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To improve the received signal strength beams are formed by multi-element arrays. These beams are focused on the direction of arriving signals, with an intention of maximizing the received signal power. The signals with noise and interference arrived from a distinct direction will be estimated by Uniform Linear Array (ULA) with 10 antenna elements. The earlier signal will be phase-shifted with the help of phase shift beamformer. The Coordinate Rotation Digital Computer (CORDIC) algorithm is used compute the vector angle in signal cluster. The CORDIC algorithm is employed determint the phase shift and frequency offset. The beamformer assumes that incoming signal are narrow banded, a phase shift can estimate the required delay and preserve the incoming signal strength. The beamformer circuit is designed in Xilinx Vivado for simulation and synthesized using both Virtex-7 device and their results are compared with exisiting methods, which is evidence that the proposed design is formidable pertaining to power and delay. This design can operate at 100 MHZ with total on-chip power consumption of 725 mW. [ABSTRACT FROM AUTHOR]

The use of red fluorescent powder derived from nitrides and oxides in warm white LEDs is a pressing concern due to its lower quantum efficiency. Fluoride red phosphors activated by Mn4+ ions show promising potential for application in white light-emitting diodes (LEDs) due to their distinctive narrowband red emission and broad blue excitation, along with the relatively mild synthesis conditions required. However, the quantum efficiency of early Mn4+-doped fluoride phosphors was not optimal, highlighting the importance of identifying a suitable preparation method and matrix. Here, we introduce an efficient and thermally stable red fluoride phosphor, Cs 2 SiF 6 :Mn4+, which demonstrates a remarkable quantum efficiency of 98.32 % achieved through ion exchange techniques. However, even at a temperature of 423 K, the luminous intensity still maintained at 95 % of that under room temperature conditions. By incorporating Cs 2 SiF 6 :Mn4+ as a red emitter, a stable 10 W high-power warm white LEDs with a luminous efficiency of approximately 126.1 lm/W can be realized. These findings underscore the significant potential of the red phosphor Cs 2 SiF 6 :Mn4+ in advancing high-performance, high-power warm white LEDs. [ABSTRACT FROM AUTHOR]

Integrated computational spectrometers with gate‐tunable nano heterostructures and reconstruction algorithms are attractive for on‐chip gas‐sensing spectrometers and have enabled versatile spectrum detectors. However, they require the selective and optical filtering capabilities of wavelengths, restricting their efficient implementation in narrow‐band photodetection. In this study, a printable spectral phototransistor is developed with high dynamic detectivity (1012 Jones and 105 Hz at −3 db bandwidth) modulated by a GeS2 nanosheet heterostructure at short‐wave infrared (SWIR) regime. Using the transport mode switching of carriers in a heterostructure and the polarization‐sensitivity of the GeS2 two‐dimension (2‐D) nanosheet, this SWIR spectral phototransistor demonstrates an accurate narrow‐band selective (96.7% accuracy) spectrum detector and performed a deep‐learning analysis of an artificial neural network (ANN). Furthermore, this GeS2 2‐D based spectral phototransistor, characterized by its high in‐plane anisotropy and electrically reconfigurable properties, extends the applicability of narrow‐band photodetection with 15 nm Full Width at Half Maximum (FWHM) to the recognition of trace‐gases at the parts per billion (ppb) level. [ABSTRACT FROM AUTHOR]

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This work addresses the design of sub-terahertz narrow-band resonators for high performance and low-cost manufacturability. The intended application for these resonators is to realize narrow-band filters for passive millimeter-wave sounding of upper atmospheric humidity using the 380 GHz water vapor absorption line. Various narrow-band resonator designs and manufacturing processes were considered for this application. A design based on a waveguide split-ring resonator topology was selected to be developed and manufactured using laser machining. Experimental results are presented and compared with results from simulations for ten narrow-band resonators fabricated with a design center frequency in the WR-2.2 (325–500 GHz) waveguide band. [ABSTRACT FROM AUTHOR]

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Powerline communication is gaining momentum with the rise of the smart grid, the Internet of Things as part of the 4th industrial revolution and associated applications such as transportation and energy efficiency. Coupling and channel characterization are essential parts of a power-line communication system. Therefore, understanding these components allows performance evaluation and prediction of the system. This paper presents an entire review of couplers and channel characterization modeling techniques used in narrow and broadband power-line communication systems. Types and applications of different couplers are presented; a review of different power-line communication channel modeling techniques and the fundamentals allows a clear understanding of factors influencing or affecting the signal propagation through the channel. The purpose of this review is to guide researchers and system designers looking for literature resources on couplers and channel characterization for power-line communication applications.

The challenge of obtaining transmission spectra with both a wider tunable spectral range and high resolution persists. In this paper, a novel all-dielectric transmissive grating structure based on Mie resonance is proposed. The structure excites the Mie resonance by embedding a high refractive index contrast grating in a KF-Si film system band-stop filter. The dipole resonance energy is confined within the high refractive index silicon grating material, expanding the cutoff bandwidth of the KF-Si film system to over 400 nm and achieving single-peak transmission in the visible range. And the continuous transmission spectrum has an adjustable range of 300 nm with the highest spectral resolution (FWHM) (∼20 nm) can be achieved by adjusting the grating period. To suppress the coupling energy excitation between the higher-order magnetic dipole and the substrate, a silicon-rich nitride (SRN) matching layer is introduced between the KF-Si film system and the substrate. This layer enhances the intensity of the resonance peaks while simultaneously suppressing the short-wavelength sidebands, thereby improving the saturation and purity of the spectrum. In addition, we obtained a large angular tolerance of up to 15° by stacking the silicon film system. This work is of great significance for the advancement of hyperspectral imaging and display technology. • All-dielectric transmissive filter structure based on Mie resonance is proposed. • This structure simultaneously exhibits a cutoff bandwidth of 400 nm, a tunable range of 300 nm, and a resolution of 20 nm. • The incorporation of a matching layer effectively suppresses the sidebands while enhances the transmittance at the central wavelength. • This structure exhibits a large angular tolerance of up to 15°. [ABSTRACT FROM AUTHOR]

Developing efficient and stable narrow-band blue phosphors has always been crucial for advancing LED backlighting technology. In this study, a host of Na 3 Ca 2 TaO 6 with a strong rigid structure and high cationic site symmetry was selected, while Bi3+ was utilized as the activator. A novel narrow-band blue-emitting phosphor Na 3 Ca 2 TaO 6 :Bi3+ was obtained through high temperature solid phase sintering. The excitation peak of Na 3 Ca 2 TaO 6 :0.005Bi3+ is at 370 nm, which can effectively match the near-ultraviolet chip. Under near-ultraviolet light excitation, the Na 3 Ca 2 TaO 6 :0.005Bi3+ sample exhibits narrow-band blue emission, characterized by a dominant peak at 421 nm and a full width at half maximum of 47 nm. Additionally, Na 3 Ca 2 TaO 6 :Bi3+ demonstrates the color purity of 93.7 %, a quantum efficiency of 56.3 % and thermal stability of 80 %@150 °C. Based on crystal structure data, spectral data, and empirical formulas, it can be inferred that Bi3+ occupies the Na2 and Ca site and forms two luminous centers in Na 3 Ca 2 TaO 6. When Na 3 Ca 2 TaO 6 :Bi3+ is utilized as the blue light component in WLED devices packaging, an impressive NTSC color gamut of 89.4 % can be achieved. The present study is anticipated to serve as a valuable point of reference for the future advancement of phosphors specifically tailored for backlight display applications. • Na 3 Ca 2 TaO 6 :0.005Bi3+ exhibits narrow-band blue emission with a dominant peak at 421 nm and a FWHM of 47 nm. • Na 3 Ca 2 TaO 6 :Bi3+ demonstrates a color purity of 93.7 %, quantum efficiency of 56.3 % and thermal stability of 80 %@150 °C. • The utilization of Na 3 Ca 2 TaO 6 :Bi3+ as the blue light component achieves an NTSC color gamut of 89.4 %. [ABSTRACT FROM AUTHOR]

Nowadays, there is a trend to employ adaptive solutions in mobile communication. The adaptive transmission systems seem to answer the need for highly reliable communication that serves high data rates. For efficient adaptive transmission, the future Channel State Information (CSI) has to be known. The various prediction methods can be applied to estimate the future CSI. However, each method has its bottlenecks. The task is even more challenging while considering the future 5G/6G communication where the employment of sub-6 GHz and millimetre waves (mmWaves) in narrow-band, wide-band and ultra-wide-band transmission is considered. Thus, author describes the differences between sub-6 GHz/mmWave and narrow-band/wide-band/ultrawide- band channel prediction, provide a comprehensive overview of available prediction methods, discuss its performance and analyse the opportunity to use them in sub-6 GHz and mmWave systems. We select Long Short-Term Memory Recurrent Neural Network (RNN) as the most promising technique for future CSI prediction and propose optimising two of its parameters - the number of input features, which was not yet considered as an opportunity to improve the performance of CSI prediction, and the number of hidden layers.

Carbonyl‐containing derivatives show enduring vitality in the field of thermally activated delayed fluorescence (TADF) materials; they can realize high device efficiency by using both singlet and triplet excitons for electroluminescence. Recently, a system based on fused ketone/amine exhibited huge potential for constructing multi‐resonance TADF (MR‐TADF) emitters, which exhibit higher narrow‐band emission than conventional TADF emitters with twisted donor‐acceptor (D‐A) structure. Herein, we summarize current research progress in both traditional and MR‐type ketone derivatives with TADF characteristics for introducing the molecular design strategy of maintaining high device efficiency while keeping narrow‐band emission profile. We hope this review can inspire the emergence of more high‐performance narrow‐band materials. [ABSTRACT FROM AUTHOR]

Nowadays, phosphors are widely used in high quality white light emitting diodes (W‐LEDs) and display technology. Micro light emitting diode (Micro‐LED) has the advantages of ultrahigh resolution color saturation, while ordinary phosphors are difficult to apply due to their large particle size. As is known to all, once the phosphor particle size is reduced, its luminescence intensity will loser. This paper presents a strategy to improve the luminescence intensity of sub‐micrometer narrow‐band red phosphors. By increasing the doping concentration of rare‐earth ions through total substitution and reducing the nonradiative transition in the cell, ultrahigh concentration doping of sub‐micrometer phosphors is achieved to improve the luminescence intensity. Surprisingly, with increasing Eu3+ up to entirely substitution for Gd3+ site, both the absorption efficiency and the internal quantum efficiency of the sample increased greatly. The external quantum efficiency increased from 5.42% to 19.70%. Sub‐micrometer EuAl3(BO3)4 exhibits ultrahigh thermal stability, with a luminous intensity at 225 °C that is 128% of that at room temperature, meeting the conditions of extreme high‐temperature environments or high‐power LEDs. In summary, this work has great potential for application in W‐LED and presents a solution idea to solve the luminous intensity reduction of sub‐micrometer phosphors. [ABSTRACT FROM AUTHOR]

A near-perfect narrow-band graphene-based absorber was fabricated using a resonant system integrated with an asymmetric meta-grating at a wavelength of 1550 nm. By optimizing the gap between the two grating strips, the absorption of monolayer graphene can be increased to 99.6% owing to the strong field confinement of the bottom zero-contrast grating (ZCG). The position of the absorption spectrum could be adjusted by tailoring the grating period or the thickness of the waveguide layer. Interestingly, absorption spectrum linewidth can be tailored by changing the thickness of the spacer layer. The accidental bound states in the continuum (BICs) are then demonstrated in the structure. Moreover, the designed structure realizes the dynamic adjustment of the absorption efficiency at a specific wavelength, which has excellent potential in integrated optical devices and systems. [ABSTRACT FROM AUTHOR]

The underwater photoelectric detection equipment mainly uses 532 nm laser as the light source, but the corresponding photocathodes like Na2KSbCs, GaAs and GaAsP have a wide spectral response region and are easily affected by other signals. Thereby, GaAlAs are materials worth developing because of their adjustable band gap, which usually is used as a window layer of GaAs-based photocathode. In this paper, the finite difference time domain (FDTD) method is used to carry out nanostructure design simulations. The results show that GaAlAs with Al component of 0.63 can obtain the cutoff wavelength near 532 nm, which is an excellent photocathode material to meet the requirement of narrow-band spectral response of 532 nm laser. Furthermore, the light absorptance can be improved effectively by the quadrangular prism or cylinder nanostructured array prepared on the Ga 0. 3 7 Al 0. 6 3 As emission layer surface, and the maximum light absorptance can reach 96.2% at 532 nm for the cylinder nanostructure array with a height of 900 nm and a base width of 100 nm. Nevertheless, the reflection-mode Ga 0. 3 7 Al 0. 6 3 As photocathode with the quadrangular prism nanostructured array can be slightly influenced with incident angle of light. [ABSTRACT FROM AUTHOR]

In this work, a photo-excited terahertz metamaterial absorber (PETMA) switched between single-band and narrow-band absorption is reported. Such an absorber includes three layers, which are a metal plate on the bottom, a dielectric layer, and a top unit attached to the dielectric substrate. The upper unit of the proposed PETMA is composed of an innermost ring-shaped and a middle truncated ring-shaped high-impedance surfaces (HISs), a nested split ring-shaped resonator connected with an outer square ring-shaped metal resonator. It is noted that four corners of the square ring-shaped metallic resonator are embedded in photoconducting semiconductors (silicon), respectively. Furthermore, the quadrate air columns (ACs) are inserted in the dielectric substrate to promote the absorption effect of this absorber. The single-band (at 1.16 THz) and the narrow-band absorption (at 1.458–1.538 THz) conversion can be realized through the variation of the conductivity of silicon tuned by an optical pump beam. Besides, the absorption principle of the devised PETMA is analyzed by describing the surface currents, the electric field diagrams, the magnetic field distributions, and the power flow distributions. In addition, the simulations show that the proposed PETMA exhibits stable absorption performance at a wider incident angle.

As the widespread application of white light-emitting diodes (WLEDs) in lighting field and liquid crystal display (LCD) backlight, the development of phosphors toward multifunctional applications is considered to be an inevitable tendency. In this work, multi-color light emissions have been realized in Eu2+ and Mn2+-activated magnetoplumbite-type GdMgAl 11 O 19 (GMAO) along with adjustable photoluminescence properties. Significantly, a promising narrow-band green light emission can be achieved by Mn2+-activated GMAO with the full width at half maximum (FWHM) of 27 nm, and such narrow emission band makes the as-prepared WLED device reach 121 % of National Television Standards Committee (NTSC), which can act as an ideal LCD backlight. On the other hand, the broad cyan light can be achieved in Eu2+-activated GMAO. Moreover, multi-color light emissions have been realized in Eu2+ and Mn2+ co-doped GMAO, and the energy transfer from Eu2+ to Mn2+ ions was established. Benefitting from the broad band cyan light emission of Eu2+ ion, a promising WLED device with high color rendering index (CRI) of 90 has been fabricated by using Eu2+ and Mn2+ co-doped sample. The result indicates the multifunctional applications of the GMAO modulated by Eu2+ and Mn2+ activators. A novel multi-color light emissions phosphor of GdMgAl 11 O 19 : Eu2+, Mn2+ with multifunctional applications has been successfully synthesized. [Display omitted] • Multi-color light emissions have achieved in Eu2+ and Mn2+-activated GdMgAl 11 O 19. • GdMgAl 11 O 19 : Mn2+ emits a narrow-band green light with FWHM of 27 nm. • The color gamut of as-prepared WLED device reach 121 % of National Television Standards Committee. • GdMgAl 11 O 19 : Mn2+ performs good thermal stability. [ABSTRACT FROM AUTHOR]

Powerline communication is gaining momentum with the rise of the smart grid, the Internet of Things as part of the 4th industrial revolution and associated applications such as transportation and energy efficiency. Coupling and channel characterization are essential parts of a power-line communication system. Therefore, understanding these components allows performance evaluation and prediction of the system. This paper presents an entire review of couplers and channel characterization modeling techniques used in narrow and broadband power-line communication systems. Types and applications of different couplers are presented; a review of different power-line communication channel modeling techniques and the fundamentals allows a clear understanding of factors influencing or affecting the signal propagation through the channel. The purpose of this review is to guide researchers and system designers looking for literature resources on couplers and channel characterization for power-line communication applications. [ABSTRACT FROM AUTHOR]

We designed and fabricated narrow-band UV-B AlGaN p-i-n photodiodes (PDs) with a full-width at half-maximum (FWHM) of 8 nm by optimizing the Al composition and thickness of the AlGaN layers. To improve the photoelectric response of the narrow-band PDs, a polarization electric field with the same direction with the applied bias field was introduced to the absorption layer by adjusting the Al composition ratio between the p-type AlGaN layer and i-type AlGaN absorption layer. The polarization enhanced narrow-band PD exhibited a higher external quantum efficiency (EQE) of 82% than the conventional one with an EQE of 67%. Meanwhile, a low dark current density of 1.7 nA/cm2 and four orders of magnitude UV-visible rejection ratio were achieved for the enhanced narrow-band PDs with a maximum photocurrent responsivity of 202 mA/W at 304 nm.

Incorporation of compact spectroscopic near‐infrared (NIR) light detectors into various wearable and handheld devices opens up new applications, such as on‐the‐spot medical diagnostics. To extend beyond the detection window of silicon, i.e., past 1000 nm, organic semiconductors are highly attractive because of their tunable absorption. In particular, organic NIR wavelength‐selective detectors have been realized by incorporating donor:acceptor thin films, exhibiting weak intermolecular charge‐transfer (CT) absorption, into an optical microcavity architecture. In this work, the alkyl side chains of the well‐known PBTTT donor polymer are replaced by alkoxy substituents, hereby redshifting the CT absorption of the polymer:PC61BM blend. It is shown that the unique fullerene intercalation features of the PBTTT polymer are retained when half of the side chains are altered, hereby maximizing the polymer:fullerene interfacial area and thus the CT absorption strength. This is exploited to extend the detection range of organic narrow‐band photodetectors with a full‐width‐at‐half‐maximum of 30–38 nm to wavelengths between 840 and 1340 nm, yielding detectivities in the range of 5 × 1011 to 1.75 × 1010 Jones, despite the low CT state energy of 0.98 eV. The broad wavelength tuning range achieved using a single polymer:fullerene blend renders this system an ideal candidate for miniature NIR spectrophotometers. [ABSTRACT FROM AUTHOR]

Nowadays, there is a trend to employ adaptive solutions in mobile communication. The adaptive transmission systems seem to answer the need for highly reliable communication that serves high data rates. For efficient adaptive transmission, the future Channel State Information (CSI) has to be known. The various prediction methods can be applied to estimate the future CSI. However, each method has its bottlenecks. The task is even more challenging while considering the future 5G/6G communication where the employment of sub-6 GHz and millimetre waves (mmWaves) in narrow-band, wide-band and ultra-wide-band transmission is considered. Thus, author describes the differences between sub-6 GHz/mmWave and narrow-band/wide-band/ultrawide- band channel prediction, provide a comprehensive overview of available prediction methods, discuss its performance and analyse the opportunity to use them in sub-6 GHz and mmWave systems. We select Long Short-Term Memory Recurrent Neural Network (RNN) as the most promising technique for future CSI prediction and propose optimising two of its parameters - the number of input features, which was not yet considered as an opportunity to improve the performance of CSI prediction, and the number of hidden layers. [ABSTRACT FROM AUTHOR]

Herein, a novel Bi3+‐activated Ca3Y2Ge3O12 (CYGO) narrow‐band cyan‐emitting phosphor was synthesized. It can be excited from 320–420 nm, and the strongest excitation peak is located at 370 nm, which is suitable for current near‐ultraviolet (NUV) chips perfectly. The full width at half maximum is at 52 nm. By analyzing the crystal structure of the sample, we infer that the Bi3+ ions replace the Y3+ site to form a highly symmetrical BiO6 octahedron. The time‐resolved photoluminescence (TRPL) spectra of CYGO: Bi3+ reveal that the only a single emission center exists in the host lattice. A warm white light–emitting diode (WLED) device with a low correlated color temperature (3148 K) and a high color rendering index (90.2) was fabricated by using the as‐prepared sample, and the significant thermal stability of CYGO: Bi3+ guarantees its potential application in WLEDs. It is verified that the structure with only one crystallographic Y site for Bi3+ dopant occupation and highly symmetrical and dense structure is conducive to realize narrow‐band emission, which will provide experience for researchers to explore more Bi3+‐activated phosphors used for high‐end lighting. [ABSTRACT FROM AUTHOR]

A near-perfect narrow-band graphene-based absorber was fabricated using a resonant system integrated with an asymmetric meta-grating at a wavelength of 1550 nm. By optimizing the gap between the two grating strips, the absorption of monolayer graphene can be increased to 99.6% owing to the strong field confinement of the bottom zero-contrast grating (ZCG). The position of the absorption spectrum could be adjusted by tailoring the grating period or the thickness of the waveguide layer. Interestingly, absorption spectrum linewidth can be tailored by changing the thickness of the spacer layer. The accidental bound states in the continuum (BICs) are then demonstrated in the structure. Moreover, the designed structure realizes the dynamic adjustment of the absorption efficiency at a specific wavelength, which has excellent potential in integrated optical devices and systems.

A simple scheme for the realization of the terahertz (THz) fundamental-mode tunable closed-stopband composite right/left-handed leaky-wave antennas (CRLH LWAs) is presented. The proposed CRLH LWAs are reconstructed by graphene-based coplanar waveguide (CPW) transmission line supercells. Their shunt inductances achieved by narrow graphene strips of two unit cell structures are halved. The CRLH LWAs are designed and confirmed by numerical simulations. They also exhibit frequency-scanning behaviors at THz with narrower bandwidth than that of the conventional graphene-based fundamental-mode CPW unit cell CRLH LWAs at THz. Besides, the LWAs also exhibit strong tunable characteristics and achieve the closed-stopband condition more effectively. Therefore, the proposed supercell CRLH LWAs could further improve the performance of the beam-steering antennas at THz. [ABSTRACT FROM AUTHOR]

A narrow-band metasurface absorber (MSA) based on InSb micro-cylinder arrays has been proposed and investigated numerically, which could be believed to be applicable for both temperature and refractive index (RI) sensing in terahertz (THz) region. Distinct from previous designs, the proposed narrow-band MSA is only consisted of a sub-wavelength periodic micro-cylinder array based on the InSb material possessing an extremely thermosensitive relative permittivity which varies with the external environment temperature, and a gold ground-plane deposited on a glass substrate. Numerical simulation results indicate that the proposed MSA can achieve an absorbance of 99.9% at 1.8985 THz and the corresponding Q-factor is about 120.9 at room temperature (300 K). It is inferred that the narrow-band perfect absorption of the MSA could be contributed to the surface plasmon polariton (SPP) resonance mode excitation. Furthermore, the absorption property of the designed MSA is found to be highly sensitive to the RI value variations of the surrounding mediums and fluctuations of external environment temperature. Thus, the proposed MSA can be not only operated as a temperature sensor with a sensitivity of 2.13 GHz/K, but also a RI sensor with a sensitivity of 960 GHz/RIU (refractive index unit). Due to its high sensing performance, it can be believed that the narrow-band MSA has great potential applications in chemical, biological or other optoelectronic related areas.

Relying on the demands of Internet of things application,a detailed review on the status quo of LEO (low earth orbit) satellite communication system was given,and the components of communication system were compared and explained separately.Afterwards,the characteristics of the NB-IoT land-based communication network widely applied at present and existing LEO satellite communication system were compared,and a feasible design scheme for IoT-oriented LEO satellite system was provided,and its main parameters and characteristics were briefly described.

Multispectral imaging systems using narrow-band power LEDs have become a feasible solution for a wide range of applications. Their fast response and simple implementation compensate for a low spectral resolution. In this article, we are filling a gap identified in the literature on multispectral systems by presenting a detailed design of a light controller, as well as a characterization of the whole system by means of a correlation and a repeatability analysis. We use a reference color target to assess accuracy and precision by comparing our system with high-performance hyperspectral equipment used in fruit quality control. The system captures multispectral images (MSIs) with 15 different wavelengths ($\lambda \in [410~950$ ] nm). The main finding is a Pearson correlation index above 80% ($\rho > 0.8$) with a variance in the measure within 10% ($\sigma ^{2} < 0.1$). We also examine the characteristics of the instrument at a maximum speed of 8 MSIs/s although this entails sacrificing precision ($\sigma ^{2} < 0.3$). [ABSTRACT FROM AUTHOR]

In this paper, a narrow‐band circularly polarized (CP) microstrip leaky‐wave antenna (LWA) with open stopband suppressed is proposed. Coupled meandered slow‐wave lines are adopted to realize narrow‐band beam scanning. The asymmetric elements are employed as radiators to realize CP and zero‐crossing scanning. We modulated the antenna by loading the ground inductance and asymmetric capacitors on the meandered slow‐wave transmission line. The antenna consists of ten asymmetrical structural elements connected by coupling, the antenna size of L × W is 170 mm × 25 mm. In the operating band of 8.1 to 8.5 GHz, the measured scanning angel of the fabricated antenna is from −31°to +6°. The antenna axial ratios (ARs) are all below 3 dB at the corresponding beam directions. The gain is above 9.1 dBi and the relative bandwidth is only 4.8%. In the operating band, the radiation efficiency is above 60%. It has potential applications in radar detection and wireless communication systems for its simple and low‐profile structure with CP, beam‐scanning, and narrow‐band performance. [ABSTRACT FROM AUTHOR]

We designed and fabricated narrow-band UV-B AlGaN p-i-n photodiodes (PDs) with a full-width at half-maximum (FWHM) of 8 nm by optimizing the Al composition and thickness of the AlGaN layers. To improve the photoelectric response of the narrow-band PDs, a polarization electric field with the same direction with the applied bias field was introduced to the absorption layer by adjusting the Al composition ratio between the p-type AlGaN layer and i-type AlGaN absorption layer. The polarization enhanced narrow-band PD exhibited a higher external quantum efficiency (EQE) of 82% than the conventional one with an EQE of 67%. Meanwhile, a low dark current density of 1.7 nA/cm2 and four orders of magnitude UV-visible rejection ratio were achieved for the enhanced narrow-band PDs with a maximum photocurrent responsivity of 202 mA/W at 304 nm. [ABSTRACT FROM AUTHOR]

In this work, 2‐element slot‐based frequency reconfigurable (FR) multiple‐input‐multiple‐output (MIMO) antenna design antenna with a very wide‐sweep is proposed for dynamic spectrum sharing (DSS) in 5G technologies. FR is achieved using varactor diode with frequency tuning range from 1655 to 2605 MHz. The design is a low profile with planar structure having a single element footprint of 19.5 × 20 mm2. The two slot antenna elements of the MIMO configuration are etched out from a ground (GND) plane of dimensions of 60 × 120 mm2. The proposed antenna is narrow‐band and hence it is suitable for RF front‐end in the 5G‐enabled DSS in cognitive radio (CR) applications. [ABSTRACT FROM AUTHOR]

Mn4+‐activated fluoride red‐emitting narrow‐band phosphors have been successfully used in wide color‐gamut white LEDs for liquid crystal display (LCD) backlights. However, highly concentrated and toxic HF is usually used in their synthesis, causing environment and safety issues. In this work, we proposed a HF‐free green method, that is, using NH4F/HCl instead of HF, to synthesize a series of A2XF6:Mn4+ (A = K, Na, Rb, Cs; X = Si, Ge, Ti) phosphors. The microstructure, photoluminescence (PL) properties, thermal quenching, and applications of the synthesized phosphors were investigated. Using the proposed approach, the phosphors generally showed a pure phase, a particle size ranging from 5 to 45 μm, and some characteristic sharp emission lines of Mn4+ in the red spectral range. The internal quantum efficiency was varied in a broad range of 69%‐94% under the 460 nm excitation, depending on the composition of the fluoride host. Among these compositions, K2XF6:Mn4+ (X = Ge and Ti) phosphors even had a similar external quantum efficiency (>60%) with commercial ones. By combining K2GeF6:Mn4+ (narrow‐band red) and β‐sialon:Eu2+ (narrow‐band green) with a blue LED, a white light‐emitting diode (wLED) backlight with a color gamut of 87.7% National Television System Committee Standard, color temperature of 8423 K, and a luminous efficacy of 110.8 lm/W was demonstrated. These results indicate that the synthetic method proposed in this work is universal for preparing highly efficient fluoride phosphors used in wLEDs. [ABSTRACT FROM AUTHOR]

The amplitude-phase error caused by the channel inconsistency in the actual digital array radar and the mutual coupling error caused by the mutual coupling effect have a great influence on the performance of the array. This study analyses and models the error characteristics of amplitude-phase error and mutual-coupling error, respectively. Based on the narrow-band and wide-band array received signal models, the spatial signal arrival angle estimation accuracy and the beam-synthesising pattern are used as indicators to analyse the influence of errors on the array. Channel inconsistency and mutual coupling will cause the estimated signal arrival angle to deviate from the true signal direction and the spatial spectrum curve peak will become gentle. In addition, the beam pattern's sidelobe will raise, null orientation will deviate from the interference signal direction, and gain will raise.

The amplitude-phase error caused by the channel inconsistency in the actual digital array radar and the mutual coupling error caused by the mutual coupling effect have a great influence on the performance of the array. This study analyses and models the error characteristics of amplitude-phase error and mutual-coupling error, respectively. Based on the narrow-band and wide-band array received signal models, the spatial signal arrival angle estimation accuracy and the beam-synthesising pattern are used as indicators to analyse the influence of errors on the array. Channel inconsistency and mutual coupling will cause the estimated signal arrival angle to deviate from the true signal direction and the spatial spectrum curve peak will become gentle. In addition, the beam pattern's sidelobe will raise, null orientation will deviate from the interference signal direction, and gain will raise. [ABSTRACT FROM AUTHOR]

Graphical abstract A novel rare-earth free narrow-band green-emitting Mn2+ doped ZnB 2 O 4 phosphor was synthesized. The phosphor can be excited by blue light and emit bright green light. Besides, the phosphor also performs outstanding thermal stability and excellent cathodoluminescence properties. Highlights • A novel narrow-band green-emitting Mn2+ doped ZnB 2 O 4 phosphor was synthesized. • The phosphor has a broad excitation, which can match well with blue LED chips. • The phosphor emits green light under blue light or electron beam excitation. • The phosphor has excellent thermal and color stability, high color purity. Abstract A novel rare-earth free narrow-band green-emitting Mn2+ doped ZnB 2 O 4 phosphor has been synthesized successfully through solid-state method, and the photoluminescence and cathodoluminescence properties of samples were investigated in detail. The phosphor can emit bright green light peaking at 541 nm with FWHM about 41 nm under both UV and blue light excitation. The broad excitation ranges from 235 nm to 535 nm, especially the strongest excitation locates in blue region, which indicates that the phosphor can match well with not only UV LED chips but also blue LED chips. The temperature-dependent PL properties show that the phosphor has good thermal stability and outstanding color stability. From the CL spectra, it is obvious that the phosphor also exhibits intense green emission with high color purity and good color stability under low-voltage excitation, and the results indicate that the phosphor owns high saturation voltage and saturation current. In view of the outstanding performance in the PL and CL, the ZnB 2 O 4 :Mn2+ can be considered to apply in both LED and FED devices. [ABSTRACT FROM AUTHOR]

High-efficiency phosphor with excellent luminescence properties and thermal stabilities is essential for phosphor-converted white light-emitting diodes (w-LEDs). Compared with red and green phosphors, near-ultraviolet excited blue phosphors with high efficiency and excellent thermal stability are still scarce, and the development of efficient blue phosphors remains challenging. NaLi 3 SiO 4 : Eu2+ (NLSO: Eu2+) is a promising narrow-band blue phosphor. In this paper, a series of Na 1-y K y Li 3 SiO 4 : 5%Eu2+ (0.05 ≤ y ≤ 0.2) phosphors were successfully synthesized by high-temperature solid-state reaction through co-doping a small amount of K+ ions in the matrix, significantly improving their luminescence property and thermal stability. Because of the weaker electronegativity of K+ ions, the emission peaks of Na 1-y K y Li 3 SiO 4 : 5%Eu2+ were slightly blue-shifted from 467 to 463 nm compared with those of NLSO: Eu2+. With an increase in the number of K+ ions, the luminescence intensity of the phosphors increased. When the content of the K+ ion reached 0.2, the luminescence intensity of the Na 0.8 K 0.2 Li 3 SiO 4 : 5%Eu2+ (NKLSO: 5%Eu2+) phosphor reached its maximum. Compared to the NLSO: 5%Eu2+ phosphor, the luminescence intensity increased by approximately 300 %. At 150 °C, the luminescence intensity of NLSO: 5%Eu2+ phosphor was retained at 75.98 % compared with room temperature, while the NKLSO: 5%Eu2+ phosphor maintained a luminescence intensity of 84.36 % relative to room temperature, demonstrating excellent thermal stability. The enhanced luminescence performance of the NKLSO: Eu2+ phosphor makes it a promising high-efficiency blue phosphor for phosphor-converted w-LEDs. Through co-doping a small amount of K+ ions into the NaLi 3 SiO 4 : Eu2+, significantly improving the luminescence property and thermal stability. [Display omitted] • A series of Na 1-y K y Li 3 SiO 4 : 5%Eu2+ (0.05 ≤ y ≤ 0.2) phosphors were successfully synthesized through co-doping K+ ions in the matrix. The weaker electronegativity of K+ ions makes it easier for Eu3+ to be reduced to Eu2+. • In luminescence properties, when the content of the K+ ion reached 0.2, the luminescence intensity of the Na 0.8 K 0.2 Li 3 SiO 4 : 5%Eu2+ phosphor reached its maximum. Compared to the NaLi 3 SiO 4 : 5%Eu2+ phosphor, the luminescence intensity increased by approximately 300 %. • The Na 0.8 K 0.2 Li 3 SiO 4 : 5%Eu2+ exhibited superior thermal stability compared to NaLi 3 SiO 4 : 5%Eu2+. The luminescent intensity of NaLi 3 SiO 4 : 5%Eu2+ at 150 °C remains 75.98 % of the room temperature intensity, while the luminescent intensity of Na 0.8 K 0.2 Li 3 SiO 4 : 5%Eu2+ is significantly increased to 84.36 %. • The narrowband blue phosphor Na 0.8 K 0.2 Li 3 SiO 4 : 5%Eu2+ is a potential candidate for n-UV excited w-LEDs applications because of its excellent luminescence properties. [ABSTRACT FROM AUTHOR]

Full-spectrum white LED (w-LED) lighting is primarily achieved through the combination of multiple-color phosphors excited by the chip, and making the development of efficient multi-color phosphors based on single matrix is an excellent choice for full-spectrum w-LED. In this paper, a series of Rb 2 KNa(Li 3 SiO 4) 4 : xEu2+ (0.1 % ≤ x ≤ 15 %) phosphors were successfully synthesized via high-temperature solid-state reaction with varied Eu2+ concentration. At low doping concentration, the Eu2+ ions exhibit primarily green emission at 530 nm in the phosphor. However, as the doping concentration of Eu2+ ions increase, the emission spectrum undergoes a significant transformation. A cyan emission occurs at 478 nm, resulting in the spectral conversion from a green single-peak emission to a dual-peak emission of cyan and green. The spectral conversion is attributed to the changes in the positioning of Eu2+ ions within the crystal lattice. The obtained phosphors demonstrate excellent thermal stability and can be utilized in w-LED devices. After encapsulation with a blue LED chip, it achieves a color rendering index of 91.8 and a correlated color temperature of 4085 K, showcasing its significant application value in the field of full-spectrum w-LED. • By adjusting the doping concentration of Eu2+ ions and occupied lattice position, the emission spectrum of the Rb 2 KNa(Li 3 SiO 4) 4 : xEu2+ (0.1 % ≤ x ≤ 15 %) phosphor was regulated from a single-peak emission of 530 nm (green) to a dual-peak emission of 478 nm (cyan) and 530 nm (green) . • The phosphors demonstrated excellent thermal stability. Compared with room temperature, the emission intensities of 478 nm and 530 nm of Rb 2 KNa(Li 3 SiO 4) 4 : 0.08Eu2+ phosphor at 150 °C maintained 84.48 % and 83.71 % , respectively. • Rb 2 KNa(Li 3 SiO 4) 4 : Eu2+ proves to be a promising narrow-band cyan-green phosphor with excellent luminescent performance, making it suitable for application in w-LED . [ABSTRACT FROM AUTHOR]

Abstract This work describes extensions to existing level-set algorithms developed for application within the field of atom probe tomography (APT). We present a new simulation tool for the simulation of 3D tomographic volumes, using advanced level set methods. By combining narrow-band, B-Tree and particle-tracing approaches from level-set methods, we demonstrate a practical tool for simulating shape changes to APT samples under applied electrostatic fields, in three dimensions. This work builds upon our previous studies by allowing for non-axially symmetric solutions, with minimal loss in computational speed, whilst retaining numerical accuracy. Highlights • Demonstration of 3D curvature level set methods for APT simulations • Demonstration of non-rotationally symmetric tip shape simulations • Optimised speed for simulations, calculations achievable on minute timescales [ABSTRACT FROM AUTHOR]

Junction-controlled narrow-band Schottky photodetectors are very attractive in the optoelectronic systems that operate in a small spectral range, due to its high noise immunity, simple structure, and self-powered work mode. In this work, simulation was carried out to study the working mechanism of the junction-controlled narrow-band photodetector based on a vertical silicon Schottky structure. It is showed that the spectral response of the device is mainly dominated by the quasi-neutral region instead of the depletion region of the Schottky structure. Widening quasi-neutral region can obviously red-shift the peak wavelengths of both quasi-neutral region and depletion region, and suppress the device response to short wavelength light. As the doping concentration of the silicon substrate increases, a similar phenomenon can be observed due to the decrease of the diffusion length. Furthermore, increasing surface recombination velocity also can effectively reduce the quantum efficiency of the device at the wavelength <1060 nm. These results signify that junction-controlled narrow-band photodetectors of long-wavelength light can be realized by a variety of simple and feasible methods, indicating their promising application in future photoelectric systems. [ABSTRACT FROM AUTHOR]

The necessity of creating channels by utilizing narrow-bands in high frequency regions is a matter of concern for the next generation-oriented wireless communication systems. A microstrip bandpass filter for narrow-band applications has been proposed in this article. Two coupled line filters with tapered line resonators are loaded at the mid-points of two identical pairs of radial stubs. The scalable length of microstrip lines to extend the radial stubs provides over 536 MHz shift of the resonant frequency with a narrow-band at each perturbing step. The proposed filter has been designed on Taconic TLX-8 substrate with 0.5 mm thickness and its filtering parts occupy a nominal area of 131.09 mm2 without feedlines. The fabricated filter exhibits nearly a 50 MHz pass-band at 6.428 GHz center frequency according to the measurement. Steep response of this filter entirely attenuates the out-band signal which enables it to be suitable for narrow-band applications in the higher frequency regions of C-band and ultra-wideband. [ABSTRACT FROM AUTHOR]

Drug‐induced photosensitivity develops when the use of oral or topical photosensitizing medications creates a rash after exposure to ultraviolet (UV) radiation. Medications most commonly implicated in photosensitive drug reactions include amiodarone, nonsteroidal anti‐inflammatories, thiazides, tetracycline antibiotics, chlorpromazine, and fluoroquinolones. It is generally believed that drug‐induced photosensitivity is an UVA phenomenon, caused by UV wavelengths between 315 and 400 nm. Here, we present a case of hydrochlorothiazide (HCTZ)‐induced photosensitivity following exposure to 308‐nm narrow‐band (nb) UVB light emitted from an excimer laser in a patient undergoing treatment for plaque psoriasis. This patient had received biweekly treatments with the excimer laser for years prior without any history of adverse reactions. We believe that our patient suffered an acute photosensitivity to UVB due to new‐onset HCTZ. Because nb UVB–emitting lasers are used to treat many dermatologic conditions, physicians should be aware of potential photosensitivity reactions, review medication lists and counsel patients accordingly. [ABSTRACT FROM AUTHOR]

Objectives: To evaluate different signal-processing algorithms for tactile identification of environmental sounds in a monitoring aid for the deafblind. Two men and three women, sensorineurally deaf or profoundly hearing impaired with experience of vibratory experiments, age 22-36 years. Methods: A closed set of 45 representative environmental sounds were processed using two transposing (TRHA, TR1/3) and three modulating algorithms (AM, AMFM, AMMC) and presented as tactile stimuli using a portable vibrator in three experiments. The algorithms TRHA, TR1/3, AMFM and AMMC had two alternatives (with and without adaption to vibratory thresholds). In Exp. 1, the sounds were preprocessed and directly fed to the vibrator. In Exp. 2 and 3, the sounds were presented in an acoustic test room, without or with background noise (SNR=+5 dB), and processed in real time. Results: In Exp. 1, Algorithm AMFM and AMFM(A) consistently had the lowest identification scores, and were thus excluded in Exp. 2 and 3. TRHA, AM, AMMC, and AMMC(A) showed comparable identification scores (30%-42%) and the addition of noise did not deteriorate the performance. Discussion: Algorithm TRHA, AM, AMMC, and AMMC(A) showed good performance in all three experiments and were robust in noise they can therefore be used in further testing in real environments.

In spectroscopic multi-component gas sensing, the crosstalk in the overlapping region of gas absorption spectra will affect the measurement accuracy. This paper reports a new multi-component gas analyzing method based on partial least squares regression (PLSR), which can retrieve target gas concentration and the composition and concentration of interfering gas from an overlapping narrow-band spectrum. Two overlapping absorption spectra (acetylene and ammonia) around 1530 nm are selected to simulate the absorption crosstalk phenomenon. We built a fiber-optic photothermal interferometry system to verify the method on two-component gases in the overlapping region. The training of the PLSR model was based on 63 sets of photothermal second-harmonic signals, which acquired from the gases composed by 100–700 ppm ammonia and 100–900 ppm acetylene. The prediction error of PLSR model achieved 3.84 % when tested by extra data. • A new multi-component gas sensing method is reported: Narrow-band photothermal spectral data and PLSR algorithm are used to analyze target and crosstalk gases simultaneously. • Acetylene and ammonia are detected by use of a near-infrareds photo-thermal gas sensing system with only one pump laser. The experimental verified determination coefficients (R 2) achieve 0.9934 and 0.9807, respectively. • Dimension optimization based on peak/valley values reduces MAE from 6.71 % to 3.84 %. [ABSTRACT FROM AUTHOR]

Planar nearfield acoustic holography (PNAH) is usually based on narrow-band, single frequency analysis, which is time consuming when the source behavior over a broad frequency range is of interest, as is the case with many industrial sources. In this paper a method, broadband planar nearfield acoustic holography based on one-third-octave band analysis (BPNAH), is described. Data relating to the complex band pressure on the hologram is obtained by combining the root-mean-square pressure corresponding to a one-third-octave band with the phase of the pressure corresponding to a single frequency line. Numerical simulations and measurements show that the BPNAH method allows a significant reduction in processing time, while keeping a similar accuracy to the conventional reconstruction, which is based on the summation of frequency by frequency in the corresponding band. As a simple, time-saving and robust technique, the BPNAH method is particularly well adapted to industrial studies. [ABSTRACT FROM AUTHOR]

ABSTRACT In this article, a Ka-band narrowband multilayer bandpass filter (BPF) centered at 34.5 GHz is presented, where a hybrid structure of two substrate integrated waveguide (SIW) cavities with slots and CPW is used to meet the good filtering capability and compact size. Benefiting from the 3-D circuit layout, the proposed filter can effectively overcome a vital drawback of large circuit size of traditional filter, and be used in system-in-package application. The circuit size of the filter excluding feed lines is about 0.5λg by 0.5λg, where λg is the guided wavelength at the central frequency of 34.5GHz. Simulated results show that the filter has the 3dB bandwidth of 0.86 GHz (FBW = 2.5%) and insertion loss of 1.7 dB at central frequency. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1395-1398, 2016 [ABSTRACT FROM AUTHOR]