scholarly journals Small-Scale Hybrid Rocket Test Stand & Characterization of Swirl Injectors

2013 ◽  
Author(s):  
Matthew H. Summers ◽  
Jacob D. Dennis ◽  
James K. Villarreal
Keyword(s):  
Test Stand ◽  
Small Scale ◽  
Hybrid Rocket ◽  
Swirl Injectors

scholarly journals The HyEnD stern hybrid sounding rocket project

2019 ◽  
Author(s):  
M. Kobald ◽  
C. Schmierer ◽  
U. Fischer ◽  
K. Tomilin ◽  
A. Petrarolo ◽  
...  
Keyword(s):  
Rocket Engine ◽  
Operating Conditions ◽  
Chamber Pressure ◽  
Sounding Rocket ◽  
Small Scale ◽  
Stable Operation ◽  
Hybrid Rocket ◽  
Wide Range ◽  
Hybrid Rocket Engine

The student team Hybrid Engine Development (HyEnD) of the University of Stuttgart is taking part with the Institute of Space Systems (IRS) in the DLR educational program STERN (Studentische Experimentalraketen). This program supports students at German universities to design, build, and launch an experimental rocket within a 3-year project time frame. HyEnD is developing a hybrid rocket called HEROS (Hybrid Experimental Rocket Stuttgart) with a design thrust of 10 kN, a total impulse of over 100 kN·s, and an expected liftoff weight up to 175 kg. HEROS is planned to be launched in October 2015 from Esrange in Sweden to an expected flight altitude of 40 to 50 km. The current altitude record for amateur rockets in Europe is at approximately 21 km. The propulsion system of HEROS is called HyRES (Hybrid Rocket Engine Stuttgart) and uses a paraffin-based solid fuel and nitrous oxide (N2O) as a liquid oxidizer. The development and the test campaign of HyRES is described in detail. The main goals of the test campaign are to achieve a combustion efficiency higher than 90% and provide stable operation with low combustion chamber pressure fluctuations. The successful design and testing of the HyRES engine was enabled by the evaluation and characterization of a small-scale demonstrator engine. The 500-newton hybrid rocket engine, called MIRAS (MIcro RAkete Stuttgart), has also been developed in the course of the STERN project as a technology demonstrator. During this test campaign, a ballistic characterization of paraffin-based hybrid rocket fuels with different additives in combination with N2O and a performance evaluation were carried out. A wide range of operating conditions, fuel compositions, injector geometries, and engine configurations were evaluated with this engine. Effects of different injector geometries and postcombustion chamber designs on the engine performance were analyzed. Additionally, the appearance of combustion instabilities under certain conditions, their effects, and possible mitigation techniques were also investigated. Concluding, the development and construction of an advanced, lightweight hybrid sounding rocket for the given requirements and budget within the DLR STERN program are described herein. The most important parts include a high thrust hybrid rocket engine, the development of a light weight oxidizer tank, pyrotechnical valves, carbon fiber rocket structure, recovery systems, and onboard electronics.

Optical and Chemical Characterization of Aerosols Emitted from Coal, Heavy and Light Fuel Oil, and Small-Scale Wood Combustion

2013 ◽  
Vol 48 (1) ◽  
pp. 827-836 ◽  
Author(s):  
Anna K. Frey ◽  
Karri Saarnio ◽  
Heikki Lamberg ◽  
Fanni Mylläri ◽  
Panu Karjalainen ◽  
...  
Keyword(s):  
Chemical Characterization ◽  
Fuel Oil ◽  
Small Scale ◽  
Wood Combustion

scholarly journals Characterization of small-scale fisheries in the Camamu-Almada basin, southeast state of Bahia, Brazil

2008 ◽  
Vol 68 (4) ◽  
pp. 711-719 ◽  
Author(s):  
TCM. Souza ◽  
M. Petrere-Jr
Keyword(s):  
Low Income ◽  
Small Scale ◽  
Income Generation ◽  
Target Species ◽  
Market Prices ◽  
Marine Fishery ◽  
Small Scale Fisheries ◽  
Main Factor ◽  
Stock Abundance

In the Camamu-Almada basin, marine fishery is exclusively small-scale, with several structural deficiencies such as boats with low or absent navigational technology, lack of credit and low income. Local fishers complain that shrimp and lobster trawling fishing is the main factor responsible for low stock abundance, but they still persist in these activities as these two species command the highest market prices. So they feel that the target species are already over-fished. We suggest that proper management action, alternative ways of income generation and the payment of job insurance would help to mitigate the problem.

scholarly journals Molecular characterization of Listeria monocytogenes isolates from a small-scale meat processor in Montenegro, 2011–2014

2019 ◽  
Vol 79 ◽  
pp. 116-122 ◽  
Author(s):  
Ivana Zuber ◽  
Brankica Lakicevic ◽  
Ariane Pietzka ◽  
Dubravka Milanov ◽  
Vesna Djordjevic ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Molecular Characterization ◽  
Small Scale

Experimental Parameters Used to Study Pesticide Degradation in Soil

1996 ◽  
Vol 10 (1) ◽  
pp. 169-173 ◽  
Author(s):  
Michael R. Blumhorst
Keyword(s):  
Small Scale ◽  
Test Substance ◽  
Pesticide Degradation ◽  
Soil System ◽  
Experimental Parameters ◽  
Effective Cost ◽  
Cost Efficient ◽  
Efficient Mechanisms ◽  
Degradation In Soil

Characterization of pesticide degradation in soil is an important component in determining the environmental impact of agriculturally-applied pesticides. Several techniques currently are being used to generate these data, but small-scale laboratory studies remain one of the most effective, cost-efficient mechanisms of evaluating pesticide behavior in soil. With small-scale studies, many different environmental factors can be incorporated into the experimental design, and with the use of14C-labeled material, these studies (often referred to as soil degradation or soil metabolism studies) provide information on test substance persistence, degradation, volatilization, and mineralization. Care must be exercised, however, in selecting the experimental parameters to be used because of the potential adverse or artificial effects on the soil system.

Tribological Characterization of Machining at Very Small Contact Areas

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Michael R. Lovell ◽  
P. Cohen ◽  
Pradeep L. Menezes ◽  
R. Shankar
Keyword(s):  
High Speed ◽  
Friction Mechanisms ◽  
High Speed Steel ◽  
Small Scale ◽  
Machining Processes ◽  
Macroscopic Theory ◽  
Contact Areas ◽  
Tribological Characterization ◽  
Physical Phenomena

When machining miniaturized components, the contact conditions between the tool and the workpiece exhibit very small contact areas that are on the order of 10−5 mm2. Under these conditions, extremely high contact stresses are generated, and it is not clear whether macroscopic theories for the chip formation, cutting forces, and friction mechanisms are applicable. For this reason, the present investigation has focused on creating a basic understanding of the frictional behavior in very small scale machining processes so that evaluations of standard macroscale models could be performed. Specialized machining experiments were conducted on 70/30 brass materials using high-speed steel tools over a range of speeds, feeds, depths of cut, and tool rake angles. At each operating condition studied, the friction coefficient and the shear factor τk were obtained. Based on the experimental results, it was determined that the standard macroscopic theory for analyzing detailed friction mechanisms was insufficient in very small scale machining processes. An approach that utilized the shear factor, in contrast, was found to be better for decoupling the physical phenomena involved. Utilizing the shear factor as an analysis parameter, the parameters that significantly influence the friction in microscale machining processes were ascertained and discussed.

scholarly journals Irradiance Variability Quantification and Small-Scale Averaging in Space and Time: A Short Review

Atmosphere ◽  
2018 ◽  
Vol 9 (7) ◽  
pp. 264 ◽  
Author(s):  
Gerald Lohmann
Keyword(s):  
Short Review ◽  
Power Grids ◽  
Small Scale ◽  
Stable Operation ◽  
Data Sets ◽  
Spatial Smoothing ◽  
Spatial And Temporal Scales ◽  
Output Variability ◽  
Temporal Averaging

The ongoing world-wide increase of installed photovoltaic (PV) power attracts notice to weather-induced PV power output variability. Understanding the underlying spatiotemporal volatility of solar radiation is essential to the successful outlining and stable operation of future power grids. This paper concisely reviews recent advances in the characterization of irradiance variability, with an emphasis on small spatial and temporal scales (respectively less than about 10 km and 1 min), for which comprehensive data sets have recently become available. Special attention is given to studies dealing with the quantification of variability using such unique data, the analysis and modeling of spatial smoothing, and the evaluation of temporal averaging.

scholarly journals Topophilia, Placemaking, and Boundary Work

2022 ◽  
Vol 6 (GROUP) ◽  
pp. 1-33
Author(s):  
Janghee Cho ◽  
Samuel Beck ◽  
Stephen Voida
Keyword(s):  
Large Scale ◽  
Methodological Approach ◽  
Work Practice ◽  
Small Scale ◽  
Work From Home ◽  
Humanistic Geography ◽  
Working From Home ◽  
Long Term Impact

The COVID-19 pandemic fundamentally changed the nature of work by shifting most in-person work to a predominantly remote modality as a way to limit the spread of the coronavirus. In the process, the shift to working-from-home rapidly forced the large-scale adoption of groupware technologies. Although prior empirical research examined the experience of working-from-home within small-scale groups and for targeted kinds of work, the pandemic provides HCI and CSCW researchers with an unprecedented opportunity to understand the psycho-social impacts of a universally mandated work-from-home experience rather than an autonomously chosen one. Drawing on boundary theory and a methodological approach grounded in humanistic geography, we conducted a qualitative analysis of Reddit data drawn from two work-from-home-related subreddits between March 2020 and January 2021. In this paper, we present a characterization of the challenges and solutions discussed within these online communities for adapting work to a hybrid or fully remote modality, managing reconfigured work-life boundaries, and reconstructing the home's sense of place to serve multiple, sometimes conflicting roles. We discuss how these findings suggest an emergent interplay among adapted work practice, reimagined physical (and virtual) spaces, and the establishment and continual re-negotiation of boundaries as a means for anticipating the long-term impact of COVID on future conceptualizations of productivity and work.

scholarly journals Characterization of Ficus benjamina and Artocarpus heterophyllus Proteases as Potential Rennet Alternatives

2020 ◽  
Vol 12 (2) ◽  
pp. 213-219
Author(s):  
Andreas Binar Aji Sukmana ◽  
Indy Widyaningrum ◽  
Rischa Karmila Lani ◽  
Sri Kasmiyati
Keyword(s):  
Proteolytic Activity ◽  
Scientific Knowledge ◽  
Knowledge Development ◽  
Small Scale ◽  
Optimum Conditions ◽  
Artocarpus Heterophyllus ◽  
Ficus Benjamina ◽  
Crucial Component ◽  
Plant Proteases

Rennet, a milk coagulant exhibiting proteolytic activity, is a crucial component in cheese industries. Its price and availability have discouraged the growth of some small scale cheese industries. Therefore, an alternative for rennet will be beneficial for the industries. Among other sources, plant proteases offer some advantages as rennet alternatives. This study aimed to investigate the potential of plant proteases obtained from the latex as potential rennet alternatives. A total of six plants from the genus Ficus and Artocarpus were screened for their proteolytic activity and milk coagulating ability. The screening indicated that all six tested plants displayed proteolytic activity at various levels, but only Ficus benjamina and Artocarpus heterophyllus produced a firm milk curd. Hence, both F. benjamina and A. heterophyllus were determined to be the most potential. Further characterizations suggested that F. benjamina and A. heterophyllus protease were optimum at pH 7.0 also at 50°C and 40°C, respectively. At their optimum conditions, both proteases exhibited a lower MCA/PA ratio than that of the rennet. This study contributed to scientific knowledge development by becoming the first to characterize the optimum conditions of F. benjamina and A. heterophyllus’ proteases, investigate their MCA/PA ratio, and compare their activity against commercial rennet. The examination of their potentials as rennet alternatives could benefit small cheese industries and the communities.

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