solving global unconstrained optimization problems by symmetry-breaking

IEEE Computer Society; International Association for; Computer and Information Science, ACIS

a computational proof of complexity of some restricted counting problems

South Central University

New Efficiency Records for Stable Dye-Sensitized Solar Cells with Low-Volatility and Ionic Liquid Electrolytes

We report a high molar extinction coefficient heteroleptic polypyridyl ruthenium sensitizer, featuring an electron-rich 3,4-ethylenedioxythiophene unit in its ancillary ligand. A nanocrystalline titania film stained with this sensitizer shows an improved optical absorption, which is highly desirable for practical dye-sensitized solar cells with a thin photoactive layer, facilitating the efficient charge collection.

Recent 2000-year geological records of mud in the inner shelf of the East China Sea and their climatic implications

AXIS(14)C dating and grain-size analysis for Core DD2, located at the north of the Yangtze River-derived mud off the Zhejiang-Fujian coasts in the inner shelf of the East China Sea, provide us a high-resolution grain-size distribution curve varying with depth and time. Data in the upper mud layer of Core DD2 indicate that there are at least 9 abrupt grain-size increasing in recent 2000 years, with each corresponding very well with the low-temperature events in Chinese history, which might result from the periodical strengthening of the East Asian Winter Monsoon (EAWM), including the first-revealed maximum temperature lowering event at around 990 a BP. At the same time, the finer grain size section in Core DD2 agrees well with the Sui-Tang Warming Period (600-1000 a AD) defined previously by Zhu Kezhen, during which the climate had a warm, cold and warm fluctuation, with a dominated cooling period of 750-850 a AD. The Little Ice Age (LIA) can also be identified in the core. It starts around 1450 a AD and was followed by a subsequent cooling events at 1510, 1670 and 1840 a AD. Timing of these cold events revealed here still needs to be further verified owing to some current uncertainty of dating we used in this study.

Paleoceanographic records in the sedimentary cores from the middle Okinawa Trough

Two gravity piston cores (Cores 155 and 18) involved in this study were collected from the middle Okinawa Trough. Stratigraphy of the two cores was divided and classified based on the features of planktonic foraminifera oxygen isotope changes together with depositional sequence, millennium-scale climatic event comparison, carbonate cycles and AMS(14)C dating. Some paleoclimatic information contained in sediments of these cores was extracted to discuss the paleoclimatic change rules and the short-time scale events presented in interglacial period. Analysis on the variation of oxygen isotope values in stage two shows that the middle part of the Okinawa Trough may have been affected by fresh water from the Yellow River and the Yangtze River during the Last Glacial Maximum (LGM). The oxygen isotope value oscillating ranges of the cores have verified that the marginal sea has an amplifying effect on climate changes. The delta(13)C of benthic foraminifera Uvigerina was lighter in the glacial period than that in the interglacial period, which indicates that the Paleo-Kuroshio's main stream moved eastward and its influence area decreased. According to the temperature difference during the "YD" period existing in Core 180 and other data, we can reach the conclusion that the climatic changes in the middle Okinawa Trough area were controlled by global climatic changes, but some regional factors had also considerable influence on the climate changes. Some results in this paper support Fairbanks's point that the "YD" event was a brief stagnation of sea level rising during the global warming up procession. Moreover, the falling of sea level in the glacial period weakened the exchange between the bottom water of the Okinawa Trough and the deep water of the northwestern Pacific Ocean and resulted in low oxygen state of bottom water in this area. These procedures are the reasons for carbonate cycle in the Okinawa Trough area being consistent with the "Atlantic type" carbonate cycle.

Geological records of marine environmental changes in the southern Okinawa Trough

Indexes of sediment grain size, sedimentation rates, geochemical composition, heavy minerals, benthic foraminiferal fauna, indicator species of the Kuroshio Current, paleo-SST and carbonate dissolution of core E017 conformably suggest a great marine environmental change occurring at about 10.1-9.2 cal. kaBP in the southern Okinawa Trough, which may correspond to the strengthening of the Kuroshio Warm Current and re-entering the Okinawa Trough through the sea area off northeast Taiwan. The invasion of Kuroshio current has experienced a process of gradual strengthening and then weakening, and its intensity became more fluctuation during the last 5000 years. Compared to the transition of sediment grain size, geochemical composition and heavy minerals, the foraminiferal faunas show a 900-year lag, which may indicate that the invasion of Kuroshio Current and the consequent sea surface and deep-water environmental changes is a gradual process, and fauna has an obvious lag compared to environment altering. The carbonate dissolution of the Okinawa Trough has had an apparent strengthening since 9.2 cal. kaBP, and reached a maximum in the late 3000 years, which may be caused by the deep-water environmental changes due to the invasion of Kuroshio Current.

A broad deglacial delta C-13 minimum event in planktonic foraminiferal records in the Okinawa Trough

The equatorial Pacific upwelling zone has been suspected of playing an important role in the global atmospheric CO2 changes associated with glacial-interglacial cycles. In order to assess the influencing scope of the surface water deglacial delta(13)C minimum in the tropical low-latitude Pacific, the core DGKS9603, collected from the middle Okinawa Trough, was examined for 4513 C records of planktonic foraminifera N. dutertrei and G. ruber. The planktonic foraminiferal delta(13)C records show a clear decreasing event from 20 to 6 cal. kaBP., which is characterized by long duration of about 14 ka and amplitude shift of 0.4 x 10(-3). Its minimum value occurred at 15.7 cal kaBP. The event shows fairly synchrony with the surface water deglacial delta(13)C minimum identified in the tropical Pacific and its marginal seas. Because there is no evidence in planktonic foraminiferal fauna and 45180 records for upwelling and river runoff enhancement, the broad deglacial delta(13)C minimum event in planktonic foraminiferal records revealed in core DGKS9603 might have been the direct influencing result of the deglacial surface water of the tropical Pacific. The identification for the event in the Okinawa Trough provides new evidence that the water evolution in the tropical low-latitude Pacific plays a key role in large regional, even global carbon cycle.

PALEOMONSOONS OF CHINA OVER THE LAST 130,000 YEARS - PALEOMONSOON RECORDS

The characteristics of the modern monsoon climate of China may be used as clues for recognizing the records of paleomonsoon climate. The present paper deals primarily with the various paleomonsoon records of the last 130,000 years in the southeast monsoon area. These records mainly come from the following three fields: (i) the historical, (ii) the geological, including loess-paleosol sequence, deserts, lakes, snowlines, timberlines, the phenomena of continental desertization and so on, and (iii) the biological, presented by vegetation a.d mammals. Among these records, the loess-paleosol sequence in the Loess Plateau reflects a climatic history characterized by alternation of two different climatic periods when the Asian winter monsoon and summer monsoon showed pronounced effects on environment, respectively.

Development of the East Asian monsoon: Mineralogical and sedimentologic records in the northern South China Sea since 20 Ma

We here reconstruct the past change of the East Asian monsoon since 20 Ma using samples from Ocean Drilling Program (ODP) Site 1146 in the northern South China Sea based On a multi-proxy approach including a monomineralic quartz isolation procedure, identification of clay minerals by X-ray Diffraction (XRD) and grain-size analysis of isolated terrigenous materials. Terrigenous supply to ODP Site 1146 was dominated by changes in the strength of multiple sources and transport processes. Grain-size data modeled by an end-member modeling algorithm indicate that eolian dust from the and Asian inland and fluvial input have contributed on average 20% and 80% of total terrigenous material to ODP Site 1146, respectively. Specifically, about 40-53% of the total (quartz+feldspar) and only 6-11% of the total clay is related to eolian supply at the study site. Detailed analysis of the sedimentary environment, and clay minerals combined with previous studies shows that smectite originates mainly from Luzon, kaolinite from the Pearl River and illite and chlorite from the Pearl River, Taiwan and/or the Yangtze River. The proportion and mass accumulation rate (MAR) of the coarsest end-member EM1 (interpreted as eolian dust), ratios of (illite+chlorite)/smectite, (quartz+feldspar)% and mean grain-size of terrigenous materials at ODP Site 1146 were adopted as proxies for East Asian monsoon evolution. The consistent variation of these independent proxies since 20 Ma shows three profound shifts in the intensity of East Asian winter monsoon relative to summer monsoon, as well as aridity of the Asian continent, occurred at similar to 15 Ma, similar to 8 Ma and the youngest at about 3 Ma. In comparison, the summer monsoon intensified contemporaneously with the winter monsoon at 3 Ma. The phased uplift of the Himalaya-Tibetan plateau may have played a significant role in strengthening the Asian monsoon at similar to 15 Ma, 8 Ma and 3 Ma. (C) 2007 Elsevier B.V. All rights reserved.

Grain-size records at ODP site 1146 from the northern South China sea: Implications on the east Asian monsoon evolution since 20 Ma

273 samples from Ocean Drilling Program (ODP) Site 1146 in the northern South China Sea (SCS) were analyzed for grain-size distributions using grain-size class vs. standard deviation method and end-member modeling algorithm (EMMA) in order to investigate the evolution of the East Asian mon-soon since about 20 Ma. 10-19 mu m/1.3-2.4 mu m, the ratio of two grain-size populations with the highest variability through time was used to indicate East Asian winter monsoon intensity relative to summer monsoon. The mass accumulation rate of the coarsest end member EM1 (eolian), resulting from EMMA, can be used as a proxy of winter monsoon strength and Asian inland aridity, and the ratio of EM1/(EM2+EM3) as a proxy of winter monsoon intensity relative to summer monsoon. The combined proxies show that a profound enhancement of East Asian winter monsoon strength and winter monsoon intensity relative to summer monsoon occurred at about 8 Ma, and it is possible that the summer monsoon simultaneously intensified with winter monsoon at 3 Ma. Our results are well consistent with the previous studies in loess, eolian deposion in the Pacifc, radiolarians and planktonic foraminifera in the SCS. The phased uplift of the Himalaya-Tibetan Plateau may have played a significant role in strengthening the Asian monsoon at 8 Ma and 3 Ma.