Integrated Civil Engineering Curriculum: Five-Year Review

An integrated curriculum, which draws material from different areas to teach students about design and problem-solving, offers civil engineering educators an option for accommodating new topics without increasing the number of courses. Freshman engineering and the senior capstone course are two examples of integrated courses, and the writers present a 5-year perspective on an approach that extends the concept of integration to six additional courses, comprised of an 8-course, integrated civil engineering core curriculum. Drawing on their combined experiences with the courses and assessment in a review by the Accreditation Board for Engineering and Technology, the writers conclude that the curriculum offers a useful vehicle by which to add material to the 4-year program without increasing the number of credit hours, and offers flexible courses to meet goals of professional groups. The paper describes lessons learned, challenges that remain, and current approaches to improvement.     

Graphical Representation of Run Length Distributions

With the development of techniques to compute run length distributions for various types of control charts, numerous researchers have advocated using these distributions. However, it is unclear how practitioners are expected to use run length distributions in making decisions about control chart performance and chart design. To alleviate this problem, we present a graphical method of representing run length distributions. Our method allows for the easy comparison of several distributions which is not currently permitted with standard types of distribution plotting.     

Mechanical properties of composites using ultrafine electrospun fibers

The objective of this research was to show the reinforcing effects of nanofibers in an epoxy matrix and in a rubber matrix using electrospun nanofibers of PBI (polybenzimidazole). The average diameter of the electrospun fibers was around 300 nanometers, which is less than one tenth the diameter and 1/100 the cross sectional area of ordinary reinforcing fibers. The ultrafine fibers provide a very high ratio of surface area to volume. The nanofibers toughened the brittle epoxy resin. The fracture toughness and the modulus of the nanofiber (15 wt%)-reinforced epoxy composite were both higher than for an epoxy composite made with PBI fibrids (17 wt%), which are whisker-like particles. In an elastomeric matrix, The Young's modulus and tear strength of the chopped nanofiber-reinforced styrene-butadiene rubber (SBR) were higher than those of the pure SBR. Micrographs of the fracture surfaces were obtained by scanning electron microscopy (SEM).     

Boron Carbide Reinforced Alumina Composites

The mechanical properties of alumina have been successfully improved by adding isolated boron carbide particles of two different shapes. A K _Ic of 7.26 ± 0.20 MPa · m^1/2 for alumina—boron carbide whiskerlike composites and of 5.27 ± 0.12 MPa · m^1/2 alumina—boron carbide shardlike particle composites has been achieved. The fracture toughness of these composites is dependent on the volume fraction of the boron carbide particles as well as their size and shape. The flexural strength is also appreciably enhanced to a constant value with from 5 to 20 vol% boron carbide additions. The whiskerlike particles increase the flexural strength by 25% and the shardlike particles produce a 47% improvement.     

Open-loop discretization methods for control systems design

In this paper, a unified theory is presented which addresses essential aspects of the open-loop discretization procedure. Initially, factors which affect the generation and propagation of discretization errors are identified by analytical, heuristic and experimental arguments. Following this, a discretization algorithm is presented which takes these factors into account. The fundamental idea of the discretization method is the replacement of the analogue integrators of the prototype continuous-time system by discrete-time approximations. This is done in such a way as to optimize a given cost function with respect to a given input. Unlike many discretization schemes presented in the literature, the procedure developed attempts to first determine the magnitude of the expected discretization errors, and then discretize with an appropriate complexity, giving the designer control over the order of the discrete-time system. This appears to be an effective means of designing filters with low complexity which still retain essential properties of the prototype system. An emphasis of this work is to view the discretization process from a control theory and engineering perspective. This results in a number of new perspectives relating to the discretization process.     

Inlet ionization: a new highly sensitive approach for liquid chromatography/mass spectrometry of small and large molecules

Inlet ionization is a new approach for ionizing both small and large molecules in solids or liquid solvents with high sensitivity. The utility of solvent based inlet ionization mass spectrometry (MS) as a method for analysis of volatile and nonvolatile compounds eluting from a liquid chromatography (LC) column is demonstrated. This new LC/MS approach uses reverse phase solvent systems common to electrospray ionization MS. The first LC/MS analyses using this novel approach produced sharp chromatographic peaks and good quality full mass range mass spectra for over 25 peptides from injection of only 1 pmol of a tryptic digest of bovine serum albumin using an eluent flow rate of 55 μL min(-1). Similarly, full acquisition LC/MS/MS of the MH(+) ion of the drug clozapine, using the same solvent flow rate, produced a signal-to-noise ratio of 54 for the major fragment ion with injection of only 1 μL of a 2 ppb solution. LC/MS results were acquired on two different manufacturer's mass spectrometers using a Waters Corporation NanoAcquity liquid chromatograph.     

Epitaxial integration of the highly spin-polarized ferromagnetic semiconductor EuO with silicon and GaN

Doped EuO is an attractive material for the fabrication of proof-of-concept spintronic devices. Yet for decades its use has been hindered by its instability in air and the difficulty of preparing and patterning high-quality thin films. Here, we establish EuO as the pre-eminent material for the direct integration of a carrier-concentration-matched half-metal with the long-spin-lifetime semiconductors silicon and GaN, using methods that transcend these difficulties. Andreev reflection measurements reveal that the spin polarization in doped epitaxial EuO films exceeds 90%, demonstrating that EuO is a half-metal even when highly doped. Furthermore, EuO is epitaxially integrated with silicon and GaN. These results demonstrate the high potential of EuO for spintronic devices.     

Wavelet-enhanced bayesian classification of surface nanostructures observed in pentacene thin films

In recent years, the wavelet transform has proven to be an extremely powerful image-processing tool. Here, we have developed a wavelet-enhanced Bayesian methodology to analyze the AFM images of organic crystals, such as pentacene, using the Haar wavelet transform. This methodology segments and identifies structures in AFM data and extracts quantitative information such as grain size, perimeter, and orientation. This methodology relies on a Naïve Bayesian classification system, which determines whether each data point corresponds to a peak or a valley with a finite statistical probability based on analysis of a synthetic teaching image. In this work, we apply this technique to AFM images of organic crystal films deposited on three different substrates.     

Designing van der Waals Forces between Nanocolloids

van der Waals (VDW) dispersion forces are often calculated between colloidal particles by combining the Dzyaloshinskii-Lifshitz-Pitaevskii (DLP) theory with the Derjaguin approximation; however, several limitations prevent using this method for nanocolloids. Here we use the Axilrod-Teller-Muto 3-body formulation to predict VDW forces between spherical, cubic, and core-shell nanoparticles in a vacuum. Results suggest heuristics for "designing" nanocolloids to have improved stability.     

An assessment of the accuracy of a home energy analysis system based on a modified TWOZONE computer model

Recently, a number of computer models have been utilized in the analysis of the energy performance of residences. In many cases, input to the computer model is provided by the homeowner. This may introduce significant error into the data inasmuch as the homeowner may not be aware of the sensitivity of the program to the accuracy of the data. This research was directed toward the validation of the class B energy audit program for the State of New Mexico and deals with the accuracy of the TWOZONE computer auditing program when used as a class B auditing tool, i.e. when used with homeowner supplied data. This study reveals a number of significant factors which are not properly dealt with in the TWOZONE model. It also presents a methodology which can be used generally to evaluate the overall accuracy of similar auditing tools.