| 1. |
- Dalarsson, Mariana, et al.
(författare)
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First-order perturbation approach to transformer winding deformations
- 2013
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Ingår i: Progress In Electromagnetics Research Letters. - 1937-6480. ; 43, s. 1-14
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Tidskriftsartikel (refereegranskat)abstract
- An on-line method to detect radial mechanical deformations of power transformer winding turns is presented. First-order perturbation theory is applied to a transformer winding surrounded by the transformer tank wall and the iron core. The transformer wind- ing is modeled as thin conducting cylindrical rings (winding segments or turns) situated within a coaxial waveguide, where the outer con- ducting cylinder represents the transformer tank wall while the inner conducting cylinder represents the iron core. Antennas which radi- ate and measure microwave fields are proposed inside the transformer tank in order to identify and quantify the mechanical deformations of winding turns. The direct propagation problem is solved using conventional waveguide theory with mode-matching and cascading techniques. An optimization algorithm is then used to solve the inverse problem whereby a good agreement between the reconstructed and true deformations of the winding segments is obtained.
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| 2. |
- Hu, Xin, et al.
(författare)
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Compact dual-band rejection filter based on complementary meander line split ring resonator
- 2009
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Ingår i: Progress in Electromagnetics Research Letters. - 1937-6480. ; 8, s. 181-190
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Tidskriftsartikel (refereegranskat)abstract
- A general model for dual band rat-race couplers is presented through an odd-even mode analysis approach. The requirements for the impedances and electrical lengths of the branches are derived. To verify this model, a dual-band rat-race coupler is designed utilizing the balanced composite right/left handed transmission line. The whole structure is much more compact than the existing dual-band rat-race couplers and easy to fabricate. The simulated results are given. Return loss and port isolation of better than -30 dB are achieved at the central frequencies of both operating bands. Furthermore, the requirements of equal amplitude and balanced phase conditions are well fulfilled (within 0.5 dB and 5) over a frequency range of almost 50 and 90 MHz at the two central frequencies.
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| 3. |
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| 4. |
- Mathur, Parul, et al.
(författare)
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An Efficient Method for Computing the Interaction of Open Ended Circular Waveguide with a Layered Media
- 2018
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Ingår i: Progress In Electromagnetics Research Letters. - : E M W PUBLISHING. - 1937-6480. ; 76, s. 55-61
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Tidskriftsartikel (refereegranskat)abstract
- This article presents a new method for studying the near-field electromagnetic interaction between a dielectric filled open ended circular waveguide (OECW) and a layered dielectric structure. The proposed model is based on plane wave spectrum theory using a novel and computationally efficient two step integration method. The first integral, involving multiple singularities in the integration path, is efficiently solved using a deformed elliptical integration path which encircles the singularities of the integral. The infinite domain tail integral involving the slowly converging integrand is further solved using an efficient trigonometric transformation. The proposed OECW based method is capable of determining the unknown material properties of any layered dielectric medium, and hence finds application in nondestructive evaluation of materials.
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| 5. |
- Pang, F., et al.
(författare)
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A dual-band slotted trapezoidal inverted-F antenna for indoor WLAN communications
- 2016
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Ingår i: Progress In Electromagnetics Research Letters. - 1937-6480. ; 64, s. 57-63
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Tidskriftsartikel (refereegranskat)abstract
- This letter presents a new directional dual-band slotted trapezoidal inverted-F antenna (IFA) for indoor Wireless Local Area Network (WLAN) applications. The dual-band performance can be obtained by tuning the lengths of the inner symmetrical trapezoidal slots and the outer trapezoidal arms in a nearly independent manner. The measured results show that the proposed antenna can provide two separate impedance bandwidths (return loss better than 10 dB) around 180MHz and 750MHz for 2.4/5.1-5.8 GHz WLAN bands, respectively. Good radiation performance and roughly constant in-band antenna directivities are also observed.
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| 6. |
- Shen, Jianqi
(författare)
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Surface plasmon wave manipulated by quantum coherence of multilevel quantum dots
- 2014
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Ingår i: Progress In Electromagnetics Research Letters. - : The Electromagnetics Academy. - 1937-6480. ; 45, s. 89-98
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Tidskriftsartikel (refereegranskat)abstract
- An EIT (electromagnetically induced transparency)-based prism coupler is suggested for realizing tunable reflection spectrum via quantum coherence of phases in a multilevel system, where destructive and constructive quantum interference will occur among multilevel transition pathways that are driven by two external control fields. In this prism coupler, a semiconductor-quantum-dot (SQD) medium layer, which can exhibit EIT and relevant quantum coherent effects, bounds the prism base, and the two external control fields are used to manipulate the probe field and the excited surface plasmon wave (on the SQD layer surface). Then the surface plasmon wave modes, which are generated by the probe field incident into this multilevel SQD medium layer, can be coherently tunable through the switchable quantum interference (destructive and constructive quantum interference) among the energy levels in the SQD systems. Such switchable quantum interference can be realized if we tune the intensities (i.e., adjust a proper intensity ratio) of the two control fields that drive the SQD multilevel EIT system. New switchable photonic devices, which could find applications in photonic microcircuits as well as some areas in integrated optical circuits, could be designed based on this quantum-interference switchable surface plasmon resonance.
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| 7. |
- Sjöberg, Daniel, et al.
(författare)
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Realization of a matching region between a radome and a ground plane
- 2010
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Ingår i: Progress In Electromagnetics Research Letters. - 1937-6480. ; 17, s. 1-10
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In order to reduce the monostatic signature of the junction between a radome and the metallic structure to which it is attached, a tapered resistive sheet can be used. In this paper, we describe an easy method to realize this tapering using geometric variations on a subwavelength scale, with a significant reduction of the number of processing steps as a result.
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| 8. |
- Su, P., et al.
(författare)
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An improved CRLH wide-band filter using CSRRs with high stop band rejection
- 2012
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Ingår i: Progress in Electromagnetics Research Letters. - 1937-6480. ; 32, s. 119-127
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a filter based on Composite Right/Left Handed (CRLH) structures is presented, wide pass band is obtained due to the balanced CRLH properties. Besides, it has Complementary Split-Ring Resonator (CSRR) units etched on ground plane, which improves signal rejection in its upper stop band. The CSRRs work as a stop band filter in a band near the main pass band of the filter and bring in equivalent negative permittivity. CSRRs and CRLH units occupy the two sides of substrate respectively and have little mutual affection in the pass band, so either structure can be designed independently, without considering the effect from the other. The improvement occupy no additional space, the size is as large as the original filter. Detailed design procedure is illustrated. Good agreements among simulation and measurement results are achieved. In addition, the filter has a semi-enclosed structure and compact size, and the performance is greatly improved.
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| 9. |
- Xiaoming, Chen, 1983
(författare)
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Required number of OTA antennas in the multi-probe test system
- 2013
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Ingår i: Progress In Electromagnetics Research Letters. - 1937-6480. ; 43, s. 35-43
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Tidskriftsartikel (refereegranskat)abstract
- The number of OTA antennas of the multi-probe over- the-air (OTA) test system should be large enough for accurate OTA testing yet not too large due to the increasing cost. In this work, the required number of OTA antennas is studied using the spatial correlation function. Some key issues are discussed.
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| 10. |
- Xiaoming, Chen, 1983
(författare)
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Robust calculations of maximum ratio combining diversity gains based on stochastic measurements
- 2012
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Ingår i: Progress In Electromagnetics Research Letters. - 1937-6480. ; 31, s. 107-112
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Tidskriftsartikel (refereegranskat)abstract
- Previous work on maximum ratio combining (MRC) diversity has derived a closed-form cumulative distribution function (CDF), referred to as Lee's formula, for spatially correlated Rayleigh fading channels. It is usually believed that (due to its singularity) Lee's formula will result in large numerical error when two eigenvalues of a diversity antenna's covariance matrix are close to each other. This letter shows that the limit of Lee's formula converges to the true CDF as eigenvalues converge to each other, which implies that Lee's formula is robust in determining diversity gains of arbitrary antennas based on stochastic measurements.
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| 11. |
- Zhao, Xiaoxiao, et al.
(författare)
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Label-Free Assessment of Vericiguat Therapy on Mitochondrial Redox States in Septic Mice by Resonance Raman Spectroscopy
- 2023
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Ingår i: Progress In Electromagnetics Research Letters. - : The Electromagnetics Academy. - 1937-6480. ; 113, s. 119-124
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Tidskriftsartikel (refereegranskat)abstract
- Sepsis is a life-threatening infectious disease. Mitochondrial dysfunction is widespread in severe sepsis. The myocardium contains a large number of mitochondria, and the survival rate of sepsis decreases sharply when cardiac dysfunction is involved. Vericiguat (BAY 1021189) is a novel drug for the prevention of heart failure. In this study, we evaluated the mitochondrial function of septic mice and drug-treated mice by resonance Raman spectroscopy (RRS). RRS is a non-invasive and label-free technique that can identify molecular vibrations by their unique fingerprints, making it ideal for quantitative studies. By choosing 532 nm as the excitation wavelength, which is close to the absorption peak of cytochrome, we can greatly enhance the Raman signal of mitochondrial redox state. RRS can accurately identify the Raman characteristic peak at 750 cm−1, 1128 cm−1 and 1585 cm−1 attributed to the reduced cytochrome in septic mice. We found that the intensity of the characteristic peak was significantly decreased in septic mice, indicating an imbalance of mitochondrial redox function, while the function was improved in the drug-treated group. It proves that BAY has the potential as a novel treatment for mitochondrial dysfunction in sepsis.
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