四辊轧机轧辊弹性变形解析模块的开发

采用影响函数方法开发了四辊轧机轧辊弹性变形解析模块，完善了辊间压扁和工作辊压扁影响函数计算模型，克服了轧辊压扁影响函数计算过程浮点数被零除的缺陷，提出了平滑指数和收敛指标取值的处理方法，有效地解决了四辊轧机辊系弹性变形计算精度及收敛问题。该模块适应于普通四辊轧机、PC轧机和CVC轧机轧辊弹性变形计算，为热轧带钢板形控制提供了解析工具。     

基于神经网络的FCD絮凝控制系统的研究

神经网络具有很强的自学习和自适应能力,对于大滞后、非线性的复杂系统有较好的控制效果.针对水处理过程中系统环境不断变化,特别是流量有较大、频繁变化的情况下,在FCD絮凝控制系统的基础上,提出了神经网络控制方法.解决了混凝控制中的目标等效直径动态确定问题.实际运行表明,该方法取得了很好的控制效果,具有广阔的应用前景.     

Determination of N-nitrosodimethylamine at part-per-trillion levels in drinking waters and contaminated groundwaters

The carcinogen N-nitrosodimethylamine (NDMA) may be quantitated routinely at ultratrace (ng/L) levels in drinking water or contaminated groundwater. The aqueous sample is passed through a preconditioned Empore C18 filter disk to remove neutral nonpolar species and then extracted continuously overnight with highest purity dichloromethane. The latter is then concentrated to 1 mL, and a large aliquot (up to 200 microL) is loaded onto a dual-stage carbon sorbent trap, after which the solvent is removed with ultrapure helium. The concentrated residues are then injected onto a gas chromatographic column using a short-path thermal desorber. NDMA is selectively detected using a chemiluminescent nitrogen detector (CLND) operated in its nitrosamine-selective mode. The reporting limit for this procedure, evaluated using two independent statistically unbiased protocols, is 2 ng of NDMA/L. A related procedure, employing an automatic sampler instead of the short-path thermal desorber, provides convenient analysis of heavily contaminated samples and exhibits a reporting limit (same protocols cited previously) of 110 ng of NDMA/L. When the two methods are used together in a "two-tiered" protocol, NDMA concentrations spanning 4 orders of magnitude (ng/L to microgram/L levels) may be measured routinely. The low-level procedure employing only the short-path thermal desorber was applied successfully to three sources of drinking water, where NDMA concentrations ranged between 2 and 10 ng of NDMA/L. The two-tiered protocol was applied to a series of contaminated groundwaters whose NMDA concentrations ranged between approximately 10-7000 ng of NDMA/L. The results agreed with those obtained from an independent collaborating laboratory, which used a different analytical procedure.     

Improved measurement of transketolase activity in the assessment of "TPP effect"

The indirect estimation of thiamine levels in human blood by measuring thiamine pyrophosphate effect on erythrocyte transketolase activity is the method of choice in most clinical laboratories. We describe here an optimized, time-saving, and accurate method to determine the thiamine pyrophosphate effect in as many as 16 blood samples simultaneously. The method is based on a multi-point determination using a computer remote-controlled microplate reader. For multiple sample handling, three pooled reaction mixtures are freshly prepared and loaded onto a 96 well microtitre plate. A pre-written software is then initiated to remote-control the system. The data is retrieved and processed to calculate thiamine pyrophosphate effect by a self-written "macro" on a "Quattro-Pro" worksheet database. This method proves to be highly accurate (coefficient of variance: 2.7%), reproducible (coefficient of variance: 4.1%) and economical.     

Effects of antioxidant state on individual susceptibility to silicosis (an experimental study)

The authors proved that animals having higher natural antioxidant activity and lower intensity of lipid peroxidation are more resistant to fibrogenic effects of quartz. The peritoneal macrophages obtained from those animals show higher resistance to quartz exposure "in vitro". Parameters characterizing antioxidant system should be included into a group of indexes describing propensity to silicosis.     

Effects of subject- versus experimenter-selected reinforcers on the behavior of individuals with profound developmental disabilities

Results from a number of studies have shown that individuals with profound developmental disabilities often show differential approach behavior to stimuli presented in a variety of formats, and that such behavior is a reasonably good predictor of reinforcement effects when these "preferred" stimuli are used subsequently in a contingent arrangement. Recent data suggest that reinforcement effects may be enhanced further by allowing individuals to select, just prior to training sessions, which (of several) preferred stimuli would be used as reinforcers, but whether this method is superior to one based on selection by a teacher or therapist has not been adequately addressed. We compared the effects of these two methods of reinforcer selection on rates of responding on a free-operant task, using stimuli previously identified as potential reinforcers. Results obtained with 4 subjects indicated little or no difference in reinforcement effects when stimuli were selected by subjects rather than experimenters. Implications of these results with respect to choice and its relation to reinforcement are discussed.     

考虑频率与区间联络线功率安全约束的两区互联电力系统机组组合

随着电源结构与电网形态的转变,互联电力系统频率时空分布特征日益显著,区域频率差异与区间联络线功率振荡增大,基于统一频率假设的频率安全约束机组组合方法不再适用。针对考虑频率时空分布特征的两区互联电力系统安全约束机组组合,推导区域频率与区间联络线功率闭式解,并基于闭式解的两项划分,推得区域频率最低点、最大变化率、准稳态值以及区间联络线功率振荡峰值、准稳态值等一系列解析安全量化指标。基于所得指标,构建考虑区域频率与区间联络线功率安全约束的机组组合模型。并根据调度模式与指标特点,提出兼顾区域能力保障与区间能力协调的两级两阶段迭代求解算法。结果表明,所得指标可准确描述两区互联电力系统的安全特征,所提模型和算法可有效保障两区互联电力系统机组组合方案的运行安全。     

珍珠层粉/壳聚糖多孔支架的制备及分析测试

用负压真空冷冻干燥机在-20℃条件下冷冻干燥48h制备珍珠层粉/壳聚糖复合多孔支架。用扫描电子显微镜(SEM)观察支架表面形貌,通过X射线衍射分析(XRD)、傅里叶红外光谱(FTIR)等手段对材料进行表征测试,检测其降解性能,并将兔骨髓间充质干细胞与支架共培养检测材料细胞毒性。结果表明复合支架具有稳固的三维多孔结构,孔隙率最大至91.64%,孔径在100~300μm范围,降解性能适宜,且冷冻干燥制备方法对珍珠层粉的结构无明显破坏,并具有良好的生物相容性,有利于细胞的生长。     

壳聚糖改性竹粉/PVC复合材料的制备和性能

壳聚糖、竹粉和PVC等按一定比例混合,用挤出成型法制备了竹粉/PVC复合材料。考察了壳聚糖添加量对复合材料物理力学性能、热稳定性、防水性能和防腐性能的影响。结果表明,适量壳聚糖的添加,可以改善复合材料的综合性能。且当壳聚糖含量为3wt%时复合材料的性能最佳,与未添加壳聚糖的复合材料相比,其拉伸强度、冲击强度和弯曲强度分别提高了44.7%、58.2%和79.6%,腐蚀前8天的吸水率从2.2%降低为1.6%,被白腐菌和褐腐菌腐蚀后材料的质量损失率分别降低了94.1%和75.0%。     

FRC measurement in intensive care patients. A definition of standards

Determination of Functional Residual Capacity (FRC) can be performed through washout methods, indicator gas dilution or bodyplethysmography. Some of these techniques have been adapted for use in intensive care patients whilst being mechanically ventilated. However, most measurement setups are bulky, cumbersome to use and their running costs are high. Hence FRC measurement has not become a routine method in intensive care although it offers considerable advantages in the management of ventilated patients such as the determination of "best PEEP", the detection of progressive alveolar collapse in the course of acute lung injury and during weaning from mechanical ventilation. Up to now most efforts to improve and simplify FRC measurement were made at the expense of accuracy. An ideal method ought to be accurate, easy to handle and cost-effective. It should supply not only FRC data but also information about intrapulmonary gas distribution and dead space. These demands can be met using modern data acquisition software. The pros and cons of all methods available for FRC measurement are discussed in view of their suitability for intensive care patients. A conventional nitrogen washout using emission spectroscopy for measurement of nitrogen concentration gives satisfying exact values for the determination of the parameters mentioned above. The measurement error can be lowered under 5% by special corrections for flow and nitrogen signal (delay and rise times, changes of gas viscosity). For flow measurement a normal pneumotachograph can be used. Using a laptop computer for data acquisition the bed-side monitor fulfills most of the demands in intensive care. It is then also possible to measure indices of intrapulmonary gas distribution such as Alveolar Mixing Efficiency and Lung Clearance Index.