Time Of Maximum Stress Research Articles

Metodologias para indicar estresse causado por jejum em poedeiras comerciais

ABSTRACT: Plasma corticosterone concentration (CORT), heterophil:lymphocyte ratio (H:L), catalase activity (CAT), total glutathione concentration (GSH), and thiobarbituric acid reactive substance levels (TBARS) were evaluated in 48 Hy-Line Brown laying hens, at 79 weeks of age, after being fasted for 10 consecutive days. Blood was collected on days zero, two, four, six, eight, and 10 of fasting, and a completely randomized design was adopted, with eight replicates on each day of collection, with each bird being an experimental unit. The time of maximum stress was determined for each method, using the polynomial regression analysis. The Pearson correlation analysis was also performed to determine whether the methods were interchangeable. CORT and GSH concentrations indicated that the time of maximum stress occurred at 4.3 days of fasting, whereas, the H:L and CAT activity indicated that the time of maximum stress occurred at 10 days of fasting. The malondialdehyde concentration detected by the TBARS method was highest at day zero and lowest at day 5.5 of fasting, but this method was not a reliable measure of stress. The low Pearson correlation coefficients observed among the methods made it impossible to designate only one of the tested methods as a replacement for the others, to measure the stress in laying hens during fasting.

Stress Shifting Effect of Hydrogen Mixed Natural Gas Pipe Under Seismic Wave

Abstract Hydrogen energy is a kind of clean secondary energy sources. Mixed hydrogen natural gas transportation technology is a new scheme of hydrogen transportation. Using natural gas pipe to transport hydrogen is expected to further promote its application. In order to study the mechanical properties of buried steel pipe under seismic waves, a numerical model is established. The time history and stress distribution of pipe section under seismic wave are analyzed. Effects of seismic intensity, surrounding soil, buried depth and seismic wave type on pipe's mechanical properties are discussed. The results show that the pipe section stress fluctuates under seismic wave, and the stress shifting effect occurs. The maximum stress is located in the directions of 45 deg, 135 deg, 225 deg, and 315 deg. Stress increases with the increasing of seismic intensity, and the stress distribution of pipe section is also changed. Stress responses of the pipe in different soil are different, and the stress distribution of pipe section at the maximum stress time is similar. The deeper the buried depth is, the greater the pipe stress is. Pipe stress is related to the maximum acceleration of the seismic wave and spectrum characteristics. Those results can provide a basis for the design and safety evaluation of mixed hydrogen natural gas pipes.

A method to estimate the maximum stress time in a fault zone before an earthquake

A method to estimate the maximum stress time in a fault zone before an earthquake

Linking plant and soil indices for water stress management in black gram

Measurement of plant and soil indices as well as their combinations are generally used for irrigation scheduling and water stress management of crops and horticulture. Rapid and accurate determination of irrigation time is one of the most important issues of sustainable water management in order to prevent plant water stress. The objectives of this study are to develop baselines and provide irrigation scheduling relationships during different stages of black gram growth, determine the critical limits of plant and soil indices, and also determine the relationships between plant physiology and soil indices. This study was conducted in a randomized complete block design at the four irrigation levels 50 (I1), 75 (I2), 100 (I3 or non-stress treatment) and 125 (I4) percent of crop’s water requirement with three replications in Urmia region in Iran in order to irrigation scheduling of black gram using indices such as canopy temperature (Tc), crop water stress index (CWSI), relative water content (RWC), leaf water potential (LWP), soil water (SW) and penetration resistance (Q) of soil under one-row drip irrigation. The plant irrigation scheduling was performed by using the experimental crop water stress index (CWSI) method. The upper and lower baseline equations as well as CWSI were calculated for the three treatments of I1, I2 and I3 during the plant growth period. Using the extracted baselines, the mean CWSI values for the three treatments of I1, I2 and I3 were calculated to be 0.37, 0.23 and 0.15, respectively, during the growth season. Finally, using CWSI, the necessary equations were provided to determine the irrigation schedule for the four growing stages of black gram, i.e. floral induction-flowering, pod formation, seed and pod filling and physiological maturity, as (Tc − Ta)c = 1.9498 − 0.1579(AVPD), (Tc − Ta)c = 4.4395 − 0.1585(AVPD), (Tc − Ta)c = 2.4676 − 0.0578(AVPD) and (Tc − Ta)c = 5.7532 − 0.1462(AVPD), respectively. In this study, soil and crop indices, which were measured simultaneously at maximum stress time, were used as a complementary index to remove CWSI constraints. It should be noted that in Urmia, the critical difference between the canopy temperature and air temperature (Tc − Ta), soil penetration resistance (Q), soil water (SW) and relative water content (RWC) for the whole growth period of black gram were − 0.036 °C, 10.43 MPa and 0.14 cm3 cm−3 and 0.76, respectively. Ideal point error (IPE) was also used to estimate RWC, (Tc − Ta) and LWP as well as to select the best regression model. According to the results, black gram would reduce its RWC less through reducing its transpiration and water management. Therefore, it can be used as a low-water-consuming crop. Furthermore, in light of available facilities, the farmer can use the regression equations between the obtained soil and plant indices and the critical boundaries for the irrigation scheduling of the field.

Superhydrophobic, compressible, and reusable polyvinyl alcohol-wrapped silver nanowire composite sponge for continuous oil-water separation

Herein, we applied a coaxial cable type polyvinyl alcohol-wrapped silver nanowire (Ag-PVAs) composite sponge as adsorbent material for oil/water separation. The Ag-PVAs sponge was prepared by two steps of hydrothermal and freeze-drying, and then modified with polydimethylsiloxane (PDMS) to reduce its surface energy. The modified Ag-PVAs sponge (f-PDMS) displayed superhydrophobic property due to its porous structure and low surface energy. Importantly, the f-PDMS has 14 times of maximum stress, compared with that of Ag-PVAs. Meanwhile, the maximum compressive stress of the f-PDMS sponge can still be maintained at 87.3% after 50 stress-strain cycles at 70% strain. Moreover, the f-PDMS sponge exhibits good adsorption properties for various oils with different densities and can be reused by extrusion and evaporation. Continuous oil/water separation can also be achieved with the aid of a vacuum pump, which will make it a powerful competitor for large-scale industrial separation of oil/organic solvents and water mixtures.

Wind-induced fatigue analysis of wind turbine steel tower

In this paper, a wind turbine tower with a hub height of 60m is taken as the research object, and its wind-induced fatigue analysis is carried out. First, the general method of wind-induced fatigue analysis of the wind turbine tower is given. The maximum stress time history curve of the tower is calculated by the time history analysis method. The stress amplitude, the mean value and the cycle times of the stress time history are counted by the rain-flow counting method. Finally, the fatigue life of tower is calculated by linear damage theory. According to the study, the fatigue life of the wind turbine is greater than that of the design service life, and it can meet the requirements of the design. The influence of wind load on the fatigue damage of the tower is different from the wind load of different wind speed and wind direction.

More comprehensive 3D modeling of clay‐like material drying

Drying process plays an important role in the manufacturing of many products such as ceramic, kitchenware and building materials, some of which have complex three‐dimensional (3D) geometry. To deal with many restrictions found in literatures, a 3D numerical approach was used to describe the drying process of a porous Clay‐like material. The problem investigated involves highly coupled equations considering heat, mass, and mechanical aspects. The model is validated through the comparison of experimental measurements with simulation result. Simulation results show that increasing the initial moisture content and reducing the initial temperature have the same privilege and without significant increase in drying time, it reduces slightly the amount of maximum stress but delays the occurrence time of maximum stress. The nonuniform heat expansion induced stresses are very small in comparison to nonuniform moisture shrinkage induced stresses and can be neglected in drying simulation. © 2017 American Institute of Chemical Engineers AIChE J, 64: 1469–1478, 2018

The Effect of Zinced Sheet on Residual Stress of Composite Material with TPO During Cure Process

Based on the indirect thermal‐stress coupled strategy that the first analysis was temperature field and the second analysis was stress field, the process induced residual stress/strain of composite parts with zinced steel and TPO was numerical simulated by ANSYS software. Moreover, the role of zinced steel played on composite material part was successfully simulated. The results show that the time of maximum stress occurred for two materials was changed due to the effect of zinced steel. Because of the constrain from zinced steel, composite material part bearded more residual stresses compared to that without considering the effect of zinced steel during cure process.

Electricity security in the European Union—The conflict between national Capacity Mechanisms and the Single Market

The European Internal Energy Market aims to promote trade and competition in electricity generation across the EU, with investment signals for new generation capacity and interconnection coming from zonal electricity prices reflecting scarcity value. However, a growing number of EU Member States have implemented national Capacity Mechanisms in order to ensure future security of supply within their own borders, which may distort the cross-border trade of energy. This local view of energy security is in response to internal technical and economic constraints and a perceived inability of cross-border electricity flows to be a reliable source of capacity at times of maximum stress, in favour of self-sufficiency. A number of routes are available to resolve this conflict through permitting cross-border participation of generators in local Capacity Mechanisms, but this requires resolution of a number of complicating factors, not least a means for properly allocating transmission capacity without introducing further distortions to the energy market. Alternative solutions could be enacted at an EU-level, such as through the alignment of Capacity Mechanisms to a common model, or the introduction of an EU-wide single Capacity Mechanism, but the current regulatory focus appears to remain on resolution of such issues at a national level.

Interleaving Test Algorithm for Subthreshold Leakage-Current Defects in DRAM Considering the Equal Bit Line Stress

Since the minimum feature size of dynamic RAM has been down-scaled, several studies have been carried out to determine ways to protect cell data from leakage current in many areas. In the field of testing, more appropriate test algorithms are required to detect weak cells with leakage-current sources. In this paper, we propose an interleaving test algorithm that takes into account the equal bit-line stress regardless of the cell location. The proposed test algorithm allows screening of weak cells that cannot hold cell data due to the subthreshold leakage current. During the stress period, the algorithm can also detect other leakage currents. This paper presents the maximum stress differences according to the cell location, and determines the influence of the refresh operation on the maximum stress time. Therefore, this paper suggests a correlation between the refresh and read time to give maximum stress time.

Effects of regulated deficit irrigation during the pre-harvest period on gas exchange, leaf development and crop yield of mature almond trees.

We investigated the effects of regulated deficit irrigation (RDI) during the pre-harvest period (kernel-filling stage) on water relations, leaf development and crop yield in mature almond (Prunus dulcis (Mill.) D.A. Webb cv. Cartagenera) trees during a 2-year field experiment. Trees were either irrigated at full-crop evapotranspiration (ETc=100%) (well-irrigated control treatment) or subjected to an RDI treatment that consisted of full irrigation for the full season, except from early June to early August (kernel-filling stage), when 20% ETc was applied. The severity of water stress was characterized by measurements of soil water content, predawn leaf water potential (Psipd) and relative water content (RWC). Stomatal conductance (gs), net CO2 assimilation rate (A), transpiration rate (E), leaf abscission, leaf expansion rate and crop yield were also measured. In both years, Psipd and RWC of well-irrigated trees were maintained above -1.0 MPa and 92%, respectively, whereas the corresponding values for trees in the RDI treatment were -2.37 MPa and 82%. Long-term water stress led to a progressive decline in gs, A and E, with significant reductions after 21 days in the RDI treatment. At the time of maximum stress (48 days after commencement of RDI), A, gs and E were 64, 67 and 56% lower than control values, respectively. High correlations between A, E and gs were observed. Plant water status recovered within 15 days after the resumption of irrigation and was associated with recovery of soil water content. A relatively rapid and complete recovery of A and gs was also observed, although the recovery was slower than for Psipd and RWC. Severe water stress during the kernel-filling stage resulted in premature defoliation (caused by increased leaf abscission) and a reduction in leaf growth rate, which decreased tree leaf area. Although kernel yield was correlated with leaf water potential, RDI caused a nonsignificant 7% reduction in kernel yield and had no effect on kernel size. The RDI treatment also improved water-use efficiency because about 30% less irrigation water was applied in the RDI treatment than in the control treatment. We conclude that high-cropping almonds can be successfully grown in semiarid regions in an RDI regime provided that Psipd is maintained above a threshold value of -2 MPa.

Perioperative nutrition

Perioperative nutrition

Adrenocortical disorders.

Preoperative preparation for the patient with adrenal disorders is directed toward restoring the intravascular volume and the electrolyte concentrations to normal. Hypertension and hypokalemia may be controlled by restricting sodium intake and administration of the aldosterone antagonist spironolactone. Patients taking steroids preoperatively must be adequately replaced throughout the perioperative phase at times of maximum stress.

Residents’ Use of Humanistic Skills and Content of Resident Discussions in a Support Group

In a 1983 position paper, the American Board of Internal Medicine stressed the importance of teaching humanistic skills to residents; however, how to teach or measure these skills is not well defined. In this study, the content of discussion (personal and professional problems) and processing of four humanistic skills (empathy, level of regard, unconditionality, and congruence) by Bowman Gray School of Medicine first year general medicine residents was observed. Fourteen videotapes of support group meetings from 1986 to 1988 were reviewed for humanistic relationship behaviors using the Barrett-Lennard Relationship Inventory and for the types of personal and professional problems discussed using a content inventory. Barrett-Lennard Relationship Inventory scores for empathy and regard paralleled increases in the number of professional problems raised at midyear, a time of maximum stress for residents. Congruence scores became flat after an initial peak while unconditionality scores remained low. Interventions designed to improve residents' use of humanistic skills could take into account residents' need for support and education, as well as the natural flow of humanistic behaviors within residency programs.

Nodule activity and allocation of photosynthate of soybean during recovery from water stress.

Nodulated soybean plants (Glycine max [L.] Merr. cv Ransom) in a growth-chamber study were subjected to a leaf water potential (psi w) of -2.0 megapascal during vegetative growth. Changes in nonstructural carbohydrate contents of leaves, stems, roots, and nodules, allocation of dry matter among plant parts, in situ specific nodule activity, and in situ canopy apparent photosynthetic rate were measured in stressed and nonstressed plants during a 7-day period following rewatering. Leaf and nodule psi w also were determined. At the time of maximum stress, concentration of nonstructural carbohydrates had declined in leaves of stressed, relative to nonstressed, plants, and the concentration of nonstructural carbohydrates had increased in stems, roots, and nodules. Sucrose concentrations in roots and nodules of stressed plants were 1.5 and 3 times greater, respectively, than those of nonstressed plants. Within 12 hours after rewatering, leaf and nodule psi w of stressed plants had returned to values of nonstressed plants. Canopy apparent photosynthesis and specific nodule activity of stressed plants recovered to levels for nonstressed plants within 2 days after rewatering. The elevated sucrose concentrations in roots and nodules of stressed plants also declined rapidly upon rehydration. The increase in sucrose concentration in nodules, as well as the increase of carbohydrates in roots and stems, during water stress and the rapid disappearance upon rewatering indicates that inhibition of carbohydrate utilization within the nodule may be associated with loss of nodule activity. Availability of carbohydrates within the nodules and from photosynthetic activity following rehydration of nodules may mediate the rate of recovery of N2-fixation activity.

Cross-correlation of voice and heart rate as stress measures

Heart rate and O 2 uptake, etc. have been widely used to assess the physical fitness of human subjects. Recently developed Hayre voice-based parameters for physical stress or fatigue are validated by the results of this work. These parameters are not only non-obtrusive means of real time observation of clinical, educational and physical training of subjects but also provide a unique comparative means of monitoring physical fatigue among various professionals such as athletes, truck drivers, pilots and doctors of medicine, etc. Subjects of various ages running on a treadmill were instrumented for recording heart rate, EKG, treadmill speed and slope. The treadmill was run at 3·3 mph (90 m/min) and the grade was increased by one per cent a minute up to a maximum of 25 per cent and then the speed was increased by 0·2 mph until exhaustion. Each subject was asked to count from one to ten and utter two other preselected words separated by silence gaps in between for ease of analysis. An analysis of these utterances indicates that a monotonic increase in heart rate is highly correlated with Hayre parameters G 1 and F 1 mentioned above, up to the time of maximum stress and the associated peak heart rate of 175. After stopping the treadmill run and letting the subject sit down, the heart rate starts dropping rapidly whereas the Hayre stress parameter G 1 tends to increase to a saturation level, thus verifying that the continued physically stressed state of the subject has not significantly lessened as one would perceive from the above mentioned drop in heart rate.

Low Cycle Corrosion Fatigue of Aluminum Alloy

Studies have been mede on the influence of no stress time, varying stress time and maximum stress time in 1 cycle on low cycle corrosion fatigue strength of Al alloy. The electrode potential of the specimens has been measured against the saturated calomel electrode during the cycles and the fatigue cracks have been observed through a microscope. The following facts have been made clear.(1) When the cycle frequency is constant, varying stress time (ta) and maximum stress time (tm) have destructive effects which will increase the corrosion fatigue damage. The effect of ta is greater than the effect of tm. This results are due to the difference of recovery of the corrosion potential on the specimen surface.(2) When the cycle frequency gets slower owing to the increase of varying stress time (ta), destructive effects appear. When the cycle frequency gets slower by the increase of no stress time (t0) or maximum stress time (tm), protective effects appear which decrease the corrosion fatigue damage. The protective effects are due to the recovery of the corrosion potential in the crack initiation period. In the crack propagation period the effects are due to the decrease of crack propagation rate caused by the lowering of stress concentration according to the branching or the thickening of the crack tip, or to the pit formation from the cracks.