Electric Field Determination in DC Polymeric Power Cable in the Presence of Space Charge

The pulsed electroacoustic (PEA) technique was used to perform space charge measurements in polymeric power cables. However, for a practical dc power cable the electric field is affected by conductivity of the material, which is a function of both temperature and electric field. The coupled problems inflict difficulties to identify the electric field distribution in high voltage (HV) cables, which therefore poses threat to the reliability in operation of dc power cables. In this paper we proposed a method of determining electric field distribution in XLPE power cable, where under temperature gradient the existence of space charge density of the cable is determined by means of a modified PEA system. Commercial 11 kV ac XLPE power cable is applied and measured under an applied dc voltage of 80 kV. The space charge across the insulation was obtained and COMSOL Multiphysics software package is used to accurately determine the electric field distribution in the dc power cable by considering the influences of both the effects of temperature and electric field on the conductivity of the insulating material. Therefore, the results of the numerical modelling shall give us a clearer representation of the electric field distribution in HVDC cables

Space charge accumulation under the effects of temperature gradient on solid dielectric DC cable

It is well known that existence and accumulation of space charge within the insulating material poses threat to the reliability in the operation of dc power cables. When the cables are loaded under high voltage direct current (HVDC), temperature gradient is developed across the insulation material. In this paper, commercial ac XLPE power cables were used under an application voltage of 80 kV dc with different temperature gradients loaded between the insulating material. Space charge distributions were then measured across the insulation of the cable by means of a modified pulsed electroacoustic (PEA) system with a current transformer attached. Therefore, a replica of a power cable under load conditions could be obtained, which allows us to investigate the formation, migration and accumulation of space charges in a power cable both without and with different temperature gradients consideration across the bulk of the insulating material. Discussion will be made thoroughly in order to understand the space charge phenomenon of power cable under its service temperature

Space Charge Accumulation under Effects of Temperature Gradient and Applied Voltage Reversal on Solid Dielectric DC Cable

A well-known fact of the existence and accumulation of space charge within the insulating material poses threat to the reliability in the operation of dc power cables. When power cables are loaded under high voltage direct current (HVDC), temperature gradient is developed across the insulation. Results of space charge evolution in commercial ac XLPE power cables under an application of 80 kV dc supply at different temperature gradients and during external voltage reversal are discussed in this paper. The space charge distributions were measured across the insulation of the cable by means of a modified pulsed electroacoustic (PEA) system with a current transformer attached. Therefore, a replica of a power cable under load conditions could be obtained, which allows us to investigate the formation, migration and accumulation of space charges in a power cable both without and with different temperature gradients consideration across the bulk of the insulating material during voltage reversal. Discussion will be made thoroughly in order to understand the space charge phenomenon of power cable under its service temperature as space charge accumulation during polarity reversal plays an important factor on the electric field distribution within the insulation material

Methods leading to best outcomes for elderly patients presenting with chest pain in emergency departments.

Abstract Background: Hospitals today currently face many health disparities among patients. There are many factors that contribute to these health disparities such as the decision-making process. Objective: The goal of this systematic review was to identify how computerized risk prediction models compared to a set of decision rules influence health outcomes during emergency room stay of older adult patients with chest pain. Method: We searched databases such as, CINAHL, EBSCOHost, and PubMed to identify barriers influencing health outcomes of older adults with chest pain in the emergency department. Results: There were seven articles included in the review indicating the effectiveness and reduction of the delay in the management of chest pain among older adult patients in the emergency room when decision making models are available. Conclusion: With the use of a computerized risk prediction for elderly patients with chest pain proved to be more reliable and effective with time and treatment

Information seeking, use, and decision making

YesIn this paper we explored three areas: decision making and information seeking, the relationship between information seeking and uncertainty, and the role of expertise in influencing information use. This was undertaken in the context of a qualitative study into decision making in the initial stages of emergency response to major incidents. The research took an interpretive approach in which activity theory is used as an analytical framework. The research provides further evidence that the context of the activity and individual differences influence the choice of decision mode and associated information behavior. We also established that information is often not used to resolve uncertainty in decision making and indeed information is often sought and used after the decision is made to justify the decision. Finally, we point to the significance of both expertise and confidence in understanding information behavior. The contribution of the research to existing theoretical frameworks is discussed and a modified version of Wilson's problem-solving model is proposed

Does sex education before college protect students from sexual assault in college?

Purpose College-bound young people experience sexual assault, both before and after they enter college. This study examines historical risk factors (experiences and exposures that occurred prior to college) for penetrative sexual assault (PSA) victimization since entering college. Methods A cross-sectional study, including an online population-based quantitiative survey with undergraduate students was conducted in spring 2016. Bivariate analyses and multivariable regressions examined risk and protective factors associated with ever experiencing PSA since entering college. Concurrently-collected in-depth ethnographic interviews with 151 students were reviewed for information related to factors identified in the survey. Results In bivariate analyses, multiple historical factors were significantly associated with PSA in college including adverse childhood experiences and having experienced unwanted sexual contact before college (for women) and initiation of alcohol, marijuana, and sexual behaviors before age 18. Significant independent risk factors for college PSA included female gender, experiencing unwanted sexual contact before college, first oral sex before age 18, and “hooking up” (e.g., causual sex or sex outside a committed partnership) in high school. Receipt of school-based sex education promoting refusal skills before age 18 was an independent protective factor; abstinence-only instruction was not. In the ethnographic interviews, students reported variable experiences with sex education before college; many reported it was awkward and poorly delivered. Conclusions Multiple experiences and exposures prior to college influenced the risk of penetrative sexual assault in college. Pre-college comprehensive sexuality education, including skills-based training in refusing unwanted sex, may be an effective strategy for preventing sexual assault in college. Sexual assault prevention needs to begin earlier; successful prevention before college should complement prevention efforts once students enter college

SmaggIce Version 1.8

SmaggIce version 1.8 is a set of software tools for geometrical modeling of, and generation of grids that conform to, both clean and iced airfoils. Ice shapes, especially those that include rough surfaces, pose difficulty in generating high-quality grids that are essential for predicting airflows by use of computational fluid dynamics. SmaggIce version 1.8 contains software tools needed to overcome this difficulty. For a given airfoil, it allows the user to define the flow domain, decompose the domain into blocks, generate grids, merge gridded blocks, and control the density and smoothness of each grid. Among the unique features of version 1.8 is a thin C-shaped block, called a "viscous sublayer block," which is wrapped around an iced airfoil and its wake line and serves as a means to generate highly controlled grids near the rough ice surface. Users can modify block boundary shapes using control points of non-uniform rational B-spline (NURBS) curves. Concave ice regions can be smoothed during geometrical modeling or creation of the viscous sublayer block