2,943 research outputs found
Mode identification for rotating rigid shaft with flexible disks by mode splits
No full textThis payer investigates the mode splits of the bending coupled modes of a rotating shaft with multiple flexible disks, in which the disks are rigidly attached to the rigid shaft supported by bearings. The bending coupled modes, in which shaft bending modes are coupled with one nodal diameter disk modes, are classified as the balanced and unbalanced modes. The mode splits of the balanced modes are the same as those of pure disk modes since the shaft does not experience any motion. On the other hand, the mode splits between pairs of the forward and backward unbalanced modes are found to be dependent upon the disk/shaft configuration and the shaft support stiffness, as well as the rotational speed and the ratio of polar to diametrical moment of inertia. (C) 1999 Academic Press
SERUM ALPHA-1-ANTITRYPSIN IN PATIENTS WITH HEPATOCELLULAR-CARCINOMA
No full textTo evaluate the diagnostic value of alpha-1-antitrypsin (alpha-AT) as a tumor marker for hepatocellular carcinoma (HCC), we studied the serum levels of alpha-AT by rocket immunoelectrophoresis and alpha-fetoprotein (alpha-FP) by radioimmunoassay in 46 proven HCC patients, 43 cirrhosis patients and 200 healthy blood donors. The mean alpha-AT level of the 46 patients with HCC (4.8 +/- 2.7 mg/ml) was significantly higher than that of 200 healthy control subjects (1.7 +/- 0.7 mg/ml) (P < 0.0001). The sensitivity of alpha-AT in 24 patients with high level of alpha-FP (> 400 ng/ml) and 22 patients with low level of alpha-FP (< 400 ng/ml) were 96% and 64%, respectively. There was no substantial correlation between alpha-FP and alpha-AT in the two groups (alpha-FP > 400 ng/ml, alpha-FP < 400 ng/ml) (r = 0.078, 0.064). The sensitivity for HCC using alpha-FP level alone (> 400 ng/ml) was only 52%, and the sensitivity using alpha-AT level alone (> 3.2 mg/ml) was 76% of the 46 patients. Combining both tests, sensitivity was improved only to 80%
Present-day constraint for tropical Pacific precipitation changes due to global warming in CMIP5 models
No full textThe sensitivity of the precipitation responses to greenhouse warming can depend on the present-day climate. In this study, a robust linkage between the present-day precipitation climatology and precipitation change owing to global warming is examined in inter-model space. A model with drier climatology in the present-day simulation tends to simulate an increase in climatological precipitation owing to global warming. Moreover, the horizontal gradient of the present-day precipitation climatology plays an important role in determining the precipitation changes. On the basis of these robust relationships, future precipitation changes are calibrated by removing the impact of the present-day precipitation bias in the climate models. To validate this result, the perfect model approach is adapted, which treats a particular model’s precipitation change as an observed change. The results suggest that the precipitation change pattern can be generally improved by applying the present statistical approach.1122Nsciescopuskc
Role of north tropical atlantic SST on the ENSO simulated using CMIP3 and CMIP5 models
No full textIn this study, role of North Tropical Atlantic (NTA) SST on the ENSO variability is examined with CMIP3 and CMIP5 simulations. It is found that most climate models involved in CMIP3 and CMIP5 successfully simulate the inverse relationship between NTA SST during the boreal spring and the ENSO during the subsequent boreal winter. The multi-model ensemble (MME) results show the observed westward propagating signals related to NTA SST from the Atlantic to the Pacific along the off-equatorial Pacific ITCZ. However, different from the observational argument, the main mechanism for the NTA to induce the ENSO is likely to be different in the MME. While the observational result exhibits the NTA-induced off-equatorial Rossby waves play a more dominant role in leading the Pacific signal, the equatorial wind over the western Pacific related to the NTA-induced Kelvin wave is likely to be more crucial to lead the Pacific variability. In addition, the amplitude of NTA SST-induced ENSO in the MME tends to be systematically weaker, and the preference for the central Pacific SST anomaly is also weak. These weak signals are distinctly improved in a model that simulates two types of El Nino events independently. That the strength of the NTA effect to the Pacific can be affected by the seasonal distribution of climatological precipitation is also discussed. Additionally, the strength of the NTA effect tends to be stronger when the model simulates phase locking of ENSO reasonably.1183sciescopu
ENSO amplitude changes due to greenhouse warming in CMIP5: Role of mean tropical precipitation in the twentieth century
No full textThis study examines the relationship between the intermodel diversities of the present climate climatology and those of El Nino-Southern Oscillation (ENSO) amplitude change under global warming in the Coupled Model Intercomparison Project Phase 5 (CMIP5) models. The models with increased ENSO amplitude under greenhouse warming (i.e., ENSO-amplified models) tend to simulate a twentieth century stronger climatological Intertropical Convergence Zone and South Pacific Convergence Zone over the central-eastern Pacific that are located farther away from the equator during boreal spring. Moisture budget analysis indicates that those climatological differences lead to stronger positive climatological precipitation change over the off-equatorial central-eastern Pacific under greenhouse warming. The stronger positive climatological precipitation change enhances the air-sea coupling strength over the central-eastern Pacific, which leads to increase the ENSO amplitude.1196sciescopu
Chosen logistics processes in Škoda JS
No full textThis master thesis deals with the purchase and sale process in Škoda JS company. The aim of this work is to assess whether the setting of the purchase and sale process is met by the company also within a real business case, in compliance with set controls, and whether the degree of perfect delivery is sufficient. In the introduction, the author specifies the basic terms: logistics, logistic chain, customer benefits, information systems in logistics, buying and selling. The following chapter introduces Škoda JS company, including the sphere of its entrepreneurial activity. This chapter also deals with the nuclear power industry. In the crucial chapter, the author describes the process of purchase and sale in Škoda JS company and compares it with a real business case. In conclusion, the author evaluates discrepancies and suggests recommendations to avoid them
Changes in Independency between Two Types of El Nino Events under a Greenhouse Warming Scenario in CMIP5 Models
No full textThis study uses archives from phase 5 of the Coupled Model Intercomparison Project (CMIP5) to investigate changes in independency between two types of El Nino events caused by greenhouse warming. In the observations, the independency between cold tongue (CT) and warm pool (WP) El Nino events is distinctively increased in recent decades. The simulated changes in independency between the two types of El Nino events according to the CMIP5 models are quite diverse, although the observed features are simulated to some extent in several climate models. It is found that the climatological change after global warming is an essential factor in determining the changes in independency between the two types of El Nino events. For example, the independency between these events is increased after global warming when the climatological precipitation is increased mainly over the equatorial central Pacific. This climatological precipitation increase extends convective response to the east, particularly for CT El Nino events, which leads to greater differences in the spatial pattern between the two types of El Nino events to increase the El Nino independency. On the contrary, in models with decreased independency between the two types of El Nino events after global warming, climatological precipitation is increased mostly over the western Pacific. This confines the atmospheric response to the western Pacific in both El Nino events; therefore, the similarity between them is increased after global warming. In addition to the changes in the climatological state after global warming, a possible connection of the changes in the El Nino independency with the historical mean state is discussed in this paper.1111sciescopu
TUNGSTEN CARBIDE MICROSPHERE AS AN ELECTRODE FOR CATHODIC HYDROGEN EVOLUTION FROM WATER
No full textTungsten carbide microsphere with hexagonal close-packed W(2)C Structure was synthesized by a polymer-induced carburization method. The synthesis process and physicochemical properties were investigated and optimized to obtain uniform spherical morphology, high surface area and high chemisorption capacity. The tungsten carbide loaded with only 7.5 wt% of platinum was tested for cathodic hydrogen evolution from water and electrocatalytic activity was compared to commercial 20 wt% Pt/vulcan XC-72R carbon (commercial E-Tek catalyst). The current density of W(2)C microsphere (without Pt) was much lower than the commercial E-Tek catalyst. But, when a small amount of platinum was loaded to the W(2)C microsphere, the current density became higher than that of the commercial E-Tek catalyst, demonstrating synergistic effect between Pt and W(2)C. The activity per mass of Pt for Pt/W(2)C was 2.3-3.2 times higher than that of E-Tek Pt/C catalyst. (C) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reservedclose424
Role of Tropical Atlantic SST Variability as a Modulator of El Nino Teleconnections
No full textThe present study suggests that the off-equatorial North Atlantic (NATL) SST warming plays a significant role in modulating El Nio teleconnection and its impact on the North Atlantic and European regions. The El Nio events accompanied by NATL SST warming exhibit south-north dipole pattern over the Western Europe to Atlantic, while the ENSO teleconnection pattern without NATL warming exhibits a Rossby wave-like pattern confined over the North Pacific and western Atlantic. Especially, the El Nio events with NATL warming show positive (negative) geopotential-height anomalies over the North Atlantic (Western Europe) which resemble the negative phase of the NAO. Consistently, it is shown using a simple statistical model that NATL SSTA in addition to the tropical Pacific SSTA leads to better prediction on regional climate variation over the North Atlantic and European regions. This role of NATL SST on ENSO teleconnection is also validated and discussed in a long term simulation of coupled global circulation model (CGCM).X1175sciescopuskc
Platinized mesoporous tungsten carbide for electrochemical methanol oxidation
No full textMesoporous WC with hexagonal crystal structure was synthesized by a surfactant-assisted polymer method. A new electrocatalyst composed of a small amount of Pt supported on the mesoporous WC exhibited higher activity for electrooxidation of methanol than microporous Pt/WC or Pt/W2C as well as commercial Pt-Ru(1:1)/C catalysts. The mesoporosity and the phase of WC appear important for the high activity. Compared to the commercial Pt-Ru/C catalyst, the Pt/WC (mesoporous) showed the higher activity per mass of Pt by a factor of six even without Ru. Since the catalyst is also stable in electrochemical environment, it could become an alternative electrocatalyst for direct methanol fuel cells. (C) 2007 Elsevier B.V. All rights reservedclose868
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