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1.
为研究大规模风电场并网运行对电容器组优化调度的影响,提出了含风电场功率机会约束的电容器组调度二阶段优化模型.采用平均近似估计法将二阶段模型转换为确定性模型,使用拟蒙特卡罗Hahon采样法和场景削减技术处理风功率的波动性.求解一种电容器组调度方案,充分利用现有的电容器组资源,使系统在风功率波动时仍能保持较大的静态电压稳定临界功率.最后,以IEEE-30、IEEE-118节点系统为例,分别计算不同置信概率条件下系统的临界功率期望值及相应的电容器组调度方案.结果表明所提方法得到的调度方案可靠有效,鲁棒性强,应用前景广阔.  相似文献   
2.
模糊神经网络汇集神经网络和模糊逻辑的优点,能有效避免神经网络的“黑箱”操作,但存在“维数爆炸”现象。将粗糙集和模糊神经网络有机集成,构建财务困境预警的二阶段模型:第一阶段利用粗糙集知识约简对数据集降维消冗,提取最优指标集;第二阶段以最优指标集设计基于模糊神经网络的财务困境预警模型。该模型融合粗糙集和模糊神经网络的特点,能提高网络结构的精练性、启发性和透明性。应用实例的结果表明该模型能有效克服“维数灾难”,避免数据噪声引起的模型过度适应,提高模型预测准确性。  相似文献   
3.
以长三洲制造业为研究对象,在总结现有技术创新绩效评价研究文献的基础上,通过建立两阶段模型来解决技术创新绩效评价中投入产出比的关键问题,并对长三角制造业技术创新绩效进行了评价。  相似文献   
4.
以长三洲制造业为研究对象,在总结现有技术创新绩效评价研究文献的基础上,通过建立两阶段模型来解决技术创新绩效评价中投入产出比的关键问题,并对长三角制造业技术创新绩效进行了评价。  相似文献   
5.
This paper presents the optimising control technique for a Toyota Corolla four-cylinder, 1.8-L hydrogen powered car. Based on the extensive experimental tuning data, statistical two stage models and calibration generation methodology are carried out, in which ignition timing, injection timing, injection duration and corresponding lambda value (indicate air to fuel ratio) are chosen as control variables while engine output torque and exhaust NOx emissions are chosen as performance index functions. The trade-off study is employed to optimise performance of hydrogen engine by considering different optimisation objectives at different engine operating states. Those engine operating states are defined by the throttle position and opening speed of throttle, except start and idle load states that need the auxiliary control parameters to be added in. Each value of ignition advance, lambda, injection duration and injection end angle are tested and the hydrogen engine is found to have good drivability and reliable on road optimisation. This work is a step towards establishing optimising control methodology of hydrogen powered car via application of advanced power train techniques while saving time, money and limiting damage for innovative hydrogen engine in early experimental fine tuning process.  相似文献   
6.
This paper presents a research work on intelligent two-stage modelling system to estimate a hydrogen internal combustion engine performances including: engine torque and oxides of nitrogen emissions. In the created models, the ignition timing is chosen as a local input, while the engine speed, throttle position, injection duration, injection end angle and lambda are chosen as global inputs. While previous papers [1], [2], [3] and [4] included tuning procedures and hydrogen engine performances, intelligent emissions prediction of hydrogen car, and two-stage modelling of torque, this paper carries on from those observations to develop a completed two-stage modelling system of the converted hydrogen engine. More details on individual two-stage models are provided based on data recorded during the fine tuning process on dynamometer. This work is a step towards establishing intelligent two-stage modelling of hydrogen powered car via application of response surface methodology with hydrogen engine in the loop simulation and testing.  相似文献   
7.
利用黏度、电导、表面张力和荧光光谱实验手段研究了聚乙烯基吡咯烷酮(PVP)和十二烷基硫酸钠(SDS)在水溶液中的相互作用,发现对SDS来说存在三个不同的特征浓度:临界聚集浓度(CAC)、CAC2和高分子饱和浓度(PSP)。实验结果表明,PVP和SDS在水溶液中的相互作用可以用类似于描述聚电解质和带相反电荷表面活性剂之间相互作用的两阶段模型解释:初始阶段(CSDS>CAC),带负电荷的SDS分子主要以单个的方式吸附到PVP带正电的侧基上;第二阶段(CSDS>CAC2),SDS分子通过疏水相互作用以协同的方式吸附到PVP分子链上形成胶束,在浓度为PSP时达到饱和。  相似文献   
8.
Stroke is a common acute neurologic and disabling disease. Orthostatic hypertension (OH) is one of the catastrophic cardiovascular conditions. If a stroke patient has OH, he/she has higher chance to fall or syncope during the following courses of treatment. This can result in possible bone fracture and the burden of medical cost therefore increases. How to early diagnose OH is clinically important. However, there is no obvious time-saving method for clinical evaluation except to check the postural blood pressure.This paper uses clinical data to identify potential clinical factors that are associated with OH. The data include repeatedly observed blood pressure, and the patient’s basic characteristics and clinical symptoms. A traditional logistic regression is not appropriate for such data. The paper modifies the two-stage model proposed by Tsiatis et al. (1995) and the joint model proposed by Wulfsohn and Tsiatis (1997) to take into account of a sequence of repeated measures to predict OH. The large sample properties of estimators of modified models are derived. Monte Carlo simulations are performed to evaluate the accuracy of these estimators. A case study is presented.  相似文献   
9.
含风电场的机组组合二阶段随机模型及其改进算法   总被引:1,自引:0,他引:1  
提出一种含风电场的机组组合二阶段随机规划模型,将风电功率作为随机变量处理,目标函数包含常规机组发电成本和切负荷惩罚费用,由于风电功率存在多种可能的情景,后一种费用采用期望值形式,同时提出一种求解二阶段模型的 SAA-自适应多切割 L 形算法,具体为首先基于抽样平均逼近(SAA)理论,将随机模型转换成确定性模型,然后提出一种自适应多切割L 形算法求解。求解中引入全局辅助变量实现迭代过程中历史最优切割信息的保存,并设置主模型约束条件数上限保证模型始终具有较小的规模。与传统单切割和多切割L形算法相比,所提出算法的迭代次数介于两者之间,但计算时间要少于两者。最后通过3机、10机和100机算例在不同数量的风电情景下仿真计算,结果表明本文模型可以有效处理风电随机性,SAA-自适应多切割L形算法在样本数量较大的情况下保持了良好的收敛性和可靠性。  相似文献   
10.
This study presents two extensions to the two‐stage expectation‐confirmation theory of information systems (IS) continuance. First, we expand the belief set from perceived usefulness in the original IS continuance model to include three additional predictors identified in the unified theory of acceptance and use of technology, namely effort expectancy, social influence and facilitating conditions. Second, we ground the IS continuance model in the context of transactional systems that involve transmission of personal and sensitive information and include trust as a key contextual belief in the model. To test the expanded IS continuance model, we conducted a longitudinal field study of 3159 Hong Kong citizens across two electronic government (e‐government) technologies that enable citizens' access to government services. In general, the results support the expanded model that provides a rich understanding of the changes in the pre‐usage beliefs and attitudes through the emergent constructs of disconfirmation and satisfaction, ultimately influencing IS continuance intention. Finally, we discuss the theoretical and practical implications of the expanded model.  相似文献   
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