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[IEEE 2018 Seventh Balkan Conference on Lighting (BalkanLight) - Varna, Bulgaria (2018.9.20-2018.9.22)] 2018 Seventh Balkan Conference on Lighting (BalkanLight) - Design and Implementation of a Low-Cost Phasor Measurement Unit: A Comprehensive Review
摘要： The complexity of the contemporary electrical power systems imposes challenges in the aspect of monitoring, protection and control. In order to obtain a high speed of response, wide area effect and prices synchronisation, the grid control functions can be benefited by the implementation of Phasor Measurement Units (PMU). The paper is aimed to make a review of the commercial implementation of Phasor Measurement Units source based implementations (open architecture hardware and software). implementations; as a This paper focuses on standard consequence, the concept of virtual PMU is not discussed here. open then and
关键词： low cost,comparison,review,options,standards,Phasor Measurement Units (PMU)
更新于2025-09-23 15:22:29
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Paediatric Refractive Errors in an Eye Clinic in Osogbo, Nigeria
摘要： BACKGROUND: Paediatric ophthalmology is an emerging subspecialty in Nigeria and as such there is paucity of data on refractive errors in the country. This study set out to determine the pattern of refractive errors in children attending an eye clinic in South West Nigeria. METHODS: A descriptive study of 180 consecutive subjects seen over a 2-year period. Presenting complaints, presenting visual acuity (PVA), age and sex were recorded. Clinical examination of the anterior and posterior segments of the eyes, extraocular muscle assessment and refraction were done. The types of refractive errors and their grades were determined. Corrected VA was obtained. Data was analysed using descriptive statistics in proportions, chi square with p value <0.05. RESULTS: The age range of subjects was between 3 and 16 years with mean age = 11.7 and SD = 0.51; with males making up 33.9%.The commonest presenting complaint was blurring of distant vision (40%), presenting visual acuity 6/9 (33.9%), normal vision constituted >75.0%, visual impairment20% and low vision 23.3%. Low grade spherical and cylindrical errors occurred most frequently (35.6% and 59.9% respectively). Regular astigmatism was significantly more common, P <0.001. The commonest diagnosis was simple myopic astigmatism (41.1%). Four cases of strabismus were seen. CONCLUSION: Simple spherical and cylindrical errors were the commonest types of refractive errors seen. Visual impairment and low vision occurred and could be a cause of absenteeism from school. Low-cost spectacle production or dispensing unit and health education are advocated for the prevention of visual impairment in a hospital set-up.
关键词： Low-cost spectacle dispensing unit,Eye clinic,Child,Refractive error
更新于2025-09-23 15:22:29
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22.3: Low cost fabrication of high contrast ratio and high transmission wire grid polarizer by nanoimprint lithography
摘要： This paper proposes a novel approach for low cost fabrication of large area wire grid polarizer (WGP). WGPs regarded as one potential alternative to traditional rear polarizer and DBEF possess the advantages of large contrast ratio (CR), high transmission. To date WGPs can be fabricated through electron beam direct write, which is slow and expensive, therefore not suitable for large area application. With the development of nano-fabrication methods, for instance, nanoimprint lithography (NIL), large area WGP can be made at low cost and fast speed. Furthermore, flexible polarizer can also be made through roll-to-roll (R2R) NIL. In this paper, a WGP with high TM transmission of around 85% and low TE transmission down to 0.2% through the visible light spectra will be realized through nanofabrication. The contrast ratio of the WGP can reach >450 with peak value >3000. For the fabrication process, atom layer deposition (ALD) will be utilized to prepare imprint mask which can achieve highly precise control of expected structure. In this paper, characterization of the designed WGP will also be narrated in the back part, including transmission, CR and the SEM schematic diagram. We believe that low cost fabrication method shows the potential to be adopted for industrial fabrication of polarizer in the future.
关键词： atom layer deposition (ALD),large area fabrication,low cost fabrication,wire grid polarizer (WGP),high contrast ratio,nanoimprint lithography (NIL),high TM transmission
更新于2025-09-23 15:22:29
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QRCI: A new quantum representation model of color digital images
摘要： In this paper, a new quantum representation model of color digital images (QRCI) is investigated, in which the color information is encoded by the basis states of qubit sequences. QRCI model utilizes 2n+6 qubits to store a color digital image with size 2n×2n. Compared with the existing NCQI representation model, the storage capacity of QRCI improves 218 times. Moreover, some quantum color image processing operations concerning channels and bit-planes based on QRCI are discussed and their quantum circuits are designed. Comparison results of the quantum circuits indicate that these operations based on QRCI have lower quantum cost than NCQI. Therefore, the new proposed QRCI representation model can save more storage space and it is more convenient to conduct quantum color image processing operations concerning channels and bit-planes. This work will help the researchers to further investigate more complex quantum color image processing operations based on QRCI.
关键词： Quantum computation,Quantum cost,Quantum image representation model,Quantum color image processing,Storage capacity,Qubit
更新于2025-09-23 15:22:29
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Effect of electron-donating groups on the electrochemical and optical properties of indoline substituents as hole transport materials: A computational study
摘要： The e?ect of electron-donating property of the groups attached to the indoline substituents with two di?erent low-cost cores (tetraazafulvalene and pyrene) as new hole transport materials (HTMs) was studied on their electrochemical and optical behaviors. The calculations were carried out based on the theoretical approaches including density functional theory (DFT), time-dependent density functional theory (TD-DFT), and Marcus theory. Some important parameters, such as hole mobility, solubility and stability, absorption and emission spectra, Stokes shift, and HOMO/LUMO energies and distributions were obtained and discussed. It was found that the HOMO of all the designed structures is distributed more widely than their LUMO. The results showed that the maximum absorption band of the designed HTMs is red shifted as the electron-donating ability increases. It is also predicted that TAF/indoline-OMe and Py/indoline-NH2 with the hole mobility of 2.90 × 10?3 and 1.51 × 10?3 cm2 V?1 s?1, respectively give higher ?ll factor and short-circuit current density of the device.
关键词： Hole transporting materials,Perovskite solar cells,Di?erent electron-donating groups,Indoline substituents,DFT/TD-DFT,Cost e?ective
更新于2025-09-23 15:22:29
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[IEEE 2018 XXIIIrd International Seminar/Workshop on Direct and Inverse Problems of Electromagnetic and Acoustic Wave Theory (DIPED) - Tbilisi (2018.9.24-2018.9.27)] 2018 XXIIIrd International Seminar/Workshop on Direct and Inverse Problems of Electromagnetic and Acoustic Wave Theory (DIPED) - Dual – Band Microtrip Quasi – Yagi Antenna Design for Free Band and 5G Mobile Communication
摘要： In this work, numerical and experimental analyses of a dual-band microstrip patch dipole-loop antenna are done. This design operates at amateur radio, amateur satellite (2.3-2.4 GHz) band and planned 5G mobile communication band; 3.4-3.8 GHz frequencies. There are two different radiating structures and regions in this antenna. One of the radiating structure is a rectangle shaped loop which is responsible for operation at lower frequency (2.3-2.4 GHz) and the other structure is a printed dipole which is responsible for operation of the upper (3.4-3.6 Hz) frequency. Apart from different operation frequencies, these structures also illustrates different radiation characteristics. The loop shaped region radiates bi-directional broadside radiation while the dipole part radiates with higher gain (peak gain 5 dBi). Proposed design is validated by High Frequency Structure Simulator (HFSS) and also measurements are carried out on fabricated prototype.
关键词： compact low cost and profile antennas,dual band,microstrip antenna,free band,5G
更新于2025-09-23 15:22:29
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Precompensation and System Parameters Estimation for Low-Cost Nonlinear Tera-Hertz Transmitters in the Presence of I/Q Imbalance
摘要： Tera-Hertz (THz) transmission can offer several attractive applications, yet developing low-cost energy-efficient THz devices is at an early stage. The most promising low-cost THz transmitter architecture in the literature is the so-called frequency-multiplier-last architecture. However, it is incapable of transmitting quadrature amplitude modulation (QAM) due to the architecture's inherent nonlinear distortions. We study such nonlinear THz communication systems by incorporating the nonlinearity aspects of the low-cost THz devices and the inphase and quadrature (I/Q) imbalance effect into the signal model. Then, we propose a precompensation scheme to compensate the nonlinearity and I/Q imbalance effects, thus enabling the QAM-capable frequency-multiplier-last architecture for THz systems. The proposed precompensation scheme requires the knowledge of the system parameters. To estimate the system parameters, we propose a maximum-likelihood estimator and its practical implementation via an alternating estimation algorithm. We also derive closed-form expressions for the Cramér–Rao lower bounds (CRLBs) of the system parameters estimation, and design the pilot sequence used in estimating the system parameters. Numerical results show that the proposed precompensation schemes overcome the prominent problems experienced in the existing THz systems, namely severe nonlinear distortions of the modulation symbols as well as spectral spreading and/or large spectrum sidelobes, and mitigate the I/Q imbalance effect.
关键词： precompensation,estimation,QAM,I/Q imbalance,nonlinear distortion,Low-cost,Tera-Hertz
更新于2025-09-23 15:22:29
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A D-band Multiplier-based OOK Transceiver with Supplementary Transistor Modeling in 65-nm Bulk CMOS Technology
摘要： A D-band on-off keying (OOK) transceiver chipset is fabricated in a 65-nm bulk CMOS technology as a low-cost and highly-integrative solution to short-distance wireless connectivity. Supplementary transistor modeling is performed for accurate circuit design at mm-wave frequencies. To overcome low transistor fmax and reduce DC power consumption, the transmitter employs a frequency-multiplier-based architecture with no power amplifier. The receiver adopts a non-coherent architecture consisting of a DC-coupled three-stage differential amplifier and an envelope detector. The OOK transmitter exhibits a measured output power of -9.8 dBm and on-off level difference of 13.2 dB at 134.1 GHz. The receiver shows a measured average responsivity of 4.1 kV/W and a noise equivalent power of 211.4 pW/Hz1/2 over all D-band frequencies. The DC power consumption of the transmitter and receiver are 76 mW and 32.5 mW, respectively. The transceiver is tested in both on-chip loopback and air-channel configurations, and demonstrates data transmission up to 10 Gbps and 2 Gbps at a distance of 0.03 m, respectively.
关键词： transceiver,transistor modeling,D-band,wireless communication,low-cost bulk CMOS,OOK
更新于2025-09-23 15:22:29
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[ACM Press SIGGRAPH Asia 2018 Posters - Tokyo, Japan (2018.12.04-2018.12.07)] SIGGRAPH Asia 2018 Posters on - SA '18 - Panoramic depth reconstruction within a single shot by optimizing global sphere radii
摘要： Depth estimation in scene reconstruction remains one of the main issues in the world of virtual reality. We propose a method that uses low cost camera facilities from previous papers and their specified procedures for stereoscopic 360 imaging. However, instead of using angular disparity, we use the spherical radius for labeling depth values for scene reconstruction. The experimental results show that the reconstructed shape is less distorted by directly optimizing spherical radii than optimizing the angular disparities.
关键词： Matching cost map,Polycamera,Inverse radius disparity depth estimation,Depth Reconstruction,Depth map
更新于2025-09-23 15:22:29
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A Dual-Discrete Model Predictive Control-based MPPT for PV systems
摘要： This paper presents a method that overcomes the problem of the confusion during fast irradiance change in the classical MPPTs as well as in model predictive control (MPC)-based MPPTs available in the literature. The previously introduced MPC-based MPPTs take into account the model of the converter only, which make them prone to the drift during fast environmental conditions. Therefore, the model of the PV array is also considered in the proposed algorithm, which allows it to be prompt during rapid environmental condition changes. It takes into account multiple previous samples of power, and based on that is able to take the correct tracking decision when the predicted and measured power differ (in case of drift issue). After the tracking decision is taken, it will be sent to a second part of the algorithm as a reference. The second part is used for following the reference provided by the first part, where the pulses are sent directly to the converter, without a modulator or a linear controller. The proposed technique is validated experimentally by using a buck converter, fed by a PV simulator. The tracking efficiency is evaluated according to EN50530 standard in static and dynamic conditions. The experimental results show that the proposed MPC-MPPT is a quick and accurate tracker under very fast changing irradiance, while maintaining high tracking efficiency even under very low irradiance.
关键词： Buck converter,dc-dc power conversion,Photovoltaic systems,Double cost function,Maximum power point tracking,Drift,EN50530 standard,MPC
更新于2025-09-23 15:22:29