Improving solar ultraviolet irradiance measurements by applying a temperature correction method for Teflon diffusers

To establish trends in surface ultraviolet radiation levels, accurate and stable long-term measurements are required. The accuracy level of today's measurements has become high enough to notice even smaller effects that influence instrument sensitivity. Laboratory measurements of the sensitivity of the entrance optics have shown a decrease of as much as 0.07-0.1%/deg temperature increase. Since the entrance optics can heat to greater than 45 degrees C in Dutch summers, corrections are necessary. A method is developed to estimate the entrance optics temperatures from pyranometer measurements and meteorological data. The method enables us to correct historic data records for which temperature information is not available. The temperature retrieval method has an uncertainty of less than 2.5 degrees C, resulting in a 0.3% uncertainty in the correction to be performed. The temperature correction improves the agreement between modeled and measured doses and instrument intercomparison as performed within the Quality Assurance of Spectral Ultraviolet Measurements in Europe project. The retrieval method is easily transferable to other instruments.     

ASTM国际标准组织信息ASTM获取证书项目

ASTM国际标准组织最近发布了第一项关于获取证书项目的国际标准ASTM E2659-获取证书项目的标准规程.此项标准由E36认证认可技术委员会负责.E36技术委员会成立于1973年,负责制定有关合格评定的技术标准.E2659由E36.30个人认证分技术委员会制定,旨在为颁发证书机构(大学、政府机构、用人单位、培训机构和行业协会)开发和管理优质认证项目提供标准指南,从而帮助相关利益方评定认证项目的质量.     

A Prioritization Process

Abstract:

A prioritization process has been developed and used at Network Systems of BAE Systems. It has been used to derive weights of importance for the criteria in tradeoff studies and to prioritize goals, customer needs, capabilities, risks, directives, initiatives, issues, activities, requirements, technical performance measures, features, functions and value engineering activities. This article presents this prioritization process.     

Corrosion behavior of pure tin deposit under 55 °C/85 % RH reliability test

With recent moves to implement lead-free manufacturing in the electronics industry, more attention is being paid to the use of tin. One of greatest limitations regarding the reliability of tin is the undesirable development of tin whiskers. Many factors have been identified as being the cause of these whiskers, though tin corrosion has not. Three types of tin deposit grain structures have been developed in an effort to reduce the growth of whisker formations as type (A) with vertical and regular grain boundary; type (B) with horizontal and irregular grain boundary; and type (C) as a combination of both vertical (the top layer) and horizontal (the bottom layer) grain structures. We kept a series of samples in an oven for 1 year at 55 °C/85 % RH (relative humidity), and then used focused ion beam to examine the corrosion microstructure that occurred three types of deposit structures. We found the preferred path of corrosion to occur along the grain boundary and that tin oxide enlarges the volume of the deposit. In order to release the compressive stress that developed during corrosion, whiskers were formed as the grain structure being vertical. Corrosion developed in different locations of various deposits made of the three grain structures. We studied resulting in whisker growth, cracking and the development of internal oxide.     

Houghton anastigmatic telescope containing aspheric mirrors that allows corrector position as a free parameter

A family of catadioptric telescopes is investigated, characterzied with two-element, full-aperture afocal corrector lenses and aspherical, focusing, primary mirrors or primary-secondary mirror combination. Third-order aberration and design equation are provided for anastigmatic systems in which corrector position must be a free parameter, forcing the consideration of aspherics on the mirrored surfaces.     

Assessing the Impact of Engineering Undergraduate Work Experience: Factoring in Pre‐work Academic Performance

This paper examines how undergraduate work experiences affect engineering graduates' post‐graduation starting salary, their cumulative grade point average upon graduation, and their likelihood of receiving a job offer prior to graduation. This study contributes to the field of undergraduate work experiences uniquely by taking into account academic performance prior to work experience, including the exact number of work experiences, and examining how gender interacts with work experience to affect the measured outcomes. The results show that more experience results in a higher post‐graduation starting salary and an increased likelihood of a job offer prior to graduation. Increases in cumulative GPA upon graduation were only marginal. Furthermore, undergraduate work experience affected female and male students as well as students from different majors similarly.     

Analysis of computational problems expressing the overall uncertainties: photons, neutrons and electrons

In the frame of the EU Coordination Action CONRAD (coordinated network for radiation dosimetry), WP4 was dedicated to work on computational dosimetry with an action entitled 'Uncertainty assessment in computational dosimetry: an intercomparison of approaches'. Participants attempted one or more of eight problems. This paper presents the results from problems 4-8-dealing with the overall uncertainty budget estimate; a short overview of each problem is presented together with a discussion of the most significant results and conclusions. The scope of the problems discussed here are: the study of a (137)Cs calibration irradiator; the manganese bath technique; the iron sphere experiment using neutron time-of-flight technique; the energy response of a RADFET detector and finally the sensitivity and uncertainty analysis for the recoil-proton telescope discussed in the companion paper.     

Accounting for indirect land-use change in the life cycle assessment of biofuel supply chains

The expansion of land used for crop production causes variable direct and indirect greenhouse gas emissions, and other economic, social and environmental effects. We analyse the use of life cycle analysis (LCA) for estimating the carbon intensity of biofuel production from indirect land-use change (ILUC). Two approaches are critiqued: direct, attributional life cycle analysis and consequential life cycle analysis (CLCA). A proposed hybrid ‘combined model’ of the two approaches for ILUC analysis relies on first defining the system boundary of the resulting full LCA. Choices are then made as to the modelling methodology (economic equilibrium or cause–effect), data inputs, land area analysis, carbon stock accounting and uncertainty analysis to be included. We conclude that CLCA is applicable for estimating the historic emissions from ILUC, although improvements to the hybrid approach proposed, coupled with regular updating, are required, and uncertainly values must be adequately represented; however, the scope and the depth of the expansion of the system boundaries required for CLCA remain controversial. In addition, robust prediction, monitoring and accounting frameworks for the dynamic and highly uncertain nature of future crop yields and the effectiveness of policies to reduce deforestation and encourage afforestation remain elusive. Finally, establishing compatible and comparable accounting frameworks for ILUC between the USA, the European Union, South East Asia, Africa, Brazil and other major biofuel trading blocs is urgently needed if substantial distortions between these markets, which would reduce its application in policy outcomes, are to be avoided.     

A Transactional Model of Parent-Infant Interactions in Alcoholic Families.

This study examined the transactional nature of parent-infant interactions over time among alcoholic and nonalcoholic families. The sample consisted of 222 families assessed at 12, 18, and 24 months of child age. Results indicated that infant behavior did not influence parental behavior across time, but parental behavior was longitudinally predictive of infant behavior during play interactions. Higher paternal alcohol consumption at 12 months was longitudinally predictive of negative parental behavior at 24 months. Other significant risk factors included marital conflict, fathers' depression, and fathers' education. Results highlight the nested nature of risk in alcoholic families and the direction of influence from parent to child during interactions and suggest that 1 pathway to risk among these children is through negative parent-infant interactions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)