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[en] The pilot training results shown that the used approach is appropriate and could be disseminate among the interested parties. • The interest from the side of the different professionals is an important indicator about the necessity to care such courses for non-nuclear professionals.The effectiveness of the training program for non-nuclear specialists will be assessed using the replies of the Course evaluation form as well as the feedback from employers, trainers and observers
[en] GaAs/AlGaAs quantum-wire (QWR) gain-coupled distributed-feedback (GC-DFB) lasers were fabricated and characterized. Interestingly, as the shape of the active grating was varied, the lasing characteristics changed greatly; for example, one laser with sharp gratings lased at a threshold current of 13 mA while another one with dull gratings lased at 230 mA. This may be due to a change in the gain coupling coefficient with the shape of the QWR active grating. Little observation of the stopband and the wavelength consistency between the lasing and the photoluminescence peaks of the QWRs also provided evidence for lasing via GC-DFB effects in these devices
[en] Feedback control engineers have been interested in multiple-input-multiple-output (MIMO) extensions of single-input-single-output (SISO) results of various kinds due to its rich mathematical structure and practical applications. An outstanding problem in quantum feedback control is the extension of the SISO theory of Markovian feedback by Wiseman and Milburn [Phys. Rev. Lett. 70, 548 (1993)] to multiple inputs and multiple outputs. Here we generalize the SISO homodyne-mediated feedback theory to allow for multiple inputs, multiple outputs, and arbitrary diffusive quantum measurements. We thus obtain a MIMO framework which resembles the SISO theory and whose additional mathematical structure is highlighted by the extensive use of vector-operator algebra.
[en] The letters collected in this focus issue of Environmental Research Letters on ‘Environmental, socio-economic and climatic changes in Northern Eurasia and their feedbacks to the global Earth system’ represent the third special issue based on the results of research within the Northern Eurasia Earth Science Partnership Initiative (NEESPI: http://neespi.org) program domain. Through the years, NEESPI researchers have presented a diverse array of articles that represent a variety of spatial scales and demonstrate the degree to which abrupt climatic and socio-economic changes are acting across Northern Eurasia and feed back to the global Earth system. (synthesis and review)
[en] A large number of plant operators on the Sellafield site require criticality awareness training. Historically, this training had been developed and delivered largely by the Criticality Safety team in isolation, with a heavy focus on the physics of criticality. Feedback from operators indicated that the historic training approach perhaps over emphasised the physics of criticality as an abstract concept, while potentially under emphasising more practical considerations for day to day work on the plants. This paper discusses some of the improvements that have been made to the training courses and the methods of delivery over recent years at Sellafield. (author)
[en] Gain saturation is treated by formulating a model that accounts for the dependence of gain on irradiance level in distributed-feedback lasers. Solutions of the coupled-mode equations of the model are obtained numerically and are presented for both overcoupled and undercoupled laser structures (KL in the 1013--10 range). Parasitic losses that are distributed uniformly within the structure are found to influence the output power characteristics of distributed-feedback lasers. Also the optimum coupling strength that results in the most efficient conversion of pump power to useful laser output is determined. The optimum coupling strength for any distributed-feedback laser is dependent on the magnitude of the parasitic losses and on the required output-power level
[en] A control problem of a class of input-delayed linear systems is considered in this paper. Due to the delay τ in the input, any designed feedback controller can only be engaged after t ≥ τ. Then, this can become the cause of slow regulation since any feedback information cannot be available during the delay. So, the initial function defined for -τ ≤ t ≤ 0 is engaged as an ‘initial non-feedback input’ for 0 ≤ t ≤ τ, which governs the system behavior during this initial time period. There have been numerous research results on the control of input-delayed linear systems by far. Yet, there have been no results on the examination and design of this initial function. Utilizing a time optimal control in the existing results, we show that if some pre-feedback as the initial function is engaged, the system response of the input-delayed linear system can be much improved, and a bang-bang input function is a good candidate as a pre-feedback which can provide better starting state values for the state feedback controller in order to perform the fast regulation. Two examples are given for the illustration of our results.
[en] We implement a mackerel (Scomber scombrus) body-shaped robot, programmed to display the three most typical body/caudal fin undulatory kinematics (i.e. anguilliform, carangiform and thunniform), in order to biomimetically investigate hydrodynamic issues not easily tackled experimentally with live fish. The robotic mackerel, mounted on a servo towing system and initially at rest, can determine its self-propelled speed by measuring the external force acting upon it and allowing for the simultaneous measurement of power, flow field and self-propelled speed. Experimental results showed that the robotic swimmer with thunniform kinematics achieved a faster final swimming speed (St = 0.424) relative to those with carangiform (St = 0.43) and anguilliform kinematics (St = 0.55). The thrust efficiency, estimated from a digital particle image velocimetry (DPIV) flow field, showed that the robotic swimmer with thunniform kinematics is more efficient (47.3%) than those with carangiform (31.4%) and anguilliform kinematics (26.6%). Furthermore, the DPIV measurements illustrate that the large-scale characteristics of the flow pattern generated by the robotic swimmer with both anguilliform and carangiform kinematics were wedge-like, double-row wake structures. Additionally, a typical single-row reverse Karman vortex was produced by the robotic swimmer using thunniform kinematics. Finally, we discuss this novel force-feedback-controlled experimental method, and review the relative self-propelled hydrodynamic results of the robot when utilizing the three types of undulatory kinematics. (paper)
[en] In this paper, a scheme of close-loop feedback is proposed to induce transition of spiral pattern in the excitable media, which is described with the modified FitzHugh-Nagumo model. The numerical simulation results confirm that the stable rotating spiral wave is removed and the whole media becomes homogeneous when appropriate intensity of feedback is used no matter whether the coupling feedback is imposed on the whole media or the sites in one line in the media
[en] Recently Sagawa and Ueda [Phys. Rev. Lett. 100, 080403 (2008)] derived a bound on the work that can be extracted from a quantum system with the use of feedback control. For many quantum measurements their bound was not tight. We show that a tight version of this bound follows straightforwardly from recent work on Maxwell's demon by Alicki et al. [Open Syst. Inf. Dyn. 11, 205 (2004)], for both discrete and continuous feedback control. Our analysis also shows that bare, efficient measurements always do non-negative work on a system in equilibrium, but do not add heat.