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1.
高比例新能源及多源耦合是电力系统发展的重要特征,这也为系统稳定经济运行提出了新挑战。该文以园区型多能系统为对象,研究了分布式多元随机动态场景分析,从多时空角度有效量化不确定因素给系统造成的影响,可为系统灵活重构、多维度协同运行与决策提供有力模型与场景支撑。首先由预测误差驱动拟合多元功率预测误差概率分布,全面反映随机功率出力信息,提高模型泛化性;以时序相关范围参数为数据驱动关联变量,高效动态控制波动强度;最终场景生成利用逆变换映射思想保证置信度。然后针对典型场景提取,提出一种综合递归聚类思想的多段嵌套削减算法,结合改进Wasserstein距离指标,兼具准确、时效、稳定方面的优势。最后由对比实验论证该方法的前沿有效性。 相似文献
2.
《Journal of dairy science》2022,105(5):4314-4323
We tested the hypothesis that the size of a beef cattle population destined for use on dairy females is smaller under optimum-contribution selection (OCS) than under truncation selection (TRS) at the same genetic gain (ΔG) and the same rate of inbreeding (ΔF). We used stochastic simulation to estimate true ΔG realized at a 0.005 ΔF in breeding schemes with OCS or TRS. The schemes for the beef cattle population also differed in the number of purebred offspring per dam and the total number of purebred offspring per generation. Dams of the next generation were exclusively selected among the one-year-old heifers. All dams were donors for embryo transfer and produced a maximum of 5 or 10 offspring. The total number of purebred offspring per generation was: 400, 800, 1,600 or 4,000 calves, and it was used as a measure of population size. Rate of inbreeding was predicted and controlled using pedigree relationships. Each OCS (TRS) scheme was simulated for 10 discrete generations and replicated 100 (200) times. The OCS scheme and the TRS scheme with a maximum of 10 offspring per dam required approximately 783 and 1,257 purebred offspring per generation to realize a true ΔG of €14 and a ΔF of 0.005 per generation. Schemes with a maximum of 5 offspring per dam required more purebred offspring per generation to realize a similar true ΔG and a similar ΔF. Our results show that OCS and multiple ovulation and embryo transfer act on selection intensity through different mechanisms to achieve fewer selection candidates and fewer selected sires and dams than under TRS at the same ΔG and a fixed ΔF. Therefore, we advocate the use of a breeding scheme with OCS and multiple ovulation and embryo transfer for beef cattle destined for use on dairy females because it is favorable both from an economic perspective and a carbon footprint perspective. 相似文献
3.
Le Fang Qian Sun Yong-Hong Duan Jing Zhai Dan Wang Jie-Xin Wang 《Frontiers of Chemical Science and Engineering》2021,15(4):902
BaSO4 nanoparticles as important functional materials have attracted considerable research interests, due to their X-rays barrier and absorption properties. However, most of BaSO4 nanoparticles prepared by traditional technology are nanopowders with broad size distribution and poor dispersibility, which may greatly limit their applications. To the best of our knowledge, the synthesis of transparent BaSO4 nanodispersions was rarely reported. Here, we firstly present a novel and efficient method to prepare transparent and stable BaSO4 nanodispersions with a relatively small particle size around 10 to 17 nm using a precipitation method in a rotating packed bed (RPB), followed by a modification treatment using stearic acid. Compared with the BaSO4 prepared in a traditional stirred tank, the product prepared using an RPB has much smaller particle size and narrower size distribution. More importantly, by using RPB, the reaction time can be significantly decreased from 20 min to 18 s. Furthermore, the transparent BaSO4-polyvinyl butyral nanocomposite films with good X-ray shielding performance can be easily fabricated. We believe that the stable BaSO4 nanodispersions may have a wide range of applications for transparent composite materials and coatings with X-ray shielding performance for future research. 相似文献
4.
Analysis of the convective heat transfer and flow behavior around two counter‐rotating side‐by‐side cylinders 下载免费PDF全文
This study presents details of the heat and fluid flow around two counter‐rotating cylinders. For this goal, three different nondimensional gap spaces such as G/D = 1.5, 2.0, and 3.0 are examined in the constant Reynolds number of 200 and Prandtl number of 7.0. In addition, computations are carried out at various nondimensional rotating speeds (R.S) in the range from 0 to 4. The obtained results are validated against the available data in the open literature for stationary cases. The results showed that the flow structure, vortex shedding process, and exerted forces on the cylinders strongly depended on the R.S and G/D. Reductions of the drag coefficients are observed for both cylinders with increasing the R.S due to suppression of the wake downstream of the cylinders at low R.S and eliminating the vortex shedding process at high R.S. Finally, it is demonstrated that, regardless of the G/D value, increasing the R.S diminishes dramatically the convective heat exchange rate between the cylinders and fluid flow. 相似文献
5.
离心式旋流雾化喷嘴内流场的速度分布决定了喷嘴的雾化性能。利用VOF两相流模型和RNG k-ε湍流模型对管道中减温水通过旋流喷嘴雾化并与过热蒸汽混合的整个流动过程进行了三维数值模拟,获得了喷嘴雾化场的流动过程,着重分析了内外流场的速度分布特性。研究表明:流体通过离心式旋流喷嘴的切向孔后变成旋转流体,从喷嘴出口螺旋喷出后,迅速由液柱变为沿一定的锥角扩散的液膜,液膜逐渐雾化为液滴;在喷嘴内部的旋转流体,其合速度与切向速度沿径向,都是先增加后减小;随着流通截面发生改变,其速度的变化主要发生在轴向分量上,切向速度的变化比较小;流体从旋流喷嘴喷出雾化,会在喷嘴出口中心轴线附近形成回流区;当管道中的流体具有一定的流速时,还会在喷嘴前壁边缘附近形成回流区。 相似文献
6.
董宪久 《有色金属(矿山部分)》2018,70(4)
研究采空区稳定性评价新方法或模型对于提高采空区稳定性状况评判的可靠度、保证地下矿山的生产安全具有重要意义。选取工程地质环境、岩体质量、采空区几何参数和围岩应力四方面的因素作为采空区稳定性的主要影响因子,构建了地下矿山采空区稳定性评价指标体系。基于功效系数法原理,采用三标度改进层次分析法确定各评价指标的权重系数,建立了采空区稳定性评判分级新模型。将所建立模型运用到盘龙铅锌矿采空区稳定性评价研究,评判结果与工程实际相吻合,验证了基于功效系数法的采空区稳定性评判分级模型的适用性和可靠性,为采空区稳定性评价提供了一种新方法。 相似文献
7.
目前电解法作为纯镍生产的主流方法被广泛采用,其主要特点为通过导电棒引导电流,最终将电流导向种板。因此在实际生产中由于受到承重、撞击等各种因素的影响,导电棒会产生形变。因为整个电解过程的效率和自动化程度的提高需要使用满足要求直线度的导电棒,所以一个电解周期后必须矫直产生形变的导电棒。本文以国内某镍冶炼厂中规格为Φ36 mm×3 mm×1 350 mm的电镍导电棒为研究对象,对转毂式斜辊矫直机进行研究,利用优化后的矫直机矫直编为两组的20根电镍导电棒,对矫直后的导电棒进行测量,并分析比较其平直度,从而验证该种矫直机能否完成电镍导电棒的矫直。 相似文献
8.
文章结合北京新机场高速公路照明工程实例,阐述了常规照明控制系统的现状,分析了基于新兴的LoRa物联网技术智能照明控制方案的系统原理和系统构成、系统在高速公路智能照明控制领域的应用以及系统应用能达到的节能和管理效益的提升效果,并对系统的扩展应用前景做了研究分析。 相似文献
9.
Linda A. Felton 《Drug development and industrial pharmacy》2018,44(7):1049-1055
Many drugs are bitter and overcoming this bitter taste is a major barrier in developing a successful product, especially for pediatric patients. Approaches to mask taste include changing taste perception, creating a physical barrier to separate the drug from interacting with taste buds, and changing drug solubility. This review is focused on polymers and the different ways these materials are used to achieve taste masking. Attention is given to systems that are easily swallowed, as swallowability is another concern in developing palatable products for pediatrics. Variables that should be considered when selecting a taste-masking approach are also presented. 相似文献
10.