Understanding the spatio-temporal characteristics of water storage changes is crucial for the arid region of the Arabian Peninsula which is facing many challenges in water management inflicted by anthropogenic impacts and climate variability. Additionally, the scarcity of in situ measurements of soil moisture and groundwater, combined with intrinsic ''scale limitations'' of traditional methods used in hydrological characterization are limiting the ability to assess the region's water resources. The data used in this study includes; monthly gravity data from the Gravity Recovery and Climate Experiment (GRACE) mission and rainfall data from the Tropical Rainfall Measuring Mission (TRMM). The objective of this study was to apply remotely sensed data for the Arabian Peninsula to analyze the inter-annual and seasonal variability as well as changes in total water storage and precipitation, before finally exploring their spatially distributed - time lagged correlations which were directly related to drainage conditions, topography, and climatology.
In this paper, we propose a coverage planning algorithm for inspecting large complex structures using a quadrotor platform. Inspecting structures (e.g. bridges, buildings, ships, wind turbines, aircrafts) is considered a hard task for humans to perform, and of critical nature since missing any detail could affect the structure's performance and integrity. Therefore, the proposed method follows a model based coverage path planning approach that generates optimized path passing through a set of admissible viewpoints to fully cover a complex structure. The algorithm predicts the coverage percentage by using an existing model of the complex structure as a reference. We developed an optimized coverage path planning algorithm with a reward function that exploits our knowledge of the structure model, and the quadrotor's onboard sensors' models to generate optimized paths that maximizes coverage. Preliminary experiments were conducted on a simulated environment to test the validity of the proposed algorithm.
In this paper, we propose using Virtual impedance force as a haptic feedback in a haptic based teleoperation system for remote navigation, tracking and control of robotics system in indoor environments. The proposed method can increase the remote operation capacity of the robotics system in an uncertain environment. The system estimates the pseudo environment force that acts on the slave reflects it back to the control device for collision avoidance system. The designed and developed UAV platform is equipped with a laser range finder and an on-board computer that can communicate with the autopilot using MavLink protocol for multi channel communication. Experiment results on laboratory illustrate the effectiveness of the proposed method for real-time applications.
This paper proposes a multi objective optimization of a novel hybrid kinematics mechanism using planar 3PRR kinematics mechanism, to improve the mechanism performance. Workspace area, minimum eigenvalue across the workspace, and stiffness condition number across the workspace were chosen to be the objectives in the optimization based on their relevancy to the application of the mechanism. The multi objective optimization has been conducted by using multi objective genetic algorithm. It is shown that the multi objective optimization compromises the improvement of all objectives by providing non-dominated solutions.
Standard endoscopy is a screening method that allows the detection of GI tract lesions. However, it suffers from a significant miss-rate for cancer detection. Therefore, there is a need to establish a standard protocol that can quantify the quality of endoscopic procedures, assist physicians in analyzing their performance and train them on how to select navigation techniques that result in different levels of quality inspection. In this paper, we propose a method to evaluate the performance of endoscopists by analyzing the trajectory produced by the endoscopic camera. The proposed method consists of three major modules: i) the image analysis module for estimating camera positions; ii) Kalman filter for estimating velocity and acceleration profiles; and iii) analysis module to analyze the trajectory based on the density of observed images and the acceleration profile. The approach was preliminary tested with images collected from an ex-vivo experiments, with porcine tissue.
MEMS Accelerometer based on capacitive sensing principle is designed and analyzed using MEMS+ and Matlab. The design focuses on high sensitivity, linearity and low cross axis sensitivity. Preliminary results shows excellent displacement sensitivity of 0.0076?m/g and differential capacitive sensitivity of 55fF/g. The cross axis sensitivity is calculated to be 0.015fF/g.
Here we investigate the optimal finger design for low concentration thin film c-Si solar cells using 2D TCAD simulation. The Si cell studied has a 2?m absorber layer and 1?m emitter layer with 185?m finger spacing. We confirmed the TCAD model by matching 1 sun simulation to experimental data. The solar concentration studied is from 1 to 60 suns and the finger spacing is from 185?m to 1000?m. We observe that there is an optimal number of suns and finger spacing where the efficiency is maximized. Results show efficiency is maximized at 15 suns and 700?m finger spacing and with this design the efficiency increases from 14.68 % to 17.37%.
In this work, non-volatile MOS memory devices with two different charge trapping nanomaterials are studied. 16-nm InN nanoparticles and 4.4-nm graphene nanoplatelets are embedded in a ZnO charge trapping layer and their effect on the memory performance is analyzed using high-frequency C-V, retention and endurance measurements. The memory with InN nanoparticles showed enhanced retention characteristic due to the larger electron affinity of InN, however, the memory with graphene nanoplatelets showed larger memory window which indicates that graphene provide larger charge trapping states density. Moreover, the results show that the tunneling mechanism in the memory devices dictates the needed operating voltage.
The rapid advance in microscopy in the past few decades had enabled researchers to fabricate, manipulate and characterize materials in nano-scale. The fabrication of ultrasharp tips with an apex of few nanometers (thus called nanotips) had remarkably optimized the image resolution of Scanning Probe Microscopes and Electron Microscopes to reach the level of atomic resolution. With this advance, nanotip characterization using the conventional ring counting method had shown some limitation in terms of its accuracy and reliability. In this paper, we present the crystal ball models of nanotips to show the limitations of the ring counting method.
Nanomaterials have a promising future in various industries. However, the inadequate knowledge on the effects of these nanomaterials on humans and the environment has led scientists to further investigate these materials. One of the most abundantly used nanomaterials in the petrochemical industry is cerium dioxide (ceria). This report uses different solvents to synthesize ceria and then uses XRD and TPR to characterize cerium dioxide.
