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Ahead-of-time forecasting of the output power of power plants is essential for the stability of the electricity grid and ensuring uninterrupted service. However, forecasting renewable energy sources is difficult due to the chaotic behavior of natural energy sources. This paper presents a new approach to estimate short-term solar irradiance from sky images. The proposed algorithm extracts features from sky images and use learning-based techniques to estimate the solar irradiance. The performance of proposed machine learning (ML) algorithm is evaluated using two publicly available datasets of sky images. The datasets contain over 350,000 images for an interval of 16 years, from 2004 to 2020, with the corresponding global horizontal irradiance (GHI) of each image as the ground truth. Compared to the state-of-the-art computationally heavy algorithms proposed in the literature, our approach achieves competitive results with much less computational complexity for both nowcasting and forecasting up to 4 h ahead of time. more...

This article presents a new approach to determining liquid concentration using a new microwave sensor and polarity correlator. The sensor design incorporates an annular ring resonator having inside three parallel lines, a trapezoid ground plane and a co-planar waveguide (CPW) tapered feeder, which altogether achieve multiple frequency bands. Multiple bands of interest are obtained at the lower end of the microwave spectrum, i.e., from 1&ndash, 6 GHz, as this region is widely accepted in analyzing various liquid samples. The sensor size is 71 &times, 40 &times, 1.6 mm3 with material selection based on an economically available FR4 substrate. The sensor is realized and experimentally validated for its sensitivity by utilizing in-lab prepared aqueous solution samples. Further, liquid concentration is determined by adopting a polarity correlator, which is applied to the sensor&rsquo, s responses obtained at different values. more...

Universal filtered multi-carrier (UFMC) is a potential multi-carrier system for future cellular networks. UFMC provides low latency, frequency offset robustness, and reduced out-of-band (OOB) emission that results in better spectral efficiency. However, UFMC suffers from the problem of high peak-to-average power ratio (PAPR), which might impact the function of high power amplifiers causing a nonlinear distortion. We propose a comparative probabilistic PAPR reduction technique, called the decomposed selective mapping approach, to alleviate PAPR in UFMC systems. The concept of this proposal depends on decomposing the complex symbol into real and imaginary parts, and then converting each part to a number of different phase vectors prior to the inverse fast Fourier transform (IFFT) operation. The IFFT copy, which introduces the lowest PAPR, is considered for transmission. Results obtained using theoretical analysis and simulations show that the proposed approach can significantly enhance the performance of the UFMC system in terms of PAPR reduction. Besides, it maintains the OOB emission with candidate bit error rate and error vector magnitude performances. more...

A novel and compact dual-polarized (DP) chipless radio-frequency identification (RFID) tag is presented in this paper. This tag can read both vertical and horizontal orientations within its frequency band, which improves the robustness and detection capability of the RFID system. The proposed tag makes use of the slot length variation encoding technique to improve the encoding capacity. This technique can duplicate the encoding capacity, thereby reducing the overall tag size by almost 50%. In particular, the proposed tag has an encoding capacity of 20 bits in the 3&ndash, 8 GHz frequency band and achieves data density of around 15.15 bits/cm2. Three prototypes are fabricated and tested outside an anechoic chamber. Furthermore, one tag is tested at different distances (10 cm, 30 cm, and 60 cm) from the reader and the measured results are compared. The simulated and measured results are in reasonable agreement, with acceptable shifts at some frequencies due to fabrication and experimental errors. more...

There is a growing interest in chipless radio-frequency identification (RFID) technology for a number of Internet of things (IoT) applications. This is due to its advantages of being of low-cost, low-power, and fully printable. In addition, it enjoys ease of implementation. In this paper, we present a novel, compact, chipless radio-frequency identification (RFID) tag that can be read with either vertical or horizontal polarization within its frequency bandwidth. This increases the sturdiness and detection ability of the RFID system. In addition, the difference between the vertical and horizontal responses can be used for tag identification. The proposed tag uses strip length variations to double the coding capacity and thereby reduce the overall size by almost 50%. It has a coding capacity of 20 bits in the operating bandwidth 3 GHz&ndash, 7.5 GHz, and its spatial density is approximately 11 bits/cm2. The proposed tag has a 4.44 bits/GHz spectral capacity, 2.44 bits/cm2/GHz encoding capacity, a spatial density at the center frequency of 358.33 bits/&lambda, 2, and an encoding capacity at the center frequency of 79.63 bits/&lambda, 2/GHz. A prototype is fabricated and experimentally tested at a distance of 10 cm from the RFID reader system. Then, we compare the measured results with the simulations. The simulated results are in reasonable agreement with the simulated ones. more...

This paper focuses on the 60 GHz band, which is known to be very attractive for enabling next-generation abundant multi-Gbps wireless connectivity in 5G communication. We propose a novel concept of a double-layer antenna, loosely inspired from standard log-periodic schemes but with an aperiodic geometry, reduced size, and a limited number of elements while achieving excellent performance over the entire 60 GHz band. To maximize the antenna&rsquo, s efficiency, we have developed a design that differs from those traditionally used for millimeter-wave communication applications. We aim to simultaneously maximize the gain, efficiency, and bandwidth. The reflection coefficient of the proposed design achieves a bandwidth of 20.66% from 53.9 GHz up to 66.3 GHz, covering the entire frequency band of interest. In addition, this proposed structure achieves a maximum realized gain of 11.8 dBi with an estimated radiation efficiency of 91.2%. The proposed antenna is simulated, fabricated, and tested in an anechoic chamber environment. The measurement data show a reasonable agreement with the simulation results, with respect to the bandwidth, gain, and side-lobe level over the operational spectrum. more...