国内外数字资源长期保存研究现状与进展

本文首先对数字资源长期保存国际会议(IPRES)以及国外具有代表性的启动项目进行简要介绍,进而分析我国数字资源长期保存的研究现状,通过比较国内外研究现状及进展情况,找出我国与国外的差距,并提出我国数字资源长期保存的几点建议。

关于数字信息长期保存的元数据

在简要介绍数字信息长期保存体系框架OAIS的基础上 ,介绍了CEDARS、PANDORA/NLA。

MANET中基于蚁群的网络核心提取分布路由协议

提出了一个用于移动Ad Hoc网络(MANET)的基于蚁群的核心提取分布路由协议——Ant-CEDAR,该协议使用类似蚁群的移动代理获得高效的路由,从而可加强核心提取分布Ad Hoc路由算法(CEDAR)。对Ant-CEDAR协议进行了模拟实验,实验数据表明该协议具有高效性和低耗性。

An Unduly Withered Rose--Analyses of Rena＇s Tragic End

Since its publication, Charles W·Chesnutt's first novel The House Behind the Cedars has drawn great attention, mostly because of the heroine's tragic end, the issue of passing for white, miscegenation and other race problems involved. It is the oppression from males and the prejudice from the whites that results in the heroine's tragic fate.

Longevity of Juniperus procera seed lots under different storage conditions: implications for ex situ conservation in seed banks

Juniperus procera Endl. is economically important timber species, but its populations are extremely small and fragmented in its natural habitat, thus, calling for immediate ex situ conservation. Here we examined the effects of seed sources and storage temperature on the longevity of Juniperus procera seed lots through collection and preservation of seeds in seed banks. Seeds were collected from nine sites across the species natural distribution in Ethiopia and stored in four warehouses： modern cold room （5℃）, mud house （15℃）, concrete block house （17℃ or corrugated iron house （20℃） for 42 months. Every three months, a random sample of stored seeds were drawn and tested for germination. A highly significant variation （p 0.01） in germination of stored seeds was observed among different storage environments, seed lots, and duration of storage. Over the storage period, seeds stored in the cold room had the highest mean percentage germination, followed by the mud house, corrugated house and blocket house. The cold room （41%） and the mud house （38%） maintained the same level of germination as the intitial germination of the seedlotds （42%）. The variation in longevity of stored seeds was significnatly correlated with the initial germination of seed lots （r 0.80; p 0.01）. Cold storage also resulted in enhancement of germination through its stratification effect that terminated the non-deepphysiological dormancy of juniper seeds. In conclusion, seed lots with good initial germination can be effectively stored in cold room （5℃） up to four years. In the absence of modern cold stores, mud houses can be used as a good alternative to store seeds at local level.

Spatial Variations in Particle Size and Magnetite Concentration on Cedar Beach:Implications for Grain-Sorting Processes,Western Lake Erie,Canada

This study examined spatial variations in the concentration,grain size and heavy mineral assemblages on Cedar Beach（Lake Erie,Canada）.Magnetic studies of heavy mineral-enriched,dark-reddish sands present on the beach showed that magnetite（～150μm） is the dominant magnetic mineral.Surficial magnetic susceptibility values defined three zones：a lakeward region close to the water line（Zone 1）,the upper swash zone（Zone 2） and the region landwards of the upper swash zone （Zone 3）.Zone 2 showed the highest bulk and mass susceptibility（κ,χ） and the highest mass percentage of smaller grain-size（250μm） fractions in the bulk sand sample.Susceptibility（i.e.κandχ） values decreased and grain size coarsened from Zone 2 lakewards（into Zone 1） and landwards （into Zone 3）,and correlated with the distribution of the heavy mineral assemblage,most probably reflecting preferential separation of large,less dense particles by waves and currents both along and across the beach.The eroded western section of Cedar Beach showed much higher concentrations of heavy minerals including magnetite,and finer sand grain sizes than the accreting eastern section, suggesting that magnetic techniques could be used as a rapid,cost-effective way of examining erosion along sensitive coastline areas.

基于分布式数据库Cedar的高效工单管理系统设计与实现

随着互联网发展,企业随之转型,积极开展基于互联网的业务.传统业务系统架构基于集中式数据管理系统如MySQL之上,在封闭使用状态向开放使用状态转换的过程中,逐渐在可用性上暴露出弊端,故而不能很好地支持业务拓展规模化、分布式处理的要求.网络业务的开展对工单系统提出了在支持大数据、高并发、高冲突、高可用下保证处理高效性的新需求.在深入分析当前业务特征的基础上,利用分布式数据库Cedar,基于Netty通信框架,以海尔的工单业务为实例,设计并实现了支持工单存储、派单以及工程师抢单业务的高效、可扩展工单管理系统,详述了系统的可靠性和可扩展实现.经实验表明,该工单系统在保证高吞吐和低延迟的同时具有良好的可扩展性和可用性.

Impact of a Low Severity Fire on Soil Organic Carbon and Nitrogen Characteristics in Japanese Cedar Soil, Yamagata Prefecture, Japan

Slash and burn practices are widely used around the globe with different degrees of success which are mostly related to the impact of fire on soil properties. In Japan slash and burn practises, known as Yakihata, have a long history and are still used in Yamagata Prefecture today. The purpose of this study was to determine the impact of a low severity controlled fire underneath Japanese cedar (Cryptomeria japonica) on brown forest soil (Cambisol). Japanese Cedar is the dominant species among plantations in Japan. We measured organic carbon and nitrogen content as well as changes in carbon (δ13C) and nitrogen (δ15N) stable isotope composition in a steep west facing slope under heavy precipitation (~2600 mm/a) and heavy snowfall (~3 to 4 m/a). The accumulation of Ctotal and Ntotal at the bottom of the slopes was remarkably higher at the slash and burned site than in the control forest site. After slash and burn δ15N isotopes in the slope in general became significantly lighter than in the control forest while the δ13C did not show any significant difference between the two sites except at the bottom of the slopes where δ13C was heavier in the forest. The results show that Ctotal and Ntotal values as well as the isotopes ratios of C and N change with decreasing elevation in the forest as well as in the burned site being consistent with leaching and erosion. The changes in soil nitrogen and carbon isotopes at the bottom of the slope appear to be related to the transport of material with different isotopic composition from the upper slope. The effect of the low severity fire (as part of the slash and burn practice) on soil organic carbon and nitrogen movement was enhanced by the steepness of the slopes and the high precipitation of Shonai region.

Cedar Pollen and Cedar Pollinosis

Objective To investigate the prevalence of cedar pollinosis in China, and compare Cryptomeria fortunei(Cf) with Cryptomeria japonica (Cj) morphologically. Methods\ An epidemiological survey on nasal allergy was carried out among 1 660 primary and middle school students and 1 620 university students, including questionnaire investigation, nasal inspection by the same doctor and scratch test with the allergen extract of Cj. The pollen of Cf and Cj were observed by optical and electron microscope. The genes of chloroplast of them were analysed. Results ①The total positive rate of cedar pollen scratch test was 4.2%. 55 cases of nasal allergy were confirmed according to the criteria of diagnosis, in which 8 cases showed positive reaction to Cj and only 1 case was hypersentive to it. ②No significant distinction between Cf and Cj was found by optical and electron microscope and no difference in gene analysis was found. Conclusion\ ①Cedar pollinosis does exist in China. It′s low prevbalence is related to the low quantity of cedar pollen.②Cf and Cj are of the same family and genus. ③There may be an increasing tendency of cedar pollinosis in China.\;

Spatial Variations in Particle Size,Heavy Mineral Assemblage and Magnetic Concentration of Dark-reddish Sands on Cedar Beach,Western Lake Erie,Ontario,Canada

Environmental magnetic research on beaches and shoreline processes is limited.Therefore,we carried out environmental magnetic studies on the heavy mineral-enriched,dark-reddish sands on Cedar Beach of western Lake Erie(41.68°N,82.40°W).Magnetite has been identified as the dominant magnetic mineral of these sands.This study reveals a spatial variation in concentration of magnetite particles,distribution of

Environmental control of daily stem radius increment in the montane conifer Cedrus libani

Growth response of conifers is species-specific and depends on site and climate conditions.Studies on daily radial stem growth use different analytical approaches to determine species reactions to environmental conditions.These results contribute to improve forecasts of tree growth under a changing climate.During 2013 and2014,radial stem growth of 33 mature Cedrus libani individuals growing under different climatic conditions in Turkey and Germany was monitored hourly using high precision point dendrometers.Stem radius increments(SRI)were extracted from dendrometer readings.The annual course of SRI showed site-specific patterns with mean daily values ranging between 9.9 and 29.3μm over the growing season.Correlation and principal component analyses indicated that humidity and low temperatures during the growing season favored SRI.Multiple regression analyses demonstrated that precipitation and relative air humidity were the most important factors influencing daily SRI.Climate-growth relationships were further evaluated using the regression tree method.Precipitation was the most significant factor on daily SRI for all sites.The close coupling of SRI to relative air humidity and precipitation underlines the importance of stem water status for radial stem growth of C.libani which is native to regions with summer drought.It further explains the superior growth of C.libani in Germany.

Structure and dendroecology of Thuja occidentalis in disjunct stands south of its contiguous range in the central Appalachian Mountains, USA

Background： Information on forest structure, growth, and disturbance history is essential for effective forest management in a dynamic landscape. Because most of our research concerning the ecology and growth of Thujo ocddenralis comes from sites in northern portions of its range, highly contextual biotic and abiotic factors that affect the species in more southern locales may not be fully accounted for. This research characterized the structural attributes and growth dynamics of Thuja occidentolis in disjunct forest stands south of its contiguous range margin. Methods： The Thujo occidentalis forests examined in this research were located in the central Appalachian Mountains, USA, approximately 440 km south of the contiguous range margin of the species. Forest structural attributes were characterized in two Thujo occidentalis forest stands, which are rare in the region. Tree-ring chronologies were used to examine the influences of disturbance and climate on the growth of Thuja occidentolis. Results： The forests contained a total of 13 tree species with Thuja occidentalis contributing substantially to the basal area of the sites. Thujo occidentalis stems were absent in the smallest size class, while hardwood species were abundant in the smallest classes. Thuja occidentalis stems also were absent from the 〈 70 years age class. By contrast, Thuja occidentalis snags were abundant within stands. Growth-release events were distributed across the disturbance chronology and generally affected a small number of trees. The Thujo occidentolis tree-ring chronology possessed an interseries correlation of 0.62 and mean sensitivity of 0.25. The correlation between mean temperature and Thuja occidentalis growth was weak and variable. Growth and moisture variables were more strongly correlated, and this relationship was predominantly positive. Conclusions： Structural attributes indicate the forests are in the understory reinitiation stage of forest development. Silvicultural manipulations may be necessary to promote Thujo occidentalis establishment. The sensitivity of Thujo occidentalis to climate appears similar throughout its range, but geographical variation in the growth response to climate factors is apparent. More research is necessary to expand the geographical and ecological scope of our knowledge concerning Thuja occidentalis, particularly at more southern and disjunct sites.

Impacts of Land Cover Changes on Runoff and Sediment in the Cedar Creek Watershed,St.Joseph River,Indiana,United States

The relation between runoff and sediment and land cover is investigated in the Cedar Creek Watershed （CCW）, located in Northeastern Indiana, United States. The major land cover types in this watershed are cultivated land, woodland and pasture /Conservation Reserve Program （CRP）, which account for approximate 90 % of the total area in the region. Moreover, land use was changed tremendously from aooo to 9004, even without regarding the effect of the crop rotation system （corn ＆ soybean）. At least 49 % of land cover types were changed into other types in this period. The land cover types, ranking by changing area from high to low series, are rye, soybean, corn, woodland and pasture/CRP. The CCW is divided into 21 subwatersheds, and soil and water loss in each sub-watershed is computed by using Soil and Water Assessment Tool （SWAT）. The results indicate that the variations in runoff and sediment have positive relation to the area of crops （especially corn and soybean）; sediment is more sensitive to land cover changes than runoff; more heavy rainfall does not always mean more runoff because the combination of different land cover types always modify runoff coefficient; and rye, soybean and corn are the key land cover types, which affected the variation in runoff and sediment in the CCW.

Structure, Tree Growth and Dynamics of <I>Cedrus atlantica</I>Manetti Forests in Theniet El Had National Park (N-W Algeria)

In North Africa, Cedrus atlantica forests are in decline, following decades of anthropogenic pressure and repeated drought events. Mixed C. atlantica-Quercus ilex stands located in the Theniet El Had National Park (northwestern Algeria) were considered in the present study. Based on a stratified sampling, six temporary plots were established to describe structure (species composition, density, total height, diameter and basal area) and radial growth in relation to type of stand (pure and mixed), using a dendroecological approach. The diameter distribution of C. atlantica indicated the presence of few young individuals and a poor regeneration status in all the stands. The density and basal area of C. atlantica were significantly higher in pure stands, which necessitate silvicultural operations. In contrast, Q. ilex showed a progressive dynamic, at moderate altitude. Radial growth showed a significant decline from 1980 to the 2000s. The absence of an appropriate management plan and the increase in anthropogenic effects, without ruling out a role for the current climate conditions marked by drought, seem to be the causes of C. atlantica decline.

超级计算机设计的折衷考虑与CEDAR系统

一、引言计算机设计人员常常必须在所期望获得的体系结构特点与实际用来制造一个系统的硬件之间进行折衷。在超级计算机的设计中,由于希望获得高速度,而这样又容易加大成本,因而这些折衷就更加重要了。今天,设计人员在以每秒1亿多次算术运算的峰值速度执行的系统上工作,用户费用高达1千多万美元。需要超级计算机设计人员另外考虑的是,在过去,超级计算机为多数用户提供的性能只是其峰值性能的一小部分(例如5％～10％)。通过大量计算获得高效率是当今超级计算机系统还未达到的一个目标。在八十年代初的五年中,由于种种限制,人们纷纷转向多处理机超级计算机的研制。单处理机超级计算机具有专门的向量指令,它可利用在科学计算中出现的大量向量数据。这些处理机依赖流水算术运算。

Estimation of Carbon Sequestration;Using Allometric Equations;in Azrou Cedar Forests (Cedrus atlantica Manetti) in the Central Middle Atlas of Morocco under Climate Change

The topic of carbon sequestration in forest ecosystems has recently taken a lot of attention due to concerns about global climate change. As a spontaneous species of the Central Middle Atlas, the Atlas Cedar was the subject of our study. Thus, a total of 30 sample trees were subjected to the weight measurements for the estimation of biomass and organic carbon stock in a logging lot in the Azrou forest. The amount of sequestered carbon was then extrapolated in all stand forests studied from the developed carbomass models. The results obtained show that the largest allocation of carbon stock (93%) is in the stem, followed by branches (5%) and foliage (2%). The average carbon storage in this cedar forest is 99.42 tC/ha (aboveground and belowground), or 364.58 t/ha of CO2, a value significantly higher than that found in other Moroccan forest ecosystems.

Microwave Assisted Acid Digestion of Biomorphic Ceramic Obtained from Cedar Wood Infiltrated with ZrO2

This work proposes the use of experimental design for optimization of microwave-assisted digestion of bio- morphic ZrO2-ceramic. Cedar wood is used as template and it was infiltrated with ZrO2 via sol-gel process. XPS, SEM and XRD have been used to verify the effectiveness of the synthesis. The effects of different combination of acids in the digestion of this sample have been optimized taking as response the concentra- tion of several metallic ions measured by ICP-MS.

Study of Atlas Cedar Growth (<i>Cedrus atlantica</i>Manetti) in El M’sid Mountains (East Algeria): Productivity and Growth According to Planting Methods

The Atlas cedar (Cedrus atlantica) is one of the more valuable reforestation species in the Mediterranean areas. But this species suffers from rainfall limitation and climate changes, particularly in its originated area, North Africa. Therefore, any knowledge about the plantation practices to improve the tree water availability and the reforestation success has great importance. The current study has been undertaken in this view, i.e. to compare the growth of cedar plots located in El M’Sid Mountains, Souk Ahras department (700 km east of Algiers), according to different planting methods. The radial growth and the productivity have been measured on a cedar plot with a total surface of 165 ha. 150 ha has been planted in 1970 on hillside ditches, and 15 ha of which the majority is planted in a simple hole and some bouquets on terraces, both are originated from a complementary reforestation achieved during 1980. The results show that most of the trees planted in 1970 reach a height ranging between 10 and 17 m and a diameter between 23 and 44 cm. Even some trees were 20 m high with diameter of 65 cm. The productivity fluctuates between 3 and 8 m3/ha/year, values close to the one of natural native plots. Trees planted in 1980 reach a height ranging between 5. 5 to 7 m, and diameter between 11.5 to 23 cm. The radial growth improves that the hillside ditches help the roots anchoring and trees growth during the first season after plantation. These results indicate that the cedar tree can be used with success in areas outside the natural cedar forest presence, and that appropriate planting techniques can compensate in part the lower rainfall occurring in these chosen regeneration areas.

Spatiotemporal Dynamics of Forest and Mountain Formations in Auras Area, Algeria

Contrary to the countries of northern coast, the forest formations on Southern and East coast of the Mediterranean are in regression. With the combined action of the ax, fire and pasture, these ecosystems are subjected to a pressure of permanent degradation. Indeed, the degradation of the forest ecosystems represents one of the most important causes of reduction and erosion of the biodiversity in the world. The massif of Aur6s is located in the North-East of Algeria. The analysis of the spatiotemporal dynamics of this vulnerable vegetation is not approached yet. This study proposes a focus on the analysis of the dynamics of this vegetation and to study the factors of its degradation. For that, a methodological approach of diachronic follow-up between two dates was adopted by using any kind of old information sources （archives, aerial photographs, topographic maps） and recent （Images satellite of American Landsat and data of land）. The results reveal a degradation of vegetable cover thus expressing a very thorough reduction of the formations forest replaced by herbaceous formations very sensitive and threatened by the overgrazing.