成分分析中测量不确定度的两种评定方法比较及Top-down法有效性验证

RB/T 141—2018《化学检测领域测量不确定度评定利用质量控制和方法确认数据评定不确定度》是近年来中国合格评定国家认可委员会大力推行的测量不确定度评定Top-down法标准。其方法原理是在期间精密度测量条件下，将影响成分分析测试结果的各种因素归纳为实验室质控数据的“偏倚值”和“期间精密度(标准偏差)”,合并这两个分量后，作为测试结果不确定度的估计量。方法简便，可操作性强。以全国分析检测人员能力培训委员会系列培训教材《成分分析中的数理统计及不确定度评定概要》(基于Bottom-up法原理的GUM法)和文献中的38个评定示例为基础数据，比较了Top-down和GUM两种方法结果。为充分利用文献数据，方便方法比较，Top-down法计算公式中的“偏倚分量”和“期间精密度”分别采用校准曲线拟合误差和重复测量精密度计算。结果表明，两种方法结果有可比性。用Top-down法结果除GUM法结果，两者比值稳健统计平均值为0.91;Top-down法结果略大于GUM法结果。用Top-down法评估了14个标准样品实验室测定结果的扩展不确定度，并与标准样品标准值扩展不确定度进行了比较。结果表明，以标...     

LD31变形铝合金新的光谱分析方法研究

本针对影响LD31变形铝合金光谱分析质量的关键问题：Mg元素的分析结果不稳定、准确度不高。通过分析线优化，利用现有的光谱标样，在进口的美国贝尔德DV6型光谱仪上成功地完成了该合金的光谱分析方法试验工作，完善了该合金的光电直读分析方法，该方法使分析结果更加准确可靠及稳定。     

钢轨矫前弯曲度的定量计算

用数学物理方法计算钢轨自然冷却过程中由于不均匀冷却产生不均匀收缩引起的弯曲率，并通过实测进行验证，证明计算方法、计算结果是正确的。分析弯曲产生机理及影响因素，提出降低或消除矫前弯曲度的方法。     

ICP—AES在钢铁材料成份分析领域的应用

电感耦合等离子发射光谱法是新兴的先进化学分析方法，该方法自动化程度高，效率快，其分析结果好坏与仪器备件设置息息相关。本文探讨了应用电感耦合等离于发射光语仅(ICP—AES)分析钢铁材料中硅(Si)、锰(Mn)、铬(Cr)、镍(Ni)、铜(Cu)等十几种元素的方法，研究了称样量、试祥前处理方式、空白、元素分析线、观察高度、背景校正方式、曲线校正方式、功率、载气流量等对分析结果的影响，建立了钢铁材料中12种元素的ICP—AES方式。在此基础上本文进一步探讨了使用ICP—AES法进行钢铁材料化学成份分析结果的可靠性，结果表明：ICP—AES分析方法结果是可靠的，与国家标准方法(GB223)之间不存在显著性差弄(Mo＞3％，Cr＞10％，Ni＞15％除外)，并近一步比较了在钢铁材料成份分析领域，ICP—AES分析方法与化学法的优劣，结果表明：对普碳钢和中低合金钢而言，Mn、Cu、Ni的ICP—AES结果较优；Si、N、Cr、V两种方法分析结果相近；Mo元素化学方法分析结果较优。     

硅铝钡中钡的测定

硅铝钡以其优异的脱氧能力，广泛应用于冶金行业中，但对硅铝钡中钡的分析方法尚无国家标准，对钡的测定一般采用硫酸钡重量法，但由于对试样处理不完全，共存元素的干扰及沉淀时酸度控制不当，造成分析结果不稳定，本文在《硫酸钡重法测定钡》的方法基础上，合理处理试样后，通过准确控制沉淀时的酸度和二次沉淀去除干扰元素，能得到更为准确的钡分析结果，方法稳定、准确度高。     

试样不具代表性对钢板韧性的影响及对策

不同的冷却速度和不同的时效温度，对试样的冲击韧性有不同的影响。分析了理化检验试样与成品板力学性能不一致的机理，对实验结果进行分析，并提出切实实际的解决方法。     

X荧光光谱分析铸铁中影响因素的研究

本文研究了炉前铁水不同取样方式对Ｘ荧光分析结果的影响，认为两种取样方式的试样在同一工作曲线上测定的Ｘ荧光值不一致。在此基础上建立了快冷却（金属模）试样炉前铸铁分析的工艺规范，经与化学方法对照，其结果吻合较好。     

提高火试金法可操作性的探讨

火试金法是检验首饰含金量的国家标准方法。但该方法冗长，影响因素多，特别是要求平行样品称量精确相等，要求粗知试样的组成含量，增加了其操作难度。通过试样纯度估计值偏差及平等样品称量不等对测试结果影响的试验与分析，放宽了方法对样品称量的苛刻要求，定量掌握试样纯度估计值偏差对测试结果的影响，提高了火试金法的可操作性。     

蒸馏—硝酸钍容量法测定氟量的测量不确定度评定

本文对测量不确定度的概念，内容作了简单的介绍，通过对蒸馏-硝酸钍容易法测定氟量中影响测量准确性各因素的分析，评定了它的测量不确定度，从评定的结果看，方法中氟化钠的纯度对测量不确定度的贡献最大，同时，在重复性条件下，方法所给出的允许差，很难达到，建议以后修订标准时加以考虑。     

测定铁矿石中磷磷钼蓝快速分析法的改进

通过对铁矿石中磷测定的磷钼蓝光度分析法的显色条件、试剂进行试验、改进，采用加入硝酸铋生成新的三元配合物，并以抗坏血酸取代氟化钠，消除了原方法存在的配合物不稳定等问题，提高了分析结果的准确度和精密度。     

Cardiovascular risk factors in relation to educational level in 36 000 men and women in The Netherlands

The study objective was to describe the associations between socioeconomic status and (concurrence of) cardiovascular risk factors. The Netherlands Monitoring Project on Cardiovascular Risk Factors is a screening project that was carried out from 1987-1991 in three cities. Cross-sectional data were obtained on educational level and on the prevalence of smoking, alcohol intake, physical inactivity, obesity, hypertension, hypercholesterolaemia and low HDL-cholesterol. A total of 36 000 men and women, aged 20-59 years participated. For all risk factors, except alcohol intake, a significant inverse association was found with educational level. Concurrence of risk factors was more prevalent in lower educated groups than in higher educated groups, but not more than can be expected under the condition of independence of the risk factors (no clustering). In conclusion, in the lower educated groups the prevalence of individual risk factors and of concurrence of risk factors was higher than in the higher educated groups. Concurrence of risk factors can have a synergistic effect on the risk for cardiovascular disease. Therefore socioeconomic differences in risk factors may explain a greater part of the socioeconomic differences in cardiovascular morbidity and mortality than is generally assumed.     

Benchmarking Studies on Construction Safety Management in China

This paper presents information by which to measure safety management performance on construction sites. In China, the conventional construction safety benchmarking approach is to assess safety performance by evaluating the physical safety conditions on site as well as the accident records, while no attention has been paid to the management factors that influence site safety. This paper is to identify the key factors that influence safety management and to develop a method for measuring safety management performance on construction sites. Based on the survey and interview data collected on safety management factors in 82 construction projects in China, the safety management index as a means to evaluate real-time safety management performance by measuring key management factors was developed. The quantified factors were compared with the commonly accepted physical safety performance index, which was derived from inspection records of physical safety conditions, accident rates, and the satisfaction of the project management team. Multifactor linear regression was conducted and the result indicates that safety management performance on site is closely related to organizational factors, economic factors, and factors related to the relationship between management and labor on site. Based on this benchmarking study, a practical safety assessment method was developed and then implemented on six construction projects. The results show that this method can be an effective tool to evaluate safety management on construction projects.     

A study of attitude change in the preretirement period.

2 separate sets of factors appear in preretirees' job attitude when they refer to their past experiences in middle age (30-55). Job-related factors provide satisfaction; context-related factors determine dissatisfaction. When sources of satisfaction were examined in the preretirement period, the dominant emphasis was on the context-related factors. This change of attitude was explained in view of the change of job structure. Choosing more attainable sources on the job, the context-related in case of preretirement, is more satisfying than choosing the ones which became more difficult to attain, the job-related factors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Valence of and Satisfaction with Job Outcomes

Approximately 2,800 unionized construction workers were surveyed and responses were received from 703, representing all crafts except boilermakers. The workers were asked about the importance they attach to various job related factors and their satisfaction with each factor. The 28 individual factors were reduced to seven using a factor analysis technique. The most important set of factors were those relating to the intrinsic nature of the work: working like a craftsman, performing challenging work, etc. The set of factors with which the workers was most satisfied was that of performance level: high productivity; quantity; and doing your work in a craftsmanlike manner. Individual factors that require attention on the part of contractors to improve worker motivation and satisfaction were identified using a 2×2 matrix that allowed the combination of importance and satisfaction scores. Overall satisfaction with the job was measured and a multiple regression analysis revealed that satisfaction with intrinsic factors makes the greatest contribution to general job satisfaction.     

Related factors contributing to the healthy lifestyle of urban employees through the PRECEDE model

The purpose of this study was to assess the related factors to the healthy lifestyle of 1147 urban employees. The theoretical framework of this study was the PRECEDE model. The model included three factors: 1. predisposing factors cardiovascular disease knowledge, general self-efficacy, health related diet and exercise self-efficacy, attitude for maintaining healthy life-style, health value, health status and illness history of family); 2. enabling factors (health resource availability, health resource utility); and 3. reinforcing factors (social support, feelings of colleagues health practice); The three factors were measured by 12 scales, through which the reliability and validity were assessed. According to the stepwise multiple regression analysis, diet and exercise self-efficacy, attitude for maintaining healthy life-style, marital status, cardiovascular disease knowledge, health status, occupational level, social support and feel of colleague health practice were the significant factors which accounted for 38.2% of variance. Predisposing factors and reinforcing factors were the important factors of healthy lifestyle on urban employees.     

Latent Structures of the Factors Affecting Construction Labor Productivity

At any moment in time, a multitude of factors simultaneously impact construction productivity. Utilizing the knowledge of thousands of construction craft workers, the writers quantitatively analyzed the underlying structure of the factors affecting construction productivity and identified which factors the craft workers consider to be more relatively important as well. This research identified 83 factors affecting construction labor productivity through 18 focus groups with craft workers and their immediate supervisors on nine jobsites throughout the U.S. Next, a nationwide survey was administered to 1,996 craft workers to assess the impact of these factors on construction labor productivity. Principal factor analyses identified 10 latent factors to represent the underlying structure of 83 productivity factors. In addition, the relative importance of the factors’ impact on construction productivity was examined based on the crafts’ union status, trade, and position (craft worker versus foreman). The writers also compared their results to similar previous efforts, and more importantly, identified significant differences that may impact future productivity improvement strategies. This research will help industry and the research community better understand the factors affecting construction labor productivity and more effectively direct future efforts to improve its performance.     

Clinical and in situ cellular responses to Haemophilus ducreyi in the presence or absence of HIV infection

This study examined the prevalence of cardiovascular risk factors among low-income women and assessed the level of awareness and attitudes about these risk factors in the community. A survey instrument was developed and administered by a single researcher to a convenience sample of women in health clinics and nonclinical community settings. These settings included: an academic clinic, community clinics, women's shelters, free meal sites, community centers, public housing units, and private homes in Philadelphia, Pennsylvania. Two hundred two women were selected without regard to age or race. The mean number of cardiovascular risk factors per subject was 2.6 (SD 1.4). Each of eight established cardiovascular risk factors was identified by 4% to 34% of subjects. Among those women with a specific risk factor, only 0% to 45% reported that they were at increased risk due to the presence of that factor. The prevalence of cardiovascular risk factors among low-income women is substantial. Knowledge and understanding of these risk factors is suboptimal, particularly among women personally affected by risk factors for cardiovascular disease.     

Protective factors for violence among released prisoners—Effects over time and interactions with static risk.

Objective: There is a substantial body of research on risk factors for violent behavior in adulthood but little empirical study of protective factors and desistance. Method: This study aimed to investigate the protective effects of factors hypothesized to reduce violent reoffending among a sample of 800 male prisoners following release into the community. Results: Five out of 15 hypothesized protective factors significantly reduced the likelihood of a violent reconviction. Protection was primarily related to social network factors that appeared to have long-term effects. Circumstances following release (finances and nature of accommodation) did not prove to be relevant, apart from immediate provision of accommodation, which had a substantial influence on reduction of risk shortly after release into the community, and being employed, in training or education, which was relevant for the 3rd year and subsequently. Our findings support the notion of independent effects of protective factors on outcome. No effect modification was found to indicate that protective factors have different effects at different levels of risk. Conclusions: The nature of the relationship between risk and protection should be considered in the assessment of risk for violence. Furthermore, risk factors focus on pathology and hazards, whereas protective factors emphasize positivism and hope for change. Future interventions may benefit from this positive approach. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Field Testing and Analysis of CRC Deck Girder Bridges

This paper presents findings of field tests and analysis of two conventionally reinforced concrete (CRC) deck girder bridges designed in the 1950s. The bridges are in-service and exhibit diagonal cracks. Stirrup strains in the bridge girders at high shear regions were used to estimate distribution factors for shear. Impact factors based on the field tests are reported. Comparison of field measured responses with AASHTO factors was performed. Three-dimensional elastic finite-element analysis was employed to model the tested bridges and determine distribution factors specifically for shear. Eight-node shell elements were used to model the decks, diaphragms, bent caps, and girders. Beam elements were used to model columns under the bent caps. The analytically predicted distribution factors were compared with the field test data. Finally, the bridge finite-element models were employed to compare load distribution factors for shear computed using procedures in the AASHTO LRFD and Standard Specifications.     

Effect of vestibular nerve section on cytochrome oxidase activity in the vestibular ganglion cells of the squirrel monkey

Estimates of behavioral thresholds of infants are elevated relative to those of adults. Explanations for the differences include auditory sensory factors and non-sensory factors, but no direct estimates of the relative contributions of these two factors have been made. In this investigation, thresholds in quiet and in increasing levels of a masking noise for a 1 kHz tone, in infants 8 to 11 months old and in adults, were determined. The infant-adult differences in unmasked threshold was compared to the infant-adult difference in an estimate of the minimum masking level (MML) that was derived from the masking data. The intensity level of a masking noise at which masking begins is assumed to be independent of the non-sensory factors that impact on the threshold value itself. Therefore, it is reasoned that the infant-adult difference in MML reflects more closely differences in auditory sensory factors than does the infant-adult difference in unmasked threshold. In the region of 1 kHz, the infant-adult difference in behavioral threshold was 12 dB and the infant-adult difference in MML was 8 dB. Therefore, according to our assumptions, 8 dB of the infant-adult difference in unmasked threshold is accounted for by sensory factors and the remaining 4 dB must be attributable to non-sensory factors.