Evaluation of Steel Bridges, Volumes I & II

This report is divided into two volumes. Volume I summarizes a structural health monitoring (SHM) system that was developed for the Iowa DOT to remotely and continuously monitor fatigue critical bridges (FCB) to aid in the detection of crack formation. The developed FCB SHM system enables bridge owners to remotely monitor FCB for gradual or sudden damage formation. The SHM system utilizes fiber bragg grating (FBG) fiber optic sensors (FOSs) to measure strains at critical locations. The strain-based SHM system is trained with measured performance data to identify typical bridge response when subjected to ambient traffic loads, and that knowledge is used to evaluate newly collected data. At specified intervals, the SHM system autonomously generates evaluation reports that summarize the current behavior of the bridge. The evaluation reports are collected and distributed to the bridge owner for interpretation and decision making. This volume (Volume II) summarizes the development and demonstration of an autonomous, continuous SHM system that can be used to monitor typical girder bridges. The developed SHM system can be grouped into two main categories: an office component and a field component. The office component is a structural analysis software program that can be used to generate thresholds which are used for identifying isolated events. The field component includes hardware and field monitoring software which performs data processing and evaluation. The hardware system consists of sensors, data acquisition equipment, and a communication system backbone. The field monitoring software has been developed such that, once started, it will operate autonomously with minimal user interaction. In general, the SHM system features two key uses. First, the system can be integrated into an active bridge management system that tracks usage and structural changes. Second, the system helps owners to identify damage and deterioration

Further Developments on a Vibration-Free Helium-Hydrogen Sorption Cooler

In our continuous effort on the development of a passively precooled two-stage 4.5 K / 14.5 K helium-hydrogen sorption cooler, a number of important development steps were made. Firstly, an improved high-density activated carbon was used for the fabrication of four new sorption cells. Tests with these new cells showed that because of increased efficiency, the required passive radiator area for this cooler reduced by a factor of 1.3. Secondly, it was shown that this cooler architecture can easily be used to reach lower (or higher) temperatures. Without hardware changes, the cold temperature was reduced from 4.5 K to 3.1 K. Thirdly, long-term experiments were carried out on the cooler. In two separate periods of two and four months of continuous operation, no change at all was observed in the cooler performance. Fourthly, clogging effects were analyzed that occurred after a 15 months storage period of the cooler at 300 K. We concluded that hydrogen diffusion out of the stainless steel components should be prevented. Finally, a design of an integrated compact cooler chain was presented, which consists of a 50 K Stirling cooler and the helium-hydrogen sorption cooler. This package may be used in the future to test the sorption cooler technology in a zero-gravity environment

Effect of sitagliptin on energy metabolism and brown adipose tissue in overweight individuals with prediabetes:a randomised placebo-controlled trial

Aims/hypothesis: The aim of this study was to evaluate the effect of sitagliptin on glucose tolerance, plasma lipids, energy expenditure and metabolism of brown adipose tissue (BAT), white adipose tissue (WAT) and skeletal muscle in overweight individuals with prediabetes (impaired glucose tolerance and/or impaired fasting glucose). Methods: We performed a randomised, double-blinded, placebo-controlled trial in 30 overweight, Europid men (age 45.9 \xc2\xb1 6.2\xc2\xa0years; BMI 28.8 \xc2\xb1 2.3\xc2\xa0kg/m2) with prediabetes in the Leiden University Medical Center and the Alrijne Hospital between March 2015 and September 2016. Participants were initially randomly allocated to receive sitagliptin (100\xc2\xa0mg/day) (n = 15) or placebo (n = 15) for 12\xc2\xa0weeks, using a randomisation list that was set up by an unblinded pharmacist. All people involved in the study as well as participants were blinded to group assignment. Two participants withdrew from the study prior to completion (both in the sitagliptin group) and were subsequently replaced with two new participants that were allocated to the same treatment. Before and after treatment, fasting venous blood samples and skeletal muscle biopsies were obtained, OGTT was performed and body composition, resting energy expenditure and [18F] fluorodeoxyglucose ([18F]FDG) uptake by metabolic tissues were assessed. The primary study endpoint was the effect of sitagliptin on BAT volume and activity. Results: One participant from the sitagliptin group was excluded from analysis, due to a distribution error, leaving 29 participants for further analysis. Sitagliptin, but not placebo, lowered glucose excursion (\xe2\x88\x9240%; p < 0.003) during OGTT, accompanied by an improved insulinogenic index (+38%; p < 0.003) and oral disposition index (+44%; p < 0.003). In addition, sitagliptin lowered serum concentrations of triacylglycerol (\xe2\x88\x9229%) and very large (\xe2\x88\x9246%), large (\xe2\x88\x9235%) and medium-sized (\xe2\x88\x9224%) VLDL particles (all p < 0.05). Body weight, body composition and energy expenditure did not change. In skeletal muscle, sitagliptin increased mRNA expression of PGC1\xce\xb2 (also known as PPARGC1B) (+117%; p < 0.05), a main controller of mitochondrial oxidative energy metabolism. Although the primary endpoint of change in BAT volume and activity was not met, sitagliptin increased [18F] FDG uptake in subcutaneous WAT (sWAT; +53%; p < 0.05). Reported side effects were mild and transient and not necessarily related to the treatment. Conclusions/interpretation: Twelve weeks of sitagliptin in overweight, Europid men with prediabetes improves glucose tolerance and lipid metabolism, as related to increased [18F] FDG uptake by sWAT, rather than BAT, and upregulation of the mitochondrial gene PGC1\xce\xb2 in skeletal muscle. Studies on the effect of sitagliptin on preventing or delaying the progression of prediabetes into type 2 diabetes are warranted. Trial registration: ClinicalTrials.gov NCT02294084. Funding: This study was funded by Merck Sharp & Dohme Corp, Dutch Heart Foundation, Dutch Diabetes Research Foundation, Ministry of Economic Affairs and the University of Granada

Thermal design of the EarthCARE MSI-VNS instrument

The EarthCARE satellite mission objective is the observation of clouds and aerosols from low Earth orbit. The payload will include active remote sensing instruments being the W- band Cloud Profiling Radar (CPR) and the ATLID LIDAR. These are supported by the passive instruments BroadBand Radiometer (BBR) and the Multispectral Imager (MSI) providing the radiometric and spatial context of the ground scene being probed. The MSI will form Earth images at 500 m ground sample distance over a swath width of 150 km; it will image the Earth atmosphere in 7 spectral bands. The MSI instrument will be formed in two parts: the Visible, Near infrared and Short wave infrared (VNS) unit, and the Thermal InfraRed (TIR) unit. In the VNS optical unit, the ground scene is imaged onto four linear detectors via four separate optical channels. Driving requirements for the VNS instrument performance are radiometric accuracy, signal-to-noise ratio, optical image quality and coregistration. Driving requirements for the VNS instrument performance are the spectral sensitivity, the image quality, co-registration and the inter-channel radiometric accuracy. Derived thermal design requirements: • The Short Wave Infrared-2 (SWIR-2) detector needs to be cooled to a narrow temperature band around 230 K in order to meet the sensitivity requirements. • Thermal stabilization of optical housing and the detectors is required to meet het radiometric accuracy requirements. • Reduction of spatial and temporal temperature gradients in the optical unit is required to prevent distortions leading to reduced image quality and loss of co-registration between the channels. The following thermal design and analysis aspects will be covered: • Accommodation of the instrument on the EarthCARE spacecraft and its thermal environment. • A trade-off between passive and thermo-electric cooling of the SWIR-2 detector. • Thermal stabilization of the optical unit. • Interaction between finite element style internal thermo-mechanical model and the external thermal analysis using ESATAN/THERMICA. The VNS is current under development by an integrated TNO/Dutch Space engineering team. © 2011 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved

Present status of developments in physical sorption cooling for space applications

A sorption cooler uses the Joule–Thomson effect for cooling a gas by expanding it through a flow restriction. The flow of gas is sustained by a compressor consisting of one or more sorption cells, which cyclically adsorb and desorb gas according to the fully reversible process of physical sorption. The technology has been shown to provide active cooling in the cryogenic temperature range without exporting vibrations or electromagnetic interference. Due to full reversibility of the process and the absence of moving parts (apart from check valves, which open and close with a very low frequency), such a cooler has the potential for a very long life and high reliability. This paper starts with a recapitulation of the principles of physical sorption cooling followed by an overview of the strengths and weaknesses of the technology in relation to other space cooling technologies, such as pulse-tube cooling and Stirling cooling. Next, the present status of physical sorption cooling technology is presented based on developments previously and currently being performed by the University of Twente, Dutch Space and Kryoz Technologies. A summary will be given of the various existing demonstrator- and lab-models which have been built, along with an overview of the tests which have so far been performed. The central result of this paper is an assessment of the current Technology Readiness Level (TRL) of various sorption cooler configurations, along with their application range in terms of temperatures, heat loads and mission profile. Finally, an outline is given on the way forward currently being pursued by the developers to achieve full maturity of the technolog

Maintenance implications of critical components in ITER CXRS upper port plug design

Already in the early phase of a design for ITER, the maintenance aspects should be taken into account, since they might have serious implications. This paper presents the arguments in support of the case for the maintainability of the design, notably if this maintenance is to be performed by advanced remote methods. This structure is compliant to the evolving maintenance strategy of ITER. Initial results of a Failure Mode Effects and Criticality Analysis (FMECA) and a development risk analysis for the ITER upper port plug #3, housing the Charge Exchange Recombination Spectroscopy (CXRS) diagnostic, are employed for the definition of the maintenance strategy. The CXRS upper port plug is essentially an optical system which transfers visible light from the plasma into a fiber bundle. The most critical component in this path is the first mirror (M1) whose reflectivity degrades during operation due to deposition and/or erosion dominated effects. Amongst other measures to mitigate these effects, the strategy is to allow for a replacement of this mirror. Therefore it is mounted on a retractable central tube. The main purpose of this tube is to make frequent replacements possible without hindering operation. The maintenance method in terms of time, geometry and spare part policy has a large impact on cost of the system and time usage in the hot cell. Replacement of the tube under vacuum and magnetic field seems infeasible due to the operational risk involved. The preferred solution is to have a spare tube available which is replaced in parallel with other maintenance operations on the vessel, as to avoid any interference in the hot cell with the shutdown scheduling. This avoids having to refurbish a full port plug and also allows for a more frequent replacement of M1, as we can replace the mirror anytime the vacuum vessel is vented, estimated to be once a year. (C) 2009 Elsevier B.V. All rights reserved

Sorption-based vibration-free cooler for the METIS instrument on E-ELT

METIS is the 'Mid-infrared ELT Imager and Spectrograph' for the European Extremely Large Telescope. This E-ELT instrument will cover the thermal/mid-infrared wavelength range from 3 to 14 &#956;m and will require cryogenic cooling of detectors and optics. We present a vibration-free cooling technology for this instrument based on sorption coolers developed at the University of Twente in collaboration with Dutch Space. In the baseline design, the instrument has four temperature levels: N-band: detector at 8 K and optics at 25 K; L/M-band: detector at 40K and optics at 77 K. The latter temperature is established by a liquid nitrogen supply with adequate cooling power. The cooling powers required at the lower three levels are 0.4 W, 1.1 W, and 1.4 W, respectively. The cryogenic cooling technology that we propose uses a compressor based on the cyclic adsorption and desorption of a working gas on a sorber material such as activated carbon. Under desorption, a high pressure can be established. When expanding the high-pressure fluid over a flow restriction, cooling is obtained. The big advantage of this cooling technology is that, apart from passive valves, it contains no moving parts and, therefore, generates no vibrations. This, obviously, is highly attractive in sensitive, high-performance optical systems. A further advantage is the high temperature stability down to the mK level. In a Dutch national research program we aim to develop a cooler demonstrator for METIS. In the paper we will describe our cooler technology and discuss the developments towards the METIS cooler demonstrato