Adapting Critical Chain Project Management to Army Engineer Construction Projects

For decades, Army Engineers have utilized the systems of the Critical Path Method (CPM) and multi-level Gantt chart planning system for its construction projects. While these methods are well accepted, they are not without their flaws. Research and literature in project management has given weight to several viable alternative options to planning projects. One such option, Critical Chain Project Management (CCPM), was developed to address the flaws of CPM by offering a holistic approach to project management based on strict resource control and the use of time buffers. This method attempts to eliminate multitasking and procrastination that can plague efficiency and offer managers more flexibly on tasks that otherwise had no leeway. CCPM may give project managers more flexibility and control while at the same time shortening the overall length of a project, saving time and money. The purpose of this thesis was to address the time saving and resource management benefits of utilizing CCPM over CPM and analyze the viability of those benefits being applied to U.S. Army Corps of Engineers construction project planning. Through the use of surveys of Army Engineer project supervisors, several key factors that cause delays because of CPM were identified and rated. The validity of CCPM based solutions to the same issues were also assessed by Army project supervisors in the survey. Analysis of the survey results indicated that CCPM may offer solutions to major issues that Army project supervisors face

Exchange-correlation orbital functionals in current-density-functional theory: Application to a quantum dot in magnetic fields

The description of interacting many-electron systems in external magnetic fields is considered in the framework of the optimized effective potential method extended to current-spin-density functional theory. As a case study, a two-dimensional quantum dot in external magnetic fields is investigated. Excellent agreement with quantum Monte Carlo results is obtained when self-interaction corrected correlation energies from the standard local spin-density approximation are added to exact-exchange results. Full self-consistency within the complete current-spin-density-functional framework is found to be of minor importance.Comment: 5 pages, 2 figures, submitted to PR

Correlation potentials for molecular bond dissociation within the self-consistent random phase approximation

Self-consistent correlation potentials for H$_2$ and LiH for various inter-atomic separations are obtained within the random phase approximation (RPA) of density functional theory. The RPA correlation potential shows a peak at the bond midpoint, which is an exact feature of the true correlation potential, but lacks another exact feature: the step important to preserve integer charge on the atomic fragments in the dissociation limit. An analysis of the RPA energy functional in terms of fractional charge is given which confirms these observations. We find that the RPA misses the derivative discontinuity at odd integer particle numbers but explicitly eliminates the fractional spin error in the exact-exchange functional. The latter finding explains the accurate total energy in the dissociation limit.Comment: 9 pages, 10 figure

Forest and Prairie in Three Northwestern Indiana Counties

The modifying influence of civilized man on natural vegetation is so rapid and so extensive that it becomes a difficult problem after a century or more to picture the original vegetation cover. The task is still more difficult when one attempts to express the vegetation in quantitative terms. Today the taxonomists scour the railway right-of-way for specimens of prairie plants for the prairie itself with its plant sociology has vanished. We will never be able adequately to reconstruct this vegetation complex, and we can only with difficulty draw its former boundary. Even though the surveyors of the original United States land survey, whose records form the basis of this study, made copious notes on prairie areas, it is likely that sedge-meadow type of vegetation was included under their classification of wet prairie. If the term actually described areas dominated by typical prairie grasses, then Indiana at that time had wet prairie, dry prairie and a transition type of prairie and forest association, park-like in nature, which might be called oak openings

Relativistic nucleon optical potentials with isospin dependence in Dirac Brueckner Hartree-Fock approach

The relativistic optical model potential (OMP) for nucleon-nucleus scattering is investigated in the framework of Dirac-Brueckner-Hartree-Fock (DBHF) approach using the Bonn-B One-Boson- Exchange potential for the bare nucleon-nucleon interaction. Both real and imaginary parts of isospin-dependent nucleon self-energies in nuclear medium are derived from the DBHF approach based on the projection techniques within the subtracted T -matrix representation. The Dirac potentials as well as the corresponding Schrodinger equivalent potentials are evaluated. An improved local density approximation is employed in this analysis, where a range parameter is included to account for a finite-range correction of the nucleon-nucleon interaction. As an example the total cross sections, differential elastic scattering cross sections, analyzing powers for n, p + 27Al at incident energy 100 keV < E < 250 MeV are calculated. The results derived from this microscopic approach of the OMP are compared to the experimental data, as well as the results obtained with a phenomenological OMP. A good agreement between the theoretical results and the measurements can be achieved for all incident energies using a constant value for the range parameter.Comment: 10 pages, 16 figure

Probing the pairing symmetry in the over-doped Fe-based superconductor Ba_0.35Rb_0.65Fe_2As_2 as a function of hydrostatic pressure

We report muon spin rotation experiments on the magnetic penetration depth lambda and the temperature dependence of lambda^{-2} in the over-doped Fe-based high-temperature superconductor (Fe-HTS) Ba_{1-x}Rb_ xFe_2As_2 (x = 0.65) studied at ambient and under hydrostatic pressures up to p = 2.3 GPa. We find that in this system lambda^{-2}(T) is best described by d-wave scenario. This is in contrast to the case of the optimally doped x = 0.35 system which is known to be a nodeless s^{+-}-wave superconductor. This suggests that the doping induces the change of the pairing symmetry from s^{+-} to d-wave in Ba_{1-x}Rb_{x}Fe_{2}As_{2}. In addition, we find that the d-wave order parameter is robust against pressure, suggesting that d is the common and dominant pairing symmetry in over-doped Ba_{1-x}Rb_{x}Fe_{2}As_{2}. Application of pressure of p = 2.3 GPa causes a decrease of lambda(0) by less than 5 %, while at optimal doping x = 0.35 a significant decrease of lambda(0) was reported. The superconducting transition temperature T_c as well as the gap to T_c ratio 2Delta/k_BT_c show only a modest decrease with pressure. By combining the present data with those previously obtained for optimally doped system x = 0.35 and for the end member x = 1 we conclude that the SC gap symmetry as well as the pressure effects on the SC quantities strongly depend on the Rb doping level. These results are discussed in the light of the putative Lifshitz transition, i.e., a disappearance of the electron pockets in the Fermi surface of Ba_{1-x}Rb_{x}Fe_{2}As_{2} upon hole doping.Comment: Accepted for publication in Physical Review

Evidence for strong lattice effects as revealed from huge unconventional oxygen isotope effects on the pseudogap temperature in La2−x_{2-x}Srx_{x}CuO4_{4}

The oxygen isotope ($^{16}$O/$^{18}$O) effect (OIE) on the pseudogap (charge-stripe ordering) temperature $T^{\ast}$ is investigated for the cuprate superconductor La$_{2-x}$Sr$_{x}$CuO$_{4}$ as a function of doping $x$ by means of x-ray absorption near edge structure (XANES) studies. A strong $x$ dependent and sign reversed OIE on $T^{\ast}$ is observed. The OIE exponent $\alpha_{T^{\ast}}$ systematically decreases from $\alpha_{T^{\ast}} = - 0.6(1.3)$ for $x = 0.15$ to $\alpha_{T^{\ast}} = - 4.4(1.1)$ for $x = 0.06$, corresponding to increasing $T^{\ast}$ and decreasing superconducting transition temperature $T_{c}$. Both $T^{\ast}(^{16}{\rm O})$ and $T^{\ast}(^{18}{\rm O})$ exhibit a linear doping dependence with different slopes and critical end points (where $T^{\ast}(^{16}{\rm O})$ and $T^{\ast}(^{18}{\rm O})$ fall to zero) at $x_{c}(^{16}{\rm O}) = 0.201(4)$ and $x_{c}(^{18}{\rm O}) = 0.182(3)$, indicating a large positive OIE of $x_{c}$ with an exponent of $\alpha_{x_{c}} = 0.84(22)$. The remarkably large and strongly doping dependent OIE on $T^{\ast}$ signals a substantial involvement of the lattice in the formation of the pseudogap, consistent with a polaronic approach to cuprate superconductivity and the vibronic character of its ground state

Loss and Waste in the Australian Fresh Apple Value Chain

Apples are a significant and popular fruit among t e Australian opulation, and in the case of fresh apples, the domestic market is relatively self-sustaining. Retail and consumer preferences are the driving force for quality standards for apples along the chain, with actors working to provide the best quality selection of produce. In order to meet these high standards, loss and waste occurs in the lower grades which are simply a by-product of first grade production. Globally, loss and waste of fresh produce is amongst the highest of all food groups and from the limited data available, apples appear to be no exception. While there is not accurate specific data regarding loss and waste data of fresh apples in the Australian value chain, reporting is increasing as is awareness of the broader issues of food loss and waste. Following along the value chain, there appear to be discrepancies in quantities of fresh apples available at the various stages, with these variations potentially reflective of loss and waste along the chain. Using best estimates from the literature, the total amount of fresh apples, conservatively, that is potentially diverted from the Australian fresh apple supply chain is around 163,000 tonnes which is about 41 per cent of total production at the farm level. What is also lacking from Australian market data and literature, other than robust primary loss and waste data, is the cost of food loss and waste, and the extent of the externalities that occur due to loss and waste along the value chain. Not only do negative externalities incur costs to the broader society, there are additional costs of intervention, and analysis is required to determine the feasibility and appropriateness of intervention strategies