Propellant Injection Strategy for Suppressing Acoustic Combustion Instability

Shear-coaxial injector elements are often used in liquid-propellant-rocket thrust chambers, where combustion instabilities remain a significant problem. A conventional solution to the combustion instability problem relies on passive control techniques that use empirically-tested hardware such as acoustic baffles and tuned cavities. In addition to adding weight and decreasing engine performance, these devices are designd using trial-and-error empirical science, which does not provide the capability to predict the overall system stability characteristics in advance. In this thesis, two novel control strategies that are based on propellant fluid dynamics were investigated for mitigating acoustic instability involving shear-coaxial injector elements. The new control strategies would use a set of controlled injectors allowing local adjustment of propellant flow patterns for each operating condition, of which the instability could become a problem. One strategy relies on reducing the oxidizer-fuel density gradient by blending heavier methane to the main fuel hydrogen. Another strategy utilizes modifying the equivalence ratio to affect the acoustic impedance through the mixing and reaction rate changes. To provide the scientific basis, unit-physics experiments were conducted to explore the potential effectiveness of these strategies. Two different model combustors, simulating a single-element injector test and a double-element injector test, were designed and tested for flame-acoustic interaction. For these experiments, the Reynolds number of the central oxygen jet was kept between 4700 and 5500 making the injector flames sufficiently turbulent. A compression driver, mounted on one side of the combustor wall, provided controlled acoustic excitation to the injector flames, simulating the initial phase of flame-acoustic interaction. Acoustic excitation was applied either as a band-limited white noise forcing between 100 Hz and 5000 Hz or as a single-frequency, fixed-amplitude forcing at 1150 Hz which represented a frequency least amplified by any resonance. Effects of each control strategy on flame-acoustic interaction were assessed in terms of modifying the acoustic resonance characteristics subject to white-noise excitation and changes in flame brush thickness under single-frequency excitation. In the methane blending experiments, the methane mole fraction was varied between 0% and 63%. Under white noise excitation, up to 16% shift in a resonant frequency was observed but the acoustic pressure spectrum remained qualitatively similar. For the fixed frequency forcing, the spatial extent of flame-acoustic interaction was substantially reduced. In the other experiments, the equivalence ratio of the control injector was varied between 0 and infinity, causing up to 40% shift in a resonant frequency as well as changes in the acoustic pressure spectrum. These results open up the possibility of employing flow-based control to prevent combustion instabilities in liquid-fueled rockets

Seasons: A motion graphics depicts activities of ancient Chinese people in four seasons

Seasons is a 2D motion graphics film that aims to visually depict my interpretation of seasons changing and seasonal activities of ancient Chinese people. It is an attempt to reproduce two classical arts on modern media. I mimic and mix the visual effects of Chinese shadow puppets and Chinese ink wash strokes through digital media technologies. Neither Chinese painting nor shadow puppet emphasize on reproducing the appearance of subject. It is more regarded as a form of expressionistic art, which intends to capture the spirit of the subject and illustrate the perception of the scene. My graphics are not planned to fully copy external forms of shadow puppets or old Chinese paintings, instead, I target to show the beauty of Chinese traditional art forms as well as the beauty of Asian aesthetics and philosophy. Seasons represents my imaginary and visual adaptation of my knowledge and memories about cultures, traditions, and mysteries that related to seasons. The intent of project is to seek a different approach to integrate motion graphics with traditional art forms, and, to discuss more possibilities of transplanting classical arts into digital platform

Coevolutionary dynamics under anthropogenic impact in intensively managed landscapes

Anthropogenic activities have encroached on floodplains for infrastructure and modified the landscapes for agriculture. Over time these become intensive and extensive to support increasing societal and economic demand. For example, landscapes in the U.S. Midwest have lost wetlands and native vegetation. These activities result in unprecedented changes in the rate and magnitude of water, soil, and carbon fluxes, and hence causes uncertainties in flood prediction, soil fertility, and food security. Understanding the co-evolution of various linked processes of hydrology, geomorphology, and biogeochemistry makes it possible to address the challenges of how anthropogenic activities have changed the critical zone and how nature would respond. The goals of this research are to: (i) characterize the hydrogeomorphological features of alluvial river valleys, which reveal universal hydrologic attributes for distinguishing the terraces and floodplains; and (ii) investigate the soil organic carbon (SOC) dynamics in intensively managed landscapes, which have accelerated soil erosion, through modeling and simulation of the coevolution of landscape and SOC. In the river valley study, we distinguish between floodplains and terraces--two similar geometries in topography but that have different hydraulic and geomorphologic functions regarding river valley development and flood response. Our approach involves transforming the transverse cross-sectional geometry of a river valley into a curve, called River Valley Hypsometric (RVH) curve. The floodplains and terraces associate with its different aspects in this curve. We applied the RVH approach for different types of landscapes across the U.S. Critical Zone Observatories (CZO). We found that the structure of the RVH curves is linked with the hydraulic inundation frequency--the transitions of steps and risers in a RVH curve may be shaped by floods with 10- to 100-yr recurrence, which establishes the demarcation between floodplains and terraces. The results also show that the lowermost step on the RVH curve is the floodplain zone. Further, the normalized width and height (by bankfull width and depth, respectively) of the 10-yr and 100-yr floods lie in a narrow range, which indicates a universal behavior. However, human-made channels show distinct departure from the universal behavior. The RVH curves can not only distinguish between terraces and floodplains but also further serve as a practical means for river valley development and flood control. In a watershed scale study, we focuses on using numerical simulation to study the coevolution of landscape and SOC dynamics through the soil vertical profiles. Soil is the largest reservoir of carbon in the terrestrial system but is going through rapid erosion due to anthropogenic influences. The soil erosion and resultant landscape evolution plays a vital role on the soil-atmosphere C exchange. Here, we develop a process-based quasi 3-D model, named SCALE (soil carbon and landscape co-evolution), which couples surface water runoff, soil moisture dynamics, biogeochemical transformation, SOC transport, and landscape evolution at high spatial and temporal resolution at a watershed scale. Specifically, this model simulates the physical transport and biogeochemical transformation of SOC across the whole watershed. We apply the SCALE model to two different human-impacted landscapes--a low-relief sub-watershed in the Clear Creek Watershed (CCW) in Iowa is U.S. and a high-relief watershed under the Gully Land Consolidation (GLC) project in the China Loess Plateau. In CCW, we simulate SOC dynamics over 100 years and validate the results with observations. The SOC profiles tend to have 'noses' below the surface at depositional sites. We also compare the lateral SOC transport flux and the vertical soil-atmosphere carbon exchange rate across the watershed. Generally, erosional sites are local net atmospheric carbon sinks and depositional sites are sources. Further, we study the impact of landscape evolution on the heterotrophic carbon loss (HCL)--defined as carbon release in the form of carbon dioxide from SOC decomposition. The results show that the HCL in topsoils is 1 to 2 orders of magnitude higher than subsoils. The vertical profiles of the subsoils follows the pattern of SOC profiles. The HCL rate--defined as the ratio of HCL to total SOC in topsoils is mainly dominated by microbes, but the ones in subsoils is dominated by soil moisture. In the GLC study, our simulation aims to address if the GLC project could provide a sustainable C cycling in the newly crated agricultural land. Model results show that GLC project effectively preserves soils and SOC inside the consolidated gully over the long-term. The intra-annual SOC dynamics in the consolidated gully area is mainly driven by biogeochemical transformation not soil transport, while in the natural watershed, the SOC dynamics are driven equally by the two processes. We also simulate possible outcomes of different scenarios of land management. To increase the SOC stocks inside the consolidated gully land, applying biochar, which has a lower decomposition rate, is more effective than increasing plant residues input. This study not only helps us understand the dynamics of SOC profiles at a watershed scale but can also serve as an instrument to develop practical approaches for protecting carbon loss due to human activities. Broadly, this modeling framework leads to a deeper understanding of how hydrology, biogeochemistry, and geomorphology affect SOC dynamics in the evolving Anthropocene

Persaingan strategi pemasaran home industry tempe Ibu Urfatusolikha dan Ibu Imah perspektif ekonomi Islam : studi komparasi home industry di Dusun Blanten Desa Cikura Kecamatan Bojong Kabupaten Tegal

ABSTRAK Home industry tempe Ibu Urfatusholikha dan Ibu Imah merupakan suatu usaha yang berdiri di satu dusun yang sama keduanya melakukan persaingan dengan perbedaan mulai dari proses produksi tempe sampai pemasaranya. Home industry tempe Ibu Urfatusholikha berdiri lebih dulu dibandingkan home industry tempe Ibu Imah, namun dalam memproduksi tempenya sudah mampu bersaing dan juga stabil setiap bulanya sedangan home industry tempe Ibu Urfatusholikha mengalami ketidak stabilan dalam proses produksinya. Penelitian ini menggunakan jenis penelitian lapangan (file Resesach) dengan pendekatan deskriptif kualitatif. Data yang didapatkan dalam penelitian ini berupa data primer dan data sekunder. Metode pengumpulan data melalui observasi, wawancara, dan dokumentasi. Data dianalisis melalui teknik reduksi data, penyajian data dan verivikasi data. Hasil penelitian menujukan bahwa home industry tempe Ibu Urfatusholikha dan Ibu Imah menerapkan strategi pemasaran (marketing mix) bauran pemasaran yang menggunakan elemen 4P+4C yaitu product, price, place, promotion, serta customer need, cost, convenience dan communication dari hal tersebut bisa dilihat pada segi tempat produksi home industry tempe Ibu Imah kurang strategis bagi produsen namun produsen tetap mengutamakan konsumen menurut ekonomi syariah berdasarkan hukum kausalitas yang harus diperhatikan sudah sesuai, dalam proses promosi yang dilakukan oleh home industry tempe Ibu Imah masih menggunakan cara yang sederhana tidak ada perkembangan hal ini belum sepenuhnya sesuai dengan sisitem ekonomi syariah karena Islam menganjurkan umatnya untuk selalu berupaya mencapai yang terbaik. Persaingan yang terjadi pada home industry tempe Ibu Urfatusholikha dan Ibu Imah bersaing sesuai ekonomi Islam dengan cara yang sehat artinya tidak menjatuhkan satu sama lain. ABSTRACT The tempe home industry, Mrs. Urfatusholikha and Mrs. Imah, is a business that stands in the same hamlet, both of which compete with differences starting from the tempe production process to its marketing. The tempe home industry, Mrs. Urfatusholikha, was established earlier than the tempe home industry, Mrs. Imah, but in producing the tempe it has been able to compete and is also stable every month, while the tempe home industry, Mrs. Urfatusholikha, has experienced instability in its production process. This study uses a type of field research (file research) with a qualitative descriptive approach. The data obtained in this study are in the form of primary data and secondary data. Data collection methods through observation, interviews, and documentation. Data were analyzed through data reduction techniques, data presentation and data verification. The results of the study showed that the tempe home industry Mrs. Urfatusholikha and Mrs. Imah implemented a marketing mix (marketing mix) strategy that used 4P + 4C elements, namely product, price, place, promotion, as well as customer need, cost, convenience and communication. From this it can be seen in terms of place of production of Ibu Imah's tempeh home industry is less strategic for producers but producers still prioritize consumers according to sharia economics based on the law of causality that must be considered is appropriate, in the promotion process carried out by the tempeh home industry Ibu Imah still uses a simple method there is no development of things This is not fully in accordance with the sharia economic system because Islam encourages its followers to always strive for the best. The competition that occurred in the tempe home industry, Mrs. Urfatusholikha and Mrs. Imah, competed according to the Islamic economy in a healthy way, meaning they did not bring each other down

Children’s Self Acceptance Raised by Single Mother: Analysis Study in Moslem Family

This research aims to analyze the self acceptance of children raised by single mother, due to death divorce or marriage problems between the parents. The methods of this research is a qualitative with case study approach, data is collected by depth interview toward 15 children as the informants which chosen through purposive sampling technique. Those 15 informants live in Aceh, NTB, Bandung, Depok, Bogor, Jakarta, Bekasi, and Tanggerang. Overall view of research result shows that children’s self acceptance raised by single mother influenced by factors of maternal education and environment. In addition, self acceptance concept also influenced by passage of time associated with the trauma healing process and memories recollecting of their parent’s death or life divorce. Those factors above will also influence their future achievement

Understanding the hydrological response of a headwater-dominated catchment by analysis of distributed surface–subsurface interactions

We computationally explore the relationship between surface–subsurface exchange and hydrological response in a headwater-dominated high elevation, mountainous catchment in East River Watershed, Colorado, USA. In order to isolate the effect of surface–subsurface exchange on the hydrological response, we compare three model variations that differ only in soil permeability. Traditional methods of hydrograph analysis that have been developed for headwater catchments may fail to properly characterize catchments, where catchment response is tightly coupled to headwater inflow. Analyzing the spatially distributed hydrological response of such catchments gives additional information on the catchment functioning. Thus, we compute hydrographs, hydrological indices, and spatio-temporal distributions of hydrological variables. The indices and distributions are then linked to the hydrograph at the outlet of the catchment. Our results show that changes in the surface–subsurface exchange fluxes trigger different flow regimes, connectivity dynamics, and runoff generation mechanisms inside the catchment, and hence, affect the distributed hydrological response. Further, changes in surface–subsurface exchange rates lead to a nonlinear change in the degree of connectivity—quantified through the number of disconnected clusters of ponding water—in the catchment. Although the runoff formation in the catchment changes significantly, these changes do not significantly alter the aggregated streamflow hydrograph. This hints at a crucial gap in our ability to infer catchment function from aggregated signatures. We show that while these changes in distributed hydrological response may not always be observable through aggregated hydrological signatures, they can be quantified through the use of indices of connectivity

The DAVID Gene Functional Classification Tool: a novel biological module-centric algorithm to functionally analyze large gene lists

The DAVID gene functional classification tool uses a novel fuzzy clustering algorithm to condense a list of genes or associated biological terms into organized classes of related genes or biology, called biological modules

Potential modulating effects of Allium mongolicum regel ethanol extract on rumen fermentation and biohydrogenation bacteria of dairy cows in vitro

The objective of this study was to evaluate the potential modulating effects of Allium mongolicum regel ethanol extract (AME) on rumen fermentation and biohydrogenation (BH) bacteria in vitro. Four Holstein cows were used as donors for the rumen fluid used in this study. In experiment 1, five treatments (supplemented with 0 mg/g, 1 mg/g, 2 mg/g, 3 mg/g, and 4 mg/g of AME based on fermentation substrate, respectively) were conducted to evaluate the effects of different levels of AME on fermentation status in vitro. The results showed that after 24 h of fermentation, MCP was reduced with AME supplementation (p < 0.05), and the multiple combinations of different combinations index (MFAEI) value was the highest with 3 mg/g of AME. In experiment 2, six treatments were constructed which contained: control group (A1); the unsaturated fatty acid (UFA) mixture at 3% concentration (A2); the mixture of A2 and 3 mg/g of AME (A3); 3 mg/g of AME (A4); the UFA mixture at 1.5% concentration (A5); the mixture of A5 and 3 mg/g of AME (A6). The abundance of bacterial species involved in BH was measured to evaluate the potential modulating effect of AME on rumen BH in vitro. Compared with the A1 group, the A3, A4, and A6 groups both showed significant decreases in the abundance of rumen BH microbial flora including Butyrivibrio proteoclasticus, Butyrivibrio fibrisolvens, Ruminococcus albus and Clostridium aminophilum (p < 0.01). The A3 group was less inhibitory than A4 in the abundance of B. proteoclasticus, B. fibrisolvens, and R. albus, and the inhibitory effect of the A6 group was higher than that of A4. In conclusion, the supplementation with 3 mg/g of AME could modulate the rumen fermentation and affect BH key bacteria, which suggests that AME may have the potential to inhibit the rumen BH of dairy cows