On the Effect of Temperature on Tightening Characteristics of Gaskets

2002 ◽  
Author(s):  
Jaroslav Bartonicek ◽  
Manfred Schaaf ◽  
Friedrich Schoeckle
Keyword(s):  
Room Temperature ◽  
Sheet Material ◽  
Leak Rate ◽  
Effect Of Temperature ◽  
Short Term ◽  
Hydraulic Test ◽  
Aging Period ◽  
Heating Device ◽  
Temperature Exposure

To study the effect of temperature on the tightening characteristics of gaskets, leak rate tests were performed using a servo-hydraulic test equipment (short term temperature exposure). According to the tests the tightening behaviour of gaskets made of fibre based sheet material improved with temperature due to additional deformation of the gaskets during the test. In tests with camprofile gaskets with graphite layers there was no significant additional deformation of the gasket thus the leak rates showed no difference between room temperature and elevated temperature. Regarding long term exposure to temperature it is expected that with a lot of gasket materials the leak rates increase after a certain aging period. It is too expensive to study these effects with complex servo-hydraulic test rigs. Therefore a more simple test rig was developed that can be loaded in hydraulic test rigs (to determine leak rate vs. gasket stress curves) and that can be exposed to temperature in an oven or by a special heating device.

scholarly journals The Effects of Various Conditions of Short-Term Rejuvenation Heat Treatment on Room-Temperature Mechanical Properties of Thermally Aged P92 Boiler Steel

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6076
Author(s):  
Ladislav Falat ◽  
Lucia Čiripová ◽  
Viera Homolová ◽  
Miroslav Džupon ◽  
Róbert Džunda ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Impact Toughness ◽  
Room Temperature ◽  
Laves Phase ◽  
Short Term ◽  
Boiler Steel ◽  
P92 Steel ◽  
The Impact

In this work, the effects of various conditions of short-term rejuvenation heat treatment on room-temperature mechanical properties of long-term aged P92 boiler steel were investigated. Normalized and tempered P92 steel pipe was thermally exposed at 600 °C for time durations up to 5000 h in order to simulate high-temperature material degradation, as also occurring in service conditions. Thus, thermally embrittled material states of P92 steel were prepared, showing tempered martensitic microstructures with coarsened secondary phase precipitates of Cr23C6-based carbides and Fe2W-based Laves phase. Compared with the initial normalized and tempered material condition, thermally aged materials exhibited a slight decrease in strength properties (i.e., yield stress and ultimate tensile strength) and deformation properties (i.e., total elongation and reduction of area). The hardness values were almost unaffected, whereas the impact toughness values showed a steep decrease after long-term ageing. An idea for designing the rejuvenation heat treatments for restoration of impact toughness was based on tuning the material properties by short-term annealing effects at various selected temperatures somewhat above the long-term ageing temperature of P92 material. Specifically, the proposed heat treatments were performed within the temperature range between 680 °C and 740 °C, employing variable heating up and cooling down conditions. It was revealed that short-term annealing at 740 °C for 1 h with subsequent rapid cooling into water represents the most efficient rejuvenation heat treatment procedure of thermally aged P92 steel for full restoration of impact toughness up to original values of normalized and tempered material state. Microstructural observations clearly indicated partial dissolution of the Laves phase precipitates to be the crucial phenomenon that played a key role in restoring the impact toughness.

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).

Short-term and long-term frequency characteristics of 2 μm single frequency Tm:YAG laser at room temperature

Laser Physics ◽  
2011 ◽  
Vol 21 (2) ◽  
pp. 356-361 ◽  
Author(s):  
C. T. Wu ◽  
Y. L. Ju ◽  
B. Q. Yao ◽  
L. Ke ◽  
Y. Z. Wang
Keyword(s):  
Room Temperature ◽  
Frequency Characteristics ◽  
Single Frequency ◽  
Short Term ◽  
Term Frequency ◽  
Tm:Yag Laser

scholarly journals Impact of temperature on short- and long-term aging of asphalt binders

2016 ◽  
Vol 1 ◽  
pp. 6 ◽  
Author(s):  
Lily D. Poulikakos ◽  
Bernhard Hofko ◽  
Laurent Porot ◽  
Xiaohu Lu ◽  
Hartmut Fischer ◽  
...  
Keyword(s):  
Softening Point ◽  
Mechanical Characterization ◽  
Chemical Characterization ◽  
Effect Of Temperature ◽  
Specimen Preparation ◽  
Structural Level ◽  
Short Term ◽  
Needle Penetration ◽  
Reduced Temperature

Properties of asphalt concrete after aging are important parameters in determining the long-term performance of these materials. With the popularity of reduced temperature mixtures the question remains how this reduced temperature in short-term aging affects the long-term properties. This paper focuses on developing a robust and fundamental understanding of the effect of temperature on aging by connecting the chemistry of bitumen to its mechanics. To this end, round robin experiments are being currently conducted within 8 laboratories using four binders of the same grade 70/100 pen from different crude sources. In developing chemo-mechanical characterization techniques at the nano- and micro-scale, the material’s variability from crude-source to crude-source and its sensitivity to temperature needs to be taken into consideration. Furthermore, the development of uniform specimen preparation procedures for these bituminous materials at the nano- and micro-structural level is the focus. The chemical characterization is performed using Fourier transform infrared spectroscopy (FTIR). For the mechanical characterization rheological data is used using the dynamic shear rheometer (DSR) as well as conventional tests, e.g. needle penetration and softening point using the ring and ball method. It is shown that the short-term aging temperature affects the increase in softening point, while the consequent effect on long term aging is less pronounced.

scholarly journals Association between ambient temperature and cognitive function in a community-dwelling elderly population: a repeated measurement study

BMJ Open ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. e049160
Author(s):  
Yuan-Ting C Lo ◽  
Wei-Peng Su ◽  
Shu-Hsuan Mei ◽  
Yann-Yuh Jou ◽  
Han-Bin Huang
Keyword(s):  
Older Adults ◽  
Cognitive Impairment ◽  
Cognitive Function ◽  
Ambient Temperature ◽  
Air Temperature ◽  
Community Dwelling ◽  
Secondary Outcome ◽  
Short Term ◽  
Temperature Exposure

ObjectivesEvidence on the associations between short-term and long-term air temperature exposure and cognitive function in older adults, particularly those in Asia, is limited. We explored the relationships of short-term and long-term air temperature exposure with cognitive function in Taiwanese older adults through a repeated measures survey.Design and settingWe used data the ongoing Taiwan Longitudinal Study on Aging, a multiple-wave nationwide survey.ParticipantsWe identified 1956, 1700, 1248 and 876 older adults in 1996, 1999, 2003 and 2007, respectively.Primary and secondary outcome measuresParticipants’ cognitive function assessment was based on the Short Portable Mental Status Questionnaire. We calculated the temperature moving average (TMA) for temperature exposure windows between 1993 and 2007 using data from air quality monitoring stations, depending on the administrative zone of each participant’s residence. Generalised linear mixed models were used to examine the effects of short-term and long-term temperature changes on cognitive function.ResultsShort-term and long-term temperature exposure was significantly and positively associated with moderate-to-severe cognitive impairment, with the greatest increase in ORs found for 3-year TMAs (OR 1.247; 95% CI 1.107 to 1.404). The higher the quintiles of temperature exposure were, the higher were the ORs. The strongest association found was in long-term TMA exposure (OR 3.674; 95% CI 2.103 to 6.417) after covariates were controlled for.ConclusionsThe risk of mild cognitive impairment increased with ambient temperature in community-dwelling older adults in Taiwan.

scholarly journals Квантование проводимости в мемристивных структурах на основе поли-п-ксилилена

2020 ◽  
Vol 54 (9) ◽  
pp. 913
Author(s):  
Б.С. Швецов ◽  
А.А. Миннеханов ◽  
А.А. Несмелов ◽  
М.Н. Мартышов ◽  
В.В. Рыльков ◽  
...  
Keyword(s):  
Room Temperature ◽  
Measurement Methods ◽  
Quantum States ◽  
Short Term ◽  
Quantization Effect ◽  
Long Term Stability ◽  
Neuromorphic Systems ◽  
Resistance State ◽  
Stable Quantum

The paper presents the results of a study at room temperature of the quantization effect of the conductivity of memristive structures based on the organic material poly-p-xylylene with resistive switching. Measurement methods are shown and a comparative analysis of the manifestation of the effect when switching structures to a high-resistance and low-resistance state is carried out. The possibility of setting stable quantum states of conductivity in memristive structures based on poly-p-xylylene is demonstrated. It is shown that some of these states have short-term, and some long-term stability. The results obtained open up new possibilities for using the quantization effect of conductivity in the implementation of neuromorphic systems.

scholarly journals Temperature Effect on Breakdown Performance of Insulating Polymer Thin Films

2017 ◽  
Author(s):  
Michael Ritamäki ◽  
Ilkka Rytöluoto ◽  
Kari Lahti
Keyword(s):  
Measurement Method ◽  
Room Temperature ◽  
Breakdown Strength ◽  
Effect Of Temperature ◽  
Large Area ◽  
Short Term ◽  
Weak Spot ◽  
Breakdown Probability ◽  
Weak Points ◽  
Multiple Breakdown

<p>The effect of temperature on the breakdown performance of metallized capacitor-grade BOPP film was characterized using a large-area multi-breakdown measurement method. The measurements conducted in the temperature range from room temperature to 100 °C revealed a linearly decreasing trend in the characteristic 63.2 % breakdown probability after 60 °C and the presence of a smaller weak spot subpopulation. The weak spots remained relatively unaffected by temperature, and first breakdowns occurred in a seemingly statistical manner. The brief exposure to elevated temperature was considered as one explanation behind the variations in the number of weak points, but fluctuations in film quality and Weibull dynamics were seen are more probable explanations. The results demonstrate the possibility of multiple breakdown mechanisms and their different temperature-dependency, and demonstrate the high short-term breakdown strength of BOPP film even at high temperatures.</p>

Nitrification with Biofilms on Small Suspended Particles in Airlift Reactors

1992 ◽  
Vol 26 (9-11) ◽  
pp. 2207-2211 ◽  
Author(s):  
L. Tijhuis ◽  
M. C. M. van Loosdrecht ◽  
J. J. Heijnen
Keyword(s):  
Activated Sludge ◽  
Loading Rate ◽  
Term Effect ◽  
Effect Of Temperature ◽  
Nitrification Rate ◽  
Activated Sludge Process ◽  
Short Term ◽  
Long Term Effect ◽  
N Loading

The development of nitrifying biofilms and short and long term influences on the nitrification process were studied in a Biofilm-Airlift-Suspension-reactor. The studied changes are (i) startup of nitrification reactor at different dilution rates, (ii) the effect of temperature on N-oxidation capacity, (iii) the short term effect of N-loading rate on conversion to determine the nitrification overcapacity and (iv) long term effect of N-loading rate on conversion to determine the maximum nitrification capacity in this reactor system. It is shown that the specific nitrification capacity during start-up is constant, 1 g N/(gorg.mat. d), which is high compared to the activated sludge process. The influence of the temperature on the nitrification rate is much less than can be expected from pure culture experiments. On a short term there is only a small nitrification overcapacity in the reactor. The maximum nitrification rate during these experiments was 6 kg N/(m3 d), which is very high compared to the activated sludge process.

scholarly journals Short- and Long-Term Exposure to Higher Temperatures is Linked to Cognitive Impairment in Taiwanese Older Adults

2020 ◽  
Author(s):  
Wei-Peng Su ◽  
Yuan-Ting C. Lo ◽  
Shu-Hsuan Mei ◽  
Yu-Hung Chang ◽  
Han-Bin Huang
Keyword(s):  
Older Adults ◽  
Cognitive Impairment ◽  
Cognitive Function ◽  
Air Temperature ◽  
Repeated Measures ◽  
Community Dwelling ◽  
Short Term ◽  
Multiple Wave ◽  
Temperature Exposure

Abstract Background: Evidence on the associations between short-term and long-term air temperature exposure and cognitive function in older adults, particularly those in Asia, is limited. Therefore, we explored the relationships of short-term and long-term air temperature exposure with cognitive function in Taiwanese older adults through a repeated measures survey.Methods: We used data from between 1996 and 2007 from the ongoing Taiwan Longitudinal Study on Aging (N = 1956), a multiple-wave nationwide survey. Participants’ cognitive function assessment was based on the Short Portable Mental Status Questionnaire. We calculated the temperature moving average (TMA) for temperature exposure windows between 1993 and 2007 using data from air quality monitoring stations, depending on the administrative zone of each participant’s residence. Generalized linear mixed models were used to examine the effects of short-term and long-term temperature changes on cognitive function.Results: Short-term and long-term temperature exposure was significantly and positively associated with moderate-to-severe cognitive impairment, with the greatest increase in odds ratios (ORs) found for 3-year TMAs (OR = 1.247; 95% confidence interval [CI]: 1.107, 1.404). The higher the quintiles of temperature exposure were, the higher were the ORs. The strongest association found was in long-term TMA exposure (OR = 3.674; 95% CI: 2.103, 6.417) after covariates were controlled for.Conclusions: The risk of mild cognitive impairment increased with ambient temperature in community-dwelling older adults in Taiwan.

Emulsified Sol-Gel Microspheres for Controlled Drug Delivery

2007 ◽  
Vol 330-332 ◽  
pp. 1025-1028
Author(s):  
Shula Radin ◽  
T.L. Chen ◽  
Paul Ducheyne
Keyword(s):  
Controlled Release ◽  
Room Temperature ◽  
Sol Gel ◽  
In Vitro Release ◽  
Processing Parameters ◽  
Short Term ◽  
Acid Catalyzed ◽  
Vitro Release

Controlled release silica sol-gels are room temperature processed, porous, resorbable, and biocompatible materials. Many molecules including drugs, proteins, and growth factors can be released from sol-gels, and the quantity and duration of the release can vary widely. Processing parameters render these release properties exquisitely versatile [1]. The synthesis of controlled release sol-gels involves several steps: an acid-catalyzed hydrolysis to form a sol with the molecules included, followed by casting, aging, and drying. Additional steps such as grinding and sieving are required to produce sol-gel granules of a desirable size. In this study, we focus on the synthesis of controlled release sol-gel microspheres by using a novel process, which involves only two steps:sol formation followed by emulsification. Sol-gel microspheres containing either vancomycin (antibiotic) or bupivacaine (analgesic) were successfully synthesized via this synthesis route. Both drugs showed controlled, load-dependent and time-dependent release from the microspheres. The in vitro release properties of sol-gel microspheres were different from those of sol-gel granules produced by grinding and sieving. In comparison to a fast, short-term release from the granules, the release from the microspheres was slower and of longer duration. In addition, the degradation rate of microspheres was significantly slower than that of the granules. These data enable the use of sol-gel powders for controlled long-term release.

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