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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Diffusion-Free Organic Hole Selective Contacts for Silicon Solar Cells
摘要： A novel one-port probe technique, which combines the measurements of a rectangular waveguide and coaxial probe to nondestructively yield the permittivity and permeability of a PEC-backed material, is presented. A brief description of the derivation of the theoretical probe reflection coefficients, necessary for permittivity and permeability extraction via numerical inversion, is provided. Experimental characterization results of a PEC-backed magnetic material are presented to validate the proposed approach. Error analysis is also undertaken to quantify the new technique’s sensitivity to common experimental errors.
关键词： Integral equations,measurement uncertainty,uncertainty,moment methods,permeability measurement,permittivity measurement,waveguides,microwave measurements
更新于2025-09-19 17:13:59
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A MCRT-FVM-FEM coupled simulation for optical-thermal-structural analysis of parabolic trough solar collectors
摘要： Based on drilling, logging, test production and dynamic monitoring data, the control effects of low-amplitude structure on hydrocarbon accumulation and development performance of ultra-low permeability reservoirs were discussed by using the methods of dense well pattern, multi-factor geological modeling, macro and micro analysis and static and dynamic analysis. The results show that the low-amplitude structure always had a significant control and influence on the distribution and accumulation of original hydrocarbon and water and the evolution trend of water flooding performance in ultra-low permeability reservoirs, and it was not only the direction of oil and gas migration, but also a favorable place for relative accumulation of oil and gas. The controlling effect of low-amplitude structure on ultra-low permeability reservoir mainly depended on its tectonic amplitude and scale; the larger the tectonic amplitude and scale, and the higher the tectonic position of the low amplitude structure, the better the reservoir characteristic parameters, oil and gas enrichment degree and development effect, and the larger the spatial scope it controlled and influenced; water cut and oil well output always fluctuated orderly with the height of the low-amplitude structure; the dynamic response of waterflooding was closely related to the relative structural position of the injection and production wells; the injected water always advanced to the low-lying area of the structure first and then moved up to the high-lying area of the structure gradually; with the continuous expansion of the flooded area, part of the oil and gas in the low-lying part of the structure was forced to be distributed to the high part of the structure, resulting in a new oil and gas enrichment, so that the dynamic reserves of oil wells in the high part increased, and the production capacity remained stable.
关键词： ultra-low permeability reservoirs,control effect,development dynamics,low-amplitude structure,oil-gas-water enrichment
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Temperature Dependence of Magnetic Permeability and Optical Polarization Rotation of Gallium-Terbium Garnet Crystals
摘要： Faraday isolators (IF) are widely used in high-power fiber lasers in order to eliminate the detrimental influence of back reflections during the laser operation. One of the most widespread materials used for IF is a gallium-terbium garnet (TGG) crystal due to its appropriate magneto-optical properties. However, heating of magneto-optical crystals due to absorption of laser radiation deteriorates IF properties. Non-uniform heating leads to mechanical stresses and, therefore, to non-uniform polarization distortions. Values of optical absorption coefficients of TGG greatly depend on a crystal growth technology. Determination of the temperature dependence of optical absorption of TGG crystal was also one of the goals of this research. Optical absorption coefficient of cylindrical TGG sample (diameter d = 0.4 cm, length l = 2 cm) at 1060 nm wavelength was measured using laser calorimetry, i.e. by measuring the temperature of the crystal heated by transmitting laser radiation. Dependence of the crystal heating on transmitted optical power was 1.1±0.1 K/W. Absorption coefficient was calculated by solving the heat balance equation. Its value has increased from 1.6*10-3 cm-1 to 1.9*10-3 cm-1 as a result of heating from 22 oC to 43 oC. Also the contribution of the temperature dependent magnetic permeability μ(T) of TGG on the polarization rotation angle β was experimentally estimated. Temperature dependence of the magnetic permeability of TGG crystal was experimentally measured using resonant impedance spectroscopy. The value of TGG magnetic permeability was about 1.008 at room temperature (20 oC) and has decreased by Δμ = ? 1.2*10-4 when the crystal was heated to 80 oC. The temperature dependences of the polarization axis rotation angle change Δβ were measured in the cases of the uniform heating of TGG sample in a furnace and its nonuniform heating by transmitting linearly polarized laser radiation up to 30 W of optical power (1064 nm wavelength, 2 mm beam diameter). Applied magnetic field strength was 0,4 T, full angle of polarization axis rotation – 17,5 deg. Taking into account the measurement errors Δβ(T) ? (5 ± 0.25)*10-2 deg/ oC for both cases. It should be noticed that narrower laser beams can lead to greater differences due to the presence of larger temperature gradients. Consideration of the measurement results of μ(T) and β(T) revealed that the contribution of magnetic permeability variation with temperature to an overall polarization rotation angle change is almost 90 times lower than the thermally induced change of Verdet constant. Nevertheless, μ(T) influence should be considered if a precise control of polarization axis angle is required.
关键词： gallium-terbium garnet,Faraday isolators,TGG,magnetic permeability,temperature dependence,optical polarization rotation
更新于2025-09-11 14:15:04
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Light and flexible composite nanofibrous membranes for high-efficiency electromagnetic absorption in a broad frequency
摘要： With the fast advancement of up-to-date communication technologies, electromagnetic wave (EMW) absorption materials are widely required for various applications. However, it is still a big challenge to produce lightweight, flexible and high efficiency EMW absorption materials in a broad-ranging frequency. Herein, we designed to fabricate the magnetic and dielectric nanofibrous membranes which can be effectively used as EMW absorption materials by facile electrospinning process. The as-fabricated composite carbon nanofibers (CNFs), which combined the components of nickel, cobalt antioxidant nanoparticles and carbon nanotubes, exhibited outstanding magnetic, dielectric properties and strong absorption ability in a wide frequency range. These nanoparticles encapsulated in CNFs are extremely beneficial to the electrical conductivity of the composites through decreasing the contact loss within the CNFs by formation the metal-metal interfaces. Correspondingly, the RL value of -46.60 dB was reached at 4.88 GHz frequency range with a layer thickness of 5.5 mm for these mechanically light and flexible membranes. The enhanced absorption performance (<?10 dB) in the wide frequency band (4.16-18 GHz) can be achieved by selecting a suitable thickness of the material. Results demonstrate that the permittivity and permeability of developed samples have been largely improved due to the integrated interaction of all introduced components in the structure. The composite membranes are a promising candidate for scalable, lightweight and high performance EMW absorption materials in the frequency range from C band to Ku band (4?18 GHz).
关键词： Magnetic and dielectric properties,permeability,permittivity,carbon nanotubes,electromagnetic wave absorption
更新于2025-09-10 09:29:36
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[IEEE 2017 IEEE HISTory of ELectrotechnolgy CONference (HISTELCON) - Kobe, Japan (2017.8.7-2017.8.8)] 2017 IEEE HISTory of ELectrotechnolgy CONference (HISTELCON) - Development of Ferrite Materials and Their Applications
摘要： Dr. Takeshi Takei, a professor at Tokyo Institute of Technology, discovered that oxides containing zinc and iron have distinguished magnetic properties, while he carried out the search for ways to raise the yield of zinc in the refining through hydrometallurgy, under the guidance of Prof. Yogoro Kato. This breakthrough led Takei to examine the chemical compositions of a variety of other divalent metal combinations. At the same time, efforts to sinter powder-compacted ferrite under a host of conditions resulted in a magnetic material with superior magnetic permeability and suppression of core-loss, making it suitable for practical high-frequency applications for inductor cores. In 1930 he published scientific paper for Mining Society of Japan, continually gave a presentation at annual meeting of American Electrochemical Society in St. Louis USA. In the same year, a patent application for this material, naming Yogoro Kato and Takeshi Takei as co-inventors, was applied in Japan, and granted in 1932. Following the patent application in 1930, researchers led by Teiichi Yamazaki, who would later become the second president of TDK continued to develop materials with high magnetic permeability and low loss properties by combining divalent metal oxide compounds. In February 1936, Yamazaki developed a ferrite with high magnetic permeability and low-loss properties suitable for practical applications by optimizing the chemical compositions and processing conditions for Cu-Zn ferrite. Tokyo Denki Kagaku Kogyo (now TDK Corporation) was founded in 1935 to commercialize this newly invented ferrite cores as a venture company originated from the university patent of ferrite. TDK started mass production of ferrite cores in 1937. Most of the shipped products were used in the local oscillators, mixers, and intermediate frequency transformers of military radios. These are the world first usage of ferrite to radio communication equipment. Ferrite largely contributed to reduce volume and weight of radio receiver compared with air coil. Until the end of the World War II, TDK was the only company in the world who could supply ferrite cores. TDK shipped a cumulative total of nearly 5 million pieces of ferrite cores by 1945. The electric and electronics industries use ferrites in numerous applications today. Nowadays, numerous numbers of ferrites are used not only for the radio communication equipment, but also for various kinds of devices, such as magnetic core of power converters, noise suppression devices, spintronics devices and medical applications. The development of Ferrite materials and their Applications, 1930-1945, was awarded as an IEEE Milestone on 13th of October 2009, IEEE Milestone in Electrical Engineering and Computing, 2009. Ferrite will be used more for mobile communication tools and automobile applications.
关键词： Ferrite,Magnetic core,IEEE Milestone,magnetic permeability
更新于2025-09-10 09:29:36
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Persistence of Electromagnetic Units in Magnetism
摘要： The centimeter-gram-second system of electromagnetic units (EMU) has been used in magnetism since the late 19th century. The International System of Units (SI), a successor to Giorgi’s 1901 meter-kilogram-second system, was adopted by the General Conference on Weights and Measures in 1960. However, EMU remains in common use for the expression of magnetic data. The forthcoming revision of the SI provides an excellent reason for magnetics researchers to abandon the use of EMU.
关键词： electromagnetic units,permeability of vacuum,International System of Units
更新于2025-09-10 09:29:36
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Hybrid Nanostructures for Cancer Theranostics || Nanostructures for Externally Triggered Chemo/Thermal Therapies
摘要： Cancer is the most common cause of death globally despite improvement in early detection, life-style changes, and advances in radiotherapy, immunotherapy, chemotherapy, and molecular medicine. The American Cancer Society estimated 1,688,780 cases of cancer and 600,920 deaths in the USA in 2017 alone. Problems with current therapies include: invasive procedures, systemic side effects from the nonspecific nature of chemotherapy drugs, and drug-resistant tumors. In addition to limited efficacy, the side effects of current treatments include anemia, bleeding or clotting, loss of bone density, bowel dysfunction, fatigue, hair loss, damage to the heart, immune suppression, infertility, lung dysfunction, lymphedema, mental deficits, nausea, pain, sexual dysfunction, skin changes, weight loss or gain, and urinary and bladder problems. Radiation and chemotherapies comprise the bulk of cancer treatment methods in current practice, and the off-target effects are primarily due to the nonspecific toxicity of these methods. Obviously, limiting nonspecific toxicity will improve patients’ quality of life, while not affecting tumor directed dose—this provides the motivation to pursue tumor-targeted nanomedicine. Further, many current therapy methods do not adequately address the individual patient differences resulting from inter and intra-tumor heterogeneity. Ideal disease treatment would noninvasively deliver therapy to only the target, limiting side effects due to the nonspecific drug action, and expose the tumor to a sufficient amount of drug, or other therapy such as heat or radiation. Multifunctional nanoparticles (NPs), which aid in the diagnosis (generally by acting as a contrast agent for traditional diagnostic imaging modalities), possibly targeted to the specific molecular phenotype of tumors, and which also deliver therapy (nanotheranostics) offer benefits not possible with other therapies. Only about 1% of current therapeutic agents deposit in tumors; thus, the vast majority of injected drugs are either excreted or end up in undesired tissues. In addition to not effectively treating the disease, exposing the tumors to such low concentrations of chemotherapeutic agents also artificially selects for cells that can tolerate the drug, leading to resistance. Incorporating drugs into nanoconstructs that can be noninvasively tracked for delivery to the tumor and activated at the disease site, offers a potential solution to both the drug-delivery and toxicity/efficacy problems of current chemotherapies. Besides drug delivery, NPs can also be designed and used to thermally ablate the tumor using energy from an external source, thereby avoiding invasive surgical procedures. The subcellular size (in the tens to hundreds of nanometers, similar in size to organelles) of NPs makes them exceptionally well suited for use in drug delivery and/or as absorbers for certain wavelengths of light. They can circulate for a relatively long period because they avoid rapid filtration by the spleen and can pass through Kupffer cell sieve plates. A long circulation time gives them a greater percentage of injected dose accumulating in the desired location. Tumors generally exhibit a more porous vasculature and poorer lymphatic circulation than normal tissue, allowing more and larger particles to cross over between the blood vessels and intercellular space and build up there. This is called enhanced permeability and retention (EPR), and can cause NPs to build up in the tumor, provided they can circulate long enough.
关键词： Drug delivery,Cancer,Thermal ablation,Enhanced permeability and retention (EPR),Externally triggered NPs,Nanotheranostics,Nanomedicine
更新于2025-09-10 09:29:36
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[IEEE 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - Odessa, Ukraine (2018.9.4-2018.9.7)] 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - The Application of Pulsed Electric Fields and Other Types of Electromagnetic Radiation in Therapy of Cancer
摘要： since the beginning of 21-th century the investigations in the area of cancer therapy by electric fields become more numerous. These investigations may be divided in three groups: studies carried out on cell cultures, studies on animal models and case reports describing applications of pulsed electric fields for treatment of cancer patients. Very important is to chose adequate methods of measuring the cell damage and speaking more generally – cell response to stress. In Kharkov University various investigations in the area of cell response to electromagnetic influences were carried out and some new methods were proposed. In this paper the analysis of recent works in this area is done and perspectives of the research are discussed.
关键词： electromagnetic pulse,cell proliferation,cell membrane permeability,cell response to electromagnetic stress,apoptosis,cancer therapy,necrosis
更新于2025-09-09 09:28:46
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Structure and Permeability of Porous Silicon Investigated by Self-Diffusion NMR Measurements of Ethanol and Heptane
摘要： The adsorption and phase transitions of con?ned ?uids in nanoporous materials have been studied intensely because of both their fundamental interest and their crucial role in many technologies. Questions relating to the in?uence of the con?nement of ?uids, and the disorder or elastic deformation of porous solids on the liquid-gas phase transition are still under debate. Model systems are needed to understand the adsorption phenomenon. In this context, Porous Silicon (PoSi), which is a single crystal obtained by etching a (100) silicon wafer is an excellent candidate. Indeed, it consists of non-connected tubular pores running parallel to the [100] axis perpendicular to the wafer surface, with transverse sections with a polygonal shape of nanometric size whose areas are widely distributed. Once detached from the wafer, free PoSi membranes can be considered a nanoscale disordered honeycomb. Adsorption/desorption experiments have been performed to characterize the structure: they have shown that evaporation occurs collectively, an intriguing observation generally associated with a disordered pore structure with many interconnections through narrow necks. The characterization of ?uid mobility inside the pores should give complementary information about the pore structure and topology. This paper focuses on the dynamics of a ?uid con?ned inside the structure of porous silicon, and in particular the self-diffusion measurements (pulsed ?eld gradient spin echo Nuclear Magnetic Resonance (NMR)). The results show a strong anisotropy of the self-diffusion tensor, as expected in this highly anisotropic structure. However, a non-zero self-diffusion in the directions perpendicular to the pore axis is observed. In order to interpret these puzzling results, molecular and Brownian dynamics calculations are underway.
关键词： Ethanol,Porous Silicon,Permeability,Heptane,Self-Diffusion NMR
更新于2025-09-09 09:28:46
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Free-Space Materials Characterization by Reflection and Transmission Measurements using Frequency-by-Frequency and Multi-Frequency Algorithms
摘要： The knowledge of the electromagnetic constitutive properties of materials is crucial in many applications. Free-space methods are widely used for this purpose, despite their inherent practical difficulties. This paper describes an affordable free-space experimental setup for the characterization of flat samples in 1–6 GHz in a non-anechoic environment. The extracted properties are obtained from the calibrated Scattering Parameters, using a frequency-by-frequency solution or a multi-frequency reconstruction. For the first, we describe how the Time-Domain Gating can be implemented and used for filtering the signals. For the latter, a weighting factor is introduced to balance the reflection and transmission data, allowing one to have a more favorable configuration. The different role of transmission and reflection measurements on the achievable results is analyzed with regard to experimental uncertainties and different noise scenarios. Results from the two strategies are analyzed and compared. Good agreement between simulation, measurement and literature is obtained. According to the reported results for dielectric materials, there is no need of filtering the data by a Time-Domain Gating in case of the multi-frequency approach. Experimental results for Polymethylmethacrylate (PMMA) and Polytetrafluorethylene (PTFE) samples validate both the setup and the processing.
关键词： free-space method,permeability,conductivity,non-destructive testing,extraction algorithms,permittivity,time-domain gating,free-space calibration,scattering parameters,material characterization
更新于2025-09-09 09:28:46