Perceived discrimination in Topeka, Kansas

Objective, This study describes perceived discrimination in Topeka, Kansas, Methods.  A 21 item survey questionnaire shows perceived levels of discrimination and the nature and type of discrimination experienced by citizens. Nine focus groups were conducted by the researchers to better understand the nature of discrimination in this community. Conclusions, A significant portion of participants experience some form of discrimination. Data from both survey responses and focus groups reveal that discrimination is experienced across all population groups. The findings convey a sense of victimization and a strong sentiment that it is an active undercurrent within this community. These findings suggest that community leaders need to be cognizant of community perceptions of discrimination as they prepare for the 50th anniversary of Brown vs. Topeka Board of Education

Two-phase anaerobic digestion in leach bed reactors coupled to anaerobic filters: A review and the potential of biochar filters

Biochar addition in anaerobic digesters is an emerging technique for enhancing high-solids anaerobic digestion. Recycling of biochar can further enhance performance and reduce costs for biochar production; however, mixing biochar with feedstock and separating from digestate is impractical. A more pragmatic method of applying biochar for high-solids digestion could be coupling a leach bed reactor (LBR) with a biochar-packed anaerobic filter (AF) to form a two-phase system. Separating the anaerobic digestion process between reactors can improve process efficiency by enhancing hydrolysis and acidogenesis in the LBR and producing higher quality biogas in the AF. However, two-phase systems can be inefficient if separation of the anaerobic digestion process between reactors – referred to as phase separation – is poor. This article aims to: (i) integrate current knowledge from literature investigating batch LBR-AF systems to improve understanding of the role of different process parameters on phase separation and process efficiency; and (ii) explore the idea of biochar as a filter medium in an LBR-AF system. Feedstocks that rapidly degrade and have ongoing VFA production are particularly suitable for phase separation in LBR-AF systems. Controllable process parameters identified as critical for phase separation and process inhibitor mitigation include co-digestion, recirculation parameters, filter media properties, inoculation method and temperature. The application of biochar in other systems highlights the potential for LBR-AF application. Future research should consider trade-offs between biogas production and digestate quality when optimising LBR-AF performance, and assess economic viability considering the additional expenses of LBR-AF systems.B.A. Collins, C.H. Birzer, P.W. Harris, S.P. Kidd, B.K. McCabe, P.R. Medwel

The Structure and Delivery of Police Use of Force Training: A German Case Study

The current study aims to investigate the current structure and delivery of police recruit training. Using a case study approach, we systematically observed a semester of police training that consisted of 30 h with a specific focus on police use of force training. Field notes and time-on-task data was analysed using an inductive approach. The results revealed, first, a lack of constructive alignment of the training modules and learning tasks within the training settings. Second, an adherence to traditional linear approaches to training resulting in high amounts of augmented instruction and feedback and a one-size-fits all approach to technical and tactical behaviour. Third, a non-efficient use of available training time with low amounts of engagement in representatively designed tasks that stimulated problem-solving processes. Based on these results we suggest that there is a need: (a) for police trainers and curriculum designers to align the objectives, practice structure and delivery of police training with the needs of police officers in the field (e.g. conflict resolution); (b) for police trainers to employ more learner-centred pedagogical approaches that account for individual action capabilities and resources, and allow for high amounts of training time with representatively designed training tasks; and (c) for senior managers of overall police training decision-makers to provide the necessary trainer education, in order to furnish trainers with the knowledge and tools to appropriately plan, deliver and reflect upon their practice in keeping with concept of constructive alignment

Flame structure of jets in confined crossflows

C. H. Birzer, R. M. Kelso and B. B. Dall

Turbulent jet flames under hot coflow conditions

Turbulent jet flames have been under intense investigation for many years. These investigations covered classical topics such as jet spread and decay, flame volume, emission and radiation. More effort was also dedicated to understand the interaction between the turbulence and the chemical kinetics, its impact on flame structure, stability and emission of pollutants. Over the last decade, interest has shifted to jet flames propagating in different coflow environments which are found in practical combustion systems. The temperature, composition and oxygen levels of these coflows have a major impact on the global and local features of these flames. This paper reports a comparison of the difference in fuel mixing rates emerging from a round jet propagating into a hot medium. Such flows include jet in a hot coflow, piloted jet flames, and bluff body flames. The key differences between these and standard flames are reviewed, and the mixing rates are presented and discussed.B.B. Dally, C.H. Birzer and P.R. Medwellhttp://www.2011australiancombustionsymposium.com

Scaling trajectories for jets in confined cross-flows

In a non-premixed flame, the mixing of fuel emerging from a jet burner with quiescent air plays a dominant role in the combustion process. The use of radial injectors upstream of the nozzle exit can be used to increase boundary layer turbulence, and thereby enhancing the mixing of fuel and air. In the current paper, a single side jet entering radially into a pipe is investigated experimentally using planar laser induced fluorescence (PLIF). This configuration is variant of a jet in cross-flow (JICF), although the cross-flow generated by the central pipe is confined cross-flow. Therefore, the walls of the pipe may influence the side-jet and the existing knowing of JICF may not extend completely to the confined cross-flow environment. In the current paper the penetration of a side jet into the pipe flow is assessed and a new scaling parameter is determined. Scaling the depth by r0.75D, where r is the velocity ratio and D is the central pipe diameter, is proposed and compared with conventional scaling for JICF (rD and r2D). The results indicate the proposed scaling produces in a very good collapse of data onto a single line for non-laminar side jet emerging into turbulent flows.C.H. Birzer, B.B. Dally and R.M. Kelsohttp://www.acldfmc.org

Mixing field characteristics of multi-lateral jets injected into a round pipe flow

Jet in cross-flow is a well-studied and characterised fluid-mixing phenomenon. In several combustion applications, the use of laterally placed side-jets can be used to produce jets into a confined cross-flow (JICCF). These flows can be expected to have similar mixing as the traditional jet in cross-flow cases and therefore provide a potentially cost-effective means of optimising a combusting jet flow. However, there are limits to the data currently available on the fundamentals of JICCF. Hence, the current study investigates the flow structures formed in a round pipe flow modified by four equi-spaced side jets. Non-reacting, isothermal experiments are conducted in water on a central nozzle with four smaller jets located one central diameter upstream of the nozzle exit plane. The induced flow structures are visualised using Planar Laser Induced Fluorescence (PLIF). The operating conditions are varied to explore the role of jet injection to primary flow ratio, whilst the bulk flow rate is maintained at a constant level. The analysed data identify the formation of various flow regimes as the relative momentum-flux ratio induced via side jet injection is increased. The behaviour of the side jets within the main jet is substantially different from similar side-jet injection into an unconfined flow. The results show that several flow regimes can be discerned, namely: a non-impinging flow; impinging flow with no backflow; and impinging flow with backflow. It is found that the mixing trends and resulting regimes have consequences for the emerging nearfield mixedness.C.X. Thong, P.A.M. Kalt, B.B. Dally, C.H. Birze

Flow dynamics of multi-lateral jets injection into a round pipe flow

Controlling the mixing field of turbulent jets is an important approach in optimizing practical combustion systems. The use of multi-lateral jets upstream from the nozzle exit to control mixing fields is one particular method. Existing studies have investigated jets into a confined cross-flow (JICCF) for dilution mixing, but there is a paucity of data available on the fundamentals for turbulent mixing capabilities of JICCF. The current study investigates the flow structures and Primary Reynolds number mixing characteristics within a round pipe flow modified by four equi-spaced, lateral side injectors. Experiments are conducted in a primary water jet flow that is modified with smaller jets located one central (axial) jet diameter upstream of the nozzle exit. Flow structures and mixing within the nozzle are non-intrusively characterized using simultaneous planar optical techniques. Planar laser-induced fluorescence is used to measure the scalar mixing of the side and axial jet streams, and particle imaging velocimetry is used to measure the planar velocities. Several cases are investigated with variable primary flow to explore the influence of cross-flow velocity on the induced mixing structures within the nozzle. By varying the momentum ratio, three characteristic flow modes are identified within the primary flow, namely streaming mode, impinging mode, and backflow mode. The impact of these modes on the flow and scalar fields is presented and discussed.Chia X. Thong, Peter A. M. Kalt, Bassam B. Dally, Cristian H. Birze