Top PDF EMP control and characterisation on high-power laser systems

EMP control and characterisation on high-power laser systems

EMP control and characterisation on high-power laser systems

Giant electromagnetic pulses (EMP) generated during the interaction of high-power lasers with solid targets can seriously degrade electrical mea- surements and equipment. EMP emission is caused by the acceleration of hot electrons in- side the target, which produce radiation across a wide band from DC to terahertz frequencies. Improved understanding and control of EMP is vital as we enter a new era of high repetition rate, high intensity lasers (e.g. ELI, the Extreme Light Infrastructure). We present recent data from the VULCAN laser facility that demonstrates how EMP can be readily and effectively reduced. Characterisation of the EMP was achieved using B-dot and D-dot probes that took measurements for a range of different target and laser parame- ters. We demonstrate that target stalk geometry, material composition and foil surface area can all play a significant role in the reduction of EMP. A combination of electromagnetic wave and 3D particle-in-cell simulations are used to inform our conclusions about the effects of stalk geometry on EMP, providing an opportunity for comparison with existing charge separation models.
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Ellipsoidal plasma mirror focusing of high power laser pulses to ultra-high intensities

Ellipsoidal plasma mirror focusing of high power laser pulses to ultra-high intensities

Due to the limited research performed to date on this type of focusing plasma optic, especially in conjunction with petawatt scale laser systems, the present study helps to bring plasma-based optical technology closer to maturity. Under optimum alignment conditions, a peak intensity of ∼ 4 × 10 21 Wcm − 2 could be achieved when employing the FPM on the Vulcan PW laser system, as determined from the focal spot characterisation. Optimisation of the Vulcan laser to enhance the pulse energy and to decrease the pulse duration, could yield peak intensities close to 10 22 Wcm − 2 when using the FPM. This would provide a window into the physics achievable with future multi-petawatt laser systems. Focusing plasma mirrors such as the type described here could also be devel- oped for use on these higher power lasers, which would also push the intensity frontier achievable yet further. In the process, this will open up the exploration of new high field physics phenomena at the focus of intense laser pulses.
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Advanced high power pulsed fibre laser systems and their applications

Advanced high power pulsed fibre laser systems and their applications

In this thesis, ultrafast fibre sources are power scaled to very high average power by mitigating fibre nonlinearities not only by adequate choice of fibre characteristics but also by employing high-speed semiconductor lasers as seed sources for the systems. Indeed these seed lasers offer higher repetition rates than conventional seed sources, meaning that after amplification, average power can be scaled accordingly before the onset of nonlinearities. A key attraction of one of the seed sources resides in the selectable repetition rate which constitutes an ideal tool for controlling levels of nonlinear effects in the fibre amplifier. The unique combination of well controlled ultrafast semiconductor lasers and well designed high- power YDFAs led to the realisation of picosecond and femtosecond sources with average powers exceeding the hundred watts levels. Owing to the high degree of control of the pulse parameters provided by the system, optimal frequency conversion efficiency could be achieved leading to the development of a high-power picosecond green laser. This source was then utilised to pump a highly nonlinear fibre for efficient generation of white light. In addition, the versatility of the Yb based fibre source allowed investigation on the development of a laser guide star system based on picosecond pulses. In this case, the source was designed to pump a signal via stimulated Raman scattering and subsequently frequency- doubling resulted in pulsed laser radiation at 589 nm. These experimental realisations represent the core of this PhD thesis whose organisation is presented in the following.
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The importance of gas infrastructure in power systems with high wind power penetrations

The importance of gas infrastructure in power systems with high wind power penetrations

While the interaction of flexible generation capacity in support of renewable energy has been well studied [10,11], research on the effects and role of gas infrastructure on power systems with high renewable penetrations has been relatively limited. A review of the recent research in the field shows that much of the work has focused on developing new integrated gas and electricity models and applying the optimisation to test networks. In [12], a security constrained unit commitment (SCUC) model incorporating gas transmission constraints was developed and applied to a six bus power system and a seven node gas system. Several scenarios were analysed, including the impacts of gas transmission constraints, gas pipeline outages and varying natural gas loads. Further analysis of the SCUC model was conducted using a 118 bus power system and a 14 node gas system to show the effectiveness of the proposed model. It was found that gas transmission constraints resulted in higher daily operating costs than the case with no gas transmission constraints. In addition, variations in gas load as well as gas pipe- line infrastructure failures negatively impact system security and results in large levels of load shedding. A similar SCUC model was presented in [13] to assess the relationship between gas pipe- line outages and power system security. It was found that imple- menting a suitable fuel switching strategy in affected zones prevented some unit shutdowns. However, the overall system load shedding was directly related to the number of gas units unable to receive fuel. A co-optimisation planning model considering the relationship between gas and power infrastructure was presented in [14], where the ability of gas infrastructure expansion to trans- port the required fuel to the power system was considered in the iterative planning approach.
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High power (60mW) single frequency erbium:ytterbium codoped fiber laser

High power (60mW) single frequency erbium:ytterbium codoped fiber laser

Recent modelling of single frequency Yb:Er fibre laser.?, has pointed out that fibres with a high concentrationof Er and Yb ions should show reduced bottlenecking due to the increased Yb[r]

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Microstructural Characterization of Thermal Barrier Coatings
Glazed by a High Power Laser

Microstructural Characterization of Thermal Barrier Coatings Glazed by a High Power Laser

The microstructure of laser-glazed top surface is shown in Fig. 4a. It presents a fine polygonal cell structure with grain sizes varied from 2-8 microns. Fig. 4b shows the fractured cross section of coating. It reveals that the microstructure in the laser remelted regions is composed of columnar grains, which differe significantly from the lamina structure of plasma-sprayed coatings. Some small voids in the columnar grains can be observed. The release of gas during the laser remelting process, as discussed previously for the formation of craters on the coating surface, may be responsible for this phenomenon. The formation of columnar grains is a consequence of a unidirectional solidification of the liquid driven by a thermal gradient across the ceramic coatings. In the molten pool produced by laser irradiation, a thermal gradient which was perpendicular to the surface started to be formed immediately when the laser beam moved away from the molten pool. The heat was transmitted to the substrate and the surrounding air, then the grain growth was primarily perpendicular to the surface due to the direction of heat flow on cooling down to room temperature.
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ESP/ EMP: ARE STUDENTS PREPARED FOR IT?

ESP/ EMP: ARE STUDENTS PREPARED FOR IT?

The survey showed that the first-year Russian medical students (Sechenov University taken as an example) are not quite aware of the skills they need to acquire while doing an ESP/EMP course. Twenty two per cent of the students are unaware of their needs in ESP/EMP, 78 per cent of the students show partial awareness of the needs. The best awareness of needs comes from first- or at least second-hand experience in the professional sphere. First-hand experience can be obtained either through workplace learning, which starts when the ESP course is already over and usually does not involve communication with non-Russian-speaking colleagues or patients, or through previous employment in the sphere of healthcare. Second-hand experience means having family or friends employed in healthcare. This is true about only 16 per cent of students surveyed.
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On the Management of Power Constraints for High Performance Systems.

On the Management of Power Constraints for High Performance Systems.

Conventionally, general purpose CPUs have several identical complex cores, each supporting features such as multi-issue pipelines, branch prediction and out-of-order processing to maximize performance. However, these CPUs are not fully utilized all the time during workload execution. In a post Moore era, transistors will not be free and CMOS real estate will be a design constraint. Hence, we will have to design the sleekest processors by maximizing utilization of transistors on the chip to achieve improvements in performance and power efficiency. Toward this end, we need to evaluate Heterogeneous System Architectures (HSA), such as the “Big Little“ architecture [biglittle ; Vil14 ] , that fit the bill. A first step in this direction will be to conduct thorough performance analysis of the state of the art workloads on these architectures. Such architectures under load pose interesting problems such as determining the optimal workload distribution across different types of cores, the choice of cores to execute a workload, and dynamic scheduling of tasks across heterogeneous processing elements to meet the performance and power targets. The ideas presented in this dissertation can be foundational in solving these problems but HSA would provide more and finer knobs to support optimal resource allocation for maximizing the power efficiency of the system.
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Electronic Suit with EMP for Defense

Electronic Suit with EMP for Defense

ABSTRACT: The core objective of this project is to design anelectronic suit for security purpose. This project is anexoskeleton suit which provides the improvement todefense in battle field for soldiers and spies. It hasvarious gadgets that helps soldiers to take outenemies more easily. This suit is equipped with EMPwhich disables any electronic equipment. And it isequipped with optical weapon laser ammo whichhelps the soldiers to toggle enemies while reloadingthe ammo or out of ammo.It reportsthe location of the soldier to thebase by the GPS.The suit assists the soldiers byproviding both the rear and front view by the hand display with a spycam and gives a warning with the miniature radar.
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Distributed Control and Optimization for Communication and Power Systems

Distributed Control and Optimization for Communication and Power Systems

Besides my advisor, I would like to thank the rest of my thesis committee: Professor John Doyle, Professor Mani Chandy, Professor P. P. Vaidyanathan and Professor Adam Wierman. It’s really my great honor to have them on my committee. They gave me their insightful comments and encouragement. I learned advanced control theory in John’s class. Mani raised many interesting questions in both my candidacy exam and thesis defense that were very beneficial in the completion of my thesis. I was in P. P. V’s class on signal processing and he could always explain the complex formula from different perspectives. Adam gave me great help and advice on writing good papers and making presentations. He taught me how to communicate complicated ideas through plain English that people could easily understand.
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Power gain analysis and control of nonlinear systems

Power gain analysis and control of nonlinear systems

Clearly this scheme is numerically very intensive. Furthermore, the test in Step 3 for divergence or convergence can never be absolutely conclusive since only a finite number of value iterations can be performed. As such, the usefulness of the bisection scheme for approximating both the available power Aa and the infinite horizon available storage V& is limited. However, in computing V&(x) with Aa known, the value space iteration (4.74) is very useful. Even without knowledge of the exact available power, a centered scheme such as th at presented in Section 4.3 can provide an accurate approximation of the available power, which may then be used in (4.74). Although using a centered scheme first may appear to defeat the purpose, it is important to remember th at centered schemes can only compute the normalization Vfc(x) — V i ( xq ) (for some reference state
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Control of power electronic interfaces for photovoltaic power systems for maximum power extraction

Control of power electronic interfaces for photovoltaic power systems for maximum power extraction

To investigate the behaviour of the inverter and its performance in relation to the other subsystems, a simulation model is developed using MATLAB/Simulink dynamic systems software. Previous chapters of this thesis have discussed the modelling of the other major subsystems of the complete PV power plant, Fig. 6.14. Those models are now integrated with the voltage source inverter based on the H-bridge topology to realise the complete model of Fig. 6.15. In Fig. 6.15, the PV array is the primary power source and generates a dc power. This is stepped up by the SEPIC converter to provide a dc link voltage of 180V. This voltage is used as input to the inverter and as a source to the bidirectional dc-dc converter to charge the energy storage system as explained earlier in Chapter 5. The bidirectional dc-dc converter also operates during periods of low insolation or night time to discharge the battery bank which serves as a backup power supply. The LC filter which is integrated with the transformer in the model filters out the high frequency harmonics generated from the switching action of the inverter. Since the 180V of the dc link is not enough to provide the needed ac output voltage of 240V, the filtered output is stepped up by the line frequency transformer.
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High power density STATCOM with extended reactive power control range

High power density STATCOM with extended reactive power control range

Abstract—This paper proposes a new configuration for static synchronous compensator (STATCOM) based on the ac-side voltage doubling voltage source converter (ACVD-VSC), which has twice of the dc-link voltage utilization as two-level VSC, hence improved power density per unit dc-link voltage. This means its dc voltage limit for reactive power generation is higher than that using conventional two-level VSC. Therefore, extended reactive power control range is resulted for the proposed solution. Also the ACVD converter has zero dc common mode voltage between the ac neutral point and the dc-link negative terminal, reducing the insulation level for the interfacing transformer when the negative dc bus is grounded. The basic operation principles of ACVD-VSC are reviewed. Then, it is used to perform voltage or power flow control as shunt compensators.
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Robust Downlink Power Control in Wireless Cellular Systems

Robust Downlink Power Control in Wireless Cellular Systems

to cellular communication systems [4, 6, 7, 8, 9, 10, 11, 12, 13, 14]. The user SINR criterion has been adopted in these papers to optimize the transmitted powers and beamformer weights to ensure that the QoS requirements are satisfied for all users. For example, in [8, 13], the problem of optimal cen- tralized power control and downlink beamforming is consid- ered in the case when the exact downlink channel informa- tion is available at the base stations. Several other works con- sider simpler suboptimal power control and/or beamform- ing methods [7, 9, 10, 14].
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A stabilising control strategy for Cyber-Physical Power Systems

A stabilising control strategy for Cyber-Physical Power Systems

Abstract: The cyber-physical nature of electric power systems has increased immensely over the past decades, with advanced communication infrastructure paving the way. It is now possible to design wide-area controllers, relying on remote monitor and control of devices that can tackle power system stability problems more effectively than local controllers. However, their performance and security relies extensively on the communication infrastructure and can make power systems vulnerable to disturbances emerging on the cyber side of the system. In this study, the authors investigate the effect of communication delays on the performance of wide-area damping controllers designed to stabilise oscillatory modes in a cyber-physical power system (CPPS). They propose a rule-based control strategy that combines wide-area and traditional local stabilising controllers to increase the performance and maintain the stable operation of CPPS. The proposed strategy is validated on a reduced CPPS equivalent model of Great Britain.
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Analysis of Delay in Feedback Power Control for CDMA Systems

Analysis of Delay in Feedback Power Control for CDMA Systems

Feedback delay affects the performance of closed loop power control in CDMA system. The increasing on fading rate will generate deeper fade that is more difficult to be tracked with small step size. In case of fading rate, we can consider that power control is not properly work in higher fading rate e.g. fading rate=100 Hz. The performance is also affected with the design of step size at mobile station. In relation to the step size, we have seen that the setting of 1 dB is more appropriate for higher feedback delay e.g. feedback delay=3T p while system of 2dB is more appropriate for lower feedback delay e.g. feedback delay=1T p . If the total feedback delay can be minimized e.g. until 1Tp, then the application of 2dB will be better than 1 dB. Conversely, if total feedback delay is difficult to be minimized, then the system of 1 dB is more applicative for higher feedback delay. Therefore, there is a trade off between step size=1 dB or 2 dB to be created at mobile station. But from the perspective of efficiency in received power (that correspondence with the capacity), we have found that the system of 1dB is better than the system of 2 dB at feedback delay =2T p . In this case, a mobile user can still operate at lower Eb/Io with implies many users can be served at base station. At the end of section, we conclude that the system of1 dB generally is still better than 2 dB from aspect of delay and capacity. The effect of feedback delay algorithm was analyzed in Rayleigh fading channels. Results show that feedback delay puts strict limits to the applicability of closed–loop algorithms within high mobile speeds while the effect of feedback bit errors is not crucial if a constant bit error rate is assumed. Closed loop power control can improve the BER performance of slow fading channel. However, power control is not perfect due to feedback delay and finite step size, which produce residual variation of the SIR (power control error). Under ideal conditions, variable step algorithms perform better than fixed step algorithms.
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Artificial intelligence application to security control in power systems

Artificial intelligence application to security control in power systems

Furthermore, an application of the stability margin analysis to measure the security level in steady state security control, presented in Chapters 5 and 8, and methods of optimal allocat[r]

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Robust Power Control of Microgrid based on Hybrid Renewable Power Generation Systems

Robust Power Control of Microgrid based on Hybrid Renewable Power Generation Systems

This paper presents modeling, control and power control in a grid connected PV/Fuel Cell/Battery hybrid power generation system in a microgrid. SIMULINK/SIMPOWER was used to model the system and simulate a power flow control strategy. PV, fuel cell and battery subsystems with power electronic converters are modeled. Then control strategies are designed for power electronic converters based on the classic and sliding mode control. It was shown that the microgrid can be controlled as desired to follow the local demand and allow the grid to operate at or near unity power factor. Controllers design methodologies for power electronic converters in order to manage the power flow from microgrid to the utility grid during normal operation and unbalanced voltage conditions are introduced. Moreover, to distribute the power between power sources, the neuro-fuzzy power controller has been developed to stabilize the DC-link power. The stability of proposed controller has been proved by Lyapanov theorem. Simulation results are illustrated to demonstrate the effectiveness and capability of proposed control strategy during different operating conditions in utility grid. Simulation results are presented to demonstrate the effectiveness of the control strategy.
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Some aspects of modelling and control of automotive power systems

Some aspects of modelling and control of automotive power systems

Given a vehicle that has no special emissions controls the effect of certain design and operating variables on emissions can be summarised (Table 3.3). Chapter 5 of Reference 3.63 contains a good description of these effects. From the control viewpoint it can be said generally that spark retard from MBT spark timing reduces HC and NOx, worsens fuel consumption but has little or no effect on CO. The effect of air-fuel ratio has been described above with reference to Figure 3.11. A third control variable, exhaust gas recirculation, though not presently used in Europe, has found use in the O.S.A. and Japan. It is a primary NOx reduction agent which feeds some of the exhaust gases back into the inlet, thus reducing peak combustion temperatures by charge dilution. The major problem with EGR is the reduction in driveability which often necessitates a richer mixture.
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