Maritime safety for fishing boat operations and avoidable hijacking in Taiwan     

Yi-Che Shih  Chiu L. Chou  Wen-Yan Chiau   《Marine Policy》2010,34(2):349-351

Taiwanese fishing boats have been hijacked many times this year. Trouble at sea can usually be attributed to communication problems, inappropriate management and an unfair salary system. The majority of boats hijacked are high sea (long-line) fishing boats. Although fishery authorities ask the fishing boats to set up vessel monitoring systems (VMSs), this precaution has not been sufficient. There is a further need for improved management by the fishing boat owner and for an improved employment policy for seamen. The issue of maritime security is not new, but it remains a major concern and continues to be a threat to Taiwan and other countries. To date, there have been many cases of hijacking in the South China Sea. This paper analyzes the reasons for the hijackings and provides potential strategies to prevent future incidents.  相似文献   

Stone cover and slope factors influencing hillside surface runoff and infiltration: laboratory investigation     

Jiin‐Shuh Jean  Koe‐Fe Ai  Kaimin Shih  Chao‐Chi Hung 《水文研究》2000,14(10):1829-1849

In this study, laboratory rainfall simulation in an extensive area was used to study the infiltration, and interception and storage from surface runoff in points with different stone cover percentages (0, 10, 20 and 30%) and slopes (5°, 10° and 20°). The experimental results of this study showed that the interrelationships among the slope, stone cover percentage, groundwater level, surface runoff amount, and interception and storage of the ponds were varied and irregular. No systematic patterns were detected for the change in the groundwater level, surface runoff amount, and interception and storage of the ponds with different stone cover percentages at different slopes and no threshold values were apparent. For a 5° slope, if the stone cover percentage was increased, the amount of surface runoff was reduced, the infiltration and the groundwater level experienced no significant change, and the interception and storage of the ponds increased. For a 10° slope, if the stone cover percentage was increased, the amount of surface runoff increased, the infiltration decreased, the groundwater level experienced no significant change or decreased slightly at certain points, and the interception and storage of the ponds increased. For a 20° slope, if the stone cover percentage was increased, the amount of runoff increased, the infiltration decreased, the groundwater level experienced no significant change or decreased slightly at certain points, and the interception and storage of the ponds increased. With or without stone cover, when the hydraulic conductivity of the top material is close to that of fine sand or laterite, an increase in the slope gradient decreased the amount of surface runoff and increased the storage amount of the ponds. As for the stone distribution, an interlaced style showed better performance in the interception and storage of ponds than that of a regular style. There was no significant change in the groundwater level. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

A Space‐Time Raster GIS Data Model for Spatiotemporal Analysis of Vegetation Responses to a Freeze Event          下载免费PDF全文

Ziliang Zhao  Shih‐Lung Shaw  Dali Wang 《Transactions in GIS》2015,19(1):151-168

Many past space‐time GIS data models viewed the world mainly from a spatial perspective. They attached a time stamp to each state of an entity or the entire area of study. This approach is less efficient for certain spatio‐temporal analyses that focus on how locations change over time, which require researchers to view each location from a temporal perspective. In this article, we present a data model to organize multi‐temporal remote sensing datasets and track their changes at the individual pixel level. This data model can also integrate raster datasets from heterogeneous sources under a unified framework. The proposed data model consists of several object classes under a hierarchical structure. Each object class is associated with specific properties and behaviors to facilitate efficient spatio‐temporal analyses. We apply this data model to a case study of analyzing the impact of the 2007 freeze in Knoxville, Tennessee. The characteristics of different vegetation clusters before, during, and after the 2007 freeze event are compared. Our findings indicate that the majority of the study area is impacted by this freeze event, and different vegetation types show different response patterns to this freeze.  相似文献   

Sm–Nd and Rb–Sr studies of lherzolitic shergottite Yamato 984028     

C.-Y. Shih  L.E. Nyquist  Y. Reese  K. Misawa 《Polar Science》2011,4(4):515-529

The distribution pattern of the trace elements Rb, Sr, Nd and Sm for Yamato 984028 (Y984028) is consistent with its classification as a lherzolitic shergottite. The Sm–Nd mineral isochron of this lherzolitic shergottite defines its age to be 170 ± 10 Ma for an initial ?_Nd = +11.6 ± 0.2. The corresponding Rb–Sr mineral isochron yields an identical age of 170 ± 9 Ma and an initial ⁸⁷Sr/⁸⁶Sr = 0.710389 ± 0.000029. The concordant Sm–Nd and Rb–Sr isochron ages suggest that Y984028 crystallized 170 ± 7 Ma ago contemporaneously with five other lherzolitic shergottites and ten enriched basaltic and olivine-phyric shergottites. The age, Sr- and Nd- isotopic signatures further suggest that Y984028 and Y-793605, and also probably Y000097 could come from a single magmatic body. Using a two-stage evolution model, the time-averaged ⁸⁷Rb/⁸⁶Sr-ratio for the mantle source of the parent magma of Y984028 is ～0.182, within the range of 0.178–0.182 that has been reported for other lherzolitic shergottites. The corresponding time-averaged ¹⁴⁷Sm/¹⁴⁴Nd-ratio for the source mantle of its parent magma is super-chondritic at ～0.217, implying its source was a depleted mafic part of the Martian mantle similar to that of diabasic shergottite Northwest Africa (NWA) 1460. Rb, Sr, Sm and Nd distributions in Y984028 are likely produced by pyroxene and olivine accumulation, probably from a NWA 1460-like parental melt, in an intrusive magma body.  相似文献   

Very High-Resolution Solar X-Ray Imaging Using Diffractive Optics     

B. R. Dennis  G. K. Skinner  M. J. Li  A. Y. Shih 《Solar physics》2012,279(2):573-588

This paper describes the development of X-ray diffractive optics for imaging solar flares with better than 0.1 arcsec angular resolution. X-ray images with this resolution of the ???10?MK plasma in solar active regions and solar flares would allow the cross-sectional area of magnetic loops to be resolved and the coronal flare energy release region itself to be probed. The objective of this work is to obtain X-ray images in the iron-line complex at 6.7?keV observed during solar flares with an angular resolution as fine as 0.1 arcsec ?C over an order of magnitude finer than is now possible. This line emission is from highly ionized iron atoms, primarily Fe xxv, in the hottest flare plasma at temperatures in excess of ???10 MK. It provides information on the flare morphology, the iron abundance, and the distribution of the hot plasma. Studying how this plasma is heated to such high temperatures in such short times during solar flares is of critical importance in understanding these powerful transient events, one of the major objectives of solar physics. We describe the design, fabrication, and testing of phase zone plate X-ray lenses with focal lengths of ???100 m at these energies that would be capable of achieving these objectives. We show how such lenses could be included on a two-spacecraft formation-flying mission with the lenses on the spacecraft closest to the Sun and an X-ray imaging array on the second spacecraft in the focal plane ???100 m away. High-resolution X-ray images could be obtained when the two spacecraft are aligned with the region of interest on the Sun. Requirements and constraints for the control of the two spacecraft are discussed together with the overall feasibility of such a formation-flying mission.  相似文献   

Development of regional design hyetographs     

Gwo‐Fong Lin  Lu‐Hsien Chen  Shih‐Chieh Kao 《水文研究》2005,19(4):937-946

A method is proposed to establish regional design hyetographs for facilitating the determination of design hyetographs at ungauged sites. The method is applied to the central area of Taiwan. First, the single‐station design hyetographs at all rain gauges are analysed using principal components analysis and cluster analysis. The principal components analysis shows that there are six dominant factors, and the cluster analysis indicates that the time to peak rainfall has the largest influence on the classification of hyetographs. It also shows that the single‐station hyetographs in the study area can be classified into three clusters. Finally, the homogeneous regions for these three clusters are delineated and the corresponding regional design hyetographs are proposed. Once the homogeneous regions and the regional hyetographs are available, the design hyetograph at the point of interest can be easily determined. The proposed method is expected to be useful for providing the design hyetographs at ungauged sites. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

Using a characteristic-based particle tracking method to solve one-dimensional fully dynamic wave flow     

Dong-Sin Shih  Gour-Tsyh Yeh 《Computational Geosciences》2018,22(2):439-449

The theoretical behavior of a one-dimensional (1-D) open-channel flow is embedded in the Saint-Venant equation, which is derived from the Navier–Stokes equations. The flow motion is described by the momentum equations, in which the terms for the inertia, pressure, gravity, and friction loss are retained while all other terms are discarded. Although the problem is valid for most channel-flow scenarios, it is numerically challenging to solve because robust, accurate, and efficient algorithms are critical for models to field applications. The method of characteristics (MOC) is applied to solve the diagonalized Saint-Venant equations. Most importantly, the boundary conditions can be naturally implemented based on the wave directions. This is considered more closely related to realistic flow conditions and sufficiently flexible to handle mixed sub- and supercritical fluid flows in natural rivers. A computer model, WASH1DF, derived from the proposed numerical method, and which differs from other commercial software packages such as HEC-RAS and SOBEK, was developed. To test the accuracy of the proposed method, four benchmark problems were examined. Analytical solutions to these benchmark problems, covering a wide range of cases, were provided by MacDonald et al. (J. Hydrol. Eng. ASCE 123(11), 1041–1045, 1997). The simulations indicate that the proposed method provides accurate results for all benchmark cases, which are valid for all transient flow scenarios. Comparisons of WASH1DF with other commercially available software packages were also conducted under the same simulation conditions. The results indicate that our proposed model demonstrates high accuracy for all problems and achieves the highest simulation precision among all packages tested.  相似文献   

Editorial: GIScience for human dynamics research in a changing world   总被引：1，自引：0，他引：1       下载免费PDF全文

Shih‐Lung Shaw  Daniel Sui 《Transactions in GIS》2018,22(4):891-899

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Soil–gas monitoring: A tool for fault delineation studies along Hsinhua Fault (Tainan), Southern Taiwan     

Vivek Walia  Shih Jung Lin  Ching Chou Fu  Tsanyao Frank Yang  Wei-Li Hong  Kuo-Liang Wen  Cheng-Hong Chen 《Applied Geochemistry》2010

Many studies have shown the soil gas method to be one of the most reliable investigation tools in the research of earthquake precursory signals and fault delineation. The present research is aimed finding the relationship between soil gas distribution and tectonic systems in the vicinity of the Hsinhua Fault zone in the Tainan area of Southern Taiwan. More than 110 samples were collected along 13 traverses to find the spatial distribution of Rn, He, CO₂ and N₂. The spatial congruence of all the gases shows that N₂ is the most probable carrier gas of He, whereas CO₂ seems to be a good carrier gas of Rn in this area. From the spatial distribution of Rn, He, CO₂ and N₂ the trace of Hsinhua Fault and neotectonic features can be identified. The spatial distribution of studied gases shows a clear anomalous trend ENE–SWS along the Hsinhua Fault.  相似文献   

Airborne Gravity Surveys Over Taiwan Island and Strait,Kuroshio Current and South China Sea: Comparison of GPS and Gravity Accuracies at Different Flight Altitudes     

Cheinway Hwang  Hsuan-Chang Shih  Yu-Shen Hsiao  Chi-Hsun Huang 《Marine Geodesy》2013,36(3):287-305

We compare the accuracies of GPS and gravity observations obtained from three airborne gravity surveys over Taiwan Island at altitude 5000 m and over Kuroshio Current, Taiwan Strait, and Dongsha Atoll at altitude 1500 m. A kinematic network adjustment was used to determine the positions of the aircrafts. GPS positioning errors are at the decimeter-level, which are not entirely propagated to velocity and acceleration errors due to cancellation of long wavelength errors. Outliers are downweighted in the Gaussian filtering to improve the gravity accuracy, especially at altitude 1500 m. Compared with the upward-continued gravity, the gravity anomalies from the 1500-m surveys show a consistent accuracy of about 3 mgal; the accuracy from the 5000-m survey is degraded, especially over high mountains. The RMS crossover differences at 1500 m and 5000 m are all below 3 mgal, suggesting flight altitudes do not affect the crossover difference. Coherence analysis suggests that the spatial resolvable wavelengths of the airborne gravity range from 4 km (altitude 1500 m) to 6 km (altitude 5000 m).  相似文献