromagnetic pulse in a vacuum transmission line is required to study the physical phenomena occurring in such a line, to analyze the operation of present-day megavolt generators at an ∼10-TW power level, and to design such new devices. The main physical theoretical principles are presented, and the stability of flows in the near-threshold region at the boundary of the regime of magnetic self-insulation is investigated based on one-dimensional telegraph equations with electron losses. Numerical (difference) methods-specifically, a method of characteristics and a finite-difference scheme-are described and their properties and effectiveness are compared by analyzing the high-frequency modes.
[en] In long distance heat transmission and distribution systems, as designed so far, when the temperature of the air rises, the amount of heat distributed diminishes and the amount of heat lost through the walls of the pipe diminishing too, these systems absorb much less heat in summer than in winter and this is a serious drawback when they contribute in cooling a nuclear power station or other thermal power station. In the compensating system described in this invention, although the amount of heat distributed diminishes with the rise in air temperature, the amount of heat lost through the walls of the return line rises. This can enable such a system to be made to absorb as much heat in the summer as in winter, and should the need arise in certain cases, more heat in summer than in winter, when these lines are long enough. Contrary to normal heat transmission and distribution line systems where the pipes are insulated throughout their entire length, in the type of system described in this invention, only the 'outward' pipe is insulated the larger section 'return' pipe is not insulated and works as a heat diffuser, either into the air when there is no frost risk or into the ground to a shallow depth
[fr]Dans les circuits de transport et distribution de chaleur a grandes distances, tels qu'on les a etablis jusqu'ici, lorsque la temperature atmospherique s'eleve la quantite de chaleur distribuee diminue et la quantite de chaleur perdue par les parois de la conduite diminuant aussi il se trouve que ces circuits absorbent beaucoup moins de chaleur l'ete que l'hiver ce qui est un inconvenient grave lorsque ces circuits participent au refroidissement d'une centrale nucleaire ou autre centrale thermique. Dans le circuit compensateur faisant l'objet de la presente invention, si la quantite de chaleur distribuee diminue avec l'elevation de la temperature atmospherique par contre la quantite de chaleur perdue par les parois de la conduite 'retour' augmente, ce qui peut permettre de faire absorber par un tel circuit autant de chaleur l'ete que l'hiver, voire meme dans certains cas, et si c'etait necessaire, plus de chaleur l'ete que l'hiver, lorsque ces circuits sont assez longs. Contrairement aux circuits normaux de transport et distribution de chaleur dont les conduites sont calorifugees sur toute leur longueur, dans le type de circuit faisant l'objet de la presente invention seule la conduite 'aller' est calorifugee, la conduite 'retour', de plus forte section, ne comporte aucune isolation et fonctionne comme diffuseur de chaleur, soit dans l'air lorsqu'il n'y a pas risque de gel soit dans le sol a faible profondeur