Global distribution of thermospheric heat sources: EUV absorption and joule dissipation     

B.K. Ching  Y.T. Chiu 《Planetary and Space Science》1973,21(10):1633-1646

The global distribution and temporal variations of thermospheric heating due to Joule dissipation of measured ionospheric electric fields are computed. It is shown that the volume Joule dissipation rate at high and middle latitude is similar in magnitude and altitudinal profile to the global solar EUV absorption rate discussed in the previous papers. Thus, Joule dissipation contributes significantly towards reconciling the quantitatively known sources of thermospheric heat input and that required to maintain the normal thermosphere. The combined heat source due to EUV absorption and Joule dissipation varies with the annual cycle in a manner closely resembling that of the thermospheric density.  相似文献   

Theory of solar radio pulsation     

Y. T. Chiu 《Solar physics》1970,13(2):420-443

We show that the observed modulation of some coronal microwave, X-ray and Type III emission into pulses of 10 sec intervals is a consequence of the stimulation of electron cyclotron waves propagated in the whistler mode in dipole-like bipolar regions of dimension 0.2 R . Assuming that a power law spectrum of 10 keV electrons with a slope similar to solar flare protons can be trapped in a bipolar region, we show that whistlers can be generated by pitch angle instability. The resultant 10 sec bounce motion of whistler wave trains leads to enhanced, modulated emission in microwave and X-ray frequencies by pitch angle scattering of MeV electrons, and to modulated Type III emission by scattering with coherent plasma waves. A direct prediction of the theory is the existence of sympathetic pulsations at two sources a fraction of a solar radius apart. A second test of the theory is that modulated Type III emission should show strong polarization.This work was conducted under U.S. Air Force Space and Missile Systems Organization (SAMSO) Contract No. F04701-69-C-0066.  相似文献   

Th/U/U and Pa/U ages from a single fossil coral fragment by multi-collector magnetic-sector inductively coupled plasma mass spectrometry     

Richard A. Mortlock  Richard G. Fairbanks  Tzu-chien Chiu 《Geochimica et cosmochimica acta》2005,69(3):649-657

The ²³⁰Th/²³⁴U/²³⁸U age dating of corals via alpha counting or mass spectrometry has significantly contributed to our understanding of sea level, radiocarbon calibration, rates of ocean and climate change, and timing of El Nino, among many applications. Age dating of corals by mass spectrometry is remarkably precise, but many samples exposed to freshwater yield inaccurate ages. The first indication of open-system ²³⁰Th/²³⁴U/²³⁸U ages is elevated ²³⁴U/²³⁸U_initial values, very common in samples older than 100,000 yr. For samples younger than 100,000 yr that have ²³⁴U/²³⁸U_initial values close to seawater, there is a need for age validation. Redundant ²³⁰Th/²³⁴U/²³⁸U and ²³¹Pa/²³⁵U ages in a single fossil coral fragment are possible by Multi-Collector Magnetic Sector Inductively Coupled Plasma Mass Spectrometry (MC-MS-ICPMS) and standard anion exchange column chemistry, modified to permit the separation of uranium, thorium, and protactinium isotopes from a single solution. A high-efficiency nebulizer employed for sample introduction permits the determination of both ²³⁰Th/²³⁴U/²³⁸U and ²³¹Pa/²³⁵U ages in fragments as small as 500 mg. We have obtained excellent agreement between ²³⁰Th/²³⁴U/²³⁸U and ²³¹Pa/²³⁵U ages in Barbados corals (30 ka) and suggest that the methods described in this paper can be used to test the ²³⁰Th/²³⁴U/²³⁸U age accuracy.Separate fractions of U, Th, and Pa are measured by employing a multi-dynamic procedure, whereby ²³⁸U is measured on a Faraday cup simultaneously with all minor isotopes measured with a Daly ion counting detector. The multi-dynamic procedure also permits correcting for both the Daly to Faraday gain and for mass discrimination during sample analyses. The analytical precision of ²³⁰Th/²³⁴U/²³⁸U and ²³¹Pa/²³⁵U dates is generally better than ±0.3% and ±1.5%, respectively (2 Relative Standard deviation [RSD]). Additional errors resulting from uncertainties in the decay constant for ²³¹Pa and from undetermined sources currently limit the ²³¹Pa/²³⁵U age uncertainty to about ±2.5%. U isotope data and ²³⁰Th/²³⁴U/²³⁸U ages agree with National Institute of Standards and Technology (NIST) reference materials and with measurements made by Thermal Ionization Mass Spectrometry (TIMS) in our laboratory.  相似文献   

Thermodynamic approach to the equation of state of a magnetized Fermi gas     

V. Canuto  H. Y. Chiu  L. Fassio-Canuto 《Astrophysics and Space Science》1969,3(2):258-267

In this paper we have rederived the equations of state for a magnetized Fermi gas by generalizing the physical definition of the pressure. We have also given a simplified derivation of the energy eigenvalues of a free electron in a magnetic field, based on the use of simple harmonic oscillators. Physical interpretations of our results are presented. Possible astrophysical applications are also discussed.On leave of absence from Dept. of Physics, C.I.E.A., Ap. Post. 14740, Mexico 14, D.F., Mexico.  相似文献   

A fast method of flood discharge estimation     

Yen‐Chang Chen  Chao‐Lin Chiu 《水文研究》2004,18(9):1671-1684

Discharge, especially during flood periods, is among the most important information necessary for flood control, water resources planning and management. Owing to the high flood velocities, flood discharge usually cannot be measured efficiently by conventional methods, which explains why records of flood discharge are scarce or do not exist for the watersheds in Taiwan. A fast method of flood discharge estimation is presented. The greatest advantage of the proposed method is its application to estimate flood discharge that cannot be measured by conventional methods. It has as its basis the regularity of open‐channel flows, i.e. that nature maintains a constant ratio of mean to maximum velocities at a given channel section by adjusting the velocity distribution and the channel geometry. The maximum velocity at a given section can be determined easily over a single vertical profile, which tends to remain invariant with time and discharge, and can be converted to the mean velocity of the entire cross‐section by multying by the constant ratio. Therefore the mean velocity is a common multiple of maximum velocity and the mean/maximum velocity ratio. The channel cross‐sectional area can be determined from the gauge height, the water depth at the y‐axis or the product of the channel width multiplied by the water depth at the y‐axis. Then the most commonly used method, i.e. the velocity–area method, which determines discharge as the product of the cross‐sectional area multiplied by mean velocity, is applied to estimate the flood discharge. Only a few velocity measurements on the y‐axis are necessary to estimate flood discharge. Moreover the location of the y‐axis will not vary with time and water stage. Once the relationship of mean and maximum velocities is established, the flood estimation can be determined efficiently. This method avoids exposure to hazardous environments and sharply reduces the measurement time and cost. The method can be applied in both high and low flows in rivers. Available laboratory flume and stream‐flow data are used to illustrate accuracy and reliability, and results show that this method can quickly and accurately estimate flood discharges. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

Application of polarization analysis in correcting the orientation error of a downhole seismometer     

Hung-Chie Chiu  Huey-Chu Huang  Chun-Long Leu  Shean-Der Ni 《地震工程与结构动力学》1994,23(10):1069-1078

This paper shows that the polarization analysis of later arrivals could be used to estimate the orientation error and the tilt of the downhole accelerometers in the Dahan downhole strong-motion array. This four-level array is located to the north of Hualien city in eastern Taiwan. Polarization analysis of a windowed signal which includes significant phases (e.g. primary S wave) can give a stable major polarization axis. This axis can then be used as the reference direction for correcting the orientation error and the tilt of the downhole seismometers. If the surface instrument is chosen as the reference, the angle between the major polarization axes of the surface and any downhole recordings will be the orientation error needed to be corrected for the downhole accelerograph. This angle is a combination of the tilt and the orientation errors which correspond to the dip and strike of maximum polarization, respectively. At the Dahan downhole strong-motion array, the orientation errors of the seismometers at the depth of 50, 100 and 200 m were 1°, 90° and 84°. These orientation errors were consistent with the horizontal particle-motion analysis. The errors of horizontal plane (tilt) were almost zero. After correction, the coherency of the waveforms between the surface and the downhole recordings was significantly improved.  相似文献   

Refinement of thrust faulting models for the Central New Madrid seismic zone     

Jose Pujol  Arch Johnston  Jer-Ming Chiu  Yung-Tun Yang 《Engineering Geology》1997,46(3-4):281-298

We present the results of the joint relocation of events recorded during 1989–1992 by the PANDA network in the central New Madrid seismic zone. The near-surface material in the study area is a gently-dipping layer of poorly consolidated sediments with low P-wave velocity and high V_p/V_s (estimated values: 1.8 km s⁻¹ and 3). The sediments are underlain by high-velocity Paleozoic rocks. Under the network the difference in sediment thickness is only 0.6 km, but because of the low velocities the location of the events using layered models is affected by errors. Application of the joint hypocentral determination (JHD) technique to a subset of 580 events shows that the single-event locations may be in error by as much as 1 km in depth, depending on where the events are located. Analysis of synthetic data generated for a realistic 3-D velocity model supports the JHD results. The analysis of synthetic data also suggests that a V_p/V_s≤ 2.3 is more appropriate for the post-Paleozoic Mississippi embayment sediments. Based on the JHD locations we present a new interpretation of the seismicity, with two en-echelon SW-dipping thrust faults connected by a west-dipping thrust fault. These faults appear associated with the Reelfoot scarp and its northern extension, the Kentucky bend scarp.  相似文献   

An Experimental Study on Wave-Induced Dynandc Stresses in Seabed     

S. C. Chang L. K. Chien J  G. Lin Y. F. Chiu 《中国海洋工程》2006,20(1):27-44

A series of hydraulic model tests with horizontal movable seabed under regular wave actions have been carried out to investigate the dynamic interactions between water waves and seabed soil. Seabed dynamic stresses from experiments are, tound to differ from theoretical resuhs. The response of p0 in permeable seabed has a small decay and phase shift to the nonlinear wave actions, and the dynamic stresses, σs/p0, σh/p0 and u/p0, contain different phase shift characteristics. Such phenomena will strongly affect the dynamic stress path in seabed. If the phase shifts of σs. and σh are neglected, the stress path will become a straight line; otherwise, it will become an elliptical curve. In phase shift cases, the long axis of the p - q diagram will be shortened when the depth increases, and the short axis will become longer when the phase shift increases. For the p＇ - q＇ diagram, the larger the phase lag of u, the longer the short axis. Relative results offer useful information for the analysis of seabed stability.  相似文献   

The liberalization of shipping in Taiwan     

Rong-Her Chiu 《Marine Policy》2007

Maritime transport has become well developed in Taiwan, which is located in the western Pacific Rim. Following the model of traditional maritime nations, Taiwan's government enacted some shipping-friendly measures to help the industry in its early expansion stage. Nevertheless, government authorities have taken actions to liberalize the operations of the maritime-transport sector over the past 10 years. This paper focuses on how the liberalization measures were proposed and implemented including the process and reasons behind the formulation of governmental policies, the interaction between domestic shipping operators and the government. In addition, this paper presents a comprehensive review of the liberalization policy's impact on domestic maritime transport operators.  相似文献   

Groundwater Level Changes in Taiwan Caused by The Wenchuan Earthquake on 12 May 2008     

Tsai-Ping Lee  Yeeping Chia  Hsin-Ying Yang  Ching-Yi Liu  Yung-Chia Chiu 《Pure and Applied Geophysics》2012,169(11):1947-1962

Widespread persistent coseismic groundwater level changes induced by the M _w 7.9 Wenchuan earthquake were recorded in 80 wells in Taiwan, located approximately 2,000?km from the epicenter. The timing and magnitude of these changes, ranging from ?40 to +23?cm, have been examined by statistical evaluation. The coseismic fall dominated in the plain area, but in the mountainous area most changes are coseismic rises. Both the coseismic rise and the coseismic fall were observed in wells of different depths at two monitoring stations. The processes of the coseismic changes can be shown by the high-frequency well water level data. Analysis of the 1?Hz water level data and the broadband seismogram revealed that a temporary water level change, ranging from 0.2 to 2.3?cm, occurred at the arrival of high-energy Love waves and Rayleigh waves. However, a water level change of 0.3–6.4?cm occurred in 7–20?min after the passing of high-energy surface waves. It is doubtful that such a change could be induced directly by ground shaking. The cross-formational flow due to fracturing or unclogging of sediment pores was possibly too slow to cause the coseismic change. Further studies are required to understand the mechanism of coseismic groundwater level changes induced by a distant earthquake.  相似文献