A two‐step‐ahead recurrent neural network for stream‐flow forecasting     

Li‐Chiu Chang  Fi‐John Chang  Yen‐Ming Chiang 《水文研究》2004,18(1):81-92

In many engineering problems, such as flood warning systems, accurate multistep‐ahead prediction is critically important. The main purpose of this study was to derive an algorithm for two‐step‐ahead forecasting based on a real‐time recurrent learning (RTRL) neural network that has been demonstrated as best suited for real‐time application in various problems. To evaluate the properties of the developed two‐step‐ahead RTRL algorithm, we first compared its predictive ability with least‐square estimated autoregressive moving average with exogenous inputs (ARMAX) models on several synthetic time‐series. Our results demonstrate that the developed two‐step‐ahead RTRL network has efficient ability to learn and has comparable accuracy for time‐series prediction as the refitted ARMAX models. We then investigated the two‐step‐ahead RTRL network by using the rainfall–runoff data of the Da‐Chia River in Taiwan. The results show that the developed algorithm can be successfully applied with high accuracy for two‐step‐ahead real‐time stream‐flow forecasting. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

Non-destructive elemental analysis of lunar meteorites using a negative muon beam     

I-Huan Chiu  Kentaro Terada  Takahito Osawa  Changkun Park  Soshi Takeshita  Yasuhiro Miyake  Kazuhiko Ninomiya 《Meteoritics & planetary science》2023,58(9):1333-1344

We report the result of a non-destructive elemental analysis of lunar meteorites using a negative muon beam at J-PARC. An experimental system of six Ge semiconductor detectors and a newly designed He analysis chamber (to enable quantitative analysis of Al) was used to provide a high signal-to-noise ratio for the detection of major elements from lunar rocks (Mg, Si, Fe, O, Ca, and Al). We performed a Monte Carlo simulation to determine the chemical compositions at two sides and the center of a sample (at depths of 0.33 and 0.96 mm below the sample surface, respectively) of the lunar meteorite DEW 12007. These results indicate that the three interior regions of DEW 12007 are likely to be 55.8:44.2, 51.4:48.6, and 54.4:45.6 wt% mixtures of anorthositic and basaltic clasts, respectively. This study is the first quantitative analysis of a heterogeneous meteorite interior using a negative muon beam. As elemental analysis using a muon beam is non-destructive and highly sensitive to light elements, including C, N, and O, the protocols established in this study are applicable to initial characterization of returned samples from the South Pole of the Moon.  相似文献   

Polybrominated diphenyl ethers do not affect metamorphosis but alter the proteome of the invasive slipper limpet Crepidula onyx     

Joy Mukherjee  Beverly H.K. Po  Jill M.Y. Chiu  Rudolf S.S. Wu  Pei-Yuan Qian  Vengatesen Thiyagarajan 《Marine pollution bulletin》2013

Man-made polybrominated diphenyl ethers (PBDEs) used as flame retardants in various consumer products may be harmful to marine organisms. Larvae of some marine invertebrates, especially invasive species, can develop resistance to PBDEs through altered protein expression patterns or proteome plasticity. This is the first report of a proteomics approach to study BDE-47 induced molecular changes in the invasive limpet Crepidula onyx. Larvae of C. onyx were cultured for 5 days (hatching to metamorphosis) in the presence of BDE-47 (1 μg L⁻¹). Using a 2-DE proteomics approach with triple quadrupole and high-resolution TOF-MS, we showed that BDE-47 altered the proteome structure but not the growth or metamorphosis of C. onyx larvae. We found eight significant differentially expressed proteins in response to BDE-47, deemed the protein expression signature, consisting of cytoskeletal, stress tolerance, metabolism and energy production related proteins. Our data suggest C. onyx larvae have adequate proteome plasticity to tolerate BDE-47 toxicity.  相似文献   

Quantifying rainfall controls on catchment‐scale landslide erosion in Taiwan     

Yi‐Chin Chen  Kang‐tsung Chang  Yu‐Jia Chiu  Sze‐Man Lau  Hong‐Yuan Lee 《地球表面变化过程与地形》2013,38(4):372-382

Landslide erosion is a dominant hillslope process and the main source of stream sediment in tropical, tectonically active mountain belts. In this study, we quantified landslide erosion triggered by 24 rainfall events from 2001 to 2009 in three mountainous watersheds in Taiwan and investigated relationships between landslide erosion and rainfall variables. The results show positive power‐law relations between landslide erosion and rainfall intensity and cumulative rainfall, with scaling exponents ranging from 2·94 to 5·03. Additionally, landslide erosion caused by Typhoon Morakot is of comparable magnitude to landslide erosion caused by the Chi‐Chi Earthquake (M_W = 7·6) or 22–24 years of basin‐averaged erosion. Comparison of the three watersheds indicates that deeper landslides that mobilize soil and bedrock are triggered by long‐duration rainfall, whereas shallow landslides are triggered by short‐duration rainfall. These results suggest that rainfall intensity and watershed characteristics are important controls on rainfall‐triggered landslide erosion and that severe typhoons, like high‐magnitude earthquakes, can generate high rates of landslide erosion in Taiwan. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Current monsoon conditions of river runoff and groundwater formation in west pacific regions: Kamchatka Peninsula and Taiwan Island     

R. G. Dzhamalov  N. L. Frolova  A. V. Stanovova  G. N. Krichevets  Chung-Ho Wang  Kuo-Chin Hsu  Feng-Sheng Chiu  Cheng-Haw Lee  Ming-Chee Wu 《Water Resources》2012,39(5):610-621

The dynamics of climate and runoff characteristics are studied in the territories of Kamchatka Peninsula and Taiwan Island, which are situated in the influence zone of monsoon circulation. Long-term variations in the temperature, precipitation, and runoff are examined in Kamchatka and Taiwan for the weather and gauging stations with the longest observation series to analyze new climate conditions of water resources generation.  相似文献   

Implications of coseismic groundwater level changes observed at multiple-well monitoring stations     

Yeeping Chia  Jessie J. Chiu  Yi-Hsuan Chiang  Tsai-Ping Lee  Yih-Min Wu  Ming-Jame Horng 《Geophysical Journal International》2008,172(1):293-301

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Effects of hypoxia on biofilms and subsequently larval settlement of benthic invertebrates     

S.G. Cheung  C.Y.S. Chan  B.H.K. Po  A.L. Li  J.Y.S. Leung  J.W. Qiu  P.O. Ang  V. Thiyagarajan  P.K.S. Shin  J.M.Y. Chiu 《Marine pollution bulletin》2014

Biofilms on submerged surfaces are important in determining larval settlement of most marine benthic invertebrates. We investigated if exposure of biofilms to hypoxia would alter the larval settlement pattern and result in a shift in benthic invertebrate community structure in the field. Biofilms were first exposed to hypoxia or normoxia in laboratory microcosms for 7 days, and then deployed in the field for another 7 days to allow for larval settlement and recruitment to occur. Using terminal-restriction fragment length polymorphism of the 16S rRNA gene, this study showed that hypoxia altered the biofilm bacterial community composition, and the difference between the hypoxic and normoxic treatments increased with the time of exposure period. This study also demonstrated significantly different benthic invertebrate community structures as a result of biofilm exposure to hypoxia and that the hypoxic and normoxic treatments were dominated by Hydroides sp. and Folliculina sp., respectively.  相似文献   

The 2dF-SDSS LRG and QSO Survey: the spectroscopic QSO catalogue     

Scott M. Croom  Gordon T. Richards  Tom Shanks  Brian J. Boyle  Robert G. Sharp  Joss Bland-Hawthorn  Terry Bridges  Robert J. Brunner  Russell Cannon  Daniel Carson  Kuenley Chiu  Matthew Colless  Warrick Couch  Roberto De Propris  Michael J. Drinkwater  Alastair Edge  Stephen Fine  Jon Loveday  Lance Miller  Adam D. Myers  Robert C. Nichol  Phil Outram  Kevin Pimbblet  Isaac Roseboom  Nicholas Ross  Donald P. Schneider  Allyn Smith  Chris Stoughton  Michael A. Strauss  David Wake 《Monthly notices of the Royal Astronomical Society》2009,392(1):19-44

We present the final spectroscopic QSO catalogue from the 2dF-SDSS LRG (luminous red galaxy) and QSO (2SLAQ) survey. This is a deep,  18 < g < 21.85  (extinction corrected), sample aimed at probing in detail the faint end of the broad line active galactic nuclei luminosity distribution at   z ≲ 2.6  . The candidate QSOs were selected from SDSS photometry and observed spectroscopically with the 2dF spectrograph on the Anglo-Australian Telescope. This sample covers an area of 191.9 deg² and contains new spectra of 16 326 objects, of which 8764 are QSOs and 7623 are newly discovered [the remainder were previously identified by the 2dF QSO Redshift Survey (2QZ) and SDSS]. The full QSO sample (including objects previously observed in the SDSS and 2QZ surveys) contains 12 702 QSOs. The new 2SLAQ spectroscopic data set also contains 2343 Galactic stars, including 362 white dwarfs, and 2924 narrow emission-line galaxies with a median redshift of   z = 0.22  .
We present detailed completeness estimates for the survey, based on modelling of QSO colours, including host-galaxy contributions. This calculation shows that at   g ≃ 21.85  QSO colours are significantly affected by the presence of a host galaxy up to redshift   z ∼ 1  in the SDSS ugriz bands. In particular, we see a significant reddening of the objects in   g − i   towards the fainter g -band magnitudes. This reddening is consistent with the QSO host galaxies being dominated by a stellar population of age at least 2–3 Gyr.
The full catalogue, including completeness estimates, is available on-line at http://www.2slaq.info/ .  相似文献   

Yielding and shear behaviour of cement-treated dredged materials     

C.F. Chiu  W. Zhu  C.L. Zhang 《Engineering Geology》2009,103(1-2):1-12

The mechanical behaviour of three cement-treated dredged materials (DM) was studied in the laboratory by isotropic compression and undrained triaxial tests. The intrinsic properties of the untreated and reconstituted soil were used as a reference framework to interpret the effect of cementation on the mechanical behaviour of the cement-treated DM. The isotropic compression line of the reconstituted soil is termed the intrinsic normal compression line (INCL). It is found that the isotropic compression lines of the cement-treated DM lie above the INCL, i.e. the void ratio of the cement-treated soil is higher than that of the reconstituted soil for a given confining pressure. The yield stress measured from the isotropic compression tests increases with increasing cement content and curing time. The pre-yield and post-yield shear responses of the cement-treated DM are different. Pre-yield soil specimens show a tendency to dilate, but post-yield soil specimens show a tendency to contract. Failure envelopes of the cement treated DM lie above that of the reconstituted DM. Linear Mohr–Coulomb failure envelopes were observed for the range of applied stress used in the study. The cohesion intercept increases with increasing cement content and curing time. The strength enhancement of the cement-treated DM is the result of the structures developed during cementation process. Based on a recently proposed soil water transfer model, the change in normalised bound water content, (Δm_bw)_N, is used to evaluate the combined effects of cement content and curing period on the mechanical behaviour of the cement-treated DM. It is found that there exists a threshold value of (Δm_bw)_N, beyond which the yield stress and cohesion intercept increases nonlinearly with increasing (Δm_bw)_N. The threshold value is equal to 0.37 for the three DM used in the study.  相似文献   

Mercury,organic-mercury and selenium in small cetaceans in Taiwanese waters     

Chen MH  Shih CC  Chou CL  Chou LS 《Marine pollution bulletin》2002,45(1-12):237-245

Total Hg (∑Hg), organic-Hg (O-Hg) and Se bioaccumulations in small cetaceans distributed in Taiwanese waters of the Taiwan Strait and the southwestern Pacific have been investigated for the first time. The results could represent the baseline metal concentrations of marine mammals in the southwestern Pacific, where volcanic activities are possibly the major source of mercury to the environments. Muscle samples of four species of small cetaceans were collected from animals accidentally caught by tuna-longline fisheries from 1994 through 1995. In total, 53 pantropical spotted dolphins, Stenella attenuata, nine spinner dolphins, S. longirostris, five bottlenose dolphins, Turiops truncatus and four Risso's dolphins, Grampus giseus were analyzed. In addition, two stranded pantropical spotted dolphins were investigated. Cold vapour AAS and ICP-MS were used in the analysis of Hg and Se, respectively. Significant species difference was found in the four species of small cetaceans. Among them, the pantropical spotted dolphin showed the highest mean concentration (mg/kg wet wt.) of both ∑Hg (3.64±2.19) and O-Hg (2.79±1.23), whereas the Risso's dolphin had the highest mean concentrations of Se (1.77±1.29). There was no significant sex difference with respect to metal bioaccumulation in the samples of S. attenuata. Significant correlations between body length (BL) and ∑Hg, as well as O-Hg concentrations were observed in pantropical spotted (Sa) and spinner dolphins (Sl). The linear relationships were Sa: ∑Hg=−8.290+0.066BL, r=0.421; Sl: ∑Hg=−2.735+0.025BL, r=0.875; Sa: O-Hg=−3.723+0.036BL, r=0.408; and Sl: O-Hg=−3.017+0.025BL, r=0.870. However, a demethylation phenomenon that decreasing the percentage of O-Hg coupled with increasing levels of Se was observed when the ∑Hg concentrations in the muscle tissues of dolphins reached 4 mg/kg wet wt.  相似文献