Visual navigation in orchard based on multiple images at different shooting angles

The orchards usually have rough terrain,dense tree canopy and weeds.It is hard to use GNSS for autonomous navigation in orchard due to signal occlusion,multipath effect,and radio frequency interference.To achieve autonomous navigation in orchard,a visual navigation method based on multiple images at different shooting angles is proposed in this paper.A dynamic image capturing device is designed for camera installation and multiple images can be shot at different angles.Firstly,the obtained orchard images are classified into sky and soil detection stage.Each image is transformed to HSV space and initially segmented into sky,canopy and soil regions by median filtering and morphological processing.Secondly,the sky and soil regions are extracted by the maximum connected region algorithm,and the region edges are detected and filtered by the Canny operator.Thirdly,the navigation line in the current frame is extracted by fitting the region coordinate points.Then the dynamic weighted filtering algorithm is used to extract the navigation line for the soil and sky detection stage,respectively,and the navigation line for the sky detection stage is mirrored to the soil region.Finally,the Kalman filter algorithm is used to fuse and extract the final navigation path.The test results on 200 images show that the accuracy of visual navigation path fitting is 95.5%,and single frame image processing costs 60 ms,which meets the real-time and robustness requirements of navigation.The visual navigation experiments in Camellia oleifera orchard show that when the driving speed is 0.6 m/s,the maximum tracking offset of visual navigation in weed-free and weedy environments is 0.14 m and 0.24 m,respectively,and the RMSE is 30 mm and 55 mm,respectively.

基于显著场景Bayesian Surprise的移动机器人自然路标检测

移动机器人在未知非结构化环境下的自然路标检测是层次化环境建模的基础.文中提出一种基于显著场景Bayesian Surprise的自然路标检测方法.通过计算场景的视觉注意图,引导SURF特征采样聚集在显著区域内,提出融合空间关系的词袋模型构造场景表观的模式向量,建立基于该特征描述的地点Multivariate Polya模型,并通过度量传感器观测的Surprise来获取显著场景对应的路标.实验验证自然路标检测方法在大规模复杂室内环境中具有较低的漏检率和误检率,结合层次化SLAM方法验证路标检测器对生成拓扑节点的有效性.

机械工程trouble-shooting案例分析教学与动手能力培养

通过trouble shooting案例的分析、讨论、实例讲解,力图引导、启发和培养学生在实际工作中如何去发现问题、如何对已有知识、经验、技能的灵活处理和技术知识的转移、搬迁、嫁接、变异、变通和改进等方面的技巧和动手能力,目的是使学生学习达到“鱼”、“渔”共获。

A CASE STUDY ON LONG HOLE RAISING BY SHOOTING TO RELIEF HOLES

ＡＣＡＳＥＳＴＵＤＹＯＮＬＯＮＧＨＯＬＥＲＡＩＳＩＮＧＢＹＳＨＯＯＴＩＮＧＴＯＲＥＬＩＥＦＨＯＬＥＳ①ＤｉｎｇＤｅｘｉｎＣｅｎｔｒａｌＳｏｕｔｈＩｎｓｔｉｔｕｔｅｏｆＴｅｃｈｎｏｌｏｇｙ，Ｈｅｎｇｙａｎｇ４２１００１ＡＢＳＴＲＡＣＴＡｃａｓｅｓｔｕ...

Optimal index shooting policy for layered missile defense system

In order to cope with the increasing threat of the ballistic missile(BM)in a shorter reaction time,the shooting policy of the layered defense system needs to be optimized.The main decisionmaking problem of shooting optimization is how to choose the next BM which needs to be shot according to the previous engagements and results,thus maximizing the expected return of BMs killed or minimizing the cost of BMs penetration.Motivated by this,this study aims to determine an optimal shooting policy for a two-layer missile defense(TLMD)system.This paper considers a scenario in which the TLMD system wishes to shoot at a collection of BMs one at a time,and to maximize the return obtained from BMs killed before the system demise.To provide a policy analysis tool,this paper develops a general model for shooting decision-making,the shooting engagements can be described as a discounted reward Markov decision process.The index shooting policy is a strategy that can effectively balance the shooting returns and the risk that the defense mission fails,and the goal is to maximize the return obtained from BMs killed before the system demise.The numerical results show that the index policy is better than a range of competitors,especially the mean returns and the mean killing BM number.

Influence of core box vents distribution on flow dynamics of core shooting process based on experiment and numerical simulation

Core shooting process plays a decisive role in the quality of sand cores, and core box vents distribution is one of the most important factor determining the effectiveness of core shooting process. In this paper, the influence of core box vents distribution on the flow dynamics of core shooting process was investigated based on in situ experimental observations with transparent core box, high-speed camera and pressure measuring system. Attention was focused on the variation of both the flow behavior of sand and pressure curves due to different vents distribution. Taking both kinetic and frictional stress into account, a kinetic-frictional constitutive model was established to describe the internal momentum transfer in the solid phase. Two-fluid model(TFM) simulation was then performed and good agreement was achieved between the experimental and simulated results on both the flow behavior of sand and the pressure curves. It was found that vents distribution has direct effect on the pressure difference of different locations in the core box, which determines the buoyancy force exerting on the sand particles and significantly influences the filling process of core sand.

Influence of core sand properties on flow dynamics of core shooting process based on experiment and multiphase simulation

The influence of core sand properties on flow dynamics was investigated synchronously with various core sands, transparent core-box and high-speed camera. To confirm whether the core shooting process has significant turbulence, the flow pattern of sand particles in the shooting head and core box was reproduced with colored core sands. By incorporating the kinetic theory of granular flow(KTGF), kinetic-frictional constitutive correlation and turbulence model, a two-fluid model(TFM) was established to study the flow dynamics of the core shooting process. Two-fluid model(TFM) simulations were then performed and a areasonable agreement was achieved between the simulation and experimental results. Based on the experimental and simulation results, the effects of turbulence, sand density, sand diameter and binder ratio were analyzed in terms of filling process, sand volume fraction(αs) and sand velocity(Vs).

A SHOOTING METHOD FOR THE SWIFT-HOHENBERG EQUATION

Stationary even single bump periodic solutions of the Swift Hohenberg equation are analyzed. The coefficient k in the equation is found to be a critical parameter. It is proved if 0<k<1 , there exist periodic solutions having the same energy as the constant solution u=0; if 1<k<32 , there exist periodic solutions having the same energy as the stable states u=±k-1. The proof of the above results is based on a shooting technique, together with a linearization method and a scaling argument.

Analysis on Stochastic Passage Characteristics for Gun Barrel in Shooting Domain

Aiming at some weapon systems with shooting domain,the stochastic passage characteristics of the barrel were studied.On the basis of the exact definition of the stochastic passage characteristics,its opportunity-awaiting time,residence time and stochastic passage period were given by using the transition probability matrix,and they all obeyed the geometry distributions.Their means and variances were also derived,and the relations between the time indexes and the structure and parameters of weapon control system were established.Finally,the creditability of the conclusions was verified by the test data of weapon system in proving ground.

Scattering from Rough Surfaces Using the"Shooting and Bouncing Rays" Technique

The “shooting and bouncing rays” (SBR) technique is used to analyze the electromagnetic scattering characters of ocean rough surfaces varying with time. Some numerical results are presented and compared with the method of moments, and some factors, such as the incident angle, polarization and frequency are investigated which influence on electromagnetic scattering characters of ocean rough surfaces.

Numerical experiment of anharmonic oscillators by using the symplectic scheme-shooting method

Symplectic scheme-shooting method (SSSM) is applied to solve the energy eigenvalues of anharmonic oscillators characterized by the potentials V(x)=λx 4 and V(x)=(1/2)x 2+λx 2α with α=2,3,4 and doubly anharmonic oscillators characterized by the potentials V(x)=(1/2)x 2+λ 1x 4 +λ 2x 6, and a high order symplectic scheme tailored to the "time"-dependent Hamiltonian function is presented. The numerical results illustrate that the energy eigenvalues of anharmonic oscillators with the symplectic scheme-shooting method are in good agreement with the numerical accurate ones obtained from the non-perturbative method by using an appropriately scaled basis for the expansion of each eigenfunction; and the energy eigenvalues of doubly anharmonic oscillators with the sympolectic scheme-shooting method are in good agreement with the exact ones and are better than the results obtained from the four-term asymptotic series. Therefore, the symplectic scheme-shooting method, which is very simple and is easy to grasp, is a good numerical algorithm.

Shooting Back

A project that puts cameras in the hands of war’s youngest victims offers them away to tell—and show——their stories. Two million children dead.Six millionmaimed or mutilated.Ten million psychologicallydamaged.Such is the tragic tally,in the last decade,of the world’s wars.border skirmishes and ethnicconflicts.And it doesn’t stop there.According toa 1999 report by the U.N.’s Special Representativefor Children and Armed Conflict,more than

Spring a Surprise on Someone

Felix had just drifted off to sleep when the bed shook andsprung a surprise on him.“Ha,ha,” Chadwick laughed.“Thatsure woke you up.”Felix frowned.“You be careful or

Distribution of Soil-Bound Lead Arising from Rainfall-Runoff Events at Impact Berm of a Military Shooting Range

Surface runoff from rainfall event is an important indicator of metal mobility in soil, which may enhance non-point source contamination of soil. This study is designed to assess the mobility of soil-bound lead through simulated rainfall runoff experiment and its spatial distribution within the vicinity of a berm at a major military shooting range. Contamination was more significant at the impact area of berm, indicating threefold increase in Pb (17,500 ± 3811 μg/g) within a space of ten years. However, the non-impact area (459 ± 147 μg/g) was less contaminated. Other metals (Cu, Cd, Cr, Ni and Zn) analyzed were about background levels except for Cu at impact area. The enrichment ratio of Pb in runoff sediments was mostly high for the 0.43 mm sediment fractions independent of rainfall condition. Principal component analysis (PCA) biplot showed strong correlation between spatial distributions of metals around the vicinity of the berm (farmlands behind the berm) with concentrations on the impact berm soil. Surface runoff simulated on impact area soil had high concentrations of Pb (40.4 - 65.6 μg/mL) which could further lead to enrichment of soil-Pb levels within the vicinity of the berm. Decontamination measure is therefore required to minimize extensive contamination of surrounding soils of the impact berm due to rainfall runoff events.

The Lie-group Shooting Method for Radial Symmetric Solutions of the Yamabe Equation

We transform the Yamabe equation on a ball of arbitrary dimension greater than two into a nonlinear singularly boundary value problem on the unit interval[0;1].Then we apply Lie-group shooting method(LGSM)to search a missing initial condition of slope through a weighting factor r 2(0;1).The best r is determined by matching the right-end boundary condition.When the initial slope is available we can apply the group preserving scheme(GPS)to calculate the solution,which is highly accurate.By LGSM we obtain precise radial symmetric solutions of the Yamabe equation.These results are useful in demonstrating the utility of Lie-group based numerical approaches to solving nonlinear differential equations.

Reliability and Validity of the New Shooting Accuracy Measurement （SAM） System Software

The aim of this study was to investigate the reliability and validity of the New Shooting Accuracy Measurement Software （SAMS）. Thirty two male collegian soccer players performed three inner side kicking to the transparent goal construction. A High speed camera was placed at the back of the construction to determine where the ball contacted. Recorded video results were assessed with the SAMS and Kinovea software. To investigate test-retest reliability, three kicking results were examined twice by SAMS. Moreover kicking accuracy results obtained with SAMS were compared with results provided by Kinovea in order to investigate validity. Test-retest reproducibility of the new software was excellent, with Concordance Correlation Coefficient for distance to target （0.99, 0.99 and 0.99 respectively） and for angular degree of the ball （0.97, 0.99 and 0.99 respectively）, low Coefficients of Variation （between 2.10 to 6.33 for distance to target and 2.40 to 2.69 for angular degree） and random error （between _.＋ 0.55 to __＋ 3.44 for distance to target and ___ 0.63 to ___ 2.75 for angular degree）. Constant error （between 0.44 to 1.28 for distance to target and -1.16 to __. -2.51 for angular degree） and proportional error （between 0.97 to 0.98 for distance to target and 1.00 to 1.01 for angular degree） were very low for validity. In conclusion, the SAMS represents a valid and reliable instrument to measure accuracy of shooting to target.

A two-parameter multiple shooting method and its application to the natural vibrations of non-prismatic multi-segment beams

This paper presents an enhanced version of the standard shooting method that enables problems with two unknown parameters to be solved.A novel approach is applied to the analysis of the natural vibrations of Euler-Bernoulli beams.The proposed algorithm,named as two-parameter multiple shooting method,is a new powerful numerical tool for calculating the natural frequencies and modes of multi-segment prismatic and non-prismatic beams with different boundary conditions.The impact of the axial force and additional point masses is also taken into account.Due to the fact that the method is based directly on the fourth-order ordinary differential equation,the structures do not have to be divided into many small elements to obtain an accurate enough solution,even though the geometry is very complex.To verify the proposed method,three different examples are considered,i.e.,a three-segment non-prismatic beam,a prismatic column subject to non-uniformly distributed compressive loads,and a two-segment beam with an additional point mass.Numerical analyses are carried out with the software MATHEMATICA.The results are compared with the solutions computed by the commercial finite element program SOFiSTiK.Good agreement is achieved,which confirms the correctness and high effectiveness of the formulated algorithm.

GPU based numerical simulation of core shooting process

Core shooting process is the most widely used technique to make sand cores and it plays an important role in the quality of sand cores. Although numerical simulation can hopefully optimize the core shooting process, research on numerical simulation of the core shooting process is very limited. Based on a two-fluid model(TFM) and a kinetic-friction constitutive correlation, a program for 3D numerical simulation of the core shooting process has been developed and achieved good agreements with in-situ experiments. To match the needs of engineering applications, a graphics processing unit(GPU) has also been used to improve the calculation efficiency. The parallel algorithm based on the Compute Unified Device Architecture(CUDA) platform can significantly decrease computing time by multi-threaded GPU. In this work, the program accelerated by CUDA parallelization method was developed and the accuracy of the calculations was ensured by comparing with in-situ experimental results photographed by a high-speed camera. The design and optimization of the parallel algorithm were discussed. The simulation result of a sand core test-piece indicated the improvement of the calculation efficiency by GPU. The developed program has also been validated by in-situ experiments with a transparent core-box, a high-speed camera, and a pressure measuring system. The computing time of the parallel program was reduced by nearly 95% while the simulation result was still quite consistent with experimental data. The GPU parallelization method can successfully solve the problem of low computational efficiency of the 3D sand shooting simulation program, and thus the developed GPU program is appropriate for engineering applications.

Supremacy of Social Media in the Hebron Shooting Incident

The controversy in the case of Elor Azaria,an Israeli soldier who shot a Palestinian assailant in the Palestinian city of Hebron,after he was wounded and neutralized,led to a highly emotional public debate threatening a major crisis in the government and society.The incident divided the Israeli public and its leaders,with some expressing outrage over the killing of an incapacitated man,and others supporting even the most extreme response to a stabbing attack.The research argues that the role of governments in preventing exposure of security information was badly shaken following the inability to control information,as the incident was recorded on a mobile phone and uploaded to social media.As demonstrated in this case,local organizations have assumed a new prominence by providing information that previously had been limited by local authorities.The research is looking at the question of who was superior in the Hebron shooting incident:the army,the government,public opinion,traditional media or social media.The conclusions in this case are clear-cut:Social media dominated the entire process and determined its outcome,which was obvious once the video was uploaded on the Internet.

Shooting for Immortality

Some people kill others as well as themselves in the hope of achieving fame. Even more, some people seek spectacular displays of carnage. This danger is the focus of my essay. I argue that the pursuit of fame is able to generate mass killings because of a hope for personal immortality underlying the pursuit. Primarily through the work of Miguel de Unamuno and Ernest Becker, I argue that the hope for immortality is a powerful yet amoral impulse that is able to generate a lethal pursuit of fame. I argue that linking fame to one＇s social immortalization exacerbates the conflict already present in the pursuit of fame as well as enables the fame seeker to reduce all others to a means. Following my theoretical analysis, I turn to the iconic shootings at Columbine High School. The shootings offer a practical exemplification of how the pursuit of social immortalization can generate mass carnage. I argue that understanding the tragedy of Columbine as predicated upon a hope for social immortalization offers a template for destruction that ought to be considered when examining other, and all too frequent, instances of mass violence.