大型水库分层期和混合期溶存温室气体空间变化及排放通量

水库作为温室气体的重要来源,对区域气候变化有不可忽略的影响。然而,目前对水库溶存温室气体的空间异质性及垂向特征的认知仍然欠缺。为了揭示水库分层期和混合期溶存温室气体空间特征及排放通量,也为厘清水库温室气体产生和排放的关键过程提供重要支撑。研究选择东北地区大型水库——汤河水库为对象,于2021年79月和10月(分别代表水库分层期和混合期)对水库不同位置(坝前、库中和库尾)开展溶存温室气体垂向分层监测。研究结果显示,水库CH 4排放通量变化范围为0.018~0.174 mmol/(m^(2)·d),是大气CH 4的源,空间分布为库尾>库中>坝前;CO_(2)通量为-4.91~58.77 mmol/(m^(2)·d),除分层期东支库尾,其余点位均表现为大气CO_(2)的源,空间分布为坝前>库中>库尾。时间上,分层期CH 4排放通量(0.071±0.044 mmol/(m^(2)·d))高于混合期((0.027±0.008)mmol/(m^(2)·d));分层期CO_(2)排放通量((5.12±5.50)mmol/(m^(2)·d))明显低于混合期((42.76±16.72)mmol/(m^(2)·d))。水温和径流的变化共同影响CH 4和CO_(2)排放通量。结合水库溶存温室气体垂向分布特征,水库CH 4的生成热区主要在坝前和库尾。分层期的水库溶存CH 4在坝前和库中底层大量累积,原因是等温层的持续缺氧以及上下水层的交换能力限制。与国内其它水库温室气体排放通量对比发现,水库的不同时期(分层期和混合期)、空间位置(坝前、库中和库尾)以及库龄是准确评估水库温室气体排放的关键因素。

贵州百花湖分层期水体有机碳及其稳定碳同位素组成分布特征与控制因素

研究湖水溶解有机碳（Dissolved organic carbon,DOC）和颗粒有机碳（Particle organic carbon,POC）的空间变化特征有助于揭示湖泊有机碳的来源、迁移转化过程与控制因素。本文通过对贵州百花湖分层期水体DOC和POC浓度及其碳稳定同位素组成的对比研究,揭示了百花湖分层期水体有机碳浓度及稳定碳同位素的空间分布特征。研究结果表明,百花湖夏季分层期水体DOC和POC的浓度范围分别为1.97～3.26mg/L（平均值2.58mg/L）和0.60～2.43mg/L（平均值1.14mg/L）,且呈现出＂上层高、下层低＂的特征。水体DOC和POC浓度主要受藻类活动控制。水体δ13 CDOC值随深度增加呈偏正趋势,这可能是由深层水体溶解有机质发生矿化作用和分解作用所致。水体δ13 CPOC值随水体深度增加呈偏负趋势,上下层水体藻类生产力差异和沉积物再悬浮作用可能是导致该现象的主要原因。受光降解作用影响,百花湖水体δ13 CDOC较δ13 CPOC偏正。

二灰碎石基层分层施工技术的试验研究

在高等级道路工程中 ,二灰碎石基层有两种不同的分层施工方法 :连续分层施工法和间隔养生期分层施工法 .现行技术规范对这两种方法均认可 ,但并不明确两者的实际效果 .以上海市外环线工程为依托 ,通过试验路的实施和现场测试 ,对二灰碎石基层的分层施工技术进行了研究 .结果表明 。

五相混合励磁双凸极电机多目标分层分期优化设计

五相定子槽口永磁型混合励磁双凸极电机定子槽内绕组与永磁体的耦合对优化设计提出了更高的要求,为进一步提升此类电机的功率密度和过载能力,该文提出一种五相20/18极的拓扑结构,对电机的空载特性和功率特性进行分析,确定初始优化参数和目标后进行六参数四目标的分层分期优化。首先,在电机直流饱和前提下,通过槽满率和绕组电流密度的限制提出基本的约束条件并合理分配好定子槽面积;其次,结合正交试验设计法和综合灵敏度分析对电机的本体结构参数进行分层优化,通过有限元分析建立高敏感层参数的数据库并建立数学模型,在此基础上运用改进的非支配排序遗传算法对模型实现分期优化设计,引入佳点集并在算法迭代前期基于线性排名加快收敛速度,在迭代后期施加均值约束避免畸形解,与其他智能算法对比验证了改进算法的优越性;最后,根据优化结构制造实验样机进行实验,验证了所提优化算法的可行性与有效性。

芒果汁均质乳化试验

取均质压力为 10 MPa、30 MPa和 50 MPa,取增稠剂含量为 0 .0 1%、0 .0 2 %和 0 .0 3% ,取芒果原浆含量为 5.0 %、7.5%和 10 .0 % ,利用 L9(34 )正交试验表 ,进行三因素三水平试验 ,结果表明影响芒果汁分层的主次因素依次为增稠剂含量、均质压力、芒果原浆含量 ;较优水平是均质压力为 30 MPa、增稠剂含量为0 .0 3%和芒果原浆含量为 7.5%。按照此水平生产的芒果汁 ,在常温下贮藏 180 d,产品质量稳定 。

Thermal Induced Periodic Phase Separation in Polymer Blends

Simulations were carried out for studying the periodic phase separation of a symmetric binary polymer blend on the basis of Cahn-Hilliard-Cook theory. The time dependent interaction parameter x（τ） was assumed to undergo a step-wise oscillation. The hierarchic structures composed of both large and small domains were obtained. The mechanism of the periodic formation of hierarchic structures was also demonstrated.

Cell Cycle Kinetic Analysis in the Cortical Regions of the Lentil Primary Root During Germination

Cell cycle kinetic activity in the cortical cells of the lentil (Lens culinaris Me-die. cv. Verte du Puy) primary root during germination was examined both temporally and spatially. Immunohistochemical and cytological evidence indicated that DNA replication and cell division started in the cortical cells of tire lentil primary root after around 13 and 17 h of imbibition, respectively. The first cells in DNA synthesis and the First mitotic figures all appeared in the cortical cells about I mm front the root-cap junction, but these divided cells had synthesized their DNA during the maturity of seed instead of during germination. The kinetic pattern of activity of the first cell cycle showed that these cells were not activated synchronously, but re-entered the cell cycle in turn depending on their places in the root tip, However, the adjacent cells partially synchronously proceeded their cell cycle.

A P.hysical Numerical Ionospheric Model and Its Simulation Results

This paper describes the construction of a one-dimensional time-dependent theoretical ionospheric model, which is based on numerical solution of continuity and momentum equations for , and NO+. The model is designed to have an option to incorporate the observational ionospheric characteristic parameters into the numerical model to indirectly determine the upper boundary condition when solving the transport equations of O+. A preliminary simulation result of the model when used to simulate the ionosphere during April 18 ~ May 10, 1998, which includes both quiet and disturbed periods, showed that the model constructed is able to reproduce the observational results reasonably well both for quiet and disturbed periods.

Investigation of the environmental impacts of steel deck pavement based on life cycle assessment

To investigate the environmental impacts of steel deck pavement through the whole life cycle,the steel deck pavement was divided into five stages:raw materials production,asphalt mixture mixing,pavement construction,operation management,and pavement removing stage.Based on the process-based life cycle assessment(PLCA)method,the calculation methods of energy consumption and gas emissions of two typical steel deck pavement systems(EA+EA pavement and GA+SMA pavement)were determined.The data lists of two pavements were analyzed,and the calculation model was built.Four characteristic indices including primary energy demand(PED),global warming potential(GWP),acidification potential(AP)and respiratory inorganics(RI)were used to quantify the environmental impacts of two pavements.The results show that the environmental impact of the GA+SMA pavement is more than 1.3 times that of the EA+EA pavement.Moreover,the critical stage of energy-saving and emission-reduction of EA+EA pavement and GA+SMA pavement are the raw material production stage and asphalt mixture mixing stage,respectively.

The ‘Two oceans and one sea' extended range numerical prediction system with an ultra-high resolution atmosphere-ocean-land regional coupled model

The‘Two Oceans and One Sea’area(West Pacific,Indian Ocean,and South China Sea;15°S–60°N,39°–178°E)is a core strategic area for the‘21st Century Maritime Silk Road’project,as well as national defense.With the increasing demand for disaster prevention and mitigation,the importance of 10–30-day extended range prediction,between the conventional short-term(around seven days)and the climate scale(longer than one month),is apparent.However,marine extended range prediction is still a‘blank point’in China,making the early warning of marine disasters almost impossible.Here,the authors introduce a recently launched Chinese national project on a numerical forecasting system for extended range prediction in the‘Two Oceans and One Sea’area based on a regional ultra-high resolution multi-layer coupled model,including the scientific aims,technical scheme,innovation,and expected achievements.The completion of this prediction system is of considerable significance for the economic development and national security of China.

Liver cell adenoma showing sequential alteration of radiological findings suggestive of well-differentiated hepatocellular carcinoma

A liver tumor 35 mm in diameter was found incidentally in a 40-year-old woman who had no history of liver diseases or the use of oral contraceptives.Radiological diagnostics showed the typical findings of liver cell adenoma(LCA).Dynamic computed tomography revealed that the tumor showed a homogenous enhancement in the arterial phase and almost the same enhancement as the surrounding liver parenchyma in the delayed phase.The tumor was found to contain fat on magnetic resonance imaging.A benign fat containing liver tumor was suggested.However,radiological findings altered,which caused us to suspect that a welldifferentiated hepatocellular carcinoma(HCC)containing fat was becoming dedifferentiated.Partial hepatectomy was performed and the pathological findings showed the typical findings of LCA.This case was an extremely rare LCA,which had no background of risk for LCA and developed the sequential alteration of the radiological findings to suspect well-differentiated HCC.

Variations and Controlling Factors of the Coccolith Weight in the Western Pacific Warm Pool over the Last 200 ka

Using a coccolith weight analytic software(Particle Analyser), we analyze most abundant coccolith species in a sediment core from the central Western Pacific Warm Pool(WPWP) and calculate coccolith size and weight variations over the last 200 ka. These variations are compared with the trends of sea surface temperature(SST), primary productivity(PP), sea surface salinity(SSS), and insolation. Our results demonstrate that the size and weight of the coccoliths varied in response to variations of these factors, and their average total weight is primarily related to the relative abundance of the dominant species GEO(Gephyrocapsa oceanica). The variation in weight of EMI(Emiliania huxleyi) and GEE(Gephyrocapsa ericsonii) are mainly influenced by nutrients, and the variation of GEM(G. muellerae conformis) and GEO(G. oceanica) weight are mainly influenced by SST. For all of the taxa weight, PP and SST present apparent precession or semi-precession cycles, we consider that the mono-coccolith weight of the Equatorial Western Pacific is primarily affected by precession drived thermocline and nutricline variation.

Analysis of the ionospheric variability based on wavelet decomposition

In this work,the ionospheric variability is analyzed by applying the wavelet decomposition technique to the noontime fo F2,F10.7,interplanetary magnetic field(IMF)Bz,Ap,and lower thermospheric temperature at pressure of 10?4 h Pa in 2002.Results show that the variance of periodic oscillations in the ionosphere is largest in the 2–4-day period and declines with the increase of the period.The maximum variance of the periodic oscillations in solar irradiation is in the 16–32-day period.For geomagnetic activities,most of the variance is about equally distributed on intervals of periods shorter than 32 days.Variance distributions of IMF Bz and lower thermospheric temperature are similar to those of the ionosphere.They show the maximum in the 2–4-day period and decline with the increase of the period.By analyzing the distributions of the variances,the potential connections between the ionosphere and the external sources are discussed.

Ambient stable FAPbI3-based perovskite solar cells with a 2D-EDAPbI4 thin capping layer

Two-dimensional(2D) lead halide perovskite materials are emerging as one of promising light-absorbing materials in perovskite solar cells(PSCs), which show outstanding stability and defect passivation. Unfortunately, the power conversion efficiency(PCE) of those stable 2D PSCs is still far behind that of 3D PSCs. Herein, we reported a simple in-situ growth technique for the ethylenediamine lead iodide(EDAPbI4) layer on the top of formamidinium lead iodide(FAPbI3) layer. The rationally designed layered architecture of2D-3 D perovskite film could improve the PCE of the PSCs. In addition, benefiting from the high moisture resistance and inhibited ion migration of EDAPbI4 layer, the 2D-3D-based devices showed obviously enhanced long-term stability,keeping the initial PCE value for 200 h and 90% of its initial PCE even after 500 h.

School Socioeconomic Segregation and Educational Expectations of Students in China＇s Junior High Schools

China＇s educational enterprise has achieved great successes since reform and opening up in 1978, but the constraints imposed by a number of factors mean that the problem of unequal distribution of high quality educational resources among groups from different strata is becoming increasingly noticeable at the basic education stage, leading to socioeconomic segregation in schools. We utilize baseline data from the China Education Panel Survey for 2013-2014 to investigate this phenomenon in junior high schools and its influence upon students＇ educational expectations. Our findings show that marked segregation currently exists at the junior high school level. The extent of the segregation varies from region to region and place to place （urban or rural）, and school socioeconomic composition （SEC） exerts a significant influence upon students＇ educational expectations. The higher the school＇s average SEC or the greater its heterogeneity, the higher the educational expectations of its students. The effect of school SEC upon the educational expectations of students varies depending on the characteristics of different student groups; students who have lower cognitive abilities and fall behind at school are more likely to benefit from an increase in school socioeconomic status （SES） and heterogeneity. Because educational expectationsare a decisive factor in academic achievement and educational attainment, the influence of school socioeconomic segregation upon educational equity should not be overlooked. Lessening the degree of school socioeconomic segregation and encouraging integrated schools would be an effective measure for ensuring educational equity in China.