Though gravel cushions are used worldwide in open-pit mines and railway slopes to control the impact of rolling stones,no universal technical standards have been put in place to guide engineers in their correct design...Though gravel cushions are used worldwide in open-pit mines and railway slopes to control the impact of rolling stones,no universal technical standards have been put in place to guide engineers in their correct design,and few laboratory test results are available with which to characterize collisions between rolling stones and a gravel cushion.We carried out a large number of experiments in which rolling stones made of the same material but differently shaped were dropped from various heights onto cushions with various particle sizes and thicknesses.We investigated the characteristics of the resulting collisions,and the relationships between coefficients of restitution(CORs)of blocks with different shape and release height H,cushion thickness h and particle diameter d are obtained through linear fitting method.Orthogonal testing reveals the relative influence of block shape,release height,and the particle size and thickness of the cushion on the collision characteristics,which can assist engineers in designing a gravel cushion suitable to the distribution and weathering characteristics of rolling stones in a specific area.展开更多
Staghorn stones have always been a challenge for urologists,especially in some special situations,such as horseshoe kidney,ectopic kidney,paediatric kidney,and solitary kidney.The treatment of these staghorn stones mu...Staghorn stones have always been a challenge for urologists,especially in some special situations,such as horseshoe kidney,ectopic kidney,paediatric kidney,and solitary kidney.The treatment of these staghorn stones must be aggressive because they can lead to renal function loss and serious complications.The gold-standard management for staghorn stones is surgical treatment with the aim of clearing the stones and preserving renal function.Treatment methods for staghorn stones have developed rapidly,such as extracorporeal shock wave lithotripsy,retrograde intrarenal surgery,percutaneous nephrolithotomy and laparoscopy and open surgery.Whether the standard procedures for staghorn stones can also apply to these stones in special situations is still not agreed upon.The decision should be made individually according to the circumstances of the patient.In this review,we evaluates the previous studies and comments on the management of staghorn stones under special situations in the hope of guiding the optimal choice for urologists.展开更多
Application of improper methods on rice processing affects rice quality and head rice recovery. In Vietnam, paddy with different moisture contents （from 13% to 17%） is dehusked by both rubber roll and stone disk. Th...Application of improper methods on rice processing affects rice quality and head rice recovery. In Vietnam, paddy with different moisture contents （from 13% to 17%） is dehusked by both rubber roll and stone disk. Thus, objective of this research was to evaluate the technical and economic aspects of the two methods. Optimization was conducted with 20 experiments for input factors （moisture content） and output factors （head brown rice recovery, specific energy consumption）. Besides, other factors were also monitored, such as the gap between the two disks, speed of disk and roll, and pressure of rubber roll on paddy. Test results showed that the maximum value of head brown rice （77.4%） and the minimum value of specific energy consumption （0.66 kWh/ton） corresponding to moisture content of paddy of 13.7% for stone disk dehusker. At similar moisture content （13.7%）, head brown rice recovery and specific energy consumption were 77.2% and 1.04 kWh/ton for rubber roll dehusker, respectively. As the result, specific energy consumption of rubber roll dehusker was higher than that of stone disk dehusker, corresponding to the higher dehusking efficiency.展开更多
基金supported by the Fundamental Research Funds for the Central Universities(No.B210201001)the open fund of Key Laboratory of Rock Mechanics and Geohazards of Zhejiang Province(No.ZJRMG-2020-02)+1 种基金the open fund of Engineering Research Center of Development and Management for Low to Ultra-Low Permeability Oil&Gas Reservoirs in West China,Ministry of Education(No.KFJJ-XB-2020-7)the Research and Development Project of Guizhou University of Engineering Science(No.G2018016)。
文摘Though gravel cushions are used worldwide in open-pit mines and railway slopes to control the impact of rolling stones,no universal technical standards have been put in place to guide engineers in their correct design,and few laboratory test results are available with which to characterize collisions between rolling stones and a gravel cushion.We carried out a large number of experiments in which rolling stones made of the same material but differently shaped were dropped from various heights onto cushions with various particle sizes and thicknesses.We investigated the characteristics of the resulting collisions,and the relationships between coefficients of restitution(CORs)of blocks with different shape and release height H,cushion thickness h and particle diameter d are obtained through linear fitting method.Orthogonal testing reveals the relative influence of block shape,release height,and the particle size and thickness of the cushion on the collision characteristics,which can assist engineers in designing a gravel cushion suitable to the distribution and weathering characteristics of rolling stones in a specific area.
基金This work was financed by a grant from the National Natural Science Foundation of China(No.81800624).
文摘Staghorn stones have always been a challenge for urologists,especially in some special situations,such as horseshoe kidney,ectopic kidney,paediatric kidney,and solitary kidney.The treatment of these staghorn stones must be aggressive because they can lead to renal function loss and serious complications.The gold-standard management for staghorn stones is surgical treatment with the aim of clearing the stones and preserving renal function.Treatment methods for staghorn stones have developed rapidly,such as extracorporeal shock wave lithotripsy,retrograde intrarenal surgery,percutaneous nephrolithotomy and laparoscopy and open surgery.Whether the standard procedures for staghorn stones can also apply to these stones in special situations is still not agreed upon.The decision should be made individually according to the circumstances of the patient.In this review,we evaluates the previous studies and comments on the management of staghorn stones under special situations in the hope of guiding the optimal choice for urologists.
文摘Application of improper methods on rice processing affects rice quality and head rice recovery. In Vietnam, paddy with different moisture contents （from 13% to 17%） is dehusked by both rubber roll and stone disk. Thus, objective of this research was to evaluate the technical and economic aspects of the two methods. Optimization was conducted with 20 experiments for input factors （moisture content） and output factors （head brown rice recovery, specific energy consumption）. Besides, other factors were also monitored, such as the gap between the two disks, speed of disk and roll, and pressure of rubber roll on paddy. Test results showed that the maximum value of head brown rice （77.4%） and the minimum value of specific energy consumption （0.66 kWh/ton） corresponding to moisture content of paddy of 13.7% for stone disk dehusker. At similar moisture content （13.7%）, head brown rice recovery and specific energy consumption were 77.2% and 1.04 kWh/ton for rubber roll dehusker, respectively. As the result, specific energy consumption of rubber roll dehusker was higher than that of stone disk dehusker, corresponding to the higher dehusking efficiency.
