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1.
Cloud computing technology plays a very important role in many areas, such as in the construction and development of the smart city. Meanwhile, numerous cloud services appear on the cloud-based platform. Therefore how to how to select trustworthy cloud services remains a significant problem in such platforms, and extensively investigated owing to the ever-growing needs of users. However, trust relationship in social network has not been taken into account in existing methods of cloud service selection and recommendation. In this paper, we propose a cloud service selection model based on the trust-enhanced similarity. Firstly, the direct, indirect, and hybrid trust degrees are measured based on the interaction frequencies among users. Secondly, we estimate the overall similarity by combining the experience usability measured based on Jaccard’s Coefficient and the numerical distance computed by Pearson Correlation Coefficient. Then through using the trust degree to modify the basic similarity, we obtain a trust-enhanced similarity. Finally, we utilize the trust-enhanced similarity to find similar trusted neighbors and predict the missing QoS values as the basis of cloud service selection and recommendation. The experimental results show that our approach is able to obtain optimal results via adjusting parameters and exhibits high effectiveness. The cloud services ranking by our model also have better QoS properties than other methods in the comparison experiments. 相似文献
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长白猪综合选择指数及其通径分析化研究 总被引:1,自引:1,他引:1
选取长白猪109头后备猪,育肥猪64头为试验材料;由此制订了综合选择指 数.经过通径分析化研究发现体高为正向选择性状,管围和膘厚为负向选择性状,决定系 数为 60.7%,中选符合率为 87.5%. 相似文献
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《Journal of Industrial Ecology》2005,9(1-2):187-200
China's development over the last few decades has been characterized by high rates of economic growth, large-scale migration from rural areas to the fast-growing cities accompanied by changes in lifestyles, and steady population growth. These developments have left deep marks on resource availability and quality. In this article we conduct a scenario analysis of how lifestyle changes and other major developments might affect water resources.
China has the longest tradition in river and water resource management in the world. Its civilization has sought to control the effects of floods and drought for thousands of years and has utilized water flows for irrigation and navigation. In the last century, competing uses such as domestic, municipal, and industrial water consumption have also become reasons for the regulation of and large-scale abstraction of water.
To investigate the major changes in economy and society and their effects on the water situation in China, a set of scenarios is developed and analyzed within a structural economics framework. A hydrological model that represents water flows in the major watersheds is linked to a regional input-output model that represents socioeconomic activities in the major economic-administrative regions of China. The regional analysis shows that the North and Northwest regions are water-scarce and that lifestyle changes and technical shifts are the most important factors driving future water consumption. 相似文献
China has the longest tradition in river and water resource management in the world. Its civilization has sought to control the effects of floods and drought for thousands of years and has utilized water flows for irrigation and navigation. In the last century, competing uses such as domestic, municipal, and industrial water consumption have also become reasons for the regulation of and large-scale abstraction of water.
To investigate the major changes in economy and society and their effects on the water situation in China, a set of scenarios is developed and analyzed within a structural economics framework. A hydrological model that represents water flows in the major watersheds is linked to a regional input-output model that represents socioeconomic activities in the major economic-administrative regions of China. The regional analysis shows that the North and Northwest regions are water-scarce and that lifestyle changes and technical shifts are the most important factors driving future water consumption. 相似文献
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A Novel Method for Optimum Global Positioning System Satellite Selection Based on a Modified Genetic Algorithm 总被引:1,自引:0,他引:1
In this paper, a novel method for selecting a navigation satellite subset for a global positioning system (GPS) based on a genetic algorithm is presented. This approach is based on minimizing the factors in the geometric dilution of precision (GDOP) using a modified genetic algorithm (MGA) with an elite conservation strategy, adaptive selection, adaptive mutation, and a hybrid genetic algorithm that can select a subset of the satellites represented by specific numbers in the interval (4 ∼ n) while maintaining position accuracy. A comprehensive simulation demonstrates that the MGA-based satellite selection method effectively selects the correct number of optimal satellite subsets using receiver autonomous integrity monitoring (RAIM) or fault detection and exclusion (FDE). This method is more adaptable and flexible for GPS receivers, particularly for those used in handset equipment and mobile phones. 相似文献
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Mathukumalli Srinivasa Rao Pettem Swathi Chitiprolu Anantha Rama Rao K. V. Rao B. M. K. Raju Karlapudi Srinivas Dammu Manimanjari Mandapaka Maheswari 《PloS one》2015,10(2)
The present study features the estimation of number of generations of tobacco caterpillar, Spodoptera litura. Fab. on peanut crop at six locations in India using MarkSim, which provides General Circulation Model (GCM) of future data on daily maximum (T.max), minimum (T.min) air temperatures from six models viz., BCCR-BCM2.0, CNRM-CM3, CSIRO-Mk3.5, ECHams5, INCM-CM3.0 and MIROC3.2 along with an ensemble of the six from three emission scenarios (A2, A1B and B1). This data was used to predict the future pest scenarios following the growing degree days approach in four different climate periods viz., Baseline-1975, Near future (NF) -2020, Distant future (DF)-2050 and Very Distant future (VDF)—2080. It is predicted that more generations would occur during the three future climate periods with significant variation among scenarios and models. Among the seven models, 1–2 additional generations were predicted during DF and VDF due to higher future temperatures in CNRM-CM3, ECHams5 & CSIRO-Mk3.5 models. The temperature projections of these models indicated that the generation time would decrease by 18–22% over baseline. Analysis of variance (ANOVA) was used to partition the variation in the predicted number of generations and generation time of S. litura on peanut during crop season. Geographical location explained 34% of the total variation in number of generations, followed by time period (26%), model (1.74%) and scenario (0.74%). The remaining 14% of the variation was explained by interactions. Increased number of generations and reduction of generation time across the six peanut growing locations of India suggest that the incidence of S. litura may increase due to projected increase in temperatures in future climate change periods. 相似文献
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Model-free Analysis of Protein Dynamics: Assessment of Accuracy and Model Selection Protocols Based on Molecular Dynamics Simulation 总被引:2,自引:3,他引:2
The popular model-free approach to analyze NMR relaxation measurements has been examined using artificial amide (15)N relaxation data sets generated from a 10 nanosecond molecular dynamics trajectory of a dihydrofolate reductase ternary complex in explicit water. With access to a detailed picture of the underlying internal motions, the efficacy of model-free analysis and impact of model selection protocols on the interpretation of NMR data can be studied. In the limit of uncorrelated global tumbling and internal motions, fitting the relaxation data to the model-free models can recover a significant amount of quantitative information on the internal dynamics. Despite a slight overestimation, the generalized order parameter is quite accurately determined. However, the model-free analysis appears to be insensitive to the presence of nanosecond time scale motions with relatively small magnitude. For such cases, the effective correlation time can be significantly underestimated. As a result, proteins appear to be more rigid than they really are. The model selection protocols have a major impact on the information one can reliably obtain. The commonly employed protocol based on step-up hypothesis testing has severe drawbacks of oversimplification and underfitting. The consequences are that the order parameter is more severely overestimated and the correlation time more severely underestimated. Instead, model selection based on Bayesian Information Criteria (BIC), recently introduced to the model-free analysis by d'Auvergne and Gooley (2003), provides a better balance between bias and variance. More appropriate models can be selected, leading to improved estimate of both the order parameter and correlation time. In addition, the computational cost is significantly reduced and subjective parameters such as the significance level are unnecessary. 相似文献
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Effect of Model Sorptive Phases on Phenanthrene Biodegradation: Molecular Analysis of Enrichments and Isolates Suggests Selection Based on Bioavailability 总被引:2,自引:6,他引:2
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M. Friedrich R. J. Grosser E. A. Kern W. P. Inskeep D. M. Ward 《Applied microbiology》2000,66(7):2703-2710
Reduced bioavailability of nonpolar contaminants due to sorption to natural organic matter is an important factor controlling biodegradation of pollutants in the environment. We established enrichment cultures in which solid organic phases were used to reduce phenanthrene bioavailability to different degrees (R. J. Grosser, M. Friedrich, D. M. Ward, and W. P. Inskeep, Appl. Environ. Microbiol. 66:2695–2702, 2000). Bacteria enriched and isolated from contaminated soils under these conditions were analyzed by denaturing gradient gel electrophoresis (DGGE) and sequencing of PCR-amplified 16S ribosomal DNA segments. Compared to DGGE patterns obtained with enrichment cultures containing sand or no sorptive solid phase, different DGGE patterns were obtained with enrichment cultures containing phenanthrene sorbed to beads of Amberlite IRC-50 (AMB), a weak cation-exchange resin, and especially Biobead SM7 (SM7), a polyacrylic resin that sorbed phenanthrene more strongly. SM7 enrichments selected for mycobacterial phenanthrene mineralizers, whereas AMB enrichments selected for a Burkholderia sp. that degrades phenanthrene. Identical mycobacterial and Burkholderia 16S rRNA sequence segments were found in SM7 and AMB enrichment cultures inoculated with contaminated soil from two geographically distant sites. Other closely related Burkholderia sp. populations, some of which utilized phenanthrene, were detected in sand and control enrichment cultures. Our results are consistent with the hypothesis that different phenanthrene-utilizing bacteria inhabiting the same soils may be adapted to different phenanthrene bioavailabilities. 相似文献
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We compare spot patterns generated by Turing mechanisms with those generated by replication cascades, in a model one-dimensional reaction-diffusion system. We determine the stability region of spot solutions in parameter space as a function of a natural control parameter (feed-rate) where degenerate patterns with different numbers of spots coexist for a fixed feed-rate. While it is possible to generate identical patterns via both mechanisms, we show that replication cascades lead to a wider choice of pattern profiles that can be selected through a tuning of the feed-rate, exploiting hysteresis and directionality effects of the different pattern pathways. 相似文献
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Environmentally extended input-output analysis (EEIOA) has long been used to quantify global and regional environmental impacts and to clarify emission transfers. Structural path analysis (SPA), a technique based on EEIOA, is especially useful for measuring significant flows in this environmental-economic system. This paper constructs an imports-adjusted single-region input-output (SRIO) model considering only domestic final use elements, and it uses the SPA technique to highlight crucial routes along the production chain in both final use and sectoral perspectives. The results indicate that future mitigation policies on household consumption should change direct energy use structures in rural areas, cut unreasonable demand for power and chemical products, and focus on urban areas due to their consistently higher magnitudes than rural areas in the structural routes. Impacts originating from government spending should be tackled by managing onsite energy use in 3 major service sectors and promoting cleaner fuels and energy-saving techniques in the transport sector. Policies on investment should concentrate on sectoral interrelationships along the production chain by setting up standards to regulate upstream industries, especially for the services, construction and equipment manufacturing sectors, which have high demand pulling effects. Apart from the similar methods above, mitigating policies in exports should also consider improving embodied technology and quality in manufactured products to achieve sustainable development. Additionally, detailed sectoral results in the coal extraction industry highlight the onsite energy use management in large domestic companies, emphasize energy structure rearrangement, and indicate resources and energy safety issues. Conclusions based on the construction and public administration sectors reveal that future mitigation in secondary and tertiary industries should be combined with upstream emission intensive industries in a systematic viewpoint to achieve sustainable development. Overall, SPA is a useful tool in empirical studies, and it can be used to analyze national environmental impacts and guide future mitigation policies. 相似文献
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建立了描述温控加热方式下激光诱导肿瘤间质热疗过程中动态光热作用的二维圆柱坐标下的数学模型,采用基于网格的蒙特卡罗方法数值模拟热疗过程中激光能量在非均质生物组织内的传输过程,基于Pennes生物传热方程和Arrhen ius方程数值求解组织内的温度场和热损伤体积的变化。通过数值模拟的方法分析了激光波长、激光功率、温控范围等因素对激光诱导肿瘤间质热疗中热损伤体积的影响。数值模拟的结果表明,通过选择合适的治疗参数,可以得到各种不同大小的热疗区域。本文的结果和结论对于临床治疗方案的制定具有一定的理论指导意义。 相似文献
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When large carnivores occupy peripheral human lands conflict with humans becomes inevitable, and the reduction of human-carnivore interactions must be the first consideration for those concerned with conflict mitigation. Studies designed to identify areas of high human-bear interaction are crucial for prioritizing management actions. Due to a surge in conflicts, against a background of social intolerance to wildlife and the prevalent use of lethal control throughout Japan, Asiatic black bears (Ursus thibetanus) are now threatened by high rates of mortality. There is an urgent need to reduce the frequency of human-bear encounters if bear populations are to be conserved. To this end, we estimated the habitats that relate to human-bear interactions by sex and season using resource selection functions (RSF). Significant seasonal differences in selection for and avoidance of areas by bears were estimated by distance-effect models with interaction terms of land cover and sex. Human-bear boundaries were delineated on the basis of defined bear-habitat edges in order to identify areas that are in most need of proactive management strategies. Asiatic black bears selected habitats in close proximity to forest edges, forest roads, rivers, and red pine and riparian forests during the peak conflict season and this was correctly predicted in our human-bear boundary maps. Our findings demonstrated that bears selected abandoned forests and agricultural lands, indicating that it should be possible to reduce animal use near human lands by restoring season-specific habitat in relatively remote areas. Habitat-based conflict mitigation may therefore provide a practical means of creating adequate separation between humans and these large carnivores. 相似文献
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确定污染物达标排放阈值是环境污染综合防治的一项重要内容,其前提是对系统现状进行准确的综合评价.基于修正灰色聚类模型的综合评价法,既考虑了指标体系本身内在的权重又考虑了实际权重,而且在确定实际权重的时候,通过引进指数型白化函数,使得实际监测数据与各级非零权重之间存在一一对应关系,有效解决了经典聚类模型的零权重问题.在综合评价的基础上,根据建模原理可进一步计算出各污染物的达标排放阈值.实例分析了2003年杭州经济技术开发区环境空气质量综合等级为Ⅲ级,若综合等级要达到Ⅱ级标准,其首要污染物PM_(10)浓度的达标排放闽值为0.07298mg/m~3,即削减率至少为47.87%才能保证该区环境空气质量达标. 相似文献
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A model of density-dependent selection in a Mendelian single-locus population was analyzed in the case where the fitnesses of genotypic forms are exponential functions of the population size. Analytical and numerical studies of the model were performed for a diallelic locus, and parametric regions were established for different dynamic behaviors of the model. The diallelic model of density-dependent selection was generalized to a multiallelic locus; the results of its analysis are described. 相似文献
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Kuang-Ho Chen 《Biometrical journal. Biometrische Zeitschrift》1979,21(8):773-779
An iteration relation is given for the moments of the surviving individuals after probit directional selection if the individuals before selection are normally distributed. The proportion, mean, variance, skewness, and kurtosis are expressed in closed form. 相似文献
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By reason nonlinear relations founded between selection differential and realised selection response we have been made investigations about variants of the genetic-statistical model, which include this nonlinearity. The variations of the model would not only referred to the postulate pattern of the connection between phenotype, genotype and environment but also enclosed the postulate assumption about the distribution of the variates. In an investigated special case the linear model equation P = G ± e was held, however the distributions of P and G were defined over a limited range in one direction. For P we have defined a modified normal distribution and the distribution of the random vector (G, e) non normal regarded with cov (G, e) ≠ 0, By means of a solution set of an integral equation a density function of the random vector (P, G) has been received, in which the expectation of the selection response of the usual genetic-statistical model approximate is included as a special case. The genetical parameters has been derived, which result from changed model. However their representation was only possible partially as an integral function. A subsequent paper informs of the examination this mode! variants, which depend on a parameter of the nonlinearity c. 相似文献
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Fang Ye Deng Ao Yao Feng Lin Wang Jie Chen Dale Huntington Haijun Wang Yan Wang Economic Impact of Maternal Deaths in China 《PloS one》2015,10(8)
Objectives
The present study aimed to explore the inter-relationships among maternal death, household economic status after the event, and potential influencing factors.Methods
We conducted a prospective cohort study of households that had experienced maternal death (n = 195) and those that experienced childbirth without maternal death (n = 384) in rural China. All the households were interviewed after the event occurred and were followed up 12 months later. Structural equation modeling was used to test the relationship model, utilizing income and expenditure per capita in the following year after the event as the main outcome variables, maternal death as the predictor, and direct costs, the amount of money offset by positive and negative coping strategies, whether the husband remarried, and whether the newborn was alive as the mediators.Results
In the following year after the event, the path analysis revealed a direct effect from maternal death to lower income per capita (standardized coefficient = -0.43, p = 0.041) and to lower expenditure per capita (standardized coefficient = -0.51, p<0.001). A significant indirect effect was found from maternal death to lower income and expenditure per capita mediated by the influencing factors of higher direct costs, less money from positive coping methods, more money from negative coping, and the survival of the newborn.Conclusion
This study analyzed the direct and indirect effects of maternal death on a household economy. The results provided evidence for better understanding the mechanism of how this event affects a household economy and provided a reference for social welfare policies to target the most vulnerable households that have suffered from maternal deaths. 相似文献19.
Adam M. Sullivan Xiaopeng Zhao Yasuhiro Suzuki Eri Ochiai Stephen Crutcher Michael A. Gilchrist 《PLoS computational biology》2013,9(11)
Toxoplasma gondii establishes a chronic infection by forming cysts preferentially in the brain. This chronic infection is one of the most common parasitic infections in humans and can be reactivated to develop life-threatening toxoplasmic encephalitis in immunocompromised patients. Host-pathogen interactions during the chronic infection include growth of the cysts and their removal by both natural rupture and elimination by the immune system. Analyzing these interactions is important for understanding the pathogenesis of this common infection. We developed a differential equation framework of cyst growth and employed Akaike Information Criteria (AIC) to determine the growth and removal functions that best describe the distribution of cyst sizes measured from the brains of chronically infected mice. The AIC strongly support models in which T. gondii cysts grow at a constant rate such that the per capita growth rate of the parasite is inversely proportional to the number of parasites within a cyst, suggesting finely-regulated asynchronous replication of the parasites. Our analyses were also able to reject the models where cyst removal rate increases linearly or quadratically in association with increase in cyst size. The modeling and analysis framework may provide a useful tool for understanding the pathogenesis of infections with other cyst producing parasites. 相似文献
20.
Background Tools and methods able to cope with uncertainties are essential for improving the credibility of Life Cycle Assessment (LCA)
as a decision support tool. Previous approaches have focussed predominately upon data quality.
Objective and Scope. An epistemological approach is presented conceptualising uncertainties in a comparative, prospective, attributional
LCA. This is achieved by considering a set of cornerstone scenarios representing future developments of an entire Life Cycle
Inventory (LCI) product system. We illustrate the method using a comparison of future transport systems.
Method Scenario modelling is organized by means of Formative Scenario Analysis (FSA), which provides a set of possible and consistent
scenarios of those unit processes of an LCI product system which are time dependent and of environmental importance. Scenarios
are combinations of levels of socio-economic or technological impact variables. Two core elements of FSA are applied in LCI
scenario modelling. So-called impact matrix analysis is applied to determine the relationship between unit process specific
socio-economic variables and technology variables. Consistency Analysis is employed to integrate unit process scenarios, based
on pair-wise ratings of the consistency of the levels of socio-economic impact variables of all unit processes. Two software
applications are employed which are available from the authors.
Results and Discussion The study reveals that each possible level or development of a technology variable is best conceived of as the impact of
a specific socio-economic (sub-) scenario. This allows for linking possible future technology options within the socio-economic
context of the future development of various background processes. In an illustrative case study, the climate change scores
and nitrogen dioxide scores per seat kilometre for six technology options of regional rail transport are compared. Similar
scores are calculated for a future bus alternative and an average Swiss car.
The scenarios are deliberately chosen to maximise diversity. That is, they represent the entire range of future possible developments.
Reference data and the unit process structure are taken from the Swiss LCA database 'ecoinvent 2000'. The results reveal that
rail transport remains the best option for future regional transport in Switzerland. In all four assessed scenarios, four
technology options of future rail transport perform considerably better than regional bus transport and car transport.
Conclusions and Recommendations. The case study demonstrates the general feasibility of the developed approach for attributional prospective
LCA. It allows for a focussed and in-depth analysis of the future development of each single unit process, while still accounting
for the requirements of the final scenario integration. Due to its high transparency, the procedure supports the validation
of LCI results. Furthermore, it is well-suited for incorporation into participatory methods so as to increase their credibility.
Outlook and Future Work. Thus far, the proposed approach is only applied on a vehicle level not taking into account alterations in
demand and use of different transport modes. Future projects will enhance the approach by tackling uncertainties in technology
assessment of future transport systems. For instance, environmental interventions involving future maglev technology will
be assessed so as to account for induced traffic generated by the introduction of a new transport system. 相似文献