This study presents a methodology for the development of a water balance model that uses publicly available data in a manner useful to water scientists and managers who manage complex lake and reservoir watersheds. The approach was applied to Coeur d'Alene Lake, a naturally occurring lake that is controlled by a dam located on its outlet (Spokane River) in North Idaho, USA. As in many other areas, the region surrounding Coeur d'Alene Lake has experienced high rates of population growth in recent years, and there is concern that, as consumptive water use increases, the lake will eventually not be able to be managed to simultaneously maintain the federally mandated minimum flow requirements in the Spokane River and also maintain the target summertime elevation of 2128 feet (648.6 m) for recreation and hydropower purposes. The complexity caused by the competing uses at Coeur d'Alene Lake makes it an excellent case study for similarly characterized watersheds. Both a natural flow model and regulated elevation model were developed, and sensitivity analysis was conducted on both models to evaluate which lake processes have the greatest effects on lake elevation, thereby requiring the most attention. A ‘low‐flow’ scenario was modelled to demonstrate the usefulness of the model and to inform Coeur d'Alene Lake regional stakeholders regarding the interrelationship between current water policy and the lake's physical behaviour under stressed conditions that could result from climate change. Model result indicates that, while lake elevation may be maintained at the summertime elevation of 2128 feet (648.6 m) under a low‐flow scenario, the outflows in the Spokane River start to approach the minimum flow requirements in the month of August. The developed approach is useful where publicly available data exist and allows for economic, yet rigorous, water resources systems evaluation without requiring significant field data collection. 相似文献
Precursor-derived Si-C-N ceramics after creep testing in air were characterized using X-ray diffractometry (XRD) and transmission electron microscopy (TEM). XRD analysis showed that the crept Si-C-N ceramics were covered by an α-cristobalite layer. TEM observations revealed that the precipitated nanocrystallites in the crept Si-C-N ceramics were β-SiC. Between α-cristobalite and crept Si-C-N ceramic, there was an intermediate zone in which Si2N2O nanocrystallites were distributed homogeneously. Moreover, Si2N2O nanocrystallites were often found covering the surface of nanosized gas channels in the crept Si-C-N ceramics, where no α-cristobalite phase was detected. Based on these observations, a two-step oxidation mechanism of Si-C-N ceramics during creep testing in air was proposed. 相似文献
The activities of Na2O and K2O dissolved in mixed-alkali Na–K–(β+β")-Al2O3 (NKBA) have been determined by using yttria stabilized zirconia (YSZ) as a solid electrolyte in the following galvanic cells: The approach enables to verify in situ the establishment and maintenance of the β/β"-equilibrium, and to characterize it as a function of the phase composition of NKBA. The results can be expressed as follows: 相似文献
Poly-p-phenylene (PPP) was synthesized from benzene according to the Kovacic method. Electrodes were made from this electronic insulator by cold- or hot-pressing of the loose, brown powder, under the addition of 7.5 wt. % soot (Corax L®, Degussa AG). The electrochemical insertion and removal of anions HSO−4, ClO−4 in this material in aqueous solutions of the corresponding acids was investigated by slow cyclic voltammetry.
Initially, only a surface layer of about 0.1 mm thickness takes part in the electrochemical processes, which are reversible. A maximum concentration of anions in the solid of [(−C6H4−)+7 A−] is attainable. The maximum degree of insertion is equal to 0.14. The insertion potential UI shifts strongly into the negative direction with increasing concentration c of the acid. A linear UI/c relationship is observed as in the case of graphite, where the intercalation potential is more positive by 20–200 mV for the same electrolyte. The round trip current efficiency for the insertion/removal cycle increases with increasing acid concentration attaining 100% in 14 M H2SO4 or 11.3 M CHlO4. For a given concentration, increases in the same order as with graphite (H2SO4 < HClO4 < HBF4), being somewhat lower for a given electrolyte composition. From anodic current limitation (jlim = 5–10 mA cm−2), a diffusion coefficient of about D = 2 × 10−7 cm2 s−1 is derived for the transport of anions in the bulk of PPP. The striking similarity of our results to former findings with graphite is thoroughly discussed. Some general conclusions are derived thereof. 相似文献
Electrochemical dressing of fine-grained metal-bonded diamond grinding wheels enables to grind hard and brittle materials
in the ductile mode. Optical surfaces can be manufactured by grinding, which reduces the need for subsequent, time-consuming
polishing work. When using metal-bonded grinding wheels, the emerging oxides regulate the electrochemical dissolution. Bronze-bonded
grinding wheels are more suitable for grinding cemented carbides and ceramics than iron-bonded grinding wheels, as it is easier
to modify their chemical composition to suit a specific grinding task. They can also be sintered at lower temperatures, which
reduces the risk of thermal damage to the diamond. In this paper, the dissolution and the oxidation of different bronze alloys
are characterized for the electrochemical dressing process. The relevant evaluation criteria are the oxide layer thickness,
the electrical behavior and the different emerging bronze alloy oxides.
This work is funded by the German Research Association DFG within the Transregional Collaborative Research Center SFB/TR4
“Process Chains for the Replication of Complex Optical Elements”. 相似文献
Abstract Beginning as an innovative idea in the early 1970s, the third-party maintenance industry realized revenues in 1986 of $1.4 billion. This flourishing industry offers opportunities for vendors and customers alike. 相似文献
Medical data mining is currently actively pursued in computer science and statistical research but not in medical practice.
The reasons therefore lie in the difficulties of handling and statistically analyzing medical data. We have developed a system
that allows practitioners in the field to interactively analyze their data without assistance of statisticians or data mining
experts. In the course of this paper we will introduce data mining of medical data and show how this can be achieved for survival
data. We will demonstrate how to solve common problems of interactive survival analysis by presenting the Online Clinical
Data Mining (OCDM) system. Thereby the main focus is on similarity based queries, a new method to select similar cases based
on their covariables and the influence of these on their survival. 相似文献
BACKGROUND: Calculations on the basis of the LQ-model have been focussed on the possible radiobiological equivalence between common continuous low dose rate irradiation (CLDR) and a superfractionated irradiation (PDR = pulsed dose rate) provided that the same total dose will be prescribed in the same overall time as with the low doserate. A clinically usable fractionation scheme for brachytherapy was recommended by Brenner and Hall and should replace the classical CLDR brachytherapy with line sources with an afterloading technique using a stepping source. The hypothes is that LDR equivalency can be achieved by superfractionation was tested by means of in vitro experiments on V79 cells in monolayer and spheroid cultures as well as on HeLa monolayers. MATERIALS AND METHODS: Simulating the clinical situation in PDR brachytherapy, fractionation experiments were carried out in the dose rate gradient of afterloading sources. Different dose levels were produced with the same number of fractions in the same overall incubation time. The fractionation schedules which were to be compared with a CLDR reference curve were: 40 x 0.47 Gy, 20 x 0.94 Gy, 10 x 1.88 Gy, 5 x 3.76 Gy, 2 x 9.4 Gy given in a period of 20 h and 1 x 18.8 Gy as a "single dose" exposition. As measured by flow cytometry, the influence of the dose rate in the pulse on cell survival and on cell cycle distribution under superfractionation was examined on V79 cells. RESULTS: V79 spheroids as a model for a slowly growing tumor, reacted according to the radiobiological calculations, as a CLDR equivalency was achieved with increasing fractionation. Rapidly growing V79 monolayer cells showed an inverse fractionation effect. A superfractionated irradiation with pulses of 0.94 Gy/h respectively 0.47 Gy/0.5 h was significantly more effective than the CLDR irradiation. This inverse fractionation effect in log-phase V79 cells could be attributed to the accumulation of cycling cells in the radiosensitive G2/M phase (G2 block) during protected exposure which was drastically more pronounced for the pulsed scheme. HeLa cells were rather insensitive to changes of fractionation. Superfractionation as well as hypofractionation yielded CLDR equivalent survival curves. CONCLUSIONS: The fractionation scheme, derived from the PDR theory to achieve CLDR equivalent effects, is valid for many cell lines, however not for all. Proliferation and dose rate dependend cell cycle effects modify predictions derived from the sublethal damage recovery model and can influence acute irradiation effects significantly. Dose rate sensitivity and rapid proliferation favour cell cycle effects and substantiate, applied to the clinical situation, the possibility of a higher effectiveness of the pulsed irradiation on rapidly growing tumors. 相似文献