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通过对研究天影广告公司所处的外部环境、公司的内部优劣势等分析,提出有助于公司竞争发展的观点,为公司作竞争战略决策提供有价值的参考意见。 相似文献
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植物种群资源竞争与共存的理论模型研究 总被引：1，自引：0，他引：1
自然生态系统不同植物种群之间存在着广泛的竞争,且多种植物种群可以共存,即具有生物多样性。经典的资源竞争模型(莫诺模型)支持生态学上的"竞争排斥原理",不适用于阐释自然生态系统不同植物种群间的竞争与共存。根据植物生态系统的特点,引入植物种群的生长率随着物种个体大小/个体数增加而逐渐趋于饱和的性质,建立自抑制资源竞争模型。该模型与莫诺模型的本质区别在于,物种的临界可利用资源随种群密度增加而上升,从而可以达到不同物种间的平衡。数学分析及数值模拟结果表明,该模型可允许多物种稳定共存(即共存的物种种类数可以多于供给其生长的资源种类数),同时优势物种随资源供给率增加而依次变化。 相似文献
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认真抓好三支骨干队伍建设加快构筑气象人才资源高地郭敬舒郭军生李栋（山西省气象局０３０００２）当今世界各国的竞争，是以经济和科技实力为基础的综合国力的竞争，焦点是科技和人才的竞争，尤其是领导者、管理者和科技人才的素质和能力的竞争。气象事业发展的实践也充... 相似文献
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1 危机意识 目前面临着国内外气象服务的挑战 ,人才、技术设备还有待提高 ,差距正在拉大。气象信息服务很可能被抢走。只有迎接挑战、开拓创新、与时俱进 ,才是走向气象科技服务未来最好的路子。2 竞争意识 市场经济是竞争经济。要想在竞争中获胜 ,必须具备“人无我有 ,人有我先”的创新与开拓精神 ,即竞争意识。3 质量意识 质量是信息产品的生命。质量好才有竞争力 ,才能出效益。在市场竞争中要坚持质量第一。在气象科技服务活动中 ,首先是气象信息产品的内容要准确 ,服务要及时 ,其次服务的载体制作要精良。4 品牌意识 品… 相似文献
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当今世界的综合国力的竞争,本质上是一场人才竞争;科技的竞争,说到底也是人才竞争。秦大河局长2004年在气象部门全国人才工作会上的讲话指出:“气象事业发展对人才的需求从未像今天这样广泛、多样和迫切。只有汇聚一大批具有高素质、掌握高科技的人才,气象现代化基础设施才能发挥更大效益,提高气象工作的科技水平和拓展气象工作领域才能成为现实,否则‘气象强国’将只是一个美好的梦想而已……”。当前,在全面建设小康社会、构建社会主义和谐社会新的历史时期,经济社会发展、国家安全和可持续发展对气象工作提出的要求从来没有像现在这样高,… 相似文献
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随着科学技术的发展 ,经济全球化的到来 ,人才问题越来越重要。国家之间的竞争主要体现于经济的强弱 ,经济强弱体现于科技的发展 ,科技的发展又体现于人才的竞争 ,而人才竞争的问题就是一个人才资源开发与利用的问题。大到一个国家 ,小到一个部门 ,谁掌握了人才的优势 ,谁就掌握了竞争的主动权。特别是我国加入 WTO后 ,面临新形势、新任务 ,各行各业对人才的需求愈显强烈 ,气象部门更是如此。基本业务发展需要人才 ,事业向五大圈拓展需要人才 ,科技产业生存与发展需要人才 ,目前我们正在下大力气实施人才战略。发达省区在这方面已经积累了… 相似文献
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广西气象台影视广告经营的竞争策略 总被引：2，自引：0，他引：2
通过对研究天影广告公司所处的外部环境、公司的内部优劣势等分析，提出有助于公司竞争发展的观点，为公司作竞争战略决策提供有价值的参考意见。 相似文献
11.
Summary We investigate the consequences of Darwinian selection in a daisymodel with uniform temperature, inter-specific competition and multiple daisies. The assumption of a higher competition between species than within them allows for the coexistence of more than two species in equilibrium. Thus, it is the first time that a high biodiversity with equal environment-altering traits at the same trophic level in a daisymodel is reported under stationary conditions. Adaptation in the biota occurs through mutations, leading to changes in the optimum temperature in order to achieve the maximum growth rate at the individual level. We study the planetary sensitivity (i.e. the variation of the global mean temperature due to a 1% change in solar radiation) as a function of the strength of the inter-specific competition and of the number of different species that grow in the model. We find the following: 1) by fixing the parameter that defines the strength of the inter-specific competition, the planetary sensitivity increases as biodiversity increases; 2) by keeping constant the number of different species in the planet, the planetary sensitivity also increases as competition between species increases. In any case, however, the planetary sensitivity associated with adaptive daisies is much greater than that obtained from non-adaptive species. However, the range of mean solar radiation where biota grows in the planet is substantially larger for adaptive species than for non-adaptive ones. This result suggests that adaptation of multiple species with the same environmental-altering traits may not imply a strong regulation of the mean planetary temperature, which differs with recent studies that analyse adaptation of single species. Similar results are obtained by using a constrained adaptation and non-uniform temperatures. 相似文献
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Greenhouse gas abatement policies will increase the demand for renewable sources of energy, including bioenergy. In combination
with a global growing demand for food, this could lead to a food-fuel competition for bio-productive land. Proponents of bioenergy
have suggested that energy crop plantations may be established on less productive land as a way of avoiding this potential
food-fuel competition. However, many of these suggestions have been made without any underlying economic analysis. In this
paper, we develop a long-term economic optimization model (LUCEA) of the U.S. agricultural and energy system to analyze this
possible competition for land and to examine the link between carbon prices, the energy system dynamics and the effect of
the land competition on food prices. Our results indicate that bioenergy plantations will be competitive on cropland already
at carbon taxes about US $20/ton C. As the carbon tax increases, food prices more than double compared to the reference scenario
in which there is no climate policy. Further, bioenergy plantations appropriate significant areas of both cropland and grazing
land. In model runs where we have limited the amount of grazing land that can be used for bioenergy to what many analysts
consider the upper limit, most of the bioenergy plantations are established on cropland. Under the assumption that more grazing
land can be used, large areas of bioenergy plantations are established on grazing land, despite the fact that yields are assumed
to be much lower (less than half) than on crop land. It should be noted that this allocation on grazing land takes place as
a result of a competition between food and bioenergy production and not because of lack of it. The estimated increase in food
prices is largely unaffected by how much grazing land can be used for bioenergy production. 相似文献
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JOEL E. COHEN ALBERT D. RICH 《Tellus. Series B, Chemical and physical meteorology》2000,52(3):980-984
The model of Daisyworld showed that nonteleological mechanistic responses of life to the physical environment can stabilize an exogenously perturbed environment. In the model, 2 species of daisies, black and white, stabilize the global temperature of a planet exposed to different levels of insolation. In both species, the response of the growth rate to local temperature is identical, but differences in albedo between the 2 species generate differences in local temperatures. The shifting balance between the daisies keeps the global temperature in a range suitable for life. Watson and Lovelock made the stronger claim that "the model always shows greater stability with daisies than it does without them." We examined this claim by introducing an extra source of competition into the equations that describe the interactions between the daisy species. Depending on the parameters of competition, temperatures can vary more widely with increasing insolation in the presence of daisies than without them. It now seems possible, timely and perhaps necessary, to include an accurate representation of interspecific competition when taking account of vegetational influences on climate. 相似文献
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In Dynamic Global Vegetation Models （DGVMs）, the establishment of woody vegetation refers to flowering, fertiliza- tion, seed production, germination, and the growth of tree seedlings. It determines not only the population densities but also other important ecosystem structural variables. In current DGVMs, establishments of woody plant functional types （PFTs） are assumed to be either the same in the same grid cell, or largely stochastic. We investigated the uncertainties in the competition of establishment among coexisting woody PFTs from three aspects： the dependence of PFT establishments on vegetation states; background establishment; and relative establishment potentials of different PFTs. Sensitivity experi- ments showed that the dependence of establishment rate on the fractional coverage of a PFT favored the dominant PFT by increasing its share in establishment. While a small background establishment rate had little impact on equilibrium states of the ecosystem, it did change the timescale required for the establishment of alien species in pre-existing forest due to their disadvantage in seed competition during the early stage of invasion. Meanwhile, establishment purely fiom background （the scheme commonly used in current DGVMs） led to inconsistent behavior in response to the change in PFT specification （e.g., number of PFTs and their specification）. Furthermore, the results also indicated that trade-off between irtdividual growth and reproduction/colonization has significant influences on the competition of establishment. Hence, further development of es- tablishment parameterization in DGVMs is essential in reducing the uncertainties in simulations of both ecosystem structures and successions. 相似文献
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冰雹形成机制的研究并论人工雹胚与自然雹胚的“利益竞争”防雹假说 总被引：37，自引：4，他引：33
在播撒防雹中,如何实现人工雹胚与自然雹胚的增长竞争是决定防雹效果的关键,这实质上也是雹云物理的关键课题。经过对强对流(雹)云的流场特征和相应的过冷水场配置的综合分析和数值模拟研究,发现:(1)由于雹云流场的对流性,其中必然存在着一个主上升气流区和相对于云体的水平风速零的区域,它在垂直剖面上,可呈现出一条零线,可长大成冰雹的水凝物粒子是绕零线循环运行增长的,并逐步进入主上升气流区;(2)在雹云中存在着冰雹“穴道”,它位于主上升气流区边侧及零线下的入流区,其体积约为雹云总体的6％或更小,不论自然雹胚或是人工雹胚,只要进入“穴道”都经历着循环运行增长,其轨迹是相互交叉的,因而可以实现平等“竞争”;(3)“穴道”的存在和位置由流场特征决定,运行轨迹的基本形态也由流场决定,而粒子增长率及运行路径的长短由“穴道”内的过冷水场(过冷度和量)决定。 相似文献
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边界层流场和地形特征对青岛奥帆赛场午后海风影响的研究 总被引：4，自引：1，他引：3
奥帆赛是奥运会唯一以自然风为动力的竞赛项目,而北京奥运会期间的8月,青岛的风速是一年中最小的,因风速过小致使帆船竞赛地法进行的情况时有发生。鉴于青岛的弱风与海陆风的发展状况关系密切,文中分析8、9月青岛奥帆赛和残奥帆赛期间竞赛海域海陆风的发展条件,并用高分辨率数值模式对相关个例进行了模拟试验研究。结果发现,地面背景气流、边界层中上部径向气流和周围地形、海陆分布等边界层特征,都对竞赛海域海陆风的发展产生影响。其中晴天时,地面西风、弱的北风和东风、均压场环境以及边界层中上部弱的北风条件等,都是竞赛海域海风发展的有利条件;而地面南风(无论大小)、强的北风以及边界层中上部较强的南风和很强的北风等,则是海风发展的不利条件。此外,当地面为东北风时,位于竞赛海域上游的崂山对地面风速有阻挡减弱的作用,从而有利于海风的发展;地面为南风时,崂山和浮山等地形强迫气流在竞赛海域附近向左右分为两支,胶州湾和崂山湾侧向海风(东南风)急流发展又加大了这种分流作用,导致竞赛海域常减小为弱风,使比赛无法进行。以上结论在2008年奥帆赛和残奥帆赛气象保障预报服务中得到运用。 相似文献
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Development of the IAP Dynamic Global Vegetation Model 总被引：1，自引：0，他引：1
ABSTRACT The lAP Dynamic Global Vegetation Model （IAP-DGVM） has been developed to simulate the distribution and structure of global vegetation within the framework of Earth System Models. It incorporates our group＇s recent developments of major model components such as the shrub sub-model, establishment and competition parameterization schemes, and a process-based fire parameterization of intermediate complexity. The model has 12 plant functional types, including seven tree, two shrub, and three grass types, plus bare soil. Different PFTs are allowed to coexist within a grid cell, and their state variables are updated by various governing equations describing vegetation processes from fine-scale biogeophysics and biogeochemistry, to individual and population dynamics, to large-scale biogeography. Environmental disturbance due to fire not only affects regional vegetation competition, but also influences atmospheric chemistry and aerosol emissions. Simulations under observed atmospheric conditions showed that the model can correctly reproduce the global distribution of trees, shrubs, grasses, and bare soil. The simulated global dominant vegetation types reproduce the transition from forest to grassland （savanna） in the tropical region, and from forest to shrubland in the boreal region, but overestimate the region of temperate forest. 相似文献
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利用冬奥会气象观测站网资料、ERA5的0.25°×0.25°高分辨率再分析资料、常规探空资料以及激光雷达和风廓线雷达资料,从环流形势、温湿度和微物理特征以及雷达特征等方面对2020年11月17-19日冬奥会张家口赛区一次明显的雨转雪天气过程进行分析。结果表明：低层前期的暖湿西南气流,为降水提供好的水汽和能量条件,后期强的干冷平流为相态转换提供有利条件。赛区出现雨转雪时,700 hPa温度低于-2℃,同时850 hPa温度低于2℃。零度层高度的快速下降是相态转换的重要温度判据,0℃线降到距地面400 m左右赛区降水相态已经转变为纯雪,低层风向的转向对赛场的雨雪相态转换有一定的指示意义。随着高空云冰和雪水含量逐渐增加,其出现最大值后,雨雪相态开始转换。降雪时激光雷达最大探测高度比降雨时有明显的降低,风廓线雷达低层风场的变化和雨雪相态关系密切,风廓线雷达探测的垂直速度变化也能反映雨雪相态的转换。 相似文献
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京津冀地区经济和文化的快速发展对冬季地面瞬时强风预报要求越来越高。正确估计和预测冬季地面瞬时强风,尤其是复杂地形条件下的阵风高分辨率格点精准预报,对于提升重大活动服务保障、首都及周边地区城市安全运行及防灾减灾能力等方面都具有重要意义。本研究基于京津冀长时间序列的实况观测资料,建立了阵风系数与稳定风速、风向、地形高度各要素之间的关系模型,并结合客观统计分析方法、阵风观测数据融合技术、格点偏差订正技术,发展了一种既保留模式物理参数特征和阵风局地气候特征,又发挥格点偏差订正技术的阵风客观预报方法。冬季奥林匹克赛事期间批量检验和个例分析结果表明,基于阵风系数格点模型和模式后处理订正技术得到的百米级分辨率、分钟级更新的阵风客观预报产品,24 h预报时效内张家口赛区和延庆赛区考核站平均绝对误差分别在2.3 m/s和3.0 m/s以下,延庆赛区8级以上大风,阵风风速预报评分超过0.5,解决了复杂山区数值模式阵风预报误差大、几乎无法业务应用的瓶颈问题,满足冬季奥林匹克运动会现场服务要求。 相似文献
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《Climate Policy》2013,13(5):467-493
An oligopoly competition model is described and used to illustrate the potential effect of EU emissions trading and transport issues on the production decisions and profitability of cement producers in a typical western European country market. The role of geography is introduced from three viewpoints: the existence of regional markets, the fact that EU producers may operate multiple plants across these regions, and the possibility of production capacity constraints. A typical EU state is divided into a coastal region which is initially exposed to international competition, and an inland region which is initially protected. Assuming pure auctioning of EU Allowances and a range of CO2 prices up to €50/t, our model predicts a large increase of imports into the coastal region. Consequences for the inland producers include reduced attractiveness of the coastal market, as well as increased competition from coastal producers and from non-EU imports. The model includes a number of simplifications and therefore does not claim to offer definitive predictions, but our results do suggest that an increase in non-EU imports could feasibly offset more than 70% of the decrease in EU cement sector emissions. The likely impact on producer profits is considered for each region, and the advantages and disadvantages of potential mitigating policy measures are reviewed for either the EU Allowance allocation process or border adjustments on cement products. 相似文献