Random Function Method Research Articles

A waste heat exchanger fly ash particle deposition model with dynamic mesh and random function method

The fly ash particle deposition in the heat recovery process of the heat exchanger is an urgent issue that must be addressed. In this work, the particle deposition model is improved using the dynamic mesh technology and random function method. We simulated and predicted the fouling morphology and particle size distribution of the fly ash layer using the deposition characteristics of particles of various sizes. The results indicated that when dynamic mesh technology is adopted, the tube wall's boundary will be deformed geometrically with the deposition of particles, allowing the changes in the fouling morphology to be expressed more effectively. Under this study conditions, the particle deposition mass on the windward and leeward sides of the tube increased initially and then decreased with the particle size increased. When particles of different sizes are mixed, the first layer of particles accelerates the deposition of subsequent particles, and the first layer of particles is generally composed of particles of small size.

Establishment and clinical validation of an artificial intelligence YOLOv51 model for the detection of precancerous lesions and superficial esophageal cancer in endoscopic procedure

Objective: To construct the diagnostic model of superficial esophageal squamous cell carcinoma (ESCC) and precancerous lesions in endoscopic images based on the YOLOv5l model by using deep learning method of artificial intelligence to improve the diagnosis of early ESCC and precancerous lesions under endoscopy. Methods: 13, 009 endoscopic esophageal images of white light imaging (WLI), narrow band imaging (NBI) and lugol chromoendoscopy (LCE) were collected from June 2019 to July 2021 from 1, 126 patients at the Cancer Hospital, Chinese Academy of Medical Sciences, including low-grade intraepithelial neoplasia, high-grade intraepithelial neoplasia, ESCC limited to the mucosal layer, benign esophageal lesions and normal esophagus. By computerized random function method, the images were divided into a training set (11, 547 images from 1, 025 patients) and a validation set (1, 462 images from 101 patients). The YOLOv5l model was trained and constructed with the training set, and the model was validated with the validation set, while the validation set was diagnosed by two senior and two junior endoscopists, respectively, to compare the diagnostic results of YOLOv5l model and those of the endoscopists. Results: In the validation set, the accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the YOLOv5l model in diagnosing early ESCC and precancerous lesions in the WLI, NBI and LCE modes were 96.9%, 87.9%, 98.3%, 88.8%, 98.1%, and 98.6%, 89.3%, 99.5%, 94.4%, 98.2%, and 93.0%, 77.5%, 98.0%, 92.6%, 93.1%, respectively. The accuracy in the NBI model was higher than that in the WLI model (P<0.05) and lower than that in the LCE model (P<0.05). The diagnostic accuracies of YOLOv5l model in the WLI, NBI and LCE modes for the early ESCC and precancerous lesions were similar to those of the 2 senior endoscopists (96.9%, 98.8%, 94.3%, and 97.5%, 99.6%, 91.9%, respectively; P>0.05), but significantly higher than those of the 2 junior endoscopists (84.7%, 92.9%, 81.6% and 88.3%, 91.9%, 81.2%, respectively; P<0.05). Conclusion: The constructed YOLOv5l model has high accuracy in diagnosing early ESCC and precancerous lesions in endoscopic WLI, NBI and LCE modes, which can assist junior endoscopists to improve diagnosis and reduce missed diagnoses.

A Waste Heat Exchanger Fly Ash Particle Deposition Model with Dynamic Mesh and Random Function Method

A Waste Heat Exchanger Fly Ash Particle Deposition Model with Dynamic Mesh and Random Function Method

A Waste Heat Exchanger Fly Ash Particle Deposition Model with Dynamic Mesh and Random Function Method

A Waste Heat Exchanger Fly Ash Particle Deposition Model with Dynamic Mesh and Random Function Method

Efficacy and Safety Analysis of Mini-incision Degreasing and Minimally Invasive Double Eyelid Surgery with Partial Thread Embedding in the Treatment of Patients with Asymmetric Double Eyelid

Objective: To analyze the effect of mini-incision degreasing and minimally invasive double eyelid surgery with partial thread embedding in the treatment of patients with asymmetric double eyelid. Methods: A total of 122 patients with asymmetric double eyelid treated in our hospital from February 2020 to February 2021 were selected as the research objects, and divided into a study group and a control group according to the Excel random function method, with 61 cases in each group. The control group received traditional blepharoplasty by incision method, and the study group received mini-incision degreasing and minimally invasive double eyelid surgery with partial thread embedding. The surgical indicators (operation time, postoperative healing time, intraoperative blood loss), complications and aesthetic satisfaction were statistically compared between the two groups. Results: The postoperative healing time of the study group was shorter than that of the control group, and the intraoperative blood loss was less than that of the control group (P<0.05). The aesthetic satisfaction of the research group was 98.36% higher than that of the control group 86.89% (P<0.05). Conclusion: Mini-incision degreasing and minimally invasive double eyelid surgery with partial thread embedding in the treatment of patients with asymmetric double eyelid can improve the healing time and intraoperative blood loss, improve aesthetic satisfaction, and reduce the incidence of complications.

Stochastic dynamic response and seismic reliability analysis of nuclear power plant’s vertical retaining wall based on plastic failure

Vertical retaining wall is usually built at the water intake in front of the pump station and is widely used in the protection of intake and voidance structures of nuclear power plants (NPPs). It has great practical significance for disaster prevention to gauge the plastic failure of vertical retaining wall accurately. In this paper, a generalized plastic model is introduced to obtain the residual deformation of vertical retaining wall during earthquake and the numerical simulation results based on plastic model reflect the plastic failure mode of the vertical retaining wall, which is consistent with the shaking table test results. In addition, the seismic excitation has great uncertainty, and in order to reflect the uncertainty, a set of fully nonstationary stochastic seismic loading samples are generated with spectral representation random function method. As a recently developed dynamic reliability methodology, the probability density evolution method (PDEM) is incorporated to the generalized plastic model to perform stochastic seismic response analysis of a vertical retaining wall. Plentiful probabilistic results of vertical retaining wall, such as evolution of probability density functions (PDF) and second-order statistics are acquired in this study. Finally, the dynamic reliability of vertical retaining wall under two earthquake levels are obtained based on the dip angle, which can more directly reflect the failure probability and degree of vertical retaining wall. The results of this study indicate that the geotechnical structures can show a more objective failure mode under earthquakes based on the plastic model, and it is more reliable to evaluate the safety of structures from the perspective of probability combined with PDEM.

Simulation of particle deposition in a plate-fin heat exchanger using a particle deposition model with a random function method

The particle deposition characteristics of plate-fin heat exchangers were studied using a particle deposition model with a random function method. The effects of the inlet velocity, particle size, and temperature difference on particle deposition and the distribution of the particles deposited in plate-fin heat exchangers were investigated. The simulation results showed that the thermal diffusion–induced motion of small particles was obvious at low velocities, the deposition of large particles was mainly limited by the critical velocity, there was a maximum deposition velocity in particle deposition and the maximum deposition velocity decreases with increasing particle size. Finally, large particles would rebound and deposit after secondary impacts. The temperature difference will increase the average deposition efficiency of 1 μm particles, and reduce the average deposition efficiency of 7 μm particles. The plate-fin heat exchanger should be designed with consideration for the particle size range and velocity seen in the intended application.

Improvement of particle deposition model using random function method

Particles in the environment not only threaten people's health, but the adhesion of particles on the equipment also threatens the safe operation of the equipment and the adhesion of particles in the heat exchange field also causes a large amount of energy waste. In this paper, the transportation and deposition processes of particles with different particle sizes were studied by numerical simulation. A random function method is introduced to improve the particle deposition model in order to consider the different characteristics between clean and fouled surfaces. As an example, the particle deposition characteristics of a two-dimensional channel were simulated using the clean surface model, fouling layer model, and random function method. The results show that as the particle size and inlet velocity increase, the gap between the three models increase. In particular, in the simulation of mixed particle size, the random function method better simulates the change in deposition rate during formation of fouling layer and the composition of fouling layer. Furthermore, the growth of the fouling was accelerated by the first layer of sediments, and the first layer of the sediments usually consisted of small particles.

How to Generate the Examination Paper: A Novel Hierarchical Backtracking-Based Algorithm

The random function method, genetic algorithm, and backtracking search algorithmare widely used to generate paper. However, typical paper-generating algorithms are inefficient to the point that they cannot ensure generate high-quality paper . In this study, we focus on this problem and devise a novel hierarchical backtracking paper-generational gorithm (HBPA). The HBPA optimizes the traditional paper-generating algorithm by using a hierarchical structure for pruning to solve the problems of ineffectiveness and inefficiency in the paper generation process.In addition, to measure the efficiency of the algorithm, an algorithm analytical model is established. Evaluation results reveal the effectiveness of the algorithm’s execution, whereby the quality of paper generation improves significantly.In addition, the number of test questions is increased.

Multi-scale stochastic damage model for concrete and its application to RC shear wall structure

PurposeThis paper aims to present a multi-scale stochastic damage model (SDM) for concrete and apply it to the stochastic response analysis of reinforced concrete shear wall structures.Design/methodology/approachThe proposed SDM is constructed at two scales, i.e. the macro-scale and the micro-scale. The general framework of the SDM is established on the basis of the continuum damage mechanics (CDM) at the macro-scale, whereas the detailed damage evolution is determined through a parallel fiber buddle model at the micro-scale. The parallel buddle model is made up of micro-elements with stochastic fracture strains, and a one-dimensional random field is assumed for the fracture strain distribution. To represent the random field, a random functional method is adopted to quantify the stochastic damage evolution process with only two variables; thus, the numerical efficiency is greatly enhanced. Meanwhile, the probability density evolution method (PDEM) is introduced for the structural stochastic response analysis.FindingsBy combing the SDM and PDEM, the probabilistic analysis of a shear wall structure is performed. The mean value, standard deviation and the probability density function of the shear wall responses, e.g., shear capacity, accumulated energy consumption and damage evolution, are obtained.Originality/valueIt is noted that the proposed method can reflect the influences of randomness from material level to structural level, and is efficient for stochastic response determination of shear wall structures.

Stochastic seismic response and stability reliability analysis of a vertical retaining wall in front of the pumping station of a nuclear power plant using the probability density evolution method

Vertical retaining walls are widely used to protect the water intake and drainage structures of nuclear power plants (NPPs); in particular, they are built as the inlet in front of the pumping station pool. It is of great significance to investigate the seismic behavior of the vertical retaining walls considering the uncertain nature of earthquakes according to the nuclear safety design requirements. The probability density evolution method (PDEM), which is a new and efficient methodology, is proposed here to study the stochastic seismic response and stability reliability of a vertical retaining wall in front of the pumping station pool of a NPP. Firstly, a set of representative acceleration time histories of non-stationary earthquake ground motions are generated by the spectral representation random function method according to the RG1.60 spectra for the NPP project design. Then, a series of deterministic stochastic seismic response analysis of a 26-m-high vertical retaining wall are performed. Finally, the probability information and seismic reliability of the vertical retaining wall under two seismic levels (SL-1 (operating-basis earthquake) and SL-2 (safety shutdown earthquake)) are obtained based on two physical parameters: the anti-sliding safety factor and anti-overturning safety factor. The results demonstrate that the proposed method of investigating the stochastic responses and seismic reliability of vertical retaining walls can provide more objective indices to evaluate the seismic safety during SL-1 and SL-2 seismic events. Furthermore, the proposed method can effectively investigate the ultimate seismic capacity of vertical retaining walls and other geo-structures in NPPs.

Application of rapid rehabilitation nursing in perioperative nursing of patients with laparoscopic hiatal hernia

Objective To explore the clinical effect of rapid rehabilitation in the perioperative nursing of patients who received total laparoscopic hiatal hernia repair and analyze specific methods and practice. Methods Totally 236 patients who received total laparoscopic hiatal hernia repair between June 2012 and June 2016 were selected by purposive sampling method and were divided into the control group and the intervention group by using the random function method, with 118 patients in each group. Patients in the control group received routine nursing, while patients in the intervention group received nursing based on the concept of rapid rehabilitation, namely, health education related to diseases and operations before operation, reduction of in-dwelling urethral catheter, temperature and humidity control, infusion warming, warmth retention of human body and infusion volume control during operation as well as early ambulation, early removing of stomach tubes, preventive use of thrombus therapeutic instrument and other nursing measures for rapid rehabilitation after operation. The differences in time of early ambulation, time of anal exhaust, time of first feeding, postoperative morbidity, hospitalization time and hospitalization expenses between two groups were compared. Results The proportion of ambulation within 24 hours after surgery in the intervention group was 93.22%, which was higher than that in the control group (40.68%) (χ2=73.611, P<0.01) ; the time of removing stomach tubes, anal exhaust and first feeding were [ (19.5±4.70) , (21.9±2.2) , (23.6±3.1) ] hours in the intervention group, and they were shorter than those in the control group [ (26.8±3.6) , (26.5±1.8) , (28.9±4.3) ] hours (t=13.394, 17.579, 10.861; P<0.01) ; the incidence rate of postoperative complications in the intervention group was 2.54%, which was lower than that in the control group (18.64%) (χ2=16.151, P<0.05) ; in the intervention group, the postoperative hospitalization time and expenses were (5.6±2.1) days and (28 772.9±1890.1) yuan, and they were lower than those in the control group [ (7.8±1.8) days, (30 011.7±2113.4) yuan] (t=8.640, 4.746; P<0.01) . Conclusions The application of rapid rehabilitation in the perioperative nursing of patients with hiatal hernia repair enables patients to ambulate earlier, reduce the incidence of postoperative complications and accelerate the recovery of intestinal functions after operation. Key words: Perioperative nursing; Laparoscope; Hernia, esophageal hiatus; Rapid rehabilitation nursing

Coupled deformation, filtration, and heat-conduction processes in media with disoriented quasi-spheroidal pores

Using the random function method we determine the effective thermoelastic properties of a saturated porous medium with disoriented quasi-spheroidal pores. On the basis of the functional dependence obtained for the parameters averaged over the macrovolume and phases we construct the equations of coupled deformation, filtration, and heat-conduction processes in a saturated porous medium. Bibliography: 8 titles.