Low drag attitude control for Skylab orbital lifetime extension

In the fall of 1977 it was determined that Skylab had started to tumble and that the original orbit lifetime predictions were much too optimistic. A decision had to be made whether to accept an early uncontrolled reentry with its inherent risks or try to attempt to control Skylab to a lower drag attitude in the hope that there was enough time to develop a Teleoperator Retrieval System, bring it up on the Space Shuttle and then decide whether to boost Skylab to a higher longer life orbit or to reenter it in a controlled fashion. The end-on-velocity (EOVV) control method is documented, which was successfully applied for about half a year to keep Skylab in a low drag attitude with the aid of the control moment gyros and a minimal expenditure of attitude control gas

Hyperfine characterization and coherence lifetime extension in Pr3+:La2(WO4)3

Rare-earth ions in dielectric crystals are interesting candidates for storing quantum states of photons. A limiting factor on the optical density and thus the conversion efficiency is the distortion introduced in the crystal by doping elements of one type into a crystal matrix of another type. Here, we investigate the system Pr3+:La2(WO4)3, where the similarity of the ionic radii of Pr and La minimizes distortions due to doping. We characterize the praseodymium hyperfine interaction of the ground state (3H4) and one excited state (1D2) and determine the spin Hamiltonian parameters by numerical analysis of Raman-heterodyne spectra, which were collected for a range of static external magnetic field strengths and orientations. On the basis of a crystal field analysis, we discuss the physical origin of the experimentally determined quadrupole and Zeeman tensor characteristics. We show the potential for quantum memory applications by measuring the spin coherence lifetime in a magnetic field that is chosen such that additional magnetic fields do not shift the transition frequency in first order. Experimental results demonstrate a spin coherence lifetime of 158 ms - almost three orders of magnitude longer than in zero field.Comment: 14 pages, 6 figure

A first Experimental Investigation of the Practical Efficiency of Battery Scheduling

Nowadays, mobile devices are used more and more, and their battery lifetime is a key concern. In this paper, we concentrate on a method called battery scheduling with the aim to optimize the battery lifetime of mobile devices. This technique has already been largely theoretically studied in other papers. It consists, for systems containing multiple batteries, in switching the load from one battery to the other. Then, while following a given scheduling sequence, advantage can be taken from the recovery and rate capacity effects. However, little studies with experimental data of battery scheduling have been found. In this paper we describe a simple setup for measuring the possible gain of battery scheduling, and give some exploratory results for two types of real batteries: a smart Li-Ion battery used in the Thales personal communication system and a more commonly used NiCd battery. The results, so far, show that system lifetime extension is not systematic, and generally can only reach less then 10%

A decision support tool to assist with lifetime extension of wind turbines

This paper is aimed at analysing the levelised cost of energy (LCOE) of onshore wind turbine generators (WTGs) that are in operation beyond their design lifetime. In order to do so, the LCOE approach is introduced and input parameters are discussed for a UK deployment. In addition, a methodology is presented to support economic lifetime extension and investment decision making at the end of an asset's design lifetime. As part of a case study, a wind farm consisting of six 900 kW WTGs is subjected to different combinations of i) lifetime extension (5- 15 years), ii) input assumptions (pessimistic, central, optimistic), and iii) re-investment types (retrofits). Results indicate that in the central lifetime extension scenario, LCOE estimates of 22.40 £/MWh are achievable

Lifetime-Management and Operational Lifetime Extension at Paks Nuclear Power Plant

The design life of the NPP PAKS WWER-440/213 units is 30 years. Formally the design life limits the operational licence. The condition of the equipment after almost 20 years of operation is excellent. The lifetime management activity of the Paks NPP provides a proper basis for the continuation of safe operation. The current Hungarian Nuclear Regulations allow the extension of the operation licence of the NPP Units beyond the design life. To prove the acceptability of continuation of operation the Licensee have to prepare a Licence Renewal Application not later than 5 years before the expiration of the design lifetime. The Licence Renewal process based mainly on USNRC approach taking into account the special features of the WWER-440/213 Units. Summary of the preconditions of the Licence Renewal and the activity for the preparation of the operational lifetime extension are reported in the paper

Battery Lifetime Extension Using Super capacitors in Small-Scale Wind-Energy System with fuzzy logic control

Because of the variable attributes of renewable era, batteries utilized as a part of renewable-force frameworks can experience numerous unpredictable, incomplete charge/release cycles. This study shows a technique for enhancing battery lifetime in a little scale remote-zone wind-power framework by the utilization of a battery/super capacitor half breed vitality stockpiling framework. An agent element model of the general framework, consolidating practical wind-speed and load power varieties has been produced