RANS-based Aerodynamic Shape Optimization Investigations of the Common Research Model Wing

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140409/1/6.2014-0567.pd

The intensified constructed wetlands are promising for treatment of ammonia stripped effluent: nitrogen transformations and removal pathways

This study investigated the treatment performance and nitrogen removal mechanism of highly alkaline ammonia-stripped digestate effluent in horizontal subsurface flow constructed wetlands (CWs). A promising nitrogen removal performance (up to 91%) was observed in CWs coupled with intensified configurations, i.e., aeration and effluent recirculation. The results clearly supported that the higher aeration ratio and presence of effluent recirculation are important to improve the alkalinity and pollutant removal in CWs. The influent pH (>10) was significantly decreased to 8.2–8.8 under the volumetric hydraulic loading rates of 0.105 and 0.21 d-1 in the CWs. Simultaneously, up to 91% of NH4+-N removal was achieved under the operation of a higher aeration ratio and effluent recirculation. Biological nitrogen transformations accounted for 94% of the consumption of alkalinity in the CWs. The significant enrichment of δ15N-NH4+ in the effluent (47–58‰) strongly supports the occurrence of microbial transformations for NH4+-N removal. However, relatively lower enrichment factors of δ15N-NH4+ (−1.8 ‰ – −11.6‰) compared to the values reported in previous studies reflected the inhibition effect of the high pH alkaline environment on nitrifiers in these CWs

Current status and developing recommendations of tailings dam failure

This is the final version of the article. Available from Hindawi Publishing Corporation via the DOI in this record.Tailings dam failure accidents with limited emergency response time and huge potential threats, can often lead to heavy casualties and serious financial losses. In recent years, the decreasing trend of tailings dam failure accidents evidences the development of modern technology and safety management. However, the frequency of major tailings dam failure accidents has increased, rather than decreased. The 2015 Samarco Accident in Brazil and the 2014 Mount Polley Accident in Canada, along with their disastrous consequences, once again sounded the alarm for the tailings ponds safety. China is now facing a complicated safety situation, with 8869 tailings ponds all over the country, including 1425 “Overhead Tailings Ponds” which represents the tailings ponds that located within 1 km upstream of residential area, workshops, schools or other important facilities. Based on a large amount of relevant research literatures, focusing on three main aspects of accident prevention and control which include safety monitoring, early-warning and emergency preparation, safety management codes and standards, the current status and frontier progress were reviewed in this paper. Furthermore, the relevant problems in China were discussed and several improvement recommendations were put forward, which could provide a reference for the tailings pond accident prevention theoretical research and technological innovation. The result shows: (1) the safety monitoring standards in China are relatively strict. However, the monitoring instruments are lack of the stability, reliability and practicability. Thus the development of specific devices and new technologies is urgently needed. (2) The current early-warning method is lack of diversity and reliability. And further interdisciplinary application of information technology is becoming the developing trend. (3) The emergency management and decision-making should be based on sufficient scientific proof. However the relevant research is limited by test methods and simulating algorithms. (4) China now has built a complete system of safety management codes and standards. But with shortcomings of safety level classification, life-cycle management, change management process, accident investigation and so on, there is still a long way to go

RANS-based Aerodynamic Shape Optimization of a Blended-Wing-Body Aircraft

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106453/1/AIAA2013-2586.pd

Software fault-tolerance by design diversity DEDIX: A tool for experiments

The use of multiple versions of a computer program, independently designed from a common specification, to reduce the effects of an error is discussed. If these versions are designed by independent programming teams, it is expected that a fault in one version will not have the same behavior as any fault in the other versions. Since the errors in the output of the versions are different and uncorrelated, it is possible to run the versions concurrently, cross-check their results at prespecified points, and mask errors. A DEsign DIversity eXperiments (DEDIX) testbed was implemented to study the influence of common mode errors which can result in a failure of the entire system. The layered design of DEDIX and its decision algorithm are described