高弹性顶杆式带锯机张紧系统时滞确定的计算机仿真研究(1)

本文通过对高弹性顶杆式带锯机张紧系统时滞状态方程的分析，得出了确定带锯机张紧系统时滞的有效方法，并运用MATLAB软件进行了计算机仿真，为实际理论研究奠定了初步基础，所提供的方法对于今后进行该方面问题的研究提供了一种新的思路。     

带锯机高弹性顶杆式张紧系统系统辨识的研究

本文通过对东北林业大学机电工程学院木工机械实验室的MJ317型细木工带锯机振动情况进行计算机采集数据，并对其分析，运用MATLAB系统辨识工具箱对其模型特征参数进行了仿真分析，为今后有关研究奠定了基础。     

带锯机高弹性顶杆式张紧系统系统辩识的研究

本文通过对东北林业大学机电工程学院木工机械实验室的MJ317型细木工带锯机振动情况进行计算机采集数据,并对其分析,运用MATLAB系统辩识工具箱对其模型特征参数进行了仿真分析,为今后有关研究奠定了基础。     

弹簧刚度对木工带锯机弹性挺杆式张紧系统反应时滞影响的实验研究

利用改进设计的弹性挺杆式张紧系统取代原有的杠杆压砣式张紧系统,在空载的情况下,进行了关键部位振动的测试,获得了弹簧刚度对木工带锯机弹性挺杆式张紧系统反应时滞影响的规律     

带锯机杠杆压砣式张紧系统振动的分析

本文通过对带锯机杠杆压砣式张紧系统振动的实验，运用DASP6．53分析系统进行了分析，为改善带锯机的动态特性提供了依据。     

带锯机张紧杠杆位置与张紧力关系的再研究

本文主要通过理论分析和张紧力模拟系统验证，来研究在重锤杠杆式张紧机构中，杠杆空间位置状态与张紧力的变化关系。首先建立了重锤杠杆式张紧机构的张紧力数学模型。通过数学模型的分析可知，杠杆位置在水平以下向水平位置移动的过程中张紧力呈增大趋势。并在水平位置处张紧力达到最大。在水平位置以上移动时张紧力呈逐渐减小的趋势。然后进行了实验，实验结果证明了理论分析是正确的。从而为合理确定重锤杠杆的初始位置，提高切削精度和加工质量。减小切削损失提供了理论依据。     

带锯机板式弹簧张紧系统锯条横向振动的研究

本文运用先进的DASP6．53型大容量数据采集分析测试系统测试并分析了带锯机板式弹簧张紧系统锯条的横向振动，验证了运用板式弹簧张紧系统对于减小锯条振动量具有较大的作用，从而为今后进一步开发具有实效的新型张紧系统奠定了基础。     

杠杆压砣式张紧系统数学模型的研究

本文通过对杠杆压砣式张紧系统部件工作的分析及研究，运用现代控制理论建立了经紧系统的数学模型，为今后进一步研究张紧系统的动态力学特性奠定了基础。     

Development of a computer simulation model for processing food in a microwave assisted thermal sterilization (MATS) system

The microwave assisted thermal sterilization computer simulation model (MATS-CSM) was developed to improve the previous computer simulation model for the microwave assisted thermal sterilization (MATS) system. Development of the new MATS-CSM included determination of optimum heating time step, evaluation of electromagnetic field distribution and the resulting heating pattern in food, and experimental validation of heating patterns. It was determined that the minimum number of discretization that would not cause immediate divergence of the EM-heat transfer solution was 32 steps corresponding to 97 mm and 5.6 s of displacement and heating time for every step, respectively. Furthermore, this study successfully demonstrated the symmetrical electromagnetic field distribution between top and bottom microwave entry ports and a staggered electric field pattern from one cavity of the MATS to the next. In addition, MATS-CSM confirmed that incorporating heat diffusion in the simulation model reduces the difference in hot spot and cold spot temperature by 65%. It also confirmed that water circulation reduces the edge heating effect, as observed in experiments. The heating pattern generated by MATS-CSM was verified experimentally through a chemical marker method. Based on the percent areal cross section of the weighted average temperature, there were no noticeable differences between the heating zones generated by the MATS-CSM and by the chemical marker method. The percent areal cross section of the cold area 1, cold area 2, and hot area by MATS-CSM were 35%, 25%, and 40%, respectively, and the cold area 1, cold area 2, and hot area by chemical marker method were 35%, 30%, and 35%, respectively.     

高效液相色谱法测定纺织品中三氯生的研究

通过研究色谱条件、萃取条件及方法的测定底限、回收率、重复性等,确定了利用高效液相色谱法测定纺织品中三氯生含量的最佳测试方法,即检测波长为282 nm,萃取溶剂为甲醇,萃取溶剂体积为25 mL,萃取时间为30 min.该方法在0.1~100 mg/L的线性相关系数r=0.999 8,检测底限为1 mg/kg,回收率为86%~103%.     

离子缔合体系测定痕量硒(Ⅳ)的研究与应用

在吐温-60存在下,研究了硒(Ⅳ)与硫氰酸钾和乙基罗丹明B形成的三元离子缔合物的吸收光谱特性,最大吸收峰为605nm,表观摩尔吸光系数ε605=1.50×106L/mol·cm,硒(Ⅳ)浓度在0.0~2.0μg/25mL范围内符合比耳定律。用巯基棉富集分离干扰离子,测定了水样和食品中痕量硒,结果满意。     

Use of sensitivity analysis to aid interpretation of a probabilistic Bacillus cereus spore lag time model applied to heat-treated chilled foods (REPFEDs)

The microbiological safety and quality of REfrigerated Processed Foods of Extended Durability (REPFEDs) relies on a combination of mild heat treatment and refrigeration, sometimes in combination with other inhibitory agents that are not effective when used alone. In this context, the output of a probabilistic model predicting the lag time of heat-treated Bacillus cereus spores under realistic heat-treatment profile and chilled supply-chain conditions, has been investigated using a sensitivity analysis technique. Indeed, knowing that there was uncertainty in the model (e.g. due to lack of data to build the model input probability density function), the objective of the analysis was to evaluate if the variability associated with some inputs (e.g. the consumers' refrigerator temperature values reported in Europe and US markets were different) had a significant impact on the model output, i.e. on the expected lag time of heat-treated B. cereus spores in REPFEDs. To do so, the uncertainty and variability associated with the various model inputs have been identified and then separated using a second order Monte Carlo decomposition. Concerning the variability, there was a significant difference between the chilled supply-chains (Europe, US) and between the raw material groups (low, medium or high contamination levels). For example, in the European market, after a heat treatment of 90 degrees C for 10 min, with a high raw material contamination level, the predicted 5th percentile of the lag time was 17 days, while it was 35 days with a low raw material contamination level. This was confirmed with an ANOVA. The impact of the uncertainty on the lag time has been illustrated graphically by building confidence intervals around its 5th percentile. A sensitivity analysis based upon uncertainty and variability decomposition is clearly a complex and time consuming exercise; however, it provides a greater confidence (greater transparency and better understanding) in the model output when making food safety decisions (e.g. determining the safe shelf-life of REPFEDs).     

Cr(Ⅵ)-溴酸钾-乙基紫催化光度法测定痕量铬(Ⅵ)的研究

在磷酸介质中,利用铬(Ⅵ)催化溴酸钾氧化乙基紫褪色这一指示反应,建立了动力学光度法测定痕量铬的新方法。线性范围为0.004~0.094μg/mL铬(Ⅵ),检出限为1×10-9g/mL,可用于水样中痕量铬(Ⅵ)的测定。