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LUT-Free Carrier Recovery for Intradyne Optical DPSK Receivers in udWDM-PON
摘要： We present an LUT-free carrier recovery architecture for intradyne optical DPSK receivers that reduces the required DSP hardware resources, power consumption as well as total process clocks, aimed at cost-effective transceivers for access networks applications. The proposed architecture simplifies frequency compensation algorithm to avoid using mth-power operation and LUTs. We prototyped the proposed carrier recovery on a commercial FPGA for real-time evaluation with data at 1.25Gb/s. The optical transmission system is implemented by direct-phase modulation of commercial DFB lasers, 25 km of single-mode fiber, and a coherent receiver with low-cost optical front-end based on 3x3 coupler and three photodiodes providing phase-diversity operation. Results show high performance in real-time, achieving -54 dBm sensitivity at BER = 10-3 as well as feed-forward frequency error correction, high robustness against the fast frequency laser drifts, and high tolerance to optical phase noise in a 6.25GHz spaced ultra-dense WDM grid.
关键词： phase shift keying,FPGA,digital signal processing,Carrier recovery,frequency estimation
更新于2025-09-23 15:22:29
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Development of Ion Exchange Ligands with High Separation Performance and Colorimetric Analysis Using Gold Nanoparticles Decorated with The Functional Ligands
摘要： Development of metal separating reagents with high selectivity is necessary for efficient separation and recovery of valuable metals contained in industrial wastes, and removal and detection of toxic metals. We have developed novel metal separating ligands with a diglycolamic acid (DGAA) framework. The ligands have a tridentate coordination structure consisting of an amide group and a carboxy group connected by an ether chain and provide a metal separation ability superior to that of commercial ligands. Since the ligands can be synthesized simply in one step, this helps to reduce the production costs of the ligands. In the present review article, we report the extraction characteristics of DGAA-type ligand for 56 kinds of metal ions, extraction separation of rare-earth metal ions, and removal of toxic metal ions. Furthermore, a one-pot biological approach to fabricate DGAA-decorated gold nanoparticles has been developed using the DGAA-type ligand fused to the N-terminus of a gold-binding peptide. It was found that the DGAA-decorated gold nanoparticles can act as a high-sensitive colorimetric sensor for detecting toxic metal ions with color change.
关键词： Ion-exchange materials,Gold nanoparticles,Diglycolamic acid,Colorimetric detection,Metal separating reagents,Separation and recovery
更新于2025-09-23 15:22:29
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Lane Adaptive Recovery for Multiple Lane Faults in Optical Ethernet Link
摘要： We propose a lane adaptive recovery scheme for multiple lane faults in a multi-lane-based Ethernet link. In our scheme, when lane faults occur in a link, they are processed not as full link faults but as partial link faults. Our scheme provides a higher link utilization and lower packet loss rate by reusing the available lanes of the link and providing a low recovery time of under a microsecond.
关键词： Multiple lane faults,multi-lane-based Ethernet link,lane recovery
更新于2025-09-23 15:22:29
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Return of function after CNS axon regeneration: Lessons from injury-responsive intrinsically photosensitive and alpha retinal ganglion cells
摘要： This review addresses issues relating to the survival and axon regeneration of both intrinsically photosensitive retinal ganglion cells (ipRGC) and αRGC, and possible ensuing patterns of functional recovery after optic nerve crush, all of which are broadly relevant to recovery from injury in the central nervous system (CNS) as whole. Although much needs to be clarified about the connectivity, function and patterns of myelination of regenerated CNS axons, the results of recent research on activity-induced αRGC axon regeneration associated with functional restitution have highlighted key focal obstacles to recovery including neurotrophic support, axon misguidance, target recognition failure and dysmyelination. Pan RGC survival/axon regeneration requires receptor binding and downstream signalling by a cocktail of growth factors, more generally defined in the CNS by the individual trophic requirements of neuronal subsets within a given disconnected centre. Resolution of the problem of failed axon guidance and target recognition is complicated by a confounding paradox that axon growth inhibitory ligand disinhibition required for axon regeneration may mask axon guidance cues that are essential for accurate re-innervation. The study of the temporal parameters of remyelination of regenerated αRGC axons may become feasible if they establish permanent homologous connections, allowing time for new myelin sheaths to fully form. Unless near complete re-innervation of denervated targets is re-instated in the CNS, debilitating dysfunctional neurological sequelae may ensue from the resulting imbalance in connectivity.
关键词： CNS axon regeneration,recovery of function,ipRGC,CNS trauma
更新于2025-09-23 15:21:21
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Hardware-efficient Signal Processing Technologies for Coherent PON Systems
摘要： Future passive optical network (PON) systems supporting more than 50 Gb/s/λ present a challenge for the use of intensity modulation direct detection (IM-DD). Since coherent technology improves the receiver sensitivity over that of IM-DD, it is a promising candidate for 100 Gb/s or higher PON systems. Introducing hardware-efficient signal processing technologies tailored to PON systems will help render coherent technology suitable for PON systems. We here review hardware-efficient signal processing technologies suitable for PON systems. We introduce two types of simplified adaptive equalization (AEQ), one which sacrifices differential group delay compensation (DGDC), and another which sacrifices some chromatic dispersion compensation but does provide DGDC. Transmission experiments on a 100 Gb/s/λ-based coherent wavelength division multiplexing (WDM) PON system showed that simplified AEQ without DGDC and with DGDC exhibited only 0.2 dB and 1.4 dB penalty respectively, compared with conventional DSP. The additional penalty due to the maximum possible cumulative DGD was evaluated by numerical simulation. Conventional AEQ and the simplified AEQ with DGDC showed negligible penalty, but the simplified AEQ without DGDC showed a 1.4 dB penalty. We also introduce simplified carrier phase recovery (CPR) with inter-polarization phase offset estimation, and this showed the same performance as the conventional DSP, in both experiment and simulation. Taking these results into account, 100 Gb/s/λ-based coherent WDM PON systems with the simplified AEQs in combination with the simplified CPR were shown to be able to support the loss budget required for 8 ONU splits over an 80 km span of single mode fiber.
关键词： adaptive equalization (AEQ),5G mobile front haul (MFH),coherent communication,carrier phase recovery (CPR),100 Gb/s-class passive optical network (PON)
更新于2025-09-23 15:21:21
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Efficient and selective sensing of nitrogen containing gases by Si2BN nanosheets under pristine and pre-oxidized conditions
摘要： Motivated by the promise of two-dimensional nanostructures in the field of gas sensing, we have employed van der Waals corrected density functional theory calculations to study the structural, electronic and gas sensing propensities of recently designed Si2BN monolayer. Our rigorous simulations reveal that the representative members of nitrogen containing gases (NCGs) such as NO, NO2 and NH3 binds extremely strongly on pristine Si2BN monolayer. However a strong dissociative adsorption in case of NO and NO2 would poison the Si2BN and ultimately reversibility of the monolayer would be compromised. Exploring the sensing mechanism in more realistic pre-oxidized conditions, the binding characteristics of O2@Si2BN changed dramatically, resulting into much lower adsorption in associative manner for all NO, NO2 and NH3. A visible change in work function indicates the variation in conductivity of O2@Si2BN upon the exposure of incident gases. Sustainable values of binding energies would also ensure a quick recovery time that makes O2@Si2BN an efficient nano sensor for pollutants like NCGs.
关键词： Conductivity,Adsorption,Work function,Recovery time,Monolayer
更新于2025-09-23 15:21:21
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valley of (In,Al)As/AlAs quantum dots
摘要： The electron-nuclei hyperfine interaction of electrons in indirect band gap (In,Al)As/AlAs quantum dots with type-I band alignment has been experimentally studied by measuring the polarization degree of the photoluminescence in a transverse magnetic field (Hanle effect) and the polarization recovery in a longitudinal magnetic field. The different symmetries of the X valley electron Bloch amplitudes at the As, In, and Al nuclei strongly affect the hyperfine interaction. The hyperfine constants corresponding to these nuclei have been determined.
关键词： X valley,hyperfine constants,Bloch amplitudes,Hanle effect,polarization recovery,photoluminescence,quantum dots,electron-nuclei hyperfine interaction
更新于2025-09-23 15:21:01
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Hybrid of quantum dots for interfacial tension reduction and reservoir alteration wettability for enhanced oil recovery (EOR)
摘要： Nanoparticle stabilized emulsions in enhanced oil recovery are more attractive and practical than conventional emulsions which stabilized by colloidal particles and different surfactants due to their advantages and special characteristics such as high stability in harsh condition, move long distance in reservoirs without high retention due to small size of nanoparticles. Only one third of original oil in place (OIP) is usually produced and two third of oil in place will be trapped to reservoir rockthus suitable chemical enhanced oil recovery (C-EOR) methods should be used. In this research, we have suggested a novel, economical and commercial method for synthesis N-doped graphene quantum dots (N-GQDs)/MoS2 quantum dots (MQDs) nanohybrids for preparing different percentage of Nanoemulsions which can reduce alterfacial tension significantly so it can used for Enhanced Oil Recovery (EOR) application. MoO3 material was used as a base of MQDs. MQDs was synthesized via exfoliation of MoS2 nanoparticles by Butyl lithium under N2 atmosphere condition. N-GQDs were synthesized by citric acid and urea materials via hydrothermal method. GQDs/MQDs were prepared via a simple sol-gel method for 5 h string. Synthetic materials were characterized with X-ray diffraction (XRD), Fourier transform infrared (FT-IR), UV–visible absorption, Scanning Microscopic Electron (SEM), EDX profile and mapping, Transmission electron microscopy (TEM), High Resolution Transmission electron microscopy (HRTEM) and differential scanning calorimetry (DSC). Then, emulsions were prepared with two different cationic and anionic surfactants and the stability and morphology of emulsion droplets were investigated in condition close to reservoir environment. Our results show that 10% GQDs/MQDs in cationic surfactant and 50% GQDs/MQDs in anionic surfactant have good stability and very small and fine emulsion droplets in simulated reservoir conditions in laboratory. The Interfacial Tension (IFT) measurement shows N70% improvement which indicates the high ability of these nanohybrids in reducing the surface tension than previous nanohybrids. Contact angle values show that these nanohybrids can alter the wettability of reservoir rock from oil-wet to water-wet so the trapped oil in the porous region of rock can be easily extracted in the presence of a layer of these nanohybrids. Furthermore, according to the results of altering the density and viscosity of nanohybrids, these are not as limiting parameters and only about 1% increasing observed for density and viscosity, respectively. Coreflooding test revealed the high oil recovery efficiency (22%) at very low nanofluid concentration (0.01 wt%).
关键词： Molybdenum disulfide quantum dots,Graphene quantum dots,Nanohybrids emulsion,Enhanced oil recovery (EOR),Quantum dot hybrids,Rock reservoir alteration wettability
更新于2025-09-23 15:21:01
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High-performance amorphous BeZnO-alloy-based solar-blind ultraviolet photodetectors on rigid and flexible substrates
摘要： In this study, the bandgap of ternary alloy BeZnO was modulated to make the material applicable to solar-blind ultraviolet (UV) radiation detection. This was done by preparing amorphous films with high Be doping contents on rigid c-sapphire and flexible polyethylene terephthalate (PET) and polyethylene naphthalene (PEN) substrates. After depositing a pair of parallel Al electrodes, amorphous BeZnO-alloy-based solar-blind UV photodetectors (PDs) with peak responsivity occurring at around 230 nm were constructed and their cut-off wavelengths are less than 284 nm. The PDs constructed on three substrates exhibit extremely low dark currents of 58.7 pA, 2.9 pA, and 1.8 pA, respectively. Time-dependent photoresponse cycling confirmed devices reproducible, and sensitive to solar-blind UV radiation. More importantly, the devices exhibited fast response speeds with rise times of approximately 40 ms and particularly fast recovery speeds with decay times of approximately 10 ms. Our research provides a method of constructing high-performance PDs on various substrates. And constructing amorphous solar-blind UV PDs on flexible substrate in this work is expected to be guiding significance to the design of PDs with deformability.
关键词： Amorphous BeZnO alloy,Fast recovery speed,Solar blind photodetectors,Flexible substrate,High Be content
更新于2025-09-23 15:21:01
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Influence of Electrode Configurations on the Interruption Capacity of Laser Triggered Vacuum Switch
摘要： The electrode configurations have an important effect on the interruption performances of laser triggered vacuum switch (LTVS), but few works pay attention to it so far. The objective of this article is to study the interruption capacity of LTVS with different electrode configurations. The 3-D simulation models of axial magnetic field (AMF) electrode and transverse magnetic field (TMF) electrode are built up, and the magnetic field distributions are calculated and compared. The test platform is set up based on a detachable vacuum chamber. The interruption capacity of LTVS with different electrode structures, electrode spacings, and polarity configurations is studied and analyzed. The test results prove that, compared to the AMF electrode, the interruption capacity of LTVS under the TMF electrode is obviously better, but it is more susceptible to the electrode spacing, and gradually decreases with the increase of electrode spacing. Influence of polarity configuration on the interruption capacity of LTVS is closely related to the target material. The LTVS with KCl + Ti under the positive polarity configuration shows better interruption capacity than negative polarity configuration. The works in this article provide references for the design of LTVS products.
关键词： target material,electrode configurations,laser triggered vacuum switch (LTVS),interruption capacity,Dielectric recovery
更新于2025-09-23 15:21:01