Ten Lessons Learned About Host Nation Construction in Afghanistan

This article presents the 10 lessons learned about Host-Nation construction in Afghanistan. Here are the lessons: 1. The Process for New Construction Was Straightforward but Took Time. 2. Afghan Companies Often Would Mislead Them to Get a Contract. 3. Ownership of Afghan Construction Companies Was Often Obscure and Dubious. 4. Afghan Lifestyle Meant Timelines Had to Be Flexible. 5. The Bulk of the Construction Material Came from Russia. 6. Afghans Have Experience with Concrete but Typically of Dubious Quality. 7. Afghan Carpentry Had to Be Closely Monitored. 8. Afghan Electrical Work Did Not Meet American Standards. 9. Afghan Plumbing Work Did Not Meet American Standards. 10. Safety Standards Are Fairly Lax on Afghan Job Sites

Distribution of Knock Frewquencies in Modern Engines Compared to Historical Data

It is widely known that the rapid autoignition of end-gas will cause an engine cylinder to resonate, creating a knocking sound. These effects were quantified for a simple engine geometry in 1934 in a study where critical resonance frequencies were identified. That analysis, performed by Charles Draper, still forms the basis of most knock studies. However, the resonance frequencies are highly dependent on the engine geometry and the conditions inside the cylinder at autoignition. Since, engines and fuels operate at substantially different conditions than they did in 1934, it is expected that there should be a shift in knock frequencies. Experimental tests were run to collect knock data in an engine, representative of modern geometries, over a range of operating conditions for a number of different fuels. The operating conditions—intake air temperature, intake air pressure, and engine speed—were varied to identify shifts in the critical frequencies. Additionally, fuels were varied in octane number from 80 to 100. The resulting analysis found that the first circumferential mode, at approximately 6 kHz still played a substantial role in knock in modern engines. However, the analysis also found a decreased contribution from radial modes and an increased contribution from the axial modes. The distributions of frequencies did not shift significantly for changes in the intake air temperature or pressure; however, the axial modes became more significant at higher engine speeds. Additionally, the axial modes increase in frequency for higher octane fuels, which have an earlier knock-limited spark advance. These results show the increased importance of the axial modes in knock for modern engines; these modes are typically not audible, though they can still result in engine damage

The Use of Stochastic Value Models to Create Technology Roadmaps

Since technology is rapidly advancing, systems engineers must now design for adaptability, such that the system can be updated with new components as they become available. Designing for adaptability typically requires analyzing and evaluating technologies at various stages of maturity to determine if they should be incorporated into the design. As such, technology roadmaps are a useful tool to identifying the change in a technology with time. Though traditional technology roadmaps are based on raw performance data, a technology roadmap based on value modeling would be more appropriate for system design. Value modeling is a technique used for evaluating different design decisions while focusing on the needs of the stakeholder. A qualitative model is built to determine what value measures are of concern to the stakeholder; a quantitative model is then built to convert raw performance data into a value score for evaluation. This process can be expanded to show the change in value score based on new technologies through the inclusion of uncertainty and the time domain. The SIPMath® Tool is Microsoft Excel provided a useful tool for building this model. A case study for different unmanned aerial vehicle batteries is presented to display this proces

Design Parameters for Small Engines based on Market Research

Small internal combustion engines outperform batteries and fuel cells in regards to weight for a range of applications, including consumer products, marine vehicles, small manned ground vehicles, unmanned vehicles, and generators. The power ranges for these applications are typically between 1 kW and 10 kW. There are numerous technical challenges associated with engines producing power in this range resulting in low power density and high specific fuel consumption. As such, there is a large range of engine design solutions that are commercially available in this power range to overcome these technical challenges. A market survey was conducted of commercially available engines with power outputs less than 10 kW. The subsequent analysis highlights the trade-offs between power output, engine weight, and specific fuel consumption. These engines are analyzed to show the benefits and disadvantages of different engine design parameters including fuel type, number of strokes per cycle, number of cylinders, intake pressure, and cooling strategy. A Pareto frontier analysis is conducted to identify the top performing engines based on the output power and the total power system weight. Recommended designs are presented for different ranges of output powers

Bridging Systems Engineering Theory and Application in Undergraduate Curricula

Systems engineering undergraduate curricula are typically divided into foundational, methodology, and application courses. The United States Military Academy, Systems Engineering program primary application course, often referred to as a Capstone project, involves teams of students performing client-based work to solve complex real-world problems. Existing foundational and methodology courses tend to emphasize engineering management processes and operations research techniques at the expense of systems engineering technical processes. As such, students often do not have the requisite knowledge base necessary for their Capstone, reducing their self-efficiency, decision-making, overall project interest, and quality of technical artifacts. In an attempt to bridge this gap, the United States Military Academy, Systems Engineering program introduced a cornerstone course to teach system engineering design and system engineering technical processes as practiced in industry and documented in the INCOSE handbook. The course structure follows the system engineering V methodology and uses a realistic, but constrained, design project to teach and apply systems engineering skills. The introduction of this new course was found to increase the overall knowledge-base of the students entering their Capstone project, allowing them to be more self-efficient and capable of making informed engineering design decisions

Teaching Modeling to Engineers in an Undergraduate Simulation Course

A significant challenge in teaching simulation to undergraduate students is to find a way to allow them to model a real world referent system within time and student skill constraints. Several research sources highlight not only the important challenge of model development (Garcia and Ceneno, 2009, Tako, 2011) but also the increased need for model development instruction among engineers (Grasas et. al., 2013, Saltzman and Roeder, 2013). One approach to this challenge is to use a general purpose discrete event simulation software package within the course, but this presents two challenges. Teaching the package to the students takes significant time, and the package introduces limitations which may restrict their ability to model certain real-world referents, particularly in the engineering domain. A conceptual approach to solving this problem is to use a model development paradigm that abstracts away the interface to the simulation infrastructure while still allowing the students to use the full expressive nature of a programming language. Two undergraduate courses at the United States Military Academy employed this strategy via the Discrete Events Specification System – Distributed Modeling Framework (DEVS-DMF) (Kewley et. al, 2016). The DEVS abstraction allowed students to think about their model as a simple state change function with defined inputs and outputs, and DMF allowed them to program in a cloud-based Jupyter Notebook using the Python language. Students in a combat modeling course employed a variety of models to understand drone jamming, and students in an engineering capstone project employed models to account for human factors in rifle marksmanship. The effectiveness of this approach was assessed through student grades, exit-interviews, and course-end surveys. These assessments showed an increased understanding of the model development process, and students also reported greater ownership of their models. However, this experiment also highlighted some weaknesses in their understanding of underlying methodologies and programming skills

A study of the physics and chemistry of knock in modern SI engines and their relationship to the octane tests

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.Cataloged from PDF version of thesis.Includes bibliographical references (p. 147-150).Avoiding knock is the major design constraint for spark ignition engines because of the unacceptable noise and engine damage associated with it. Hence, the Research and Motor Octane Number (RON and MON) tests were established in 1928 such that a fuel with a higher RON and MON is less likely to knock than a fuel with a lower value. However, engine and fuel technology has evolved since 1928, and thus the relevancy of these tests for modem engines needed to be evaluated. First, the study compared knock onset, knock metrics, reference fuels, and test conditions for the octane tests to those in modem engines. The results showed that in modem engines, for a given RON, fuels with lower MON values performed better than fuels with higher values, and this trend becomes stronger when engines are boosted and intercooled. Second, detailed chemical kinetics models were used to study fuel autoignition phenomena leading to knocking conditions. These models showed that the fuel autoignition chemistry in modem engine is different from that in the RON and MON tests. Based on these results, it was concluded that the RON and MON tests no longer represent modem engine operating conditions; therefore, modifications are suggested and evaluated to improve the tests' applicability.by Vikram Mittal.Ph.D

Potential for Army Integration of Autonomous Systems by Warfighting Function

The article explains the maximum extent that the U.S. Army can integrate autonomous systems into its operations given the inherent limitations of the technology. Topics include these limitations determine the appropriateness of using autonomous systems to perform each of the broad range of Army tasks that are captured through the warfighter functions and the six warfighting functions of the U.S. Army include mission command, intelligence and protection

Avoiding Pitfalls in Undergraduate Simulation Courses

Simulation development has historically been a specialized skill performed by engineers with graduate-level training and industry experience. However, advances in computing technology, coupled with the rise of model-based systems engineering, have dramatically increased the usage of simulations, such that most engineers now require a working knowledge of modeling and simulation (M&S). As such, an increasing number of undergraduate engineering programs are now requiring students to complete a simulation course. These courses are intended to reinforce foundational engineering knowledge while also teaching the students useful M&S tools that they will need in industry. Yet, a number of pitfalls are associated with teaching M&S to undergraduate students. The first major pitfall is focusing on the tool or software without properly teaching the underlying methodologies. This pitfall can result in students becoming fixated on the software, limiting their broader knowledge of M&S. The second pitfall involves the use of contrived, academic tutorials as course projects, which limits students from fully understanding the simulation design process. The third and fourth pitfalls are only superficially covering verification and validation and not building upon material that was taught in other courses. Finally, the fifth pitfall is the over-reliance on group projects and tests over individual projects. These pitfalls were uncovered during academic years (AYs) 2017 and 2018 in different undergraduate simulation courses at the United States Military Academy. The combat modeling course adapted its structure and content in AY2019 to address these pitfalls, with several lessons learned that are applicable to the broader simulation education community. Generally, students gained a broader understanding of M&S and submitted higher quality work. Additionally, the course-end feedback found an overall increase in M&S knowledge, with many students choosing to use M&S to support their honors theses and capstone projects, a trend not seen in past years