2,615 research outputs found
New features and applications of PRESTO, a computer code for the performance of regenerative, superheated steam turbine cycles
The code was designed to analyze performance at valves-wide-open design flow. The code can model conventional steam cycles as well as cycles that include such special features as process steam extraction and induction and feedwater heating by external heat sources. Convenience features and extensions to the special features were incorporated into the PRESTO code. The features are described, and detailed examples illustrating the use of both the original and the special features are given
Implementation of control point form of algebraic grid-generation technique
The control point form (CPF) provides explicit control of physical grid shape and grid spacing through the movement of the control points. The control point array, called a control net, is a space grid type arrangement of locations in physical space with an index for each direction. As an algebraic method CPF is efficient and works well with interactive computer graphics. A family of menu-driven, interactive grid-generation computer codes (TURBO) is being developed by using CPF. Key features of TurboI (a TURBO member) are discussed and typical results are presented. TurboI runs on any IRIS 4D series workstation
Dynamics of axial separation in long rotating drums
We propose a continuum description for the axial separation of granular
materials in a long rotating drum. The model, operating with two local
variables, concentration difference and the dynamic angle of repose, describes
both initial transient traveling wave dynamics and long-term segregation of the
binary mixture. Segregation proceeds through ultra-slow logarithmic coarsening.Comment: 4 pages, 3 Postscript figures; submitted to PR
Recommended from our members
Patient-Related Barriers to Timely Dialysis Access Preparation: A Qualitative Study of the Perspectives of Patients, Family Members, and Health Care Providers
Rational & Objective
A key aspect of smooth transition to dialysis is the timely creation of a permanent access. Despite early referral to kidney care, initiation onto dialysis is still suboptimal for many patients, which has clinical and cost implications. This study aimed to explore perspectives of various stakeholders on barriers to timely access creation.
Study Design
Qualitative study.
Setting & Participants
Semi-structured interviews with 96 participants (response rate, 67%), including patients with stage 4 chronic kidney disease (n = 30), new hemodialysis patients with (n = 18) and without (n = 20) permanent access (arteriovenous fistula), family members (n = 19), and kidney health care providers (n = 9).
Analytical Approach
Thematic analysis.
Results
Patients reported differential levels of behavioral activation toward access creation: avoidance/denial, wait and see, or active intention. 6 core themes were identified: (1) lack of symptoms, (2) dialysis fear and practical concerns (exaggerated fear, pain, cost, lifestyle disruptions, work-related concerns, burdening their families), (3) evaluating value against costs/risks of access creation (benefits, threat of operation, viability, prompt for early initiation), (4) preference for alternatives, (5) social influences (hearsay, family involvement, experiences of others), and (6) health care provider interactions (mistrust, interpersonal tension, lack of clarity on information). Themes were common to all groups, whereas nuanced perspectives of family members and health care providers were noted in some subthemes.
Limitations
Response bias.
Conclusions
Individual, interpersonal, and psychosocial factors compromise dialysis preparation and contribute to suboptimal dialysis initiation. Our findings support the need for interventions to improve patient and family engagement and address emotional concerns and misperceptions about preparing for dialysis
Impact and key challenges of insider threats on organizations and critical businesses
The insider threat has consistently been identified as a key threat to organizations and governments. Understanding the nature of insider threats and the related threat landscape can help in forming mitigation strategies, including non-technical means. In this paper, we survey and highlight challenges associated with the identification and detection of insider threats in both public and private sector organizations, especially those part of a nation’s critical infrastructure. We explore the utility of the cyber kill chain to understand insider threats, as well as understanding the underpinning human behavior and psychological factors. The existing defense techniques are discussed and critically analyzed, and improvements are suggested, in line with the current state-of-the-art cyber security requirements. Finally, open problems related to the insider threat are identified and future research directions are discussed
Raman spectroscopy of human teeth using integrated optical spectrometers
We have designed an arrayed-waveguide grating in silicon oxynitride technology for the detection of Raman signals from tooth enamel in the spectral region between 890 nm and 912 nm. The detected signals for both parallel and cross polarizations are used to distinguish between healthy and carious regions on the tooth surface of extracted human teeth. Our experimental results are in very good agreement with those achieved using conventional Raman spectrometers. Our results represent a step toward the realization of compact, hand-held, integrated spectrometers
Thermophysical and elastic properties of Cu50Zr50 and (Cu50Zr50)95Al5 bulk-metallic-glass-forming alloys
By employing a containerless high-temperature high-vacuum electrostatic levitation technique, the thermophysical properties, including the ratio between the specific heat capacity and the hemispherical total emissivity, the specific volume, and the viscosity, of Cu50Zr50 and (Cu50Zr50)95Al5 bulk-metallic-glass (BMG)-forming liquids have been measured. Compared with Cu50Zr50, the improved glass-forming ability of (Cu50Zr50)95Al5 can be attributed to its dense liquid structure and its high value of viscosity. Additionally, the relationship between the viscosity of various BMG forming liquids at the melting temperature and the elastic properties of the corresponding glasses at room temperature will be compared
Chemical Raman Enhancement of Organic Adsorbates on Metal Surfaces
Using a combination of first-principles theory and experiments, we provide a
quantitative explanation for chemical contributions to surface-enhanced Raman
spectroscopy for a well-studied organic molecule, benzene thiol, chemisorbed on
planar Au(111) surfaces. With density functional theory calculations of the
static Raman tensor, we demonstrate and quantify a strong mode-dependent
modification of benzene thiol Raman spectra by Au substrates. Raman active
modes with the largest enhancements result from stronger contributions from Au
to their electron-vibron coupling, as quantified through a deformation
potential, a well-defined property of each vibrational mode. A straightforward
and general analysis is introduced that allows extraction of chemical
enhancement from experiments for specific vibrational modes; measured values
are in excellent agreement with our calculations.Comment: 5 pages, 4 figures and Supplementary material included as ancillary
fil
- …