Performance of A Sludge Reduction System on Removal of Nitrogen and Phosphorous Controlled by Low Dissolved Oxygen

The influences of dissolved oxygen (DO) on the removal process of nitrogen and phosphorous in a sludge reduction system had been studied by controlling aeration amounts. It was found that under the conditions of low doses of 2,4,5trichlorophenol (TCP), endogenous sour values of activated sludge increased with the extension of low DO state duration in SBR system and the decrease of cyclic average DO, which led to a low DO environment favored the formation of simultaneous nitrification and denitrification(SND).TCP concentration was recommended as 2mg / L and cyclic average DO value in SBR system was kept at 2mg / L based on the impacts of TCP concentration on sludge reduction, removal of nitrogen and phosphorous and sludge performance. Compared with the control system, aeration amounts increased by 23% and the discharge of excess sludge decreased by 34.6%. The water quality in effluents was equivalent in the aeration sludge reduction system with 2mg/LTCP, which met the discharge standards. Therefore, it was indicated that the removal of nitrogen and phosphorous and sludge reduction can obtain excellent performance in TCP system under low DO state with removing Phosphrous rich sewage.     

Fire and explosion hazard analysis of the urea synthesisproduction process

On the basis of identifying and analyzing harmful risk factors in the urea synthesis production process of a factory, the production process is assessed and analyzed using the Dow chemical company fire and explosion index method. The related indexes are f     

Dynamic responses of ultra high voltage transmission line ice shedding

Numerical models of typical 500 kV ultra high voltage (UHV) transmission lines are set up in ABAQUS/CAE software. The dynamic response of the transmission lines with different structure parameters under various ice shedding load cases are analyzed, and th     

Hybrid field network simulation of temperature in a building fire

A connecting platform between the field model and network model has been constructed, based on a multi functional building model. The field model is used to simulate the fire smoke in certain special compartments (the fire room and specific large space rooms), while the network model is used to simulate the uniform compartments. When combining the simulation results of the field model and network model as the interface boundary conditions for the each other, a hybrid field and network model is presented. The hybrid field network model can provide more detailed physical information of the fire smoke properties under a specific fire scenario for the specially confined compartments. In addition, the hybrid model can predict the fire smoke flow properties in the building accurately.     

Simulation and analysis of all terrain vehicle ride comfort

A multi rigid body dynamic model of an all terrain vehicle (ATV) is established in MSC.ADAMS. The model takes into consideration the body, suspension, frame and the steering system. According to the method of superposition of harmonic wave, a Grade B road file is created in ADAMS for the riding comfort test. The engine excitation is analyzed. The infliction for engine excitation to ADAMS is achieved. The ATV ride comfort simulation is carried out with the excitation of the engine, and the seat vibration is evaluated using an evaluation method programmed via MATLAB. It has laid a good foundation for further analysis.     

Performance analysis and comparison of IEEE 802.11 distributed coordination function and improved schemes

To improve the media access control mechanism and enhance the performance of large scale wireless LANs, the distributed coordination function of IEEE802.11 standard and two typical improved schemes are studied extensively. Compared with the distributed coordination function, the fast collision resolution mechanism greatly enhances the throughput, but deteriorates the delay jitter and fairness of wireless LANs. The new self adaptive distributed coordination function markedly improves the delay jitter and fairness performance, while enhancing the throughput of wireless LANs to a certain degree. Hence, with further improvement, the new self adaptive distributed coordination function is more suitable for large scale wireless LANs for multimedia information transmission.     

Design and application of hospital service info structurebased on medical knowledge flow

To counter deficient medical knowledge sharing and the low efficiency cooperative diagnosis between doctors, the knowledge flow from knowledge management (KM), knowledge acquisition and knowledge supply are established as the core info structure of a hospital KM model. This is done by combining heavy idea exchange, frequent updating, and intensive use of the medical knowledge. Three important knowledge flow(KF) operations (knowledge refreshing, knowledge migration and knowledge expansion) are proposed. By comparing hospital information management with hospital KM, a hospital KM method based on knowledge flow is constructed. The method emphasizes tracking, monitoring and controlling hospital wide comprehensive process of medical knowledge. A specific clinical diagnosis instance is given for detailed healthcare knowledge flow analysis.      

Generalized conforming quadrilateral membrane element with vertex rotational freedom

A new generalized conforming quadrilateral membrane element is developed by introducing additional rigid vertex rotational freedoms to the normal 4 node quadrilateral membrane element. The rotational stiffness of the present element is not zero so that the singularity of the stiffness matrix is avoided. Numerical analysis of the Cook problem cantilever beam shows that the EAE/Mem element passes the patch test and possesses good convergence, reliability, and precision without a zero energy mode. It provides a lock free solution to the MacNeal beam problem. Numerical results also show that the EAE/Mem element is insensitive to mesh distortion. The results demonstrate that the generalized conforming technique is an efficient tool for developing high performance finite element models.     

A mathematical description of the liquid flows inside blast furnaces

The knowledge of liquid flows in blast furnaces may play an important role in controlling the blast furnace process. Appropriate assumptions are given to represent the main characteristics of the liquid flow in blast furnaces, such as liquid streams being composed of unwetting liquid droplets, inertial force having little effect on the liquid flows, and mass exchange existing along the direction perpendicular to liquid flow. A mathematical model is built to predict the distribution of the liquid flow rate and the liquid flow range in packed beds. The scale of the numerical grid used to solve this model may not necessarily be reduced to the particle level. The predicted results of this model accord well with the observed data. This model is an alternative theory for the simulation of blast furnaces     

Stability of a nonlinear red tide dynamic model in a polluted environment

We develop a nonlinear red tide dynamic model to study the effect on a system of two harmful phytoplankton and zooplankton and of a toxicant emitted into the environment from external sources and a toxin excreted by phytoplankton. We use modern nonlinear dynamics to discuss stability and bifurcation, and obtain the thresholds of persistence and extinction for each species. Numerical simulations are used to validate the theoretical results. The results show that a sequence of Hopf bifurcations occur at the interior equilibrium as the delay increases or the growth rates increase.