机械加工过程中神经网络最优自适能力的控制研究

通过本次研究设计机械加工过程的最优自适合控制板型。本文提出了工程器械磨耗的神经网络测量的一个途径,并把机械加工过程的最优自适合扼制板型对应到神经网络优化电路板型中,设计出机械加工过程的神经网络最优自适合扼制系统。在机械加工过程中,期望在保障加工品质的同时,减低加工成本和增长出产率,机床和刃具经过测试被确认时,关键就在于确认最优的磨削用量,因为机械加工过程的最优自适合扼制引起了人们广泛的研究。     

增压锅炉烟气发生器燃烧流场与污染排放数值分析

为了考察设计方案中增压锅炉烟气发生器的阻力大小及流场条件能否满足系统设计要求,采用FLUENT程序,对增压锅炉烟气发生器设计结构方案的燃烧流场及阻力进行了数值分析,同时考察了发生器的污染物排放性能。数值模拟时采用了RNGk-ε湍流模型、P-1辐射模型、液体燃料喷雾燃烧过程的颗粒轨道模型和PDF燃烧模型,对设计方案的压力场、温度场及NOx排放进行分析,得到了设计方案的阻力特性、温度分布和排污特性。结论表明:该方案的阻力大小及出口温度能够满足设计要求。该工作为优化烟气发生器结构和污染控制具有重要的指导意义。     

锅炉的强化燃烧

分析锅炉的燃烧,阐释强化燃烧的原理,说明提高燃烧的效率的方法。     

神经网络在锅炉燃烧控制中的应用

锅炉燃烧过程的控制是火电厂最重要的过程控制。本文在采用MPIDNN神经网络控制方案基础上,以现场运行数据为依据,在不同负荷下,利用了MATLAB软件对锅炉燃烧系统进行仿真研究。经过建模仿真得出的数据综合分析,结果表明,MPIDNN神经网络在锅炉燃烧系统应用上有一定价值。     

Computation of a tetrahedral mesh for striated muscle deformation simulation

Competing concepts exist regarding surgery for instance of the cleft lip and palate to date. Morphology‐based simulations at histological scale may one day be used to help the surgeon predict the possible outcome of a variety of approaches. It however can be a challenge to generate volume meshes that are applicable to the mathematical modelling of three‐dimensional spatial modifications. Computation of surface meshes may be considered less delicate. The aim of this study is to design and evaluate a novel algorithm that supports finite element methods. Images of histological serial sections of a striated muscle were segmented. Results of the three‐dimensional reconstruction of multiple layers of the polygonal segmentation data characterized the hull of the muscle. The corresponding surface mesh was then converted into a tetrahedral mesh to generate volume. This was achieved by mapping multiple template types onto neighbouring intersection polygons. Muscle contraction was subsequently simulated by mesh deformation. The technique successfully generated volumes and was able to provide data on contraction directions. The mesh supported a novel approach to simulate representations of contraction. However, several drawbacks were evident. Mathematical modelling of scenarios with more than one striated muscle will require considerable modification of the currently presented approach. Future studies need to then evaluate the applicability of volume meshes to represent arrays of three‐dimensional biological objects. Surface mesh based mathematical modelling of cleft lip and palate surgery and its results are therefore not yet in reach.     

Oxy-fuel combustion boiler for CO2 capturing: 50 kW-class model test and numerical simulation

A novel oxy-fuel burner was devised and integrated into a 50 kW-class furnace-type boiler system. A series of experiments was conducted to verify its feasibility for industrial applications. Additionally, numerical simulations were performed and the results validated against experimental data on the detailed physics inside the conventional-design combustion chamber. The oxy-fuel burner, with the help of gas radiation, could effectively heat the combustion chamber. The composition of the exhaust gas revealed that the sealing of the system is crucial to the achievement of high CO₂ concentrations and low NOx emissions.     

CFD investigation of NOx reduction with a flue-gas internal recirculation burner in a mid-sized boiler

The demand for reduction of nitrogen oxide (NO_x) emissions from industrial facilities continuously increases, and considerable efforts have been exerted to achieve this goal. In this work, we propose a novel flue-gas internal recirculation (FIR) burner emphasizing the function of FIR to accomplish single-digit NO_x emissions from a mid-/large-sized combustion system. In the new design, a FIR passage is installed inside the conventional non-FIR burner to draw back the flue gas from the combustion chamber and release it into the chamber as a mixture of air and flue gas. The effectiveness of FIR burner is evaluated by employing extensive computational fluid dynamics (CFD) simulations with an enhanced reaction rate model. The existing eddy dissipation model for reaction rate, including the turbulence-chemical interaction, is improved by introducing a position-dependent scaling factor, which is validated by comparison with temperature profiles in experiments. CFD predictions show that a small amount of flue gas returned to the burner still significantly alters the flow structure and temperature distribution. Accordingly, NO_x emission is dramatically diminished (82.83 and 9.7 ppm in the non-FIR and FIR systems, respectively) using the FIR burner. These observations confirm that the new FIR burner effectively accomplishes ultra-low NO_x emissions in field-scale combustion systems. In addition, the fundamentals of NO_x reduction by the FIR burner are thoroughly examined in the present study. The findings will provide essential knowledge in designing other ultra-low NO_x burners.

     

模糊神经网络在链条炉燃烧过程中的应用

本文介绍了基于模糊神经网络控制实现链条炉的优化燃烧。同时利用改进的BP算法,对神经网络的各参数进行离线训练。利用人工神经网络的记忆特性,对链条炉的优化燃烧进行在线控制。     

Large eddy simulation of two-phase reacting turbulent flow in a pilot-scale pulverized coal combustion furnace with flamelet model

Journal of Mechanical Science and Technology - A three-dimensional numerical simulation was performed to investigate the physics and combustion characteristics of a two-phase reacting turbulent...     

锅炉供煤系统筛分设备的改进

通过对锅炉供煤系统试运行的改进,完善了供煤系统的关键设备。     

一种改进PSO-LSSVM算法在锅炉燃烧优化中的应用

为了实现锅炉高效低NOX排放,提出一种LSSVM建模和改进PSO算法结合的方法实现锅炉燃烧多目标优化。首先采用LSSVM算法建立了锅炉效率和NOX排放等相关特性模型,并针对PSO算法在飞行后期易失去粒子多样性的不足及过早收敛于局部最优值的问题,采用一种改进的PSO算法。优化结果表明,改进的PSO算法与LSSVM结合可有效的实现多目标寻优,在保证锅炉效率的同时降低NOX排放,找到最佳的送风调节系统的设定值,给出一种可行的各风门开度等操作量的优化调整方案。     

煤燃烧特性综合测试仪的研制

介绍了自制的煤燃烧特性综合测试议的测量原理、仪器组成及测量方法。该测试仪由燃烧炉、温度控制器、气氛气动控制系统、热天平、气体测量仪、微计算机系统组成。采用稳态测量方法测量煤的着火温度、燃尽时间及工业分析值 ,用计算机进行数据处理和分析 ,对煤质作出基本评价 ,为合理用煤提供科学依据。     

工业锅炉燃烧系统的分级智能控制

针对工业锅炉燃烧过程的复杂性和控制难点，提出采用分层递阶智能控制方案，以实现燃烧系统长期自动、稳定优化运行。     

并列运行锅炉燃烧自动控制系统的分析和研究

本文对母管制并列运行锅炉燃烧自动控制系统进行了详细地分析和研究,提出了一种并列运行锅炉燃烧自动控制系统。理论分析表明该控制系统正确合理,具有一定的实用价值。     

轮胎式压路机消声器的CFD模拟探究

首先采用计算流体动力学(CFD)软件数值模拟了某一算例消声器的内部流场,然后将软件数值模拟的结果与实验数据进行了比对,验证了该做法的可靠性.在此基础上,用同样的数值模拟计算方法研究某型号轮胎式压路机的消声器压力损失的影响,得到该压路机消声器的压力损失的影响规律,为该型号压路机的消声器结构设计和性能改进提供理论依据.     

Dynamic simulation of a circulating fluidized bed boiler system Part II: Simulation of a boiler system operating in a power plant

A case of dynamic performance simulation model of a CFB boiler is presented in this study. The dynamic system of a CFB boiler in an operating power plant and the transient behavior of sub-models is described in the accompanying paper, Part I. The current paper, Part II, describes the model extension for the CFB boiler system in a power plant. The open loop model in Paper I was expanded by applying a set of PID (Proportional-integral-differential) control loops. In the control loop, pressure, temperature, mass flow rate of the main steam, the drum water level and the oxygen level at the stack were controlled. Dynamic performance was simulated to check the response of the closed control loop. Finally, performance of the total boiler system for a range of operation load of the power plant was simulated, where the parameters were calculated and control variables were maintained at the set values by PID control. Dynamic performance of a boiler at a selected load variation case was simulated and compared with actual measurements and their transient response characteristics were discussed. The simulation can also directly produce useful operation parameters, which are not measurable, but could be used for engineering evaluation.

     

Numerical simulation of turbulent flow in the suction chamber of a gearpump using deforming mesh and mesh replacement

The flow in the suction chamber of an external gearpump is numerically analysed. The evolution of the boundaries of the domain is very complex, and an arbitrary Lagrangian-Eulerian (ALE) formulation is used with mesh deformation and local remeshing. Nevertheless, a mesh replacement strategy is also adopted in order to avoid skewed meshes and allow for simulation of solid contact between gears. This process approximates a more realistic flow behaviour when the working pressure is larger than 10 bar, which is an important in fluid power systems where the pressure is usually greater than 100 bar.Aside from the laminar model, which fails as a result of the vortex configuration in the suction chamber, Standard k-ε, RNG k-ε, Realizable k-ε and Reynolds Stress Models (RSM) are tested. The numerical flow is compared with experimental data obtained with Time Resolved Particle Image Velocimetry. Although all of the models failed in some respect, the RSM and RNG k-ε were the best choice provided its behaviour close to the gearing zone and general shape of the vortex distribution.     

锅炉送粉管道煤粉浓度的电容层析成像测量方法研究

锅炉燃烧过程中,准确测量各风管中的煤粉浓度并指导调节对锅炉的安全、经济运行非常重要.采用电容层析成像技术(ECT),对常温下锅炉煤粉气力输送的固体浓度进行了测试研究.为克服电容传感器敏感场的不均匀性对成像造成的影响,实验系统中装置了一个旋风分离装置,通过旋风分离作用将固体颗粒主要集中在壁面区域,传感器电极布置在分离器直管上.这种测试方法的优点在于不破坏原有系统的运行特性,属于非侵入式、在线的快速测试技术.通过搭建实验台及相应的在线测量系统,并对不同浓度工况进行测量及对比分析,实验结果证明了该测量方法的可行性及可靠性.     

组合型线涡旋压缩机压缩腔流体的CFD模拟

根据已被理论验证过的一种复杂的圆渐开线-高次曲线-圆弧组合涡旋型线的数学模型,利用MATLAB和CAD软件建立了该组合涡旋型线的计算模型并采用CFD软件对其进行模拟计算,得到其压力损失以及流场特性,为进一步研究涡旋压缩机的组合涡旋型线提供参考.