Advanced Materials Research Vols. 268-270

Abstract: This paper researches control problem for active power filters with three-level NPC inverter and proposes a novel PI control algorithm for tracking harmonic command current. This novel PI control algorithm can suppress the periodic error in the whole system to achieve zero steady error tracking. In this scheme, the state variables are estimated with a state observer to cancel the delay of one sampling period in this digital control system. Harmonic current is predicted with a repetitive algorithm simultaneity, which makes use of the repetitive nature of load current. The controller is analyzed and designed in the paper, and the experiment results illustrate that this APF can be controlled in a satisfactory way.

Abstract: This paper proposes a blend control scheme of APF based on harmonic voltage to solve the problem that load current detection APF cannot change the harmonic impedance in distribution system. In addition, based on the relationship between the rated volt-ampere of APF and the load volt-ampere, the conductance value could automatic adjustment. Computer simulation and laboratory system are designed and constructed to verify the validity and effectiveness of the shunt active filter equipped with the blend control. The shunt active filter with blend control not only can compensate the nonlinear load harmonic current but also can help to damp the harmonic voltage in distribution system.

Abstract: In this paper, a reasoning model is proposed for energy efficiency task allocation in wireless sensor network. The presented energy efficient contract net protocol is used to implement the negotiation process. Multi-issue scoring function can evaluate the offer with multi-issues in a quantifiable way. An energy threshold is brought to decrease communications which will turn out to decrease nodes’ energy consumption. And the usage of energy threshold also promote the nodes with high level energy have more chance to implement tasks. The simulation results show that the allocation model has outstanding performance maintaining a fair energy balance and is energy efficient in negotiation process.

Abstract: In this paper, it is aimed at the agricultural soil after harvest in WeiNan and its surrounding countries, researching the importance of the iron element in soil, animals and plants. organic substance content low, and the iron content also generally low. It can be broadly ranked as following: Pucheng ＞ Fuping ＞ Hancheng ＞ Dali ＞ Tongguan . The distribution of iron content of agricultural soil over the Weinna area, that is to say, is the East south low and increasing from the Eastsouth (Tongguan) to the other neighboring countries. And to some extent there minimum and maximum in each county. Natural conditions and human factors contributed to the differences in soil iron content and distribution.

Abstract: According to some statistical surveys and data about the land from the year 1984 to 2004, here’s an analysis on where the financial investment in soil and water conservation comes and goes in tins district. In conclusion, after the actions in improving the soil and water, there’s an obvious decent in the flow rate of the channel’s interior diameter as well as the amount of soil erosion, a rise in vegetation coverage, and some improvement in ecological environment together with a great improvement to the natives’ living standard.

Abstract: The design and implementation of the control system of an ARM9-based biochemical analyzer was introduced in detail. The S3C2440, an ARM9-based MCU, was the core of the control system. Precision regulator circuit of light of the analyzer was designed to stabilize the voltage supply of the light source. Closed-loop motor positioning control technology and freely programmable CPLD stepper motor sub-circuit technology were used to precisely position the grating. And flexible gain control technology based on digital potentiometers was employed to solve the problem of signal regulation. Such core technical problems was solved in succession, it thereby improves the instrument's performance and function and provides a number of inexpensive high-quality products for domestic small and medium sized hospitals especially rural hospitals and promoted the establishment of those hospitals in consequence.

Abstract: The advanced implicit generalized predictive self-tuning control algorithm was used against those characteristics of the outlet’s gas pressure such as large-time delay, time varying, vulnerable to random noise and so on. Through the simulation, a good tracking performance was shown, and in the process of actual operation, it also achieved satisfactory control effect.

Abstract: Concept-Resources Maps Authoring System is an independent software R&D by Shanghai Distance Education Group. Concept-resources maps conceive a new way to exhibit education resources. With the help of Concept-Resources Maps Authoring System(CRMAS), teachers and students can combine and organize education resources by means of concept maps.This paper first introduced research background, analysised meanings and main features of CRMAS, then analyzed the system’s architecture and RIA technology, and finally introduced its application in 52 laboratory schools in Shanghai.

Abstract: By analyzing Ansai county utilization current situation and land utilization the past years change condition by the fact that 1989-2005 annual land inquires into a data's to locality , have revealed land utilization middle have problem. Ansai County land use patterns by state policy affects in more, at the same time for the oil industry also has a great influence on the land use type.

Abstract: Many 3D films use technologies of facial expression recognition. In order to use the existing technologies, a large number of markers shall be attached to a face, a camera is fixed in front of the face, and movements of the markers are calculated. However, the markers calculate only the changes in regions where the markers are attached, which makes difficult realistic recognition of facial expressions. Therefore, this study extracted a preliminary eye region in 320*240 by defining specific location values of the eye. And the final eye region was selected from the preliminary region. This study suggests an improved method of detecting an eye region, reducing errors arising from noise.