| 29101. |
- Khanal, Siraj, et al.
(författare)
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Optimal capacity of solar photovoltaic and battery storage for grid-tied houses based on energy sharing
- 2023
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Ingår i: IET Generation, Transmission and Distribution. - 1751-8687 .- 1751-8695. ; 17:8, s. 1707-1722
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Tidskriftsartikel (refereegranskat)abstract
- This paper determines the optimal capacity of solar photovoltaic (PV) and battery energy storage (BES) for a grid-connected house based on an energy-sharing mechanism. The grid-connected house, also mentioned as house 1 where it is relevant, shares electricity with house 2 under a mutually agreed fixed energy price. The objective is to minimize the cost of electricity (COE) for house 1 while decreasing the electricity cost of house 2. Practical factors such as real data for solar insolation, electricity consumption, grid constraint, ambient temperature, electricity rate, and battery degradation are considered based on actual data. The developed methodology is examined by taking the actual load data of two houses in South Australia. Different scenarios of contract years between the houses are investigated to make it more practical in real life. Sensitivity analyses are conducted for the sharing of energy between the houses and by changing parameters like export power limitation, load of houses, and costs of PV and BES. Likewise, operational analysis is done for two days of summer and winter. It is found that when energy sharing is applied, the optimal design of the PV-BES system will achieve lower COE for both houses.
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| 29102. |
- Khanal, Siraj, et al.
(författare)
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Stationary BES Coupled with Solar PV for an Energy Shared Home with an EV
- 2023
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Ingår i: 2023 IEEE International Conference on Energy Technologies for Future Grids, ETFG 2023.
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Konferensbidrag (refereegranskat)abstract
- This study examines the optimal combination of stationary battery energy storage (SBES) and solar photovoltaic (SPV) components for grid-tied homes with electric vehicle (EV) when electricity is shared with a neighbor. In this paper, Load-1 refers to the home with SPV-SBES and EV that shares electricity with Load-2. The optimization is performed to obtain the lowest possible cost of electricity (COE) for Load-1 and to reduce the COE for Load-2 over the project lifespan, considering the design constraints. Utilizing realistic yearly data of the solar irradiance, temperature, load consumption of each dwelling, and EV, the capacity of SPV and SBES is determined to achieve optimal results. The time of departure, the time of arrival, and the initial state of charge at the time of arrival are all subject to EV uncertainty. The devised optimization method is applicable to all grid-connected homes that are willing to share their electricity with a neighbor. The configuration is subjected to sensitivity, uncertainty, and operational analysis when energy is shared between households and L1 has SPV, SBES, and EV.
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| 29103. |
- Khanal, S, et al.
(författare)
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Thermal Characterization of THz Schottky Diodes Using Transient Current Measurements
- 2014
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Ingår i: IEEE Transactions on Terahertz Science and Technology. - 2156-342X .- 2156-3446. ; 4:2, s. 267-276
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a new method for thermal characterization of THz Schottky diodes. The method is based on the transient current behavior, and it enables the extraction of thermal resistances, thermal time-constants, and peak junction temperatures of THz Schottky diodes. Many typical challenges in thermal characterization of small-area diode devices, particularly those related to self-heating and electrical transients, are either avoided or mitigated. The method is validated with measurements of commercially available single-anode Schottky varactor diodes. A verification routine is performed to ensure the accuracy of the measurement setup, and the characterization results are compared against an in-house measurement-based method and against simulation results of two commercial 3-D thermal simulators. For example, characterization result for the total thermal resistance of a Schottky diode with an anode area of 9 $muhbox{m}^{2}$ is within 10% of the average value of 4020 K/W when using all four approaches. The new method can be used to measure small diode devices with thermal time constants down to about 300 ns with the measurement setup described in the paper.
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| 29104. |
- Khandelwal, Akanksha, et al.
(författare)
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Discovery of an inflated hot Jupiter around a slightly evolved star TOI-1789
- 2022
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Ingår i: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 509:3, s. 3339-3354
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Tidskriftsartikel (refereegranskat)abstract
- We report here the discovery of a hot Jupiter at an orbital period of 3.208664 ± 0.000015 d around TOI-1789 (TYC 1962-00303-1, TESSmag = 9.1) based on the TESS photometry, ground-based photometry, and high-precision radial velocity (RV) observations. The high-precision RV observations were obtained from the high-resolution spectrographs, PARAS at Physical Research Laboratory (PRL), India, and TCES at Thüringer Landessternwarte Tautenburg (TLS), Germany, and the ground-based transit observations were obtained using the 0.43-m telescope at PRL with the Bessel-R filter. The host star is a slightly evolved (log g∗ = 3.943+0.023-0.043), late F-type (Teff= 5991 ± 55 K), metal-rich star ([Fe/H] = 0.373+0.071-0.086 dex) with a radius of R ∗ = 2.168+0.036}-0.034 R located at a distance of 223.53+0.91-0.90} pc. The simultaneous fitting of the multiple light curves and the RV data of TOI-1789 reveals that TOI-1789 b has a mass of MP = 0.70 ± 0.16 MJ, a radius of RP = 1.44+0.24-0.14, RJ, and a bulk density of ρP = 0.28+0.14-0.12 g cm-3 with an orbital separation of a = 0.04882+0.00063-0.0016 au. This puts TOI-1789 b in the category of inflated hot Jupiters. It is one of the few nearby evolved stars with a close-in planet. The detection of such systems will contribute to our understanding of mechanisms responsible for inflation in hot Jupiters and also provide an opportunity to understand the evolution of planets around stars leaving the main-sequence branch.
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| 29105. |
- Khanmirza, H., et al.
(författare)
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Evaluating passive neighborhood discovery for Low Power Listening MAC protocols
- 2014
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Ingår i: International Conference on Wireless and Mobile Computing, Networking and Communications. - 2161-9654 .- 2161-9646. - 9781479950416 ; , s. 173-180
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Konferensbidrag (refereegranskat)abstract
- Low Power Listening (LPL) MAC protocols are widely used in today's sensors networks for duty cycling. Their simplicity and power efficiency ensures a long network life when nodes are battery driven and their easy deployment and lower cost of maintenance makes them suitable to be used in hard-to-access places and harsh conditions. We argue that to fully utilize energy efficiency provided by LPL, other protocols in the protocol stack should be aware of mechanisms. In this paper, we focus on neighborhood discovery protocols and discuss their energy efficient integration with LPL. Then, we study the possibility of using a completely passive approach for neighborhood discovery in such networks and provide an analytical model for its performance characteristics. We verify our performance model both by simulation and implementation in TinyOS. Our evaluation results confirm the efficiency of our proposed method in duty-cycled sensor networks.
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| 29106. |
- Khanzadeh, Babak, et al.
(författare)
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Multilevel Dual Active Bridge Leakage Inductance Selection for Various DC-Link Voltage Spans
- 2023
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Ingår i: Energies. - : MDPI. - 1996-1073. ; 16:2
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Tidskriftsartikel (refereegranskat)abstract
- The leakage inductance of the transformer in a dual active bridge (DAB) dc–dc converter directly impacts the ac current waveforms and the power factor; thus, it can be considered a design requirement for the transformer. In the existing literature, a choice is made to either ensure soft switching in nominal power or to minimize the RMS current of the transformer. The inductance is typically obtained using optimization procedures. Implementing these optimizations is time-consuming, which can be avoided if a closed-form equation is derived for the optimum leakage inductance. In this paper, analytical formulas are derived to estimate the desired leakage inductance such that the highest RMS value of the current in the operation region of a DAB is kept to its minimum value. The accuracy and sensitivity of the analytical solutions are evaluated. It is shown that in a large design domain, the solution for the YY-connected MFT has a less than 3% error compared to the results obtained from an optimization engine. As an example of the importance of selecting the leakage inductance correctly, it is shown that for 11% deviations in the dc link voltages, a 10% deviation from the desired leakage inductance value can cause 2% higher RMS currents in the converter. © 2023 by the authors.
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| 29107. |
- Khanzadi, M Reza, 1983, et al.
(författare)
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A model-based analysis of phase jitter in RF oscillators
- 2012
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Ingår i: 2012 IEEE International Frequency Control Symposium, IFCS 2012, Proceedings. - 9781457718199 ; , s. 508-511
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Konferensbidrag (refereegranskat)abstract
- The closed-form autocorrelation function of the phase jitter accumulation process in presence of 1/f 3 and 1/f 2 shape noises is derived from the single-sideband (SSB) phase noise (PN) measurements. Exploiting the calculated autocorrelation function, a lower bound for the minimum achievable mean square error (MSE) of the PN prediction in a typical single-input singleoutput communication system is computed. This bound links the performance of a communication system suffering from the PN directly to the SSB PN measurements.
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| 29108. |
- Khanzadi, M Reza, 1983, et al.
(författare)
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A Novel Cognitive Modulation Method Considering the Performance of Primary User
- 2010
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Ingår i: Wireless Advanced (WiAD), 2010 6th Conference on. - 9781424470693 ; , s. 1 - 6
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Konferensbidrag (refereegranskat)abstract
- This paper proposes a new modulation method foran uncoded cognitive transmission (secondary user transmission)in presence of a Primary User (PU) for the AWGN channel.Interference of the PU is assumed to be known at the transmitterof Cognitive User (CU) non-causally. Based on this knowledge,for the design of the modulator and demodulator of the CU,a symbol by symbol approach is studied which can fulfill thecoexistence conditions of the CU and the PU of the band. In thisscheme, the modulator and demodulator of CU are designedjointly by solving an optimization problem to mitigate theinterference of the PU and minimize the symbol error probability(Pe) in CU’s communication link without increasing the symbolerror probability (Pe) of the PU. The proposed method is amodulation approach in a single (complex-valued) dimensionrather than a high dimensional coding scheme. Although thisone-dimensional method is not capacity achieving, we show it stillhas a remarkable performance with low amount of complexity.An implementation algorithm for our modulation method is alsopresented and the performance of this method is evaluated byexperimental results.
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| 29109. |
- Khanzadi, M Reza, 1983, et al.
(författare)
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Calculation of the Performance of Communication Systems from Measured Oscillator Phase Noise
- 2014
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Ingår i: IEEE Transactions on Circuits and Systems I: Regular Papers. - 1549-8328 .- 1558-0806. ; 61:5, s. 1553-1565
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Tidskriftsartikel (refereegranskat)abstract
- Oscillator phase noise (PN) is one of the major problems that affect the performance of communication systems. In this paper, a direct connection between oscillator measurements, in terms of measured single-side band PN spectrum, and the optimal communication system performance, in terms of the resulting error vector magnitude (EVM) due to PN, is mathematically derived and analyzed. First, a statistical model of the PN, considering the effect of white and colored noise sources, is derived. Then, we utilize this model to derive the modified Bayesian Cramer-Rao bound on PN estimation, and use it to find an EVM bound for the system performance. Based on our analysis, it is found that the influence from different noise regions strongly depends on the communication bandwidth, i.e., the symbol rate. For high symbol rate communication systems, cumulative PN that appears near carrier is of relatively low importance compared to the white PN far from carrier. Our results also show that 1/f^3 noise is more predictable compared to 1/f^2 noise and in a fair comparison it affects the performance less.
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| 29110. |
- Khanzadi, M Reza, 1983, et al.
(författare)
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Capacity of SIMO and MISO Phase-Noise Channels with Common/Separate Oscillators
- 2015
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Ingår i: IEEE Transactions on Communications. - 0090-6778 .- 1558-0857. ; 63:9, s. 3218-3231
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Tidskriftsartikel (refereegranskat)abstract
- In multiple antenna systems, phase noise due to instabilities of the radio-frequency (RF) oscillators, acts differently depending on whether the RF circuitries connected to each antenna are driven by separate (independent) local oscillators (SLO) or by a common local oscillator (CLO). In this paper, we investigate the high-SNR capacity of single-input multiple-output (SIMO) and multiple-output single-input (MISO) phase-noise channels for both the CLO and the SLO configurations.Our results show that the first-order term in the high-SNR capacity expansion is the same for all scenarios (SIMO/MISO and SLO/CLO), and equal to 0.5ln(SNR), where SNR stands for the signal-to-noise ratio. On the contrary, the second-order term, which we refer to as phase-noise number, turns out to be scenario-dependent. For the SIMO case, the SLO configuration provides a diversity gain, resulting in a larger phase-noise number than for the CLO configuration. For the case of Wiener phase noise, a diversity gain of at least 0.5ln(M) can be achieved, where M is the number of receive antennas. For the MISO, the CLO configuration yields a higher phase-noise number than the SLO configuration. This is because with the CLO configuration one can obtain a coherent-combining gain through maximum ratio transmission (a.k.a. conjugate beamforming). This gain is unattainable with the SLO configuration.
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