Comments on: “Underwater measurements of carbon dioxide evolution in marine plant communities: A new method” by J. Silva and R. Santos [Estuarine,Coastal and Shelf Science 78(2008) 827–830]     

Gwenaël Abril 《Estuarine, Coastal and Shelf Science》2009

Silva et al. propose a new method for quantifying benthic net community production (NCP) of tidal flats under submerged condition, based on the monitoring of water pCO₂ in a transparent benthic chamber around high tide. I demonstrate here with theoretical considerations that this method is inappropriate for coastal environments, because it allows only the quantification of the change in the dissolved CO₂ which, at classical seawater pH, is only ∼10% of the change of the dissolved inorganic carbon (DIC). Total Alkalinity and/or DIC must be measured at the beginning and end of incubations in order to compute NCP in coastal environments. However, I also demonstrate that when pH is below 7, more than 95% of the DIC change occurs in the CO₂ pool. The method proposed by Silva et al. is thus valuable for freshwater environments with acidic, low alkalinity waters, where monitoring the water pCO₂ in a vial or chamber provides alone a very close approximation of the planktonic or benthic net community production.  相似文献   

高精度距离等比例线法海洋划界模型研究          下载免费PDF全文

彭认灿  董箭  陈轶  郑义东  陈惠荣 《海洋测绘》2009,29(4):14-18

分析表明，目前国内外只对距离等比例线法海洋划界模型作了初步的研究，所建立的模型仍然停留在欧氏平面或地图投影平面上，无法满足海洋划界对分界线点位精度的要求。为改变这种局面，提出并建立了一种全新的基于地球椭球体缓冲区构建技术的高精度距离等比例线法——椭球面距离等比例水线法海洋划界模型。  相似文献   

手机游戏中的2D卷轴算法及其实现     

谢海军  陶宏才 《成都信息工程学院学报》2007,22(4):445-449

详细介绍2D卷轴游戏中的两种算法--整体Copy算法和四分缓冲区算法及其实现,并对比两者的差异.相对PC开发平台而言,手机平台有运算速度慢、内存容量小的特点.因此,对于2D卷轴游戏,提高游戏的FPS是游戏引擎开发程序员面临的重要的技术问题.两种算法都对游戏的FPS有很好的支持,其中,整体Copy算法的理解和编程实现都相对较为容易,而四分缓冲区算法对游戏性能的提高则更为明显.  相似文献   

Influence of small-molecule material on performance of polymer solar cells based on MEH-PPV:PCBM blend     

刘晓东  徐征  张福俊  赵谡玲  张天慧  龚伟  宋晶路  孔超  闫光  徐叙瑢 《海洋学报(英文版)》2010,29(11)

In this work, the influence of a small-molecule material, tris(8-hydroxyquinoline) aluminum (Alq₃), on bulk heterojunction (BHJ) polymer solar cells (PSCs) is investigated in devices based on the blend of poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV) and [6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM). By doping Alq₃ into MEH-PPV:PCBM solution, the number of MEH-PPV excitons can be effectively increased due to the energy transfer from Alq₃ to MEH-PPV, which probably induces the increase of photocurrent generated by excitons dissociation. However, the low carrier mobility of Alq₃ is detrimental to the efficient charge transport, thereby blocking the charge collection by the respective electrodes. The balance between photon absorption and charge transport in the active layer plays a key role in the performance of PSCs. For the case of 5 wt.% Alq₃ doping, the device performance is deteriorated rather than improved as compared with that of the undoped device. On the other hand, we adopt Alq₃ as a buffer layer instead of commonly used LiF. All the photovoltaic parameters are improved, yielding an 80% increase in power conversion efficiency (PCE) at the optimum thickness (1 nm) as compared with that of the device without any buffer layer. Even for the 5 wt.% Alq₃ doped device, the PCE has a slight enhancement compared with that of the standard device after modification with 1 nm (or 2 nm) thermally evaporated Alq₃. The performance deterioration of Alq₃-doped devices can be explained by the low solubility of Alq₃, which probably deteriorates the bicontinuous D-A network morphology; while the performance improvement of the devices with Alq_3 as a buffer layer is attributed to the increased light harvesting, as well as blocking the hole leakage from MEH-PPV to the aluminum (Al) electrode due to the lower highest occupied molecular orbital (HOMO) level of Alq₃ compared with that of MEH-PPV.  相似文献   

Entire Catchment and Buffer Zone Approaches to Modeling Linkage Between River Water Quality and Land Cover——A Case Study of Yamaguchi Prefecture, Japan     

Bahman Jabbarian AMIRI Kaneyuki NAKANE 《中国地理科学(英文版)》2008,18(1):85-92

This study investigated the linkages between river water quality and land use in river catchments in Yamaguchi Prefecture, the western Japan, in order to examine the effect of land use changes of both entire catchment and buffer zone on river water quality. Dissolved Oxygen （DO）, pH, Biological Oxygen Demand （BOD）, Suspended Solids （SS）, Escherichia coli, Total Nitrogen （TN） and Total Phosphorus （TP） were considered as river water quality indicators. Satellite images were applied to generating the land use map. Multiple regression model was applied to linking the changes in the river water quality with the land uses in both entire catchment area and buffer zone. The results indicate that the integrative application of land use data from the entire catchment and the buffer zone could give rise to more robust model to predict the concentrations of Suspended Solids （r^2=0.88） and Total Nitrogen （r^2=0.90）, rather than models which separately considered land use data in catchment and buffer zone.  相似文献   

基于GIS的塌陷分布与地质要素关系研究--以广西省来宾市吉利村为例     

何素楠  周国清  李毅夫  陈昆华 《东北测绘》2014,(2):38-42

以岩溶地貌发育强烈的广西省来宾市吉利村为研究实例,首次借助于GIS缓冲区分析方法,通过对其塌陷程度的调查,结合研究区的地质状况,分析塌陷点分布位置与地质要素的关系。研究结果表明：塌陷点的分布位置主要与岩溶发育程度、地下河和断裂构造有关,与其他地质要素关系不大。这项研究为下一步岩溶塌陷成因的研究提供了参考数据,为当地经济发展布局和岩溶塌陷的防治工作提供了科学依据。  相似文献   

多源矢量道路匹配方法研究     

刘一宁 《现代测绘》2014,(2):16-18

地理信息服务的基础是数据,要求数据现势性强,信息可靠。随着经济、科技的发展,地理数据的获取方式越来越丰富,卫星遥感、GPS等等都已经成为获取数据的技术手段。基于此,本文根据生产中的实际需要,探讨了矢量道路的匹配方法,并将其分为同源和非同源数据进行分类研究,作为道路变化检测的基础。最后根据研究方法予以实验,验证其有效性。  相似文献   

Effects of forest roads on habitat pattern for sables in Da Hinggan Mountains,northeasten China     

Yuehui Li  Wen Wu  Zaiping Xiong  Yuanman Hu  Yu Chang  Duning Xiao 《中国地理科学(英文版)》2014,24(5):587-598

The anthropogenic managements of forest have created a network of roads resulting in the loss and alternation of habitat. To better understand road＇s impact on animal habitats, we assessed the habitat pattern of sables （Martes zibellina）, one of rodents within national first-class protected species, when roads are considered in Huzhong area in Da Hinggan Mountains, northeastern China. Em- ploying published literatures about behavior ecology, aerial photographs and forest stand maps, we classified the study area into three habitat types including best-suitable, suitable and unsuitable habitats based on sable habitat requirements at the landscape scale includ- ing four variables derived from forest source map with attribute database. Results indicated the loss and significant fragmentation of best-suitable habitat and home range habitat when roads, especially 150 m avoidance distance of roads, were considered. The roads re- duced and fragmented highly suitable habitats more significantly during earlier development period than the later development period. Additionally, the suitable area percentage increased with increasing distance to roads. This study helped to identify the suitable area for sables and location of sable population. Also, this study suggested the passage construction and road management involving road clo- sure and removal will reduce the fragmentation functionally and benefit the sable population.  相似文献   

几何部件缓冲区域合并的Buffer算法及其并行优化方法     

范俊甫  马廷  周成虎  季民  周玉科  许涛 《测绘学报》2014,43(9):969-975

摘 要：本文在介绍一种基于几何部件缓冲区域合并的矢量数据缓冲区生成算法的基础上,采用数据并行思想和MPI编程模型对缓冲区算法的并行化实现和优化方法开展研究。实验结果显示,与ArcGIS Buffer工具相比,（1）当缓冲区结果多边形不合并时,虽然串行缓冲区算法的时间开销较高,但可轻易通过并行方式实现加速。（2）当缓冲区结果合并时,本文算法要明显优于ArcGIS Buffer工具,并且经过优化的并行缓冲区算法表现出了更高的计算效率和更大规模的数据处理能力。因此,基于几何部件缓冲区域合并的Buffer算法具备一定的实用价值,本文提出的按结点数量的任务分解方法和进程间结果“树状”归并策略是对缓冲区算法进行并行优化的有效途径,对GIS中其他矢量分析算法的并行化及相关优化工作也具有一定的借鉴意义。  相似文献   

温度对POP Rb原子钟性能影响的研究     

薛文祥  陈江  杜志静  张首刚 《时间频率学报》2012,35(3):129-136

从温度对缓冲气体碰撞频移和弛豫率的影响出发,对充有Ar和N2这2种缓冲气体的POP(pulsed optically pumped,脉冲激光抽运)汽泡式铷原子钟的温度特性进行了理论和实验研究。研究表明,Ar与N2的气压比为1.6时,60℃的线性温度系数为0;不同温度时,布居数差弛豫率1和相干弛豫率2各不相同,若1 2,则POP铷原子钟Ramsey条纹包络在微波场与原子跃迁失谐为0附近为凹陷,信噪比较差,反之,为凸起,信噪比较高。研究结果对设计POP原子钟的缓冲气体气压比和工作温度,以及提高POP原子钟的中长期稳定度有一定借鉴作用。  相似文献