The 3-D viscous flow CFD analysis of the propeller effect on an advanced ducted propeller subsonic inlet

A time marching Navier-Stokes code called PARC3D was used to study the 3-D viscous flow associated with an advanced ducted propeller (ADP) subsonic inlet at take-off operating conditions. At a free stream Mach number of 0.2, experimental data for the inlet-with-propeller test model indicated that the airflow was attached on the cowl windward lip at an angle of attack of 25 degrees became unstable at 29 degrees, and separated at 30 degrees. An experimental study with a similar inlet and with no propeller (through-flow) indicated that flow separation occurred at an angle of attack a few degrees below the value observed when the inlet was tested with the propeller. This tends to indicate that the propeller exerts a favorable effect on the inlet performance. During the through-flow experiment a stationary blockage device was used to successfully simulate the propeller effect on the inlet flow field at angles of attack. In the present numerical study, this flow blockage was modeled via a PARC3D computational boundary condition (BC) called the screen BC. The principle formulation of this BC was based on the one-and-half dimension actuator disk theory. This screen BC was applied at the inlet propeller face station of the computational grid. Numerical results were obtained with and without the screen BC. The application of the screen BC in this numerical study provided results which are similar to the results of past experimental efforts in which either the blockage device or the propeller was used

Analysis of an advanced ducted propeller subsonic inlet

A time marching Navier-Stokes code called PARC (PARC2D for 2-D/axisymmetric and PARC3D for 3-D flow simulations) was validated for an advanced ducted propeller (ADP) subsonic inlet. The code validation for an advanced ducted propeller (ADP) subsonic inlet. The code validation was implemented for a non-separated flow condition associated with the inlet operating at angles-of-attack of 0 and 25 degrees. The inlet test data were obtained in the 9 x 15 ft Low Speed Wind Tunnel at NASA Lewis Research Center as part of a cooperative study with Pratt and Whitney. The experimental study focused on the ADP inlet performance for take-off and approach conditions. The inlet was tested at a free stream Mach number of 0.2, at angles-of-attack between O and 35 degrees, and at a maximum propeller speed of 12,000 RPM which induced a corrected air flow rate of about 46 lb/sec based on standard day conditions. The computational grid and flow boundary conditions (BC) were based on the actual inlet geometry and the funnel flow conditions. At the propeller face, two types of BC's were applied: a mass flow BC and a fixed flow properties BC. The fixed flow properties BC was based on a combination of data obtained from the experiment and calculations using a potential flow code. Comparison of the computational results with the test data indicates that the PARC code with the propeller face fixed flow properties BC provided a better prediction of the inlet surface static pressures than the predictions when the mass flow BC was used. For an angle-of-attack of 0 degrees, the PARC2D code with the propeller face mass flow BC provided a good prediction of inlet static pressures except in the region of high pressure gradient. With the propeller face fixed flow properties BC, the PARC2D code provided a good prediction of the inlet static pressures. For an angle-of-attack of 25 degrees with the mass flow BC, the PARC3D code predicted statis pressures which deviated significantly from the test data; however, with the fixed flow properties BC, a good comparison with the test data was obtained

Analytical and experimental studies of a short compact subsonic diffuser for a two-dimensional supersonic inlet

An experimental study of a two-dimensional supersonic inlet with a short compact subsonic diffuser, length to exit diameter (dl/d) ratio of 1.25, was conducted to investigate the impact of the short diffuser on inlet performance at low speeds and to assess the diffuser subsonic performance for a simulated diffuser flow corresponding to high-speed inlet conditions near the design flight Mach number of 2.2. For the low-speed testing, a drooped lip was employed to improve the inlet performance at a high angle of attack. For the simulated high-speed testing, air was blown through slots or discrete nozzles as an active boundary-layer control. The results from the low-speed performance test were compared with the results from a previous test program on the same inlet with a long subsonic diffuser (dl/d = 4.5). The comparison indicates that inlet recovery was not affected by the use of the short diffuser for either the baseline (no droop) or the drooped cowl lip configuration. However, the inlet baseline distortion for the short diffuser configuration was substantially higher than for the long diffuser. A comparison of the two configurations with a 70 deg drooped lip showed no significant difference in distortion. For the portion of the experimental program in which diffuser conditions for high-speed flight were simulated, diffuser-induced flow separation occurred. This separation was predicted from an analytical study that used the Hess potential flow panel method and the Herring two-dimensional boundary-layer analysis computer codes. The flow separated mainly on the diffuser ramp. Subsequent tests in which boundary-control systems were utilized showed that blowing with either slots or discrete nozzles could suppress the flow separation in the short subsonic diffuser, thereby substantially improving the diffuser performance

Effect of Calcium on the Growth of Melon (Cucumis melo L.)

Melon (Cucumis melon L.) is an important crop for the world economy, and it is one of the most valuable crops in the market. The cultivation of melon in Cambodia is still low due to the unclear use of varieties and the inappropriate cultivation techniques that cannot achieve high yields. This is the reason why this research is conducted. The objectives of this research are: 1. to compare the growth of melon varieties with calcium in Svay Rieng province condition, 2. to study the appropriate level of calcium fertilizer on melon yield in the supplementary stage, and 3. to study the fruit quality of the five melon varieties. This experiment was arranged into Randomized Complete Block Design (RCBD) with 4 replications and 20 treatments equivalent to 80 plots totallyat the Agricultural Station of Svay Rieng University. The results showed that the application of calcium fertilizer and foliar spraying once every 7 days resulted in the highest growth of melon plants. The use of different varieties showed that the melon varieties V4 (Lady Green = 547) and V2 (Lady Gold = 518) received the highest number of seeds. Thus, in summary, comparing the growth of 5 melon cultivars with 4 levels of calcium fertilizer, the results showed that the application of calcium fertilizer and leaf spray every 4 days, every 7 days, made the melon crop. Growth, yield, and fruit quality are excellent. The use of different varieties showed that only the melon varieties V4, V1, and V2 are the best

The potential impact of climate change on 'Nezara viridula' (L.) (Hemiptera: Pentatomidae) and its parasitoid, 'Trichopoda giacomelii' Blanchard (Diptera: Tachinidae) in Cambodia and Australia: Ecological, behavioural and physiological assessments

'Nezara viridula' (L.) (Hemiptera: Pentatomidae) is a cosmopolitan, polyphagous heteropteran insect that causes economic damage to many crop species worldwide. Despite several interventions attempts, 'N. viridula' has remained a significant pest in certain regions of Cambodia and eastern Australia, particularly those where soybean and nut crops are cultivated. Recently, 'Trichopoda giacomelii' Blanchard (Diptera: Tachinidae), a species native to Argentina was established in Australia as an effective biological control agent for 'N. viridula' in one instance. However, with predicted climate change, the range of the pest could expand or change and the relationship between the pest and the parasitoid could also change in response to altered temperature and precipitation regimes. Changed climatic conditions could affect the pest status and geographic range of 'N. viridula' as well as the efficacy of the parasitoid. Climate change will potentially affect the interactions between factors such as temperature, humidity, light, food, and the wellbeing of the pest and the parasitoid and the relationship between the two. The aims of this study were (i) to evaluate the sampling methods of arthropods on soybean crops in Cambodia, in terms of accuracy of the use of the two main sampling methods: sweep netting and beat sheeting; (ii) to measure the effect of changed temperature and moisture regimes on 'N. viridula' and 'T. giacomelii' life cycles in populations from contrasting climatic regimes (Breeza and Grafton); (iii) to measure the effect of changed temperature and moisture regimes on the ability of the parasitoids to parasitize 'N. viridula'; and (iv) to investigate the various physiological variables of 'N. viridula' under the stress of temperature

Pendidikan Kesehatan tentang Sikap Tubuh Ergonomis dan Pola Aktivitas untuk mencegah Muskuloskeletal Disorders pada Remaja

Latar belakang: Pandemi COVID 19 selama kurun waktu dua tahun ini telah menghentikan banyak aktivitas manusia, termasuk remaja yang harus  belajar secara online di rumah. Aktivitas fisik yang kurang adekuat dan juga sikap kerja tubuh selama beraktivitas di rumah yang tidak memperhatikan prinsip ergonomis dalam jangka waktu yang lama, memberikan dampak terhadap kesehatan terutama munculnya gangguan muskuloskeletal mulai dari yang ringan-sedang pada remaja. Tujuan: melakukan pendidikan kesehatan tentang sikap tubuh ergonomis dan pola hidup sehat untuk mencegah terjadinya musculoskeletal disorders (MSDs). Metode: Pengabdian kepada masyarakat berbasis riset dilakukan dengan metode pendidikan kesehatan dengan topik sikap tubuh ergonomis dan pola aktivitas/olahraga dalam rangka mencegah gangguan tulang dan sendi. Peserta yang hadir sebanyak 50 orang. Hasil : Tingkat pengetahuan remaja tentang bagaiman pola aktivitas dan olahraga yang ideal untuk remaja berada pada tingkat sedang yaitu sebanyak 41 anak (82%) dan tingkat pengetahuan tentang sikap ergonomis tubuh dalam aktivitas sehai-hari dalam mencegah musculoskeletal disorder sudah mencapai 96% tingkat pengetahuan yang tinggi. Kesimpulan: Pendidikan kesehatan tentang sikap tubuh ergonomis sangat penting dilakukan pada remaja untuk membekali pengetahuan, sikap dan perilaku sikap tubuh ergonomis yang baik dan benar dalam aktivitas sehari-hari sehingga mencegah terjadinya MSDs. Dengan terjaganya kesehatan otot, tulang, dan sendi maka kualitas hidup dan produktivitas remaja akan terpelihara bahkan meningkat.   Kata kunci: Ergonomi, sikap tubuh, musculoskeletal disorders, remaj

Factors Associated with Negative Direct Sputum Examination in Asian and African HIV-Infected Patients with Tuberculosis (ANRS 1260)

OBJECTIVE: To identify factors associated with negative direct sputum examination among African and Cambodian patients co-infected by Mycobacterium tuberculosis and HIV. DESIGN: Prospective multicenter study (ANRS1260) conducted in Cambodia, Senegal and Central African Republic. METHODS: Univariate and multivariate analyses (logistic regression) were used to identify clinical and radiological features associated with negative direct sputum examination in HIV-infected patients with positive M. tuberculosis culture on Lowenstein-Jensen medium. RESULTS: Between September 2002 and December 2005, 175 co-infected patients were hospitalized with at least one respiratory symptom and pulmonary radiographic anomaly. Acid-fast bacillus (AFB) examination was positive in sputum samples from 110 subjects (63%) and negative in 65 patients (37%). Most patients were at an advanced stage of HIV disease (92% at stage III or IV of the WHO classification) with a median CD4 cell count of 36/mm³. In this context, we found that sputum AFB negativity was more frequent in co-infected subjects with associated respiratory tract infections (OR = 2.8 [95%CI:1.1-7.0]), dyspnea (OR = 2.5 [95%CI:1.1-5.6]), and localized interstitial opacities (OR = 3.1 [95%CI:1.3-7.6]), but was less frequent with CD4 ≤ 50/mm³ (OR = 0.4 [95%CI:0.2-0.90), adenopathies (OR = 0.4 [95%CI:0.2-0.93]) and cavitation (OR = 0.1 [95%CI:0.03-0.6]). CONCLUSIONS: One novel finding of this study is the association between concomitant respiratory tract infection and negative sputum AFB, particularly in Cambodia. This finding suggests that repeating AFB testing in AFB-negative patients should be conducted when broad spectrum antibiotic treatment does not lead to complete recovery from respiratory symptoms. In HIV-infected patients with a CD4 cell count below 50/mm3 without an identified cause of pneumonia, systematic AFB direct sputum examination is justified because of atypical clinical features (without cavitation) and high pulmonary mycobacterial burden

The Adaptation of Tropical Perennial Grasses to Abiotic Constraints in Sandy Soils

The inclusion of perennial forage grasses in agricultural systems has the potential to improve livestock production, ecosystem health and climate resilience. However, the establishment of forage grasses in many ecosystems is challenged by abiotic stresses. Perennial forage grass species are often grown in environments with limited water availability following establishment and rely on accessing water deep in the soil profile to survive. In sandy soils with rapid surface drying and hardpan soils, root growth to greater soil depths enables forage grass species to survive soil surface drying following establishment and is assisted by increased root growth rate and greater ability to penetrate compacted soils. In addition, the presence of large rhizomes in rhizomatous grasses promotes post-harvest regrowth rate and post-establishment survival or drought resistance without relying on root access to water at depth. Therefore, characterisation of these traits in perennial forages grass species will provide an objective means for species selection, based on the local abiotic constraints. Five glasshouse experiments were conducted to identify the mechanisms of perennial grass adaptation to abiotic constraints in ecosystems with rapid surface-drying soils and hardpan soils. The first experiment assessed variations in vertical root growth rates between tropical perennial forage grass species, and characterised traits associated with higher vertical root growth rates. Tropical forage grasses, namely Urochloa (basionym: Brachiaria) brizantha Mekong Briz, Urochloa decumbens cv. Basilisk, Urochloa humidicola cv. Tully, Urochloa hybrid cv. Mulato II, Urochloa mosambicensis cv. Nixon, Megathyrsus maximus (basionym: Panicum maximum) cv. Tanzânia, and Setaria sphacelata cv. Solander, were established in large rhizotrons that facilitated measurement of the rate of root depth development, the rate of root length development, photosynthesis and morphological traits. Rapid vertical root growth with narrow root angle, high photosynthetic rate, high ratio of root length to leaf area and high percentage of fibrous roots were apparent mechanisms that enabled M. maximus and U. mosambicensis to establish deep roots faster than other forage grass species. M. maximus and U. mosambicensis were identified as species with exploitative growth strategy. Wide root angles and a higher proportion of shallow root distribution to 10 cm depth were associated with decreased vertical root growth rate. The exponential rate of root depth development per growing degree day increased with average root diameter in U. humidicola and Urochloa hybrid Mulato II, indicating a conservative growth strategy. The second and third experiments investigated traits correlated with vertical root growth rates, the stability of variation between grasses in root and shoot growth in summer and winter, and relationships between vertical root growth rates and post-establishment drought resistance, using 12 bermudagrass ecotypes (Cynodon spp.) from varied Australian climatic zones. Previous field experiments using these ecotypes found that drought resistance was promoted by water extraction; however, relationships between vertical root growth rates and drought resistance are poorly understood. The 12 ecotypes were established in large rhizotrons during experiments in mild winter (17 to 24 °C mean temperature) and summer (19 to 38 °C mean temperature). A proportion of root length became inactive due to seasonal root death in winter conditions, and vertical root growth rate during winter significantly decreased as this proportion increased. During summer, vertical root growth rate significantly increased with a greater tiller appearance rate but significantly decreased with increased root distribution to 10 cm depth. Despite the inconsistency of variation between ecotypes in shoot growth, the genotypic rank of root length, root dry weight, vertical root growth rate and leaf area were consistent in both seasons. Positive correlations between vertical root growth rate measured in both seasons and drought resistance were found, suggesting that increased vertical root growth rate promotes active roots for extracting water at the greater depth of soil profiles in association with post-establishment drought resistance. The fourth experiment was conducted to examine variations in root penetration in forage grass species and characterise forage grass species with a high root penetration capability using wax layers to measure root penetration. U. brizantha, U. decumbens, U. humidicola, U. hybrid cv. Mulato II, U. mosambicensis, U. ruziziensis, M. maximus, and S. sphacelata, Panicum coloratum cv. Makarikariense, Paspalum scrobiculatum cv. BA96 10 were evaluated. Root diameters were determined for each species from seedlings grown in growth pouches. Increased root penetration at high resistance was associated with larger root diameter and increased vertical root growth rate. The results indicate that M. maximus can avoid water stress during soil surface drying better than other forage species by accessing profile moisture due to its greater vertical root growth rate and capability of root penetration. The fifth experiment analysed variation in rhizome growth and correlated traits to examine relationships between rhizome growth and aridity index, rainfall and evapotranspiration, using bermudagrass ecotypes collected from environments with varying aridity indices. A total of 142 ecotypes collected from regions in Australia with varied aridity indices were grown in pots for 14 weeks during the summer in South Australia to measure rhizomes and plant traits. Rhizome growth between ecotypes from arid (aridity indices less than 0.65) and non-arid environments was not significantly different. Bermudagrasses with the largest rhizomes were amongst those ecotypes that originated from arid environments. Moreover, rhizome growth of bermudagrass ecotypes from arid environments had a positive response to environments with more humid climate conditions in winter, while the rest of the year is dry. Amongst bermudagrass ecotypes from both regions, increased rhizome growth during establishment was associated with greater leaf width and decreased internode length. Through the combined results of the five experiments presented within this thesis, several mechanisms that enable perennial grass adaptation to abiotic constraints in ecosystems with rapid surface-drying soils and hardpan soils were identified. Increased vertical root growth rate was associated with narrow root angle, greater leaf area and greater shoot growth. Increased root penetration at high resistance was associated with large root diameter and increased vertical growth rate. Post-establishment drought resistance is promoted by greater vertical root growth rate. Bermudagrass ecotypes with the greatest rhizome growth originated from arid regions. In relation to plant traits, greater leaf width and decreased internode length were characteristics of bermudagrasses with large rhizomes. This research provides new insights on the beneficial characteristics of vertical root growth in perennial forage grasses that can be well-adapted to sandy soils with rapid surface drying and hardpan soils. For field application, M. maximus appears to be well-adapted to sandy soils because it had rapid vertical root growth and great capability of root penetration that can be associated with drought resistance and high yield. Caution is advised when recommending M. maximus because it expressed an exploitative growth strategy that is associated with high nutrient requirement to sustain production. Furthermore, results from bermudagrass ecotypes showed that drought-resistant perennial grasses did not have specific traits that differed from drought-susceptible grasses. These findings indicate that drought resistance in perennial grasses may involve complex trait interplay. Therefore, the drought resistance and high yield of forage species such as U. humidicola and U. hybrid cv. Mulato II may be associated with other characteristics, but not the vertical root growth rate. These species that expressed a conservative growth strategy may be well-adapted to a wide range of agronomic conditions.Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 202