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Based on the dynamic load-line GaN HEMT large signal model and load-pull technology, a high efficiency harmonic tuned power amplifier operating at 2 GHz is designed and implemented. Under the condition that the parasitic parameters and package parameters of the transistor are unknown, the optimal fundamental and harmonic impedance values that meet the performance requirements are initially determined by the load-pull technology, and tuning and optimizing the overall circuit of the power amplifier based on the drain current and voltage waveforms obtained from the dynamic load-line large signal model. The measured results show that, when the input power is 27 dBm, the drain efficiency reaches 81.53%, the power added efficiency is 76%, the output power is 38.69 dBm, and the gain is 11.69 dB. The high-efficiency harmonic tuned power designed by this method has the advantages of simple structure and convenient tuning, while satisfying high performance.

The effect of trace elements (TEs) addition and NaOH pretreatment on the anaerobic digestion of rice straw was investigated in batch tests. Co, Ni and Se were added to the raw rice straw at different dosages. The NaOH pretreatment was applied to the rice straw both alone and in combination with the addition of TEs, in order to evaluate potential synergistic effects of the pretreatment and the TEs supplementation on the biogas production yields. The results obtained showed that the alkaline pretreatment was more effective than the TEs addition in increasing the cumulative biogas production, causing a 21.4% enhancement of the final biomethane yield, whereas the increase due to TEs dosing was not statistically significant. The analysis of volatile fatty acids (VFAs) confirmed that the NaOH pretreatment resulted in a higher production of VFAs, indicating an increased hydrolysis, while TEs addition did not cause significant changes in the VFA concentrations.

A new mechanism of harmonics generation (HG) induced by quantum electrodynamics (QED) effects in extreme intense laser foil interaction is found and investigated by particle-in-cell (PIC) simulations. When two laser pulses with identical intensities of 1.6 × 1024 W cm-2 are counterincident on a thin foil target, harmonics emission is observed in their reflected electromagnetic waves. Such harmonics radiation is excited due to transversely oscillating electric currents coming from the vibration of QED effect generated e-e+ pairs. The effects of laser intensity and polarization were studied. By distinguishing the cascade depth of generated photons and pairs, the influence of QED cascades on HG was analyzed. Although the current HG is not an efficient way for radiation source applications, it may provide a unique way to detect the QED processes in the near future ultra-relativistic laser solid interactions.

The smart grid is a fully automatic delivery grid for electricity power with a two-way reliable flow of electricity and information among different equipment on the grid. Smart meters and sensors monitoring the system provide a huge amount of data in various part of smart grid. To logically manage this trouble, a new lossy data compression approach for big data compression is proposed. The optimal singular value decomposition (SVD) is applied to a matrix that achieves the optimal number of singular values to the sending process, and the other ones will be neglected. This goal is done due to the quality of retrieved data and the compression ratio. In the presented scheme, to implement the optimization framework, various intelligent optimization methods are used to determine the number of optimal values in the elimination stage. The efficiency and capabilities of the proposed method are examined using a wide range of data types, from electricity market data to image processing benchmarks. The comparisons show that the compression level obtained by the proposed method can dominate the points given by the existing SVD rank reduction methods. Also, as the other finding of this article, the performance of the rank reduction methods depends on the application and data types. It means that a rank reduction method can reveal a good performance in one application and performs unacceptably for another purpose. So, the optimized rank reduction can pave the way toward a robust and reliable performance.

This thesis investigates the way to reduce the maintenance cost and increase the life cycle of the offshore wind turbines, as in the offshore case maintenance is highly difficult and expensive.\ud \ud Firstly, we study the possibility to replace the vulnerable and expensive DC link capacitor in wind power integration system by the virtual infinite capacitor (VIC), which is a power electronic circuit functioning as a large filtering capacitor. We propose a control algorithm for the VIC. Before applying it to the wind power system, we firstly test it in a simple power factor compensator (PFC) as the output filter capacitor. The simulation results show the effective filtering performance of VIC in low-frequency range. Then, we validate it experimentally by directly injecting the DC voltage together with a 50 Hz ripples to the VIC. The VIC successfully eliminates the ripple and extracts the DC voltage at the output terminals. Besides, the experiment performances are highly consistent with the corresponding simulations, which demonstrates the possibility to use VIC to replace the DC-link capacitor in wind power integration system and use it in other industrial systems.\ud \ud Since the VIC mainly filters the ripple in low frequency range while the DC-link voltage usually includes ripples in two distinct frequency ranges, we further develop it into the parallel virtual infinite capacitor (PVIC), aiming to suppress the voltage ripple in a wider frequency range. The PVIC is applied to replace the DC-link capacitor in wind turbine grid integration system. The simulations are conducted under different grid conditions with turbulent wind input. The results show that the PVIC provides much better voltage suppression performance than the equivalent DC-link capacitor, which facilitates the power generation control under normal operations and reduces the risks of converter failure under grid faults. In this way, the PVIC proves to be a great solution to substitute the vulnerable DC-link voltage in the offshore wind turbine power integration system.\ud \ud The wind power conversion system from the generator to the grid is composed of a DC-link capacitor and two back-to-back power converters. Though the application of PVIC removes the fragile DC-link capacitor in the power conversion system, the power converters are also fragile and expensive. In addition, the existence of power converters decouples the generator with the grid, which hinders the direct inertia support and frequency regulations from wind turbines. It would be desirable to completely remove the whole power conversion system. Hydrostatic wind turbine (HWT) may provide a suitable solution. The HWT is a wind turbine using hydrostatic transmission (HST) to replace the original heavy and fragile gearbox. The HST can provide the ‘continuously variable gearbox ratio’ , which allows HWT to be connected to a synchronous generator (SG) and then directly to the grid. We propose a coordinated control scheme for the HWT. The simulations are conducted with turbulent wind under variable system loads. The results indicate that with the proposed coordinated control system, the HWT (without power converters) provides efficient frequency support to the grid, which shows it is a promising solution for the future offshore wind power system.\ud \ud Finally, we consider to further reduce the maintenance cost and improve the performance of the HWT by using a new and novel control algorithm called model-free adaptive control (MFAC). It is applied to both torque control and pitch control of the HWT. Their control performances are compared to some of the existing algorithms. The simulation results demonstrate that the MFAC controller has much better tracking and disturbance rejection performances than the existing algorithms which can increase the fatigue life of the wind turbine and reduce the maintenance cost.

Photodetachment studies of atomic and molecular negative ions in the gas phase are presented. Negative ions are loosely bound quantum systems whose existence is strongly dependent on the correlations between the electrons. This makes sophisticated calculations of the structure and dynamics for these systems complex and experimental data are needed for verification. Negative ions are also important in applications such as plasma etching and atmospheric studies. One of the most important applications for negative ions is as the state of matter for injection in tandem accelerators used in Accelerator Mass Spectrometry (AMS), the most sensitive method for ultra trace isotope analysis. Using negative ions in the injection stage provides isobar suppression in cases where the contaminating isobar does not form stable negative ions. Several experiments on laser interaction with a beam of mass-selected negative ions are presented. The objective for these studies can be divided into three subgroups: structure studies, dynamic studies, and proof-of-principle experiments for applications of negative ions. In the first group, the value for the electron affinity and the fine structure splitting of phosphorus is refined. The value of the electron affinity of tungsten is improved and the origin of the photodetachment signal below threshold is discussed. Resonant structure in the cross section and the electron affinity of cerium is treated. Finally, a predicted excited state in platinum is observed experimentally for the first time. The second group consists of the lifetime measurements of metastable excited states for tellurium, selenium and silicon. These measurements were made at the magnetic heavy ion storage ring CRYRING at Manne Siegbahn Laboratories in Stockholm. The third and last group are proof-of-principle experiments of isobar and neighboring isotope suppression by laser interaction. Suppression of up to four orders of magnitude is reached and the implementation into mass spectrometric systems are discussed.

Raziskovali smo možnost izdelave opažne plošče z lepilom na osnovi utekočinjenega lesa (UL) in melamin-urea-formaldehidnega (MUF) lepila. Ugotavljali smo sestavo lepilne mešanice, ki zadosti različnim pogojem uporabe opažnih plošč: suhi pogoji, vlažni pogoji in zunanji pogoji. Pripravili smo 5 lepilnih mešanic, kjer smo spreminjali delež MUF lepila in utekočinjenega lesa (MUF/UL): 100/0, 90/10, 80/20, 70/30 in 60/40. S temi lepilnimi mešanicami smo zlepili laboratorijske opažne plošče (500 mm x 500 mm x 27 mm) in iz njih izžagali strižne preizkušance, ki smo jih pred testiranjem pripravili glede na predvidene pogoje uporabe. Nato smo ugotavljali vpliv deleža utekočinjenega lesa v lepilni mešanici na strižno trdnost lepilnega spoja po standardu SIST-TS CEN/TS 13354:2004. Ugotovili smo, da so vse proučevane lepilne mešanice ustrezale zahtevam standarda za uporabo opažnih plošč v suhih pogojih, medtem ko so pogojem uporabe opažnih plošč v vlažnih in zunanjih pogojih ustrezale lepilne mešanice MUF100/UL0, MUF90/UL10 in MUF80/UL20. Rezultati so pokazali, da za izdelavo opažnih plošč lahko del MUF lepila nadomestimo z utekočinjenim lesom. Delež dodanega utekočinjenega lesa moramo prilagoditi glede na pogoje uporabe opažne plošče. Manufacturing of shuttering panels with adhesive, based on liquefied wood and melamine-urea-formaldehyde (MUF), was examined. We identified the structure of adhesive mixture satisfying the different usage conditions of shuttering panels: dry conditions, humid conditions and exterior conditions. We prepared 5 adhesive mixtures, with varying proportions of MUF adhesive and liquefied wood (MUF/LW): 100/0, 90/10, 80/20, 70/30, 60/40. We manufactured shuttering panels (500 mm x 500 mm x 27 mm) with these adhesive mixtures. The shear test pieces were cut and prepared according to the conditions of use. Then we tested the effect of the share of liquefied wood in adhesive mixture on the shear strength of adhesive bond according to SIST-TS-CEN/TS 13354:2004 standard. All of the examined adhesive mixtures for usage in dry conditions correspond to the standard. MUF100/LW0, MUF90/LW10 and MUF80/LW20 adhesive mixtures can just be used for humid and exterior conditions corresponding to the standard for usage of shuttering panels. The results show that we can replace a certain proportion of MUF adhesive with liquefied wood for manufacturing of shuttering panels, but we must adapt them according to the conditions of use.

Abstract This paper describes orbital attitude control experiments carried out on the ETS (Engineering Test Satellite)-VIII in June 2009. These experiments aim to develop a technical basis for the orbital control of a class of future large flexible spacecraft. Several novel robust control laws were tested, including a μ-synthesis based control law, a DVDFB (Direct Velocity and Displacement FeedBack) control law and a linearly interpolated gain scheduling law. Among them, this paper focuses on the gain scheduling law. Experimental results of this control law are presented to show its high control performance and lower computational burden compared with other control laws.

The extreme solar and SEP event of 20 January 2005 is analyzed from two perspectives. Firstly, we study features of the main phase of the flare, when the strongest emissions from microwaves up to 200 MeV gamma-rays were observed. Secondly, we relate our results to a long-standing controversy on the origin of SEPs arriving at Earth, i.e., acceleration in flares, or shocks ahead of CMEs. All emissions from microwaves up to 2.22 MeV line gamma-rays during the main flare phase originated within a compact structure located just above sunspot umbrae. A huge radio burst with a frequency maximum at 30 GHz was observed, indicating the presence of a large number of energetic electrons in strong magnetic fields. Thus, protons and electrons responsible for flare emissions during its main phase were accelerated within the magnetic field of the active region. The leading, impulsive parts of the GLE, and highest-energy gamma-rays identified with pi^0-decay emission, are similar and correspond in time. The origin of the pi^0-decay gamma-rays is argued to be the same as that of lower energy emissions. We estimate the sky-plane speed of the CME to be 2000-2600 km/s, i.e., high, but of the same order as preceding non-GLE-related CMEs from the same active region. Hence, the flare itself rather than the CME appears to determine the extreme nature of this event. We conclude that the acceleration, at least, to sub-relativistic energies, of electrons and protons, responsible for both the flare emissions and the leading spike of SEP/GLE by 07 UT, are likely to have occurred simultaneously within the flare region. We do not rule out a probable contribution from particles accelerated in the CME-driven shock for the leading GLE spike, which seemed to dominate later on. 34 pages, 14 Postscript figures. Solar Physics, accepted. A typo corrected. The original publication is available at http://www.springerlink.com