The Effect of Simulated Post Weld Heat Treatment Temperature Overshoot on Microstructural Evolution in P91 and P92 Power Plant Steels
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Abstract Creep strength enhanced ferritic (CSEF) steels, particularly modified 9Cr steels Grade 91 and 92, are increasingly used in advanced coal-fired power plants for header and steam piping construction. While these materials typically enter service after receiving a standard high-temperature normalizing treatment followed by lower temperature tempering to achieve optimal microstructure, practical situations like welding operations may expose components to additional heat treatment exceeding the Ac1, and potentially the Ac3, temperature before returning to tempering temperature. This research examines the effects of simulated post weld heat treatments (PWHT) on Grade 91 and 92 materials using dilatometer-controlled heating and cooling rates, with peak temperatures below Ac1, between Ac1 and Ac3, and above Ac3, followed by heat treatment at 750°C for 2 hours. Hardness measurements revealed significant reduction when exceeding the Ac1 temperature, while advanced electron microscopy, including electron back scatter diffraction, was employed to analyze changes in martensite laths and grain structure, along with detailed carbide size distribution analysis using both scanning and transmission electron microscopy. The findings are discussed in terms of how such PWHT overshoots might affect mechanical properties during high-temperature service.Keywords:
Overshoot (microwave communication)
For energy-conservation in temperature control, the overshoot should be decreased. To overcome this, we newly developed a function to adjust the overshoot against disturbances. In this paper, this new control system for adjusting the overshoot against disturbance is described. as well as the test results to show the overshoot suppression effects in packing machine temperature control. As a result, we confirm that this new control system can realize a 50% reduction of the time takes until the temperature gets stable.
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One way of characterizing a system is to consider its response to a unit step function (a function whose value is zero until l t = 0 and is one thereafter). When considering the system's step response , a typical goal is to determine whether it is ever negative (even though the steady-state response is positive), in which case the system suffers from undershoot . An additional goal is to determine whether or not the system?s step response ever exceeds its steady-state output, in which case the system suffers from overshoot. For more on the significance of under- and overshoot, see "Why Undershoot and Overshoot Are Significant." This article presents precise conditions under which systems will suffer from undershoot and overshoot. Some easier-to-use rules of thumb are also provided. Although these are useful, it will be shown that the given conditions are not actually necessary and, in the case of overshoot, are not sufficient either.
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The Intergovernmental Panel on Climate Change's (IPCC) special report on global warming of 1.5 degrees Celsius (degrees C) makes clear that most scenarios (90%) that hold warming to 1.5 degrees C by 2100 include an overshoot, or a period in which the temperature increase exceeds 1.5 degrees C before declining to the end-of-century 1.5 degrees C goal (IPCC 2018). An overshoot is also possible for 2 degrees C scenarios, given the lack of ambition in existing mitigation commitments. Current conservation policy and planning does not adequately account for the high likelihood of a temperature overshoot in a 1.5 degrees C scenario, but the impacts of an overshoot on conservation may be large. Efforts to avoid an overshoot must be increased through more ambitious mitigation commitments and a greater focus on peak warming rather than end-of-century outcomes. Simultaneously, conservation planning should account for such impacts by anticipating more dynamic systems that carry greater uncertainties and potentially irreversible changes that may persist even as temperatures peak and decline.
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In a previous experiment, threshold was measured for a brief duration probe positioned temporally at the onset of a broadband masker, with and without a broadband precursor, to determine the amount of overshoot. The probe level was then fixed 10 dB above the threshold levels determined in the overshoot experiment, and a notched-noise masker was varied in level to estimate filter shape, with and without a precursor. In general, filters were broader and the signal-to-noise ratio at threshold, k, was lower following a precursor, but there was not a clear relationship between the amount of change in the filters and overshoot. In the present study, filter shapes were measured with the probe level set at the threshold from the overshoot experiment, rather than 10 dB above. Results revealed that the change in k is in general closely related to the amount of overshoot (which would be expected) and also that there is at least some relationship between the change in filter width and the amount of overshoot. The study was also extended to look at possible filtering changes with decrease in overshoot, and to look at effects of overshoot from off-frequency precursors and maskers. [Work supported by NIH (NIDCD).]
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The factors which effect the overshoots of pressure sensor and its measurement method are described,and pointed out that the overshoot is affected by the rising time of input signal when the rising time tr0.02π/ωd,and it is the largest one when the overshoot is measured by the end-wall sensor mounting shock tube,it must be calibrated according to the working states of pressure sensor when the effect of overshoot should be considered in the measuring of pressure.
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In this paper, properties of overshoot and undershoot as functions of circuit parameters are formally investigated. We identified existence conditions of overshoot and undershoot. Analytic solutions of overshoot and undershoot amplitudes by line length, termination, and rise time are derived. These analytic solutions have a form of two-piece linear dependence of these amplitudes on interconnect length. Simulation results for lossy pin-to-pin and daisy-chain interconnects demonstrated this dependence even with loss effects present. The role of interconnect length in the control of overshoot and undershoot at the physical design step is investigated.
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A number of biological systems can be modeled by Markov chains. Recently, there has been an increasing concern about when biological systems modeled by Markov chains will perform a dynamic phenomenon called overshoot. In this article, we found that the steady-state behavior of the system will have a great effect on the occurrence of overshoot. We confirmed that overshoot in general cannot occur in systems which will finally approach an equilibrium steady state. We further classified overshoot into two types, named as simple overshoot and oscillating overshoot. We showed that except for extreme cases, oscillating overshoot will occur if the system is far from equilibrium. All these results clearly show that overshoot is a nonequilibrium dynamic phenomenon with energy consumption. In addition, the main result in this article is validated with real experimental data.
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This study is concerned with the mechanism of off-frequency overshoot. Overshoot refers to the phenomenon whereby a brief signal presented at the onset of a masker is easier to detect when the masker is preceded by a “precursor” sound (which is often the same as the masker). Overshoot is most prominent when the masker and precursor have a different frequency than the signal (henceforth referred to as “off-frequency overshoot”). It has been suggested that off-frequency overshoot is based on a similar mechanism as “enhancement,” which refers to the perceptual pop-out of a signal after presentation of a precursor that contains a spectral notch at the signal frequency; both have been proposed to be caused by a reduction in the suppressive masking of the signal as a result of the adaptive effect of the precursor (“adaptation of suppression”). In this study, we measured overshoot, suppression, and adaptation of suppression for a 4-kHz sinusoidal signal and a 4.75-kHz sinusoidal masker and precursor, using the same set of participants. We show that, while the precursor yielded strong overshoot and the masker produced strong suppression, the precursor did not appear to cause any reduction (adaptation) of suppression. Predictions based on an established model of the cochlear input–output function indicate that our failure to obtain any adaptation of suppression is unlikely to represent a false negative outcome. Our results indicate that off-frequency overshoot and enhancement are likely caused by different mechanisms. We argue that overshoot may be due to higher-order perceptual factors such as transient masking or attentional diversion, whereas enhancement may be based on mechanisms similar to those that generate the Zwicker tone.
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본 논문은 M/$E_n$ /1 큐에서 overshoot에 대한 근사식을 제안한다. overshoot은 큐의 작업부하량과정이 어떤 한계점을 처음으로 초과한 순간에 그 초과량을 의미하는데, overshoot의 분포 및 1차, 2차 적률은 큐의 최적화문제를 푸는데 중요한 역할을 한다. 본 논문에서는 그동안 이루어진 overshoot의 분포에 대한 이론적인 결과를 바탕으로 하여 overshoot의 분포를 고객의 서비스시간의 분포와 지수분포의 선형결합으로 표현하는 근사식을 제안한다. 그리고 제안된 근사식의 정확성을 확인하기 위하여 시뮬레이션을 통해 구한 overshoot의 분포와 비교한다. In this paper, we propose an approximation to the overshoot in M/$E_n$ /1 queues. Overshoot means the size of excess over the threshold when the workload process of an M/$E_n$ /1 queue exceeds a prespecified threshold. The distribution, $1^{st}$ and $2^{nd}$ moments of overshoot have an important role in solving some kind of optimization problems. For the approximation to the overshoot, we propose a formula that is a convex sum of the service time distribution and an exponential distribution. We also do a numerical study to check how exactly the proposed formula approximates the overshoot.
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