Large Liquid Rocket Testing: Strategies and Challenges

Rocket propulsion development is enabled by rigorous ground testing in order to mitigate the propulsion systems risks that are inherent in space flight. This is true for virtually all propulsive devices of a space vehicle including liquid and solid rocket propulsion, chemical and non-chemical propulsion, boost stage and in-space propulsion and so forth. In particular, large liquid rocket propulsion development and testing over the past five decades of human and robotic space flight has involved a combination of component-level testing and engine-level testing to first demonstrate that the propulsion devices were designed to meet the specified requirements for the Earth to Orbit launchers that they powered. This was followed by a vigorous test campaign to demonstrate the designed propulsion articles over the required operational envelope, and over robust margins, such that a sufficiently reliable propulsion system is delivered prior to first flight. It is possible that hundreds of tests, and on the order of a hundred thousand test seconds, are needed to achieve a high-reliability, flight-ready, liquid rocket engine system. This paper overviews aspects of earlier and recent experience of liquid rocket propulsion testing at NASA Stennis Space Center, where full scale flight engines and flight stages, as well as a significant amount of development testing has taken place in the past decade. The liquid rocket testing experience discussed includes testing of engine components (gas generators, preburners, thrust chambers, pumps, powerheads), as well as engine systems and complete stages. The number of tests, accumulated test seconds, and years of test stand occupancy needed to meet varying test objectives, will be selectively discussed and compared for the wide variety of ground test work that has been conducted at Stennis for subscale and full scale liquid rocket devices. Since rocket propulsion is a crucial long-lead element of any space system acquisition or development, the appropriate plan and strategy must be put in place at the outset of the development effort. A deferment of this test planning, or inattention to strategy, will compromise the ability of the development program to achieve its systems reliability requirements and/or its development milestones. It is important for the government leadership and support team, as well as the vehicle and propulsion development team, to give early consideration to this aspect of space propulsion and space transportation work

Worldwide Space Launch Vehicles and Their Mainstage Liquid Rocket Propulsion

Space launch vehicle begins with a basic propulsion stage, and serves as a missile or small launch vehicle; many are traceable to the 1945 German A-4. Increasing stage size, and increasingly energetic propulsion allows for heavier payloads and greater. Earth to Orbit lift capability. Liquid rocket propulsion began with use of storable (UDMH/N2O4) and evolved to high performing cryogenics (LOX/RP, and LOX/LH). Growth versions of SLV's rely on strap-on propulsive stages of either solid propellants or liquid propellants

Remembering the Giants: Apollo Rocket Propulsion Development

Topics discussed include: Rocketdyne - F-1 Saturn V First Stage Engine; Rocketdyne - J-2 Saturn V 2nd & 3rd Stage Engine; Rocketdyne - SE-7 & SE-8 Engines; Aerojet - AJ10-137 Apollo Service Module Engine; Aerojet - Attitude Control Engines; TRW - Lunar Descent Engine; and Rocketdyne - Lunar Ascent Engine

Global Trends in Space Access and Utilization

In the not-so-distant past, space access and air/space technology superiority were within the purview of the U.S. and former Soviet Union's respective space agencies, both vying for global leadership in space exploitation. In more recent years, with the emergence of the European Space Agency (ESA) member countries and Asian countries joining the family of space-faring nations, it is truer now more than ever that space access and utilization has become a truly global enterprise. In fact, according to the Space Report 2007, this enterprise is a $251-billion economy. It is possible to gauge the vitality of worldwide efforts from open sources in today's transparent, media-based society. In particular, print and web broadcasters regularly report and catalog global space activities for defense and civil purposes. For the purposes of this paper, a representative catalog of missions is used to illustrate the nature of the emerging "globalization." This paper highlights global trends in terms of not only the providers of space access, but also the end-users for the various recently accomplished missions. With well over 50 launches per year, in recent years, the launch-log reveals a surprising percentage of "cooperative or co-dependent missions" where different agencies, countries, and/or commercial entities are so engaged presumably to the benefit of all who participate. Statistics are cited and used to show that recently over d0% of the 50-plus missions involved multiple nations working collectively to deliver payloads to orbit. Observers, space policy professionals, and space agency leaders have eloquently proposed that it might require the combined resources and talents of multiple nations to advance human exploration goals beyond low earth orbit. This paper does not intend to offer new information with respect to whether international collaboration is necessary but to observe that, in continuing to monitor global trends, the results seem to support the thesis that a global interdependent effort with all its likely complexities is an increasingly viable and pragmatic option. The discussion includes a breakdown of space missions into those of civil (scientific), military, and strictly commercial nature. It concludes that all three are robust components of a globally diversified portfolio of activities relying, essentially, on a common space industrial base and space infrastructure. As in other industries, the distribution of space industry assets and knowledge across countries and continents enables a diverse suite of options and arrangements, particularly in the areas of civil and commercial space utilization. A survey of several ongoing bilateral and multilateral space collaboration examples are provided to augment the observations regarding multinational work in space

JANNAF "Test and Evaluation Guidelines for Liquid Rocket Engines": Status and Application

For many decades, the U.S. rocket propulsion industrial base has performed remarkably in developing complex liquid rocket engines that can propel critical payloads into service for the nation, as well as transport people and hardware for missions that open the frontiers of space exploration for humanity. This has been possible only at considerable expense given the lack of detailed guidance that captures the essence of successful practices and knowledge accumulated over five decades of liquid rocket engine development. In an effort to provide benchmarks and guidance for the next generation of rocket engineers, the Joint Army Navy NASA Air Force (JANNAF) Interagency Propulsion Committee published a liquid rocket engine (LRE) test and evaluation (T&E) guideline document in 2012 focusing on the development challenges and test verification considerations for liquid rocket engine systems. This document has been well received and applied by many current LRE developers as a benchmark and guidance tool, both for government-driven applications as well as for fully commercial ventures. The USAF Space and Missile Systems Center (SMC) has taken an additional near-term step and is directing activity to adapt and augment the content from the JANNAF LRE T&E guideline into a standard for potential application to future USAF requests for proposals for LRE development initiatives and launch vehicles for national security missions. A draft of this standard was already sent out for review and comment, and is intended to be formally approved and released towards the end of 2017. The acceptance and use of the LRE T&E guideline is possible through broad government and industry participation in the JANNAF liquid propulsion committee and associated panels. The sponsoring JANNAF community is expanding upon this initial baseline version and delving into further critical development aspects of liquid rocket propulsion testing at the integrated stage level as well as engine component level, in order to advance the state of the practice. The full participation of the entire U.S. rocket propulsion industrial base is invited and expected at this opportune moment in the continuing advancement of spaceflight technology

Spectrum of perforation peritonitis in Pakistan: 300 cases Eastern experience

<p>Abstract</p> <p>Background</p> <p>Perforation peritonitis is the most common surgical emergency encountered by the surgeons all over the world as well in Pakistan. The spectrum of etiology of perforation peritonitis in tropical countries continues to differ from its western counter part. This study was conducted at Dow University of health sciences and Civil Hospital Karachi (DUHS & CHK) Pakistan, designed to highlight the spectrum of perforation peritonitis in the East and to improve its outcome.</p> <p>Methods</p> <p>A prospective study includes three hundred consecutive patients of perforation peritonitis studied in terms of clinical presentations, Causes, site of perforation, surgical treatment, post operative complications and mortality, at (DUHS&CHK) Pakistan, from 1st September 2005 – 1st March 2008, over a period of two and half years. All patients were resuscitated underwent emergency exploratory laparotomy. On laparotomy cause of perforation peritonitis was found and controlled.</p> <p>Results</p> <p>The most common cause of perforation peritonitis noticed in our series was acid peptic disease 45%, perforated duodenal ulcer (43.6%) and gastric ulcer 1.3%. followed by small bowel tuberculosis (21%) and typhoid (17%). large bowel perforation due to tuberculosis 5%, malignancy 2.6% and volvulus 0.3%. Perforation due to acute appendicitis (5%). Highest number of perforations has seen in the duodenum 43.6%, ileum37.6%, and colon 8%, appendix 5%, jejunum 3.3%, and stomach 2.3%. Overall mortality was (10.6%).</p> <p>Conclusion</p> <p>The spectrum of perforation peritonitis in Pakistan continuously differs from western country. Highest number of perforations noticed in the upper part of the gastrointestinal tract as compared to the western countries where the perforations seen mostly in the distal part. Most common cause of perforation peritonitis is perforated duodenal ulcer, followed by small bowel tuberculosis and typhoid perforation. Majority of the large bowel perforations are also tubercular. Malignant perforations are least common in our setup.</p

System Biology and Machine Learning Framework for Prostate Cancer Survival Prediction

Prostate cancer (PC) is the most commonly diagnosed and the second most lethal malignancy in men. Proper understanding about the factors influencing the disease mechanism, response to the treatment and long term survival could facilitate effective disease management, treatment planning and decision making. Previous research initiatives reported a number of genes having impact on PC development but their genetic influence on the overall survival of the patients is still obscure. In this study, we fist identified PC related signature genes by analysing the RNA-seq transcriptomic data. Then we investigated the influence of those genes on the survival of PC patients using the clinical and transcriptomic data from the Cancer Genome Atlas (TCGA). Considering the univariate and multivariate analysis using the Cox proportional-hazards (CoxPH) model, we evidenced notable variation in the survival period between the altered and normal groups for two genes (APLN, and DUOXA1). We also identified ten hub genes such as CAV1, RHOU, TUBB4A, RRAS, EFNB1, ZWINT, MYL9, PPP3CA, FGFR2 and GATA3 in protein-protein interaction analysis that could be the source of potential therapeutic intervention. Moreover, several significant molecular pathways through functional enrichment analysis was obtained. After verification through functional studies, the identified genetic determinants could serve as therapeutic target for prolonged PC survival

Role of bronchoalveolar lavage in the diagnosis of lung cancer

Background: Early diagnosis of lung cancer plays a vital role in reducing the lung cancer death rate. Different modalities can be applied e.g. radiology, bronchoscopy, bronchoalveolar lavage (BAL), and fine needle aspiration cytology. Cytological diagnostic techniques are safer, economical, and provide quick results. The aim of the study was to find out diagnostic yields of bronchoalveolar lavage in diagnosing lung cancer, and to determine the sensitivity, and specificity of BAL fluid cytology considering the bronchial biopsy as the gold standard.Methods: This cross-sectional study was carried out in the Department of Respiratory Medicine, Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka during the period from November 2018 to March 2020 with a total of 38 participants.Results: 33 (86.84%) patients were male, and 5 (13.16%) were female; the mean age was 58.29±13.11 years. In clinical presentations, cough was present in all 100% of the patients, and some more frequent presentations were shortness of breath in 26 (68.4%), hemoptysis in 24 (63.15%), and chest pain in 21 (55.26%). Majority of the patients (78.95%) were smokers. Considering histopathological findings, maximum patients had squamous cell carcinoma 13 (38.23%), then adenocarcinoma 11 (32.35%), small cell carcinoma 5 (14.70%), large cell carcinoma 3 (8.82%), and poorly differentiated non-small cell carcinoma 2 (5.88%). The sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy of BAL were 70.59%, 100%, 100%, 28.57%, and 73.68% respectively.Conclusions: BAL fluid cytology is a useful tool for the diagnosis of lung cancer. It has good sensitivity, and specificity, and shows nearly identical information as biopsy

Volumetric Properties of Binary Mixtures of 2-Ethoxyethanol and 2-Butoxyethanol with 1,4-Dioxane

Densities, r, of 2-Ethoxyethanol (EGMEE) + 1,4-Dioxane (DXN) and  2-Butoxyethanol (EGMBE) + 1,4-Dioxane (DXN) systems have been measured in the whole range of composition at an interval of 5 K ranging from 303.15 to 323.15 K. Excess molar volumes, , partial molar volumes, , thermal expansivities,a, and excess thermal expansivities, aE, have been estimated from the experimental values of ρ. All of the derived properties have been fitted to appropriate polynomials. Values of   and aE were fitted to the Redlich-Kister polynomial equation and their variations with composition and temperature have been discussed in terms of molecular interaction in the mixtures. Values of  and aE were all positive and were attributed due to specific interactions

Measuring Coverage in MNCH:A Prospective Validation Study in Pakistan and Bangladesh on Measuring Correct Treatment of Childhood Pneumonia

Antibiotic treatment for pneumonia as measured by Demographic and Health Surveys (DHS) and Multiple Indicator Cluster Surveys (MICS) is a key indicator for tracking progress in achieving Millennium Development Goal 4. Concerns about the validity of this indicator led us to perform an evaluation in urban and rural settings in Pakistan and Bangladesh.Caregivers of 950 children under 5 y with pneumonia and 980 with "no pneumonia" were identified in urban and rural settings and allocated for DHS/MICS questions 2 or 4 wk later. Study physicians assigned a diagnosis of pneumonia as reference standard; the predictive ability of DHS/MICS questions and additional measurement tools to identify pneumonia versus non-pneumonia cases was evaluated. Results at both sites showed suboptimal discriminative power, with no difference between 2- or 4-wk recall. Individual patterns of sensitivity and specificity varied substantially across study sites (sensitivity 66.9% and 45.5%, and specificity 68.8% and 69.5%, for DHS in Pakistan and Bangladesh, respectively). Prescribed antibiotics for pneumonia were correctly recalled by about two-thirds of caregivers using DHS questions, increasing to 72% and 82% in Pakistan and Bangladesh, respectively, using a drug chart and detailed enquiry.Monitoring antibiotic treatment of pneumonia is essential for national and global programs. Current (DHS/MICS questions) and proposed new (video and pneumonia score) methods of identifying pneumonia based on maternal recall discriminate poorly between pneumonia and children with cough. Furthermore, these methods have a low yield to identify children who have true pneumonia. Reported antibiotic treatment rates among these children are therefore not a valid proxy indicator of pneumonia treatment rates. These results have important implications for program monitoring and suggest that data in its current format from DHS/MICS surveys should not be used for the purpose of monitoring antibiotic treatment rates in children with pneumonia at the present time