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- IoT based data acquisition system
- Grid tie solar PV system
- IoT
- Losses in Solar PV plant
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[IEEE 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz2018) - Nagoya, Japan (2018.9.9-2018.9.14)] 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Intrinsic Losses in Dielectrics Investigated by Terahertz Spectroscopy
摘要： Low-loss dielectrics with various microstructure and, consequently, different extrinsic losses were investigated by using terahertz time-domain spectroscopy. The losses have been extrapolated and compared with those measured at microwave frequencies. The results showed that extrinsic factors have a considerably contribution in microwave domain. The intrinsic limit of dielectric loss of low absorption polycrystalline materials have been estimated by terahertz spectroscopy.
关键词： microwave frequencies,intrinsic losses,terahertz spectroscopy,extrinsic losses,dielectrics
更新于2025-09-10 09:29:36
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Preserving preclinical PET quality during intratherapeutic imaging in radionuclide therapy with Rose metal shielding reducing photon flux
摘要： Performing Positron Emission Tomography (PET) imaging intratherapeutically during ongoing radionuclide therapy, can be a promising method to follow tumor response in vivo. However, the high therapeutic activity can interfere with the PET camera performance and degrade both image quality and quantitative capabilities. As a solution, low energy photon emissions from the therapeutic radionuclide can be highly attenuated, still allowing sufficient detection of annihilation photons in coincidence. Method: Hollow Rose metal cylinders with 2‐4 mm walls were used to shield a 22Na point source and a uniform phantom filled with 18F as they were imaged on a pre‐clinical PET camera with increasing activities of 177Lu. A mouse with a subcutaneous tumor was injected with 18F‐FDG and imaged with an additional 120 MBq of 177Lu and repeated with shields surrounding the animal. Results: The addition of 177Lu to the volume imaged continuously degraded the image quality with increasing activity. The image quality was improved when shielding was introduced. The shields showed a high ability to produce stable and reproducible results of both spatial resolution and activity quantification up to 120 MBq of 177Lu activity (maximum activity tested). Conclusion: Without shielding, the activity quantification will be inaccurate at time points where therapeutic activities are high. The suggested method shows that the shields reduce the noise induced by the 177Lu and therefore enables longitudinal quantitative intratherapeutic imaging studies.
关键词： small animal imaging,shielding,count losses,radionuclide therapy,PET
更新于2025-09-10 09:29:36
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Recent Development in Ferrite Material for High Power Application [Passive Components]
摘要： There is no doubt that power electronics is playing a critical role in the evolution of the overall infrastructure of energy supply, from motion control and drives to industry automation and traction techniques. However, unlike decades of impressive developments in semiconductor technologies, the developments in the passive components arena, especially in magnetic components, have been rather slow and have been seen as a power system bottleneck in terms of efficiency and miniaturization. To fully tap the benefits of next-generation semiconductors, namely, silicon carbide (SiC) and gallium nitride power devices, the next-generation passive components, particularly magnetic components, must be compatible with these emerging devices, especially at high frequencies and under high pulse excitation. In essence, high saturation and low-power losses under pulse excitation and relatively high temperatures are required. Current power converters using MnZn-ferrite magnetic materials possess saturation induction (Bs) levels around 530 mT at room temperature that decrease down to 430 mT at 100 °C. It is to be noted that the Bs is measured according to the IEC standard for polycrystalline ferrite under room temperature, at a field strength of 1194 A/m and 10 kHz, which is far beyond the application range. The applicable field strength varies between 100 and 200 A/m depending on the industry (aerospace, industry, and consumer electronics). Accordingly, the power losses of these materials at 1 MHz and 50 mT vary from around 350 mW/cc at room temperature to approximately 1 W/cc at 100 °C. The measuring condition is still under the sinusoidal mode.
关键词： MnZn-ferrite,power losses,ferrite material,saturation induction,high power application
更新于2025-09-10 09:29:36
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[IEEE 2018 IEEE 38th International Conference on Electronics and Nanotechnology (ELNANO) - Kiev (2018.4.24-2018.4.26)] 2018 IEEE 38th International Conference on Electronics and Nanotechnology (ELNANO) - Harmonic Balance Method and Effective Magnetization Curves in Finite Element Analysis of Eddy-Current Losses
摘要： A nonlinear model of the magnetic field in a conductive ferromagnetic medium is presented. The model based on the simultaneous use of the harmonic balance method and the finite element method. The case of a magnetic field excitation by an alternating current source is considered. The values of eddy current losses are compared, determined using the presented method as well as by applying the monoharmonic approach using the normal magnetization curve and the curves obtained from it, by means of two energy methods.
关键词： finite element method,ferromagnetic,conductive medium,eddy current losses,harmonic balance method
更新于2025-09-10 09:29:36
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Two-channel method for measuring losses in a ring optical resonator at a wavelength of 632.8 nm
摘要： A two-channel method is proposed for measuring losses in an optical ring resonator (RR), in which eigenmodes (counter-propagating waves) are excited by means of a Zeeman ring He – Ne laser with a wavelength of 632.8 nm. The measured frequency splitting of the laser counterpropgating waves is used to determine the absolute value of losses in an exemplary RR. The value of losses in the measured RR is determined by comparing the resonance width of the output radiation intensity with the resonance width of the radiation intensity for an exemplary resonator. The algorithm of intensity resonance processing takes into account the distortions caused by the dynamic effect, which allows a significant increase in the accuracy (up to 1 % – 2 %) and sensitivity of the proposed method. The measured losses in the RR with a perimeter of 28 cm constitute 80 – 5000 ppm.
关键词： ring optical resonator,eigenmode losses in the RR,radiation intensity resonances at the RR output,laser gyroscope,ring He – Ne laser with a wavelength of 632.8 nm
更新于2025-09-10 09:29:36
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[IEEE 2018 International Power Electronics Conference (IPEC-Niigata 2018 –ECCE Asia) - Niigata, Japan (2018.5.20-2018.5.24)] 2018 International Power Electronics Conference (IPEC-Niigata 2018 -ECCE Asia) - Optimized Bidirectional PFC Rectifiers & Inverters - Si vs. SiC vs. GaN in 2L and 3L Topologies -
摘要： In industrial drive systems, PFC converters are widely used. For PFC converters, a lot of different configurations and topologies exist and it is difficult to choose one. Therefore, in this paper, a comprehensive survey of possible configurations are optimized and compared against each other. The analysis shows the important aspects of the converter design and how the used semiconductor technology (Si, SiC and GaN) affects the total converter volume. A sensitivity analysis of certain power semiconductor parameters is performed to highlight the benefit of possible future developments of components and materials. In addition, the differences between the rectifier stage, where an EMI filter stage is necessary and the inverter stage, where the harmonic motor losses are influenced by the modulation scheme, are presented.
关键词： semiconductor technology,EMI filter,PFC converters,harmonic motor losses,modulation scheme
更新于2025-09-10 09:29:36
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On the Origin of the Coss-Losses in Soft-Switching GaN-on-Si Power HEMTs
摘要： The unprecedented performance potential of Gallium-Nitride-on-Silicon (GaN-on-Si) High Electron Mobility Transistors (HEMTs) is seen as the key enabler for the design of power converters featuring extreme power-density figures, as demanded in next generation power electronics applications. However, unexpected loss mechanisms, i.e. dynamic Rds,on phenomena and Coss-losses, are appearing in currently available GaN transistors and are compromising their operation. In this paper, measurements of Coss-losses are performed in a dedicated calorimetric measurement setup and, through a systematic approach, the root cause of the loss mechanism is potentially identified. Afterwards, with the essential support of a manufacturer of power semiconductors, a novel transistor, featuring an enhanced multi-layer III-N buffer, is developed according to the acquired knowledge. A significant reduction in terms of Coss-losses, i.e. of soft-switching losses, and the absence of dynamic Rds,on phenomena are verified experimentally on the new device. These achievements enable a significant performance improvement for future soft-switching power converters featuring GaN-on-Si HEMTs.
关键词： Soft-Switching Losses,Calorimetric Loss Measurements,Coss-Losses,GaN-on-Si HEMTs
更新于2025-09-09 09:28:46
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Two-dimensional vortex quantum droplets
摘要： It was recently found that the Lee-Huang-Yang (LHY) correction to the mean-field Hamiltonian of binary atomic boson condensates suppresses the collapse and creates stable localized modes (two-component quantum droplets, QDs) in two and three dimensions (2D and 3D). In particular, the LHY effect modifies the effective Gross-Pitaevskii equation (GPE) in 2D by adding a logarithmic factor to the usual cubic term. In the framework of the accordingly modified two-component GPE system, we construct 2D self-trapped modes in the form of QDs with vorticity S embedded into each component. Because of the effect of the logarithmic factor, the QDs feature a flat-top shape, which expands with the increase of S and norm N. An essential finding, produced by a systematic numerical investigation and analytical estimates, is that the vortical QDs are stable (which is a critical issue for vortex solitons in nonlinear models) up to S = 5, for N exceeding a certain threshold value, which is predicted to scale as Nth ～ S4 for large S (for three-dimensional QDs, the scaling is Nth ～ S6). The prediction is corroborated by numerical findings. Pivots of QDs with S (cid:2) 2 are subject to structural instability, as specially selected perturbations can split the single pivot in a set of S or S + 2 pivots corresponding to unitary vortices; however, the structural instability remains virtually invisible, as it occurs in a broad central "hole" of the vortex soliton, where values of fields are very small, and it does not cause any dynamical instability. In the condensate of 39K atoms, in which QDs with S = 0 and a quasi-2D shape were created recently, the vortical droplets may have radial size (cid:2)30 μm, with the number of atoms in the range of 104–105. The role of three-body losses is considered too, demonstrating that they do not prevent the creation of the vortex droplets but may produce a noteworthy effect, leading to sudden splitting of "light" droplets. In addition, hidden-vorticity (HV) states in QDs, with topological charges S+ = ?S? = 1 in their components, which are prone to strong instability in other settings, have their stability region too. Unstable HV states tend to spontaneously merge into zero-vorticity solitons. Collisions of QDs, which may lead to their merger, and dynamics of elliptically deformed QDs (which form rotating elongated patterns or ones with oscillations of the eccentricity) are briefly considered too.
关键词： hidden-vorticity states,Gross-Pitaevskii equation,Lee-Huang-Yang correction,quantum droplets,vorticity,three-body losses,stability
更新于2025-09-09 09:28:46
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AIP Conference Proceedings [Author(s) SolarPACES 2017: International Conference on Concentrating Solar Power and Chemical Energy Systems - Santiago, Chile (26–29 September 2017)] - Cavity losses estimation in CSP applications
摘要： Estimations of convection and radiation cavity losses in two common CSP applications have been analyzed; a cavity in a solar tower plant for high temperature (800 K) and in a down facing cavity in a Fresnel configuration for medium temperature (350 K) applications. An analysis regarding the effect of the configuration, geometry and the presence of wind has been also carried out.
关键词： solar tower plant,Fresnel configuration,convection,radiation,cavity losses,CSP applications
更新于2025-09-09 09:28:46
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POWER DIVIDER BASED ON STEPPED-IMPEDANCE SLOTLINE
摘要： A novel 180? out-of-phase power divider based on stepped-impedance slotline is presented in this article. This power divider employs one T-junction formed by microstrip line and slotline to obtain two out-of-phase dividing signals. Stepped-impedance slotline and lumped resistor are introduced to improve the isolation between output ports. The experimental data show that the proposed power divider has good performance on insertion loss, return losses, isolation, phase balance, as well as group delay over the wide band 5 GHz–10 GHz.
关键词： slotline,isolation,group delay,microstrip line,insertion loss,power divider,phase balance,stepped-impedance slotline,return losses
更新于2025-09-09 09:28:46