Behavior of exciton in direct−indirect band gap Al_(x)Ga_(1−x)As crystal lattice quantum wells

Excitons have significant impacts on the properties of semiconductors.They exhibit significantly different properties when a direct semiconductor turns in to an indirect one by doping.Huybrecht variational method is also found to influence the study of exciton ground state energy and ground state binding energy in Al_(x)Ga_(1−x)As semiconductor spherical quantum dots.The Al_(x)Ga_(1−x)As is considered to be a direct semiconductor at AI concentration below 0.45,and an indirect one at the concentration above 0.45.With regards to the former,the ground state binding energy increases and decreases with AI concentration and eigenfrequency,respectively;however,while the ground state energy increases with AI concentration,it is marginally influenced by eigenfrequency.On the other hand,considering the latter,while the ground state binding energy increases with AI concentration,it decreases with eigenfrequency;nevertheless,the ground state energy increases both with AI concentration and eigenfrequency.Hence,for the better practical performance of the semiconductors,the properties of the excitons are suggested to vary by adjusting AI concentration and eigenfrequency.

Near-zone Direct and Indirect Topographic Effects Based on the Rectangular Prism and Surface Element

Helmert’s second method of condensation is an effective method for terrain reduction in the geoid and quasi-geoid determinations. Condensing the masses outside the geoid to a surface layer on the geoid produces several forms of topographic effects: direct effect on gravity, secondary indirect effect on gravity and indirect effects on the (quasi-) geoid, respectively. To strike a balance between computation accuracy and numerical efficiency, the global integration region of topographic effects is usually divided into near zone and far zone. We focus on the computation of near-zone topographic effects, which are functions of actual topographic masses and condensed masses. Since there have already been mature formulas for gravitational attraction and potential of actual topographic masses using rectangular prism model, we put forward surface element model for condensed masses. Afterwards, the formulas for near-zone direct and indirect effects are obtained easily by combining the rectangular prism model and surface element model. To overcome the planar approximation errors involved with the new formulas for near-zone topographic effects, the Earth’s curvature can be taken into account. It is recommended to apply the formulas based on the rectangular prism and surface element considering the Earth’s curvature to calculate near-zone topographic effects for high-accuracy demand to determine geoid and quasi-geoid.

Topographic effects observed at Amatrice hill during the 2016-2017 Central Italy seismic sequence

The estimate of seismic site effects by experimental approaches is based on different assumptions aimed at simplifying the complex actual site conditions and related uncertainties.However,the reliability of the results can increase if the experimental data is focused on quite strong seismic sequences and the on-site acquisition of a large number of signals is deemed strategic for the assessment of the expected phenomena.Based on these considerations,the ground motion at the Red Zone sector of Amatrice hill,violently struck by the 2016-2017 Central Italy seismic sequence,was analyzed via an observational approach.A large set of weak motions(moment magnitude Mw 2.5-3.9)was analyzed in this study by means of standard(SSR)and horizontal to vertical(HVSR)spectral ratio techniques.The results from the experimental analysis of the site effects by using weak motion and noise signals show a significant amplification at the top of Amatrice hill with a remarkable polarization of the motion and changes in spectral shapes according to the topographic setting of the relief.

THE OVERLOOKED ECOSYSTEM DRIVING FORCE IN NON-EUTROPHICATED FRESHWATER SYSTEMS:DISSOLVED HUMIC SUBSTANCES-A SHORT REVIEW AND OUTLOOK

This review starts with the description of the quantitative significance of dissolved organic material in general and dissolved humic substances (HS) in particular in various ecosystems. Despite their high quantities, the knowledge about the role of HS is still very low and full of old, but still recycled paradigms. HS are thought to be inert or at least refractory and too large to be taken up by aquatic organisms. Instead, I present evidence that dissolved HS that mainly derives from the terrestrial environment, are taken up and directly and/or indirectly interfere with freshwater organisms and, thus, structure biocenoses. Relatively well known is in the meantime the fuelling function of allochthonous HS, which, upon irradiation, release fatty acids, which serve as substrates for microbial growth. This is an indirect effect of HS. Microbes, in turn, are food for mixotrophic algae and (heterotrophic) zooplankton. Thus, non-eutrophicated freshwaters are net-heterotrophic, meaning that respiration exceeds primary production. Furthermore, model calculations exemplify that only a very small portion of the terrestrial production is sufficient to cause net-heterotrophy in these freshwater bodies. But, recent papers show also that due to different stoichiometries the maximal plankton biomass production with algae or mixotrophs is higher than with bacteria. Very recently, several direct effects of HS have been elucidated. Among them are:induction of chaperons (stress shock proteins), induction and modulation of biotransformation enzymes, modulation (mainly inhibition) of photosynthetic oxygen release of aquatic plants, production of an internal oxidative stress, modulation of the offspring numbers in the nematode Caenorhabditis elegans[WTBZ], feminization of fish and amphibs, interference within the thyroid system, and action as chemical attractant to C. elegans. We are still in the phase of identifying the various physiological, biochemical, and molecular-biological effects. Hence, the ecological and ecophysiological significance of these HS-mediated effects still remain somewhat obscure. Nevertheless, HS appear generally to have an impact on the individual as well as on the community and even ecosystem level comparable to that of, for instance, nutrients.

The mediating role of export-oriented Japanese foreign direct investment in China

Since the early 1990s, China has become the largest destination of Japanese foreign direct investment （FDI）. Observing this trend, the authors analyzed whether Japanese FDI did promote exports from China to the rest of the world, and more importantly, whether this is a strategy adopted by Japanese multinationals to penetrate not only the Chinese market but also the global market. This analysis takes into account not only the direct effects of FDI on exports, but also the indirect effects, by examining the mediating role of export oriented Japanese FDI in China from 1998 to 2007 through panel analysis. The study contributes to the conceptual framework of indirect relationship among the macroeconomic variables, FDI and exports provides some insights into the strategy of export oriented Japanese FDI in creating a win-win platform for Japan and China.

政府R&D补贴的技术创新效应分析--基于2009-2021年中国的经验数据

政府R&D补贴既可以通过提供公共服务的方式直接作用于技术创新,也可以通过对社会资本的引导作用间接影响技术创新,其总效应取决于两种影响的方向与大小。基于2009—2021年中国的经验数据,建立了由技术创新方程和引致方程共同组成的动态模型,对政府R&D补贴的技术创新效应进行了实证分析。结果发现:持续增加的政府R&D补贴带来了国内专利授权数量的稳定增加,技术创新效应较为显著;政府R&D补贴不仅对技术创新产生了积极的直接影响,也通过引导社会资本投资于研发领域而对技术创新产生了积极的间接影响;政府R&D补贴的技术创新效应存在区域差异,中东部地区为正,而西部地区为负。提高资金使用效率、积极引导社会资本投资技术研发、努力改善欠发达地区的研发环境,无疑是提高政府R&D补贴技术创新效应的必要选择。

飞机及分系统雷电效应标准及测试浅析

对国内外关军用及民用飞机平台、分系统及设备雷电标准进行分析,针对雷电直接效应和雷电间接效应的所有测试项目,详述每个测试项目的适用区域、波形要求、测试配置等。结合现有国内雷电设计验证标准及测试存在的不足,提出提升测试设备与试验验证技术匹配性、扩展军用标准测试领域、统一同军种同一平台要求等建议。通过对军用机载平台、设备及分系统关于雷电设计验证标准及测试的分析,为相关产品设计师及试验人员提供设计指标参考,明确产品关于雷电防护的设计要求及验证要求,做到有的放矢,提高设计费效比。

绿色金融、碳交易与产业绩效:影响机理及中国7个试点的力证

目前,各界对绿色金融和碳交易影响产业绩效的认知和预期仍相对模糊或片面。基于实际发展进程与客观诉求,对C-D生产函数进行重构与改进,通过实证分析验证绿色金融和碳交易影响产业绩效的动态机制。结果表明:直接影响,绿色金融和碳交易的导入会短暂阻碍产业绩效的提升,但跨越“拐点”后可显著促进产业发展;间接影响,绿色金融和碳交易的推进均存在一个最佳时间段,不仅可通过生产要素影响产业绩效,而且可促进“劳动密集型”向“资本密集型+能源密集型”的结构升级;现阶段绿色金融和碳交易的相互影响不具有对称性。只有对“试点建设”成功经验和作用规律进行科学总结才可为“全国推广”奠定坚实基础。

PRELIMINARY NUMERICAL STUDY OF TOPOGRAPHIC EFFECTS OF THE TIBETAN PLATEAU ON SURFACE DIRECT RADIATION

To improve the simulating ability of a model,this paper presents a scheme of calculating direct radiation at land surface with topography in the model.A numerical study is conducted for the topographic effects of the Tibetan Plateau on the direct radiation using NCEP terrain data. Results show that,after taking account into the topographic radiation effect,the regional average of the radiation over the Plateau obviously increases in the local early morning and late afternoon, but changes less around noon.The effect is stronger in winter than that in summer.And heterogeneous topography has also affected the distribution of the radiation in this area.A simple numerical experiment shows that considering the effect will lead ground temperature to increase on the slope having more sunshine,and vice versa.

Dynamics and Responses of Vegetation to Climatic Variations in Ziya- Daqing Basins, China

Examining the direct and indirect effects of climatic factors on vegetation growth is critical to understand the complex linkage between climate change and vegetation dynamics. Based on the Moderate Resolution Imaging Spectroradiometer(MODIS) Normalized Difference Vegetation Index(NDVI) data and meteorological data(temperature and precipitation) from 2001 to 2012, the trend of vegetation dynamics were examined in the Ziya-Daqing basins, China. The path analysis was used to obtain the information on the relationships among climatic factors and their effects on vegetation growth. It was found that the trends of growing season NDVI were insignificant in most plain dry land, while the upward trends were significant in forest, grass and dry land in Taihang Mountains. According to the path analysis, in 23% of the basins the inter-annual NDVI variation was dominated by the direct effect of precipitation, in 5% by the direct effects of precipitation and temperature, and in less than 1% by the direct effect of temperature or indirect effects of these two climatic factors. It indicated that precipitation significantly affected the vegetation growth in the whole basins, and this effect was not regulated by temperature. Precipitation increase(especially in July, August and September) was favorable to greenness enhancement. Summer temperature rising showed negative effect on plant productivity enhancement, but temperature rise in April was beneficial for the vegetation growth. When April temperature increases by 1℃, the onset date of greenness for natural vegetation will be 2 days in advance. There was a lag-time effect of precipitation or temperature on monthly NDVI for all land use types except grass.

Correlation and Path Coefficient Analyses of Cowpea (<i>Vigna unguiculata</i>L.) Landraces in Ethiopia

Understanding the nature and extent of association between yield and yield related traits is the prerequisite study for any underutilized crop improvements of sustainable genetic enhancement. However, there is a lack of sufficient information on seed yield and related trait correlation and path coefficient analysis of cowpea in Ethiopia. To fill the existing knowledge gap, the present study was conducted to determine the nature and extent of phenotypic and genotypic correlation and path coefficient analysis among 18 quantitative traits. A total of 324 cowpea landraces were tested in 18 × 18 simple lattice design at Melkassa Agricultural Research Center and Miesso sub center during 2016 cropping season. The magnitude of genotypic correlations was higher than phenotypic correlations in most traits at both locations;this implies that the traits under consideration were genetically controlled. Seed yield was positively and highly significantly correlated with most of the traits at phenotypic and genotypic levels, indicating the presence of strong inherited association between seed yield and the other 17 traits. Almost all traits genotypic direct and indirect effects were higher than the phenotypic direct and indirect effects;this indicated that the other traits had a strong genetically inherited relationship with seed yield. Genotypic path coefficient analysis revealed that days to flowering, biomass and harvest index at Miesso, and seed thickness, plant height, days to maturity and biomass at Melkassa had relatively high positive direct effect on seed yield. However, seed width and hundred seed weight had exerted negative direct effect on seed yield at each location. Phenotypic path coefficient analysis showed that biomass and harvest index had exerted high positive direct effect on seed yield at both locations. From these results it can be concluded from this study that seed yield in cowpea can be improved by focusing on traits pod length, seed length, seed thickness, seed width, biomass and harvest index at both locations. The information obtained from this study can be used for genetic enhancement of cowpea thereby developing high yielding varieties.

The Role of Clouds in Global Radiation Changes Measured in Israel during the Last Sixty Years

An analysis of global radiation measurements and fractional cloud cover observations made in the Israel Meteorological Service’s network of climate stations demonstrated a significant decrease in the transmittance of solar radiation through the atmosphere during the last 60 years. The major cause was the reduced transparency of clouds. Under completely overcast skies with complete cloud cover transmission in the industrialized central coastal region decreased from 0.41 in the mid-20th century to 0.21 in the first decade of the 21st century. Under cloudless skies the reduction in the transmission of global radiation was less, from 0.79 to 0.71, and not statistically significant. Similar but somewhat smaller changes were observed in the less industrialized central hill region. Multi-linear analysis showed that since 1970, 61% of the measured decline in global radiation was attributable to changes in fractional cloud cover but only 2% to the marked increase in local fuel combustion;there was no statistically significant interaction between the two parameters.

中国区域碳生产率的空间特性及影响因素分析

基于2006—2021年中国30个省的碳生产率测算及空间特征,采用邻接、经济和地理矩阵下的空间杜宾模型,实证检验了各影响因素对碳生产率的直接效应和间接效应。研究表明:从空间特征来看,我国碳生产率表现为“发达聚集,欠发达分散”的特征;从作用效果来看,城镇化、产业结构和能源结构对本地区及相邻地区碳生产率均具有显著的抑制作用,经济发展水平具有显著的促进作用,而绿色技术创新和FDI对本地区碳生产率具有显著的促进作用但对相邻地区具有显著的抑制作用;从作用大小来看,经济发展水平对碳生产率的促进作用最大,绿色技术创新的促进作用最小,FDI的抑制作用最大,能源结构的抑制作用最小;从区域异质性来看,经济发展水平在西部的提升作用不显著;FDI在西部表现出负溢出效应。建议从完善外商政策、降低能源强度、加快绿色技术创新和促进产业结构高级化来助力碳生产率提升。

高等教育质量提升的“增长绩效”

通过测算宏观层面的高等教育质量指数,对全国和地区样本内高等教育质量提升所带来的“增长绩效”进行了综合检验。研究发现:首先,高等教育质量提升对经济增长带来了“直接效应”,即高校扩招以来虽然我国高等教育质量的提升幅度总体较小,但却不可忽视其在经济高速增长中的重要作用。其次,高等教育质量提升对经济增长带来了“间接效应”,即高等教育质量提升通过促进科技创新而间接地带来了社会总产出的增加。最后,在吸收外地高等教育质量提升对本土增长绩效的外溢作用的力度上,“直接效应”在东部地区最强,中部和西部地区则不显著;“间接效应”在东部和中部地区均为正,而在西部地区则为负,这与“西北有高楼”和“孔雀东南飞”的要素流向现实极为吻合。

垄断行为反竞争效果的直接证明方法

直接证明方法和间接证明方法都是反垄断法合理原则第一步骤中,原告证明行为反竞争效果,进而转移举证责任的分析方法。直接证明方法的法理逻辑是,原告如果提供了表明行为实际反竞争效果的直接证据,便没有必要再进行相关市场界定和市场结构分析。相较于间接证明方法的风险和困境,直接证明方法可以简化反垄断分析框架,并且使其更具连贯性。在我国已有实践的基础上完善直接证明方法,需要合理设置适用范围,并且在消费者福利标准下确定实际反竞争效果的考量因素。同时,直接证明方法与间接证明方法之间并不是对立的,保持两者之间的互补性适用是我国现阶段的可行方案。

低温烟气余热回收核心设备应用分析

综合分析了烟气换热器和溴化锂吸收式热泵在低温烟气余热回收中的特点和适用性。在烟气换热器选择方面,间接接触式换热器相较于直接接触式换热器体积更小、阻力更低、占地更少、系统更简单,但低温水温度要求更低。在溴化锂吸收式热泵选择方面,重点分析了单效溴化锂吸收式热泵和双效溴化锂吸收式热泵的供热特性及与不同换热器的匹配使用情况。实际应用表明:双效热泵供热温度低、效率高,适合与直接接触式换热器匹配;而单效热泵适用性更强,应用更广泛,2种换热器都可匹配。

数字金融对碳排放的直接与间接效应——基于省级面板数据的实证分析

近年来,数字金融发展迅速,绿色金融工具的广泛应用有助于缓解碳排放的压力,为实现“双碳”目标提供了现实方案。基于30个省(区、市)2011—2019年面板数据,检验数字金融对碳排放的影响及作用机制。研究发现:数字金融对碳排放具有明显的直接效应,并通过优化产业结构对碳排放产生间接效应;且直接效应在中东部地区显著,在西部地区不显著;间接效应均不显著,其中在中东部表现为遮掩效应。最后,从促进数字金融产业发展、数字金融引导产业结构优化、区域金融发展平衡等方面提出相应对策建议。

Effects of elevated temperature on chemistry of an invasive plant,its native congener and their herbivores

Climatic warming affects plant growth and physiology,yet how warming alters chemistry in invasive plants and indirectly affects herbivorous insects remains largely unknown.Here,we explored warming-induced changes in leaf chemistry of the invasive plant Alternanthera philoxeroides and its native congener Alternanthera sessilis,and further examined how these changes affected the performance of the herbivores,Cassida piperata and Spodoptera litura.We conducted a simulated warming experiment to address its effects on 13 leaf chemical traits of A.philoxeroides and A.sessilis.We measured growth and development time of two herbivores reared on plants from warming or ambient controls.Warming significantly affected leaf chemistry composition for both the invasive and native Alternanthera.Warming decreased nitrogen concentration in A.philoxeroides and increased total flavonoid and total phenol concentration in A.sessilis.The effects of warming on nutrients(i.e.fructose,sucrose,total soluble sugar and starch)varied with individual chemicals and plant species.Weight of C.piperata pupal and S.litura larval reared on warming-treated A.sessilis significantly decreased compared with non-warmed control,and a similar pattern was observed for weight of S.litura larval feeding on warming-treated A.philoxeroides.In addition,warming-treated A.sessilis significantly prolonged larval development time of S.litura.These results indicate that warming can directly affect the leaf chemistry in both invasive plant and its native congener,but these effects vary by species.Such differences in warming-induced changes in plant chemistry could indirectly affect herbivorous insects associated with the invasive and native plants.

基于SEM的客车出行者出行路径选择行为研究

为探究高速公路客车出行者出行路径选择行为的影响因素及影响关系,本研究以问卷调查的方式获取了206名客车出行者出行路径选择行为数据.通过构建结构方程模型,确定了出行路径选择影响因素,分析了因素对路径选择的直接和间接影响,结果表明:出行习惯对出行路径选择有直接影响;驾驶经验在出行特征和出行习惯的中介下对出行路径选择有间接影响;出行特征在出行习惯的中介下对出行路径选择有间接影响.此外,还发现影响因素间存在相互影响,出行特征对出行习惯有直接影响;驾驶经验不仅对出行特征有直接影响,还在出行特征的中介下对出行习惯有间接影响.基于研究结果提供了缓解高速公路拥堵的相关建议.

地形对确定高精度局部大地水准面的影响

以计算香港大地水准面为例 ,着重研究了以下几点 :①DTM的分辨率对地形改正的影响 ;②质量柱体地形模型与质量线地形模型对计算地形改正的差异 ;③采用Helmert凝聚改正法 ,计算地形对大地水准面的间接影响 ;④比较经典Stokes