Application and testing of a vertical angle control for a boom-type road header

Automatic profiling control using a boom-type roadheader requires an understanding of horizontal and vertical swing angles of the cutting boom. In this study the vertical angle of the cutting boom is discussed. First, a vertical swing detection model for the cutting boom is established. Then, a kinematic analysis of the vertical swing mechanism is made and formulae describing the geometrical relationship between the vertical swing of the cutting boom and the telescopic length of vertical hydraulic lift cylinders and vertical swing angle of the boom are presented. Various factors such as complexity of the calculation model, the difficulty of installing the sensor and the cost are compared for two methods. Finally, directly measuring the vertical swing angle of the cutting boom with a tilt sensor is decided to be the more simple and effective method. The detection sensitivity and the vertical cutting error of a tilt sensor are studied. Vibration tests on an EBZ160 roadheader were performed in a coal mine. The characteristic vibration frequencies are analyzed. A design of a vibration isolation mount for the tilt sensor is presented. It makes the detection device work more reliably under conditions where vibration is present and lays a foundation for the implementation of an automatic roadhead cutter. A tilt sensor is installed on an EBZ160 and an EBZ200, and experiments have been done in a coal mine. The re- suits show that the experimental result is favorable and achieves the goal of automatic control of the vertical swing of the cutting boom.

A deep learning network for estimation of seismic local slopes

The local slopes contain rich information of the reflection geometry,which can be used to facilitate many subsequent procedures such as seismic velocities picking,normal move out correction,time-domain imaging and structural interpretation.Generally the slope estimation is achieved by manually picking or scanning the seismic profile along various slopes.We present here a deep learning-based technique to automatically estimate the local slope map from the seismic data.In the presented technique,three convolution layers are used to extract structural features in a local window and three fully connected layers serve as a classifier to predict the slope of the central point of the local window based on the extracted features.The deep learning network is trained using only synthetic seismic data,it can however accurately estimate local slopes within real seismic data.We examine its feasibility using simulated and real-seismic data.The estimated local slope maps demonstrate the succes sful performance of the synthetically-trained network.

Factors associated with gastric adenocarcinoma and dysplasia in patients with chronic gastritis:a population-based study

Objective： Gastric cancer （GC） is one of the leading causes of death in China and other Asian countries. Recently, gastric endoscopy has become the main approach for GC screening, but the identification of high-risk individuals remains a challenge in GC screening programs. Methods： There were 7,302 patients with chronic gastritis involved in this study. Endoscopic examinations were performed, and their demographic characteristics and lifestyle data were collected. Each possible associated factor of GC/premalignant and precursor lesions was evaluated by univariate and multivariate logistic regressions. Nomograms were used for visualization of those models, and receiver operating characteristic （ROC） curve analysis was used to present the predictive accuracy. Resu Its： We detected 8 （0.11% ） gastric adenocarcinomas, 17 （0.23 %） dysplasia cases, 14 （0.19%） hyperplasia cases, 52 （0.71%） intestinal metaplasia cases, 217 （2.97%） inflammatory lesions, 141 （1.93%） gastric ulcers, 10 （0.14%） atrophic gastritis cases, 1,365 （18.69%） erosive gastritis cases, and 5,957 （81.58%） superficial gastritis cases in 7,302 patients. The age （P〈0.001）, gender （P=0.086）, labor intensity （P=0.018） and leek food intake （P=0.143） were identified as independent predictive factors of GC/premalignant lesions possibility. The corresponding nomogram exhibited an area under the curve （AUC） [95% confidence interval （95% CI）] of 0.82 （0.74-0.89） for the modeling group and 0.80 （0.75-0.85） for the validation group. The age （P=0.002）, gender （P=0.024）, smoldng （P=0.002） and leek food intake （P=0.039） were independent predictive factors of precursor lesions possibility. The corresponding nomogram exhibited an AUC （95% CI） of 0.62 （0.60-0.65） for the modeling group and 0.61 （0.59-0.63） for the validation group. Conclusions： We identified several potential associated factors and provided a preclinical nomogram with the potential to predict the possibility of GC/premalignant and precursor lesions.

Automatic microseismic events detection using morphological multiscale top-hat transformation

The occurrence of microseismic is not random but is related to the physical properties of the underground medium.Due to the low intensity and the influence of noise,microseismic eventually lead to poor signal-to-noise ratio.We proposed a method for automatic detection of microseismic events by adoption of multiscale top-hat transformation.The method is based on the difference between the signal and noise in the multiscale top-hat transform section and achieves the detection on a specific section.The microseismic data are decomposed into different scales by multiscale morphology top-hat transformation firstly.Then the potential microseismic events could be detected by picking up the peak value in the multiscale top-hat section,and the characteristic profile obtains the start point with a specific threshold value.Finally,the synthetic data experiences demonstrate the advantages of this method under strong and weak noisy conditions,and the filed data example also shows its reliability and adaptability.

Cluster analysis of the domain of microseismic event attributes for fl oor water inrush warning in the working face

Differences are found in the attributes of microseismic events caused by coal seam rupture,underground structure activation,and groundwater movement in coal mine production.Based on these differences,accurate classification and analysis of microseismic events are important for the water inrush warning of the coal mine working facefloor.Cluster analysis,which classifies samples according to data similarity,has remarkable advantages in nonlinear classification.A water inrush early warning method for coal minefloors is proposed in this paper.First,the short time average over long time average(STA/LTA)method is used to identify effective events from continuous microseismic records to realize the identification of microseismic events in coal mines.Then,ten attributes of microseismic events are extracted,and cluster analysis is conducted in the attribute domain to realize unsupervised classification of microseismic events.Clustering results of synthetic andfield data demonstrate the effectiveness of the proposed method.The analysis offield data clustering results shows that thefirst kind of events with time change rules is of considerable importance to the early warning of water inrush from the coal mine working facefloor.

Numerical and theoretical investigations of the effect of the gangue-coal density ratio on the drawing mechanism in longwall top-coal caving

Discrete element calculations of the top-coal drawing process for diferent gangue-coal density ratios were conducted to investigate the efect of the gangue-coal density ratio on the drawing mechanism in longwall top-coal caving.The efects were analyzed for the drawing body,the top-coal boundary,and the recovery of top coal.The results show that for increasing density ratio,the initial drawing body on the goaf side is farther away from the drawing support and its width and volume gradually increase.The upper part of the sickle-shaped drawing body extends near the initial drawing body with increasing density ratio in the normal cycling stage,and the distance from the drawing body to the initial drawing body is its maximum width.The larger the density ratio,the smaller the height of the top coal above the goaf at the end of the initial drawing process.The height of the top-coal boundary decreases with increasing density ratio,until it reaches a limit.In a normal cycle,due to hysteretic development,the top-coal boundary moves toward the goaf until the density ratio is approximately 2.0,which is consistent with the physical experiment results.Finally,increasing the advance length of the working face is benefcial for increasing the overall recovery of top coal.

Occurrence of No.12 lymph node micrometastasis in gastric cancer and its effect on clinicopathological parameters and prognosis

Objective This study aimed to investigate the occurrence of No.12 lymph node micrometastasis in patients with gastric cancer and its relationship with clinicopathological parameters and prognosis.Methods A cohort of 160 gastric cancer patients who underwent gastrectomy and lymph node dissection were selected as the research subjects.The immunohistochemical method was used to detect the micrometastasis of No.12 lymph node sections with negative routine pathological detection.At the same time,the clinical data of patients were collected and followed up to analyze the clinical significance of No.12 lymph node micrometastasis.Results A total of 370 No.12 lymph nodes were detected in 160 surgical specimens.Among 160 patients,27 patients were found to be positive for No.12 lymph nodes during routine pathological examination,with a positive rate of 16.8%.A total of 308 lymph nodes from 133 patients with negative routine pathological examinations were stained by immunohistochemistry.A total of 17 lymph nodes from 10 patients were found to be positive.The results showed that 37 of the 160 patients had No.12 lymph node metastasis,and the positive rate was 23.1%,which was 6.3%higher than that of routine pathological examination.Logistic multivariate analyses showed that the depth of invasion,lymph node metastasis in other groups,and clinical stage were independent risk factors for No.12 lymph node metastasis.The average follow-up time was 79.3 months,and the overall median survival time was 47.9 months.The survival time of the No.12 lymph node-negative group was 67.3±2.5Âmonths,the median survival time was 73.2 months;the survival time of the No.12 lymph node-positive group was(28.4±5.4)months,and the median survival time was 31.3 months.The survival time of the No.12 lymph node-negative group was significantly longer than that of the positive group(χ^(2)=12.75,P=0.000).Conclusion No.12 lymph node micrometastasis is a signal affecting the prognosis of patients with gastric cancer.Standardized dissection of No.12 lymph nodes is recommended for patients with gastric cancer who can undergo radical resection.

Effect of rosuvastatin intensification therapy on blood lipid metabolism,adipocytokines and plaque stability after PCI in ACS patients

Objective: To explore the effect of rosuvastatin intensification therapy on blood lipid metabolism, adipocytokines and plaque stability after PCI in ACS patients. Methods: ACS patients who received PCI in the hospital between July 2015 and January 2017were reviewed and divided into the routine dose group (n=60) who received rosuvastatin routine dose therapy after PCI and the intensification therapy group (n=46) who received rosuvastatin intensification therapy after PCI. The differences in blood lipid metabolism, adipocytokines and plaque stability were compared between the two groups before and after treatment. Results: Before PCI, the differences in blood lipid metabolism, adipocytokines and plaque stability were not statistically significant between the two groups. 1 month after PCI, lipid metabolism indexes HDL-C and ApoA1 levels in peripheral blood of intensification therapy group were higher than those of routine dose group while LDL-C and ApoB levels were lower than those of routine dose group;adipocytokines APN and Leptin levels in serum were higher than those of routine dose group while Resistin level was lower than that of routine dose group;plaque stability-related indexes ICAM-1, MMP-1 and TIMP-1 levels were lower than those of routine dose group. Conclusion: Rosuvastatin intensification therapy after PCI could effectively regulate the lipid metabolism and increase the plaque stability in ACS patients.

Modifiable risk factors for esophageal cancer in endoscopic screening population:A modeling study

To the Editor:Esophageal cancer,one of the most common cancer types in China,with an estimated 346,633 new cases and 323,600 deaths in 2022,is becoming an increasingly serious clinical and public health problem.^([1])The successful promotion of the self-management strategy has indicated that lifestyle modifications can be valuable in the primary prevention of cancer development.Adopting a healthy lifestyle has become a novel strategy for primary prevention and risk reduction in high-risk areas.Previous epidemiological studies have identified several lifestyle-related risk factors for esophageal cancer,including smoking and diet.^([2])Each factor can typically explain a modest proportion of cancer risk.However,when combined,these known risk factors may substantially affect the risk of esophageal cancer.Nevertheless,some risk factors for esophageal cancer are non-modifiable,including age,low socioeconomic status,and family history.Whether and how these non-modifiable risk factors affect primary cancer prevention by intervening with modifiable risk factors remain unclear.