Digital Commons Network^™

The Role Of Ball Backspin Alignment And Variability In Basketball Shooting Accuracy, Nathan Slegers, Dave Love

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

Interaction between the shooting hand and ball at the moment a basketball is released generates a three dimensional backspin of the ball. This study is the first to investigate how characteristics of the backspin alignment and variability contribute to lateral shooting accuracy. Spin axis (SA) direction and backspin magnitude were measured on 25 shot attempts for 26 collegiate basketball players (male: n = 16, female: n = 10). The mean SA alignment, as viewed from the shooting hand side, was found to be tipped down and towards the target (p < 0.001). Standard deviations (SD) in the SA alignment were strong predictors of lateral accuracy (vertical SD: r = 0.80, p < 0.001, forward-backward SD: r = 0.51, p = 0.01), with variation in the vertical alignment being the best predictor. No significant correlation between mean SA misalignment and lateral accuracy was observed. However, intra-individual relationships between SA misalignment and lateral error revealed that individuals tended to have 0.17 degrees more misalignment for each cm of lateral error (p < 0.001, 95% CI: 0.24–0.09). These indicate that while an individual’s mean alignment may not predict lateral accuracy, improving one’s SA alignment and reducing alignment variability may increase lateral accuracy.

Understanding Rural Water Services As A Complex System: An Assessment Of Key Factors As Potential Leverage Points For Improved Service Sustainability, Nicholas Valcourt, Jeffrey P. Walters, Amy Javernick-Will, Karl Linden, Betelhem Hailegiorgis

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

Rural water supply services worldwide consistently fail to deliver full public health impacts as intended due to a low service sustainability. This failure is increasingly attributed to weak local systems composed of social, financial and environmental factors. Current approaches in the water, sanitation and hygiene (WASH) sector for understanding and improving these systems typically focus on the strength and capacity of these factors, but not the interactions between them. We contend that these approaches overlook the inherent complexity and context-specific nature of each local system. To assess this complexity, we conducted four participatory factor mapping workshops with local stakeholders across …

Moving Toward Prevention: Rural Water Maintenance And Sustained Service Delivery, Caleb Cord, Jeffrey P. Walters, Harold Lockwood, Pranav Chintalapati, Amy Javernick-Will, Karl Linden

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

This paper outlines a research plan to be conducted across the Sustainable WASH Systems (SWS) Learning consortium to learn from maintenance approaches both internal and external to the partnership. It follows a study commissioned by IRC WASH and SWS which gathered information on prominent existing approaches from key informants.

System Dynamics Modelling As A Tool For Assessing Rural Water Sustainability, Pranav Chintalapati, Jeffrey P. Walters, Amy Javernick-Will, Karl Linden

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

System dynamics modelling is a tool that has been used for decades in business management and economics applications, but little focus has been applied to the WASH sector.

Specifically, this paper discusses the use of causal loop diagrams and stock flow diagrams as methods to better understand the systemic drivers affecting sustainability of rural water service delivery.

Factors Influencing Household Solar Adoption In Santiago, Chile, Jeffrey P. Walters, Jessica Kaminsky, Claudio Huepe

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

In Santiago, Chile, the market conditions are seemingly excellent for the household adoption of photovoltaic (PV) technology, yet the uptake is negligible. To explore this paradox, the authors conducted a Delphi study to solicit the knowledge of a panel of Chilean PV experts. These efforts yielded 26 factors—both motivations and barriers—impacting the diffusion of PV in Santiago. Of the 26, experts were in consensus on the relative importance of 21. The literature suggests that diffusion of PV technologies is influenced by complex technical, economic, and social factors. Similarly, the experts saw influence from financial, environmental, and energy supply (e.g., electrical …

Revealing Casual Pathways To Sustainable Water Service Delivering Using Fsqca, Kate E. Gasparro, Jeffrey P. Walters

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

This study aimed to build on theory and practice regarding the combinations of conditions that influence water service sustainability when external partners are involved. The study investigates 26 well projects that have been implemented in developing countries with the assistance of Engineers Without Borders-USA (EWB-USA). Using past literature on sustainable water service delivery in developing communities, emergent coding techniques with project documents, and surveys with EWB-USA team members, this study identifies a set of project conditions to conduct fuzzy-set Qualitative Comparative Analysis (fsQCA). Findings show that the presence of a water committee cannot alone account for project sustainability. Additional conditions, …

Embedding Systems Thinking Into Ewb Project Planning And Development: Assessing The Utility Of A Group Model Building Approach, Kimberly Pugel, Jeffrey P. Walters

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

Amongst growing sociotechnical efforts, engineering students and professionals both in the international development sector and industry are challenged to approach projects more holistically to achieve project goals. Engineering service learning organisations must similarly adapt their technological projects to consider varying cultural and economic structures, ensuring more resilient social progress within development efforts. In practice, systems thinking approaches can be utilised to model the social, economic, political, and technological implications that influence the sustainability of an engineering project. This research assesses the utility of integrating systems thinking into Engineers Without Borders (EWB) project planning and development, thereby improving project impact and …

Working With Complexity: A Participatory Systems-Based Process For Planning And Evaluating Rural Water, Sanitation And Hygiene Services, Jeffrey P. Walters, Kate Neely, Karla Pozo

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

Individuals working within the water, sanitation and hygiene for development (WASH) sector grapple daily with complex technical, social, economic, and environmental issues that often produce unexpected outcomes that are difficult to plan for and resolve. Here we propose a method we are calling the ‘Participatory Systems-based Planning and Evaluation Process’ (PS-PEP) that combines structural factor analysis and collaborative modeling to guide teams of practitioners, researchers, and other stakeholders through a process of modeling and interpreting how factors systemically and dynamically influence sustained access to WASH services. The use and utility of the PS-PEP is demonstrated with a regional team of …

Risk Attitudes And Global Infrastructure Technology Choices, Jessica Kaminsky, Jeffrey P. Walters

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

Past research shows that Hofstede’s cultural dimension of uncertainty avoidance explains variance in nations’ technology choice for sanitation and electricity infrastructure construction. The uncertainty avoidance dimension describes the way that nations deal with ambiguity and uncertainty. This paper is part of a larger project that links that previous national scale research to the project level that is most relevant to the construction practice. As such, this paper reviews methods from the literature that measure individual risk attitudes, including issues of measurement and risk determinants. For example, this paper discusses paid real-stakes lotteries, general risk questions, and context specific risk questions. …

Using Casual Loop Diagramming To Explore The Drivers Of The Sustained Functionality Of Rural Water Services In Timor-Leste, Kate Neely, Jeffrey P. Walters

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

It is recognized that international water sector development work has issues with a lack of sustained positive outcomes. A large driver of this outcome is how NGOs work with communities to implement and then manage water services. Many NGOs tend to focus their efforts on improving their reach and organisational growth by continually engaging in new projects. This behaviour is largely driven by short-term donor funding models that reward extended coverage, leaving little focus on sustained outcomes. Similarly, community-based management (CBM) schemes often impede sustained services as a result of the community’s limited capacity to operate and maintain the technology. …

Planning Rural Water Services In Nicaragua: A Systems-Based Analysis Of Impact Factors Using Graphical Modeling, Jeffrey P. Walters, Paul S. Chinowsky

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

The success or failure of rural water services in the developing world is a result of numerous factors that interact in a complex set of connections that are difficult to separate and identify. This research effort presented a novel means to empirically reveal the systemic interactions of factors that influence rural water service sustainability in the municipalities of Darío and Terrabona, Nicaragua. To accomplish this, the study employed graphical modeling to build and analyze factor networks. Influential factors were first identified by qualitatively and quantitatively analyzing transcribed interviews from community water committee members. Factor influences were then inferred by graphical …

Long-Term Functionality Of Rural Water Services In Developing Countries: A System Dynamics Approach To Understanding The Dynamic Interaction Of Causal Factors, Jeffrey P. Walters, Amy N. Javernick-Will

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

Research has shown that sustainability of rural water infrastructure in developing countries is largely affected by the dynamic and systemic interactions of technical, social, financial, institutional, and environmental factors that can lead to premature water system failure. This research employs systems dynamic modeling, which uses feedback mechanisms to understand how these factors interact dynamically to influence long-term rural water system functionality. To do this, the research first identified and aggregated key factors from literature, then asked water sector experts to indicate the polarity and strength between factors through Delphi and cross impact survey questionnaires, and finally used system dynamics modeling …

Management Of Rural Water Services In Nicaragua: A Systematic Network Approach To Evaluating Stakeholder Alignment, Jeffrey P. Walters, Amy N. Javemick-Will

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

Water sector literature attributes a substantial cause of rural water system failure in developing countries to poor alignment between water service stakeholders. This study aimed to investigate a means for assessing stakeholder alignment by comparing the systemic interaction of stakeholder values, where the term ‘stakeholder values’ refers to aspects stakeholders believe are necessary to ensure rural water services are sustainable. The research held focus groups with key stakeholder groups involved in the management of rural water infrastructure in Terrabona, Nicaragua, to identify stakeholder values, and then used cross-impact analysis to evaluate how these values interacted to form stakeholder value networks …

An Investigation Of Students’ Conceptual Understanding In Related Sophomore To Graduate-Level Engineering And Mechanics Courses, Devlin Montfort, Shane Brown, David Pollock

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

Interviews were conducted with students from a sophomore-level mechanics of materials class, a sophomore/junior-level structures class, a senior-level steel design class and a graduate-level advanced steel design class to investigate students’ conceptual understanding of bending and normal stress. The graduate students generally demonstrated higher computational skill and confidence but they were not significantly different from the sophomores in terms of conceptual understanding. Interestingly, the seniors showed markedly lower confidence in their ability to solve the problems posed in the interviews. Common difficulties include a conceptual definition of stress and reasoning involving the normal stresses developed under bending.

Detection Of Voids In Prestressed Concrete Bridges Using Thermal Imaging And Ground-Penetrating Radar, David G. Pollock, Kenneth J. Dupuis, Benjamin Lacour, Karl R. Olsen

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

Thermal imaging and ground-penetrating radar was conducted on concrete specimens with simulated air voids. For the thermal imaging inspections, six concrete specimens were constructed during the month of June 2007 to simulate the walls of post-tensioned box girder bridges. The objective was to detect simulated air voids within grouted post-tensioning ducts, thus locating areas where the post-tensioning steel strands are vulnerable to corrosion. The most important deduction taken from these inspections was that PT-ducts and simulated voids were more detectable in the 20 cm (8 in.) thick specimens than in the 30 cm (12 in.) thick specimens. While inspections of …

Transient Heat Partition Factor For A Sliding Railcar Wheel, T C. Kennedy, C Plengsaard, Robert F. Harder

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

During a wheel slide the frictional heat generated at the contact interface causes intense heating of the adjacent wheel material. If this material exceeds the austenitising temperature and then cools quickly enough, it can transform into martensite, which may ultimately crack and cause wheel failure. A knowledge of the distribution of the heat partitioned into the wheel and the rail and the resulting temperature fields is critical to developing designs to minimize these deleterious effects. A number of theoretical solutions have appeared in the literature to model the thermal aspects of this phenomenon. The objective of this investigation was to …

Application Of Dynamic System Identification To Timber Bridges, S T. Peterson, D I. Mclean, David Pollock

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

A method of global nondestructive evaluation for identifying local damage and decay in timber beams was developed in previous analytical studies and verified experimentally using simply supported beams in the laboratory. The method employs experimental modal analysis and an algorithm that monitors changes in modal strain energy between the mode shapes of a damaged structure with respect to the undamaged structure. A simple three-girder bridge was built and tested in a laboratory to investigate the capability and limitations of the method for detecting damage in a multimember timber structure. The laboratory tests showed that the method can correctly detect and …

Efficacy Of Interactive Internet-Based Education In Structural Timber Design, Aaron B. Henson, Kenneth J. Fridley, David Pollock, C Jayne Brahler

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

While traditional teaching methods (e.g., real-time, synchronous lectures) have proven effective for training future engineers, the Internet provides an avenue to reinforce the material and augment student learning, comprehension, and retention of material. This paper presents the integration and assessment of a library of interactive instructional modules specifically for a senior-level undergraduate elective course in civil engineering. An ongoing, comprehensive assessment process was implemented in the fall 1999 semester. The results of this quantitative assessment indicate that the use of well designed and pedagogically sound Internet-based supplemental modules provide students with a better understanding of course material. However, when Internet-based …

Reliability Indices For Bolted And Nailed Connections In Wood Structures, David Pollock, Donald A. Bender

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

Recently published test data for bolted and nailed connections was evaluated to assess the structural reliability inherent in current allowable stress design procedures for connections in wood structures. Reliability indices were determined for timber connections using standard firstorder, second moment (FOSM) procedures. For the connections considered in this study, reliability indices range from 2.6 to5.1, generally providing higher levels of safety than the structural members in timber structures.

Application Of Dynamic System Identification To Timber Beams - Part Ii, S T. Peterson, D I. Mclean, M D. Symans, David Pollock, W F. Cofer, R N. Emerson, Kenneth J. Fridley

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

In a companion paper, a method of global nondestructive evaluation (NDE) for identifying local damage and decay in timber beams was developed and verified analytically using a finite-element model of a timber beam. The previously presented method of damage localization employs experimental modal analysis and an algorithm that monitors changes in modal strain energy between the mode shapes of a damaged beam with respect to the undamaged state of the beam. In this second part of a two-part paper, experimental laboratory tests on simply supported timber beams are presented to verify the capabilities and determine the limitations of the proposed …

Application Of Dynamic System Identification To Timber Beams - Part I, S T. Peterson, D I. Mclean, M D. Symans, David Pollock, W F. Cofer, R N. Emerson, Kenneth J. Fridley

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

In this first part of a two-part paper, development of a method of dynamic system identification for timber beams is presented with an analytical verification of the method using a finite-element model. A method of global nondestructive evaluation for identifying local damage and decay in timber beams is investigated in this paper. Experimental modal analysis is used in conjunction with a previously developed damage localization algorithm. The damage localization algorithm utilizes changes in modal strain energy between the mode shapes of a calibrated model, representing the undamaged state of the beam of interest, and the experimentally obtained mode shapes for …

Governing Yield Modes For Common Bolted And Nailed Wood Connections, Brian J. Tucker, David Pollock, Kenneth J. Fridley, Jeffrey J. Peters

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

Connections in wood structures are important when designing for ductility. The 1997 Uniform Building Code has taken this into consideration when designating wind and earthquake load duration factors for connections. Factors of 1.6 or 1.33 may be applied to the connection strength, depending on the type of yield mode exhibited by the connection, which may be determined from the yield limit equations supplied in the National Design Specification for Wood Construction (NDS). The NDS provides the designer with multiple tables containing capacities for various common connections. Unfortunately, yield modes are not published along with tabulated capacities. Therefore, the designer must …

Bolt Bearing Behavior Of Engineered Wood Composites, Stephen J. Carstens, David Pollock

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

The goal of this research was to gain a better understanding of the bolt bearing behavior of engineered wood composites made from yellow poplar lumber. Lumber specimens included in this study were laminated veneer lumber, strandbased lumber, yellow poplar lumber, and Douglas-fir larch lumber. Testing followed the half-hole and full-hole configuration as set forth in ASTM Standard D5764 (1998).

In a previous study by Wilkinson (1991), a strong correlation was shown between bearing strength perpendicular to grain and bolt diameter. This study supports Wilkinson's finding for bearing strength perpendicular-to-grain based on the half hole test configuration. Other findings in this …

Lateral Resistance Of Ring-Shank Nail Connections In Southern Pine Lumber, R D. Theilen, D A. Bender, David Pollock, S G. Winistorfer

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

Ring-shank nails are used in engineered structures with lateral connection design values based on theoretically derived equations which were validated only for common nails. The goal of this study was to quantify the input parameters and lateral connection strength of several types of ring-shank nails in Southern Pine lumber and critically evaluate the applicability of the theoretical equations for ring-shank nails.

Two sizes of galvanized and ungalvanized, hardened steel ring-shank nails from two manufacturers were studied. The hardened, ring-shank nails carried significantly higher loads than the common wire nails studied. Because the current method of determining yield load does not …

Withdrawal Strength Of Ring-Shank Nails Embedded In Southern Pine Lumber, M J. Skulteti, D A. Bender, S G. Winistorfer, David Pollock

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

Ring-shank nails are used extensively in post-frame construction due to their superior performance, yet surprisingly little testing has been done on nail sizes above 12d. Experience in the post-frame industry suggests that published allowable design values for ring-shank nails may be overly conservative and need revision. The goal of the research reported herein was to characterize the withdrawal strength of ring-shank nails embedded in Southern Pine lumber. Three sizes ofgalvanized and ungalvanized (bright) ring-shank nails from two manufacturers were studied. Ring-shank nails had approximately twice the withdrawal resistance of smooth-shank nails of the same diameter. Galvanizing slightly reduced withdrawal strength …

Threaded-Nail Fasteners - Research And Standardization Needs, B L. Wills, S G. Winistorfer, D A. Bender, David Pollock

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

Threaded nail fasteners are commonly used in agricultural and commercial post-frame structures, yet there has been insufficient research to fully understand the effect of threads on withdrawal and lateral load resistance. The objective of this article is to review technical information on threaded nail fasteners and to identify problems facing manufacturers, designers, and users of threaded nail fasteners for engineering applications. Recommendations are given concerning research and standardization needs.

Seismic Performance Of Confined Sill Plate Connections, Joseph M. Bracci, Rebecca F. Stromatt, David Pollock

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

In the aftermath of the 1994 Northridge earthquake, extensive field investigations revealed damage in wood frame construction in the form of splitting of the 2 X 4 or 2 X 6 wood sill plates along the line of anchor bolts that typically connect shear walls to the masonry or concrete foundation. Due to the severity of such brittle failures, the city of Los Angeles has recently restricted the use of 2X dimension lumber in sill plates and requires the use of 3X dimension lumber. This paper presents an experimental investigation of the performance of 2X dimension lumber sill plate connections …

Ultrasonic Detection Of A Plastic Hinge In Bolted Timber Connections, David Pollock, Donald A. Bender, Don E. Bray, James T P Yao

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

Connections between structural members are critical elements that typically govern the performance of structural systems; hence, techniques for monitoring the condition of connections are needed to provide early warning of structural damage. Plastic hinge formation in fasteners frequently occurs in timber connections when the yield capacity is exceeded. An innovative pulse echo testing technique was developed for detecting the formation of a plastic hinge in bolted timber connections and estimating the associated magnitude of connection displacement. A shift in overall signal centroid proved to be the best flTedictor of plastic hinge formation, with a coefficient of determination (R2) of 0.9. …

Lrfd For Engineered Wood Structures - Connection Behavioral Equations, Thomas E. Mclain, Lawrence A. Soltis, David Pollock, Thomas L. Wilkinson

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

A new design specification for engineered wood structures has been proposed in load and resistance factor design (LRFD) format. This paper provides an overview of the proposed LRFD connections design criteria. The connections design provisions are, in part, calibrated from allowable stress design provisions. Major changes from historic practice, however, result from a change in behavioral equations to a theoretical base for predicting the lateral strength of connections using bolts, screws, and nails. New provisions for axial withdrawal of driven and turned fasteners, as well as combined axial and lateral loading criteria are also proposed. Safety levels were calibrated to …