Numerical simulation of steady and unsteady asymmetric vortical flow

The unsteady, compressible, thin-layer, Navier-Stokes (NS) equations are solved to simulate steady and unsteady, asymmetric, vortical laminar flow around cones at high incidences and supersonic Mach numbers. The equations are solved by using an implicit, upwind, flux-difference splitting (FDS), finite-volume scheme. The locally conical flow assumption is used and the solutions are obtained by forcing the conserved components of the flowfield vector to be equal at two axial stations located at 0.95 and 1.0. Computational examples cover steady and unsteady asymmetric flows around a circular cone and its control using side strakes. The unsteady asymmetric flow solution around the circular cone has also been validated using the upwind, flux-vector splitting (FVS) scheme with the thin-layer NS equations and the upwind FDS with the full NS equations. The results are in excellent agreement with each other. Unsteady asymmetric flows are also presented for elliptic- and diamond-section cones, which model asymmetric vortex shedding around round- and sharp-edged delta winds

Assessment Cu, Ni and Zn pollution in the surface sediments in the Southern Peninsular Malaysia using cluster analysis, ratios of geochemical nonresistant to resistant fractions, and geochemical indices.

The intertidal sediment samples collected in May 2007 from 12 sampling sites in the southern part of Peninsular Malaysia, were determined for the total concentrations of Cu, Ni and Zn and their four geochemical fractions. The total concentrations (μg/g dry weight) of Cu, Ni and Zn ranged from 9.48 to 115.82, 12.95 to 36.18 and 45.35 to 136.56, respectively. The ratios of nonresistant to resistant fractions based on geochemical analysis revealed that the Pantai Lido and Senibong had > 1.0, indicating > 50% of the total concentrations of Cu, Ni and Cu were contributed by anthropogenic sources. This is well complemented by the cluster analysis in which Pantai Lido and Senibong are clustered together based on the three metals clustering pattern. By using Fe as a normalizing element, Cu found at Pantai Lido and Senibong showed > 1.5 for the enrichment factor (EF), which indicated that the Cu was delivered from non-crustal materials or anthropogenic origins while all sampling sites showed Ni and Zn may be entirely from crustal materials. Based on the geoaccumulation index (Igeo) (Müller, 1981), similar pattern was also found for Pantai Lido and Senibong in which again only Cu concentrations ranged from 1-2, indicating ‘moderate pollution’ (Igeo 1 < 2; Class 2).while other sites can be considered as ‘unpolluted’ (Igeo < 0; Class 0) by Cu, Ni and Zn. Ratios of NR/R exhibited better in the assessment of polluted sites while EF and Igeo should be revised according to Malaysian sedimentary characteristics. This study should prompt more biochemical and molecular studies on the intertidal molluscs from the Straits of Johore since the identified two sites are located in the Straits of Johore, especially the commercial mussel Perna viridis

Recent advances in numerical simulation and control of asymmetric flows around slender bodies

The problems of asymmetric flow around slender bodies and its control are formulated using the unsteady, compressible, thin-layer or full Navier-Stokes equations which are solved using an implicit, flux-difference splitting, finite-volume scheme. The problem is numerically simulated for both locally-conical and three-dimensional flows. The numerical applications include studies of the effects of relative incidence, Mach number and Reynolds number on the flow asymmetry. For the control of flow asymmetry, the numerical simulation cover passive and active control methods. For the passive control, the effectiveness of vertical fins placed in the leeward plane of geometric symmetry and side strakes with different orientations is studied. For the active control, the effectiveness of normal and tangential flow injection and surface heating and a combination of these methods is studied

Properties of a hand-printed Chinese character recognizer based on contexted vector quantization

A hand-printed Chinese character recognizer based on Contextual Vector Quantization (CVQ) has been built previously. In this paper, several properties of the recognizer will be discussed and the recognizer of 4516 Chinese characters has a successful rate of 91.0%. Then the output of the recognizer is passed to a language model which when applied to recognize a passage of about 1200 characters raises the rate from 91.5% to 97.5%.published_or_final_versio

Harnessing high-dimensional hyperentanglement through a biphoton frequency comb

Quantum entanglement is a fundamental resource for secure information processing and communications, where hyperentanglement or high-dimensional entanglement has been separately proposed towards high data capacity and error resilience. The continuous-variable nature of the energy-time entanglement makes it an ideal candidate for efficient high-dimensional coding with minimal limitations. Here we demonstrate the first simultaneous high-dimensional hyperentanglement using a biphoton frequency comb to harness the full potential in both energy and time domain. The long-postulated Hong-Ou-Mandel quantum revival is exhibited, with up to 19 time-bins, 96.5% visibilities. We further witness the high-dimensional energy-time entanglement through Franson revivals, which is observed periodically at integer time-bins, with 97.8% visibility. This qudit state is observed to simultaneously violate the generalized Bell inequality by up to 10.95 deviations while observing recurrent Clauser-Horne-Shimony-Holt S-parameters up to 2.76. Our biphoton frequency comb provides a platform in photon-efficient quantum communications towards the ultimate channel capacity through energy-time-polarization high-dimensional encoding

Near-infrared Hong-Ou-Mandel interference on a silicon quantum photonic circuit

Near-infrared Hong-Ou-Mandel quantum interference is observed in silicon nanophotonic directional couplers with raw visibilities on-chip at 90.5%. Spectrally-bright 1557-nm two-photon states are generated in a periodically-poled KTiOPO4 waveguide chip, serving as the entangled photon source and pumped with a self-injection locked laser, for the photon statistical measurements. Efficient four-port coupling in the communications C-band and in the high-index-contrast silicon photonics platform is demonstrated, with matching theoretical predictions of the quantum interference visibility. Constituents for the residual quantum visibility imperfection are examined, supported with theoretical analysis of the sequentially-triggered multipair biphoton contribution and techniques for visibility compensation, towards scalable high-bitrate quantum information processing and communications.Comment: 15 pages, 6 figure

Nonlocal cancellation of multi-frequency-channel dispersion

We present an investigation of the temporal correlation of time-energy entangled photon pairs propagating through multi-frequency-channel dispersive media, in which photon spectra spread over multiple discrete frequency channels with dispersions. We have observed more complex coincidence structures including double coincidence envelopes and dependence on frequency detuning that are absent in the single-channel case. Our results on the correlation of the time-energy photonic entanglement in dispersive media with channel divisions would impact the fields of quantum metrology and communication.United States. Defense Advanced Research Projects Agency. Information in a Photon Program (Army Research Office Grant W911NF-10-1-0416

A preliminary study on kenaf (Hibiscus cannabinus L.) accessions for fibre and pulp production (Kajian awal aksesi kenaf (Hibiscus cannabinus L.) untuk penghasilan serabut dan pulpa)

Abstrak Kenaf (Hibiscus cannabinus L.) merupakan pokok semusim daripada famili Malvaceae yang digunakan sebagai bahan asas dalam penghasilan tali, karung, kanvas dan permaidani. Sejumlah 16 aksesi kenaf telah dikaji dari segi pertumbuhan termasuklah bentuk daun, pigmentasi batang, saiz biji benih (mengikut isipadu) dan fenologi bagi setiap aksesi. Bentuk daun terbahagi kepada jejari atau bulat. Pigmentasi batang pula adalah hijau muda, hijau gelap atau hijau kemerahan dan ini boleh dibezakan antara aksesi. Abstract Kenaf (Hibiscus cannabinus L.), a herbaceous annual plant of the Malvaceae family, is one of the important source of raw materials for the traditional production of rope, sack, canvas and carpet. A total of 16 accessions were evaluated for growth performance including leaf shape, stem pigmentation, seed size (by volume) and the phenology of each accession. Leaf shape can be classified as palmate or cordate. Stem pigmentation is either light green, dark green or reddish green and it can be distinguished among all accessions. The tallest accessions were MK 13, MK 12, MK 23 and MK 22, while MK 19, MK 13, MK 04 and MK 28 showed the largest basal stem diameter. Accessions that gave high fibre and pulp yields such as MK 04, MK 12, MK 13, MK 19, MK 21, MK 22, MK 23, MK 25 and MK 28 were chosen for further testing on fibre and pulp production at multilocations