Electrostatics in Periodic Slab Geometries I

We propose a new method to sum up electrostatic interactions in 2D slab geometries. It consists of a combination of two recently proposed methods, the 3D Ewald variant of Yeh and Berkowitz, J. Chem. Phys. 111 (1999) 3155, and the purely 2D method MMM2D by Arnold and Holm, to appear in Chem. Phys. Lett. 2002. The basic idea involves two steps. First we use a three dimensional summation method whose summation order is changed to sum up the interactions in a slab-wise fashion. Second we subtract the unwanted interactions with the replicated layers analytically. The resulting method has full control over the introduced errors. The time to evaluate the layer correction term scales linearly with the number of charges, so that the full method scales like an ordinary 3D Ewald method, with an almost linear scaling in a mesh based implementation. In this paper we will introduce the basic ideas, derive the layer correction term and numerically verify our analytical results.Comment: 10 pages, 7 figure

Electrostatics in Periodic Slab Geometries II

In a previous paper a method was developed to subtract the interactions due to periodically replicated charges (or other long-range entities) in one spatial dimension. The method constitutes a generalized "electrostatic layer correction" (ELC) which adapts any standard 3D summation method to slab-like conditions. Here the implementation of the layer correction is considered in detail for the standard Ewald (EW3DLC) and the PPPM mesh Ewald (PPPMLC) methods. In particular this method offers a strong control on the accuracy and an improved computational complexity of O(N log N) for mesh-based implementations. We derive anisotropic Ewald error formulas and give some fundamental guidelines for optimization. A demonstration of the accuracy, error formulas and computation times for typical systems is also presented.Comment: 14 pages, 7 figure

Leadership Style and Readiness to Lead: Perceptions of Florida Level 1 Educational Leadership Preparation Program Participants

The present study examined the relationship between aspiring school principals’ self-perceived competency regarding expected leadership behaviors as indicated by the domains identified in the 2011 Florida Principal Leadership Standards and their perception of their leadership style as indicated by the Multifactor Leadership Questionnaire (Bass & Avolio, 1994). The conceptual frameworks of this study included leadership style, as defined and conceptualized by Bass and Avolio’s Full Range Leadership Model and measured by the Multifactor Leadership Questionnaire (MLQ), and leadership behavior, as defined through the domains of the Florida Principal Leadership Standards (FPLS, 2011). Both the MLQ and the FPLS questionnaire served as data collection instruments. The three main leadership styles measured by the MLQ (including transformational, transactional, and laissez-faire leadership) served as the independent variables, and the four leadership domains measured by the FPLS questionnaire (i.e., student achievement, instructional leadership, organizational leadership, professional and ethical behavior) served as the dependent variables. The research sample included participants currently enrolled in a state-approved Level 1 Educational Leadership Program and were recruited to participate from 3 state universities in Florida. Both survey instruments were administered via a single, anonymous link embedded in an email containing both an introduction and description of the research study and informed consent. Of 200 potential participants, 48 respondents or 24% of the original sample returned completed surveys. Using canonical correlation analysis, the study found that the degree of respondents’ self-perceived ability to competently perform the leadership behaviors as identified by the four 2011 FPLS domains could be explained to some degree by respondents’ self-perceived leadership style (as identified on the MLQ). Two canonical roots were interpreted. The MLQ predictor variables accounted for 48% of the variance in the FPLS subscale scores (root 1 Rc2 =.48; p \u3c .001). For this root, transformational leadership was the primary independent variable accounting for variance across all 4 FPLS domains. Canonical root 2 (Rc2 = .117) accounted for a moderate amount of the shared variance between the two sets (i.e., 12%) and was not statistically significant (p \u3e .05). The correlation in this root was due primarily to a direct relationship between MLQ transactional leadership and the professional and ethical behavior domain of the FPLS. Additionally, the findings indicated that participants of Level 1 Educational Leadership programs felt confident in their ability to competently perform the expected behavioral indicators of the 2011 FPLS domains

Perceptions of Youth Risk and Safety Education: A Survey of Farm Safety Day Camp Participants and Their Parents

Farm Safety Day Camps are popular educational formats for teaching safety awareness to rural youth audiences. Surveys were administered to 3rd graders and their parents following a safety day camp program to determine the amount of exposure the youth had to six identified rural hazards. Data showed that students are capable of self-reporting their exposure rate and risk of injury and that they are capable of following safety rules 91.8% of the time. Most parents (80%) revealed that the program was a beneficial experience for their children and reported a preference to general safety topics as opposed to farm-related topics

Lessons Learned from Conducting Volunteer-Based Urban Forest Inventories on the Gulf Coast

Volunteer-based urban forest inventories are a common activity among Extension professionals; however, project facilitators often end up duplicating mistakes experienced previously by others. This article shares lessons learned from conducting several volunteer-based urban forest inventories. The lessons revolve around the themes of volunteer recruitment, communication with the public, private property access, project scope and time line, volunteer management, and efforts to increase efficiency. Through awareness of these lessons, Extension professionals can implement and adapt our successful strategies yet not repeat our mistakes. In turn, readers will increase the likelihood of successfully developing baseline measures while engaging the public in urban forest management

Batch Measurement Extremum Seeking Control of Distributed Energy Resources to Account for Communication Delays and Information Loss

Distributed Energy Resources (DER) have great potential to enhance the operation of electric power distribution systems. Previously, we explored the use of 2 Dimensional Extremum Seeking (2D-ES) control algorithms to enable model-free optimal control of DER to provide grid services to both the distribution and transmissions systems. Motivated by preliminary deployments of DER managed by 2D-ES algorithms in hardware-in-the-loop tests and in operational distribution grids, in this work, we extend the control scheme to accommodate communication delays and information loss. We propose a modification to the 2D-ES scheme to allow for the processing of batches of possibly noncontiguous objective function measurements at unknown and possibly uneven intervals. We provide a proof of the convergence of the batch 2D-ES (2D-BES) scheme when optimizing a generic convex objective function, as well as simulation results that demonstrate the suitability of the approach for substation active and reactive power target tracking