Engineering Unit Research Articles

A framework to define and quantify leadership styles within Navy engineering units

The purpose of this study was to develop a framework for the U.S. Navy's leadership styles by assessing self-perceived leadership styles in a sample of reserve Engineering Duty Officers (EDOs) and the Senior Enlisted Leaders (SELs) in these technical units. Transformational and transactional leadership styles were examined using the Multifactor Leadership Questionnaire (MLQ) Form (Avolio & Bass, 2004), while the servant leadership style was examined using the Servant Leadership Self-Assessment Questionnaire (SLSQ) (Sandling, 2021). The effect of rank and the triad leadership position had on leadership style was explored in this study. The survey was made available to all EDOs and SELs (n = 525). A total of 84 surveys were completed (a 16% return rate). Results showed that there was a statistically significant difference in servant leadership between SELs and junior officers. When broken down into the factors of servant leadership this difference was seen in the conceptual skills and putting followers first factors. No statistical differences were seen across leadership triad positions, or between any other ranks for any other leadership style. The findings are discussed for their implications for leadership development in the U.S. Navy.

Subsurface imaging dataset acquired at the Garner Valley Downhole Array site using a dense network of three-component nodal stations

There is a growing need to characterize the engineering material properties of the shallow subsurface in three dimensions for advanced engineering analyses. However, imaging the near-surface in three dimensions at spatial resolutions required for such purposes remains in its infancy and requires further study before it can be adopted into practice. To enable and accelerate research in this area, we present a large subsurface imaging data set acquired using a dense network of three-component (3C) nodal stations acquired in 2019 at the Garner Valley Downhole Array (GVDA) site. Acquisition of this data set involved the deployment of 196 stations positioned on a 14 × 14 grid with a 5 m spacing. The array was used to acquire active-source data generated by a vibroseis truck and an instrumented sledgehammer, and passive-wavefield data containing ambient noise. The active-source acquisition included 66 vibroseis and 209 instrumented sledgehammer source locations. Multiple source impacts were recorded at each source location to enable stacking of the recorded signals. The active-source recordings are provided in terms of both raw, uncorrected units of counts and corrected engineering units of meters per second. For each source impact, the force output from the vibroseis or instrumented sledgehammer was recorded and is provided in both raw counts and engineering units of kilonewtons. The passive-wavefield data include 28 h of ambient noise recorded over two nighttime deployments. The data set is shown to be useful for active-source and passive-wavefield three-dimensional imaging and other subsurface characterization techniques, which include horizontal-to-vertical spectral ratios (HVSRs), multichannel analysis of surface waves (MASW), and microtremor array measurements (MAM).

University-industry collaboration as a driver of digital transformation: Types, benefits and enablers

University-Industry collaboration as a driver of digital transformation ultimately depends on the engagement and relationship between individual academics and industry practitioners as partners in a trust relationship. This paper describes the personal (‘lived’) experiences of academics and industry practitioners. The types, benefits, and enablers of the collaboration were investigated during semi-structured face-to-face interviews with industry partners and academic staff from the Science, Technology, Engineering and Mathematics (STEM) unit at the University of Enterprise in Australia. The types of collaboration included research activities, sharing facilities and equipment, innovation and commercialisation, collaboration involving students projects, collaborative teaching and learning, and sharing facilities and equipment. The benefits of the collaboration include access to valuable resources, validation of work, learning and teaching opportunities, financial benefits, improved reputation and career progression. The enablers of collaboration have been clustered into institutional, output, framework, and relationship factors. In this paper we focus on relationship factors and institutional enablers such as stakeholder engagement. The research is represented in a UA-IP Collaboration Model indicating the types (what), benefits (why), and enablers (how) of academic-practitioner collaboration. Universities and businesses from a variety of industries can benefit from the results of the presented research.

METHODS FOR CALCULATING THE THERMAL AND STRESS-STRAIN CONDITIONS OF THE MAIN COMBUSTION CHAMBERS FLAME TUBES

Large-scale russian aggression has created a number of new and critical challenges in the field of security and defense. The growing number of emerging tasks, and at the same time the need for greater efficiency in solving them, determine the need to update and implement rational ways to maintain the serviceability of the required number of aircraft, taking into account their own and international experience.
 Thus, the development of a scientific and methodological apparatus for modeling physical processes that occur in resource-limiting parts and assembly units of aircraft engines, regarding their impact on the durability of the material in the process of operating factors, is an urgent scientific task. At the same time, it is taken into account that absolutely every engine loading cycle during flight or ground testing corresponds to a certain proportion of damage to its components, which determines a certain quantitative measure of their exhaustion of the resource.
 The article proposes a methodology for calculating the thermal stress-strain states of the flame tubes of the main combustion chambers. The objectivity and accuracy of the calculations is determined by the reliability of the boundary conditions required to solve the non-stationary thermal conductivity equation. The proposed technique allows to take into account the distribution of temperature fields obtained due to numerical modeling of the working process in the main modes of engine operation.

‘We’re supposed to be at the forefront’: a multiple case study exploring how institutional context shapes engineering diversity and inclusion initiatives

Research suggests the normative culture of engineering perpetuates the marginalization of individuals with excluded identities, contributing to a lack of diversity in academia and the workforce. As evidenced by recent funding opportunities, stakeholders view diversity and inclusion (D&I) as critical to broadening participation, and many engineering units have espoused their commitment to D&I efforts. However, additional research is needed to better understand how institutional contexts shape D&I efforts occurring in academic engineering units. This multiple case study examined engineering units at three U.S. universities that received the same National Science Foundation grant to cultivate an inclusive engineering culture. Drawing from the field of organizational theory, I analyzed data from 11 interviews and 209 pages of documents to understand how university context shaped engineering D&I efforts. The theory of neoinstitutionalism was used as a lens to understand similarities and differences among the cases. Findings suggest D&I efforts were heavily shaped by institutional contexts including the desire for prestige, availability of resources, and pressure from internal and external stakeholders. Implications for policymakers, funding agencies, and engineering leaders point to the need to re-imagine markers of engineering education legitimacy.

Fault Prognosis of Turbofan Engines

In the era of industrial big data, prognostics and health management is essential to improve the prediction of future failures to minimize inventory, maintenance, and human costs. Used for the 2021 PHM Data Challenge, the new Commercial Modular Aero-Propulsion System Simulation dataset from NASA is an open-source benchmark containing simulated turbofan engine units flown under realistic flight conditions. Deep learning approaches implemented previously for this application attempt to predict the remaining useful life of the engine units, but have not utilized labeled failure mode information, impeding practical usage and explainability. To address these limitations, a new prognostics approach is formulated with a customized loss function to simultaneously predict the current health state, the eventual failing component(s), and the remaining useful life. The proposed method incorporates principal component analysis to orthogonalize statistical time-domain features, which are inputs into supervised regressors such as random forests, extreme random forests, XGBoost, and artificial neural networks. The highest performing algorithm, ANN–Flux with PCA augmentation, achieves AUROC and AUPR scores exceeding 0.94 for each classification on average. In addition to predicting eventual failures with high accuracy, ANN–Flux achieves comparable remaining useful life RMSE for the same test split of the dataset when benchmarked against past work, with significantly less computational cost.

Preparation and electrochemical performance of FG/SnS2 composite as a cathode material for high power thermal batteries

SnS2 is a promising cathode material for its high specific capacity (1232 mAh/g), but it’s limited to the low decomposition temperature and conductivity as the thermal battery application. Herein, the flaky graphite(FG) coating SnS2 composite (denoted as FG/SnS2) with excellent thermal stability and conductivity was prepared. Then, as a thermal battery cathode material, it presented longer working time at current constant density of 100 mA/cm2, and higher pulse voltage at 2A/cm2 pulse current density than the pure SnS2. Application as the engineering unit thermal battery, its performance of higher working voltage, lower total resistance, and more stable output capacity indicated it can be used for high-power thermal batteries.

Breccia for Diversion Tunnel Construction at Bener DAM in Purworejo, Central Java, Indonesia: Fragments, Matrix, RMR

This study aimed to explain the detailed engineering geology investigation which has breccia geological units on Diversion Tunnel at Bener Dam, Purworejo Regency, Central Java Province. The investigation includes geological conditions both breccia fragment and matrix, to Rock Mass Rating (RMR) values each unit. The data were taken from face mapping tunnel with interval 10 meters at inlet 1-390 and 841-865 meters. The findings showed that geological engineering units consisted of Monomict Breccia. The geological units can be divided into geological engineering; Monomict Breccia Matrix (RMR 72-92), Polymict Breccia Matrix (RMR 82), Andesite Fragmen (RMR 52-62), and Tuff Fragmen (RMR 79-84). The discovery of Andesite and Tuff Fragments needs to be handled differently than Monomict Breccia or Polymict Breccia. Andesite Fragment unit with discontinuity of sheeting joint requires rock bolt reinforcement to be installed perpendicular to the discontinuity plane. While the dominant unit is the Tuff Fragment which has a UCS value of 5-7 MPa, it is not recommended to use the blasting excavation method even though it has an RMR value of 79-84.

Structural optimization of resonance tubes for a looped thermoacoustic engine with multiple heat sources

The advantage of coupling different heat sources with each thermoacoustic core unit in a three-stage looped traveling-wave thermoacoustic system is used to solve the application problem of multiple waste heat sources. The effects of the heat-side heat exchanger temperature, the resonance tube radius and length, and their interaction terms on the thermoacoustic thermodynamic properties are analyzed using response surface methodology on the premise that thermoacoustic core structures remain unchanged. The results indicate that prediction deviations for acoustic power, thermoacoustic conversion efficiency, and relative Carnot efficiency are within ±9%, ±3%, and ±3%, respectively. The acoustic power can be improved by increasing the hot-side heat exchanger temperature and the resonance tube radius. Under the same heat source conditions, the acoustic power, thermoacoustic conversion efficiency, and relative Carnot efficiency of the optimized thermoacoustic system show the highest increases of 49.63%, 4.82%, and 3.20%, respectively, compared to the non-optimized thermoacoustic system. The optimized variable-temperature system not only has higher thermodynamic efficiency compared with the optimized constant-temperature system but also can realize the complementary regulation among the thermoacoustic engine units by matching decreasing-gradient variable temperature and increasing-gradient variable radii and effectively broaden the working temperature range of the looped thermoacoustic system.

Assessment of Reliability and Technical Risks in the Operation of Heat Engineering Units

Assessment of Reliability and Technical Risks in the Operation of Heat Engineering Units

To the method of calculation of the main characteristics of promising booster electric pump units of liquid processor engines

The increase in the capacity of electric power sources, the use of electric motors in the systems for supplying rocket fuel components from foreign companies, the limitations on the power of classical fuel supply systems all these conditions set a trend for studying the possibility of introducing electric drives for rocket engine power systems. The study is devoted to the analysis of the possibility of using electric motors as a drive for the main and auxiliary pumps of liquid rocket engines. Promising developments in the field of rechargeable batteries give grounds for a mathematical justification for the use of this technical solution in order to modernize power systems, both existing rocket engines and samples under development. The article presents a selection of patents for modern technologies for creating high-capacity batteries, an analysis of the use of technology for the use of electric motors in the international market for delivering payloads to orbits, and a rationale for the prospects of this direction in the development of rocket engines. The statistics of the causes of failures of upper stages and their correlation with units, which can be replaced by more reliable systems using electric motors, have been studied. The advantages and disadvantages of power supply systems with the use of electric drives are determined. This study allows us to conclude that the use of electric motors in rocket engine power systems is a promising solution that improves the efficiency of the propulsion system, performance and reliability.

Assessment of reliability and technical risks in the operation of heat engineering units

Приведен способ оценки технических рисков, возникающих при работе теплотехнических агрегатов. Оценка рисков производится на основе данных об остаточном ресурсе футеровки агрегата и оценки степени тяжести последствий аварии. Для получения первичных данных при оценке остаточного ресурса применяется приборный метод, который позволяет вести непрерывный мониторинг теплового состояния футеровки. При этом определяющий фактор разрушения ― термомеханические напряжения, превышающие предел прочности материала, которые рассчитываются по разработанной схеме на основе численных методов.

A Review on the Adsorption Isotherms and Design Calculations for the Optimization of Adsorbent Mass and Contact Time.

Adsorption is a widely used chemical engineering unit operation for the separation and purification of fluid streams. Typical uses of adsorption include the removal of targeted pollutants like antibiotics, dyes, heavy metals, and other small to large molecules from aqueous solutions or wastewater. To date several adsorbents that vary in terms of their physicochemical properties and costs have been tested for their efficacy to remove these pollutants from wastewater. Irrespective of the type of adsorbent, nature of the pollutant, or experimental conditions, the overall cost of adsorption depends directly on the adsorption contact time and the cost of the adsorbent materials. Thus, it is essential to minimize the amount of adsorbent and the contact time required. We carefully reviewed the attempts made by several researchers to minimize these two parameters using theoretical adsorption kinetics and isotherms. We also clearly explained the theoretical methods and the calculation procedures involved during the optimization of the adsorbent mass and the contact time. To complement the theoretical calculation procedures, we also made a detailed review on the theoretical adsorption isotherms that are commonly used to model experimental equilibrium data that can be used to optimize the adsorbent mass.

Климент Александрович Звонарев – выдающийся советский маркшейдер, геодезист, картограф

The article is devoted to the famous scientist-surveyor, mining engineer and cartographer, a captain of the geodetic detachment, Kliment Aleksandrovich Zvonarev (1902–1986). K. A. Zvonarev went from a student of the Leningrad Mining Institute (graduated in 1928) to Doctor of Technology (1953) and professor (1954). From 1929 to 1957 he taught at the Leningrad Mining Institute (since 1935 – associate professor, since 1954 – professor), in the period of 1957–1978 he headed the Department of Cartography in Leningrad State University. Participant of the Great Patriotic War of 1941–1945. He served in the engineering units of the Leningrad, Volkhov and Karelian fronts as the topographic department head’s assistant, military engineer and engineer-captain of the geodetic service. He was awarded the Order of the Red Star (1942), Badge of Honor (1948), medals For the Defense of Leningrad (1943), For the Victory over Germany (1946), For Labor Valor (1950), In Memory of the 250th Anniversary of Leningrad (1957), 20 years of Victory in the Great Patriotic War (1966). The authors provide information on working, the main scientific achievements and recollections by Kliment Alexandrovich about his participation in battles.

Theoretical analysis of a direct-coupled Stirling combined cooling and power system for heat recovery

The Stirling CCP (combined cooling and power) technology is an effective way to realize cooling and power cogeneration, but it still faces problems of complicated structure and large vibration. To relieve these issues, in this work, a direct-coupled Stirling CCP system with a simple structure is proposed and analyzed through the aid of a verified numerical model. In such a system, a thermal buffer tube is used to couple the engine unit and the refrigeration unit so that only two pistons are employed. To investigate the influence of varying working conditions, the output characteristics with different external resistances and operating temperatures are analyzed. In the optimal case, the system can provide a cooling capacity of 4042 W and an electricity power of 467.4 W with an exergy efficiency of 27.6%, when the heating, ambient and cooling temperatures are 300 °C, 30 °C and 10 °C, respectively. The results demonstrate that, compared with the conventional Stirling CCP systems, the presented system not only has a simpler structure, but also possesses superiority in both volumetric specific electricity power and exergy efficiency, which indicates its potential for cooling and power cogeneration driven by waste heat.

The Effectiveness of Students’ Use of Computer Modeling in Learning Engineering Mathematics

The aim of this study is to explore the effectiveness of teaching mathematics using computer modeling. It was conducted for a five-grade engineering unit by modeling concepts, terminology, and issues related to engineering in collaboration between groups of students and teachers from several primary schools. in Amman, Jordan, in the academic year 2021/2022. The working group consisted of thirty students. An action research model was used to conduct this study. Photographs, videos, teacher records, graded grading model, focus group discussions, and researcher's record were used to collect data. Through percentage statistics and content analysis, the obtained qualitative data were analyzed. And concluded that the positive impact of students' use of computer modeling in learning aeronautical engineering mathematics and motivating students towards studying mathematics and increasing study skills and the ability to represent and model to clarify any issue in mathematics in space engineering.

ВИКОРИСТАННЯ ПІДШИПНИКІВ КОВЗАННЯ У АВІАЦІЙНІЙ ТА КОСМІЧНОЇ ТЕХНІЦІ

Examples and prospects of various types of sliding bearings applications in power elements of aircraft engines and in turbopump units (TPU) of liquid propellant rocket engines (LPRE) are discussed in this article.In the second half of the last century, piston aircraft engines were replaced by turboprop (TPE) and turbojet (TJE) engines. Almost all leading manufacturers of these motors use rolling bearings as rotor supports for the main power units. The use of sliding bearings is extremely rare and is the exception rather than the rule. These exceptions include the company Pratt & Whitney, which has been using sliding bearings since the 1950s (engine PT6A). The sliding bearings are also used in modern turbofan engines Pratt & Whitney PW1000G series. The use of sliding bearings as a support for planetary gearbox elements has a number of advantages over rolling bearings, since under normal operating conditions such supports have a significantly longer service life.In rocketry, sliding bearings are used as supports for a LPRE TPU. Examples of such supports are hydrodynamic sliding bearings of the first German missiles during the Second World War (one of them was the FAU-2) and Soviet missiles developed by S.P. Korolev and V.P. Glushko. As our analysis has shown, in the 50s the use of sliding bearings in LPRE was abandoned due to a number of advantages of rolling bearings over sliding bearings, especially taking into account the very short service life of these engines (hundreds of seconds). Recently, however, sliding bearings as supports for a TPU have been attracting more attention again due to the development of reusable missile systems with a sharp increase in required service life. Although the results achieved for TPU with rolling bearings still provide the required durability, studies of the sliding bearings for TPU design with increased service life are relevant.The data obtained as the result of the analysis describe existing practice of using sliding bearings in units of aircraft and rocket engines, as well as the prospects for their further use.

School Personnel Lived Experiences Related to High School Engineering Education and the Covid-19 Pandemic

This study investigated the teaching experiences of three school personnel at a public high school during the 2020–2021 school year as they implemented a unique science, technology, engineering, arts, and math (STEAM) unit with in-person and virtual students in their engineering classes during the Covid-19 pandemic. A research team interviewed two teachers and one administrator at the school to better understand the nuances of pre-college engineering during a pandemic year and how changes in school and district policy affected the instructional delivery of STEAM projects. Narrative analytic methods were utilized to understand each participant’s experience and an inductive content thematic approach was used to develop the findings. The participants described varied experiences navigating instruction during the pandemic, particularly when adapting hands-on STEAM projects for virtual or hybrid teaching. All three participants thought deeply about how to best meet the needs of students while attempting to support equitable instruction. The findings of this study indicate that pre-college engineering in the pandemic was challenging for the participants, but not impossible, and that this setting was an appropriate context for STEAM projects that provided students with a mechanism for collaboration and engagement.

A comparison of elementary teachers' verbal supports for students in inclusive and general classroom contexts during an NGSS‐aligned science, engineering, and computer science unit

AbstractElementary teachers are tasked with the challenge of implementing Next Generation Science Standards‐aligned projects that integrate science, technology, engineering, mathematics, and computer science (STEM + CS) in a variety of classroom contexts. This study investigates how teachers verbally support students in two classrooms, one general education class and one inclusive class with a larger proportion of students with individualized educational plans, to engage in a Next Generation Science Standards‐aligned, STEM + CS unit. Teachers' verbal support for students to understand how (pragmatic) and when and why (epistemic) to use practices was examined during whole‐class discussions for a 4‐week unit in science, engineering, and computer science‐focused lessons. Bi‐weekly teacher surveys and weekly teacher interviews provided insight into the teachers' perceptions of students and project activities in each class section. Teachers reported instructional decisions to modify their enactment of the interdisciplinary curricular materials for the Inclusive Class and discussed their rationales for these modifications. Results suggest that instructional decisions that teachers made in how to verbally support students may depend upon their own knowledge of the different disciplines being integrated, their prior beliefs of students in different classroom contexts, and their in‐the‐moment perceptions of student needs. These factors may have led to different learning experiences for the students in each class section. Findings underscore the need for more research to better understand what kinds of support students and teachers need to be able to integrate engineering, science, and computer science content and practices within their elementary classrooms and provide equitable learning opportunities for all students.

Transplantation of adipose tissue-derived microvascular fragments promotes therapy of critical limb ischemia

BackgroundAdipose tissue-derived microvascular fragments are functional vessel segments derived from arterioles, capillaries, and veins. Microvascular fragments can be used as vascularization units in regenerative medicine and tissue engineering containing microvascular networks. However, the in vivo therapeutic and vascularization properties of human microvascular fragments have not been investigated.MethodsIn this study, we isolated microvascular fragments, stromal vascular fractions, and mesenchymal stem cells from human lipoaspirate and studied their therapeutic efficacy and in vivo vasculogenic activity in a murine model of hindlimb ischemia. In addition, in vivo angiogenic activity and engraftment of microvascular fragments into blood vessels were measured using Matrigel plug assay.ResultsBoth microvascular fragments and stromal vascular fractions contain not only mesenchymal stem cells but also endothelial progenitor cells. In a Matrigel plug assay, microvascular fragments increased the number of blood vessels containing red blood cells more than mesenchymal stem cells and stromal vascular fractions did. The engraftment of the microvascular fragments transplanted in blood vessels within the Matrigel plug significantly increased compared to the engraftment of mesenchymal stem cells and stromal vascular fractions. Moreover, intramuscular injection of microvascular fragments markedly increased blood flow in the ischemic hindlimbs and alleviated tissue necrosis compared to that of mesenchymal stem cells or stromal vascular fractions. Furthermore, transplanted microvascular fragments formed new blood vessels in ischemic limbs.ConclusionsThese results suggest that microvascular fragments show improved engraftment efficiency and vasculogenic activity in vivo and are highly useful for treating ischemic diseases and in tissue engineering.Graphical Adipose tissue-derived microvascular fragments are vascularization units in regenerative medicine and tissue engineering containing microvascular networks. Intramuscular injection of microvascular fragments markedly increased blood flow in the ischemic hindlimbs and alleviated tissue necrosis. The present study suggests that microvascular fragments show improved engraftment efficiency and vasculogenic activity in vivo and are highly useful for treating ischemic diseases and in tissue engineering.