Centrifuge modeling of unreinforced and multi-row stabilizing piles reinforced landslides subjected to reservoir water level fluctuation

With the construction of the Three Gorges Reservoir dam,frequent reservoir landslide events have been recorded.In recent years,multi-row stabilizing piles(MRSPs)have been used to stabilize massive reservoir landslides in China.In this study,two centrifuge model tests were carried out to study the unreinforced and MRSP-reinforced slopes subjected to reservoir water level(RWL)operation,using the Taping landslide as a prototype.The results indicate that the RWL rising can provide lateral support within the submerged zone and then produce the inward seepage force,eventually strengthening the slope stability.However,a rapid RWL drawdown may induce outward seepage forces and a sudden debuttressing effect,consequently reducing the effective soil normal stress and triggering partial pre-failure within the RWL fluctuation zone.Furthermore,partial deformation and subsequent soil structure damage generate excess pore water pressures,ultimately leading to the overall failure of the reservoir landslide.This study also reveals that a rapid increase in the downslope driving force due to RWL drawdown significantly intensifies the lateral earth pressures exerted on the MRSPs.Conversely,the MRSPs possess a considerable reinforcement effect on the reservoir landslide,transforming the overall failure into a partial deformation and failure situated above and in front of the MRSPs.The mechanical transfer behavior observed in the MRSPs demonstrates a progressive alteration in relation to RWL fluctuations.As the RWL rises,the mechanical states among MRSPs exhibit a growing imbalance.The shear force transfer factor(i.e.the ratio of shear forces on pile of the n th row to that of the first row)increases significantly with the RWL drawdown.This indicates that the mechanical states among MRSPs tend toward an enhanced equilibrium.The insights gained from this study contribute to a more comprehensive understanding of the failure mechanisms of reservoir landslides and the mechanical behavior of MRSPs in reservoir banks.

Analysis and Comparison of the Effect of Preserving Spontaneous Breathing Without Intubation and Endotracheal Intubation with One Lung Ventilation in Single-hole Thoracoscopic Bulla Suture

Objective:To explore the situation of patients and the compare the effect between two methods,which are preserving spontaneous breathing without intubation and endotracheal intubation with one lung ventilation in the single-hole thoracoscopic bulla suture.Method:42 patients who received single-hole thoracoscopic pulmonary bullae suture in our hospital from January 2020 to December 2021 were selected as the study subjects,including 19 patients who underwent endotracheal intubation and one lung ventilation as the control group and 23 patients who underwent single-hole thoracoscopic pulmonary bullae suture without intubation as the study group.The relevant indexes,postoperative general conditions,complications and pneumothorax recurrence of the two groups were analyzed and observed.Results:In the control group,the scores of anesthesia time(points),resuscitation time(points),surgical visual field score(points),surgical time(points),and surgical bleeding volume(points)were 20.8±4.6,19.9±7.9,1.7±0.5,44.9±7.9,and 11.4±2.4 respectively.In the study group,the scores of anesthesia time(points),resuscitation time(points),surgical visual field score(points),surgical time(points),and scores of surgical bleeding(points)were 17.9±4.3,15.4±3.4,1.9±0.4,48.4±7.1,10.9±2.2,respectively.There was no statistical difference in surgical visual field score,surgical time and surgical bleeding whereas there was a statistical difference between anesthesia time and resuscitation time.In the control group after operation,VAS score at 6 hours after operation,SaO_(2)(%)after operation,PaCO_(2)(mmHg)after operation,drainage volume(ML)after operation,feeding time(H)after operation,retention time of thoracic tube after operation(H),WBC(109)on the first day after operation,hospitalization time(d),and total hospitalization cost(RMB 1000)were 2.1±0.7,98.2±1.4,42.4±4.9,139.1±23.1,6.9±1.6,37.1±5.4,7.9±2.1,6.6±1.3,and 2.6±0.3 respectively.As for the study group,the VAS score at 6 hours after operation,SaO_(2)(%)after operation,PaCO_(2)(mmHg)after operation,drainage volume(ML)after operation,feeding time(H)after operation,retention time of thoracic tube after operation(H),WBC(109)on the first day after operation,hospitalization time(d),and total hospitalization cost(RMB 1000)were 1.9±0.4,97.9±1.2,42.8±5.1,151.8±21.9,4.3±1.4,15.3±2.6,5.2±2.3,4.2±1.2,and 1.8±0.4 respectively.Among them,there were no significant differences in visual analog scale(VAS)score at 6 hours after operation,SaO_(2) after operation and PaCO_(2) after operation between the two groups,but there were significant differences in other factors.The complication rate of the control group was 36.84%,which was significantly higher than that of the study group(4.35%),with statistical difference.The recurrence rate of the control group was 21.05%,which was not significantly different from that of the study group(4.35%).Conclusion:The single-hole thoracoscopic bullae suture without intubation can reduce the anesthesia time and resuscitation time of patients,reduce the hospitalization cost of patients,reduce the treatment burden,shorten the first feeding time,and reduce the complication rate of patients.Therefore,it is worthy of clinical promotion.

Study on Plant Landscaping Methods in Garden Landscape Construction

Garden landscape is a beautiful complex formed by space and time complementing each other and acting together.Garden plants are the core landscaping elements in garden landscape construction.It is necessary to flexibly use a variety of plant landscaping methods to create a richer and more vivid natural landscape,and promote the improvement of the quality of the living environment and the harmonious coexistence between man and nature.

3D FEM simulation of flow velocity field for 5052 aluminum alloy multi-row sprocket in cold semi-precision forging process

Based on the design of the multi-row sprocket with a new tooth profile,a cold semi-precision forging process for manufacturing 5052 aluminum alloy multi-row sprocket was presented.Through simulating the forging process of 5052 aluminum alloy sprocket billet with 3D rigid-viscoplastic FEM,both the distributions of flow velocity field in axial(U_Z),radial(U_R) and circumferential(U_θ) directions and the curves of velocity component in different deformation regions were respectively obtained.By comparison and analysis of the velocity varying curves,the velocity component relation conditions for filling the die cavity were clarified.It shows that when the die cavity is almost fully filled,the circumferential velocity U_θ increases sharply,implying that U_θplays a key role in fully filling the die cavity.

Upper-bound and finite element analyses of multi-row sprocket during cold semi-precision forging process

The cold semi-precision forging of a multi-row sprocket was investigated using upper-bound （UB） and finite element methods combined with experiments. Based on the design of a new tooth profile for the sprocket, a cold semi-precision forging process and a kinematically admissible velocity field for filling the die cavity were proposed. Using the UB method, the velocity fields of the sprocket billet in the forming process were divided theoretically and calculated. The process of forging a multi-row sprocket was simulated using the FEM package Deform-3D V6.1 to obtain the distributions of the velocity field and the effective stress field in filling the die cavity. Similar to the simulated results, the experiment on cold forging a 5052 aluminum alloy sprocket was successfully performed. By comparing the calculated （UB method）, experimental and simulated load-stroke curves, the calculated and simulated results were basically in accordance with the experimental results. The study provides a theoretical foundation for the development of the precision forging of multi-row sprockets.

SELF-ALIGNING EVEN LOAD MECHANISM OF MULTI-ROW BEARINGS OF LARGE STRIP ROLLING MILL

The load distribution of multi-row bearings of large strip rolling mill is fully analyzed by 3D contact boundary element method （BEM）. It is found out that bearings are frequently worn out due to serious uneven load on the multi-row rollers. The constraint mechanism of the previous rolling system is found to be unreasonable by theoretical analysis on heavy machinery structure. A mechanism of self-aligning even load for workroll bearing of 2 050 mm hot rolling mill of Baoshan I＆S Co. is developed. This device is manufactured with particular regard to the structure of 2 050 mm hot rolling mill mentioned above. Hence, uneven load on multi-row bearings is greatly relieved and their lives are remarkably prolonged. Meanwhile, theoretical analysis and on-spot tests prove the rationality and validity of the device.

Modified scaled distance regression analysis approach for prediction of blast-induced ground vibration in multi-hole blasting

The blast-induced ground vibration prediction using scaled distance regression analysis is one of the most popular methods employed by engineers for many decades. It uses the maximum charge per delay and distance of monitoring as the major factors for predicting the peak particle velocity(PPV). It is established that the PPV is caused by the maximum charge per delay which varies with the distance of monitoring and site geology. While conducting a production blasting, the waves induced by blasting of different holes interfere destructively with each other, which may result in higher PPV than the predicted value with scaled distance regression analysis. This phenomenon of interference/superimposition of waves is not considered while using scaled distance regression analysis. In this paper, an attempt has been made to compare the predicted values of blast-induced ground vibration using multi-hole trial blasting with single-hole blasting in an opencast coal mine under the same geological condition. Further,the modified prediction equation for the multi-hole trial blasting was obtained using single-hole regression analysis. The error between predicted and actual values of multi-hole blast-induced ground vibration was found to be reduced by 8.5%.

Signal processing method for shear wave velocity measurement

Soil shear wave velocity （SWV） is an important parameter in geotechnical engineering. To measure the soil SWV, three methods are generally used in China, including the single-hole method, cross-hole method and the surface-wave technique. An optimized approach based on a correlation function for single-hole SWV measurement is presented in this paper. In this approach, inherent inconsistencies of the artificial methods such as negative velocities, and too-large and too-small velocities, are eliminated from the single-hole method, and the efficiency of data processing is improved. In addition, verification using the cross-hole method of upper measuring points shows that the proposed optimized approach yields high precision in signal processing.

多层螺旋CT灌注成像在肺癌诊断中的价值

目的:评价多层螺旋CT灌注在诊断肺癌中的价值。材料与方法:回顾性分析2013年1月至2014年12月间经手术确诊的肺部肿瘤患者共48例,患者术前均行CT灌注检查和CT常规增强。结果:肺癌的BV、BF、PS均高于良性病变,而肺癌的MTT则低于良性病变。常规CT增强检查和CTP对肺癌的检出率分别为65%和90%,两者具有统计学差异。结论:多层螺旋CT灌注为肺癌的诊断提供重要信息。

PREPARATION OF SINGLE-HOLE HOLLOW POLYMER NANOSPHERES BY RASPBERRY-LIKE TEMPLATE METHOD

Single-hole hollow polymer nanospheres were fabricated by raspberry-like template method using ＂graft-from＂ strategy through atom transfer radical polymerization （ATRP）. Nanometer-sized silica spheres were covalently attached onto the surfaces of micrometer-sized silica spheres. Crosslinked polymer shells on the nano-sized spheres outside the attached area were formed by ＂graft-from＂ strategy through ATRP. After removal of the silica cores, single-hole hollow crosslinked polymer nanospheres were obtained. In this strategy, most of ATRP monomers may be used and thus many functional groups can be easily incorporated into the single-hole hollow crosslinked polymer nanospheres.

Design and experiment of multi-row pneumatic precision metering device for rapeseed

The main objective of this study was to design a pneumatic disk with four-rows for planting rapeseed and to investigate its performance under several rotating speeds and vacuum pressure values.The effects of rotating speeds,vacuum pressure and rows on seed sucking and retaining were inspected.Six rotating speeds(5 r/min,10 r/min,15 r/min,20 r/min,25 r/min and 30 r/min)incorporated with the application of vacuum pressure were employed for detecting the optimum vacuum amount that was sufficient for seed sucking under each speed.These values of vacuum were found to be 1.1 kPa,1.25 kPa,1.35 kPa,1.65 kPa,1.8 kPa and 2.0 kPa,respectively.Moreover,a regression model was developed for predicting of vacuum pressure that corresponds with each rotating speed.Based on seed mass analysis,statistical differences were found at 5%significance under the influence of speeds and negative pressure and existed also between and within rows according to Duncan’s Test.The highest seed mass means of 3.17 g and 3.96 g were obtained by row 1 under the effects of speed and vacuum pressure,respectively,while the lowest means of 2.79 g and 3.05 g were attained by row 4.Due to the influence of rows,important differences were occurred between row 1(closer to the center of rotation)and row 4(farther one),particularly under high speeds(25 r/min and 30 r/min).Results concluded that,pneumatic disk with multiple-rows could be satisfactorily used for seed sowing with a little variation in seed amount between rows without any seed damage.The rows of hole farther from plate center of rotation were obviously influenced by angular velocity and vacuum amount rather than the closer ones.

Design and experiment of the pneumatic cylinder type precision metering system for wheat

The main goal of this study was to design a pneumatic cylindrical-type metering device with six-rows for wheat precision and to analyze its output under different rotating speeds and vacuum pressure values.The effect of the pressure,rotating speed and rows on seed suction,retention and dropping was shown inspected.Six levels of rotating speed(5,10,15,20,25 and 30 r/min.)combined with the applying of different vacuum pressures(1.8,2.1,2.4,2.7,3.0,and 3.3 kPa)were inspected to detect the optimum pressure which was adequate for seed sucking at each speed.In addition,to predict the vacuum pressure corresponding with each rotating speed,a regression model was developed.Based on seed mass analysis,statistical differences under the influence of velocities and negative pressure were found at 5 percent significance according to Duncan’s Test,whereas the differences were existed between and within rows.Results revealed that the highest seed mass means of 19.02 g and 22.64 g were obtained by row1while the lowest means of 18.02 g and 21.49 g were attained by row6 under the effect of the speed and vacuum pressure,respectively.The noticeable variation between row1 and row 6,particularly under high speeds(25 and 30 r/min),might be returned to the truth that row 1 was closer to vacuum inlet,and row 6 was the farthest one.Results concluded that the multiple-row pneumatic cylinder with oblong shape seed nozzle was found to be capable for single seed picking with a small rows variation but without seed damage.