Effects Of Firing Rate Research Articles

Experimental investigation of the effects of altitude on the performance of a non-sprayed porous burner

A self-sustained burner was built for diesel oil without an atomizer using metal fiber felt as an evaporator. The effects of firing rate, excess air coefficient, and altitude on the temperature distribution, NOx emission, and CO emission were studied. The results indicated that fuel evaporation and combustion inside the burner are significantly influenced by the altitude. The overall temperature distribution inside the burner first decreased and then increased with the increase in altitude. The main reasons for the formation of NOx are the local high temperature during start-up and the high temperature after flame stabilization. The NOx emission initially decreased and then increased with the increase in altitude. The NOx emission is the lowest at an altitude of 1700 m and reaches its maximum value at an altitude of 4780 m. The main cause of CO generation is incomplete combustion during the start-up process. The CO emission decreased with the increase in the excess air coefficient at the same altitude. Less CO is produced with the increase in altitude at the same firing rate and excess air coefficient.

Effect of Firing Rate on the Properties of Chamotte from Kyshtym Deposit Kaolin

Effect of Firing Rate on the Properties of Chamotte from Kyshtym Deposit Kaolin

Natural firing patterns reduce sensitivity of synaptic plasticity to spike-timing

Synaptic plasticity is sensitive to both the rate and the timing of preand postsynaptic spikes. In experimental protocols used to induce plasticity, the imposed spike trains are regular and the relative timing between every preand postsynaptic spike is fixed. This is at odds with natural firing patterns observed in the cortex of intact animals, where cells fire irregularly and the timing between preand post-synaptic spikes varies. To investigate synaptic changes elicited by in vivo-like irregularly firing neurons at different rates and realistic correlations between preand post-synaptic spikes, we use numerical simulations and mathematical analysis of synaptic plasticity models. We concentrate on a calcium-based model [1], and further consider a voltagebased model [2] and a spike-timing based model [3]. To allow for comparison, all models are fitted to plasticity results obtained in vitro [4]. We show that standard stimulation protocols overestimate the influence of spike-timing on synaptic plasticity. Using a simple modification of regular spike-pair protocols, we allow for neurons to fire irregularly. Such irregular spike-pairs reduce the amplitude of potentiation and depression obtained by varying the time difference between preand postsynaptic spikes. This protocol allows us to quantify the relative effects of firing rate and timing in natural firing patterns, and to predict changes induced by an arbitrary correlation function between preand post-synaptic spikes. We show that spike correlations change synaptic plasticity at low firing rates in all models; whereas their influence becomes negligible at high firing rates for the calcium-based model but remains significant for the other two models. Our findings yield predictions for novel experiments and help bridge the gap between existing results on synaptic plasticity and plasticity occurring under natural conditions.

An experimental study on the performance optimization of a radiant burner with a surface flame structure

An experimental study was carried out on a newly developed, gas-fired radiant burner to optimize its performance for three different conditions of firing rate (80.5, 107.4, and 134.2 kW/m2). The operational equivalence ratios ranged from 0.6 to 1.3. Gas temperatures along the mat and upstream/downstream of the ceramic mat were obtained to investigate the effects of firing rate and equivalence ratio. The temperature of the unburned mixture in the burner port decreased as the firing rate increased. The opposite trend appeared in response to change in the equivalence ratio. This was mainly due to mixture velocity and residence time. The mechanism of temperature variations in the mat with the equivalence ratio and firing rate was described in detail. Results on flue gas emissions, such as the concentrations of EINO and CO, were also presented. It was confirmed that in lean-mixture conditions, the concentration of CO remains below 100 ppm for all firing rates. Lastly, radiation and water-boiling efficiencies were measured as functions of the equivalence ratio, firing rate, cookware diameter (Dp), and height of the burner housing (H). It was observed that conduction heat transport dominated the radiation effect less as the firing rate increased. From these observations, the effective heat input in the present radiant burner was determined to optimize its performance.

Effect of firing rate on the performance of shock wave lithotriptors

To determine the mechanism that underlies the effect of shock wave (SW) rate on the performance of clinical lithotripters. The effect of firing rate on the pressure characteristics of SWs was assessed using a fibre-optic probe hydrophone (FOPH 500, RP Acoustics, Leutenbach, Germany). Shock waves were fired at slow (5-27 SW/min) and fast (100-120 SW/min) rates using a conventional high-pressure lithotriptor (DoLi-50, Dornier MedTech America, Inc., Kennesaw, GA, USA), and a new low-pressure lithotriptor (XX-ES, Xi Xin Medical Instruments Co. Ltd, Suzhou, PRC). A digital camcorder (HDR-HC3, Sony, Japan) was used to record cavitation fields, and an ultrafast multiframe high-speed camera (Imacon 200, DRS Data & Imaging Systems, Inc., Oakland, NJ, USA) was used to follow the evolution of bubbles throughout the cavitation cycle. Firing rate had little effect on the leading positive-pressure phase of the SWs with the DoLi lithotriptor. A slight reduction ( approximately 7%) of peak positive pressure (P+) was detected only in the very dense cavitation fields (approximately 1000 bubbles/cm(3)) generated at the fastest firing rate (120 SW/min) in nondegassed water. The negative pressure of the SWs, on the other hand, was dramatically affected by firing rate. At 120 SW/min the peak negative pressure was reduced by approximately 84%, the duration and area of the negative pressure component was reduced by approximately 80% and approximately 98%, respectively, and the energy density of negative pressure was reduced by >99%. Whereas cavitation bubbles proliferated at fast firing rates, HS-camera images showed the bubbles that persisted between SWs were very small (<10 microm). Similar results were obtained with the XX-ES lithotriptor but only after recognizing a rate-dependent charging artefact with that machine. Increasing the firing rate of a lithotriptor can dramatically reduce the negative pressure component of the SWs, while the positive pressure remains virtually unaffected. Cavitation increases as the firing rate is increased but as the bubbles collapse, they break into numerous microbubbles that, because of their very small size, do not pose a barrier to the leading positive pressure of the next SW. These findings begin to explain why stone breakage in SWL becomes less efficient as the firing rate is increased.

다공성 세라믹 매트를 이용한 복사버너에서의 연소라디칼 특성과 배기배출물에 관한 연구

An experimental study was performed to investigate the characteristics of chemiluminescence in a radiant burner, varying the excess air ratio from 0.91 to 1.67 at firing rate 80.5 to 134.2 ㎾/m2 on OH<SUP>*</SUP>, CH<SUP>*</SUP>, C₂<SUP>*</SUP> in LNG-Air premixed flames. The signals from electronically excited states of OH*, CH<SUP>*</SUP>, C₂<SUP>*</SUP> were detected using a Intensified Couple Charged Detector (ICCD) camera. The measurements of exhausted emission were made to investigate the correlation between chemiluminescence and emissions. The chemiluminescence intensity was increased with increase of firing rate like characteristics of NOx emission. NOx also increased with increase of firing rate and excess air ratio. It is found that effect of firing rate is more dominant excess air ratio NOx emission. The maximum chemiluminescence intensity occurs near the stoichiometric excess air ratio or lean conditions in case of high firing rate and the maximum intensity occurs rather than rich conditions in case of relatively low firing rate. Amount of NOx emission is maximum at near stoichiometric excess air ratio, which is chemiluminescence intensity is maximum.

SIMULATION OF GASEOUS COMBUSTION AND HEAT TRANSFER IN A VORTEX COMBUSTOR

This article presents the numerical simulation of gaseous combustion and heat transfer in a novel vortex combustor (VC) recently developed for commercial heating applications. A new algebraic Reynolds stress model for strongly swirling turbulence, the eddy break up model for turbulent combustion, and the four-heat-flux model for thermal radiation were employed in the present calculations. Different thermal boundary conditions were specified on the combustor walls. The calculations were conducted on a 22-cm ID VC firing gaseous fuel at 58-, 41-, and 38-kW thermal inputs. Detailed effects of firing rate on the gas axial and tangential velocities, streamlines, temperature, species mass concentrations and wall heat removal are presented, from which the distinct features of the VC flow, combustion, and heat transfer are delineated.

A few electroconvulsive shocks produce more reliable effects of firing rate in lateral septal neurons than repetitive treatment in the rat.

Electroconvulsive shock is a common treatment used in depression, especially in cases in which suicide constitutes a risk. The recommendation for its use varies from one place to another, but there is an empirical agreement to avoid daily treatment or several treatments on the same day. The present study explored the actions of electroconvulsive shock in lateral septal firing rate in rats. The first or second once-a-day electroconvulsive shock produced a maximal increase in firing rate; however, effects vanished as treatment was repeated. Three consecutive electroconvulsive shocks on the same day also produced fewer changes in firing rate than once-a-day treatment. These results are likely to be related to clinical recommendations to avoid serial-repetitive treatment, and suggest that some resting time is required in treatment to achieve long-lasting changes in neuronal activity.

Effect of firing rate on the calcium permeability in adult neurons during spontaneous action potentials.

Calcium channels in neurons mediate a wide variety of essential functions. In addition to contributing to action potential shape, they furnish a substrate that acts as an intracellular second messenger. This study shows that the shape of the neuronal action potential has characteristics that promote long openings of L-type (high threshold) calcium channels. We also present evidence that a change in the firing rate of isolated neurons modulates gating of single calcium channels. This mechanism could be important in modulating neuron excitability and providing a rise in intracellular Ca, when needed.

The effect of firing rate on preoptic neuronal thermosensitivity.

1. In anaesthetized rabbits, preoptic single units were recorded having positive or negative thermal coefficients (impulses/sec. degrees C) for changes in preoptic temperature.2. A population of forty-two positive coefficient units was divided into four groups based on their level of firing rate at 38 degrees C. In each group, the average thermoresponse curve was determined by averaging the firing rates of the units at 1 degrees C intervals over the 33-43 degrees C range of preoptic temperatures.3. A population of twenty-six negative coefficient units was divided into three groups based on their firing rates at 38 degrees C. Similar average thermoresponse curves were determined for each group.4. As the level of firing rate increased in the positive coefficient units, the preoptic thermosensitivity progressively decreased at temperatures above 39 degrees C, but generally increased at temperatures below 39 degrees C.5. In the negative coefficient units, preoptic thermosensitivity generally increased (especially above 39 degrees C) as the firing rate at 38 degrees C increased.6. The results indicate that in positive coefficient units the level of firing rate determines the temperature range in which units are most thermosensitive. This range reflects whether a neurone is more likely to function in heat-loss or heat-production responses.7. Since peripheral thermal input affects the level of firing rate of positive coefficient units, a neuronal model is suggested to explain the role of peripheral and central thermal signals in temperature regulation.