On the analysis of fracture mechanisms and mechanical behavior of AA5083-based tri-modal composites reinforced with 5 wt.%B4C and toughened by AA5083 and AA2024 coarse grain phases

In this article, the influence of AA2024 and AA5083 coarse grains on mechanical properties and failure mechanisms of AA5083-5wt. %B₄C tri-modal composite has been discussed. AA2024 and AA5083 powders (<100 µm) were added to mechanically milled AA5083-5 wt.%B₄C powders in 25 and 50 wt.% and the mixtures were consolidated using the hot press and hot extrusion techniques. Results indicated that by adding AA2024 and AA5083 powders as coarse grains, hardness and tensile strength of AA5083-5 wt.%B₄C composite decreased but ductility increased. Moreover, by adding AA2024 powders as coarse grains, fracture mode changed and cracks tended to grow through along AA2024/AA5083-5 wt.%B₄C interface rather than being arrested or deflected. It seemed that dislocation mobility and the interface between coarse grains and ultra-fine grains had the main role in determining the mechanical properties and failure mechanisms in tri-modal AA5083-B₄C composites.     

柔性夹具技术研究

为适应快速多变的市场需求,制造企业需要设计并应用柔性夹具。介绍了柔性夹具的发展及特点,给出了柔性夹具的设计依据,并从零件结构及工艺、组成元件确定、强度与精度保证等方面分析了柔性夹具的设计方法。     

A new DEA common-weight multi-criteria decision-making approach for technology selection

This paper addresses an advanced manufacturing technology selection problem by proposing a new common-weight multi-criteria decision-making (MCDM) approach in the evaluation framework of data envelopment analysis (DEA). We improve existing technology selection models by giving a new mathematical formulation to simplify the calculation process and to ensure its use in more general situations with multiple inputs and multiple outputs. Further, an algorithm is provided to solve the proposed model based on mixed-integer linear programming and dichotomy. Compared with previous approaches for technology selection, our approach brings new contributions. First, it guarantees that only one decision-making unit (DMU) (referring to a technology) can be evaluated as efficient and selected as the best performer while maximising the minimum efficiency among all the DMUs. Second, the number of mixed-integer linear programs to solve is independent of the number of candidates. In addition, it guarantees the uniqueness of the final optimal set of common weights. Two benchmark instances are used to compare the proposed approach with existing ones. A computational experiment with randomly generated instances is further proceeded to show that the proposed approach is more suitable for situations with large datasets.     

Technology-driven growth and inclusive growth- implications for sustainable development in Africa

The 21st century industrial and digital age has been largely driven by technological dynamics and advancement. The Neo-classical argued that beyond the classical notion of investments and capital accumulation, technology growth, which is driven by innovation and development is a major driver for growth and development. Africa economies, which has been largely described as technologically dependent, has over the years through technological diffusion engaged modern processes in driving its economic activities, which has informed economic and even social outcomes. Therefore, using the generalised methods of moments for selected sub-Saharan African economies, this study intends to assess the extent to which the presence of technology has informed economic activities in Africa as well as its impact in addressing developmental issues of poverty and unemployment. Also, given the current drive towards sustainability, this study takes the neo-classical growth theory a step higher by examining the modulating effects of technology-driven growth (through mobile densities and ICTs) in setting the pace for sustainable development in Africa. The study shows that the expected long-run impact of a technology-induced growth in reshaping developmental outcomes is seen from the estimates.     

Processing of CaLa2S4 infrared transparent ceramics: A comparative study of HP and FAST/SPS techniques

The densification of CaLa₂S₄ (CLS) powders prepared by combustion method was investigated by the use of Field-Assisted Sintering Technique (FAST) and Hot Pressing (HP). CLS powders were sintered using FAST at 1000°C at different pressures and heating rates and sintered by HP under 120 MPa from 800°C to 1100°C for 6 hours with a heating rate of 10°C/min. Comparison of both techniques was further realized by use of the same conditions of pressure, dwell time, and heating rate. Complementary techniques (XRD, SEM-EDS, density measurements, FTIR spectroscopy) were employed to correlate the sintering processes/parameters to the microstructural/compositional developments and optical transmission of the ceramics. Both sintering techniques produce ceramics with submicrometer grain size and relative density of about 99%. Nevertheless, HP is more suitable to densify CLS ceramics without fragmentation and also reach higher transmission than FAST. Transmission of 40%–45% was measured out of a possible maximum of 69% based on the Fresnel losses in the 8-14 μm window when HP is applied at 1000°C for 6 hours under 120 MPa. In both techniques, ceramics undergo reduction issues that originate from graphitic sintering atmosphere.     

Office of Technology Assessment: History,implementation, and participatory critique

The Office of Technology Assessment (OTA), which was created by the Technology Assignment Act of 1972, was—and still remains even after its abolishment in 1995—a unique congressional agency. OTA provided members of Congress with their own means of understanding and evaluating complex science and technology matters—of which there are no shortages. It spurred an entire literature of academic research both about OTA and the idea of technology assessment more generally. Understanding the legislative history and implementation of the Technology Assessment Act is crucial not just for scholarship, though. OTA was a blueprint for institutionalizing politically accountable technology assessment. Even as technologies advance at rapid rates, OTA still offers valuable lessons that scholars and policy-makers alike ought to glean. This paper places OTA in a contemporary context of (institutionalized) technology assessment. It contributes to a better understanding of OTA's origins by tracing its lineage to a set of federal reports beginning in 1929. It then analyzes OTA's response to pragmatic implementation questions of how to strike a balance between speed, depth, scope, and temporal focus. Lastly, it uses a public values framework to critique OTA's failure to adequately incorporate participatory elements into its processes.     

Challenges for technology diffusion policy to achieve socio-economic goals

The aim of this contribution is to analyze the challenges for technology diffusion policies to achieve expected socio-economic goals and to deduce conclusions for an adequate policy design. Based on hypotheses from theoretical contributions, we review two rather distinct technology fields. One is biobased products, the other health technologies with bioethanol and magnetic resonance imaging respectively as case studies in order to derive rather general insights regarding those policies. The case studies highlight the difficulties in achieving the aimed societal goals by promoting technology diffusion. The dominant innovation design (e.g. techniques or resources used) which diffuses or its application fields (e.g. indication, patient characteristics) differ from those assumed in impact assessments and side-effects which occur in other markets. The direct linkage of policy measures to societal criteria may avoid some of those undesired developments but may have side effects of their own, such as trade distortions or shifting the environmental burden to other activities. However, there is considerable scope for improvement in policy design compared to the status-quo. Overall, a more balanced policy mix regarding various socio-economic goals is vital and unintended side effects have to be considered more in decision making.     

生产国V汽油的RSDS-III技术开发

The 3rd generation catalytic cracking naphtha selective hydrodesulfurization(RSDS-III) technology developed by RIPP included the catalysts selective adjusting(RSAT) technology, the development of new catalysts and optimized process conditions. The pilot plant test results showed that the RSDS-III technology could be adapted to different feedstocks. The sulfur content dropped from 600 μg/g and 631 μg/g to 7 μg/g and 9 μg/g, respectively, by RSDS-III technology when feed A and feed B were processed to meet China national V gasoline standard, with the RON loss of products equating to 0.9 units and 1.0 unit, respectively. While the feed C with a medium sulfur content was processed according to the full-range naphtha hydrotreating technology, the sulfur content dropped from 357 μg/g in the feed to 10 μg/g in gasoline, with the RON loss of product decreased by only 0.6 units. Thanks to the high HDS activity and good selectivity of RSDS-III technology, the ultra-low-sulfur gasoline meeting China V standard could be produced by the RSDS-III technology with little RON loss.     

The adoption of websites by nonprofits and the impact on society

An analysis is done on a sample of 1691 nonprofit organizations from division 5 of the census. The adoption rate of websites and the choice of website type by size of the organization are examined. The overall rate of adoption is far less than expected. A resource allocation view among those who have a website suggests that small organizations appear to be using their resources suboptimally compared to the larger organizations. Possible explanations of this are offered. Based upon the findings concerning growth, an improved path for success and its implications for nonprofits are discussed.