Shear wave structure of a transect of the Los Angeles basin from multimode surface waves and H/V spectral ratio analysis

We use broad-band stations of the ‘Los Angeles Syncline Seismic Interferometry Experiment’ (LASSIE) to perform a joint inversion of the Horizontal to Vertical spectral ratios (H/V) and multimode dispersion curves (phase and group velocity) for both Rayleigh and Love waves at each station of a dense line of sensors. The H/V of the autocorrelated signal at a seismic station is proportional to the ratio of the imaginary parts of the Green’s function. The presence of low-frequency peaks (∼0.2 Hz) in H/V allows us to constrain the structure of the basin with high confidence to a depth of 6 km. The velocity models we obtain are broadly consistent with the SCEC CVM-H community model and agree well with known geological features. Because our approach differs substantially from previous modelling of crustal velocities in southern California, this research validates both the utility of the diffuse field H/V measurements for deep structural characterization and the predictive value of the CVM-H community velocity model in the Los Angeles region. We also analyse a lower frequency peak (∼0.03 Hz) in H/V and suggest it could be the signature of the Moho. Finally, we show that the independent comparison of the H and V components with their corresponding theoretical counterparts gives information about the degree of diffusivity of the ambient seismic field

Evaluation of a hybrid hydrostatic bearing for cryogenic turbopump application

A hybrid hydrostatic bearing was designed to operate in liquid hydrogen at speeds to 80,000 rpm and radial loads to 440 n (100 lbf). The bearing assembly consisted of a pair of 20-mm angular-contact ball bearings encased in a journal, which was in turn supported by a fluid film of liquid hydrogen. The size and operating conditions of the bearing were selected to be compatible with the operating requirements of an advanced technology turbopump. Several test parameters were varied to characterize the bearing's steady-state operation. The rotation of the tester shaft was varied between 0 and 80,000 rpm. Bearing inlet fluid pressure was varied between 2.07 and 4.48 MPa (300 and 650 psia), while the fluid sump pressure was independently varied between 0.34 and 2.07 MPa (50 and 300 psia). The maximum radial load applied to the bearing was 440 N (110 lbf). Measured hybrid-hydrostatic-bearing stiffness was 1.5 times greater than predicted, while the fluid flow rate through the bearing was 35 to 65 percent less than predicted. Under two-phase fluid conditions, the stiffness was even greater and the flow rate was less. The optimal pressure ratio for the bearing should be between 0.2 and 0.55 depending on the balance desired between bearing efficiency and stiffness. Startup and shutdown cyclic tests were conducted to demonstrate the ability of the hybrid-hydrostatic-bearing assembly to survive at least a 300-firing-duty cycle. For a typical cycle, the shaft was accelerated to 50,000 rpm in 1.8 sec. The bearing operated for 337 start-stop cycles without failure

Development program for 35 watt traveling-wave tube space amplifier Final report, 30 Jun. 1967 - 30 Sep. 1969

Development of 35-watt, S band, traveling wave tube amplifier for Saturn 5 instrument uni

Hospital environment as a reservoir for cross transmission. Cleaning and disinfection procedures

Background. Healthcare associated infections (HAIs) represent a serious problem for public health, as they increase the morbidity and mortality rates, present a relevant financial burden, and significantly contribute to the antimicrobial resistance. Methods. The aim of this review was to investigate the literature about HAIs, with particular reference to hospital environments and the role of cleaning and disinfection procedures. Hospital environments are an essential reservoir for HAIs cross transmission, and the application of appropriate procedures related to hand hygiene and disinfection/sterilization of surfaces and instruments remain key strategies for controlling HAIs. Results. Different procedures, based on the risk associated with the healthcare procedure, are recommended for hand hygiene: washing with soap and water, antiseptic rubbing with alcohol-based disinfectants, antiseptic and surgical hand washing. Environmental surfaces can be treated with different products, and the mostly used are chlorine-based and polyphenolic disinfectant. The reprocessing of instruments is related to their use according to the Spaulding's classification. In addition, scientific evidence demonstrated the great relevance of the "bundles" (small set of practices performed together) in controlling HAIs. Conclusions. Research agenda should include the improvement of well-known effective preventive procedures and the development of new bundles devoted to high-risk procedures and specific microorganisms

Active Structure from Motion for Spherical and Cylindrical Targets

International audienceStructure estimation from motion (SfM) is a classical and well-studied problem in computer and robot vision, and many solutions have been proposed to treat it as a recursive filtering/estimation task. However, the issue of actively optimizing the transient response of the SfM estimation error has not received a comparable attention. In this paper, we provide an experimental validation of a recently proposed nonlinear active SfM strategy via two concrete applications: 3D structure estimation for a spherical and a cylindrical target. The experimental results fully support the theoretical analysis and clearly show the benefits of the proposed active strategy. Indeed, by suitably acting on the camera motion and estimation gains, it is possible to assign the error transient response and make it equivalent to that of a reference linear second-order system with desired poles

Sicurezza dell’acqua negli edifici. Traduzione italiana.

Una delle sfide maggiori in ambito sanitario è la gestione dell’acqua negli edifici, spesso trascurata. In molti paesi e regioni, la gestione dell’acqua negli edifici non rientra nelle responsabilità dell’azienda acquedottistica. Per gli edifici generalmente non vengono applicati i cosiddetti Piani di Sicurezza per l’Acqua per la gestione dell’acqua pubblica. Questo testo, traduzione italiana del volume Water Safety in Buildings, fa parte della serie dei documenti di supporto che forniscono indicazioni sull’attuazione delle Linee guida per la qualità dell’acqua potabile dell’Organizzazione Mondiale della Sanità. Può essere un utile supporto per il controllo e il miglioramento della qualità e della sicurezza dell’acqua negli edifici

Inclusive Access: A multi-institutional study of academic outcomes from a statewide community college automatic billing eTextbook pilot

In response to issues related to the high cost of textbooks and other course materials, Inclusive Access programs allow the cost of a discounted eTextbook and/or courseware to be automatically added to a student’s tuition bill at the time of course registration (McKenzie, 2017). Touted for their ability to lower costs and provide students with access to materials on or before the first day of class, automatic billing programs have become increasingly prolific across the higher education landscape. At the same time, research into many aspects of the program’s impact and efficacy remains lacking. This study examined academic outcomes from an Inclusive Access pilot launched fall 2019 by Tennessee’s largest system of public higher education. Results from across 13 community colleges, 41 course areas, and 141 courses indicated no significant differences in either overall or population-specific academic outcomes between the Inclusive Access pilot semester and the two prior falls in which the courses were taught. The findings demonstrate that benefits accrued from relative cost-savings and/or Day One Access were insufficient to produce significant improvements in academic outcomes, with no significant differences in outcomes also evidenced for non-White, federal Pell grant award recipients, and/or non-traditional students over the age of 25. These results suggest that measures beyond cost-savings and Day One access, such as hidden costs, the need for perpetual access, and the ultimate repercussions of deferred costs to student debt, should also be considered when evaluating ways to provide students with affordable course materials that enable high-quality, equitable learning experiences