小型拖拉机常见故障智能专家系统的应用   总被引：1，自引：0，他引：1  

周桂霞  张吉军 《中国农机化》2005,(2):57-59

根据小型拖拉机的常见故障．应用人工智能专家系统原理和面向对象的设计方法，建立了知识库和相应知识表达推理机制，利用Visual Basic6．0编程工具，设计并组建了小型拖拉机常见故障诊断专家系统，缓解了故障诊断专家供不应求的矛盾，提高了小型拖拉机的常见故障诊断的效率和准确率。  相似文献   

Are urban forests ecological traps for understory birds? An examination using Northern cardinals     

Lionel F.V. Leston 《Biological conservation》2006,131(4):566-574

Many studies have reported increased numbers of certain synanthropic species in urbanizing landscapes, but few have evaluated if urban habitats constitute ecological traps for these species. The Northern cardinal (Cardinalis cardinalis) was used as a model species to evaluate if urban riparian forests might act as ecological traps for understory-nesting birds. Cardinals were surveyed within 2-ha riparian forest plots within rural (n = 6) and urban (n = 6) landscapes in Ohio USA during breeding and non-breeding seasons 2003-2005. Cues used by cardinals to select habitats were identified based on measurements surrounding 219 nests and in 106 randomly-located plots and 96 systematically-located plots. Productivity of 161 cardinal pairs and survival of 180 adults were monitored from late March-September, 2003-2005. Cardinals were 1.7× (in the breeding season) to nearly 4× (in non-breeding season) more abundant in urban than rural forests, and the results suggest that these differences in abundance stemmed from urban-associated changes in habitat and microclimate features used by cardinals to select habitats. Most notably, cardinals were strongly associated with dense understory vegetation and warmer minimum January temperatures, both of which were promoted as urban development increased within the landscapes surrounding riparian forests. Although other studies suggest mismatches between the habitat cues used by cardinals and how those features affect nesting success (e.g., higher nest predation in exotic shrubs), these results provide no evidence that urban forests were acting as ecological traps for cardinals. Instead, cardinals in urban and rural forests had similar numbers of nesting attempts, young fledged over the breeding season, and apparent annual survival rates. Thus, these findings do not support for the idea that urban forests in central Ohio represent ecological traps for synanthropic understory birds.  相似文献   

The relevance of data on genetic diversity for the conservation of Afro-montane regions     

Charles Kahindo  John M. Bates 《Biological conservation》2007,134(2):262-270

Molecular data are shedding new light on our understanding of genetic diversity and biological diversity in general. We examine results of recent genetic studies on African birds that document endemic diversity in small, isolated montane forests of Africa. These studies show that levels of genetic differentiation in these isolated montane regions are substantial and indicate little or no gene flow with their closest populations. Although this pattern of locally distributed montane taxa is not something that has gone unnoticed by traditional taxonomists, we argue that many of the small, often outlying areas run the risk of being devalued in conservation planning because these areas generally have comparatively low levels of overall diversity and endemism (especially at the species level). We strongly suspect that other organisms will possess similar patterns of differentiation in Afro-montane regions of Africa and we argue that this information can be effectively brought to bear to highlight the conservation significance of these smaller areas.  相似文献   

Evaluation of the extinction risk and of conservation alternatives for a very small insular population: the bearded vulture Gypaetus barbatus in Corsica     

Vincent Bretagnolle  Pablo Inchausti  Jean-François Seguin 《Biological conservation》2004,120(1):19-30

The bearded vulture Gypaetus barbatus is a large, long-lived osteophagus vulture whose abundance and breeding range have drastically declined during the last century, making it one of the most endangered European bird species. We evaluated the extinction risk of the bearded vulture population in Corsica (a small, isolated breeding population of 8-10 pairs), one of the last extant populations in Western Europe, and estimated its probability of extinction to be 0.165 over the next 50 years. A sensitivity analysis to assess the influence of uncertain demographic rates showed that it is critical to estimate precisely the values of pre-adult survival. Neither the type nor the parameters of density dependence acting on fecundity and survival rates influenced much the extinction risk of the Corsican population. We evaluated the effect of four realistic conservation actions that could be implemented on the Corsican bearded vulture population and rank them in terms of their respective decrease of the current extinction risk faced by this population. We found that the release of two juveniles every other year for 12 years and the increase of fecundity due to selective food provisioning would reduce by more than one-half the current extinction risk of Corsican bearded vulture population. In contrast, even substantial increases in the carrying capacity through large supplemental feeding produced very modest decreases in the extinction risk, thus calling into question the efficacy of one of the main pan-European conservation strategies for this species. Re-establishing a population network within the Mediterranean could be a potentially better strategy, though its efficacy depends on natal dispersal among populations that is currently unknown.  相似文献   

Conservation in the face of climate change: The roles of alternative models, monitoring, and adaptation in confronting and reducing uncertainty   总被引：2，自引：0，他引：2  

Michael J. Conroy  Michael C. Runge  James D. Nichols  Kirk W. Stodola  Robert J. Cooper 《Biological conservation》2011,(4):1204-1213

The broad physical and biological principles behind climate change and its potential large scale ecological impacts on biota are fairly well understood, although likely responses of biotic communities at fine spatio-temporal scales are not, limiting the ability of conservation programs to respond effectively to climate change outside the range of human experience. Much of the climate debate has focused on attempts to resolve key uncertainties in a hypothesis-testing framework. However, conservation decisions cannot await resolution of these scientific issues and instead must proceed in the face of uncertainty. We suggest that conservation should precede in an adaptive management framework, in which decisions are guided by predictions under multiple, plausible hypotheses about climate impacts. Under this plan, monitoring is used to evaluate the response of the system to climate drivers, and management actions (perhaps experimental) are used to confront testable predictions with data, in turn providing feedback for future decision making. We illustrate these principles with the problem of mitigating the effects of climate change on terrestrial bird communities in the southern Appalachian Mountains, USA.  相似文献   

Dampened behavioral and physiological responses mediate birds’ association with humans     

Gerardo Jiménez  Jesús A. Lemus  Leandro Meléndez  Guillermo Blanco  Paola Laiolo 《Biological conservation》2011,(5):1702-1711

The study of the mechanisms involved in phenotypic adaptations or plasticity to environmental stressors may serve to evaluate contemporary ecological and evolutionary dynamics in threatened or growing wildlife populations. By addressing human disturbance as a main stressor agent, we investigated antipredator response (flushing distance), social behavior (degree of gregarism), health (fecal pathogens), and endocrine status (fecal corticosterone levels) as potential mechanisms that permit birds to cope with anthropogenic impact in tourist areas. Our study models were species that are neither urbanized nor invasive, and that are typical of the high mountains of the Palearctic: the Alpine and the Red-billed chough (Pyrrhocorax graculus and P. pyrrhocorax), and the surrounding alpine bird community. Both chough species showed habituation, reduced flushing distances, fewer parasites and lower corticosterone levels in tourist than in non-tourist sites, and a significant variation in gregarious behavior. Behavioral and physiological adjustments permitted these corvids to optimize resource exploitation depending on habitat quality and in conditions of continuous disturbance. Human-induced changes in chough social behavior had no effect on local avian species richness, a surrogate measure for community diversity. Irrespectively of chough aggregations, bird diversity decreased significantly in recreational areas, thus not all community members tolerated human impact as choughs did. Our findings suggest that species that manage to coexist with humans primarily adjust traits that influence ecological interactions (social, foraging or antipredatory responses) and that vary rapidly (learned behaviors and physiological mechanisms that promote homeostasis).  相似文献   

黑龙江大沾河湿地国家级自然保护区鸟类多样性及其保护   总被引：1，自引：0，他引：1  

周绍春  刘浩  古彦昌 《野生动物》2011,32(2):83-86,110

为了掌握黑龙江大沾河湿地国家级自然保护区的鸟类多样性和认识保护区目前存在的问题,我们通过查阅资料、鸟类环志和鸟类救护的方法对保护区的鸟类多样性进行了研究。结果表明黑龙江大沾河湿地国家级自然保护区分布有鸟类202种,国家Ⅰ级重点保护鸟类有东方白鹳、白头鹤、丹顶鹤、金雕4种,国家Ⅱ级重点保护鸟类有白枕鹤、苍鹰、鸳鸯等33种,鸟类多样性极其丰富。在鸟类保护工作方面,目前虽然保护区已经开展了大量的保护工作,但仍然存在经济发展与鸟类保护相矛盾、人为干扰严重、自然资源利用过度和环境污染加剧等问题。针对存在的问题,本文通过研究提出了保护区在今后鸟类多样性保护和管理方面的科学意见。  相似文献   

The conservation value of urban riparian areas for landbirds during spring migration: Land cover, scale, and vegetation effects     

Derric N. Pennington  James Hansel 《Biological conservation》2008,141(5):1235-1248

Urbanization changes bird community structure during the breeding season but little is known about its effects on migrating birds. We examined patterns of habitat use by birds at the local and landscape level during 2002 spring migration at 71 riparian plots along an urban gradient in Cincinnati, Ohio, USA. Using linear regression, we examined variation in relative density, species richness, and evenness of four migratory guilds associated with natural land covers and building area at four scales (50, 100, 250, 500 m radial buffers). We also examined the influence of local vegetation using multiple regression models. As building area increased, riparian forests tended to be narrower and have fewer native trees and shrubs. In general, native birds were positively associated with tree cover (within 250-500 m of stream) and native vegetation, and negatively with building area (within 250 m); exotic species responded inversely to these measures. Short-distance migrants and permanent residents displayed the weakest responses to landscape and vegetation measures. Neotropical migrants responded strongest to landscape and vegetation measures and were positively correlated with areas of wide riparian forests and less development (>250 m). Resident Neotropical migrants increased with wider riparian forests (>500 m) without buildings, while en-route migrants utilized areas having a wide buffer of tree cover (250-500 m) regardless of buildings; both were positively associated with native vegetation composition and mature trees. Consequently, developed areas incorporating high native tree cover are important for conserving Neotropical migrants during stopover.  相似文献   

基于OBD-Ⅱ系统检测信息故障分析诊断方法的应用     

金洪卫 《农业装备与车辆工程》2006,(7):40-42

通过对第二代车载诊断系统——OBD—Ⅱ系统的特点、监测机制的分析,论述了应用OBD-Ⅱ系统监测信息进行故障诊断的方法,并列举了运用此方法解决实车故障的诊断。  相似文献   

Predicting short-term extinction risk for the declining Little Bustard (Tetrax tetrax) in intensive agricultural habitats     

Pablo Inchausti  Vincent Bretagnolle 《Biological conservation》2005,122(3):375-384

Populations of Little Bustard (Tetrax tetrax) have shown pronounced declines in European farmland landscapes over the last 25 years due to the intensification of agricultural practices. In France, the number of breeding males in agricultural habitats has declined by 92% since 1980 as a result of decreases in insect abundance and nest destruction during harvesting. We formulate an age- and sex-structured stochastic model for the remaining Little Bustard population in SW France that has been studied since 1997 and, using actual values of demographic rates, we estimate its extinction risk over a time period of 30 years to be of 0.45. At the level of local populations, the extinction risk ranged between 0.66 and 0.90, largely depending on the initial population size and local fecundity of each population. A comprehensive sensitivity analysis evaluated the influence of uncertain demographic rates and of aspects of the spatial dynamics (sex and age dispersing individuals, sex-biased dispersal and different dispersal rates) on the predicted extinction risks and showed that our model was robust to changes of a wide range of combinations assessed. Given the severity of the current decline, and the spatial issues raised by our analysis, implications of our findings for the conservation of this endangered species are suggested.  相似文献