Proceedings of the International Astronautical Congress, IAC | Year: 2013
The static operation of an EmDrive microwave thruster has once again been demonstrated by the Chinese experimental work reported in REF 1. The work repeats and enhances results obtained in earlier UK experiments, REF 2, and confirms the direct relation between specific thrust and Q factor of the cavity. This paper considers the dynamic operation of a thruster with the very high Q factors obtained when a cavity employs superconducting technology. The very high specific thrusts resulting from such second generation (2G) devices must be subject to the law of conservation of energy. It follows therefore, that there must be a mechanism which limits the acceleration of any vehicle propelled by a 2G EmDrive thruster. A mathematical model of a 2G thruster is described which illustrates such a mechanism. The results from the model illustrate the Doppler changes, which occur when a thruster is subject to acceleration. For Q factors around 1 × 109, the total Doppler shift moves the frequency outside the narrow resonant bandwidth of the cavity. This causes the loaded Q of the cavity, and thus the specific thrust, to decrease and therefore limits the acceleration. A technique, employing pulse operation and dynamic control of the cavity length, is described which enables partial compensation for the effect. The resulting thruster design, employing YBCO superconducting walls and liquid hydrogen cooling, achieves a specific thrust of 1 Tonne per kW, provided the acceleration is limited 0.5m/s/s. This low acceleration rate is compatible with primary in-orbit propulsion applications, and will be particularly suitable for deep space missions. For launch vehicles, the acceleration limitation is no obstacle; as a flight profile is proposed where high velocity is only achieved once clear of the atmosphere. Indeed the reusable, EmDrive propelled carrier vehicle itself, is only used to lift the payload to geostationary altitude, where an expendable propulsion module is used to provide orbital velocity. The resulting costs to geostationary orbit are predicted to be 130 times lower, when compared to current launch vehicles. Copyright ©2013 by the International Astronautical Federation.
IET Conference Publications | Year: 2013
This paper describes Vattenfall's long term platform which is intended to cope with the quantity and rate of change of innovation driven by new Regulatory requirements and Smart Grid developments.
IET Conference Publications | Year: 2012
Our experience suggests that an organisations' ability to solve their own problems are indicative of how likely they are to improve their overall performance. Many organisations deal with their problems in an order of priority, which is of course a highly effective method of tackling the right things. This can be negatively impacted however if a 'band-aid' approach affects the items on the priority list. Additionally, employing a one-size-fits-all approach to tackling problems often leads either to the simple problems becoming over-bureaucratised or the complex problems not being sufficiently analysed to fully understand their contributing factors. A proportionate approach to problem solving applies the appropriate level of rigour required to ensure that each problem is fully resolved, with the minimum amount of effort.
Asian Journal of Pharmaceutical and Clinical Research | Year: 2015
Objective: Prunus persica leaves are used as anthelmintic, insecticidal, sedative, diuretic, demulcent, expectorant and vermicidal ethnopharmacologically. The objective of the present study was an evaluation of anthelmintic activity of different extracts of P. persica leaves. Methods: Pheretima posthuma (annelids) and Ascaridia galli (nematods) were used to perform experiments for anthelmintic activity. Piperazine citrate was used as a standard. The time required for paralysis and death (lethal time) of worms were noted for each sample of P. persica extracts and standard. Results: The results demonstrated that the treatment with P. persica significantly (p<0.05-p<0.01) with dose-dependently paralyzed and killed the both A. galli and earthworms. Ethanol and ethyl acetate extracts have showed the comparable anthelmintic activity at the highest concentration (60 mg/ml) to the well-known anthelmintic agent piperazine citrate against A. galli. Conclusion: The ethanolic and ethyl acetate extracts exhibited the maximum potency, i.e. shortest paralysis and lethal times. The potency was not more than the reference drug, piperazine citrate but comparable to it at 60 mg/ml concentrations in both test worms. © 2015, Asian Journal of Pharmaceutical and Clinical Research. All rights reserved.
Engineering and Technology | Year: 2014
Some of the letters addressed to The Editor, E&T, are discussed. Brian Highe, in his letter, questions on Dickon Ross's editor's letter in the February issue of E&T, and poses several questions about the apparently utopian scene portrayed on the front cover. A letter by Mike Pannell discusses Dennis Sharp's letter about his unsatisfactory experience with mains LED lamps in a new house (February 2014) typifies the problems consumers face when trying to make good environmental decisions. Ian Griffiths, in his letter, is disappointed by Derek Salkeld's Comment column on risk management in the February 2014 issue. He says that the author only describes a process that enables project managers to make an estimate of the value of contingency, and does not cover any of the techniques that risk managers use to mitigate the identified risks and ultimately enable project managers to make timely decisions to maintain project schedules.