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41.
Artificial added mass instabilities in sequential staggered coupling of nonlinear structures and incompressible viscous flows 总被引:1,自引:0,他引:1
Christiane Förster Wolfgang A. Wall 《Computer Methods in Applied Mechanics and Engineering》2007,196(7):1278-1293
Within this paper the so-called artificial added mass effect is investigated which is responsible for devastating instabilities within sequentially staggered Fluid-structure Interaction (FSI) simulations where incompressible fluids are considered.A discrete representation of the added mass operator MA is given and ‘instability conditions’ are evaluated for different temporal discretisation schemes. It is proven that for every sequentially staggered scheme and given spatial discretisation of a problem, a mass ratio between fluid and structural mass density can be found at which the coupled system becomes unstable. The analysis is quite general and does not depend upon the particular spatial discretisation schemes used. However here special attention is given to stabilised finite elements employed on the fluid partition. Numerical investigations further highlight the results. 相似文献
42.
在应用γ能谱资料寻找砂岩型铀矿的过程中,要尽可能地消除非矿化因素引起的干扰,提取与铀矿化有关的信息。介绍了钍归-化的原理及特点,采用与矿化有关的元素迁移信息的钍归-化方法,分析了二连盆地东部的γ能谱资料,揭示了该区放射性元素的分布特征、地球化学作用和后期铀元素的迁移与富集。结合其他地质资料,分析了钾剩差的变异区(正、负高值区)及铀剩差正高值区形成的原因,同时指出了经过钍归-化处理所得到的铀剩差正高值区应为氧化与还原作用过渡带的直接指示,也是该区进一步寻找砂岩型铀矿的重要标志。 相似文献
43.
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45.
Conceptual fusion reactor studies over the past 10–15 yr have projected systems that may be too large, complex, and costly to be of commercial interest. One main direction for improved fusion reactors points toward smaller, higher-power-density approaches. First-order economic issues (i.e., unit direct cost and cost of electricity) are used to support the need for more compact fusion reactors. The results of a number of recent conceptual designs of reversed-field pinch, spheromak, and tokamak fusion reactors are summarized as examples of more compact approaches. While a focus has been placed on increasing the fusion-power-core mass power density beyond the minimum economic threshold of 100–200 kWe/tonne, other means by which the overall attractiveness of fusion as a long-term energy source are also addressed.Nomenclature
a
Plasma minor radius at outboard equatorial plane (m)
-
A
Plasma aspect ratioR
T
/a
-
AC
Annual charges ($/yr)
-
b
Plasma minor radius in vertical direction (m)
-
B
Magentic field at plasma or blanket (T)
-
B
c
Magnetic field at the coil (T)
-
B
Toroidal magnetic field (T)
-
B
Poloidal magnetic field (T)
- BOP
Balance of plant
-
C
Coil
-
COE
Cost of electricity (mills/kWeh)
- CRFPR
Compact RFP reactor
- CT
Compact torus (FRC or spheromak)
-
c
FPC
Unit cost of fusion power core ($/kg)
-
DC
Direct cost ($)
- DZP
Dense Z-pinch
-
E
Escalation rate (1/yr)
-
EDC
Escalation during construction ($)
- ET
Elongated tokamak
-
F
Annual fuel charges ($/yr)
-
FC
Component of UDC not strongly dependent or FPC size ($/kWe)
- FW
First wall
-
FPC
Fusion power core
-
f
Aux
Fraction of gross electric power recirculated to BOP
-
f
1
(IC+IDC+EDC)/DC
-
f
2
(O&M + SCR + F)/AC
-
IC
Indirect cost ($)
-
IDC
Interest during construction ($)
-
I
w
Neutron first-wall loading (MW/m2)
-
i
Toroidal plasma current (MA)
-
j
Plasma current density, I/a2
-
k
B
Boltzmann constant, 1.602(10)–16 (J/keV)
- LWR
Light-water (fission) reactor
-
MPD
Mass power density 1000PE/MFPC (kWe/tonne)
-
M
N
Blanket energy multiplication of 14.1-MeV neutron energy
-
M
FPC
Mass of fusion power core (tonne)
-
n
Plasma density (m–3) or toroidal MHD mode number
-
O&M
Annual operating and maintenance cost ($/yr)
-
p
f
Plant availability factor
- PFD
Poloidal field dominated (CTs, RFP, DZP)
-
P
Construction time (yr)
- PTH
Thermal power (MWt)
-
P
E
Net electric power (1-)P
ET
(MWe)
- PET
Total gross electric power (MWe)
- pf
Fusion power (MW)
-
q
Tokamak safety factor (B
/B
gq
)(a/R
T
)
-
q
e
EngineeringQ value, 1/e
-
R
T
Major toroidal radius (m)
- RFP
Reversed-field pinch
- RPE
Reactor plant equipment (Account 22)
- S
Shield
-
SCR
Annual spare component cost ($/yr)
- SSR
Second stability region for the tokamak
- S/T/H
Stellarator/torsatron/heliotron
- ST
Spherical tokamak or spherical torus
-
T
Plasma temperature (keV)
-
TDC
Total direct cost ($)
-
TOC
Total overnight cost ($)
-
UDC
Unit direct cost,TDC/10
3
P
E
($/kWe)
-
V
p
Plasma volume (m3)
-
W
p
Plasma energy (GJ)
-
W
B
Magnetic field energy (GJ)
-
Magnetic utilization efficiency, 2nkBT/(B
2/20)
-
0
Permeability of free space, 4(10)–7 H/m
-
XE
Plasma confinement efficiency, a2/4E
-
e
Plasma energy confinement time
-
p
Overall plant efficiency, TH(1-)
-
TH
Thermal conversion efficiency
-
FPC
AverageFPC mass density (tonne/m3)
-
Plasma vertical elongation factor,b/a
-
Thickness of allFPC engineering structure surround plasma (m)
-
Total recirculating power fraction, (P
ET-P
E)/P
ET, or inverse aspect ratioa/R
T
This work was performed under the auspices of USDOE, Office of Fusion Energy. 相似文献
46.
准确、快速地测定含铁尘泥中有害元素,对含铁尘泥节能降废项目研究及综合利用有着重要的指导意义。实验针对含铁尘泥试样因含碳量高,导致常规酸溶解方法如果不增加除碳步骤则很难完全分解试样的问题,采用高温熔融法将试样制成熔融液后倾倒于稀酸中溶解的方法,解决了碳含量高难溶解的问题。采用四硼酸锂-碳酸锂混合熔剂在高温下将试样熔融,熔融液高温倾倒于稀酸中制成澄清溶液,由于骤冷,试样炸裂成微小玻璃珠,无迸溅,操作简单,使得后续溶解过程快速完成,从而建立了电感耦合等离子体原子发射光谱(ICP-AES)测定P、Pb、K、Na、Zn共5种有害元素的方法。按照实验方法测定含铁尘泥中P、Pb、K、Na、Zn,测定值的相对标准偏差(RSD,n=9)在1.4%~5.7%之间,加标回收率在96%~110%之间。研究结果表明方法能够满足含铁尘泥样品中5种元素的定量分析要求。 相似文献
47.
Zinc Coated Steel/Epoxy Adhesive Systems: Investigation of the Interfacial Zone by FTIR Spectroscopy
The present study takes advantage of the ability of Fourier Transform Infrared Spectroscopy (FTIR) for the analysis of ultrathin organic films on metals. FTIR in the reflection mode (IRRAS) is used in order to study the interaction of ultrathin films of dicyandiamide (hardener of most one-pack epoxy resins) with various substrates, model ones such as gold or zinc and industrial ones such as steel and zinc-coated steels.
Pure zinc surfaces and, to a lesser extent, zinc-coated steels are shown to react with dicyandiamide after heating at 180°C, as evidenced by the frequency shift of the absorption band (at about 2200 cm-1) characteristic for nitrile groups. As real systems consist of thick layers of a fully formulated adhesive cured onto a metallic substrate, the direct investigation of such a buried interphase is no longer possible by FTIR and by most of the known spectroscopies. Some mechanically tested specimens are then analysed, after failure, by FTIR microspectrometry. The spectra obtained, corresponding to the fracture initiation zone which is about 100 μm in diameter, advocate for the presence of an ultrathin layer of modified polymer still covering the substrate. 相似文献
Pure zinc surfaces and, to a lesser extent, zinc-coated steels are shown to react with dicyandiamide after heating at 180°C, as evidenced by the frequency shift of the absorption band (at about 2200 cm-1) characteristic for nitrile groups. As real systems consist of thick layers of a fully formulated adhesive cured onto a metallic substrate, the direct investigation of such a buried interphase is no longer possible by FTIR and by most of the known spectroscopies. Some mechanically tested specimens are then analysed, after failure, by FTIR microspectrometry. The spectra obtained, corresponding to the fracture initiation zone which is about 100 μm in diameter, advocate for the presence of an ultrathin layer of modified polymer still covering the substrate. 相似文献
48.
Analysis of the carbon disulphide extracts of nine samples of UK coal-maceral concentrates by 1H highresolution n.m.r. spectroscopy, gas-liquid chromatography and field-desorption mass spectrometry indicates the presence of components with a wide molecular weight range extending up to 1200 amu; these are attributed to n-alkanes up to ≈C50 and highly condensed polynuclear aromatic compounds. 相似文献
49.
Zhen Zhou 《Ergonomics》2014,57(5):693-713
The dependence of biodynamic responses of the seated human body on the frequency, magnitude and waveform of vertical vibration has been studied in 20 males and 20 females. With sinusoidal vibration (13 frequencies from 1 to 16 Hz) at five magnitudes (0.1–1.6 ms? 2 r.m.s.) and with random vibration (1–16 Hz) at the same magnitudes, the apparent mass of the body was similar with random and sinusoidal vibration of the same overall magnitude. With increasing magnitude of vibration, the stiffness and damping of a model fitted to the apparent mass reduced and the resonance frequency decreased (from 6.5 to 4.5 Hz). Male and female subjects had similar apparent mass (after adjusting for subject weight) and a similar principal resonance frequency with both random and sinusoidal vibration. The change in biodynamic response with increasing vibration magnitude depends on the frequency of the vibration excitation, but is similar with sinusoidal and random excitation. 相似文献
50.
Ralph W. Howard C. A. McDaniel Dennis R. Nelson Gary J. Blomquist Leslie T. Gelbaum Leon H. Zalkow 《Journal of chemical ecology》1982,8(9):1227-1239
The cuticular hydrocarbon components of four castes ofReticulitermes virginicus (Banks) have been identified and quantitated. Components identified includen-alkanes; 2-, 3-, 11-, 13-, and 15-methyl-alkanes; 11,15-dimethylalkanes, (Z)-9-alkenes; (Z,Z)-7,9-dienes; and (E/Z)-6,9-dienes ranging in carbon number from C21 to C40. All caste forms ofR.virginicus contained the same components, but showed caste-specific proportions. Comparison of these hydrocarbons with those of the sympatric termiteR. flavipes (Kollar) suggest that cuticular hydrocarbons might serve as species- and caste-recognition cues. A bioassay was developed to test this species-recognition hypothesis, with the experimental results supporting the hypothesis.Isoptera: Rhinotermitidae. 相似文献