蔬菜工厂监控系统研究与实现

积分球内部的直插式灯座既不适用于铝基板式LED光源的安装,也不能满足功率型LED光源的散热要求.针对这一问题,通过三维软件为积分球设计一种通用的外接灯座,利用ANSYS软件的热分析模块,对该灯座加载模拟的最大设计热载荷并进行热稳态仿真分析,以得到整个灯座的模拟温度场分布.然后利用ANSYS软件的多目标驱动优化分析工具,对灯座模拟温度场中的最高温度点(区域)进行结构优化设计,以降低灯座的最高温度.最后在实验条件下,调节程控直流电源,加载最大设计电功率,验证热稳态下整个灯座的实际温度分布,并与仿真进行比较.结果表明,实验得到的灯座温度场分布与仿真得到的温度场分布十分接近,经优化后的灯座最高温度明显降低.     

An effective thermal conductivity model for unsaturated compacted bentonites with consideration of bimodal shape of pore size distribution

An effective thermal conductivity model was proposed for unsaturated compacted bentonites with consideration of the bimodal shape of pore size distribution curves.The pores of soils were grouped into two dominant pore size modes corresponding to the intra-and inter-particle pores,and were simulated with randomly distributed spheroidal inclusions of different aspect ratios.With the assumption of preferential invasion of the wetting fluid(water)into pores of smaller sizes and by virtue of the analytical solution to the inhomogeneous inclusion problem in heat conduction,the model was developed using the Mori-Tanaka(MT),Ponte Casta?eda-Willis(PCW)and self-consistent(SC)homogenization approaches for different considerations of the interactions between pores and the solid phase.The proposed model is functions of the thermal conductivities of the solid,liquid and gas phases,porosity,the degree of saturation,the aspect ratios of pores and/or soil particles,and the fraction of the smaller group of pores.The proposed model was validated against five sets of laboratory measurement data on the MX-80,FEBEX,Kunigel-V1 and GMZ01 bentonites,showing a good agreement between the model predictions and the laboratory measurements.The responses of the model with respect to the geometries of pores and solid particles were examined.Compared to series-parallel structural models,the proposed model may overall exhibit better performance if proper homogenization schemes are adopted,but as an advantage,the model has clearer physical mechanisms and a smaller number of parameters.     

Study on implicit composite element method for seepage analysis in underground engineering

Based on the basic principle of the finite element method, the implicit composite element method for numerical simulation of seepage in underground engineering is proposed. In the simulation, the faults and drainage holes are set implicitly in the model elements without adding additional elements. Elements containing fault or drainage-hole data are termed composite elements. Then, their information data in model could be obtained. By determining the osmotic transmission matrix of the composite elements, the permeability coefficient matrix is then obtained. The method was applied to the numerical simulation of the seepage field around the underground powerhouse of the Ganhe Pumping Station in Yunnan, China, using a compiled three-dimensional finite element method calculation program. The rock mass around the site includes two faults. The seepage field in the rock mass was analyzed at different stages of the engineering project. The results show that, before the excavation of the underground caverns, the rock mass seepage is affected by the faults and the groundwater permeated down along the tangential fault plane. After the excavation of the caverns during the operation period, the groundwater is basically drained away and the underground caverns are mostly above the groundwater level. Thus, the calculation results of the engineering example verify the implicit composite method for the simulation of faults and drainage holes. This method can well meet the calculation demands of practical engineering.     

EMD滤波方法在NMR测井中的应用

核磁共振测井中,回波信号的信噪比对T2谱反演及后续地层解释评价过程有重要影响。基于核磁共振测井信号与噪声的分析,提出了一种采用自适应性较强的经验模态分解（ EMD）算法对核磁共振测井原始数据作消噪处理。结果表明,采用该滤波算法,实验室回波数据信噪比由22 dB提高到46 dB,标准油井回波数据信噪比由11 dB提高到31 dB,反演得到的T2分布更加精确,多次重复测量中孔隙度结果有较高的一致性。     

带悬吊质量结构的多维地震反应

为了研究带悬吊质量结构体系在地震动水平-竖向-摇摆耦合作用下的动力效应,推导了地震动水平-竖向-摇摆耦合作用下带悬吊质量结构体系的动力方程,提出一种改进的摇摆分量时程获取方法,并以某带悬吊质量阀厅结构为原型,进行1∶10缩尺模型振动台试验,探讨采用不同长度的钢索和弹簧悬吊质量时,结构在水平-竖向、摇摆-竖向和水平-竖向-摇摆耦合地震动作用下的地震效应．结果表明:相较于水平地震动作用下,悬吊质量对摇摆地震动作用下主体结构的减震效果更加显著;随着钢索或弹簧长度增加,悬吊质量对主体结构的减震效果降低;将拉索由钢索改为同等长度的弹簧后,结构顶层的加速度响应和位移响应变化不大,但拉索动拉力却明显减小,当采用悬吊质量作为质量摆减震系统时,拉索应尽量采用弹簧或拉压刚度较低的构件．     

Analysis and characterization of orientation structure of pre-oxidized PAN fibers in high magnetic fields

PAN fibers pre-oxidized at 240 ℃, 260 ℃, 280 ℃, 300 ℃ were treated in 8 T, 12 T, 16 T high magnetic fields, respectively. The experimental result implied that there were two kinds of magnetic units cyan and carbon-nitrogen heterocycle in pre-oxidized PAN fibers, and the movement of magnetic units resulted in changes of orientation structure of pre-oxidized PAN fibers in high magnetic fields. Overall orientation increased with increase of magnetic field intensity and extension of processing time, whereas change of crystalline orientation depended on magnetic field intensity and content of carbon-nitrogen heterocycle due to the competition of two magnetic units. Furthermore, magnetic fields induced the conversion from amorphous region to crystal region and improved crystalline properties of pre-oxidized PAN fibers.     

Synthesis and characterization of CePO4 nanorods via solvothermal process

One-dimensional cerium phosphate(CePO4) nanorods were successfully synthesized by a facile and simple solvothermal method at 150 ℃ for 12 h, using Ce(NO3)3·6H2O and NaH2PO4·2H2O as the starting materials. Phase and morphologie of the as-synthesized CePO4 products, characterized by XRD, FESEM, and TEM, were proved to be perfect and uniform hexagonal CePO4 nanorods with aspect ratio of more than 100. The photoluminescence(PL) spectrometer was used to investigate the optical properties of the assynthesized hexagonal CePO4 nanorods.     

Periodontal ligament cells cultured on the tricalcium phosphate/chitosan scaffolds in vivo and in vitro

To search suitable scaffolds for periodontal tissue regeneration, different ratios of tricalcium phosphate/chitosan(TCP/chitosan) scaffolds were prepared through a freeze-drying process. Human periodontal ligament cells(HPLCs) were incubated on the scaffolds in vitro. Cells were cultured on the scaffolds, detected by scanning electron microscopy (SEM). HPLCs were analyzed by MTT assay and alkaline phosphatase(ALP) activity detection. HPLCs were seeded onto the scaffolds. Then these scaffolds with HPLCs were implanted subcutaneously into athymic mice. The state of periodontal tissue regeneration was detected after 4 weeks. As the ratio of TCP increased, TCP/chitosan scaffolds accelerated HPLCs proliferation significantly higher than the pure chitosan scaffold. HPLCs produced the cementoid tissue in vivo. The periodontal tissue regeneration engineering is able to be applied with TCP/chitosan scaffolds.     

Growth characteristics and kinetics of niobium carbide coating obtained on AISI 52100 by thermal-reactive diffusion technique

Niobium carbide coating was produced by thermal-reactive diffusion technique on AISI 52100 steel in salt bath at 1 123 K, 1 173 K, and 1 223 K for 1, 2, 4, and 6 hours. The salt consisted of borax, sodium fl uoride, boron carbide, and niobium pentoxide. The presence of NbC phase on the steel surface was confi rmed by X-ray diffraction analysis. Microscopic observation showed that niobium carbide coating formed on the substrate was smooth and compact. There was a distinct and fl at interface between the coating and substrate. The micro-hardness of niobium carbide coating was 2892±145HV. The thickness of coating ranged from 1.6 μm to 14μm. The forming kinetics of niobium carbide coating was revealed. Moreover, a contour diagram derived from experimental data was graphed for correct selection of process parameters. Some mathematical equations were built for predicting the coating thickness with predetermined processing temperature and time. The results showed that these mathematical equations are very practical as well as the kinetics equation.     

A Novel Fluorescence Probe 9-（4-（1,2-diamine）benzeneN 1-phenyl）acridine for Nitric Oxide Determination

A novel fluorescent probe 9-(4-(1,2-diamine)benzene-N1-phenyl)acridine(DABPA) was synthesized for the detection of nitric oxide(NO) and characterized by IR, 1H-NMR and EI-MS spectroscopy. Based on a photoelectron transfer mechanism, the fl uorescence intensities of DABPA were investigated with the different concentrations of NO. Under the optimal experimental conditions, the fl uorescence intensity of DABPA had a good linear relationship(R2=0.9977) with NO concentration in the range from 1×10-7 to 1.5×10-6 mol/L with a detection limit of 1×10-8 mol/L. The cytotoxicity induced by DABPA was evaluated by the MTT(3-(4,5-dimethylthiazol-2-yl)-2,5diphenyl tetrazolium bromide) assay for biological application. Furthermore, the probe DABPA had also been successfully applied to real-time image NO produced in PC12 cells in the presence of L-arginine.