Localization of an Autonomous Mobile Robot Based on Ultrasonic Sensory Information

Based on ultrasonic sensory information, an approach is proposed for localization of autonomous mobile robot (AMRs). In the proposed method, it will be proven that the combination of three ultrasonic transmitters and two receivers can determine both the position and the orientation of an AMR with respect to a reference frame uniquely. In this manner, since only ultrasonic sensors are used, the proposed method will be highly cost-effective and easy to implement. To show the validity and feasibility of the proposed method, the hardware configuration and a series of experiments will be given for illustration.     

Exploring the Mechanism of Surface and Ground Water through Data-Driven Techniques with Sensitivity Analysis for Water Resources Management

The over extraction of groundwater in central-western and southwestern Taiwan has resulted in serious land subsidence for decades. For making countermeasures in response to land subsidence, this study collects long-term hydrological data to explore the relationships between surface water and groundwater in various monitoring stations, and then constructs one-month-ahead forecast models by using data-driven techniques for the water resources management of the Zhuoshui River basin in Taiwan. The results demonstrate that the constructed models can accurately forecast monthly groundwater levels. The sensitivity analysis is next conducted on the input variables of the constructed models by using the partial derivative method. The analysis results reveal that streamflow is a predominant factor for groundwater level variation, and therefore streamflow management made by the upstream weir of the river would influence groundwater level variations. This study further implements several scenario analyses based on the interactive mechanism between groundwater and surface water in response to future climatic conditions and weir discharge management, respectively. The results of scenario analyses indicate that the groundwater recharge zone spreads along the Zhuoshui River while lateral and vertical recharge sources would cause different quantities and distribution patterns of groundwater recharge. Besides, an increase in weir discharge would improve groundwater recharge quantities with groundwater level variations at 0.12 m and 0.06 m in wet and dry seasons, respectively. As a consequence, the operation of weir discharge would play an import role in sustainable development of water resources management in the study area.     

Dipole antenna coaxially mounted on a conducting cylinder

The problem of a cylindrical dipole antenna symmetrically mounted on a conducting coaxial cylinder is analyzed both theoretically and experimentally. The theoretical approach is based on the Fourier transform solution for thin wire antennas, equivalence and image principles, point matching, and numerical optimization. The basic idea is that the modified dipole structure can be replaced by an equivalent system (as far as exterior fields are concerned) consisting of a simple perfectly conducting rod excited by an array of magnetic ring sources. The coefficients of these sources are then adjusted to match boundary conditions on the cylindrical modification surface. For the locations of the match points and sources, three gauges involving weighted integrals of the tangential electric fields are used to optimize the solution. Good agreements between measurement and theory have been obtained for the input admittances, resonance properties, and radiation patterns. Results are also presented for a dipole on a sphere to contrast effects due to change in modification shape.     

Investigation of phases and stability of solid electrolytes in the NASICON system

In order to study the phase change and stability of the NASICON structure, sodium, lithium and magnesium ions were chosen to substitute the zirconium ion at octahedral sites in the NASICON network. It was found that the zirconium ion can not be replaced by these ions. All the synthesized products are Na_1+xZr₂Si_xP_3?xO₁₂ and phosphate salts. NASICON immersed in liquid sodium at 300°C also results phosphate salt and ZrO₂. It was found that an appropriate excess of sodium phosphate in NASICON will improve the chemical stability, corrosion against sodium and mechanical properties.     

Determination of the long term corrosion behavior of coated steel with A.C. impedance measurements

A previous study of the a.c. impedance of thin polymer films on aluminum alloys, steel, and phosphated steel, determined over a wide frequency range, has resulted in a general model for the electrochemical impedance across the coated surfaces. According to this model, penetration of the coating by the electrolyte results in an impedance behavior which is typical of a dielectric film short-circuited by conducting electrolytic paths perpendicular and parallel to the polymer/metal interface. Comparison of the time dependence of the impedance of coated steel substrates with the impedance across a free film has demonstrated that the corrosion of the substrate enhances the development of parallel paths of ionic conduction in the coating. A.c. impedance measurements carried out on polybutadiene-coated steels pretreated by different procedures determine quantitatively the resistance R_p of the conducting paths. The time dependence of R_p for the coated substrates has been determined for exposure periods of up to three weeks. Visual observation of the corroded and delaminated areas according to ASTM D610 has been carried out simultaneously, and correlations have been established with R_p. The results are discussed in terms of the possibility to predict the corrosion behavior of a coated metal, based on the measurement of R_p.     

Membrane performance enhancer evaluations on pilot- and full-scale membrane bioreactors

Recently developed polymeric membrane performance enhancer product, MPE50, was tested in various pilot‐ and full‐scale membrane bioreactors (MBRs). The Initial MPE50 dosage was determined by visual jar tests and by using various bench‐top filtration tests. Different amounts of MPE50 were dosed, and the particle size and supernatant clarity of the mixed liquor were monitored visually. Bench‐top filtration tests were also conducted. A 50% higher MPE50 dosage is recommended to be added to the pilot/full‐scale bioreactors because, based on experience, some of the soluble microbial products in the mixed liquor do not completely react with polymer during the relatively short bench‐test mixing time interval. With the addition of 400 mg/L MPE50 to a pilot MBR, the design flow was increased twofold without any significant transmembrane pressure (TMP) increase for 1 day. The control TMP surged within a few hours without MPE50. Long‐term field trials in a full‐scale plant also showed a substantial flux increase. In addition to flux enhancement, MPE50 helped to remove foam from the bioreactors and improved plant aesthetics, safety and general operating performance.     

Morphological and Microstructural Aspects of Metal Dusting on 304L Stainless Steel with Different Surface Treatments

The effect of surface treatment on the susceptibility to metal dusting of 304L stainless steel (SS) exposed in a mixed gas of CO/CO₂ = 100/1 in the temperature ranging from 500–700 °C was investigated. Thermogravimetric analyses (TGA) and long-term exposure tests in the above environments, followed by surface-morphological examination and cross-section chemical composition and microstructure analyses were conducted. The results showed that the decomposition of CO gas to form graphite and nano-sized carbon filaments was affected by the surface pre-treatment applied on the 304L SS. Enhanced carbon deposition but with a significant resistance to metal dusting was found on the sand-blasted 304L SS. The existence of an initial non-protective oxide on the pre-oxidized 304L SS surface, however, gave rise to the highest susceptibility to metal-dusting-associated-localized attack. The roles of different surface treatments on the reactions between 304L SS and the exposing gas environment are discussed.     

Synthesis and thermal properties of block copolyetheresters with poly(pentamethylene p,p′-bibenzoate) segments

The block copolyetheresters with hard segments of poly(pentamethylene p,p-bibenzoate) and soft segments of poly (tetramethylene ether) were prepared by melt polycondensation of dimethyl-p,p-bibenzoate, 1,5-pentanediol and poly (tetramethyene ether) glycol (PTMEG) with molecular weights of 650, 1000 and 2000. The results by NMR indicate that the polymer composition is determined by the charge molar ratio (x) of PTMEG to dimethyl-p,p-bibenzoate. The thermal transitions of the block copolyetheresters were investigated by DSC in combination with X-ray diffraction and polarized microscopy. Some block copolyetheresters exhibit a monotropic smectic phase due to the presence of the poly (pentamethylene p,p-bibenzoate) segments. As the molar content of PTMEG increases, the average sequence length of the polyester segments decreases, the isotropic-smectic transition temperature and the smectic order decrease accordingly. When x is as high as 0.3, the block copolyetheresters exhibit no liquid crystallinity.     

The spiral flow analysis on the injection molding of alumina powder — An experimental design

A spiral flow analysis based on the McLean-Anderson design method was conducted in studying the influence of each formulation component on the flow of alumina feedstocks. The mixtures were composed of alumina powder (AL), polypropylene resin (PP), paraffin wax (PW) and stearic acid (SA). Fourteen different formulations were designed and tested. The spiral flow distance (SFD) of each formulation as a function of ingredient concentration was measured and analyzed. The studied ranges of AL, PP, PW and SA were 87–89, 5–9.25, 3–7.25 and 0.75–1.5 wt%, respectively. It is observed that lower alumina content or higher binder content would obtain longer SFD of feedstocks. Both PW and SA are more effective than polypropylene (PP) in enhancing SFD. For alumina content less than 88%, PW is the most effective one. In contrast, SA becomes the most effective when the powder loading is higher than 88%.     

Synthesis of chiral polymers having camphanediol moieties and their applications on the optical resolution of some racemates

Optically active exo-exo-2,3-camphanediol (CPO) (3) was synthesized from (+)-camphor. Chiral polymers poly(CPO-co-TDI) ( 6 ) and poly(CPO-co-IPDI) ( 7 ) were synthesized by the step polymerization of chiral compound CPO ( 3 ) with toluene-2,4-diisocyanate (TDI) and isophorone diisocyanate (IPDI). To investigate the stereo structure of the chiral polymers, two kinds of model compounds, exo-exo-2,3-di[(phenylamido)oxy]camphane ( 4 ) and exo-exo-2,3-di[(propylamido)oxy]camphane ( 5 ), related to polymers ( 6 ) and ( 7 ) were synthesized. Chiroptical characteristics and stereo structures of the chiral polymers were investigated using a circular dichroic spectrometer. The results obtained in this investigation suggest that the chiral polymers ( 6 ) and ( 7 ) have no one-handed helix conformation. The optical resolution ability as chiral adsorbent for HPLC of the chiral polymers was investigated. It was found that chiral polymers ( 6 ) and ( 7 ) are effective for the optical resolution of some racemates. © 1995 John Wiley & Sons, Inc.