Optimum traveling and rotation speeds in friction stir welding for dissimilar Al alloys

Aluminum alloys are subjected to large deformation and decreased strength due to the high expansion modulus caused by heat effects during friction stir welding （FSW）.The optimum conditions for friction stir welding of 5052-O and 6061-T6 Al alloys were determined.The optimum traveling and rotation speeds were identified to be 61mm/min and 1600r/min using various mechanical characteristic evaluation methods.

CUTTING REGULARITY AND DISCHARGE CHARACTERISTICS BY USING COMPOSITE COOLING LIQUID IN WIRE CUT ELECTRICAL DISCHARGE MACHINE WITH HIGH WIRE TRAVELING SPEED

The analysis of cutting regularity is provided through using and comparing two typical cooling liquids. It is proved that cutting regularity is greatly affected by cooling liquid＇s washing ability. Discharge characteristics and theoretic analysis between two electrodes are also discussed based on discharge waveform. By using composite cooling liquid which has strong washing ability, the efficiency in the first stable cutting phase has reached more than 200 mm^2/min, and the roughness of the surface has reached Ra〈0.8 μm after the fourth cutting with more than 50 mm^2/min average cutting efficiency. It is pointed out that cutting situation of the wire cut electrical discharge machine with high wire traveling speed （HSWEDM） is better than the wire cut electrical discharge machine with low wire traveling speed （LSWEDM） in the condition of improving the cooling liquid washing ability. The machining indices of HSWEDM will be increased remarkably by using the composite cooling liquid.

Cyclical helping hands: seasonal tailwinds differentially affect migrating Oriental Storks (Ciconia boyciana) travel speed

Background:The Oriental Stork(Ciconia boyciana)breeds in southeastern Siberia and parts of northeast China,and winters mainly in southeast China.Although the autumn migration pattern of Oriental Storks has been previ-ously described,differences between spring and autumn migration travel speed in relation to wind assistance were unknown.Methods:Using GPS/GSM transmitters,we tracked the full migrations of 18 Oriental Storks during 2015-2018 to compare differences in autumn and spring migration patterns,and combined the satellite telemetry data with the National Center for Environmental Prediction Reanalysis data to explain the relationship between 850 mbar wind vec-tors and seasonal differences in travel speed.Results:Differences in tailwinds contributed to significant differences in daily average Oriental Storks travel speed in spring(258.11±64.8 km/day)compared to autumn(172.23±49.7 km/day,p<0.001).Storks stopped significantly more often in autumn than spring(1.78±1.1 versus 1.06±0.9,p<0.05),but stopover duration(15.52±12.4 versus 16.30±15.1 days,respectively,p=0.3)did not differ significantly.Tailwinds at 850 mbar pressure level(extracted from the National Center of Environmental Prediction Reanalysis data archive)significantly affected daily flying speed dur-ing spring and autumn migration.Tailwind conditions in spring(mean 4.40±5.6 m/s)were always more favourable than in autumn when they received no net benefit(0.48±5.6 m/s,p<0.001).Despite mean spring migration dura-tion being less than autumn(27.52±15.9 versus 32.77±13.4 days,p=0.17),large individual variation meant that this duration did not differ significantly from each other.Conclusions:For long distance migratory soaring birds(such as storks),relative duration of spring and autumn migration likely relates to the interaction between imperative for earliest arrival to breeding grounds and seasonal meteorological conditions experienced en route.

Floating Car Data Based Nonparametric Regression Model for Short-Term Travel Speed Prediction

A K-nearest neighbor （K-NN） based nonparametric regression model was proposed to predict travel speed for Beijing expressway. By using the historical traffic data collected from the detectors in Beijing expressways, a specically designed database was developed via the processes including data filtering, wavelet analysis and clustering. The relativity based weighted Euclidean distance was used as the distance metric to identify the K groups of nearest data series. Then, a K-NN nonparametric regression model was built to predict the average travel speeds up to 6 min into the future. Several randomly selected travel speed data series, collected from the floating car data （FCD） system, were used to validate the model. The results indicate that using the FCD, the model can predict average travel speeds with an accuracy of above 90%, and hence is feasible and effective.

Visible Losses to the Mechanical Harvesting of Ratoon Sugarcane Using the Harvester John Deere 3520

The aim of this study was to evaluate the visible loss of sugar cane and the damage to the knuckles, using the John Deere 3520 harvester on three different travel speeds (3.0;4.0 and 5.0 km·h-1), in DIC with five repetitions in Campos dos Goytacazes, Rio de Janeiro/Brazil. Each treatment was composed by six lines of harvested cane stumps, with a length of 290 m each. In these six lines, the remains of sugar cane left in the field were collected by placing the sampling frame in two central lines every 50 m, and separating 40 m of edge. The sampling area was surrounded by 2 m wide and 10 m long, totaling 20 m2. To calculate the damage to stumps, a visual methodology by [1], was used, which classifies the damage grade, ranging from 1 to 4. Fifty stumps were assessed randomly for each speed, in a sampling area of 1800 m2. The data were submitted to ANOVA and Tukey test at 5%, in order to compare the effect of different speeds on the losses and damages. There was no significant difference regarding the loss or damage by comparing the different speeds. Therefore, it is more advantageous to use the speed of 5.0 km·h-1, harvesting more in less time and causing the same level of damage.

Stability and a fast calculation method of travel speed of pulse peak in convergence zone

A long-range sound propagation experiment was conducted in the West Pacific Ocean in summer 2013.The signals received by a towed array indicate that the travel speed of pulse peak(TSPP)in the convergence zones is stable.Therefore,an equivalent sound speed can be used at all ranges in the convergence zones.A fast calculation method based on the beam-displace-ment ray-mode(BDRM)theory and convergence zone theory is proposed to calculate this equivalent sound speed.The computation speed of this proposed method is over 1000 times faster than that of the conventional calculation method based on the normal mode theory,with the computation error less than 0.4%compared with the experimental result.Also,the effect of frequency and sound speed profile on the TSPP is studied with the conventional and fast calculation methods,showing that the TSPP is almost independent of the frequency and sound speed profile in the ocean surface layer.

Virtual speed sensors based algorithm for expressway traffic state estimation

The accurate estimation of expressway traffic state can provide decision-making for both travelers and traffic managers. The speed is one of the most representative parameter of the traffic state. So the expressway speed spatial distribution can be taken as the expressway traffic state equivalent. In this paper, an algorithm based on virtual speed sensors (VSS) is presented to estimate the expressway traffic state (the speed spatial distribution). To gain the spatial distribution of expressway traffic state, virtual speed sensors are defined between adjacent traffic flow sensors. Then, the speed data extracted from traffic flow sensors in time series are mapped to space series to design virtual speed sensors. Then the speed of virtual speed sensors can be calculated with the weight matrix which is related with the speed of virtual speed sensors and the speed data extracted from traffic flow sensors and the speed data extracted from traffic flow sensors in time series. Finally, the expressway traffic state (the speed spatial distribution) can be gained. The acquisition of average travel speed of the expressway is taken for application of this traffic state estimation algorithm. One typical expressway in Beijing is adopted for the experiment analysis. The results prove that this traffic state estimation approach based on VSS is feasible and can achieve a high accuracy.

Effect of travel speed on seed spacing uniformity of corn seed meter

Both seeding performance of seed metering unit and travel speed of seed planter have significant effects on seeding quality,thereby affecting crop growth and yields.In order to determine the effects of different travel speeds on seed spacing uniformity,four different types of seed meters were evaluated at five different travel speeds on seed meter test bench and in field.The tested seed meters included a finger pickup seed meter,a scoop-wheel seed meter,an air-pressure type seed meter and an air-blowing type seed meter.The seeding performance of the horizontal distribution of seeds within a row was described by using the coefficient of variation,the quality of feed index,the multiple index and the miss-seeding index.Experiments were performed in laboratory and field,respectively.Results indicated that different travel speeds have statistically significant effects on seed spacing uniformity.The four types of seed meters performed better on the seed meter test bench than in the field.Coefficient of variation increases and quality of feed index decreases as the travel speed of seed planter increases.The best seed spacing uniformity was obtained with the air-pressure type seed meter,followed with the air-blowing type seed meter,the finger pickup seed meter and the scoop-wheel seed meter.There were considerable differences between the performances of the scoop-wheel seed meter in the bench test and field test;the seeding qualities were much better in the bench test than in the field test.The scoop-wheel seed meter is more sensitive to vibration than the other types of seed meters.

Sowing uniformity of bed-type pneumatic maize planter at various seedbed preparation levels and machine travel speeds

Precision planters are important machines in the regime of modern technological agriculture.Field conditions,seed metering system and machine operating parameters affect the pneumatic planter performance.The pneumatic planter was evaluated to determine the effect of three tillage levels(L1,L2,and L3)and four travel speeds(S1,S2,S3 and S4).The sowing uniformity of the planter was observed with respect to the horizontal distribution of seeds within a row and described by using the precision index(Ip),the multiple index(Imult),the miss-seeding index(Imiss)and the quality of feed index(Iqf).The results revealed that the tillage levels(L)and travel speed(S)had a significant effect(p<0.05)on dependent variables.The maximum Imiss(22.12%)was observed at L1 and S4 whereas the maximum Imult was observed at L1 and S1.The mean values of missing-,multi-,quality-feed and precision indices were 5.14%,5.833%,89.03%and 17.85%at L3,respectively.The mean values of multi-index 17.59%,14.44%,12.40%and 10.18%,quality feed index 74.07%,75.92%,75.74%and 74.07%and precision indices 21.47%,23.26%,25.51%and 28.53%were at S1,S2,S3 and S4,respectively.The study showed that maize could be seeding within an acceptable precise range by bed-type pneumatic planter subjected to the proper seedbed preparation level.

An estimation of vehicle kilometer traveled and on-road emissions using the traffic volume and travel speed on road links in Incheon City

The objective of this study is to estimate the vehicle kilometer traveled（VKT） and on-road emissions using the traffic volume in urban. We estimated two VKT; one is based on registered vehicles and the other is based on traffic volumes. VKT for registered vehicles was 2.11 times greater than that of the applied traffic volumes because each VKT estimation method is different. Therefore, we had to define the inner VKT is moved VKT inner in urban to compare two values. Also, we focused on freight modes because these are discharged much air pollutant emissions. From analysis results, we found middle and large trucks registered in other regions traveled to target city in order to carry freight, target city has included many industrial and logistics areas. Freight is transferred through the harbors,large logistics centers, or via locations before being moved to the final destination. During this process, most freight is moved by middle and large trucks, and trailers rather than small trucks for freight import and export. Therefore, these trucks from other areas are inflow more than registered vehicles. Most emissions from diesel trucks had been overestimated in comparison to VKT from applied traffic volumes in target city. From these findings, VKT is essential based on traffic volume and travel speed on road links in order to estimate accurately the emissions of diesel trucks in target city. Our findings support the estimation of the effect of on-road emissions on urban air quality in Korea.

How fast is it to city centers?The average travel speed as an indicator of road traffic accessibility potential

Transportation is the lifeblood of a modern metropolis.Accessibility generally refers to the interconnection between nodes in a regional traffic network.The purpose of the paper is to obtain more realistic and accurate measures of travel speed and to study the road traffic accessibility potential in cities.This study proposes a method for analyzing road traffic accessibility potential which is based on the average travel speed to city centers in off-peak times and which ranks 80 cities around the world.Based on the Suomi National Polar-Orbiting Partnership satellite’s visible-infrared imaging radiometer suite(NPP-VIIRS)night-time light data,urban built-up areas and city centers were extracted.Further,with the aid of the Google Maps application programming interface(API)network crawling technique,travel times and travel distances for several optimal routes to city centers by car were obtained.Feasible proposals for improving road traffic accessibility and planning urban transportation in different cities are presented.The proposed method offers a new possibility of analyzing traffic accessibility using internet data and geo-spatial methods.

Development and evaluation of a low-cost precision seeding control system for a corn drill

Precision seeding requires that the corn drill drop seeds into the soil by a specific in-row spacing while its travelling speed fluctuates due to unevenness of the field ground.This paper presents a low-cost precision seeding control system for a conventional corn drill with mechanical metering devices of finger-pickup type.A median filtering method was implemented in the control system to process measurements from a rotary encoder in order to acquire stable values of the corn drill travelling speed.The metering unit was driven by an electric motor controlled by the metering ECU according to the actual travelling speed and the desired in-row spacing in real-time.A user interface was programmed to communicate with ECUs for configuring parameters and displaying operating information during working.The newly-developed precision seeding control system was first calibrated in terms of speed measurement and control for two ECUs.Experiments were conducted on a seeding test platform in the laboratory for evaluating its accuracy in dropping seeds by giving different in-row spacing under different travelling speeds of the conveyor sticky belt.Results showed that the average spacing error was less than 2 cm and the maximum RMS error was 0.78 cm for all spacing values including 25 cm,30 cm and 35 cm under the travelling speed of 1.0-8.0 km/h.These indicated that the low-cost precision seeding control system worked in a both accurate and stable way.

A periodic reaction-diffusion system modelling man-environment-man epidemics

The purpose of this work is to study the spatial dynamics of a periodic reaction-diffusion epidemic model arising from the spread of oral-faecal transmitted diseases. We first show that the disease spreading speed is coincident with the minimal wave speed for monotone periodic travelling waves. Then we obtain a threshold result on the global attractivity of either zero or the positive periodic solution in a bounded spatial domain.