基于电磁振动与卷积神经网络的玉米品质精选装置

为提高玉米分选自动化水平,针对传统方法特征建模过程繁琐、现有卷积神经网络部署要求高的问题,设计了一种基于电磁振动与卷积神经网络的玉米品质精选分级装置,主要包括玉米粒群落料单元、电磁给料单元、控制单元、分选收集单元和恒定光强视觉单元,可实现玉米粒群自动分离、籽粒自动识别与分选.模型、样机试验结果表明:模型大小仅5.83 MB,对计算机硬件要求低;模型平均检测准确率mAP为88.03%,模型总体分类检测性能良好;模型对优良玉米籽粒的识别能力强,准确率P、召回率R、误报率FPR、加权调和平均值F1分别为98.75%,94.84%,3.78%,96.85%;样机将玉米籽粒的实际检测准确率提升至96.50%,实际有效分选率为97.51%.

智能除草装备苗草模式识别方法研究

精准苗草识别是靶向施药除草装备作业基础。为提高识别算法精度及效率,解决光照变化对识别图像分割精度影响,文章优化研究分割算法,引入加权系数,提高算法光照适应性;根据作物线性分布生长特点,采用烟花智能群体算法,对垄间杂草与作物识别与定位;田间图像采集与试验结果表明,加权分割方法可有效解决光照变化对分割效果影响,实际作物与垄间杂草识别率为98.7%和89.5%,满足苗草识别与导航要求,对导航技术与智能除草装备发展具有重要意义。

开式吸收式热泵超重力旋转填料床吸收器实验研究

研究在高湿烟气水、热回收过程中操作参数对超重力旋转填料床吸收器性能的影响。研究表明,一定范围内增大液气比、超重力因子和进口溶液浓度,降低进口溶液温度可提高潜热回收率（水回收率）。最佳操作参数为进液温度40～50℃,液气比1.0～1.6,超重力因子150～200,溶液质量分数为49%～51%。

Experimental and Theoretical Study of an Internally Cooled Liquid Desiccant Dehumidifier

Liquid desiccant dehumidifiers are useful for simultaneously recovering heat and water from flue gas.Internally cooled dehumidifiers are generally superior to adiabatic dehumidifiers in terms of the consumption of the desiccant and the size of the equipment required.This study examines the performance of a counter-flow dehumidifier through experiments and simulations under different operating conditions,and analyzes the moisture effectiveness and enthalpy effectiveness as performance indices.By applying correlations from the literature,the theoretical model can predict the performance of the dehumidifier within an acceptable range of accuracy.According to the experimental results,droplets were visible at a low desiccant flow rate when the velocity of the gas was above 4.88 m/s.Moreover,a higher cooling ratio and a higher temperature of the solution enhanced the effectiveness of the dehumidification.A temperature cross occurred between the gas and the solution when the mass transfer was sufficiently high,which reflects better heat transfer performance than the conventional convective heat exchanger.

基于共价键结构BMCP热解模型的建立和发展

煤热解过程的模型研究受限于集总方法和经验参数,不能在做出具有一定精度预测的同时辅助对热解过程的机理进行研究。BMCP (boltzmann-monte-carlo-percolation)模型从组成煤的共价键出发,通过对热解过程共价键"解离-生成"机制的描述并结合渗透理论,给出不同条件下不同媒热解过程的共价键变化以及产物分布信息,预测结果与实验结果误差不超过20%;通过对"解离-生成"机制的不同假设,BMCP模型判断出热解过程的速率控制步骤为共价键断裂步骤。此外,通过引入其他方法得到的原理性假设或经验参数,BMCP模型的预测结果还可得到进一步扩展。BMCP模型的建立和发展可为复杂化学反应体系的模型研究提供一种新思路。

Modeling and Experimental Validation on Pressure Drop in a Reverse-flow Cyclone Separator at High Inlet Solid Loading

高海湾的稳固的装载是在高密度传播的气旋隔板的最重要的特征之一使流体化的床(CFB ) 。在这个工作，在反向流动的气旋在压力落下上装载的高固体的效果试验性地被学习。使用的粒子是沙和 -Al2O3。入口固体装载(M) 的一个扩大范围，空气的 solids/ kg 的多达 30 kg 在不同入口空气速度(V in=1624 m/s ) 被测试，很好，在装载的固体以外，范围以前报导了。当时，实验证明在稳固的装载的测试范围，气旋压力落下与增加稳固的装载戏剧性地减少了 M < 7.5 kg/kg 然后几乎仍然是的常数。为预言气旋压力落下的一个新半实验的模型也被开发。计算、试验性的结果为粒子显示出好同意免费流动和粒子沉重的流动。

MILD Combustion for Hydrogen and Syngas at Elevated Pressures

As gas recirculation constitutes a fundamental condition for the realization of MILD combustion, it is necessary to determine gas recirculation ratio before designing MILD combustor. MILD combustion model with gas recirculation was used in this simulation work to evaluate the effect of fuel type and pressure on threshold gas recirculation ratio of MILD mode. Ignition delay time is also an important design parameter for gas turbine combustor, this parameter is kinetically studied to analyze the effect of pressure on MILD mixture ignition. Threshold gas recirculation ratio of hydrogen MILD combustion changes slightly and is nearly equal to that of 10 MJ/Nm3syngas in the pressure range of 1-19 atm, under the conditions of 298 K fresh reactant temperature and 1373 K exhaust gas temperature, indicating that MILD regime is fuel flexible. Ignition delay calculation results show that pressure has a negative effect on ignition delay time of 10 MJ/Nm3syngas MILD mixture, because OH mole fraction in MILD mixture drops down as pressure increases, resulting in the delay of the oxidation process.

Experimental and Numerical Study of the Effect of Fuel/Air Mixing Modes on NO_(x) and CO Emissions of MILD Combustion in a Boiler Burner

The Moderate or Intense Low-oxygen Dilution (MILD) combustion is characterized by low emissions,stable combustion and low noise for various kinds of fuel,which has great potential in the industry.The aim of this study is to investigate the effect of fuel/air mixing modes on NO_(x) and CO emissions of MILD combustion in a boiler burner by experiments and numerical simulations.Three types of fuel/air mixing modes (premixing mode,diffusion mode and hybrid mode) have been considered in this study.The realizable k-ε turbulent model and the Eddy Dissipation Concept (EDC) combustion model were used in numerical simulations.In addition to the temperature near the burner head,the calculation results match very well with the axial temperature distribution at the furnace center.The flow pattern under different mixing modes is similar,while the hybrid mode has a higher OH concentration near the diffusive fuel nozzle than the premixing mode,and the corresponding position of the peak OH concentration is closer to the rear half of the furnace.The distribution of temperature is extremely uniform for the premixing mode in the main reactive zone,which is typical for MILD combustion.There is a distinct area where the reaction temperature is higher than 1600 K for the hybrid mode.Moreover,in the main reactive zone,the gas recirculation ratio is high enough to ensure flue gas recirculation,which is beneficial to achieve MILD combustion at local areas.At the location where the axial distance is greater than 0.2 m,the gas recirculation ratio of the premixing mode is larger than that of the hybrid mode,which strengthens the entrainment of hot flue gas into the recirculated gas.The experimental results show that when the thermal intensity is less than 1.67 MW·m^(-3),the NO_(x) emissions are less than 15× 10^(-6)@3.5%O_(2) in near stoichiometric ratio in the premixing mode,and the CO emissions are less than 10× 10^(-6)@3.5%O2 under the same conditions.In the diffusion mode,the NO_(x) emissions are less than 30×10^(-6)@3.5%O_(2).In order to keep NO_(x) and CO emissions low,the hybrid modes with optimized fuel distribution ratio are found under different thermal intensities.

Experimental Study of Falling-film Mode Transitions between Horizontal Tubes in CaCl_2/Water Absorber

It is important to accurately predict the flow mode especially intertube falling-film mode of absorbent for its great impact on the heat and mass transfer in a horizontal tube absorber. In this paper, a test facility used to study falling-film outside horizontal tubes was built, and experiments were conducted to explore the intertube mode transitions with water-calcium chloride(CaCl2/water) solution in quiescent surroundings. The correlations which are more suitable for predicting CaCl2/water solution intertube mode transitions were developed. In general, the transitional Re will decrease with the solution concentration increasing, and its effects increase with the transitions from droplet mode to sheet mode. Hysteresis exists in all the mode transitions, and it is more obvious for low concentration solutions. The results may be an important support for modeling, designing and operating of CaCl2/water falling-film absorber.

Influence of Solids Circulation Flux on Coal Gasification Process in a Pressurized High-density Circulating Fluidized Bed

The coal gasification behaviors in the pressurized high-density circulating fluidized bed under various solids circulation fluxes were studied with the CFD method, which combines the two-fluid model and coal gasification reactions represented by the chemical percolation devolatilization and the MGAS models. The numerical method was validated with two experimental cases, and detailed distributions of gas species and temperature in the riser were illustrated to understand the gasification process. To fully understand the influence of solids circulation flux on the gasification behavior, a series of cases were simulated with the solids flux varying gradually from 260 to 1010 kg/m^2 s, and the composition and quality of syngas were compared between various cases. The higher heating value of syngas firstly increased and then decreased with the increase of solids flux, and it reached the highest value around 480 kg/m^2 s. The influence of solids flux on gasification process was further analyzed through the contours of temperature, solids concentration, and gas composition in the riser.

Synergistic Effect of Alkali Metals in Coal and Introduced CaO during Steam Gasification

The steam gasification kinetics of Zhundong raw coal and the washed coal by deionized water or hydrochloric acid with/without addition of CaO were tested by thermogravimetric analyzer(TGA)at medium temperatures(650℃ to 800℃).The cation contents of potassium and sodium in samples were determined by Inductively Coupled Plasma Optical Emission Spectrometer(ICP-OES).The Brunauer-Emmett-Teller(BET)surface area of the samples was tested by N2 adsorption,and the morphologies of the samples were characterized by scanning electron microscopy(SEM).Experimental results showed that the organic sodium was the main catalyst for the gasification of the pyrolysis char,and the gasification rate of the char could be enhanced further with the introduction of CaO.The inherent alkali metals in coal and the introduced CaO showed a synergistic effect that occurred obviously above 735℃.The char conversion curves with or without CaO were fitted by the modified volumetric model(MVM).The calculated results indicated that the addition of CaO increased the pre-exponential factor obviously,but made little changes on the activation energy.It was proposed that the synergistic effect was resulted from the co-melting of the sodium and CaO,which facilitated the migration of the catalyst ions and the generation of C(O)intermediates for the gasification.