Outdoor Autonomous Landing of a Quadcopter on a Moving Platform using Off-board Computer Vision

 This paper presents a method that enables a quadcopter to perform autonomous landing on a moving platform using computer vision. In addition, the system implementation of the computer vision technique is presented. Unlike other researches, the camera is mounted on the moving platform instead of being installed on the quadcopter. Besides, the computer vision system is tested outdoor, and the results such as the performance and the accuracy are presented. In the stationary platform test, 5 out of 10 landings fall within 30 cm from the center. In the moving platform test, the maximum platform-moving speed for autonomous landing is 2 m/s. Hence, it is proven that this methodology is feasible. Lastly, the advantages and limitations of the computer vision technique proposed are discussed

Prediction of Roughness Heights of Milled Surfaces for Product Quality Prediction and Tool Condition Monitoring

The objective of this research is to predict the roughness heights of milled surfaces, which indicates product quality and tool conditions. Two experiments are carried out to evaluate relevant factors such as vibration, force, and surface roughness. The purpose of the first experiment is to find out the limits of the machining variables compared to the constraints of the materials. The purpose of the second experiment is to identify, collect, and compare how each factor affects product quality and tool conditions. Based on this study, the vibration, force, and surface roughness are good indicators for tool conditions. When the magnitudes of the vibration and force increase, the surface roughness also increases. The increase in surface roughness with constant cutting parameters indicates the degrading of product quality and the decrease of the tool life. Thus, the variables, such as vibration and forces, are used as the inputs, and the surface roughness is used as the output of neural networks. By optimizing the network variables, it has been found that a 4,4,8,1 neural network can achieve the least absolute error, and accurately predict the actual roughness heights collected from the experiment. The minimum error of the prediction of surface roughness is 0.11%, the average error is 2.11%, and the maximum error is 6.98%. The prediction of surface roughness of milled surfaces is very important for the product quality prediction and tool condition monitoring

Evolutionary in Solid State Recycling Techniques of Aluminium: A review

AbstractThis paper provides an intensive review on past and current research works in solid state recycling of aluminium and its alloys. The review relates the extrudates quality of the solid state recycled aluminium to certain aspects noted as chips preparation, reinforced materials addition, die geometry, processing parameters, and performance of miscellaneous solid state recycling techniques. Finally, concluding remarks underline challenges for aluminium recycling by the solid state and also highlight the potential future work on making the method as a promising alternative for sustainable manufacturing and hence technologically feasible for industrial implementation

Investigation of Roll-to-Roll Gravure Printing for Printed Electronics with Fine Features

Gravure printing is known to be cost competitive in manufacturing of printed electronic devices due to its capability to mass produce at lower costs. Current standard of gravure printed feature sizes is in a range of around 50 μm down to sub-10 μm, predominantly through small scale setups and specialized engraving. However, reliance on gravure cell design limits the scalability of printing over a large area due to the setup cost. In this study, ink viscoelastic behavior was modified to improve replication of gravure printed features over a large printing area of 300 mm web-width without a reduction in gravure cell dimension. Fine lines were printed using a high viscosity ink with a good replication of the nominal line width. Control over the printed features was performed through the variation of printing speed and the alteration of ink viscosity. The effects of ink viscosity and printing speed on the printed ink particle distribution and size were also examined. New methodologies of characterizing ink transfer were also developed to help understand the ink transfer processes: mass transfer and particle transfer. A deeper understanding of the thixotropic effect and shear recovery behavior of inks was achieved through simulations of shearing conditions

A Study of the Intermetallic Compound Growth in Flip-Chip Packages under Thermal Loading

 The intermetallic compound layers in solder bumps have the brittle feature and can easily fracture under thermal or mechanical loading. Therefore, the intermetallic compound is an issue for the fracture reliability of the solder bumps. In this work, the intermetallic compound growth before and after high temperature storage tests was investigated. The experiment results revealed that the solder bumps with nickel layers could reduce the intermetallic compound growth rate. The nickel layer, which was added in between Cu and SnAg for top solder bumps, was an important factor controlling the intermetallic compound thickness. It was hard to tell the intermetallic compound thickness at time zero; at the time of 147 hours, the intermetallic compound grew to 3.25 µm; at the time of 294 hours, the intermetallic compound grew to 5.25 µm. However, the solder joints were still in good condition

Numerical Analysis of Crack Propagation Path Using an Advanced Element Cracking Method

The determination of the crack path is important for predicting the unexpected failures or assessing fatigue life in engineering material. To simulate the crack path under mixed mode loading using a finite element model, a new local element cracking technique was proposed. The waiting cracking element was divided into two units along crack propagation direction based on the maximum circumference ( 0) KII criterion. Then, the information of element number and nodal number was also modified and singular elements were avoided by the transfixion method. With advantages of small remeshing only on a local region, this method also examined three classic problems of stationary crack growth, i.e., edge crack propagation in double cantilever beam, mode I cracking in an asphalt concrete beam, a crack in typical longitudinal connection of large natural gas carriers. The calculated stress intensity factors and the predicted crack trajectories using this method agree well with the theoretical solutions existing in literature. Optimal design of structure against failure by fast fracture is discussed.Определение траектории трещины является важным при прогнозировании непредвиденного разрушения или при оценке усталостной долговечности конструкционного материала. Предложен новый метод моделирования траектории локальной трещины при нагружении смешанного типа с помощью модели, основанной на методе конечных элементов. Элемент, моделирующий трещину, разбивают на два вдоль распространения трещины с использованием критерия максимальных касательных напряжений (KII 0). Затем изменяется информация о номерах элемента и узла, поскольку метод трансфикции исключает использование сингулярных элементов. Преимущества незначительного перестроения конечноэлементной сетки только в локальной зоне позволили исследовать с помощью предложенного метода три классические проблемы роста стационарной трещины, т.е. распространение краевой трещины в двухконсольной балке, моделирование трещинообразования в асфальтобетонных балках и трещина в стандартном продольном соединении в газопроводе. Расчетный коэффициент интенсивности напряжений и траектория трещины, спрогнозированная с помощью описанного метода, хорошо соответствуют теоретическим данным, представленным в литературных источниках. Рассмотрена оптимальная конструкция структуры, которой несвойственно быстрое разрушение.Визначення траєкторії тріщини є важливим при прогнозуванні непередбачуваного руйнування або при оцінці довговічності від утомленості конструкційного матеріалу. Запропоновано новий метод моделювання траєкторії локальної тріщини під час навантаження змішаного типу за допомогою моделі, що базується на методі скінченних елементів. Елемент, що моделює тріщину, розбивають на два вздовж поширення тріщини з використанням критерію максимальних дотичних напружень ( ). KII 0 Далі змінюється інформація щодо номерів елемента і вузла, оскільки метод трансфікції виключає використання сингулярних елементів. Переваги незначної перебудови скінченноелементної сітки тільки в локальній зоні дозволили за допомогою запропонованого методу дослідити три класичні проблеми росту стаціонарної тріщини: поширення краєвої тріщини в двоконсольній балці, моделювання тріщиноутворення в асфальтобетонних балках і тріщина в стандартному поздовжньому з’єднанні у газопроводі. Розрахунковий коефіцієнт інтенсивності напружень і траєкторія тріщини, спрогнозована за допомогою описаного методу, добре відповідають теоретичним даним, представленим у літературних джерелах. Розглянуто оптимальну конструкцію структури, якій невластиве швидке руйнування

Debinding process of ss316L metal injection moulding under argon atmosphere

Solvent and thermal debinding acted as binder in removing Restaurant Waste Lipid (RWL) and Polypropylene (PP) from the stainless steel 316L. This investigation was carried out to determine the effect of thermal debinding variables on density, shrinkage and surface morphology of the brown parts other than to remove the binder from the SS316L under the Argon atmosphere with flow rate of 5 ml/min. The parameter used for solvent debinding process was solvent temperature at 60°C for six hours, while thermal debinding process was conducted at various temperature of 400°C, 500°C and 600°C, heating rate of 10 °C/min, 20 °C/min and 30 °C/min, dwell time of 30 min, 60 min and 90 min, and cooling rate of 5 °C/min, 10 °C/min and 15 °C/min. Analysis of weight loss percentage was done on the brown part after the solvent debinding and thermal debinding processes. Scanning Electron Microscope (SEM) was used to confirm the removal of RWL and PP from the compacts based on the porosity form, and attachment of PP in the powder particles. This investigation showed that debinding parameters were important in terms of their effects on the physical properties. Based on the observation through SEM and consideration of the factors that affected the physical properties of the parts, it was found that RWL was completely extracted out at 60°C for six hours, while the thermal temperature of 500°C with heating rate of 10 °C/min, dwell time of 60 min and cooling rate of 15 °C/min were the optimal thermal debinding parameters in PP removal

Longitudinal broadening of near side jets due to parton cascade

Longitudinal broadening along $\Delta\eta$ direction on near side in two-dimensional ($\Delta\phi \times \Delta\eta$) di-hadron correlation distribution has been studied for central Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV, within a dynamical multi-phase transport model. It was found that the longitudinal broadening is generated by a longitudinal flow induced by strong parton cascade in central Au+Au collisions, in comparison with p+p collisions at $\sqrt{s_{NN}}$ = 200 GeV. The longitudinal broadening may shed light on the information about strongly interacting partonic matter at RHIC.Comment: 5 pages, 4 figures; accepted by Eur. Phys. J.