Slow Ramp Research Articles

Use of slow atomization ramp in high resolution continuum source graphite furnace atomic absorption spectrometry for the simultaneous determination of Cd and Ni in slurry powdered chocolate samples

A methodology for simultaneous (not sequential) determination of Cd and Ni in powder chocolate samples by high-resolution continuum source graphite furnace atomic absorption spectroscopy (HR–CS–GF-AAS) and slurry sample analysis was developed. Acid digestion of the samples was not necessary, considering the high total fat content of this type of matrix (above 10 %), and no apparent deterioration of the graphite tubes was even observed once these samples were subjected to analysis. Despite the volatilities of both elements are quite different, simultaneous quantification was achieved using a slow heating ramp atomization, covering a convenient and wide temperature gradient for Cd volatilization at low temperatures and subsequent atomization of Ni at elevated temperatures, using the same heating program without an apparent change in sensitivity. This slow heating ramp was essayed between 200 and 1500 °C·s−1 and optimized at 400 °C·s−1, achieving the simultaneous measuring of Cd in the principal line (228.8018 nm) and using a secondary for Ni (228.9984 nm). No stop events for sequential changes in wavelength or temperature additional steps were involved in the method and molecular spectral interferences overlapping the analyte signals were corrected appropriately by a pragmatic strategy taking advantage of the fine structure signals adjacent to analyte signals within the same spectrum recorded. Palladium matrix modifier and aqueous standards were used for the calibration and determination of both elements in the samples. The method accuracy was successfully confirmed using a reference material (NIST SRM 1573a). An improvement in the sensitivity of Ni was found using a greater number of pixels for signal integration, central and five adjacent pixels (CP ± 5), while a lengthening of the linear range of Cd was obtained by using an attenuated signal (±2) or using only one pixel (CP). The limits of detection were 0.027 μg g−1 and 0.22 μg g−1 for Cd and Ni respectively by this simple methodology using aqueous standards for calibration and the simultaneous determination of both elements in the same measurement. The respective limits of quantification for Cd and Ni were 0.090 and 0.72 μg g−1 and the relative standard deviations in samples (n = 5) were about 4–20% and 0.3–11% for Cd and Ni respectively. The optimized method was used for the determination of both elements in real samples purchased from retail supermarkets finding variable concentrations between 0.5 and 5.7 μg g−1 for Cd and 2.1–10.9 μg g−1 for Ni, comparable to levels reported in the literature referred to elsewhere in the world.

Improved acquisition of contact heat evoked potentials with increased heating ramp

Contact heat evoked potentials (CHEPs) represent an objective and non-invasive measure to investigate the integrity of the nociceptive neuraxis. The clinical value of CHEPs is mostly reflected in improved diagnosis of peripheral neuropathies and spinal lesions. One of the limitations of conventional contact heat stimulation is the relatively slow heating ramp (70 °C/s). This is thought to create a problem of desynchronized evoked responses in the brain, particularly after stimulation in the feet. Recent technological advancements allow for an increased heating ramp of contact heat stimulation, however, to what extent these improve the acquisition of evoked potentials is still unknown. In the current study, 30 healthy subjects were stimulated with contact heat at the hand and foot with four different heating ramps (i.e., 150 °C/s, 200 °C/s, 250 °C/s, and 300 °C/s) to a peak temperature of 60 °C. We examined changes in amplitude, latency, and signal-to-noise ratio (SNR) of the vertex (N2-P2) waveforms. Faster heating ramps decreased CHEP latency for hand and foot stimulation (hand: F = 18.41, p < 0.001; foot: F = 4.19, p = 0.009). Following stimulation of the foot only, faster heating ramps increased SNR (F = 3.32, p = 0.024) and N2 amplitude (F = 4.38, p = 0.007). Our findings suggest that clinical applications of CHEPs should consider adopting faster heating ramps up to 250 °C/s. The improved acquisition of CHEPs might consequently reduce false negative results in clinical cohorts. From a physiological perspective, our results demonstrate the importance of peripherally synchronizing afferents recruitment to satisfactorily acquire CHEPs.

Performance Analyses of a RAIM Algorithm for Kalman Filter with GPS and NavIC Constellations.

This paper evaluates the performance of an integrity monitoring algorithm of global navigation satellite systems (GNSS) for the Kalman filter (KF), termed KF receiver autonomous integrity monitoring (RAIM). The algorithm checks measurement inconsistencies in the range domain and requires Schmidt KF (SKF) as the navigation processor. First, realistic carrier-smoothed pseudorange measurement error models of GNSS are integrated into KF RAIM, overcoming an important limitation of prior work. More precisely, the error covariance matrix for fault detection is modified to capture the temporal variations of individual errors with different time constants. Uncertainties of the model parameters are also taken into account. Performance of the modified KF RAIM is then analyzed with the simulated signals of the global positioning system and navigation with Indian constellation for different phases of aircraft flight. Weighted least squares (WLS) RAIM used for comparison purposes is shown to have lower protection levels. This work, however, is important because KF-based integrity monitors are required to ensure the reliability of advanced navigation methods, such as multi-sensor integration and vector receivers. A key finding of the performance analyses is as follows. Innovation-based tests with an extended KF navigation processor confuse slow ramp faults with residual measurement errors that the filter estimates, leading to missed detection. RAIM with SKF, on the other hand, can successfully detect such faults. Thus, it offers a promising solution to developing KF integrity monitoring algorithms in the range domain. The modified KF RAIM completes processing in time on a low-end computer. Some salient features are also studied to gain insights into its working principles.

Designing Robust and Automated Treatment Plans Utilizing Dynamic Couch Motion With Automated Treatment Planning: Optimizing Couch Motion for Precise Delivery ― Part A

<h3>Purpose/Objective(s)</h3> This study finds a relationship among couch speed, dose rate, and MLC, allowing gradual start and stop positioning of the couch for treatments utilizing dynamic couch-based dose delivery at static gantry positions. <h3>Materials/Methods</h3> We introduce a gantry static couch motion (GsCM) based technique, which delivers the dose using a dynamic couch and static gantry positions. It is imperative to study couch motion behavior for techniques like GsCM, where the patient is a moving target throughout the dose delivery. Sudden changes in couch speed can result in a shift in position and discomfort for the patient. Therefore, it is necessary to implement a smooth start, a constant speed in the middle, and deceleration at the couch's stopping positioning. We studied the relationship among the following parameters: dose rate, MLC speed, and couch motion. To fulfill this, we simulated a single treatment arc manually in the treatment planning system that includes multiple couch positions at static gantry positions. All the fields were merged into a single deliverable arc while exporting into the Extensible Markup Language (XML) format using the TPS scripting API. Developer mode on a Linac performed the treatment delivery. The second part of this study looked into the various ways to control the couch motion. Methods tried included a fixed couch speed versus controlling the couch speed by limiting the dose rate. Trajectory log files helped analyze the couch positional error (RMSE). <h3>Results</h3> We found couch speed optimization by limiting the dose rate is better than the MLC speed or couch speed. A slow ramping up and down of the speed with a constant speed in the middle of an arc field is achievable. Linac log file analysis showed minimum couch position error (RMSE: median 0.035⁰, range 0.02-0.0.045⁰) for 1° couch speed as compared to system defined couch speed (RMSE: median 0.07⁰, range 0.05-0.12⁰), and (RMSE: median 0.07⁰, range 0.06-0.09⁰) for 2° couch speed respectively. Even though 1° couch speed provided a minimum couch RMSE error but at the expense of a longer treatment time which is not suitable for keeping the patient longer on the treatment table. For the dose rate limiting option, couch positioning error at the start and stop location (RMSE: median 0.008⁰, range 0.006-0.02⁰) showed a gradual and accurate ramping up and down of the couch, and at the middle of the arc remained the same as noticed for the system defined couch speed (RMSE: median 0.09⁰, range 0.065-0.12⁰). <h3>Conclusion</h3> This feasibility study serves as an end-to-end test and is probably the first of its kind that thoroughly validates various ways to control the couch speed and its integration with patient motion during the dose delivery. Treatments utilizing dynamic couch-based dose delivery must include patient immobilization. Our study takes patient motion into account and provides gradual start and stop motions of the couch, which helps minimize the patient motion for treatments utilizing dynamic couch motion.

A Data-Driven Design for Gas Turbines Exit Temperature Spread Condition Monitoring System

One of the most complex and costly systems in the industry is the Gas turbine (GT). Because of the complexity of these assets, various indicators have been used to monitor the health condition of different parts of the gas turbine. Turbine exit temperature (TET) spread is one of the significant indicators that help monitor and detect faults such as overall engine deterioration and burner fault. The goal of this article is to use data-driven approaches to monitor TET data to detect faults early, as fault detection can have a significant impact on gas turbine reliability and availability. In this study, the TET data of v94.2 GT is measured by six temperature transmitters to show a detailed profile. According to the statistical tests, TET data are high dimensional and time-dependent in the real world industry. Hence, three distinctive methods in the field of the gas turbine are proposed in this study for early fault detection. Conventional principal component analysis (PCA), moving window PCA (MWPCA), and incremental PCA (IPCA) were implemented on TET data. According to the results, the conventional PCA model is a non-adaptive method, and the false alarm rate is high due to the incompatibility of this approach and the process. The MWPCA based on V-step-ahead and IPCA approaches overcame the non-stationary problem and reduced the false alarm rate. In fact, these approaches can distinguish between the normal time-varying and slow ramp fault processes. The results showed that IPCA could detect fault situations faster than MWPCA based on V-step-ahead in this study.

Fast-slow analysis as a technique for understanding the neuronal response to current ramps.

The standard protocol for studying the spiking properties of single neurons is the application of current steps while monitoring the voltage response. Although this is informative, the jump in applied current is artificial. A more physiological input is where the applied current is ramped up, reflecting chemosensory input. Unsurprisingly, neurons can respond differently to the two protocols, since ion channel activation and inactivation are affected differently. Understanding the effects of current ramps, and changes in their slopes, is facilitated by mathematical models. However, techniques for analyzing current ramps are under-developed. In this article, we demonstrate how current ramps can be analyzed in single neuron models. The primary issue is the presence of gating variables that activate on slow time scales and are therefore far from equilibrium throughout the ramp. The use of an appropriate fast-slow analysis technique allows one to fully understand the neural response to ramps of different slopes. This study is motivated by data from olfactory bulb dopamine neurons, where both fast ramp (tens of milliseconds) and slow ramp (tens of seconds) protocols are used to understand the spiking profiles of the cells. The slow ramps generate experimental bifurcation diagrams with the applied current as a bifurcation parameter, thereby establishing asymptotic spiking activity patterns. The faster ramps elicit purely transient behavior that is of relevance to most physiological inputs, which are short in duration. The two protocols together provide a broader understanding of the neuron's spiking profile and the role that slowly activating ion channels can play.

Threshold variations of medial pterygoid single motor units during vertical or horizontal force tasks.

To test the hypotheses that (a) the force thresholds at onset of medial pterygoid muscle single motor unit (SMU) activity do not decrease with an increase in the rate of force generation in standardised vertical or horizontal jaw-force tasks, and (b) there is evidence for functional heterogeneity within the medial pterygoid muscle. In 14healthy participants, electromyographic recordings of the right medial pterygoid muscle were performed with intramuscular fine-wire electrodes during four isometric force tasks: vertical, horizontal contralateral, horizontal protrusion and horizontal ipsilateral, performed at two rates of force development (slow ramp, fast ramp). Computer tomography scans confirmed electrode location within the muscle, which was divided into medial and lateral parts. Force thresholds of onset of discriminated SMUs were compared between rates in each task; significance accepted at p<0.05. Of 45 SMU force thresholds studied in one or more tasks, there was no significant difference between slow and fast ramp within each force task, except slow ramp thresholds from the lateral part during the vertical force task were significantly higher than fast ramp thresholds. Reversals of recruitment order between tasks provided evidence for functional heterogeneity within the muscle. Force thresholds of the vertical tasks (range: 1-292.6N) were mostly higher than for the horizontal tasks (range: 0.1-12.5N). The data are consistent with the proposal that the medial pterygoid muscle stabilises the jaw in the vertical plane during isometric force generation in the jaw closing, as well as horizontal directions.

Implantable vagus nerve stimulator settings and short-term adverse effects in epileptic dogs.

BackgroundImplantable vagus nerve stimulation (VNS) devices can be used to treat epilepsy in dogs. Adverse effects and short‐term complications associated with delivering suggested therapeutic electrical stimulation (>1.5 mA) are not well‐described.ObjectivesTo compare complications and adverse effects observed with standard and rapid protocols of current increase.AnimalsSixteen client‐owned dogs with idiopathic epilepsy.MethodsNonrandomized, nonblinded prospective cohort study. Surgical complications, stimulation‐related adverse effects, modifications to stimulator settings, number of hospital visits, and time to reach 1.5 mA stimulation current without intolerable adverse effects were described in dogs receiving current increases every 1 to 3 weeks (slow ramping) and dogs receiving current increases every 8 to 12 hours (fast ramping).ResultsSelf‐resolving surgery site seromas formed in 6 dogs. No other surgical complications were observed. Fourteen dogs reached 1.5 mA. Coughing (11/14 dogs; 5 slow, 6 fast ramping) was the most common adverse effect. Intolerable coughing that limited current increases despite changing other stimulus parameters occurred in 6/7 of the fast‐ramping group and in none of the slow‐ramping group. Median time to 1.5 mA was 72 days (range, 28‐98) in the slow‐ramping group and 77 days (range, 3‐152) in the fast‐ramping group. Median number of clinic visits was 6 for the slow‐ramping group (range, 5‐6) and 3 for the fast‐ramping group (range, 1‐7).Conclusions and Clinical ImportanceCoughing is a common adverse effect of VNS in dogs and generally is well tolerated, particularly if current is increased slowly and other stimulation parameters are adapted for effect.

A Takagi Sugeno based reactor power control of VVER-1000 using linear parameter varying identification of two-point kinetic model

This study aims to design Takagi Sugeno (TS) Fuzzy logic based power control for VVER-1000 PWR to achieve smooth and precise load following situations under various disturbances and model uncertainties. To achieve the purpose, a two-point kinetic model with consideration of neutron diffusion, thermal hydraulics and poison concentration is developed. Model identification for the equivalent linear parameter varying (LPV) system is performed using the fixed functional parameters and reproducing the corresponding LPV subsystems for each of those functional points in the form of SISO transfer function synthesis. Linear heft factors are introduced to compute the weighted output based on the triangular and trapezoidal membership functions of fuzzy logic. Linear interpolation is used to find the controlled power based on heft factors and operational specifications of the nuclear reactor over the entire power range. A TS fuzzy based controller with fixed gain and parameters is designed to efficiently control the reactor power under multiple transient conditions. The LPV subsystems are to be controlled with the fuzzy controller comprising two inputs with effective utilization of unsymmetrical, nonlinear and optimized membership functions and scaled output linear function of fuzzy variables. Stability analysis is performed using the Lyapunov like function and the condition is demonstrated for the two-point kinetic model of the reactor. The performance of the proposed framework is evaluated for load following scenarios with fast and slow ramp changes; along with accident handling with positive reactivity insertion tests. The proposed TS fuzzy power control model found preferably efficient in load tracking applications and disturbance rejection conditions.

Subcellular Distribution of Persistent Sodium Conductance in Cortical Pyramidal Neurons.

Cortical pyramidal neurons possess a persistent Na+ current (I NaP), which, in contrast to the larger transient current, does not undergo rapid inactivation. Although relatively quite small, I NaP is active at subthreshold voltages and therefore plays an important role in neuronal input-output processing. The subcellular distribution of channels responsible for I NaP and the mechanisms that render them persistent are not known. Using high-speed fluorescence Na+ imaging and whole-cell recordings in brain slices obtained from mice of either sex, we reconstructed the I NaP elicited by slow voltage ramps in soma and processes of cortical pyramidal neurons. We found that in all neuronal compartments, the relationship between persistent Na+ conductance and membrane voltage has the shape of a Boltzmann function. Although the density of channels underlying I NaP was about twofold lower in the axon initial segment (AIS) than in the soma, the axonal channels were activated by ∼10 mV less depolarization than were somatic channels. This difference in voltage dependence explains why, at functionally critical subthreshold voltages, most I NaP originates in the AIS. Finally, we show that endogenous polyamines constrain I NaP availability in both somatodendritic and axonal compartments of nondialyzed cortical neurons.SIGNIFICANCE STATEMENT The most salient characteristic of neuronal sodium channels is fast inactivation. However, a fraction of the sodium current does not inactivate. In cortical neurons, persistent current (I NaP) plays a prominent role in many important functions. Its subcellular distribution and generation mechanisms are, however, elusive. Using high-speed fluorescence Na+ imaging and electrical recordings, we reconstructed the I NaP in soma and processes of cortical pyramidal neurons. We found that at near-threshold voltages I NaP originates predominately from the axon, because of the distinctive voltage dependence of the underlying channels and not because of their high density. Finally, we show that the presence of endogenous polyamines significantly constrains I NaP availability in all compartments of nondialyzed cortical neurons.

Poroviscoelasticity and compression-softening of agarose hydrogels

Agarose hydrogels are poroviscoelastic materials that exhibit a waterlogged-crosslinked microstructure. Despite an extensive use in biotechnologies and numerous studies of the elastic properties of agarose gels, little is known about the compressible behavior and the microstructural changes of such fibrillar hydrogels under compression. The present work investigates the mechanical response of centimeter-sized pre-molded agarose cylinders when applying a compressive strain ramp over an extended range of loading speed and polymer concentration. One of the original contributions is the simultaneous monitoring of the changes in the hydrogel volume to determine the Poisson’s ratio through a spatiotemporal method. The linear poroelastic response of agarose hydrogels shows a compressible behavior at strain rates less than 0.7 % s−1. The critical compressive strain of a few percent at the onset of the non-linear regime and the always positive Poisson’s ratio decrease when applying a slow compressive ramp. The mechanical response in the linear regime is typical of a deformation mode either dominated by the bending of semiflexible strands (enthalpic regime) or by the stretching of the network (entropic regime) at higher agarose concentration. Cyclic linear shear deformations superimposed to a compressive strain from 0.5 up to 40% further give evidence of a compression-softening of the network causing the transition to the non-linear regime without dependence upon the network topology and connectivity. Finally, the buckling-induced aging of the network under a weak compression and the poroviscoelasticity of the hydrogel are shown to impact the relaxation of the normal stress and the equilibrium stress.

Thresholds, Firing Rates, and Order of Recruitment of Anterior Temporalis Muscle Single-Motor Units During Experimental Masseter Muscle Pain.

To test the hypothesis that, in comparison with control, experimental noxious stimulation of the right masseter muscle would result in significant changes in the firing rates, thresholds, and recruitment orders of single-motor units (SMUs) of the nonpainful, synergistic right anterior temporalis muscle during goal-directed isometric biting task performance. Twenty healthy volunteers received an infusion of hypertonic saline (HS; 5% sodium chloride) into the right masseter to produce pain intensity of 40 to 60 on a 100-mm visual analog scale (VAS). Isotonic saline (IS) infusion was a control. Standardized biting tasks were performed with an intraoral force transducer, and intramuscular electromyographic activity was recorded from the right anterior temporalis muscle. Tasks (slow and fast ramp biting tasks, two-step biting task) were performed in 3 blocks: baseline, HS infusion, and IS infusion. Across blocks, SMU thresholds and firing rates were statistically compared, and SMU recruitment sequences were qualitatively compared. Statistical significance was set at P < .05. No significant differences (P > .05) were noted between HS and IS infusion blocks in thresholds or firing rates of anterior temporalis SMUs. Individual SMUs showed increases or decreases in thresholds or firing rates or changes in recruitment sequences mostly during HS compared to IS infusion. The reorganization of SMU activity that has been suggested to occur in both painful and nonpainful agonist jaw muscles may involve not only recruitments and de-recruitments of SMUs, but may also extend to more subtle increases and/or decreases in firing rates, thresholds, and recruitment sequences of individual SMUs in the nonpainful synergistic muscles.

Non-Hermitian Kibble-Zurek Mechanism with Tunable Complexity in Single-Photon Interferometry

Non-Hermitian descriptions of quantum matter have seen impressive progress recently, with major advances in understanding central aspects such as their topological properties or the physics of exceptional points, the non-Hermitian counterpart of critical points. Here, we use single-photon interferometry to reconstruct the non-Hermitian Kibble-Zurek mechanism and its distinct scaling behavior for exceptional points, by simulating the defect production upon performing slow parameter ramps. Importantly, we are able to realise also higher-order exceptional points, providing experimental access to their theoretically predicted characteristic Kibble-Zurek scaling behaviour. Our work represents a crucial step in increasing the experimental complexity of non-Hermitian quantum time-evolution. It thus also furthers the quest to move the frontier from purely single-particle physics towards increasingly complex settings in the many-body realm.

Selective laser sintering (SLS)-printable thermosetting resins via controlled conversion

An alternative strategy toward SLS-printable thermosets is demonstrated based on partial curing of the material to increase the Tg of the resin and minimize the additional cure needed to cross-link the printed article. This material is then printed, yet it does not become cross-linked during the printing process. Rather, after printing the material is cured via a slow temperature ramp maintained just below the material’s evolving Tg. Although equipment limitations resulted in parts which have intrinsic porosity, the strategy employed here serves as the first demonstration of SLS printing and subsequent curing of minimally filled (< 1 wt% filler) high Tg (~ 200°C) thermoset materials competitive with popular thermoplastics such as PEEK and PPS.

Pedestal magnetic turbulence measurements in ELMy H-mode DIII-D plasmas by Faraday-effect polarimetry

Internal magnetic fluctuation measurements are utilized to identify turbulence associated with micro-tearing modes (MTM) in the DIII-D Edge-Localized-Mode (ELM)-y H-mode pedestal. Using a Faraday-effect polarimeter, magnetic turbulence (150–500 kHz) is directly observed with a typical line-averaged fluctuation amplitude of ∼0.8 G at peak frequency (250 kHz) and ∼15 G integrated over the spectrum from 150 to 500 kHz. Frequency, poloidal wavenumber, and propagation direction of the magnetic turbulence all serve to identify as MTM. Magnetic turbulence amplitude non-monotonically correlates with collision frequency, peaks off mid-plane, and correlates with electron temperature gradient evolution between ELMs, consistent with MTM features identified from theory and gyro-kinetic simulation. The magnetic turbulence growth correlates with confinement degradation in ELMy H-mode plasmas during a slow density ramp. These internal measurements provide unique constraints toward developing physics understanding and validating models of the H-mode pedestal for future devices.

Microstructure evolution of spray deposited and as-cast 2195 Al-Li alloys during homogenization

In this paper, a comparative study on the spray deposited and as-cast 2195 alloy was carried out to reveal their microstructure evolutions and differences during the homogenization process. The dissolution of the secondary particles and the diffusion of solute were studied based on microstructure characterization and kinetics analysis. The precipitation behavior of Al3Zr dispersoids and its influence on recrystallization were investigated by using TEM and EBSD characterization. It was found that the large-size particles at triangular grain boundaries dissolve slower than the intragranular phases and other grain boundary phases. The required homogenization time depends on the dissolution processes of the large-size phases at grain boundaries. The size of grain boundary phases in the spray deposited alloy is much smaller than that in the as-cast alloy, so the homogenization time required for the spray deposited alloy is significantly shorter. Two-stage and ramp heating homogenization processes can promote the precipitation of Al3Zr dispersoids in the two alloys. In the spray deposited alloy, the dispersoids tend to precipitate at the positions of the T1 plates dissolved, which causes a non-uniform distribution and decreases the recrystallization resistance of the alloy. However, the distribution of the dispersoids in the as-cast alloy is more uniform after the homogenization, which brings a stronger inhibition on the recrystallization. According to the microstructural characterization and kinetics analysis results, it can be concluded that the homogenization with a slow ramp heating is suitable for the two 2195 alloys, and a shorter holding time can be used for spray deposited alloy, e.g. 12 h at 500 °C, while the holding time for the as-cast alloy is no less than 35 h at 500 °C.

Dynamic Modelling and Simulation of Coal Pulverizer

The mathematical model and simulation of coal pulverizer has been presented in the paper using first principle mass and heat balance equations based on physical insight. The coal mass flow is modelled based on the mass balance model. The pulverized coal temperature is modelled by considering the coal and the pulverized coal as a lumped thermal mass. The multi variable non-linear model is simulated in Python environment and the parameters are obtained by using the moving horizon estimation. The archived data from an operating 660 MW coal fired boiler database are used to identify the parameters and to be compared with the model outputs. As the megawatt power output of thermal power generating plant is directly influenced by the coal being fired into the boiler, it is necessary to study the dynamic behaviour of the model as their poor dynamic performance causes a slow megawatt ramp up or ramp down rate and also causes shutdown of plant in some cases. In view of more and more penetration of renewable energy in the power grid, rapid and automatic flexible operation of coal fired boiler is necessary to accommodate injection of renewable power or withdrawal of renewable power as both remain connected directly or indirectly to the same power grid. Hence, fast response of the steam generating boiler is desired in a coal fired thermal power generating unit to generate the megawatt load as per the demand placed on the grid to maintain the power system frequency which calls for support of boiler steam flow, pressure and temperature to the steam turbine generator equipment. In order to achieve that, performance of combustion control of the boiler is one of the important factors which can be improved by modelling and implementing the predictive dynamic behaviour of coal pulverizer under varying coal feed rate in the boiler control system. The main focus of the work is to determine the pulverizer response under varying coal flow and coal characteristic condition with an objective of keeping minimum differential pressure across it based on a realistic mathematical model of pulverizer so that the boiler response can be improved under transient condition of megawatt load demand variation. The simulated model responses for various scenarios are also presented in this paper.

VALIDATION OF THE FEMAXI/SIMMER COUPLING BY USING THE E9 CABRI-2 EXPERIMENT

Accidents prevention and mitigation of the related consequences are mandatory for the safety assessment of the Generation IV Sodium-cooled Fast Reactors (SFRs). In order to reach these goals, the accurate evaluation of the most challenging transients, which may lead to severe accidents, is fundamental. In particular, an accurate evaluation of the degradation of the thermo-mechanical properties of the fuel pins due to irradiation, affecting the course of accidental transient conditions, is necessary. In our studies, the reference calculation route for the analysis of a severe accident in SFRs is based on the sequential use of the SAS-SFR and the SIMMER-III/IV mechanistic codes for the initiation (up to hexcan failure of a fuel sub-assembly) and the late (with core melting) phases of the scenario, respectively. Nevertheless, the module devoted to the SAS-SFR/SIMMER data transfer shows some limitations when innovative pins and core designs are considered. Having this in mind, the present paper proposes an innovative approach based on the coupling of a fuel performance code FEMAXI and the SIMMER code. When applied to severe accident studies of new reactors designs, such an approach is expected to improve the consistency of the SIMMER results as well as to extend its range of application. The FEMAXI/SIMMER coupling is described in the paper. Further, the results of the code validation against the CABRI-2 E9 experimental test, performed at the CABRI reactor using an OPHELIE-6 annular fuel pin irradiated in the PHENIX reactor, are shown and discussed. In the E9 test, a slow power ramp non-failure transient, corresponding to control rod withdrawal conditions, was investigated. New FEMAXI/SIMMER results are compared also to stand-alone SAS-SFR and SIMMER evaluations.

L-mode plasmas analyses and current ramp-up predictions for a JT-60SA hybrid scenario

In this work, L-mode analyses are performed in order to assess a modeling framework for the prediction of electron cyclotron resonant heating (ECRH) -assisted current ramp-up phases for JT-60SA tokamak hybrid scenario #4-2. We compare two turbulence transport models, CDBM and TGLF, using the integrated modeling code CRONOS. Model validation is performed on the basis of an L-mode ramp-up phase in a JET plasma, and a flat-top L-mode TCV (Tokamak a configuration variable) plasma with applied ECRH. Parameter scans in and in-edge electron temperature (T e ) are performed. Our results indicate effective prediction of the q profile in JET ramp-up if edge T e is properly captured. Indeed, our sensitivity scan demonstrates the strong impact of edge T e on q profile evolution. The results of CDBM and TGLF modeling show good agreement with the experimental measurements. With respect to a JT-60SA hybrid scenario, a significant amount of ECRH off-axis is required to maintain a q profile above unity across the entire plasma radius. Based on an analysis of power deposition location, we find that ECRH applied close to ρ = 0.33 allows a compromise between a q profile larger than unity, and high central T e . We evaluate two current ramp-up rates, where the fast rate is double that of the slower rate. The quantity of ECRH required for the fast ramp scenario is found to be greater by almost a factor of two than that required in the slow ramp scenario.

Investigation of lyophilized formulation susceptible to the ramp rate of shelf temperature in the primary drying process

In a series of our studies, we revealed that the ramp rate of shelf temperature in the primary drying process affects final product quality in an aggressive cycle (macroscopic collapse occurs at the slow ramp rate whereas acceptable lyophilized cake appearance is observed at the fast ramp rate). However, the studies were performed by disaccharide-based formulations, and whether the other formulations are susceptible to the ramp rate remained unclear. In the present study, the aqueous solutions of a representative bulking agent (mannitol, glycine, dextran, sucrose, trehalose and lactose) and protein model formulation with different levels of bovine serum albumin were lyophilized at different ramp rates. Macroscopic collapse occurred at the slow ramp cycle in a high concentration of disaccharide solutions, which have a low collapse temperature (Tc), and slow ramp-induced collapse was inhibited as the concentration was decreased. Also, drying failure in the slow ramp cycle was not confirmed in mannitol, glycine and dextran formulations. Furthermore, the slow ramp-induced collapse was inhibited as the concentration of the protein was increased. Thus, the amorphous-based formulation with low Tc containing a large amount of bulking agent was considered to be the formulation susceptible to the ramp rate.