Examination of the LBM in simulation of microchannel flow in transitional regime

The gas flows in micro-electro-mechanical systems possess relatively large Knudsen number and usually belong to the slip flow and transitional flow regimes. Recently the lattice Boltzmann method (LBM) was proposed by Nie et al. in Journal of Statistical Physics, vol. 107, pp. 279-289, in 2002 to simulate the microchannel and microcavity flows in the transitional flow regime. The present article intends to test the feasibility of doing so. The results of using the lattice Boltzmann method and the direct simulation Monte Carlo method show good agreement between them for small Kn (Kn = 0.0194), poor agreement for Kn = 0.194, and large deviation for Kn = 0.388 in simulating microchannel flows. This suggests that the present version of the lattice Boltzmann method is not feasible to simulate the transitional channel flow.

Configuration optimization of hypersonic vehicles under transitional flow conditions

The rarefied gas effects on several configurations are investigated under hypersonic flow conditions using the direct simulation Mont Carlo method. It is found that the Knudsen number, the Mach number, and the angle of attack all play a mixed role in the aerodynamics of a flat plate. The ratio of lift to drag decreases as the Knudsen number increases. Studies on 3D delta wings show that the ratio of lift to drag could be increased by decreasing the wing thickness and/or by increasing the wing span. It is also found that the waveriders could produce larger ratio of lift to drag as compared with the delta wing having the same length, wing span, and cross section area.

Fish Fauna Status in the Lugu Lake with PreliminaryAnalysis on Cause and Effect of Human Impacts

泸沽湖是位于滇西北的一个断陷湖泊，为滇川两省共有。文献记录泸沽湖原始的鱼类区系由4种鱼 类组成，隶属于裂腹鱼属和泥鳅属。于2001，2002和2004年3次考察泸沽湖，进行标本采集和鱼类区系现状调 查。查看了采自泸沽湖的鱼类标本518号，结合历史上的采集记录和大量相关文献，确定泸沽湖记录有鱼类12 种，隶属于3目4科10属；过度捕捞和毁林造成的泥石流是泸沽湖鱼类区系变化的主要原因。

The diverse Grania fauna (Clitellata : Enchytraeidae) of the Esperance area, Western Australia, with descriptions of two new species

Seven species of the marine enchytraeid genus Grania Southern, 1913 are described from sediments sampled during the 2003 International Workshop on the Marine Flora and Fauna of Esperance Bay and the Recherche Archipelago, on the southern coast of Western Australia. Two species are new to science, the euryhaline Tasmanian G. dolichura Rota and Erseus, 2000 represents a new record for the state, and the remaining four species were known from other parts of Western Australia. Grania quaerens sp. n. is recognized by having a high chaetal index (= 5 short chaetal foot), small coelomocytes, penial apparati with long whip-like terminal stylets, conspicuous spermathecae with ectally bulbous ducts, and ectally granulated ampullae housing sperm rings in their ental region. Grania sperantia sp. n. is readily distinguishable by the complete lack of lateral chaetae, a multiple-banded pattern of the clitellum, extremely long sperm funnels, and the intrasegmental location of the spermathecal pores. The latter new species and four others in the collection (G. bykane Coates, 1990, G. crassiducta Coates, 1990, G. dolichura, and G. ersei Coates, 1990) are remarkable in possessing the head organ, a sensory structure unique to Grania that was not noted previously in Western Australian species. When considering the whole genus, the geographic pattern of the head organ appears southern-centred: of the 17 species of Grania reported to possess it, as many as 13 inhabit the southern latitudes. The seventh species of the Esperance collection, G. vacivasa Coates and Stacey, 1993, is notable for the kind of items found in its gut and the unusual appearance of its pygidium.

Properties of the rotational bands in the transitional nucleus 189Pt

High-spin states in 189Pt have been studied experimentally using the 176Yb(18O,5n) reaction at beam energies of 88 and 95 MeV. The level scheme of189Pt has been revised significantly and extended to high-spin states.Rotational bands have been analyzed in the framework of triaxial particle-rotor model, and a γ ≈−30◦triaxial shape and a near-prolate shape have been proposed to the νi−113/2 and νf5/2(p3/2) bands, respectively. Two ΔI = 2 transition sequences with similar energies have been observed, and they have been proposed to be associated with the νi−213/2νf5/2(p3/2) configuration. The structure built on the νi−213/2νf5/2(p3/2) configuration could be interpreted theoretical calculations of the triaxial particle-rotor model if a near-oblate shape is assumed.

Band properties of the transitional nucleus Pt-187

High-spin states in Pt-187 have been studied experimentally using the Yb-173(O-18, 4n) reaction at beam energies of 78 and 85 MeV. The previously known bands based on the nu i(13/2),nu 7/2(-)[503], and nu i(13/2)(2)nu j configurations have been extended to high-spin states, and new rotational bands associated with the nu 3/2(-)[512] and nu 1/2(-)[521] Nilsson orbits have been identified. The total Routhian surface calculations indicate that the transitional nucleus Pt-187 is very soft with respect to beta and gamma deformations. The band properties, such as level spacings, band crossing frequencies, alignment gains, and signature splittings, have been compared with the systematics observed in neighboring nuclei and have been interpreted within the framework of the cranked shell model. The rotational bands show different band crossing frequencies, which can be explained by the alignment either of i(13/2) neutrons or of h(9/2) protons. Importantly, evidence is presented for a pi h(9/2) alignment at very low frequency in the nu 7/2(-)[503] band. The proton nature of the band crossing is strongly suggested by comparing the measured B(M1;I -> I-1)/B(E2;I -> I-2) ratios with the theoretical values from the semiclassical Donau and Frauendof approach.

Band properties of the transitional nucleus Pt-189

High-spin states in Pt-189 have been studied with the in-beam gamma-spectroscopy method via the Yb-176(O-18, 5n) reaction at beam energies of 88 MeV and 95 MeV. A new level scheme of Pt-189 has been established. Rotational bands based on the upsilon i(13/2)(-1), upsilon f(5/2)(p(3/2)) and upsilon i(13/2)(-2)upsilon f(p(3/2)) configurations, as well as several structures with irregular level spacings, have been observed. Properties of rotational bands have been analyzed in the framework of triaxial particle-rotor model. A gamma similar to -30 degrees triaxial shape and a near prolate shape have been proposed to the upsilon i(13/2)(-1) and uf(5/2)(p(3/2)) bands, respectively. Two Delta I=2 transition sequences with similar energies have been observed, and they have been proposed to be associated with the upsilon i(13/2)(-1)upsilon f(5/2)(p(3/2)) configuration. According to the relevant Nilsson orbitals, the bands built on the upsilon i(13/2)(-1)upsilon f(5/2)(p(3/2)) configuration could be interpreted as a pair of pseudo-spin partner.

Effect of main-chain rigidity on the phase transitional behavior of comblike polymers

The influence of the rigidity of polymer backbones on the side-chain crystallization and phase transition behavior was systematically investigated by a combination of differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), Fourier transform infrared spectroscopy (FTIR), and high-resolution solid-state nuclear magnetic resonance spectroscopy (NMR). DSC investigation indicated that the crystallization number of alkyl carbon atoms of the side chains grafted onto the rigid polymer backbone, poly(p-benzamide) (PBA), is much lower than that of the alkyl carbon atoms of the side chains grafted onto the flexible polymer backbone, poly(ethyleneimine) (PEI), implying that the conformational state of the polymer backbones has a strong effect on the side-chain crystallization behavior in comblike polymers. WAXD and FTIR results proved that these two comblike polymers pack into hexagonal (PBA18C) and orthorhombic (PEI18C) crystals, respectively, depending on the adjusting ability of the polymer backbones for particular conformational states. It was also found that the presence of the crystalline-amorphous interphase (delta = 31.6 ppm) in PBA18C detected by solid-state C-13 NMR spectroscopy can be attributed to the rigid PBA backbone, which restricts the mobility of the alkyl side chains.

Synthesis and thermal transitional properties of side-chain liquid crystalline polyacrylates containing para-nitroazobenzene as mesogenic groups

The synthesis and characterization of side-chain liquid crystalline (LC) polyacrylates containing para-nitroazobenzene (Pn) as mesogenic groups were described. Homopolymers with 3 and 4 carbon atoms in the spacers were non-LC polymers; for homopolymers with 6 carbon atoms in the spacer, nematic LC behavior was observed. Copolymers with acrylic acid as one component exhibited an S-Ad phase according to the WAXD results which showed the d/l of 1.4-1.54 for the copolymers with 3, 4, and 6 carbon atoms in the spacers. Considering the molecular structure as well as the WAXD results of the copolymers, the possible molecular arrangement in the smectic Sad phase was proposed, in which the smectic layers were composed of the antiparallel mesogens and the antiparallel arrangement was considered to be enhanced due to the H bond between - COOH and - NO2. The stress-induced orientational phenomena of Pn in the LC states was also discussed. (C) 1996 John Wiley & Sons, Inc.

STUDY ON THE PHENOMENA OF LASER-EXCITED POPULATION-CHANGE ON RES-ONANTLY TRANSITIONAL LOWER LEVEL AND ITS APPLICATION

Ⅰ. INTRODUCTIONLaser-excited atomic fluorescence spectrometry in hollow cathode discharge(HCD) has been widely used in the research field of laser spectroscopy in recent years. Similar to traditional method, information obtained in the researches was direct line nonresonance fluorescence arising from the resonantly transitional upper level. Attention has not been sufficiently paid to the phenomenon of population change on the resonantly transitional lower level due to laser irradiation of plasma in HCD,...

Radiolarian fauna in surface sediments of the northeastern East China Sea

Radiolarian abundance and species composition have been determined in 72 surface: sediment samples from the northeastern East China Sea. The results are compared with chemical and physical properties of the overlying water masses, and with sediment conditions. In the study area, radiolarian abundance and species number increase markedly from northwest to southeast, and their distributions can be divided into three provinces: the low-density zone corresponding to the shelf, the middle-density zone corresponding to the western slope of the Okinawa Trough and the high-density zone corresponding to the central part of the Okinawa Trough. The distribution of radiolarians correlates well with modem sea surface temperature and sea surface salinity, but shows a negative relation with nutrients and primary productivity of the overlying water. This distribution pattern is also strongly affected by the sediment type and terrigenous material input. Also, the Kuroshio Current has an important effect on controlling the distribution and species composition of radiolarian fauna in this area. Based on three Q-mode factors (accounting for 90.2% of the variance), three radiolarian assemblages have been distinguished, and their distributions are clearly correlated with oceanographic current patterns in the region. The mixed water assemblage dominated by Tetrapyle circularis, Tetrapyle quadriloba and Ommatartus tetrathalamus tetrathalamus is restricted to the area of the Mixed Water, but mainly influenced by the Shelf Water. The Kuroshio Water assemblage, which is dominated by Lithelius minor, Dictyocoryne profunda, Stylodictya multispina, Acrosphaera spinosa, Dictyocoryne truncatum, Spongaster tetrars, Stylodictya arachnia and Ommatartus tetrathalamus tetrathalamus, is basically controlled by the Kuroshio Surface Water. And the transition assemblage dominated by Tetrapyle quadriloba and Monozonium pachystylum is associated with the Tsushima Warm Current Water. The boundaries among these assemblages approximately coincide with the oceanographic front. And the changes in the distribution of these assemblages could be,regarded as-not only modifications of the water masses, but also indicators of the possible movements of the oceanic front. (C) 2003 Elsevier Science B.V. All rights reserved.