Outlet Volume Research Articles

Development and performance evaluation of a mini plastic crushing machine

Global plastic production has seen a significant surge owing to its versatile applications resulting in a large volume of plastic waste polluting the environment. However, the high cost and size of plastic crushers have hindered efficient plastic recycling efforts. This research focused on creating a cost-effective, portable plastic crusher tailored for local use. The machine comprises four main units: the feeding, grinding, power, and framework units. A 3D model was crafted using Solid Works software (2017 version 25), and essential components were constructed from mild steel. The feeder has a capacity of 837480 mm3, a 20 mm diameter shaft with a power rating of 2.078 kW, and an outlet volume of 748692 mm3. Performance tests using High-Density Polyethylene (HDPE), Low-Density Polyethylene (LDPE), Poly Vinyl Chloride (PVC), and Polyethylene Terephthalate (PET) indicated throughput capacities of 2.83, 2.71, 6.00, and 1.60 kg/h, respectively. The machine has efficiencies of 73.3%, 53.85%, 60%, and 50% for HDPE, LDPE, PVC, and PET, respectively. Notably, the portable plastic grinding machine excels in grinding HDPE, making it highly recommended for small and medium-sized enterprises. This innovation focused on bolstering plastic recycling efforts in localized contexts.

A constant pressure differential valve and its controlling characteristics for aero engine

No matter in traditional hydraulic mechanical or newly numerical controlling system, pressure differential valve (PDV) always plays an important role in main fuel oil system and thrust augmentation fuel system. A throughout study on PDV is required to gain a more precise control and effective design for aero engine. Therefore, this paper presents a PDV and establishes the mathematical model to analyze its working characteristics, which shows that PDV performance is greatly affected by return oil inlet orifice and spring stiffness. The simulation and experiment are carried out to analyze the effect of PDV performance on system outlet volume flow rate and their results agree well with a maximum error of approximately 5 %. According to the study, it is found that there is a maximum increase of 9.99 % in system volume flow rate with pump rotating velocity from 300 to 900 rpm, but a maximum decrease of 3.4 % with outlet load pressure from 0.5 to 1.6 MPa. In addition, calculated curve slope reduces with return oil inlet orifice number increase and spring stiffness decrease, which means that PDV shows a faster response to working condition change and a better dynamic characteristic in controlling process. It is excepted that the research can be helpful in a further understanding of aero engine controlling system and a meaningful instruction on system optimization as well as fuel efficiency improvement.

Numerical and experiment study on ventilation performance of the equipment compartment of Alpine high-speed train

Alpine High-Speed Train serves on the Lanzhou-Urumqi Line in northwest China, where the terrain is mainly the Gobi Desert. To adapt to this complex environment, the independent-air duct is mainly used for the electrical facilities inside the equipment compartment to prevent the spread of sand particles. This isolated air duct makes ventilation characteristics of the equipment susceptible to the external environment. For this reason, this work aims to clarify and investigate the ventilation characteristic of electrical facilities. A two-step simulation method using IDDES (Improved Delayed Detached Eddy Simulation) and a real-vehicle tracking test using the T-typed pitot tubes were conducted. In the simulation, it is found that the ventilation performance can be influenced by the location of the equipment compartment, facilities and the fan mounted inside. By comparing the results of the test and simulation, they share the same characteristic that the air outlet volume of the converter near the head car is being promoted while it near the tail car is being inhibited. The maximum deviation ratio between the test and simulation is 9%. Therefore, the measurement method in this study is relatively reliable.

EDEM and FLUENT Parameter Finding and Verification Study of Thickener Based on Genetic Neural Network

To improve the concentration performance of the concentrator in the iron ore beneficiation process for iron ore tailings, a coupled simulation analysis of the concentration process was conducted using the discrete element software EDEM (Engineering Discrete Element Method) and the finite element FLUENT software. The volume concentration at the bottom flow outlet of the concentrator was used as the evaluation index. The scraper rotation speed, feed rate, and feed concentration were considered as parameters. Response surface experiments were designed using the Box-Behnken module in Design Expert11 software, and numerical simulations were performed to obtain data. Based on the numerical simulation results, a prediction model was established using the backpropagation neural network (backpropagation neural network, BP-NN) and combined with the genetic algorithm (genetic algorithm, GA) for parameter optimization of the thickener’s concentration conditions. The results showed that with a scraper rotation speed of 9.7677 rpm, feed rate of 0.2037 m/s, and feed concentration of 6.5268%, the maximum outlet volume concentration reached approximately 62.00%. The predicted optimal working conditions were validated through physical tests and numerical simulations. The average outlet volume concentration in the physical tests was 60.712% (n = 10) (“n” is the number of experiments), with an error of only 2.077% compared to the predicted value. The middle outlet volume concentration in the numerical simulation experiments was 59.951% (n = 10), with an error of only 3.304% from the expected value. These results demonstrate the feasibility of using a genetic neural network for optimizing the EDEM–FLUENT simulation parameters of the thickener, providing valuable insights for the matching optimization of the thickener’s process parameters.

Study on the Selection of Single-Screw Steam Compressors in Industrial Steam Supply

Both direct and indirect heating compression methods were proposed to satisfy the requirement of industrial steam compression and supply. The compression process in a single-screw compressor was analyzed with the determination of different inlet and outlet boundary conditions. Considering the misalignment of meshing pairs caused by the offset of the star wheel axis and screw origin, the differential expansion of the vertical meshing pair was further analyzed. The inner ring of the sealing end face, the wall of the inner ring of the bearing at the inlet and outlet ends, and the bottom surface of the bracket were analyzed by different coordinate systems and different constraints, thus facilitating the design and selection of the single screw. The critical point for the design of a steam-type single-screw compressor is an outlet temperature of 350 °C and an outlet volume flow rate of 130 m3/min. At a flow rate of 130 m3/min, when the temperature exceeds 350 °C, the reliability of the compressor is still limited, and the differential expansion of the meshing pair exceeds 0.3 mm. In addition, superheating of steam can be improved by applying a centrifugal compressor with cascade compression and centrifugal compression in conjunction with reflux adjustment at the compression outlet.

Study of Evaporative Heat and Mass Transfer in Solar Distillation

In this work, the assessment of 3 experimental tests on a solar still is presented, where 4, 5 and 6 L of brine were utilized. Data of temperature in several parts of the device and of solar radiation were obtained, besides, the outlet volume water was measured every 5 minutes during a timelapse from 10:00 am to 18:00 pm, which is compared through a study of heat and mass transfer due to evaporation, with the aim of predicting de amount of distilled volume.Experimental results show that 2.7, 2.2 and 1.8 L are distilled for the initial volumes of 4, 5 and 6 L, respectively. However, when Dunkle’s thermal model is applied, the resulting distilled volumes are 2.2 2 and 1.7 L for the initial volumes of 4,5 and 6 L, respectively. This analysis indicates that the chosen thermal model has an error of approximately 4% compared with experiments. However, this model can be used to estimate accurately the outlet volume of distilled fluid.

Size reduction and enhanced power generation in ORC by vaporizing LNG at high supercritical pressure irrespective of delivery pressure

LNG regasification terminals generate power with Organic Rankine cycle (ORC) using LNG as the heat sink. A 3-stage ORC designed for regasification pressure of 70 bar(a) produces the highest net power with appropriate temperature approach in each heat exchanger and it is higher by 108 kW for LNG flow of 30 kg/s compared to the fixed temperature approach of 5 K. For 30 bar(a) delivery pressure, a regasification pressure of 70 bar(a) instead of 30 bar(a) produces about 17% higher net power and 1.9 times reduction of total heat exchanger area. The sizing parameter of the turbine becomes 12.3% lower. The analysis shows that total outlet volume flow rate through turbine, pump inlet and hot side of heat exchangers are 24.5%, 28.2% and 25.0% lower respectively for 70 bar(a) regasification pressure. The total capital investment for 30/30 bar(a) and 70/30 bar(a) systems are 18.8% and 21.8% respectively higher than that of 70/70 bar(a) system. For the delivery pressure of CNG at 30 bar(a), the net present value of 70 bar(a) regasification pressure is 1.7% higher than that for 30 bar(a) regasification pressure. This is over and above the flexibility of operation that the regasification terminal achieves with supercritical LNG.

The effect of biochar on the migration theory of nutrient ions

As the acidification of arable soils increases, the utilization of nutrient ions such as N, P, and K decreases substantially. It causes environmental pollution and reduces crop yields. Through previous studies, acidified soil amendments have problems such as easy-retrograde and unclear mechanism. Therefore, in this study, biochar prepared by pyrolysis using peanut shells was used as a green amendment for acidified soil. Biochar with 0, 5 and 10 % biochar ratios were applied to the acidified soil, and the improvement and mechanism were investigated via experiments and software simulations. Analysis of the software simulation results revealed that biochar had the highest unit adsorption of K+ through physical adsorption at 820.38 mg/g. This was followed by PO43−, NO3−, and NH4+ as 270.51, 235.65 and 130.93 mg/g, respectively. These ions were controlled by both electrostatic and ion-exchange adsorption processes. During the improvement, the 10 % biochar ratio group performed the best with a 65.32 % reduction in the outlet volume, and the accumulated levels of nutrient ions in the leachate dropped by 48.40–68.28 % and increased by 437.80–913.87 % in the surface soil. Nutrient ion levels decreased gradually with the increase of soil depth, which agreed with the software simulation results. This study found that applying biochar to acidified soils can provide a solution to low nutrient utilization efficiency and unclear improvement mechanism of acidified soils, and provide a partial theoretical basis for the large-scale application of biochar. Future research on biochar for soil carbon sink and microbial expansion can be strengthened to contribute to environmental protection and multi-level utilization of energy.

Fault Modeling and Simulation of Engine Driven Pump in Aircraft Hydraulic System

Abstract The structure of engine driven pump in aircraft hydraulic system is complex, its fault forms are diverse, and the fault transmission path is complex and multi factor coupling. In view of the above problems, based on the in-depth analysis of the working principle of the engine driven pump, the engine driven pump model is established, and the leakage fault injection mechanism of the friction pair is added. The relationship between the flow fluctuation characteristics of engine driven pump and the changes of pump spindle speed, swashplate inclination and pump outlet cavity volume are obtained through model simulation analysis. The mechanism of internal leakage fault of plunger pair, port pair and slipper pair are analyzed, the influence of leakage clearance parameters on key performance indexes such as pump pressure and flow are simulated, and the simulation test data of internal leakage fault of pump are obtained. The simulation results show that the inclination angle of swashplate and spindle speed are positively correlated with the output flow of the pump. The increase of pump outlet volume can effectively alleviate the pressure and flow fluctuation behind the pump. In addition, when the radial clearance of the plunger pair of this type of pump exceeds 0.2mm, the pump fault characteristics begin to appear. At the same time, the load change behind the pump will affect the characterization of the fault of internal leakage of the pump.

Carbon dioxide recovery from a simulated dry exhaust gas by an internally heated and cooled temperature swing adsorption packed with a typical hydrophobic adsorbent

• Internally heated / cooled temperature swing adsorption was tested for CO 2 capture. • Two typical hydrophobic adsorbents were employed for wet emission gas processing. • The separation performance of High Silica Zeolite was explored. • The unique separation behavior of Carbon Molecular Sieves was examined. This study focused on the carbon dioxide (CO 2 ) separation and recovery by an internally heated and cooled thermal swing adsorption process. As part of the preliminary investigation, the CO 2 capture and enrichment performance of carbon molecular sieve (CMS), a typical hydrophobic adsorbent, and high silica zeolite (HSZ), which indicates hydrophobic behavior among zeolites, were examined in a simulated dry exhaust gas. In addition, the hydroscopic adsorbent, CaA type zeolite, was employed for comparison. The effects of the regeneration temperature and the regeneration air flow rate on the separation performance were primarily investigated. In general, the CaA type of zeolite indicated a greater CO 2 concentration performance and recovery ratio due to its relatively larger adsorption capacity. Comparison between HSZ and CMS showed that the CO 2 separation and recovery performance of HSZ were greater than that of CMS. A CO 2 concentration four times higher than that of the feed gas was obtained at a regeneration temperature of 80 °C. Moreover, further enrichment of CO 2 at the desorption outlet was achieved by reducing the regeneration air flow rate to 1/40 of the feed gas of the adsorption process in exchange for lowering the CO 2 recovery ratio. In contrast, CMS could only produce three times greater the concentration of enriched CO 2 when compared to the feed gas. The enriched CO 2 concentration was almost independent of the regeneration air flow rate. This behavior was due to a lower CO 2 adsorption selectivity of CMS; this interpretation was supported by time profiles of desorption gas outlet volume and the CO 2 concentration.

Direct fluid–structure coupling analysis of reciprocating series seals in hydropneumatic suspension

The reciprocating piston seals are crucial parts in hydraulic system, which are widely used in aerospace and military industry. A direct fluid–structure coupling method with high efficiency is proposed for solving the transient Elaso-Hydrodynamic-Lubrication problem in float piston series seal system of hydropneumatic suspension. The method is validated by theory solution of a simple pad-bearing film model. Detailed three-dimensional fluid–structure coupling model of the seal system is built using finite element discretization. Rubber material tests are carried out to obtain parameters of the third-order Ogden constitutive model for the O-ring seal. The sealing performance and friction force of the complicated series seal system are analyzed with direct fluid–structure dynamic coupling simulation in high pressure and high speeds conditions. The critical speed from mixed lubrication to full film lubrication is obtained. The fluid velocity and pressure distribution in the sealing gap along axial direction is compared. The outlet volume flux leakage in different piston speeds and inlet pressures is calculated to evaluate the sealing performance. The friction force experiment for the float piston system is carried out in various speeds. The friction force from direct fluid–structure interface simulation coincides well with the test result.

Selection of working fluid for low enthalpy heat source Organic Rankine Cycle in Dholera, Gujarat, India

Organic Rankine Cycle (ORC) is a technique which can generate electricity by using low to medium enthalpy geothermal water. This paper narrates selection of working fluid which is the most important factor in designing of ORC. In this paper four fluids, R600, R600a, R134a and R245fa were chosen for screening. The screening is done with respect to hot water temperature at generator inlet side and pressure ratio condition. Analysis of working fluid in this paper is done for six parameters namely ORC efficiency, Volumetric Flow Ratio (VFR), Expander Size Parameter (SP), Total heat exchanger utilised area (UA), Network output and Turbine outlet volume flow rate. This analysis were done in order to select the suitable working fluid for ORC integrated with space heating and cooling plant at Dholera. This ORC uses the output water of 75–80 °C obtained from heating side of the space heating and cooling system. As the water temperature which is used in ORC is a low enthalpy it needed a working fluid which can increase the efficiency and exergy of ORC. After screening the results shows that R245fa is a suitable working fluid for ORC integrated with space heating and cooling plant in Dholera, Gujarat, India.

P2743Right ventricular size in repaired tetralogy of Fallot: correlations between transthoracic echocardiography and cardiovascular magnetic resonance

Abstract Introduction Right ventricular (RV) size informs about prognosis and need for pulmonary valve replacement in patients with repaired tetralogy of Fallot (rTOF). Cardiac magnetic resonance (CMR) is considered the reference standard for measurement of RV volumes. Despite known limitations for RV evaluation, 2D transthoracic echocardiography (TTE) remains the primary and most available imaging modality in the rTOF population. Purpose To determine which TTE RV size parameters best correlate with CMR-derived indexed RV end-diastolic (RVEDVi) and end-systolic (RVESVi) volumes in the rTOF population. We sought to determine the best TTE measurement thresholds to predict normal RV volume (RVEDVi ≤110 mL/m2) and significant RV dilatation by CMR (RVEDVi ≥150ml/m2). Method We retrospectively enrolled all rTOF patients followed at a single-center between 2010 and 2018 who had both TTE and CMR exams performed within a 12-month interval. All TTE exams were reviewed by an observer measuring RV areas, RV inlet and RV outlet at end-diastole and end-systole. Analyses of CMR studies were performed by 3 observers who measured RV area, RV inlet, RV outlet and RV volumes at end-diastole and end-systole. Correlations between TTE and CMR parameters were performed using Pearson correlation coefficients. Using the TTE RV parameters with the strongest correlation with CMR, we subsequently determined thresholds to predict a CMR RVEDVi ≤110ml/m2 and ≥150ml/m2 using ROC analysis. Results We enrolled 130 patients (59 women [45%], mean age 43±12.8 years). Median age at TOF repair was 4 [3–6] years; 18 patients (14%) had subsequent pulmonary valve replacement. Median interval between TTE and CMR exams was 114 [59–239] days. There were significant correlations between all TTE parameters and CMR RVEDVi. TTE indexed RV end-diastolic area (RVEDAi) most strongly correlated with CMR RVEDVi (r=0.73, p<0.0001). All TTE RV parameters significantly correlated with CMR RVESVi but indexed RV end-systolic area had the strongest correlation (r=0.77, p<0.0001). ROC analysis performed to predict RVEDVi of ≤110ml/m2 and ≥150ml/m2 using TTE RVEDAi revealed areas under the curve of 0.86±0.04 and 0.90±0.03, respectively. A TTE RVEDAi ≤17cm2/m2 predicted a normal CMR RV volume (≤110ml/m2) with a sensitivity of 90% and a specificity of 74%. A TTE RVEDAi ≥19cm2/m2 predicted a CMR RVEDVi ≥150 mL/m2 with a sensitivity of 93% and a specificity of 76%. Conclusion In rTOF patients, both diastolic and systolic TTE RV area best correlate with CMR-derived RV end-diastolic and end-systolic volumes. A cut-off value of TTE RVEDAi of 19cm2/m2 is 93% sensitive and 76% specific to predict a CMR RVEDVi ≥150ml/m2. Simple RV size measurement using TTE may help inform the need and frequency of CMR evaluations in rTOF patients.

A finite outlet volume correction to the time lag method: The case of hydrogen permeation through V-alloy and Pd membranes

The time-lag method is a technique to derive the permeability of a membrane from the time-variant outflux of a permeate. The original formulation assumes an invariant outlet pressure; however, for practical reasons, the permeate is often contained in a finite outlet volume, and the outflux is evaluated using the increase in the outlet pressure. The outlet pressure change inevitably introduces an error in the diffusivity and in the solubility, i.e., Sieverts' constant. We demonstrate that when a time lag is obtained from the tangent line at the maximum flux, the error in the diffusivity stays within ca. 2% under usual experimental conditions. On the other hand, Sieverts' constant is underestimated to a larger degree if the outlet pressure change is not considered. To solve this problem, we propose a finite outlet volume correction to the time-lag method for the case of hydrogen permeation. The proposed scheme is an approximate solution that is valid when a linear hydrogen concentration profile is developed across the membrane. When the correction method is applied to characterize V-alloy and Pd membranes, the simulated outlet pressure from the corrected Sieverts’ constant closely approximates the experimental data. The proposed method does not require any additional measurements and greatly improves the accuracy of the permeability measurement.

Thermo-economic evaluation of an innovative direct steam generation solar power system using screw expanders in a tandem configuration

Tandem screw expander (SE) technology is a promising solution for large volume ratio situations. Tandem SE driven direct steam generation (DSG) system is first proposed for distributed solar thermal power generation. Steam accumulator is adopted for storage due to its moderate heat source temperature. Compared with the cascade steam-organic Rankine cycle (SORC) system, the novel tandem system has simpler structure, easier control strategy and lower technical requirements, less operating and maintenance fees, more stable power output and higher security. Thermodynamic analysis and economic evaluation of the novel system are conducted based on some parameters of a recently constructed tandem SE project. Steam Rankine cycle (SRC) efficiency of 18.49% is achieved by employing built-in volume ratio (rv,b) of 3 for the high-pressure SE (SE1) and rv,b of 7 for the low-pressure SE (SE2). The cost-effectiveness of the system is improved as the power capacity and heat storage time increase. Levelized electricity cost (LEC) of 0.118 $/kWh and payback period (PP) of 10.48 years are obtained for 1 MW tandem plant with 6.5 h heat storage. The cost of parabolic trough collectors accounts for nearly half of the total investment while the accumulators occupy less than 7%. The cost of SE2 is approximately seven times that of SE1 due to the larger design outlet volume flow rate and rotor diameter.

A review on silent sinus syndrome

Silent sinus syndrome (SSS) is a rare condition that causes facial asymmetry, unilateral painless enophthalmos, orbital floor collapse, and diplopia, which represent the chronic maxillary sinus atelectasis with chronic negative pressure within the sinus. SSS is also known as imploding antrum. Some believe that congenital development of the maxillary sinus may also be responsible for the development of SSS. Its characteristic imaging features are maxillary sinus outlet obstruction, sinus opacification, and volume loss caused by inward retraction of the sinus wall. Ostium obstruction appears to play a critical role in the development of SSS. Treatment involves reconstructive procedure of orbital floor and functional endoscopic sinus surgery.

Discrete event based hybrid framework for petroleum products pipeline activities classification

The importance of timely detection, classification and response to anomalies on petroleum products pipeline (PPP) have attracted pragmatic researches in recent times. There is need for efficient monitoring and detection of activities on PPP to guide leak detections and remedy decisions. This paper develops an intelligent hybrid system, driven by discrete event system specification (DEVS) and adaptive neuro-fuzzy inference system (ANFIS) for detection and classification of activities on PPP. A dataset comprising 330 records was used for training, validation and testing of the system. Result of sensitivity test shows that inlet pressure, inlet temperature, inlet volume and outlet volume have cumulative significance of 71.72% on flowrate of PPP. Hybrid learning algorithm was observed to converge faster than the back propagation algorithm in the detection of pipeline activities. ANFIS hybrid learning algorithm with training and testing errors of 0.11980 and 0.010233 yielded a correlation of 0.916 between the computed and the desired output and produced optimal consequent parameters to boost the intelligence of DEVS. A testing error of 0.0303 was observed in the evaluation of DEVS-ANFIS system on 33 test data sample, 32 precise detections were made with one incorrect detection, this gives 96.97% level of confidence in the DEVS-ANFIS model for detection, classification and localization of PPP activities.

Comparative Analysis of Neural Network Models for Petroleum Products Pipeline Monitoring

In recent years, Neural Network (NN) has gained popularity in proffering solution to complex nonlinear problems. Monitoring of variations in Petroleum Products Pipeline (PPP) attributes (flow rate, pressure, temperature, viscosity, density, inlet and outlet volume) which changes with time is complex due to existence of non linear interaction amongst the attributes. The existing works on PPP monitoring are limited by lack of capabilities for pattern recognition and learning from previous data. In this paper, NN models with pattern recognition and learning capabilities are compared with a view of selecting the best model for monitoring PPP. Data was collected from Pipelines and Products Marketing Company (PPMC), Port Harcourt, Nigeria. The data was used for NN training, validation and testing with different NN models such as Multilayer Perceptron (MLP), Radial Basis Function (RBF), Generalized Feed Forward (GFF), Support Vector Machine (SVM), Time Delay Network (TDN) and Recurrent Neural Network (RNN). Neuro Solutions 6.0 was used as the front-end-engine for NN training, validation and testing while My Structured Query Language (MySQL) database served as the back-end-engine. Performance of NN models was measured using Mean Squared Error (MSE), Mean Absolute Error (MAE), Correlation Coefficient (r), Akaike Information Criteria (AIC) and Minimum Descriptive Length (MDL). MLP with one hidden layer and three processing elements performed better than other NN models in terms of MSE, MAE, AIC, MDL and r values between the computed and the desired output.

STUDY REGARDING THE IDENTIFICATION OF THE WATER POLLUTION SOURCES AND FACTORS ON THE SIRET RIVER IN THE BACAU-MARASESTI SPAN

The main pollution sources of the Siret river and its tributaries in the Bacau-Marasesti span are submitted in the present study. The Siret River, through the watershed it forms, is one of the largest tributaries of the Danube. Thereby Siret river through its water volume outlet for the Danube River, which crosses our country, is considered a major pollution agent for the surrounding areas of the river from a social, economical and agricultural point of view.

An improved model for through-diffusion experiments: application to strontium and tritiated water (HTO) diffusion in Boom Clay and compacted illite

Abstract Through-diffusion experiments are conventional experiments to measure the transport parameters of radionuclides in clays. Typically, a regular replacement of the outlet volume by a tracer-free volume is performed. In the classical approach, this type of through-diffusion experiment is modelled by assuming a zero concentration in the outlet volume. Nonetheless, this assumption is not always correct, usually because the outlet volume is insufficiently large or the time between two consecutive replacements of the outlet volume is too long. Therefore, a model was developed disregarding this assumption and, instead, considers the tracer concentration in the outlet volume to evolve, as in the experiments: the flux into the outlet volume increases the tracer concentration and, at each replacement, the tracer concentration in the outlet volume is set to zero. The model was used to reproduce the diffusion of strontium (Sr) and tritiated water (HTO) in illite and Boom Clay. Model results yielded good matches with the tracer evolution in the inlet and the outlet, and the tracer profile in the core at the end of the experiment.