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Automatic modulation classification (AMC) has been identified to perform a key role to realize technologies such as cognitive radio, dynamic spectrum management, and interference identification that are arguably pivotal to practical SG communication networks. Random graphs (RGs) have been used to better understand graph behavior and to tackle combinatorial challenges in general. In this research article, a novel modulation classifier is presented to recognize M-Quadrature Amplitude Modulation (QAM) signals using random graph theory. The proposed method demonstrates improved recognition rates for multiple-input multiple-output (MIMO) and single-input single-output (SISO) systems. The proposed method has the advantage of not requiring channel/signal to noise ratio estimate or timing/frequency offset correction. Undirected RGs are constructed based on features, which are extracted by taking sparse Fourier transform (SFT) of the received signal. This method is based on the graph representation of the SFT of the 2nd, 4th, and 8th power of the received signal. The simulation results are also compared to existing state-of-the-art methodologies, revealing that the suggested methodology is superior.

Unstained microscopy of growth cartilage microstructure is crucial for understanding bone formation and related diseases. Here, we compare imaging modalities with unconventional contrast mechanisms applied to the epiphyseal bone-cartilage interface and highlight their comparative merits.

We have constructed a finite element simulation where we investigate the effects of wet-etch-induced surface roughness on transmission and reflection of infrared light in the 8-12um band. A silicon wafer was wet-etched for 2 hours in a 10% KOH solution at 80°C, scanned in an atomic force microscope, and the surface profile was recreated in COMSOL. Simulated plane waves of light and varying angles of incidence were then allowed to pass through this surface and the resulting effects on the reflection and transmission were investigated. Roughness was then amplified to investigate the effects of increased surface roughness. For the wavelengths investigated, an increase in transmission of 8% could be seen up to an RMS surface roughness of 800nm followed by a decrease, while the angles investigated showed an RMS dependent increase in transmission between 20° and 40° for RMS surface roughness' above 1000nm.

Cerium-doped single crystals (Ce:LuAG, Ce:YAG, Ce:GAGG, Ce:GdYAG) have been investigated as stationary phosphor candidates for blue laser driven solid-state lighting without heat sink. The luminous properties of the single crystals are superior compared to the commercial ceramic powder phosphor wheels (Ce3+: Y3Al5O12). The high-power blue laser diode driven temperature increase of the crystals versus quantum efficiency is experimentally measured and discussed. We have carried out realistic measurements at high excitation power levels and at high temperatures. Limitation of phosphors as stationary sources is determined for commercial usage. The measurements were done without any heat sink to see the relative comparison of SCPs in the worst-case scenarios. The results indicate that Gd and Ga addition decreases the luminescence quenching temperature. Based on their superior properties, these single crystals can serve as potential phosphor candidates for high-power blue diode laser driven picture projectors for the green and red channels.

The remarkable performance in perovskite solar cells over the past few years primarily stemmed from an improvement in perovskite film composition and morphology. Antisolvent treatment of perovskite films is one such widely adopted method where a solvent other than that used for precursor solution is introduced to facilitate rapid crystallization of perovskite crystals and to obtain a homogeneous pin-hole free film. Various reports are published recently to understand solvent extraction mechanism, electrical properties and the effect of antisolvent treatment of perovskite film on device performance and stability. Herein, we report some more insights on the charge carrier dynamics, crystallinity and more importantly, the change in energy levels of antisolvent treated perovskite films. The UV–vis absorption, photoluminescence, and photoelectron spectroscopy measurements revealed a downward shift in energy levels of MAPbI3 perovskite when treated with an antisolvent. The energy level shift favoured interfacial charge transfer and resulted in remarkable open-circuit voltage ~1.08 V and photoconversion efficiency 8.21% up from 0.61 V and 1.3% for a non-treated film, respectively for devices prepared at ambient conditions.

Sheet beam vacuum electron tubes are an attractive solution for high-power sources or amplifiers at millimeter-waves. In this article, a novel ${W}$ -band slow wave structure (SWS) for traveling wave tube (TWT) amplifiers supporting a sheet beam is proposed. The SWS is based on a rectangular waveguide with ${H}$ - and ${E}$ -plane loaded (HEL) metal corrugations. A test structure of the proposed HEL SWS with purposely designed input and output couplers was built in the frequency range of 91–98 GHz ( ${W}$ -band). The measured scattering-parameters agree well with the simulations showing ${S}_{11} dB over 10-GHz bandwidth. A TWT was designed and simulated with the HEL SWS. It shows very good gain-bandwidth performance. The SWS is easy to manufacture by low-cost computer numerical controlled (CNC)-milling. The results demonstrated that the HEL SWS is a very good solution to build high-power, wideband millimeter-wave TWTs for a wide range of applications that need high power in a broad frequency range.

There is a need to better understand the peripheral optics of the human eye and their correction. Current eye models have some limitations to accurately predict the wavefront errors for the emmetropic eye over a wide field. The aim here was to develop an anatomically correct optical model of the human eye that closely reproduces the wavefront of an average Caucasian-only emmetropic eye across a wide visual field. Using an optical design program, a schematic eye was constructed based on ocular wavefront measurements of the right eyes of thirty healthy young emmetropic individuals over a wide visual field (from 40° nasal to 40° temporal and up to 20° inferior field). Anatomical parameters, asymmetries, and dispersion properties of the eye’s different optical components were taken into account. A geometry-independent gradient index model was employed to better represent the crystalline lens. The RMS wavefront error, wavefront shapes, dominant Zernike coefficients, nasal-temporal asymmetries, and dispersion properties of the developed schematic eye closely matched the corresponding measured values across the visual field. The developed model can help in the design of wide-field ophthalmic instruments and is useful in the study and simulations of the peripheral optics of the human eye.

Laser sources have been promised for many years to be better light sources as compared to traditional lamps or light-emitting diodes (LEDs) for projectors, which enable projectors having wide colour gamut for vivid image, super brightness and high contrast for the best picture quality, long lifetime for maintain free operation, mercury free, and low power consumption for green environment. A major technology obstacle in using lasers for projection has been the speckle noise caused by to the coherent nature of the lasers. For speckle reduction, current state of the art solutions apply moving parts with large physical space demand. Solutions beyond the state of the art need to be developed such as integrated optical components, hybrid MOEMS devices, and active phase modulators for compact speckle reduction. In this article, major methods reported in the literature for the speckle reduction in laser projectors are presented and explained. With the advancement in semiconductor lasers with largely reduced cost for the red, green and the blue primary colours, and the developed methods for their speckle reduction, it is hoped that the lasers will be widely utilized in different projector applications in the near future.

For travelling-wave tube in millimeter and submillimeter wave frequency bands, an H-plane and E-plane loaded rectangular waveguide is demonstrated as slow-wave structure. The H-plane and E-plane loaded slow-wave structure is designed at W-band for fast verification of the design concept. The cold-test parameters are compared with measurement results.

An Imaging and a non-imaging Laser Driven Static Phosphor Light Engine which utilizes LuAG:Ce(0.3%) single crystal phosphor is proposed. Both designs are compared and their limitations and advantages are discussed.

The design optimization and simulation for high performance of two types of slow wave structures (SWS) for micro-electro-mechanical system (MEMS) terahertz (THz) sources are presented, e.g., THz staggered double vane (SDV) traveling wave tube (TWT) working at center frequency of 220 GHz, H-plane and E-plane loaded (HEL) rectangular TWT working at center frequency of 400 GHz. The structures are able to realize a larger interaction impedance, thereby resulting in higher gain and improved output power of the devices. To further enhance the energy transferring between the electron beam and THz wave, the maximum length of the interaction section can be extended using the phase velocity tapering technique, where the spent electron beam energy can be reused by resynchronizing the phase velocity of the THz signal with electron velocity at the second section of the TWT. As an achievement, improved power of more than 50% is achieved over the operated bandwidth for both designs. The designs have considered the LIGA fabrication for these vacuum MEMS THz sources.

An analysis of slow-wave structure (SWS) for vacuum-electron traveling wave tube is carried out using COMSOL Multiphysics software. A helix SWS is used as an example to model and perform fully coupled 3D electromagnetics cold-simulations and beam-wave interaction hot-simulations. The preliminary COMSOL simulation results show good agreement with calculations from CST studio software.

In this study, a sequential deposition process is used for the fabrication of PEDOT: PSS based inverted planar perovskite solar cell. A small amount of additive deionized water (DI-H2O) was added into PbI2 + Dimethyl formamide (DMF) precursor solution in order to increase the solubility of PbI2 in DMF, and finally to manipulate the surface morphology of the perovskite films. A morphology transition from needle like structure to hexagonal plates, and then needle-like again has been observed as the DI-H2O was added continuously (0.0 wt% to 3.0wt%). The latter one leads to full surface coverage of the perovskite, which is essential for high performance solar cell., {"references":["Z. Xiao, C. Bi, Y. Shao, Q. Dong, Q. Wang, Y. Yuan, et al., \"Efficient, high yield perovskite photovoltaic devices grown by interdiffusion of solution-processed precursor stacking layers,\" Energy & Environmental Science, vol. 7, pp. 2619-2623, 2014.","L. Zheng, Y. Ma, S. Chu, S. Wang, B. Qu, L. 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