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61.
62.
董玉 《农业机械化与电气化》2009,(1):39-40
介绍并对比了基于神经网络和模糊控制的瞬态空燃比控制方法,二者均不要求控制对象为非常精确的模型。特别在应用的非线性理论建模还不十分完善的情况下。神经网络控制器和模糊控制器的这个优点更为突出。 相似文献
63.
基于MCR-ANN-CA模型的包头市生态用地演变模拟 总被引:1,自引:0,他引:1
以内蒙古自治区包头市为研究区,耦合最小累积阻力(MCR)模型、人工神经网络(ANN)和元胞自动机(CA)构建MCR-ANN-CA模型。利用MCR模型量化包头市各用地类型演变为生态用地时的阻力,构建CA适宜性规则;利用ANN模型提取CA邻域转换规则,基于包头市2006、2011年土地利用数据及归一化植被指数(NDVI)、高程、坡度、水体距离、人口密度多项数据,对2016年生态用地演变情景进行模拟,以2016年实际生态用地分布为参照,将该模型模拟结果与CA-Markov模型的模拟结果进行对比(以2016年实际景观分布为参照),结果显示,两种模型模拟结果的卡帕一致性指数(Kappa index of agreement,KIA)分别为0. 89和0. 87,相对误差分别为3. 10%和5. 31%,MCR-ANN-CA模型显示了较高的模拟精度。 相似文献
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65.
Sawomir Krejszeff Dariusz Kucharczyk Krzysztof Kupren Katarzyna Targoska rzej Mamcarz Roman Kujawa Zbigniew Kaczkowski & Sebastian Ratajski 《Aquaculture Research》2008,39(9):907-912
Research into artificial reproduction of chub was studied during three subsequent reproductive seasons. Chub reproduction was conducted in two different variations. In the first experiment different hormonal agents were given to fish, such as CPE, hCG, or an analogue of GnRH with dopamine antagonist (ovopel). In the second one, the optimum moment of applying of artificial reproduction was sought and the fish were only obtained an analogue of GnRH in different periods. The results obtained in two first seasons indicated that ovopel is the most effective agent for the artificial reproduction of chub. Consequently, it was decided that the fish would obtain only this agent in the final year of research. In last year (experiment II), chub spawners were taken to the hatchery under controlled conditions every few weeks from February to the beginning of June. Periodically, the maturity of oocytes was checked. As soon as the oocytes had achieved stage 2–3 of maturity, fish were obtained ovopel. It was noted that there was no problem with collecting semen. Obtaining oocytes was much more difficult. Most frequently, they were not obtained at all or obtained in very small amounts. It was also observed that the administration of hormones caused a very quick maturation of gonads and their over-maturation. 相似文献
66.
澄海莱芜人工鱼礁集鱼效果初步评价 总被引:11,自引:2,他引:9
2003和2007年分别对澄海莱芜人工鱼礁区进行了投礁前的本底调查和投礁后的跟踪调查。结果表明,投礁后礁区海域游泳生物的资源密度明显比投礁前高,增加了25.63倍;礁区海域各类资源种类均比投礁前丰富,总种数由投礁前的23种增加至41种,比投礁前增加了0.78倍,其中,蟹类种数增加最多,增加了1.75倍;在本底调查中没有出现的经济种类龙头鱼Harpodon nehereus和红星梭子蟹Portunus sanguinolentus在跟踪调查中已成为主要优势种;Shannon—Wienver多样性指数(H’)在礁区和对比区均比投礁前有所增加。表明鱼礁投放后,鱼礁区集鱼效果和群落结构明显改善,人工鱼礁建设取得了明显的生态效益和经济效益。 相似文献
67.
Sung-Je Choi Eun-Jeong Park Hirotoshi Endo Yukihiro Kitade Naotsune Saga 《Fisheries Science》2008,74(4):822-829
ABSTRACT: To investigate inheritance of chloroplasts and mitochondria (organelles) in the marine red alga Porphyra yezoensis , cleaved amplified polymorphic sequence (CAPS) profiles of the two strains, TU-2 and KGJ, as parental gametophytes and 44 hybrid sporophytes (i.e. female of TU-2 and male of KGJ) were examined. A carbamyl phosphate synthase small subunit gene ( carA ) and ribosomal protein S11 gene ( rps11 )-small subunit ribosomal RNA gene ( rns ) spacer region were used as molecular markers for the chloroplast and mitochondrial DNAs, respectively. Thirty-eight of 44 (86.4%) conchocelis colonies showed maternal banding patterns, five (11.4%) colonies showed biparental bands and one (2.2%) colony showed paternal bands in CAPS analyses both with chloroplast and mitochondrial markers. These results suggest that organelles of P. yezoensis are inherited uniparentally from the female parent. 相似文献
68.
Effects of landscape structure on nest predation in roadsides of a midwestern agroecosystem: a multiscale analysis 总被引:1,自引:1,他引:0
Bergin Timothy M. Best Louis B. Freemark Kathryn E. Koehler Kenneth J. 《Landscape Ecology》2000,15(2):131-143
Nest predation is an important cause of mortality for many bird species, especially in grassland ecosystems where generalist predators have responded positively to human disturbance and landscape fragmentation. Our study evaluated the influence of the composition and configuration of the surrounding landscape on nest predation. Transects consisting of 10 artificial ground nests each were set up in 136 roadsides in six watersheds in south-central Iowa. Nest predation on individual roadside transects ranged from 0 to 100% and averaged 23%. The relationship of landscape structure within spatially-nested landscapes surrounding each roadside transect (within 200, 400, 800, 1200, and 1600 m of the transect line) to nest predation was evaluated by using multiple regression and canonical correlation analyses. The results of this multiscale landscape analysis demonstrated that predation on ground nests was affected by the surrounding landscape mosaic and that nest predators with different-sized home ranges and habitat affinities responded to landscapes in different ways. In general, wooded habitats were associated with greater nest predation, whereas herbaceous habitats (except alfalfa/pasture) either were associated with less nest predation or were not important. Different landscape variables were important at different spatial scales. Whereas some block-cover habitats such as woodland were important at all scales, others such as rowcrops and alfalfa/pasture were important at large scales. Some strip-cover habitats such as gravel roads and paved roads were important at small scales, but others such as wooded roadsides were important at all all scales. Most landscape metrics (e.g., mean patch size and edge density) were important at large scales. Our study demonstrated that the relationships between landscape structure and predator assemblages are complex, thus making efforts to enhance avian productivity in agricultural landscapes a difficult management goal. 相似文献
69.
Adaptive neuro fuzzy inference system (ANFIS) and genetic algorithm–artificial neural network (GA-ANN) models were used to predict the effect of methyl jasmonate (at three levels 0, 0.01, and 0.1 mM) and storage time (0, 14, 28, 42, 56, 70, and 84 days) on quality parameters and physiological changes of pomegranate fruits during storage. Methyl jasmonate reduced chilling injury and improved quality characteristics of pomegranates during postharvest storage. The GA-ANN and ANFIS were fed with two inputs of methyl jasmonate and storage time. The results showed that GA-ANN predictions agreed with experimental data and the GA-ANN with 14 neurons in one hidden layer can predict physiological changes and quality parameters of pomegranate (weight loss, pH, chilling injury index, ion leakage, ethylene, respiration, polyphenols, anthocyanins, and total antioxidant activity) with correlation coefficients equal to 0.87. The ANFIS model was trained by a hybrid method and agreement between experimental data and ANFIS predictions was significant (r = 0.90). 相似文献
70.
考虑非线性摩擦模型的机器人动力学参数辨识 总被引:1,自引:0,他引:1
针对机器人动力学参数辨识的问题,提出了一种基于人工蜂群算法的辨识方法。考虑到关节摩擦特性,引入非线性摩擦模型,推导了机器人动力学模型的非线性形式。设计满足速度、加速度边界条件的五阶傅里叶级数作为激励轨迹来采集实验数据;利用人工蜂群算法,以蜂群为搜索单位,通过群体间的信息交流方式与优胜劣汰机制,对模型中的未知参数进行了辨识。最后,对得到的辨识模型进行了分析与验证,结果表明通过辨识得到关节预测力矩与测量力矩有较高的匹配度,所建立的非线性模型能够更好地描述机器人的动力学特性。 相似文献