应用图像空域法的针织物密度在线测量

人工测量针织物密度的方法存在耗时、不能连续测量的缺点,且离线测量也无法满足针织物密度在线控制要求,为此,提出一种基于空间域对针织物图像处理得到其密度的方法。在针织物二值化图像基础上,根据针织物纹理特点提取出表征织物横密的纱线后,应用改进的Hough变换检测得到图像中针织物的横纱数目;而后根据横纱提取每行线圈,采用核密度估计对针织物线圈间距的统计量进行密度估计,得到标准的线圈间距,进而计算得到图像中横向平均线圈数;再通过换算计算得到针织物的密度。实验验证结果表明该方法是有效的。     

The measurement of wood density by microwave sensor

This paper presents the first results of wood density measurement using a microwave sensor. The information given by the sensor are amplitude variations and phase variations of the transmitted wave. This work concerns the calibration of the sensor. To eliminate the problem of wood anisotropy we used boards made from glued and pressed sawdust. There are 5 kinds of sawdust and from each five different board densities were prepared. The first measurements concerned the geometry and the realibility of the sensor. The results show that the sensor does not present defect geometry and that its readings are reliable. Then we looked for a relationship between board density and the variations of the microwave parameters. An accurate linear relationship was found, but it appears to be necessary to consider each sawdust type separately. Based on these results we prepared other samples with different glue contents to control the influence of glue on microwave parameters. The results show that in our ranges of densities (0.55–0.75 g/cm³) and glue contents (6–12%) the influence of glue is negligible. Furtheron, it appears that measuring the amplitude variation may be a means for controlling the granulometry of particle boards.     

Developing novel 3D measurement techniques and prediction method for food density determination

Density is a physical characteristic which depends on the experimental technique used and structural properties of food. True, apparent, and bulk are different types of densities based on the way volume is measured. For porous foods such as grain food products, accurate measurement of density is challenging. Current measurement techniques for food density are inconsistent and nutrient databases do not have sufficient density data. Computed tomography (CT) and magnetic resonance imaging (MRI), laser scanners are non-destructive diagnostic tools for characterizing food microstructure. The objectives of this study were to 1) optimize the parameters of CT, MRI, and laser scanner to determine food density and compare the corresponding values with other traditional techniques, and 2) to develop neural networks as a prediction method for apparent and bulk densities. MicroCT 40 (Scano Medical Inc.), Lightspeed QX/i clinical CT (GE Healthcare), and 3 Tesla Signa HDx MRI (GE Healthcare) were used to acquire 3D images of foods for true density. A 3D laser scanner (NextEngine, Inc) was used to scan the foods items for apparent density. Neural networks were used in conjunction with the data collected from laser scanner and using food composition and processing conditions to generate a black-box prediction scheme. The results of CT, MRI, and laser scanner showed great potential to estimate density in comparison to traditional techniques. Porosity was estimated from the CT and MRI scanned image data. Laser scanner was successful in acquiring 3D images and calculating apparent density. Neural networks provided reliable density prediction power and were comparable to the other empirical equations in terms of accuracy. The ability to predict food density based on composition and processing conditions is necessary to fill gaps in nutrient databases and account for new foods.     

生长圈法应用于选育L-异亮氨酸菌株的条件优化

生长圈测定法是L-异亮氨酸高产菌筛选育种工作中较为简单、方便、经济、有效的一种测定方法。本文对影响生长圈法测定的检测培养基加入指示菌时温度、指示菌加入量、检测板琼脂浓度、琼脂块琼脂浓度等因素进行了研究。结果得到优化方法为测定平板和琼脂块均选用基本培养基;测定平板采用上层为10mL混菌培养基,下层为10mL基本培养基的双层平板,其琼脂浓度都为1%;琼脂块的琼脂浓度为1.5%;混菌平板中指示菌培养时间为18h,加入量为4%,混菌时最佳培养基温度为55℃。      

热敏电阻法测量食品导热系数的研究

在微珠状热敏电阻传热模型的基础上,提出适用于食品导热系数的测量方法,同时研究标定物、介质大小和加热功率对该方法的影响.结果表明,以水和甘油为标定物所得到的热敏电阻的特性参数具有最高的准确度,对标准样品导热系数测量的最大相对误差为5.02%;热敏电阻法适用于食品介质导热系数的测量,通过热敏电阻法和热探针法得到样品的导热系数相对偏差小于4%.     

Sensitive real-time measurement of the refractive index and attenuation coefficient of milk and milk-cream mixtures

We demonstrate a first simultaneous measurement of both the refractive index and the attenuation coefficient (defined as the sum of the scattering and absorption coefficients) of highly turbid milk and milk-cream mixtures. We achieve this by observing the real-time reflectance profile of a divergent laser beam made incident on the surface of the milk sample. The experiments were carried out on commercial milk samples with fat volume concentrations of 0.5 or less, 1.6, and 3.3%, and on milk-cream mixtures with fat volume concentrations of 10 and 33.3%, without any dilutions of these samples. We find that the reflectance data are well described, for the first time without any empirical fit-parameters, by Fresnel theory that correctly includes the effect of angle-dependent penetration into the turbid medium on the total internally reflected signal. Therefore, our method provides the most accurate determination to date of the refractive index and attenuation coefficient of milk and milk-cream mixtures. Our sensor is compact, portable, and inexpensive.     

Estimating bacterial density from tube dilution data by a Bayesian method

We have developed a statistical computer program based on a Bayesian approach to estimate bacterial density from tube dilution data. The program calculates an expectation, a mode (equivalent to the traditional most probable number (MPN)) and a median as point estimates of the bacterial density. The Bayesian analysis provides a probability density function which reflects the knowledge accumulated about the bacterial density by observing the data. Its expectation is a summary value that incorporates the shape and skewness of the distribution. On the other hand, the MPN (mode) only uses the single most likely value and ignores other values that are consistent with the data. As a result the MPN consistently underestimates the bacterial density and is likely to produce large errors. Thus we recommend the use of the expectation as an estimator for most problems. The theoretical basis of the Bayesian approach and its application toSalmonelladata is discussed. Tables of results for different combinations of tube dilutions are also presented.     

Milk fat content measurement by a simple UV spectrophotometric method: an alternative screening method

We developed a simple microtechnique to measure lipids in milk by UV spectrophotometry. This technique is based upon the property of fatty acids to absorb UV light proportional to their concentration. Samples of powdered or fluid milk (30 or 60 muL) were added to 3 mL of analytic grade ethanol and stored at -20 degrees C for at least 1 h. This procedure precipitates proteins and hydrophobic peptides that interfere with UV measurement. Sample absorbances are then measured at 208 nm in an UV-Vis spectrophotometer. This technique correlated very well against Milko-Scan, a device that measures milk fat by IR spectroscopy, with an r(2) >0.982. Accuracy and precision, evaluated by recovery and replicate assays, are also very acceptable. This method is suitable as a fast, cost-effective alternative screening method to estimate milk fat content in small samples without prior lipid extraction.     

密度方法在谱与tilings关系中的一个应用

谱对与tiling对存在某些确定的联系，两者在小波理论、离散Fourier分析与三角逼近理论中有着直接的应用．本文将从谱与tilings的基本性质出发，利用密度方法，得到谱与tilings关系中集合的勒贝格测度的一些估计，为进一步研究此类I＂-1题奠定基础．这里的研究是基于谱与tilings的基本性质，与共轭Fuglede猜想密切相关．     

蒸馏法测定葡萄酒中二氧化硫的不确定度分析

对蒸馏法测定葡萄酒中二氧化硫的不确定度进行了评定。通过对实验中不确定度各分量的分析计算,测得葡萄酒中二氧化硫的含量为(0.0929±0.0028)g/L(k=2)。本实验不确定度具体由碘标准滴定溶液的标定及肉眼判断滴定终点所引起。      

内核密度分布与自举法对纺织品镉含量代表值估计

测定了国产织物样品中的镉含量,对镉含量基础统计学特征进行了描述,采用内核密度分布估计对镉含量数据的多态性进行分析,根据非正态分布的特点,使用Bootstrap法对样本值模拟重复取样,以多次Bootstrap模拟取样的均值与标准偏差作为被考察样品有限单次样本代表值及标准偏差的稳健估计。实践证明:该方法得到的均值与标准偏差作为有限单次样本代表值是合理、有效的,该研究为纺织品禁限用物质的风险评估中禁限用物质含量的表述提供了一种新方法。     

Simultaneous measurement of the effective density and chemical composition of ambient aerosol particles

Simultaneous measurements of the effective density and chemical composition of individual ambient particles were made in Riverside, California by coupling a differential mobility analyzer (DMA) with an ultrafine aerosol time-of-flight mass spectrometer (UF-ATOFMS). In the summer, chemically diverse particle types (i.e., aged-OC, vanadium-OC-sulfate-nitrate, biomass) all had similar effective densities when measured during the same time period. This result suggests that during the summer study the majority of particle mass for the different particle types was dominated by secondary species (OC, sulfates, nitrates) of the same density, while only a small fraction of the total particle mass is accounted for by the primary particle cores. Also shown herein, the effective density is a dynamic characteristic of the Riverside, CA ambient aerosol, changing by as much as 40% within 16 h. During the summer measurement period, changes in the ambient atmospheric water content correlated with changes in the measured effective densities which ranged from approximately 1.0 to 1.5 g x cm(-3). This correlation is potentially due to evaporation of water from particles in the aerodynamic lens. In contrast, in the fall during a Santa Ana meteorological event, ambient particles with a mobility diameter of 450 nm showed three distinct effective densities, each related to a chemically unique particle class. Particles with effective densities of approximately 0.27 g x cm(-3), 0.87 g x cm(-3), and 0.93 g x cm(-3) were composed mostly of elemental carbon, lubricating oil, and aged organic carbon, respectively. It is interesting to contrast the seasonal differences where in the summer, particle density and mass were determined by high amounts of secondary species, whereas in the fall, relatively clean and dry Santa Ana conditions resulted in freshly emitted particles which retained their distinct source chemistries and densities.     

果汁中碳水化合物测定方法的工艺研究

对果汁中碳水化合物的测定方法进行了研究,采用单因素和正交实验法测定果汁中碳水化合物量,其最佳条件为:水解时加入盐酸20mL,反应滴定温度70℃,反应液酸度(pH)5.0、水解时间1.5h.该方法直观、简洁、可操作性好.     

响应面法优化包被发酵嗜酸乳杆菌的高密度培养

针对益生菌嗜酸乳杆菌（Lactobacillus acidophilus）包被发酵的形成特性和营养需要,采用Plackett-Burman试验设计优化其增殖培养基,获得高密度培养条件和提高菌粉存活率方法。结果表明,嗜酸乳杆菌包被发酵的增菌最佳培养基组成为：葡萄糖7.77%、蛋白胨2%、牛肉膏2%、酵母粉3%、柠檬酸氢二铵0.3%、K2HPO4·7H2O 0.2%、MgSO4·7H2O 0.09%、MnSO4·4H2O 0.025%、NaAc·3H2O 0.3%、吐温-80 0.1%、海藻酸钠1.45%、纳米碳酸钙2.93%。在此优化条件下,嗜酸乳杆菌活菌数达4.32×1010 CFU/mL,制备成的冻干粉在37 ℃条件下贮藏100 d后仍保留75%以上的存活率。     

毛坯密度控制方法

☆线圈长度法 在40 cm长的纱线上做记号,然后去编织,下机后记下其编织成的线圈个数(保留1位小数).相同织物的织片,相同长度的纱长,在其他编织条件相同时,其衣片的毛坯密度也应相同.此法常用于指导改换品种时对横机弯纱三角的调节.     

稳健统计-迭代法评估卷烟物理测量不确定度

为改进实验室卷烟物理测量不确定度的评定工作,探索稳健统计-迭代法评定卷烟物理测量不确定度的可行性,本研究利用实验室积累的质控数据,分别采用“bottom-up”法和稳健统计-迭代法对卷烟物理中质量、圆周、吸阻、硬度的测量不确定度进行评定。结果表明:利用稳健统计-迭代法计算的卷烟质量、圆周、吸阻和硬度的扩展不确定度分别为0.010 g、0.04 mm、28.0 Pa和5.3%,利用“bottom-up”法的计算结果为0.012 g、0.04 mm、32.0 Pa和6.8%。稳健统计-迭代法反映了实验室较长时间内的检测水平,而且评定过程简单方便,体现了该方法的优势。      

Cu2+/Fe3+/H2O2体系降解染料脱色的研究

用Fe^3＋／H2O2、Cu^2＋／H2O2、Cu^2＋／Fe^3＋／H2O2三种催化氧化体系，对四种不同结构的有机染料废水进行氧化脱色；考察初始pH值、反应时间及Fe^3＋／Cu^2＋比等因素对处理效果的影响；探讨重复利用Fe^3＋／Cu^2＋／H2O2体系中Fe^3＋和Cu^2＋结果表明，四种染料被氧化脱色的难易程度为：酸性橙Ⅱ（偶氮染料）〉中性红（醌亚胺染料）〉碱性品红（三芳甲烷染料）〉茜素紫（蒽醌染料）；采用Fe^3＋／Cu^2＋／H2O2复合体系代替单一的催化离子，能有效适应pH值的变化；Fe^3＋和Cu^2＋可重复利用4—5次。     

Preparation of magnetic PET fabric loaded with Fe3O4 nanoparticles by hydrothermal method

A layer of magnetite nanoparticles are synthesized and simultaneously coated on the surface of the PET fabric using ferrous sulfate as the precursor, sodium hydroxide as the precipitant, and sodium dodecyl benzene sulfonate as the dispersant at controlled pH during hydrothermal treatment. The magnetite-coated PET fabric is then modified with silane coupling agent A-151. The as-obtained fabric and nanoparticles are systematically studied by means of field emission scanning electron microscopy, energy-dispersive X-ray, X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermal gravimetric analysis, differential scanning calorimetry, and vibrating sample magnetometry. The tensile properties and resistance to washing are also examined. The obtained results indicate that magnetite (Fe₃O₄) nanoparticles with diameters around 50 nm are grafted onto the PET fabric and modified with silane coupling agent A-151 via the C–Fe, O–Fe, and Si–O–Fe bonds. After treatment, the thermal stability and tensile properties of the Fe₃O₄-coated PET fabric change, but not too much. The capabilities of magnetic response and durable washing are also obtained.