Search

This paper gives a hierarchical control strategy of multi-microgrids. The hierarchical control structure is made up with microgrid center controller (MGCC), microgrid controller (MC), generator controller (GC), load controller (LC). Controllers recognize the current operation mode of microgrids according to state trigger event and local operation state, realize transition of operation state. Controller is controlled by the upper controller, but once the communication among controllers is interrupted, MC can operate normally according to its local operation state. Thus, the MCs have a certain independence. The simulation platform is built-up by Netlogo for simulation of controller logic and communication coordination mechanism, OpenDSS for modeling distribution network and multi-microgrids, and matlab for data transmission and control optimization. With the simulation platform, this paper analyzed the characteristics of power regulation and different state transitions of multi-microgrids. Through verification, the strategy is available to realize operation state transition of multi-microgrids, guarantee stability of multi-microgrids under every operation state. Besides, compared with centralized control, it has better control effect and it has faster response.

To understand the oil and gas accumulation rules and main controlling factors of H Basin at different phases, approaches such as reservoir dissection and analysis on the spatial allocation of reservoir accumulation conditions are adopted to divide the reservoir of the main fault depression zones of central H Basin into early and late phases. The widely-spread oil and gas at early phase are obviously more than that of the late phase. The main controlling factors of reservoir accumulation at early phase include source rocks area, antithetic faults - tilted upheavals and sand body of fan delta front subfacies while that of the late phase include sources rocks area, inverted structure and long-term developed fractures. The achievement of the study expounded in this paper is significantly important to correctly understand the oil and gas accumulation rules of complicated faulted-block fields and guide the oil and gas exploration activities.

For the issue of fault impact on the height of water-flowing fractured zone, the study worked out several damage heights of superincumbent stratum under the influence of different dip angles faults. The research shows that small angle fault influence area is apt to develop a wide range of the plastic zone,and the water-flowing fractured zone of high-angle fault influence area is apt to increase along the fault surface and breakover the aquifers of coal seam roof and floor.

The effects of a red phosphorus master batch (RPMB) on a modified intumescent flame retardant (MIFR) ABS composite system (ABS-MIFR) were investigated in this study. The Underwriter's Laboratory Bulletin 94 (UL-94) flame retardancy rating clearly revealed the synergistic interactions of RPMB and MIFR. Thermogravimetric analysis was used to evaluate the thermal decomposition of these flame retardant composite systems. The results show that adding RPMB increased the char residue formation and the thermal stability of ABS-MIFR at high temperature.

The Hong Run petrochemical oil depot is located in a saline area in the north of Weifang, where the contents of chloride and sulfate in this area are very high. Due to the rigorous environmental conditions, concrete with 50 years durability and C40 strength grade was prepared. A kind of corrosion resistance concrete with high performance superfine mineral powder and high performance pumping agent was developed to adapt to the conditions in saline areas. The chloride-penetration resistance ability was investigated by the test of chloride ion rapid electric transport (ASTM C1202). The concrete compressive strength and mortar expansion rate under continuous immersion in four different corrosion solutions was studied. The results showed that the chloride-penetration grade is very low. The compressive strength is high and the mortar expansion rate lower than 0.1%.

In this paper, the effects of drying chamber pressure, heating plate temperature and material thickness on the drying time of Tan lamb in vacuum freeze-drying process were studied using quadratic regression orthogonal design. The results showed that the drying time was significantly affected by drying chamber pressure, heating plate temperature and material thickness as well as the interaction of heating plate temperature and material thickness. The optimized parameters were drying chamber pressure 27.9 Pa, heating plate temperature 47.9°C and material thickness 4.3 mm. On these parameters, the drying time was 4.3 h.

Energy conservation is a long-term strategic approach of economic development. Subway is a most important way of urban mass transit, the energy consumption of subway accounted for a large part in mass transit. Therefore, retrofitting the subway for energy saving is close to the current policy, it can relieve the energy pressure, so it plays an important role on the sustainable development of economy. This paper conducted a survey of Beijing subway energy consumption, and summed up annual energy consumption data of the Beijing subway lines. Based on this research, this paper shows the energy-saving potential of the Beijing subway. Also it lays the foundation of energy saving transformation for subway.

Building energy audit and equipment energy-saving assessment are an important part of the building energy monitoring system in the construction. This paper takes a five-star hotel in Beijing as an example and audits the building energy consumption of the hotel. By testing air conditioning chillers, chilled water pumps, cooling water pumps and other equipments analyses energy-saving potentiality of the conditioning system and lighting equipments. The results would help us put forward some sound energy-saving measures, regulatory frameworks and reduce energy equipment consumption.

As an important tool to study practical problems of biology, engineering and image processing, the cellular neural networks (CNNs) has caused more and more attention. Some interesting results about the existence of solution for cellular neural networks have been obtained. In this paper, by means of iterative analysis, the existence and uniqueness of anti-periodic solution of delayed cellular neural networks with impulsive effects are considered. Some new results are obtained.

A clock-inverter feed-forward toggle flip-flop (CIFF-TFF) based ultra-high-speed 2:1 dynamic frequency divider is designed in a GaAs heterojunction bipolar transistor (HBT) technology with fT of 60 GHz from Win Semiconductors corporation. The co-simulation methodology of electromagnetic field and schematic diagram is utilized in the design. Through tuning the currents in the core and the other parts of the divider separately, the dynamic frequency divider approaches an operating speed of 36 GHz with a power consumption of 162 mW in the core part from a single 6 V supply. The design is currently taped out.

A modeling method of single-phase grid-connected photovoltaic micro-inverter is presented in this paper,which depends on the topology structure of fly-back converter. Simulation of the micro-inverter is performed using Matlab software, which has the virtues of high accuracy and fast speed. Prototype experiment results show that the simulation model can be a true reflection of the working process of a micro-inverter, and could be used to verify the control algorithm and select the control parameters.

In order to get better image Semantics recognition, in this paper, a scene Semantics recognition system based on fuzzy reasoning is presented. The system contains three parts: image preprocessing, target recognition, and fuzzy reasoning machine. Compared with other methods, the outputs of pattern classifiers are fuzzed, the fuzzy relationships between targets are extracted, and fuzzy inference is performed using fuzzy automata. The experiment indicates that this method could overcome the problems of false positive and false negative of pattern classifiers, and perform relatively more accurate image semantics recognition than other existing methods.

To meet different DCS training requirements of thermal staff, while addressing the high cost of purchasing several sets of DCS, this paper presents the general DCS configuration training platform, which is based on Ovation system, could simulate the Symphony, XDPS and other DCS training environments, and complete basic operations such as configuration, compilation, downloading and debugging. This platform gets significant savings in expenses, and provides a new idea for thermal training.

The paper elaborates on the operating principle and technical features of thermo-compression drying process, the kinetics involved in the dewatering process, and the technological process system and equipment used. It is demonstrated by the case of the treatment of Ti-Gypsum using the thermo-compression drying process that the moisture of the products can reach 30%.

A remote supervisory system of classroom lighting based on LonWorks fieldbus is presented, which controls the switch state of lights and the number of lights to turn on, achieving the purpose of energy saving. The administrator can remotely know the situation of each classroom, and be able to perform manually control. The experiment results show that the proposed supervisory system has the qualities of easy to implement, high reliability, and easy to expand.

In this paper, an intelligent warehousing management system (IWMS) using Internet of Things is designed to facilitate the warehousing management. Firstly, the characteristics of IWMS are analyzed, together with some new advanced technologies and theories, such as RFID, Zigbee and heterogeneous network are introduced. Then, the architecture of IWMS is developed and the related management system is accomplished as well. Finally, through the implementation of a prototype system in practical working environment, the operation results show the IWMS can facilitate storekeeper to manage the warehouse and improve logistics capability efficiently.

In this paper, a model of an engine case is designed in Pro/Engineer for fatigue simulation. The meshing is created by the way of Abaqus. According to the working conditions, the boundary restriction of the simulation is defined. By the simulation, the heat distribution of the engine case is given, the causes of relatively high temperature areas are discussed, and the heat-stress distribution is drawn too. The high stress area in the engine case is discovered. The simulation result shows that the steady working stress is about 60MPa, the transient stress is between 90MPa to 120MPa, and the maximal stress is 136MPa. Based on the heat stress the fatigue life of the engine case is analyzed. The research result is a reference of the engine case safe working.

The saline-alkaline geological environment is highly corrosive to the concrete. Aimed at the saline-alkaline geological environment, the article ascertains how to prepare frost resisting and anti-corrosive concrete with strong endurance.

The historical and cultural heritage of contemporary city is facing unprecedented challenges in the fast urbanization process. Against the existing problems of the cultural heritage protection in large-scale construction, such as dispersion, unilateralism, destructiveness along with the loss of city characteristic, the paper analyzes the significance and value of cultural heritage for whole city. It puts forward to establish the integrated conservation view of history city of historical and cultural heritage, then discusses the strategies of integrated conservation of historical and cultural heritage for greater Xian Region example.

An effective theoretical method is developed to analyze three-ball system at contact in a bidimensional case basing on the impact law. The accurate solutions of the post-velocity have been computed in the paper. With the increase of between BallII and Ball III, the post-velocity of Ball III will be less and less. In fact, in the case of , the three-ball system in the same plane is consistent with the three-ball system in co-linear, when , the impact is happened only between BallI and Ball II. It is proved that the vibrating frequency influences only the impact time and the displacement of each ball for the three-ball system in the plane with elastic impact, but can not affect the momentum transfer and the post-velocities of the three balls, and all possible rigid solutions for impact are the limits of the theoretical results in some parameters of the system actually.

More and more scholars have attached importance to the piston effect, which seriously impact the metro environment. In this paper, after referring the present researches on the piston effect domestically and oversea, the author studied their methods and results and then summed up the disadvantages, for the further exploration.

Discusses the Dongguan Changan mold in economic development status and the necessity to establish mold standard parts library, study the technology and related steps for product design in UG / KF environment. Using this technology to solve the problem, unable to integrate into traditional CAD design engineering knowledge and laid the foundation for enterprise storage and reuse of design knowledge, to improve design efficiency and quality and to further the design of intelligent rapid response.

Thermal compression is effective for solid-liquid separation of various materials. In this paper, thermal compression was applied on the dewatering of sewage sludge with coal as a filter aid. Experiments with 0.25-1 mm coal particles (0.2 kg coal/kg dry sludge solid) obtained cakes of solid content over 49%. Higher dosage of coal generated cakes with lower moisture content. The combustion behavior of the sludge cake was studied using TG/DTG analysis. The results showed that a total weight loss of 65.1% occurred from 25 °C to 800 °C, including two major weight loss stages corresponding to loss of moisture and volatile materials respectively.

As an important tool to study practical problems of biology, engineering and image processing, the cellular neural networks (CNNs) has caused more and more attention. Some interesting results about the existence of solution for cellular neural networks have been obtained. In this paper, by means of iterative analysis, the existence of periodic solution and the uniform stability of the equilibrium point of impulsive Hopfield cellular neural networks with distributed delays are considered. Some new results are obtained.

Based on 2-D PFC, non-circular particle with direction was constructed and specimens with different distribution of long axis orientation were established. Loads were applied in vertical direction. Changes of fabric such as the long axis orientation, particle contact direction and particle contact force in the process of loading were analyzed. It was shown that the larger angle of the loading direction and the long axis orientation, the greater strength of specimen and more anisotropic. It was proved by the numerical analysis that tendency of particle contact stress direction is the micro – mechanics reasons of soil’s anisotropy under loading.

The two-degrees-of-freedom VIV of the circular cylinder with high mass-ratio is numerically simulated with the software ANSYS/CFX. The VIV characteristic is analyzed in the different conditions (Ur=3, 5, 6, 8, 10). When Ur is 5, 6, 8 and 10, the conclusion which is different from the cylinder with low mass-ratio can be obtained. When Ur is 3, the frequency of in-line VIV is twice of that of cross-flow VIV which is equal to the frequency ratio between drag force and lift force, and the in-line amplitude is much smaller than the cross-flow amplitude. The motion trace is the crescent. When Ur is 5 and 6, the frequency ratio between the drag force and lift force is still 2, but the main frequency of in-line VIV is mainly the same as that of cross-flow VIV and the secondary frequency of in-line VIV is equal to the frequency of the drag force. The in-line amplitude is still very small compared with the cross-flow amplitude. When Ur is up to 8 and 10, the frequency of in-line VIV is the same as the main frequency of cross-flow VIV which is close to the inherent frequency of the cylinder and is different from the frequency of drag force or lift force. But the secondary frequency of cross-flow VIV is equal to the frequency of the lift force. The amplitude ratio of the VIV between in-line and cross-flow direction is about 0.5. When Ur is 5, 6, 8 and 10, the motion trace is mainly the oval.

3D CAPP has become trend. Based on recognition of manufacturing features, the design model is reconstructed. First, the features of the engine case are classified. The workflow of reconstruction is put forward. Then, the detail ways to identifying manufacturing features are illuminated, and the functions are listed. The design model is reconstructed by redefining geometric and no-geometric information, including surfaces, holes, slots, text, sizes, and so on. The model of the engine case is reconstructed in the developed system.

Early warning system of water resources security is a multi-level and complex system made of many factors. By analyzing current situation of water resources security early warning, operating mechanism of water resources security early warning system is put forward. Logic, time and knowledge related to operating mechanism are discussed. For early warning threshold decision is one of key technologies in water resources security early warning, warning threshold decision and warning degree classification of water resources security early warning are set forth. These methods are systematic method, control chart method, catastrophe theory method and expert decision method. Adopting the water resources security early warning system, situation can be analyzed and predicted promptly and effectively.

A novel fluorine containing epoxy 4-fluoro-4′,4″-diepoxypropoxy triphenyl methane (FDE) was designed and synthesized. The synthesized epoxy was cured by methyl nadic anhydride (MNA) and diglycidyl ether of bisphenol A (DGEBA) was chosen for comparison. Both glass transfer temperature (Tg) and 5% weight loss degradation temperature (Td5%) of cured FDE are over 60°C higher than that of DGEBA. Dielectric constants of the cured FDE at 106 Hz and 107 Hz are 3.09 and 2.91, comparing to 3.50 and 3.24 of the cured DGEBA, respectively. Furthermore, water absorption of the cured FDE is lower than that of DGBEA.

This paper examines the construction of livable environment in TieXi's old Industrial Relocation Area from three aspects, namely, the connotation of livable environment, the strategy and objective of constructing livable environment in TieXi district, and the according specific measures. Then the specific measures will be drawn via qualitative analysis and on-site inspection methods.

The two-degrees-of-freedom of vortex-induced vibration of circular cylinders is numerically simulated with the software ANSYS/CFX. The VIV characteristic, in the two different conditions (A/D=0.07 and A/D=1.0), is analyzed. When A/D is around 0.07, the amplitude ratio of the cylinder’s VIV between in-line and cross-flow direction in the lock-in is lower than that in the lock-out. The in-line frequency is twice of that in cross-flow direction in the lock-out, but in the lock-in, it is the same as that in cross-flow direction and the same as that of lift force. When A/D is around 1.0, the amplitude ratio of the VIV between in-line and cross-flow in the lock-in is obviously larger than that in the lock-out. Both in the lock-in and in the lock-out, the in-line frequency is twice of that in cross-flow direction.

Mechanical compression is a traditional process for the dewatering of sewage sludge. However, the moisture content of the cake is still high, unfavorable for the sludge management. In this paper, the use of thermal compression to improve the sludge dewatering is investigated. The dewatering efficiency is affected by the applied temperature, pressure and the sludge mass. The bound water of the sludge is further reduced by thermal compression, improving the dewatering performance. The solid content of the cake obtained after 10 min mechanical compression and 60 min thermal compression at 120 oC and 4 MPa is 85.2%.

This paper carried out interpolation processing to the groundwater hydrology data of Minqin oasis from 2000 to 2009, via ArcGIS software. Analyzed the result, it was concluded that the distribution rule about spatio-temporal distribution and change of the groundwater depth and mineralization. Using MATLAB the program language, the grey forecasting model was well fitted compared to the time series forecasting model. For the next five years, the groundwater depth and mineralization changes were forecasted, and the author put forward some concrete proposals.

Climate crisis has become the main concern of International community. China is undergoing the quick growing period of urbanization. The fast urbanization inevitably encountered a lot of problems and defects. Our carbon emission occupy more and more percentage of the whole world. To change the traditional way of constructing activity and work towards low-carbon city development mode is the most important task of China city development. From the causes of low carbon cities construction and its significance, this essay focuses on the space structure, traffic mode, land use and landscape architecture framework of constructing a low-carbon city. Low carbon urban construction planning is also presented.

In order to improve control affect of 3-DOF parallel robot, the structure and work principle are presented in brief, control algorithm is introduced in great detail, three controller, which are PID controller , fuzzy logic control and robust control,are established, research of compare experiment show that robust control in hydraulic servo system is better than the other control algorithms.

Nanoparticles have been used with polymer to make composites having remarkable properties. An attempt was made in this direction, in order to enhance the mechanical and tribological properties of nanocomposites. In the paper, the polytetrafluroethylene (PTFE) polymer-based nanocomposites filled with serpentine (SPT) and reinforced with different nanoparticles such as nano-β-carborundum whisker (β-SiCw), nano-copper and nano-TiO2 were prepared by using cold briquetting and hot-press sintering technologies. Also, the mechanical performances of these nanocomposites were studied. The quasi-static tensile experiments and dynamic mechanical thermal analysis (DTMA) were carried out. The results obtained showed that the mechanical properties of these nanocomposites stronger depend on the variety of nanoparticle. Stress-displacement and stress relaxation curves indicate that theses composites are typical viscoelastic materials. These research findings are believed to be helpful for providing practical guide in applications.

The tribological tests were conducted on several PTFE/nano-EG solid self-lubricating composites filled with different nano-particles such as nano-Al2O3, nano-copper, nano-SiO2 and nano-TiO2. The Friction coefficient, wear rate, worn surface morphology and transfer film were studied. It was found that the present filler additions can remarkably increase wear resistance in all composites researched in the paper. The friction coefficients of these composites were lower than that of pure PTFE. The experimental results indicate that the enhancement effect of nano-particles effectively improved anti-friction and wear resistance of these composites. The highest wear resistance was found for composites containing (a) 10%nano-EG+10%Al2O3, (b) 10% nano-EG + 20% nano-Cu and (c) 10%nano-EG+nano-SiO2. Scanning electron microscopy (SEM) and optical microscope (OM) were utilized to examine the worn surface of PTFE-based composite and transfer film generated on counterface. Also, the dominant wear mechanisms and mode of failure were studied.