- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Nearest Centroid Neighbor Based Sparse Representation Classification for Finger vein Recognition
摘要： In this paper, an efficient finger vein recognition algorithm based on the combination of the nearest centroid neighbor and sparse representation classification techniques (kNCN-SRC) is presented. The previously proposed recognition algorithms are mainly based on distance computation. In the proposed method, the distance, as well as the spatial distribution, are considered to achieve a better recognition rate. The proposed method consists of two stages: first, the k nearest neighbors of the test sample are selected based on the nearest centroid neighbor and then in the second stage based on the selected number of closest nearest centroid neighbors (k) the test sample is classified by sparse representation. Findings from the proposed method kNCN-SRC demonstrated an increased recognition rate. This improvement can be attributed to the selection of the train samples, where the train samples are selected by considering the spatial and distance distribution. In addition, the complexity of SRC is reduced by reducing the number of train samples for classification of the test sample by sparse representation and the processing speed of the proposed algorithm is significantly improved in comparison to the conventional SRC which is due to the reduced number of training samples. It can be concluded that the kNCN-SRC classification method is efficient for finger vein recognition. An increase in the recognition rate of 3.35%, 9.07%, 20.23%, and 0.81% is obtained for the proposed kNCN-SRC method in comparison with the conventional SRC for the four tested public finger vein databases.
关键词： Finger vein recognition,Distance criterion,k-Nearest Centroid Neighbor,Spatial distribution,Sparse Representation Classification
更新于2025-09-23 15:22:29
-
Application to Artificial Skin of Double Cone Tube Made of Acrylic Resin Formed by Micro Stereolithography
摘要： A functional double cone tube (DCT) array with gas trapping and high durability is developed in the application of artificial skin. A stereo-lithography system is employed to fabricate DCT made of acrylic resin. In an aqueous solution, a certain amount of gas can be trapped in the tube due to capillary force balance. Under applying an external load, internal stress is effectively released at the interface between top and base cones. In the tactile sensing investigation, softness and tackiness senses as an artificial skin are felt.
关键词： Acrylic resin,Gas storage,Double cone tube (DCT),Stress distribution,Artificial skin,Micro stereo-lithography
更新于2025-09-23 15:22:29
-
Optical Wireless Communication Based Indoor Positioning Algorithms: Performance Optimisation and Mathematical Modelling
摘要： In this paper, the performance of the optimal beam radius indoor positioning (OBRIP) and two-receiver indoor positioning (TRIP) algorithms are analysed by varying system parameters in the presence of an indoor optical wireless channel modelled in line of sight configuration. From all the conducted simulations, the minimum average error value obtained for TRIP is 0.61 m against 0.81 m obtained for OBRIP for room dimensions of 10 m × 10 m × 3 m. In addition, for each simulated condition, TRIP, which uses two receivers, outperforms OBRIP and reduces position estimation error up to 30%. To get a better understanding of error in position estimation for different combinations of beam radius and separation between light emitting diodes, the 90th percentile error is determined using a cumulative distribution frequency (CDF) plot, which gives an error value of 0.94 m for TRIP as compared to 1.20 m obtained for OBRIP. Both algorithms also prove to be robust towards change in receiver tilting angle, thus providing flexibility in the selection of the parameters to adapt to any indoor environment. In addition, in this paper, a mathematical model based on the concept of raw moments is used to confirm the findings of the simulation results for the proposed algorithms. Using this mathematical model, closed-form expressions are derived for standard deviation of uniformly distributed points in an optical wireless communication based indoor positioning system with circular and rectangular beam shapes.
关键词： position estimation,channel modelling,raw moments,optical wireless communication,indoor positioning system,cumulative distribution frequency,standard deviation
更新于2025-09-23 15:22:29
-
A review on smart application of supplemental lighting in greenhouse fruiting vegetable production
摘要： Different spectra of light trigger different plant growth processes. Therefore, the optimum light spectrum for various plant physiological and growth processes may be different. For greenhouse fruiting vegetables, such as tomatoes, it is important to optimize light spectrum to promote canopy growth to increase light interception during the early stage of plant growth. Once the plants reach full canopy, the focus should be moved to optimizing vertical light distribution because most greenhouse fruiting vegetables are tall crops and the growth processes along the vertical profile are different; most of the canopy growth occurs in the top and middle canopy while fruit growth occurs in the middle and bottom canopy. Because the fruit, not the leaf, is the economic product, the optimized light spectral composition should enhance leaf carbon export and translocation to fruit to improve fruit yield and quality. Therefore, a research project was initiated in 2013 to identify proper light spectral composition and vertical distribution regimes for greenhouse fruiting vegetable production. Different overhead light sources (high-pressure sodium light with or without far-red light-emitting diode (LED) light, plasma light and different spectral compositions of LEDs) and several intra-canopy spectral compositions provided by LEDs were evaluated over four winters on tomatoes, mini-cucumbers and sweet peppers. The effects of light spectrum on whole-plant net carbon exchange and leaf carbon export using 14C-isotype tracing were also investigated. The vertical light regimes resulted in significant differences in leaf photosynthetic rate, leaf size, fruit yield and fruit quality in greenhouse tomatoes, mini-cucumbers and sweet peppers. Proper vertical light regimes were identified for hybrid light systems (overhead high intensity discharge light + intra-canopy LEDs) and for pure LED light systems (overhead + intra-canopy LEDs). This review clearly demonstrates that optimized vertical light regimes can be developed for improving both plant growth and fruit yield and quality in year-round greenhouse fruiting vegetable production.
关键词： far-red light,Solanum lycopersicum,Capsicum annuum,Cucumis sativus,light quality,vertical light spectral distribution,temperature,LED,lighting,spectral composition
更新于2025-09-23 15:22:29
-
Rainbow schlieren-based direct visualization of thermal gradients around single vapor bubble during nucleate boiling phenomena of water
摘要： Real time non-intrusive diagnostics of thermal gradients around a single vapor bubble in isolated nucleate pool boiling with water as the working fluid have been presented. Direct visualization of transient evolution of temperature gradients in the vicinity of the heated substrate and around the single bubble as it undergoes various sub-processes has been performed using rainbow schlieren deflectometry. Boiling experiments have been conducted under saturated conditions. Results have been presented in the form of two-dimensional rainbow schlieren images wherein the degree of color re-distribution gives a direct measure of the strength of thermal gradients. Through the real time experimental images, various sub-processes/phenomena associated with boiling heat transfer such as development of superheat layer in the vicinity of the heated substrate, inception and further growth of the vapor bubble followed by scavenging of the superheat layer as the vapor bubble departs into the bulk fluid have been discussed. The profiles of hue distribution near the triple contact line brought out the presence of near stagnant fluid zone in which the heat transfer phenomenon was seen to be primarily diffusion-dominated. Beyond this narrow region, significant bulk fluid movement was observed on the basis of the spatial distributions of hue values recorded in the form of real time schlieren images. The experiments further revealed an instantaneous localized bending of the superheat layer as the bubble leaves the heater surface and subsequent shedding of the wake vortices from the edges of the departing bubble as it moves upwards in the bulk fluid.
关键词： Whole field temperature distribution,Heat transfer rates,Nucleate pool boiling,Rainbow schlieren deflectometry
更新于2025-09-23 15:22:29
-
Double-slit photoelectron interference in strong-field ionization of the neon dimer
摘要： Wave-particle duality is an inherent peculiarity of the quantum world. The double-slit experiment has been frequently used for understanding different aspects of this fundamental concept. The occurrence of interference rests on the lack of which-way information and on the absence of decoherence mechanisms, which could scramble the wave fronts. Here, we report on the observation of two-center interference in the molecular-frame photoelectron momentum distribution upon ionization of the neon dimer by a strong laser field. Post-selection of ions, which are measured in coincidence with electrons, allows choosing the symmetry of the residual ion, leading to observation of both, gerade and ungerade, types of interference.
关键词： double-slit interference,photoelectron momentum distribution,strong-field ionization,neon dimer,molecular frame
更新于2025-09-23 15:22:29
-
The effect of size and aspect ratio on the trapped field properties of single grain, Y–Ba–Cu–O bulk superconductors
摘要： Bulk, single grain (RE)Ba2Cu3O7?δ [(RE)BCO, where RE is a rare earth element or yttrium] high temperature superconductors exhibit significant potential for use in a variety of engineering applications due to their ability to trap large magnetic fields, which can be up to ten times greater than those generated by conventional, iron-based magnets. Limitations on the maximum size to which single grains can be grown, however, are a major obstacle to the further development of these materials. Indeed, multiple samples are often required to achieve the required superconducting properties in particular applications. The geometry of bulk (RE)BCO single grain samples plays an important role in determining the superconducting properties of a given technical arrangement. In order to gain a better understanding of the full application potential of bulk single grain superconductors, three relatively long, cylindrical YBCO single grains of different diameters were fabricated and their trapped field and total trapped flux measured at 77 K as a function of sample height. The effects of size and aspect ratio of YBCO single grains on these key applied properties have been investigated experimentally and the results compared qualitatively with the predictions of an established theoretical model. Conclusions based on the trapped field measurements on a variety of single grain samples are presented in this study and the possibilities of using assemblies of smaller samples for engineering devices, in particular, are discussed.
关键词： distribution of the trapped field,aspect ratio,assemblies,bulk superconductors,applications
更新于2025-09-23 15:22:29
-
Numerical analysis of brilliance and coherent photon flux of segmented undulator radiation based on statistical optics
摘要： A method based on wave optics together with electron tracking is used to analyze synchrotron radiation from a segmented undulator in a double or multi mini-β function lattice storage ring. Radiation brilliance and transverse coherence features are investigated, where the former is calculated with the Wigner distribution function and the latter is evaluated by integrating the photon flux and cross-spectral density to exhibit the coherent flux and overall degree of coherence. To be specific, radiation properties for a single undulator in a typically single mini-β function and a tandem undulator in a double mini-βy lattice are compared in this work. As a result, both, brilliance and coherent flux can be enhanced by a second tandem undulator at the Taiwan Photon Source.
关键词： Wigner distribution function,transverse coherence,segment undulator.,double mini-βy lattice,brilliance
更新于2025-09-23 15:22:29
-
Polarization-based plug-and-play measurement-device-independent quantum key distribution
摘要： Measurement-device-independent quantum key distribution (MDI-QKD) has received much attention, with the goal of overcoming all of the security loopholes caused by an imperfect detection system. We here propose a plug-and-play MDI-QKD (P&P MDI-QKD) scheme whereby an untrusted relay node, Charlie, owns a laser and sends photons to Alice and Bob. Alice (Bob) modulates the polarization of the incident photons and returns them to Charlie. Charlie uses a modified Bell state analyzer (BSA) to perform Bell state measurements (BSM). In comparison with the original version of MDI-QKD, our scheme exploits a single untrusted laser as the photon source. This makes the signal photons identical and enhances the Hong-Ou-Mandel effect. Second, because of the P&P structure, the setup can automatically eliminate the birefringence influence of the fibers, which makes the setup highly stable. Finally, our modified BSA can identify |Φ?+ and |Φ?? of four Bell states with polarization encoding but not |Ψ?+ and |Ψ??. Based on practical experimental parameters, a simulation showed that the maximum theoretical secure transmission distance could reach more 280 km.
关键词： Plug-and-play,Measurement-device-independent,Quantum cryptography,Quantum key distribution
更新于2025-09-23 15:22:29
-
Translucent packed bed structures for high throughput photocatalytic reactors
摘要： Translucent photocatalytic reactor structures are investigated as a possible alternative to numbering up as a method for the scale-up of microreactors. The structure and the light source design is elaborated to introduce this concept. The light field was characterized using a ray tracing algorithm. A rectangular reactor made from glass was designed using borosilicate spheres small enough to create an array of interconnected microchannels in the reactor. It was found that ray tracing can be used as a proper tool to easily design multiple-LED light sources and predict respective irradiance patterns. The performance of the reactor was assessed using the apparent rate constant, the space-time yield and the photocatalytic space-time yield, a recently introduced performance parameter which takes into account the lamp power and the reactor productivity. The apparent rate constant of the reactor for an incoming irradiance of 191 W m?2 was found to be 0.82 min?1, which is, to our knowledge, in the range of microreactors and 1–2 orders of magnitude higher than any high throughput immobilized reactor in literature. With a photocatalytic space-time yield of 0.657 m3 day?1 m?3 reactor kW?1 our reactor was amongst the best reported performers in terms of productivity and energy efficiency. This performance is related to the high specific illuminated surface area of 4267 m2 m?3 and high catalyst load of 1.9 g L?1.
关键词： Light distribution,Structured reactors,Photocatalysis,Photocatalytic degradation,LED,Reactor engineering
更新于2025-09-23 15:22:29