Power load forecasting

For the electric power factory, the power load forecasting problem, including load forecasting and consumption predicting, is crucial to work planning. According to the predicting time, it can be divided into long-term forecasting, mid-term forecasting, short-term forecasting and ultra-short-term forecasting. The long-term and mid-term forecasting are mainly used for macro control, and their forecasting time arrange are from one year to ten years and from one month to twelve months respectively. The short-term forecasting which prediction time is from one day to seven days is used in generators macroeconomic control, power exchange plan and some other areas. Predicting the situation in next 24 hours is named as the ultra-short-term forecasting which is used for failure prediction, emergency treatment and frequency control. In general, the forecast accuracy is different for different prediction time. The longer is the time, the lower accurate is the prediction. As the unique power supplier in Huizhou (China), Huizhou Electric Power wants to know the solution to the problems: 1. Prediction of the total electrical consumption and the peak load of the city in 2006 based on the economy development and the feature of the city. 2. Monthly prediction of the consumption and peak load in 2006. 3. Daily prediction of the consumption and peak load from July 10th to 16th in 2006. 4. Prediction of the load every 15 minutes of July 10th. 5. Real-time forecasting which means to amend the existing load prediction for next 15 minute

Tungsten fibre reinforced Zr-based bulk metallic glass composites

A Zr-based bulk metallic glass (BMG) alloy with the composition (Zr55Al10Ni5Cu30)98.5Si1.5 was used as the base material to form BMG composites. Tungsten fiber reinforced BMG composites were successfully fabricated by pressure metal infiltration technique, with the volume fraction of the tungsten fiber ranging from 10% to 70%. Microstructure and mechanical properties of the BMG composites were investigated. Tungsten reinforcement significantly increased the material’s ductility by changing the compressive failure mode from single shear band propagation to multiple shear bands propagation, and transferring stress from matrix to tungsten fibers

Assessing Ageing Condition of Mineral Oil-Paper Insulation by Polarization/Depolarization Current

Accurately assessing the ageing status of oil-paper insulation in transformer is essential and important. Polarization and Depolarization Current (PDC) technique is effective in assessing the condition of oil-paper insulation system. Though the PDC behaviour of mineral oil-paper insulation has been widely investigated, there is no report about how to make the quantitative analysis of mineral oil-paper insulation ageing condition by PDC. The PDC characteristics of mineral oil-paper insulation samples were investigated over the ageing period at 110°C. A new method for assessing the ageing condition of mineral oil-paper insulation by calculating the depolarization charge quantity was proposed. Results show that the depolarization charge quantity of mineral oil-paper insulation sample is very sensitive to its ageing condition. The stable depolarization charge quantity could be used to predict the ageing condition of mineral oil-paper insulation

Games Parents and Adolescents Play: Risky Behaviors, Parental Reputation, and Strategic Transfers

This paper examines reputation formation in intra-familial interactions. We consider parental reputation in a repeated two-stage game in which adolescents decide whether to give a teen birth or drop out of high school, and given adolescent decisions, the parent decides whether to house and support his children beyond age 18. Drawing on the work of Milgrom and Roberts (1982) and Kreps and Wilson (1982), we show that the parent has, under certain conditions, the incentive to penalize older children for their teenage risky behaviors in order to dissuade the younger children from the same risky behaviors. The model generates two empirical implications: the likelihood of teen risky behaviors and parental transfers to a child who engaged in teen risky behaviors will decrease with the number of remaining children at risk. We test these two implications, using data from the National Longitudinal Survey of Youth, 1979 Cohort (NLSY79). Exploiting the availability of repeated observations on individual respondents and of observations on multiple siblings, we find evidence in favor of both predictions.

Cosmological dynamics of scalar fields with O(N) symmetry

In this paper, we study the cosmological dynamics of scalar fields with O(N) symmetry in general potentials. We compare the phase space of the dynamical systems of the quintessence and phantom and give the conditions for the existence of various attractors as well as their cosmological implications. We also show that the existence of tracking attractor in O(N) phantom models require the potential with $\Gamma<1/2$, which makes the models with exponential potential possess no tracking attractor.Comment: 9 pages, 4 figures; Replaced with the version to be published in Classical and Quantum Gravity. Reference adde

Bending vibration of an automotive turbocharger under the influence of rotor imbalance

As one of the most common faults, rotor imbalance in a turbocharger will give rise to the bending vibration, which may cause damage to and even destroy the bearings and impellers. Therefore, it is necessary to detect rotor imbalance as early as possible. The present paper develops a mathematical model for investigating the rotor dynamic characteristics of a commercial automotive turbocharger supported on floating ring bearings. In order to reveal the behaviours of oil film instabilities the model takes into account nonlinear hydrodynamic oil film forces instead of linearization. A two-dimensional elastic collision model is introduced to deal with the rub-impact process between such solid parts as journal, floating ring and the bearing. In addition, the change of clearances in floating ring bearing due to temperature increases are also estimated by ignoring the variation of lubricating oil viscosity. Following model development, a numerical simulation is implemented to study the bending vibration of the turbocharger and floating ring bearing under the influence of rotor imbalance. This study paves a foundation for the monitoring of turbochargers