A SiC MEMS Resonant Strain Sensor for Harsh Environment Applications

In this paper, we present a silicon carbide MEMS resonant strain sensor for harsh environment applications. The sensor is a balanced-mass double-ended tuning fork (BDETF) fabricated from 3C-SiC deposited on a silicon substrate. The SiC was etched in a plasma etch chamber using a silicon oxide mask, achieving a selectivity of 5:1 and etch rate of 2500 Aring/min. The device resonates at atmospheric pressure and operates from room temperature to above 300degC. The device was also subjected to 10 000 g shock (out-of-plane) without damage or shift in resonant frequency. The BDETF exhibits a strain sensitivity of 66 Hz/muepsiv and achieves a strain resolution of 0.11 muepsiv in a bandwidth from 10 to 20 kHz, comparable to state-of-the-art silicon sensors     

Fuzzy control of environmentally conscious refrigeration systems

This paper introduces the reader to the concepts of fuzzy sets and fuzzy logic and to their capabilities in the area of control systems. To understand the capabilities of fuzzy logic in real-time controller design, a controller for an environmentally conscious refrigeration system was designed and implemented. Initial results show that a fuzzy logic controller is easy to implement, does not need an exact system model, does not need precise and expensive hardware, and deals with human concepts in a fairly natural and obvious way. This would be, hopefully, a potential avenue for future production of intelligent manufactured products.     

Thermal characterization of polylactides

Three important thermal characteristics of polylactides have been measured and discussed. These are glass transition temperature, melting temperature, and degradation behaviour. The glass transition temperatures at infinite molecular weight for - and -optical isomers were 58 and 57°C, respectively. Melting temperature for the crystalline -isomer was 184°C at infinite molecular weight. Number-average molecular weight, melt viscosity, differential scanning calorimetry, infra-red analysis and thermogravimetric analysis were used to study the degradation behaviour under different conditions. Polylactides were found to be highly sensitive to heat, especially at temperatures higher than 190°C. Most of the degradative reactions were thought to involve the highly concentrated ester bond on the main chain. These reactions included thermohydrolysis, depolymerization and cyclic oligomerization, intermolecular and intramolecular transesterifications. Low molecular weight compounds associated with the polymer seemed to play an important role in lowering the molecular weight at high temperatures, as well as the hydroxyl end group of the main chain. The compounds include water, monomers, oligomers, and polymerization catalysts. Removal of the non-polymeric contents and blocking the hydroxyl end-group enhanced the thermal stability of the polymers. The increased amount of the polymerization catalyst in the end product contributed to the degradative reactions.     

Robot manipulator control for hazardous waste-handling applications

The U.S. Department of Energy has identified robotics as a major technology to be utilized in its program of environmental restoration and waste management, and in particular has targeted robotic handling of hazardous waste to be an essential element in this program. Successful performance of waste-handling operations will require a robot to perform complex tasks involving both accurate positioning of its end effector and compliant contact between the end effector and the environment, and will demand that these tasks be completed in uncertain surroundings. This article focuses on the development of a robot control system capable of meeting the requirements of hazardous-waste-handling applications and presents as a solution an adaptive scheme for controlling the mechanical impedance of kinematically redundant manipulators. The proposed controller is capable of accurate end effector impedance control and effective redundancy utilization, does not require knowledge of the complex robot dynamic model or parameter values for the robot or the environment, and is implemented without calculation of the robot inverse kinematic transformation. Computer simulation results are given for a 4 degree of freedom redundant robot under adaptive impedance control. These results indicate that the proposed controller is capable of successfully performing tasks of importance in robotic waste-handling applications.     

Reduction of cobalt oxide with methane

The present work deals with reduction of cobalt oxide, CoO, with methane. Thermogravimetry was used for finding kinetic parameters of the reduction reaction. The reaction of cobalt oxide with methane was carried out in the temperature range 800 °C to 950 °C at atmospheric pressures with porous pellets prepared from cobalt oxide powder with a mean particle size of 10.6 μm. Assuming that the reaction is first order with respect to methane concentration, the activation energy is f6ound to be 155 kJ/mol (±20).     

Feature Fusion Models for Deep Autoencoders: Application to Traffic Flow Prediction

ABSTRACT

Due to reduction in dimensionality and extraction of the definitive features of input data, deep architectures have achieved significant success in various machine learning applications. Considering their successful applications in speech recognition and image classification, the main goal of this research is to investigate the performance of the sparse autoencoders utilized in regression analysis. To this end, deep sparse autoencoders with the standard method of training, cascaded, and partially cascaded architectures, fed with the fusion of low- and high-level features, are proposed and implemented. The regression task is to forecast the vehicular flow rate of a location on an arterial highway using different traffic variables of several locations ahead in the Twin Cities Metro area of Minneapolis. The results demonstrate that the partially cascaded model exhibits advancements in yielding more accurate results than the other two architectures fed with the features that correlate the most to the traffic flow rate.     

Comparability Analyses of the <Emphasis Type="Italic">SPI</Emphasis> and <Emphasis Type="Italic">RDI</Emphasis> Meteorological Drought Indices in Different Climatic Zones

Comparability analyses are performed to investigate similarities/differences of the standard precipitation index (SPI) and the reconnaissance drought index (RDI), respectively, utilizing precipitation and ratio of precipitation over potential evapotranspiration (ET ₀). Data are from stations with different climatic conditions in Iran. Drought characteristics of the 3-month, 6-month and annual SPI and RDI time series are developed and Markov chain order dependencies are investigated by the Log-likelihood, AIC and BIC tests. Steady state probabilities and Markov chain characteristics, i.e., expected residence time in different drought classes and time to reach “Near Normal” class are investigated. According to results, both indices exhibit an overall similar behaviour; particularly, they follow the first order Markov chain dependency. However, climatic variability may produce some differences. In several cases, the “Extremely Dry” class has received a more critical value by RDI. Furthermore, the expected residence time of “Near Normal” class and expected time to reach “Near Normal” class are quite different in a number of cases. The results show that the RDI by utilizing the ET ₀ can be very sensitive to climatic variability. This is rather important, since if the drought analyses are for agricultural applications, utilization of the RDI would seem to serve a better purpose.     

Fuzzy Adaptive Control for a UAV

In this paper a combination of Fuzzy Logic Control (FLC) and Model Reference Adaptive Control (MRAC) will be developed to stabilize and control a fixed-wing unmanned aerial vehicle (UAV). The control must be able to direct the airplane towards different waypoints while at the same time maintaining the UAV stable. Also, the control should be transferable to similar UAV models with little to no change to the algorithm.     

Light-Actuated AC Electroosmosis for Nanoparticle Manipulation

We present a novel light-actuated ac electroosmosis (LACE) mechanism that allows the concentration and transportation of micro- and nanoscopic particles using light-patterned dynamically reconfigured microfluidic vortices on a photoconductive surface. LACE is realized by sandwiching an aqueous liquid medium between a featureless photoconductive surface and a transparent indium tin oxide electrode. By applying an ac electrical bias with a frequency that is close to the electric double-layer relaxation frequency, a light-patterned virtual electrode can induce ac electroosmotic flow to concentrate and transport nanoscopic particles on the photoconductive surface. By integrating with a spatial light modulator such as a digital micromirror device microdisplay, we can create 31000 microfluidic vortices on a 1.3 times 1-mm² area for massively parallel trapping of 2- and 1-mum polystyrene beads. We have also demonstrated LACE concentration and transportation of nanoscopic particles including 200- and 50-nm polystyrene beads, lambda-phage DNA molecules, and quantum dots.