Sol–Gel Spin Coating Growth of Magnesium-Doped Indium Nitride Thin Films on Different Substrates

We report on the growth of p-type indium nitride (InN) thin films on different substrates using a relatively simple and cost-effective sol-gel spin coating method. The precursors for the indium source and p-type dopant were indium nitrate hydrate and magnesium chloride 6-hydrate powders, respectively. The structural, morphology, and optical properties of p-type InN thin films grown on different substrates were investigated. X-ray diffraction patterns revealed that the deposited Mg-doped InN thin film on GaN/AlN/Si(111) template show polycrystalline wurtzite structure with a strong InN(002) orientation and have a good crystallinity. Field emission scanning electron microscopy images and energy dispersive X-ray results showed that all the films exhibit densely packed surface morphology with hexagonal-like grains shape and low oxygen percentage with almost 1:1 ratio of indium to nitrogen. Moreover, two Raman-active modes of E2(High) and A1(LO) of the wurtzite InN were clearly observed for all samples. The ultraviolet-visible-near infrared spectroscopy results showed that the energy bandgap of the Mg-doped InN thin films was in the range of 1.62-1.66 eV. From all the results, it can be concluded that the Mg doped InN film on GaN/AlN/Si(111) substrate has better crystalline quality as compared to that of other substrates

Obstacle Avoidance Using Convolutional Neural Network For Drone Navigation In Oil Palm Plantation

In Malaysia, oil palm plantation is one of the vital sectors that contribute to the country economy. In recent years, drones are widely applied in the precision agriculture due to their flexibility and capability. However, one of the challenges in a low-altitude flight mission is the ability to avoid the obstacles in order to prevent the drone crashes. Most of the previous literature demonstrated the obstacle avoidance systems with active sensors which are not applicable on small aerial vehicles due to the cost, weight and power consumption constraints. In this research, we present a novel system that enables the autonomous navigation of a small drone in the oil palm plantation using a single camera only. The system is divided into two main stages: vision-based obstacle detection, in which the obstacles in the input images are detected, and motion control, in which the avoidance decisions are taken based on the results from the first stage. As the monocular vision does not provide depth information, a machine learning model, Faster R-CNN, was trained and adapted for the tree trunk detection. Subsequently, the heights of the predicted bounding boxes were used to indicate their estimated distances from the drone. The detection model performance was validated on the testing images in term of the average precision. In the system, the drone is programmed to move forward until the detection model detects any closed frontal obstacle. Next, the avoidance motion direction is defined by commanding a yawing angle which is corresponded to the x-coordinate in the image that indicated the optimum path direction with the widest obstacle-free space. We demonstrated the performance of the system by carrying out flight tests in the real oil palm plantation environment in two different locations, where one of them is a new place. The results showed that the proposed method was accurate and robust for the drone vision-based autonomous navigation in the oil palm plantation

Investigation on the use of iron and steel for restoration purposes during 19th and 20th century

Since the earliest times, wrought iron cramps and dowels were used in the traditional masonry structures to secure stones which might be prone to movement or displacement. In the period between the late 19th century and the early 20th century, masonry-clad buildings are exploded to use. However, due to the porous nature of the mortar and the inconsistent fill around the steel members, the protective oxide film is lost over time, resulting in corrosion of the steel framing and other embedded metals. The metals which are used for historical construction are cast iron, steel and wrought iron. The causes of metal deterioration are corrosion, mechanical breakdown, weathering and connection failure. The traditional restorations are repair, replacement and jointing method. And new, a new method, cathodic protection, is also applied on historical building restoration. New materials began to be used for replacing the original materials, The most common have been aluminum, epoxies, reinforced polyester, glass fiber-reinforced concrete and titanium. The first cathodic protection system for stone clad steel framing was installed in 1991. Cathodic protection (CP) prevents corrosion by converting all of the anodic sites on the metal surface to cathodic sites by supplying electrical current from an alternate source. Different from the traditional way, CP method does not to remove the masonry and install new masonry back. According to Roberto Pane, the extreme variety of cases and the need for safeguarding a large amount of monuments shows that restoration can not be constrained within stiff limits .As a conclusion of this studying, due to the former experience, the Barcelona Cathedral’s façade can be considered to use the CP method for restoration blend with the old with regard to size, scale and appearance

Load monitoring and output power control of a wireless power transfer system without any wireless communication feedback

For mid-range wireless power applications, the load is normally far away from the power source. In this project, a new method is proposed to determine the load impedance and load power without using any direct output feedback. Based only on the information of the input voltage and current, the load impedance and load power can be monitored and controlled without using any wired or wireless feedback from the load. This new method can therefore eliminate the need for any directly measured output feedback, which was previously thought to be essential. It also makes the power control of a wireless power transfer very simple. The concept is verified by the comparison between the computed results and practical results of an 8-ring domino wireless power transfer system. A good degree of accuracy has been achieved in the verification. 2013 IEEE.published_or_final_versio

A new algorithm for instantaneous speed and position estimation of surface-mounted permanent magnet synchronous motors

Session 5-5: Motor Drives II: paper 5-5-1This paper describes a patent-pending method that can be used to estimate the speed and position of surface-mounted permanent magnet synchronous motors (SMPMSM) with cylindrical rotor structure and sinusoidal back emf. The concept involves the use of the power inverter's switching actions and switching current to provide instantaneous real-time information for extracting the speed information. The theory and algorithm are included to explain the proposed concept, which has been verified by simulations on a SMPMSM drive under the control of a sensorless speed control scheme. © 2013 IEEE.published_or_final_versio

Monitoring of multiple loads in wireless power transfer systems without direct output feedback

In this paper, a computational method that uses only the input voltage and current to identify the impedances of multiple loads in wireless power transfer systems without any direct load measurements is proposed. The method has been practically realized in a wireless power domino-resonator system comprising 8 resonators. A good degree of accuracy has been achieved in the practical verification. Although the method is demonstrated in a relatively complex system, the principle applies to any wireless power transfer system with 3 or more coil-resonators. Without the requirements for direct load measurements, control circuitry of a wireless power transfer system with multiple loads can avoid the needs for using wireless communication system for feedback purposes. © 2014 IEEE.published_or_final_versio

Front-End Monitoring of Multiple Loads in Wireless Power Transfer Systems Without Wireless Communication Systems

5siThis paper describes a method for monitoring multiple loads from the front end of a wireless power transfer system without using any wireless communication systems. A mathematical approach based on scanning the frequency around the resonant frequency has been developed for deriving the load conditions. The proposal requires only information of the input voltage and current, thereby eliminating the requirements of using wireless communication systems for feedback control. The proposal has been practically confirmed in hardware prototype with good results.reservedmixedYin, J.; Lin, D.; Lee, C. K.; Parisini, T.; Hui, S. Y. R.Yin, J.; Lin, D.; Lee, C. K.; Parisini, Thomas; Hui, S. Y. R

Nickel hydroxide/chemical vapor deposition-grown graphene/nickel hydroxide/nickel foam hybrid electrode for high performance supercapacitors

Rational design of electrode structures has been recognized as an effective strategy to improve the electrochemical performance of electrode materials. Herein, we demonstrate an integrated electrode in which nickel hydroxide (Ni(OH)2) nanosheets are deposited on both sides of chemical vapor deposition-grown graphene on Ni foam, which not only effectively optimizes electrical conductivity of Ni(OH)2, but also accommodates the structural deformation assciated with the large volume change upon cycling. The synthesized Ni(OH)2/graphene/Ni(OH)2/Ni foam electrode exhibits a high specific capacity of 991 C g−1 at a current density of 1 A g−1, which is higher than the theoretical specific capacity of additive sum of Ni(OH)2 and graphene, and retains 95.4% of the initial capacity after 5000 cycles. A hybrid supercapacitor is constructed by using Ni(OH)2/graphene/Ni(OH)2/Ni foam as the positive electrode and activated carbon on Ni foam as the negative electrode, which achieves a maximum energy density of 49.5 W h kg−1 at a power density of 750 W kg−1, and excellent cycling lifespans with 89.3% retention after 10000 cycles at 10 A g−1