scholarly journals High-temperature short-term and long hardness of sintered compact and porous titanium-siliceous carbide ti3sic2

2004 ◽  
Vol 36 (1) ◽  
pp. 11-20 ◽  
Author(s):  
S.A. Firstov ◽  
E.P. Pechkovsky
Keyword(s):  
High Temperature ◽  
Ternary Compound ◽  
Solid Phase ◽  
Porous Titanium ◽  
Critical Values ◽  
Holding Time ◽  
Short Term ◽  
Sintered Compact ◽  
Temperature Range

The ternary compound of titanium-siliceous carbide Ti3SiC2, one of the representatives of Nan laminates, prepared by solid-phase sintering is investigated in compact and porous (q=0.03-0.41) states. Features of its short-term and long-term hardness (?=10 N) behavior in the temperature range from 20 to 1200?? at a holding time of 1-60 min were studied. It is shown that a temperature of about 700?? and holding time under load of about 10 min are critical values of the indentation procedure that correspond to an intensive decrease of hardness. The presence of porosity results in a decrease in hardness. a deformation scheme of compact and porous titanium-siliceous carbide Ti3SiC2 in the temperature range from 20 to 1200?? is proposed. .

Intraoperative motor and somatosensory evoked potential monitoring during surgical clipping of ruptured and unruptured intracranial aneurysms: a comparative study

2021 ◽  
pp. 1-8
Author(s):  
Hao You ◽  
Xing Fan ◽  
Jiajia Liu ◽  
Dongze Guo ◽  
Zhibao Li ◽  
...  
Keyword(s):  
Evoked Potential ◽  
Motor Evoked Potential ◽  
Critical Values ◽  
Somatosensory Evoked Potential ◽  
Short Term ◽  
Surgical Clipping ◽  
Unruptured Aneurysms ◽  
Ruptured Aneurysms ◽  
Unruptured Intracranial Aneurysms

OBJECTIVE The current study investigated the correlation between intraoperative motor evoked potential (MEP) and somatosensory evoked potential (SSEP) monitoring and both short-term and long-term motor outcomes in aneurysm patients treated with surgical clipping. Moreover, the authors provide a relatively optimal neurophysiological predictor of postoperative motor deficits (PMDs) in patients with ruptured and unruptured aneurysms. METHODS A total of 1017 patients (216 with ruptured aneurysms and 801 with unruptured aneurysms) were included. Patient demographic characteristics, clinical features, intraoperative monitoring data, and follow-up data were retrospectively reviewed. The efficacy of using changes in MEP/SSEP to predict PMDs was assessed using binary logistic regression analysis. Subsequently, receiver operating characteristic curve analysis was performed to determine the optimal critical value for duration of MEP/SSEP deterioration. RESULTS Both intraoperative MEP and SSEP monitoring were significantly effective for predicting short-term (p < 0.001 for both) and long-term (p < 0.001 for both) PMDs in aneurysm patients. The critical values for predicting short-term PMDs were amplitude decrease rates of 57.30% for MEP (p < 0.001 and area under the curve [AUC] 0.732) and 64.10% for SSEP (p < 0.001 and AUC 0.653). In patients with an unruptured aneurysm, the optimal critical values for predicting short-term PMDs were durations of deterioration of 17 minutes for MEP (p < 0.001 and AUC 0.768) and 21 minutes for SSEP (p < 0.001 and AUC 0.843). In patients with a ruptured aneurysm, the optimal critical values for predicting short-term PMDs were durations of deterioration of 12.5 minutes for MEP (p = 0.028 and AUC 0.706) and 11 minutes for SSEP (p = 0.043 and AUC 0.813). CONCLUSIONS The authors found that both intraoperative MEP and SSEP monitoring are useful for predicting short-term and long-term PMDs in patients with unruptured and ruptured aneurysms. The optimal intraoperative neuromonitoring method for predicting PMDs varies depending on whether the aneurysm has ruptured or not.

Influence of temperature on the activity of anammox granular biomass

2016 ◽  
Vol 73 (10) ◽  
pp. 2518-2525 ◽  
Author(s):  
D. Sobotka ◽  
K. Czerwionka ◽  
J. Makinia
Keyword(s):  
Removal Rate ◽  
Batch Reactor ◽  
Effect Of Temperature ◽  
Short Term ◽  
Temperature Range ◽  
Batch Tests ◽  
Different Temperatures ◽  
Effects Of Temperature ◽  
Granular Biomass

The aim of this study was to determine a short-term and long-term effect of temperature on the anammox rate and determination of temperature coefficients in the Arrhenius and Ratkowsky equations. The short-term effects of temperature on the anammox granular biomass were investigated in batch tests at ten different temperatures in the range of 10–55 °C. The maximum overall nitrogen removal rate of 1.3 gN gVSS−1·d−1 was observed at 40 °C (VSS: volatile suspended solids). The minimum rate, close to 0 gN gVSS−1·d−1, was observed for the limits of the analyzed temperature range (10 and 55 °C). The activity tests carried out at 55 °C showed an irreversible loss of the activity due to the observed biomass lysis. Subsequently to the batch tests, a sequencing batch reactor (SBR) was operated at different temperatures (from 30 to 11 °C) to determine the long-term effects of temperature. The system was successfully operated at 15 °C, but when temperature was decreased to 11 °C, nitrite started to accumulate and the system lost its stability. The temperature coefficient (θ) was 1.07 for the batch tests carried out in the temperature range of 10–40 °C. In contrast, during the long-term SBR operation, substantially different θ had to be estimated for two temperature ranges, 1.07 (T = 15–30 °C) and 1.65 (T = 11–15 °C).

Performance Related Parameters of Flexible Connections Used in Offshore Pipelines

2002 ◽  
Author(s):  
Alok Kumar ◽  
Michael E. Hogan
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Mechanical Response ◽  
Structural Performance ◽  
Gas Mixture ◽  
Short Term ◽  
Offshore Pipelines ◽  
High Pressure High Temperature ◽  
Flexible Connections

Despite continued advances in rubber technology, the design of elastomeric flexible connections, used in offshore pipelines transporting high-pressure/high-temperature hydrocarbon fluid/gas mixture, remains more of an art than a science, primarily due to the intricate behavior of rubber. The mechanical response of rubber is dependent on time, temperature and mode of loading. It is susceptible to explosive decompression damage. Rubber’s non-linear stress-strain curves, creep, hysteresis and other properties are influenced not only by the method of fabrication but also by age. If these characteristics are not accounted for properly, the result can be less precision in design compared with metals. At present, there are no codes or standards that directly address the design, analysis or evaluation of the elastomeric flexible connections used in offshore oilfield applications. Based on the results of the recent research, the significance of key parameters that affect the short term and long term structural performance of elastomeric flexible connections is presented in this paper.

Solubility Modelling of Cements: Implications for Radioactive Waste Immobilisation.

1986 ◽  
Vol 84 ◽  
Author(s):  
F.P. Glasser ◽  
D.E. Macphee ◽  
E.E. Lachowski
Keyword(s):  
Calcium Silicate Hydrate ◽  
Composition Range ◽  
Solid Phase ◽  
Chemical Properties ◽  
Free Energies ◽  
Short Term ◽  
Solubility Products ◽  
Compositional Properties ◽  
Cementitious Systems

AbstractThe suitability of cement matrices for the long-term immobilisation of radionuclides cannot be predicted from short-term experimental data alone, because the chemical properties of cementitious systems change continuously over the repository lifetime. To model such changes is complex, so a stepwise approach has been adopted. A chemically simplified model for the solubility and compositional properties of calcium silicate hydrate gels in the system CaO-SiO2 -H20 was previously developed but has now been extended and improved and is applicable to gels in the wider composition range 0.8 < Ca/Si < 1.7. The effects of silicate speciation in aqueous solution on the formation of the solid phase have been more fully considered and the dissolution equilibrium has been revised. Solubility products and free energies of C-S-H formation have been evaluated and predictive applications of the model are discussed.

High-Temperature Properties of SiC-Si3N4 Particle Composites

1999 ◽  
Vol 122 (1) ◽  
pp. 8-12 ◽  
Author(s):  
G. Woetting ◽  
B. Caspers ◽  
E. Gugel ◽  
R. Westerheide
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Hot Pressing ◽  
Oxidation Behavior ◽  
Short Term ◽  
High Temperature Properties ◽  
Sintering Additive ◽  
Hot Pressing Sintering

Due to promising results in literature, SiC-Si3N4 particle composites in the range 0–100 percent SiC were evaluated. Focusing on high-temperature properties, mainly Y2O3 was used as sintering additive. Consolidation occurred primarily by hot-pressing, sintering tests were performed for comparison. Besides short-term properties like strength, toughness etc., long-term properties like creep and oxidation behavior were determined. Results as a function of SiC-content and microstructure were discussed with respect to materials’ performance at high temperatures and possibilities of their production on a technical scale. [S0742-4795(00)00201-5]

scholarly journals Fiber Bragg Grating Wavelength Drift in Long-Term High Temperature Annealing

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1454
Author(s):  
Dan Grobnic ◽  
Cyril Hnatovsky ◽  
Sergey Dedyulin ◽  
Robert B. Walker ◽  
Huimin Ding ◽  
...  
Keyword(s):  
High Temperature ◽  
Fiber Bragg Gratings ◽  
Sensor Arrays ◽  
Physical Processes ◽  
Short Term ◽  
Bragg Wavelength ◽  
Distributed Sensor ◽  
Ambient Temperatures ◽  
High Temperature Processes

High-temperature-resistant fiber Bragg gratings (FBGs) are the main competitors to thermocouples as sensors in applications for high temperature environments defined as being in the 600–1200 °C temperature range. Due to their small size, capacity to be multiplexed into high density distributed sensor arrays and survivability in extreme ambient temperatures, they could provide the essential sensing support that is needed in high temperature processes. While capable of providing reliable sensing information in the short term, their long-term functionality is affected by the drift of the characteristic Bragg wavelength or resonance that is used to derive the temperature. A number of physical processes have been proposed as the cause of the high temperature wavelength drift but there is yet no credible description of this process. In this paper we review the literature related to the long-term wavelength drift of FBGs at high temperature and provide our recent results of more than 4000 h of high temperature testing in the 900–1000 °C range. We identify the major components of the high temperature wavelength drift and we propose mechanisms that could be causing them.

Pharmaceuticals and health care products in wastewater effluents: the example of carbamazepine

2003 ◽  
Vol 3 (4) ◽  
pp. 131-137 ◽  
Author(s):  
K. Stamatelatou ◽  
C. Frouda ◽  
M.S. Fountoulakis ◽  
P. Drillia ◽  
M. Kornaros ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Consumption Rate ◽  
Solid Phase ◽  
Organic Content ◽  
Operating Conditions ◽  
Anaerobic Sludge ◽  
Aquatic Environments ◽  
Short Term ◽  
Xenobiotic Compound

Persistence and impact of pharmaceutics in the environment are discussed. The case of carbamazepine (CBZ), a widely used antiepileptic drug detected in rivers, lakes, sludges and even in ground water is examined. CBZ fate was investigated in all possible routes that may follow after it has been discharged to the sewage system: activated sludge, anaerobic digestion sludge, seawater, fresh water and soil. Carbamazepine slowed down, i.e. caused a decrease in the COD consumption rate in the activated sludge process, especially after longer term exposure, while the anaerobic sludge process was unaffected in the operating conditions that were applied. The compound was not degraded under either short term or long term exposure to either aerobic or anaerobic degradation processes. Carbamazepine seemed to biosorb to solid phases (soil, sludge) and this strength of sorption was related to the organic content of the solid phase. These results explain why CBZ is a very persistent xenobiotic compound, as is apparent from its detection in appreciable amounts in various aquatic environments.

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