Designing Air Intake Ducts for High Speed Flight

A proven duct flow model is used to examine the influence of the intake duct geometric and inlet flow parameters on the pressure recovery performance of intake ducts for high speed flight. The geometric parameters include: the inlet parallel pipe length, the diffuser cone angle, the length of the faired transition from the pipe to diffuser cone as well as the degree of the fairing. The inlet flow parameters examined are: the boundary layer momentum thickness, the velocity profile shape and the turbulence level. The inlet parameter values used simulate those following a normal shock wave — turbulent boundary layer interaction inside the intake duct, i.e. they simulate the conditions at the inlet to the diffuser of a supersonic intak

STR-920: STRUCTURAL BEHAVIOUR OF REINFORCED HIGH PERFORMANCE CONCRETE COLUMNS SUBJECTED TO MONOTONIC AXIAL LOADING

This paper presents the results of experimental and analytical investigations on the structural performance of high performance reinforced concrete (HPC) columns subjected to monotonic axial loading. Reinforced columns made of self-consolidating concrete (SCC), engineered cementitious composite (ECC) and ultra-high performance concrete (UHPC) were tested to failure under axial loading. The test variables included concrete strength and length/slenderness of columns (classified as short and long columns). The UHPC and ECC columns demonstrated excellent ductility and higher energy absorbing capacity compared to their SCC counterparts. UHPC columns also illustrated higher ultimate load capacity compared to both ECC and SCC columns. The efficiency of UHPC and ECC columns was also judged based on strength and ductility ratio compared to their SCC counterparts. Existing models and other Code based equations were used to predict the axial load capacity as a part of analytical investigation. The predictions suggested the need for the modification of existing models/Code based equations for UHPC and ECC columns

Crystal nucleation mechanism in melts of short polymer chains under quiescent conditions and under shear flow

We present a molecular dynamics simulation study of crystal nucleation from undercooled melts of n-alkanes, and we identify the molecular mechanism of homogeneous crystal nucleation under quiescent conditions and under shear flow. We compare results for n-eicosane(C20) and n-pentacontahectane(C150), i.e. one system below the entanglement length and one above. Under quiescent conditions, we observe that entanglement does not have an effect on the nucleation mechanism. For both chain lengths, the chains first align and then straighten locally. Then the local density increases and finally positional ordering sets in. At low shear rates the nucleation mechanism is the same as under quiescent conditions, while at high shear rates the chains align and straighten at the same time. We report on the effects of shear rate and temperature on the nucleation rates and estimate the critical shear rates, beyond which the nucleation rates increase with the shear rate. We show that the viscosity of the system is not affected by the crystalline nuclei.Comment: 9 page

Effect of Rock Phosphate and Inoculation Arbuscular Mycorhizal Fungi and Rhizobium sp Bacteria on Growth of Soybean (Glycine max L.)

Tanaman kedelai di Indonesia banyak dimanfaatkan sebagai sumber bahan baku makanan diantaranya tahu dan tempe. Rendahnya produksi kedelai nasional salah satunya disebabkan hasil produksinya yang masih rendah. Penelitian bertujuan untuk mengkaji pengaruh batuan fosfat, cendawan mikoriza arbuskular dan bakteri Rhizobium sp terhadap pertumbuhan tanaman kedelai. Penelitian dilaksanakan pada 28 Juni – 21 September 2022 di Dusun Mlati RT 02 RW 03, Desa Tinanding, Kecamatan Godong, Kabupaten Grobogan dan di Laboratorium Ekologi dan Produksi Tanaman, dan Laboratorium Fisiologi dan Pemuliaan Tanaman Fakultas Peternakan dan Pertanian, Universitas Diponegoro, Semarang. Penelitian menggunakan RAL monofaktor dengan 6 perlakuan dan 5 ulangan. Perlakuan terdiri dari P1: Batuan Fosfat, P2 : CMA, P3 : Bakteri Rhizobium sp, P4 : Batuan Fosfat Bakteri Rhizobium sp, P5 : Batuan Fosfat + CMA, P6 : Batuan Fosfat + CMA + Bakteri Rhizobium sp. Hasil penelitian menunjukkan bahwa perlakuan CMA memberikan pengaruh signifikan terhadap parameter jumlah daun dan jumlah cabang, sedangkan perlakuan BP dan Rhizobium sp tidak berpengaruh siginifikan terhadap parameter pertumbuhan tanaman kedelai.

Assessment and Comparison of Obstetric Characteristics and Perinatal Outcomes of Rural Population of South Africa

Context: Maternal and perinatal morbidity and mortality are the major health problems confronting many developing countries including South Africa. In developing countries, interventions that are known to be effective in lowering maternal and perinatal mortality and morbidity are not universally provided. In the past, access to maternal health services was a major problem for rural and black communities of SA.Objective: The objectives were to assess and compare the demographic and obstetric characteristics and perinatal outcome indicators over time.Study design, Setting and Subjects: A retrospective comparative study was conducted for women delivered during 1999 (3875) and 2004 (3912) at a rural Empangeni hospital. Multivariate logistic regression was undertaken to determine the significant predictors for outcome variables.Results: The prevalence of teenage pregnancy and pregnancy of younger women (<25 years) were increased significantly by 3% and 8% respectively (p < 0.05). There was a significant reduction of pregnancies among higher parity (parity 5 or more) women during 2004 (p < 0.05). There weresignificant reductions of eclampsia, anaemia, and post partum  haemorrhage during delivery for the year 2004. Breech presentation was 3.75 times more likely to deliver preterm and 5.45 times more likely todeliver low birth weight babies. Pregnancy induced hypertension was more likely to have preterm (OR =3.50) and low birth weight babies (OR = 2.09). Eclampsia was also a risk factor for preterm (OR = 6.14),and low birth weight babies (OR = 18.42).Conclusion: Further research is needed to find the causes of higher rate of teenage pregnancies and simple strategies to combat high rates of negative perinatal outcomes.Key Words: Pregnancy Complications, Outcome, Rural Healthcar

Fault-tolerance thresholds for the surface code with fabrication errors

The construction of topological error correction codes requires the ability to fabricate a lattice of physical qubits embedded on a manifold with a non-trivial topology such that the quantum information is encoded in the global degrees of freedom (i.e. the topology) of the manifold. However, the manufacturing of large-scale topological devices will undoubtedly suffer from fabrication errors---permanent faulty components such as missing physical qubits or failed entangling gates---introducing permanent defects into the topology of the lattice and hence significantly reducing the distance of the code and the quality of the encoded logical qubits. In this work we investigate how fabrication errors affect the performance of topological codes, using the surface code as the testbed. A known approach to mitigate defective lattices involves the use of primitive SWAP gates in a long sequence of syndrome extraction circuits. Instead, we show that in the presence of fabrication errors the syndrome can be determined using the supercheck operator approach and the outcome of the defective gauge stabilizer generators without any additional computational overhead or the use of SWAP gates. We report numerical fault-tolerance thresholds in the presence of both qubit fabrication and gate fabrication errors using a circuit-based noise model and the minimum-weight perfect matching decoder. Our numerical analysis is most applicable to 2D chip-based technologies, but the techniques presented here can be readily extended to other topological architectures. We find that in the presence of 8% qubit fabrication errors, the surface code can still tolerate a computational error rate of up to 0.1%.Comment: 10 pages, 15 figure

Radiation pattern of two identical emitters driven by a Laguerre-Gaussian beam: An atom nanoantenna

We study the directional properties of a radiation field emitted by a geometrically small system composed of two identical two-level emitters located at short distances and driven by an optical vortex beam, a Laguerre-Gaussian beam which possesses a structured phase and amplitude. We find that the system may operate as a nanoantenna for controlled and tunable directional emission. Polar diagrams of the radiation intensity are presented showing that a constant phase or amplitude difference at the positions of the emitters plays an essential role in the directivity of the emission. We find that the radiation patterns may differ dramatically for different phase and amplitude differences at the positions of the emitters. As a result the system may operate as a two- or one-sided nanoantenna. In particular, a two-sided highly focused directional emission can be achieved when the emitters experience the same amplitude and a constant phase difference of the driving field. We find a general directional property of the emitted field that when the phase differences at the positions of the emitters equal an even multiple of \pi/4, the system behaves as a two-sided antenna. When the phase difference equals an odd multiple of \pi/4, the system behaves as an one-sided antenna. The case when the emitters experience the same phase but different amplitudes of the driving field is also considered and it is found that the effect of different amplitudes is to cause the system to behave as a uni-directional antenna radiating along the interatomic axis.Comment: published versio