The aerodynamic challenges of SRB recovery

Recovery and reuse of the Space Shuttle solid rocket boosters was baselined to support the primary goal to develop a low cost space transportation system. The recovery system required for the 170,000-lb boosters was for the largest and heaviest object yet to be retrieved from exoatmospheric conditions. State-of-the-art design procedures were ground-ruled and development testing minimized to produce both a reliable and cost effective system. The ability to utilize the inherent drag of the boosters during the initial phase of reentry was a key factor in minimizing the parachute loads, size and weight. A wind tunnel test program was devised to enable the accurate prediction of booster aerodynamic characteristics. Concurrently, wind tunnel, rocket sled and air drop tests were performed to develop and verify the performance of the parachute decelerator subsystem. Aerodynamic problems encountered during the overall recovery system development and the respective solutions are emphasized

Cold Flow Determination of the Internal Flow Environment Around the Submerged TVC Nozzle for the Space Shuttle SRM

A series of subscale cold flow tests was performed to quantify the gas flow characteristics at the aft end of the Space Shuttle Solid Rocket Motor. This information was used to support the analyses of the redesigned nozzle/case joint. A portion of the thermal loads at the joint are due to the circumferential velocities and pressure gradients caused primarily by the gimbaling of the submerged nose TVC nozzle. When the nozzle centerline is vectored with respect to the motor centerline, asymmetries are set up in the flow field under the submerged nozzle and immediately adjacent to the nozzle/case joint. Specific program objectives included: determination of the effects of nozzle gimbal angle and propellant geometry on the circumferential flow field; measurement of the static pressure and gas velocities in the vicinity of the nozzle/case joint; use of scaling laws to apply the subscale cold flow data to the full scale SRM; and generation of data for use in validation of 3-D computational fluid dynamic, CFD, models of the SRM flow field. These tests were conducted in the NASA Marshall Space Flight Center Airflow Facility with a 7.5 percent scale model of the aft segment of the SRM. Static and dynamic pressures were measured in the model to quantify the flow field. Oil flow data was also acquired to obtain qualitative visual descriptions of the flow field. Nozzle gimbal angles of 0, 3.5, and 7 deg were used with propellant grain configurations corresponding to motor burn times of 0, 9, 19, and 114 seconds. This experimental program was successful in generating velocity and pressure gradient data for the flow field around the submerged nose nozzle of the Space Shuttle SRM at various burn times and gimbal angles. The nature of the flow field adjacent to the nozzle/case joint was determined with oil droplet streaks, and the velocity and pressure gradients were quantified with pitot probes and wall static pressure measurements. The data was applied to the full scale SRM thru a scaling analysis and the results compared well with the 3-D computational fluid dynamics computer model

Project 1640 observations of the white dwarf HD 114174 B

We present the first near infrared spectrum of the faint white dwarf companion HD 114174 B, obtained with Project 1640. Our spectrum, covering the Y, J and H bands, combined with previous TaRgetting bENchmark-objects with Doppler Spectroscopy (TRENDS) photometry measurements, allows us to place further constraints on this companion. We suggest two possible scenarios; either this object is an old, low-mass, cool H atmosphere white dwarf with T_(eff) ∼ 3800 K or a high-mass white dwarf with T_(eff) > 6000 K, potentially with an associated cool (T_(eff) ∼ 700 K) brown dwarf or debris disc resulting in an infrared excess in the L΄ band. We also provide an additional astrometry point for 2014 June 12 and use the modelled companion mass combined with the radial velocity and direct imaging data to place constraints on the orbital parameters for this companion

A lower bound on CNF encodings of the at-most-one constraint

Constraint "at most one" is a basic cardinality constraint which requires that at most one of its $n$ boolean inputs is set to $1$. This constraint is widely used when translating a problem into a conjunctive normal form (CNF) and we investigate its CNF encodings suitable for this purpose. An encoding differs from a CNF representation of a function in that it can use auxiliary variables. We are especially interested in propagation complete encodings which have the property that unit propagation is strong enough to enforce consistency on input variables. We show a lower bound on the number of clauses in any propagation complete encoding of the "at most one" constraint. The lower bound almost matches the size of the best known encodings. We also study an important case of 2-CNF encodings where we show a slightly better lower bound. The lower bound holds also for a related "exactly one" constraint.Comment: 38 pages, version 3 is significantly reorganized in order to improve readabilit

“It’s Always Good to Ask”:A Mixed Methods Study on the Perceived Role of Sexual Health Practitioners Asking Gay and Bisexual Men About Experiences of Domestic Violence and Abuse

Development of joint displays is a valued approach to merging qualitative and quantitative findings in mixed methods research. This study aimed to illustrate a case series mixed methods display and the utility of using mixed methods for broadening our understanding of domestic violence and abuse. Using a convergent design, 532 gay and bisexual men participated in a Health and Relationship Survey in a U.K. sexual health service and 19 in an interview. Quantitative and qualitative data were analyzed separately and integrated at the level of interpretation and reporting. There were inconsistencies in perceptions and reports of abuse. Men were supportive of selective enquiry for domestic violence and abuse by practitioners (62.6%; 95% confidence interval = 58.1% to 66.7%) while being mindful of contextual factors.</p

Researching domestic violence and abuse in healthcare settings: challenges and issues

Domestic violence and abuse (DVA) is now recognised as a significant global health and societal issue. Conducting DVA research in healthcare contexts requires the consideration and understanding of a number of practical, methodological and ethical issues. Based on their experiences of working as clinicians and researchers, the authors aim to explore some of the pertinent issues and challenges associated with DVA research conducted in healthcare settings involving patients and/or healthcare professionals or both. A number of ethical, methodological and practical challenges, particularly those associated with research design and data collection, and ethical challenges related to participants and researchers, are explored

'If she gets married when she is young, she will give birth to many kids': a qualitative study of child marriage practices amongst nomadic pastoralist communities in Kenya

Child marriage is associated with adverse health and social outcomes for women and girls. Among pastoralists in Kenya, child marriage is believed to be higher compared to the national average. This paper explores how social norms and contextual factors sustain child marriage in communities living in conflict-affected North Eastern Kenya. In-depth interviews were carried out with nomadic and semi-nomadic women and men of reproductive age in Wajir and Mandera counties. Participants were purposively sampled across a range of age groups and community types. Interviews were analysed thematically and guided by a social norms approach. We found changes in the way young couples meet and evidence for negative perceptions of child marriage due to its impact on the girls’ reproductive health and gender inequality. Despite this, child marriage was common amongst nomadic and semi-nomadic women. Two overarching themes explained child marriage practices: 1) gender norms, and 2) desire for large family size. Our findings complement the global literature, while contributing perspectives of pastoralist groups. Contextual factors of poverty, traditional pastoral lifestyles and limited formal education opportunities for girls, supported large family norms and gender norms that encouraged and sustained child marriage

Infusing Technology Into Perinatal Home Visitation in the United States for Women Experiencing Intimate Partner Violence: Exploring the Interpretive Flexibility of an mHealth Intervention.

BACKGROUND: Intimate partner violence (IPV) is common during pregnancy and the postpartum. Perinatal home visitation provides favorable conditions in which to identify and support women affected by IPV. However, the use of mHealth for delivering IPV interventions in perinatal home visiting has not been explored. OBJECTIVE: Our objective was to conduct a nested qualitative interpretive study to explore perinatal home visitors' and women's perceptions and experiences of the Domestic Violence Enhanced Home Visitation Program (DOVE) using mHealth technology (ie, a computer tablet) or a home visitor-administered, paper-based method. METHODS: We used purposive sampling, using maximum variation, to select women enrolled in a US-based randomized controlled trial of the DOVE intervention for semistructured interviews. Selection criteria were discussed with the trial research team and 32 women were invited to participate. We invited 45 home visitors at the 8 study sites to participate in an interview, along with the 2 DOVE program designers. Nonparticipant observations of home visits with trial participants who chose not to participate in semistructured interviews were undertaken. RESULTS: We conducted 51 interviews with 26 women, 23 home visiting staff at rural and urban sites, and the 2 DOVE program designers. We conducted 4 nonparticipant observations. Among 18 IPV-positive women, 7 used the computer tablet and 11 used the home visitor method. Among 8 IPV-negative women, 7 used the home visitor method. The computer tablet was viewed as a safe and confidential way for abused women to disclose their experiences without fear of being judged. The meanings that the DOVE technology held for home visitors and women led to its construction as either an impersonal artifact that was an impediment to discussion of IPV or a conduit through which interpersonal connection could be deepened, thereby facilitating discussion about IPV. Women's and home visitors' comfort with either method of screening was positively influenced by factors such as having established trust and rapport, as well as good interpersonal communication. The technology helped reduce the anticipated stigma associated with disclosing abuse. The didactic intervention video was a limiting feature, as the content could not be tailored to accommodate the fluidity of women's circumstances. CONCLUSIONS: Users and developers of technology-based IPV interventions need to consider the context in which they are being embedded and the importance of the patient-provider relationship in promoting behavior change in order to realize the full benefits. An mHealth approach can and should be used as a tool for initiating discussion about IPV, assisting women in enhancing their safety and exploring help-seeking options. However, training for home visitors is required to ensure that a computer tablet is used to complement and enhance the therapeutic relationship. CLINICALTRIAL: Clinicaltrials.gov NCT01688427; https://clinicaltrials.gov/ct2/show/NCT01688427 (Archived by WebCite at http://www.webcitation.org/6limSWdZP)

Violence, uncertainty, and resilience among refugee women and community workers: An evaluation of gender-based violence case management services in the Dadaab refugee camps.

Reports of gender-based violence (GBV) are common in camps for refugees and displaced populations. In the Dadaab refugee camps in north-eastern Kenya, the International Rescue Committee (IRC) and CARE International (CARE) implement programmes that aim to both respond to and prevent GBV. A cornerstone of this work has been to train refugees, known as refugee community workers, to deliver aspects of GBV prevention and response work in order to develop a broader implementation of traditional GBV outreach, community mobilisation, and case management. To date, there has been limited rigorous research on this broader GBV case management plus task sharing approach in the context of a refugee camp setting. To address this key gap in evidence, the London School of Hygiene and Tropical Medicine (LSHTM) and the African Population and Health Research Centre (APHRC), in collaboration with IRC and CARE, have sought to assess this model to understand its feasibility, acceptability, and influence among female survivors of GBV accessing care. Data for this study, funded by UK aid, were collected in the Dadaab refugee camps between 2014 and 2017, which coincided with a temporary decision to close the camp and repatriate Somali refugees. The research confirms the magnitude and complexity of the violence that women and girls experience in the camps in Dadaab. In the year leading up to this study, 47% of women accessing the GBV centres for case management reported experiencing intimate partner violence and 39% reported experiencing non-partner violence. In addition, the study highlights the specific risks, challenges, opportunities and rewards experienced by refugee community workers in their dual role of community members and GBV activists living side-by-side with survivors and perpetrators of violence. Solely related to their work as GBV caseworkers, one in three refugee community workers reported experiencing non-partner violence in the last 12 months. Despite this, 93% of refugee community workers stated their work was rewarding or extremely rewarding. The majority of women (82%) accessing services reported that their interactions with refugee community workers had a positive effect, and that working with them was useful. However, having refugees deliver services to their own community was not without its challenges, and survivors raised issues on confidentiality, mistranslations, and perceived biases on clan differences. The study also provides an insight into the importance of contextual factors in case management, and the impact of the announcement of the (now-delayed) camp closure in Dadaab. Priorities of both the camp population and service providers (GBV and referral services) shifted greatly during this time of uncertainty and affected when and how women were accessing services