Estimating Inducer Blade Damping in Water with On-Blade Strain Measurements

This paper describes the testing, methodology, and results for estimating critical damping ratios of inducer blade structural natural frequencies. A sub-scale inducer water flow test was performed with on-blade strain gauge measurements. Data were acquired in quiescent air and water, and also at several shaft speeds and operating conditions. Two methods were used to provide active excitation to the blades. The first was to impart a mechanical impulse to the inducer shaft and observe the strain gauge response. The second was to install a stator plate upstream of the inducer to create a non-uniform but regular pressure field at the inducer inlet. There are challenges with using either approach, but damping information was extracted using both methods. Results showed that the critical damping ratio for a given blade mode increased from air to quiescent water, and also increased when the inducer was spinning

CSI sensing and control: Analytical and experimental results

Recent work on structural identification and large-angle maneuvers with vibration suppression was presented. The recent work has sought to balance structural and controls analysis activities by involving the analysts directly in the validation and experimental aspects of the research. Some new sensing, actuation, system identification, and control concepts were successfully implemented. An overview of these results is given

Bridges Structural Health Monitoring and Deterioration Detection Synthesis of Knowledge and Technology

INE/AUTC 10.0

Lessons from PPPs of Indian Railways and Way Forward

The Indian Railways (IR) have grand plans. They would like to leapfrog to a higher growth trajectory during 2010-20. Towards this, they would like to see a total investment of Rs 14,00,000 crores (cr), as stated in the Vision 2020, brought out by the Ministry of Railways (MoR) in December 2009. With whatever level of optimistic projections for the internal resources and borrowings for the coming decade, clearly, PPPs would have to be a significant source. This makes it imperative for the IR to create a policy framework that would attract PPPs, especially in the context that the PPPs in IR have not taken off as projected. This paper reviews PPP projects that the IR has evolved over the past 25 years. These include operating partnership projects of IR including with the state government, PPPs in the pipeline, and discontinued partnership projects in IR. The paper brings out issues that have implications for PPPs in IR. The significant ones are focus on infrastructure creation PPPs rather than service PPPs, partner selection more contextually based than through open competitive bidding, more than acceptable time lags between conceptualization and project execution, issues in extending the project scope, non mutuality in contractual arrangements, and conflict of interest due to multiple roles of IR. Based on these issues, the paper derives certain key lessons and provides a way forward.

Primordial non-Gaussianities after Planck 2015: an introductory review

Deviations from Gaussian statistics of the cosmological density fluctuations, so-called primordial non-Gaussianities (NG), are one of the most informative fingerprints of the origin of structures in the universe. Indeed, they can probe physics at energy scales inaccessible to laboratory experiments, and are sensitive to the interactions of the field(s) that generated the primordial fluctuations, contrary to the Gaussian linear theory. As a result, they can discriminate between inflationary models that are otherwise almost indistinguishable. In this short review, we explain how to compute the non-Gaussian properties in any inflationary scenario. We review the theoretical predictions of several important classes of models. We then describe the ways NG can be probed observationally, and we highlight the recent constraints from the Planck mission, as well as their implications. We finally identify well motivated theoretical targets for future experiments and discuss observational prospects.Comment: 23 pages + bibliography. 5 figures. Published in the French "Comptes Rendus de l'Acad\'emie des Sciences" on Inflatio

Promoting Intermodal Connectivity at California’s High Speed Rail Stations

High-speed rail (HSR) has emerged as one of the most revolutionary and transformative transportation technologies, having a profound impact on urban-regional accessibility and inter-city travel across Europe, Japan, and more recently China and other Asian countries. One of HSR’s biggest advantages over air travel is that it offers passengers a one-seat ride into the center of major cities, eliminating time-consuming airport transfers and wait times, and providing ample opportunities for intermodal transfers at these locales. Thus, HSR passengers are typically able to arrive at stations that are only a short walk away from central business districts and major tourist attractions, without experiencing any of the stress that car drivers often experience in negotiating such highly congested environments. Such an approach requires a high level of coordination and planning of the infrastructural and spatial aspects of the HSR service, and a high degree of intermodal connectivity. But what key elements can help the US high-speed rail system blend successfully with other existing rail and transit services? That question is critically important now that high-speed rail is under construction in California. The study seeks to understand the requirements for high levels of connectivity and spatial and operational integration of HSR stations and offer recommendations for seamless, and convenient integrated service in California intercity rail/HSR stations. The study draws data from a review of the literature on the connectivity, intermodality, and spatial and operational integration of transit systems; a survey of 26 high-speed rail experts from six different European countries; and an in-depth look of the German and Spanish HSR systems and some of their stations, which are deemed as exemplary models of station connectivity. The study offers recommendations on how to enhance both the spatial and the operational connectivity of high-speed rail systems giving emphasis on four spatial zones: the station, the station neighborhood, the municipality at large, and the region