Numerical and experimental studies of the natural convection within a horizontal cylinder

Numerical solutions are obtained for the quasi-compressible Navier-Stokes equations governing the time-dependent natural convection within a horizontal cylinder. The early flow development and wall heat transfer are obtained after a uniformly cold wall is imposed as a boundary condition on the cylinder. Results are also obtained for a time-varying cold wall as a boundary condition with windward explicit differencing used for the numerical solutions. The viscous truncation error associated with this scheme is controlled so that first-order accuracy is maintained in time and space. Experiments within a small-scale instrumented horizontal cylinder revealed the time development of the temperature distribution across the boundary layer as well as the decay of wall heat transfer with time. Agreement between temperature distributions obtained experimentally and numerically was generally good. The time decay of the dimensionless ratio of the Nusselt number to the one-fourth power of the Grashof number is found both numerically and experimentally, and good agreement is obtained between these two results over most of the cylinder wall

Justice System Disparities: Black-White National Imprisonment Trends, 2000 to 2020

Although significant gaps remain, disparities between Black and White people continued to narrow at nearly every stage of the criminal justice process between 2016 and 2020. In some cases, the pace of the decline slowed; in others, the disparity gap closed entirely.These trends extend patterns from 2000 to 2016 that were identified in CCJ's first report on correctional control by race and sex. Subsequent reports will explore trends in disparity among female populations and by ethnicity, assess trends in multiple states, and seek to identify what, if any, policy changes may have contributed to reductions in racial disparities

Robbery, Recidivism, And The Limits Of The Criminal Justice System

The roughly 175,000 convicted robbers currently serving time in the U.S. eventually will be released. Over half of them will have been there before. Locked up as mostly young men and women, they will return to the communities they left behind, possessing little more than a criminal record and the clothes on their back. Many will find themselves owing supervision fees to the state; almost all will face legal barriers to employment, decent housing, political participation, and other sources of social inclusion. What can the criminal justice system—a system designed to prevent and deter lawbreaking— realistically do to keep them from returning to prison? This Article explores that question by drawing on published accounts from a sample of 86 individuals actively involved in committing armed robberies, many of whom have returned to crime after being released from prison. The emphasis throughout is on the ways in which pervasive social exclusion, both a cause and a consequence of their lawbreaking, challenges our ability to “reintegrate” such offenders who in reality were not integrated to begin with

Trends in Correctional Control by Race and Sex

American prison populations have long been characterized by racial and ethnic disparities. U.S. Census Bureau data on incarcerated persons from 1870 through 1980 show that black incarceration rates ranged from three to nine times those of whites, depending upon the decade and region of the country.In recent years, racial disparities in imprisonment have decreased. This Council on Criminal Justice report updates and advances earlier presentations of data on disparities

Training Collaboration in a Network-Assisted Environment

Technology enabled non-face-to-face collaboration has the potential to enhance information sharing and shared situational awareness (SSA) by providing near real-time information to a wide audience. Collaborators require an awareness of what critical information should be shared to develop this SSA. Previous research suggested that participants, while reporting that they shared relevant information, in actuality did not. To explore this issue, the previous research was repeated with the addition of having half of the participants exposed to a short training video on how to collaborate. Participants who received training on how to collaborate located significantly more SCUDs during each of the five turns of the two games played. Similarly, participants who received collaboration training scored higher on shared situational awareness during every turn played. Overall, those receiving the training on collaboration shared information more often with their partners and these information exchanges were longer than those who had not received the training. As technology advances, there is an increased need to understand how humans collaborate at a distance. Findings from this research advance our knowledge of how to enhance non-face-to-face collaboration. SCUDHunt, an on-line game developed by Thoughtlink Inc., was selected for this research on collaboration because it provides a simplified model of the interplay of shared awareness and collaboration, while permitting independent manipulation of variables thought to affect them. SCUDHunt requires participants to do the following: (1) collaborate from distributed locations, and (2) share unique information from their intelligence assets for optimal game performance. The goal of the game is simple: locate three SCUD missile launchers on a map. The game requires geographically dispersed players to collaborate while executing digital tasks to achieve a shared goal

Performance in Non-Face-to-Face Collaborative Information Environments

Using technology to obtain and process information requires training not only in human-computer interaction but also in human-human-computer (collaborative) interaction. Warfighters must not only develop their own situational awareness (SA), they must understand each others’ SA (Pew, 1995). This common ground is what each collaboration participant assumes about the others to ensure effective interactions (Ross, 2003; Wellons, 1993). Communication is key. Collaborators must coordinate and share information. Collaboration influences military operations at all levels. Technical interoperability is not enough to produce the synchronization required

Revisiting the method to obtain the mechanical properties of hydrided fuel cladding in the hoop direction

The method reported in the literature to calculate the stress–strain curve of nuclear fuel cladding from ring tensile test is revisited in this paper and a new alternative is presented. In the former method, two universal curves are introduced under the assumption of small strain. In this paper it is shown that these curves are not universal, but material-dependent if geometric nonlinearity is taken into account. The new method is valid beyond small strains, takes geometric nonlinearity into consideration and does not need universal curves. The stress–strain curves in the hoop direction are determined by combining numerical calculations with experimental results in a convergent loop. To this end, ring tensile tests were performed in unirradiated hydrogen-charged samples. The agreement among the simulations and the experimental results is excellent for the range of concentrations tested (up to 2000 wppm hydrogen). The calculated stress–strain curves show that the mechanical properties do not depend strongly on the hydrogen concentration, and that no noticeable strain hardening occurs. However, ductility decreases with the hydrogen concentration, especially beyond 500 wppm hydrogen. The fractographic results indicate that as-received samples fail in a ductile fashion, whereas quasicleavage is bserved in the hydrogen-charged samples

Addressing Barriers to Housing in Reentry Programs Working to Address a Variety of Needs: A Qualitative Study of Second Chance Act Grantees

Using data from an evaluation of three Second Chance Act grantees, we explore formerly incarcerated people’s (FIP) access to housing. This study is unique in that it includes the perspectives of individuals with lived experiences and the insights of the reentry program providers working to meet their overall needs, including in the area of housing. The data come from reentry programs in three regions of the United States. Although the needs of the people with lived experiences have similarities, regional differences exist, particularly related to housing costs and supply, including the availability of transitional housing. Also, variations exist between FIP who are able to live with family compared with those who do not have this option. The three programs this study examined worked to address housing needs in distinctive ways and explores the housing needs of FIP and the strategies the three programs use to address these needs. Incorporating a two-pronged approach, this article includes analyses of (1) interview data with 31 FIP from 3 months to 3 years post-incarceration and (2) interviews and program materials to support formulative case analyses of the housing-related work that program enacted. Through this work, highlighting program efforts to remove barriers to housing for this population, the study seeks to promote the advancement of relevant policy, practice, and research in this arena