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排序方式: 共有624条查询结果,搜索用时 31 毫秒
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周淑娟 《廊坊师范学院学报(自然科学版)》2011,11(2):40-43
神经网络能精确地对复杂问题进行预测,但易受训练过度的影响且训练速度慢。遗传算法是一种全局优化搜索算法,这种方法的要求是拟合度函数必须收敛于最小误差,这为具体的实现方案留下了许多自由空间。将遗传算法与神经网络结合起来使用可以在较高的层次上提高模型的可理解性。 相似文献
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Stephanie M. Curenton Shana E. Rochester Jacqueline Sims Nneka Ibekwe-Okafor Iheoma U. Iruka Arlene G. García-Miranda Jessica Whittaker 《Child development》2022,93(3):681-698
This study used secondary data from the My Teaching Partner-Math/Science 2013–2016 randomized control trial to explore whether equitable sociocultural classroom interactions (see Curenton et al., 2019) were associated with the skills of 105 four- and five-year-olds (52% boys; drawn from 20 unique video recordings of preschool teachers/classrooms; 43% were Black, Latine, Asian, or other racially marginalized learners). Equitable interactions predicted children's skills with effect sizes ranging from small (0.01–0.44) to large (1.00). Moderation analyses revealed that when classrooms had more racially marginalized learners, teachers’ use of equitable disciplinary and personalized learning practices were associated with higher executive functioning gains across prekindergarten. Findings illustrate how classroom composition can be a key indicator between equitable classroom interactions and young children's early skills. 相似文献
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This paper presents a stochastic multi-parameters divergence method for online parameter optimization of fractional-order proportional–integral–derivative (PID) controllers. The method is used for auto-tuning without the need for exact mathematical plant model and it is applicable to diverse plant transfer functions. The proposed controller tuning algorithm is capable of adaptively responding to parameter fluctuations and model uncertainties in real systems. Adaptation skill enhances controller performance for real-time applications. Simulations and experimental observations are carried on a prototype helicopter model to confirm the performance improvements obtained by the online auto-tuning of fractional-order PID structure in laboratory conditions. 相似文献
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Ajay Kumar D. H. Shah M. G. R. Rajan U. R. Thakare S. M. Sharma 《Indian journal of clinical biochemistry : IJCB》1992,7(2):159-164
An external quality assessment was conducted to assess the performance of various laboratories for RIA of thhyroid related
hormones in two phases. In the first phase thirty five laboratories participated. At the end of first phase a meeting cum
workshop was organised to discuss the results of first phase, difficultires faced by the participants and pinpoint the short
oming. A second phase was then initiated with an objective of improvement in the performance, if any, where twelve samples
from four pools were distributed to twenty four laboratories who participated for the second phase. The overall return of
the results increased significantly from 71.8% (1586/2208) for the first phase to 92.4% (732/792) for the second phase. The
inter laboratory %CV for T3, T4 and TSH were lower during the second phase (30.6%, 19.0% and 31.6% respectively) as compared to those observed during first
phase (36.3%, 22.7% and 52.8% respectively). Similarly, there was an improvement in reproducibility of ALTM as %CV for T3, T4 and TSH decreased from 6.0%, 9.8% and 13.4% respectively to 4.5%, 4.6% and 8.5% respectively. The individual performances
of the participating laboratories viz. bias, variability of bias and imprecision also showed a trend towards improvement as
percent laboratories having desirable or acceptable results for T3, T4 and TSH increased from 10.7%, 60.7% and 0.0% respectively to 20.8%, 66.7% and 22.2% respectively. External quality assessment
thus appears to be beneficial in assessing the performane of a laboratory in comfparison with other laboratories and indeed
helps in improving the performance. 相似文献
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The transport of thermal energy in thermodynamics is described as the product of entropy flow and of the absolute temperature, in analogy to the volume flow and pressure in oil hydraulics and to electric charge flow (= current) and voltage in electronics. Bond graphs are shown to be especially suitable to describe the splitting of applied thermal energy into internal energy and external mechanical work. Transformers and the 0- and 1-junctions of Paynter can illustrate various entropy flow processes, including Carnot engines and heat exchangers. Entropy flow in heat conduction is distinguished from entropy convection, or transport by moving mass, where the entropy/temperature characteristic or equation of state is important. Irreversibilities are represented by impedance transformers reducing temperature and increasing entropy flow but conserving power. 相似文献
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Meena Desai U. M. Donde M. Ikram Khatkhatay 《Indian journal of clinical biochemistry : IJCB》2001,16(1):127-131
Baseline data available on the excretory profiles of estrone giucuronide (E1G), pregnanediol glucuronide (PdG) and luteinising hormone (LH) on human menstrual cycles (n=104) was retrospectively analysed
for identifying the limits of fertile period (FP) to be used as natural method of family planning. The limits of fertile period
are suggested based on centile distribution of E1G and PdG levels during defined phase of menstrual cycle. Two approaches, which do not involve any mathematical calculation
are suggested. In approach A, fertile period is said to have started when E1G value of 35 ng/ml is reached and is said to have ended when the PdG value of 2 μg/ml on two consecutive days is obtained.
The criteria were applied to 30 test cycles in whom authentic fertile period was identified based on excretory profiles of
E1G, PdG and LH throughout the menstrual cycles. When approach A was followed the authentic fertile period was covered in 27
cycles giving an accuracy of 90% with a mean fertile period length of 9.11+1.9 days. In approach B, the cut off limit of E1G value was increased to 55 ng/ml in order to reduce the days of abstinence. Though the length of the fertile period was reduced
to 7.2+1.5 days the accuracy of the approach was 66.6%. Thus the approach A which has accuracy of 90% may appeal to determined
couples who wish to practice family planning by periodic abstinence or restrict the use of barrier methods. 相似文献