Engineering Commons^™

Engineering Education In Developing Nations: Progress On The School Of Engineering At Northrise University In Ndola, Zambia, Jeff Gladstone, Gitogo Churu, John Tixier, Nolan Van Gaalen

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The engineering and technology capabilities of developed nations continues to advance and to be a major driver of the economies of those nations. Developing nations recognize this reality, and they accordingly recognize the importance of nurturing the growth of their own countries’ STEM capabilities. Engineering education in developing nations is thus a critical need; but it is work that, for a variety of reasons, tends to be under-resourced by developing nations themselves as well as by potential participants from developed nations. As followers of Jesus, we sometimes find our hearts stirred on behalf of our brothers and sisters in Christ …

Effective Parameters Controlling Sterol Transfer: A Time‑Resolved Small‑Angle Neutron Scattering Study, Ursula Perez-Salas, Lionel Porcar, Sumit Garg, Manuela A.A. Ayee-Leong, Irena Levitan

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Though cholesterol is the most prevalent and essential sterol in mammalian cellular membranes, its precursors, post-synthesis cholesterol products, as well as its oxidized derivatives play many other important physiological roles. Using a non-invasive in situ technique, time-resolved small angle neutron scattering, we report on the rate of membrane desorption and corresponding activation energy for this process for a series of sterol precursors and post-synthesis cholesterol products that vary from cholesterol by the number and position of double bonds in B ring of cholesterol’s steroid core. In addition, we report on sterols that have oxidation modifications in ring A and ring …

Achieving Optimal Value Of Solar: A Municipal Utility Rate Analysis, Ben Saarloos, Jason C. Quinn

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Wind and solar renewable energy in the United States is projected to triple by 2050 to nearly 30% of total electric energy generation. The upper Midwest region (Iowa, Minnesota, and North and South Dakota in particular) is considered wind energy country and not historically known for solar energy development. In this work, Value of Solar (VOS) is developed as a photovoltaic (PV) optimization measure and analysis tool using a northwest Iowa municipality as a representative case study. By applying a top-down load duration curve system analysis, VOS is used to optimize PV orientation and compare electric rate structures for increasing …

Net-Zero Energy Districts And The Grid: An Energy-Economic Feasibility Case-Study Of The National Western Center In Denver, Co, Usa, Ben Saarloos, Jason C. Quinn

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Given the enormous impact of buildings on energy consumption, it is important to continue the development of net-zero energy districts. Opportunities exist for energy efficiency and renewable energy on a district level that may not be feasible in individual buildings. Due to the intermittent nature of many renewable energy sources, net-zero energy districts are dependent on the energy grid. The novelty of this work is to quantify and optimize the economic cost and grid independence of a net-zero energy district using the National Western Center (NWC) in Denver, CO, USA as a case study. The NWC is a 100+ ha …

Lipoprotein-Induced Increases In Cholesterol And 7-Ketocholesterol Result In Opposite Molecular-Scale Biophysical Effects On Membrane Structure, Manuela A.A. Ayee, Irena Levitan

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Under hypercholesterolemic conditions, exposure of cells to lipoproteins results in a subtle membrane increase in the levels of cholesterol and 7-ketocholesterol, as compared to normal conditions. The effect of these physiologically relevant concentration increases on multicomponent bilayer membranes was investigated using coarse-grained molecular dynamics simulations. Significant changes in the structural and dynamic properties of the bilayer membranes resulted from these subtle increases in sterol levels, with both sterol species inducing decreases in the lateral area and inhibiting lateral diffusion to varying extents. Cholesterol and 7-ketocholesterol, however, exhibited opposite effects on lipid packing and orientation. The results from this study indicate …

Guiding Principles For Integrally Christian Engineering Work In Industry, Justin R. Vander Werff

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What is integrally Christian engineering? Or to ask it slightly differently, what does engineering look like if it is faithful and obedient to God’s will as revealed in His Word? I do not think we, as finite and creaturely Christ-followers, can expect to exhaustively determine God’s biblical directive for every facet of engineering and technology on this side eternity. However, if we truly believe that Christ is Lord of all of life and that He calls us to grateful service in everything we do, we need to continue to wrestle with these questions. One framework to help navigate these questions …

Transformation Of Char Carbon During Bubbling Fluidized Bed Gasification Of Biomass, Kevin Timmer, Robert C. Brown

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This study focuses on the fate of carbon in the char generated by devolatilization of biomass during fluidized bed gasification. A carbon balance model was developed to distinguish between char transformed to carbon-bearing gases and its comminution and elutriation as fine char during gasification. The model accurately predicts the transient accumulation of char carbon in the reactor. Experiments revealed steady state reactor char carbon loadings were achieved after multiple hours of gasification. The model formed the basis of an experimental methodology that assesses the transformation of char carbon based on collection of elutriated solids from the reactor and assessment of …

The Bridge Between Beauty And Functionality, Justin R. Vander Werff

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"While our human creatureliness and limited understanding often lead us to pit form and function against each other, God provides glimpses of their unity."

Posting about ­­­­­­­­balancing aesthetics and practicality in design from In All Things - an online journal for critical reflection on faith, culture, art, and every ordinary-yet-graced square inch of God’s creation.

https://inallthings.org/the-bridge-between-beauty-and-functionality/

Shalom Seeking: Foundations Of Flourishing, Kevin Timmer

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Jesus instructs us to seek first the Kingdom of God. Seeking first the Kingdom of God is no small task. It is a process of striving to show God’s love in every situation by showing love to our neighbors and to the rest of the creation. It is serving in a way that enables them to flourish. Seeking first the Kingdom of God is striving for true progress in all its wholeness; it is seeking shalom [1]. Shalom is an Old Testament word which refers to the restfulness, contentment, beauty, and harmony of a life lived in perfect obedience to …

Comparing Machine Learning And Logistic Regression Methods For Predicting Hypertension Using A Combination Of Gene Expression And Next-Generation Sequencing Data, Elizabeth Held, Joshua Cape, Nathan L. Tintle

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Machine learning methods continue to show promise in the analysis of data from genetic association studies because of the high number of variables relative to the number of observations. However, few best practices exist for the application of these methods. We extend a recently proposed supervised machine learning approach for predicting disease risk by genotypes to be able to incorporate gene expression data and rare variants. We then apply 2 different versions of the approach (radial and linear support vector machines) to simulated data from Genetic Analysis Workshop 19 and compare performance to logistic regression. Method performance was not radically …

Strain Energy Absorption Corresponds To Decreased Incidence Of Ventricular Fibrillation In A Commotio Cordis Model, Kayt E. Frisch, Mark S. Link, John Van Weelden

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A healthy teenage boy is playing high school baseball, when he is struck in the chest by the ball; minutes later, his heart is experiencing ventricular fibrillation (VF) and the only way to resuscitate him is to use a defibrillator. This phenomenon, is known as Commotio Cordis (CC), and occurs as many as 20 times each year in the United States. CC most frequently occurs in sports with small balls (e.g. baseball or lacrosse) and requires a specific set of circumstances–a projectile with a certain amount of energy that impacts directly over the left ventricle of the heart during a …

Approximation Assessment Of Photocatalytic Air Cleaning Pavements, James E. Alleman, Joel K. Sikkema, Peter C. Taylor

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This paper examines an approximation method to qualitatively assess the air-cleaning performance (i.e., specifically the elimination of aerial nitrogen oxide, NO, released within vehicular exhaust) by full-scale pavements which contain photo-catalytically reactive titanium dioxide under optimal conditions. Two hypothetical road configurations were considered using this method, including both a two-lane, low traffic density (i.e., 4,000 full-day AADT) and a four-lane, moderate traffic density (i.e., 10,000 full-day AADT) design. These options were then comparatively examined on the basis of expected European Union or United States vehicular emission levels. In each case, this method’s day-time-only percentile elimination approximation results were derived using …

120 Seconds, Kari Sandouka

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Posting about living with impact from In All Things - an online hub committed to the claim that the life, death, and resurrection of Jesus Christ has implications for the entire world.

http://inallthings.org/120-seconds/

Photocatalytic Concrete Pavements: Laboratory Investigation Of No Oxidation Rate Under Varied Environmental Conditions, Joel K. Sikkema, Sae-Kee Ong, James E. Alleman

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Concrete pavements containing TiO₂ can be used for air pollution control by oxidizing NO_X under UV-bearing sunlight. This study employed a bench-scale photoreactor to estimate NO oxidation rates for varied environmental conditions. Rates correlated positively with NO inlet concentration and irradiance and negatively with relative humidity. No correlation occurred with flow rate. A decrease in slab moisture (previously unstudied) positively correlated with NO oxidation rate at 0–2% loss of saturated mass, but negatively correlated at losses greater that 2%. Although prior researchers deemed temperature insignificant, data indicated a positive correlation. Overall, rates ranged from 9.8–64 nmol∙m^-2∙s …

Distinctively Christian Engineering: Implementing Guiding Principles In Our Civil Curriculum, Joel K. Sikkema, Justin Vander Werff

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At Dordt College, we work to make our motto, Soli Deo Gloria (glory to God alone), the organizing principle for all activities. In the Engineering Department, it is our responsibility to continue to shape our program to be holistic and Christ-centered in order to equip our students to serve the Lord obediently in engineering. To direct the development and modification of our engineering curriculum, we established a set of five distinctively Christian guiding principles for engineering. Setting the direction for this work required a grounding point. Therefore, in a subsequent manuscript we evaluated the extent to which these principles were …

Finding Your Path, Michael Foster, Justin Vander Werff

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Each of us has a desire to do good, fulfilling work. How do we find this work? Do we discover it or is it something we create for ourselves? If we believe there is a particular area in which we should work, then work decisions can become even more burdensome. Since there are so many areas in which we could work, and many more we may not even know about, how do we know if we have chosen the right path? These questions are particularly acute for college students. From first-year students through seniors, some aspect of their journey toward …

Sola Gratia: Grace In The Engineering Curriculum And Profession, Ethan Brue

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Integral Christian higher education is in vogue. Most Christian institutions of higher education who take their mission seriously make the claim that the education offered to students is one where faith and learning are not separate. It is a belief that their entire educational enterprise is inexorably tied in some way, shape, or form to our new life in Christ. Most engineering programs on Christian campuses are the outgrowth of this perspective. Over the last fifty years, numerous philosophers, writers, scientists, and engineers have developed a solid foundation from which engineering can be understood as an essential calling in the …

Girder Load Distribution For Seismic Design Of Integral Bridges, Justin Vander Werff, Sri Sritharan

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Current seismic design practice related to integral bridge girder-to-cap beam connections allows little or no lateral seismic load to be distributed beyond the girders immediately adjacent to the column. However, distribution results from several large-scale tests have shown that the distribution of column seismic moment typically engages all the girders. An approach utilizing simple stiffness models to predict distribution in integral bridge structures is presented in detail; distribution predictions based on grillage analyses also are compared. The experimental results and the analytical results from the stiffness and grillage models show that current design methods related to vertical load distribution are …

Seismic Performance Of Precast Girder-To-Cap Beam Connections Designed For Abc, Sri Sritharan, Justin Vander Werff, Robert Peggar, Ron Bromenschenkel

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The behavior of critical connections between prefabricated elements in bridges utilizing accelerated bridge construction (ABC) methods continues to be of utmost interest. Some of these connections will experience excessively high demand in regions that are susceptible to high seismic load. This paper presents a large-scale experimental study that investigated seismic performance of the connection between precast concrete I-shaped girders and a concrete inverted-tee cap beam using two different details. The ability of the girder-to-cap connection to successfully resist positive moment and the corresponding shear under combined gravity and seismic effects was of particular interest. The effect of vertical seismic acceleration …

Using Design Hierarchy In A Linear Circuits Class To Illustrate The Scientific Method As A Human Invention, Douglas Deboer

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There are various ways to classify academic studies. One might make a “two cultures” division, separating academic studies into the humanities and sciences. Or one might have three divisions: humanities, social sciences, and natural sciences. Or one might choose to classify academic studies along the lines of traditional academic disciplines such as theology, law, art, music, economics, social studies, languages, political studies, history, psychology, biology, physics, chemistry, math, etc. In our era of global commerce, where does engineering fit in these types of classification? What should engineers study? In a 2008 presidential debate, candidate Barack Obama said that, “Ensuring that …

To Engage Creation, Joel K. Sikkema, Justin Vander Werff

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"An engineer's role in this service is to use science and technology to care for the entirety of creation - humans, other creatures, and the natural environment - in a way that both develops its potential and ensures that our activities do not impair its ability to flourish in the future."

Posting about ­­­­­­­­a Christian perspective on engineering from In All Things - an online hub committed to the claim that the life, death, and resurrection of Jesus Christ has implications for the entire world.

http://inallthings.org/to-engage-creation/

Integral Precast Girder-To-Cap Connections For Accelerated Bridge Construction In Seismic Regions, Justin Vander Werff

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Accelerated bridge construction (ABC) is increasingly desired and needed, due to the aging transportation infrastructure across the United States and the always-growing demand placed on our nation’s highway system. Precast concrete is a common way to incorporate ABC techniques. Advantages over typical cast-in-place concrete methods include speed of field construction, improved quality control, and decrease in detoured traffic during construction, among others. However, precast concrete structures have not been used to their full potential in high seismic regions, due to the deficiency of precast concrete connections in past earthquake events. The California Department of Transportation (Caltrans) is eager to incorporate …

Interleukin Expression After Injury And The Effects Of Interleukin-1 Receptor Antagonist, Connie S. Chamberlain, Ellen M. Leiferman, Kayt E. Frisch, Stacey L. Brickson, William L. Murphy, Geoffrey S. Baer, Ray Vanderby

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Ligament healing follows a series of complex coordinated events involving various cell types, cytokines, as well as other factors, producing a mechanically inferior tissue more scar-like than native tissue. Macrophages provide an ongoing source of cytokines to modulate inflammatory cell adhesion and migration as well as fibroblast proliferation. Studying interleukins inherent to ligament healing during peak macrophage activation and angiogenesis may elucidate inflammatory mediators involved in subsequent scar formation. Herein, we used a rat healing model assayed after surgical transection of their medial collateral ligaments (MCLs). On days 3 and 7 post-injury, ligaments were collected and used for microarray analysis. …

Photocatalytic Degradation Of Nox By Concrete Pavement Containing Tio₂, Joel K. Sikkema

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Emissions from motor vehicles cause the concentrations of nitrogen oxides (NOX) in the immediate vicinity of highways to be 30-100% higher than background concentrations. Photocatalytic pavements have been proposed to address this localized pollution problem. Bench-scale evaluation of environmental variables confirmed that nitric oxide (NO) oxidation rate positively correlated with influent NO concentration and irradiance and negatively correlated with relative humidity. However, comparison of the slope of these correlations found significant differences between this study and other published work. Slab water loss, a variable not investigated in prior work, positively correlated with NO oxidation rate at water losses of 0-2% …

Carbon Conversion During Bubbling Fluidized Bed Gasification Of Biomass, Kevin Timmer

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Gasification is one means of transforming biomass so that it can be more easily utilized as a renewable source of thermal energy, transportation fuel, and chemicals. Under typical gasification conditions it is not uncommon that a portion of the carbon entering with the biomass leaves the reactor unconverted as char. Understanding and improving carbon conversion during biomass gasification in an atmospheric bubbling fluidized bed reactor is the focus of this study.

To better understand the intricacies of biomass gasification a carbon conversion analytic methodology was developed. The methodology is based on a mass balance of the fixed carbon entering and …

Methods Of Measuring The Solubility And Viscosity Of Lubricating Oil/Refrigerant Mixtures At High Discharge Pressures And Temperatures, Nolan Van Gaalen

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The design and construction of a test facility and methodology for measuring the solubility and viscosity of lubricating oil/refrigerant mixtures at high pressures and temperatures are described. An auxiliary charging system, developed to provide precisely measured quantities of oil and refrigerant to the test facility, is also presented. The test facility was developed under the sponsorship and supervision of ASHRAE which funded this research project (RP-580);The solubility, viscosity and density of mixtures of R-22 and of R-502 with commonly used 150 SUS lubricants have been measured by using this facility. Specifically, results for liquid mixtures of 10% to 40% refrigerant …