Properties of Cr:LiSrAIF(6) crystals for laser operation

We have performed several physical and optical measurements on the Cr:LiSAF (LiSrAlF(6)) laser material that are relevant to its laser performance, including thermal and mechanical properties, water durabilities, and Auger upconversion constants. The expansion coefficient, Young's modulus, fracture toughness, thermal conductivity, and heat capacity are all used to determine an overall thermomechanical figure of merit for the crystal. An investigation of the water durability suggests that the cooling solution should be maintained at pH = 7 to ameliorate problems associated with water dissolution. The Auger constant was found to become much more significant at higher Cr doping, in which excited-state migration leads to a substantial increase in the upconversion rate. We propose a design for a 50-W Cr:LiSAF laser system that is based on a detailed knowledge of all the relevant material parameters.     

In Situ Artificial Hybrid SEI Layer Enabled High-Performance Prelithiated SiOx Anode for Lithium-Ion Batteries

Considered the promising anode material for next-generation high-energy lithium-ion batteries, SiO_x has been slow to commercialize due to its low initial Coulombic efficiency (ICE) and unstable solid electrolyte interface (SEI) layer, which leads to reduced full-cell energy density, short cycling lives, and poor rate performance. Herein, a novel strategy is proposed to in situ construct an artificial hybrid SEI layer consisting of LiF and Li₃Sb on a prelithiated SiO_x anode via spontaneous chemical reaction with SbF₃. In addition to the increasing ICE (94.5%), the preformed artificial SEI layer with long-term cycle stability and enhanced Li⁺ transport capability enables a remarkable improvement in capacity retention and rate capability for modified SiO_x. Furthermore, the full cell using Li(Ni_0.8Co_0.1Mn_0.1)O₂ and a pre-treated anode exhibits high ICE (86.0%) and capacity retention (86.6%) after 100 cycles at 0.5 C. This study provides a fresh insight into how to obtain stable interface on a prelithiated SiO_x anode for high energy and long lifespan lithium-ion batteries.     

MXene Functionalized,Highly Breathable and Sensitive Pressure Sensors with Multi-Layered Porous Structure

Breathable, flexible, and highly sensitive pressure sensors have drawn increasing attention due to their potential in wearable electronics for body-motion monitoring, human-machine interfaces, etc. However, current pressure sensors are usually assembled with polymer substrates or encapsulation layers, thus causing discomfort during wearing (i.e., low air/vapor permeability, mechanical mismatch) and restricting their applications. A breathable and flexible pressure sensor is reported with nonwoven fabrics as both the electrode (printed with MXene interdigitated electrode) and sensing (coated with MXene/silver nanowires) layers via a scalable screen-printing approach. Benefiting from the multi-layered porous structure, the sensor demonstrates good air permeability with high sensitivity (770.86–1434.89 kPa⁻¹), a wide sensing range (0–100 kPa), fast response/recovery time (70/81 ms), and low detection limit (≈1 Pa). Particularly, this sensor can detect full-scale human motion (i.e., small-scale pulse beating and large-scale walking/running) with high sensitivity, excellent cycling stability, and puncture resistance. Additionally, the sensing layer of the pressure sensor also displays superior sensitivity to humidity changes, which is verified by successfully monitoring human breathing and spoken words while wearing a sensor-embedded mask. Given the outstanding features, this breathable sensor shows promise in the wearable electronic field for body health monitoring, sports activity detection, and disease diagnosis.     

抑制图像非语义信息的通用后门防御策略

目的 后门攻击已成为目前卷积神经网络所面临的重要威胁。然而,当下的后门防御方法往往需要后门攻击和神经网络模型的一些先验知识,这限制了这些防御方法的应用场景。本文依托图像分类任务提出一种基于非语义信息抑制的后门防御方法,该方法不再需要相关的先验知识,只需要对网络的输入进行编解码处理就可以达到后门防御的目的。方法 核心思想是在保持图像语义不改变的同时,尽量削弱原始样本中与图像语义不相关的信息,以此抑制触发器。通过在待保护模型前添加一个即插即用的U型网络(即信息提纯网络)来实现对图像非语义信息的抑制。其输入是干净的初始样本,输出命名为强化样本。具体的训练过程中,首先用不同的训练超参数训练多个结构不一的干净分类器,然后在保持强化样本被上述分类器正确分类的前提下,优化信息提纯网络使强化样本和原始样本之间的差异尽可能地大。结果 实验在MNIST、CIFAR10和Image Net10数据集上进行。实验结果显示,经过信息提纯网络编解码后,干净样本的分类准确率略有下降,后门攻击成功率大幅降低,带有触发器的样本以接近干净样本的准确率被正确预测。结论 提出的非语义信息抑制防御方法能够在不需要相关先验知识的...     

Development,integration, and field evaluation of an autonomous citrus-harvesting robot

Citrus harvesting is a labor-intensive and time-intensive task. As the global population continues to age, labor costs are increasing dramatically. Therefore, the citrus-harvesting robot has attracted considerable attention from the business and academic communities. However, robotic harvesting in unstructured and natural citrus orchards remains a challenge. This study aims to address some challenges faced in commercializing citrus-harvesting robots. We present a fully integrated, autonomous, and innovative solution for citrus-harvesting robots to overcome the harvesting difficulties derived from the natural growth characteristics of citrus. This solution uses a fused simultaneous localization and mapping algorithm based on multiple sensors to perform high-precision localization and navigation for the robot in the field orchard. Besides, a novel visual method for estimating fruit poses is proposed to cope with the randomization of citrus growth orientations. Further, a new end-effector is designed to improve the success and conformity rate of citrus stem cutting. Finally, a fully autonomous harvesting robot system has been developed and integrated. Field evaluations showed that the robot could harvest citrus continuously with an overall success rate of 87.2% and an average picking time of 10.9 s/fruit. These efforts provide a solid foundation for the future commercialization of citrus-harvesting robots.     

Effect of Nano Potassium Fertilizer on Cucumber Amino Acid Component,Volatile Metabolite Components and GLN Family Genes Expression

Wireless Personal Communications - To investigate the effect of nano-potassium silicate on the expression of glutamine (GLN) family gene, amino acid (AAs) componentand volatile metabolites (VMs)...     

Global contextual guided residual attention network for salient object detection

High-level semantic features and low-level detail features matter for salient object detection in fully convolutional neural networks (FCNs). Further integration of low-level and high-level features increases the ability to map salient object features. In addition, different channels in the same feature are not of equal importance to saliency detection. In this paper, we propose a residual attention learning strategy and a multistage refinement mechanism to gradually refine the coarse prediction in a scale-by-scale manner. First, a global information complementary (GIC) module is designed by integrating low-level detailed features and high-level semantic features. Second, to extract multiscale features of the same layer, a multiscale parallel convolutional (MPC) module is employed. Afterwards, we present a residual attention mechanism module (RAM) to receive the feature maps of adjacent stages, which are from the hybrid feature cascaded aggregation (HFCA) module. The HFCA aims to enhance feature maps, which reduce the loss of spatial details and the impact of varying the shape, scale and position of the object. Finally, we adopt multiscale cross-entropy loss to guide network learning salient features. Experimental results on six benchmark datasets demonstrate that the proposed method significantly outperforms 15 state-of-the-art methods under various evaluation metrics.

     

Dendrite‐Free Lithium Deposition via Flexible‐Rigid Coupling Composite Network for LiNi0.5Mn1.5O4/Li Metal Batteries

Notorious lithium dendrite causes severe capacity fade and harsh safety issues of lithium metal batteries, which hinder the practical applications of lithium metal electrodes in higher energy rechargeable batteries. Here, a kind of 3D‐cross‐linked composite network is successfully employed as a flexible‐rigid coupling protective layer on a lithium metal electrode. During the plating/stripping process, the composite protective layer would enable uniform distribution of lithium ions in the adjacent regions of the lithium electrode, resulting in a dendrite‐free deposition at a current density of 2 mA cm^?2. The LiNi_0.5Mn_1.5O₄‐based lithium metal battery presents an excellent cycling stability at a voltage range of 3.5–5.0 V with the induction of 3D‐cross‐linked composite protective layer. From an industrial field application of view, thin lithium metal electrodes (40 µm, with 4 times excess lithium) can be used in LiNi_0.5Mn_1.5O₄ (with industrially significant loading of 18 mg cm^?2 and 2.6 mAh cm^?2)‐based lithium metal batteries, which reveals a promising opportunity for practical applicability in high energy lithium metal batteries.     

Pulse colliding in a self-mode-locked ring-cavity ti:sapphire laser

A new self-mode-locked ring-cavity Ti:sapphire laser is described that is self-mode locked in both unidirectional and bidirectional operations. We found that clockwise and counterclockwise pulses collide with each other at the Ti:sapphire rod when the laser is mode locked in a bidirectional operation. Spectrum narrowing and pulse broadening were found in bidirectional rather than unidirectional mode-locked operation. This is explained by the performance of a transient grating in the gain medium that restricts oscillation to a narrow spectral range.     

Detection and confirmation of N-nitrosodialkylamines using liquid chromatography-electrospray ionization coupled on-line with a photolysis reactor

Simultaneous detection and confirmation of several N-nitrosodialkylamines are accomplished by on-line coupling of a photolysis reactor with an HPLC-electrospray ionization mass spectrometer. Several parameters such as irradiation wavelength, irradiation time, mobile-phase composition, and pH, as well as different organic acid modifiers are investigated, and their impact on the detection of the N-nitrosodialkylamine-acid complex and its dissociative photolysis products is presented here. Additionally, the type of structural information obtained from the photolytic processes of N-nitrosodialkylamines is compared to that obtained by using in-source collision-induced dissociation. To demonstrate the potential of this technique, six N-nitrosodialkylamines are studied to determine the linearity of the response, the limits of detection and confirmation, and the reproducibility. The technique's versatility is also exhibited by utilizing negative-ion mode as a complementary means for analysis of the compounds. Finally, an illustrative application for N-nitrosodimethylamine analysis in beer is described.