Extraordinary Compatibility to Mass Loading and Rate Capability of Hierarchically Porous Carbon Nanorods Electrode Derived from the Waste Tire Pyrolysis Oil

The conversion of waste tire pyrolysis oil(WTPO)into S-doped porous carbon nanorods(labeled as WPCNs)with hierarchical pore structure is realized by a simple template-directed approach.The specific surface area of as-obtained porous carbon nanorods can reach up to 1448 m^(2) g^(−1) without the addition of any activating agent.As the capacitive electrode,WPCNs possess the extraordinary compatibility to capacitance,different electrolyte systems as well as long-term cycle life even at a commercial-level areal mass loading(10 mg cm^(−2)).Besides,only an extremely small capacitance fluctuation is observed under the extreme circumstance(−40 to 80℃),reflecting the excellent high-and low-temperature performance.The relationship between the pore structure and capacitive behavior is analyzed by comparing WPCNs with mesopores-dominated asphalt-derived porous carbon nanorods(APCNs)and micropores-dominated activated carbon.The molecular dynamics simulation further reveals the ion diffusion and transfer ability of the as-prepared carbon materials under different pore size distribution.The total ion flow(NT)of WPCNs calculated by the simulation is obviously larger than APCNs and the N_(T) ratio between them is similar with the experimental average capacitance ratio.Furthermore,this work also provides a valuable strategy to prepare the electrode material with high capacitive energy storage ability through the high value-added utilization of WTPO.

High mass loading NiCo_(2)O_(4) with shell-nanosheet/core-nanocage hierarchical structure for high-rate solid-state hybrid supercapacitors

Rational design of advanced structure for transition metal oxides(TMOs) is attractive for achieving high-performance supercapacitors.However, it is hampered by sluggish reaction kinetics, low mass loading, and volume change upon cycling. Herein, hierarchical Ni Co_(2)O_(4) architectures with 2D-nanosheets-shell and 3D-nanocages-core(2D/3D h-NCO) are directly assembled on nickel foam via a facile one-step way.The 2D nanosheets are in-situ generated from the self-evolution of initial NCO nanospheres. This 2D/3D hierarchical structures ensure fast ion/electron transport and maintain the structural integrity to buffer the volume expansion. The 2D/3D h-NCO electrode with an ultrahigh mass loading(30 mg cm^(-2)) achieves a high areal capacity of 4.65 C cm^(-2)(equivalent to 1.29 mAh cm^(-2)) at a current density of 4 mA cm^(-2), and retains 3.7 C cm^(-2) even at 50 mA cm^(-2). Furthermore, the assembled solid-state hybrid supercapacitor yields a high volumetric energy density of 4.25 mWh cm^(-3) at a power density of 39.3 mW cm^(-3), with a high capacity retention of 92.4% after 5000 cycles. Therefore, this work provides a new insight to constuct hierarchical electrodes for energy storage application.

CNT/High Mass Loading MnO2/Graphene-Grafted Carbon Cloth Electrodes for High-Energy Asymmetric Supercapacitors

Flexible supercapacitor electrodes with high mass loading are crucial for obtaining favorable electrochemical performance but still challenging due to sluggish electron and ion transport.Herein,rationally designed CNT/MnO2/graphene-grafted carbon cloth electrodes are prepared by a“graft-deposit-coat”strategy.Due to the large surface area and good conductivity,graphene grafted on carbon cloth offers additional surface areas for the uniform deposition of MnO2(9.1 mg cm?2)and facilitates charge transfer.Meanwhile,the nanostructured MnO2 provides abundant electroactive sites and short ion transport distance,and CNT coated on MnO2 acts as interconnected conductive“highways”to accelerate the electron transport,significantly improving redox reaction kinetics.Benefiting from high mass loading of electroactive materials,favorable conductivity,and a porous structure,the electrode achieves large areal capacitances without compromising rate capability.The assembled asymmetric supercapacitor demonstrates a wide working voltage(2.2 V)and high energy density of 10.18 mWh cm?3.

Facile anodization approach derived low-crystalline NiCoeOH/NiCoOOH composite films for ultra-high areal capacity and mass loading supercapacitors

The design of supercapacitor materials with both high areal capacity(C)and high mass loading is vitally important for enhancing energy density(E).Herein,we prepared a NiCosingle bondOH/NiCoOOH composite film consisting of NiCosingle bondOH/NiCoOOH nanosheets on an expanded graphite paper(EGP)by using a facial anodization method.The as-prepared NiCosingle bondOH/NiCoOOH film exhibits ultra-high C of 11 mA·h·cm^(-2)at a mass loading of 165 mg·cm^(-2),high rate capability of 71%and excellent cycling stability of 95%after 12000 cycles.The outstanding performance is ascribed to the low-crystalline feature of the NiCosingle bondOH/NiCoOOH nanosheets,and the synergistic effect of the NiCosingle bondOH and NiCoOOH phases and high conductive porous EGP.An aqueous asymmetric supercapacitor,assembled with the NiCosingle bondOH/NiCoOOH on EGP and Fe_(2)O_(3)on EGP as positive-and negative-electrode,respectively,shows a highest E of 3.8 mW·h·cm^(-2)at a power density(P)of 4 mW·cm^(-2)and a maximum P of 107 mW·cm^(-2)at an E of 2.7 mW·h·cm^(-2).

High mass loading Ni_(4)Co_(1)-OH@CuO core-shell nanowire arrays obtained by electrochemical reconstruction for alkaline energy storage

The design of three-dimensional(30)core-shell hetercistructures is an efficient method to achieve high mass specific capacity of electroactive materials under high mass loading.In this work,porous Ni_(4)Co1-0H nanosheets with a mass loading of 7.7 mg·cm^(-2) are obtained by using Ni_(4)Cor(NO_(3))_(2)(0H)_(4) supported on the CuO nanowires as precursors via an unavoidable electrochemically induced phase reconstruction.During the electrochemical reconstruction process,the N03-anions in Ni_(4)Cor(N0_(3))_(2)(0H)_(4) are easily replaced by OH-anions in the electrolyte.The phase reconstruction is accompanied by the decrease of ionic diffusion.:resistance and the increase of pore volume,and the shift of binding energy.The obtained Ni4Co1-0H nanosheets show a high:mass specific capacity of 363.6 mAh·g^(-1) at 5 mA·cm^(-2).The as-fabricated alkaline hybrid supercapacitor and Ni-Zn battery deliver high energy density of 293.1 and 604.9 Wh·kg^(-1),respectively,indicating.excellent alkaline energy storage performance.

Ultrahigh “Relative Energy Density” and Mass Loading of Carbon Cloth Anodes for K-Ion Batteries

Mass loading and potential plateau are the two most important issues of potassium(K)-ion batteries(KIBs),but they have long been ignored in previous studies.Herein,we report a simple and scalable method to fabricate acidized carbon clothes(A-CC)as high mass loading(13.1 mg cm−2)anode for KIBs,which achieved a reversible areal-specific capacity of 1.81 mAh cm−2 at 0.2 mA cm−2.Besides,we have proposed the concept of“relative energy density”to reasonably evaluate the electrochemical performance of the anode.According to our calculation method,the A-CC electrode exhibited an ultrahigh relative energy density of 46 Wh m−2 in the initial charge process and remained at 40 Wh m−2 after 50 cycles.Furthermore,we performed the operando Raman spectroscopy(ORS)to investigate the K-ion storage mechanism.We believe that our work might provide a new guideline for the evaluation of anode performance,thereby,opening an avenue for the development of commercial anode.

Wet-spinning assembly of nitrogen-doped graphene film for stable graphene-polyaniline supercapacitor electrodes with high mass loading

Graphene-polyaniline(GP)composites are promising electrode materials for supercapacitors but possessing unsatisfied stability,especially under high mass loading,due to the low ion transmission efficiency and serious pulverization effect.To address this issue,we propose a scalable method to achieve highly wettable GP electrodes,showing excellent stability.In addition,our results demonstrate that the performance of electrodes is nearly independent of the mass loading,indicating the great potential of such GP electrodes for practical devices.We attribute the remarkable performance of GP to the delicate precursor of nitrogen doped graphene film assembled by wet-spinning technology.This report provides a strategy to promote the ion penetrating efficiency across the electrodes and deter the pulverization effect,aiming at the practical GP supercapacitor electrodes of high mass loading.

Construction of Ti_(3)C_(2)T_(x)/WO_(x) heterostructures on carbon cloth for ultrahigh-mass loading flexible supercapacitor

The capacitance loss caused by slow electron and ion migration kinetics in thick electrode with high-mass loading has been regarded as a great challenge in the field of electrochemical energy storage.Herein,we demonstrate a facile electrochemical deposition method for coating the heterostructured Ti_(3)C_(2)T_(x)/WO_(x) onto flexible carbon cloth( Ti_(3)C_(2)T_(x)/WO_(x)@CC).In the Ti_(3)C_(2)T_(x)/WO_(x) heterojunction,the mixed-valence WOx core provides abundant active sites for H+ions accommodation,while Ti_(3)C_(2)Tx shell can not only prevent peeling off the thick WOx but also act as an interconnected conductive network.The Ti_(3)C_(2)T_(x)/WO_(x)@CC flexible electrode with an ultrahigh mass loading of 34.9 mg·cm^(−2) exhibits a high areal capacitance of 5.73 F·cm^(−2) at 5 mA·cm^(−2) and excellent rate capability.Notably,the Ti_(3)C_(2)T_(x)/WO_(x)@CC electrode under such a high mass loading still delivers a gravimetric capacitance of 164 F·g^(−1) and areal capacitance of Ti_(3)C_(2)T_(x)/WO_(x)@CC electrode increases linearly with the WOx mass loading.Furthermore,a symmetrical supercapacitor assembled with Ti_(3)C_(2)T_(x)/WO_(x)@CC electrode exhibits a good areal energy density of 96.8μWh·cm^(−2) at a power density of 1.5 mW·cm^(−2).This work verifies high mass loading of active materials per unit electrode area for charge storage of supercapacitors in limited space,indicating the great potential in the development of commercially available thick metal-oxide film supercapacitors.

Ultra-High Mass-Loading Cathode for Aqueous Zinc-Ion Battery Based on Graphene-Wrapped Aluminum Vanadate Nanobelts

Rechargeable aqueous zinc-ion batteries(AZIBs)have their unique advantages of cost efficiency,high safety,and environmental friendliness.However,challenges facing the cathode materials include whether they can remain chemically stable in aqueous electrolyte and provide a robust structure for the storage of Zn2+.Here,we report on H11Al2V6O23.2@graphene(HAVO@G)with exceptionally large layer spacing of(001)plane(13.36?).The graphene-wrapped structure can keep the structure stable during discharge/charge process,thereby promoting the inhibition of the dissolution of elements in the aqueous electrolyte.While used as cathode for AZIBs,HAVO@G electrode delivers ideal rate performance(reversible capacity of 305.4,276.6,230.0,201.7,180.6 mAh g?1 at current densities between 1 and 10 A g?1).Remarkably,the electrode exhibits excellent and stable cycling stability even at a high loading mass of^15.7 mg cm?2,with an ideal reversible capacity of 131.7 mAh g?1 after 400 cycles at 2 A g?1.

Responses of jointed rock masses subjected to impact loading

Impact-induced damage to jointed rock masses has important consequences in various mining and civil engineering applications. This paper reports a numerical investigation to address the responses of jointed rock masses subjected to impact loading. It also focuses on the static and dynamic properties of an intact rock derived from a series of laboratory tests on meta-sandstone samples from a quarry in Nova Scotia, Canada. A distinct element code(PFC2D) was used to generate a bonded particle model(BPM) to simulate both the static and dynamic properties of the intact rock. The calibrated BPM was then used to construct large-scale jointed rock mass samples by incorporating discrete joint networks of multiple joint intensities into the intact rock matrix represented by the BPM. Finally, the impact-induced damage inflicted by a rigid projectile particle on the jointed rock mass samples was determined through the use of the numerical model. The simulation results show that joints play an important role in the impactinduced rock mass damage where higher joint intensity results in more damage to the rock mass. This is mainly attributed to variations of stress wave propagation in jointed rock masses as compared to intact rock devoid of joints.

Application of artificial neural networks in optimal tuning of tuned mass dampers implemented in high-rise buildings subjected to wind load

High-rise buildings are usually considered as flexible structures with low inherent damping. Therefore, these kinds of buildings are susceptible to wind-induced vibration. Tuned Mass Damper（TMD） can be used as an effective device to mitigate excessive vibrations. In this study, Artificial Neural Networks is used to find optimal mechanical properties of TMD for high-rise buildings subjected to wind load. The patterns obtained from structural analysis of different multi degree of freedom（MDF） systems are used for training neural networks. In order to obtain these patterns, structural models of some systems with 10 to 80 degrees-of-freedoms are built in MATLAB/SIMULINK program. Finally, the optimal properties of TMD are determined based on the objective of maximum displacement response reduction. The Auto-Regressive model is used to simulate the wind load. In this way, the uncertainties related to wind loading can be taken into account in neural network’s outputs. After training the neural network, it becomes possible to set the frequency and TMD mass ratio as inputs and get the optimal TMD frequency and damping ratio as outputs. As a case study, a benchmark 76-story office building is considered and the presented procedure is used to obtain optimal characteristics of the TMD for the building.

Optimization of structural parameters for spatial flexible redundant manipulators with maximum ratio of load to mass

Optimization of structural parameters aimed at improving the load carrying capacity of spatial flexible redundant manipulators is presented in this paper. In order to increase the ratio of load to mass of robots, the cross-sectional parameters and constructional parameters are optimized respectively. The cross-sectional and configurational parameters are optimized simultaneously. The numerical simulation of a 4R spatial manipulator is performed. The results show that the load capacity of robots has been greatly improved through the optimization strategies proposed in this paper.

A Review of Research on Catastrophic Formation and Evolutionary Mechanism of Deep High Stress Rock Mass under Impact Loading

With the exploitation of resources expanded to deep, the geological environment which is “three tenors one disturbance” of rock mass in great depth has been more complex, resulting in some new engineering geological disasters, such as rock burst, pressure bumping, large deformation of surrounding rock, brittle-ductile transition of rock and zonal disintegration of rock mass, which occur frequently in deep underground engineering rock mass. The impact load caused by collision, explosion, extrusion and outburst is the root cause of the dynamic instability of the deep rock mass. What should be emphasized is that high in-situ stress and blasting excavation disturbance complicate disaster developing mechanism of deep underground engineering rock mass and sharply increase the difficulty of controlling disaster. This paper is aimed at the research status and development trend, of which dynamic characteristics of deep high stress rock mass and its damage and failure effect each other under impact, and conduct analysis, in the later stage where I would discuss how to carry out the response law of the deep high-stress rock mass under the impact load and the mechanism of catastrophe developing, which is of great significance to build a model of instability and fracture evolution about deep rock mass under shock disturbance and to maintain its safety and stability.

列车作用下大跨径悬索桥纵向运动响应分析方法对比研究

随着我国铁路事业的发展,近年来设计和建造了一些大跨径铁路悬索桥。悬索桥属于典型的柔性结构,加之列车荷载大、运行速度快,列车过桥时加劲梁纵向运动问题突出。准确地计算出列车过桥时梁端纵向运动响应是进行悬索桥结构设计和梁端位移控制的前提。该文通过有限元仿真,采用4种不同的分析方法,对运行列车作用下大跨径铁路悬索桥纵向运动响应特征进行对比研究。首先,分别介绍移动静载法、移动荷载法、移动质量法、车-桥动力相互作用法的计算理论及其有限元实现方法;随后,以某主跨1060m铁路悬索桥为例,分别采用4种方法进行纵向运动响应计算;最后,对4种分析方法的计算结果进行对比分析。结果表明:大跨径铁路悬索桥纵向运动分析应考虑动力效应;通过移动荷载法、移动质量法及车-桥动力相互作用法分析得到的纵向运动响应接近;采用移动荷载法进行大跨径铁路悬索桥纵向运动响应分析可以简化计算且满足计算精度要求。

Dynamic Failure Model of Thin Coal and Rock Mass under Uniform Impact Load

During the excavation of deep coal and rock mass, the radial stress of the free face changes from three-dimensional compression state to two-dimensional stress, bearing the combined action of dynamic disturbance and static load at the same time. With that, many mines suffer from dynamic disasters, such as coal and gas outburst, rock burst and rock caving during deep mining excavation, which is often accompanied by plate crack, spalling and other disasters, seriously affecting the stability of stope and roadway. Taking thin rectangular coal and rock mass as the research object, the dual equation of the free vibration was derived and the exact solution model of the free vibration was established with the use of Hamilton dual system. Based on the action characteristics of the uniform impact load, the effective mode of the forced vibration was obtained by using the Duhamel integral principle and the orthogonality of the mode function. Based on the third strength theory and the numerical simulation results, the dynamic damage process and development trend of coal and rock mass were analyzed under uniform impact load. It was concluded that the starting position of dynamic damage can be judged by the first order main mode, and the development direction and trend of the damage can be judged by the fifth and sixth order main modes. It was concluded that the vibration mode functions of coal and rock mass with four side fixed (C-C-C-C), the two sides fixed and simply supported on the other (S-C-S-C) are mainly composed of three modes that are the first order (dominant frequency), the fifth order and the sixth order, from which the dynamic damage mechanism is preliminarily studied.

Retrieval of Volcanic Sulfate Aerosols Optical Parameters from AHI Radiometer Data

This paper presents a method for retrieving optical parameters from volcanic sulfate aerosols from the AHI radiometer on board the Himawari-8 satellite.The proposed method is based on optical models for various mixtures of aerosol components from volcanic clouds,including ash particles,ice crystals,water drops,and sulfate aerosol droplets.The application of multi-component optical models of various aerosol compositions allows for the optical thickness and mass loading of sulfate aerosol to be estimated in the sulfuric cloud formed after the Karymsky volcano eruption on 3 November 2021.A comprehensive analysis of the brightness temperatures of the sulfuric cloud in the infrared bands was performed,which revealed that the cloud was composed of a mixture of sulfate aerosol and water droplets.Using models of various aerosol compositions allows for the satellite-based estimation of optical parameters not only for sulfate aerosol but also for the whole aerosol mixture.

空气过滤棉荷尘阻力特性的实验研究

为研究复合式空气过滤棉的阻力特性,选择3层复合空气过滤棉作为主要研究对象,通过实验系统地研究荷尘速率对其阻力变化的影响,并与过滤纸进行对比。研究结果表明:在相同过滤风速下,荷尘质量浓度越低,过滤棉阻力上升速度越快;过滤棉等级越低,荷尘质量浓度对其阻力增长影响越大,归一化阻力随单位面积荷尘质量的增长越快;过滤风速对过滤棉归一化阻力的增长有影响,过滤风速越大,归一化阻力增长越缓慢,但对效率较高的过滤棉影响不大。相同荷尘条件下,相较于过滤纸,过滤棉的归一化阻力上升更慢;基于实验归纳得到3层复合空气过滤棉的阻力增长特性方程。研究结果可为其使用寿命预测提供参考。

南水北调中线北京段岩体隧洞围岩变形模量分析研究

岩体力学参数是影响地下工程围岩稳定的重要因素,确定合理的岩体变形模量对隧洞设计至关重要。结合南水北调中线北京段西甘池试验洞工程,对岩体进行静载荷试验分析研究,详细介绍试验点岩体的加卸载变形关系曲线,获得西甘池隧洞岩体变形模量参数建议值,为工程设计提供依据,并以期为类似工程的设计和施工提供参考。研究结果表明:试验压力较小时,各试点岩体变形或弹性模量的变化曲线有的升、有的降,试验压力大于0.4 MPa以后,各试点的变形模量和弹性模量逐渐趋于稳定;隧洞围岩变形控制及支护结构设计时,应根据各段围岩的岩性(大理岩、滑石片岩)、结构完整性、节理裂隙的空间展布方式以及发育充填情况等综合考虑,结合工程类比和地质经验最终确定岩体弹性参数的基本代表值。研究的方法和结论可为类似条件下隧洞工程的设计、施工提供参考和借鉴。

基于突变理论的隔水岩体失稳分析及安全厚度计算

为了保障岩溶突水隧道施工和运营安全,基于弹性梁模型,应用突变理论建立岩溶突水顶板在动力扰动下失稳的双尖点突变模型;综合考虑围岩性质、静水压力、动力扰动等因素,分析岩溶突水隧道顶板的失稳机制和破坏条件,建立其失稳突变的判别方程,并采用Matlab软件编程,求解顶板的最小安全厚度;同时,为了避免当静水压力过大时,突变理论公式的不合理性,单独计算仅在静水压力的情况下的最小安全厚度,并取两者计算值中的更大值。结果表明:隔水岩体是否保持稳定是由岩体内外因素共同决定的;岩体跨度越长,岩体最小安全厚度越大;岩体弹性模量越大,岩体最小安全厚度越小。在振动频率一定时,爆破荷载越大,岩体最小安全厚度越大;在爆破荷载的大小一定时,爆破振动的频率越大,岩体最小安全厚度越小;静水压力越大,岩体最小安全厚度越大。该岩溶突水隧道顶板安全厚度计算方法具有可行性与较高的准确性。

基于声发射频谱的次生胶结岩体加卸载损伤特性

斜坡岩体裂隙中广泛存在后期次生胶结物,地震过程中次生胶结岩体极易发育密集微裂纹。开展单轴静荷载和加卸载试验,通过声发射频谱演化特征研究荷载条件下次生胶结物对岩体微裂纹扩展过程的影响。研究结果表明:静荷载下小尺度裂纹、微小裂纹、沿晶裂纹和穿晶裂纹贯穿整个试验过程,低频高频信号对应的大尺度裂纹主要产生在不稳定扩展阶段,加卸载条件下声发射主频演化类型受到次生胶结物面积的影响,次生胶结物对岩体损伤起主要控制作用,降低了造成岩体损伤的应力阈值,加卸载作用下次生胶结物与岩石性质差异造成的非协调变形是造成损伤的根本原因。