Near‐Infrared Quantum Cutting via Downconversion Energy Transfers in Ho3+/Yb3+ Codoped Tellurite Glass Ceramics

The different concentration of Ho³⁺/Yb³⁺ codoped tellurite glasses were prepared by high‐temperature melting‐quenching method. On excitation of Ho³⁺ ions with blue photon at 449 nm as well as ultraviolet (UV) photon at 360 nm, the near infrared emission at 977 nm from Yb³⁺ and 981, 1020 nm from Ho³⁺, which could be absorbed by silicon and enhance the efficiency of the silicon‐based solar cell, were observed. The energy‐transfer process of Ho³⁺ and Yb³⁺ ions and involved mechanism have been investigated and discussed. The first‐order energy transfer (ET) through cross relaxation and a back ET from Yb³⁺ to Ho³⁺ occurred in the near‐infrared quantum cutting (NIR QC) system are proposed and verified. The NIR quantum efficiency achieved 166% when Yb³⁺ doping concentration is 20 mol%.     

Network Design Model to Integrate Shelter Assignment with Contraflow Operations in Emergency Evacuation Planning

Networks and Spatial Economics - In traditional emergency evacuation planning, shelter assignment and contraflow operations are determined sequentially. In this paper, we show that these two types...     

Medical image fusion based on hybrid intelligence

Medical image fusion combines complementary images from different modalities for proper diagnosis and surgical planning. A new approach for medical image fusion based on the hybrid intelligence system is proposed. This paper has integrated the swarm intelligence and neural network to achieve a better fused output. The edges are an important feature of an image and they are detected and optimized by using ant colony optimization. The detected edges are enhanced and it is given as the feeding input to the simplified pulse coupled neural network. The firing maps are generated and the maximum fusion rule is applied to get the fused image. The performance of the proposed method is compared both subjectively and objectively, with the genetic algorithm method, neuro-fuzzy method and also with the modified pulse coupled neural network. The results show that the proposed hybrid intelligent method performs better when compared to the existing computational and hybrid intelligent methods.     

An efficient dynamic multicast traffic-grooming algorithm for WDM networks

With the growth of multi-granularity multicast applications, there comes into being a huge gap between the bandwidth of a wavelength provided and a multicast traffic required in the wavelength division multiplexing (WDM) networks. The dynamic multicast traffic-grooming is an effective way for WDM networks to improve the wavelength utilization and decrease the traffic blocking probability. A novel switching node architecture with the multicast switching matrix and traffic-grooming fabric is studied in the paper. Then, an efficient dynamic multicast traffic-grooming algorithm is proposed for the architecture. According to the ratio of network available grooming port number to network transceiver number, the proposed algorithm estimates whether the traffic-grooming port is a scarce resource for input traffic and chooses the appropriate grooming strategy. If the traffic-grooming port is scarce, the minimized use grooming port strategy is designed for the coming traffic. On the contrary, the minimized use node transceiver strategy is applied for the coming traffic. Simulation results show that the proposed algorithm can groom traffic efficiently with low blocking probability and high network throughput constraint by limiting number of node transceivers and grooming ports.     

高校WLAN优化方案研究

在规模应用无线局域网的网络中,网络优化是不可缺少的步骤。对重庆各大高校WLAN优化所使用的各种方案进行了总结及简单分析,并以楼层构造较特殊的某高校12舍为例,通过频点规划、功率控制和天线改造等优化方法,使得该宿舍楼在指标和业务测试结果中均有明显提升。     

Mitigation of the inter-node interference in multi-antenna full-duplex networks

When multiple single-antenna half-duplex (HD) nodes communicate with a full-duplex (FD) base station equipped with multiple transmit and receive antennas, the uplink nodes would generate inter-node interference (INI) on the downlink nodes. We propose a base station assisted INI suppression scheme. The scheme is to design a proper amplify-and-forward matrix at the base station so that the sum achievable rate of the uplink and downlink is maximized. We derive the close-form expression of the amplify-and-forward matrix, which is the product of a parameter optimization and a zero-forcing beamforming (ZFBF) matrices. Finally, we investigate the performance of the proposed INI suppression scheme in a single cell.     

Ultrafast fabrication of nanostructure WO3 photoanodes by hybrid microwave annealing with enhanced photoelectrochemical and photoelectrocatalytic activities

Tungsten oxide (WO₃) nanoplate films with a relatively rough surface were successfully fabricated via a simple hydrothermal method, followed by the hybrid microwave annealing (HMA) treatment only a few minutes for the first time. The microscopic morphology and phase were characterized by scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM), Raman spectrum and X-ray diffraction (XRD). Photoelectrochemical measurements demonstrated that the obtained WO₃ film of microwave processing for 11 min exhibited the photocurrent density of 1.60 mA/cm² at 1.2 V (vs. Ag/AgCl) and the IPCE value of 55% at 355 nm under an applied voltage of 1.0 V (vs. Ag/AgCl), which were about 3 and 2.5 times compared with the WO₃ film prepared by the conventional annealing method, respectively. Moreover, the WO₃-HMA films were applied to the versatile photoanode-driven photoelectrochemical system for CO₂ reduction into formic acid. The maximum formic acid generation rate and faradaic efficiency of the WO₃-HMA films were 9.21 μmol h^?1 cm^?2 and 45.45%, respectively. This study provided a facial and rapid method to synthesize the high-performance WO₃ photoanodes with better photoelectrochemical and photoelectrocatalytic activities.     

Risk assessment in ramps for heavy vehicles—A French study

This paper presents the results of a study dealing with the risk for heavy vehicles in ramps. Two approaches are used. On one hand, statistics are applied on several accidents databases to detect if ramps are more risky for heavy vehicles and to define a critical value for longitudinal slope. χ² test confirmed the risk in ramps and statistical analysis proved that a longitudinal slope superior to 3.2% represents a higher risk for heavy vehicles. On another hand, numerical simulations allow defining the speed profile in ramps for two types of heavy vehicles (tractor semi-trailer and 2-axles rigid body) and different loads. The simulations showed that heavy vehicles must drive more than 1000 m on ramps to reach their minimum speed. Moreover, when the slope is superior to 3.2%, tractor semi-trailer presents a strong decrease of their speed until 50 km/h. This situation represents a high risk of collision with other road users which drive at 80–90 km/h. Thus, both methods led to the determination of a risky configuration for heavy vehicles: ramps with a length superior to 1000 m and a slope superior to 3.2%. An application of this research work concerns design methods and guidelines. Indeed, this study provides threshold values than can be used by engineers to make mandatory specific planning like a lane for slow vehicles.     

A comprehensive theoretical study of halide perovskites ABX3

Solar cells based on halide perovskites have recently been attractive due to their excellent power conversion efficiency (PCE), lower cost and simple manufacture. Here, a series of halide perovskites (ABX₃: A = CH₃NH₃, CH(NH₂)₂, Cs, Rb; B = Pb, Sn, Ge; X = I, Br, Cl, F) were investigated by Density Functional Theory (DFT) calculations, together with Shockley-Queisser Maximum Solar Cell Efficiency (S-Q) and Spectroscopic Limited Maximum Efficiency (SLME) mathematical models. The results indicate that: the electronic structure of germanium perovskites bears a close similarity to that of lead perovskites with a small energy difference between the nonbonding orbital and antibonding orbitals, but with a large energy difference comparing with that of tin perovskites (0.6–1.7 eV for CsGeI₃ at Z point of the Brillouin zone, 0.7–1.4 eV for CH₃NH₃PbI₃ and 1.4–2.2 eV for CH₃NH₃SnI₃ at R point of the Brillouin zone), which is attributable to the atomic level, where the 4s orbital energy of Ge (−11.5 eV) is close to the 6s orbital energy of Pb (−11.6 eV), but the 5s orbital energy of Sn (−10.1 eV) is significantly high. Therefore, germanium perovskites possess as high absorption coefficient around solar spectrum as lead perovskites, while tin perovskites only have low absorption coefficient, which makes the short-circuit current of CsGeI₃ and CH₃NH₃PbI₃ (0.017 Acm⁻² and 0.016 Acm⁻², simulated by SLME with a 200 nm absorber under AM1.5G) are higher than that of CH₃NH₃SnI₃ (0.015 Acm⁻²) even if the bandgap of CsGeI₃ and CH₃NH₃PbI₃ (1.51 eV and 1.55 eV) are larger than that of CH₃NH₃SnI₃ (1.21 eV). Meanwhile, the effective mass of electrons and holes are approximate for germanium perovskites and lead perovskites (0.14:0.19 for CsGeI₃ and 0.12:0.12 for CH₃NH₃PbI₃), indicating a balanced electrons and holes transport, whereas the electrons transport is much slower than the holes transport for tin perovskites due to the effective mass of electron is much larger than that of hole (0.17:0.04 for CH₃NH₃SnI₃). As a result, the PCE of CsGeI₃ (27.9%) and CH₃NH₃PbI₃ (26.7%) is higher than that of CH₃NH₃SnI₃ (19.9%).     

A rapid hybrid algorithm for image restoration combining parametric Wiener filtering and wave atom transform

Image restoration refers to removal or minimization of known degradations in an image. This includes de-blurring images degraded by the limitations of sensors or source of captures in addition to noise filtering and correction of geometric distortion due to sensors. There are several classical image restoration methods such as Wiener filtering. To find an estimate of the original image, Wiener filter requires the prior knowledge of the degradation phenomenon, the blurred image and the statistical properties of the noise process. In this work, we propose a new rapid and blind algorithm for image restoration that does not require a priori knowledge of the noise distribution. The degraded image is first de-convoluted in Fourier space by parametric Wiener filtering, and then, it is smoothed by the wave atom transform after setting the threshold to its coefficients. Experiment results are significant and show the efficiency of our algorithm compared with other techniques in use.