Lewis acid catalyzed diesel‐like fuel production from raw corn oil

The pyrolysis of raw corn oil in the absence and presence of Lewis acids was carried out at 500°C. The catalytic effect of AlCl₃ was better than that of FeCl₃. The physico‐chemical properties of diesel‐like fuels produced by Lewis acid catalyzed are close to that of commercial diesel fuel. The diesel‐like fuels obtained from catalytic runs can be evaluated as diesel fuels. Copyright © 2008 John Wiley & Sons, Ltd.     

Reassessment of Al-Ce and Al-Nd binary systems supported by critical experiments and first-principles energy calculations

The present study reinvestigates the Al-Ce and Al-Nd phase diagrams and reoptimizes their thermodynamics using the CALPHAD method. First-principles energy calculations play an important role in terms of sublattice formalism and phase-stability prediction, demonstrating that they should be effectively integrated into experimental investigations and thermodynamic assessments. Specifically, current experimental results and theoretical calculations show that Al₂Nd (or Al₂Ce) should be treated as a stoichiometric compound phase rather than as the solution phase that was proposed in previous studies. Further, a new compound, AlCe₂, is found stable at high temperatures (648 °C to 775 °C) in the Al-Ce system. It forms through a peritectic reaction of liquid and AlCe phases at 775 °C, and decomposes into AlCe and βAlCe₃ at 648 °C and below. Since the AlCe₂ phase is not retained at room temperature by quenching experiments, it is suggested that AlCe₂ may be isostructural with the previously known compound AlNd₂ (oP12). Based on current differential thermal analysis (DTA) measurements and theoretical calculations, it is also proposed that there is an α/βAl₃Ce polymorphous transition occurring at 973 °C in the Al-Ce system and an α/βAl₃Nd polymorphous transition occurring at 888 °C in the Al-Nd system. The βAl₃RE phase may be isostructural with βAl₃Y (hP12). Finally, the previously described βAl₁₁RE₃ phase (rare earth elements (RE)=La, Ce, Nd, or Pr) is proposed to have a stoichiometry of Al₄RE (tI10), based on direct evidence from differential scanning calorimetry (DSC) measurements.     

Autonomous precision agriculture through integration of wireless underground sensor networks with center pivot irrigation systems

Precision agriculture (PA) refers to a series of practices and tools necessary to correctly evaluate farming needs. The accuracy and effectiveness of PA solutions are highly dependent on accurate and timely analysis of the soil conditions. In this paper, a proof-of-concept towards an autonomous precision irrigation system is provided through the integration of a center pivot (CP) irrigation system with wireless underground sensor networks (WUSNs). This Wireless Underground Sensor-Aided Center Pivot (WUSA-CP) system will provide autonomous irrigation management capabilities by monitoring the soil conditions in real time using wireless underground sensors. To this end, field experiments with a hydraulic drive and continuous-move center pivot irrigation system are conducted. The results are used to evaluate empirical channel models for soil-air communications. The experiment results show that the concept of WUSA-CP is feasible. Through the design of an underground antenna, communication ranges can be improved by up to 400% compared to conventional antenna designs. The results also highlight that the wireless communication channel between soil and air is significantly affected by many spatio-temporal aspects, such as the location and burial depth of the sensors, soil texture and physical properties, soil moisture, and the vegetation canopy height. To the best of our knowledge, this is the first work on the development of an autonomous precision irrigation system with WUSNs.     

Synthesis and characterization of boehmitic alumina coated graphite by sol–gel method

Non-wettability property makes graphite a good protecting material against the molten metal and/or slag. Properties like high oxidation potential between 600 and 1200 °C and non-wettability with water at room temperatures limits the usage of graphite in castable refractory applications. In this study, sol–gel method, which is a relatively cheaper process, was used. Boehmitic sol was obtained by hydrolyzing and peptiziting the alkoxide AIP (aluminum isopropoxide) used as alumina source. Then natural flake graphite was mixed with the boehmitic solution for coating of graphite. At 120 °C boehmitic sol coated graphite was dried and gelled. Then heat threaded at 550 °C for γ-Al₂O₃ transformation of boehmite. Products that obtained from the studies were characterized with FTIR and XRD tests. Alumina coated graphite samples were made by repeating the same steps and TG analysis were made to investigate the oxidation behaviour of the samples. Finally, SEM–EDS analyses were carried out to investigate the microscopic properties of the alumina coated graphite powders.     

Design and biomechanical testing of pedicle screw for osteoporotic incidents

In this study, geometrical features of pedicle screws have been modified and their performances are compared. Performance analysis has been made in terms of pull-out strength and torsional strength. The parameters investigated are core diameter, holes drilled normal to screw axis, angle between sequential holes and distance between holes. Three different core diameter have been studied, which are 4 mm (normal core diameter), 5 mm (medium core diameter) and 5.5 mm (high core diameter). Distance between sequential holes has been arranged such that there is either one hole per pitch or one hole per two pitches. Angle between sequential holes is either 90 degrees or 120 degrees. According to the test results, the screw, with medium core diameter (5 mm) containing one hole per two pitches with 90 degrees angle between sequential holes, has exhibited the optimum performance considering torsional strength and pull-out strength requirements. Its torsional strength is slightly higher than and, when Grade 40 polyurethane foam was used as bone simulating material, its pull-out strength is as good as, an undrilled normal core diameter screw, which is already being used in surgical operations. The fatigue performance of this best performed screw has also been found satisfactory according to the related standard. Its pull-out strength is also tested on a calf vertebra and a promising result has been obtained.     

Factors Affecting International Construction

A construction company’s decision to expand into international markets must be based on a good understanding of the opportunities and threats associated with international business, as well as the development of company strengths relative to international activities. These factors were evaluated in this study by surveying the executives in charge of international construction of large United States based contractors. The information was collected by means of two rounds of a Delphi survey, the results of which were used as input in an analytic hierarchy process (AHP). The findings indicate that track record, specialist expertise, project management capability are the most important company strengths; loss of key personnel, shortage of financial resources, and inflation and currency fluctuations are the most important threats relative to international markets; and increased long term profitability, the ability to maintain shareholders’ returns, and the globalization and openness of the markets are the most important opportunities available in international works. This study is of relevance to practitioners as it systematically highlights the factors that affect international construction for the benefit of executives of medium-to-large size construction companies who are considering expanding into overseas markets. It is of relevance to researchers too as it demonstrates the successful use of the combined Delphi and AHP.     

Using Modified Bellani Plate Evapotranspiration Gauges to Estimate Short Canopy Reference Evapotranspiration

Modified Bellani plate atmometer has been offered as an alternative and simpler technique to combination-based equations to estimate evapotranspiration (ET) rate from green grass surface. However, there is a lack of information on its’ accuracy in humid climates. The evaporation rate (EA) from one type of atmometer marketed under the brand name ETgage? (or ETG) with a Number 30 green canvas cover that simulates the ET rate from a green grass surface was tested against the reference ET of a short green grass canopy (ETo) computed using the Food and Agriculture Organization of the United Nations Paper No. 56 Penman–Monteith (FAO56-PM) equation in two sites in north-central Florida. The ETG underestimated the ETo as much as 27%. The root mean square error (RMSE) of daily estimates of EA ranged from 1.03 to 1.15?mm. Data analyses indicated that the most of the poor performances and underestimations of the ETG occurred on rainy days. Using only the nonrainy day EA versus ETo relationship, the daily RMSE was as low as 0.47?mm and r2 was as high as 0.89, and the underestimations were within 3% of the ETo. Averaging daily ETG readings over 3 and 7 day periods considerably improved (lower RMSE and percent error, %E, and higher r2) ETo estimates. The ETG performed quite well on nonrainy days. The adjustment factors were developed and tabulated as a function of rainfall amount to adjust the EA values on rainy days. Results showed that an average adjustment factor of 0.84?(EA/0.84 = ETo) can be used as a practical number if rainfall observations are not available. The underestimations of the ETG on rainy days were attributed, in part, to the wetting of the green canvas cover due to the rainwater accumulations on it and to the lower diffusivity (higher resistance) value of the canvas cover (112–294?s?m?1) compared to the diffusivity of a green grass surface used in the ETo definition (70?s?m?1). Although it is found that the ETG is feasible and practical device, the EA values measured on rainy days require careful interpretation in humid and rainy climates such as Florida. The rainy day EA values should be used cautiously with the proper regression equation and adjustment factors to estimate ETo for irrigation scheduling if the input variables are not available to use the FAO56-PM equation for ETo estimates.     

Tool wear evaluation by vibration analysis during end milling of AISI D3 cold work tool steel with 35 HRC hardness

In this study, the relationship between vibration and tool wear was investigated during end milling. For this purpose, a series of experiment were conducted in a vertical milling machine. An indexable CBN insert and AISI D3 cold work tool steel hardened to 35 HRC were used as material twin in the experiments. The vibration was measured only in the machining direction, which has more dominant signals than in the other two directions. The measurements were taken by using an acceleration sensor assembled on a machinery analyzer. Tool wear was measured by a toolmaker's microscope. It was observed that there was an increase in vibration amplitude with increasing tool wears. This situation was evident especially by monitoring vibration of displacement type. It was also observed that the first three multiplies of tooth passing frequency (1×, 2×, 3×) gave the best information about the tool wear. Results showed that there was no considerable increase in the vibration amplitude until a flank wear value of 160 μm was reached, above which the vibration amplitude increased significantly.     

Importance of early dialysis for acute renal failure after an open-heart surgery

Coronary artery disease is a major cause of death in patients with a renal dysfunction. Among the patients who undergo coronary artery bypass grafting, renal dysfunction is known to be a major predictor of in-hospital and out-of-hospital mortality. From 2004 to 2007, we performed elective open-heart surgeries on 2380 patients in whom there was no primary renal failure. Of those patients, only 185 in whom acute renal failure (ARF) was developed were included in the study. The patients were divided into 2 groups: a late dialysis group (n=90) and an early dialysis group (n=95). The mean age of the patients was 62.3±6.4 in the late dialysis group and 64.5±5.2 in the early dialysis group. There were 32 female and 58 male patients in the late dialysis group and 36 female and 59 male patients in the early dialysis group. Acute renal failure developed only in 185 patients out of 2380 open-heart surgery patients. The overall mortality in the 2380 open-heart surgery patients was 1.97%. Mortality among the ARF patients was 5.9%. However, there was no significant difference in hospital mortality between the 2 groups. Major complications, such as postoperative pneumonia, prolonged ventilation time, arrhythmia, the number of times postoperative hemodialysis was performed, development of chronic renal failure, time spent in the intensive care unit and the period of hospitalization, sepsis, and low cardiac output, were significantly higher in the late dialysis group. There was no difference in mortality between the 2 groups. Early dialysis for open-heart surgery patients who develop ARF postoperatively does not decrease mortality. However, it decreases morbidity, the amount of time spent in intensive care, and the period of hospitalization and thus reduces patient costs.