Main Index

2021 ◽  
pp. 633-646
Keyword(s):  
Main Index

Analysis of Mechanophysical Properties of Fritillaria ussuriensis Maxim and Designing of Grade Sieve Machine

2013 ◽  
Vol 764 ◽  
pp. 165-168
Author(s):  
Jiang Song ◽  
Song Zhuo Lu ◽  
Li Hua Liu ◽  
Ming Wang ◽  
Tian Xiang Liu
Keyword(s):  
Mechanical Properties ◽  
Friction Coefficient ◽  
Physical And Mechanical Properties ◽  
Middle Layer ◽  
Mathematical Statistics ◽  
Angle Of Repose ◽  
Screening Process ◽  
Geometrical Properties ◽  
Pore Dimension ◽  
Main Index

Based on the field and lab measuerement in harvest time, Physical and mechanical properties of fritillaria ussuriensis maxim (FUM) are researched. Geometrical properties of FUM are analyzed using mathematical statistics method, and the variation sections of main index values of two kinds of FUM are obtained. Mechanical properties of FUM outsifting in screen penetrating process are tested by means of friction experiment, the friction coefficient and angle of repose of two kinds of FUM are obtained using mathematical statistics method. Grade sieve machine is designed based on the analysis of mechanophysical properties of FUM. The main parameters are: shape of sieve pore is rectangle, screen diameter is 20mm, sieve pore dimension of upper layer is 13×20mm2, middle layer is 9×18mm2, and under layer is 7×10mm2. By testing of friction coefficient and angle of repose and movement and dynamics analysis of grade sieve, outsifting velocity is 7<<9rad/s and acceleration is 4<a<13m/s2 in screening process.

scholarly journals Road train motion stability in BRT system

2019 ◽  
Vol 254 ◽  
pp. 03007 ◽  
Author(s):  
Vladimir Sakhno ◽  
Juraj Gerlici ◽  
Viktor Poliakov ◽  
Alexandr Kravchenko ◽  
Oleg Omelnitcky ◽  
...  
Keyword(s):  
Critical Speed ◽  
Motor Vehicles ◽  
Mass Center ◽  
Passenger Transportation ◽  
Wheel Drive ◽  
Main Index ◽  
Rapid Transport ◽  
The Stability ◽  
The City ◽  
Potential Stability

The peculiarities of organization and perspectives of mass passenger transportation in the city and beyond are considered with the use of "Bus Rapid Transport" (BRT) or Metrobus. Different aspects of study of motor vehicles (MV) controllability and stability are analyzed. It is substantiated that it is sufficient to consider the potential stability of the MV itself, in order to guarantee the stability of the "driver MV" system with a large reserve. A mathematical model of a three-axle bus train consisting of a bus and two trains (metrobus) is developed and the factors influencing the critical speed as the main index of the stability of its movement are determined. It is established that the increase of the critical speed of the metrobus can be achieved by increasing the base of the bus, the first and the second trailer, as well as the mass of the bus and the coefficients of resistance of the drive wheels of the bus driving axle and the trailers axles. At the same time, increasing the distance from the mass center to the bus rear axle, increasing the distance from the mass center to the point of the coupling of the bus with the first trailer, increasing the mass of trailers and the resistance of the resistance of the wheel drive of the bus axis lead to a decrease in the critical speed of the metrobus. This must be taken into account both when designing metrobuses, and when operating them.

scholarly journals Study of Availability and Productivity of Automated Lines

2021 ◽  
Vol 8 (1) ◽  
pp. 144-153
Author(s):  
A. M. Ahmed Alwaise ◽  
Omer Haitham Kanam
Keyword(s):  
Mechanical Parameters ◽  
Technical Data ◽  
Main Index ◽  
Productivity Rate ◽  
Automated Lines ◽  
Manufacturing Machine

In area of manufacturing, the indices of each manufacturing machine are the productivity and goodness of products. The theory of reliability is closely related to Indices of productivity, the both theories the efficiency of machines, and optimizations one. The reliability of machines has been guessed by standard indices of the theory of reliability. The main index of reliability of every manufacturing machine is its availability. However, indicated the reliability of industrial machines with complicate design have not expressed in equations of the productivity. These indices of accuracy should be a component of equations of a productivity of a machine and reflects changes of a productivity rate one on changes of indices of reliability and mechanical parameters of a machine. The availability has been included the equations of the machines productivity rate, therefore the reliability of machines is the integrated indication. The machines reliability with complicate design such as automated lines relies also on construction and technical data. The output modelling has been reported the output result with availability for the automated lines, defining their structures according to the grade of reliability and productivity as a task of technical motif of manufacturing machines with complex designs.

scholarly journals Epidemiological evidence relating environmental smoke to COPD in lifelong non-smokers: a systematic review

F1000Research ◽  
2018 ◽  
Vol 7 ◽  
pp. 146 ◽  
Author(s):  
Peter N. Lee ◽  
Barbara A. Forey ◽  
Katharine J. Coombs ◽  
Jan S. Hamling ◽  
Alison J. Thornton
Keyword(s):  
Meta Analysis ◽  
Middle Eastern ◽  
Epidemiological Data ◽  
Case Control ◽  
Chronic Obstructive ◽  
Exposure Index ◽  
Bias Estimation ◽  
Case Control Studies ◽  
Cross Sectional ◽  
Main Index

Background: Some evidence suggests environmental tobacco smoke (ETS) might cause chronic obstructive pulmonary disease (COPD). We reviewed available epidemiological data in never smokers. Methods: We identified epidemiological studies providing estimates of relative risk (RR) with 95% confidence interval (CI) for various ETS exposure indices. Confounder-adjusted RRs for COPD were extracted, or derived using standard methods. Meta-analyses were conducted for each exposure index, with tests for heterogeneity and publication bias. For the main index (spouse ever smoked or nearest equivalent), analyses investigated variation in RR by location, publication period, study type, sex, diagnosis, study size, confounder adjustment, never smoker definition, and exposure index definition. Results: Twenty-eight relevant studies were identified; nine European or Middle Eastern, nine Asian, eight American and two from multiple countries. Five were prospective, seven case-control and 16 cross-sectional. The COPD definition involved death or hospitalisation in seven studies, GOLD stage 1+ criteria in twelve, and other definitions in nine. For the main index, random-effects meta-analysis of 33 heterogeneous (p<0.001) estimates gave a RR of 1.20 (95%CI 1.08-1.34). Higher estimates for females (1.59,1.16-2.19, n=11) than males (1.29,0.94-1.76, n=7) or sexes combined (1.10,0.99-1.22, n=15 where sex-specific not available), and lower estimates for studies of 150+ cases (1.08,0.97-1.20, n=13) partly explained the heterogeneity. Estimates were higher for Asian studies (1.34,1.08-1.67, n=10), case-control studies (1.55,1.04-2.32, n=8), and COPD mortality or hospitalisation (1.40,1.12-1.74, n=11). Some increase was seen for severer COPD (1.29,1.10-1.52, n=7). Dose-response evidence was heterogeneous. Evidence for childhood (0.88,0.72-1.07, n=2) and workplace (1.12,0.77-1.64, n=4) exposure was limited, but an increase was seen for overall adulthood exposure (1.20,1.03-1.39, n=17). We discuss study weaknesses that may bias estimation of the association of COPD with ETS. Conclusions: Although the evidence suggests ETS increases COPD, study weaknesses and absence of well-designed large studies precludes reliable inference of causality. More definitive evidence is required.

Lowlands Mapping in Forest Guinea

2013 ◽  
Vol 4 (1) ◽  
pp. 20-34 ◽  
Author(s):  
S. Saïdi ◽  
A. Camara ◽  
L. Gazull ◽  
M. Passouant ◽  
M. Soumaré
Keyword(s):  
Surface Topography ◽  
Digital Elevation Model ◽  
Low Cost ◽  
Mapping Method ◽  
Drainage Network ◽  
Digital Elevation ◽  
Agricultural Potential ◽  
Forested Areas ◽  
Main Index ◽  
Elevation Model

This article presents a lowland mapping method for the Forested Guinea (Guinée Forestière) using a 30 m resolution Digital Elevation Model (DEM) that is currently the best option to analyze large forested areas. This low cost DEM method applies surface topography analysis processes to better discriminate areas with stagnant and/or accumulated water. The main index selected is the immediate proximity of flat areas to drainage network, the former with slope gradients not exceeding 5% (2.86°). The mapped lowlands potential cover a surface of 4516 km2, i.e., 10% of the total area of the region with hydro-agricultural potential.

scholarly journals An Ore Image Segmentation Method Based on RDU-Net Model

Sensors ◽  
2020 ◽  
Vol 20 (17) ◽  
pp. 4979
Author(s):  
Dong Xiao ◽  
Xiwen Liu ◽  
Ba Tuan Le ◽  
Zhiwen Ji ◽  
Xiaoyu Sun
Keyword(s):  
Image Segmentation ◽  
Production Efficiency ◽  
Fragment Size ◽  
Conveyor Belt ◽  
Segmentation Method ◽  
Residual Structure ◽  
Production Safety ◽  
Segmentation Methods ◽  
Segmentation Accuracy ◽  
Main Index

The ore fragment size on the conveyor belt of concentrators is not only the main index to verify the crushing process, but also affects the production efficiency, operation cost and even production safety of the mine. In order to get the size of ore fragments on the conveyor belt, the image segmentation method is a convenient and fast choice. However, due to the influence of dust, light and uneven color and texture, the traditional ore image segmentation methods are prone to oversegmentation and undersegmentation. In order to solve these problems, this paper proposes an ore image segmentation model called RDU-Net (R: residual connection; DU: DUNet), which combines the residual structure of convolutional neural network with DUNet model, greatly improving the accuracy of image segmentation. RDU-Net can adaptively adjust the receptive field according to the size and shape of different ore fragments, capture the ore edge of different shape and size, and realize the accurate segmentation of ore image. The experimental results show that compared with other U-Net and DUNet, the RDU-Net has significantly improved segmentation accuracy, and has better generalization ability, which can fully meet the requirements of ore fragment size detection in the concentrator.

Damage Assessment of Single-Layer Cylindrical Latticed Shells Based on Degradation of Static Stability Capacity

2010 ◽  
Vol 163-167 ◽  
pp. 227-232
Author(s):  
Da Bin Yang ◽  
Yi Gang Zhang ◽  
Jin Zhi Wu ◽  
Hai Tao Zhou ◽  
Wen Chao Liu
Keyword(s):  
Damage Assessment ◽  
Static Load ◽  
Mechanical Performance ◽  
Single Layer ◽  
Static Stability ◽  
Seismic Damage ◽  
Assessment Method ◽  
Live Load ◽  
Dead Load ◽  
Main Index

The static stability capacity is the main index to measure the whole mechanical performance of single-layer latticed shells. Three single-layer cylindrical latticed shells with different height to span ratio were modeled, and their seismic damage were assessed by the degradation of static stability capacity incurred by earthquakes. Two different static load patterns were considered: dead load and the combination of dead load and half span live load. The results show that the damage assessment method is applicable to single-layer cylindrical latticed shells, and the static load patterns have no big influence on the damage assessment of the single-layer cylindrical latticed shells.

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