Highly Reversible Li–Se Batteries with Ultra-Lightweight N,S-Codoped Graphene Blocking Layer

The desire for practical utilization of rechargeable lithium batteries with high energy density has motivated attempts to develop new electrode materials and battery systems. Here, without additional binders we present a simple vacuum filtration method to synthesize nitrogen and sulfur codoped graphene(N,S-G) blocking layer, which is ultra-lightweight, conductive, and free standing. When the N,S-G membrane was inserted between the catholyte and separator, the lithium–selenium(Li–Se)batteries exhibited a high reversible discharge capacity of 330.7 mAh g^(-1) at 1 C(1 C = 675 mA g^(-1)) after 500 cycles and high rate performance(over 310 mAh g^(-1) at 4 C) even at an active material loading as high as ～5 mg cm^(-2). This excellent performance can be ascribed to homogenous dispersion of the liquid active material in the electrode, good Li^+-ion conductivity, fast electronic transport in the conductive graphene framework, andstrong chemical confinement of polyselenides by nitrogen and sulfur atoms. More importantly, it is a promising strategy for enhancing the energy density of Li–Se batteries by using the catholyte with a lightweight heteroatom doping carbon matrix.

Properties and mechanism of red mud in preparation of ultra-lightweight sludge-red mud ceramics

New ultra-lightweight sludge-red mud ceramics(ULS-RMC) were prepared by red mud(RM),clay and dried sewage sludge(DSS).The properties and mechanism of RM in the preparation of ULS-RMC were discussed.The chemical components,thermal properties and mineral phases of RM were determined by energy dispersive X-ray(EDX),differential scanning calorimetry/thermal gravimetric analysis(DSC/TGA) and X-ray diffraction(XRD),respectively.Constant dosage of DSS to clay and different amounts of RM were utilized in the preparation of ULS-RMC.Physical properties test(bulk density,grain density,water absorption and expansion ratio),XRD and scanning electron microscopy(SEM) were employed to characterize the ULS-RMC.The results show that RM exhibits high hydroscopic property and good water-retention property,and bloating property and fluxing property of RM are caused by abound of gaseous components and flux,respectively.The two chemical properties are utilized to discuss the mineral phases and microstructures differences between ULSC and ULS-RMC.

Preparation and Bloating Mechanism of Porous Ultra-lightweight Ceramsite by Dehydrated Sewage Sludge and Yellow River Sediments

To solve the disposal problems of solid wastes, dehydrated sewage sludge and Yellow River sediments were tested as components for production of ultra-lightweight ceramsite. The effects of Yellow River sediments addition on the characteristics of ceramsite were investigated. Ceramsite with different Yellow River sediments additions was characterized using thermal analysis, X-ray diffraction, morphological structures analyses, pore size distributions and porosity analyses. Chemical components, especially ratios of Si O2 ＋ Al2O3/Flux, were used to explain the glassy shell formation, physical properties and pores distribution of ultralightweight ceramsite; physical forces for instance expansion force and frictional resistance which combined with Si O2 ＋ Al2O3/Flux ratios were used to explain the bloating mechanism. Results showed that the maximum addition of Yellow River sediments for making ultra-lightweight ceramsite was 35%. Macropores（between 0.226 μm and 0.554 μm） of ultra-lightweight ceramsite were dominant in the pore structures of ultra-lightweight ceramsite and its porosity was up to 67.7%. Physical force of expansion force was constant with the variation of Yellow River sediments content and physical force of frictional resistance was decreased with the increase of Yellow River sediments addition. The relationship between expansion and frictional resistance could determine the expansion rate of ceramsite. Larger pores inside the ceramsite bodies could be obtained as Yellow River sediments additions ranged from 10% to 30%. Ceramsite with higher Yellow River sediments additions of 40%（Si O2 ＋ Al2O3/Flux ratios 4.25） became denser and have lower porosity. Crystal components analysis proved that the sintering process made some components of raw materials transfer into other crystals having better thermostability.

RUAP:Random Rearrangement Block Matrix-Based Ultra-Lightweight RFID Authentication Protocol for End-Edge-Cloud Collaborative Environment

Cloud computing provides powerful processing capabilities for large-scale intelligent Internet of things(IoT)terminals.However,the massive realtime data processing requirements challenge the existing cloud computing model.The edge server is closer to the data source.The end-edge-cloud collaboration offloads the cloud computing tasks to the edge environment,which solves the shortcomings of the cloud in resource storage,computing performance,and energy consumption.IoT terminals and sensors have caused security and privacy challenges due to resource constraints and exponential growth.As the key technology of IoT,Radio-Frequency Identification(RFID)authentication protocol tremendously strengthens privacy protection and improves IoT security.However,it inevitably increases system overhead while improving security,which is a major blow to low-cost RFID tags.The existing RFID authentication protocols are difficult to balance overhead and security.This paper designs an ultra-lightweight encryption function and proposes an RFID authentication scheme based on this function for the end-edge-cloud collaborative environment.The BAN logic proof and protocol verification tools AVISPA formally verify the protocol’s security.We use VIVADO to implement the encryption function and tag’s overhead on the FPGA platform.Performance evaluation indicates that the proposed protocol balances low computing costs and high-security requirements.

Progress on Preparation and Characteristics of Ultra-lightweight Foam Concrete

With the increase in global warming,building energy saving becomes a principal policy for most countries.About 70%of the energy consumption loss of buildings is through the external walls of the buildings.Ultra-lightweight foam concretes with dry density of 150-300 kg·m-3 as the thermal insulation materials have been commercially prepared and used in building insulation engineering in China.This paper reports the raw materials and procedures for preparation of ultralightweight foam concretes by chemical foaming(UFC-C)and physical foaming(UFC-P).The characteristics of the air-voids structure,the mechanical properties,the water absorption,the thermal conductivity and the fire resistance of UFC-C and UFC-P were summarized in this paper.Based on existing research progress,the future research works were presented.

High-areal-capacity/power lithium metal microbattery configuration based on the mechanically flexible,ultra-lightweight,nanocellulose framework

The ubiquitous implementation of integrated microelectronics requires the on-chip power sources featured with the lightweight configuration design,high areal-capacity-loadings as well as facile reaction kinetics that beyond the current available microbattery prototypes.Herein,this study constructs a mechanically flexible,nanocellulose fiber(NCF)reinforced microbattery configuration,which consists of metal-organic frameworks(ZIF-8)modified NCF as the separator(MOF@NCF),the carbonized MOF@NCF as the metallic deposition substrate(c-MOF@NCF)as well as gradient-structured LiFePO4 particles infiltrated in the NCF matrix(LFP@NCF)as the cathode.The film-stacked,integrated NCF-based microbattery prototype not only achieves the facile reaction kinetics with homogenized,dendrite-free Li metal deposition at high-capacity-loadings(2 mAh·cm^(-2)),but also eliminates the necessary use of metallic current collector to maximize the electroactive mass ratio,which therefore enables the high energy density of 6.8 mWh·cm^(-2)at the power output of 1.36 mW·cm^(-2)as well as the robust cyclability upon various geometric flexing states.This study presents a quantum leap towards the facile reaction kinetics and multi-scale interfacial stability for the flexible microbattery construction that based on the sustainable utilization of bio-scaffolds.

VMMAO-YOLO:an ultra-lightweight and scale-aware detector for real-time defect detection of avionics thermistor wire solder joints

The quality of the exposed avionics solder joints has a significant impact on the stable operation of the inorbit spacecrafts.Nevertheless,the previously reported inspection methods for multi-scale solder joint defects generally suffer low accuracy and slow detection speed.Herein,a novel real-time detector VMMAO-YOLO is demonstrated based on variable multi-scale concurrency and multi-depth aggregation network(VMMANet)backbone and“one-stop”global information gather-distribute(OS-GD)module.Combined with infrared thermography technology,it can achieve fast and high-precision detection of both internal and external solder joint defects.Specifically,VMMANet is designed for efficient multi-scale feature extraction,which mainly comprises variable multi-scale feature concurrency(VMC)and multi-depth feature aggregation-alignment(MAA)modules.VMC can extract multi-scale features via multiple fix-sized and deformable convolutions,while MAA can aggregate and align multi-depth features on the same order for feature inference.This allows the low-level features with more spatial details to be transmitted in depth-wise,enabling the deeper network to selectively utilize the preceding inference information.The VMMANet replaces inefficient highdensity deep convolution by increasing the width of intermediate feature levels,leading to a salient decline in parameters.The OS-GD is developed for efficacious feature extraction,aggregation and distribution,further enhancing the global information gather and deployment capability of the network.On a self-made solder joint image data set,the VMMAOYOLO achieves a mean average precision mAP@0.5 of 91.6%,surpassing all the mainstream YOLO-series models.Moreover,the VMMAO-YOLO has a body size of merely 19.3 MB and a detection speed up to 119 frame per second,far superior to the prevalent YOLO-series detectors.

掺轻质砂超高性能混凝土的轴拉力学性能

为研究轻质砂对不同试件尺寸下超高性能混凝土(ultra high performance concrete,UHPC)拉伸应变强化性能的影响,采用轻质砂对原黄砂进行等体积替代,完成9组不同轻质砂体积率(0~35%)和不同试件厚度(30~100 mm)的单轴拉伸试验,并同步进行声发射实时探伤测试。结果表明:轻质砂体积率对UHPC弹性极限点对应应力和对应应变的影响较小,但轻质砂体积率由0增加到35%时,UHPC的极限抗拉强度和极限拉应变分别由10.6 MPa和2.35×10^(-3)提高到了19.4 MPa和4.3×10^(-3);轻质砂体积率大于15%时,UHPC的应变强化程度得到显著提升,试件内部产生的损伤点数更多且分布更均匀,展现出良好的裂缝控制能力;在相同轻质砂体积率下,UHPC的应变强化程度随试件厚度的增加而降低,且试件内部的损伤点趋于集中,表现出明显的尺寸效应。

超高温陶瓷复合材料研究进展

随着高速飞行器朝着更宽空域、更长时间和更高速度的方向发展,对飞行器的鼻锥、前缘和发动机燃烧室等关键结构的热防护性能提出了更加严苛的要求,发展在极端环境下使用的高性能热防护材料是当前的研究重点。超高温陶瓷复合材料具有优异的抗氧化烧蚀性能,是一类极具应用潜力的非烧蚀型热防护材料。然而,本征脆性问题限制了超高温陶瓷复合材料的工程化应用,需通过组分结构调控对其进行强韧化。同时,飞行器有效载荷提升也对超高温陶瓷复合材料提出了轻量化的要求。本文系统概述了超高温陶瓷复合材料近年来取得的主要研究进展,包括压力烧结、泥浆浸渍、前驱体浸渍裂解、反应熔渗、化学气相渗透/沉积与“固-液”组合工艺等制备方法,颗粒、晶须、软相物质、短切纤维和连续纤维等强韧化方法及其机制,抗氧化烧蚀性能与机理,以及轻量化设计等。讨论了超高温陶瓷复合材料组分、微结构和性能之间的关系,并指出了超高温陶瓷复合材料目前存在的挑战以及未来的发展趋势。

机载液晶显示模组轻量化及低功耗技术研究

针对机载设备轻量化和低功耗的要求,提出了基于支框的机载液晶显示模组加固方式,采用有限元迭代仿真计算,优化散热板加强筋设计,减轻结构重量;基于2 mm超薄导光板,通过LED选型、LED排布对现行背光灯板进行设计改进,提升了超薄导光板光耦合效率。经计算和测试验证,改进后的方法可显著降低液晶显示模组背光功耗。

A novel approach to with a preparing ultra-lightweight ceramsite large amount of fly ash

The disposal of fly ash has become a serious problem in China due to its rapid increase in volume in recent years.The most common method of fly ash disposal is solidification-stabilization-landfill,and the most common reuse is low-value-added building materials.A novel processing method for preparing ultra-lightweight ceramsite with fly ash was developed.The results show that the optimal parameters for preparation of ultra-lightweight ceramsite are as follows:mass ratio of fly ash:kaolin:diatomite=80:15:5,preheating temperature of 800℃,preheating time of 5 min,sintering temperatiire of 1220℃,and sintering time of 10 min.The expansion agent is perlite,at 10 wt.% addition.Finally,a ceramsite with bulk density of 340 kg/m3,particle density of 0.68 g/cm3,and cylinder compressive strength of 1.02 MPa was obtained.Because of its low density and high porosity,ultra-lightweight ceramsite has excellent thermal insulation performance,and its strength is generally low,so it is usually used in the production of thermal insulation concrete and its products.The formation of a liquid-phase component on the surface,and generation of a gas phase inside ceramsite during the sintering process,make it possible to control the production of the suitable liquid phase and gas in this system,resulting in an optimization of the expansion behavior and microstructure of ceramsite.These characteristics show the feasibility of industrial applications of fly ash for the production of ultralightweight ceramsite,which could not only produce economic benefits,but also conserve land resources and protect the environment.

Ultra-lightweight and wide field of view augmented reality virtual retina display based on optical fiber projector and volume holographic lens

A novel see-through virtual retina display(VRD) system is proposed in this Letter. An optical fiber projector is used as the thin-light-beam source, which is modified from a laser scan projector by separating the laser sources and the scan mechanical structure. A synthetic aperture method is proposed for simple, low-cost fabrication of a volume holographic lens with large numerical aperture. These two key performance-enhanced elements are integrated into a lightweight and ordinary-glasses-like optical see-through VRD system. The proposed VRD system achieves a weight of 30g and a diagonal field of view of 60°.

钢框架岩棉夹芯板超高防火隔墙耐火与稳定性能研究

为满足大型厂房对轻质超高防火隔墙的需求,提出了一种钢框架岩棉夹芯板超高防火隔墙,并对其耐火性与稳定性进行研究。采用ISO-834标准升温曲线的加热方法,对缩尺比例为1∶0.3岩棉夹芯板防火隔墙进行单面受火试验。并基于有限元软件ABAQUS建立缩尺模型与足尺模型,研究了防火隔墙防火优化前后两种方案下受火面与背火面的温度场变化规律。结果表明:缩尺试验模型与缩尺有限元模型的温度和形变基本吻合;足尺有限元模型的岩棉夹芯板超高防火隔墙在防火优化后,背火面最高温度降低,最大形变降低了75.5%,耐火性与稳定性得到大幅改善,并满足《建筑构件耐火试验方法》对于防火隔墙隔热性和完整性要求。在防火隔墙设计方面,容重为50 kg/m^(2)的钢框架岩棉夹芯板超高防火隔墙,跨度方向每8 m需设一根钢柱,高度方向每3.6 m需设一根钢梁。

养护制度对轻集料超高性能混凝土力学性能的影响

研究了标准养护、蒸汽养护、干热养护、蒸压养护等4种养护制度的升温速率、恒温时间、恒温温度等养护参数对轻集料超高性能混凝土(LUHPC)强度的影响,确定了最佳养护制度,并研究了养护制度对LUHPC弯曲韧性的影响。结果表明:高温养护能加快LUHPC的水化速率,提高早期强度,然而过高的养护温度会导致LUHPC力学性能下降;蒸汽养护与标准养护下LUHPC的力学性能无明显差异;蒸压养护与干热养护能够明显提高LUHPC的峰值挠度与峰值荷载,干热养护下LUHPC的残余韧性最高。

机载超轻量化卷积神经网络加速器设计

卷积神经网络庞大的权重参数和复杂的网络层结构,使其计算复杂度过高,所需的计算资源和存储资源也随着网络层数的增加而快速增长,难以在资源和功耗有严苛要求的机载嵌入式计算系统中部署,制约了机载嵌入式计算系统朝着高智能化发展。针对资源受限的机载嵌入式计算系统对超轻量化智能计算的需求,提出一套全流程的卷积神经网络模型优化加速方法,在对算法模型进行超轻量化处理后,通过组合加速算子搭建卷积神经网络加速器,并基于FPGA开展网络模型推理过程的功能验证。结果证明:本文搭建的加速器能够显著降低硬件资源占用率,获得良好的算法加速比,对机载嵌入式智能计算系统设计具有重要意义。

飞机拦阻系统用超轻质混凝土制备与性能研究

文中建立“P·I水泥+惰性掺合料”胶凝材料体系制备飞机拦阻系统用超轻质混凝土,并与P·II水泥和硫铝酸盐水泥进行对比。研究结果表明,P·I水泥体系制备的超轻质混凝土气孔孔径集中分布在1.0~2.0 mm,60~150 d溃缩强度变化率为4.81%,半溃缩能软化系数和抗冻系数分别为0.67和0.70,超轻质混凝土力学性能稳定性显著提高。

超轻量人脸关键点检测算法

随着深度学习网络研究的深入和网络模型精度的提高,网络层数及深度在逐渐增加,导致计算量增大。同时,基于深度学习模型人脸关键点检测在嵌入式设备上部署的需求,轻量化、高效和准确的网络模型成为研究关键。因此,本文设计了一个基于Ghost Model块和Ghost Bottleneck架构的超轻量型人脸关键点检测算法,在确保网络精度的同时,尽可能减小网络模型大小,降低计算量。在网络宽度因子为1X的情况下,与现有表现最好的轻量化网络模型PFLD 1X相比,归一化平均误差降低了7%,参数量减小了36%;在宽度因子为0.25X的情况下,本论文提出的网络模型大小仅420 KB,归一化平均误差降低了6.6%,参数量减小了25%。

陶砂和钢纤维对轻质超高性能混凝土的影响

为利用陶砂与钢纤维做骨架制备出轻自重与超高强度协同设计的轻质超高性能混凝土(LUHPC),研究了不同掺量与粒径的陶砂、不同掺量与长度的钢纤维对LUHPC工作性能、力学性能和收缩性能的影响规律,并通过SEM对其微结构进行分析。试验结果表明,增加陶砂的掺量可以有效减少LUHPC的表观密度,但力学性能也会随之下降;钢纤维掺量的增加显著提高了LUHPC的力学性能,且抗折强度的提升效果最为明显,在体积掺量为2%的情况下,增加钢纤维长度会导致LUHPC的工作性能降低、抗折强度提升;采用粒径为0.075~4.75 mm连续级配的陶砂和长度为13 mm的钢纤维制备的LUHPC综合性能最佳。

磷尾矿轻质超高强混凝土配制及其微观界面特性

该文以自制的筒压强度为7.2 MPa的800级磷尾矿轻质陶粒作集料,并通过添加适量硅粉、粉煤灰替换水泥作为胶凝材料,配制轻质超高强混凝土。研究了胶凝材料用量、轻细集料掺量以及浆集比对轻质超高强混凝土工作性能、力学性能及密度的影响,得出了最优配合比。在此基础上,采用扫描电镜-X射线能谱(SEM-EDX)和显微硬度计研究了轻质超高强混凝土微观界面过渡区的结构特征,并与普通高强混凝土比较。结果表明:随着胶凝材料用量以及浆集比的增加,坍落度、抗压强度、干表观密度均逐渐升高;而随着轻细集料掺量增加,各项性能均呈现出下降的趋势。当胶凝材料中水泥、粉煤灰、硅灰用量比例为70%、15%、15%时,其总用量为1110 kg·m^(-3),水胶比0.19,减水剂掺量1.9%,浆集比1.80,轻质集料掺量占集料总量80%,制备的轻质超高强混凝土各项性能最优,其坍落度为225 mm,28 d抗压强度达到了115.4 MPa,干表观密度为1875 kg·m^(-3)。在轻细集料的释水内养护作用下,轻质超高强混凝土的微观界面区结构较普通高强混凝土的更加致密,形成了拱壳结构,界面区内的显微硬度平均值为89.7MPa,高于水泥石基体的显微硬度,其界面过渡区宽度约为20~25μm。

18000 r/min超高转速轻量化新能源汽车电机轴开发

随着新能源汽车电机转速的不断提升,电机轴面临更加苛刻的刚强度、耐久性和抗过挠要求。通过合理选材,并辅之以轻量化设计、磁环境优化、工艺匹配等方法,成功开发出满足18 000 r/min服役要求的电机轴。新电机轴在质量减少25.5%时,其自由模态频率、扭转强度、扭转疲劳寿命、台架试验过程中的噪声和温升等性能指标均不低于原低转速电机轴。通过对材料成分及工艺的优化以增强基体的强韧性有利于提升电机轴的抗扭及抗疲劳性能。通过轻量化结构设计和反向辅助磁场设计,可降低电机轴在高速旋转过程中承受的单边磁拉力、离心力、系统重力等,也有利于提升电机轴的抗挠能力,进而提升电机的耐久性和车辆的舒适性。