-
[show abstract]
[hide abstract]
ABSTRACT: Growth of Ru-RuO
x
composite nanodots (RONs) on atomic-layer-deposited Al2O3 films has been investigated using magnetic sputtering of a Ru target followed by postdeposition annealing. RONs with a density
as high as ~2×1012cm−2 were obtained together with good uniformity. Subsequently, metal–oxide–semiconductor capacitors with RONs embedded in Al2O3 films have been electrically characterized for different configurations of tunneling layers (T)/blocking layers (B), and the underlying mechanisms of charge storage are discussed. For a 6-nm T/22-nm B device, a memory window of 3.7V is achieved for a ±7V programing/erasing voltage for 0.1ms, and superior charge retention
of more than 80% is achieved after 10years.
KeywordsNonvolatile memory capacitors-Ru-RuO
x
composite nanodots (RONs)-atomic-layer-deposited Al2O3
Journal of Electronic Materials 05/2012; 39(8):1343-1350. · 1.47 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: In this paper, the optimal policy is considered when the buyer faces two supply sources: one is the contract supplier from
which the buyer orders over a specific contract period (say, a year) at a pre-agreed price, and the other is the spot market.
However, when ordering from the contract supplier, the buyer must fulfill a pre-determined total order quantity, or the so-called
definite total order quantity commitment, over the whole contract period. In other words, the commitment secures the buyer
a fixed price but obliges him/her a total order quantity over the contract period. Although the spot market gives the buyer
more flexibility in terms of order quantities, its prices are volatile. Such a combination of contract and spot procurements
is often observed in practice. Within the contract period, there are multiple sub-periods, during each of which the buyer
reviews the inventory, issues an individual order, and uses the on-hand inventory to meet the random demand. Thus, in each
(ordering) period, the buyer will weigh between the current known spot price (by procuring from the spot market) and a lower
future price (by waiting while consuming the remaining commitment). An optimal dual ordering policy is characterized for each
period, depending on the on-hand inventory level, the spot price, and the remaining commitment quantity. The optimal policy
in each period is also shown to be independent of the contract price. Through a numerical study, the inventory cost is demonstrated
to be (1) insensitive to the contract price when the total commitment quantity is lower than the total expected demand over
the contract period and (2) non-increasing in the variability of spot prices.
KeywordsTotal ordering quantity commitment (TOQC)–spot market–procurement policy
Journal of Systems Science and Systems Engineering 04/2012; 20(1):25-42. · 0.43 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Supergene Mn-oxide deposits are widely distributed in Guangxi, Guangdong, Yunnan, and Hunan Provinces, South China, accounting
for 18% of the total Mn reserves in the country. Direct dating of supergene Mn enrichment, however, is lacking. In this paper,
we present high-resolution 40Ar/39Ar ages of Mn oxides from the Xinrong Mn deposit, western Guangdong, to place numerical constraints on the timing and duration
of supergene Mn enrichment. A total of ten cryptomelane samples, spanning a vertical extent of 67m, were dated using the
40Ar/39Ar laser incremental heating technique, with seven samples yielding well-defined plateau or pseudo-plateau ages ranging from
23.48 ± 0.91 to 2.06 ± 0.05Ma (2σ). One sample yields a staircase spectrum that does not reach a plateau; the spectrum, however, indicates the presence of
two or more generations of Mn oxides in the sample, whose ages are best estimated at 22.34 ± 0.31 and 10.2 ± 0.86Ma, respectively.
The remaining two samples gave meaningless or uninterpretable results due to significant 39Ar recoil and contamination by old phases. The 40Ar/39Ar data thus reveal a protracted history of weathering and supergene Mn enrichment that started at least in the end of the
Oligocene or beginning of Miocene and extending into the latest Pliocene. Staircase-apparent age spectra, resulting from banded
or botryoidal samples, yield an average growth rate of Mn oxides at 0.6–0.7 × 10−3mm kyr−1. The values indicate that a 1-mm grain of Mn oxides may host minerals precipitated during a time span of ca. 1.5m.y., and
accumulation of Mn oxides to form economic deposits under weathering environments may take millions of years. The distribution
of weathering ages shows that the oldest Mn oxides occur on the top of the profile, whereas the youngest minerals are found
at the bottom, suggesting downward propagation of weathering fronts. However, two samples located at the intermediate depths
of the profile yield ages comparable with those occurring at the highest elevations. Such a complexity of age distribution
is interpreted in terms of preferential penetration of Mn-rich weathering solutions along more permeable fault zones, or as
a result of multi stages of dissolution and re-precipitation of Mn oxides. A synthesis of geochronological and geological
data suggests that formation of the Xinrong deposit was a consequence of a combination of favorable lithological, climatic,
and structural conditions. Because the climatic and structural conditions are similar among the provinces of South China during
the Cenozoic, the geochronological results obtained at Xinrong may also have implications for the timing of supergene Mn enrichment
throughout South China.
Mineralium Deposita 04/2012; 42(4):361-383. · 1.68 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Business innovation and collaboration lead to the development of enterprise information systems from the internal scope towards
the more broadly external parties. EERP (End-to-End Resources Planning) as the up to date requirement in the enterprise information
field is presented in this paper. The relevant technologies about internet of service to realize EERP have been researched
in detail. An approach based on value-aware service engineering and service network technologies for EERP has been proposed
and applied, which can help to realize business-goal-driven dynamic semantic integration of the Web services.
KeywordsInternet of Service–SOA (Service Oriented Architecture)–EERP (End-to-End Resources Planning)–Service Network
09/2011: pages 19-26;
-
[show abstract]
[hide abstract]
ABSTRACT: We consider an inventory system with two heterogeneous suppliers differentiated by their fixed and variable costs as well as constraints on order sizes. Procuring from one of the supplier involves a high variable cost but negligible fixed cost while procuring from the other supplier involves a low variable cost but high fixed cost, as well as a constraint on the maximum order size. We show that the problem can be reduced to an equivalent problem with a single supplier. However, the corresponding cost is neither concave nor convex. Using the notion of quasi-convexity, we characterize the structure of the optimal policy and show that it can be specified in terms of multiple thresholds which determine when to order from each supplier and how much. In contrast to previous research, which does not consider order size constraints, we show that sourcing from a specific supplier can occur over multiple ranges of inventory levels and simultaneously with sourcing from other suppliers. We show how the results can be extended to systems with more than two suppliers and to order size constraints on all suppliers. We offer managerial insights into the benefit of dual-sourcing and how this benefit is affected by various supplier characteristics. In particular, we show that multi-sourcing is most valuable in the presence of order size constraints.
05/2009;
-
[show abstract]
[hide abstract]
ABSTRACT: Deep weathering profiles and associated supergene Mn-oxides deposits are widely distributed in South China. However, data on their ages are not available until most recently. 40Ar/39Ar laser incremental heating analysis of potassium-bearing supergene Mn-oxides collected from four weathering profiles in the Qinzhou–Fangcheng Mn belt, Guangxi Province, South China, provides, for the first time, numerical constraints on timing of weathering and supergene Mn enrichment. Thirty-eight of 42 cryptomelane grains yield well-defined plateau (36 grains) or pseudo plateau (2 grains) ages ranging from 17.6 ± 0.5 Ma to 4.71 ± 0.08 Ma (2σ). The results, when combined with data from Mn-oxides deposits from the adjacent Guangdong and Hunan Provinces, document a protracted history of weathering and supergene Mn enrichment, spanning from the earliest Miocene to the latest Pliocene in South China. This indicates that warm and humid climatic conditions conducive to intense weathering and secondary mineralization prevailed across South China during the whole Neogene. The climatic conditions inferred from weathering geochronology are consistent with sedimentary records and fossil floral and fauna associations from Cenozoic inland and marginal sea basins of South China. The weathering geochronology data also provide temporal constraints on the initiation and intensification of the East Asian monsoon that has been the cause for the South China's humid climate.
Earth and Planetary Science Letters.
-
[show abstract]
[hide abstract]
ABSTRACT: Supergene Mn-oxide deposits are widely distributed in Guangxi, Guangdong, Yunnan, and Hunan Provinces, South China, accounting for 18% of the total Mn reserves in the country. Direct dating of supergene Mn enrichment, however, is lacking. In this paper, we present high-resolution Ar-40/Ar-39 ages of Mn oxides from the Xinrong Mn deposit, western Guangdong, to place numerical constraints on the timing and duration of supergene Mn enrichment. A total of ten cryptomelane samples, spanning a vertical extent of 67 m, were dated using the Ar-40/Ar-39 laser incremental heating technique, with seven samples yielding well-defined plateau or pseudo-plateau ages ranging from 23.48 +/- 0.91 to 2.06 +/- 0.05 Ma (2 sigma). One sample yields a staircase spectrum that does not reach a plateau; the spectrum, however, indicates the presence of two or more generations of Mn oxides in the sample, whose ages are best estimated at 22.34 +/- 0.31 and 10.2 +/- 0.86 Ma, respectively. The remaining two samples gave meaningless or uninterpretable results due to significant Ar-39 recoil and contamination by old phases. The Ar-40/Ar-19 data thus reveal a protracted history of weathering and supergene Mn enrichment that started at least in the end of the Oligocene or beginning of Miocene and extending into the latest Pliocene. Staircase-apparent age spectra, resulting from banded or botryoidal samples, yield an average growth rate of Mn oxides at 0.6-0.7x10(-3) mm kyr(-1). The values indicate that a 1-mm grain of Mn oxides may host minerals precipitated during a time span of ca. 1.5 m.y., and accumulation of Mn oxides to form economic deposits under weathering environments may take millions of years. The distribution of weathering ages shows that the oldest Mn oxides occur on the top of the profile, whereas the youngest minerals are found at the bottom, suggesting downward propagation of weathering fronts. However, two samples located at the intermediate depths of the profile yield ages comparable with those occurring at the highest elevations. Such a complexity of age distribution is interpreted in terms of preferential penetration of Mn-rich weathering solutions along more permeable fault zones, or as a result of multi stages of dissolution and re-precipitation of Mn oxides. A synthesis of geochronological and geological data suggests that formation of the Xinrong deposit was a consequence of a combination of favorable lithological, climatic, and structural conditions. Because the climatic and structural conditions are similar among the provinces of South China during the Cenozoic, the geochronological results obtained at Xinrong may also have implications for the timing of supergene Mn enrichment throughout South China.
