The Separation of Powers from Functions and the Establishment of a New Structure of Management and Operation of State-owned Assets

The development of the socialist market economy demands the furtherintensification of the reform of the management operating system (MOS)of the state-owned assets, the strengthening of the efficiency in the man-agement of state-owned assets,and the improvement of the operating bene-

INVESTIGATION OF DOMINANT FREQUENCIES IN TRANSITION REYNOLDS NUMBER RANGE OF FLOW AROUND A CIRCULAR CYLINDER PARTⅡ: THEORETICAL DETERMINATION OF THE RELATIONSHIP BETWEEN VORTEX SHEDDING AND TRANSITION FREQUENCIES AT DIFFERENT REYNOLDS NUMBERS

An attempt has been made to explore whether the power relation can be obtained from theoretical considerations. The classical laminar and turbulent boundary layer concepts have been employed to determine appropriate values of the scaling lengths associated with vortex shedding and shear layer frequencies to predict the power law relationship with Reynolds number. The predicted results are in good agreement with experimental results. The findings will provide a greater insight into the overall phenomenon involved.

An Improved Calculation of the Thermodynamically Based Allocation of Cumulative Exergy Consumption in the Petroleum Distillation Process

One of the most common problems arising from the application of exergy analysis is the allocation of cumulative exergy consumption （CExC） in the petroleum distillation process yielding several useful products. Based on the concept of exergy, an improved calculation of the minimum separation power of product （MSPP） in the petroleum distillation process is provided in this article. The calculation of MSPP can be derived from the concept of exergy. The related mathematical models are established. Finally, application of this method to a case study is given, and the results are compared with the ones using mass as an allocation parameter.

A cubic triboelectric generator as a self-powered orientation sensor

Recently, triboelectric generator(TEG) has attracted a lot of attention due to its high output voltage and low-cost fabrication process. Here, a novel cubic TEG box is designed, which has separated electrodes on different surfaces. Thanks to the specially designed structure, it can scavenge vibration energy from all directions. Firstly the device is investigated through finite element method(FEM) simulation. Then the device is evaluated by experiments. The measuremental results show that this device can generate an amount of 25 n C charge during once shake by charging a 10 n F capacitor. Besides, an output voltage about 100 V is obtained, which is able to directly light up several light-emitting diodes(LEDs) simultaneously. At last, the device is utilized as a self-powered orientation sensor, which shows explicit directivity. This work extends the applications of TEG for ambient vibration energy harvesting techniques and the self-powered orientation sensor.

Effective Controlled Islanding Method for Power Grids Solving a Sequence of Optimization Problems

Controlled islanding is an important approach to prevent instability in power grids.In this paper,a novel approach is proposed for power system separation,which consists of two steps:1)Finding multiple islanding scenarios;2)Choosing the best option to obtain the most desirable island.In the first step,different islanding solutions are determined by a proposed hierarchical clustering method.In this algorithm,which is based on a minimum active power flow disruption objective function,the generator coherency constraints are considered in the clustering process.In the second step,the best separation scenario is chosen based on an arbitrary objective function.Particularly,in this paper,the amount of load shedding and the voltage profile deviation after separation are considered as the final criteria to select the best solution among available options.In so doing,the degree of load importance is also taken into account.The proposed two-step method is applied on an IEEE 9-bus test system and it is also evaluated on an IEEE 39-bus grid.The simulation results on the IEEE 39-bus grid and the comparative analysis with a state-of-the-art method confirm that the final islanding solution is more optimized based on the secondary criteria,which have not been addressed in the existing approaches.Moreover,the proposed method is computationally efficient and can be employed in real-scale power grids.