Variations in organic carbon loading of surface sediments from the shelf to the slope of the Chukchi Sea,Arctic Ocean

The content of organic carbon （OC） normalized to the specific surface area （SSA） of sediment is widely used to trace variations in OC loading （OC/SSA）. This study presents observations of OC/SSA of surface sediments collected in the Chukchi Sea, a typical Arctic marginal sea. Shelf sediments exhibit much higher OC/SSA values than slope sediments in the study area. Compared with OC/SSA values reported from the East Siberian Shelf and Mackenzie River, the slope sediments possess lower OC loading. This abrupt decrease in OC/SSA is mostly related to the lower primary production on slope as well as possible oxidization processes. The results of linear regression analysis between OC and SSA indicate a sedimentary source rock for the OC in the Chukchi Sea sediments. Moreover, shelf sediments with low SSA possess a larger rock OC fraction than slope sediments do. The dataset of the present study enables a more thorough understanding of regional OC cycling in the Chukchi Sea.

POSITIVE TEMPERATURE COEFFICIENT PHENOMENON OF CARBON LOADED NBR COMPOSITES

The resistivity of conductive composites of NBR(Butadiene nitrile rubber) filled with conductive carbon black and two kinds of special organic fillers was measured from room temperature to 90℃. In such semiconduc-tive systems. A positive temperature coefficient (PTC) phenomenon is observed, whose intensity depends on the type concentration and other physical and chemical properties of carbon black. Two empirical formulae are obtained by a the-oretical fitting method from the experimental data. One is for the resistivity of NBR/CB composites at room temperature and the other is for the resistivity of NBR/ N550 composites with relatively high concentrations N550 carbon blick in the temperature range of 30 ~ 90℃. The stability of resistivity is also discussed.

In situ formation of multiple catalysts for enhancing the hydrogen storage of MgH_(2) by adding porous Ni_(3)ZnC_(0.7)/Ni loaded carbon nanotubes microspheres

MgH_(2) is considered one of the most promising hydrogen storage materials because of its safety,high efficiency,high hydrogen storage quantity and low cost characteristics.But some shortcomings are still existed:high operating temperature and poor hydrogen absorption dynamics,which limit its application.Porous Ni_(3)ZnC_(0.7)/Ni loaded carbon nanotubes microspheres(NZC/Ni@CNT)is prepared by facile filtration and calcination method.Then the different amount of NZC/Ni@CNT(2.5,5.0 and 7.5 wt%)is added to the MgH_(2) by ball milling.Among the three samples with different amount of NZC/Ni@CNT(2.5,5.0 and 7.5 wt%),the MgH_(2)-5 wt%NZC/Ni@CNT composite exhibits the best hydrogen storage performances.After testing,the MgH_(2)-5 wt%NZC/Ni@CNT begins to release hydrogen at around 110℃ and hydrogen absorption capacity reaches 2.34 wt%H_(2) at 80℃ within 60 min.Moreover,the composite can release about 5.36 wt%H_(2) at 300℃.In addition,hydrogen absorption and desorption activation energies of the MgH_(2)-5 wt%NZC/Ni@CNT composite are reduced to 37.28 and 84.22 KJ/mol H_(2),respectively.The in situ generated Mg_(2)NiH_(4)/Mg_(2)Ni can serve as a"hydrogen pump"that plays the main role in providing more activation sites and hydrogen diffusion channels which promotes H_(2) dissociation during hydrogen absorption process.In addition,the evenly dispersed Zn and MgZn2 in Mg and MgH_(2) could provide sites for Mg/MgH_(2) nucleation and hydrogen diffusion channel.This attempt clearly proved that the bimetallic carbide Ni_(3)ZnC_(0.7) is a effective additive for the hydrogen storage performances modification of MgH_(2),and the facile synthesis of the Ni_(3)ZnC_(0.7)/Ni@CNT can provide directions of better designing high performance carbide catalysts for improving MgH_(2).

Effects of mineral loading methods on carbon solution reaction of coal-derived carbon material

11 oxides (MgO, CaO, BaO, TiO2, V2O5, MnO2, Fe2O3, CuO, ZnO, PbO2 and B2O3), often found in coal-derived carbon materials, were loaded into the coal-derived carbon material by two methods such as adsorbing oxides through solution onto the surface of coke and adding oxides into the coal before carbonization. The effects of oxides on carbon solution reaction of carbon material were investigated and compared. The results show that the effect trends are similar but the effect of oxides by adsorbing is remarkably greater than that of the oxides by adding oxides as BaO, MgO, Fe2O3, CuO, ZnO, MnO2, PbO2 and B2O3. And the effect trends are similar. BaO, CaO and Fe2O3 are the greatest affecting oxides. The saturation point of addition content is 3% and that of adsorption is 1%.

Catalytic ozonation of phenol and oxalic acid with copper-loaded activated carbon

A novel heterogeneous catalytic ozonation process in water treatment was studied,with a copper-loaded activated carbon(Cu/AC) that was prepared by an incipient wetness impregnation method at low temperature and tested as a catalyst in the ozonation of phenol and oxalic acid.Cu/AC was characterized using XRD,BET and SEM techniques.Compared with ozonation alone,the presence of Cu/AC in the ozonation processes significantly improves the degradation of phenol or oxalic acid.With the introduction of the hydroxyl radical scavenger,i.e.,turt-butanol alcohol(t-BuOH),the degradation efficiency of both phenol and oxalic acid in the Cu/AC catalyzed ozonation process decreases by 22% at 30 min.This indicates that Cu/AC accelerates ozone decomposition into certain concentration of hydroxyl radicals.The amount of Cu(Ⅱ) produced during the reaction of Cu/AC-catalyzed ozonation of phenol or oxalic acid is very small,which shows that the two processes are both heterogeneous catalytic ozonation reactions.

Study on Direct Synthesis of Diphenyl Carbonate with Heterogeneous Catalytic Reaction (VI) Effect of Sn Loading Method and Content on Activity of Sn-Pd Supported Catalyst

The compound metal oxide LaxPbyMnzO used as support was prepared by the sol-gel method, and the catalyst in which Pd was used as active component and Sn as co-active component for direct synthesis of diphenyl carbonate (DPC) with heterogeneous catalytic reaction was obtained by co-calcination and precipitation respectively.The catalyst was characterized by XRD, SEM and TEM respectively. The specific surface area of catalysts was measured by ChemBET3000 instrument, and the activity of the catalysts was tested by the synthesis of DPC in a pressured reactor. The results showed that when the co-active component Sn was added by co-calcination method A, its loading content was equal to 14.43% and active component Pd was loaded by precipitation, the yield and selectivity of DPC could reach 26.78% and 99% respectively.

Facile Synthesis of Gold Nanoparticle-loaded Carbon Nanofiber Composites and Their Electrocatalytic Activity Towards Dopamine, Ascorbic Acid and Uric Acid

A facile approach for the synthesis of gold nanoparticle-loaded carbon nanofiber（Au/CNF） composites was developed. When applied to electrochemistry, these composites showed attractive performances such as high conductivity and facile electron transfer kinetics. Under physiological conditions, the Au/CNF composite modified electrode exhibits highly electrocatalytic activity for the oxidation of dopamine, ascorbic acid and uric acid. Owing to the good selectivity for the simultaneous detection of these three species, the novel composites are promising for the development of effective electrochemical biosensors.

DYNAMIC BUCKLING OF DOUBLE-WALLED CARBON NANOTUBES UNDER STEP AXIAL LOAD

An approximate method is presented in this paper for studying the dynamic buckling of double-walled carbon nanotubes （DWNTs） under step axial load. The analysis is based on the continuum mechanics model, which takes into account the van der Waals interaction between the outer and inner nanotubes. A buckling condition is derived, from which the critical buckling load and associated buckling mode can be determined. As examples, numerical results are worked out for DWNTs under fixed boundary conditions. It is shown that, due to the effect of van der Waals forces, the critical buckling load of a DWNT is enhanced when inserting an inner tube into a single-walled one. The paper indicates that the critical buckling load of DWNTs for dynamic buckling is higher than that for static buckling. The effect of the radii is also examined. In addition, some of the results are compared with the previous ones.

Service Life Prediction of Lining Concrete of Subsea Tunnel under Combined Compressive Load and Carbonation

Qingdao Jiaozhou Bay subsea tunnel is the second self-built tunnel in China with the designed service life over 100 years.The durability of lining concrete are one of an important factors to determinate the service life of tunnel.Considering the main environmental loads and mechanical loads of subsea tunnel,the durability properties of lining concrete under combined action of compressive load and carbonation has been studied through the critical compressive load test,accelerated carbonation test,natural carbonation test and capillary suction test.The tests results show that critical compressive load apparently accelerates the carbonation and deteriorates the anti-permeability of concrete.Under the combined action of critical compressive load and carbonation,the durability of lining concrete decreases.Based on the carbonization life criteria and research results,for the high-performance concrete with proposed mix ratio,the predicted service life of lining concrete for Jiaozhou bay subsea tunnel is about 80 years which fails to reach the required service life.It is necessary to adopt other measurements simultaneously to improve the durability of lining concrete.

High microwave absorption performances for single-walled carbon nanotube–epoxy composites with ultra-low loadings

Microwave-absorbing polymeric composites based on single-walled carbon nanotubes （SWNTs） are fabricated via a simple yet versatile method, and these SWNT-epoxy composites exhibit very impressive microwave absorption perfor- mances in a range of 2 GHz-18 GHz. For instance, a maximum absorbing value as high as 28 dB can be achieved for each of these SWNT-epoxy composites （1.3-mm thickness） with only 1 wt% loading of SWNTs, and about 4.8 GHz bandwidth, corresponding to a microwave absorption performance higher than 10 dB, is obtained. Furthermore, such low and appro- priate loadings of SWNTs also enhance the mechanical strength of the composite. It is suggested that these remarkable results are mainly attributable to the excellent intrinsic properties of SWNTs and their homogeneous dispersion state in the polymer matrix.

POSTBUCKLING OF CARBON NANOTUBES SUBJECTED TO CYCLIC LOAD

This study focuses on the postbuckling and the nonlinear behavior of single-walled carbon nanotubes subject to a cyclic axial compressive load through the use of molecular dynamic simulation based on the Tersoff-Brenner potential. It reveals the bifurcation behavior in the buckling process simulated with very fine time steps. In the whole cycle of nonlinear deformation, the carbon nanotubes exhibit the profound hysteretic behavior and the energy absorption ability. The molecular dynamics simulation indicates that the carbon nanotube behaves approximately as an ideal plastic spring when the cyclic strain is applied within the same postbuckling mode. In comparison, the theory of continuum mechanics gives a good prediction about the critical buckling strength, but only provides a rough estimation for the post-buckling behaviors.

Thermal-mechanical properties of short carbon fiber reinforced geopolymer matrix composites subjected to thermal load

Short carbon fiber preform reinforced geopolymer composites containing different contents of α-Al2O3 filler (Cf(α-Al2O3)/geopolymer composites) were fabricated,and the effects of heat treatment temperatures up to 1 200 ℃ on the thermal-mechanical properties were studied. The results show that the thermal shrinkage in the direction perpendicular to the lamination of the composites gradually increases with the increase of the heat treatment temperatures from room temperature (25 ℃) to 1 000 ℃. However,the composites in the direction parallel to the lamination show an expansion behavior. Beyond 1 000 ℃,in the two directions the composites exhibit a larger degree of shrinkage due to the densification and crystallization. The mechanical properties of the composites show the minimum values in the temperature range from 600 to 800 ℃ as the hydration water of geopolymer matrix is lost. The addition of α-Al2O3 particle filler into the composites clearly increases the onset crystalline temperature of leucite (KAlSi2O6) from the amorphous geopolymer matrix. In addition,the addition of α-Al2O3 particles into the composites can not only help to keep volume stable at high temperatures but also effectively improve the mechanical properties of the composites subjected to thermal load to a certain extent. The main toughening mechanisms of the composites subjected to thermal load are attributed to fiber pulling-out.

Integrated Behavior of Carbon and Copper Alloy Heat Sink Under Different Heat Loads and Cooling Conditions

An actively water-cooled limiter has been designed for the long pulse operation of an HT-7 device, by adopting an integrated structure-doped graphite and a copper alloy heat sink with a super carbon sheet serving as a compliant layer between them. The behaviors of the integrated structure were evaluated in an electron beam facility under different heat loads and cooling conditions. The surface temperature and bulk temperature distribution were carefully measured by optical pyrometers and thermocouples under a steady state heat flux of 1 to 5 MW/m^2 and a water flow rate of 3 m^3/h, 4.5 m^3/h and 6 m^3/h, respectively. It was found that the surface temperature increased rapidly with the heat flux rising, but decreased only slightly with the water flow rate rising. The surface temperature reached approximately 1200℃ at 5 MW/m^2 of heat flux and 6 m^3/h of water flow. The primary experimental results indicate that the integrated design meets the requirements for the heat expelling capacity of the HT-7 device. A set of numerical simulations was also completed, whose outcome was in good accord with the experimental results.

计及LCA碳排放的源荷双侧合作博弈调度研究

为实现新型电力系统的低碳经济目标,提出一种计及生命周期评价(lifecycleassessment, LCA)的源荷双侧合作博弈优化调度模型。首先,考虑灵活可调度的柔性负荷,构建含热电联产机组、燃气锅炉、电转气等设备的源荷双侧合作运行框架。然后,运用LCA方法分析源荷双侧中不同能源链的温室气体排放,并结合碳交易机制,建立碳交易成本计算模型。最后,基于合作博弈策略,建立以源荷合作联盟总成本最小为目标的源荷双侧协同运行优化模型,并利用改进的Shapley值法对成员合作收益进行分配。算例分析表明,所提模型有利于降低系统运行的总成本、减少系统碳排放量、提升可再生能源消纳量,有效促进系统低碳经济的发展。

Nonlinear vibration of embedded single-walled carbon nanotube with geometrical imperfection under harmonic load based on nonlocal Timoshenko beam theory

Based on the nonlocal continuum theory, the nonlinear vibration of an embedded single-walled carbon nanotube （SWCNT） subjected to a harmonic load is in- vestigated. In the present study, the SWCNT is assumed to be a curved beam, which is unlike previous similar work. Firstly, the governing equations of motion are derived by the Hamilton principle, meanwhile, the Galerkin approach is carried out to convert the nonlinear integral-differential equation into a second-order nonlinear ordinary differ- ential equation. Then, the precise integration method based on the local linearzation is appropriately designed for solving the above dynamic equations. Besides, the numerical example is presented, the effects of the nonlocal parameters, the elastic medium constants, the waviness ratios, and the material lengths on the dynamic response are analyzed. The results show that the above mentioned effects have influences on the dynamic behavior of the SWCNT.

卤氧化铋在光催化降解有机废水中的应用及其改性研究

【目的】卤氧化铋BiOX(X=Cl、Br、I)因其独特的层状结构和禁带宽度在光催化反应中表现出优异的活性与稳定性,已成为光催化材料领域极具前景的材料。因此,对卤氧化铋进行改性,使其拥有更高的光催化性能成为近年来研究的热点。【方法】概述了有机废水的污染现状及主要处理方式,特别是光催化降解技术的研究现状。综述了BiOX(X=Cl、Br、I)光催化材料在有机污染物降解方面的应用及改性措施,改性措施主要包括金属掺杂、异质结构筑和碳材料复合改性。【结果】关于金属掺杂改性和异质结构筑改性的方法研究得最多,光催化降解污染物的效率高,但存在掺杂的金属离子难回收,会对环境造成二次污染,构建异质结中存在逆反应、光屏蔽、副反应等问题。相较于以上两种改性方法,采用碳材料复合改性的方法通过吸附与光催化耦合提高光催化降解效率,可以降低催化剂的成本。【结论】通过对三种改性方法的比较,为卤氧化铋BiOX(X=Cl、Br、I)材料进行改性提供了参考与借鉴。生物碳是一种低成本、环境友好且可持续的含碳材料,采用生物碳对催化剂进行改性,可为解决目前迫在眉睫的环境有机染料污染和抗生素污染问题提供新方案。

基于节点碳势需求响应的电力系统双层优化调度

为实现电力系统低碳排放、助力经济提升,在建立碳势引导多元柔性负荷模型的基础上,提出一种基于节点碳势需求响应的双层优化调度策略。首先,利用比例共享原则追踪碳排放流,搭建碳排放流模型,从时空维度感知各节点的碳势变化规律。其次,将碳流分析纳入负荷侧需求响应机制中,利用节点碳势建立负荷聚合商需求响应碳排放模型,并厘清不同碳势强度下负荷聚合商调度差异,构建基于节点碳势需求响应的电力系统双层优化调度模型。模型上层为电网运营商最优经济调度,模型下层为负荷聚合商需求响应经济调度。最后,以改进IEEE 30节点系统为例,验证了所提方法的有效性。

DPF碳载量对重型车PN排放影响研究

从DPF碳载量为0%时开始,直至DPF碳载量为100%,达到后处理再生状态结束共进行了8次PEMS试验。研究DPF碳载量对PN比排放的影响,根据瞬时车速和瞬时机动车比功率等参数对瞬态数据划分Bin网格,计算每次试验各个Bin的PN平均排放浓度和DPF平均温度的关系。试验结果表明,除最后一次发生再生的PEMS测试外,随着DPF碳载量的增大,PN比排放呈现先升高再降低的趋势;随着碳载量升高,Bin0、Bin1、Bin12以及Bin22等区间内每次试验的PN排放浓度相差不多。Bin13区间内的PN排放会随着碳载量的升高整体呈升高趋势。Bin23和Bin33区间内,PEMS试验的PN排放会随着碳载量的升高整体呈降低趋势。

车辆载重对重型货车碳排放的影响

现有交通碳排放模型对重型车在实际路况下的载重变化特性考虑不足,尚未从微观排放率角度分析载重对车辆排放的影响,从而造成碳排放测算的不确定性较大。针对此问题,首先采集大规模的实际路况下重型货车运行工况和油耗数据,使用基于油耗的CO_(2)排放测算模型计算重型货车的CO_(2)排放量;然后对不同类别的货车分类讨论,使用基于VSP的排放模型研究车辆载重对CO_(2)排放的影响,并建立考虑车重的LC-VSP排放模型,再与传统MOVES模型进行排放测算误差的对比。研究结果显示,载重对重型货车CO_(2)排放率、VSP分布都会产生显著影响,进而显著影响CO_(2)排放因子,具体表现为:①当VSP处于较小的正区间时,CO_(2)排放率随载重的增加而线性增大;②在相同速度区间,随着载重的增加,VSP分布的均值和方差都会逐渐减小;③在平均工况下,根据车型的不同,满载相较于空载的CO_(2)排放因子增加了约24%~113%,当车辆速度较低(小于20 km/h)时,载重对CO_(2)排放因子影响显著,车辆满载(49 t)时的CO_(2)排放因子为车辆空载(18 t)时的2.8倍,但随着速度的提高,载重对CO_(2)排放因子的影响逐渐减小;④相较于不考虑车辆实际载重的排放模型,考虑车辆实际载重时CO_(2)排放测算误差可以减小3%~12%。这一结果强调了在排放测算中考虑车辆载重的必要性,为精准的排放建模和评估提供了一定的理论依据。

考虑柔性负荷和阶梯式碳交易的微电网鲁棒优化调度

针对低碳背景下微电网中可再生能源出力的不确定性以及碳排放问题,提出了一种考虑阶梯式碳交易机制同时柔性负荷参与调控的微电网两阶段鲁棒优化方法。在调度模型中引入阶梯式碳交易机制,限制系统的碳排放量;通过柔性负荷的调控作用弥补由于可再生能源出力波动造成的功率缺额,进一步减小了微电网的碳排放量和调度成本;模型中引入不确定参数调节系统的保守性,日前阶段基于预测数据并考虑系统日内可能遭受的最恶劣场景,制定预测数据下的日前调度方案,日内调控阶段则在日前调度方案的基础上进行二次优化,在最恶劣场景下给出系统的日内调控方案;模型利用嵌套C&CG算法对调度模型进行求解。算例仿真结果证明,鲁棒优化方法相较于确定性优化方法其总调度成本平均减少了3.1%;考虑阶梯式碳交易机制后,系统单日运行的碳排放量和总调度成本相较于未考虑碳交易机制时分别下降了17.7%和3.7%;考虑柔性负荷参与调度后,系统单日运行的碳排放量和总调度成本相较于未考虑柔性负荷时分别下降了26%和24.3%,验证了所提优化模型的有效性。