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Yousef, Basma M., Allam M. Ameen, Bassant H. El Swiefy e Reham Arnous. "A Compact Ultra-wide Band Antenna with a Notched Band for Wireless Communication Systems". Progress In Electromagnetics Research Letters 108 (2023): 31–39. http://dx.doi.org/10.2528/pierl22101503.
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Masuda, Hiroji. "Wide-band and low-noise optical amplification technologies in ultra-high capacity optical communication systems". Review of Laser Engineering 36, Supplement (2008): 184–85. http://dx.doi.org/10.2184/lsj.36.184.
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Tan, Mingqi. "Design of L+Band Bismuth-doped Fiber Laser". Highlights in Science, Engineering and Technology 97 (28 maggio 2024): 147–51. http://dx.doi.org/10.54097/yypbq622.
Testo completoAbstract (sommario):
At present, the development of new communication bands to meet the needs of large communication transmission capacity in the current era is one of the key research topics. The conventional erbium-doped laser is limited by its structure which has the problem of short luminous bandwidth and can not cover a large communication band. Therefore, there is growing interest in designing bismuth-doped glass and fiber with ultra-wide gain bandwidth for fiber laser applications. By utilizing its ultra-wide gain bandwidth characteristics, important communication devices such as broadband fiber amplifiers and broadband tunable fiber lasers can be designed to operate in the L+band, thereby solving the problem that the ultra-wide bandwidth of the optical communication window cannot be achieved in the future high-speed communication systems. In this study, the 1550nm pump source is used to excite the bismuth-doped fiber, and the MATLAB numerical simulation modeling is used to design a bismuth-doped fiber laser with a central wavelength of 1650nm and a threshold power of 10W. To a certain extent, this design addresses the research gap in L+ band bismuth-doped fiber lasers.
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Koshelev, V. I., V. T. Sarychev e S. E. Shipilov. "Estimation of the impulse response of ultra-wide-band systems". Radiophysics and Quantum Electronics 41, n. 9 (settembre 1998): 805–12. http://dx.doi.org/10.1007/bf02677635.
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Okamoto, Seiji, Kyo Minoguchi, Fukutaro Hamaoka, Kengo Horikoshi, Asuka Matsushita, Masanori Nakamura, Etsushi Yamazaki e Yoshiaki Kisaka. "A Study on the Effect of Ultra-Wide Band WDM on Optical Transmission Systems". Journal of Lightwave Technology 38, n. 5 (1 marzo 2020): 1061–70. http://dx.doi.org/10.1109/jlt.2019.2962178.
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Lu, Yong, Shaohe Lv e Xiaodong Wang. "Adaptive Sub-Nyquist Spectrum Sensing for Ultra-Wideband Communication Systems". Symmetry 11, n. 3 (7 marzo 2019): 342. http://dx.doi.org/10.3390/sym11030342.
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With the ever-increasing demand for high-speed wireless data transmission, ultra-wideband spectrum sensing is critical to support the cognitive communication over an ultra-wide frequency band for ultra-wideband communication systems. However, it is challenging for the analog-to-digital converter design to fulfill the Nyquist rate for an ultra-wideband frequency band. Therefore, we explore the spectrum sensing mechanism based on the sub-Nyquist sampling and conduct extensive experiments to investigate the influence of sampling rate, bandwidth resolution and the signal-to-noise ratio on the accuracy of sub-Nyquist spectrum sensing. Afterward, an adaptive policy is proposed to determine the optimal sampling rate, and bandwidth resolution when the spectrum occupation or the strength of the existing signals is changed. The performance of the policy is verified by simulations.
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Deshours, Frédérique, Anne-Laure Billabert, Catherine Algani, Fabrice Blache, Christian Rumelhard e Georges Alquié. "A 40 Gbps electro-absorption modulator integrated laser modeling method for optical transmitter in ultra-wide band radio-over-fiber systems". International Journal of Microwave and Wireless Technologies 1, n. 6 (dicembre 2009): 511–19. http://dx.doi.org/10.1017/s1759078709990791.
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The great interest of optical fiber links in communicating systems especially in ultra-wide band (UWB) communications has grown up in the last decade and requires co-simulation for mixed circuits design exploiting both optical and microwave domains. In this paper, we report an original modeling method of an electro-absorption modulator associated with a distributed-feedback laser to simulate an optical transmitter of an UWB over fiber system. Large signal optoelectronic device models can be developed and implemented in a high-frequency simulator, such as advanced design system-Ptolemy to analyze the performances of fiber radio links and study the impact of the transmitter characteristics. This specific simulation way, taking into account precisely electrical characteristics of both electrical and optical circuits, links two different frequency domains by coupling electrical and optical modules in the same system simulator. Therefore, a complete simulation of an UWB multi-band orthogonal frequency division multiplexing signal transmission over fiber with an external modulator is investigated.
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Barde, Rajesh, Kailash Nemade e Sandeep Waghuley. "Complex Optical Investigation of Sodium Superoxide Loaded Phosphovanadate Glass System in Ultra-Violet and Visible Region". Trends in Sciences 19, n. 23 (10 novembre 2022): 2077. http://dx.doi.org/10.48048/tis.2022.2077.
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Sodium superoxide loaded phosphovanadate based glass systems were prepared from a mixture of vanadium pentoxide (V2O5), phosphorus pentoxide (P2O5) boric acid (H3BO3) and sodium superoxide (NaO2) using a melt-quenching method. Amorphous phase of as-prepared glass system confirmed using XRD technique. Surface morphology of glass system studied using scanning electron microscope. Ultraviolet-visible spectroscopy was employed to extract complex optical parameters like direct and indirect optical band gap, Urbach energy, refractive index, complex dielectric constant and optical conductivity. The absorption bands in the region 200 - 400 nm are recognized to the ligand-to-metal charge transfer. The region of 400 - 600 nm is ascribed to the pair excitation processes. The refractive index increases initially and then decreases for 15 and 20 mol % of NaO2 due non bridging oxygen (NBO) atoms. The 25 mol % of NaO2 sample shows maximum value of extinction coefficient and refractive index. The direct and indirect band gap energies vary in between 2.067 to 1.824 eV and 1.869 to 1.495 eV, respectively. With increase in concentration of NaO2, the effective band gap of NaO2 decreases because band edge shifted into forbidden gap due to increase in defect levels below the conduction. This primary report on sodium superoxide loaded phosphovanadate based glass systems opens wide avenue for battery and supercapacitor applications. Tailing in the bandgap was observed and found to obey Urbach rule. HIGHLIGHTS Sodium superoxide-phosphovanadate glass system prepared by melt-quenching method Complex optical properties of prepared glass system studied successfully Glass system have characteristics of trapping of light Also, glass system has ability to slow down light GRAPHICAL ABSTRACT
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Fornaser, Alberto, Luca Maule, Alessandro Luchetti, Paolo Bosetti e Mariolino De Cecco. "Self-Weighted Multilateration for Indoor Positioning Systems". Sensors 19, n. 4 (20 febbraio 2019): 872. http://dx.doi.org/10.3390/s19040872.
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The paper proposes an improved method for calculating the position of a movable tag whose distance to a (redundant) set of fixed beacons is measured by some suitable physical principle (typically ultra wide band or ultrasound propagation). The method is based on the multilateration technique, where the contribution of each individual beacon is weighed on the basis of a recurring, self-supported calibration of the measurement repeatability of each beacon at a given distance range. The work outlines the method and its implementation, and shows the improvement in measurement quality with respect to the results of a commercial Ultra-Wide-Band (UWB) system when tested on the same set of raw beacon-to-tag distances. Two versions of the algorithm are proposed: one-dimensional, or isotropic, and 3D. With respect to the standard approach, the isotropic solution managed to reduce the maximum localization error by around 25%, with a maximum error of 0.60 m, while the 3D version manages to improve even further the localization accuracy, with a maximum error of 0.45 m.
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Wang, Yong, Biaogang Xu, Dengguo Zhang, Shixiang Xu, Zheng Dong, Xuanke Zeng, Xiaowei Lu e Jihong Pei. "Magneto-Optical Isolator Based on Ultra-Wideband Photonic Crystals Waveguide for 5G Communication System". Crystals 9, n. 11 (30 ottobre 2019): 570. http://dx.doi.org/10.3390/cryst9110570.
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This paper presents a novel magneto-optical isolator based on an ultra-wideband and high efficiency photonic crystals (PCs) waveguide and gyromagnetic ferrites. The three-dimensional numerical simulation finds that the photonic crystals waveguide’s (PCW) transmission efficiency rises with its height and width. The corresponding experiments are performed by using a triangular lattice Al2O3 dielectric posts array in 5G millimeter wave band. The measured transmission efficiency is up to 90.78% for the optimal PCs waveguide structure, which has ultra-wide operating bandwidth from 23.45 to 31.25 GHz. The magneto-optical isolator is designed by inserting two rectangular gyromagnetic ferrites into the PCs waveguide. Due to the contrast between the effective permeability of the left and right circular polarization waves passing through the magnetized ferrite sheets, the ferromagnetic resonance absorption of the forward and reverse waves is different. By using finite element method, the isolation is optimized to be 49.49 dB for the isolator and its relative bandwidth reaches 8.85%. The high isolation, broadband, and easy integration indicate that our designed magneto-optical isolator has significant advantage in 5G communication systems.
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Basir, Shahid, Ubaid Ur Rahman Qureshi, Fazal Subhan, Muhammad Asghar Khan, Syed Agha Hassnain Mohsan, Yazeed Yasin Ghadi, Khmaies Ouahada, Habib Hamam e Fazal Noor. "A Novel Monopole Ultra-Wide-Band Multiple-Input Multiple-Output Antenna with Triple-Notched Characteristics for Enhanced Wireless Communication and Portable Systems". Sensors 23, n. 15 (6 agosto 2023): 6985. http://dx.doi.org/10.3390/s23156985.
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This study introduces a monopole 4 × 4 Ultra-Wide-Band (UWB) Multiple-Input Multiple-Output (MIMO) antenna system with a novel structure and outstanding performance. The proposed design has triple-notched characteristics due to CSRR etching and a C-shaped curve. The notching occurs in 4.5 GHz, 5.5 GHz, and 8.8 GHz frequencies in the C-band, WLAN band, and satellite network, respectively. Complementary Split-Ring Resonators (CSRR) are etched at the feed line and ground plane, and a C-shaped curve is used to reduce interference between the ultra-wide band and narrowband. The mutual coupling of CSRR enables the MIMO architecture to achieve high isolation and polarisation diversity. With prototype dimensions of (60.4 × 60.4) mm2, the proposed antenna design is small. The simulated and measured results show good agreement, indicating the effectiveness of the UWB-MIMO antenna for wireless communication and portable systems.
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Tamas, Razvan D., e Stefania Bucuci. "An Ultra-Wide Band Antenna System for Pulsed Sources Direction Finding". Sensors 20, n. 17 (20 agosto 2020): 4695. http://dx.doi.org/10.3390/s20174695.
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Electric discharges in high-voltage power distribution systems can be localized through their electromagnetic signature in the radio-frequency range. Since discharges produce series of short pulses, the corresponding spectrum usually covers wide frequency ranges, typically up to 1 GHz. In this paper, we propose an ultra-wide band (UWB) antenna system and a direction-finding (DF) approach based on using energy-based descriptors, instead of classical frequency-domain parameters. As an antenna system, we propose a dual-padlock configuration with a suitable pulse-matched response, featuring two unbalanced outputs. The proposed antenna system was successfully validated, both by simulations and measurements.
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Babu, K. Vasu, e Bhuma Anuradha. "Design of MIMO antenna to interference inherent for ultra wide band systems using defected ground structure". Microwave and Optical Technology Letters 61, n. 12 (26 luglio 2019): 2698–708. http://dx.doi.org/10.1002/mop.31958.
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Mucchi, Lorenzo, Sara Jayousi, Alessio Martinelli, Stefano Caputo, Emanuele Intrieri, Giovanni Gigli, Teresa Gracchi et al. "A Flexible Wireless Sensor Network Based on Ultra-Wide Band Technology for Ground Instability Monitoring". Sensors 18, n. 9 (5 settembre 2018): 2948. http://dx.doi.org/10.3390/s18092948.
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An innovative wireless sensor network (WSN) based on Ultra-Wide Band (UWB) technology for 3D accurate superficial monitoring of ground deformations, as landslides and subsidence, is proposed. The system has been designed and developed as part of an European Life+ project, called Wi-GIM (Wireless Sensor Network for Ground Instability Monitoring). The details of the architecture, the localization via wireless technology and data processing protocols are described. The flexibility and accuracy achieved by the UWB two-way ranging technique is analysed and compared with the traditional systems, such as robotic total stations (RTSs) and Ground-based Interferometric Synthetic Aperture Radar (GB-InSAR), highlighting the pros and cons of the UWB solution to detect the surface movements. An extensive field trial campaign allows the validation of the system and the analysis of its sensitivity to different factors (e.g., sensor nodes inter-visibility, effects of the temperature, etc.). The Wi-GIM system represents a promising solution for landslide monitoring and it can be adopted in combination with traditional systems or as an alternative in areas where the available resources are inadequate. The versatility, easy/fast deployment and cost-effectiveness, together with good accuracy, make the Wi-GIM system a possible solution for municipalities that cannot afford expensive/complex systems to monitor potential landslides in their territory.
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Perez-Ramos, Aldo-Eleazar, Salvador Villarreal-Reyes, Alejandro Galaviz-Mosqueda e Catherine Lepers. "Design of Optical-Wireless IR-UWBoF Systems with Spectral Line Suppression Capabilities". Electronics 11, n. 21 (28 ottobre 2022): 3496. http://dx.doi.org/10.3390/electronics11213496.
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Impulse-Radio Ultra-Wide Band (IR-UWB) over Fiber (IR-UWBoF) has been proposed to interconnect IR-UWB-based deployments separated by hundreds of meters or even kilometers. IR-UWB transmissions must comply with spectral masks provided by radio spectrum regulatory agencies. The maximum transmit power of an IR-UWB signal is adversely affected by the presence of spectral lines in its Power Spectral Density (PSD). Thus, it is desirable that the PSD of signals generated by IR-UWBoF systems does not show spectral lines. Previous works have shown the feasibility of deploying of optical-wireless IR-UWBoF systems. However, most of these proposals report PSDs showing spectral lines. To the best of our knowledge, spectral line suppression has not been previously studied for optical-wireless IR-UWBoF systems. This work shows the design and implementation of optical-wireless IR-UWBoF systems generating signals with Spectral Line-Free (SLF) PSDs. The proposal considers the use the use of a specifically designed convolutional code combined with Binary Phase Shift Keying (BPSK) or Quaternary Biorthogonal Pulse Position Modulation (Q-BOPPM) to provide a SLF PSD in IR-UWBoF systems. A testbed consisting of 30 km of single-mode optical fiber (SMF) concatenated to a 20 cm wireless link was physically implemented. The results show that a SLF PSD is achieved for both the optical and the wireless transmissions, even when the binary data source feeding the system is not perfectly random.
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Chen, Zilong, Zhaowei Zhu, Liting Huang e Chuantong Cheng. "High sensitivity UV photodetectors based on low-cost TiO2 P25-graphene hybrids". Nanotechnology 33, n. 8 (30 novembre 2021): 08LT01. http://dx.doi.org/10.1088/1361-6528/ac3a37.
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Abstract Photodetectors (PDs) are the core component of multiple commercial optical sensing systems. Currently, the detection of ultra-weak ultraviolet (UV) optical signals is becoming increasingly important for wide range of applications in civil and military industries. Due to its wide band gap, low cost, and long-term stability, titanium dioxide (TiO2) is an attractive material for UV photodetection. A kind of low-cost TiO2 nanomaterial (named as P25) manufactured by flame hydrolysis is an easily available commercial material. However, a low-cost and high-sensitivity UV PD based on P25 has not been achieved until now. Here, a hybrid UV PD with monolayer CVD graphene covered by a thin film of P25 quantum dots was prepared for the first time, and its responsivity was approximately 105 A W−1 at 365 nm wavelength. The response time and recovery time of the UV PD were 32.6 s and 34 s, respectively. Strong light absorption and photocontrolled oxygen adsorption of the P25 layer resulted in high UV sensitivity. The UV PDs proposed in this work have great potential for commercialization due to their low cost and high sensitivity.
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Patil, Dnyaneshwar S., e E. P. Samuel. "Analysis of Optical Properties of GaN/AlGaN Quantum Well Ultra-Violet Laser Diode Using 6X6 Hamiltonian". Materials Science Forum 638-642 (gennaio 2010): 1653–58. http://dx.doi.org/10.4028/www.scientific.net/msf.638-642.1653.
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The Quantum well structures have exhibited significant utility in the fabrication of advanced laser devices. The Gallium nitride semiconductor and its alloy particularly AlGaN based quantum structures are having important applications in optical data storage systems and the visible displays. Due to tailoring of wide band gap energy the spectrum obtained is from visible to ultraviolet wavelength range. We had thoroughly investigated the influence of Aluminum mole fraction variation in AlxGa1-xN under a biased condition for GaN/AlGaN based quantum heterostructure optical properties. Here, we had used 6X6 Hamiltonian to realize these properties. The 6X6 Hamiltonian has been chosen to include the many body effect in the calculation and to enhance the accuracy of the optimized results. The paper is focused to reveal the Aluminum mole fraction dependence of near and far filed intensities, peak optical gain, carrier concentration, and optical confinement factor. The effective index method has been used in determination of the optical field intensity in the near and far regimes. The variation in Aluminum mole fraction produces disparity in carrier concentration; hence, we have obtained the spontaneous emission and optical gain as a function of photon energy for different carrier density. The piezoelectric effect on GaN quantum well due to AlGaN barriers has been included through Poisson equation. This Poisson equation has been solved in a self-consistent manner along with Schrödinger and subsequently carrier concentrations have been deduced with a high accuracy using our simulation tools developed in MATLAB.
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Boyle, Alex, e Matthew E. Tolentino. "Localization within Hostile Indoor Environments for Emergency Responders". Sensors 22, n. 14 (8 luglio 2022): 5134. http://dx.doi.org/10.3390/s22145134.
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Recent advances in techniques to improve indoor localization accuracy for personnel and asset tracking challenges has enabled wide-spread adoption within the retail, manufacturing, and health care industries. Most currently deployed systems use distance estimates from known reference locations to localize a person or asset using geometric lateration techniques. The distances are determined using one of many radio frequency (RF) based ranging techniques. Unfortunately, such techniques are susceptible to interference and multipath propagation caused by obstructions within buildings. Because range inaccuracies from known locations can directly lead to incorrect position estimates, these systems often require careful upfront deployment design to account for site-specific interference sources. However, the upfront system deployment requirements necessary to achieve high positioning accuracy with RF-based ranging systems makes the use of such systems impractical, particularly for structures constructed of challenging materials or dense configurations. In this paper, we evaluate and compare the accuracy and precision of alternative RF-based devices within a range of indoor spaces composed of different materials and sizes. These spaces range from large open areas such as gymnasiums to confined engineering labs of traditional buildings as well as training buildings at the local Fire Department Training Facility. Our goal is to identify the impact of alternative RF-based systems on localization accuracy and precision specifically for first responders that are called upon to traverse structures composed of different materials and configurations. Consequently, in this study we have specifically chosen spaces that are likely to be encountered by firefighters during building fires or emergency medical responses. Moreover, many of these indoor spaces can be considered hostile using RF-based ranging techniques. We built prototype wearable localization edge devices designed for first responders and characterize both ranging and localization accuracy and precision using alternative transceivers including Bluetooth Low Energy, 433 MHz, 915 MHz, and ultra-wide band. Our results show that in hostile environments, using ultra-wide band transceivers for localization consistently outperforms the alternatives in terms of precision and accuracy.
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Jamwal, Nishant Singh, e Amirkianoosh Kiani. "Advanced Fabrication of 3D Micro/Nanostructures of Gallium Oxide with a Tuned Band Gap and Optical Properties". Micromachines 15, n. 3 (29 febbraio 2024): 347. http://dx.doi.org/10.3390/mi15030347.
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Gallium oxide (Ga2O3) is a promising material for high-power semiconductor applications due to its wide band gap and high breakdown voltage. However, the current methods for fabricating Ga2O3 nanostructures have several disadvantages, including their complex manufacturing processes and high costs. In this study, we report a novel approach for synthesizing β-Ga2O3 nanostructures on gallium phosphide (GaP) using ultra-short laser pulses for in situ nanostructure generation (ULPING). We varied the process parameters to optimize the nanostructure formation, finding that the ULPING method produces high-quality β-Ga2O3 nanostructures with a simpler and more cost-effective process when compared with existing methods. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) were used to characterize the samples, which indicated the presence of phosphorous. X-ray photoelectron spectroscopy (XPS) confirmed the formation of gallium oxide, along with a minor amount of phosphorus-containing compounds. Structural analysis using X-ray diffraction (XRD) revealed the formation of a monoclinic β-polymorph of Ga2O3. We also measured the band gap of the materials using reflection electron energy loss spectroscopy (REELS), and found that the band gap increased with higher nanostructure formation, reaching 6.2 eV for the optimized sample. Furthermore, we observed a change in the heterojunction alignment, which we attribute to the change in the oxidation of the samples. Our results demonstrate the potential of ULPING as a novel, simple, and cost-effective method for fabricating Ga2O3 nanostructures with tunable optical properties. The ULPING method offers a green alternative to existing fabrication methods, making it a promising technology for future research in the field of Ga2O3 nanostructure fabrication.
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Sheikh, Muhammad Usman, Boxuan Xie, Kalle Ruttik, Hüseyin Yiğitler, Riku Jäntti e Jyri Hämäläinen. "Ultra-Low-Power Wide Range Backscatter Communication Using Cellular Generated Carrier". Sensors 21, n. 8 (10 aprile 2021): 2663. http://dx.doi.org/10.3390/s21082663.
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With the popularization of Internet-of-things (IoT) and wireless communication systems, a diverse set of applications in smart cities are emerging to improve the city-life. These applications usually require a large coverage area and minimal operation and maintenance cost. To this end, the recently emerging backscatter communication (BC) is gaining interest in both industry and academia as a new communication paradigm that provides high energy efficient communications that may even work in a battery-less mode and, thus, it is well suited for smart city applications. However, the coverage of BC in urban area deployments is not available, and the feasibility of its utilization for smart city applications is not known. In this article, we present a comprehensive coverage study of a practical cellular carrier-based BC system for indoor and outdoor scenarios in a downtown area of a Helsinki city. In particular, we evaluate the coverage outage performance of different low-power and wide area technologies, i.e., long range (LoRa) backscatter, arrow band-Internet of Things (NB-IoT), and Bluetooth low energy (BLE) based BC at different frequencies of operation. To do so, we carry out a comprehensive campaign of simulations while using a sophisticated three-dimensional (3D) ray tracing (RT) tool, ITU outdoor model, and 3rd generation partnership project (3GPP) indoor hotspot model. This study also covers the energy harvesting aspects of backscatter device, and it highlights the importance of future backscatter devices with high energy harvesting efficiency. The simulation results and discussion provided in this article will be helpful in understanding the coverage aspects of practical backscatter communication system in a smart city environment.
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Ji, Yuxiang, Yuhang Du, Jixuan Dai, Hui Zou, Ruizhe Zhang e Dinghao Zhou. "Dual-Core Photonic Crystal Fiber Polarization Beam Splitter Based on a Nematic Liquid Crystal with an Ultra-Short Length and Ultra-Wide Bandwidth". Electronics 13, n. 12 (15 giugno 2024): 2343. http://dx.doi.org/10.3390/electronics13122343.
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This paper presents a novel pentagonal structure dual-core photonic crystal fiber polarizing beam splitter (PS-DC-PCF PBS) filled with a nematic liquid crystal (NLC) in the central hole. Unlike previous designs with symmetric arrangements, the upper and lower halves of the structure have different air hole arrangements. The upper half consists of air holes arranged in a regular quadrilateral pattern, while the lower half features a regular hexagonal arrangement of air holes. By filling the central hole with birefringent liquid crystal, the birefringence of the structure is enhanced, reducing the coupling lengths along the x polarization and y polarization directions. The polarization properties, coupling characteristics, and the influence of different structural parameters on the extinction ratio of the polarizing beam splitter are analyzed using the full-vector finite element method. Simulation results demonstrate that the designed PS-DC-PCF PBS achieves a maximum extinction ratio (ER) of 72.94 dB with a splitting length of only 61.9 μm and a wide operating bandwidth of 423 nm (1.324–1.747 μm), covering most of the O, E, S, C, L, and U communication bands. It exhibits not only ultra-short splitting lengths and ultra-wide splitting bandwidth but also good manufacturing tolerances and anti-interference capabilities. The designed PS-DC-PCF PBS could provide crucial device support for future all-optical communication systems and has potential applications in fiber optic communication or fiber laser systems.
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Farhad, Arshad, e Jae-Young Pyun. "Terahertz Meets AI: The State of the Art". Sensors 23, n. 11 (24 maggio 2023): 5034. http://dx.doi.org/10.3390/s23115034.
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Terahertz (THz) is a promising technology for future wireless communication networks, particularly for 6G and beyond. The ultra-wide THz band, ranging from 0.1 to 10 THz, can potentially address the limited capacity and scarcity of spectrum in current wireless systems such as 4G-LTE and 5G. Furthermore, it is expected to support advanced wireless applications requiring high data transmission and quality services, i.e., terabit-per-second backhaul systems, ultra-high-definition streaming, virtual/augmented reality, and high-bandwidth wireless communications. In recent years, artificial intelligence (AI) has been used mainly for resource management, spectrum allocation, modulation and bandwidth classification, interference mitigation, beamforming, and medium access control layer protocols to improve THz performance. This survey paper examines the use of AI in state-of-the-art THz communications, discussing the challenges, potentials, and shortcomings. Additionally, this survey discusses the available platforms, including commercial, testbeds, and publicly available simulators for THz communications. Finally, this survey provides future strategies for improving the existing THz simulators and using AI methods, including deep learning, federated learning, and reinforcement learning, to improve THz communications.
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Qu, Yuwei, Jinhui Yuan, Shi Qiu, Xian Zhou, Feng Li, Binbin Yan, Qiang Wu et al. "A Novel Gold Film-Coated V-Shape Dual-Core Photonic Crystal Fiber Polarization Beam Splitter Covering the E + S + C + L + U Band". Sensors 21, n. 2 (12 gennaio 2021): 496. http://dx.doi.org/10.3390/s21020496.
Testo completoAbstract (sommario):
In this paper, a novel gold film-coated V-shape dual-core photonic crystal fiber (V-DC-PCF) polarization beam splitter (PBS) based on surface plasmon resonance effect is proposed. The coupling lengths of the X-polarization (X-pol) and Y-polarization (Y-pol) and the corresponding coupling length ratio of the proposed V-DC-PCF PBS without gold film and with gold film are compared. The fiber structure parameters and thickness of the gold film are optimized through investigating their effects on the coupling lengths and coupling length ratio. As the propagation length increases, the normalized output powers of the X-pol and Y-pol of the proposed V-DC-PCF PBS at the three wavelengths 1.610, 1.631, and 1.650 μm are demonstrated. The relationships between the extinction ratio (ER), insertion loss (IL) and wavelength for the three splitting lengths (SLs) 188, 185, and 182 μm are investigated. Finally, it is demonstrated that for the proposed V-DC-PCF PBS, the optimal SL is 188 μm, the ILs of the X-pol and Y-pol are less than 0.22 dB, and the splitting bandwidth (SB) can cover the E + S + C + L + U band. The proposed V-DC-PCF PBS has the ultra-short SL, ultra-wide SB, and ultra-low IL, so it is expected to have important applications in the laser, sensing, and dense wavelength division multiplexing systems.
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Ruman, Kornel, Alena Pietrikova, Pavol Galajda, Igor Vehec, Tibor Rovensky e Martin Kmec. "A new approach to construction of extended kit for M-Sequence UWB sensor system based on LTCC". Microelectronics International 33, n. 3 (1 agosto 2016): 130–35. http://dx.doi.org/10.1108/mi-03-2016-0029.
Testo completoAbstract (sommario):
Purpose The purpose of this paper is to introduce modified in–phase and quadrature components (I–Q) demodulator based on low temperature co-fired ceramics (LTCC) dielectric substrate GreenTape 951PX for M-Sequence ultra-wide band (UWB) sensor system. Design/methodology/approach Microstrip low pass (LP) and band pass (BP) filters for UWB sensor systems with required properties (for both filters, minimum attenuation is −40dB in stopband, bandwidth of pass band is 6 to 8.5 GHz for BP filter and cutoff frequency is 2.5 GHz for LP filter) were designed, simulated, fabricated and measured using dielectric substrates Du Pont GreenTape 951 PX. The developed microstrip filters were integrated with all parts of I–Q demodulator on one multilayer structure based on LTCC substrate Du Pont GreenTape 951 PX. Findings Both type of microstrip filters integrated in the I– Q demodulator achieved better transmission characteristics in comparison with commercial available filters. It was shown that LTCC technology based on GreenTape 951PX proves good stability in gigahertz frequency and suitability for fabrication of I–Q demodulator with a multilayer approach. Originality/value The novelty of this work lies in substituting commercially available LP and BP filters used in I– Q demodulator by microstrip LP and BP filters with better performance and furthermore the I– Q demodulator is fabricated based on LTCC instead of previously used PCB.
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Li, Lixia, Chuang Zhu, Haixia Liu, Yan Li, Qi Wang e Kun Su. "Quality Factor Enhancement of Piezoelectric MEMS Resonator Using a Small Cross-Section Connection Phononic Crystal". Sensors 22, n. 20 (12 ottobre 2022): 7751. http://dx.doi.org/10.3390/s22207751.
Testo completoAbstract (sommario):
Anchor loss is usually the most significant energy loss factor in Micro-Electro-Mechanical Systems (MEMS) resonators, which seriously hinders the application of MEMS resonators in wireless communication. This paper proposes a cross-section connection phononic crystal (SCC-PnC), which can be used for MEMS resonators of various overtone modes. First, using the finite element method to study the frequency characteristics and delay line of the SCC-PnC band, the SCC-PnC has an ultra-wide bandgap of 56.6–269.6 MHz. Next, the effects of the height h and the position h1 of the structural parameters of the small cross-connected plate on the band gap are studied, and it is found that h is more sensitive to the width of the band gap. Further, the SCC-PnC was implanted into the piezoelectric MEMS resonator, and the admittance and insertion loss curves were obtained. The results show that when the arrangement of 4 × 7 SCC-PnC plates is adopted, the anchor quality factors of the third-order overtone, fifth-order overtone, and seventh-order overtone MEMS resonators are increased by 1656 times, 2027 times, and 16 times, respectively.
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Gillani, S. S. A., Nisar Fatima, I. Zeba, M. Shakil, R. Kiran, M. B. Tahir, Muhammad Rizwan, Riaz Ahmad e A. Jawad. "Static isotropic pressure induced ultra-wide band gap response of NaCaF3 fluoro-perovskite and its repercussions on optical properties: ab initio calculation". Molecular Simulation 47, n. 18 (20 ottobre 2021): 1549–57. http://dx.doi.org/10.1080/08927022.2021.1992406.
Testo completo
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Pino-Ortega, José, Asier Los Arcos, Petrus Gantois, Filipe Manuel Clemente, Fabio Yuzo Nakamura e Markel Rico-González. "The Influence of Antenna Height on the Measurement of Collective Variables Using an Ultra-Wide Band Based Local Positioning System in Team Sports". Sensors 21, n. 7 (1 aprile 2021): 2424. http://dx.doi.org/10.3390/s21072424.
Testo completoAbstract (sommario):
Ultra-wide band (UWB) based local positioning systems (LPS) are based on devices and a portable antenna set. The optimal installation height of the antennae is crucial to ensure data accuracy. Collective variables are metrics that consider at least two pairs of coordinates, which may lead to lower precision than an individual one. Therefore, the aim of this study was to compare the influence of antenna height with collective metrics using a UWB (i.e., IMU; WIMU PRO™, RealTrack Systems, Almeria, Spain) based LPS. Data acquisition was carried out in a basketball court measuring 28 × 15 m. Five devices were used; one of which was carried by a healthy and well-trained athlete (age: 38 years, mass: 76.34 kg, height 1.70 m), while each of the remaining four was positioned on a tripod in one of the four corners of the court. Four kinds of variables were extracted: (1) static distances, (2) dynamic distances, (3) static areas and (4) dynamic areas in all antenna installation modes of 0.15, 1.30 and 2.00 m. The results showed that the antenna of 1.30 m provided better accuracy for all measures (% difference range from −0.94 to 1.17%) followed by the antenna of 2.00 m (% difference range from −2.50 to 2.15%), with the antenna of 0.15 m providing the worst accuracy level (% difference range from −1.05 to 3.28%). Overall, the measurements of distance metrics showed greater accuracy than area metrics (distance % difference range from −0.85 to 2.81% and area % difference range from −2.50 to 3.28). In conclusion, the height of the antennae in basketball courts should be similar to the height at which the devices are attached to a player’s upper back. However, as the precision is sensitive to the magnitude of the measure, further studies should assess the effects of the relative height of antennae in team sports with greater playing spaces.
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Du, Jinxin, Ruimeng Wang, Haiyan Li, Xue-Xia Yang e Christophe Roblin. "All-Textile Compact Ultra-Wideband Microstrip Antenna with Full Ground Plane for WBAN Applications". International Journal of Antennas and Propagation 2024 (27 gennaio 2024): 1–10. http://dx.doi.org/10.1155/2024/4236695.
Testo completoAbstract (sommario):
A novel low-profile all-textile microstrip antenna for ultra-wideband (UWB) applications in wireless body area networks (WBANs) is presented. The antenna incorporates flexible materials such as felt and conductive fabrics which provide optimal wearing comfort and durability. The use of a single dielectric substrate layer facilitates the integration process. The antenna also features a full background plane that minimizes the back radiation towards the human body. Multiple branches are designed in a compact area to generate adjacent resonances, and their combination achieves broadband characteristics across the 4.83–9.57 GHz frequency band. The antenna has a miniaturized size of 60 mm × 60 mm, which is 1.6λg × 1.6λg (where λg represents the guided wavelength at the center frequency), and it has a high realized gain of up to 10 dBi. The fully grounded structure also ensures good isolation between the antenna and the human body, thereby alleviating concerns regarding safety and radiation degradation in WBAN context. Simulation results indicate that the antenna maintains high performance levels during various bending tests. Given its favourable properties like ultra-wide bandwidth, compact size, low profile, high flexibility, and low specific absorption rate (SAR), the proposed design could find broad application prospects in high-speed WBAN systems.
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Nefyodov, Eugeniy I., Igor N. Ponomarev e Viacheslav P. Zayarnyi. "The structure of the radiation field of a symmetric slot line perpendicular to the edge of an infinite half-plane, taking into account the cross-polarization component". Physics of Wave Processes and Radio Systems 26, n. 2 (1 luglio 2023): 27–35. http://dx.doi.org/10.18469/1810-3189.2023.26.2.27-35.
Testo completoAbstract (sommario):
Background. Symmetric slot lines on a perfectly reflecting half-plane are good mathematical models for slot antennas on an ideal plane of finite dimensions, which in practice have a high gain and operate over a wide frequency band. These antennas are used in ultra-fast information processing systems based on microwave and optical volume integrated circuits. Aim. The work presents a solution to the problem of radiation of a perfectly reflecting half-plane, which was excited by a symmetric slot line with a different law of slot expansion. Methods. The problem was solved by the Fourier variable separation method, by which the Green tensor function was obtained, which connects the two components of the antenna radiation field with the excitation field in the gap. Results. It is shown that in the far zone, the radiation field of an ideally reflecting half-plane has two components: the main and crosspolarization. The Green tensor function has a complex form and consists of two terms. The analysis of the Green tensor function shows the participation of each term in the formation of a field in the far zone, demonstrates the mechanism of radiation and leads to known special cases for slot radiators. Conclusion. The validity of the presented mathematical model is confirmed by experimental research.
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Qu, Yuwei, Ying Han, Jinhui Yuan, Xian Zhou, Binbin Yan, Kuiru Wang, Xinzhu Sang e Chongxiu Yu. "A Novel Liquid Crystal-Filled, Dual-Core Photonic Crystal Fiber Polarization Beam Splitter Covering the E + S + C + L + U Communication Band". Photonics 8, n. 11 (21 ottobre 2021): 461. http://dx.doi.org/10.3390/photonics8110461.
Testo completoAbstract (sommario):
This paper proposes a novel liquid crystal-filled, dual core photonic crystal fiber polarization beam splitter (LC-DC-PCF PBS) based on the coupled mode theory of DC-PCF. The mode birefringence of odd and even modes, coupling lengths (CLs) of the X-polarization (X-pol) and Y-polarization (Y-pol), and the corresponding coupling length ratio (CLR) of the proposed LC-DC-PCF PBS filled without LC E7 and with LC E7 are compared. The change rules of the CLs of the X-pol and Y-pol and CLR of the proposed LC-DC-PCF with wavelengths for different cladding microstructure parameters were investigated. The relationships between the X-pol and Y-pol normalized output powers in core A of the proposed LC-DC-PCF PBS and the propagation length at the wavelength of 1.604 μm are discussed. Finally, by studying the change of extinction ratio (ER) with wavelength, the LC-DC-PCF PBS ER of 60.3 and 72.2 dB at wavelengths 1.386 and 1.619 μm are achieved, respectively. The final splitting length (LS) is 94 μm, and the splitting bandwidth is 349 nm (1.352~1.701 μm), covering the whole of the E + S + C + L + U communication bands. The proposed LC-DC-PCF PBS has good beam-splitting performance, such as ultra-short LS and ultra-wide splitting bandwidth, with potential applications in laser, sensing, and communication systems.
31
Delamare, Mickael, Fabrice Duval e Remi Boutteau. "A New Dataset of People Flow in an Industrial Site with UWB and Motion Capture Systems". Sensors 20, n. 16 (12 agosto 2020): 4511. http://dx.doi.org/10.3390/s20164511.
Testo completoAbstract (sommario):
Improving performance and safety conditions in industrial sites remains a key objective for most companies. Currently, the main goal is to be able to dynamically locate both people and goods on the site. Security and access regulation to restricted areas are often ensured by doors or badge barriers and those have several issues when faced with people being in places they are not supposed to be in or even tools of objects being used incorrectly. In addition to this, a growing use of new devices requires precise information about their location in the environment such as mobile robots or drones. Therefore, it is becoming essential to have the tools to dynamically manage these flows of people and goods. Ultra-wide-band and motion capture solutions will be used to quickly identify people who may be in unauthorized areas or performing tasks which they have been uninstructed to do. In addition to the dynamic tracking of people, this also overcomes some issues associated with moving objects or tools around the production floor. We offer a new set of data that provides precise information on worker movement. This dataset can be used to develop new metrics regarding worker efficiency and safety.
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Rapinski, Jacek, e Artur Janowski. "The Optimal Location of Ground-Based GNSS Augmentation Transceivers". Geosciences 9, n. 3 (27 febbraio 2019): 107. http://dx.doi.org/10.3390/geosciences9030107.
Testo completoAbstract (sommario):
Modern Global Navigation Satellite Systems (GNSS) allow for positioning with accuracies ranging from tens of meters to single millimeters depending on user requirements and available equipment. A major disadvantage of these systems is their unavailability or limited availability when the sky is obstructed. One solution is to use additional range measurements from ground-based nodes located in the vicinity of the receiver. The highest accuracy of distance measurement can be achieved using ultra wide band (UWB) or ZigBee phase shift measurement. The position of the additional transmitter must be carefully selected in order to obtain the optimal improvement in the dilution of precision (DOP), which reflects the improvement in the geometry of solution. The presented case study depicts a method for selecting the optimal location of a ground-based ranging source. It is based on a search of a minimum DOP value as a transmitter location function. The parameters of objective function are the elevation and azimuth of the transceiver. The solution was based on a limited-memory Broyden–Fletcher–Goldfarb–Shanno with Box constraints (L-BFGS-B) method and a numerical optimization algorithm for parameter value estimation. The presented approach allows for the selection of the optimal location of a ground-based source of ranging signals in GNSS processing from a geometry of solution point of view. This can be useful at the design stage of an augmentation network of ground-based transceivers. This article presents a theoretical basis and a case study presenting the selection of the optimal location of a ground-based ranging source.
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Muraviev, Sergei, Vitaly Dorofeev, Pavel Kuznechikov, Artem Sharafeev, Maksim Koptev e Arkady Kim. "Broadband Amplification in the 2.6–2.9 μm Wavelength Range in High-Purity Er3+-Doped Zinc-Tellurite Fibers Pumped by Diode Lasers". Photonics 10, n. 10 (11 ottobre 2023): 1140. http://dx.doi.org/10.3390/photonics10101140.
Testo completoAbstract (sommario):
In recent years, great progress has been made in the technology of high-purity and ultra-dry tellurite glasses, which has enabled the creation of high-purity single-mode tellurite fibers doped with rare-earth ions. This technology has made it possible to demonstrate laser generation in the range of about 2.7 μm in erbium-doped tungsten tellurite fibers. In this paper, we present an experimental study of broadband amplification in erbium-doped zinc-tellurite fibers. Zinc-tellurite glasses containing modifying components, such as Na2O, La2O3, Bi2O3, or rare-earth metal oxides, are known to have noticeably lower phonon energy than heavy metal-tellurite systems, namely, tungsten tellurite glasses, which leads to better lasing output. The on-off gain of 30- and 60-cm long zinc-tellurite fibers has been measured in a wide range of diode pump powers. It has been shown for the first time that the amplification band is essentially extended, with pump power reaching over 250 nm (2600–2850 nm) at a peak power of about 40 W for a 30-cm long fiber.
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Chahine, Georges, Pete Schroepfer, Othmane-Latif Ouabi e Cédric Pradalier. "A Magnetic Crawler System for Autonomous Long-Range Inspection and Maintenance on Large Structures". Sensors 22, n. 9 (22 aprile 2022): 3235. http://dx.doi.org/10.3390/s22093235.
Testo completoAbstract (sommario):
The inspection and maintenance of large-scale industrial structures are major challenges that require time-efficient and reliable solutions to ensure the healthy condition of structures during operation. Autonomous robots may provide a promising solution for this purpose. In particular, they could lead to faster and more reliable inspection and maintenance without direct intervention from human operators. In this paper, we present a custom magnetic crawler system, and sensor suit and sensing modalities to enable such robotic operation. We first describe a localization framework based on a mesh created from a point cloud coupled with Inertial Measurement Unit (IMU) and Ultra-Wide Band (UWB) readings. Next, we introduce a mapping framework that relies on a 3D laser, and explicitly state how autonomous navigation and obstacle avoidance can be developed. Lastly, we present how ultrasonic guided waves (UGWs) are integrated into the system to provide accurate robot localization and structural feature mapping by relying on acoustic reflections in combination with the other systems. It is envisioned that long-range inspection capabilities that are not yet available in current industrial mobile platforms could emerge from the designed robotic system.
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Huang, Zhenchuan, Shuanggen Jin, Ke Su e Xu Tang. "Multi-GNSS Precise Point Positioning with UWB Tightly Coupled Integration". Sensors 22, n. 6 (14 marzo 2022): 2232. http://dx.doi.org/10.3390/s22062232.
Testo completoAbstract (sommario):
Global Navigation Satellite Systems (GNSSs) can provide high-precision positioning services, which can be applied to fields including navigation and positioning, autonomous driving, unmanned aerial vehicles and so on. However, GNSS signals are easily disrupted in complex environments, which results in a positioning performance with a significantly inferior accuracy and lengthier convergence time, particularly for the single GNSS system. In this paper, multi-GNSS precise point positioning (PPP) with tightly integrating ultra-wide band (UWB) technology is presented to implement fast and precise navigation and positioning. The validity of the algorithm is evaluated by a set of GNSS and UWB data. The statistics indicate that multi-GNSS/UWB integration can significantly improve positioning performance in terms of the positioning accuracy and convergence time. The improvement of the positioning performance for the GNSS/UWB tightly coupled integration mainly concerns the north and east directions, and to a lesser extent, the vertical direction. Furthermore, the convergence performance of GNSS/UWB solution is analyzed by simulating GNSS signal interruption. The reliability and robustness of GNSS/UWB solution during GNSS signal interruption is verified. The results show that multi-GNSS/UWB solution can significantly improve the accuracy and convergence speed of PPP.
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Moragrega, Ana, e Carles Fernández-Prades. "A Data-Driven Factor Graph Model for Anchor-Based Positioning". Sensors 23, n. 12 (17 giugno 2023): 5660. http://dx.doi.org/10.3390/s23125660.
Testo completoAbstract (sommario):
This work presents a data-driven factor graph (FG) model designed to perform anchor-based positioning. The system makes use of the FG to compute the target position, given the distance measurements to the anchor node that know its own position.The aim was to design a hybrid structure (that involves data and modeling approaches) to address positioning models from a Bayesian point of view, customizing them for each technology and scenario. The weighted geometric dilution of precision (WGDOP) metric, which measures the effect on the positioning solution of distance error to the corresponding anchor node and network geometry of the anchor nodes, was taken into account. The presented algorithms were tested with simulated data and also with real-life data collected from IEEE 802.15.4-compliant sensor network nodes with a physical layer based on ultra-wide band (UWB) technology, in scenarios with one target node, three and four anchor nodes, and a time-of-arrival-based range technique. The results showed that the presented algorithm based on the FG technique provided better positioning results than the least squares-based algorithms and even UWB-based commercial systems in various scenarios, with different setups in terms of geometries and propagation conditions.
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Crețu-Sîrcu, Amalia Lelia, Henrik Schiøler, Jens Peter Cederholm, Ion Sîrcu, Allan Schjørring, Ignacio Rodriguez Larrad, Gilberto Berardinelli e Ole Madsen. "Evaluation and Comparison of Ultrasonic and UWB Technology for Indoor Localization in an Industrial Environment". Sensors 22, n. 8 (11 aprile 2022): 2927. http://dx.doi.org/10.3390/s22082927.
Testo completoAbstract (sommario):
Evaluations of different technologies and solutions for indoor localization exist but only a few are aimed at the industrial context. In this paper, we compare and analyze two prominent solutions based on Ultra Wide Band Radio (Pozyx) and Ultrasound (GoT), both installed in an industrial manufacturing laboratory. The comparison comprises a static and a dynamic case. The static case evaluates average localization errors over 90 s intervals for 100 ground-truth points at three different heights, corresponding to different relevant objects in an industrial environment: mobile robots, pallets, forklifts and worker helmets. The average error obtained across the laboratory is similar for both systems and is between 0.3 m and 0.6 m, with higher errors for low altitudes. The dynamic case is performed with a mobile robot travelling with an average speed of 0.5 m/s at a height of 0.3 m. In this case, low frequency error components are filtered out to focus the comparison on dynamic errors. Average dynamic errors are within 0.3–0.4 m for Pozyx and within 0.1–0.2 m for GoT. Results show an acceptable accuracy required for tracking people or objects and could serve as a guideline for the least achievable accuracy when applied for mobile robotics in conjunction with other elements of a robotic navigation stack.
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Bonnin-Pascual, Francisco, e Alberto Ortiz. "UWB-Based Self-Localization Strategies: A Novel ICP-Based Method and a Comparative Assessment for Noisy-Ranges-Prone Environments". Sensors 20, n. 19 (1 ottobre 2020): 5613. http://dx.doi.org/10.3390/s20195613.
Testo completoAbstract (sommario):
Ultra-Wide-Band (UWB) positioning systems are now a real option to estimate the position of generic agents (e.g., robots) within indoor/GPS-denied environments. However, these environments can comprise metallic structures or other elements which can negatively affect the signal transmission and hence the accuracy of UWB-based position estimations. Regarding this fact, this paper proposes a novel method based on point-to-sphere ICP (Iterative Closest Point) to determine the 3D position of a UWB tag. In order to improve the results in noise-prone environments, our method first selects the anchors’ subset which provides the position estimate with least uncertainty (i.e., largest agreement) in our approach. Furthermore, we propose a previous stage to filter the anchor-tag distances used as input of the ICP stage. We also consider the addition of a final step based on non-linear Kalman Filtering to improve the position estimates. Performance results for several configurations of our approach are reported in the experimental results section, including a comparison with the performance of other position-estimation algorithms based on trilateration. The experimental evaluation under laboratory conditions and inside the cargo hold of a vessel (i.e., a noise-prone scenario) proves the good performance of the ICP-based algorithm, as well as the effects induced by the prior and posterior filtering stages.
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Bian, Sizhen, Peter Hevesi, Leif Christensen e Paul Lukowicz. "Induced Magnetic Field-Based Indoor Positioning System for Underwater Environments". Sensors 21, n. 6 (22 marzo 2021): 2218. http://dx.doi.org/10.3390/s21062218.
Testo completoAbstract (sommario):
Autonomous underwater vehicles (AUV) are seen as an emerging technology for maritime exploration but are still restricted by the availability of short range, accurate positioning methods necessary, e.g., when docking remote assets. Typical techniques used for high-accuracy positioning in indoor use case scenarios, such as systems using ultra-wide band radio signals (UWB), cannot be applied for underwater positioning because of the quick absorption of the positioning medium caused by the water. Acoustic and optic solutions for underwater positioning also face known problems, such as the multi-path effects, high propagation delay (acoustics), and environmental dependency. This paper presents an oscillating magnetic field-based indoor and underwater positioning system. Unlike those radio wave-based positioning modalities, the magnetic approach generates a bubble-formed magnetic field that will not be deformed by the environmental variation because of the very similar permeability of water and air. The proposed system achieves an underwater positioning mean accuracy of 13.3 cm in 2D and 19.0 cm in 3D with the multi-lateration positioning method and concludes the potential of the magnetic field-based positioning technique for underwater applications. A similar accuracy was also achieved for various indoor environments that were used to test the influence of cluttered environment and of cross environment. The low cost and power consumption system is scalable for extensive coverage area and could plug-and-play without pre-calibration.
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Yuan, Debao, Jian Zhang, Jian Wang, Ximin Cui, Fei Liu e Yalei Zhang. "Robustly Adaptive EKF PDR/UWB Integrated Navigation Based on Additional Heading Constraint". Sensors 21, n. 13 (26 giugno 2021): 4390. http://dx.doi.org/10.3390/s21134390.
Testo completoAbstract (sommario):
At present, GNSS (Global Navigation Satellite System) positioning technology is widely used for outdoor positioning services because of its high-precision positioning characteristics. However, in indoor environments, effective position information cannot be provided, because of the signals being obscured. In order to improve the accuracy and continuity of indoor positioning systems, in this paper, we propose a PDR/UWB (Pedestrian Dead Reckoning and Ultra Wide Band) integrated navigation algorithm based on an adaptively robust EKF (Extended Kalman Filter) to address the problem of error accumulation in the PDR algorithm and gross errors in the location results of the UWB in non-line-of-sight scenarios. First, the basic principles of UWB and PDR location algorithms are given. Then, we propose a loose combination of the PDR and UWB algorithms by using the adaptively robust EKF. By using the robust factor to adjust the weight of the observation value to resist the influence of the gross error, and by adjusting the variance of the system adaptively according to the positioning scene, the algorithm can improve the robustness and heading factor of the PDR algorithm, which is constrained by indoor maps. Finally, the effectiveness of the algorithm is verified by the measured data. The experimental results showed that the algorithm can not only reduce the accumulation of PDR errors, but can also resist the influence of gross location errors under non-line-of-sight UWB scenarios.
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Castañeda-Miranda, Víctor H., Luis F. Luque-Vega, Emmanuel Lopez-Neri, Jesús Antonio Nava-Pintor, Héctor A. Guerrero-Osuna e Gerardo Ornelas-Vargas. "Two-Dimensional Cartesian Coordinate System Educational Toolkit: 2D-CACSET". Sensors 21, n. 18 (21 settembre 2021): 6304. http://dx.doi.org/10.3390/s21186304.
Testo completoAbstract (sommario):
Engineering education benefits from the application of modern technology, allowing students to learn essential Science, Technology, Engineering, and Mathematics (STEM) related concepts through hands-on experiences. Robotic kits have been used as an innovative tool in some educational fields, being readily accepted and adopted. However, most of the time, such kits’ knowledge level requires understanding basic concepts that are not always appropriate for the student. A critical concept in engineering is the Cartesian Coordinate System (CCS), an essential tool for every engineering, from graphing functions to data analysis in robotics and control applications and beyond. This paper presents the design and implementation of a novel Two-Dimensional Cartesian Coordinate System Educational Toolkit (2D-CACSET) to teach the two-dimensional representations as the first step to construct spatial thinking. This innovative educational toolkit is based on real-time location systems using Ultra-Wide Band technology. It comprises a workbench, four Anchors pinpointing X+, X−, Y+, Y− axes, seven Tags representing points in the plane, one listener connected to a PC collecting the position of the Tags, and a Graphical User Interface displaying these positions. The Educational Mechatronics Conceptual Framework (EMCF) enables constructing knowledge in concrete, graphic, and abstract levels. Hence, the students acquire this knowledge to apply it further down their career path. For this paper, three instructional designs were designed using the 2D-CACSET and the EMCF to learn about coordinate axes, quadrants, and a point in the CCS.
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Gabela, Jelena, Guenther Retscher, Salil Goel, Harris Perakis, Andrea Masiero, Charles Toth, Vassilis Gikas et al. "Experimental Evaluation of a UWB-Based Cooperative Positioning System for Pedestrians in GNSS-Denied Environment". Sensors 19, n. 23 (29 novembre 2019): 5274. http://dx.doi.org/10.3390/s19235274.
Testo completoAbstract (sommario):
Cooperative positioning (CP) utilises information sharing among multiple nodes to enable positioning in Global Navigation Satellite System (GNSS)-denied environments. This paper reports the performance of a CP system for pedestrians using Ultra-Wide Band (UWB) technology inGNSS-denied environments. This data set was collected as part of a benchmarking measurementcampaign carried out at the Ohio State University in October 2017. Pedestrians were equippedwith a variety of sensors, including two different UWB systems, on a specially designed helmetserving as a mobile multi-sensor platform for CP. Different users were walking in stop-and-go modealong trajectories with predefined checkpoints and under various challenging environments. Inthe developed CP network, both Peer-to-Infrastructure (P2I) and Peer-to-Peer (P2P) measurementsare used for positioning of the pedestrians. It is realised that the proposed system can achievedecimetre-level accuracies (on average, around 20 cm) in the complete absence of GNSS signals,provided that the measurements from infrastructure nodes are available and the network geometryis good. In the absence of these good conditions, the results show that the average accuracydegrades to meter level. Further, it is experimentally demonstrated that inclusion of P2P cooperativerange observations further enhances the positioning accuracy and, in extreme cases when only oneinfrastructure measurement is available, P2P CP may reduce positioning errors by up to 95%. Thecomplete test setup, the methodology for development, and data collection are discussed in thispaper. In the next version of this system, additional observations such as theWi-Fi, camera, and othersignals of opportunity will be included.
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Tong, Haibin, Ning Xin, Xianli Su, Tengfeng Chen e Jingjing Wu. "A Robust PDR/UWB Integrated Indoor Localization Approach for Pedestrians in Harsh Environments". Sensors 20, n. 1 (29 dicembre 2019): 193. http://dx.doi.org/10.3390/s20010193.
Testo completoAbstract (sommario):
Wireless sensor networks (WSNs) and the Internet of Things (IoT) have been widely used in industrial, construction, and other fields. In recent years, demands for pedestrian localization have been increasing rapidly. In most cases, these applications work in harsh indoor environments, which have posed many challenges in achieving high-precision localization. Ultra-wide band (UWB)-based localization systems and pedestrian dead reckoning (PDR) algorithms are popular. However, both have their own advantages and disadvantages, and both exhibit a poor performance in harsh environments. UWB-based localization algorithms can be seriously interfered by non-line-of-sight (NLoS) propagation, and PDR algorithms display a cumulative error. For ensuring the accuracy of indoor localization in harsh environments, a hybrid localization approach is proposed in this paper. Firstly, UWB signals cannot penetrate obstacles in most cases, and traditional algorithms for improving the accuracy by NLoS identification and mitigation cannot work in this situation. Therefore, in this study, we focus on integrating a PDR and UWB-based localization algorithm according to the UWB communication status. Secondly, we propose an adaptive PDR algorithm. UWB technology can provide high-precision location results in line-of-sight (LoS) propagation. Based on these, we can train the parameters of the PDR algorithm for every pedestrian, to improve the accuracy. Finally, we implement this hybrid localization approach in a hardware platform and experiment with it in an environment similar to industry or construction. The experimental results show a better accuracy than traditional UWB and PDR approaches in harsh environments.
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Lv, Hao, Teng Jiao, Yang Zhang, Fulai Liang, Fugui Qi e Jianqi Wang. "A Novel Method for Breath Detection via Stepped-Frequency Continuous Wave Ultra-Wideband (SFCW UWB) Radars Based on Operational Bandwidth Segmentation". Sensors 18, n. 11 (10 novembre 2018): 3873. http://dx.doi.org/10.3390/s18113873.
Testo completoAbstract (sommario):
Human being detection via ultra-wideband (UWB) radars has shown great prospects in many areas, such as biomedicine, military operation, public security, emergency rescue, and so on. When a person stays stationary, the main feature that separates him/her from surroundings is the movement of chest wall due to breath. There have been many algorithms developed for breath detection while using UWB radars. However, those algorithms were almost based on a basic scheme that focused on processing in the time dimension of UWB data. They did not utilize the benefits from the wide operational bandwidth of UWB radars to show potential superiority over those narrowband systems such as a continuous wave (CW) Doppler radar. In this paper, a breath detection method was proposed based on operational bandwidth segmentation. A basic theoretical model was firstly introduced, indicating that characteristics of breath signals contained in UWB echoes were consistent among the operational frequencies, while those of clutters were not. So, the method divided a set of UWB echo data into a number of subsets, each of which corresponded to a sub-band within the operational bandwidth of the UWB radar. Thus information about the operational frequency is provided for subsequent processing. With the aid of the information, a breath enhancement algorithm was developed mainly by averaging the segmented UWB data along the operational frequency. The algorithm’s performance was verified by data measured by a stepped-frequency CW (SFCW) UWB radar. The experimental results showed that the algorithm performed better than that without the segmentation. They also showed its feasibility for fast detection of breath based on a short duration of data. Moreover, the method’s potential for target identification and impulse-radio (IR) UWB radar was investigated. In summary, the method provides a new processing scheme for UWB radars when they are used for breath detection. With this scheme, the UWB radars have a benefit of greater flexibility in data processing over those narrowband radars, and thus will perform more effectively and efficiently in practical applications.
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Packiaraj, D., M. Ramesh e A. T. Kalghatgi. "Ultra wide band filter with wide stop band". Microwave and Optical Technology Letters 49, n. 2 (2006): 436–39. http://dx.doi.org/10.1002/mop.22166.
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Packiaraj, D., K. J. Vinoy, M. Ramesh, A. T. Kalghatgi, Varsha Chaware e G. J. Phatak. "LTCC ultra wide band filter". Microwave and Optical Technology Letters 53, n. 11 (19 agosto 2011): 2580–83. http://dx.doi.org/10.1002/mop.26311.
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Baqué, Rémi, Luc Vignaud, Valentine Wasik, Nicolas Castet, Reinhold Herschel, Harun Cetinkaya e Thomas Brandes. "MIC: Microwave Imaging Curtain for Dynamic and Automatic Detection of Weapons and Explosive Belts". Sensors 23, n. 23 (30 novembre 2023): 9531. http://dx.doi.org/10.3390/s23239531.
Testo completoAbstract (sommario):
DEXTER (detection of explosives and firearms to counter terrorism) is a project funded by NATO’s Science for Peace and Security (SPS) program with the goal of developing an integrated system capable of remotely and accurately detecting explosives and firearms in public places without impeding the flow of pedestrians. While body scanner systems in secure areas of public places are becoming more and more efficient, the attack at Brussels airport on 22 March 2016, upstream of these systems, in the middle of the crowd of passengers, demonstrated the lack of discreet and real-time security against threats of mass terrorism. The NATO-SPS international and multi-year DEXTER project aims to provide new technical and strategic solutions to fill this gap. This project is based on multi-sensor coordination and fusion, from hyperspectral remote laser to smart glasses, artificial algorithms, and suspect identification and tracking. One of these sensors is dedicated to threat detection (large weapon or explosive belt) using the clothing of pedestrians by means of an active microwave component. This project is referred to as MIC (Microwave Imaging Curtain), also supported by the French SGDSN (General Secretariat of Defense and National Security), and utilizes a radar system capable of generating 3D images in real-time to address non-checkpoint detection of explosives and firearms. The project, led by ONERA (France), is based on a radar imaging system developed by the Fraunhofer FHR institute, using a MIMO architecture with an Ultra-Wide Band waveform. Although high-resolution 3D microwave imaging is already being used in expensive body scanners to detect firearms concealed under clothing, MIC’s innovative approach lies in utilizing a high-resolution 3D imaging device that can detect larger dangerous objects carried by moving individuals at a longer range, in addition to providing discrete detection in pedestrian flow. Automatic detection and classification of these dangerous objects is carried out on 3D radar images using a deep-learning network. This paper will outline the project’s objectives and constraints, as well as the design, architecture, and performance of the final system. Additionally, it will present real-time imaging results obtained during a live demonstration in a relevant environment.
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Kaiser, T., Feng Zheng e E. Dimitrov. "An Overview of Ultra-Wide-Band Systems With MIMO". Proceedings of the IEEE 97, n. 2 (febbraio 2009): 285–312. http://dx.doi.org/10.1109/jproc.2008.2008784.
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kumar, V. Gajendra, T. Krishnamoorthy, B. S. Ganesh, U. V. Pavani e D. S. L. Prasanna. "Novel Compact Dual Band Notched Ultra Wide Band Print-ed Antenna". International Journal of Innovative Research in Engineering and Management 8, n. 4 (21 luglio 2021): 61–66. http://dx.doi.org/10.55524/ijirem.2021.8.4.10.
Testo completoAbstract (sommario):
Wireless technology is one of the main areas of research in the world of communication systems today and a study of communication systems is incomplete without an understanding of the operation and fabrication of antennas. A simple and compact printed ultra-wideband antenna with dual-band-notched characteristics is presented. The proposed antenna is composed of a rectangular patch and a modified ground plane. The rectangular patch is etched onto a lossy FR4 substrate. A circular ring strip parasitizes the rectangular patch embedded by a U-shaped slot. Two Inverted-L slits and a rectangular slit are embedded onto the ground plane. Some bandwidth enhancement and band notched techniques are applied in the antenna structure for broadening the bandwidth and generating notches. The simulated and measured results show that the proposed antenna offers a very wider bandwidth ranging from 3.04 to 17.30 GHz, defined by the return loss less than −10 dB, with dual-notched bands of 3.30–4.20 and 5.10–5.85 GHz covering the 3.3/3.7 GHz WiMAX, 3.7/4.2 GHz C-band, and 5.2/5.8 GHz wireless local area network systems.
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Noghanian, S., e M. K. Jung. "Ultra Wide Band Planar Slot Antenna". Journal of Electromagnetic Waves and Applications 22, n. 8-9 (gennaio 2008): 1299–308. http://dx.doi.org/10.1163/156939308784158869.
Testo completo