Search results

The purpose of this paper is to study turbulent flow separation at the airfoil trailing edge. This work aims to improve the knowledge of stall phenomenon by creating a QDNS database for the NACA412 airfoil.

Quasi-DNS simulations of the NACA 4412 airfoil in pre-stall conditions have been completed. The Reynolds number based on airfoil chord and freestream velocity is equal to 0.35 million, and the freestream Mach number to 0.117. Transition is triggered on both surfaces for avoiding the occurrence of laminar separation bubbles and to ensure turbulent mixing in the wake. Four incidences have been considered, 5, 8 10 and 11 degrees.

The results obtained show a reasonably good correlation of the present simulations with classical MSES airfoil simulations and with RANS computations, both in terms of pressure and skin-friction distribution, with an earlier and more extended flow separation in the QDNS. The database thus generated will be deeply analysed and enriched for larger incidences in the future.

No experimental or HPC numerical database at reasonable Reynolds number exists in the literature. The current work is the first step in that direction.

This case presents the history and recent governance challenges of Carvajal, S.A., a Colombia-based, family-owned, billion-dollar-plus holding company that had offered printing-related (e.g., Yellow Pages, notebooks) and other products and services across and beyond South America for more than a century. Specifically, the case details the company’s state of affairs in early 2011, a time by which Carvajal’s flagship businesses had matured rapidly with the emergence of digital technology and diminished demand for paper/print-based products. Though profits and growth remained positive, Carvajal’s leaders knew that upholding the business’s legacy of returns, dividends for all family members, and extensive philanthropy would take significant strategy and execution.

Compounding the strategy issues, Carvajal faced these market challenges with new leadership: the first non-family CEO since the company’s inception. Well-established Colombian executive Ricardo Obregon had been hired in 2008 over two family candidates to lead the business. Obregon was to oversee a complex governance network that included a holding company with seven operating companies, their management and respective boards, a family council, and 280 members (including spouses) of a shareholding family in its sixth generation. Carvajal’s business and family leaders had to face market issues and decisions that included the possibility of taking public the operating companies and/or the holding company while maintaining the business’s long traditions of unity, respect, strong ethics, and philanthropy. That meant optimizing several crucial relationships: between the family and the new CEO; between the family and the board; between the operating companies and the holding company; and between members of the large Carvajal family, many of whom now resided outside of Colombia and Latin America.

Understand general and specific challenges associated with carrying on a longstanding family business facing multiple market challenges; explore the process of engaging a complex family-business governance network to handle business challenges while maintaining family values; consider the effects of culture on a multi-generation family business.

The continuing economic recession throughout Western Europe (and not just the UK, as some media reports imply) has necessitated in predictions for the future demand for paint over the next decade to be revised downwards. A new report from Information Research Ltd. states that it is now expected that the average growth rate for the years ahead will be around 2% per annum, so that the present usage of just over 4.70 m tons will increase to around 5.16 m tons by 1985 and to 5.67 m tons by the end of the decade.

Seeking to build an objective scientific approach to psychiatry, American psychiatrists, physiologists, and psychologists began to turn to the conditional reflex method of Ivan Pavlov from the late 1920s. The generation of “neurotic” animals in the laboratory was critical to the emergence of a new experimental psychiatry in the United States. To understand the development of this field of research, the chapter will draw first on Mary Morgan’s identification of the mediatory and intermediary role of models and their ability to surprise and generate new questions, and second, upon her recent work on narratives in science. It will argue that it was through discursive and descriptive techniques that traced over time the tangled and interconnected lives of experimental subjects, that such elements of unpredictability in the animal laboratory were transformed into tools of research and put to disciplinary uses, promoting the clinical relevance of this new objective approach to psychiatric medicine.

While the past few decades have witnessed a substantial number of studies on public attitudes toward the police, a relatively thin line of inquiry has focused exclusively on low income urban Black-Americans, and especially street-identified Black populations. The purpose of this paper, however, is to examine trust in police amongst street-identified Black men and women.

Relying on a street participatory action research methodological approach, the authors collected survey data (N = 520) from two low-income unban Black neighborhoods, to examine the effects of an instrumental model versus an expressive model on procedural- and outcome-based trust in police.

The findings suggested a community sample of street-identified Black men and women were able to differentiate between procedural- and outcome-based trust. The instrumental model was better in predicting procedural-based trust in police, while the expressive model accounted better for outcome-based trust in police.

Implications for street participatory action research methodology, future research and policy are also discussed.

This paper is an original manuscript.

The widespread use of drones among the general public has led to an alarming increase in accidents, some with lethal consequences. As drone blades are made from rigid materials and rotate at very high speeds, their impact with a human body can result in fatal injuries. Reliable collision detection combined with near-instantaneous braking of the drone’s rotor(s) can substantially lessen the severity of injuries sustained. The purpose of this paper is to achieve a safety solution which can be easily integrated into new products, or retrofitted into existing systems.

Through a proof of concept, this paper demonstrates the possibility of detecting a collision with a drone propeller absent any hardware modifications to the drone’s instrumentation. The solution relies on current-sensor readings, ordinarily used for monitoring the battery status of electrically actuated drones. The braking is achieved purely by reconfiguring the motor’s control strategy, without the need for additional hardware, as has been the case in previous works.

This paper demonstrates the possibility of detecting a collision with a drone propeller absent any hardware modifications to the drone’s instrumentation.

Compared to previous works which require installing additional hardware, the solution is purely software. This makes it very easy to integrate into existing systems or new products, at no additional cost. In experiments conducted on a prototype system, the solution was shown capable of detecting a collision and braking the motor in fewer than 20 ms. This allowed attenuating centimetre-deep cuts made to a piece of meat by an unprotected rotor to mere superficial scratches.

The management of children′s literature is a search for value and suitability. Effective policies in library and educational work are based firmly on knowledge of materials, and on the bibliographical and critical frame within which the materials appear and might best be selected. Boundaries, like those between quality and popular books, and between children′s and adult materials, present important challenges for selection, and implicit in this process are professional acumen and judgement. Yet also there are attitudes and systems of values, which can powerfully influence selection on grounds of morality and good taste. To guard against undue subjectivity, the knowledge frame should acknowledge the relevance of social and experiential context for all reading materials, how readers think as well as how they read, and what explicit and implicit agendas the authors have. The good professional takes all these factors on board.

The purpose of this paper is to evaluate some of the wider aims and potential consequences of maintaining remand and short-term prisoners on methadone, rather than providing them with a rapid detoxification on first reception into prison. Consideration is given to the effects of methadone prescribing on treatment engagement; drug-related violence; treatment choice, including detoxification, maintenance and reduction doses; recidivism; and through care.

The author draws on qualitative data gathered during a wider study involving drug-using prisoners and prison drug workers exploring the influence of the therapeutic working alliance on outcomes in prison-based drug treatment.

Whilst participants reported advantages to the prescribing of methadone in prisons, such as reduced levels of bullying and drug-related violence in the prisons, they were also critical of many aspects of methadone prescribing which were intended to increase treatment choice, but in practice, often restricted choice. Drug workers reported that some drug-using prisoners were harder to engage with treatment when they were maintained on methadone.

Data were gathered from two “local” prisons in the same geographical area, and as such, the findings may not be applicable across all prison service establishments. Nonetheless, they highlight important considerations and wider policy implications that could be applicable.

Some previously unreported consequences of methadone prescribing in prisons are discussed, including its potential to increase, rather than decrease heroin use and accompanying crime.