Probabilistic simulation for developing likelihood distribution of engineering project cost

Inaccurate early project cost estimates can eliminate investment benefits. This study focuses on assisting estimators who are attempting to enhance the accuracy and reliability of engineering project cost in the pre-conceptual stage. This aim has recently garnered the attention of the transportation communities. Data from the Texas Department of Transportation (TxDOT) were utilized to develop an alternative approach that aids decision makers in terms of probability and confidence level. The proposed procedure comprises heuristic and practical simulation models that can be employed to calculate the probabilistic costs of highway bridge replacement projects. The simulation models utilize independent, correlated, and Latin Hypercube sampling approaches that incorporate major work items, roll-up work items, and project-level engineering contingencies. Cumulative distribution functions (CDFs) are then developed as a user-friendly chart for decision makers and these CDFs can be used to assess project risks during the pre-conceptual stage. Trial runs using these estimating procedures generate reliable pre-conceptual estimates. Additionally, these procedures can be extended to other project types along with programming techniques for developing an engineering project cost decision support system.     

Efficacy of Trust-Building Tactics in Construction Mediation

Distrust hinders disputing parties and mediators from achieving mediation success. Mediators therefore often use different trust-building tactics to generate some degree of trust in themselves and in the mediation process. This paper reports a study that identified the trust-building tactics used by construction mediators and examined the efficacy of these tactics with respect to their outcomes. Three study stages were designed. With reference to the mediation model of Sloan (1998), trust-building tactics and outcomes were first identified in Stage I. Next, the data were collected from accredited mediators with a questionnaire survey in Stage II. The collected data were then validated via reliability assessments in Stage III. With the use of multiple regression analyses, the efficacy of the trust-building tactics was examined by relating these tactics to their outcomes. The findings of this study suggest that the trust-building tactics used in Step 4 (i.e., explore interests) of Sloan’s (1998) mediation model are influential in developing trust among disputing parties and that they can also act as a time-saving tool in the mediation process. Furthermore, it was found that mediators can earn trust by adopting the trust-building tactics used in Step 3 (i.e., issues and trust) of Sloan’s (1998) model. These tactics can also serve to improve the relationships between the disputing parties. The results show that the trust-building tactics used in the final step (i.e., solutions) of Sloan’s (1998) model seem to have low efficacy in developing trust among disputing parties.     

Patterns of email use by teachers and implications: A Singapore experience

This paper attempts to identify the patterns of email use by schoolteachers. The findings are based on a survey of 2998 Singapore teachers whose teaching experiences ranged from 24 to 48 months. The result shows that teachers use email mainly to communicate with colleagues, and the degree of email use varies according to the school level that the teachers are working in. While the teachers teaching at higher school levels (Grades 11–12) email their colleagues more frequently than their counterparts teaching at lower school levels especially primary school teachers, the latter tend to email parents more frequently than other teachers. Implications of the findings are discussed in relevance to pre-service teacher education, teacher professional development and ICT adoption in organisations.     

Glass Structure Changes in CO$_{2}$ -Laser Writing of Long-Period Fiber Gratings in Boron-Doped Single-Mode Fibers

We investigate in detail the process of CO₂-laser writing of long-period fiber gratings (LPFGs) in unannealed and annealed boron-doped fiber samples by using repeated scanning of CO₂-laser pulses. We find that the writing dynamics depends strongly on the CO₂-laser energy density and the annealing temperature of the fiber. Our results from analyzing the writing dynamics reveal the relative importance of various physical effects arising from glass structure changes due to different writing conditions and thus provide a better understanding of the formation and the properties of CO₂-laser written LPFGs.     

Fundamental Analysis of Profitability of Large Engineering and Construction Firms

This research examines the strategic performance of sixty-one large international engineering and construction (E&C) firms from the regions of North America, Europe, and East Asia. The primary objective is to identify critical factors of corporate strategy that potentially affect the prospects of a large E&C firm. The research methodology relies on financial analysis and strategic management theories to draw meaningful conclusions. Statistical tests are selectively conducted to assess various aspects, including profitability, capital structure and asset liquidity. This paper documents the research findings for the first aspect—profitability. The first part of the findings suggests that there is no significant correlation between firm size and profitability. Large firms, which are endowed with greater resources and prowess, are not guaranteed to be more profitable. However, firm size has some influence on generic strategies, as large firms tend to adopt either a broadly targeted or a nonrelated diversification strategy. Regional trends of revenue growth of firms are subsequently presented. Despite strong forces of globalization experienced in many other industries, the growth trends suggest that the construction business remains largely localized in nature. Consequently, domestic and regional economic outlook, rather than global trends, should be given more weights in strategic planning.     

Voltammetric measurement in supercritical CO2 utilizing a water-in-CO2 microemulsion

A novel method for voltammetric measurement in supercritical CO2 is described. In this method a water-in-supercritical CO2 microemulsion is utilized to raise the conductivity of the fluid phase. Well-defined voltammograms for the redox reactions of ferrocene and tetramethyl-p-phenylenediamine were obtained in supercritical CO2 in the presence of the microemulsion. The electrolysis product is stabilized in the water core of the microemulsion. This implies a wide range of electrochemical synthesis involving ionic or radical species in supercritical CO2 may be possible utilizing the microemulsion. The electrochemical results obtained from the water-in-supercritical CO2 microemulsion system are different from that obtained from a supercritical CO2-ethanol mixture system.     

Correction of temperature-induced spectral variation by continuous piecewise direct standardization

In process analytical applications it is not always possible to keep the measurement conditions constant. However, fluctuations in external variables such as temperature can have a strong influence on measurement results. For example, nonlinear temperature effects on near-infrared (NIR) spectra may lead to a strongly biased prediction result from multivariate calibration models such as PLS. A new method, called Continuous Piecewise Direct Standardization (CPDS) has been developed for the correction of such external influences. It represents a generalization of the discrete PDS calibration transfer method and is able to adjust for continuous nonlinear influences such as the temperature effects on spectra. It was applied to shortwave NIR spectra of ethanol/water/2-propanol mixtures measured at different temperatures in the range 30-70 degrees C. The method was able to remove, almost completely, the temperature effects on the spectra, and prediction of the mole fractions of the chemical components was close to the results obtained at constant temperature.     

An adaptive fuzzy-neural-network controller for ultrasonic motor drive using the LLCC resonant technique

In this study an adaptive fuzzy-neural-network controller (AFNNC) is proposed to control a rotary traveling wave-type ultrasonic motor (USM) drive system. The USM is derived by a newly designed, high frequency, two-phase voltage source inverter using two inductances and two capacitances (LLCC) resonant technique. Then, because the dynamic characteristics of the USM are complicated and the motor parameters are time varying, an AFNNC is proposed to control the rotor position of the USM. In the proposed controller, the USM drive system is identified by a fuzzy-neural-network identifier (FNNI) to provide the sensitivity information of the drive system to an adaptive controller. The backpropagation algorithm is used to train the FNNI on line. Moreover, to guarantee the convergence of identification and tracking errors, analytical methods based on a discrete-type Lyapunov function are proposed to determine the varied learning rates of the FNNI and the optimal learning rate of the adaptive controller. In addition, the effectiveness of the adaptive fuzzy-neural-network (AFNN) controlled USM drive system is demonstrated by some experimental results.     

Modification of SiO2 nanowires with metallic nanocrystals from supercritical CO2

Through hydrogen reduction of metal precursors in supercritical CO2, Cu, and Pd, nanocrystals were deposited onto SiO2 nanowires to form different types of nanostructured materials, including nanocrystal-nanowire, spherical aggregation-nanowire, shell-nanowire composites, and "mesoporous" metals supported by the framework of nanowires. This supercritical fluid deposition technique is an attractive approach for modifying nanowires because of its generality and simplicity; the modified nanowires could be useful as catalysts and for further fabrication of multifunctional composites.     

Performance optimization of spectroscopic process analyzers

To increase the power and the robustness of spectroscopic process analyzers, methods are needed that suppress the spectral variation that is not related to the property of interest in the process stream. An approach for the selection of a suitable method is presented. The approach uses the net analyte signal (NAS) to analyze the situation and to select methods to suppress the nonrelevant spectral variation. The empirically determined signal-to-noise of the NAS is used as a figure of merit. The advantages of the approach are (i). that the error of the reference method does not affect method selection and (ii). that only a few spectral measurements are needed. A diagnostic plot is proposed that guides the user in the evaluation of the particular suppression method. As an example, NIR spectroscopic monitoring of a mol-sieve separation process is used.